Modern Mechanix, August 1937

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AUGUST CATION А FAWCETT PUBL o E 2 2 A _ 28 o б o Е o uc. 1937 ME

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GRANTLAND RICE REPORTS: HE STRAINS of “When We Come To The End of A Perfect Day” seemed to fit the mood of Mr. Jack Davis of Seattle, Washington, and his party of four, as they motored down from Mt. Baker that Sunday afternoon, And when the familiar Everett highway finally was reached, they were still recounting the ex- periences of that care-free week-end. Then, with startling suddenness, the scene changed. BANG! The left front tire had blown out with the noise of a thunderclap! A terrible drag set in. The steering wheel jerked itself right out of Mr. Davis’ control. Down went the brakes. But too late. Off the road they shot. Blow-out Protection Why any motorist should |take chances by riding around on ordi- пагу tires is beyond me. Especially when Goodrich has perfected a tire invention that brings real blow-out protection. This revolutionary con- struction, which they call the Life- Saver Golden Ply and which is found only in Goodrich Silvertowns, is a layer of special rubber and full- floating cords, scientifically treated Goodrich SAFETY Si OFF THE ROAD THEY SHOTAS AN UNSEEN DEMON THREW BER CAR OUT OF CONTROL GRANTLAND RICE Describes The Unhappy Ending To A Seattle Motorist’s Week- End Trip To Mt. Baker to resist the terrific blowout-causing heat generated inside all tires by today’s higher speeds. By resisting this heat, the Golden Ply protects you against these high-speed blow-outs. One blow-out was enough to cure Mr. Jack Davis. Now you'll find his car equipped with Goodrich Safety Silver- towns. Make up your mind to “beat a blow-out to the punch” by starting to ride on Silvertowns today. They're on sale at Goodrich Silvertown Stores and Goodrich dealers everywhere. GRANTLAND RICE Well-known Radio Annow Sports ncer vertow With Life-Saver Golden Ply Blow-Out Protection tors Commentato and Columnist

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READ THESE 3 ИС YEUENCEA of Men | Trained at Home For RADIO Í 1 Cw HAVE MY N RADIO SINESS | D AVERAGE | | 455 TO $70 1 А WEEK. MEMES SKLAVOS 333 THIRD ST. SAN FRANCISCO CALIF f 1 АМ EMPLOYED BY A RADIO STORE, AND EARNED ABOUT $2,500 LAST YEAR. CHARLES L. TORREY #25 5 I2TH ST. SAN JOSE,CALIF. Е | = | WILL TRAIN YOU AT HOME ror a GOOD RADIO JOB Мапу Radio Ex- perts Make $30, $50,975aWeek Do you want to make more money? Broad- casting stations em- ploy engineers, oper- ators, station mane agers and pay up to 5,000 & year. Spare ime Radio set serye | icing pays as much as $200 to $500 а year —full time servicing jobs pay as much as 530, 75 а week, Many Radio Experta own their own ful time or part time Radio businesses, Radio manufacturers and jobbers employ testers, in- spectors, foremen, engineers, servicemen, paye. ing up to $6,000 à year. Radio operators on ships get good pay and see the world besides. Automobile, po- lice, aviation, commercial Radio, and loud. speaker systems offer good oppor- tunities now and for the future. Television promises many good jobs soon. Men | trained at home are hold- ing good jobs in all these branches of Radio. Many Make $5, $10, $15 a Week Extra in Their SpareTimeWhile Learning Practically every neighborhood needs а good spare fime service- J. E. SI National Radio Institute г 00 RADIO SERVICE WORK IN SPARE TIME AND AVERAGE ABOUT $12.59 A WEEK. 4. 8 МИВУ Вох 95 UTICA, MICH. AUTO RADIO AND N.R t TRAINING ARE A GOOD COMBINATION { Ам BUILDING А FINE BUSINESS, А.С HENDRIKSEN / B 125 $. MELROSE AVE А | B ELGIN, ILLINOIS Cw | The day you enroll I start sending Job Sheets, They show you how to do Radio repair jobs that you can cash in on quickly. Throughout your training I send you plans and ideas that have made good врате time money for hun- dreds of fellows. send you special equip- ment which gives you practical Radio ex- perience—shows you how to conduct experi- ments and build circuits which illustrate important principles used in modern Radio sets. My Free Book tells all about this. Find Out What Radio Offers You Mail the coupon now for "Rich Rewards in Radio.” It’s free to any fellow over 18 years old. It describes Radio’s spare time $nd full time opportunities, also those cora- ing in Television; tells about my training in Radio and Television: shows you actual letters from men I have trained, telling what they are doing aud earning; tells man, you Extra Mone \ J. E. SMITH, President Washington, D. C. Dear Mr. Smith: Without obligatin Which poiats out the spare time an explains become Radio Experts, A y ) AFTER COMPLETING TWENTY LESSONS P JOINED STATION WMPC WHERE ! AM NOW CHIEF OPERATOR. HOLLIS F. HAYES 85 MADISON ST. LAPEER, MICK. МУ LOUDSPEAKER SYSTEM PAYS ME ABOUT $35 А WEEK, BESIDES MY RADIO WORK MILTON l. LEIBY, JR, ТОРТОМ, PENNA National Radio Institute, Dept. 7HH e, send “Rich Rewards in Radio,” ful time o portunities in Radio and our 50-50 method of training men a i (Please Write Plainly.) 1 AM NOW FOREMAN OVER PRODUCTION OF RADIOS FOR THE \-----©-- CORP. OTTO CLIFFORD 312 W. SEMINARY ST. CHARLOTTE, М.С. ГАМ NOW GROUND STATION OPERATOR FOR THE AMERICAN AIRWAYS, INC. AT CINCINNATI WALTER B. MURRAY LUNKEN AIRPORT CINCINNATI, OHIO about my Money Back eement, MAIL THE COUPON iu am cavclope or paste jt on a penny postcard—NO i J. E, SMITH, President National Radio Institute, Dept. 7HH Washington, D. C. home in spare time to esu ваа 2665 АСЕ.. When Answering Advertisements Please Mention August Modern Mechanix 3

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AUGUST PRICE АЛЕ 1937 15 CENTS 7 МО ( ) Circulation over 250,000 Copyright 1937 by Modern Mechanix Publishing Со, Volume XVIII Number 4 SAME PRICE IN CANADA SPECIAL FEATURES NEXT MONTH Adventures Of The Poison Squad - - - 30 By James N. Miller Is There а Speed Limit?- - - - - - 36 By Don Glassman 36 Killed On The “Hindenburg,” But— Records Prove That Zeppelins Are Safe! - 42 By Bob Gordon Racing The Homing Pigeon- - - - - 50 In an article — "Science Builds The By W. R. Stamford Greatest Telescope"——John Edwin Hogg supplies interesting details concerning the gigantic 200-inch telescope being con- structed for astronomical observations to С Н be made from Mt. Palomar, Calif. The Dogs Diamond Guardians - * = Е Е 56 huge mounting for the telescope (above) is 60 feet long and has an outside diameter By Lawrence G. Green of 22 feet. Without optical parts, gears, or mirror cranes, mounting weighs 100 tons. Inventions Needed In Field Of Electrochemistry - - - - 60 By Richard H. Parke FOR WORKSHOP FANS Among the many interest- ing projects included in the September issue will be— Restocking The Ocean - - - - - - 62 "Tiny Tot" a %4-Merer Radio Receiver; A Midget By C. S. van Dresser Metal Hull Dinghy; How To Clean And Condition Fire- arms; А metal Humidor 0 : ғ. а - Pipe Rack; Making Photo- So You're Buying a House! 68 graphic Name Cards; an d И other plans, suggestions, an By Alfred Dong practical workshop kinks. [Continued on page 8] Published monthly by Modern Mechanix Publishing Co., Fawcett Bldg., Greenwich, Conn., U. S. A. Entered as second-class matter under the Act of March 3. 1879, at the post office in Greenwich, Conn., with additional entry at Louisville, Ky. Editorial offices: 1501 Broad- way, Now York, N. Y. Not responsible for unsolicited manuscripts. In U. S. and Possessions and in Canada, loc a copy; $1.50 a year. Send subscriptions to Greenwich, Conn., address. Other Postal Unions, $2.00 a year. Printed іп U. S. A. Advertising forms close the first of second month preceding date of issue. Advertising offices: New York, 1501 Broadway; Chicago, 360 М. Michigan Ave.; San Francisco, Simpson- Reilly, 1014 Russ Bldg.; Los Angeles, Simpson-Reilly, 536 S. НШ St. Member Audit Bureau of Circulalion, W. H. FAWCETT, Publisher RALPH DAIGH, Managing Editor ROBERT HERTZBERG, Editor AL ALLARD, Art Director THOMAS A. BLANCHARD, JOHN L. SCHERER, CLIFFORD PETERS, Associate Editors ROBERT PAGE LINCOLN, Hunting and Fishing Consultant S. S. RABL, Naval Consultant

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YOU CAN REPEAT ALMOST EVERY EXPERIENCE IN LIFE —EXCEPT * e Topay is life. Tomorrow is a hope. Yesterday is a dream. Nothing is so dead as a day that has passed. Only the trailing clouds of memory remain. One. today upon another today—how quickly a decade is built! Youth approaches manhood in high heart, embraces maturity as the period of his conquest, then “remembers with a sigh the days that are no more.” So life goes—like that. NOW is the only oppor- tunity. NOW is the moment of success. NOW men decide— NOW men win or fail. Are you one of the men who are wondering today what will happen to them tomorrow? Then | МТЕЕМАТ : ОМА CORRESPONDENCE BOX remember this: Jf you take care of today, tomorrow will take care of itself. And one of the most im- portant safeguards you can take is to be certain your training is modern... that you are adequately equipped to master the problems of 1937. Today, in almost every line of human endeavor, ambitious men are modernizing their training by spare-time study of International Correspondence Schools Courses. 'Their action is a guide to you — and NOW is the time to act! Complete information on any subject in which you are interested will be * sent without cost or obligation. The coupon is for your convenience. Return it today. SCHOOLS 2322-M, SCRANTON, PENNA. * Without cost or obligation, please send me a copy of your booklet, “Who Wins and * Why," and full particulars about the subject before which I have marked X: C Architect D Architectural Draftsman О Building Estimating О Contractor and Builder О Structural Draftsman О Structural Engineer O Management of Inventions O Electrical Engineer O Electric Lighting O Welding, Electric and Gas O Reading Shop Blueprints О Heat Treatment of Metals Business Management D Industrial Management О Trafic Management O Accountancy О Cost Accountant Li C. P. Accountant О Home Dressmaking О Professional Dressmaking and Designing TECHNICAL AND INDUSTRIAL COURSES О Sheet Metal Worker О Plumbing О Steam Fitting D Boilermaker О Ileating O Ventilation Telegraph Engineer О Air Conditioning О Telephone Work О Radio O Steam Engineer G Mechanical Engineering O Steam Electric Engineer Mechanical Draftsman О Marine Engineer О Machinist OToolmaker OR. К. Locomotives О Patternmaker > OR. R. Section Foreman D Diesel Engines С Air Brakes О R. R. Signalmen О Aviation Engines С Highway Engineering O Automobile Mechanic О Civil Engineering О Refrigeration O Surveying and Mapping BUSINESS TRAINING COURSES C] Service Station Saleemanship С First Year College Subjects. D Business Correspondence О Stenography and Typing D Civil Service О Mail Carrier О Railway Mail Clerk DOMESTIC SCIENCE COURSES О Advanced Dresemaking G Millinery О Bookkeeping O Secretarial Work D Spanish О French О Salesmanship О Advertising po m———— РОИ A 2 PET |.) City... it you reside in Canada, State... & this coupon to e International О Bridge Engineer О Bridge and Building Foreman О Chemistry O Pharmacy O Coal Mining О Mine Foreman О Navigation U Cotton Manufacturing О Woolen Manufacturing O Agriculture D Fruit Growing О Poultry Farming О Fire Bosses О Grade School Subjecta D High School Subiecta О College Preparatory О Illustrating O Cartooning G Lettering Show Cards О Signs O Foods and Cookery O Tea Room and Cafeteria Management, Catering — marnma „Present Position.. When Answering Advertisements Please Mention August Modern Mechanix

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A frank PATENTS -| HE world of invention moves on. About a hundred years ago people were saying, *There’s nothing left to invent"—today we know that is one of the funniest things ever said. Just think what has happened in the last hundred years! Autos, radios, airplanes, and thousands of useful, practical devices for home, shop and office have been invented and put on the market. Inventors are con- stantly making the world a better place to live in. Did you see a notice in the paper that an obscure worker, Hans Wach, has invented a simple device to utilize exhaust steam on steam boats. Already, the report states, the steam ship lines have saved more than $15,000 in fuel bills with his invention. Almost in the same breath the Dept. of Commerce announces that it will soon test out a new non- crashable aeroplane, which the average man can learn to fly in a day, which will travel at 110 miles an hour and sell at the price of a cheap automobile. An unknown Seattle man has invented a robot to go 5,000 feet under the sea and recover millions and man to millions of dollars worth of gold lying at the bottom of the ocean since the days of the early Spaniards, Remember this: For every outstanding big inven- tion there are thousands of small, simple things for use in the home, the office, the factory, on the farm, on every sort of travel conveyance. Little articles like you find on the counters of a 10-cent store, hardware store, drug store, toy and novelty shop. Many Little Ideas Have Big Commercial Possibilities A person finds something he’s using doesn’t work right, or it’s clumsy, or costs too much. He gets a happy thought. He improves the old Article. That’s contribution to human progress. That’s the way that many, many men have reached the goal of financial comfort, independence and even wealth. Most of the things millions of us use didn't come from the brains of engineers and physicists. They came from the mind and maybe the crude home work bench of Mr. Average Man, busily engaged in@arning his bread and butter at whatever chance or circumstance has given him to do. The "little? man’s opportunity as an inventor was never greater than it is today. Who Are Inventors? You'd be amazed at the men we con- tact in the course of a busy year, Most of them do not consider themselves inventors at all, During their work or leisure they get an idea, They work it out on paper, They get in touch with us about Protection, Did you know that a dentist invented the stock ticker, a school teacher the telephone, a farmer the typewriter, an artist the telegraph? Did you know that the crinkly hair pin—sold by millions now—came about because a husband saw his wife twisting the old-fashioned straight hair pin to make it stay in place? Poor men who have no thought of invention now will be financially well-fixed in a few years hecause of a happy thought that the world could use to advantage, Can You Answer These Questions? -Ask yourself these questions: How do the Patent Laws protect me? What easy steps ean I take, without cost, to put myself in position to support my belief that I am the first man to think of any invention? Is a Patent worth the cost? Do I need a model? Should I try to sell my invention before I have it Patented? Is there any sife, business-like way to secure financial help? If І do apply for a Patent how shall [ reach people who сап market my invention? Can I protect and sell an improvement on some invention that has already been patented? These are but a few of the questions which usually confront the average man, You need the answers! YOU CAN HAVE THEM, without cost, trouble, or delay, Copyright 1937 Victor J. Evans & Co. RUSH COUPON TO WASHINGTON. D.C. TODAY 6 Accept No Substitutes! Our Business Is To Help You. Write Us Today For more than thirty-six years, this firm has been helping men with an inventive tura of mind, We maintuin a lurge staff of trained, experienced specialists—Registered Patent Attorneys, Draftsmen, and Searchers to help our clients secure all the protection to which they are entitled, Fees are reasonable, De- ferred payments frequently arranged, Ques- tions promptly answered, Write us frankly with absolute assurance that what you say will be treated with strictest secrecy. But FIRST, send for the FREE BOOKS shown on the op- posite page, They are filled with facts, pie- tures and suggestions, They tell you things about Patents, Inventions and Selling Inven- tions that we hare learned in our long experience, They may save you time, expense, EVEN LATER DISAPPOINTMENT, Simply fill in the coupon. No charge, no obligation. Write us today, Always Insist on the Advertised Brand!

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man talk about - SELLING INVENTIONS ЦТУ] 115 Mechanical Move- ments Like These Besides many other features and facts there are 115 differ- ent mechanical movements and principles in the big, 48-page Book below. Maybe there is just the idea you need to solve some mechanical problem. Use the coupon or write us a card or letter. EST^ WZ о АЕМ Picton г Г, ED we" | Evans & Co. REGISTERED PATENT ATTORNEYS, " NEW BOOK. About Selling MAIN OFFICE: 220-J, VICTOR BUILDING, INVENTIONS WASHINGTON, D. C. Other Offices: 2610-B, Singer Bldg., New York 1445-B, Monadnock Bldg., Chicago 514-B, Empire Bldg., Pittsburgh 1010-B, Hobart Bldg., San Francisco 736-B, Security Bldg., Los Angeles Send me FREE copies of your books, ‘‘Patent Protection" and "When and How to Sell an Invention." (Note: Same books supplied by any of branch offices listed above.) So far as we know, the facts in this booklet have never before been pub- lished by any Patent At- torney. You are given very definite suggestions on “When and How to Sell an Inven- tion.” It also comes to you " Y FREE. SütreeL and №0... ее. тонкие зоне eher T Cur ar DOWD us acoso shai ordei RS obit xr RMSE ERE VI When Answering Advertisements Please Mention August Modern Mechanix 7

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AUDELS Carpenters and Builders Guides "A d 21:4. vols.56 inside Trade Information for Carpentera, Builders, Join- ors, Building Mechanics and ell Woodworkers. These Guides give you the short-cut instructions that you want— including new methods, ideas, solutions, plans, eysteme and money saving suggestions. An easy progressive course for the apprentice and student. А ractical daily helper and uick Reference for the master worker. Carpenters every- where cre using these Guides as a Helping Hand to Easier Work, Better Work and Bet- E 2 i ter Pay. To get thia assist- зн НЙ - n nnd mii - Inside Trade Information On: PON below, © How to use the steel square—How to file and set saws—How to build furniture-xHow to use а mitre box—How to use the chalk line—How to use rules and seales—IHow to таке jointa—Carpentera arithmetic—Solving mensuration problems—Es- timating strength of timbere—How to act girders and sills—How to frame houses and roofs—How to estimate costs—How to build houses, barns, gar- ages, bungalows, etc.—How to reed and draw plans—Drawing up specifications —How. to ex- cavate—Ho to use settings 12, 13 and 17 on the steel equnre—How to build hoists and scaffolds— skylights—How to build stairs—How to put on interior trim—Low to hang doors—How to lath— lay floors—LHow to paint BEHNESER THEO. AUDEL & CO., 49 W. 23rd St., New York CIty Mail Audela Carpenters and Buildera Guides, 4 vols., on 7 days’ free trial. If O.K* I will remit $1 in 7 days, and $1 monthly until $6 ia paid, Otherwise I will return them: No obligation unless I am satisfied, ER eNGINEERING d THE FIELD with a FUTURE} Fér those who cannot afford the expense of 4-year № college training, Bliss offers a CONDENSED ONE- YEAR residence course, approved by educators; endorsed by industry. 44 years experience. Modern, E laboratory and shop equipment, suburban campus. B Excellent faculty; wholesome, friendly atmosphere. 45th year begins September 29th. CATALOGI BLISS ELECTRICAL w р SCHOOL B 3 298 Takoma Ave., Washington, D. C. Ё ARREST HIM, OFFICER! l'LL HAVE COMPLETE FACTS ON THE OTHER FELLOW TONIGHT! Secret Service Operator No. 33 is on the job . . . FOLLOW HIM through all the exeitement of his chase after the counterfelt gang. Write NOW for F R E Confidential Reports No. 38 Made to His Chief! Jt may open your eyes to the great opportunity for YOU as a well paid Finger Print Expert. The kind of work you'd like. Excitement! Travel! Thrills! A REGULAR MONTHLY salary. REWARD MONEY. Grad- uates of this school HEAD 47% of all Identification Bureaus in U. S.! Write for Free Reports, Finger Print Book, low prices, Easy Terms Offer, if 17 or over. Literature will be sent only to persons stating their age, INSTITUTE OF APPLIED SCIENCE 1920 Sunnyside Ave., Dept. C-235 Chicago, Illinois 8 Accept No Substitutes! CONTENTS—Continued from page 4 SHORTER FEATURES Eclipse Began After It Ended!—Frontispiece 35 Folding House Becomes Trailer - - - - 40 Tiny News Plant Draws Crowds - - - - 48 HOW-TO-BUILD FEATURES Home Experiments For The Amateur Physicist - - - =- - = - - - - - 72 Scan The Sky With This Powerful Home-Made Telescope = = = - - - 74 A Recording Rain Gauge For Amateur Weathermen- =- =- - - - - 80 Build a Bellanca “Gas” Model Plane— Conclusion - - = - = = = - - = 82 Body Completes “Arlen” Racer—Part ПТ. - 86 Conditioning Your Boat For Summer Sailing 94 $2.50 Breakfast Nook - - - - - - - - 96 A Walnut And Copper Ice Bucket - - - - 98 "Ether Imp"—A 34-Meter Transmitter - - 102 NEW MECHANICAL INVENTIONS New Navigation Computer Solves Flight Problems = - - - - - - - - 33 New Slide Rule Aids Printers - - - - - 33 Flash Bulb Has Wire Element - - - - - 41 New Saw Operates By Lever - - - - - 41 Steam Challenges Diesel With New Locomotive- - - - - - - 49 Telegraph Transmits Colors- - - - - - 49 Electrical Device Examines Inside Of Fruit - 57 Doorbell Demands а Nickel - - - - - - 57 Novel Propeller Has Arced Blades | Offset At Hub - - -= - - - -.- 58 Air Suction Drives Machine- - - - - -. 58 Robot Parachutist Devised - - - - - - 59 New Refrigerator Has Built-In Radio Receiver - - - - - - - - - 63 Car Heater Burns Gasoline - - - - - - 66 Machine Provides Permanent Wave In One Minute - - - - - - - - - 67 "Crawler" Uses 8 H. P. Motor - - 67 [Continued on page 12] Always Insist on the Advertised Brand!

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pa 1939 1940 1941 1942 1943 1944 1945 046 1047 The leaders of the next ten years will largely be deter- mined in the next ten monthsa Will you be one of them? Will You Be Clerk or Manager Ten Years from Now? MONURELY, this could never happen to me,” you say— “that I should be sitting at the same desk—be doing the same work-—for ien straight years!" But wait а minute— Exactly that same thing has happened to thousands upon thousands of men. lt has probably happened to. men right in the company you now are working for. And —unless you fit yourself for а better job—there is a very good chance that it may happen to youl Unthinkable? That’s what J. N. Dixon of Columbus; Ohio, said to himself. Yet lack of training kept bim slaving away at low wages for a long time. TRIPLES INCOME Here is Mr. Dixon's own story—‘‘Just after I returned from the war, one of your representatives found mo lugging away at a bookkeeper's job in Marietta, Ohio. E: performed a realservice and explained to me the need of further training, and induced me to take the LaSalle training in Higher Accountancy. After a few months of study, 1 secured a position with the Trust Department of a National Bank. This was the stepping stone I needed to various responsible positions including handling of receiverships and other important duties, That quickly boosted my income several hundred percent.” ANOTHER AMAZING SUCCESS STORY Tf you think Mr. Dixon's success story unusual, please read what J. H. Krouse of Memphis, Tennessce, says. Мед I decided to take your training in Higher Accoun- tancy, I was a clerk. Today I am Chief Consultant Ac- countant for the U. S. Engincer's Office in Memphis, Tenn. Whatever success or recognition I have had, È owe to your training. I have had no other specialized tralning along this line. Your method of teaching is поб only instructive but highly engaging. I have observed other courses, but firmly believe LaSalle has the best to be had anywhere,” Another bit of proof is Mr. В, P. Barthalow's ехрегі- ence. Мг. Barthalow is Chief of the Sales Tax Section of the Tax Commission of Ohio. A department which handles over $50,000,000 a year. Mr. Barthalow attribe utes much of his success to LaSalle training. SEND FOR These Two Books and Start Toward Bigger Success Need you hear more before you investigato the oppore tunities in Accountancy? Or will you face the problem of your future NOW— and send to LaSalle and get further facts and particulars? Without cost or obligation, the coupon will bring you two interesting books—one a 64-page book entitled; "Accountancy, the Profession that Pays"; the other “Ten Years’ Promotion in One.” | How about those next ten years—will you wait or will you START TODAY to realize the tremendous oppore tunities that Не ahead of you through sound and practical home-study business training? Measure your grit and ambition by what you do with this coupon—NOW, LaSalle Extension University LASALLE EXTENSION UNIVERSITY, Cost Accountant, etc. Other LaSalle Opportunities: If more interested in one of the other fields of business indicated below, check that. O Business Management OLaw: Degree of LL. B. OExpert Bookkeeping D Industrial Management Oc. P. A. aching O Personnel Management О Modern Salesmanship ОТга с Management Name ———Ó Dept. 8493-HR Opportunities in Accountancy—Check below and we will send you a copy of “Accountancy, the Profession that Pays," also copy of “Ten Years’ Promotion in One,” all without obligation. 0 Higher Accountancy: Leading to position as Auditor, Comptroller, Certified Publle Accountant, n O Modern Business Correspondence Li Eective Speaking CHICAGO OStenotypy O Business English Commercial Law Present Розов ыенен m rure ee rrr ere re e e e ee ee e Gir SSecccceccccenavscnneaceananenasenee When Answering Advertisements Please Mention August Modern Mechanix 9

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THAT HAVE BUILT BIG BUSINESSES | № VENTions do not have to be complicated to be profitable when Pat- ented. The 5c and 10c stores flourish on simple Patented products which are commercially suc- cessful. The zipper, safety pin, thumb tack, paper clip, collar button—all simple, yet familiar inven- tions—brought their inventors rich rewards. If you have a Patentable invention—act to protect it. Many of the most useful, widely popular, greatly profitable, and extremely successful inventions have been very simple ones. You have only to look at the devices we have pictured here to realize how a simple invention may become a utility bought by a hundred thousand or a million people soon after it is produced. Don't be afraid that the simplicity of your invention makes it valueless. The thing that you find so simple that you wonder why a thousand other people haven't already done it is often the invention worthwhile, HOW OTHER INVENTORS GOT STARTED 38173 ADAMS The list of men who succeeded in in- vention with only a poor boy's start is a very long and noble one. Poverty, hardships, lack of friends, distance from the market—these could not hold back Bell, Edison, Eastman, McCormick, Whitney and others. Everyone cannot succeed. But every man can try. Cour- age, sacrifice, and hard work may bring you a measure of the success these men had. Lack of mechanical ability is not a serious drawback. You can always get someone able to build a model, draw a detailed design, or otherwise mater- ialize your invention for you. The big drawback is discouragement. Your invention of a practical article or an improvement upon an old one should be patented NOW. Frequently many of the thousands of applications filed in the U. S. Patent Office each year are for the same or almost the same in- vention. In such a case, the burden of proof rests with the last application filed. Sometimes a delay of even a few days in filing the application means the total loss of the patent. LOSE NO TIME. The entire time of this large and ex- perienced organization is devoted ex- clusively to patent and trade-mark cases. We know the rules and require- ments of the Patent Office. We under- stand the technicalities of Patent Law. We can proceed in the quickest and safest ways in preparing an application for a patent covering your invention. THE BIOGRAPHY OF GEORGE EASTMAN Views of the man who used Patent Protection to amass millions and give per- fection to a new art—Photography—itself one of the greatest inventions. CLARENCE A.OBRIEN & HYMAN BERMAN BUILDING WASHINGTON, р. €. Registered Patent Attorneys Before U. S. Patent Office 10 Accept No Substitutes! Always Insist on the Advertised Brand!

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If you have an invention from the invention—you can’ The First Important Step in Securing a Patent is to obtain the services of a Regis- tered Patent Attorney. The U. S. Patent Office advises that you secure the aid of an experienced Registered Patent Attorney to prepare your statements. Establish the date of your invention as explained in our book and disclose your invention to him in correct form. He then makes a SEARCH of the Patent Office Records and reports to vou on existing U. S. Patents which might bear on your invention, giving his opinion on the advisability of proceeding and filing formel application. Reasonable Fees—Con- venient Terms Don’t worry about finances. Our fees are very reasonable—we can arrange convenient terms of pay- ment. It is our custom to permit clients to pay for our services in in- stallments as the application pro- gresses in our office. See our Big Book for fees in obtaining Patent. It explains our arrangements clearly, Send for it NOW! that is patentable—and want to secure - for yourself your inventor’s sole right to profit : t afford to lose time in COM securing the protection of a U. S. Patent. Other inventors may be ^^ working on the same invention right now. Should they develop. this invention and file patent application before you do—the burden of establishing priority will be upon you. Our Big Book—"Patent Guide for the Inventor’—will tell you the quickest possible way to secure Patent Protection for your invention, SEND FOR IT TODAY! FREE RECORD OF INVENTION FORM Use our Free “Record of In- vention" form to assist you in recording the descriptive out- line of your invention and to establish the date of your in- vention. With it you can make a rough sketch of your invention and have it wit- nessed in a manner of value to you as evidence Should occasion arise, CLARENCE A.O°BRIEN _& HYMAN BERMAN | 3 3173 ADAMS BUILDING — МАЅНЕМСТОМ, О.С. _ REGISTERED PATENT ATTORNEYS ze E EFORE U.S. PATENT: OFFICE Please send me at once your Big Free 48-Page Book, “Patent Guide for the Inventor” and your Specially Prepared “Record of Invention” form, Also George Eastman Biography, “Inventor and Business Man.” This request does not obligate me. NAME ... ADDRESS 9260 вов PAB4b 400300210282 000) I BODUL0ORAQUA POP RDA Pn MAD С 9119 еьо 9969990010909 93 96 иди 09 ьевазезвенознонувгвевавововеввревоњаневв оен (Please write or print plainly) Раис eee Lanuanenacaunm When Answering Advertisements Please Mention August Modern Mechanix 13

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a Queer Wa to Leain Music / BE your own music teacher. Just a simple, easy, home-study method. Takes only a few minutes—averages only a few cents— a day. No "grind" ог hard work. Every step is clear as crystal— simple as A-B-C throughout, You'll be sur- prised at your own rapid progress. From the PickYourInstrument start you are learning real tunes by note, | Piano Guitar Learn to play ''jazz'" or classical selections— | Yiolin Saxophone е, н Organ Mandolin right at home in your spare time. ornet Ukulele " rombone Harp Free Book and Demonstration Lesson Piccolo Elarinet Don’t be a wallflower. Send for Free ие. сено Booklet and Free Demonstration Lesson. Hawalian Speel These explaln our wonderful home study Piano Accordion CONTENTS- Continued from page 8 FOR THE WORKSHOP FAN Workshop Hobbies - - - = = = > - "1 Kiddies’ “Whirl Swing" Combines Clothes Drier - - =- + - = = = = 97 Animated Elephant Sprinkles Lawn With Its Trunk - - - - - -~ = - 97 Tips For Mode! Railroad Builders - 100 New Ideas For Handy Men- - - - = - 104 Kinks That Simplify Shop Tasks - 105 PHOTOGRAPHY Home Camera Stunts - - - = = = = = 106 method fully and show you how easily and quickly you can learn to play at little ex- pense. Mention your favorite instrument. Write NOW. Instruments supplied when needed, cash or credit. U. S. SCHOOL OF MUSIC . Trumpet italian and Gorman , Accordion Voice and Speech Culture Harmony and Com- position Drums and Traps Banjo (Plectrum, S- Modernizing Your Graflex - - - - - - 108 Kinks For Camera Fans - - - - = - - Ш All-Purpose Camera Stand - - - - - - 112 Short-Cuts For The Amateur Photographer - 113 A Double Unit Floodlight Case- - - - - 114 String or Tenor) 2628 Brunswick Bida.. New York City Year Bubseription 60c entered upon promise to pay on receipt of first copy. Place your order by cutting out and mailing this advertisement. Tread Invention & Finance—it's your chance to make money. INVENTION & FINANCE MAGAZINE 80-H WALL ST., NEW YORK, N. Y. CATALOG FREE FACTORY PRICES—SAVE 50% Why pay fancy prices for radios? FREE home trial. MONEY-BACK if not satisfied. ONE YEAR GUARANTEE. 24 beautiful models. 5 to 15 tubes. Radios that get EUROPE. New battery radios for farms. Auto radios. Send postcard for FREE catalog. WORLD-W!DE RADIO Co. 2868 ELSTON AVE. Dept. M, CHICAGO SEND ONLY 3 1 Pay balance C. 0. D. MAKE MONEY AT HOME RUBBER /ошс, MOLDS M Amazing rubber mold-making outfit makes perfect fexible molds of plaques, ash trays, book-ends, etc, Molds eost from бе to 25c each. Each mold makes hundreds of novelties and gifts to sell up to $1.00 apiece! No experience necessary. Everything fure nished. Start profitable business in your home... Sell to stores, friends, resorts, road stands or by mail—NOW! Make BIG MONEY full or spare time. Write for complete FREE details and easy instruc tlons. 50-50 GO-MA MOLD CO., Dept. U-834, Cincinnati, Ohio. DEPARTMENTS Random Chips From The Editor's Workbench 14 Solving The Readers Problems - - - - 24 Nie Sprank's Science Oddities - - - - - 34 Workshop Hobbies - - - - - - = - "71 Timely Kinks For The Auto Enthusiast 91 Useful Tips For Motorcyclists - - - - - 92 Kinks For Summer Campers - - - = - 93 Radio Sparks - + - - = - = = = 101 MISCELLANEOUS Fluoroscope Used On Dog - 33 Trucks Remove Cargo From Wrecked Freighter - - - - = = = - 41 Powder Flame-Proofs Cloth- = =- = = = 49 Motorcycle Sets New Mark - - - = = = 57 Youth Builds Bike Trailer - - - - - - 58 Trailer Shop Provides Livelihood For Cobbler 59 3,000 Pictures Per Second - - = = = = 66 Paste Restores Compression- - = = = = 67 12 Accept No Substitutes! Always Insist on the Advertised Brand!

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Beginning Lessons in Diesel — [$ Your Job Safe? Just as the gasoline engine changed or wiped out the jobs of thousands who depended on norse-drawn vehicles for their living—just as electricity changed the entire set-up in the fields of light and power—so now the Diesel engineisfast invading both the power and transportation fields, and threatening the present jobs of thousands of workers. growing scarcer, you owe it to yourself to investigate this new, progressive, uncrowded line, that in our opinion will offer good openings for the next 25 years. the If jobs in your line are steadily § Diesel engines— because of their high efficiency, dependability, and economy of operation—are fast replac- ing steam and gasoline engines in power plants, motor trucks and busses, loco- motives and ships, aircraft, dredges, drills, pumps, etc.—opening up an in- creasing number of well-paid jobs for Diesel-trained men. The field of Diesel Engineering is on the upgrade and con- tinually expanding. It will provide steady employment, advancement and good pay forthose properly trained in this new industry. What This New Fleld Offers You Now is your chance to get into a big new industry and grow up with it to an important position. Today there is practically no competition in the Diesel field, but the increasing use of Diesel engines will result in keen competition for jobs in the near future. By starting your training now, you American School, Dept. DC28, Drexel Avenue at 58th Street, Chicago бат Diesel Engineering To Men Over 18 and Under 40 _ This offer is NOT open to boys under 18 or men over 40. Butif you are WITHIN these age limits, you owe | it to yourself to investigate this unusual opportunity. Test Yourself Without Cost See how readily you, too, can Learn Diesel At your leisure in your own home, read these 2 | Diesel lessons carefully. Judge for yourself our abil- ity to teach — and your ability to learn — this fast- growing new line of work, No experience needed. New, Fast-Growing Power do D In Í | BrE В. ean keep ahead of such competition. You get complete information on all the latest Diesel developments—two- and four-stroke cycles; low- and high- speed and heavy duty types; Diesel- electric generating systems, etc.—in our course. Includes all text material —with special diagrams for quick un- derstanding of this new power. Real Opportunities tor Trained Men Get our Free Diesel Booklet and learn all about this new, fast- growing line—its opportunities and re- quirements. Find out what the Diesel field offers you—how rapidly the Diesel industry has developed during the last three years—the large number of Diesel engines and accessories being manu- factured today—how quickly you can obtain a complete understanding of Diesel engine principles and operation by home study during your spare time! ...8í your own pace—without inter- fering with your regular work. Get These 2 Diesel Lessons When you learn what worthwhile op- portunitiesDieseloftersand howreadily you can cashinon them through Ameri- can School training, lt may mark the turning point in your Ше. If you are over 18 and under 40, write TODAY for FREE lessons and FULL informa- tion. No obligation, Free Lesson Coupon American School, Dept, DC28, Drexel Ave. at 58th St., Chicago I am over 18 and under 40 years of age. Without obligation, please send me 2 Diesel lessons ‘and Diesel booklet When Answering Advertisements Please Mention August Modern Mechanix 13

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This 25-passenger sightseeing boat (top) was constructed by H. G. Meigs, of Milwaukee, Wis. Lower photo shows how paddle wheels are attached to auto rear-end to propel the craft. . E WISH to remind all readers that letters and photos relating to projects completed in home workshops are always eligible for entry in the monthly Editors Workbench contest. There is no time limit, contributions receiving careful consideration as soon as received in the MM office. A monthly selection is made from the available photos, a prize of $5 being awarded to the reader who, in the opinion of the editors, sends in the most interesting photo and letter. Prizes of $3 each are awarded for all other photos published in the Workbench each month. Send in a photo and letter describing projects you have completed. LLLI A letter describing an unusual project was re- ceived from H. G. Meigs, of Milwaukee, Wis., who 14 was awarded this month's first prize of $5. His letter reads: Dear Editor: I thought you might be in- terested in a sightseeing boat which we built, so I am send- ing you photos of it. The boat has a speed of 12 m. p. h. and is very popular with visitors to the lake resort where the boat is kept. It has a draft of only five inches. The motive power consists of an automobile engine and transmission. The rear end of an auto is mounted on a frame- work so that wooden blades attached to the rims of the wheels can propel the craft. Ап automobile steering wheel is mounted by the driver's seat, having a large spool attached to the bottom of the shaft in the hold. A flexible cable runs from this to the rudder. H. G. Meigs. Reader Meigs is to be complimented for com- pleting such a novel and practical project. kK An award of $3 was sent to Wendell Lalley, of Monroe, La., for his letter and photo describing an attractive “gas” model airplane. He says: Dear Editor: I am sending you a photo of my "gas" model air- plane. Although I have built many rubber-powered models, this is the first “gas” model I ever tackled. It has a span of 7 feet, weighs 494 pounds, and is powered with a motor of one-fifth horsepower. p cen RR 2 E Powered by a miniature gasoline engine of 1/5 horsepower, this model plane has a 7-foot wingspan. Wendell Lalley, who built the model, prepares to test its gliding qualities.

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ep Calor ot onc] I enjoyed the "gas" model article that appeared some time ago. Why not give us some more plans for “gas” models? I would also like to correspond with readers who are interested in such models. | Wendell Lalley. Lalley’s model looks like a well designed and well constructed one. We hope he will build the Bellanca gas model described (final installment) in this issue. РРР This is the season for midget racers and а letter and photo received from James Webb, of Attwood, IH., telling of his speedy little auto was awarded a prize of $3. He says: Dear Editor: Enclosed is a photo of a midget racer that a pal and myself built. We want to tell you how pleased we are with your magazine for we get most of our plans from it. We are now planning to build the sailing cruiser "Buddy". Good luck to MM. James Webb. While Webb neglected to supply details con- cerning the size, power, etc., of his tiny racer, we awarded him a prize on the basis of its appear- ance alone. eee Novel in appearance and utility is the project described in a letter from W. Posniak, of Tampico, Mexico, which won an award of $3. He writes: Midget autos still continue to intrigue MM workshop fans. This metal-clad racer built by James Webb, of Attwood, Ill, was awarded a prize on basis of its appearance alone. Music played by W. Posniak, of Tampico, Mexico, is picked up by the microphone lamp he built and emanates from small radio set nearby, serving to entertain friends in novel manner. Dear Editor: T am sending you a photo of the microphone lamp that [ constructed. The device is 12 inches high with- out the light globe, the microphone ring having a 6-inch diameter with a center disc 376 inches in diameter. The photo shows me broadcasting over the micro- phone lamp, the music being heard from a small radio set located nearby. W. Posniak. A microphone lamp provides much entertain- ment and constitutes a project that has ap, :^! to all radio fans. From Oteen, North Carolina, came a letter written by C. E. Self which was awarded a $3 prize. It reads: Dear Editor: I am enclosing a picture of a miniature railroad caboose that I built from discarded match sticks. I hope you will consider the project in the Workbench contest. The walls of the caboose are constructed of burnt match sticks. The roof is covered with the inside of the boxes that the matches were packed in. The wheels, steps, oil boxes, and draw heads are made of wood, whittled to proper shape. | Four bunks are features of the caboose interior, while four seats are located in the cupola, all of which are upholstered in leather, The windows are made from old X-ray plates. The caboose is 16 inches long and [Continued on page 16] 15

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EASY WAY TO TRAIN START (36) FINISH AT HOME IN CALIFORNIA Combined Home Training & Actual Shop Experience Electricity is a tremendous Industry, growing bigger every year. Trained men qualify for good jobs in all its branches. YOU сап qualify by training and you don't have to leave home to start. National Schools bring training facilities to you, We offer an ex- tension of resident school training, enabling you to master preliminary iraining at home, while you are working. No interruption to your present job. Then you come to this million-dollar School for final intensive SHOP-PRACTICE instruction on same types of equipment you will find in the field. Not Ordinary Home-Study Course Only a residentia] school such as National can offer this kind of train. ing. This ‘‘start-at-home’’ plan is the development of 32 years of continuous testing and use In the shops of Natlonal Schools. Shop-Tested Quick-To-Learn Course We actually brin ine School's facilities to you and you to the School. No dull text books, Easy, fascinating, individual coaching. Transportation To California After preliminary home-training is ompleted, we allow round-trip transportation from any point in the U. о L. A. for you to complete your course at school. Investigate. Psi Coupon for Book of Electri- €al facts and detalls. NATIONAL SCHOOLS (Home Tralning Division) | Dept. 8-ММЕ, 4000 So. Figueroa St, Los Angeles. і 16 Editor’s Workbench Chips [Continued from page 15] Em LIT: GI E AK S rt Displaying unusual patience and skill, C. E. Self, of Oteen, N. C., constructed this model caboose, using more than 4,000 match sticks. Wheels, steps, etc., were whittled from wood. 7 inches high, and incorporates more than 4,000 matches in its construction, C. E. Self. We admire Mr. Selfs patience and skill in creating the novel caboose and hope he will let us see photos of other projects he has completed. ж Modelers interested in particular types of modeling frequently desire to correspond with other readers having similar interests. MM will gladly print letters from readers who desire to locate a "Pen-Pal", Send in your letter, but be sure to print your name and address clearly. The value of correspondence with other readers who are interested in the same subject cannot be overrated. Through an exchange of ideas, de- signs, kinks, еїс., а more thorough knowledge of any hobby can be acquired, to say nothing of the friendships started, many of which last through- out a lifetime. *dok Boat project letters and photos continue to out- number all other types. George C. Espersen, of Silver Creek, N. У. sent іп a letter that was awarded a $3 prize. The letter reads: Dear Editor: I am enclosing some photos of "Nomad", which was constructed from MM plans. It is framed with yellow pine and planked with mahogany, finished natural. "Nomad" sails very well with one or two persons aboard, being very stable and showing good speed. I certainly recommend MM plans to ali persons contem- plating the construction of a boat. They are very clear, easy to follow, but most important, thoroughly tested designs. George C. Espersen. Thanks for the compliments. on the MM plans, Espersen. The trimness of your craft is eloquent testimony as to your craftsmanship, and we are pleased that you selected MM plans. [Continued on page 18] Accept No Substitutes! Always Insist on the Advertised Brani!

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To help you answer these 3 E | questions: What are today's € opportunities in Drafting? Will I like the "work? Can I learn Draft- "V ing readily? To Men Over 18 and Under 40 This offer is NOT open to boys under 18 or men over 40. But if you are WITHIN these agelim- its, you owe ittoyourself to lnves- tigate this unusual opportunity. Drafting Opportunities Growing Daily Before anything can be made or built, the Drafts- man first must draw it. Building trades, transportation, manufacturing — ALL depend on him, That is why any pickup in any line means first call for the Draftsman! Fit Yourself for a Job with a Future Drafting weleomes ambitious men — offers good pay to start, with splendid opportunities for promotion. One of the steadiest of all lines. Right from the start, the beginner works side by side with experienced men—inking in their drawings, making tracings, constantly profiting by his contact with seasoned engineers. The “higher ups” see his work. If it is good, advancement is sure and steady. Pleasant, well-lighted offices are the Draftsman’s work- room. He keeps regular hours, with congenial, high grade fellow workers, The work is fascinating—embraces not just one line, but hundreds. Drafting Experience NOT Necessary You can master Drafting readily by home study because you learn and advance exactly as professional Draftsmen work—with T-square, dividers and drawing board. Actual working conditions are duplicated to the final detail. Thou- sands of successful graduates enthusiastically endorse Amer- ican School methods, nowhere better exemplified than in our Drafting course. We want you to see for yourself—before you come to ANY decision—exactly what Drafting is like. We want you to judge your own interest in the work—and our ability to teach you. So we make this 2 Free Lesson Offer. American School, Drexel Ave. at 58th St., Chicago, lil. Prove That You Can Qualify If you are over 18 and under 40 years of age; the 2 lessons will besent FREE. In theprivacy of your own room, look them over. See how simply you start — how gradually you are led step by step—how, as time goes on, you can pass from 2 raw beginningto complete mastery of Drafting — able to get and hold a pleasant, profitable, steady job. Such a futureis well worth looking into RIGHT NOW,so...just mail the coupon! pu a 0 dnsrumento M a erial 3 aet Mail Coupon for 2 Lessons FREE Бака eS PLE Pr eee ee Е American School, Dept. DDC28, [| Drexel Ave. at 58th St., Chicago Е Without theslightest obligation, send 2 beginning Dreft- Е ing Lessons and free Bulletin. І am over 18, under 40. When Answering Advertisements Please Mention August Modern Mechanix 17

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Earn better pay! Get out of overalls! Learn PRACTICAL DRAFTING. If you’re a Shop Worker, DRAFTING will put you in line for quick pro- motion. As a mechanic, DRAFT- ING means increased earnings, more pay raises, DRAFTING leads in all industries. Jobs open NOW! Aviation, Machinery, Automobiles, Building must have draftsmen. Learn Practical Er RAFTING 2: ENGINEER an ENGINEER ТИ train you on practical work by a method successful with thousands since 1900—-and furnish you all tools; also Drawe ing Table. No high school or previous experience required. You must be entirely satisfied with my personal training UNTIL COMPETENT and assisted toa position OR MONEY BACK, TART NOW! Write TODAY for FREE BOOK on “Draftsmanship.” You must give your age. No obligations, Mail coupon belowt FREE BOOK ENGINEER DOBE Div. C473 ВЕ. Libertyville, 111. m Send me your free book, ‘‘Successful Draftsmanship" and м explain how you will assist me to a good position as а m draftsman, Sar a Name = Address — -a Post Office. a "STATE COLLEGE B. S. Degree 1n 2 years. World famous for technical 2-year courses in Civil, Electrical. > 4 а а Radio, Aeronautica] 2 Engineering; Business Administration and ENGINEERI NG Accounting. Those who lack high school may make up work. Low tuition. Low living costs. Short diploma courses in Surveying (36 weeks), Drafting (36 weeks). Students from етегу state and many foreign countries, 54th year. Enter March, June, Sept. and Jan. Write for catalog. 687 College Ave., ANGOLA, IND, BE A POULTRY EXPERT Make $1000 to $2500 a Year Free book shows how to get started quickly, You'll be surprised at the amazing profit opportunities in the poultry business. Wherever you live—whatever you do—it is easy to start on a spare or full time basis. Free book tells all. Send for “How to Raise Poultry for Profit." Learn at home in spare time. The famous №. P. I. home- study course is endorsed by colleges and leading poultrymen, Know how to get the maximum profits from interesting, healthy work. Iron- clad agreement protects you, We have prepared hundreds for good jobs and businesses of thelr own, Write now for free book, No а yama Poultry Institute, Inc., Dept, 132-С, Adams enter, N. Y. AMATEUR CARTOONISTS" WIN $2500 No drawing ability AIK үр" Wanted—Amateurs with humorous ideas. necessary. The amateurs of today are the professional cartoonists of tomorrow. Ideas judged and prizes awarded by Applause-O- Meter test before movie audiences, Everyone has an equal chance. 26 cash prizes in all. Rush name on penny post card for ‘Valuable Tips on How to Make Money With Simple Cartoons and Humorous Ideas’’, Cash Prize Entry Blank and Rules-SEND NO MONEY. CARTOONISTS' EXCHANGE Dept. 358-A Pleasant НШ, Ohio Editor's Workbench Chips [Continued from page 16] Sailing well with one or two persons aboard, the "Nomad" sailboat shown above was built by George C. Espersen, of Silver Creek, N. Y., from plans in popular MM boat book. What is YOUR opinion concerning the much debated question as to whether or not home craftsmen aviation fans should be permitted to build and fly home-built aircraft? Do you be- lieve that existing regulations should be elimi- nated or modified so that groups of aviation enthusiasts could band together to build and fly light planes, thus enabling ambitious fellows to indulge in the sport of flying at minimum cost? Does the fact that many finely constructed home- built aircraft are being operated in some states make you yearn for similar "considerate" air legislation in your state? MM would like to hear from all readers in- terested in the construction of light planes and will print as many letters as possible concerning opinions on the elimination, modification, or continuance of present government regulations relating to home-built aircraft. Send in your letter and include a photo of yourself, if possible. In addition to printing the letters of readers on this controversial subject, MM plans to feature photos and details of home-built aircraft that are being operated in states where regulations permit such activities, Some one is killed in one out of 61 automobile accidents, if the automobile is traveling no faster than 20 miles an hour; but if the car is going 50 miles or faster, the ratio is a death to every 11 accidents. 18 Accept No Substitutes? Always Insist on the Advertised Brand!

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GEE what a build / Didnt it take a long time to get those muscles? Fi Will You Give Me 7 Days to PROVE І Can Make YOU a NewMan: 5 inches of new Muscle Sater ONE ase ту ins rms increase in. э i chest 2125 in., forearm - (пота!) an 9.212 s Za in. " and 1 have gained E с S.C. $. W., Va. № SIR! -ATLAS Makes Muscles Grow tarted а k ago. For quick results | recommend | Here's what ATLAS did for ME/ CHARL TEAS i 4, recent photo of harles Atlas, twice winner and holder of the pe. “The World’ Most piger Ат sending snapshot of wone derful progress. Certainly rec- ommend you for quick ree sults!’’—W. G., М. J. studlo picture 2 but a simple enlarge- Tnent P nade from an ordinary smalt jnapshot, muscles ** ainted ga or retouched WM B $s ‘Your method 5 B Е way. This long, smooth inis x is в Charles «Has John Jacobs John Jacobs When | started, V- S he looks today! BEFORE AFTER Now weigh td. -DAY TRIAL OFFER I could fill this whole magazine with enthu- Sterling Silver Cup siastic reports from OTHERS. But what you Being Given Away s This valuable cu of solid want to know is—-“What can Charles Atlas do | sterling. silver, stands about for ME?” 14 inches, high on & black ж s а imnahogan; ase. Find out.—at my risk! Right in first 7 days I will award e engraved, to, Trai s e " В I'll start to PROVE I can turn YOU into a | PY ВЧ оо Каў но торготетепе іп pon of micht ond musele, ( And it will be Hes SEE, FEEL Еее AER ind of you (and anyone else) can Ё MEASURE with a tape! : i CHARLES ATLAS, Dept. 6х Му FREE BOOK tells about my amazing 7-DAY TRIAL OFFER—an 115 East 23rd Street, New York, N. Y. offer no other instructor has ever DARED make! If YOU want smashing X want proof that DYNAMIC TENSION will make a new strength, big muscles, glowing health—I'l| show you results QUICK! man of me—give me a healthy, husky body and big muscle FREE BOOK development. Send me your free book, “Everlasting Health and Strength.” T myself was once a 97- -pound weakling—sickly, half-alire, Then I dis- covered “Dynamic Tension.” And I twice won against all comers—the title, “The World's Most Perfectly Developed Man” have no use for apparatus, ''Dynamic ‘Tension’ ALONE (right in your own home) will start new inches of massive power pushing out your ehest—build up your shoulders to champion huskiness—put regular moun- tains of muscle on your biceps—free you of constipation, pimples—make those stomach muscles of yours hard ridges! Make me PROVE it! Gamble a postage stamp. Send coupon for my FREE BOOK AT ONCE! Address me personally: Charles Atlas, Dept. 6X, 115 East 23rd Street, New York, N. Y. NAMS аанынан а еек (Please print or write plainly) Addtéss „.. киль зороорво ноя во ото о ооо ро ов ивозоотоое AAA n1 P When Answering Advertisements Please Mention August Modern Mechanix 19

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“I knew I was saving money," writes a new Atlas buyer, “but thought I was missing something a costly lathe might have. Now I’m doubly sold on Atlas. A Гуе given it some of the toughest tests —nothing is lacking. It is fully as / much lathe as I could have bought / for a lot more money," Yes—Atlas leads in quality of'construction and performance. Send for Catalog. Se why Atlas will serve you better. ATLAS PRESS COMPANY 852 N. Pitcher St., Kalamazoo, Michigan A Я e вор 2d m ied. atore E. ol Mus Slips inte Any Old Range or Cooking Stove; Does Away With Coal or Wood; No Dirt or Ashes; Cheaper, Cooks a Meal for Less Amazing oli burner which many users say beats any ever gotten out burns cheap oil a new way, withou! pre-generating or clogging up; gives intense heat at less cost by turn of valve. hu cH at TURN € OF VALVE One free to one person in each locallty who A GEN T $ will demonstrate and е act as agent. write] BIG MONEY gulek be first to learn how to end drudgery It’s sweeping of eoa. and wood апа | the country. make big money spare GET YOUR or full time—mai! 1с| OWN BURNER 5 "UNITED FacToRtes | FREE ae and make COOLER KITCHEN K-600 Factory Building REAL MONEY. Kansas City, Missouri Write quick. IN SUMMER 20 Map "Curvimeter" Devised “CURVIMETER” device which enables hikers or motorists to determine the dis- tance between two points on a map has been developed by a German manufacturer. Equalling a pocket watch in size, the device has a compass on one side and graduated scales апа an indicating needle on the other. In operation, a small wheel attached to the base of the Curvimeter is run over the map, following the road line between the desired points. Glancing at the scales and needle of the device, the user can quickly determine the distance involved. New Airplane Fuel System IRTUAL elimination of conventional air- craft engine carburetors and solution of the problems of carburetor ice and excessive intake heat are expected to result from a new type fuel system being developed by United Air Lines engineers. 'The system is consid- ered so important that full details are being withheld at the request of military and naval aviation authorities. The system will embody completely auto- matic mixture controls to compensate for changes in engine load and altitude condi- tions. А twin-engined transport plane has been equipped with the new fuel system and is being used to conduct actual operating tests of its efficiency. Work on the system started in 1931 and has been continued since then. Accept No Substitutes! Always Insist on the Advertised Brand!

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Inventio n 7" SUPERCHARG С" SAVES GAS á pn y Sd Nc оС Ат ING АТ LAST! Automotive engineers have smashed down the KER ST A barriers to perfected combustion! The new VACU} MATIC solves the secret of greater power! With almost tnagical action, this amazing invention instantly puts new life and рер in any motor. It adds mileage to every gallon of gasoline . , . produces split-second pick-up, sensitive accelerator tesponse, quicker starting, greater speed and smoother running, QLGrmuZér « Nothing Like It! The self-scarter — four wheel brakes — knee action — streame lining . . . and now VACU-MATIC! The sensational money» Guaranteed Gas Savings saving invention! With it, engineers have achieved a practical means VACU-MATIC proves itself on every cara Ie В guaranteed — 9f balancing aic and gasoline automatically for all speeds, to give worthwhile gas savings, quicker pick-up, and’more УАСО-МАТІС is entrrely Телеу) — Jt operates on the supercharge power or it costs you nothing. You can instantly tell the tinciple by automatically adding a charge of extra oxygen, drawn {ree difference іа added. power and motor: pecfo. се == you fom thc outer air, into the heart of che gas mixture. It is encirely is І power ; pertamman y AUTOMATIC and allows the motor to "breathe" at the correct time, quickly notice the cash savings on gasoline, opening and closing automatically as required. No idling troubles» по carburetor adjustments necessary. Ic is so simple ic will amaze you Fits All Cers so practical it will save you many dollars on gas costs, VACU-MATIC is constricted of six parcs, assembled ang ` NT fused into one unit, correctly adjusted and sealed а? the г = = @ « FREE OFFER COUPON = = = a а! ann’ egeat P, factory. Nothing to regulate. Any motorist can attach ies ef Call VACU-MATIC in ten minutes. Once in, its only remindet i THE VACU-MATIC COMPANY uc. itd EN is the surge of instant power and speed 7617-320 W. Sie St, Wauwatosa, Wig dap Ду A Bat it gives to the motor and the атар f > Б : gation о 003 i гош pocketbook, Gentlemen: Please send me full particulars concerning the VACUs e each ёа it affords your М [| MATIC and deuils of your Free Offer. This of course does noe VACU-MATIC offers a Free Details і splendid opportunity (т You owe it to yourself to know all Ni unusual sales and Prob f Sbor this remarkable discovery, Mail П ате че eme -om eee орното е аа IE TA орва E eee being the coupon below. Start saving gas obligare me in any way, Lo a» an ane — — oe mang V assigned. Check with VACU-MATIC and enjoy a new Address «canescens osaeener. eo granm оо e a сабре eve raa. ea en mue апі mail driving thrill! There's no obligation : She ve ye coupon, 30 get the facts now! Write today? і City. serge еа о о eeu see савр STA eme w oui uh ыбо rm „7. О Check here if interested ба selling proposition The VACU-MATIC Со. Wauwatosa, Wis. eee ee He ee o а ewe wee we SPECIAL Correspondence Courses In Only MAKE MONEY - Be a Locksmith Here’s Your Opportunity to Own a Paying Business : RADIO and ELECTRICAL ENGINEERING $ АСТ NOWI! Make this profitable, fascinating profession i p 2 5 g yours, No experience or study required. We ELECTRICAL ENGINEERING Set, £904 grasp supply full instructions and complete equip- eal field. Prepare yourself, at Low Cost, ior secure future, Moderp ment. You start earning immediately. ^ May course. So simplified anyone can understand quickly. Й be operated right in your own home. It’s Easy. RADIO EN GINEERING Extra fine course in radic, public addresg, " s 3 photo-electric work. Trains you to be Big returns on small investment sure, Profitable Super-service man, real vacuum tube technician. Experlmental kita side-line for stores. too. Write now for star- furnished, Diploma glven on completion. Tuition, ONLY $25, either tling introductory FREE offer. Be independent. course. Deferred payment pian available: copies of school catalogs 4 AS k тте D it! i ies g 3 E Own your own business. Don t Wait! Act Now, FR E E! student magazines, complete details. SEND NOW. MIDWEST LOCKSMITHS, 3711-К West Chicago Ave. Chicago | LINCOLN ENGINEERING SCHOOL, Вох 931-33, Lincoln, Nebr. sunt FROGS . MARKETS WAITING! Season Just Starting! Frog FREE legs in big demand at good prices the year round. Millions used yearly! We have one of the largest д frog markets in the world. Sel to us in addition to WEEE, soother waiting markets. Men & Women starting in every state and Canada! Now's the time to begin. Small pond starts YOU. FREE BOOK explains unusual offer to beginners. . Get this year's eggs. Write today! American Frog Canning Co. Dept. 119-R New Orleans, La. &UFDND GIANTS WEIGH UP TO 3 LBS. EACH When Answering Advertisements Please Mention August Modern Mechanix 21

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ГЕ ee ee питты = рить = O u e ПИ пищи а, я SS Sa — рии И MEEA EER. E o aO Serareà Oo e ae = OE EEE EE pose а a ra SS ee e ae ae и a a a a a ht В БШ а) ем — к=] | к ELT ‘on approval Just mail the coupon and we'll send you a set of these remarkable auto books, just off the d press. Whether you are a mechanic or helper, ex- pert or apprentice, auto owner or driver, if you're interested in knowing ап about automobile mechanics, take advantage of this FREE OFFER. Nearly 100 pages on DIESEL Engines A better job—in the gigantic auto in- dustry. BIGGER PAY—a chance to go into business for yourself and get a share of the huge profits, are waiting for any man who even half tries to improve himself. Learn auto engineering with these wonder CAN YOU FIX IT! These wonder books teli step by step HOW to take out ''play" in dif- ferential — to kill the shimmy іп steering—to set TIMING—how to put books à new way—without studying or your finger Instantly on memorizing. Simply use the JIFFY IN- engine trouble and then the quick expert way to FIX it, ewest ime provements fully cov- ered. Equal toacomplete trade course at less than & fourth the cost. 6 BIG VOLUMES 1937 Edition 2500 pages, 2000 Illus- trations, wiring аја- grams, ete., including Marine Engines, Avia- tion Motors, Diesel en- DEX to look up the answer to any auto problem. Built by eleven of America’s greatest automobile engineers, and written in simple language so you сап understand it. ‘Very newest cars, ail covered. FREE! Privilege of consulting Automobile Engineers of Amer- lcan Teci:nical Soclety for one year without cost if you mall coupon immediately ines, etc. De Luxe edl- AMERICAN TECHNICAL SOCIETY ilon, geld .stambed fiex- PreyelAvenue & 581 St., Dept. AC320, Chicago, Il, AMERICAN TECHNICAL SOCIETY, _ " Drexel Ave. & 58th St., Dept. АСЗ20, Chicago, IIl. I would like to see the new G-volume edition of your AUTO BOOKS. 1 will pay the few cents delivery charges only, but if I choose to, 1 may return them express collect. И after 10 days use I prefer to keep them, I will send you $2 and pay the balance at the rate of only $3 a month, unti! $24.80 is pald. Please include free consulting membership as per your offer nbove. Name — Address City -— Attach ployer and that of at least one business man as reference. ft. Flying Scale Models $4 „252, acking, T osta L5size of real planes тозан M express E collectsend 5 ft. Monocoupe (Ulustrated) only $1,00 5 ft. Stinson Rollant T 5 ft. Heath Parasol Send today for our new Giant Models— each a strong out- door flyer — а $10 value for only $1. Everything is in = the kit—nothing else to buy. Each of these G. H. О. Giant 5 ft. model planes cach ong Blas. ОВ formas End curved > d Bae cleanly, printed on best grade Balsa. Complete with LARGE OTTLES CEMENT AND DOPE, different colors Japanese Tissue, Special Endurance Rubber, finished Ready-Cut 3’” Wheels, Wire Balsa strips cut to elze, Washers, and... Movable Controls, shock-proot Landin; ear, Scale Details, Lettering, Numbering and Insignias, Flight Log, ete. FREE information about our line of model airplanes priced from 10c to 81. G. H. Q. MODEL AIRPLANE CO. 854 East 149th St. Dept. A, New York, N. Y. CEC OF Nd = PLEASURE or PROFIT Prepare for profitable business or fascinating hobby, at home under guidance of qualifie: instructors. No previous experience necessal 'ommon echool education sufficient. Many earn wh! learning. Our practical studio methods also Qualify ‘for well-payIng positions upon graduation. Send cou- n below at once for free booklet "Opportunities in - odern Photography'', particulara and requirements. Ta мн m mm mm um wa ma mm mm cm mé WM ÜME Mm EM um a us m s RR RU RO AMERICAN, SCHOOL OF PHOTOGRAPHY 3601 Michigan Avenue 9 Dept. 205C Chicago, lilinois Bend booklet, *Opportunities In Modern Photography'', full particulare end requirements. « Мата EE рее imm —€————— — Sie Аде------ Accept No Substitutes! No JoKE To BE DEAF WOULD YOU... Ex . 70 YOUR NEIGHBORS... х If I sendit without Cost? f РИ show you how to turn your Spare Time into Big Money No Experience Necessary Here's your opportunity to get a fine, new tailored-to- measure sult without а penny's cost, No money or ехрегі« ence necessary. If you would like to wear and introduce our guaranteed made to measure suits to a few friends and neighbors, write today. ГИ show you how to get your Suit as a bonus—also how to make BIG MONEY in spare time. Send no money! Just mail Jetter or posteard and receive beautiful woolen samples and complete details FREE. FAIRBANKS TAILORING CO., 2333 Wabansia, Chicago, fllinois. 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MAKE YOUR OWN Even a child can build at least one of the many boats that are described jn the big new 148-page book, HOW TO BUILD 20 BOATS. Send 50c for your copy, now. К MODERN MECHANIX PUBL. CO., Fawcett Bldg., Greenwich, Conn. ANE -ғт 70 7 ON FUEL COSTS Зате up io 70% fuel costs. Wonderful performance, Proven factory method. Costs nothing to investigate. Write for free HARRINGTON COMPANY 1-204 Manchester Bldg. Portland, Oregon СОМРГЕТЕ ЕГЕСТКІС Р1.АМТ$ ONAN ALTERNATING CURRENT? PLANTS furnish same as city current anywhere. Operate on gasoline, Run Radio, Water System, Refri- gerator, all Appliances. Complete, ready to rum . SIZES 350 WATTS UP Easy to install. Available from stock. Ideal for Farms, Camps, Lake Ilomes, Commercial use. Sizes tor any purpose. Write for details. W. ONAN & SONS С D. 1668 Royalston Ave. Minneapolis, Minn. Always Insist on the Advertised Brand!

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HANDY MAN'S HOME MAN NC 144 Pages X E 800 Pictures How To Repair— Broken Furniture The Home Radio Set The Basement Furnace Home Plumbing and 1000 other items for the.ailing home How To Make— All-Stee! Auto Trailer World Wide Radio Colonial Furniture Toys and Games and other interesting home shop projects Get your copy now at your favorite newsstand or order direct from: 50: MODERN MECHANIX PUB. CO. Fawcett Building :: Greenwich, Conn. ALL EYES ARE ON THE MAN WHO LOOKS AHEAD € A MAN cannot conceal ability. And the man who is determined to go some place and is doing something about it cannot conceal that either. His associates feel it and his superiors recognize it. The man who looks ahead knows the importance of training, and other men who have looked ahead and gone some place know that I. С. S. offers the right kind of train- ing. Look ahead — mail this coupon! “INTERNATIONAL CORRESPONDENCE SCHOOLS Box 2323-M, Scranton, Penna. Without obligation, please send full particulars about the subject before which I have marked X: TECHNICAL AND INDUSTRIAL COURSES О Architect О Diesel Engines О Architectural Drafteman О Aviation Eng. О Auto Месћапіа П Building Estimating O Plumbing O Heating 0 Contractor and Builder О Air Conditioning Lj Refrigeration О Structural Draftsman D Steam Engineer О Structural Engineer О Steam Electric Engineer О Electrical Engineer О Marine Engineer О Electrie Lighting D) Civil Engineer [] Highway Engineer О Welding, Electric and Gas L] Bridge Engineer Lj Reading Shop Blueprints О Bridge and Building Foreman Q Telegraph Engineer О Surveying and Mapping О Telephone Work О Radio О R. К. Locomotives O Air Brakes O Mechanical Engineer OR. R. Section Foreman O Mechanical Dreftsman О В. В. Signalmen E] Machinist С Toolmeaker O Chemistry О Pharmacy О Patternmaker Dj Foundry Practice О Sheet-Metal Worker О Boilermaker O Coal Mining D Navigation О Cotton Manufacturing О Woolen Menufacturing О Heat Treatment of Metals О Agriculture П Fruit Growing D Management of Inventions O Poultry Farming BUSINESS TRAINING COURSES О Business Management D Lettering Show Cards О Induetrial Management O Stenography and Typing O Traffic Management О Civil Service О Mail Carrier О С.Р. Accountancy О Bookkeeping О Secretarial Work О Cost Accountant О Salesmanship О Service Station Salesmauship О Mlustrating O Business Correspondence О Cartooning DOMESTIC SCIENCE COURSES О Professional Dressmaking O Millinery end Designing О Foods and Cookery О Home Dressmaking О Tea Room and Cafeteria D Advanced Dressmaking Management, Catering D Signa О Railway Mail Clerk О Grade School Subjects П High School Subjects D College Preparatory O Advertising C First Year College Subjecte О Spanish Lj French Name... Age. Address... Present Position m if you reside in Canada, send this coupon to the Internationa Correspondence Schools Canadian, Limited, Montreal, Canada When Answering Advertisements Please Mention August Modern Mechanix 23

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Editors Note: not require special research or involve trade secrets, Naines and addresses of manufacturers of new products de- scribed in this issue can also be obtained free upon request. Enclose a self-addressed and stamped envelope for Your questions will be answered personally and free of charge by MM experts provided they do reply. Address: PREVENTING SOLDERING IRON CORROSION The copper tip on my electric soldering iron is constantly getting dirty. In fact, corrosion accumulates faster than I can remove it with a file. Since the soldering tip is very small, the metal is wearing away so rapidly that it will be of little use in a short while. Can you suggest some way in which I can prevent this excessive corrosion from taking place?—Andrew Vena, New York City. If the tip of your small electric soldering iron corrodes rapidly the trouble can, in all probability, be traced to the wrong kind of flux. Acid soldering pastes or salts should never be used on the tip of small soldering irons. These irons were designed for light work only, therefore only rosin flux should be used since it is non-corrosive. For radio, electrical and other light soldering, a rosin core solder should be used. This solder, marketed in spool form, contains the flux in the hollow center of the wire solder. Not only is it very convenient to use, but it protects the tip of the soldering iron against excessive corrosion. SUBSTITUTING DIFFERENT COILS AND CONDENSER IN SHORT WAVE RECEIVER I am planning to build a simple one-tube regenerative receiver similar to the one which appears in the MM “Radio Builders’ Manual," but would like to substitute a 100 mmfd. tuning condenser and matched set of coils for the 60 mmfd. condenser called for in the original circuit. Can I do this without effecting any radical changes to the original circuit?—Morris Мау, Buffalo, New York. If the receiver is, as you say, a simple one tube regen- erative affair, you can substitute a 100 mmfd. tuning condenser and a matched set of coils for the condenser and coils originally called for in the plans which appear in the “Radio Builders’ Manual" The use of the substitute condenser and coils will result in slightly sharper tuning, whereas stations can be more easily separated with the 60 mmfd. condenser as suggested in the original circuit. BUILDING A TRACTOR FROM “Т” FORD In the Editor's Workbench department of the June issue there appeared a homemade tractor which interested me very much. Can you tell me where I might secure plans so that I can build a tractor similar to the one mentioned? —E. C. Van Zandt, Battle Creek, Michigan. 24 Problems Editor, Modern Mechanix Publishing Co., 1501 Broadway, New York City. While plans are not available for building the tractor which appeared in the Editor’s Workbench in the June issue of MM, plans are available on the building of a similar tractor from a model T Ford. This tractor is capable of handling heavy work since it employs both the original transmission and an auxiliary, the latter being salvaged from a four cylinder Dodge car. A novel feature of this Ford tractor is that it can be used with either tires or cleats. Its total cost should not exceed $25. Complete plans for building this tractor will be found in the “1937 Handy Man’s Home Manual,” copies of which can be pur- chased from Modern Mechanix Blueprint Dept., Fawcett Bldg., Greenwich, Conn., at 50е postpaid, AUTOMOTIVE MEANING OF "TORQUE" Will you furnish me with an explanation of the word "torque" as applied to automotive devices? I have noticed that automobile engines are claimed by their manufacturers to develop so many foot pounds per minute. How is this torque computed?—Rex Hockett, Caldwell, Idaho. Torque is the product of force multiplied by the distance at which it is exerted from the center of rotation. When a manufacturer claims that his car developes 83 ft. pounds torque, he means that at a distance of 1 ft. from the center of the crankshaft the engine would exert a force of 83 pounds, or at a distance of 83 ft. from the center of the crankshaft the engine would develop only 1 pound. To simplify this, let us suppose that a 1 ft. wrench were attached to the crankshaft of the car’s engine and the wrench held firmly so as to stall the motor. In order to accomplish this, 83 pounds would have to be exerted jn order to stop the engine. But by increasing the length of the wrench handle to 83 feet, the motor could be stalled by exerting only one pound of force. PLAYING PHONOGRAPH RECORDS THROUGH . RADIO. SET I would like to use my radio receiver for reproducing recorded music. Can you tell me how to connect up a phonograph pick-up to a radio?—F. Е. Ulvinen, Aurora, Ohio. A phonograph pick-up of the high impedance type can be connected in many radio receivers without making any changes to the wiring of the set. Connect one of the insu- lated wires, extending from the pick-up, to the plate prong of the receiver’s detector tube. If the set employs both

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a first and second detector, connect this wire to the second detector’s plate prong. The remaining wire is then con- nected through a 25,000 ohm volume control to the chassis of the receiver. The volume control should include a switch so that the phonograph pick-up is disengaged when not in use. MAKING AN AQUARIUM CEMENT I am planning the construction of a glass fish aquarium and would appreciate some information regarding a suitable waterproof cement which could be used for fastening the corners in place. Can you furnish a formula that will meet my requirements?—Lyman Armstrong, Lexington, Ten- nessee. For an aquarium of moderate size, automobile window glass is advised. This should be cut to the desired size and inserted in a frame formed from Y by !4 inch angle brass. Solder the frame together and then insert the glass sides. Anchor these in position with a cement made from the following ingredients: litharge 22.22 eae ea 3 ounces Fine white sand ............ 3 ounces Plaster of Paris ............. 3 ounces Powdered rosin ............. 1 ounce Linseed oil and drier. Enough to form paste. Mix the first three ingredients together then dissolve the rosin in the linseed oil and add to make a paste. Last, add a small amount of drier and mix the resulting cement thoroughly before applying it to the glass. By first coating the metal corners with a sufficient amount of cement and pressing the glass sides into position the possibility of leakage is reduced to a minimum. If leaks develop later they can be quickly stopped by application of more cement. CASE-HARDENING IRON AND STEEL Can you furnish me with a formula for case-hardening iron and steel? I have a number of articles which I would like to treat in this manner, but do not know just how to proceed.—Alonzo Franklin, Dallas, Texas, Case-hardening iron and steel is not difficult although due care should be exercised in mixing the chemical bath into which the article to be hardened is submerged. The formula for the bath consists of the following chemicals: Table salt Potassium cyanide parts by weight parts by weight Potassium bichromate 0.8 parts by weight 0.15 parts by weight 0.1 parts by weight Broken glass Potassium nitrate Powder the broken glass and mix it and the chemicals together thoroughly. Heat the metal to be hardened until it attains a dull red color, then submerge in a water bath to which has been added the hardening chemicals and glass. The metal to be hardened should not be overheated if best results are to be obtained. The metal hardening operation should be performed only in a well ventilated room. Be careful not to inhale the fumes. LEARN TO = AT HOME!] ITS FUN TO LEARN THIS В -WAY-AT НОМЕ * IN. 2/40. YOUR SPARE TIME, 1 |^ 2 ` N BE AN ARTIST and be your “отп boss”, There’s a big future in this fascinating, ? profitable field for men and women who are well-trained Artists. You can learn at home in your spare time this helpful, practical way. COMMERCIAL ART CARTOONING лм. DESIGN AU in ONE Practical Course For 23 years our method of instruction has proven successful, Today it is even more complete and strictly up-to-date. You start by drawing straight lines, and in advancing from lesson to lesson your drawings are given the correction and criticism of an experienced Art instructor. A few Pleasant hours a week should give you the ability to earn good money later on. MAKE $30, $50, $75 A WEEK Enjoy The Better Things In Life ar , 2 v Л) с GET MARRIED Many of our graduates are enjoying a ‘new life" thanks to W. S. A, training. Margaret Kessell of New York earned $125 in one week doing free lance Artwork. Mr. L. Haymond of Florida says, ''Course paid for before completed." There's big money waiting for YOU—and sending for our FREE BOOK will help toward your career as a successful Artist. ?2»ARTIST OUTFITS GIVEN! e d Two full-sized Out. fits given with the course. Including everything you need to get started— drawing board, pens, brushes, paints, paper, etc. Mail coupon today for complete des tails. REE BOOK shows how WASHINGTON SCHOOL OF ART Studio 208A, 1115—15th Street, Ne W. Washington, D. C. Without obligation, please send me ё BRED eopp ef sour Book, ‘Art for Pleasure and Profit”? аге.......... Маше. secccccccvecccccvescccsacccecscnnes Address State... eee СЦ... зоо сео ово юовани (No salesman will call) haunnuumuumuuumumuR When Answering Advertisements Please Mention August Modern Mechanix 25

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allt in al), un | T FREE! ON APPROVAL 5 VOLUMES BRAND NEW EDITION Only 15 minutes a day with these WON- DER BOOKS can prepare you for a good drafting job In less than a year. Mechani- cal and architectural drafting from simple Straight lines to important complex plans, A step at a time! Built especially for be- ginners, for men with only grammar school- ing. Drafting room practice, PLUS EN- GINEERING, made easy and clear. In- For Beginners Written, understand every word, by 22 well known engi- so you can neers and architects. DeLuze flexible binding, ‘cludes complete course іп hlue-print nearly 2,000 pages, reading. " 1546 blueprints, charts Big Field Big Demand Big Pay and diagrams; prepares you for a Sood drafting Job in mechanical or reht OR DRAFTSMEN HAVE architectural lines. Sent THE BEST CHANCES FOR ADVANCEMENT. for 10 days’ free exami- Pleasant, fascinating work, easy to learn and nation if you mail do. Learn quickly with these books—send eoupon immediately. coupon for a set and see for yourself, а wenr's consulting Е in the merican echnica octely now n и ole ] Included Competent draftsmen are urgently needed right now in all bullding and manufacturing lines at $30.00 to $75.00 a week. That's just the beginnIng—F drafting, Many say that it is worth more than the cost of the hooks. Complete set of drawing Instruments it you send for these drafting books NOW, These instruments are made of the finest of German silver, are absolutely accurate and are packed In velvet lined leatherette pocket case. Real $10 value, but included with these books. AMERICAN TECHNICAL SOCIETY т Е a Dept. DC320, Droxel at 58th St., Chicago, IN American Technica! Society, Dept. DC320, Drexel at S8th St., Chicago, НІ. Send for 10 days’ trial New 5 volume set of drafting. I will pay the few cents dellvery charges. If I wish, I may return books in 10 days and owe you nothing. but If 1 decide to Keep them, I will send $2.00 after 10 days, then only $3.00 a month until $24.80, the adver- tising price, 1s paid. , Send latest edition and include drawing instru- ments and membership certificate. Address. Attach letter stating age, occupation, employer's that of at least one business man ав a reference. Does many jobs speedily, easily—grinds, drills, engraves, sharpens, routs, carves, polishes, etc. Universal motor—about 20,000 R.P.M.—plugs in any light socket A. C. or D. C. Handles as lightly as a pencil. Weighs only 6 oz., yet is amazingly powerful, Oilless — self-aligning — ball thrust bearings. TEN DAY TRIAL. Satisfaction guaranteed or money back. 20 pc. general utility tool set $5.75 extra. Send for FREE BOOKLET. N DREMEL MFG. CO., Dept. 1020-CT, Racine, Wis. GAS MOTORS FREE finished, Never in the history of gas en. ЕД mount- gines was a motor ever offered ed fly wheel at so low a price. АП America КА withevery has acclaimed this engineering tri- umph—accomplisned by outstand- ing G. Н. Q. designers and engl- neers after years of exhaustive, Scientific, aercdynamic research. Has broken all records for amazing per- formance. Flies model planes up to 30 ft. wingspread. Also used for boats. And look at all these extra features! Easy starting—just a twist of the wrist. Steady Tunning—runs 27 minutes on ounce of gas. Precision, replaceable parts. Cylinder and Piston Lapped. Longest crank shaft ever made on miniature motor. Chrome nickel steel shaft with 114” bearing surface. Connecting rod of high speed bronze. 1 horse power at 3000 to 7000 R. Г. М. This famous motor complete, entirely as- Sembled on a stand. Tested and run before shipment— erformance guaranteed. No oil, gas or batteries in- eluded, Only $12.50 postpaid. One Day Service, Tilus- trated catalog 3c. G.H.Q. MODEL AIRPLANE Co. 854 East 149th St. Dept. A New York, N.Y. New Filament Betters Lamp NEW high-efficiency tungsten filament which will increase the light output of incandescent lamps 10% without using addi- tional electrical current has been developed by a leading manufacturer, climaxing 24 years of continuous research. A “lighting bonus" or saving of over 16-million dollars to the public through use of the new filament is forecast. І | When installed in a lamp, the new filament is mounted as a cross-bar between two lead- in wires, with one support in the center of the filament, instead of being looped around three supports, as was the practice formerly. Since the effective length of theeew fila- ment, as shown in the accompanying photo, is only about one-half that of the old, there is much less cooling by the gas within the lamp, permitting the lamp to give 10% more light for the same amount of current. The gas employed in the new lamps is a mixture of nitrogen and argon. Aero Clubs Increase In U. S. LYING clubs are on the increase in the U. S, according to a report issued by D. B. Thomson, director of the National Aero Reserve, one of America’s leading semi- military aeronautical organizations. The report attributes the increase to the produc- tion of light planes of 40 h.p. which, through their low initial and maintenance cost, enable small groups of air-minded youths to secure training at low rates. 26 Accept No Substitutes?! Always Insist on the Advertised Brandt

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HOW TO BUILD TRAILERS THE BOOK THOUSANDS HAVE BEEN WAITING FOR | 128 PAGES 300 PICTURES | COMPLETE PLANS For BUILDING— Six Cabin Trailers Two Folding House Trailers Trailer Radio and Light Plant Delivery and Boat Trailers Trailer Interior Fittings and hundreds of trailer and auto shortcuts, kinks and camping tips Get your copy now at your с favorite newsstand ог order direct from: MODERN M MECHANIX PUB. CO. Fawcett Buil d ing i Greenwich, Conn. TESTED SYSTEM OF DIESEL AND GAS ENGINE TRAINING To qualify for a good Diesel job you must receive training in an institution that can offer you practical instruction. At National Schools vou actually work on the latest equipment, including practically every approved make of Diesel engine. You get the kind of instruction that serves your every day needs in the Diesel field after you have graduated, It’s the type of training you can “cash in” on. You are trained under the direct, personal supervision of licensed Diesel Engineers. Diesel Electric Power Generation A new feature essential to the complete training of Diesel ex- perts. Completely covers power generation. This extra course is now presented to all Diesel stu- dents without extra’ tuition. EASY-TO-LEARN MASTER TRAINING National Schools’ training is complete in every respect. It includes all phases of Diesel en- gines, fuel injection, gasoline, butane, propane and natural gas engines, also Auto-Diesel elec- trics, machine shop practice, bat- teries and other essentials that must be learned In order to give you well rounded-out training. LEARN IN LOS ANGELES The most delightful place to learn—Los Angeles—the play- ground of America. Fascinating surroundings. Your coach rail- road fare will be allowed to Los Angeles from any point in the . 8. Stu Diesel Etectri EARN ROOM AND BOARD We help students obtain parte time jobs to earn room and board while learning. ‘This pe i Diesel only for residents of U. S. Converted Ford Auto NATIONAL FREE | ype г National al Schools, Dept. 8-MMA, 8 g 4000 So, Figueroa St., Los Angeles | І кессон АСЕ... - | ADDRESS .....sescssseeeeeeeerenes Я —— Е ; СУ ВИИИ НАНЕ ЅТАТЕ............ г When Answering Advertisements Please Mention August Modern Mechanix 27

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BUILD YOUR OWN Electric Outboard Motor from old auto generator. We show you how. Lightweight—Clean—Silent. Variable speed from standstill to maximum makes it ideal for trolling or casting. Operates 8 to 12 hours on 6 volt battery. Many other important features. Dime brings complete plans and catalogue. > i LeJAY MFG. CQ. 1514 W. Lake Minneapolis, Minn.

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AT HOME You can learn by our modern and original system of Instruction every Part of the Watch repairing Trade at home. You can earn money while learning and prepare yourself for a_well paying position or start In business after completing our course of instruction, Good watch repalrers are |n demand and. generally earn very good salaries. Гог pare ticulars apply to the WISCONSIN SCHOOL OF WATCH REPAIRING 524 E. Mason St., Dept. C, Milwaukee, Wis. HAVE YOU SOME SPARE ROOM & basement or garage where you can do light work? We can offer you a profitable proposition casting new 5c and 10c Novelties, Ashtrays, Toy Automoblles, etc., as Manufacturer [or firm of many years standing. No experience necessary and small outlay starts you. If Inlerested in devoting your spare or full time to profitable work write AT ONCE as we are now closing arrangements for supply of our goods. METAL CAST PRODUCTS CO. 1696 ton Road, New York, N. Y. CITY

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) Motors, ебе. TRUR, ©) Y BILD-UR-OWN DEVICES FOR PRICES Most educational hob bg 5237 Lake St. Dept. 87 Chicago, 111. any boy can have! 29 pleces a a È genuine commercial apparatus. Illustrated manual shows how to build radio circuits, 110-volt motor, extension : hone, th у + Bove, olee. door tock, ‘generate altri violet T€ 3 QU TRAILER ENGINEERING AC to DC rectifier, scores more. Value$14. ONL "$3.99 а = (Second Edition) 6 Books Yale $4.50, given with kit. Radlo-Elec. 4 1 ù BRAND NEW BOOK Short Courses, etc, Complete value $18.50, рез s x (SEY To Help You Buy or Build for only $3.99. Price back if not pleased. Order now, 14 chapters, 130 illustrations. Proven plans for 10, 14, 17, and or get free book! ELECTRICA " i T LI = Box 524 A47, Lincoln, Мере, 21 foot trallers. Tells you about bob, roll, weave, snaking, nose х diving, rear vision, Ackernnn steering, tandem wheels, tow car е balance, trailer balanee, all State laws, American coaches, English earn 1 ie coaches, plumbing, wiring, brakes, step action chassls, parking jacks, welghts, furniture, ironing the tow car, every engineering detail. Get е unvarnished trailer enginzering facts before you buy ог build. Order pea ing NOW. $1.00 postpaid, 51.15 C. O. D. RAY KUNS, Dept. 8, 8 Eastwood Circle, Cincinnati, Ohlo MEN—WOMEN—EARN MONEY Make colorful glazed concrete pottery without molds, Kga New easy method. 2,500 designs, Jars, birdbaths, sa tiles, statuary, giftware, souvenir goods. Money- making ‘employment. No experience needed. Send 10с TODAY for booklet, color plates, details. NATIONAL POTTERIES COMPANY 13 W. 26th St. Room 26, Minneapolis, Minn. IT RIT GOVT. JO hiat at s Thousands of openings yearly. Men-women, age 18-50. Start $105-$175 month. Get ready now for

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SPORTSMEN'S Manual —NEW 1937 EDITION— No sportsman should be without a copy of this all-new edition of the Sportsmen's Manual. |f you hunt, fish, camp or indulge in other outdoor sports you will find in it numerous articles to meet your particular fancy. In addition to its many out- door features the new 1937 edition contains RESERVE YOUR COPY NOW building two sportsmen's trailers, two boats and many kinks and short cuts C for the outdoor man. AT YOUR LOCAL NEWS- STAND OR ORDER DIRECT 250 PICTURES MODERN MECHANIX PUBL. CO. Fawcett Building Greenwich, Conn. When Answering Advertisements Please Mention August Modern Mechanix 29

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by James Nevin Miller N THE city of White Plains, N. Y., not so long ago, more than 700 people suddenly were stricken with a mysterious ailment. City authorities thought the case was food poisoning. But just what kind, puzzled them. True enough, it was learned that all the vic- tims had eaten chocolate eclairs, cream puffs or Boston cream pies. However, none of the custard-filled pastries appeared to be “spoiled” although it was suspected that con- taminated custard filling might have been the source of the poisoning. Therefore, the city officials turned over samples of the pastry to the New York office of the U. S. Food and Drug Administration. These Gov- ernment experts in turn sent the pastry to the Washington laboratories of the Administra- tion. Very quickly, the Federal investigators, aided by local authorities cleared up the sit- uation by tracing the source of the spoiled food to one manu- Is your ginger ale fit to drink? B. Wilson, a Federal expert chemist (center), can tell you. He is shown conducting a test to de- termine the purity of a soft drink. Right-—Spoiled sea foods are some- times offered for sale, but not if B. A. Linden, bureau bacteriologist, can help it. Samples of sea food are collected regularly and sub- mitted to laboratory examination. 30 The U. S. Food and Drug Administration constantly labors to insure the quality of food products. Through the efforts of its field in- spectors and expert labo- ratory technicians, the Fed- eral bureau tracks down poisoned foods that consti- tute a threat to the nation's health. Left — A Federal chemist using special ap- paratus to determine the condition of canned goods. Modern Mechanix

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of th "His nose knows.” This Federal agent can tell in a few seconds whether or not a shipment of powdered eggs is in satisfactory con- dition by merely smelling the product. However, to make doubly certain he will take along samples to be scientifically tested in Food and Drug Administration laboratories. All to safe- guard your family’s health. ud facturing bakery in Westchester County, seiz- ing and destroying all shipments sent out on the same day as the food poisoning outbreak, and identifying the deadly bacteria that caused the large-scale illness. Thrills are commonplace to these health sleuths, who are known unofficially as Uncle Sam's “Poison Squad." Their job is to guard the safety of your pantry by tracking down, armed with ingenious laboratory and field methods, outstanding cases where moldy fruits and vegetables, contaminated sea foods, spoiled canned goods, and doubtful-looking p ; d imported edibles offer a serious menace to the Deadly Bacillus linus; magnified 1,000. im 1 health of the nation. о ов po E Just a few of the Poison Squad's recent ected (uM Ae million ore achievements, besides the settlement of the poisoned pastry case, include: the rounding up, during a three months period, of nearly a quarter million shipping cases of canned salmon, an apprecia- ble percentage of which was spoiled; the investigation of a food poisoning outbreak in Philadelphia somewhat similar to the one at White Plains; and the discovery of the cause of a strange “epidemic” of the “Looks mighty suspicious,” says this laboratory expert as he pro- ceeds with tests to determine whether a can of corn is safe for your palate or whether it is teem- ing with health-destroying bacteria. Poisoning from canned foods has decreased greatly since adoption of improved canning methods, but the Federal chemists are vigilant. August, 1937 31

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now might be eating apple butter or apple jelly containing lead or arsenic. Recently a jury, after studying a thorough investigation by the Federal food sleuths, found a big fruit company in the state of Washington guilty of a violation of the Food and Drugs Act in shipping interstate stocks of apple scrap which contained residues of poison- ous lead and arsenical sprays. About 46,000 pounds of the scrap had been seized by the undercover men assigned to the case. Surprisingly enough, nearly one- third of the time, money and effort expended by Uncle Sam's food policemen is being devoted to [Continued on page 149] Dr. A. C. Hunter, chief bacteriologist of the "Poison Squad," is shown (below) preparing a toxin of health- destroying bacteria that sometimes cause outbreaks of food poisoning. Of.elf foods fish is usually quickest to spoil, so Federal food inspectors spend a great deal of time in examin- ing fish markets. Ordinary spoilage can be detected by odor or color. parasitic disease known as trichi- nosis, at Williamsville, N. Y. Seizure of poisonous, decom- posed or filthy foods is like stop- ping a murderer's bullet in flight, says Dr. A. C. Hunter, chief bac- teriologist of the Poison Squad. Oftentimes such seizure has been criticized as only a worthless ges- ture that may be compared to the arrest of a murderer's revolver after it has slain its victim. Dr. Hunter does not agree. He says it is better to protect the public health ‘by confiscating dangerous foods be- fore they can cause injury than it is to prosecute after the damage is done. Seizure is the prompt and effective weapon which is the first reliance of the Food and Drug Ad- ministration. Were it not for the vigilance of the Poison Squad your family right :32 Modern Mechanix

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New Navigation Computer Solves Flight Problems IMPLIFYING aerial navigation problems to a point never before possible, an en- tirely new type navigation computer has been perfected by engineers and adopted as stand- ard equipment by many pilots on the nation- wide air travel systems. Designed to provide an immediate answer to navigation questions the pilot must face during the course of a flight, the new instru- ment combines features of a slide rule with a series of special scales in the form of three celluloid discs which rotate around а common center. By means of this instrument the pilot may determine immediately the true air speed of the plane, the compass course which he must follow, gasoline consumption and the flying time between terminals. It can also be used to calculate wind direction and velocity while the plane is in flight, allowing the pilot to keep an accurate check of upper air infor- mation provided at the beginning of the flight, New Slide Rule Aids Printer Circular slide rule for solving problems involving type, cuts and space to be filled. Device supplies easy and rapid means of obtaining answers to questions arising in the printing art, COPY fitting device determines quickly what size and faces of type will fit a definite copy space. It also tells how much space a certain amount of copy will require jn any type face. Used by many printing concerns, it will also answer the problem of what size cut any photograph or drawing will make. August, 1937 New type navigation computer in use during flight. With this instrument the Pilot may quickly determine answers to flight problems arising during the course of the trip. Fluoroscope Used On Dog HE value of the flouroscope in animal surgery was demonstrated when a foreign body was removed from under the skull of a German shepherd dog. The success of this delicate operation was credited largely to the use of the fluoroscope. The animal was given a general anesthetic for the operation. A complete recovery was made and now the dog is at home with his mistress. Today the X-ray and fluoroscope has become almost a necessity for veterinary surgery. A German shepherd dog, Benjie, being fluoroscoped for a Skull injury. After determining the extent of the injury, vet- erinary surgeon removed a foreign body from under the skull. 33

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Oysters Grow on Mangrove Trees

i Nic Sprank Offers $5.00 For Best Oddity OYSTERS GROW ON TREES/-THE RED MANGROVE TREES GROWING IN THE EVERGLADES NATIONAL PARK. FLA. ARE PARTLY UNDER WATER WHEN THE | TIDE ISIN, AT TIAS TIME THE INFANT OYS TERSTAKE HOLD OF THE ROOTS AND CLING. WHEN THE TIDE FEET FROM THE WATER. Sirs RE S Јод, fatrvien, Oti. A 400,000,000-POUND B HOTDOG MEAL/THAT IS TUE ANNUALWEIGHT OF FRANKFURTERS* CONS UMED INTHE ITED STATES. 2 NEW EDIBLE SEAMLESS CELLULOSE TUBING USED TO COVER THESE IS PRO- DUCED ATA RATE, THAT IF 1TWEREALLOFONESIZE, IT WOULD BE LONGER THAN 500 MILES A DAY. d A Hall, Ийи,

АЗЫ STATION 100 MILES FROM 2: ARAILROAD/~ INTHE GHOST MINING TOWN < OF RHYOLITE,NEVADA, ARAILROAD STATION WAS = BUILT WITH THE EXPECTATIONOFARAILROAD -7 AY BEING BUILT IN THE NEAR FUTURE. THE STATION _ й WAS COMPLETED BUT THE RAILROAD NEVER MATER- IALIZED BECAUSE OF THE SHORT LIFE OF THE TOWN,

60 MILES ANHOUR/ THE OSTRICH IS PERHAPS THE MP SWIFTESTOF ALLLAND ANIMALS, . CAPABLE OF RUNNING ATASPEED OF GO MILES AN HOUR.ITS VOICE IS LIKE THE ROAROFA LION, -Archard Bengston, Илии ул ўа вит y War и”

Five dollars will be paid for the oddity used by Nic Sprank as his central illustration. One dollar will Бе paid for all others used on this page. Send your oddity to Nic Sprank, Modern Mechanix Publishing Company, 1501 Broadway, New York, N. Source or proof of each oddity must be given. Send all oddities separately, not with other manuscripts or letters, 34 Modern Mechanix

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ECLIPSE BEGAN AFTER IT ENDED eme SA SHADOW OF “Se = PARTIAL , ECLIPSE EN EE. a UT SCIE LACKED A FIXED BASE FOR THEIR INSTRUMENTS - К INTERNATIONAL | { BATE LINE 2 NEAR SITE OF ANCIENT INCA SUN WORSHIP IN PERU, OB~ SERVERS OF THE HAYDEN PLANETARIUM~GRACE EX- PEDITION AWAITED THE ECLIPSE WHICH HERE LASTED THREE AND ONE HALF MINUTES MAJOR AW. STEVENS PHOTOGRAPHING FROM AIRPLANE — POLAR AXIS MOUNT PARALLEL TO EARTH'S AXIS CLOCKWORK—»-. E e SOCIETY S CANNON CAMERA -14- FT. LONG-FOCAL LENGTH- 19 FEET | sunrise, -MEMI s JUNE 9, ` 4 ECLIPSE | BEGAN HEN the shadow of the moon traveled across the earth at 2,000 miles an hour on June 8 and 9, astronomers were given the longest observation time in 1,200 years. But with the fickleness for which it is known, nature provided no firm foundation on which observation equipment could be set. The total eclipse was visible for more than seven minutes at the 130-degree meridian, but astronomers were unable to set up equip- August, 1937 CAMERA. MERIDIAN 70 Quum HOW THE ECLIPSE BEGAN THE DAY AFTER IT ENDED ment on a more substantial foundation than the Pacific Ocean or the deck of a boat. The unusually long eclipse duration was caused by the earth being almost at its great- est distance from the sun while the moon was. almost at its shortest distance from the earth. To take advantage of the longest possi- ble time, astronomers set up equipment on Enderbury Island and on the coast of Peru. : 35 INTERNATIONAL DATE LINE — END OF TOTAL ECLIPSE, MERIDIAN 180° SUNSET, JUNE 8 ———»

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At Langley Field, Va., the National Advisory Committee for Aeronau- tics maintains amammoth wind tunnel in which a completely assembled airplane can be tested to determine its aerod y- namic qualities (above). Driven by engines pro- ducing 4,000 horsepower each, two 351-foot pro» pellers blast the air past the airplane’s controls at velocities up to 118 m.p.h. The tunnel is 43415 feet long, 222 feet wide, 97 feet high. by Don Glassman OBODY knows how long the present speed marks can endure. In a world of sudden change and far-reaching discoveries, the mortality rate of speed records is high. All the racing heroes want to hang up un- beatable records. Gradually, but surely, they have been approaching the speed beyond which they cannot go, for there is a law which no speeder can break. Nature laid it down without consulting us. A 575-mile per hour speed limit for mod- ern airplanes was recently determined at the Langley Field, Va., "super-speed" wind tun- nel by the engineers of the National Advisory Committee for Aeronauties. With present designs, you may be sure that no man will surpass that figure. Beyond the 575-mile critical speed, forward motion is checked by a "shock wave" of 36 Major James (“Jimmie”) Doolittle, famous American speed and stunt pilot, conducted risky flight tests that helped determine the ac- celeration speeds of various aerial maneuvers. Modern Mechanix

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A too-sudden change in acceleration while testing a new Navy plane is believed to have caused Jimmy Collins, well known test pilot, to become uncon- scious, resulting in the crash that caused his death. turbulent air that travels from front to rear of an airplane wing and wastes the energy. Result:—the wings lose their lifting power. In engineering language this "shock wave" of air is called the “compressibility burble." The violence and turbulence of the burble August, 1937 In the Macchi-Castoldi-72 seaplane shown above, Lieut. Francesco Agello, Italian ace, set a world’s speed record of 440.67 m.p.h. in 1934. The plane’s 3,000 h.p. Fiat engine had tandem propellers re- volving in opposite directions to eliminate torque. causes a severe drag on the wings. The power that was intended to support the wings is spent as useless heat. The burble is not a factor in airplane speed until the free stream of air approaches the velocity of sound—750 miles per hour. With each increase in speed, the burble travels farther from front to rear of the wing, and dissipates still more energy as heat. If we eould travel beyond 750 miles per hour sound waves could never catch up with our flight. That would be "supersonic" speed. These facts hold good for the types of air- plane wings in use today, and it is highly probable that a corresponding burble could be found for every common form of trans- port if desired. : With suitable wind tunnels, one could de- termine the critical speeds of ship, train, auto, and dirigible forms, but at the present stage of development there is no point in making such experiments, since all these transports are still very far below their respective criti- cal speeds. With the airplane, however, the speed record now held by Italy stands at 440.67 miles per hour, only 135 miles per hour below the critical speed. The Speed School at Densenzano, Italy, has specialized in the training of crack speed pilots for years. Premier Mussolini told these men to work for a velocity of 600 miles per hour. In the light of present knowledge about 37

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the burble, the Italians seek to invent a new type of air foil with a higher critical speed. And that is not impossible. What about man’s own engine? Do our bodies have a critical speed? As I sit on my chair, I am being whirled through space at the dizzy velocity of 1,140 miles per min- ute—the earth’s speed. It is said that 36 dis- tinct motions are involved. Nobody feels any ill effects from this pace, although it is far beyond the critical speed of the airplane. There is quite some difference, however, between traveling through space with Mother Earth and traveling at 400 miles per hour in an airplane. In our joy ride on the earth we do not turn sharp corners or experience sudden accelerations. Traveling along a straight line at any speed seems to make little difference to our bodies. But the experience of speed pilots tends to show that taking curves at high speeds is something positively annoying, and probably injurious, if carried to extremes. B The "blank out" experienced by speed and test pilots is a sensation caused by the blood rushing away from the head, creating a short- age of oxygen. In highspeed aerobatics, the centrifugal force makes one’s body feel much heavier than it actually is, and one finds it difficult to raise an arm or to stand up. To counteract this sudden drain of blood from the head, test pilots wrap their bodies in bandages, or tight belts. Sudden acceleration and quick change in direction are the chief difficulties man has to contend with when attempting to set new 38 Designed, built and flown by Comdr. Frank Hawks, noted speed pilot, the airplane shown above lived up to its name—Time Flies—by attaining speeds exceed: ing 300 m.p.h. before it was wrecked in landing. The craft featured an air-cooled engine of 1,150 horsepower. seaplane (right), Major Alford Williams hoped to win the Schneider Cup for the U. S. in 1929. Unfor- tunately, the plane was damaged Бе- fore the race and could not compete. | In this Mercury Speeding along a straight path seems to have no ill effect on the human body, but a sudden change in direction or acceleration, as sketched at left, causes a speed pilot’s mind to "blank out."

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1915 speed records. To visualize what hap- pens in a case of extreme acceleration: if an airplane could take off with the acceleration of an automobile piston, the pilot’s effective weight would become 20 tons and his body would flatten like a pan- cake. A burst of speed can break a man’s neck unless he has a solid head rest. A free body falling in space falls 16 feet in the first second of its descent and gathers speed at a rate of 32 feet per second. This rate of fall is called one-gravity. If the ac- celeration is increased to about three times Exactly 7 hours, 28 minutes and 27 seconds after he zoomed aloft at Los Angeles, Calif., in his specially built speed plane (above), Howard Hughes, wealthy sportsman pilot, landed at Newark, М. J., having averaged 332 m.p.h. for the 2,490-mile flight. = Hughes is shown walking at the tail of his plane as it was wheeled into a hangar. Below—Chart showing the steady climb in speed records since 1910. d | [9:24 oka E + ES— CRITICAL SPEED FO 126 | л! the normal acceleration of gravity, you ap- proximate the takeoff speed of an airplane launched from a catapult. An acceleration of three-gravity is 100 times the normal ac- celeration of a steam locomotive. An auta- mobile starts off only one-sixth as fast as the catapulted airplane. Some interesting discoveries in the field of [Continued on page 122] 39

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Above—-Folding the. fold- ing trailer. Side pieces fold down to floor and top comes down and covers both pieces as all three fold: against sides of per- manent structure. Ease of folding makes arrangement convenient for getting under way when ready. At tight is shown the trailer ready. to proceed юп its journey. The two extra rooms have been folded up for traveling and trailer appears to be the conven- tional type, When it ar- rives at new location, a few minutes work will produce the two additional rooms. 40 Above—A new three-room house capable of rapid con- version into a conventional type trailer. | William В. Stout, inventor and de- signer of the convertible | trailer, is shown ‘seated in one of the three rooms. When sides and bottom are folded up, house more nearly resembl conven- tional trailer. hen fold- ing sides are placed ^in position, this home ‘on wheels gives. more. room than usually, is available. Floors are“ raised | above ground, thereby increasing comfort. of the. inhabitants.

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Trucks Remove HE Mexican freight steamer ‘‘Sinaloa,’’ strike-bound , with no crew to man her engines, was blown ashore at Terminal Island, Calif. in a heavy gale. Because her bottom plates were so badly dam- aged by the beating taken on the jagged rocks, salvagers decided that the cost of re- pairs and refloating her would be more than she was worth. To remove the cargo, piles were driven and a trestle constructed out over the beach to her side. A large hole was cut in the hull and with the help of stationary engines rigged on the trestle, the cargo was loaded on trucks and hauled. ashore. Flash Bulb Has Wire Element HYDRO- LANIUM wire flash bulb recently brought out is reported to give 50 per cent more illumina- tion than the foil type. An exactly measured wire diameter pre- determines the timing charac- teristics of the flash, and the measured length of the wire pre- determines the light intensity. Because of the measured light control, it is pos- sible to lengthen the peak intensity so that the flash is longest at its brightest point, thus throwing more light on the photographic plate when the shutter is open. The light peak of this bulb occurs within 26 to 28 milliseconds after current is turned on. Uniform flashing qualities are ob- tained by exactly measured wire length and diameter. "Safety spot" denotes presence of eir in bulb. Cargo From Wrecked Freighter Mexican freight steamer on rocks of Terminal Island, Calif. "Trucks travel to ctaft by trestle, where cargo is loaded through ole cut in hull. Danger to workmen brought high wages. New Saw Operates By Lever NEW type saw, capable of cutting a tree close to the ground while being operated from a standing position, recently has ap- peared on the market in Germany. Operating the handle with a side-to-side motion causes the saw to move in a.corresponding direc- tion. Lever-operated saw cuts close to the ground and is operated by workman in standing position. Gears transfer power from lever to semi-circular saw blade. Spring maintains blade pressure. 41

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The nose already a mass of burning wreck- age, the flaming tail of the giant German Zeppelin Hindenburg settles to earth after exploding while landing at Lakehurst, М. J. Naval аш base on May 6th, 1937. O MOST of us Earth-bound mortals, there is something singularly terrifying about death from the sky. The only terror equal to it is death from fire. When the two horrors are combined in one spectacular disaster such as overtook the airship Hindenburg, we of panicky imaginations are prone to ignore facts, prone to throw up our hands and cry, “That is enough!” Yet the men who must face this fate again if airship progress is to continue are far from ready to cry enough. Every uninjured sur- vivor of the Hindenburg crew hurried back to Germany, that he might get a berth in the next great Zeppelin, the LZ-130, rapidly nearing completion. And this attitude is not mere heroics. Air- ship men really believe that the rigid dirigible is a reliable means of transporta- 42 tion. Disasters? Of course they encounter disasters. “What mode of transportation does not?" is their argument. And they make a pretty good case for the airship, too. They will tell you, for instance, that dirigibles have carried more than 250,000 paying passengers, yet up until the time 12 of the 36 passengers on the Hindenburg’s last Modern Mechanix

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Ciouds of smoke still rise from the twisted steel frame (above) of the ill-fated air- ship as rescue workers аг- tive to search for possible survivors. The Hinden- burg had just completed her 21st crossing from Germany to the U. S. when the tragedy that caused the world to gasp in horror oc- curred. Right-—Aerial view of the airship’s charred re- mains at Lakehurst base. August, 1937 any airship had ever lost his life. 66 members to a fiery death. by Bob Gordon trip were killed at Lakehurst, not a single passenger of You don’t believe this? Well, here are the figures. On the three commercial Zeppelins built and flown before the World War, 37,250 passengers were carried without even a serious injury. Immediately following the war, the Nordstern and the Bodensee carried several thousand passengers before being seized by the Allies. .Goodyear blimps have carried 180,000 passengers in perfect safety, while the Graf Zeppelin and the Hinden- burg carried 16,000 on regularly scheduled runs. As to crew casualities, aside from one blimp pilot and two members of a ground crew killed when their ship was wrecked in a violent gale, after being torn from its moorings, no crew member of a commercial ship had been killed before the Hindenburg carried 24 of its There have been only 156 large rigid dirigibles built in the history of the industry. Twenty-nine of these were built and flown in Germany before the war. Several of the first ones were wrecked, but no one was killed. Count Zeppelin, a balloon observer for the Union Army in the American Civil War, devoted practically his entire lifetime to building and flying

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dirigibles, and died a natural death at the age of 76. During the war, Germany built 104 and England 14 large airships. Sixteen German Army ships were lost in action, including four that were sabotaged while in their hangars; two bombed by British planes while on the ground, one blown to sea in a gale, and five stranded—two in enemy territory, three in Germany. Only four were shot down in flames. The rest were dismantled because they were obsolete, had been badly damaged (although able to return home), or to prevent confiscation by the Allies at the close of the war. Since the war, Germany has built four large rigid airships, the United States three, and England two. No other country has ever built this type of craft. Of Germany's four, the Los Angeles was retired after many years of safe use. The Graf Zeppelin is still in regular service, hav- ing made more than 500 flights without ac- cidents. The Dixmude disappeared over the Mediterranean after being turned over to an inexperienced French crew. The Hinden- burg was destroyed while landing at Lake- hurst, when exhaust flames from the motors or static electricity probably ignited hydro- gen gas as it was being valved. Of the two English ships, one broke in mid- air, due to structural weakness and burned. The other was driven into a hillside during a rainstorm. Of the three American-built ships, the Shenandoah broke in two during a thunder- storm. The Akron was flown into the sea at full speed during a thunderstorm, while still intact. The frame of the Macon broke dur- ing a storm at a spot where needed repairs had been deferred, and was landed at sea at a spot selected by the Commander, with the loss of only two lives. In the entire world, since the first dirigible was flown, only 318 lives have been lost in peace time operations of lighter-than-air craft. Then why all the cry that the dirigible is doomed? Since the World War there have been 69 major submarine accidents, in which 771 men were lost. We still build submarines. During the same period there have been more than 100 “notable” marine disasters, in which 12,000 lives were lost. Yet try to book a quick passage on even a lowly freighter! A view of the interior of the former giant airship is shown below. A series of 16 gas cells like those shown here held 7 million cubic feet of inflammable hydrogen.

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You will find the, accommodations booked for weeks, sometimes months, ahead. There have been 100,000 railroad fatalities since the war, yet the railroads advertise (and truthfully) they have the safest means of transportation. On almost any summer holiday in the United States, more lives are lost in auto ac- cidents than have been lost in the whole history of the airship. More than half a mil- lion persons have thus been killed since the war. There is no cry to stop commercial air- plane flights, though the past season has been disastrous. And if you think the air lines have lost business on account of these acci- Dr. Hugo Eckener, rated as ranking authority on airships. dents, take the fingers of one hand out to Newark airport, and count the empty seats. Then why this condemnation of the air- ship, when, as a means of commercial trans- portation, it is the least offender of all? Are twelve passenger deaths, out of a quarter of a million passengers carried, too great a price to pay for the development of this swift and comfortable means of long distance transpor- tation? The fate of the rigid airship now seems to be entirely in the hands of the Zeppelin Company, and the U. S. Navy. The Germans have no idea of abandoning the industry, ; Four engine gondolas of a type shown above, each housing a 1200-horsepower Diesel engine. were features of the. Hin- denburg’s massive frame construction. which for the first time was getting on a paying basis when the Hinden- burg burned. The LZ-130, now nearing com- pletion, will have accommodations for 100 passengers; the projected 131 will carry 150. Since an aver- age of forty passengers have been turned away from each trip of the Graf Zep- pelin and the Hindenburg, the company has no qualms about being able to sell the addi- tional accommodations. It costs an average of $53,000 a round trip for an airship to make the North Atlantic flight. On the other side of the ledger will be $79,000 passenger revenue, and an addi- tional $18,000 from mail and freight, making a net profit of $44,000 for each round trip. Not a bad payoff on a $2,000,000 investment! But the pie the Zeppelin Company really has its eye on is a trans-Pacific service. It is a ten-day trip from Seattle to Japan by the fastest steamers. The Graf Zeppelin . 45

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made the trip in less than three days, nine years ago. І Airship officials do not consider the present Clipper planes as serious competition. The present planes carry only six passengers, a crew of nine, and half a ton of mail and cargo. Opposed to them, the LZ-130 will carry 100 passengers, a crew of sixty, and twenty to thirty tons of mail and freight. The Clipper ships, though they fly faster, take the longer southern route, make four stops en route, and take from five to six days. An airship can take the great circle route, and fly non-stop in less than three days. Aside from larger passenger quarters, and a slightly larger gas capacity, there will be no radical change in the design of the LZ-130 and 131, which will be almost sister ships of the Hindenburg. They will, of course, be buoyed by helium, in spite of its greater cost when compared to the highly inflam- mable hydrogen. That is one lesson the Ger- mans have learned. Perhaps from necessity, for this government will never again permit a hydrogen-filled ship to use its landing facilities, according to reports. Though several newspaper commentators have inferred that the United States was to blame for the Hindenburg’s burning, through refusal to sell helium, this is not true. The Navy did insist upon a monopoly of the gas at first, when it was scarce, and ex- tremely expensive to extract from natural 46 S The Graf Zeppelin, still in active setvice after having made more. than 500 flights without an accident, is shown making a landing at Friedrichshafen, Germany, the birthplace of all German air- ships. Despite the set-back of the Hindenburg disaster, German authorities state that they will continue to build airships, the LZ-130 and 131 being constructed at this time. gas. But when an ample supply was assured several years ago, the sale to foreign countries for commercial purposes was offered. The German government could have secured helium for both the Graf Zeppelin and the Hindenburg, but balked at the price. It was Dr. Eckner's insistence on obtaining helium for the Hindenburg that caused his break with the Nazi Government, and his subse- quent dismissal from command of that ship, according to well-informed people in the in- dustry. Commercial development of the rigid air- ship in the United States seems to be dead at the present time, due largely to a lack of interest in those having sufficient capital for the venture. The Science Advisory Board, appointed to investigate the future possibilities of the dirigible shortly after the Macon crashed, recommended that another ship be built. It designated that this ship be used "at least for a time, as a flying laboratory and training ship." The airship was never built. As to the military use of the dirigible, it is the general opinion in Army circles that the airplane and blimp can accomplish mili- tary missions more effectively, and more economically, than can large airships. With airplanes able to climb higher than the dirigible, and able to fly circles around it, the airship has lost its value as a wartime scout and raider over land. The day of Modern Mechanix

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Retired after years of safe usage, the dirigible Los Angeles is shown making a landing on an aircraft carrier during Naval tests, the airship bomber has definitely passed. But with the Navy it is something else again. Nothing can take the place of the large airship as a long-range scout. With a liquid desert as vast as the Pacific to patrol, twelve airships, costing less than one cruiser, could absolutely prevent a hostile fleet from approaching our shores undetected, while all the ships and airplanes in the fleet could not guarantee this. Besides, the dispersion of the fleet for scouting purposes, or to protect coastal cities, would so weaken it that a hostile fleet, able to approach intact, could defeat our forces piecemeal. During twelve hours of daylight, a cruiser costing $18,000,000, with a erew of 605, can August, 1937 The military value of airships was demonstrated by the Los Angeles (above). Ап airship can scout 172,000 square sea miles in the time a cruiser scouts only 4,800. scout 4,800 square miles of sea. During the same period an airship manned by a crew of sixty, and costing only $2,000,000, can scout 172,000 square miles. But cannot airplanes, with even greater speed, patrol even a greater territory? For a short distance off shore they can. But even the longest-range airplane cannot remain aloft more than 72 hours (you can't refuel far at sea), while an airship can remain aloft two weeks, drifting at night to save fuel. The argument usually given against the air- ship is that it is so vulnerable that, if it should discover the approach of a hostile fleet, it would be destroyed. Granting this for the moment, the same also applies to any other patrol medium. A cruiser must approach to within ten or twelve miles to secure the de- sired information, so could not hope to escape unscathed. It would be more economical, both in lives and money, to risk an airship to secure this vital information. The airship would certainly have time to radio its dis- covery before being destroyed; and the sacri- fice would be well worth while if it prevented one ship from being sunk, one city from being bombarded. But the dirigible would have better than [Continued on page 120] 47

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Tiny News Plant Draws Crowds (FINANCIAL | pd Today d WS | i More than a thousand parts—gears, cams, levers, etc., are re- produced in this scale model of the printing presses of the Buffalo (N. Y.) News. Compare size with folded newspaper. MAZING in its accuracy, precision, and fidelity to its prototype, a scale model of the mechanical section of the Buffalo (N. Y.) Evening News building attracted scores of the newspaper's readers when placed on ex- hibition. Constructed by two of the news- paper's employees, the miniature building is only three feet high and five feet square, yet every detail, not only of the building exterior, The exterior of the model newspaper plant is complete ın every detail. The windows, columns, cornices, and other architectural features were made sepa- rately and then assembled in proper order. 48 Charles Beenau (right) and Frank- lin Meno, co- builders of the model plant. A battery of 34 model linotype machines, each with over 100 parts, is a feature of the miniature plant. Compare size of machines with ruler at top of photo. but presses and linotypes, includ- ing their gears, cams, levers, etc., were reproduced. Charles Beenau, a linotype operator for the newspaper, and his assistant, Franklin Meno, spent 6700 spare time hours in con- structing the model plant at a cost of $500. Materials used for con- struction included walnut and maple wood, celluloid, brass, zinc, paper, lead, etc. Special tools were designed by the two craftsmen in order to permit details of the plant to be cut from materials. Modern Mechanix

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Steam Challenges Diesel With New Locomotive TEAM issues a defiant chal- lenge to Diesel powered loco- motives with a new stainless steel streamlined locomotive con- structed in the Burlington, Iowa, railroad shops. The most extra- ordinary features of the new type locomotive are to be found in the driving rods that transmit power from its cylinders to the 6%-foot drive wheels. The major obstacle in operating steam locomotives at very high speeds has been the terrific forces set up by the up-and-down and back-and-forth motion of the drive rods and attendant recipro- cating parts. To overcome this difficulty, experts took the latest development in alloy steels and roller bearings, and applied them to their problem. Telegraph Transmits Colors amem = 4x я x AAG RAN AN [vs With this new device, colors may be transmitted by telegraph. Each color has ita own characteristic graph curve, No two curves are exactly alike unless they are for the same color. SING a new tool of science, research col- orists now are sending color samples by telegraph. Known as “colorgram,” these color samples represent the most accurate means of color transmission. By a complex photoelectric system, the device charts the color characteristics on a sheet of graph paper. August, 1937 This new streamlined steam locomotive is capable of a 125 m. p. h, maximum speed and a cruising speed of between 90 and 100 m. p. h. It is fueled with coal by automatic stoker. Powder Flame-Proofs Cloth NEW flame-proofing agent for cloth or paper, which does not change the feel or texture of the material treated, may be ap- plied when the material is washed. In the form of a powder, this flame-proof- ing agent may be mixed with the final rinse water. The material treated is not fire proofed but it is flame-proofed. Pieces of cloth subjected to flame. The piece on the right has been flame-proofed and the ene on the left has not. To apply to cloth, special powder is added to final rinse water. 49

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50 Thwarting human ex- planation for centuries, homing pigeons mi- raculously return to lofts many miles away. ACING the homing pigeon is a very in- teresting sport, and yet there are many people who are unaware that such a sport exists although it is one of the leading sports in England, Belgium, Germany and other European countries. To give one an idea of the vast number of racing enthusiasts par- ticipating in this sport in these countries as Modern Mechanix

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a 4 W. В. Stamford m Shown above is the liber- ation of almost 1,000 pigeons at Wilmington, Delaware, for a race to New York. A blue checker hen fed the field, making a flight of 112 miles in 2 hours, 6 minutes. Right—- "Swiftwing, blue checker cock, winner of the Chat- tanooga National Race in 1936. Owned by F. E. Gorely, of Washington, D. C., this pigeon flew 534 miles at average speed of 1036.42 yards per minute. August, 1937 well as the United States, the following figures are presented: : There are some 300,000 fanciers in England, 35,000 in France, 350,000 in Belgium, 10,000 in Germany, 20,000 in Holland, 8,000 in Italy, 3,000 in Portugal, less than a thousand in Switzerland, about a thousand in Austria and 10,000 in the United States; a total of some 800,000 fanciers and this is not counting the fanciers in Brazil, Spain, Poland, Cuba, etc. Mons. Hansenne, a Belgian who lived in Verviers, was, before his death, a most noted racing pigeon fancier. His fame and reputa- tion as a breeder are known throughout the racing pigeon world. During the last three years of his life, he averaged $15,000 a year from the sale of his birds and their winnings. One of his favorite racers, "Good Blue," won $10,000. J. W. Logan, an Englishman, is known to have sold a pair of his birds for over $1,400. A few years ago a Dr. Anderson, of Scotland, - paid to Mons. Stassart, of Belgium, $1,000 for "Epinard," one of the greatest champion birds he ever owned. European birds and'their progeny have performed wonderful feats, but some of the records of the U. S. birds are really extra- ‘ordinary. The conditions they must fly under in this country are very trying. On the Pacifie coast they have to contend with the terrific heat blown in from the desert, flying over the mountains four to five thousand feet high. Over these mountains they must come on their way home from a race, as there is no easier way round. In the central part of the country they encounter dust storms, strong head winds and intense electrical storms, which arise out of nowhere. Along the Eastern seaboard they have to fly over the high Alle- gheny Mountains which are nesting

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Sealed timing devices (left) are used by pigeon fanciers’. clubs. When a bird "homes" in a race, the fancier removes a countermark from its leg and places it in either of the timer's two holes. Turning a dial locks the countermark in timer and stamps the time on slip. The important parts of a "stop and start" timer are shown above. When timer is to be used, the nut A is unscrewed from post. Both clocks are wound and «ase B is then slipped over timer and nut A replaced, a string and seal being attached to it. Re- turned pigeons' countermarks ate inserted ín the holes. The manner in which pigeons are countermarked before a race is clearly shown in the photo at left. Notice how rub- ber countermark is stretched to allow the bird's foot to be placed through it. When the handle is released, the counter- mark automatically flies off prongs onto the bird's leg. Below — Countermarked, the bird is ready for shipment to the point of liberation. grounds for fierce hawks. Is it any wonder why the racing pigeon fancier becomes so attached to his little feathered racers? How are racing pigeons trained? When young racing pigeons are 7 to 10 days old a seamless aluminum band is placed on one of their legs. As the bird's leg and foot grows, the band will soon be impossible to remove. On the band is stamped, in raised letters and figures, the initials of the organization to which the fancier belongs, year of hatch, initials of the fancier's club, and a number. At 12 weeks of age, when these young 2 са

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racing pigeons—called youngsters—have be- come settled to their loft, they should be exercised 30 minutes or more each time they are let out of their loft by their owner. This exercise strengthens their wing muscles, de- velops the respiratory organs, and gets them familiar with the country surrounding their loft, developing their instinct. ‘Birds that are let out to exercise hungry should *'trap" into the loft when they alight after the exercising flights. “Trap” is the racing pigeon fancier’s word for birds enter- ing the loft. If the birds were put out to exercise not hungry, they would soon get into the habit of loafing on top of the roof once they lit. This is the worst habit a racing pigeon can have, and unless it is corrected as a youngster, the bird is of no use to its owner. A pigeon race cannot be won if the bird sits on the roof when homing from a race. Young birds should be ready for their first training "fly" at the age of four or five months. They are taken about a mile away from their loft in baskets and > liberated. On these “flys” the p birds are taken away hungry, d so that when they return to y their loft they will "trap" 4 into it. The above dis- A tance is gradually in- 4 creased to 15 miles, . then to 25 miles, etc. Á After the birds are | thoroughly trained 4 up to 60 miles, / they will in most | cases be ready | for their first | competitive race, | which is 100 | Old birds | 1 miles. W. O. Maybury, said to be the oldest pigeon flyer in Pittsburgh, Pa., shrewdly in- start of a race. The physical condi- tion of a bird is only one of the factors that worry racers. Winds and type of terrain en route are equally important. spects his champion bird before а that have been inactive during the Fall, Win- ter and early Spring months will need a few training flights previous to the “old bird” race, to freshen their memory and sense of direction, but they, like the young birds, must exercise during the races, There are two series of races every year for the fancier, provided he lives in a city where pigeon races are conducted. These series are known as the “old” and “young” bird races. The old bird races are for birds bred previous to the year in which they are to compete, while the young bird races are for birds bred the same year in which they are to compete. The old bird race schedule consists mostly of 100, 200, 300, 300, 400, 500, 500-mile hops and generally ends with one 600-mile race, although special races are sometimes held by clubs for longer distances such as 700 and 1,000 miles. This series of races starts about the first of May and

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Homing pigeons were used by both sides during the World War. Pre-eminent was the work of "Cher Ami," shown above. Lib- erated with an important message during intense machine gun and artillery action, this bird flew 25 miles to deliver its mes- sage. Examination showed that one leg had been amputated and its breast pierced by a machine gun bullet. The message tube, intact, was hanging by a ligament. Below—"Spike," another battle veteran. At Fort Monmouth, М. J., the U. S. Army Signal Corps maintains lofts (below) for breeding and training of pigeons. During the St. Mihiel drive in the World War, 567 birds were released with mes- sages, attesting to their importance \ large scale military operations. \ HJ а continues until mid-summer. The young bird race schedule generally consists of 100, 100, 130, 200, 200 and ends with a 300-mile race, this series starting a few weeks after the old bird schedule is completed and last- ing until the Fall months. Short races are flown in most cities on Sunday, and the longer ones on Saturday. Birds that are entered in a race must be countermarked at the fancier’s club house on the night preceding the day of the race on short races, and two nights ahead for longer races. A small charge is paid by the fancier for each bird entered in the race, a countermark being received for each bird. A countermark is a rubber ring with two different numbers stamped upon it—one number inside, the other outside. The coun- termark is attached to a stub of paper called the countermark stub, which has the same numbers stamped upon it as the marker itself. When a bird is eountermarked, the countermark is placed on the bird's leg (by a hand-operated appliance made for this purpose) and at the same time the bird's band number is written on the stub from which it was removed. This stub is then placed in an envelope (which has the fancier's name on it) together with other Modern Mechanix

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Just what prompts and enables pigeons to return to ^ Е lofts located hundreds of miles away has never been doors are sealed shut with r egulation club satisfactorily explained. The birds are taught to be- seals and sent to the railway express station. lieve that food can only be obtained at the home loft, En ki but what guides them unerringly ee and After the shipping costs for the baskets are plains to their respective lofts оѓоз on pages : 3 54-55 by courtesy of the U. S. Army Signal Corps.) paid to the express agent by the club secre tary, they are then placed in charge of the convoyor who directs the placing of the bas- kets in the railway express car, which has been hired for this purpose by the various clubs. A convoyor is a person sent with racing pigeons whose duty it is to liberate them the morning of the race, weather per- mitting. On the long grinds such as the 300, 400, 500 and 600-mile races the birds are fed and watered in the baskets by the convoyor at the race site station on the day previous to being liberated. How a liberation is conducted and prepared is told in The American Racing Pigeon News by a man who has convoyed Pittsburgh, Pa., pigeons for almost two decades: “About four days before I make a trip [Continued on page 124] stubs, if he is fying more than one bird, and sealed. All competing birds must be countermarked by this method, The countermarked bird is then placed in the club’s ship- ping basket. These baskets are of different styles and hold about 50 birds with space to feed and water them when they are on the longer races. Straw or shavings are placed on the bottom to keep them in a sanitary condition. When the shipping baskets are filled with countermarked birds, the The two photos at the right show a close-up of one of the lofts at the Army Signal School at Fort Monmouth, N. J., and a series of the Army's extensive pigeon taising and training quar- ters. The pigeon’s mili- tary value is established, the Japanese army main- taining 20,000 of them. Experiments are being conducted in which the pigeons wear tiny cameras strapped to their breasts, timed to take photos at regular inter- vals during their flights. August, 1937

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56 Above—One of the watch dogs being trained to dis- arm a raider. A long train- ing period prepares the dogs for the responsibility of protecting property. Left—One of the dogs be- side а practice raider. dressed in heavy clothing. Above-—One of the trained dogs guarding the “blue ground” at the diamond mines in Kimberley, South - Africa. Men patrol during the day and dogs take over the work at night. by Lawrence G. Green ARBED wire entanglements at Kimberley, South Africa, enclose a square mile of crumbled “blue ground” which still contains a fortune in diamonds. This private “El Dorado” is guarded by trained dogs. Fifty men patrolled this area at the time when the whole output of the De Beers mines was left exposed to the weather before the diamonds could be extracted. Four men and a dozen dogs carry out the task at the present time, defeating all raiders. Not that raids are frequent—the mere presence of the dogs is a strong deterrent. Criminals who might be tempted to scratch the rich earth at night see the dog training station every time they pass out of Kimberley along the main road. It is there as a warning. When I visited the kennels recently I found Mr. Arthur Marsberg in charge—Marsberg the international footballer who went to En- gland thirty years ago with the first Spring- bok team. Now Mr. Marsberg trains dogs with the same kindly skill that he once showed in training young footballers. Dogs were his hobby when, in 1928, De Beers de- cided to protect the property with dogs. And so Mr. Marsberg built up the efficient system that I saw within the barbed wire. At first Alsatians were used. Today there [Continued om page 153] Modern Mechanix

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Electrical Device E TRANGE "eyes" which "look" into citrus fruit to determine whether it is frosted and dried, or decayed, have been invented by Harold C. Pierce of Anaheim, Calif. The machine’s operation is based on the theory that damaged fruit has a different electrical resistance than good fruit. As the oranges, lemons or grapefruit pass along a conveyor belt they come in con- tact with ten energized “fingers.” If energy passes through the fruit at a sufficient volume, it is shunted into the correct box. Doorbell Demands A Nickel Conant Wait, inventor of the anti-door-bell-ringer, is shown with his device which requires that a nickel be deposited before bell will ring. Friends are reimbursed; others are not. LOS ANGELES attorney became tired of peddlers pushing his doorbell, so he invented a device making it necessary for them to deposit a nickel before the bell will ring. You can always reimburse your friends, says the inventor, but anyone else will have to pay just as if he called you on the phone. August, 1937 Examines Inside Of Fruit Fruit passing through electrically operated device capable of determining, by resistance test, whether fruit is frosted and dried or decayed. Damaged pieces are shunted into discard. Motorcycle Sets New Mark HEN he set a new American Motorcycle Association record of more than 136 miles an .hour, at Daytona Beach, Fla, Joe Petroli used a streamlined motorcycle. A fin, covering the rear wheel, and increasing the streamlined effect, gives greater sta- bility to the machine. The streamlined effect being carried throughout, the front wheel fork resembles an airplane landing strut. A wind deflector in front of the handle bars reduces the wind resistance which would normally be caused by the rider. As he bends below the top of this deflector, further streamlining is carried out during operation. Varying from the usual motorcycle design, the seat instead of being level, slants up at the rear. A broadside view of the streamlined motorcycle which set a new speed mark at Daytona Beach, Fla. Streamlined rear also adds to stability of the machine at high speeds. 57

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Novel Propeller Has Arced Blades Offset At Hub The blades of this novel propeller are arced and offset at the hub. Better balance, resulting in smoother operation and increased efficiency, is claimed for the invention. Youth Builds Bike Trailer OT to be outdone by motor car trailer owners, Billy Roach, of Tampa, Fla., de- signed and built a bicycle trailer for use on week-end camping trips. Constructed of wood and wallboard, the trailer is 7% feet long, 26 inches wide, and 33 inches deep. Weighing 75 pounds, the trailer body is mounted on an axle equipped with 15-inch tricycle wheels. An air mattress and pillow provide all the comforts of home and a 6-volt dry battery furnishes current for an interior dome light and a tail light. г Hooked to a bicycle with а bracket that takes the place of a tear wheel stand, this trailer affords comfortable sleep- ing quarters for Billy Roach, of Tampa, Fla., who built it. 58 EW in principle and design, an arc-bladed propeller has been developed by a Milwaukee, Wis., firm. Greater efficiency and per- formance are claimed for the novel arrangement of the blades. The blades carry a decided arc and are offset at the hub. The arc acts to bring the point of propeller fatigue four inches nearer to the hub and the offset arrangement provides a better balance for the motor, reducing vibration. Blowing through a small tube, G. W. Johnston, 60-year-old inventor, demonstrates how air currents and air suction are util- ized to move wheels of his new "perpetual motion” machine. ONSISTING principaly of four main wheels, three of which are nearly five feet in diameter and one-foot thick, a novel perpetual motion machine driven by air suc- tion is claimed to have been invented by G. W. Johnston, of Tulsa, Okla. Valves and other wheels are assembled in- side the main wheel, each of which turns on a hollow axle. A turn of the wheel produces an air current at one end of the axle and suc- tion at the other end, serving to keep the ma- chine in motion. A small unit of the device, an eight-pound cylinder, can create eight horsepower under a 100-pound air pressure according to the inventor. Modern Mechanix

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Trailer Shop Provides Livelihood For Cobbler [РАЙ BUILDING Starting with the idea of having a short vacation during which he could earn enough money to cover expenses, Ivan Symmonds mounted shoe repairing machinery in his home-built trailer. traveling for three years, doing business in towns en route. ESIRING to travel around the country and to spend a vacation in Yosemite Na- tional Park while, at the same time, earning money to cover expenses, Ivan Symmonds, owner of a small shoe store near Reno, Ne- vada, hit upon the idea of carrying his busi- ness along with him. He loaded an electric stitcher, finisher, and other shoe repairing machinery into a home-made camp trailer, managed to reach Yosemite and, established at a campsite, hooked his machinery onto a 110-volt electric circuit. Surprisingly, business flooded him. In- stead of a short vacation, he spent a whole summer in the valley, working on hiker's boots and shoes, the vacationists giving him their business instead of making a trip to the towns outside the camp area. After leaving the campsite, isolated mining sites and small “cowtowns” furnished him with winter trade. The traveling "shop" is seven by fourteen feet, with a six-foot headroom. The walls are masonite, the roof being plyboard, canvas covered and painted. The chassis is of extra heavy construction, being made of six-inch channel iron in order to carry the 3000- pound load of shoe repairing machinery. August, 1937 The novel shop attracted so many customers that A 75-foot cable connects machinery with nearby electric lines, he has been Robot Parachutist Devised UMAN in appearance and life-like in its actions, a robot parachute jumper has been invented by Bill Kuhn, a professional parachutist of Sandusky, Ohio. The robot is de- signed to make delayed leaps from any desig- nated altitude. А clock-work motor activates the robot when it is hurled from an airplane, releas- ing the parachute. by automatically pulling the rip- cord after a cer- tain lapse of time. The mechanical jumper is six feet tall and weighs 160 pounds with- out equipment.

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“ГАНЕ young inventor looking for new worlds to conquer would do well to in- vestigate the vast but little-explored domains of electrochemistry. Hundreds of new prod- ucts and inventions difficult or impossible to discover during the countless ages of the past with mechanical skill alone are today readily possible through the combined power of electricity and chemistry." Thus Professor Colin G. Fink of Columbia University presents an invitation — and a challenge—to inventive minds everywhere. He sees no reason why young men with courage and imagination should not play an important part in future scientific development and he believes his own field offers un- limited possibilities for advancement. When I called on him in his laboratory at Columbia, I told him the readers of MopERN MxcHANIX were particularly interested in needed inventions and I asked him to name a few of the problems which, in his opinion, demanded the greatest attention at this time. "Our basic engineering metal is iron," he began. "It is the most abundant and has the most valuable properties, such as high tensile strength, high fatigue value, ete. The world produces more of iron and steel than all the other metals put together. For every 100 tons of iron and steel, only 2 tons of copper are produced—and copper occupies second place in quantity and importance among metals! "With ever rapidly increasing utilization of steel in railroads, automobiles, bridges, buildings, high transmission towers and other articles, the problem of eliminating rust and protecting steel products and costly structures against corrosion is undoubtedly the biggest problem confronting the chemist and engi- neer. Metals rust as a result of electro- chemical action. If we eliminate this, we eliminate rust! The young men of the com- ing generation will solve this problem; marked progress towards a solution already has been made. “We are also badly in need of an electric source of illumination suitable to our eyes which will operate at 90 per cent or better in 60 Aninterview with Professor Colin G. Fink Head, Division ofElectrochemistry Columbia University by Richard H. Parke Scientists are baffled in their efforts to release gold from sea water cheaply. efficiency instead of less than 10 per cent as at present. Electricity is modern man’s in- dispensable and versatile servant; eliminate it and civilization would drop back 100 years. But, although electricity has increased the efficiency of old hand-operated machines and Modern Mechanix

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of electrochemistry, Pro- the growth of fruit and. vegetables can be greatly increased and that metals. rusting and corroding. Photo-electric generator cells mounted on roof tops will be used to sup- \ ply electricity \ í} for homes, pre- > dicts Dr. Fink. A innumerable devices a thousandfold or more, it has so far not accomplished anything near as much for artificial light. “The tungsten lamp in the average man’s home furnishes but 5 cents’ worth of light for every dollars worth of electricity. The August, 1937 Through the application Я fessor Fink believes that . can be prevented from - Winner of the Perkins Medal of the Society of Chemical Industry and the Acheson Gold Medal for outstanding accomplish- ments in the field of elec- trochemistry, Professor Colin G. Fink now heads Columbia University's De- partment of Chemical En- gineering. Discoverer of a platinum substitute used in manufacturing incandes- cent lamps, Dr. Fink seeks lamps that will be ninety per cent efficient instead of ten per cent as at present. balance, 95 cents, is lost as useless heat. Modern homes and towns need a lamp that will furnish at least 90 per cent light and only . 10 per cent heat. The little firefly, or glow- worm, operates its light at figures even better than 90 per cent. The lamp of the future may very well be based on principles similar to those of the firefly’s glow. “A simple means of electrically controlling rainfall—keeping it out of the cities—is an- other important problem to solve. The Cottrell electrical precipitation process is used at factories all over the world to precipi- tate fumes, dusts, smoke and vapors of all kinds. It requires very little development to apply this same process to the precipitation of rain in localities outside of towns and cities. Millions of dollars’ worth of shoes, clothing [Continued on page 118] 61

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RESTOCKING The Federal! Bu- reau of Fisher- ies takes un- usual mea- sures to bal- ance inroads made by com- mercialfishers. HAT is probably the largest undertaking of its kind in the entire history of man has recently been completed, for, fan- tastic as it may sound, the ocean has been restocked by human efforts! This gigantic task was accomplished by the Federal Bureau of Fisheries which states, in part: “If all of the fish planted by the Bureau in the past fiscal year in the Atlantic and Pacific Oceans and in lakes and rivers were to grow to maturity and be caught, almost every man, woman and child im the United States could have approximately six pounds of fish every week for a solid year from this source alone.” The total was slightly over eight billion, and was composed of eggs, fry and finger- lings of forty-three different salt and fresh water species from eighty-four hatcheries in thirty-eight states. But why go to all this trouble to put fish into the sea? Restocking streams and lakes seems reasonable, but the ocean is a vast place, covering three-quarters of the earth’s surface. Won't the salt water fish wander off to Europe or South America after they've 62 been planted? How does the Bureau know that there will be any benefit reaped planting fish eggs and fingerlings in the boundless sea? The answer is, and most definitely, that the Bureau does know what will happen to a good majority of the eggs and fish it re- leases in Old Father Neptune's domain. This knowledge came about after long and ar- duous study of ocean currents (known as oceanography) and years of so-called “tag- ging" of various fishes to learn their migratory and spawning habits. The story of fish tagging is a tale in itself, but suffice it to say that by identifying fish by attaching tags on the fleshy part of the tail, or clipping certain fins and several other methods, the Bureau has unquestionably established many facts, such as: large quan- tities of codfish lay their eggs in Massachu- setts Bay, and ocean currents carry them to the famous Georges Banks, 150 miles away, Modern Mechanix

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Unloading a catch from one of the many fishing boats supplying the colos- sal public demand for this popular food. Nets make large scale catching possi- ble in a minimum of time. Because of the relentless demand for salt water fish, restocking is becoming necessary to prevent extinc- tion of popular species. just in time to be hatched; that weakfish, a valuable commercial fish of New Jersey, go south to Chesapeake Bay and the Carolinas during winter to spawn; that salmon, when- ever possible, return to the identical stream where they were hatched to spawn and die. These are but a few instances of what the Bureau has learned about the. habits of the denizens of the deep. So, when it plants six billion eggs and young fish in the At- lantic Ocean, you may be sure then an ap- preciable amount of them will end their careers in the frying pan of Mr. and Mrs. America. With rare exceptions, our native salt water fish do not leave our shores. Backing up this statement are the scien- tists of the Rockefeller-endowed Oceano- graphic Institution of Woods Hole, Mass., whose studies of ocean life have extended in the Atlantic from Labrador to the Equa- tor. They state, without qualification, that August, 1937 Тор of page—-Large numbers of per- sons now enjoy deep sea fishing on one of the many boats used for this pur- pose. With rods and reels, dozens of fishermen are taken to. fishing grounds not usually available to the individual. Below—One of the reasons why fish- ingis one of the most popular pastimes. 63

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marine life hardly exists over 200 miles from shore. In other words, our salt water fishes remain close to home. The Bureau of Fisheries scientists know where and when various fish spawn, where they migrate to (when they do migrate) and act accordingly in their vast propagation activities. Naturally you're not going to eat six or seven pounds of fish a week, unless you're more than crazy about sea-food or live in Alaska. So why this extensive planting of fish—the largest that the Bureau of Fisheries А Bureau of Fisheries scientist picking out unfertilized cans pre- has ever accomplished in one year? paratory to planting іп suitable spawning grounds on the Georges Take one of our best known com- Banks, off the New England coast, Six billion eggs were planted. : : or m mercial fishes—the cod, for example; for the past several decades we have consumed on an average of one hun- dred million pounds annually of this Single staple marine product and practically all of it comes from the New England region alone! That gives an idea of the amount of fish we eat. Bear in mind the dozens of kinds of fish on the market today from our diversified and many fishing grounds, and it will be readily agreed that, taking the cod as an example, the American publie consumes a staggering amount of fish. By far the greatest fisheries in the United States are those off the New England coast. They extend, roughly, from the east end of Long Island A Bureau rescuing unit salvaging fish. trapped iby overflow waters Sound to Nova Scotia and the New- of the Mississippi River. More than 47,000,000 fish were saved : foundland Banks. These grounds in this manner during the past year and replanted up-stream. E ; : are more extensively fished than any others in the entire country. Huge fieets of fishing boats leave almost daily from Boston and Gloucester, Mass., and Portland, Maine, as well as numerous smaller ports, (The fish pier at Boston is the largest of its kind in the world devoted ex- clusively to receiving and packing fresh fish.) The aggregate catch of these ports is colossal. Better equipped and more nu- merous boats are bringing in sea- food delicacies at such a rate that nature, lavish as she is, cannot keep up with the inroads man is making. Today the fishing fleets must make longer and longer trips to get satis- factory hauls. Several important ;Removing fish from overflow waters during floods, for transfer species are becoming alarmingly to other sections of the country. This work saves many million fish which might have been killed when the flood waters. subsided. 64 Modern Mechanix

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searce. Yet the demand for cod, haddock, flounder, mackerel and other salt water products goes on re- lentlessly. This depletion does not confine itself to New England alone, for, according to Bureau scientists, it is true in varying degrees in prac- tically all of the nation’s commercial and sports fishing areas. Perhaps the public does not realize the situation, but five years ago the Bureau of Fisheries foresaw that unless something drastic was done, our fisheries would within a short time face an economic crisis. This huge industry, with its ramifica- tions, employing many thousands of workers, might conceivably cease to exist—and more than that—a tre- mendous source of food be denied the entire nation. What to do? Only one thing— increase the number of fish in the ocean and inland waters—somewhat of a job, especially the former. Whereupon two great hatcheries of the Bureau, one at Gloucester, Mass., and the other at Boothbay Harbor, Maine, began collecting eggs from fish caught during the spawning sea- son. Knowledge of the proper way to treat and handle the precious eggs grew with experiments, till today, the Bureau of Fisheries announces that it has planted the greatest num- ber of eggs and fingerlings of salt water fish that it has done in any one year in its entire history. Close to six billion potential fish dinners are now on their proper beds on the great Georges Banks and along the coast of Massachusetts and Maine, either in the fingerling and young fish state, or in the form of eggs, ready to hatch. A most stupendous ac- complishment! Cod and flounder head the list, the former with over two billion and the latter with a billion and a half. Pollock, a valued commercial fish re- sembling the haddock, makes its initial artificial spawning bow by placing third with over a billion. Haddock is: represented by a mere 500 million, while the neglected mackerel has only an insignificant 100 million of its progeny planted [Continued on page 122] August, 1937 Young fish being disinfected at one of the Federal Bureau hatcheries. After these fingerlings are immunized against disease, they are released in waters suitable for their healthful growth. Planting bass fry in fresh water lake. Моге than four million bass were deposited in lakes and rivers throughout the United States in the largest propagation program ever carried out by the bureau. Bureau ‘of Fisheries field man unloading fingerlings into a container preparatory to planting them in suitable water. There they will grow to maturity and ‘stem the flow of many species toward extinction.

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New Refrigerator Has Built-In Radio Receiver EN New refrigerator with built-in radio in the top. Chromium knobs match hardware on refrigerator. With radio in kitchen, housewife may listen to her favorite program while working. NEW automobile heater utilizes gasoline vapor drawn from the carburator and ignited in a sealed metal combustion cham- ber. The hot gasses then pass into a com- pletely sealed "oven" and are drawn off into the exhaust by suction. Air from a fan is blown past heated fins surrounding the oven, and billows of hot air pour into the car ninety seconds after the heater is started. The photograph shown is the first radiograph of its type taken, and re- veals the internal structure of the heater unit. 3,000 Pictures Per Second Y MEANS of a new camera technique, 3,000 pictures per second can now be taken. When these pictures are slowed down to ordinary projection speed, it is possible to see action not visible without instrumental aid. High speed pictures show many un- usual and interesting facts. 66 REFRIGERATOR equipped with a built-in radio has been placed on the market. So popular was the first model that the manu- facturer has made available a choice of several models in different sizes equipped with radio. This has been accomplished by having the radio mounted in the top of the refrigera- tor, and having the refrigerator con- structed so that a top equipped with radio may be substituted for one without. It has been said that the housewife spends sixty per cent of her time in the kitchen. Now by having a radio installed in the refrigerator, she may listen to her favorite program while working. Because most radios are placed in the living room, one or two rooms from the kitchen, usually the house- wife, when she is in the kitchen, finds it necessary either to miss a program or turn the volume up to a point where it is objectionable to the rest of the family. With this popular com- bination the housewife may work and listen at the same time. Car Heater Burns Gasoline Radiograph of new heater utilizing gasoline vapor as its heat source. Vapor is drawn from carburetor to sealed combus- tion chamber. Burned gas leaves through exhaust pipe. Modern Mechanix

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Machine Provides Permanent Wave In One Minute ONE-MINUTE permanent waving ma- chine of new design has been developed by Ralph Shakour, Frank Feeney, and E. Riley of Springfield, Mass. The device fea- tures vertical heater elements that preheat thirty-six aluminum curler clips in groups of eighteen because the speed of the machine is so rapid it proved to be impractical to heat all the clips at the same time. The heater is di- vided into two units with safety switches and red safety lights. The clips are merely taken off the heater and placed upon the hair. By the time the eighteenth clip has been attached, it is time to remove the first one. The proc- ess of waving is then repeated. Paste Restores Compression Easily injected into cylinders by means of a small rubber tube, a new tefined mineralized paste is said to restore compres- sion efficiency to auto engines having scored cylinders. ACKED in a compact tube and injected into engine cylinders by means of a rub- ber tube attachment, a new paste product, claimed to function similar to the installation of new piston rings or new rings and a cylin- der rebore, has been produced by a Kansas | City, Mo., manufacturer. The product consists of a mineral refined by scientific methods until it assumes the con- sistency of a paste. When applied to an en- gine with scored cylinders, the paste assumes a smooth, metallic hardness and tests indi- cate that the engine’s compression efficiency is restored after about 400 miles of driving. August, 1937 Beauticians can provide their clients with permanent waves in record time with the new machine shown being demon- strated here. Aluminum curler clips are fastened to the hair after being heated only one minute on vertical heater ele- ments of special design. “Crawler” Uses 8 H.P. Motor E QUIPPED withan eight horse power gaso- line engine and possessing high tractive power, a compact farm “crawler” has been developed by a German manufacturer. The design of the machine enables it to be used to work narrow strips of cultivated ground even when located on heavily sloped land. By using special attachments, the machine can be used for ploughing, hoeing, digging, and other miscellaneous farm work. Designed especially for farm work where narrow strips of land are to be worked, this "crawler" is equipped with an 8-horsepower gasoline engine and has great tractive power. 67

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Above—Window screens for summer use ` are important comfort aids to the home owner. During the cold months, the screens should be replaced with storm win- dows, thus eliminating “cold zones” in the rooms. Right—-A typical example of what can be done with an average cellar. Covered‘ walls, floor and ceiling add a тоот to the house, suitable for any use. (Photo courtesy American Radiator Com- pany's Castles Underground) 68 ‘the country. The summer of 1937 will see a TTRACTED by the low prices made pos- sible by large-scale, government-spon- sored production, thousands of families of modest income are buying homes throughout building boom of unequalled size, according to realtors everywhere. The advertised prices of comfortable five- and six-room houses appear so reasonable, and the terms of payment so convenient, that сера

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many people hurriedly purchase dwellings in desirable and rapidly filling communities and learn only afterward that the down, pay- ment and the monthly installments do not cover a really complete home; they dis- cover to their dismay that the “ex- tras” add up to a considerable sum, some- times an appreciable fraction of the pur- chase price. Builders have found that average prices of $5,000 for a one-story house and about $6,500 for a two-story structure draw the greatest number of prospective Right—A stout fence to keep children and animals off the lawn is good insurance for grass and flowers. Costs vary according to type and general construction. buyers, mainly because the carrying charges on these sums are smaller than rent for: equivalent apartments. Such houses cannot include numerous accessories and attach- ments if they are to conform to the technical standards established by the government and still earn a legitimate profit for the builders. The latter therefore emphasize the minimum prices and simply do not mention the ex- iras. If you are in the market for a home, do not hesitate to ask many questions of the builders you meet. Start with the heating system, which is undoubtedly the most important single mechanical ele- ment in a home. You will be surprised to learn that standard equipment for the great majority of small houses is an old- fashioned coal furnace, Left—Rock wool insula- tion, shown being in- stalled in a top floor ceil- ing, is an efficient means of reducing fuel costs in winter and for lowering temperature in summer.

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nm ae | | mer. Аз the bedrooms and the bathroom are on the upper level, the family will be very uncomfortable unless the furnace is kept running almost continu- ously. You can easily pour any of the mineral type insulating materials between the attic floor beams after the house is finished, but getting it into the walls or the roof calls for the services of expert blowers. The time to think about insulation is when the house is being built, or at least before the walls and upper ceiling are plastered. Putting it in then is easy. The cost of complete attic and wall insulation de- pends on the size and the construction of the house. A completely detached home, say of the usual two- story, six-room type, should have the attic floor and at least the upper outside walls insu- = lated; the lower walls should also be done if the extra cost is not objec- tionable. An at- tached house, with other houses on both sides, will re- quire treatment only on its front [Continued on page 121] о PUN UE DN а ад й НИИ Above — Venetian blinds are decorative and useful, especially for small houses whose windows are at street level. Right—The re- frigerator is considered part of the house own- er's personal effects and is not supplied with the new house. with a galvanized iron tank opera- ting off a sepa- rate pot stove for summer hot-water supply. If you want an oil burner and a modern non- rusting water tank, the builder will be glad to put them in—at an ex- tra charge of at least $300. _A word of warning here. Don’t install an oil burner in a furnace designed for coal, unless the fire chamber is so constructed that special baffle plates can be inserted. Otherwise, most of the hot gases will be pushed up the chimney by the forced draft of the oil burner, and your oil bills will be an unending headache. Insist on a furnace made specifically for oil heat, and make sure that the quoted extra cost includes the fuel tank, an up- stairs thermostat for steam control, and another thermostat in the water chamber of the furnace itself for year-round automatic hot water supply. What about insulation? Without it, the upper rooms will be chilly in winter and stuffy in sum- 70 Although the radi- ators may be sup- plied with plenty of steam, the room may remain cold. Many times this is caused by poor insulating qualities of the walls.

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MINUTE MARKERS MADE FROM RESIN BALL BUTTONS WITH BACKS SAND- ED FLAT

MINUTE HAND qu BENT TO MISS. '. BOLT HEADS

BOLTS HOLDING P CLOCK WORKS " "IP" & "6° MARKERS — MADE FROM RESIN = BUTTONS CUT IN E HALF An old alarm clock mechanism mounted in a skillet makes an attractive home decoration and timepiece. Round dress buttons, cut in half, serve as hour divisions while hands are cut from scrap pieces of tin or aluminum. Worksho This novel, “Scottie” brush can be put to many uses about the home. Cut out the body of the dog from a piece of 1"x2l15"x6GV5" hard- wood, on a jig saw, by following pattern shown Made from an 014 .22 below. Drill a 114” hole in the head of the ; calibre rifle, this distinc- dog for inserting the brush which can be any : j tive pirate’s pistol makes type that will lend itself to the purpose, Р a novel decoration for а А boys’ room ог den. . Cut off the barrel at the point indicated in. the upper diagram and file the end smooth. Next, remove the gunstock and saw it down at both ends to form a pistol grip. Fin- Г] m ] Tr < ish the grip by sanding Г al t smooth rough edges and : applying one ot two coats- of varnish stain.

|

Illuminated wall brackets can Бе made in the home workshop at a cost that is trivial. Make the disc and lamp mounting from walnut, cutting the stock to the shapes and „ Sizes shown. Attach curved alu- 67, minum decorative strips to the 8 walnut disc for holding in place the lamp shade. The shade is formed from a piece of opaque cel- luloid or "Lumerith", bent "U^" shape. Fit the completed lamp with a small three watt bulb. TO OUT- LET BOX IN WALL

3 WATT LAMP

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DEMONSTRATE STEAM’S HEAT TRANSMISSION QUALITIES-—Water in a test tube is boiled and the steam car- tied into a glass of water by means of a rubber tube. In a short time the water in the glass will be heated although the condensed steam has added very little water to that already in the glass. Steam in addition to being hot gives up a large amount of heat when it changes to water. A REVOLVING COPPER DISC—A copper disc will revolve between the poles of a magnet if direct current is allowed to flow from center to edge or edge to. center of the wheel. A drop of mercury supplies the contact for the current at the lower portion of the rim although very light contact with a piece of wire also will work. The disc revolves because the part of the disc carrying current between the magnetic poles is constantly being pushed aside by the magnetic field. 72 - Modern Mechanix

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DILUTE HYDROGEN EXPLODES— Fill two balloons with hydrogen. Ignite one as shown in the photograph. It will blaze up with a puff of smoke. Permit the other to stand for several hours and then ignite in the same manner. This time it will ignite with a sharp "bang," indicat- ing that air has mixed with the hydrogen. MIRROR REFLECTS HEAT—To demonstrate heat reflecting qualities of а mirror use metal one instead of glass. A piece of shiny tin will be satisfactory. If a piece of glass is held in front of the heater, it will be found that it will stop the heat rays just as effectively as did the sheet of opaque material. August, 1937 BALLOON LOSES HY- DROGEN FASTER THAN AIR—The bal- loons in the photograph originally were the same size. After fifteen hours they were as shown. The small one contained hy- drogen and the large one air. The hydrogen mole- cules pass through the rub- ber with less difficulty than air molecules because of their being smaller in size.

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pis?” geld ope? xo V pore abe. nore yas and woe ze дес? елевсоР <") л escop? ape conse Fa serie? of ypre® Ad and mean

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tion that is hard to beat. As to the equipment necessary, it is far less elaborate than is im- agined by the average workman. Of course, each worker in the field has a great many special gadgets and pieces of equipment which he believes essential. In truth, they are essen- tial only to his particular technique. One of the purposes of this series of articles is to strip telescope making to its true, and remarkably simple, essential. On the other hand, it is obviously impos- sible to cover the whole field of telescope making and optical calculations in articles of this length. The broad outlines will be sketched and the major steps described. For the rest, the worker will have to rely on his own good judgment and understanding of mechanics to get him over the minor difficul- ties which are bound to arise. The worker who wishes to study the subject in more de- tail is referred to the numerous books on the subject. | During the grinding, polishing and testing ' of a mirror, the simplest home workshop, so long as it has an, assortment of common tools and a good, solid workbench, will be sufficient. The only truly essential thing is a good lock on the door, with the key reposing in the worker's pocket. Mirrors are very sensitive to heat, cold and shock. They do not make ideal playthings for Junior. The workshop must never be dusted while a mirror is in process of grinding. Particles of the rough grind- ing abrasive will Left——Mirror being polished by hand. The table shown is set in a heavy movable base. However, a barrel is a good substitute for the table. For grinding, a glass “tool” is used instead of the pitch lap shown. Below—Ex- amining the surface of the mirror for pits. A reading glass is used for this test. An out-of-focus sun spot reveals pits and scratches on surface of mirror.

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A drawing of the mirror grinding machine. Power obtained from the electric motor is transmitted to the two turntables through the shaft A. Gears reduce the speed to sixty r.p.m. for the eccentric table S, and to two r.p.m. for the grinding table G. The slot I makes possible adjustment for the eccen- tric motion of the arm H. This arm is hinged at J to allow removal of the mirror К from the “tool” І. The belt for connecting the two pulleys is not shown. M is a counterbalance for adjustment of pressure of mirror against "tool." invariably get on the surface of the mirror and scratch it. Therefore, women with dust- ing apparatus must be relentlessly kept out- side. The only known way to do this is with a lock. If it is planned to place the mirror in one : of the more elaborate metal mountings, cer- Above — Diagram ~- SUN оча а tain power tools will be found necessary, or gri nding mirror by | at least a great help. This however, will be Ludos Ene dE SEI discussed in the third of this series of articles, handle for the mirror. f i : ; А A glass “tool” is under jo which deals with types of mountings. = the mirror. Blocks of ak There is one other necessary piece of equip- the “tool” in place dur- i ment—a mechanical bent of mind on the part ing grinding operation. | i of the workman. This problem, however, usually solves itself, as anyone interested enough in telescope making to attempt it seri- ously is almost always at least a passable workman. The following items and equipment are necessary to begin the grinding and pol- ishing of a six-inch mirror. (A mirror of that size has been chosen for this discussion because it is simple to grind. If it is designed to have a speed of F. 11, it need not be made parabolic. However, mirrors from four to ten inches may be ground with only slight variations in the methods described in this series of articles.) The items in this list are the bare minimum necessary to attempt to grind a mirror: FOCAL 0—1 LENGTH REFLECTION OF SUN ` Diagram showing rough test for de- | termining the focal - \ length of a mirror. \ An image of the sun is brought into \ focus on a white board or wall; the distance between the image and mir- ror is focal length, MIRROR NI M

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1. Two circular pieces of glass, six inches in diameter. One will form the mirror, and thé other the tool. The glass which is to be made into the mirror should be Pyrex. An- nealed glass will do, but Pyrex is far superior. The tool may be of ordinary glass. The mir- ror should not have a thickness of less than one-sixth of its diameter. The tool may be of lighter material. 2. If the mirror is to be ground by hand, a barrel or other circular stand will be neces- sary. The workman walks around this as he grinds. : 3. One pound of pitch, or black asphaltum. 4. Carborundum in the following grades: No. 80, No. 220, FFF, No. 320, No. 600. Various workers prefer different grades, but the above is a good working average. Some M. 303% American optical emory will be found useful, as described later. 5. One pound of optical rouge. The entire system of mirror grinding is based on a remarkably simple physical prin- ciple. If a disc is shoved, under pressure, across the surface of another disc of equal hardness, there being abrasive between the two, each stroke covering about one-third of the diameter of the lower disc, and if the upper dise is rotated in such a manner that the grinding is equal on all portions, the two dises will become spherical, the lower being convex and the upper concave. As we are seeking to produce a concave mirror we may disre- A closeup of the grind- ing table with mirror in position for grinding. Machine is set for spot grinding. Although mir- ror grinding by hand is both interesting and good exetcise, after a time it tends to become monot- onous and for this reason many telescope makers find it an advantage to own their own grinding machine. The grinding table shown, turns at two r.p.m. while the eccentric table turns at sixty r.p.m. 78 gard the lower disc—which is known as the tool. It is a good plan to make a template as a guide. This is done in the following manner: Having decided on the focal length of your mirror fasten one end of a piece of strong cord to the floor and with a radius equal to twice the focal length of the mirror describe an arc slightly more than six inches in length. Take a segment of this arc equal to the diameter of your mirror and cut a template of tin reproducing the curve of this seg- ment. By placing the template against the the face of the mirror you can easily get a rough check on how close the glass is ap- proaching the desired curve. This test is, however, too crude to be accurate beyond the rough grinding stage. The simplest way to produce the desired grinding motion is to shove the disc by hand, at the same time walking around a barrel. Perhaps a dozen strokes are given in one po- sition before the worker moves in his circular path. The mirror is also rotated slightly in the hands as the grinding is done. The abrasive necessary for grinding is fur- nished by the carborundum, which is damp- ened and placed between the glass surfaces. А

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The greater the pressure applied, the more rapidly the work will progress. The coarsest grade of carborundum is used first, being followed in order by finer grades. The pur- pose of the first coarse abrasive is to rough out the general shape of the curve, which, in a six-inch, F. 11 mirror, will be about .05-inch in depth. The successive grades of abrasive bring the curve closer to the exact shape wanted, at the same time polishing the sur- face, and removing pits and irregularities. The final polishing is done with rouge. Before beginning to grind a mirror, it is absolutely necessary to decide on the desired focal length. A length of 66 inches has been chosen, as this is very convenient. The focal length of a mirror is the distance between the surface of the mirror and the point where the image reflected by the mirror comes to a sharp focus. The “speed” of mirrors is numbered in the same way as the lenses of cameras and other optical apparatus. That is, the diameter of the mirror is divided by the focal length and the resultant ratios characterized by the letter "E." A six-inch mirror having a focal distance of sixty-six inches is therefore said to have a speed of Е. 1:11, or merely F. 11. Having decided on the focal length of the mirror, the progress of the work may be tested in the following manner: Take the mirror out into the sunlight, drench the face with. water, and set it up on its side so that it casts a reflection of the sun on some vertical white surface such as the wall of a house. Move the mirror back and forth until the image of the sun comes to the sharpest possible focus. The image should be about one-half-inch in diameter. Then measure the distance between the mirror and the image of the sun. This will be the present focal length of the mirror, and cor- rections can be made accordingly. Don’t expect the focus to be very exact dur- ing the early stages of grinding. Rough grind- ing should be stopped when the mirror comes within four or five inches of the desired focal length. At this stage it is better to have the focal length too long than too short. Fine grinding continues through the vari- ous grades of carborundum. It is essential that each successive grade of abrasive re- move the pits left by the previous grade. The pits may be easily seen by the appli- cation of the following test: Take an ordinary reading glass and place it between the mirror and the sun in such a way that an out-of-focus image of the sun falls on the surface of the mirror. This image should be about half an inch in diameter. If the surface of the mirror contains pits, it will appear frosted under the illumination of this concentrated sunlight. If all the pits left by the previous abrasive have been taken out, it will appear clear. By moving the disc of sunlight over the entire face of the mirror, it is possible to make a good check for pits. The testing of the focal length should be continued throughout the fine grinding stage. As the mirror comes closer to the desired fo- cal length, the testing will become simpler and more accurate. Great care should be exercised in cleaning the mirror with water whenever making a change in the number of abrasive. A single grain of the coarser grade of carborundum will scratch the mirror and make necessary a return to coarser grinding. The worker should “feel out” the mirror as he grinds. When the feel tells him that the carborundum is no longer cutting, fresh abrasive should be substituted before the work is continued. Although mirror grinding by hand is both interesting and good exercise, it does tend to become monotonous. This is especially true when the worker begins on his second or third mirror. For this reason, many workers find it an advantage in the long run to construct a grinding machine. The base of the machine shown in the ac- companying diagram, Fig. 1, is a sturdy wooden bench. The shaft A runs in two bear- ings fitted into either end of the bench. This shaft has two worm gears, B and B’, which mesh with the two large gears, C and C’, These in turn drive the shafts D and E. The gearing should be so arranged that the speed of the table G is 2 r.p.m. that of the table S 60 r.pm. A system of belts and pulleys may be substituted for the worm gears. The long arm H is pivoted on the eccentric T. This provides a sliding motion of the mir- ror K over the tool L. The arm H is hinged at J to allow the mirror to be lifted from the tool M is a counterbalance and should be ` so weighted that there will be a light pressure between the mirror and the tool An old coffee box filled with lead will do for a weight. It can be slid along the rod until the proper balance is achieved. The shaft O' runs through a bearing at Q. It should be allowed to rotate freely. In this way the mirror will be turned slowly by fric- tion in the opposite direction from the tool. [Continued on page 140] 79

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HERE are few subjects, if any, that create more general interest than the weather. If you are like the average American, the first item you read, when you pick up the evening paper, is the general forecast of weather con- ditions. The study of the weather in all of its many phases provides an interesting hobby that can be pursued by any man or boy. A recording rain gauge is only one of the many homemade weather instruments that will find practical application in the amateur meteorologist’s observatory, but the building of this interesting device will definitely prove the merits of this hobby and spur you on in making other forecasting instruments. The rain gauge, about to be described, not only indicates, graphically, the exact amount of fall, but shows, directly on the graph cylin- der, when the rain began and when it ended. Though its accuracy is comparable with the most costly of laboratory instruments, this recording gauge can be built for less than ‘two dollars. Procure, first, a one dollar alarm clock, with a three-inch diameter face, to be used for rotating the recording drum. Remove the glass face and also the hour and minute hands, then to the minute hand rod, solder a strip of metal about 3% inches long with the ends bent up about 34 inch at both ends, at right angles to the face of the clock. Cut a disc from stiff cardboard 4 inches in diameter and to it fasten two right angle clips of l4-inch flexible steel. They should be placed opposite each other, 334 inches apart and fastened to the cardboard with small bolts. The clips serve to hold the re- cording drum on the face of the clock. Punch two holes in the cardboard disc for 80 OLD ALARM EACH END TURNED UP ENDS OF. METAL STRIP GOES THRU CARDBOARD

EM _ CARDBOARD -. ТО FIT OVER —- С CLOCK FACE

COUNTER-/ V WEIGHT <I! FROM HOOK FOR SPRING CROSS ARM SUX i/4" X 1716"

1/2" SQ, BLOCK OE BALSA WOOD TO HOLD PEN The rainfall for a given period is recorded on a cylinder to which is fastened a graph paper chart. An alarm clock, from which the face and hands have been removed, is fitted with a metal strip, soldered to the hour hand, to permit attachment of the chart drum, as shown above. Details of pen holder, drum clip and dise for supporting the chart drum are also indicated. the upturned ends of the strip soldered to the clock shaft. The cardboard disc is next set in place with the two metal ends pro- truding from the slots provided for them after which the two metal upright strips are Modern Mechanix

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Operated by an alarm clock mechanism, this record- ing rain gauge provides the amateur meteorologist with a very accurate weather station instrument. - RAIN GAUGE amateur weathermen clinched to hold the disc in permanent posi- tion. For the recording drum, get a cardboard carton that is exactly 12 inches in circum- ference. An empty salt container works very satisfactorily. The two right angle drum clips will hold a drum of this size in perfect position by cutting the bottom out of the drum so the [Continued on page 130] THE FINISHED RECORDER SHOWN WITHOUT OUTSIDE BOX, MESI 9"X 20" OIL CLOTHED - HOUSING ee e RECORDING DRUM VJ FLATTEN END OF FLOAT WIRE SUPPORT- PUNCH OUT SMALL HOLE ING SPRING | E бы COPPER SHEETING FLOAT ЕЕ i CAP,WITH 3/32" HOLE FOR FLOAT WIRE SIDE ARM -1/4" COPPER TUBE DRUM CAMION CAR- TON C RED x WITH СААР PAPER | CIRCUMFERENCE OF DRUM IS 12" BOX SUPPORT TO DRUM СОРРЕВ \ FUNNEL PEN-MADE FROM DRAWN HOSE OUT GLASS TUBE Ud The rain gauge, proper, consists of a 115"x10" copper tube into which is inserted a cork float. А A length of No. 12 wire connects to cork for is depicted here. When in use, the device is д \ operating the реп arm. Rain is collected in a protected in a 9"x9"x20" oil cloth covered box. BLOCK WITH 1 5/8" HOLE 2” funnel, passing into gauge through a rubber Mount the recording drum on a support of | TO SUPPORT FLOAT TUBE tube. Details of the graph drum and glass sufficient height so glass pen contacts chart. pen, shown above, are described in the text. August, 1937 | 81 The rain gauge, as it appears when completed,

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Build A Bellanca “Gas Model Plane by Fred C. Tuxworth CONCLUSION HE wing is constructed along conven- Чопа] lines. (Study the plans). Much time can be saved in rib-making if thirty-two pieces 10%” x158" are cut from 38” hard sheet balsa and pinned together in two or three blanks. The rib pattern is marked off on both sides of each blank and cut with jig or bandsaw roughly to shape. The cutaway por- tions and the spar slot are cut with a jig saw. Use the coarse sanding block for finishing. The leading and trailing edges may now be cut and shaped and the wing assembled. Glue all joints securely, utilizing all possible area. Brace the frame with linen thread the same as the fuselage. The tip ribs are formed by running ¥%” sq. strips over formers, and the root rib is 2; balsa curved to fit the fuselage. The sheer pin tubes, one inch sections of 14” diameter aluminum tubing, are glued and lashed into position, and the two inside ribs are covered with gy” balsa. The basswood blocks for strut fittings are pinned and glued in place. The leading edge former ribs are yy” х фу” soft balsa and are sanded to shape after they are placed and glued. Ailerons 82 Details of wing construction, rig- ging and assem- bly appear in this final installment. are optional, but advisable, and may be hinged with soft iron wire. The stabilizer is built like the wings. The rear spar is replaced by a piece of 1⁄4” diameter drill rod at the center to fit into a tube for the stabilizer hinge. The fin ribs are \” square strips bent around the fin spars. The hinges and fittings for the tail surfaces are clearly shown in the drawings. Both ad- justment screws are made from 1” diameter brass brazing rod, threaded with a 6-32 die and slotted for a screw-driver. Fittings for the tail surface brace wires are bent as shown from .020 piano wire. The brace wires between the fin and stabilizer have hooks bent in each end so they can be removed. Those between the stabilizer and the bottom of the fuselage are equipped with turnbuckles to keep the whole assembly taut. Rigging the wings is the next step. This is an important operation and must be done carefully. The center section spars are б; square balsa with sheer pin tubes lashed on either end as in the wing. Place them in their approxi- mate positions in the fuselage and slip the wings in place, using white pine dowels for sheer pins. The spars are not glued till after the wing is properly aligned. Set it at [Continued on page 84] Modern Mechanix

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x Me" D... [TEE is BEVELTIP TO- В FT Wine > я

тг: WING ТІР i Мә" 378"

= ig 5 P" 5" з" lal a tla BASSWOOD ru Т] № Suit ron n 1427116771167 28—24 16774 216—7 am PEN IS T i6 ALUMINUM —- LE k SCALE RIC SHT. END => i UR ^ sy Á | SELYING RIG 5 ХВ ROUNDED SPRUCE

SAND TO STREAMLINE

STRUT BLOCK DETAIL

FORM AFTER i GLUE INTO SLOT- " 3 i 3/16" DIAM FILL IN WITH JOINING di N PINE DOWEL і Е \ a | = анор Y £4 I о TUBE і & b a i H 2 i | Е zl Fo i a i А ш t, ii ul PINS С 20 ist se | fl $E INE SECTION THRU zi Е TEE ў | | Е COMPLETED STUB Siu =) ш à Ln 4 ee Fap ш Le R ui ie Eli sss n EE wi 2 ti 9 5 ii STRUTS РЕ & =H i dI GO HERE 5Е 5 $ E 1 x 9 Е 1 я ü | 2 a | Bp oc 4 DIVIDE AND "oc 2 E | = == | Е E x18 SOFT EE = is es T 5 2 i T SHEAR PIN BALSABEVEL 5 ше == X 1 TUBE AFTER AND GLUE TO ale I 4 ёа | 1 FITTING STUB PORTION Ze Е но шт | 5555 AFTER SETTING 2) p і 95 | "SES WING AT SCALE Ы ] 2 | 25a DIHEDRAL AND 2 ш | | gu | Seve DEGREES INCIDENCE e bw | og 8 $ ce -b Is. Е ТУ а = об: = F5 = f d о cc o-n "| А & ше = Т NMERT: Lj 3 "NE: k—~ if < 40 | 2 Зтов 8 STRUT LAYOUT ü 58 č FUSELAGE STRUT SECTION 4 STRUTS REQD. z — eS 3 DETAIL OF WING STRUTS AND STUB FITTINGS Е ag | m ш 5 «Qi s z aie - B | ug u i fea 2 N = $90 | 3| v7] 1 x ча 2 -— ЈОМТ АТ | X og | o or x und j TRaILING | © й аб | $ "4 A b 3 £8 | a- SAND LATER TO a | E Н so | S174 COMPLETE RIB ш E [ | Bis j CONTOUR Q zi 2 ] |= ў ш j T D SOLID AT ROOT E S| 59 zm А £ a] = T < ao | x S 26 МЕ x o - | i E: 1 SOFT BALSA [2 2 S8 a е" o € m 8 с CEMENTING Е [7]

S Mew. COMP. MEMBER f x. 5 ORILL 16 FOR SUPPORT

con | ++ H Aeron spars oF "У-У j EL ЗОО —— LE MAT. CUT OUT AILERON -H + eS - Wer [+ RIBS HERE LATER | = | REAR SPAR [Stee eel 81 j Й NOTCH | a | А ЕЕ I 110 CL ОМЕН 374" +f, pan 1 7 | И 2 T /16" 22 - IE ri 1 Wb AILERON SPAR | LLLI | | DETAIL OF SPAR TIPS NOTE: TIP FORMERCTE) WING RIB PATTERN — I/4"SQUARES SPARS TAPER AS FOLLOWS - T.F #1 FROM t5716" TO 5/I&"AT ТІР —— TF #2 FROM 11/8" TO 1/4" The wing of the Bellanca “gas” model is constructed along conventional lines, but a careful study of the above plan should be made before actual construction is started. Note that some parts are made of hard balsa while others use the soft grade. Time can be saved in making the ribs by cutting one to the shape indicated on the rib pattern and then pinning five or six balsa blanks together, using the carved rib as a pattern for trimming the blanks to shape. After shaping, the ribs are notched out with a jig saw to provide the spar slots and to reduce weight of the completed wing. ` August, 1937 83

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two degrees positive incidence with the thrust line, and be certain it is the same in both wings. The dihedral in flying position is 6” and scale position 3”. This can be varied by changing the strut positions from the inside tq the outside holes of the strut fitting blocks. Measure the distance between the tail post and each wing tip to check alignment. After the plane is finished the sheer pin tubes receive white pine sheer pins. In case of a severe impact the pins will break before the wing. Replace them and the plane is ready for another flight. The struts are made according to the draw- ing from soft balsa and spruce. Two-inch sections of the struts are glued to the lower longeron so that they jut straight out as on the real Bellanca. The wing is then set on scale dihedral by resting the tips on blocks. The struts are cut to the correct length by fitting, and beveled to fit the stubs. Then they are fastened to the outside holes of the Construction of the cidence of the stab

faces and method of regulating the in- the plan and detailed sketches below. blocks in the wings and glued securely to the stubs. The short bracing struts can then be bound and glued in place. When the struts are dry they are cut off one-half inch from the fuselage. Drill them and place in the sheer pin tubes. Use straight pins to secure the sheer pins in position. You are now ready to cover and finish your model. First see that all holes and unsightly joints are smocthed over with crack filer. The celluloid for the windows should be put in place and the windows outlined in the covering material Added realism may be obtained by adding a thin sheet aluminum wing fillet, air speed indicator, and a venturi tube. Cover with bamboo paper using air- plane dope or any standard commercial prod- uct for an adhesive. All wood parts except- ing the N. A. C. A. cowling should also be covered to provide a better surface for the finish. The N. A. C. A. is given several coats of lacquer sur- facer and sanded. This will Bellanca's tail sur- ilizer are shown in

T } S20 eee DAA | МО Ey 23" | sueETBALSA SoBe 7 4 Hi 4 j BOTH SIDES =Z- | | |... BASSWOOD [—— | LH Lt p ms | | 8 " Г on bue MAN j HM — 78 He — 3} > Te SPAR | 2 COMBINED FIN & RUDDER PLAN- SCALE AS IN STABILIZER К 3. . } Ko. $ а SN. CY NE ua NOTE MANNER OF fZ | à 1 PA SAM RIB CONSTRUCTION ^ ib ; /, 7 /^ f A M V " x A | 7 E SOLDERNUT free l if Ё y СЕ aues [| PZ Sou 148" DIAM, DRILL ROD / ! А 2 ЧАРЕ FROM GLUED'& BOUND TO SPAR R/ Р FITTING ffi fee 1/6" SHEET сЕ аас END FORMER М РЕ | № ў CROSS MEMBER ATSTATION# X= cuT FROM И RECEIVE 2" d £ C AM S ver SHEET И „æ WOODSCREW $ R ADJUSTMENT. SESS MALA TURNBUCKLE ` JT i W ~ 8 рань 7 NNNM. ^F" зо pea To ROD SG ! a TORVE | > COLLAR r LONGÉRONS N NUT SS 15 LONG epee OFFSET TOS HARD АШ. М SREE BELOW LONG. FITTING Men rn ee ALUM. SLEEVE DRILL Wie", HOLES 3/4" SCREW SLAMS) Block aT SS Wo» T FOR BRACE WIRES BLOCKS TOGETHER) STATION#! p > ee TO STAG! SLOT gr v a А DETAIL OF THE ADJUSTMENT DETAILS DETAIL OF STABILIZER ATTACHMENT E 84 SCREW ASSEMBLY- 2 REQ'D.

RUDDER ASSEM Modern Mechanix

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MASK OUT WINDOWS THUS CUTTING OUT TO SUIT THE OPENINGS AS INDICATED IN FUSELAGE PROFILE DWG. COVER ENTIRE PLANE EXCEPT N.AC.A. COWL m. WITH BAMBOO PAPER “| DOPE 2 COATS CLEAR i Y AND FINISH WITH PIG- BAMBOO MENTED DOPE OR LACQUER PAPER STABILIZER ADJUSTMENT d BIND AND GLUE TO LOWER LONGERONS WHEEL MAY BE HARD WOOD NS OR SMALL RUBBER(SOLIDIBALL =~ WSS DETAIL OF TAIL WHEEL FITTING give it a smooth metallic ap- pearance. Apply two coats of dope to ihe covering and use very fine sandpaper to remove any noticeable fuzz. Lacquer cr pigmented airplane dope is used for finishing. Although the color scheme is entirely optional, it is suggested that elabo- rate arrangements employing scallops and curved lines be avoided. They may conflict with the beautiful, conservative lines of the ship, making it appear gaudy. All that now remains is to provide for igni- tion. The coil and the condenser are held on the plywood gusset between the landing gear legs with narrow metalstraps. The batteries are encased in a tube of fiber and fastened with rubber bands to the battery slide. They can be moved fore and aft to shift the center of gravity. The battery slide is removable, being held in place by aluminum clips which fasten to the lower cross members, and is se- cured by a wood serew. The propeller is, of course, dependent upon the make of engine used. Any of the companies manufacturing August, 1937 free after the _ —— WINDOW DETAIL CELLULOID SHEET LAID OVER ENTIRE SECTION WHERE SIDE WINDOWS OCCUR ye RUDDER „Ё ADJUSTMENT, MISCELLANEOUS —== DETAILS = SS — Е Details of the final assembly job are shown above. Wing fairing is cemented to fuselage only so that in the event of a bad landing the wing can fall shear pins WING FAIRING THIN ALUMINUM SHEET SHAPED TO EXACT WING CURVE.CEMENT TO FUSELAGE ONLY — NOT то WING FINISH N.A.C.A. COWLING WITH LACQUER SANDED N BETWEEN COATS EXTERNAL FAIRING STEP. MAKE 2 THUS FROM 1/16" DIAM. PIANO WIRE -GLUE IN PLACE DRILL FOR 3/32" WIRE 3/64" HARD ALUMINUM SHEET PATTERN FOR TAIL WHEEL FORK engines will gladly furnish you with a propeller design for their engines. If, however, you use a homemade engine, you wil be forced to design your own. For easy starting a booster of two or three dry cells is advisable. To employ this, bare about one inch of each of your battery leads. Bend them double at this bare spot and twist them. into rigid prongs. Press these prongs through the veneer just in front of either of the doors and glue them securely. Bet- ter yet—use an ordinary phone jack. To “cut in" the booster, an assistant, (and they'll be plentiful!) can press the positive and nega- tive booster wires to their respective battery leads and hold them till the engine is running satisfactorily. Pick a windless evening or dawn and a fairly large, smooth field for your test hops. Glide the ship for balance by pushing it off the ground a little way. Adjust the batteries till it settles gently to the ground when the stabilizer is set at zero degree incidence to the [Continued on page 138] break. 85

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With the chassis con- structed аз described in previous installments, the racing fan is now ready to build the special body. 20 GA. RIGHT- ANGLE FITTINGS SQUARE TUBING Although it has the aspects of the finest full-size racing car, “Arlen Special”, shown here with Don Arlen, is constructed entirely from parts of junked autos. by Manley Mills PART III HE phenomenal success, during the past few years, of midget automobile racing has prompted hundreds of home mechanics and craftsmen to undertake the building of midget cars from whatever odds and ends they could salvage from old automobiles. Realizing that the popularity of the miniature racing car was steadily increasing, a lead- ing West Coast racing car designer, Don Arlen of Hollywood, set to work on designing a truly authentic midget racer that could be constructed from materials procurable at any auto graveyard. The resulting car proved to be a masterpiece in custom racing car design, since it not only had been assembled from motorcycle and automobile parts, but featured a front-drive transmission—a feature usually found only on custom-built racers costing Left—The gasoline tank is constructed from galvan- ized iron and shaped to fit in the tail of the “Arlen” body. Tank is installed in a rack formed from ^" sq.. 20-gauge steel tubing. Below this is shown completed instruments panel and cowl framework construction. Modern Mechanix

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m POST =e / STEERING BRACKET N BODY FRAMEWORK \ (SEE DETAILS) & -— АЕ JOINTS ARE ELECTRIC WELDED 22 SX EE 30 us 72 SQUARE TUBING 20 GA. GAS TANK SIDE RAIL DETAIL OF CORNER This head-on view provides a true conception of the in- genious construction employed in the front-drive mechan- ism. A four-cylinder motorcycle engine provides the motive power to the converted Ford А transmission. Body frame consttuction is shown in upper diagrams. $2,000 or more. Probably the most amazing fact concerning Don Arlen’s racer was the cost. After all work had been finished and the car was ready for its first run, a check-up on expenses showed that the total investment was less than $100, or about one-twentieth the price of a factory built car! August, 1937 In the foregoing installments, which ap- peared in the June and July issues of Мор- ERN МЕСНАМТХ, construction of the chassis, axle, steering and front-drive mechanisms for the “Arlen Special" were discussed in detail. The builder has now reached the point where he is ready for making the racing body. 87

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Detail of the cowl and gas tank frame construction is described in the schematic plans at left. Frames are formed from 1/2” sq., 20-gauge steel tubing and all joints securely welded. Above-—Completed cowl. The cowl, tail, and hood are made from 22-gauge body steel. You can easily make the hood and cowl—and possibly the tail. How- ever, you can have them made at any sheet metal shop for a nominal sum. It’s much easier to build the cowl without the 3” flare, but it adds so much to the ap- pearance of the car that it is well worth in- cluding. The tail and cowl are riveted to- gether, then the right-angle strips, made from body material, are riveted along the bottom edge on each side. These strips will rest on the side rails where they are bolted with 1⁄4” bolts. Hood and radiator shell are made in one. The pointed nose is made from half of an auto headlight shell Bend a length of 3” square tubing to fit inside the front end of the hood where it is welded. Also weld the nose to the tubing. Ordinary screen wire is used to form the front end. A piece of 34” rod, extending down about 2", is welded into The "Arlen Special" body is formed from 22-gauge steel. 'The body is shown here before being installed on chassis over the cowl and tail frames. Modern Mechanix

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Gear shift levers on the “Arlen Special" are conventionally located on the outside of the chassis as indicated in the photographic decrip- tions at upper right. the ends of the square tubing. These rods slip into short pieces of round tubing, welded to the inside front ends of the side rails. Ordi- nary auto type hood fasteners hold down the hood. The rear end of the latter and the front end of the cowl rest on hood lacing, riveted to the front part of the cowl frame. A snappy paint job will add greatly to the attractiveness of the car. The color scheme is, naturally, optional with the builder, but as a suggestion a chrome yellow body and chassis, with red wheels, trimming and let- tering, is a good contrasting job. August, 1937 Profile and top views of the body, shown here, contain ali dimensions for building a true-fitting racing shell. Anyone with average driving ability can easily handle this ear up to about 65 miles per hour, without any previous practice. How- ever, beyond 65 miles per hour conditions change rapidly and it is then when you must exercise skill and caution so as to keep the car rolling on all four wheels. Numerous tests runs have been made on the Legion- Ascot speedway near Los Angeles, [Continued on page 126] ge

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. Бу Hi Sibley —— — Cranksuart Curonictes- - ALL RIGHT, CHARLEY SCRUNCH / — AND TAKE A LOOK AT MY CARBURETOR WHILE YOU'RE. THERE E d А ЕЕ Г a A a 2 THE HIGH, WIDE AND HANDSOME” HOLSMAN" COULD ALMOST STRADDIE A TRAFFIC COP, WHILE THE "CRESTMOBILE " WENT TO THE OTHER EXTREME AND WAS DESIGNED TO PARK UNDER THE PORCH. TESTED KINKS FOR THE MOTORIST Bicycle Grip Insulates Screwdriver VERY auto mechanic knows that shocks received while working on high tension ignition circuits are by no means pleasant. If you own a screwdriver provided with a wooden handle it can be thoroughly insulated by fitting it with a bicycle handle grip. If the wooden handle is too large to accommodate the rubber grip, trim it down, with a rasp or pocket knife, to a firm fit and shellac the grip in place.—Bob Poulson. Hot Water Bag Forms Door Pocket F YOUR car or truck lacks a door pocket, a service- able one can be made from an old hot water bag that is no longer usable for its intended purpose. With a pair of scissors, cut off the metal stopper and the front of the bag, to a depth of 4 inches from the top, so that a rubber pocket is formed. The door pocket is installed on the car by sewing it fast to the upholstery.—R. Paul. 25 x ALU ogy is 90 Modern Mechanix

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TIPS FOR THE AUTO ENTHUSIAST An Automatic Clutch Release TTACHED to the brake pedal of the car, this device automatically releases the clutch when the brake is applied. А ^V" bracket bolted to the brake pedal arm is pro- vided with a hook on one end for engaging a slotted adapter which claps on the clutch arm. When the brake is depressed, the bracket pulls down the clutch at the same time, thus freeing the gears. But when clutch pedal is depressed, it works independently, having no effect on brake pedal.—L. W. Hochheimer. SPOKE 3/8" PIPING -TWINE WOUND AROUND AND PAINTED craft. F'SPOKES OF OLD WHEEL CUT. - DOWN TO 178" "Trip" Valve Prevents Theft UTOISTS ward off car theft by inserting a "trip" air valve in series with the gas line of the car. Connect a tee fitting, in the line, to which is connected a vertical length of copper tubing, fitted with a spring petcock, held closed by a simple trigger hook. A wire from the hook to drivers seat permits opera- tor to render car inoperative.—J. E. Hogg. SMALL WING MIRROR ATTACH- ED TO REAR VIEW MIRROR WILL GIVE REFLECTION OF CAR COMING FROM LEFT August, 1937 DETAIL AND ` BASE OF AOD SECTION « WHICH SLIPS INTO SEIN SLOT GROOVE SIDE VIEW OF A CLUTCH. DISENGAGER A Steering Wheel For Midget Cars IDGET car builders will find this flexible steering wheel a worth while accessory for their diminutive Get a steering wheel from a Model T Ford and, with a hacksaw, cut away the spokes so that only the hub remains. Allow just enough of the spokes to remain on the hub so that holes can be drilled for inserting bicycle spokes. Form the outer rim of the wheel from a length of 34-inch iron pipe, bent to a diameter of 10 inches and welded at the joint. for the bicycle spokes, insert and draw all 16 spokes up tight. Complete the wheel by winding twine around the pipe and finally painting.—L. D. Bailey. Drill holes in the pipe 2] а \-TRIGGER EAS LIN CÒNTROL WIRE TUBE В НН PE F FUEL SUPPLY у GASLINE) $ CONTROL с TO TANK" | WIRE TAGOINNECTIGM ,PETCOCK N i TCOCK LEVER \ SPRING , K РЕТСОСК LEVER . Д COIL SPRING T-CONNECTION SECRET RING Winged Mirror Aids Driving N MODERN automobiles the rear vision header type mirrors are of little value so far as reflecting images of cars approaching from the rear left as in the case when one car passes another. By fitting a winged mirror along the righthand side of the header mirror this most common road hazard can be re- duced to a considerable extent. Any glazier wil supply a small mirror, for a few cents, which ean be attached to the original rear vision mirror with adhesive tape.—L. Read. 91

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Nn ARN Е OLD KNIFE OR SPATULA APPLY WARM COMPOSITION Few motorcyclists realize that it is mot mecessary to cast off their ignition batteries when a leak developes in the hard rub- ber case. Black transformer wax, heated and applied to cracks willeffectively seal leaks. STRAP TO TOP OF TANK f BLACK COMPOSITION FROM USED ORY BATTERY MELTED BELL CRANK ACTUATES STOP WATCH TRIGGER — OUTER CASE OF RUBBER OR моор INNER CASE OF SWILL TANK VELVET-PADDED THOROUGHLY wood Mid PLAIN WATER АМ 2 SWILL OUT WITH THEN DRAIN METHYLATED SPIRITS The inside of a motorcycle gas tank can be freed of sediment by flushing it out with water, applied with a hose. Methylated spirits, swirled around in the tank, will effectively absorb any remaining particles of water. CONNECTING STRAPS EACH SIDE OF CASE STIFF PAPER CONE A : р | А TINY HOLE АТ ТІР dE The time required to cover a given distance can be accurately deter- = Я mined with this rider-operated timing device. Mount ап ordinary SA stop-watch in a sponge rubber cushioned box so that the stopping and } starting pin is directly opposite the bell-crank. Connect a spark control cable to the end of the bell-crank, as shown, so that when the handlebar iever is pressed by the rider the stop-watch goes into oper- ation. Adjust timer by experiment and mount over gas tank. A substitute grease gun for lubricating transmissions can be fashioned from a paper GREASE cone formed as shown. OUT TO FORCE DIP IN SOLDER AND T RUB ON PLATE | When making repairs on copper gas lines the use of a brass plate, smeared with flux, will insure a well tinned soldering iron that will re- main thoroughly clean and bright at all times. . e e Leaks ín fuel lines can be permanently fe- е MY paired by cleaning the surface with steel wool, ) FLOW SOLDER tinning and winding copper wire over the EVENLY OVER break. Seal by flowing solder over wire. WIRE BINDING Modern Mechanix 32

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Kinks For Summer Campers ORDINARY TYPE OF CAMP STOVE. BURNER THE NEW RING, Cellophane Protects Fishing Lures HEN worms, grasshoppers or minnows are used for bait when fishing in swift streams they are fre- quently washed off the hook by the current. This very disgusting trouble can be prevented by forming a small cellophane bag and tying it over the bait, leaving only the hook exposed. Under water the cellophane will not show and fish will bite at the line just as readily as they would if the cellophane were not there.—Emil J. Novak. ATTACH HOSE TO WATER OUTLET PIPE OF OUTBOARD MOTOR Canoe Rolled Ashore OnTires ANOES and small boats can be rolled ashore single handed without loading them on a trailer or skid. Secure two large tire casings and slip one over each end of the boat pushing them over the craft as far as they willgo. The canoe or boat can then be rolled to the boat house or garage without damaging the canvas. Larger boats can be handled in the same manner as small craft simply by substituting large truck tires.—A. Н. Waychoff. August, 1937 Making Stove Burner Rings UT THE o AMP stove burner rings that no longer EWER will produce a satisfactory flame can be ск CASE IN . . . » ERSTRIPS OF replaced inexpensively by substituting sec- al ist tions cut from a kerosene wick case. 9 Cut the wick case into strips identical in width to those on the camp stove. Remove the screws holding the burner top in position and lift out the original ring. In replacing the worn out ring with the wick casing it may be necessary to crimp it so that a perfect fit is obtained. The camp stove burner is then reassembled and ready for use. The make- shift rings will function as well as the original rings did when new.—A. Н. Waychoff. Outboard Motor Heats Camp Water LTHOUGH considered as a luxury by most campers, hot water has innumerable uses about the camp. If your equipment includes an outboard motor an adaquate supply of hot water is always at your disposal simply by attaching a length of rubber hose to the discharge pipe of the circulating system of the outboard. The temperature of the water flowing out of the engine is approximately 110 degrees.—E. J. Novak.

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CONDITIONING YOUR BOAT WASH BOAT THOROUGHLY WITH STRONG SOAP POW- DER. WORK BEHIND BULK- HEADS AND _INTO loc~ SCRAPE LOOSE DIRT AND SC KNIFE. fury y LOCATE Y SOFT / \ |А FLUSH WELL AFTERWARD WITH HOSE OR PAILS OF WATER After a winter's storage, boats should be removed of their tarpaulin and allowed to dry out in the sun. The interior and exterior of the craft should then be scrubbed with soap and water. If dry rot is present kill by pouring salt in cavity. WHERE PLANKS ARE CRACKED, BORE 3/16" HOLES AT BOTH ENDS. FILL HOLES WITH SOFT WOODEN PLUGS AND THE CRACK WITH SEAN FILLER Q s PLUGS CAULK WITH A SINGLE STRAND N SF CANDLE WICK, 24 м IN GLUE. 522 | FORCE IN LIGHTLY AND FILL WITH SEAM FILLER REPLACE FAULTY BUTT BLOCKS WITH NEW. OVERLAP THE PLANKS. SCREWING FROM THE OUTSIDE, COAT FIRST WITH GLUE. A i 0 E За (i : IL Cracks in hulls can be repaired by drilling holes at each end of crack and driving in wooden plugs, then screw on battens as shown above. Caulk open seams with single strand candle- wick which has been dipped in marine glue. To prevent a craft from sinking while swelling apply soft soap tp seams. BEFORE PLACING BOAT IN WATER RUB LAUNDRY SOAP OR WAX OVER BOTTOM TO PREVENT SINKING FROM DRIED OUT SEAMS 94 Ren WORBING ALONG THE STEM, PACK DUG OUT AREA WITH WET SALT. FOLLOW LATER WITH | MARINE GLUE OR PITCH FINISH SURFACE WS SMOOTHLY AND \ VARNISH A Few boats receive the atten- tion they deserve. This article tells how many years can be added to the life of your craft by proper care of the sails, deck fittings, hull and finish. by J. A. Emmett VERY hour spent overhauling and fitting out your boat, whether it be a canoe, sailboat or motorboat, the latter either in- board or outboard powered, will not only return big dividends in the way of increased pleasure secured from your outfit, but add materially to the value of your investment in hull and gear. Thanks to American inventive genius and today's wide awake manufacturers spring fitting out work is a comparatively simple matter to what it was not so many years back when less fortunate owners had to either use indifferent paints or mix their own, then wait days for surfaces to harden. Standardized small boats built of late years by reputable manufacturers are constructed of the best of materials; given halfway decent care struc- tural repairs will not be necessary for years to come. Modern marine engines, both inboard and outboards, are clean in operation and sound engineering practice insures such long life that, barring accidents, overhauls are necessary but once in five years time and even then manufacturers stand ready to give a thorough factory job at minimum cost. Better cleaners, abrasives, rot preventatives Modern Mechanix

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FOR SUMMER SAILING TO REPAIR TACKS IN CANVAS- FIRST TACK DOWN EDGES = = ALONG TEAR COAT SPOT WITH HEATED,HARD GRADE MARINE GLUE p LAY MUSLIN PATCH OVER AND SWEAT INTO PLACE WITH HOT OR SAND OFF — ESPECIALLY, IF ONLY CRACKED REMOVE PAINT WITH BLOW TORCH USE STEEL WOOL IF ONLY DULLED BUILD UP PAINTED SURFACE SLOWLY, APPLYING 3 COATS,FROM @ | THINNED TO . STRAIGHT РАМТ Vy >” Canvas deck repairs can be neatly made by applying marine glue to the torn area and allowing it to dry. A piece of new muslin or light canvas is then placed over the glued surface and secured with a hot flat поп. Old paint should be removed with a file tang and blow? torch. In repainting a boat apply a thinned coating first, slightly thinned second coat and straight paint fer the final. Use turpentine for thinning the paint. and sclvents enable the owner to secure a cleaner undersurface for later painting in the shortest possible time and quick drying paints developed especially for boat use shorten the finishing period, offset the unreliability of spring weather and give a surface to with- stand a full summer’s use. If your boat has been covered with a tar- paulin, get the canvas off the first warm day August, 1937 and let the air dry out the winter’s con- densation. Take out loose gear and remov- able fittings preparatory to a thorough clean- ing, unless removed last fall as they should have been. More washing and less covering dirt with paint will save fitting out time and money and add years to the life of your boat. Use a strong soap powder even if it dulls and washes off paint. Scrub into every corner, inside and out, especially behind bulkheads and in lockers. Scrape with a putty knife to remove loose scale and dirt and to locate possible soft spots, then flush clean with a hose or pails of fresh water. Soft spots caused by dry rot become apparent at fitting-out time. Look for them in unventilated places and where fresh water lodges. If located, do not leave because rot [Continued on page 132] IF WATER LINE IS NOT ALREAI ONTO BOTH SIDES AND INDENT WATER LINE um

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374" X 3/4" MOLDING MOLDING LY SUPPORTING T BACK SUPPOR \ЕСЕЗ CROSS Pi The benches and table each і measure 47” in length.. The above plan shows front view of bench, giving all basic dimensions. Width of back supports and runners depends on stock used. Wood salvaged f for building "this ^ bench and table a Project is not important since om old packin i n modern-style ем po зуы materials required рреаг at left. REAKFAST Nook ast nook, Assembly detail The kind of wood used in nie nce ita an enameled finish covers all surfaces, by J. B. Williams F YOU are one of those persons who have more time and ideas than money at your disposal, you can build this useful breakfast set from lumber salvaged from old packing cases which can be picked up, from time to time, at local department stores. The com- pleted project should not involve an expense of more than $2.50, most of this amount being invested in several cans of paint and leather- ette material for making the bench pads. If possible, select boxes assembled from boards of uniform width. While planks vary- ing in width can be used, considerable time can be saved by using lumber which requires no extra sawing and planing. The boxes should be salvaged carefully so that no [Continued on page 136] Modern Mechanix

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Kiddies’ “Whirl Swing” Combines Clothes LAWN clothes drier that combines a thrilling “Whirl Swing” for children can be built from odds and ends at a negligi- ble cost. The arms of the clothes drier, when not used for that pur- pose, are fitted with hobby horses to accommodate kiddie riders. Make the upright post from a length of 2% or 3-inch iron pipe and anchor it in a concrete foun- dation below the level of the lawn. Atop the post, mount a cast iron bearing unit, made as described in the details at left or, if desired, an auto wheel from which the rim and а portion of the spokes have been removed. Make the swinging arms from 5-inch by 114-inch oak, anchoring them to the bearing unit with long bolts. Attach horses, cut from 5-ply veneering, to opposite ends of arms in such a manner so as to permit their removal when not in use. Drier BEARING UNIT FROM PIPE FITTING MAYPOLE USED AS CLOTHES DRIER CAST IRON BEARING UNIT ea OR LA REMOVABLE SEAT SUBSTANTIAL CONCRETE BASE This entertaining childregs' toy is quickly converted into a clothes drier, thus serving two useful purposes. Make the upright post from a length of 3” iron pipe, anchoring it securely in a concrete base. Bearing on which the swings revolve is made as described above or fashioned from hub of an auto wheel. Animated Elephant Sprinkles Lawn With Its Trunk a a 0. mmo ава 7 sai i l FORA PANEL FOR SIDES Веи ae WIRE AXEL MAKE ROLLER à FROM HARDWOOD DOWEL S. tar ig METAL BUSHING When water pressure is applied, this animated toy elephant wiggles its ears and at the same time sprinkles the lawn with its trunk. Scrap pieces of wood are used in forming the body. Cut these pieces as shown at tight. A light spring connects to the wires holding ears so as to provide wiggling motion. August, 1937 NIMATED by centrifugal force, this lively elephant garden decoration serves also as a practical lawn sprinkler. The body and head are shaped from scrap wood, while the trunk is formed from a piece of 5g-inch copper tubing which passes through the body of the elephant and down through the right hind leg to the base where it connects to a length of smaller tubing to permit its revolving ‘around in a circle. Cut the wooden body from a piece of 1% by 16 by 10-inch white pine using a jig saw for the operation. Two pieces of plywood of similar dimensions are likewise cut to shape to form the sides. Insert the copper tubing to form the trunk and crimp the end so that a spray of water will be ejected when the elephant is placed in operation. AS NR | EAR FLAPPING DEVICE | A DELICATE SRING 97

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AWALNUT and COPPER by Dale R. Van Horn EW home workshop projects will find greater appeal during the hot summer months than will this turned walnut ice bucket. The hostess will take considerable pride in using it when serving party guests, for its antique design will undoubtedly bring many favorable comments. By slightly alter- ing the original dimensions, either larger or smaller, the bucket can be used also as a bottle chiller for tomato or fruit juices or as a smart container for candies and nuts. For the latter purpose, a spun copper lid provides the bucket with a distinctive closure. Get a solid piece of wood if possible or glue up pieces to give you a square slightly less than 5 by 5 inches and about 9 inches long. This particular job was turned inside with a metal lathe because of its depth and because the sides could be made more accurately. After the inside had been turned, the piece 98 Turn the ice bucket from a solid or glued-up block of walnut measuting 5 by 5 by 9 inches. The inside of the container is best turned on a metal working lathe in manner shown above. Modern Mechanix

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was transferred to a jig in the wood working lathe, snuggled to a tight fit, the tail stock brought into use and the outside turned down to the dimensions shown. Note that whereas the final outside diameter at the top is 4% inches, it is only 4% inches at the bottom. The bottom diameter can be 4 7/16 inches if you care to work with close figures. The slight taper is not noticeable to the eye, but it does permit the tapping of each hoop to a snug fit after the ends are soldered. Cut the copper strips for the hoops 12-inch wide and of the necessary length, including a lo-inch overlap. To make a strong, yet scarcely noticeable, joint, lay 42-inch of each end of the hoop over the top of the vise and hammer flat until the copper is approximately one-half the original thickness. Turn the piece over and make the same mark on the opposite side of the other end. Heat these ends with a blow torch, one at a time, and tin them well by rubbing with solder. Make another check against diameter, clamp the joint at one edge with the pliers and again heat in the flame. When the solder is soft, quickly clamp the other side of the joint with another pair of pliers and hold until the solder has set. This makes a joint only slight- ly more than the original copper thickness and if you have matched the outside seam well it will be inconspicuous. The next step is to tap the hoop home on the bucket. A tri- square or any flat metal having square edges will do nicely. Turn the piece in the lathe continually as you tap it in position to prevent breaking the seam. If hook is too tight, [Continued on page 134] After completing the inside turning, temove ‘the block from the metal lathe, turning down the outside to a diameter of 414 inches. Copper hoops are then driven over the cylinder and trued up with a tri-square, after which they are polished with a file and steel wool as depicted in the above illustrations showing construction through the various stages. The lid jig is turned from pine and the copper closure spun over it. After spinning the copper lid, trim off the edges and remove pine jig. August, 1937 99

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Model Railroad Builders’ Tips Miniature locomotives can be made to perform better by use of these novel kinks.

FORMED PLATFORM —3 HEAVY BRASS OF LIGHT BRASS PLATFORM STEAM CHESTS AND SAND BOXES ARE EASILY SHAPED FROM WOOD - GLUED DOWN. USE BRASS WIRE ©. ТО FORM ШР TOP PLATE я DRILLED, TAPPED BOLT IN USUAL E BRASS TUBE OF ELIMINATED Ў AND ASSEMBLED WAY TO FIRESOX CONVENIENT SIZE WITH SMALL SIZE FRONT PLATE 15 EXCELLENT EOR BRASS SCREWS Ro THE SMOKE STACK SLIP INTO HOLE (7 DRILLED TO SNUG. GOOD FIT- SLOTTED END ENGAGES TIE-ROD

POOR

SOLDERED ASSEMBLY FITTED ASSEMBLY ~ x 3 FEW PARTS UN NSS ` DRILL OUT FOR TOO MANY PARTS !|ENTIRE LENGTH OF EXAMPLES OF SOLDERED AND FITTED ASSEMBLIES 3 JRM STERS E e? EDGE IS SUGGESTED Oi MAKE FROM ANGLE BOARDS IN BOLT INSIDE

POOR MOTOR INSTALLATION [a BRASSISIZE TOSUIT) BO o EPICE = SMOKE BOX (DIFFICULT TO MAINTAIN PROPER N FILE TO SMOKE Box ee ETER is LINE UP. JUMPS OR LOCKS GEARS) IMPROVED MOUNTING Here ís an excellent instance where precision methods count. е The drive hook-up is of vital importance and must be properly A ; and permanently aligned. Note heavy brackets recommended and the neat way in which reversing gear is placed by motor. A 2 15 PREFERABLE Ww CUT SIGNAL FLAGS OUT ~. TO THE BUILT: Age OF 26 GA. BRASS SHEET "dd “ UP VARIETY provide the necessary traction. The = boiler and frame construction of "Midget Mike” as well as other Lilli- putian models can be provided with

NUMBER PLATES ^ SMALL SPLIT ВМА piNS MAKE

SECTIONAL VIEW OF CYLINDER

THIN TIN i i i фин" \ BLOCK-FILE TO REQUIRED / а beres Woods bellos BRASS RIVET MAKES STANCHIONS . SHAPE FROM SOLID can be weighted by filling them with HEADLIGHT BARREL BRASS— 2 lead shot. At the left are shown SIMPLE FITTINGS M. SCALE EFFECT — = several simple boiler fittings that any model maker can duplicate. 100 Modern Mechanix

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THIRD REWOUND AMMETER RELAY a GENERATOR PILOT LIGHT RELAY ON RADIO GENERATOR = 10 OHM RHEOSTAT This extra cut-out provides automatic charging for radio equipped cars. Connect third gener- ator brush in series with cut-out contacts, across which is shunted a 10-ohm radio rheostat. Remove heavy wire from cut-out and connect fine wire coil to radio pilot light and ground, respectively. 4 This extremely simple mon- itor provides the amateur op- erator withameans for check- ing quality of his transmit- ter’s signals. The coil is ^ wound to satne frequency as transmitter and mounted, along with tuning condenser, crystal detector and fixed condenser in a metal cabinet. August, 1937 The circuit above provides excellent tone modulation for 5-meter trans- mitters. À dynamic speaker transformer is used in the novel circuit which needs no explanation. 5 WATT 2 RESISTOR TUB SE 37 OR 76 TUBE ВА: x -Worn out rectifier tubes in A.C.-D.C. sets need not be replaced when set is used only on D.C, current. Break glass and wire tube base with heavy duty resistor as shown above. 101

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MIGROPHONE ANTENNA PENAS ©] STATOR PLATE i i 1х № SWITCH WOOD BOX 3'x a x 2" DRILL HANDLE FOR CABLE 4 CONDUCTOR BATTERY CABLE 102 "ETHER IMP'— by Bill Bartlett RESENTING the “Ether Imp,” perhaps the tiniest, and certainly one of the most fascinating radio transmitters ever designed. It is so light and compact that it may be car- ried about even more conveniently than the conventional sports mike used by profes- sional radio announcers at outdoor events. The battery supply for the transmitter is small enough to slip into coat or overcoat pocket and a small flexible cord from transmitter to pocket provides battery leads. The 34 meter band is destined to become popular with radio amateurs doing short dis- SLIDING COVER ANTENNA NSULATOR R.F. CHOKE Assemble the J4-meter transmitter components in a 3"x312"x2" plywood box in the manner shown. The tuning condenser, mounted on the side of the box, is homemade and consists of one rotor and one stator plate, each having а 34” radius. The 955 “acorn” tube socket is installed in the back of the box, while the 200-ohm microphone is attached to the front with a small machine screw. Make connections short as possible. Modern Mechanix

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A 3/4-Meter No larger than a sports an- nouncer's hand microphone, this tiny transmitter provides a novel method for transmit- ting on ultra-short waves. tance work. The range of this transmitter is from one-half-mile, under poor conditions, to as much as two or three miles, or even bet- ter, under more conducive weather condi- tions. -This is the ideal outfit for the beginner who wishes to maintain contact with a friend over a short range, or for the amateur who wishes to conduct 34 meter field experiments during the summer. The transmitter is simple enough for even a beginner, with absolutely no experience, to build, since the parts are few and the dia- grams show clearly the situation and connec- tion of each part. The most important point of the construction is to keep all leads as short as possible since at this high frequency long wires in the circuit result in capacities that tend to pull the set out of its proper frequency band. The type 955 "acorn" tube accounts, in a large measure, for the set's tiny propor- tions. This tube, which is about the size of a person's little fingertip, has a glass envelope [Continued on page 130]

N als T в VOLTS "This schematic diagram indicates the utter simplicity of the transmitter's circuit. with No. 18 enameled copper wire as shown in inset. 14” Bakelite dowel. August, 1937 aa, < o E A = 90 VOLTS Да [в в] во з i The choke coil is wound with Мо. 32 The antenna radiators, which mount to the stand-off insulators, each measure 714"x34". Transmitter

This simple wavemeter permits an accurate check of the trans- mitter’s frequency. It consists of a S' long by %’ wide copper strip, mounted on a baseboard with stand-off in- sulators to form, а “U” shape. COPPER STRIP Connect a 0-200 milli- ammeter in series with plate lead, bring wave- meter near transmitter

and slide bar along strips CANTO QE until highest reading is INSULATOR obtained. Measure dis- tance around bow to de- termine the wavelength. MQUNTING OF coll LI

NO. 32 D.C.c. WIRE CLOSE WOUND

BAKELITE ROD The tuning inductance is wound d.c.c. wire on a 103

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NEW IDEAS FOR HANDY MEN HOUSE MOVERS JACK Tee à ADMAN BURIED 4 FEET! | IN GROUND - ABOUT 16-0" LONG-IBPXIB, . Dolly Built From Odds And Ends FREIGHT dolly that will find many practical appli- 2 X cations in the home workshop can easily be built from strap iron, fashioned into a frame similar to the one in the accompanying illustration. bearing casters provide the rolling stock. A sheet iron plate attached to the front of the frame permits easy wand loading of heavy objects.—T. L. Moore. SEN Heavy Duty Jack Drives Water Wells HE drilling of wells, without the use of the usual elaborate well driving equipment, can be accomplished, without diffi- culty, by employing a heavy duty truck or house movers jack and several sturdy bridge timbers. Assemble the bridge timber so as to form the driving rig and bury the lower portion in the ground to a depth of 4 feet. In assembling the rig, make certain that the construction is thoroughly rigid. To accomplish this, fasten all timbers together with large carriage bolts and draw them up tight with a wrench having an ample amount of leverage. When a location has been decided upon, for the well drilling operation, set up the rig by digging a trench 4 feet deep, inserting the 16-foot by 15 by 15-inch deadman in the pit and refilling it with dirt. A hole in the center of the deadman serves as a guide for the pipe. To use the drilling rig, feed a length of pipe through guide hole and force down with jack, adding additional sections of pipe, until water is struck. A pair of ball BALL'BEARING CASE DRIVEN E ONTO SHAFT T 2 SHOVEL MADE FROM HEAVY WASHERS 178” SHEET IRON тиг" 178” STRAP IRON USED THROUGHOUT Ez Y SLENDER ~~ NAILS PROJECT ABOUT 1" THRU THE BACK EDGE OF THE SHEET 19 PUSHED INTO PLACE OVER THE PROJECTING CLEATS Wallboard Installation Simplified VERHEAD wallboard installations can be made a one man operation by using wooden cleats for holding the board in position while it is being nailed in place. Make the cleats l-inch square by 6-inches long, rounding off one end so that when the cleat is fastened to the ceiling, the wallboard can easily be slipped under it.—A. Н. Waychoff. Bed Rails Form ARMERS who are seeking a practical gate closure for pasture land will find this stunt worth while. Bed rails, which are not difficult to obtain, are hung across the fence opening and fitted into the original bed rail fittings so that once in position, it is impossible for live stock to stray. Install the bed rail fittings to each side of the fence opening with spikes, spacing them accordingly.—A. Н. Waychoff. 104 Gate Bars Modern Mechanix

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Kinks Tuar Simpiiry SHor Tasks Drill Press Clamp Aids Glass Cutting HEN cutting glass into intricate shapes, the use of a drill press as a clamp for holding the glass in a firm position during the cutting operation, makes the task a simple one. Fit the drill press chuck with a dowel to which has been attached a small block of wood. The size of the dowel is not important, although one of %-inch diameter is recommended. Fasten the small block of wood to it by drilling a hole in the center and gluing in place. Cut a plywood pattern to the exact shape to which the glass is to be cut and place this over the glass pane in the manner shown. The chuck is then lowered and pressure applied to the drill lever so that the glass can be scored ac- curately with a glass cutter.—K. Murray. Rubber Band Protects Brush Bristles N OBJECTIONABLE feature common with most brushes having long bristles is that they spread paint over too large an area so that it is impossible to use them when painting in corners or other close places. A simple way to overcome BAND this disadvantage is to slip.a wide elastic band over the bristles, Guia adjusting it to the most satisfactory position for the particular SRREADING painting operation in which it wil be employed. The paint brush can be used, instantly, for painting large surfaces by slipping off the elastic.—E. Novak. RUBBER TRUBE Rubber Ball Forms Steel Wool Holder ANY have experienced painful, if not serious, sores from 1¥H small particles of steel wool sticking in the fingers when this material was used for smoothing or polishing metal sur- faces. An excellent holder for steel wool pads can be made by cutting a rubber bouncing ball in half and stuffing it with ЗА the metallic polishing material Опе five-cent ball will make STEEL Woot two holders for taking two different grades of steel wool — __ 4a —Emil Novak. es Wood Screw Makes Handy Countersink LARGE wood screw can be converted into a serviceable countersink that will cut keen screwhead recesses in woodwork in no more time than required to do it with the usual countersink bit. Select a screw, of moderate size, hav- ing a round head and, with a triangular shaped file, file it down at the slot to form a cutting edge. After filing away part of the metal from opposite sides of the screw slot, as shown WOOD SCREW, in the accompanying illustration, heat the screw until it be- А «а comes а dull red, then plunge it into cold water. To prevent FILE SLOT TOTORM 7 the screw threads from damaging the jaws of the drill press CUTTING EDGE chuck, file off all sharp edges.—Kenneth Murray. August, 1937 105

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This looks like a cozy log cabin in the ~ mountains, with the owner's car ready outside the door to take him to town. Actually, this is a “table top" shot. The cabin is a cleverly-made model of lollypop sticks and cardboard, and the. flashy roadster is a rubber toy purchased for a dime in a chain store! This realistic lake scene will fool many people. The plane really flies, but it is only about a foot long! The placid "Jake" is a mirror; the shore is beach sand; the "trees" are tiny twigs from window plants. An excellent example of ingenuity and good photography made with an ordinary hand camera. S ALMOST every motion picture goer knows, the Holly- wood studios are continually fooling us these days with scenes photographed in miniature, such as a village street, rural winter snow scene, a ship at sea, an airplane wreck and what not else. So cleverly are these miniature "sets" designed and photo- graphed that in the picture their lack of re- ality defies detection, and when we are let in on the secret, we do not mind at all. In- deed, we admire the achievement. Have you ever tried creating miniature Scenes yourself and photo- graphing them with your own camera? Itsfun. Depending upon your skill, artistic ability and the materials you employ, you may construct and photo- graph miniature sets in your own home that will rival the semblance of reality achieved in Hollywood; or, if you pre- fer, you may create scenes of fantasy, comedy or burlesque to compare with a “shot” in an animated cartoon. For a "still" camera, this is really nothing else than table-top photography, such Modern Mechanix

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CAMERA STUNTS These elephants must have heard of the ‘song “Kitten on the Keys" and decided they'd try a tune themselves. А simple but effec- tive home-camera stunt, made by the light of a single flood lamp in а reflector. as has long been practiced by amateurs, but which now is photographically much easier for the amateur than it used to be, because of the recent introduc- tion for home use of more powerful artificial lighting. For table- top photography you can very cheaply, with two or three of these brighter home flood light bulbs, rival the lighting equipment of Hollywood studios, and, what is more, do good work with an inexpensive fixed- focus camera, provided you use a portrait attachment to secure the necessary close-up focus. Constructing one of these sets requires, of course, a certain amount of time and patience, with the expense depending upon the ma- An amateur photographer-entomolo- ec gist raided his specimen jars for the “props” for this weird scene, which represents a '"'Grasshopper Night teriels you put into it. Very amusing Club Note the “fan daneri e : orming for amusement of assemble scenes may be created, however, with- guests. Specimens are held temporarily [Continued on page 142] in place by specks of rubber cement. August, 1937 107

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oR WIRE TO BE CLIPPED ON CAMERA Fastened to the top of the camera, these handy exposure data cards in- sure successful shots” by Everett Rudloff ESPITE new and clever cameras of all shapes, sizes and prices, there are thou- sands of camera addicts who have used the time-tried Graflex with great success. With some frequency, however, they would like to make it still more useful. Many photogra- phers build their camera equipment around a Graflex, adding other machines for special work. from time to time, but falling back on the “old reliable” for their important shots. 108 A small toggle switch mounted on the side of the Graflex permits tight hand to trip "photoflash" and left hand to snap shutter. The “photoflash” holder is made from flashlight case as described above. This metal indicator permits distances to be inscribed on focusing knob for instant adjustment, eliminating use of camera's focusing screen. PHOTOFLASH REFLECTOR WIRING It is this kind of work which has inspired some of the “Graflex gadgets" described here. First in importance, because it may save the cost of the camera, is a neck strap. Neck straps are not new, except on a Graflex. Miniature cameras come equipped with the straps so that the camera may be carried at chest level all the time. While no one would choose to carry a heavy camera in that posi- tion constantly, there are occasions in news and commercial work when it is helpful to be able to let go of the camera and have your hands free. To make this strap, secure from the five and ten-cent store one web strap three feet long, two swivel snap hooks, such as are used for dog chains; two brass reinforcing strips, one inch long, and two half-inch screws. Run the plain end of the strap through the buckle and rivet it over one of the hooks. Find the Modern Mechanix

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mid-point of the camera case and fasten one brass strip on each side, with one screw, so that the other hole in the strip projects above the camera box, then ream the other holes to take the strap hooks. To use the strap, open the camera to work- ing position, snap the left hook, bring the strap around the neck and snap the right hook in position. Now, adjust the strap length with the buckle so that when using the camera in normal position the hands take the weight as usual, the neck strap being allowed just a little slack. When not in use, the strap is carried in the pocket and the two August, 1937 A neck strap, such as this one, permits more freedom of the hands when using the Grallex for news and commercial work. The strap, a 10с web type, is fitted with swivel snap hooks for fastening to camera box connectors. brass strips swung down along the body of the camera. A focusing scale is a real neces- sity, yet few popular Graflex models have one. The ground Elass is ideal for most pictures, but there are times when the light is bad, the lens is stopped way down or a night picture with photoflash is necessary and it is impossible to see the image in the hood. An accurate focusing scale is provided by making a metal pointer for the regular focus- ing knob and screwing it to the camera at a 45 degree angle with the bottom and front of the box so that the pointer just clears the knob. The camera is then taken outdoors and a target set up on a support. With a lens of 644 inches focal length the following distances were measured off: 4, 5, 6, 7, B, 12, 15, 20, 30, 45, 60, 85 feet and infinity. With the lens over the 4-foot mark and 109

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This dark cardboard lens shade, installed on Graflex camera, tends to ward off ob- jectionable light, assuring better pictures. LENS SHADE ADAPTER FILTER SLIDE HGLDER s GELATINE FILTER * PATTERNS FOR t LENS SHADE & \ FILTER HOLDER cem Lp t sal a i i i i D ' ER | мафии оч широта шв ные se 1 ч e у 2 Hi DIRECTIONS AND GLUE eno FILTER HOLDER CARDBOARD FILTER HOLDER FILTER HOLDER (2 REQUIRED) CARDBOARD A lens shade, for preventing extraneous light from striking the Graflex lens, can be made from cardboard, cut according to the above template and as- sembled with “scotch” tape. The rear of the shade is fitted with a holder into which can be inserted colored gelatine slides when unusual effects are desired. wide open, turn the focusing knob clockwise until the target is needle-sharp on the ground glass. Now, with the knob in that position, make a scratch mark on the knob opposite the pointer and label it "4" Do the same with the camera five feet from the target and so on. Always make the scratch mark when the knob is turned in a clockwise direction with a slight tension being exerted against the focusing mechanism. This will take care of the backlash present in most of these cameras and will insure that when the camera is later focused to a predetermined setting and the reading taken while the clockwise pressure is being exerted on the knob, the setting will be accurate. With the series B 110 Graflex and a 6%-inch lens, the range from four feet to infinity is covered in slightly less than one complete revolution of the focusing knob. On the top of the camera, next to the han- dle, are two places ideal for exposure data, typed on cards and protected by celluloid en- velopes. At the top of each card are the shutter settings for the most common speeds, which saves turning the camera end for end to find the regular shutter speed table on the front of the hood. On the left hand table, at the bottom, are the speeds necessary to stop motion at various distances. The left figures are miles-per-hour, the middle [Continued on page 128] Modern Mechanix

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PHOTO DEVELOPING AGITATOR insures proper development of both negatives and Secure an old electric fan, remove two of the blades and mount it to a 12” by 12” plywood panel, as shown below. the assembly on an elevated mounting so fan blades are free to revolve. by fastening rubber tubing guide around top panel. prints. tank, then place on To each corner attach a sponge rubber ball and then mount Complete the agitator Insert the film in a daylight developing the vibrating panel, so as to receive proper and thorough agitation. FILM PROJEC. TION GUIDE pre- vents 16 mm film from jumping off the sprockets of the framing mechanism. The guide is formed from a [еле of scrap film looped over the sprockets. as indicated at right, and cemented to- gether at the ends. he movie film is threaded through the Projector sprockets in the usual manner. MAKING POSITIVE FILMS FOR PROJECTION slide lanterns is a kink well worth knowing. ere made from the ordinary negative film in the same manner Cut up a roll of unexposed films, in the as a positive print. darkroom, to the size to be made. August, 1937 Place the emulsion side of both films together and expose in printing frame for 1/10 second. А 10-watt lamp is recommended for obtaining most satisfactory results. BOTTOM— = 2 BLADES Я ONLY LEFT f AGITATOR. IN MOTOR FAN FOR ALL OPENING 'CUT IN 2-' 12^ SQUARE PLYBOARDS BOTTOM BOARD = 3 SPONGE BALLS SEREWED BETWEEN WOOD STRIPS PLACED UNDER CEMENT BLANK iL M FEEDER REEL TAKE-UP REEL —P EILM PROJECTION AID in Positive films of the negatives from which prints are DARK-ROOM LIGHT. WALL: COFFEE CAN f AN INEXPENSIVE DARKROOM SAFELIGHT can be made from a 1-pound coffee can and а 10-cent porcelain cleat socket. Cut a slot in the side of the can and a circular hole in the lid as depícted in the illustration at left. Mount the cleat socket to the center of the can so that a pair of wood screws serve the dual pur- pose of holding both socket and light housing to the wall. To use, paste safe paper over opening in can and insert a 7- or 10-watt lamp in socket. SOCKET CUT SLOT IN SIDE OF CAN 111

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ALL-PURPOSE CAMERA STAND by Ralph T. Moore OR those who use the larger size cam- eras, an ordinary tripod is many times inadequate and an unstable suoport. This is especially so when a quick shot is neces- sary indoors. Here is a simply designed, sturdy and quickly adjustable stand that most photog- raphers will find to be an answer to cam- era mounting problems. Many similar de- signs may be purchased, but by following this construction costly fittings are elimi- nated and only materials universally avail- able are employed in the construction. Make the wooden parts first, beginning with the stem. This is a triangular shaped box, made from hard stock. Ash and spruce are satisfactory woods to use, but ma- hogany makes a more beautiful job if such is preferred. Three side pieces, each 3 by 1 by 24 inches long, are required. Plane or saw the pieces at 30 degrees on both edges to form alternate laps at the corners as shown. Using hot glue and finishing [Continued om page 138] 112 6"X9"X!' ADJUSTABLE TOP HINGED TO BASE 3"LENGTH OF THREADED f Ў DRILL BOLT f ii HOLE I1" FROM | TOP OF LEG \ ! Ip IVA"X9"X i | J I^8"HARD S RUBBER STRIPS TENSION SCREW —= X 6"Xel/2"XI" BASE PIPE FLANGE FLANGE LOCKING SCREW PIPE TOFIT FLANGE 3172" X24" X2" TRIANGULAR BOX SLOTTED LEGS 28"X2 х4" ^. i | FOR ADJUSTING TRIANGULAR i ) CLAMP AND WING NUTS Y ING NUT AND EG CLAMP )"- FOOT DOWELS RUBBER IB CRUTCH TIPS — aa The photographic illus- teations, at top, show assembly of the leg hinges and the manner in which adjustable leg dowels are installed. Details of the stand are given in perspective form to simplify con- struction. At left is shown the completed tilting top of the tripod. Modern Mechanix

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Short-Cuts For The Amateur Photographer Homemade Floodlight Built For 30c LARGE tin or aluminum mixing bowl, two window- shade roller hooks, a 3-foot length of 34-inch gas pipe and an iron base, salvaged from an old display stand, provide the major materials for building this handy floodlight reflector and stand. Cut a hole in the bottom of the mixing bowl to allow for the insertion of an ex- tension light socket. Fit a tee coupling to one end of the Eas pipe, mounting the opposite end to the cast-iron base. The mixing bowl reflector is attached to the lamp standard by mounting the curtain roller hooks to the bowl with machine bolts. Space the hooks so that they : IRON BASE can be slipped over the tee fitting and a long bolt passed through to secure the reflector.—K. F. Keith. 3gX4d° CUT FILM HANGERS Е. Midget Tank Develops Cut Films Fo the amateur photographer who rarely develops more than three or four cut-film negatives at one time, this tiny tank permits 314 by 44-inch cut film to be developed in the smallest possible space. Make the tank, 514 by 514 by 434-inches in size, from sheet brass, м soldering all seams securely so that they are leakproof, заход кат. : then have a local garage nickel-plate it thoroughly — £D BO: E : (= SX. A. Dolid. Lamp Socket Shell Serves As Lens Adapter A SIMPLE adapter which permits the use of supplementary lenses and filters, smaller than those designed for a camera fitted with 144-inch lens, can be assembled, in emergency, from the lower portion of a brass light-socket shell. Cut off the threaded stud and enlarge the hole to permit insertion of the smaller lens or filter mounting. Complete the adapter by painting the inside a dull black.—R. Pinault. | RUBBER SUCTION CUP Е Suction Cup Forms Lens Shade ‚ LENS shade that will also serve as a holder for light filters is a useful camera accessory that will find many practical applications. The use of a lens shade will result in better pictures, since only the light rays reflected from the object being photographed find their way through the lens. To make this unique shade, pur- chase a rubber sink drain plunger and cut off the end stud so that it can be forced over the lens of the camera. The expansion on the plunger, where it fits over the: camera lens, will close the mouth of the suction cup to a sufficient degree so as to eliminate the possibility of stray light striking the lens. Small light filters, cut from colored glass, can be slipped into the lens shade when special effects are desired —H. W. Stowell. August, 1937 113

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LET i METAL i BACK IN — ^ FLUSH- FASTEN ~ WITH SMALL NAILS 7 FRAME L DIRE SIDE AND TOP , zz im 2

| REFLECTOR pr SPOOL PIN AND HOLE FOR FITTING A EI FLANGE CASE TOGETHER 36"X 5/1 TUBE — CUT OFF AND RIVET WOOD FRAME IS ON \ ТОР, ВОТТОМ АМО SIDES ONLY. <——~_ METAL RE- FLECTING HANDLE LY BACK < SLIDING BRACKET 1 METAL | REFLECTORS i] SOCKETS E I

12 1/4"

BULNOSE ALL CORNERS”

Folding into a compact case, no larger than that of a pottable typewriter, this double unit reflector provides the amateut with a very useful accessory. The case is formed from 3% inch plywood and lined with aluminum reflecting surfaces. Two No. 2 photoflood lamps are contained in each half of the case. Music stands, from which the racks have been removed and flanges substituted, make excellent tripods for reflector cases. 114

R. G. Lissaman NCORPORATING features of unusual con- venience to the amateur photographer this portable floodlight case can be carried around with considerable ease. In size, it is no larger than the average portable typewriter and weighs much less. Each half of the case serves as an inde- pendent reflector fitted with two porcelain cleat type sockets into which are inserted No. 2 size photoflood lamps. While the smaller photoflood bulb can be used, the larger type is recommended due to the smoother distribu- tion of light on the subjects to be photo- graphed. Barring accidents, the reflectors will provide satisfactory service for many years. Only an occasional replacement of a photoflood bulb will be required and by using a series parallel switch in conjunction with the lamps their life can be extended consid- erably. In making the floodlight case any available wood can be used, although a good grade of 3g-inch plywood as advised if an exception- ally neat job is desired. Four pieces of ply- wood, measuring 415 by 11% inches and four measuring 4% by 1234 inches, are assembled to form the sides of the case. Two panels, each measuring 1134 by 13 inches, form the sides. Before gluing and nailing the case to- gether, run a shallow rabbet along one edge [Continued on page 132]

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nun We ЙА ЛА malt Т ^us С RLEY; DAY мо on є S вох МОА clint: Dert iate eae otot e? i stage ium b iw Павии clo’ sed te счет pail ame ae vats padres? — p ge is A 16/19 ye and SP. 0Y age Whe п Ansu vering A dverti isemei nts Please Ment ion A ugust M doder: n Mech hanis 115

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. AMATEUR PHOTO PUZZLERS In this department the Photography Editor will answer any question or problem relating to cameras of all types, enlarging, printing, developing, taking pictures, and the various phases of home movie making. When sending questions to this department, be sure to include a stamped, addressed envelope, so that we can answer directly in case space does not permit publication of the question on this page. Send all inquiries to the Photography Editor, Modern Mechanix, 1501 Broadway, New York, N. Y. CAUSE FOR SPOTS ON NEGATIVES I am just starting to do my own developing and printing. I get clear pictures, but am troubled with tiny spots on the negatives which show up badly on the enlargements. Can you tell me where to look for the cause of this trouble?—J. B. Kane, Bayside, L. I. First make sure that the inside of your camera is spot- lessly clean and free of dust. Wipe it out occasionally with a fine brush. The trouble is more likely to be with the developing and fixing solutions. Most beginners do not seem to appreciate the importance of filtering these solutions thoroughly each time BEFORE they are used, especially if the negatives are small and enlargements are to be made. A surprising amount of fine sediment will be found in the filter paper or cotton after apparently clean developer or hypo is filtered through it. Also make certain that the wash water is clean. communities the water is full of slight impurities that stick to the soft emul- sion of the negative or print. An in- expensive filter that attaches directly to the faucet will help eliminate this pos- sible cause of the “spot” trouble. In many DIFFICULTIES EXPERIENCED WITH HOME-BUILT ENLARGER Although I constructed the "Kitchen Utensil Enlarger," which was described in the May, 1936, issue of MM, accord- ing to instructions, I have been unable -to secure clear enlargements with it. I have tried a 60, 100 and, 150 watt bulb in the device, but still enlargements are not clear. Can you suggest a possible cause for my disappointing results?— Gene Renk, Chicago, 111. There are several factors which, if not properly attended to, can lead to unsatisfactory resulis with the MM photo enlarger. First, it is of especial importance that the lens be in sharp focus before any enlargements are made; with the lens out of focus a clear enlargement is impossible. Before any enlargements are made the lens should be adjusted carefully so as to project a clear image of the negative. Ex- posure is also very important, and this can only be determined by experiment. If the enlargements are too light, a longer exposure will be required. If too dark, shorten the length of ex- posure. Keep in mind that the brighter the light used to project the negative, the shorter the length of the exposute. The use of a '"Photoflood" bulb in the “Kitchen Utensil Enlarger,’ and а short exposure, will produce very clear enlargements. use of filters. MAKING GLOSSY PRINTS In drying prints on ferrotype tins to get a glossy finish, I find that many of my pictures are spoiled because the surface is broken up by irregular areas 116 MONTH'S BEST PHOTOS Beautiful moonlight effects. like the one pictured at top, can sometimes be obtained in broad daylight without the This snapshot, which won for Eugene Miller of Ft. Worth, Texas, MM's $5 photo award, was taken directly against the sun and the print allowed to over-develop until the desired contrast was obtained. month's second award of $3 was re- ceived by William McAleer of Wood- side, Long Island, N. Y., for his inter- esting composition photograph, which was snapped through a stone archway. М. Y. that have not taken the "shine? properly. Тһе fertotype plates are clean and new.—C. P., Portchester, N. Y. This "egg shell" effect on glossy prints is à common one. It is due merely to improper contact between the prints and the ferrotype plates. After placing the wet prints on the tins, cover them with a piece of lintless blotting paper or an old linen towel and run over them heavily with a rubber roller. This will squeeze the paper into thorough contact with the surface of the ferrotype plate and prevent the formation of air pockets. Incidentally, the blotting paper or towel will absorb much of the water on the top of the prints and the latter will there- fore dry more quickly. ADVISABILITY OF SHORT STOP BATH Is it advisable to rinse negatives and prints after removing them from the developer and before putting them into the hypo?-—E. Bachner, Richmond Hill, N. Y. Yes, this is highly advisable. Use ordinary water for negatives, letting them wash for about two minutes. For prints, use a "short stop" bath con- sisting of 1L2 ounces of acetic acid mixed with cold water to make 32 ounces. Swish the prints through this wash for about fifteen seconds and then transfer them to the hypo. This bath can be saved and used several times. Throw it away when the prints that are put in it continue to darken instead of stopping their development instantly. The value of both the water and acetic acid baths is that they lengthen the life of the hypo and also prevent the likelihood of gas bubbles forming on the negatives or printings. These show up later as *black or white pinholes which cannot be removed. DEVELOPING HOME MOVIE FILMS I own an 8 mm amateur motion pic- ture camera and plan to process the film myself. Can you furnish me with the necessary instructions for doing this? —T. M. Benson, Marion, Ohio. Processing home motion picture films involves delicate chemical operations which should not be attempted by the novice. Realizing that even the experi- enced photographer did not possess the necessary equipment for reversing home movie film, the manufacturers included the cost of reversing along with the pur- chase price of the film. After the amateur has exposed the roll of film he merely has to mail it back to the factory where it is developed and returned to him ready for projection, This The photography editor will Фау $5.00 or $3.00 each for photographs interest. ing enough for publication on this page. All pictures should be mailed to Modern Mechanix, 1501 Broadway, New York,

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ODAK VOLLENDA in hand, you’re ready for every picture that comes along—off-guard snaps, light- ning-fast sport shots, landscapes, close-ups, rainy-day pictures, indoor snapshots under Photofloods... Brilliant/.3.5anastigmat lens; 1/500- second Compur-Rapid shutter. Nega- tives are sharp, capable of extreme en- largement—especially when Kodak Panatomic Film is used. See Kodak Vollenda at your dealer’s. Weigh range and refinements against price, $44.50—you’ll say it’s the buy among ''miniatures" . . . Eastman Kodak Company, Rochester, N. Y. ou get sharp ONLY EASTMAN MAKES THE KODAK to dusk; in LENS · • ° 3.5. Y anastigmat f-t awn DEPTH-OF~FOCUS SCALE (A) Rotating outer ring shows sharp-focus range for any stop-and- distance combination. FINDER (В). . » Direct- view, eye-level type; folds flat when not in use. a s up nine spes full ‘or quick, infinity- IT... N зу feet (0 M Е en from L REV or ING on у» YOU СЕТ 16 PICTURES ОМ АМ 8-EXPOSURE ROLL Kodak Vollenda gives you 16 pictures, each 1 3/16 x 19/16 inches, on a roll of Kodak Film No. 127: Verichrome, 25¢; “ss” or Panatomic, 304. Your negatives are critically sharp, and ca- pable of extreme enlarge- ment — especially when Kodak Panatomic Film has been used. ACTION FRONT Actuated by push but- ton, automatically opens camera, extends bellows, erects lens, and locks front firmly in correct picture- making position. When Answering Advertisements Please Mention August Modern Mechanix 117

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Inventions—Electrochemistry [Continued from page 61] and other goods are annually destroyed in the cities on account of rain. “We should systematically investigate the ap- plication of electric currents in the stimulation of the growth of living cells and the formation of many organic compounds. The production of fruits, vegetables and other food materials in a few localities and then shipping them half way around the globe appears to us an awful economic waste and extravagance. With the aid of elec- tricity, truck farms located in the outskirts of cities, or on the roofs of skyscrapers, will pro- duce any, or all, fruits and vegetables. Why not? “One other important problem is a means to convert ores into finished metal products easily and efficiently. Metals occur in nature com- bined with other elements, notably sulphur. The old process that dates back at least 5,000 years consists in roasting the sulphur compounds, thereby producing oxides; and then mixing these oxides with coke or charcoal and heating to high temperatures to reduce the oxides to metal— usually very impure at that. Electrically, it will be commercially possible some day to produce pure metals free from sulphur, phosphorus and other deleterious or objectionable impurities.” Dr. Fink is, himself, working on two important developments at the present time. He is experi- menting on a way to convert the sun’s rays into electric power and he is trying to find a satis- factory method of extracting gold from the seas. In explaining his “power from the sun” theory, he told me that mankind was rapidly approaching the need for additional power resources. “There is not enough water power on earth to supply more than 10 per cent of our energy de- mands,” he said, “and since coal, oil and gas necessarily produce most of the remaining 90 per cent, a substitute must be found. I believe: this can be accomplished through the use of photo-electric generator cells and I predict that the day will come when these cells will be placed, for example, on the roofs of large apartment buildings and will be used to operate electric refrigerators, flat irons, toasters, vacuum cleaners and other appliances. Still greater uses will of course eventuate.” Dr. Fink’s new photo-electric generator cell produces about 25 per cent more current than devices formerly used and also is more sensitive tolight. The current obtained is still far too small to be practical for commercial power generation but he expects a vast improvement will be made in the near future. Pointing out that this cell is not the “electric eye” of the motion picture and television, he said it was composed of a sheet of metal in a salt solution or in contact with a salt which, like silver bromide, is sensitive to the sun’s rays. Opposite to this sheet of metal, but kept in the dark, is a second sheet of metal. While the sun shines on 118 the first an electric current flows from one sheet of metal to the other. “It has been known for a long time,” he ex- plained, “that some chemical compounds are changed in composition upon exposure to the sun. Now certain of these compounds change in one direction only. Thus white silver bromide is converted to a black product when exposed to the sun, as all amateur photographers know. An- other well known case, especially for the Sunday hiker, is the way green pop bottles will be found to have changed to a lavender shade after having been discarded and left to lie on the ground ex- posed to the sun’s rays. “The chemical salts or compounds we are par- ticularly interested in at the present are those that will change to a new compound in the light but will change back to the original when placed in the dark.” The “gold from the sea” problem is one that has baffled scientists for many years. One of the main difficulties in this field has been the fact that the gold particles, or ions, that carry a positive charge of electricity, are unable to get close enough to be deposited on the negative electrode, or cathode, because the alkaline film surrounding the cathode is too thick. This alkaline film is brought about by the decomposition of sodium chloride (ordinary table salt) at the cathode, the sodium ions being converted to sodium hydroxide (lye). | Dr. Fink has succeeded in overcoming this film obstacle by rotating the cathode at high speed, an action that reduces the thickness of the alka- line film. | Не uses а copper disk for his cathode, which is electrically propelled and spins around at a ter- rific speed. | It is interesting to know that his original ар- paratus was the familiar malted milk stirrer. He took off the little nut at the end of the rod and replaced it with a copper disk the size of a half dollar, But the speed of the malted milk machine was not high enough and he substituted his present apparatus which, while considerably larger and heavier, looks not unlike its smaller counterpart in any drugstore! In a typical experiment, Dr. Fink employed a disk of 5-centimeter diameter, spinning at the rate of 8,500 revolutions per minute. The disk was set in three liters of a 3 per cent salt solution containing three miligrams of gold. At the end of a half hour, more than 90 per cent of the gold was plated out on the disk. Dr. Fink pointed out, however, that hope of recovering billions from the seas must be dis- pelled for the present because the cost of the electricity to operate the cathode is about five times the value of the gold recovered. He added that at the same time this procedure was more profitable in the case of radioactive metals. The metal polonium, for example, can readily and profitably be recovered from waste solutions.

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Inspections, which no human skill can equal, guard the quality of Ford quality must be main- tained. This is a law at Ford plants—a law guarded by expert workmen and highly scientific inspection machines during every phase of the manufac- turing of Genuine Ford Parts. One machine, for example, checks piston pins for smooth- ness, hardness, straightness, roundness and diameter at the rate of 1500 per hour. Át one stage in the inspection an auto- matic scleroscope checks the pin for hardness, À small ham- mer is allowed to fall upon the pin. The rebound of the ham- mer measures, to a fine degree, the hardness of the metal. If the metal is of the correct hard- ness, the hammer rebounds to intercept a light beam from a photo-eleeitrie cell which ашо» matically allows the pin to pro- ceed for further inspections. Another inspection machine gages camshafts at 25 points at FORD MOTOR COMPANY * DEARBORN * MICHIGAN When Answering Advertisements Please Mention August Modern Mechanix the rate of 500 camshafts per hour. And valve stems are checked for roundness by means of optical and mechanical gages that keep the limit of variation within two ten-thousandths of an inch. Because of such accurate and scientific inspections, because of Ford quality materials and Ford precision manufacturing, you can be sure of getting the best parts for your Ford by buy- ing them from your Ford dealer or any garage that displays the sign “Genuine Ford Parts.” Genuine Ford Cut-outs have large coin- silver contact points, Layers of the shunt-coil windings are insulated individ- ually. Series coil winds ing has full generator output carrying capacity. GENUINE FORD PARTS This automatic valve lifter inspece tion machine performs eleven dife ferent inspections оп 35 valve lifts -ers per minute—a total of 385 inspections. à All Genuine Ford Piston Pins are ine spected for smoothness, hard. ness, straightness, roundness and di- ameter, Diameters are held within a vari- ation of one ten-thou- sandth of an inch of speci- fied sizes. Clutch Disc Assembly, Alt discs are cares fully inspected to make cer- tain that all parts measure up to specified requirements. 119

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So You're Buying A House! [Continued from page 10] and rear walls and the attic. In some types of brick houses there is no room for wall insulation, as the firring strips (to which the plaster lath is nailed) is attached directly to the inner layer of brick, with less than an inch of air space between. Tn any case, attic or roof insulation is a necessity, because the usual plaster and lath ceiling is a sieve as far as the rising warm air currents from the radiators are concerned. An average attic insulation job costs about $75 if you do it yourself, $100 if the "blowers" do it. The walls cost in proportion. If you contract with the builder to do the work, he adds its cost to that of the house, and you pay it off conveniently over the life of the mortgage. The additional cost per month is small, as even complete insulation for an average house costs only about $500. If you have the insulation done after the mortgage on the house is taken out, you will have to go through the same amount of red tape for the second loan. Of course, you can get along with- out insulation, but when the first cold snap comes along and you start buying oil, you'll be sorry you overlooked this protection. Most small houses are furnished with gas ranges, but not even the largest come with refrig- erators. Check off another $100 here, and that will buy only a small box. People accustomed to renting apartments and houses take the electric ice-box for granted, and they look somewhat dumbfounded when the builder says: "The refrigerator? That’s up to you.” Window coverings are still another little joker. You simply must have screens, otherwise mos- quitoes and other insects will make life miserable during the summer in most parts of the United States. To close a difficult sale a builder some- times throws in the screens as an inducement, but in nine cases out of ten they are not included. The same applies to. storm windows. These аге not quite as necessary in winter as screens are in summer, but in exposed locations their use is imperative. Without them, “cold zones” develop around the windows, even with good insulation in the walls, and a lot of valuable heat is wasted in warming up the window panes instead of rais- ing the temperature of the rest of the room. Storm windows should be fitted with the same kind of hooks as the screens, to make for easy inter- changeability. Figure about $2.50 average per window for Screens and a little more for storm sash and you'll know why the builder doesn't say anything about these items in his prospectus. Venetian blinds are all the rage now. Appre- ciating their attractiveness and sales appeal, many builders put them on the front windows of a house, but not on the back. Of course, your wife will want to complete the effect, and that means about $5.00 per window. They really are worth it, because they give full privacy without cutting [Continued on page 135] 120 Records Prove Zeppelins Safe [Continued from page 41] an even chance of getting away. Proof of this was given a few years ago, when the Los Angeles sighted the aircraft carrier Lexington during fleet maneuvers, and observed it for an hour and 55 minutes before being discovered, although the Lexington had several planes in the air. The reason for this is apparent to anyone who has ever done any flying. It is quite simple to sweep the horizon with a strong glass, spot any ship on the surface within the limits of visibility. It is quite something else again for the lookout on a ship to watch the immense dome of the entire sky effectively. In practice, it would be quite pos- sible for an airship to discover the approach of a hostile fleet in mid-ocean from a distance of 40 miles, radio its position and size, and escape without the enemy being aware he had been ob- served. а Inflated with non-inflammable helium, the аіг- ship is by no means as vulnerable a target as is popularly supposed. Those who think a few ma- chine gun holes in the bag will doom the ship do not realize that there is little pressure on top of the bag, none at all on the sides and bot- tom. There were four valves 32 inches in diameter on each of the Macon's twelve gas cells, yet with all valves fully open, it took several minutes to effect an appreciable change in buoyancy. Hundreds of machine gun bullets would do very little damage to such an airship. In the meantime, machine gun- ners aboard the dirigible, and the five planes it carries, could do quite a creditable job of defend- ing itself. Bombing and shell fire are something else again. A plane could easily destroy an airship by drop- ping bombs on it. The airship has no business coming within effective range of shell fire. Although the Navy, especially the younger of- ficers, still want additional airships, no definite steps аге being taken (that they will admit) to procure them now. The policy seems to be that, with the recent Jarge appropriations for bringing the fleet up to treaty strength, it would not be wise to ask for additional appropriations for airship construction, with the Hindenburg tragedy so fresh in the minds of congressmen. They are, however, laying definite plans to go ahead with the develop- ment of airships when the time seems more pro- pitious. The Secretary of the Navy says: "The Hindenburg tragedy will not effect the Navy's decision, because it resulted from a hydro- gen fire, and American. ships use, instead of the highly inflammable hydrogen, an inert gas, heli- um, which while it has less lifting power than hydrogen, does not either burn or explode.” So the immediate future of the airship is still in the hands of the Germans. For the next sky queen, we must await the arrival of the helium- filled LZ-130.

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. VerveT TOBACCO tastes better and better the more you smoke it. This fine Burley tobacco is mellowed two years in wood...that makes it milder. And it's smoking tobacco with that pure maple sugar flavor for extra taste and aroma. Copyright 1937 Liccett & Myers Товлссо Co. When Answering Advertisements Please Mention August Modern Mechanix 121

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Restocking The Ocean [Continued from page 65] on its spawning grounds. The Bureau of Fisheries feels that there will yet be a good many fish caught in the New England fishing grounds. This unprecedented amount of eggs, with the exception of the mackerel, was planted by only two stations, the one at Gloucester producing the majority of cod and all of the pollock, while Boothbay Harbor distributed most of the flounder and has a slight edge on the haddock output. The Federal laboratory at Woods Hole, Mass., handled the mackerel eggs and young fish. One other valuable sea-food, the shad, is draw- ing the attention of the Bureau for the first time. At Fort Belvoir, Virginia, the Federal hatchery obtained almost fifty million eggs, hatched them and released the resultant fry in suitable waters, mostly in Virginia and North Carolina. In this business of planting eggs and hatching fish, man’s method has an advantage over nature’s. For this reason: There are countless fish in the sea that devour eggs and young of other fish, and in many cases, even their own. Fertilized eggs laid on the spawning grounds by any fish are open and defenseless against any marauder who wishes to make a meal out of them. Thus untold millions of them perish. In fact, scientists claim that the percentage of cod fish eggs that reach maturity can be reckoned in fractions of one percent! The eggs hatched and raised by the Bureau of Fisheries are taken from fish already caught (the process is known as “stripping”) which, in that case, never would be deposited in the ocean, for the fish are in the holds of commercial vessels, on their way to market. Shielded from their nat- ural enemies, the mortality of these eggs is almost nil, and especially if allowed to hatch, the chances of survival are far higher than if the parent fish were not caught and had laid the eggs in the ocean. In fact, Bureau scientists point out that this work really comes under the head of salvag- ing, due to the fact that without their interven- tion, none of the eggs would ever hatch into young fish, -* Naturally, re-stocking the Great Lakes presents an easier problem. Once the fish are there, they can’t get out. The cisco (also known as lake her- ring), possibly considered the greatest delicacy that ever came out of the Great Lakes, once espe- cially plentiful in Lake Erie, is not only nearing extinction, it is practically wiped out, as far as commercial fishing is concerned. And so the Bureau is trying to bring the cisco back again. With great and painstaking effort, specialists at the Bureau hatchery at Cape Vincent, New York, succeeded in collecting a bare 2,640,000 eggs which they have planted in Lake Erie and others of the Great Lakes. Two million and a half fish may seem a fairly large number, but it is only the beginning compared to what is needed to bring the cisco catch anywhere near up to what it was two decades ago. 122 Is There A Speed Limit? [Continued from page 39] high acceleration have been made by Jimmy Doo- little, well-known speed pilot. He determined the acceleration speeds for such maneuvers as single and multiple barrel rolls, power spirals, tail spins, loops, Immelman turns, and power dives. He also found that the accelerations of an airplane flying through moderately rough air do not exceed 2.5 gravity. The maximum acceleration a pilot can stand depends upon the length of time he endures it. No ill effects are suffered under an instantaneous 78 gravity acceleration; but, if the pilot is sub- jected to an acceleration of only 4.5 gravity for a matter of several seconds, he loses possession of his faculties. The effects of 4.5 gravity acceleration are not dangerous to-health unless the acceleration con- tinues for ten or twelve seconds. Beyond that, death is practically certain. The above are the acceleration limits possible to man, no matter whether he is traveling on a straight or a curved line. This seems to explode the notion that men will be able to fly in rocket ships at a takeoff velocity greatly exceeding that of catapulted airplanes. Man-carrying rockets, if they are to be success- ful, must build up their speeds gradually. Rockets do not, of course, reach maximum speed im- mediately, but their launching speed and speed of acceleration are doubtless greater than man can endure with safety. The experimental flight of the mail-carrying rocket, “Gloria,” across the New York State line at Greenwood Lake, did not demonstrate any re- markable speed, although the theoretical speed of the rocket employed was estimated at 500 miles per hour. Dr. R. H. Goddard’s torpedo rocket in New Mexico has attained a velocity of 700 miles per hour, the highest speed ever attained by a man-made power device traveling in free space. Seven hundred miles an hour, it may be noted, is 125 miles an hour beyond the critical speed of the modern type of airplane. Nevertheless, that is a low speed for a rocket. Rocket design is far different from airplane design, and their max- imum velocities are, likewise, wide apart. Rocket speeds really begin where airplane speeds end. The burble, a serious annoyance in airplane speeds, does not affect the rocket to such an ex- tent. Rockets must, of course, travel through low altitudes also, but they never reach their max- imum efficiency until they strike the rarefied zones of the stratosphere and the ionosphere. But there is a speed limit foreverything. Rockets will never exceed the speed of light, 186,000 miles per second, but at some future date they are ex- pected to escape the earth’s gravitational clutch with a built-up speed of seven miles per second, or 25,200 miles per hour.

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Racing The Homing Pigeon [Continued from page 55] convoying the Pittsburgh birds, I carefully ob- serve weather conditions and winds at home, especially early in the morning. Upon arrival at the race point, I compare weather and winds. А. detailed check up on weather conditions for a few days previous to a liberation. gives me an idea on what sort of wind and weather conditions I can expect. “When the crates or shipping baskets are first taken out of the car, they are stacked five high and no two crates from any one club are placed together. They are so arranged that each and every club will have its birds in various stacks. As the crates are piled in the form of steps, each crate as it is opened will rest upon the top of the erate beneath it. I arrange all the doors for liberation and the men are lined up at the doors of the crates so as to get the birds out as soon as possible upon the liberation signal. “The birds, upon gaining altitude, fly in about eight to ten different flocks. They wing around for various lengths of time and before long are lost to sight. On the first race the birds wing around a lot, but following races find them doing better. They seem to pick out the various winds. I like to leave them up early as that gives them a chance to get home in good shape before the different winds blow them all around. The liberation is a wonderful sight to behold and any- one living near a race site station should at least try and see the spectacle.” After the birds are released, the convoyer sends a telegram to the secretary of the Racing Pigeon Center in the city to which the birds are to home, stating the liberating time, direction of the wind, and weather conditions. This secretary then phones the secretary of each club affiliated with the center, giving him the information noted in the telegram. The paris of one of the common timers used along with a countermark may be observed in one of the photographs illustrating this article. Every fancier must have a distance measure- ment in miles and fractions by air line from each race site station to his loft. These distances are figured by a nationally known “surveyor.” As there are 1,760 yards to a mile, by multiply- ing this number by- 60, the result is 105,600. Multiplying the distance measurement by 1,056 (omitting the lest two figures for convenience) the result is the distance reduced to sixtieths of yards, If the distance by airline is 105.47 miles from the 100 mile race station, by multiplying 105.47 by 1,056 the result is 11,137,632. Reducing 2 hours, 31 minutes and 31 seconds (time con- sumed in flight) to seconds the result is 9,091 secónds. 11,137,632 divided by 9,091 gives 1,225.12 yards per minute. The fancier with a longer distance measurement will have an “over- fly” on the one with a shorter distance measure- ment; that is, a bird flying 105 miles could be 124 clocked so many minutes or seconds later, than a bird clocking at the same time or sooner and only flying 100 miles and still win because it had 5 miles farther to fly. The bird making the greater speed wins the race. There is no sport that is more dependent on wind and weather conditions for successful racing than that of pigeon racing. If the birds have tail winds and good weather on their flight home- ward, their speed will be greater than if they have io fly under adverse conditions. Pigeons have been known to fly over 2,000 yards per min- ute in some races. It may be interesting to know that a 500-mile flight was first made on the day of liberation in the United States in 1885 by a bird named “Ned Damon,” flown by Mr. Fred Goldman. A flight of 500 miles on the day of liberation was first made in England by a pigeon owned by a Mr. Pointer of London in 1896, elever years after the brilliant performance of "Ned Damon," so one can see that even at this early date the American birds were leading Europe in performance. Mr. E. S. Peterson of San Antonio, Texas, is another long distance fancier. Some of his birds have flown 700 miles оп the day of liberation and 800 miles more early the following morning. C. W. Oetting of Ft. Wayne, Indiana, bred a bird he called "Wayne Jr." that flew 1,000 miles in 24 hours-22 minutes-20 seconds, at a speed of 1,122.43 yards per minute. J. Kozlowski of Baltimore, Md., had a bird he called "Miss Havana" that flew from Havana, Cuba, to Baltimore in 1930 in four days. This bird, when released with several others, faced a water jump of 100 miles with high temperatures and prevailing winds against her. The shortest airline distance after she made Florida territory to her loft was not less than 1,300 miles, so one can see that it took real courage, stamina, and determination on her part to keep going. Tn June of each year the Chattanooga National Race is flown from Chattanooga, Tenn. This is a race to which fanciers living hundreds of miles away from Chattanooga send their best birds. And it takes a good bird to win, as it is competing against birds flying to Boston, New York, Wash- ington, D. C., Philadelphia, Pittsburgh, Detroit, Cleveland, etc. The bird winning the race is awarded $100. These birds, off in a flurry at daylight, meet varying conditions ranging from ideal to overcast skies, changing winds, and the possibility of rain squalls or storms on their way homeward. The 1935 winner, a Blue Checker cock named "Chattanooga," is owned by D. J. Clagett of Woodside Park, Md. This male outdistanced 1,114 champion racers from 63 cities and covered 525 miles in less than 11 hours. In 1936, the winner was also a Blue Checker cock bird. This bird is named “Swiftwing” by his owner F. E. Gorely, of Washington, D. C. Flying 534 miles, he arrived home the second day of liberation at 4:37 a. m., beating 1,151 birds from 278 lofts!

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Months from date you start school, Ex- perience or advenced education поб needed. Many Earn While Learning. Free lifetime employment service.Di Engines, Flectrie Refrigeration and Air 2 Conditioning Instruction included, MAIL, -— u—— — COUPON for FREE BOOK and all Facts, Е C. LEWIS, President, COYNE ELECTRICAL SCHOOL installments. 500'S. Paulina St., Dept, C7-54, Chicago, Send Big Free Book with facta on Coyne ing and tell ще 1 about А росы терасна оп Соуде ра Bias. і NAME. AGE. 1 | ADDRESS ] CITY. STATE. Body Completes Racer [Continued from page 89] a 95" mile dirt track and a rough one too. The best average in ten laps was 33.2 seconds per lap or about 69 m. p. h., just 4 seconds slower than the best average for full-size racers on this track. Dirt tracks are so rough that the tires can’t be pumped up to full pressure. With the low air pressure, centrifugal force shows its effect at around 65 miles an hour and the tires begin to “stand up” or increase in diameter. At full pres- sure, this doesn’t take place until a considerably higher speed is reached. In either instance, it is a precarious situation because of the loss of traction. If it were not a front-drive, it would be almost impossible to hold the car on its course under such conditions. Just to find how good the front-drive was at pulling the car out of a spin or skid, the racer was deliberately thrown broadside on the Ascot track at 70 miles per hour. If this were tried with a rear-drive car of the same size and weight, re- sults would be disastrous. From tests of this nature, it has been found that the driver must never go into a turn faster than he can continue through it. If you slow down during a turn, a spin is almost sure to follow and you must open the throttle instantly to pull out. Remember this: Always slow down before you go into a turn, then, as you make the turn, keep the front end pulling by gradually increasing the speed. At Muroc Dry Lake, test runs have been made to find how the car would behave at its top speed. At speeds of 90 to 100 miles an hour, it begins to feel rather light and has a tendency to drift with the slightest breeze, though at no time does it try to get out of control. At this speed, it is still possible to maneuver the car at will, providing that each move is made with caution. When 115 or 120 miles per hour is reached, which has been accomplished on several occasions, any attempt to maneuver the car, other than to keep on the course, is out of the question due to loss of traction. The tires increase to nearly 24" in diameter, and the side walls are not much over 1% inch apart. There is actually less than 1" of the tread width in contact with the ground: This can be clearly seen when driving the car; It shows up as if a black stripe had been painted around the apex of the tread on the tires. Some- times a trace of smoke is noticed when the top Speed is held very long on a hot day. After a fast run, to put your hand on the tires is like touching hot wax. At top speed any attempt to slow down must be done with the utmost caution for the rear end, due to momentum, moves forward when the car is slowed down too rapidly. The only way to keep the car from performing in this manner is to step on the gas again. When running at high speeds, you might as well have no brakes at all, for in the first place, should an emergency arise, you probably wouldn't have 126 Accept No Substitutes! Always Insist on the Advertised Brand!

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time to use them, and even if you did, it wouldn’t help matters any. To apply the brakes, no matter how carefully, the car would respond by doing plain and fancy somersaults, While the foregoing statements might lead you to believe that the Arlen Special is an extremely dangerous car, it is, on the contrary, safer at high speeds than a comparable rear-drive car would be. Everyone realizes that high speed driving with any car is more or less dangerous. Careful and skillful driving and frequent inspection of the car are the best way to avoid accidents and that applies to any racer. At ordinary road speeds, the Arlen is as safe as any car. As for the brakes, they are practically as efficient as four-wheel brakes on a normal sized car, because of the large braking surface area in proportion to the weight. Under normal driving conditions on the highways, it is doubtful whether you can tell by the feel that it is a front- drive type. But on slippery roads and loose sand or gravel, it is much steadier at all speeds than a rear-drive. It is just as easy to steer as the con- ventional type of car and the universal joints have no tendency to bind in a sharp turn. On account of the small road clearance, it is advisable to keep off of very rough, rocky or un- even roads. Stay on the smooth highways where you can take full advantage of the car's features. The building of "Arlen Special" cannot be completed over a period of one week. This car, it must be understood, is an elaborate project that requires the highest degree of careful planning before any construction work can be attempted. Patterns for the chassis and body should all be enlarged to full size plans by draw- ing them up on heavy brown wrapping paper. Before having any welding work done, make ab- solutely certain that parts are assembled correctly. “Arlen Special" will perform exceptiorially well if the car is assembled step by step as outlined in the two previous installments, which appeared in the June and July issues of МорЕвм МЕСНАМІХ. Work can be simplified to a considerable extent by working from the blueprint plans which have been prepared on this midget racer. While not actual size, the blueprints are sufficiently large to permit being used to best advantage in the. home workshop or garage. Those who now have the "Arlen Special" under construction, or who are planning to build this car, can obtain copies of these genuine blueprint plans at $3.00 per set. All orders for blueprints should be addressed to Modern Mechanix Publ. Со. Blueprint Dept. Greenwich, Conn. In the search for motor fuels, Italy is finding unexpectedly good results with anhydrous am- monia. A powerful electro-magnet was used recently to draw out five tiny sharp needles embedded in a mill worker's hand. | E make this generous о fet so that new thousands of car owners will try No. 7 Duco Polish immediately, and see how greatly it improves the ap- pearance of the саг: You should use No; 7 Polish on new cars as well as old. It keeps new cars beautiful and restores the color and lustre of oldfinishes dulled by grime and Traffic Film. Now we offer a Du Pont Cellulose Sponge (25c size) FREE to everyone who buys a pint can of No. 7 Polish. (Offer good in U. S. only.) This sponge, created by du Pont chemists, is ideal for bath and household cleaning, as well as for the car. See your dealer WHILE THEY LAST! When Answering Advertisements Please Mention August Modern Mechanix A new sponge made (like fayon) of Cellulose. Soft, durable, sanitary, absorbent. 127

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FACTORY TO YOU NEW REMINGTON NOISELESS PORTABLE AMOUS Remington Noiselesa Portable that speaks in a whisper, only 10с a day, direct from factory. Standard Keyboard. Auto- matie ribbon reverse. Variable line spacer and all the сопуепіепсев of the finest portable ever built, PLUS the NOISELESS feature, Act now. Send coupon TODAY for details, You don't RISK a Penny. We send you a Remington Noiseless Portable for 10 days’ free trial. If not satisfied, send it back. We pay all shipping charges, FREE typing course and carrying case, You will receive FREE a complete simplified home course in Touch Typing. Also FREE, & handsome, sturdy carryin EPA No obliga- tion, Mail coupon for full details -—NO = ce ee mes ee ee "EMEND GRE Ghé cuum uw Remington Rand Inc., Dept, 141-8 315 Fourth Ave., New York, N. Y. Tell me, without obligation, how to get a new Remington Noiseless Portable, Case, for 10с а day. lus Free Typing Course and Carrying end Catalogue, INA- GENTS!3:50 1. Big cash profits for yous full o spare time. Over 250 household necessities— things people. must Proven fast sele lers; steady repeaters, earnings very first day. TUDOR SEDAN GIVEN YOU AS BONUS ГИ show m y once; send you everything—] fit and quick cash plans. obligation. Just send name on postcard. ALBERT MILLS, 4057 Monmouth Ave., Cincinnati, 0. AIR CONDITIONING rE AND REFRIGERATION TRIAL LESSON \ Trained mor needed. Good pay. Learn easily AT HOME in spare time. for FREE TRIAL LESSON. CHICAGO TECHNICAL COLLEGE K316 Tech Bidg., 118 E, 26th St., Chicago, NI. If you can go away to pm to learn Air Conditioning En- gineering, 27 есите, rafting, Electricity, or kadio, for Ё Get ALIEDS Hew RAD | фе Send for TREE 15$6-раве 1937 ALLIED ME Radio Catalog—10,000 parts; dozens of kits; M 53 Knight sets; Amateur gear; Test instru- ments; Public Address; books, tools, etc. Low- est prices, fastest service. BUILD MOD- ERN MECHANIX CIRCUITS. Write for Free parts lists covering: Hitch Hikers’ Portable; Dx Tube AC-DC; All Wave set: Bicycle Radio; Match Box set; 6 Volt Farm Radio; Metal Tube DX'er; 1 Tube All Wave Set, etc. г ALLIED Radio Corp., Dept. 6-H | I 833 W. Jackson Blvd., Chicago, 111. і O Send me your new 1937 Radio Catalog. Opportunities, Write today _ Modernizing Your Graflex [Continued from page 110] figures, the number of feet from the camera to the moving object and the right figures are the shutter speeds necessary to stop motion at right angles to the line of motion. Only two-thirds of the speed is necessary if the picture is taken at a 45-degree angle. At the bottom of the right hand card are the hyperfocal distances for the 614-inch lens used. The hyperfocal distance for each. stop is that set- ting which will result in satisfactory sharpness from half that distance to infinity. For example, if it is desired to photograph a scene in which everything from 30 feet to infinity will be in focus, it will be necessary to set the camera for 60 feet and use the f. 11 stop. In calibrating the focusing knob, the hyperfocal distances for the camera lens were used so that they could be set to correspond. The data cards save much time and are well worth installing on your Graflex. With modern film emulsions there are few pic- tures which could not be improved by the use of an appropriate filter for the effect desired. Glass filters cost several dollars each, but gelatine filter material costs only 40 cents for a piece 2 inches square. However, in order to use this cheap and fragile gelatine, a holder is necessary to permit it to be clamped over the lens, in an exact plane with the lens and perfectly smooth, so that no dis- tortion will be introduced into the picture. Also, it is desirable that a lens hood be used to keep out the stray light rays that strike the lens from points outside the scope of the picture and cause a lack of brilliance in the negative. A combined filter holder and lens hood of heavy cardboard, designed to fit in a regulation filter holder intended for glass filters, can be made of heavy cardboard and works perfectly, being light and strong. Three pieces of cardboard are needed, two of which will slide into the filter holder together. They, each, have a round hole, the size of the lens opening, and are hinged with gummed fabric with the gelatine placed between these two pieces. The third piece forms the truncated pyramid, which is the lens hood, and is fastened to one of the first two pieces with strong glue. The inside of the hood is then covered with the dull black paper from films or enlarging paper to do away with reflections. To use, place the proper gelatine filter between the two cardboards with the holes, close them and slide into the metal filter holder and clamp over the lens. If you desire to use the hood without a filter, omit the gelatine. The gelatine sheets can be carried between the leaves of a little book when not in use to keep them clean and flat. The last gadget is one which has been a life saver on more than one occasion. It is a photo- flash attachment that will take almost every kind Accept No Substitutes! Always Insist on the Advertised Brand!

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of night picture required. The holder for the reflector is a flashlight case of the type intended for clamping on the steering post of an automo- bile. Part of the bracket is removed and the bracket screwed to the camera box. From this bracket, a flat brass strip is run to the upper shutter mechanism. Below the operating arm, for the focusing mirror, a piece of bent spring brass is fastened so that when the shutter is tripped and the mirror swings forward, it makes contact with the brass strip a fraction of an inch before the arm stops. From this bent strip another strip runs to one pole of a switch, originally intended to be fastened on the edge of an automobile dashboard, but now fastened to the camera with screws so that it is “off” when snapped up and “on” when snapped down. From the other pole of the switch a piece of spring brass extends for one inch, shaped so that a piece of wire can be clipped under it. Next, take a regular photoflash reflector and fasten a hose clamp around it, over the button, so that a solid contact is made. Drill a hole in the bottom of the case and insert a wire fastened to a contact in the middle of a wooden plug that will fit in the case between the tension spring and the bottom battery, Scrape any paint off the case, where it will snap into the bracket, so that a good contact is assured, To use this photoflash attachment set the switch on the camera to “off,” snap the reflector into the bracket, clamp the wire under the brass strip as shown and place a bulb in the reflector. Now set the curtain aperture at “0” and the tension at “1”. Be sure the mirror arm is swung toward the back of the camera, then set the lens stop at f. 11 or f. 16 for close-ups or f. 8 for distance shots and focus the camera for the proper distance by means of the calibrated focusing knob. Aim the camera at the subject, snap the switch “on” with the right thumb and trip the shutter with the left thumb. The shutter setting is for 1/10 second and during that time the flash goes off, taking 1/50 second, enough to stop most mo- tion. The extra time the shutter is open the lens is stopped down so far that nothing else is likely to be recorded on the negative. Now snap the camera switch to "off" and change bulbs. As long as the switch is "off" the bulb is safe and normal pictures may be taken as usual with the camera. When the occasion arrives when the flash is needed set the shutter in position, flip the switch to “on” and the flash is ready for use. With these added pieces of equipment the ver- satility of the Graflex is increased, permitting its effective use for a much wider and more difficult range of subjects and conditions. An eighteenth century counterfeiter used plati- num instead of gold to make Spanish doubloons —the platinum then rated almost worthless has since been valued as much as five times as high as the gold. 415, 000 VOLTS REV um U ‘OUTBOARDING IR етеу water pump or heavy jacketing to clog and corrode! Stream- lining—no exposed moving parts! Ignition designed by aircraft experts for instant starting! Full 180-degree steering! Full- leve] tilt-up! Outside controls and fuel-fill! Silenced underwater no-fume exhaust! Bendix quality! Here's outboarding at its top grade—for fishing, for work or for carefree water-fun! MederSM AL” мочь 55 OA s ‘онон: +3650 All Prices F. O. B. penes Bend (less batteries) FAST FIRING! Sensational new magneto delivers hottest spark ever known to outboard motoring—even at low cranking speed! Rugged! Permanent magnet life. GET THIS FOLDER —WRITE: BENDIX PRODUCTS CORPORATION (Marine Division) 457 Bendix Drive, South Bend, Ind. — AIR- COOLED OUTBOARD MOTOR When Answering Advertisements Please Mention August Moern Mechanix 129

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Mental Poisoning ! Thoughts that Enslave Minds Tortured souls. Human beings whose self- ‘confidence and peace of mind have been torn to shreds by invisible darts—the evil thoughts of others. Can envy, hate and jealousy be pro- jected through space from the mind of another? Do poisoned thoughts, like mysterious rays, reach through the ethereal realms to claim innocent victims? All of us, from day to day and hour to hour, in every walk of life, in every circumstance, are possible victims of mental poisoning, unless we understand its nature, and can quickly recognize its infegs ious innoculation. This FREE Sealed Book Do you know the strangest of all laws бп man's body? Man's life, happiness, health, and enjoyment of the things of life depend on his understanding of the working of the human mind. Let the Rosicrucians explain how you may ac- quire an age-old method for mind devel. opment and the proper use of your latent ‘inner powers. If sincere, write for the free sealed book. Address: Scribe Е.р,А. The. ROSICRUCIANS (AMORC) Зап Jose, California LET ME SEND YOU THIS TAILORED SUIT AND PAY YOU UP TO $10.00 IN A DAY! Amazing new idea! Wear this splendid suit and РИ pay you for it if you follow my easy plan and quality. Choose suit from fine woolens, union tailored to your Measure, Just show it to your friends. Маке up to $10 in a_day—casy—representing big nationally-known іаПог- ing house, No experience needed. ACTUAL SAMPLES FREE! Write today for details of sensational new plan and actual Samples. SEND NO MONEY. H. J. Graves, Pres, SLNE FIELD cone 1300 W. Harrison, Dept. W-737, FREE TO THOS ested in improving their work through the use of fine power tools-—a copy of the 48-page 1937 catalog describ- ing and illustrating the latest Driver Engineered Power Tools and accessories. Learn what it means to get yout money’s worth! Write for catalog to-day, WALKER-TURNER CO., Inc., 587 South Ave., Plainfield, N. J. DRIVER. POWER TOOLS Ее aside a aa. има, Govt Jobs | of These EN Do YOU Want? i No special education or experience | usually required. Steady work. Short [ MEN--WOMEN hours. Vacations. PENSIONS! Age 8-50. Extra Social Security Jobs ex- І START $1.260 to Н $2,100 а YEAR ected soon. REE book. Tells how you can pass Civil Liquor- Gauger I Stenographer Service Examination. md TEREE BOOK Meat Inspector Acthur R. Patterson, Custom House (Former Govt. Examiner) Principal, PATTERSON SCHOOL, i Office Clerk—Tvpist Accountant 438 Mercantile Building, Rochester, N. Y. Send FREE Book, “How to Secure а a File Clerk — Income Tax Auditor Government Position.” EM HEB es eee GUN NN = ыи ume Peri Send coupon below for 130 A Recording Rain Gauge [Continued from page 81] clips are able to grip it. Graph paper for this drum can be purchased at any architectural supply store, the preferable type has inch di- visions sub-divided into tenths of inches. A 12- inch circumference drum makes each large hori- zontal division represent five minutes of time. The copper funnel, for collecting the rain, has a 2-inch vertical edge to prevent the rain from splashing in or out. The top of the funnel is 1% inches in diameter and the lower tube is 14-inch in diameter. To this lower tube a 10-inch piece of rubber tubing of appropriate size is fastened. The float tube is constructed from the same size tubing as the top of the funnel. To this tube, which is 10 inches tall, solder a side arm connec- tion 112 inches from the top, for attaching the rubber tubing from the funnel The side tube Should not extend on the inside of the float tube or it will hamper the action of the cork float. The side arm tube is cut from a 44-inch copper tube So as to fit the rubber tubing that leads from the funnel. The cap for the float tube is formed of thin copper sheeting, and provided with a #&:- inch hole in the top of it for the float wire. A cork, coated with shellac for water-proofing, is used for the float. Being slightly smaller in diameter than the float tube, it insures smooth action with a minimum of wabbling. Using a 9-inch piece of No. 12 wire that has one end flat- tened, and a hole bored in it, stick the round end through the hole in the float cap and after coating this same end of the wire with glue, push it into [Continued on page 133] "Ether Imp"—4A Transmitter p a re e [Continued from page 103] measuring only Yí-inch in diameter. The tube’s petite, proportions are not its only virtue, however. for it is the only one that will satisfactorily oscillate at 400,000,000 cycles, which is the frequency of the 3í-meter band. While the usual receiver tubes, have, in some cases, been made to oscillate at these frequencies by freak hook-ups. the ‘tacorn” tube stands alone in its ability to give a reliable, stable and non-fluctuat- ing signal. The “Ether Imp" is built into a small box 3-inches wide, 3¥4-inches high and 2-inches deep. The box should prefer- ably be of wood, since the capacity of a metal housing will prove troublesome because of hand capacity produced at ultra-high frequencies. The box should have a sliding front, to facilitate installation of the parts and to make them readily accessible for adjustment. At the top of the box, install two 34-inch feed-through insulators. These tiny insulators hold the miniature doublet radiating antenna in place. The single button lapel mike, that modulates the carrier wave, is fastened onto the sliding front of the box with a machine screw. At the left side of the housing a pointer knob and a dial index are installed to make the tuning condenser easily adjustable. The handle from an old screwdriver, chisel, or similar tool makes an ideal grip for carrving the transmitter. Before fastening the handle to the box, a Y4-inch hole is drilled through it lengthwise to later take the 4-conductor flexible battery cable. The variable tuning condenser is homebuilt and consists of two semi-circular brass plates, with a radius of %4- inch. One of the plates is fastened to the shaft of the pointer knob at the side of the housing, so that it will revolve. The other plate is mounted in a stationary position to a small bakelite strip as shown in the diagram. The distance Accept No Substitutes!’ Аксаух Insist on the Advertised Brand!

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between these plates must largely be determined by experi- mentation, since all sets will vary somewhat. In no instance though, should the gap be greater than %-inch. Commercial sockets specially made for the “acorn” tube can be purchased or you can make your own from a two- inch square of bakelite, The tubes are provided with five “pigtail” leads, instead of the usual tube prongs, and connections are made through these leads. Provision must be made on a home-built socket for the five contacts. Five Fahnestock clips will do. Note that the grid and plate are together at the top, and the cathode and two filament leads at the bottom. The bakelite square is supported at each corner on а ¥%-inch insulator. Drill a hole 34-inch in diameter in the socket’s center to accommodate the base of the tube. The tuning inductance is wound of No. 18 enameled copper wire and consists of 8 turns, each turn 14 -inch spaced from the next. The outer diameter of this coil should be 14-inch, therefore it must be wound on a y-inch form to allow for the size of the wire and its expansion after winding. The completed coil is supported оп 33-inch insulators, one at either end. The hook-up is not at all complicated, The feed-through insulators at the top of the transmitter housing connect to the coil, one to either end, and contact should be made through No. 28 enameled copper wire. Leads to the insula- tors should be spaced as far as possible from each other. The radiating antenna is of the modified doublet type and consists of two lengths of copper strip, each exactly 714- inches in length. Each is drilled at the extreme end and fastened to the insulator. The left end of the tuning coil, or grid end, connects to one lead of a .00025 mfd. fixed mica “postage stamp" con- denser and to the moving plate of the variable tuning condenser, The opposite end of the .00025 fixed mica condenser connects to ihe grid lead of the tube and thence to the cathode connection through a 15,000-ohm grid resistor of 1-watt carbon variety. It will be noted that the cathode lead is the center connection of the group. The cathode tap also fastens to one side of the single button lapel type carbon microphone. The opposite side of the mike connects to the negative filament connection. The plate connection of the “acorn” tube connects directly to the plate end of the coil. 'The plate also makes contact with the stationary plate of the tuning condenser. The radio frequency choke construction is decidedly critical at this high frequency and in this particualr circuit should consist of No. 32 cotton covered wire, close-wound on a form 14-inch in diameter for a distance of about 144-inches. One end of this choke goes to the plate contact of the tube while the other end connects to the positive “B” battery lead of the 4-conductor battery cable. The negative “В” battery cable connects to the cathode tap of the tube. The other two leads connect to the positive and negative filament contacts of the tube, respectively, The cable is then passed through the drilled handle of the transmitter, putting it entirely out of the way when using the set. A switch should be installed on the handle of the set and inserted in the negative filament lead to turn off the current. WARNING! Do not try to solder the connections to the acorn tube, since the heat generated by the soldering iron may injure the delicate tube elements, Before putting the set into operation, be sure to check the wavelength to make certain that you are operating in the prescribed amateur band. Measuring the wavelength at 34-meters is very simple, being accomplished by the Lecher wire method as shown on page 103. About 5 feet of copper strip is bent “U” shape, spaced three inches apart and supported, by small insulators, on a wooden baseboard. Iusert a 0-200 milliammeter in the positive plate lead as shown. Place the bend of the copper strip near the antenna of the transmitter and then slide a copper bar along the copper strip so as to Short the two sides. When the needle of the milliammeter reaches the highest point, measure the length of the strip around the bend, from one end of the sliding rod to the other, to determine the correct wave- length. The sliding rod should always be insulated from the hand when determining wavelength. In makiug these tests. have the transmitter in an upright position. The set will not oscillate if the mike is in a horizontal position, since the granules in the button make no contact when horizontal. Next month. the companion 34-meter receiver will be described for building. The two sets together make an ideal duplex or two-way communication system. Until'the receiver is built, you can check the modulation of the set and signal quality by using a set of earphones, shunted by ап .001 mfd. fixed condenser, and a crystal detector in series with one of the leads. Connect one end of the crystal detector to the copper “U” at the point where the slider bar stopped and the other lead of the phones to the other side. This will pick up the signals originating in an adjacent room and allows for final adjust- ment of the transmitter before building the receiver. Get the FREE Book NI е P of a ee E oe АМА \ NN = [ЕЕ Ny Brimful of terse instructive facts about TELEVISION RADIO SOUND RECORDING ELECTRICITY Note These Interesting Contents Written in plain, understandable language, this free Book gives facts you want to know NATIONAL SCHOOLS is about the best-paying trades and opportu- tion in the West. Ese nitles, 95 illustrations. Major subjects tablished 1905. You include Television Theory and Construction, сап earn room and hoard smi while learning. Coach Pick-up Systems, Amplifiers, Transmitters. Tiliroad fare allowed to Jteceivers, Cathode Tubes; Radio іп all its pos Angeles. This service only for residents of branches, Receiving, Broadcasting, Trouble- shooting, Construction and Theory; Sound- recording on Discs: Loud Speakers, Talking Picture Projection, Radio Communication, Laws, ete. This book also tells how you ean qualify for these good pay trades by train- ing at NATIONAL SCHOOLS. Send coupon now for free book. NATIONAL SCHOOLS LOS ANGELES Е... NATIONAL SCHOOLS, Dept. 8-MMR 4000 So. Figueroa St., Los Angeles, Callf, Without obligation send your free book. When Answering Advertisements Please Mention August Modern Mechanix 131

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MEAD'S NEW RANGER cHAMBPIon! — ВОТ FIRST IT’S YOURS Here it ist— The snapplest PER $ Туккк—— TO TRY FOR 30 DAYS picycle Mead has ever of- fered during 50 years of leadership—the new super-streamlined Ranger CHAMPION! Built-in speeaometer. Jump Into the saddle—try it a whole | month at our ri: Then, if not perfectly satisfied, return at QUR expense! Latest fearures. Save AN buying direct from Mead. Send postal for fr Y ial offer: MEAD CYCLE CO. 15 55. Market, Dept P-289 CHICAGO, U.S.A. RTOON YOUR WAY Yro SUCCESS] DON’T COPY - LEARN TO ORIGINATES RAYE BURNS will teach you HOW to TETI 85 ORIGINAL CARTOONS at home that you can BELLI Course has 26 lessons and 600 Send name and address for free. 600 oad RAYE BURNS SCHOOL, Dept, F-X, Box 2194, CLEVELAND, OHIO T MECHANICS & WELDERS ce Mechanics and Welders are in big de- Write | fo ” mand. Complete courses in arc and acetylene welding, metal finishing, body and fender bumping, spray paint- ing. Special low rates, Write today. MICHIGAN TRADE SCHOOL 3763 Woodward Ave., Detroit, Mich. a IFREE CIRCULAR DEALDIRECT.. .FACTORY PRICES! Many models to ве lect from: AC-DC;All-Wave Farm seta that operate like city radios! Your name and address on postcard brings you NEW Bargain Catalog in colors FREE, Get details of 30-DAY TRIAL plan and Е GOLDENTONE RADIO co Dept. H-8, DEARBORN, MICHIGAN || Oe ANIMALS, HEADS, FISH Also to tan shins and FURS. Easil - Learned AT HOME BY MAIL. Wi! jd ame growing зсасег- big demand: Bea taxidermist. Mount f. or others E ig Fun v Hobby. = ed. J REAL PROFITS IN SPARE TINE, FREE BOOK х gets 1, Bors, aa FREE BOOK-tells how YOU can learn this fine art quickly. Investigate. Seud this m minutas State AGE. | N.W. School of Taxidermy, Dept.C473 ОМАНА, NED, 132 Accept No Substitutes? Conditioning Your Sail Boat [Continued from page 95] fungus spreads quickly although it can often be easily killed. Dig out the rot thoroughly so pre- ventative measures can be applied at once. If the spot is small and does not extend through the member attacked fill the cavity with wet salt or use one of the different preparations com- pounded to combat rot and mildew. Do not cover the spot at once but leave so its condition can be observed from time to time and further treated. Later, when the rot is killed, you decide against replacing the faulty member because of its other- wise good condition, fill the cavity with melted marine glue or pitch or pack the hole with salt and screw down a batten in marine glue over it. A handful of salt thrown in any unventilated locker or where fresh rainwater lodges will help prevent the wood being attacked by dry rot. If the rot has advanced to such an extent so as to structurally weaken the boat have a boat car- penter replace the member. The renewing of a neatly fitted stem on a fair-sized boat, for in- stance, may seem an impossibility to the owner but builders have a saying that there is nothing built into a boat which cannot be replaced. Do not attempt such structural repairs yourself. Simpler jobs are within the amateur’s capacity and this is the time to do them while the boat is drying out and the weather improving. If the [Continued on page 137] Double Unit Floodlight Case [Continued from page 114] of all members for insertion of the aluminum or tin reflectors after the floodlight case has been assembled. Proceed to assemble the case, using light finish- ing nails to add further strength to the glued joints. When both sections of the case have been carefully put together set them aside and allow one day for the glue to set. In the meantime, a sheet of thin polished aluminum can be obtained and the reflectors cut from it. Two methods are available for this in- stallation; one involves the use of three separate aluminum panels, as was used in the original, while the other permits the use of a single piece of aluminum, bent “U” shape and the ends in- serted in the rabbets along the sides of the case to hold it secure. While the latter type of re- flector requires little explanation, mention of the three piece reflector is in order. Assuming that the case has been allowed sufficient time for the glued joints to dry, mount one piece of aluminum in the back and fasten it in place with small brads or escutcheon tacks. Next, insert the end of one of the side reflectors in the rabbeted groove and fasten it in position at a 30 degree angle. By previously fastening [Continued on page 139] Always Insist on the Advertised Brand!

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A Recording Rain Gauge [Continued from page 130] the cork. To the top end of this wire, where the hole has been bored, bolt a piece of wood 5 inches long, ¥s-inch thick and %4-inch wide to serve as the pen arm. Allow 1-inch of the wooden pen arm to protrude at one end so that an appropriate counterweight can be attached. To the other end of the arm, glue a 12-inch cube of balsa, with a is-inch hole bored in it for inserting the pen. Halfway between the float and the balsa pen holder, glue a small wire hook on the pen arm to serve as a spring. This spring holds the pen against the graph paper while the other end of it can later be fastened to the back of the gauge shelter. The spring is made by taking a piece of No. 30 wire and winding it around a pencil It must not be wound too tightly or it will prevent quick action of the pen on the graph paper. Its strength may be adjusted by experiment. The pen, which is of original design, requires none of the customary slow drying inks, but op- erates very well using fountain pen ink. Procure a piece of !4-inch glass tubing and heat it in the middle, above a hot flame, until the glass is flex- ible. Quickly pull the ends of the tubing, stretch- ing the glass, and you will have a very small tube with a small opening in it, known commonly as a capillary tube. Now heat the tube and bend as shown on page 81, using the extra end as a hand hold. The unneeded end may be broken off by scratching the glass with a file and breaking it with the hands. If in operation, the pen allows too much ink to flow, the opening in the end may be heated more and closed still further. The curve in the tube is to prevent flooding and at the same time allow a large ink supply. Do not be dis- couraged at a few failures. With a little practice it is possible to make two or three pens in five minutes. It is wise to have several extra pens on hand in case one should break. When com- pleted, the pen is mounted in the hole in the balsa pen holder. The rain gauge, after installing the pen, is mounted in a wooden cabinet. A box, 9 by 9 by 20 inches, covered with oil cloth for water proof- ing and provided with a hinged door in the front, is well suited for the purpose. A 1!4-inch hole is drilled in the top of the cabinet for the funnel. The clock is mounted 7 inches above the bottom of the box. Since it rests on its back, it is ele- vated on four small nails so it is level, but still can be removed for winding. The float tube fits snugly in a block with a 195-inch hole bored in it. The completed shelter is placed on a permanent platform, 1 foot high and secured by four small door hooks, one at each corner, so it can be brought indoors during the winter months. The automatic rain gauge should be set into operation at the first hint of an approaching storm, as the record will not be harmed by con- [Continued on page 135] * When Answering Advertisements Please Mention August Modern Mechanix г TURN SPARE HOURS INTO CASH! 49 Weekly InYour Own Home No soliciting! No canvassing! We show you how to make big money decorating fast-selling Giftwares. We start you with the big 310 Artist's Outfit shown above. We supply you with $150 worth of Giftwares free of extra charge and show you how to dis- pose of them without leaving your home. We give you 29 Tested Plans for making money. One Fireside Member says, “I made _ $100 on furniture in one week.” Another writes, “My sales were $500 for 5 weeks. 'This is my first year.” Ц. M. P., of Ill, says, “I did $3,500 worth of business last year and over $12,000 this year," D. W., New Mexico, reports, “1 would not take $1,000 for my Course.’ No Experience Needed You too may have a guaranteed income opportunity with Fireside. No tiresome study. You learn by doing. No artistic ability neces- sary. Our easy 3-Step Method makes the work easy to learn and , easy to do and fits yeu to make pud money practically from the start. Quick Sales in Your Home No need to leave the house to dis- pose of everything you make. Our new automatic salesman does all the selling for you. Designed to quickly find cash buyers for all the Giftwares you can turn out, No Cost Plan Send coupon for details of new plan that pays for your Fireside Course besides putting big cash profits in your pocket. Mall cou- pon now while openings for new members are still being offered, FIRESIDE INDUST RIES Dept, 142-K Adrian, Mich, Fireside Industries р Dept. (42-K. Adrian, Mich. Send me FREE Book on Home Deco- rating for a big steady income. Also details of plan that will pay for my Course and give me big profits be- sides, ета am sm emm «л SS NS

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HOW TO OBTAIN A PATENT Written by a_Former Member of the Examin- ing Corps (1922-24) of the U. S. Patent Office, 1? you want to profit by your idea, you should = take stens to apply for a S. Patent at once. Your first step is to get this Free Book. This interesting illustrated book contains valuable information È it tells you fully how to obtain a patent В on your idea in the quickest way. With this Free Book you will also receive a “Record of Invention" form on which уси can easily record your idea. Personal and Confidential Service: Your case will he personally handied only by a Registered Patent Attorney who is also a Former Member of the Examining Corps of the Ц. S, Patent Office. АП com- munications confidential, MAIL COUPON TODAY for FREE PATENT BOOK and RECORD OF INVENTION Form CARL MILLER REGISTERED PATENT ATTORNEY FORMER MEMBER EXAMINING CORPS U. S. PATENT OFFICE. 1638 Woolworth Bidg., Dept. 5/5, New York City MILLER BUILDING, Dept. WASHINGTON, D. C. Please send me your Free Book, Mow to Obtain a Patent,” and your “Record of Invention” form. you should have. [| L] 1 NAME) si LUDUM E L| ы ADDRESS. ае ES Re ursi aie d e a eain xim a аа a Па па па но ee as Oa St DO Б за п а аа DO IT WITH SQUABS Easily, steadily raised in only 25 days. Write a postcard, ask for eye-opening picture book. Why cater to ordinary trade when these great luxury national markets are wide open ^ for all the SQUABS you can ship, every day in the year, at PROFIT- ABLE prices. We give a large bonus in stock for promptness. Elmer Rice, 602 How. St., Melrose, Mass. APPRENTICES Ambitious, air-minded young men, interested in entering the well paid field of Aviation, write ә immediately, enclosing stamp, ta MECHANIX UNIVERSAL AVIATION SERVICE, Strathmore Station Dept. A Int. Detroit, Mich. Full size, heavy duty ‘Aladdin Electric ARC WELDER only $39.25 with De Luxe Accessories! Has efficiency of inaehlnes costing $145 to $80: Welds all metals and alloys 1900. heavy motor block and castings to fenders and light sheet metal. Also fine for soldering and brazing. Fully guaranteed. Approved ‚РУ Automotive Test Laboratories. Easily portable on casters. WORKS FROM 110-V SOCKET. Simply plug into 110-Volt or 220-Volt electric socket— costs only few pennies an hour to use. Has complete heat controls, Anyone can use easily. Full instructions included. AMAZING DETAILS FREE! Write today for sensational facts about Aladdin Are Welder for $39.25 including De Luxe Accessorles. COMMONWEALTH MFG. CORP., Dept. Y-52 4208 Davis Lane Cincinnati, Ohio With Deluxe ACCESSORIES 134 Accept No Substitutes! A Walnut Ice Bucket [Continued from page 99] push it back slightly and very carefully remove a little more wood from the bucket. : When all three hoops are in position and spaced uniform- ly, smooth down the outside of each hoop by turning the lathe at a slow speed and holding a flat file lightly to the metal. Last, rub the hoops with steel wool to polish. Before applying the finish, all cracks must be sealed with wood filler, but exercise care so that the filler does not get on the metal, then set aside and when dry, sand off the surplus lightly and apply a thick coat of clear lacquer, spar varnish or white shellac. The shoulder to form the recess for the spun cover should be cut while the block is still in the metal lathe, since the end of the jig will cover it up. Cut off enough of the bottom of the bucket to remove the tail stock mark and sand smooth. Cut and polish a [cum z i INSIDE ОР. BUCKET FACEPLATE JIG USED IN WOOD LATHE TOPPER > WIDE WALLS V THICR SHOWING HOW LAP ENDS ARE JOINTED CROSS SECTION OF PINE. JIG USED TOSPIN COVER ОЕ COPPER Before starting on the construction of the walnut ice bucket study this cross-section diagram thoroughly so that errors are avoided. The lid is of copper, spun over a turned wood jig. strip of quite heavy gauge copper, 14-inch wide and bend to а “U” shape to form the handle. Fasten it in place with small, round head screws, Small washers inserted between handle and bucket will prevent the metal from scratching the bucket's finish. To make the cover, slightly crown a block of white pine of good size and turn it off flat. The center of the crown should be about 14-inch higher than the edges with a groove around this erown of the same diameter as the extreme diameter of the cover is to be. Place this jig in the metal lathe, fasten a square of copper over it by bending down the corners and secure with small nails. Grease the metal surface well and, with a smooth, rounded rod, conform the copper to the shape of the jig. An excellent tool for this purpose is a steel ball about J4-inch in diameter which is welded to a М by 14-inch iron bar 3 inches long. This is held in the tool post and the ball applied firmly, but not too hard, against the surface to be shaped. As a last step, crimp a bead around the edge of the cover, polish and then cut off. Turn a small knob of walnut and fasten it to the lid with a small screw from the underside. Give knob and cover a coat of lacquer, spar varnish or white shellac. Before the bucket can be used as a container for ice cubes, it will be necessary to waterproof the inside, To do this, dissolve a quantity of white paraffin in a tin can by placing it over a gas flame and, while the wax is in liquid form, brush it over the inside surface. Always Insist on the Advertised Brand! *

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So You're Buying A House! [Continued from page 120] off ventilation. This is of particular importance in one-story houses whose windows are barely above street level. You will want to keep your lawn in respectable condition and grow a few shrubs and flowers. That means a grass cutter, a roll of garden hose and at least a few elementary implements and supplies, to the tune of about $25. And then you'll find that animals, neighbors with baby car- riages, and children on skates and bicycles trample all over your fresh seeds, and you'll wish you had put up a stout fence like the one the Jones’s have down the street. You can do a pretty good job yourself with 2 x 4’s for posts and ready-cut pickets, for about 40 cents a running foot, or you can be extravagant and have a fence company put in wire mesh and iron posts, at about a dollar a running foot. You most certainly will want a finished room or two in the basement, for a darkroom, work- shop or den. There’s practically no limit to what you can spend here. A modest room about 12 by 22 feet (the full width of one end of a typical cellar) costs about $50 for simple board walls and insulating-sheet ceiling. When you buy the house allow yourself at least $100 for general “fixing up.” In a house equipped with an oil-burning furnace, the basement is just as liveable as any of the upper floors—frequently more so. The builder leaves it rough because he doesn’t want to make the house appear expensive. Cover the ceiling beams, put up walls and a few curtains, paint the floor a gay color, and you increase the value of the dwelling tremendously. Total the foregoing items and you'll see that a thousand dollars isn't too much to add to the "price" of a medium-size one-family house. Don't let this figure disturb or discourage you. It is better to be prepared for the expenditure than to have it overwhelm you later. Adopt the atti- tude that your house cost $5,790, and not $4,790, as the signs down the road indicate, and you'll never feel sorry that you spent more than you really intended. A Recording Rain Gauge [Continued from page 133] tinuous operation. Recording without a rainfall merely makes a continuous line around the drum, When the rain begins to fall, the pen climbs up onto new graph paper. Should the rain last over one hour, or longer than it takes the drum to make one revolution, the record will still be preserved for on the second revolution of the drum, during a rainstorm, the pen will be above its former posi- tion and will not interfere with the first line. Always leave enough water in the float tube to float the cork and pen arm, otherwise a rainfall will not cause an immediate rise of the pen. Aigh School Course at Home Many Finish in 2 Years You сап complete this simplified High School ; Course as rapidly as your time and abilities permit. Equivalent to resident school work —prepares you for entrance to college. Stand- ard Н. S. texts supplied—Diploma, Credit for H. S. subjects already completed. Single sub- jectsif desired. High Schooleducation is very important for advancement in business and industry and socially. College Entrance During the past 14 years, our High School graduates have been admitted to 531 different Universities, Colleges, Junior Colleges and Normal Schools—80% of them without entrance examination. Course also prepares for teachers' certificate and pre-professional examinations. Business—Industry To get and hold a good position in Business today you rnust be able to write clear, accurate letters and re- ports—do figuring involving Algebra and Geometry— talk intelligently on matters requiring a knowledge of Geography, History, and Economics. In Industry—Mechanical and Engineering lines— you must have at least an elementary knowledge of Physics and Chemistry—be able to figure quickly and accurately—know something of Mechanical Drawing and biueprints—and be able to talk and write ac- curately and clearly on both your work and ordinary topics of conversation. Our High School course meets the preparatory edu- cational requirements for Business and Industry. An Educational Institution The American School was chartered in 1897 as an educational institution, not for profit—and is exempt from paying Federal income tax, like the best resident colleges and universities. Don't Be Handicapped — Complete Your Training Now Be a High School Graduate! Prepare yourself for promo- tioninBusinessandIndus- 20 Other Courses try —for the Professions, College Entrance and so- Over 150 noted Educators, En- Rineers, and Business Men cial success. No matter what line you may select, helped prepare our special in- High School training will struction material, which Is prove invaluable to youl used by many resident schoola Our moderate fees cover all instruction, standard textbooks and Diploma. Easy monthly terms. Get and colleges. U. S. Navy, and Province of Manitoba, Canada. We off б, quality training а at home for the best- paying lines of Industry and Business, as listed in the coupon, ahead in life. Start your training NOW Mail coupon for information about line that interests you American School, Drexel at 58th, Chicago vum iu à € Mas € € —À — uÀ € —— —— —— — — —À— — — —— American School, бо НС29, Drexel at 6810, Chicago Tell me how to train for success in line checked. No obligation. OHigh School Course DAccounting & Auditing [Diesel Engineering OArchitecture & Blding O Drafting & Design O Automotive Engin'rin& OLiberal Arts OBusiness Management [Private Secretary OCom’ercialAeronautics OHi’erAc’t’g(C.P.A.) O Electrical Engineering OHighway Engin'r'é OElectrical Refrigerat’n (Mechanical Eng’r’¢ Air Conditioning О Radio & Television D Civil Engineering О Salesmanship D Complete Law O Steam Engineering When Answering Advertisements Please Mention August Modern Mechanix 135

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1,500 NEEDED INVENTIONS Concentrate your talents on inventions that wiil pay BIG MONEY. 1936 Edition of 1500 NEEDED 5s NVENTIONS by R, Е. Yates tells what inven» >” ^ tlons manufacturers NEED badly. Describes in detall 1500 Needed Inventions In these fields: Genera! Problems; Automotive; Electrical; Me- chanical; Chemical; Aviation; Radio; Marine. Also chapters on the Ten Most Needed Inventions, and on new sclen- iific discoveries Important to inventors. Simple, practical ideas—one idea from this book may win you a fortune, If you want to Invent, know what inventlons will ny you the most money. This book tells ou. Keeps you from working on Inventions nobody wants to buy. arge cloth bound book, £50 pages, nine big chapters. Only 52.5 » Drop a postal and we will send 1500 NEEDED INVENTION .O.D. We pay postage If you send cash with order. If mot delighted after 5 days’ examination, return it and get your money back. INVENTORS’ SELLING GUIDE How and where to sell patented or unpatented inven- tions. inventors’ Selling Guide by R. Е. Yates noted authority on Inventions, gives classified list of nearly 1000 manufacturers who buy ideas. Tells how to sell unpatented Inventions safely, how to sell chaln stores, how to price Inventions, selling by correspondence and demonstration, how to find buy- ers, etc. Tells what an Inventor must know about * Law, Royalty, Contracts, Patents Pending, Financing, Gyp Schemes, Selling Methods. Cloth bound book, 224 pages, 15 chapters, Postpaid $2 (or „O.D. plus postage.) Satisfaction guaranteed. BOTH BOOKS FOR $4.00. if ordered at one time Write for FREE specimen pages and complete catalog of valuable books for inventors. DONLEY PUBL. CO., 509 Fifth Av.:Dept. M-8, New York, N.Y. PARKS AIR COLLEGE: PARKS AIRPORT - EAST ST.LOUIS, ILL- Also: Take Out our Own Patents, $1.00 Making Unpat- ented Inventions Pay, 50c Offers you college education majoring in aviation Four 96-week courses lead to В. Я. degrees in Professional Flight Aviation Operations, Aviation Mechanics, Aeronautical Engineering. 100 acre airport, 14 buildings. 33 in faculty. 241 enrolled. 5,800,000 miles flight training. 1,548 planes. 523 engines repaired and rebuilt in shops. Graduates with all leading aviation companies. Dormi- tories, dining hall on field. Fall term Sept. 27th. Catalog. Write 10th YEAR REGISTRAR, DEPT. MM-8 PARKS AIR COLLEGE, EAST ST. LOUIS, ILL. “Make money in advertising. Prepare quickly during spare time. Also earn while you learn. No experience necessary, New easy method. Nothing else like it. Send at oncefor free booklet—‘‘Win Success in Advertising,” and require- ments. No obligation. Pa&e-Dsvis School of Advertising 3601 Michigan Ave., Dept.205C, Chicago, U. S. A. rm РАЗУ #5. А DAY! Possible with new “QUICK ACTION" — œ (1837) perfected Invention the ens ~~ A sure sale whetever artificial is used, Retails for 25c. CERE /1 MYSTERY GAS-LIGHTER Big Money AC TNT) ПЕ Money Сбн Ew METHOD MANUFACTURING CO. Act Now! „New Method Bldg. M G-56, BRADFORD, РА. Wanted—Amateurs with humorous ideas, No drawing ability necessary. The amateurs of today are the professional саг’ toonists of tomorrow. Ideas Judged and prizes awarded by Applause-O-Meter test before movie audiences. Everyone has an equal chance. 26 cash prizes in all. Rush name on penny post card for ‘Valuable Tips on How to Make Money With Simple Cartoons and Humore ous Ideas”, Cash Prize Entry Blank and Tules—SEND NO MONEY. có CARTOONISTS' EXCHANGE, Dept, 358-B, Pleasant Hill, Ohio 136 $2.50 Breakfast Nook [Continued from page 96] lumber is wasted through boards splitting during the operation of knocking the packing cases apart. After the necessary amount of lumber has been collected, plane and sand each piece smooth, first of course cutting the boards to their correct sizes. The benches are 47 inches in length and provided with seats having a width of 17 inches, From these dimensions, the builder will have little difficulty in making the back support pieces, legs and runners since they can be cut accordingly. The rear legs of the bench are 34 inches in height, or twice the height of the front legs, to permit simple installation of the two boards which form the back support. The tops of these pieces are tapered off to eliminate sharp edges and at the same time provide a neater design for the com- plete’ bench. Assembly of both benches and table should be done with flat headed wood screws, properly countersunk. The table does not require any detailed ex- planation. A novel three-leg arrangement per- mits the table to stand perfectly rigid without inconveniencing breakfasters when getting in and out of the nook. The top of the table is built up from several planks, each securely screwed down to a pair of runners, to provide a table surface measuring 29 inches in width, The legs are made secure to the runners; two mounted on the end facing the wall and one located in the center of the opposite runner in the manner shown in the photographic illustration of the completed breakfast nook. With all woodworking operations completed, apply a coat of flat paint to the table and benches, followed by two coats of quick drying enamel. After the paint has been allowed sufficient time for drying, an oil cloth top is installed on the table and fastened in place with half round mold- ing. Cardboard backing, placed under the oil cloth, before it is tacked down, will provide the necessary cushioning and at the same time pre- vent any impressions of the boards from showing through. The benches are provided with leatherette cushions, their construction being left entirely to the discretion of the builder. In making the cushions, the leatherette can be formed into re- movable pads or tacked down to the bench seats. For a very neat finish, removable pads are ad- vised and while they will involve the use of slightly more material, the added cost will be well worth while. Controlling malaria in the United States means chiefly fighting two types of mosquitoes that carry the disease. Government scientists are trying to develop a kind of broom corn that will make good brooms and also will yield seed palatable to livestock. Accept No Substitutes! Always Insist on the Advertised Brand!

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Conditioning Your Sail Boat [Continued from page 132] craft leaked last season, you no doubt, traced the water to its inlet. Examine the faulty area close- ly. As the seams are somewhat open after the winter layup the leak may be apparent. Leaks are often hard to find because the water may come in at some distant spot and run along a seam before actually coming into the boat. A small check in a bottom plank may cause the trouble. Bore a 3/16-in. hole at each end of the erack and into these drive lightly, soft wood plugs dipped in liquid marine glue. Dress off each side flush and serew down a 1/4 x 1%-in. batten somewhat longer than the crack inside. Then, working from the outside, fill the crack with one of the non-hardening seam fillers put up by the marine glue makers or with a wood preparation. Fillers such as putty harden and crack and do not give with the swelling of the wood. Keep the filler just below the surface for when the wood swells it will be crowded flush. The leak may be traced to a faulty butt block. These are located inside the hull between frames where plank ends are joined. Examine their con- dition for rot or inability to hold the screw fast- enings. If at fault, split out the butt block and use it for a pattern to shape another. Use plenty of glue when fastening the new one and be care- ful not to crack the ends of the planks when coming up on the screw fastenings. Before attempting any caulking make sure the seams need it then proceed carefully. Use a single strand of candlewick dipped in glue forcing it into the cleaned out seam lightly with a putty knife and fill flush with seam filer. If you put off fitting out until too warm weather many of the underwater seams will open up. Do not caulk or fill these. If the boat was tight at these places last year it will be this when it swells—unless you leave it out of the water too long. Boats with open seams can be placed overboard to swell but they usually sink and have to be later pumped out or raised. To prevent the craft sinking use soft laundry soap or one of the waxes developed for this purpose. Simply wipe the soap or wax along the seam to keep the water out until the wood has a chance to swell. Wonders сап be worked with old boats by iron- ing muslin in hard marine glue over leaking spots or by using sheet lead patches. The glue treatment calls for carefully cleaning the faulty spot and surrounding wood of all paint and oil then brushing on glue heated until it works like paint. After the glue hardens lay a correctly shaped piece of unbleached muslin over the spot and press down with a hot flat iron. The heat sweats the glue through the fabric and allows you to smooth it out perfectly. After sanding and painting you have a permanent job. Thin sheet lead patches are applied after coat- ing the faulty place with liquid marine glue or [Continued on page 141] When Answering Advertisements Please Mention August Modern Mechanix NEW 3-WAY TREATMENT HAS PUT ON SOLID POUNDS FOR THOUSANDS OF SKINNY to у lood, песеѕкату he broot and bulge very part of the body, 1s es EHE promoted by „this Dew discovery where iron is nee is Rich properly n0 i i ts digestion which ge А healt od out of your 1190, requires an а equate supp Mane Vitamin В. This new discov supplies this clement, imination to Yormal, regular elimina о emore poisons and ету eelis health ат L mote ре Vitamin B. This js the third purpose. QUICK GAINS or 10 10.25 POUNDS WITH NEW IRONIZED YEAST OW thousands of skinny, rundown men can say goodbye to bony angles and unsightly hollows that rob them of natural ‘attractiveness. For with this new easy 3-way treatment, thousands who never could gain before have put оп: pounds of solid, nor- mally good-looking flesh—in just a few weeks! Doctors now know that the real reason why many do not gain weight is that they don't get enough Vitamin B and iron in their daily food. Without these you may lack appetite and not get the most body-building good out of what you eat. Now scientists hare discovered that one of the richest sources of heaith-building Vitamin B is English ale yeast, By a new process the finest imported English ale yeast 15 now concentrated 7 times, making it 7 times more powerful. Then it is combined with 3 kinds of iron, pasteurized whole yeast and other valuable ingredients in little tablets called Ironized Yeast tablets. Tf you, too, are one of the many “skinny,” wornoul persons who need these vital elements to aid in building you up, get these new lronized Yeast tablets from your drurg!st at once. Day after day watch flat Chest develop and skinny limbs round out to normal attracliveness. Indigestion and constipation from the same source quickly vanish, skin clears to normal beauty. Soon you feel like an entirely different person, with new charm, new personality. Money-back guarantee No matter how skinny and rundown уои may he from lack of sufficient Vitamin B and iron, try these new “‘3-тау” Ironized Yeast tablets just a few weeks and watch the marvelous change, See 1f they don't aid in building you up, as they hare helped thousands. If you are not delighted with the results of the very first package, your money instantly refunded. Special FREE offer! To start thousands building up their health right away, we make this absolutely FREE offer. Purchase a package of Ironized Yeast tablets at once, cut out the seal on the box and mail it to us with a clipping of this paragraph. We will send you a fascinating new book on health, “New Facts About Your Body." Remember, results with the тегу first package—or money refunded. At all druggists. Ironized Yeast Co, Inc., Dept. 568, Atlanta, Ga. Posed by professional modela 137

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NEW Aleks Scoot 6 Miles READY! for i 1 Cent! Pay While You Ride with the EASY TERMS Money You Earn! К] к Here it is—at last! x —a MOTO SCOOT so simple, so safe a child can run it YET strong enough for a heavy man! Go anywhere—at 30 miles per hour—120 miles to gallon. No other like it! Easy Terms—pay as you ride with the money you can Chicago £ earn from lt! Shipped ready te ride. WRITE QUICK for color folder while this Special LOW ` PRICE, Speclal TERMS Offer lasts! (DEALERSI Write for available territoriesl) M qeu COMPANY Write us today ea DEPT. 8-285 CHICAGO for free folder HOME WORKSHOP FANS Get full advantage from your shop by buildihg that project you have long had in mind. No doubt you'll find it explained fully in the 1936 How-To-Build-It book which contains plans for making midget racers, Send auto trailers, furniture, .radios, games and toys. your 50c now for this big 148-page book—contains 500 pictures and plans alí in rotogravure. MODERN MECHANIX PUBLISHING CO. Fawcett Bldg. Greenwich, Conn. LEARN maos RADIO TELEVISION Color-Coded Extension Training fits you for better radio jobs— prepares for future television opportunities. Backed by 5000-watt Columbia Базе network broadcasting station, KMBC. Graduates quallfied to take Government operator's license exams, Lifetime employment service. All necessary equipment for “home Jaboratory'" experiments furnished; 90 illustrated lessons, 10 laboratory manuals. After “home training,” bus ticket to Kansas City for 4 weeks’ in- tensive tralning in laboratories. Get facts—wrlte for free catalog. MIDLAND TELEVISION, Inc., Power & Light Bldg., 108 W. 1441 St. Kansas City, Mo. Print YourOwn Cards, stationery, advertising, labels, paper, circulars, tags, etc. Savemoney and time, Sold direct from factory only. Junior Press, $5.90. — Job Press, $11, Power, $149. Do popular raised printing like en- graving with any of our presses. Print for Others. Big Profits Pays for itself in a short time. Easy rules sent. Write for free catalog of outfits and all details. ? The Kelsey Со. КӨ, Meriden, Conn. Heat Without Coal Remarkable, Cheap Invention, Burns Cheap Grade Diesel Oil Once Thrown Away as Use- less—Converts any Stove or Range to Fast, Clean Heat—Hotter, More Economical Than Coal or Wood—Banishes Wood Chopping and Ashes. Sent on 30 Days" Free Trial. Over 10,000 already in use. Rise on freezing, wintry mornings in enug, comfortable room, toast-warm. Cook our mesls without drudgery end dirt of ashes, coal, wood. luxury no longer comes high. Runs on pennies. Safe. Temperature Controlled. Many wonderful automatic fea- tures. Sent on 30 days’ trial at our risk, Agents Wanted— we will select parties in each locality to receive one FREE to install in their own homes and demonstrate. Make up to $60 weekly and more booking orders, Selling Fast. Write at once—peàk of season now—no time to lose. Name and address on one cent postcard will do, Listed' as approved by il Board of Fire Underwriters, Brigham Oil Burner Co. ept. 2823-H, St. Louis, Mo, 138 Build Bellanca "Gas" Plane [Contimued from page 85] line of thrust. Then tie a piece of very strong cord to the tail wheel fork (a piece of linen rib cord is ideal for this). Lay out approximately fifty feet of the cord along the path you expect to take. Warm up the engine, grasp the cord, and let her go. Follow it and feed the cord to it as fast as you can. At the first sign of any faulty adjustment, "throttle down" on the cord and force it to land. Keep her well under control for the first few hops and only allow about a five foot altitude. Then, increase the length of flights and the alti- tude till it shows no bad adjustment signs. You are then ready for a free flight. For this you'll obviously need an extremely large field such as an airport, and something, such as a photo timer, or a definite amount of gas, to limit the length of flights. A few words of advice: Keep the stabilizer angle as near zero as pos- sible. Use the batteries for balancing and change the stabilizer setting only for different winds and power or other temporary changes. . When anything is broken on the ship, repair it before making any more flights. One part in slight need of repair may cause serious damage in what would ordinarily be a minor crack-up. Get in as much flying time as possible. This will increase your success tremendously. Max- well Bassett, the "father" of gas model flying and one of the most consistent contest winners, credits a large part of his success to experience gained while flying his models. Happy Landings! All-Purpose Camera Stand [Continued from page 112] nails assemble the stem and cut a triangular block of wood l-inch thick and fit it into the bottom end, then glue and nail this in place, countersinking and filing in all nail heads. When the glue has set round off the coruers, sand sniooth and using a sharp knife and a chisel recess a place, l-inch from the top (open end) 3-inches long, Y4-inch wide and yy-inch deep, in one face of the stem. Now obtain a piece of brass 3-inches long, 14-inch wide and -inch thick and drill a X-inch hole in the center. Solder a 14-inch nut over this hole, place the metal piece in the recess in the stem and cut out for the nut so that the metal strip will be flush with the face of the stem. The triangular center piece is of similar stock 214 -inches on each side and 24-inches long. After cutting this piece out on the circular saw, round a 2-inch section at one end to snugly fit into a 3-inch length of l-inch pipe which is threaded on one end. Taper the wood to form a blending intersection with the pipe using a wood rasp for this purpose. Remove the pipe and rout out a strip, 44-inch wide 14-inch deen, down the center of one face of the center-piece, drill а 22-inch length of V4 by %-inch strap iron, every 2-inches with a #,-inch drill and countersink these holes to receive ` flat head wood screws. Drill through the pipe also to match the end hole in the metal then replace the pipe and insert the wood screws as shown, А The legs come next. Six of these are required each measuring 134 by 76 by 28-inches. Using a shaper or a drawknife, shape the six pieces into a half round section leaving a rectangular section at the top 4-inches long. Now, using a l-inch circular cutter in the circular saw, rout out a groove %4-inch deep in each of the six pieces and sand these pieces smooth. Cut three 4-inch lengths of 1-inch dowel and glue these into the round grooves, matching Accept No Substitutes! Always Insist on the Advertised Brand!

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these between two of the leg pieces. When the glue bas set, drive a few finishing nails through the assembly to secure the joint. . Drill each of the legs with a -inch hole and then cut three 12-inch lengths of l-inch dowel for the foot pieces. Rubber cane tips may be used on the ends of these or, if desired, rubber head tacks may be used. From bakelite or fiber j;-inch thick, such as old radio panel, cut three pieces 1:4 -іпсһеѕ wide and 11-іпсһеѕ long and round the ends with a file. The metal height adjustment clamp is made next. From brass or aluminum cut a strip 34-inch wide and about 10-inches long and bend it around the triangular stem. Now place the metal strip in the recess cut for it, with the nut inside, and drill the band and the strip to receive the wood screws. Exercise care to get the locations of the screws absolutely correct so that they will not come through the inside of the stem. Obtain а 14-inch wing bolt at a hard- ware store to form the adjustment screw. The metal stem clips are of L$-inch aluminum or brass 34 inch wide and about 414-inches long, bent around the stem piece and then at right angles to fit the leg pieces, Three of these pieces are necessary and are assembled to the leg pieces as shown with 4j&s-inch bolts and wing nuts. This assembly should clamp around thé stem tightly, The clips to hold the foot pieces securely are of brass or aluminum 34-inch wide 14-inch thick and about 8-inches long, Three of these are required and the ends are rounded and drilled ps-inch for bolts and wing ‘nuts to be inserted. The clamps for the bottom‘of the stem are similar to the leg clamps, but are longer and these are assembled to the hakelite pieces with wing nuts and bolts. Insert round head stove bolts through the holes in the center of the leg pieces and bakelite strips between the leg halves, slipping a rivet over the bolt to retain the nut. Now slide the stem through the clamps and tighten the wing nuts, insert the triangular center piece inside the stem and tighten the wing bolt to hold it in place. The tripod head is made last. The tilt top is of wood, 6-inches wide, 1-inch thick and 9-inches long, rounded off at the corners, Drill this piece on the center line to receive the thumb screw of your camera. The panoramic base is of similar stock 6%4-inches long. Drill this piece through its width with a %-inch drill, 2-inches from the end. Drill a 1-inch pipe floor flange and tap the hole for a lock screw such as can be obtained from an old “С” clamp. Wood screws hold the flange to the center of the base piece. Two small brass hinges are used to tilt the top. Obtain two brass desk hinges about 7-inches long and screw these to the top as shown. Using washers on each side of the slots in the desk hinges, insert а %-inch bolt, 6% or 7-inches long and add a wing nut. Now. screw the head assembly to the pipe in the center piece to complete its construction. The camera tripod can be enhanced to a con- siderable extent by applying a coat of natural stain, followed by a coat of varnish, to all wooden parts. Double Unit Floodlight Case [Continued from page 132] strips of wood in the back, over the rear reflector, the side reflectors can be securely tacked into place. | After completing one half of the case, by ш- stalling two porcelain cleat type sockets and wir- ing them to a suitable rubber covered fixture cord, the remaining half of the case is duplicated in the same manner, Before completing the case, by painting with a good grade of enamel and fitting with a carrying handle and brass hooks for holding the case in- tact, provision for hanging the diffusion screens must be made. The screens are nothing more than pieces of thin silk, hemmed at each end to per- mit the insertion of metal rods for drawing out the wrinkles in the cloth. The upper rods are suspended on hooks made from two No. 127 film spools, Remove the metal disc from one end of each spool and trim down the dise on the opposite ends of the spools to form a hook. Next, in the upper [Continued on page 140] When Answering Advertisements Please Mention August Modern Mechanix desire men to Jearn Elec: О. S. Manufacturers S92 om Pes d X] 1" actirat production conditions in the laboratories Of the School of Au enn ule derate training Fee. Accepted applicants will Þe аа y to pass rigid test and assisted in securing Are Welding presents one of the outstanding op. portunities for steady income and future success. Welding is growing r " rapidly, replacing large and intricate n ineerin castings, rivets, nuts, bolts, screws. g it ds commonly used in assembling " PONE В oists, ridges, ` struct steel work, ete. No limit to the application of welding to induce try, increasing durability and reducing manufacturing costs. There K a decided shortage of properly trained Welding Operators, ` Technicians. duis jding Engineers. Why be content with ordinary 8 l S ow pay when in i become a trained Specialist in Welding? E "C ALL WA LI IK E £ tt CHOAL of GEHAL cf ENGINEERING MM-837 Broadway and E. State, Milwaukee, Wis, ее igation sen ree Booklet ''The D. i industry and Its Outstanding Opportunities.” awn of Gisentio Also tell me how tọ become a Welding Operator (3 mo.).._. Refrigeration and Air Condt. Welding Technician (6 mo... tloning Technician (8 mo.).. Welding Engineer (1 yr).... Radilo and Television Electrical Englneer Service Man (6 по.)----- ----- В. S. Degree (4 yrs.)--.. =-~ Commercial Radio Engineer (1 yr.) Student Loan Plan....--...- Earn Part Expense Plan....... Powertul—Aecurate—Economlical —Practical— Adjustable Shooting Force—Amazing Maximum V Velocity—cal. 177 or 22and BB—ForTargetand Small me—the only Genuine Compressed Ale Plato! on the market—Single Shot with Bolt Action—Hammer Fire. Heic Trigger- Safety, Price $7.50, Also 177 and Z Single Shot Alr Rifle $7.50.—Single Shot BB Air Rifle $8.00—25 Shot BB Repeater Air Rifle $7.50—at Dealer or Direct—No license required—Safe for Indoor цве. FULL DETAILS—TARGETS—PREE—WAITE TODAY. Benjamin Air Rifle Co., 631 N. Broadway. St. Louls, Mo. n = ON Ty ТТА This REAL meee заррага no - tical Electricity in ‘your own fome ‘Shop. No EQU | PME NT previous experience or advanced education is necessary. опеу back if not satisfied. RIGHT YOUR for full inf ti thi " EASY WAY 10 BUTTER JOBS AND Good PAY: ОМУМ НОМЕ Lifetime FREE Employment Service to Gradaates. eT This FREE Book W rUTE, Dest. AT. 7 K Tells YOU HOW, 139

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LOOK TWICE Dirty oil in your car engine can be just as expensive as too little oil—and that’s why wise car owners always take two looks at the oil measuring stick. Black, tarry looking oil means that your en- gine is no longer getting filter protection and needs a new PUROLATOR. A genuine PUROLATOR keeps your oil clean and clear in color for thousands of miles. It keeps the dirt, grit, hard carbons and small metal particles that get into the crankcase from scoring and damaging valves, bearings and cyl- inder walls. But, don’t neglect your filter... in time it must be renewed. Your garage or service station man can attend to this in a few minutes. If your car is not already PURO- LATOR equipped, he can take care of that, too. There is a PUROLATOR for every make of car. Motor Improvements Inc., Newark, N. J., makers of PUROLATOR, the oil filter on your motor car, Licensed under Sweetland Patents. Spiatin (ac OFFERS YOU GREAT FUTURE Demand for trained aircraftsmen in Southern California lants is increasing and already exceeds supply. Curtiss- right Technical Institute, Aviation's foremost and oldest School, is located in heart of this activity and specializes in Sheet Metal, Master Mechanics and Aero Engineering. (No flying involved.) Graduates are obtaining immediate employ- ment. Write for details NOW. Curtiss-Wright Technical Institute, Glendale, Los Angeles, Cal. Depl. MM-8, №) Earn Cash сг Home! Raise giant patented mushrooms! We supply materials and instruct with pictures, Our 25 Coast-to-Coast branches buy all crops. Big FREE book, photos tell if your cellar, shed, barn, ete., suitable. Write today. (Established 190$.) UNITED MUSHROOM COMPANY 3648 Lincoln Ave., Dept. 317, Chicago dis 2 Turn Your Skill /aro DOLLARS | Make extra money іп spare or full time with motor- driven woodworking tools, Opportunities in every com- munity await alert crafts- men. Hundreds of men all over the country are cashing in today. Find out how they are doing it. Send only 10c for bir new book, crammed with money-making plans, ideas, drawings, illustrations —.show- ing how others have increased in- come and become independent, Address Dept. №837. Delta Mfg Co. ого wis: 140 Scan The Sky With Telescope [Continued from page 79] The tool is rigidly fastened to the table G. The machine is driven by one-fourth horse-power electric motor R. А . These are all the features needed for simple grinding. F is a block of wood which is fastened to the mirror. The machine should be so lined up that each stroke of the mirror is equal to one- third the diameter of the tool. The pulleys P and P' are used in spot grinding, which is in itself an advanced process. The pulley P is rotated by the shaft O when it is centered by being moved along the slot I. A belt between it and the pulley P' drives the latter at whatever speed is desired. Spot grinding, however, is a technical operation which should not be at- tempted by the beginner. The bearings, gears and shafts used in this machine may be adapted from old automobile or washing machine parts, and stray bits of old machinery, or they can be purchased from a re- liable gear company. There are a few general hints which apply both to machine and hand grinding. First and most important, be clean. Don’t be sloppy. The dirty workman may expect nothing but disappointment. Second, don't take too long a stroke. liable to result in a turned edge. Third, don't allow the mirror to be subjected to too great changes in temperature. For this reason, a basement is the best place to work. Always test your mirror at a constant tempera- ture. Wait thirty minutes after grinding before testing, to allow the mirror to cool. Fourth, in roughing out the center of the curve by hand, grind slightly off center so that the edge of the tool will pass over the center of the mirror. Be sure to test often while using this technique, as the work progresses rapidly. Fifth, it is a good plan to finish the grinding with a little optical emory mixed with precipi- tated chalk. The chalk will prevent sticking. This article has described the rough and fine grinding. Your flat piece of glass has now become concave. It should be close to the desired focal length. It must now be polished, silvered, and mounted. These steps will be taken up in the next two articles. Double Unit Floodlight Case [Continued from page 139] corners of the case sections, drill holes large enough to permit the insertion of the wood dowel sections of the film spools. Make these holes sufficiently large so that the dowels will slide in and out freely. 5 The slots in the dowels, through which the film was origi- nally threaded, are used to advantage since they provide a means whereby the hooks are free to move in and out without accidentally falling out and becoming lost. Slide the dowels into the holes so that the slots are in a horizontal position then drive small escutcheon tacks through the side of ‘case to provide a stop for the hooks. Installed, they permit the diffusion screen to be hung in position in a moment, When transporting the reflector, the hooks are pushed flush with the edges of the case and the silk screens rolled up and placed inside along with the fixture cords, This is Accept No Substitutes! Always Insist on the Advertised Brand!

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Conditioning Your Sail Boat [Continued on page 137] white lead. Lay a flannel patch over this, then apply another coat of glue and place the patch in position and fasten down with copper tacks. The soft lead can be beaten down around the edges and into odd corners to blend in with the planking contour. Make sure that the patch is large enough so that the tacks enter firm wood surrounding the faulty spot. Seams, cracks and dents above the waterline should be filled with plastic wood or a mixture of white lead and putty. Whatever is used, mix a little of the topside paint with it so that if the regular finish wears off such puttying will not be apparent. The condition of the painted surfaces will govern the treatment necessary. Removing paint is a hard, tedious job no matter how you do it. If the surface is merely dulled, rub with steel wool; if cracked sand down well, but if scaled loose in patches scrape or burn off the old paint. A professional can do wonders with a blow torch and putty knife and you can master the knack fairly easily for it is the quickest way to remove paint. The torch must work perfectly and the day be without wind. The alternative is to use a small three cornered boat scraper which must be sharpened constantly with a file to work easily. A painted surface once scraped off must be refinished slowly. Not by heavy paint, but by at least three coats, the first well thinned with turpentine, the second thicker and the final one as it came from the can. Varnish is more a matter: of adhesion to the wood than of penetration and can go on thicker. Different paints require dif- ferent treatments and there is no excuse for a poor job as marine paint makers issue free in- formative literature for amateur painters. Be- fore you commence fitting out decide to use one reputable firm’s paint, write them for literature and then follow instructions to the letter rather than listen to well meaning friends. Wash canvas decks and covered boats and canoes with strong soap powder or paint cleaner to remove loose color, oil and dirt. Do not re- move paint unless absolutely necessary. Spend plenty of time preparing for the final painting. Scale off loose paint and try :o blend surround- ing surfaces into these by sanding well. Paint such spots first with several coats to build them up to the surrounding level. A very thin mixture of putty and white lead colored with paint to be used should be putty knifed into cracks and depressions after sanding. Tears and rents respond to the hard glue treat- ment. Apply the glue sparingly and sand after- wards so that spots are not noticeable after final treatment. Use thinned deck paint or it will check when the canvas gives and takes with walking. Only a regular marine paint developed for CANVAS decks will withstand the give and take of the fabric. Ordinary household porch [Continued on page 150] . I Positlon This Р MACHINISTS’ Home-Study Course E o helps men get ahead Newly üssembled—specially priced—these five recent books give you the practical facts on modern machines, up-to-date methods you need to advance in machine shop work. Take advantage of the other man’s experience as found in books, to solve your problems, increase your efficiency, with the new Library of Modern Machine Shop Practice 5 volumes--2000: pages—1600 Illustrations (A combined home-study course. and reference library) This library of machine shop practice was written for practica] men, lt glves you the- best methods for every kind of machine shop. work. It deals fully with lathes, drills, and other machine tools and their operation, automatic screw: machines, speeds and feeds, gear design and production, punch and die work, meta! finishing, ete., etc. Plainly written—completely illustrated—the best Kind of lielp. to the machine-shop man who: wants to advance himself, No money down-special price—easy payments Otro DIL ce REE EXAMINATION COUPON McGRAW-HILL BOOK CO., Inc., 330 W. 42nd St., NEW YORK, N. Y. І Send me for 10 days’ free examination the Library of MODERN MACHINE SHOP PRACTICE. И satisfactory I will send $1.50 in 10 days and $3 monthly until the special price of $16.50 із paid. Jf not wanted, I will return the books postpaid, (To In- Sure prompt shipment write plainly and fill in all lines.) Name e —————— | Company -—A es ee БНА ee ee eee ee ee ee emm ee mm HANDE: TOOL OF 1001 USES Grinds - Drills - Cuts - Polishes Carves - Routs - Saws - Sands Sharpens - Engraves A whole shop full of tools in one for work on all met- als, alloys, bone, resins, glass, stone, wood, etc. Uses 200 accessories. Saves hours of КРМ tedious work. 13,000 г.р. m. Socket ACor DC, 110 volts. $10.75 and up, postpaid. 3 Accessories Free. DE LUXE MODEL For constant service, nothing com- pares with this easy-to-handle pro- duction tool. Saves time and labor. Fastest, smoothest, most powerful tool for itstypeand weight. 25,000 т.р.т, $18.50 postpaid, 6 Accessories Free. Geta Demonstration at Your Dealer’s or Order Either Model on 10-Days Money- Back Trial. Catalog Free, CRAFTSMAN'S PROJECT BOOK "Pleasure and Profit with a Handee" Easy working plans for making many . interesting and unusual projects, 25c stamps or coin. Chicago Wheel & Mfg. Co, 2102 Vi, Monroe St. Dept. н. Ù Send Catalog О Project Book 1 ns D Send C. O. D. | MMI-8 10.75 Model D De Luxe Model Name cecccussvsucceves eresoosae фоне essoososons When Answering Advertisements Please Mention August Modern Mechanix 141

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BROADCAST the house—-imject wise C redio stars, “Ben Bernie" gUached in a jiffy withoul Not a toy. Put on your own pro- club af- grams at home, parties, faim, etc. to operate. i ms and Listen to Music ogra -pocket radio civ vou arecin the ecu Bear halen, jn bed он 3nd EVERYWMERE. Size of $ you =| tone. Range. 20 mii te rectifer ani ‘pens Li $1.05. Mot & tov. Price Postpaid, Pir with the First again! fous World, Mike, Wide Radios, then the RADIO TRANSMITTER that sends out only $1.00, plus 40с postage. Note thes ж Can bi ж Not a Mike, bul a com, ж Complete with Key, ж Plugs in to any А tactice crooning, or в “Rudy Valee." World. Mike Made especially for home- use, Barrels of fun! 425c GET POCKET RA ports Everywhere ifnl clear tone while you walk! age. yi rates егес у ЕН No static ar noise, Ме crystals, 10 ic price y then the, All Dollar l'ocket "Radio. icked on а suitable Mike, but: plete Broa In Kit Form -DC circult your voice on programs coming through your own Tadie set—make announcements [roi any part of racks, Josh and mystify friends. Imitete singing, radio acting, et. Do в DELUXE MIK substantial, all. Practise Га] 2 broadcast. E, programs. ete. ihrü vour own radio, Reproduces valeo inl Jaud. clear tene with. out distortion. Regu Br omen ae Е t Lools. Easy You Go—toud fone The amazing midcel ent of а radio wherever ea radio, then the Ware Wold (Gy all the entertaiumi sona hoat, ANYWHERE S Ginareuse eau titul gations, New tesien, tat and NOW а geny inessages by wireless, for е sensational Features: Radio Recelver dcasting Set 2 oscillating tubes ж Us Completo Transmitter, $1.00 plus 106 po: st. Tubes (uses 2) Each 505 A Private Elecmic Telegraph set for only 15e: Use it ак в practice set ог nd тезкасен to friends — (sending вла receiving), Ñ Learn he code ea: > Ty end quickly. Be base, plete with eawern Line 4 Electricity Add fne fur G4 pace Legh written specially, for now олія Супа» vos. motors. ra. dios; teleiraph yay WATER WINGS MA Wawr Wings impart hr o at one.” Papert Swimmers’ use eem Cts gover Teng distances: 40 Swim, Ip deep water carried in tne pocket and blown un Shel carrito nes aaah Smart, snappy. Just what every real boy 15 wearin. Cool and confortar) ——— with black ollcloth pe: p Blue anchor on fron Sweat Land, Ў 4 and prase bution Закон price, 256 Р ca, sup- erjor quality duck, white erl- Тоат cep. gold ford: brate ^ pe EU ALIVE PET WATCH IT CHANGE COLOR! Gel one of these mast wonderful of au i О С enam 3 fear onc on the lape) of your совр іч a curiosity, PSOE EUER EE а i e CERE MEE И, an Pepler : Bed wo any tiaras in COR NE т Antec sve arrival and five dels Distributor Intensifie The auto distributor Intensifier wilt Give Sau mare IPREN wit ese и TN maue ib mor Tun оС and better. Just uy this Intensifier on vour esr ‘end eee {or VAT ee difference makes. Can be slinned 4 Onto “the distributor Pr niri ied Onde without tect nou confuse TUN, spark ели Bakelite cu Only ene needed Гог or E. Vlinder rar. Distributor басе гог 256 Win Prize Contests Tells the best methods and ies for winning some of Prize contesta which are ann almost dally. ^ People make tidy sums of money by sobving the var lous contesta. Methods and princl. have been selected d hy the wii 9 loc. gc Novelty Catalog. 3C Tomorrow? What will in bring, for What will haps Ye Mitt M, PP оне раза Ta TELLING CARD И Gn deck and iriends for mica around will wont to gei in on the fun. At parties, ratherings. evenings, ele.. evervane wil want vou to Eu Tt. fascinates them. Yet fnere le nothing difficult lo telling the fors tunes-.cvery card ia пізіпіу marked with its mearink And the connection between the ants hecomces at once apparent. Complele rectiong with "ach о @rige She por deck. Daluxe deck with 53 Ivory finished атая. 750. nostoale. BIG ENTERTAINER 600 ORTUNE 13 Fiirtations, 10 "Picture, ев. 37 Amusing riments, "Deaf And DünibAlphabet. Shadowzraphv, Fortune Tel ler! Fortunes. with Cards. Crystal; Tea Cup. eic., Hypnotism, Ventriloauism. Gut-ouls” for Greiner, Chess, Dominoes, Fox ant Coste. len Morris. Anagrams, са Фо © Ine wie: ater only LOS ALL WA WORLD WIDE &et poli anywher eign aad dome: with remarkable valime an «Rach ket complete вый tuhe. hone. watiery or aerial, T R V'SET $1.55 reception: comprete Bit Wired, roxy 10 operate, ELECTRIC TWO TUBE. lon s Sate Noes rice: v cali This sha Fagio n DUCIT aN itis DOs! "ме lg кер reventiop SED te et 25 mites or à m ror up lo 100 | miles under good ron- ЕН AN you need an aerial & ear Б phone.” Comnleicle Assembled & wired n. * CANS whisker. ete._ Reception ruaranterd. 28€ WIND LIGHTER LIGHTS IN ANY WEATHER Wind Lighter now bel lower th. v br attached, to waun Aulomatie Wind Liahter, -23c Finis. 3 for VOe. Hill Bill Ban CE. 4 5 РІЕСЕЅ Consists of Е Harmon- 1 Warbier. 2 atene: d Karoo. 1 ienis, at home m EU ER Y- WHERE, "And pov. oh мор can you go lo town! Ger nve fellows Bnd Tet "er e se 156 X у Band Ser ЭВ CRYSTAL j GAZING BALLS А Look Into The Future Guaranteed perfeet in каре. A стукат Of noL Jess than 2 inches ваші te used, but the aerer crystals are семи: a Jürver Vision is seen, censeaventy bele ter results are chuined, Geta erysual—ure tt" constantly and Ва jt vH accomplish, 10 тау ne: ihlantiy glazed, t colors. snap. uthause Novelty 236. China Той Rall your own and save попсу. Beller and quick оз more than Faut Seat, userul, handy. Pack eb size: weighs d ounce, Nickel pla Мор be noticed. vet when the victim lights up ‘and takes m Jew “pufa. ће, cigarette thruws 9f «n awful Joke “for "moochers. sunk t A rand E Siinkers tüc LUMINOUS PAINT. when applied toan Bhiertemitsraysof white lieht render. BEng it vivibre In the dark, The darker the ИВ пе brighter it shines. Simple to i^e you can doit! Апр1у some to the Aint of your watch so vou cim tel] time at 4 nicht. Paint ОЛ switches Any eversihing wiln И. Smal! Bottle. 38c, edium sire 506. Larae size 51-00 postpaid. Funniest novelty ever Invented: Fits the Anger like a ring, but concealed In palm Is Ine TICK- LER The Muster. or tichler, can. tang a clockwork, mechanism that is wound up. Whenever |t Ig touched, the mochanism is re- leased. piving the victima shock. Every-time you shake hands. yaur friend “will Kel a violent shock. Touch them on the b, inem" Jump. They will Rit tev sit on, It. Under a shes! A mouse. Use” it an a “tle-tac window. Hundrede of “uses: Containa everything needed to lar е face to represent any chai acter: the. Beautiful Heroine,” the vicious Villain. the Charming Bea fhe Comic Old Lady. the Clown. | The , the, Negro Minatrel and. Many others. Just a few touchem expression 18 entirely changed so oue mast minae Your Amatwar'a Жа Resurrection Plant №”. lest curisty. Pare in wat er. plant opens un and starus er io sleep unul ve in w lasts almost forever. What a bargain! " genuine "Field. 12е Sn the power mage nifeation-” Cener Diece uurek ane бани. 4 Permita fully une апреле twa Syed Vitión thae Hlos ета Scobe sad clarity. Sweet fer nature bum. ay. Maing. Sparu and E mimoa oter, dy ompieis wi eard, backed -in box. nalure study, Sports. looking at ine mann. Converted into Solar telescope by ys. Bluse so von can sec DB Shot 25 cente 07 Ano EM Рал. MOVING PICTUOE POOLTOON buna ШВАМ Safety Film fectric Movie Machine for only 34 clear pictures about 14 x 19 ches in sizo. Just Insert the film. turn the frank pnd watch the pictures as long as vow Tiko! Uses 2 where. Brecht red enamel purine SxJx9 inche: Feady to uae. LOC Aim, choice of Felix : Чей. Tom MIN, etc. ABe KACH. пісі sea! large size, тусч, wiih able for traminiz nd nne ef ihesen your friend md h Асет Liars License Death Certificate Arrest rant, Collece Diploma Dog License Divorce, Cert We Cr Gold Mine моек Cer. Aw Pilots “License г С; BBeeuercer Diploma Price 20c wach license. Any 3 lor 255. CIGAR LIGHTERS 4 Four uniaye lighters at re low brice of 13c each. Full sized penrli&lighter: kev; Dullet: ind nne which [oaks Marriage, Certificate Lae опет Cn Quartermaster - Navy Bir jumbo size, with a flay! Like the U. Mernment men ui Sterling Sliver, $1.00. 44 м. Aing, $1.75. INSERT A COIN AND OU This sena! al to lave and think qf havi nickel or dime FREE! в nen Var, al) wranned ш you'll find that t fills up w пк this handy dropped 3—01 h money bank cannat he ho: This slot-machine «end $1.00 for TA c опе way to get lt will include the bank free keked door so you can open, Temove in chocolate. On the front is a siot (o drop window showing bars, add. wit If vou bury, we'll diy catal EXTRA! oir объе по Made of slicel metal with Te, Tied, yellow and green. bil (81.00) for the 70 bars und get the ban T COMES A DELICIOUS. CHOCOLATE BAR Thrift Bank and Slot Machine hew-lype bank to hold—without any is Yours—yours: са: Just bank nrownd and 2: mt comes a eliocolate leave (he hank around the house and while you're zone. HOW TO GET YOUR BANK FREE! uzht. There Is Just acolate bars amd w- lar oney nnd refill with coin in, and о glass end a dollar k FREE. hout ros, vur big 900 illustration THRIFT VAULT suto lock nA Vault ust dial the three and open tne any measures abouL 3x2 in. weti та keen Your money, jewelry, etc. Constructed of he: insi [ bans. ULT Өлу 506 porte. ти phearanre wa € only mode of wel. ded steel. and slightly larter. Hacked in a box, ‘with complete Ago? YE i bank e bank. me Gant i; кода. ann Eve delivers a torrine KO flouring Me onbo- ent! Friende. печат And relatives pur money in Sour bank (ust ip хее th Titheeranhed och and hey. Hun a non wip cemoe $1.25 BlankCartridgePistol ams Two of the latest, newest models naw ont—60e and $1.00, Гамегп- ed after the latest Буре of revolver. Where. Handy protection . against | burg! wamps and dogs, Fine for 4th of July, Years, slage work, starting pistol, ete. Shoota 22 caliber blank cartridges obtainable every- lars. New etc. i Looks Like A rongly con- structe: nt. c ish. Rot риа. je blank Fires blanke опчу: 3 Looks exactly ке ox: i Bens ive automatir, $ by expr 1 Prieo $5.30. Usch soe: Fac ner 100. Large 4719906 ле lone 07 Io сету manv umes. Don't utinstheva ^ (or any hi һе master Keys Will ть ordinary door lacks. — Five ent kevs for varlaus. турга af locus. Will save Their com if you on, IY use them ance, bur veu | eani find thom ко handy that you'll saves SMASTER KEYS Price 25€ (c ТЕСТО: ashing rubies er ‘ет rkte eut of the, a to briag good The. wearer, Only 23c. Marine - Army Ring rrounded by the American Каз, spe "d ize, Silver Finish, 25c Your eleture" or уои S Picluve slips. пеш top frante.” making E thal 157 surar КЛУ smart luoking. Snan- Inest, оне Pine ot! w sells for $1 w York. Beautiful ai Ver Appearance $ TOL “ohacea PHOTO Ri nolo Tio Holder, Silver Fini photo Pendant Fob, Silver or Gold Fin, 38e m). racel з все" BOC ndi Рори, млге Cus made of rub) fates dive el and then placed nn à hir. couch. кем. ie. When the victim Enmusnectinicle elts upon the cushion. fL gives | Forth "nai thateanbe beter k. under the bed or anywhere. Lots п fooling tencher. policeman or friend THE WONDERFUL VENTRILO а little instrnmenf. fita in the mouth out of sight, used wlth nbove fo eun цяе it. full course on Ventriloqu the ¥entrilo. Sent позу karese. Always ready for Oniy 10 ¢ ppd- Drass band ail i» onectne higzest sensa- Uan in the "musical world years, Just insert A roi and Tw Whie yau blow, Nothing coul Minds af melodies, Th Mr æ last few the handie Ve “simpler, Saved төг ноте on roti, 9. ie. Lazy Bones, the’ Range. Each extra Re!monica wilh. t “ADDRESS ALL ORDERS FOR JOHN ever foils, A complete hook w SON SMITH & CO. г Bird Cults, etc. An th ism together with l for only.... vone ‚ 10c New Vest Pocket alu NOE Dues) chine, Ten Simie ant пиеса far мент and ted of toel и durabilitvand Thats а ие nd l;zbi, е? ол. n vest Docket E Constr AMIE. mona. told or any ery. ete. y thing, Live- n ck а extra cual easily by do. nt tiis for other neante, Every r£ eei timet Fasy touse. есь light socket i ready to write, PENCIL, compiere itr NLY and ELECTRITE "h $1250 C N THIS PAGE TO brings you our big, jumbo catalog of amazing novelties from С all over the world! xJoke Goods ж Time Savers ж Unusual Books x Puzzles ж Magic X Fi eworks д Cameras х Games gh Curious Seeds ж Live Animals к Radios ж Jewelry, etc, Things you never knew existed! Delure edition with permunent cloth binding 25¢ te construction Has the cartridges to be loaded im a second. Medium sile, (Cowboy Ту; lay EXPRE ms, injormation, Ва flashy nickel fine barrel that allows d wi size $1.00. Blank Čar- 60c рег 100. Holster go» 506. SHIPPED $, NOT PREPAID. Ting In many an awhwaldens Great fun "sticking ub" vour wis They squirm and protest Pull Lhe Wigrer and 1 ахй 'y thecasy rhythm Seinaling grae of wicht. Fred Astire Tap dance In ONT Y 8 vanes mph ied course by Prof. Wilson. Nó hiltty neede 310 Illustrations loveit.Friendsadore Садзе isnot ОЕ and ener: but Is also a еда ho E gma and giving a Ергіпру тесу gf Btness to the whole hady. Pras Raton shuamess Nature's way nó PIS, drucsor dieting, eade: s Sav; а peneki. Think too Ц бы ого accornp. Ре 25e Бо, ЕСИ mired —alwavs p. Ц патера Mi ПЕН СААЯ E E PRIOR “sien The musin state et lays Е want to becomea perfect down, douhle, knee throw. learn 10 protect yourself un- tow to ее Тот poise and control: d Reverse Turns. tre feverse “Wave, ‘tne Тате 7 заре to music. Wall: aei z [i Fari ehotzes tie Continental М анана DON'T BEJ ISAURA зос TreJananese art of self defense" алела them.” Deale fully, Shins Mies ромео 8 wriat Torin, ‘badd Пора. defende Мане revolves. гареп ах slick ваги, defense against knie. "one “hang throat rip. defense” eransi, two asan! " he throw, ‘secret Wei Tall Circumstances with tures Wesbons. "Fear" nà mam kuns o Ив Ae af du Jusu On dollars. AII about Tacer Paris. cours, transmis. sions. dirt" track rac. ers, track regula. RINE at low cost. Inccearing’ spiced: ste. etc. “Cram: med ^4 jammed Nimprove your donee steps, FC Solini. owe To walk 10 miea, ANB e Fed Ta eel fo The famous Kiss dance the Mor Lar am the College RMU ti e New "methods, af pltack ana sense are И ‘sus EO MEER ARMS ЧЕН Weadloch. holding a "mam, tom Wnockdwl) ^ nerve and numerous o hers. 3 4 derent The one уі Tipns. ‘blueprints ans, А ui DD full ef infornratron Dinos & ‘blueprints. , al] ready io on ine front. of your Swealer ог {аске or hang them in your Easy. the leet ‘design aard "Good Luck Emblem. F sAaeugiball, засва, Bov Seon or Linra. ‘Posteald "286 JAPANESE ROSE BUSHES Verpetual Rose Bush seeds Dtm. o. duce ane af the most amazing var feries “ot the rose ever developed. Mav ope fawn either indoora oF Butdoors and blooms ше first vear Eie hanea. "and when fears old, ihc bush 15 a mans 9 resev. ^ Tired Shades whites ари baa "tri meone WE GUARANTEE IF TO PRODUCE SPLENDID FULL Size HOES: Maona regular Sex Indicalor 12:523 by she «sx of ени. handwriting. eic. etc. 10c

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A. C. GENERATORS PRACTICAL, changes for automobile generators. See our advertisement at bottom of page 125. Autopower. ADVERTISING AGENCIES LEARN Advertising quickly at home. Easy practical plan. No text books. Common school education sufficient. In- teresting booklet and requirements free, Page-Davis School of Advertising, 3601 Michigan Avenue, Dept. 204C, Chicago. — S 00 a ao ADVERTISE: Get mail-order business, agents. Free assistance. Free Ad- Guide of newspaper, magazine, circula- tions, rates, mailing-lists. Chicago Ad- vertising Agency, 22 West Jackson, Chicago. 33 WORDS, 25 magazines, three months $2.00. Goodall Agency, 742 Market, San Francisco. FREE NEW advertisers rate guide. Brown Advertising Agency, 140 South Dearhorn. Chicago. AGENTS WANTED NEED Money Quick? Here's a genu- jne opportunity to make up to $42.50 in a week. Operate grocery business from your own home. Supply friends, neighbors, others. I send complete outfit on 30-day trial; no money risk. Details free. Albert Mills, 2349 Mon- mouth, Cincinnati, Ohio. AGENTS: Smash go prices. Santos Coffee 12c lb. 4-oz. Vanilla 8/4c. Razor Blades 10 for 812c. 100 Sticks Chew- ing Gum 12e. Christmas Cards, 21 in box, 14c. 150 other bargains, Premiums. Experience Unnecessary. Carnation Co., MN, St. Louis, Mo. BIG MONEY and Fast Sales. Every owner buys Gold Initials for his auto. You charge $1.50; make $1.45. Ten orders daily easy. Write for particu- lars and free sample. American Mono- gram Company, Dept. 11, Dunellen, New Jersey. DOLLARS in savings and sales from semi-diesel conversion units for all auto, other gas engines, factory built. Low as $5. Guaranteed on trial plan. For details write Dies-L-Gas Sales, 420 Market, San Francisco. BIG Money Applying Gold Initials on Automobiles. Easiest thing today. Free Samples. Also, Sideline Salesmen for Name Plates and Tire Cover Transfers. "Ralco", 1084 Washington, Boston, Mass. : PROFIT with new products. Make, sell, repeat. Analysis. Research, Guaranteed formulas. Biggest catalog free. Special prices, leads. Gibson Laboratory, Chemists, CE-1142 Sunny- side, Chicago. GOLD Reflecting Window Sign Let- ters. Penny Each. Large Sizes. Easily Applied. New Styles. Absolutely Beautiful. Free Samples, Atlas Sign Works, 7941.G Halsted, Chicago, ll). AGENTS-—Erco Hand Cleaner will build you a steady repeat business. Details on request. Erion Manufactur- ing Company, 32 Erie Boulevard, Schenectady, New York. 1000 BARGAINS, Drygoods, Notions, Drug Sundries, Specialties, Novelties. Agents undersell stores, Free catalog. Jobbers, Dept. 2098-A, 930 W. Roose- velt, Chicago. 144 ‘aviation jobs now. _home. Accept No Substitutes! Classified Advertisements Rate for classified ads, 18c per word (include name, address and all numbers), per insertion. accompany order and be received in this office July 3rd for the September issue (on sale July 28th). Modern Mechanix Hobbies & Inventions, 1501 Broadway, New York City. YOU'LL Like Resilvering Mirrors. Autoparts, Reflectors, Making Chipped Glass Signs. Write Sprinkle, Plater, 850, Marion, Indiana. AGENTS’ Gold Sign Letters for store windows. _ 500% profit. Free sample. Metallic Letter Co, 426 N. Clark, Chicago. EARN $20 to $100 weekly operating your own business from home. Elco publishing Co, 507-А 5th Ave, New ork. WANTED: Cloth. Sample Stamp: Eden, Baltimore. Chromeshine Polishing Kaplan, 13 S. SELL Novelty fun cards, novelties, etc. Samples, list 10c. National Box 500H, Cincinnati. AMERICAN POLICE JIU JITSU 13 KNOCKOUT Blows without use of fists, by internationally famous Jiu Jitsu instructor. Send 15 cents. S. J. Jorgensen, 284 Maritime Building, Seattle, Washington. AUSTRALIAN OPALS OPAL, Bracelets, dozen stones, very beautiful — $17.00. Catalogue free. Seward, Optician, Melbourne, Aus- tralia, AVIATION GET INTO AVIATION. Air trans port pilots get up to $7,000 per year; mechanics, $2,500. Learn at this Gov- ernment approved school. Write for complete information. State аре, Lin- coln Flying School, 4002 Aircraft Bldg., Lincoin, Nebr. AEROPLANES, New Production, $98.00. Easy payments. Propellers for aeroplanes, boats, sleds, wind-driven generators, $2.50 up. , Send 25с for more information. Universal Aircraft Co., Fort Worth, Texas. AVIATION mechanically inclined young "тел desiring positions as airplane mechanics write enclosing stamp for reply. Aviation Personnel Service, 72 Monroe, Williamsville, New York, INEXPERIENCED workers, apply for i Full salary while learning. Details for stamp. Airploy- ment, Box 553, West Los Angeles, Cali- fornia. AIRPLANES, $50 up. Terms. Crack- ups, salvage. Directory 25c. Aircraft Directory, Athens, Ohio. à AMBITIOUS Young Men interested in entering Aviation as Apprentices, see ad on page 134. BLUEPRINTS METAL TUBE Midget Radio, the last word in compact radio receivers. You can construct this set even though your knowledge of radio is limited hy follow- ing the large pictorial blueprints avail- able, from Modern Mechanix Publ. Co., Greenwich, Conn., at 50c postpaid. $700 BUYS all materials for your Send 25c for design folder, details. Dana Co., Box 1381, Indian- apolis, Ind. BOATS FORD Marine Conversion parts and kits all models. Catalogue 25c (coin). Osmithson, 3105 C Street, Philadelphia. Minimum (0 words. Cash must Address Classified Мог» BOOKS AND PERIODICALS SPORTSMEN’S MANUAL—The out- doors man’s guide containing scores of practical articles by America’s leading outdoor writers, covering every phase of fishing, hunting, camping, and trap- ping. This book, edited by Robert Page Lincoln, will make that next vacation а dozen times more enjoyable. Price 50c at your newsstand, or order directly from Modern Mechanix Publishing Co., Fawcett Bldg., Greenwich, Conn, USED Books, All Kinds. Catalog Listing Thousands Free. Bookman, 369 Border, E. Boston, Mass. BUSINESS OPPORTUNITIES PLASTEX INDUSTRY needs manu- facturers on small scale and for big production of Religious Statuettes, Art Goods and Novelties in Plastex and marble imitation. Cheaply and easily made in our guaranteed rubber moulds. We cooperate in selling goods. You are just in time for big wholesale season now starting. Interesting booklet mailed FREE. Plastex Industries, 1085 Washington Ave., Dept. R, New York. WE START you in business, furnish- ing Outfits and Instructions, operating “Specialty Candy Factory" home. Men and women, earn $25.00 up to $60.00 weekly, all or spare time. (Our 29th year.) Booklet Free. W., Hillyer Rags- M Inc, Drawer 110, East Orange, WE FURNISH Formulas; and teach marbelizing, imitating marble with Porcelain finish, Make rubber molds, one-tenth price charged by rubber com- panies. Satisfaction guaranteed. Rub- ber. Porcelain, Marble, samples Free. Cowell Institute, Grayling, Mich. NEW Brush Plating Outfits for auto parts, reflectors, etc., connect to a bat- tery, no tanks used. Almost as simple as painting. Good income plating and silvering mirrors, low cost. Free proof. Gunmetal Co., Ave. A, Decatur, 11. LIKE To Write? Earn extra cash! Clipping and preparing newspaper articles for publishers. Simple, fasci- nating, profitable. Stamp brings details, Division 76, National Press, 3923 West Sixth, Los Angeles, California. PROFIT with new products. Make, sell, repeat. Analysis. Research. Guaranteed formulas. Biggest catalog free. Special prices, leads. Gibson Laboratory, Chemists, CE-1142 Sunny- side, Chicago. STOP squealing! Start growing! Work mornings home, drive in country, or “movies” afternoons! Unusual plan. No canvassing. Prepare for surprise! National Folio-W (Station “D’’), Los Angeles. WANTED Manufacturers, by old es- tablished firm to cast Ashtrays, 5 and 10c Novelties, etc. See page 28 for our offer. Metal Cast Products Co., 1696 Boston Road. New York City. HAVE а fine business-profession. Quickly become a collection expert. Very profitable, Free details. Cole Associates, Syracuse, New York. SUCCEED With Your Products. Make-Sell Them. Formulas. Processes. Accurate analyses. Catalog free. A. Thaxly Co., Washington, D. C Always Insist on the Advertised Brand!

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Tablecloths and Seat Pads Made From Fabrikoid Clean Easily Housewives will welcome the Fabrikoid tablecloth, chair pad, and shelf edging shown here. The red and white design has a lacquered finish which is easily wiped clean with a damp cloth. INVENTION Finance Magazine, 80-H Wall Street, New York. Year sub- Scription 60c entered upon promise to Pay on receipt of first copy. PROFITABLE Opportunities. Operat- ing Mailorder! Local! Home Busi- nesses! Write. Service Mails, Grand Marais, Mich. AMATEUR Cartoonists, earn up to $35.00 weekly, copying cartoons for ad- vertisers. 3-N Service, Argyle, Wis- consin. SELL by Maill Books, Novelties! Bar- ains! Big profits! Particulars Free! . Elfco, 438 North Wells, Chicago. AGENTS—To mail our Good profits. Home husiness. wood, 149 Fifth Ave., New York. SANIPHONE business local or mail. order, complete plan 25c. S. Vetromile, 20 Gordon Pk., Rochester, N. Y. WHERE to buy at lowest wholesale prices. Information free. ^ Yorena, Box A-312, Bayonne, N. J. HOW and Where to Obtain Capital fully explained. Particulars free. Service, Wapakoneta, O. OPPORTUNITIES Everywhere. Book- let Free. Goodall, 60 Lochalsh Road, Inverness, Scotland. YOUR Own Business Easily Started. Write! Joray, 1015 Shunk St., Phila- delphia, Pa. literature, May- BIG pay, clipping newspapers; investi- gate. McArthur, Drawer 339-12, Butte, Montana. MAIL Order Opportunities. ture. Silvester & Co., Litera- Old Bridge, CAMERAS & PHOTO SUPPLIES PHOTOMURALS-—Gigantic enlarge- ments easily and economically made. Complete illustrated instructions $1.00, Details free. Fogerty, 1689 Capitol, Bridgeport, Conn. When Answering Advertisements Please Mention August Modern. Mechanix CAMERAS and supplies. Free illus- trated catalog listing everything photo- graphic—still and movie cameras, films, lenses—at tremendous savings. Hun- dreds of bargains, new and used. АП guaranteed. We take your old camera or equipment in trade. Write now for your Free copy of our newest money- out! saving Bargain B оок — just Limited edition. Hurry! Central Camera Co. (Photographic Head- quarters since 1899), 230 So. Wabash, Dept. 8.T. Chicago. FREE! Just out! Big. new, illus- trated catalog of nationally advertised cameras and photographic supplies by Marks & Fuller (in the heart of the photographic industry since 1860). Read about extra liberal trade-in allowance on your present camera. Send for it today. Marks & Fuller, Inc, Dept. MM-11, Rochester, New York, U. S. A. MAKE money in photography. Learn quickly at home. Spare or full time. Easy plan. Previous experience un- necessary. Common school education sufficient. Interesting booklet and re- quirements free. American School of Photography, 3601 Michigan Avenue, Dent. 2048, Chicago. INCOME From your camera instead of expense, Low cost home course teaches you to make photographs for magazines, newspapers, advertisers. Tremendous demand. Earn good money wherever you live. Free book. Universal Photog- raphers, Dept, A, 10 West 33rd St. MAKE Money Selling Snapshots. Dime brings ninety page book, complete in- structions, 1800 buyers. Photomarkets, т Evans Building, Washington, CARNIVAL GAMES MAKE You Money—Outfits supplied. Catalog 10c. '"MooreMade", Lapeer, Michigan. CAPITAL RAISE Needed Business Capital. We show you how. Write fully. Enter- prise Bureau, Syracuse, New York. Е ee i Aa EN CARTOONING CARTOONING, Sketching, etc., by Alexander Murray. 46 lessons, 600 illustrations, including practice sheets, pens, pencils, drawings criticized, $1.00 complete. Singer Art Service, 1782 E. 100th, Cleveland, Ohio. CARTOONING & COMMERCIAL ART AMATEUR Cartoonists—Win $25.00. No drawing ability necessary to win. 26 prizes in all. Rush name on post- card for valuable tips on “How to Make Money With Simple Cartoons", Cash Prize Entry Blank and Rules. Send no money. Cartoonists’ Exchange, Dept. C-358-A, Pleasant Hill, Ohio. CHARTERS DELAWARE Charters: Complete in- corporating and organizing service $35. Submitted forms. Chas. С, Guyer, Inc., Wilmington, Delaware. DETECTIVES DETECTIVES. Make Secret Investi- gations. Experience unnecessary. De- tective Particulars free. Write, George Wagner, 2640-V Broadway, N. Y. DUPLICATORS INCREASE Business Now. ''Excello- graph” Rotary Stencil Printer reprints thousands everything you typewrite, handwrite, draw or trace. Colors. $19.75 to $44.00. Terms. Illustrated Literature Free to Business or Profes- sional Men. Pittsburgh Typewriter Supply, Department K-4, Pittsburgh, a. Garden Seat Resembles "Covered Wagon” å i а Inspired by фе Prairie Schooners of pioneer days, this novel wheelable garden chair features a sunshade that resembles the famous “covered wagons” in appearance. Wooden wheels and wheelbarrow type handles permit the chair to be moved at will. EDUCATIONAL & INSTRUCTION MEN Wanted—Learn Tool & Die Making. Automatic Screw Mach. Machinist Trade. Big Demand, Actual Experience. Expert Supervision, Write for Free Book “М”. Allied Screw Machine Со., Inc., School Div., 603-9 Lake St., Chicago. WORK for “Uncle Sam.” Start $1260- $2100 year. Men-women, Try next held examinations. List positions and particulars telling how to get them— Free. Write today. Franklin Institute, Dept. F62, Rochester, N. Y. FOREST Jobs available $125-$175 month. Cabin, hunt, trap, patrol. Qualify immediately. Write Rayson Service, B-32, Denver, Colo. WORK FOR “UNCLE SAM.” Start $105-$175 month. Qualify now for next entrance test. Write, Instruction Ser- vice, 234, St. Louis, Mo. ELECTRICAL REFRIGERATION REFRIGIDAREA Service Manual of Electric Refrigeration. Now obtainable. Trouble prevention, diagnosis, repairs. Operate and repair economically. $1.50. E. G. Gazaway, Box 415A, Tulsa, Oklahoma. ELECTRICAL SUPPLIES replacement parts and supplies, 10c for new, 60-page wholesale cata- log. Autopower, 412 S. Hoyne Avenue, Chicago. ENGINES, MOTORS, ETC. CONVERT Dodge 12V Generator to м H.P., two speed, 32V Motor in ten minutes, no expense. Pumps water, runs saw, grinder, shop tools. Instructions $1.00. Dorris Plant, Moorcroft, Wyoming. 145

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ААА. Trailer Features Easily Accessible Battery Compartment A trailer recently designed by a Cali- fornia manufacturer features a readily accessible battery compartment in the side of the house-car. The compart- ment is conveniently located so as to permit frequent examination of the battery's condition. А simple lock mechanism prevents tampering or theft of the battery. WINDING Data, 225 motors, single and three phase. Price $1.00. Motor pus Service, Box 7631, Kansas City, 0. FEMALE HELP WANTED AGENTS—Up to $32 in a week. In- troduce amazing guaranteed hosiery service. Your hosiery free no extra cost; send size. Wilknit, Desk 8B34, Greenfield, Ohio. FOR, INVENTORS PATENT YOUR IDEA. Write im- mediately for two free books, “Patent Protection” and “When and How to Sell an Invention.” Fully explain many interesting points to inventors and illustrate important mechanical prin- ciples. With books we also send *Evi- dence of Invention" form. Prompt service, reasonable fees, thirty-seven years' experience. Avoid risk of de- lay. Address: Victor J. Evans & Co., Registered Patent Attorneys, 921-J Victor Building, Washington, D. C. INVENTORS—Small ideas may have large commercial possibilities. Write us for FREE book, “Patent Guide for the Inventor" and "Record of Invention" form. Delays are dangerous in patent matters. Free information on hi proceed. Clarence A. O’Brien and Hyman Berman, 28-F Adams Building, Washington, D, C. INVENTORS: Send for my free 72- page book. Conscientious, prompt per- sonal service on all patent matters. Registered Patent Attorney. І. Е. Randolph, Dept. 341, Washington, D. C. WE SUCCESSFULLY SELI, inven- tions, patented and unpatented. Write for proof, and tell us what you have for sale. Chartered Institute of American Inventors, Dept. 5-B, Washington, D. C. 146 Accept No Substitutes! “HOW To Sell an Invention.” Booklet of practical information, compiled by Registered Patent Attorney. Postpaid, $1. C. L. Drew, 582 Market St., San Francisco, California. INVENTORS—Why not profit from your Unpatented and Patented Inven- tions? International Inventors Service, Leon Building, 503 F Street, Washing- ton, D. C. FORMULAS, PLANS, ETC. ANALYSIS. Research. Newest guatan- teed formulas. Biggest catalog free. Spe- : cial prices, leads. Gibson Laboratory, Chemist, CE-1142 Sunnyside, Chicago. 3000 FORMULAS, trade secrets, processes, 368 page volume. $1.00 prepaid. Damon Co., Geneseo, Ill. FORMULAS-—Latest Money Makers. Literature free. D-Belfort, 4042 N. Keeler, Chicago. FORMULAS—AIl kinds. Guaranteed, Catalog Free, Tllinois. 550 MONEYMAKING Formulas, 20c. iu. Book Shop, 100, Park Ridge, inois. : Kemico, 67, Parkridge, FOR SALE DODGE 12 volt generators. Fields Stripped. $3.50. Flecks, Warren, Ohio. FROG RAISING “RAISE Giant Frogs" We Buy! Unusual offer to beginners. Free Book. American Frog Canning. (142-R) HELP WANTED—INSTRUCTION BECOME Business Detective—make money in your spare time—pleasant work—good fees. Details Free. Busi- ness Detective System, 1009 Oak, El- mira, №. У, HYPNOTISM PSYCHO-THERAPEUTICS Learn How. Rokos, 172814 West Gage Ave- nue, Los Angeles, California. HYPNOTISM. Complete 20 Method Course 25c. Lonk Institute Hypnotism, D-1313, Palatine, Illinois. INVENTIONS HAVE YOU a sound, practical inven- tion for sale, patented or unpatented. If so, write Chartered Institute of American Inventors, Dept. 5-À, Wash. ington, D. C. INVENTIONS WANTED SMALL inventions wanted by manu- facturers. I'll help you sell your in- vention. 5. Hull. I,-7829 Euclid Ave- nue, Cleveland, Ohio. INVENTIONS—Patented, Unpatented, Bought outright, royalty. Write Arel- Iano-Power Company, 53 West. Jackson, Chicago, Illinois. INVENTIONS Commercialized. Pat- ented or unpatented. Write Adam Fisher Company, 582 Enright, St. Louis, Mo. INVENTIONS wanted, patented or unpatented, write, Ralph Lee, Vicks- burg, Mich. 7 MASTER Keys $1.00. Catalog Free on request with order, BudenKaye En- erprises. Plymouth, Pennsylvania. KNIFE & SCISSORS SHARPENER РОТ a razor edge on knives and scis- sors. Not a gadget but a paste. Results will amaze you. Guaranteed. В. Stine, Dept. A, Osceola Mills, Pa, 30 er tube. No stamps. LAMP INSECT KILLER STANDARD Electric Lamp kills in- sects. indoors, outdoors. $2.00 up. Literature free, Sauer Brothers, Oak- land, Calif. en Chemists Reclaim Silver From Movie Film Bath Solutions Pure silver in sheet form is reclaimed daily from old motion picture film de- veloping solutions by the reclamation laboratories of the leading film studios. The operation is performed in a manner similar to that of electro-plat- ing by suspending an aluminum plate in the “hypo” solution and allowing the free silver to collect by an electro-chemical process. The chemist, pictured above, is shown testing a sheet of the reclaimed silver. MAGIC TRICKS & NOVELTIES MAGIC Tricks at lower prices. South’s largest line. My famous “Book 1000 Wonders" and “50 Magic Mysteries’ postpaid 10c. Write today. You will be surprised. Lyle Douglas, Station A-3, Dallas, Texas. LEARN MAGIC — Large Illustrated Catalog of tricks. You Can Do. 25c, Holden. 222 West 42nd St., New York, MALE HELP WANTED LOCAL Agents Wanted to wear and demonstrate Free Suits lo friends. No canvassing. Up to $12 in a day easy. Experience unnecessary. Valuable demonstrating equipment, actual samples Free. Progress Tailoring, Dept. W-219, 500 Throop, Chicago. MALE—INSTRUCTION DETECTIVES. Work home or travel. Experience unnecessary. Write, Ameri- can Detective Institute, 2640-T Broad- way, N. Y MIDGET AUTOMOBILES BUILD a Midget Miller Racer. Com- plete plans for constructing this authen- tic midget automobile appear in the new 1936 edition of How-To-Build-It along with many other interesting home and workshop plans. Send 50c for this 148- page book to Modern Mechanix Publ. Co., Greenwich, Conn. MISCELLANEOUS WANTED—Hear from parties in- terested gold or silver ores, buried or hidden treasures. Bergman’s instru- ment $5.00.. Particulars free. Henry Bergman, Box 398MM, Springfield, Missouri. Always Insist on the Advertised Brand?

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Midget X-Ray Locates Flaws In Mechanical Devices se Flaws in mechanical devices are in- stantly detected with this tiny x-ray machine which is no larger in size than the average home moving picture projector. Designed by a German laboratory, the instrument is light enough to be carried around by one person so that it can be employed in tnaking an unlimited number of tests. VARIETY Offerings. of information and opportunity. Sample 10c. Boyles Variety, Pub., Вох 508, Winfield, Kansas. ‘BURIED TREASURE Minerals, free booklet, photographs. Fisher, Palmer Bldg., Hollywood. MODEL RAILROADING BUILD a Model Railroad in 00 gauge (34 inch between rails). А complete catalogue of parts, construction kits, and completed units, One Dime. Nason Railways, P. O. Box 9, Mt. Vernon, N. Y., Dept. X4. MODELS & MODEL SUPPLIES YOUR Ideas developed into practical working model. 30 years successful experience; thousands satisfied custonu- ers. Confidential service guaranteed. Bank references, Send 3c postage for 32 page book “Making Inventions Pay.” Crescent Tool Company, Dept. T. Cin- cinnati, Ohio. MONEY-MAKING GPPORTUNITY AMATEUR Cartoonists—Win $25.00. No drawing ability necessary to win. 26 prizes in all. ush name on post- card for valuable tips on “How to Make Money With Simple Cartoons”, Cash Prize Entry Blank and Rules. Send no money, Cartoonists’ Exchange, Dept. C-358.B, Pleasant Hill, Ohio. MOTION PICTURE & SOUND EQUIPMENT (€————Íst tlla o 94 9 LEARN Motion Picture Theatre Busi- ness. Home-Study Training: Manage- ment, Advertising, Projection. Free Catalog. Theatre Institute, 345 Wash- ington, Elmira, N. Y. When Answering Advertisements Please Mention August Modern Mechanix The magazine. MOTORCYCLES RECONDITIONED Motorcycles. New —used parts for all makes. Authorized Harley-Davidson Dealer. Whitman Motorcycle & Supply Co., 405-9 South- west Blvd., Kansas City, Mo. ALLOY Pistons Harley, Indian, Hen- derson, Excelsior, new or used parts, cylinder grinding, catalogue and wings pin 10е. Ballak, 1115 Chestnut, St. Louis, Mo. SEND 15c for illustrated used Motor- cycle catalog. Bargains. Largest stock genuine Indian parts and motorcycles. Indian Motorcycle Sales, Kansas City, Mo. OFFICE EQUIPMENT TYPEWRITERS, multigraphs, address- Ing machines, adders, dictaphones, dup- licators, sealers, folders. Save half, write Pruitt, 553 Pruitt Bldg., Chicago, OLD MONEY WANTED $5.00 to $500.00 EACH paid for Old oins. Keep all old money. Get posted. Send 10 cents for Illustrated Coin Value Book, 4x6. Guaranteed Buying and Selling Prices. Coin Exchange, Box 18, Le Roy, N. Y. PATENT ATTORNEYS PATENT YOUR IDEA, Write imme- diately for two free books, "Patent Pro- tection” and “When and How to Sell an Invention.” Fully explain many in- teresting points to inventors and illus- trate important mechanical principles. With books we also send “Evidence of Invention" form. Prompt service, reasonable fees, thirty-seven years' ex- perience. Avoid risk of delay. Address Victor J. Evans & Co, Registered Patent Attorneys, 920-J, Victor Build- ing, Washington, D. C. INVENTORS—Small ideas may have large commercial possibilities, Write us for FREE book, "Patent Guide for the Inventor" and “Record of Invention” form, Delays are dangerous in patent matters, Free information on how to proceed. Clarence A. O’Brien and Путап Berman, 28-Е Adams Building, Washington, D. C "INVENTOR'S Guidebook’? containing 96 mechanical movements and advice about patenting, selling inventions, also “Record of Invention", Free. Frank A. Ledermann, Patent Attorney-Engineer, 154 Nassau Street, New York. PATENTS INVENTORS—Small ideas may have large commercial possibilities. Write us for FREE book, “Patent Guide for the Inventor" and “Record of Invention” form. Delays are dangerous in patent matters. Free information on how to proceed. Clarence A. O'Brien and Hyman Berman, 28-F Adams Building, Washington, D. C. Е PATENTS. Booklet free. Highest references. Best results. Reasonable fees. Watson E. Coleman, Victor Build- ing, Washington, D. C PATENTS WANTED = INVENTIONS Wanted—Patented, un- patented. If you have an idea for sale write Hartley’s Inc., Box 928-J, Ban- gor, Maine. INVENTIONS Commercialized. Раі ented or unpatented. Write Adam Fisher Company, 582 Enright, St. Louis, Mo. PERSONAL STUTTERING and Stammering cor- rectéd at home. Booklet free. Paul J. Wolfe, Box 52, Pittsburgh, Penna. University Professor Builds Complete Model Railroad Planned by Prof. William Rowan, of the University of Alberta, this minia- ture outdoor railway is the most complete system of its kind in Canada. The system, which covers most of Prof. Rowan's estate, includes bridges, tunnels, switches and signals. Prof. Rowan is shown above driving the last Spike in a section of the right-of-way. Below him is shown a "double-header" passing over a wooden trestle bridge. PHOTO DEVELOPING DEVELOP and print your own pic- tures. Save time, money with our com- plete $1.49 outfit postpaid or pay post man $1.55 COD. Includes electric ruby lamp, printing frame, photo paper, chemicals and equipment, One of hun- dreds of amaziug bargains in our Free, newest, money-saving Bargain Book. Send for it today! Central Camera Co., 230 So. Wabash, Dept. 18-J, Chicago. FINER Finishing. Rolls developed and printed, with One Colored enlargement, or two professional enlargements. All for 25е (coin). Genuine, Nationally Known, Moentone Superior Quality. Moen Photo Service, La Crosse, Wis. AT LAST! All your prints in natural color. Their lifelikeness is outstanding; their beauty amazing. Roll developed, 8 natural color prints, 25c. Fast service. Natural Color Photo, C-39, Janesville, Wis. $100.00 VALUE prize offer. Roll de- veloped, 8 guaranteed prints, oil painted enlargement, coupon on 8x10 painted enlargement, 25c. Immediate service. Janesvile Film, A-39, Janesville, Wis. 147

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Grinder Rotates At 9,000 R.P.M. Powered by а 1l5-horsepower motor, this flexible shaft grinder operates at 9,000 r.p.m. on either 110 volt or 220 volt A.C. and D.C. current. Used for grinding weld seams, flat surfaces, snagging castings, etc., its 4-inch wheel is said to produce same results as an 8- inch wheel used on slow speed units. WIN prize, $100.00 value offer. Roll developed, 8 guaranteed prints, 2 en- largements, coupon on 8x10 painted enlargement, 25c. Daily service. Mid- west Photo, B-39, Janesville, Wis. ROLLS DEVELOPED—Two Beauti- ful Double Weight Professional En- largements, 8 Never Fade Prints, 25c. Century Photo Service, LaCrosse, Wis. ROLLS _DEVELOPED—25c coin, Two 5x7 Double Weight Professional Enlargements, 8 gloss prints. Club Photo Service, LaCrosse, Wis. 8 FINE Enlargements per roll, Charge 25 cents. Beat this for a bargain! Hilo, Yale, Okla. PRINTING 100 EACH, 812x11 Letter-Heads, 634 Envelopes, $1.00 Postpaid. Samples! pues Co., MM, Box 63, Indianapolis, nd PROPELLERS PROPELLERS, Sled-Lightplane, Cata- log 10c. Woodcraft Propellers, Hill- side Station, Wichita, Kans. RADIO PLANS 18 Distance Crystal Sets— 4250 mile record; copy “Radio Work- bench"—25c. Laboratories, 151-K Lib- erty, San Francisco. RADIO & TELEGRAPHY RADIO BUILDERS’ MANUAL—A book of radio set building plans and kinks for the home experimenter. Everything from a crystal set to a powerful 6-tube auto radio is included. Price 50 cents—order directly from Modern Mechanix. Publishing Co., Fawcett Bldg, Greenwich, Conn, 148 Accept No Substitutes! RADIO Engineering, broadcasting, aviation and police radio, Servicing, Marine and Morse ‘lelegraphy taught thoroughly. All expenses low. Catalog free. odge’s Institute, King St., Val- paraiso, Ind, RAZOR BLADE KNIFE ARTISTIC. Durable steel. Watch chain loop. 214"x]"xr$", folded, 25с, coin. Vital Products-M, Hoboken, М. J. SALESMEN WANTED JUST OUT! Directory of over large responsible business firms in every section of the United States who are immediately seeking direct selling salesmen. products given. Also names of scores who supply you with complete Outfits ; Absolutely Free—and pay generous commissions. Send 25c for this large 160 page book, Tt can be the means of making 1937 your greatest money-mak- | ing vear. Direct Selling Institute, Inc., 75 East Wacker Drive, Dept. D, Chi- cago, Ill. FREE Suits, Pants, O'Coats. Given as bonus besides large cash profits, premiums and gifts. Sell only (4) suits to get a Free Suit. No limit to number of Free garments you may earn. Wholesale prices $16.95 and up. Sample | line Free. No experience needed to | make easy sales. All garments indi- vidually cut and tailored to measure. Satisfaction or money back guarantce. Three Star Clothes, Inc. 330 South Franklin St., Dept. T-1, Chicago, ШІ. IMAGINE going into stores, gas sta- tions, etc., empty-handed and coming out, with money in your pocket. New, powerful progressive sales stimulator. Merchants going for it. Fast, adyance cash commission getter. Automatically repeats. Sales outfit free. Meinhardt, Dept. T-8, 18 E. Kinzie, Chicago. IMMEDIATE openings for ambitious men! Wear, introduce “Fairbanks” tailored- to-measure clothes, make up to $10 in a Day. Experience unnecessary. Bonus Suit offer. Low prices. Quick sales. Free outfit, Permanent! Fair- banks Company, 2309-A Wabansia, Chicago. GOLD Reflecting Window Sign Let- ters. Penny Each. Large Sizes. Fasily Applied. New Styles. Absolutely Beautiful, Free Samples. Atlas Sign Works, 7941-G Halsted, Chicago, Ill. BIG commissions selling stores celluloid pricing tickets, metal shelf moulding, menu covers, signs, chrome changeable letters. T. Pricing Press, 124 White St., New York. SHIP MODELS & SUPPLIES SCALE Model, Roman Cargo Ship— All Materials, Instructions, Blue Print $2.00. Master Models, 64 Tine Sty River Rouge, Michigan, U. S. TATTOOING SUPPLIES TATTOOING Outfits, Supplies—Cata- logue. Guaranteed Remover, “Waters,” M-965 Putnam. Detroit. TELESCOPES, MICROSCOPES, ETC, COMPLETE 8” Telescope with alumi- nized mirror $85.00. Also 107-12” and finished parts. Stamps for catalogue. New Telescope Company, 3675 West 165th St., Cleveland, Ohio. TELESCOPES, Microscopes, Binocu- ars. Lowest prices. Optical catalog free. Brownscope Company, 234 Fifth Avenue, New York. А Full information about their | Blower Heater Warms Up Cold Airplane Motors The problem of heating up cold air- plane motors at Indianapolis’ Munici- pal Airport has been simplified by use of a blower heater which is placed in front of the radial motor of the craft. Designed by Nish Dienhart, airport superintendent, the heater is capable of warming up cold motors to such an extent that strenuous propeller “kicking” is eliminated. TELESCOPES, Microscopes, Binocu- lars, Chemistry, Mineralogy. Catalog Free. Teeko, 315-K, Evanston, Illinois. BUILD Reflecting telescopes; catalog free. Instructions 10c. Optical Labo- ratories, Larchmont, N. Y. TREASURES PERSONS knowing of treasure loca- tions write R. Evans, 415 Dorchester Ave., Cincinnati, Ohio. WELDING & SOLDERING ARC-WELDER 40 volts, 25-200 am- peres, Direct Current. Build it your- self from old North-East, automobile generators. upkeep. Results guaranteed, Certified Instructive Plans $1.00 COD $1.12 Includes Free Consultation Service for one year. Materials and parts furnished at cost. Welders Club of America, Box 3432-B, Merchandise Mart, Chi- cago. ARC-WELDING Outfit, heavy duty, $2.00. Weld fenders, braze, solder. Lavrow, 4368-W. Warren, Detroit. Stamp appreciated. DODGE are welder plans 35c. 50 other generator changes. LeJay Manu- facturing, 1314 Lake, Minneapolis, Minn. WIND ELECTRIC PLANTS GENERATOR Propellers, expertly de- signed at factory prices. niversal Aircraft Co., Fort Worth, Texas. WIND Generators, Propellers. Lowest prices. Woodcraft Propellers, Hillside Station, Wichita, Kans. Always Insist on the Advertised Brand!

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Adventures Of Poison Squad : [Continued from page 32] protecting the public from the danger of poisons used in sprays to combat inséct pests and diseases that attack fruits and vegetables. Every year thousands of carloads of fruits and vegetables are given painstaking laboratory examination to detect traces of such health-destroying residues. However, many of the states are co- operating and the situation is improving rapidly from year to year, officials say. But, to complete the story about the White Plains poisoned pastry case. Aided by local health officers, the Federal food sleuths, as men- tioned earlier, traced the source of the spoiled food to a single manufacturing bakery in West- chester County and rounded up and destroyed all. shipments sent out on the same day as the food poisoning outbreak. Meantime New York agents of the Food and Drug Administration made a thorough inspection of the bakery that made the pastry and found not a single trace of any unsanitary conditions. To this day the case is somewhat enshrouded in mystery, but it is believed by the Government Scientists that the cream-filled pastry became poisonous mainly because it became unduly ex- posed to warm temperatures without proper re- frigeration. This outbreak and many other somewhat similar ones emphasizes that cream-filled pastries, since they are ideal for the growth of bacteria, should be produced, handled and refrigerated with extraordinary care if they are to be held any length of time before consumption. A good many months ago New York City members of the Poison Squad tracked down 15 cases of the parasitic disease known as trichinosis, at Williamsville, N. Y. The outbreak, like others occurring in the United States, was traced to the eating of raw, or improperly cooked pork that was infested with the parasite known as Trichinae. Although 8 of the 15 persons affected were con- fined to hospitals, no deaths were reported. This [Continued on page 151] ADLETS FOR HOBBYISTS (See regular classified section for rates and other Information.) STAMPS SUPER-WONDER Packet offered, containing 60 different stamps from Afghanistan, Transjordania, North Borneo, Manchukuo, Sudan, Macao, Iraq, Charkhari, French and British Colonies, including natives, beasts, ships, etc., all for 5c to approval applicants. Big illustrated lists included. Kent Stamp Company, Box 87-Z (G. P. O.), Brooklyn, N. Y. GIANT Netherlands Commemorative Triangle, Jubilee, Air- mails, Pictorials in Mammouth Collection—10c, with Double Premium Approvals. Free Airmail Collection given regular customers. Tru-Value Stamp Service, Box M1412, Hart- ford, Connecticut. COLLECTORS Illustrated Catalogue Free:—28 pages, fea- turing United States, Canadians, Newfoundland, Dritish Colonials, Jubilees, Edwards, Sets. Sent for postage or entirely free. Empire Stampco, Dept. MM, Toronto, Canada. PRODIGIOUS Gift! Scare Perak, Negri Sembilan, Bi- colored Airpost, Picturesque Trinidad, Siberia, Selangor, etc. —Free with Approvals! Postage 3c, Saxon Company, Albee Dldg., Brooklyn, N. Y. MAGNIFICENT Mourning Stamp; complete issue com- memorating bloodiest period in history with 20 additional commemoratives only 10c. Friendly Filatelists, Box 4428, Philadelphia, Penna. STAMPS! 100 diff. 3c; 500 diff. 35е; 1,000 diff. 90c! Illustrated Album (4000 spaces) 22c. Approvals sent. Tatham Stamp Co. (D9) Springfield, Mass. UNITED STATES—45 different 10c. Free 25 different AUDIRE or pricelist. Enclose 3c. Sidenburg, Baroda, ich. MONTHLY Stamp Magazine, 6 months and 25 foreign stamps, 25c. American Stamp Journal, Cedar Rapids, Iowa. When Answering Advertisements: Please Mention August Modern Mechanix FULL sized lawn ornament patterns, any craving enlarged 5с ар. В. Smith, 43 М, Fitzhugh St., Rochester, М. Y. FREE!!! New King George VI set. T Postage 3c. ROBERTS, 901T Fourth, Baycity, Michigan. COINS $2000.00 FOR 1c. We Guarantee To Pay World's Highest Prices, certain 1909 cents $25.00, 1860 cents $500.00, Large cents $2000.00, Quarters $300.00, Gold Coins $7500.00, 1913 Liberty Head Nickel $350.00, certain 50c of 1838— $1500.00, 1853— $750.00, 1915—$13.50, 1921—$26.00, 1922 —$60.00, 1928— $12.00, 1935— $60.00, Half Cents, Half Dimes, Foreign Coins, Paper Money. and Thousands of others up to $5000.00 each. Know What Your Coins Are Worth. Send Dime For 1937 World's Largest 10с Complete Illustrated Catalogue. Romanocoinshop, Dept. 159, Nan- tasket, Mass. $5.00 TO $500.00 EACH paid for Old Coins. Keep all old money. Get posted. Send 10 cents for Illustrated Coin Value Book, 4x6. Guaranteed Buying and Selling Prices. Coin Exchange, Box 17, Le Roy, N. Y. CALIFORNIA GOLD, quarter size, 27c; $16 size, 53c. Illustrated Catalogue Coins and Stamps 25c. Norman Shultz, Salt Lake, Utah. FREE: Foreign Coin, Banknote and Large Illustrated coin catalogue, for 4c postage. Approvals sent. Tatham Соірсо, Springfield-9, Mass. COINS, Beadwork, Indian Relics, Minerals, Books, Curios, gamps, Catalogue, 5c. Indian Museum, Northbranch, ansas. INDIAN CURIOS INDIAN CURIOS. Tomahawk Head 50c. Dardanelle, Arkansas. 100 good ancient Arrowheads $3.00. Illustrated catalog 5c. H. Daniel, 149

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TRAINED PILOTS WANTED: трен Tor BIG PAY Ј085 Ø "AVIATION, Aviation Needs and Must mtm Thousand ok Newly Trained Men for new positions as Pilots and Airplane Mechanics. Аіг- lines adding millions of miles to thelr flight schedules. Factories crowded with huge private and Government orders for new airplanes. This Lincoln Government Approved School trains you for good pay positions as Pilot or Government Licensed Airplane and Engine Mechanic, School now in 27th year; 17 years teaching Aviation. Good Salaries paid to properly trained men. Airline Pilots get up to 3700 a month; Co-Pilots $250 a month, Licensed Mechanics get up to $200 a month—wonderful opportunities for promotion Make Aviation YOUR Career, Supervised by U. 5, Government, Avia- lion offers you unlimited opportunities for promotion. Prepare your- Self at this Lincoln Government Approved School. Graduates now employed by leading Airlines, Factories and Foreign Governments. We assist Graduates In locating positions when qualified. Write for Cata- log. Please state age. LINCOLN AIRPLANE & FLYING SCHOOL, 404-G Aircraft Bidg., Lincoln, Nebraska. WHY RENT A BOAT? MAKE YOUR OWN Even a child can build at least one of the many boats that are described in ines big new 148-page book, HOW TO BUILD 20 BOATS. Send 50c for your сору, now. MODERN MECHANIC PUBL. CO., Fawcett Bldg., Greenwich, Conn. pis NEEDS MEN NOW! AIR CONDITIONING ELECTRIC REFRIGERATION Large Air Conditioning and Electrie Refrigeration Train= ing Organization now selecting men who would like, to prepare ra positions as Iocal Service and Installation Exe perts. Many make $20.00-$50.00 a week. No experienc: needed. We will train you in your spare time for thi interesting work. For further facts, without obl your name and address, age, occupation, e по Institute, 400-410 N. Wells St. for life’s pleasures. Drive to the country or go to the “Movies” afternoons. Work each morning till noon at HOME. Unusual Business “Plan” (Treatise No, 1). No Canvassing. Prepare for Surprise! Write now in time for a happy summer! NATIONAL FOLIOS-W, Station “р”, Los Angeles. Earn While Learning at Home Television, Photo Electric Cells, Public Address Many R-T-I Trained Men make up to $75 a week and more in full-time radio jobs— $5-$15 in spare time alone. More trained men needed. Learn at home by quick, $25 R-T-I WAY. Endorsed by REAL PAY big concerns. . Write for wie pportunity Book FR Inc., 2136 RADIO and TELEVISION INSTITUTE, Lawrence Ave., Dept. 3-C, Chicago, 111. Kidneys Must Clean Out Acids The only way your body can clean out Acids and poisonous wastes from your blood is thru 9 million tiny, delicate Kid- ney tubes or filters, but beware of cheap, drastic, irritating drugs. If functional Kidney or Bladder disorders make you suffer from Getting Up Nights, Nervousness, Leg Pains, Backache, Circles Under Eyes, Dizziness, Rheumatic Pains, Acidity, Burning, Smarting or Itching, don’t take chances. Get the Doctor’s guaranteed prescription called Cystex (Siss- tex). Works fast, safe and sure. In 48 hours it must bring new vitality, and is guaranteed to do the work in one week or money back on return of empty package. Cystex costs only 3c a dose at druggists and the guarantee protects you. PHILCO CROSLEY ZENITH GRUNOW and 46 olher mfgrs. endorse R-T-I 150 Accept No Substitutes? | Always Conditioning Your Sail Boat [Continued from page 141] and deck paint is lower priced but not satisfac- tory for this purpose. Go over fittings and mouldings carefully. Re- fasten the former after cleaning, using new screws and renew entire sections of rail and quarter round rather than fit in small pieces. If you change the boat’s color scheme do so only after seeing an identical boat so painted or draw yours out on paper and fill in new colors with crayons. Different colors and their placing have a tendency to shorten or lengthen a boat; a chubby craft may be made to look sleek by painting the hull dark with an arrow or con- trasting light sheer strake or rubbing rail. A low boat will look larger by painting it white Black is harder to keep clean in salt water, makes for a warmer boat and topside seams have a tendency to open. High cabins and sides should be kept dark. Mahogany, gray or buff colors are recom- mended. Cut in different colors sharply so as to locate joinings at some point in the construc- tion as deck edge, rail or cockpit coaming. If the waterline is not already scribed or scratched in, tack long timber batten guides along the hull, then scratch in the waterline with a bent and sharpened file tang. It will be there for sub- 'sequent paintings and the topside paint can be allowed to run down below the line to be later covered with the bottom paint. Sails, engine and gear fittings call for treat- ment all their own. The best plan is to have re- moved these the previous fall so they can-be worked on during the winter in the warmth of the basement or heated garage. Small sails should be laundered clean. If your laundry cannot do the work contact some sailmaker who will tell you where to send them. New York sailmakers wil mildewproof sails, old or new, at around twenty cents a pound. No matter the age of your sail go over it carefully before bending it on. Machine sewing patches ashore is easier and better than hand work afloat. Renew grommets wherever loose and mend frayed boltropes. Standing wire rigging is usually painted with galvanized or aluminum paint and splices served with marline wound on over varnished muslin or tire tape. Running rope rigging if only used one season can be trusted another by reversing ends to change working sections. Varnish the mast and boom after sanding and filling cracks and rents with proper filling. Scrape and varn- ish blocks and oil their sheaves as well as the sail tracks, also paint the anchor and check the condition of its line. Every manufacturer issues an information book in connection with the running of his particular engines. If you haven’t one send in your serial number and secure a copy. Follow its directions for fitting out the engine. Spring is a poor time for major engine repairs as marine mechanics are busy on big jobs now and automobile workers Insist on the Advertised Brand!

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should not be trusted with these machines because they do not appreciate the difficulties under which they run. Minor adjustments are usually all that are required. Perhaps new packing if oil has been oozing out, strainers cleaned, points and plugs renewing for best possible running and the battery recharged or replaced. Canoes call for larger boat treatment in smaller doses. Modern marine glues, especially the hard glue treatment outlined, work wonders with torn and worn canvas. Manufacturers issue helpful booklets in connection with such repairs and their products have removed the old bugaboo of canvas covered boats. Hardboiled boat owners often try to impress the newcomer with all the work necessary at fitting out time, but a comparatively new boat decently used and kept up during the summer and properly laid up for the winter invariably requires more than a careful preliminary clean- ing, a thorough sanding and an interesting final light painting with good paint. For some years to come harder jobs, barring accidents, will result only from carelessness. Careful owners avoid major repairs and heavy expense by common- sense use.

Adventures Of Poison Squad [Continued from page 149] fact is attributed to the prompt action of the Federal health sleuths, aided by Dr. Myron Metz, local health officer, who obtained a list of the buyers of the infected pork and advised each person to call a physician in case he felt sick. A case of food poisoning in North Dakota, in which 12 persons died from eating home-canned peas, has prompted the United States Department of Agriculture to call attention again to a method of canning non-acid vegetables in the home to guard against the deadly botulinus poison. In the canning of non-acid vegetables—peas, asparagus, beans, corn, beets, and spinach—the only safe course is to destroy all bacteria that may be present by canning under steam pressure, ac- cording to the Bureau of Home Economics. In the case of acid vegetables and fruits, such as tomatoes, apples, peaches, and gooseberries, the bacteria are killed at boiling temperature (212° F.) but with non-acid vegetables there is no assurance that the botulinus organisms will be killed by processing in boiling water unless the material is heated for six hours or longer. Obviously, a 6-hour treatment of peas or similar vegetables would result in a very unattractive product. A much shorter heating time is required at a temperature of 240° or 250° F., such as may be obtained in a pressure cooker.

Popularity of chemistry is suggested by a sur- vey showing that in 80 women's colleges, 11 per cent of students took the first general course in this science, INVENTORS Pages 6 and /

NEW BRUSH PLATING OUTFITS tor auto parts. Connect to a battery, no tanks used. Almost as simple as painting. Your opportunity to make good income plating auto parts, reflectors, mirrors, etc. Free Particulars and Proofs GUNMETAL CO. Ave, P ELECTRIC ’ ARC WELDER or Ordinary Light Socket. . » This New Electric Arc Welder is made possible by the invention of alow voltagecarbon. Auto bat- teries may be used without re- moving from car. Uses abou same current as four headlight bulbs. Can be used on electric light socket by using а Trindl Converter in place of battery. Broken parts areSIMPLY MELTED TOGETHER by the 7. white HOT electric arc, in just a few sec- Z ^, onds, Produces about 7,000 degrees heat. 2: Hottest Flame Known У < MELTS iron and steel in- * stantly. Welds fenders, ra- М diators, holes in bodies and Decatur, Ш.

milk cans, tanks and brazes broken castings. Works on anything —iron, steel, cop- | f: per, brass, tin or galvanized D metal. Permanent repairs made for almost nothing. Used by factories in many operations , Positive money back guarantee by respon- siblefirm. Send for it now. TRINDL PRODUCTS 2229-SM CALUMET AVE., CHICAGO, ILL, When Answering Advertisements Please Mention August Modern Mechanix 151

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ти ши mmy M ши ши ши et at UR | a Month The new w 9-inch Workshop Lathe is a back- geared, screw cutting lathe designed te handle the finest, most accurate jobs in manufacturing—in the tool room, in home workshops and automotive machine shops, for all classes of fine precision work. Materials and workmanship are exactly the same as used in our more expensive models of larger size, thus representing the greatest value we have offered in more than 30 years of fine lathe manufacturing. Features include: Twin gear reverse to leadscrew; Ball Thrust Bearing on spindle; Automatic Longitudinal screw feed to carriage; Precision leadscrew for cutting screw threads from 4 to 40 per inch; 3(- inch hole through epindle taking colleta up to 14 inch capacity. Operates from any ordinary lamp socket. Write for catalog. SOUTH BEND LATHE WORKS 521 E. Madison St.,South Bend, Ind.,U.S.A. ` -—— € — uà — m 0m b P e En D UD M M E South Bend Lathe Works, - 521 E. Madison St., South Bend, Ind., U.S.A, Please send the following free, postpald: о. 15-U. О 9" Workshop Lathe Catalog O General Catalog No. 96. - О Easy Payment Plan. Class of work. seses Name...,cecccsevecescvcvcsceses Address... i. E E dene sesesweneaeaeisie Сіу. POIL se cceess a SOUTH BEND ' PREELLLGR: 152 Ne ПЕТА 914" swing by 3° bed ‘Workshop Bench Lathe vith Horizontal Motor Drive, 14 h.p. Reversing Motor, Bmiteh a and adjustable belt tension countershaft as shown above. . à 5116% 5 OTHER SIZES: 9”, 11", 13’, 15" and 16" SWING IN ALL BED LENGTHS PRICED FROM $97 to $1200 Lathe shown below is No. 117-C 16” x 6’ Quick Change Gear Underneath Belt Motor Driven Lathe with 1 h.p. motor. 5869 Complete as shown. Weight 2300 Ibs.......-- ($87.00 Down, $38. 50 Monthly for 22 Months) ($15.00 Down, $6.00 a month for 18 minds Bm em vtec m d Qu y um Р LATHES Accept No Substitutes? Always Insist.on the Advertised Brand?

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Dogs — Diamond Guardians [Continued from page 56] are more than sixty Alsatians and fourteen bull- mastiffs—a "staff" from which the fifty dogs that keep watch every night are drawn. “All the most important places on the mines have their dog sentries at night—the pulsator house, where the diamonds are finally recovered, and the offices in Kimberley where diamonds are kept in safes,” Mr. Marsberg told me. “At each spot there is a dog chained to a picket line about a hundred yards in length. If this dog hears a suspicious sound, it barks and up comes a "fight- ing dog," that has been roaming the area free, to investigate. "Cattle are responsible for many false alarms. But at long intervals the dogs find à man wearing knee and elbow pads, crawling over the ground in search of diamonds. Then the "fighting dog" puts its training into practice and tackles the raider without biting. If the man attempts to escape, the dog will hang on to his arm, but it will never fly at his throat. Otherwise the dog will escort the man and shepherd him towards the human guard. "A raider armed with a revolver is forced by . the dogs to drop his weapon. The dog then car- ries the revolver in its mouth until the guard takes charge of the trespasser. So cleverly do the dogs carry out their duties that I have never known a dog to be injured in a tussle.” Mr. Marsberg was once bitten in the nose while stopping a dog fight, but he declares he has never known.a treacherous Alsatian. Training starts in the “kindergarten,” where the puppies are strung out on a picket line and taught to sit and lie down at the word of command, and later to heel. After a month or two comes a course of dis- cipline, when the dogs go over jumps and hoops. Finally there are exercises in which a man wear- ing a padded leather suit with long sleeves takes the part of a raider, and the dogs are taught to hang tenaciously on to the man until the trainer arrives on the scene. I saw a dramatic rehearsal with a famous dog named Bongo in the leading part. Bongo is ten years old, one of the first batch of Alsatians trained, and still doing useful work. A man went into hiding in the long grass, and Bongo was. sent sniffling out in search of him. Dis- covered within a minute, the man lashed out furiously. At once Bongo hackled up and gripped the long leather sleeve. It was clear that a raider, seized by those teeth, would soon give up the struggle. In the next test Mr. Marsberg stuck a match in the ground and dispatched Bongo to reveal the strange scent. The match was speedily de- livered to the trainer. These dogs can jump over burning fences, climb walls twelve feet high, walk the plank, and obey whistles and signals. The full training period is eighteen months to two years. Know Electricity as Experts Know It—and Get an Expert's Pay? Recovery has begun! The months ahead are charged with signifi- cance and expectation. What will you do to get the jump on the other fellow? Thousands of men have used he Croft Library of Practical Electricity The Croft Library is a complcte electrical educator. LR is founded on 20 years of shi rt-sleeve experience—on work as it is actu- It 12 jammed from cover to cover with the kind of harde Written so that the beginner can easily n transformers, cireuits, switelibbards, та ipution systems - electrical machinery of every t e—wiring for light and power—wiring of finished buildings—underwriters’ and municipal requirements—il- luminatlon in its every phase—the most improved methods of lirhting— татар апа lamp е efects, etc.—how to do a complete job, from estimating о complet No money down--easy payments Fill in and mai! the coupon attached and we will send you the entire Set of seven volumes for ten days’ Free Examination. We take all tha risk—you assume no obligation. If you decide to keep the books, sen 51.50 in ten days and the balance af the rate of $2.00 a month. send the coupon NOW and see the books for yourself. | FREE EXAMINATION Г COUPON | цаатан McGRAW-HIEL BOOK CO., 330 W. 42nd St., New York nd me for ten days’ free examination the Croft "ibrary of Practical Electricity. И satisfactory I will send you $1.50 in 10 days and $2.00 monthly until the price of $19.50 is Be If not wanted, I will return the books „ (To insure prompt shipment write plainly and fili т all lines.) Name ..--.--..2l22-2-2-.-22-22-22222-2£2-£2-2-2-22--2--2-2-22-2-2-2---- | City and State Position --------- GOVERNMENT START $1260 to $2100 YEAR OVER 42,000 APPOINTMENTS LAST GOVERNMENT YEAR MEN—WOMEN File Clerks / Postoffice Clerks-Carrlers Rallway Postal Clerks Customs Inspectors / Stenograpers-Clerks Many Other Jobs GET READY IMMEDIATELY ¿=-= Franklin Institute Dept. E-260 ROCHESTER, N. Y. ’ Gentlemen: Rush to me, FREE of charge, list Common Education -S of U. S. Government big Usually Sufficient. © Pay jobs. Send FREE 32- $ page book describing sala- Mail / ries, vacations, hours, work, Coupon / etc. Tell me how to get one of TODAY— / these jobs. SURE / / Маше......... / / Address ...... Rus m When Answering Advertisements Please Mention August Modern Mechanix 153

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роли kusines рига идо An electric fan with rubber blades sufficiently soft to prevent injury even to baby’s hands. Because of shape and pitch of the blades the fan delivers an amazing flow of air. A child’s vehicle propelled by pushing and pull- ing a handle in front of the seat. Designed for children between the ages of three to ten years, its frame is capable of supporting 200 pounds. A tee square of stainless steel with transparent edges. Features include double channel construc- tion for rigidity, narrow blade covering a mini- mum of drawing and is non-warpable. A safety medicine cabinet having a-dial combi- nation lock protects children from dangerous medicines and poisons. A paper cup with substantial handle eliminates possibility of burned fingers when cup contains hot liquid. An electrie utility fan with a reversible base which makes it possible to hang the fan on the wall or stand it on a level surface. A pneumatic valve grinder giving 600 to 6,000 Strokes a minute, and is instantly adjust- able. A new series of iransmitting con- densers for high and ultra-high frequency units. Plate spacing varies between .031 and .171 inches, depending upon the voltage break- down required. CA— ae A screwdriver incorporating а flashlight attachment shines light on the work when needed. 154 An automatic © exposure meter | indicating the ex- act exposure or diaphram opening to use indoors or out under any ' light conditions, The device is ap- plicable to still, movie or three- color cameras without change or modification. E New device keeps visible record of all outgoing calls from any house- hold or office telephone. A sheepskin mitten for car washing use. Spe- cial treatment of mitten eliminates the need for chamois when car is cleaned. A fast production gun for all types of product finishing. Especially designed for spraying new synthetic materials. A spring checker for determining the strength of compression coil springs. A wood preservative to give protection against destructive work of termites. A sawing vise suitable for cutting thin wall tubing. A tachometer for testing normal rates of rotation or speeds. A hand shear for cutting flat steel bands, .А slow speed, high torque hand drill. A knife espe- cially designed for stripping insula-' tion from wires. A recotd player for use with the conventional models of home electric radio receivers. Editor’s Note—Addresses of manufacturers of these and other new products in this issue can be obtained by sending a stamped, self-addressed envelope to Modern Mechanix Publishing Co., Information Bureau, Fawcett Building, Green- wich, Connecticut. Manufacturers are invited to submit material for publication on this page.

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MILES K4s steam locomotives of the Pennsylvania Railroad weigh over 250 tons and pull a train of over 1000 tons. Their powerful air- brakes can bring them to a stop from a speed of 80 miles per hour quickly and smoothly. Powerful air-brake of locomotive illustrates HIGH COMPRESSION principle of modern auto engine HE higher the air-pressure in the locomotive brake Tono the more stopping power Casey Jones gets. The higher the compression in the cylinders of your automobile, the more driving power you get. That’s why automobile manufacturers are using high compression engines in even the lowest priced cars. 'These cars squeeze more power, more mileage, more get-up-and-go from every drop of gasoline. 'To get these advantages, set the spark for maximum performance and use a fuel made for high compression! Stop at pumps marked “Ethyl.” There GIVES YOU A BETTER RUN FOR YOUR MONEY RINTE, eR O USA 2 TO DEAD STOP N A FEW SECONDS! BRAKE SHOES are jammed against racing drivers by compressed air power for smooth, safe stops. HIGH COM- AIR in train brake- PRESSION in your cylinders gives stop- automobile engine ping power to con- cylinders gives “‘go- | trol heavy trains, ing" power. | fluid (containing lead tetraethyl) than you get inthe best regular-grade gasoline. By prevent- ing harmful knock and overheating, you make sure of 100% performance from your high compression engine and save on gas and oil. And at these Ethyl pumps you get all-round quality that is double-tested—by the oil com- pany and by the Ethyl Gasoline Corporation. COMPRESSED GETS FULL POWER FROM HIGH COMPRESSION

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Copyright 1937, Liccerr & Myers TOBACCO Со.

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uble Page Spreads

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A frank man to man talk about PATENTS-INVENTIONS -SELLING INVENTIONS HE world of invention moves on. About a hundred years ago people were saying, ""There's nothing left to invent"—today we know that is one of the funniest things ever said. Just think what has happened in the last hundred years! Autos, radios, airplanes, and thousands of useful, practical devices for home, shop and office have been invented and put on the market. Inventors are con- stantly making the world a better place to live in. Did you see a notice in the paper that an obscure worker, Hans Wach, has invented a simple device to utilize exhaust steam on steam boats. Already, the report states, the steam ship lines have saved more than $15,000 in fuel bills with his invention. Almost in the same breath the Dept. of Commerce announces that it will soon test out a new non- crashable aeroplane, which the average man can learn to fly in a day, which will travel at 110 miles an hour and sell at the price of a cheap automobile. An unknown Seattle man has invented a robot to go 5,000 feet under the sea and recover millions and. Who Are Inventors? You'd be amazed at the men we con- tact in the course of a busy year, Most of them do not consider themselves inventors at all, During their work or leisure they get an idea, They work it out on paper, They get in touch with us about Protection, Did you know that a dentist invented the stock ticker, a school teacher the telephone, a farmer the typewriter, an artist the telegraph? Did you know that the crinkly hair pin—sold by millions now—came about because a husband saw his wife twisting the old-fashioned straight hair pin to make it stay in place? Poor men who have no thought of invention now will be Financially well-fixed in a few years because of a happy thought that the world could use to advantage, sell have any the average man, YOU CAN HAVE trouble, or delay, Can You Answer These Questions? Ask yourself these questions: the Patent Laws protect me? What easy № steps can I take, without cost, to put || myself in position to support my belief Е that I am the first man to think of my invention? Is a Patent worth the a model? to secure financial help? If 1 do how shall 1 reach people who can market my invention? Can I protect and sell an improvement on some invention that has already been patented? These are but a few of the questions which usually confront millions of dollars worth of gold lying at the bottom of the ocean since the days of the early Spaniards. Remember this: For every outstanding big inven- tion there are thousands of small, simple things for use in the home, the office, the factory, on the farm, on every sort of travel conveyance. Little articles like you find on the counters of a 10-cent store, hardware store, drug store, toy and novelty shop. Many Little Ideas Have Big Commercial Possibilities A person finds something he’s using doesn’t work right, or it’s clumsy, or costs too much. He gets a happy thought. He improves the old Article. That’s contribution to human progress. That’s the way that many, many men have reached the goal of financial comfort; independence and even wealth. Most of the things millions of us use didn’t come from the brains of engineers and physicists. They came from the mind and maybe the crude home work bench of Mr. Average Man, busily engaged in@arning his bread and butter at whatever chance or circumstance has given him to do. The “little” man’s opportunity as an inventor was never greater than it is today. Our Business Is To Help You. Write Us Today For more than thirty-six years, this firm has been helping men with an inventive tura of mind, We maintain a large staff of trained, experienced specialists—Registered Patent Attorneys, Draftsmen, and Searchers to help our clients secure all the protection to which they are entitled, Fees are reasonable, De- ferred payments frequently arranged, Ques- tions promptly answered, Write us frankly with absolute assurance that what you say will be treated with strictest secrecy. But FIRST, send for the FREE BOOKS shown on the op- posite page, They are filled with facts, pic- tures and suggestions, They tell you things about, Patents, Inventions and Selling Inven- tions that we have learned in our long experience, They may save you time, expense, EVEN LATER DISAPPOINTMENT, Simply fill in the coupon. No charge, no obligation. Write us today, How do cost? Do I need Should I try to my invention before I it Patented? 15 there safe, business-like way apply for a Patent You need the answers! THEM, without cost, Copyright 1937 Victor J. Evans & Co. RUSH COUPON TO WASHING 6 Accept No Substitutes! Always Insist on the Advertised Brand! NZ N “МШ NEW BOOK About Selling INVENTIONS So far as we know, the facts in this booklet have never before been pub- lished by any Patent At- torney. You are given very definite suggestions on "When and How to Sell an Inven- tion,” It also comes to you К. 115 Mechanical Move- ments Like These Besides many other features and facts there ate 115 differ- ent mechanical movements and principles in the big, 48-page Book below. Maybe there is just the idea you need to solve some mechanical problem. Use the coupon or write us a card or letter. FREE BOOKS wih c 68 PAGES of Facts and Pictures! VICTOR. J. Evans = Co. REGISTERED PATENT ATTORNEYS, MAIN OFFICE: 220-J, VICTOR BUILDING, WASHINGTON, D. C. Other Offices: 2610-В, Singer Bldg., New York 1445-B, Monadnock Bldg., Chicago mpire Bldg., Pittsburgh 1010-B, Hobart Bldg., San Francisco 736-B, Security Bldg., Los Angeles i Send me FREE copies of your books, ‘Patent Protection’? and “When and How to Sell an Inrention.'" : (Note: supplied by any of branch offices listed above.) Same books Street and №№........... ——— PCI 5 City or Town When Answering Advertisements Flcasc Mention August Modern Mechanix 7

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И | THAT HAVE { ОТЕУ < | BUSINESSES | № VENTIons do not have to be complicated to be profitable when Pat- ented. The 5c and 10c stores flourish on simple Patented products which are commercially suc- cessful. The zipper, safety pin, thumb tack, paper clip, collar button—all simple, yet familiar inven- tions—brought their inventors rich rewards. If you have a Patentable invention—act to protect it. Many of the most useful, widely popular, greatly

profitable, and extremely successful inventions have been very simple ones. You have only to look at the devices we have pictured here to realize how a simple invention may become a utility bought by a hundred thousand or a million people soon after it is produced. Don’t be afraid that the simplicity of your invention makes it valueless. The thing that you find so simple that you wonder why a thousand other people haven’t already done it is often the invention worthwhile.

HOW OTHER INVENTORS GOT STARTED — The list of men who‘succeeded in in- vention with only a poor boy's start isa very long and noble one. Poverty, hardships, lack of friends, distance from the market—these could not hold back Bell, Edison, Eastman, McCormick, Whitney and others. Everyone cannot succeed. But every man can try. Cour- age, sacrifice, and hard work may bring you a measure of the success these men had. Lack of mechanical ability is not a serious drawback. You can always get someone able to build a model, draw a detailed design, or otherwise mater- ialize your invention for you. The big drawback is discouragement. Your invention of a practical article or an improvement upon an old one should be patented NOW. Frequently

many of the thousands of applications filed in the U. S. Patent Office each year are for the same or almost the same in- vention. In such a case, the burden of proof rests with the last application filed. Sometimes a delay of even a few days in filing the application means the total loss of the patent LOSE NO TIME. The entire time of this large and ex- perienced organization is devoted ex- clusively to patent and trade-mark cases. We know the rules and require- ments of the Patent Office. We under- stand the technicalities of Patent Law. We can proceed in the quickest and safest ways in preparing an application for a patent covering your invention. Views of the man who used Patent Protection to amass millions and give per- fection to a new art—Photography—itself one of the greatest inventions.

3173 ADAMS BUILDING CLARENCE A.OBRIEN & HYMAN BERMAN FREE- BIOGRAPHY OF GEORGE EASTMAN WASHINGTON, D. C. Registered Patent Attorneys Before U. S. Patent Office 10 Accept No Substitutes?! Always Insist on the Advertised Brand!

If you have an invention The First Important Step in Securing a Patent is to obtain the services of a Regis- tered Patent Attorney. The U. S. Patent Office advises that you secure the aid of an experienced Registeređ Patent Attorney to prepare your statements. Establish the date of your invention as explained in our book and disclose your invention to him in correct form. He then makes a SEARCH of the Patent Office Records and reports to you on existing U. S. Patents which might bear on your invention, giving his opinion on the advisability of proceeding and filing formal application. Reasonable Fees—Con- venient Terms Don’t worry about finances, Our fees are very reasonable—we can arrange convenient terms of pay- ment. It is our custom to permit clients to pay for our services in in- stallments as the application pro- gresses in our office. See our Big Book for fees in obtaining Patent. It explains our arrangements clearly. Send for it NOW! that is patentable—and want to secure for yourself your inventor's sole right to profit from the invention—you can’t afford to lose time in ~ securing the protection of a U. S. Patent. Other inventors may be ~ working on the same invention right now. Should they develop this invention and file patent application before you do—the burden of establishing priority wil be upon you. Our Big Book—"Patent Guide for the Inventor"—will tell you the quickest possible way to secure Patent Protection for your invention, SEND FOR IT TODAY!

FREE RECORD OF INVENTION FORM Use our Free "Record of Iu- vention” form to assist you im recording the descriptive out- line of your invention and to establish the date of your in- vention. With it you can make a rough sketch of your invention and have it wit- nessed in а manner of value to you as evidence Should occasion arise, CLARENCE A.0°’BRIEN HYMAN BERMAN | 3173 ADAMS BUILDING WASHINGTON, Ю.С. REGISTERED PATENT ATTORNEYS BEFORE U.S. PATENT. OFFICE = Please send me at once your Big Free 48-Page Book, “Patent Guide for the Inventor" and your ‘Specially Prepared “Record of Invention" form. Also George Eastman Biography, "Inventor and

— HI - Business Man." This request does not obligate ше, a H МАМЕ ssasssvossorssessnanssnsscoucensnennannecononees — RI E | ADDRESS — ————M И я x

(Piease write or print plainly) Fee eee eel When Answering Advertisements Please Mention August Modern Mechanix 1

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This 25-passenger sightseeing boat (top) was constructed by Meigs, of Milwaukee, Wis. Lower photo shows how paddle wheels are attached to auto rear-end to propel the craft. ® Е WISH to remind all readers that letters and photos relating to projects completed in home workshops are always eligible for entry in the monthly Editor’s Workbench contest. There is no time limit, contributions receiving careful consideration as soon as received in the MM office. A monthly selection is made from the available photos, a prize of $5 being awarded to the reader who, in the opinion of the editors, sends in the most interesting photo and letter. Prizes of $3 each are awarded for all other photos published in the Workbench each month. Send in a photo and letter describing projects you have completed. ES A letter describing an unusual project was re- ceived from Н. С. Meigs, of Milwaukee, Wis., who 14 was awarded this month’s first prize of $5. His letter reads: Dear Editor: І thought you might be in- terested in a sightseeing boat which we built, so I am send- ing you photos of it. The boat has a speed of 12 m. p. h. and is very popular with visitors to the lake resort where the boat is kept. It has a draft of only five inches. The motive power consists of an automobile engine and transmission, The rear end of an auto is mounted on a frame- work so that wooden blades attached to the rims of the wheels can propel the craft, An automobile steering wheel is mounted by ihe driver's seat, having a large spool attached to the bottom of the shaft in the hold. A flexible cable runs from this to the rudder. H. G. Meigs. Reader Meigs is to be complimented for com- pleting such a novel and practical project. doe An award of $3 was sent to Wendell Lalley, of Monroe, La., for his letter and photo describing an attractive "gas" model airplane. He says: Dear Editor: I am sending you a photo of my “gas” model air- plane, Although I have built many rubber-powered models, this is the first “gas” model I ever tackled. It has a span of 7 feet, weighs 434 pounds, and is powered with a motor of one-fifth horsepower. Powered by a miniature gasoline engine of 1/5 horsepower, this model plane has a 7-foot wingspan. Wendell Lalley, who built the model, prepares to test its gliding qualities. I enjoyed the "gas" model article that appeared some time ago. Why not give us some more plans for “gas” models? I would also like to correspond with readers who are interested in such models. Wendell Lalley. Lalley's model looks like a well designed and well constructed one. We hope he will build the Bellanca gas model described (final installment) in this issue. doen This is the season for midget racers and a letter and photo received from James Webb, of Attwood, IH., telling of his speedy little auto was awarded a prize of $3. He says: Dear Editor: Enclosed is a photo of a midget racer that a pal and myself built. We want to tell you how pleased we are with your magazine for we get most of our plans from it. We are now planning to build the sailing cruiser “Buddy”. Good luck to MM. James Webb. While Webb neglected to supply details con- cerning the size, power, etc., of his tiny racer, we awarded him a prize on the basis of its appear- ance alone. ee Novel in appearance and utility is the project described in a letter from W. Posniak, of Tampico, Mexico, which won an award of $3. He writes: Midget autos still continue to intrigue MM workshop fans. This metal-clad racer built by James Webb, of Attwood, Ill, was awarded a prize on basis of its appearance alone. Music played by W. Posniak, of Tampico, Mexico, is picked up by the microphone lamp he built and emanates from small tadio set nearby, serving to entertain friends in novel manner. Dear Editor: І ат sending you a photo of the microphone lamp that I constructed, The device is 12 inches high with- out the light globe, the microphone ring having a 6-inch diameter with a center disc 376 inches in diameter, The photo shows me broadcasting over the mitro- phone lamp, the music being heard from a small radio set located nearby. W. Posniak. A microphone lamp provides much entertain- ment and constitutes a project that has ap, :71 to all radio fans. жж From Oteen, North Carolina, came a letter written by C. E. Self which was awarded a $3 prize. It reads: Dear Editor: I am enclosing a picture of a miniature railroad caboose that I built from discarded match sticks. I hope you will consider the project in the Workbench contest. The walls of the caboose are constructed of burnt match sticks. The roof is covered with the inside of the boxes that the matches were packed in. The wheels, steps, oil boxes, and draw heads are made of wood, whittled to proper shape. А Four bunks are features of the caboose interior, while four seats are located in the cupola, all of which are upholstered in leather. The windows are made from old X-ray plates. The caboose is 16 inches long and [Continued on page 16] 15

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4 8 4 d B by James Nevin Miller N THE city of White Plains, N. Y., not so long ago, more than 700 people suddenly were stricken with a mysterious ailment. City authorities thought the case was food poisoning. But just what kind, puzzled them. True enough, it was learned that all the vic- tims had eaten chocolate eclairs, cream puffs or Boston cream pies. However, none of the custard-filled pastries appeared to be “spoiled” although it was suspected that con- taminated custard filling might have been the source of the poisoning. Therefore, the city officials turned over samples of the pastry to the New York office of the U. S. Food and Drug Administration. These Gov- ernment experts in turn sent the pastry to the Washington laboratories of the Administra- tion. Very quickly, the Federal investigators, aided by local authorities cleared up the sit- uation by tracing the source of the spoiled food to one manu- Is your ginger ale fit to drink? J. B. Wilson, a Federal expert chemist (center), can tell you. He is shown conducting a test to de- termine the purity of a soft drink. Right—Spoiled sea foods are some- times offered for sale, but not if B. A. Linden, bureau bacteriologist, can help it. Samples of sea food are collected regularly and sub- mitted to laboratory examination. 30 The U. S. Food and Drug Administration constantly labors to insure the quality of food products. Through the efforts of its field in- spectots and expert [abo- ratory technicians, the Fed- eral bureau tracks down poisoned foods that consti- tute a threat to the nation's health. Left — A Federal chemist using special ap- paratus to determine the condition of canned goods. Modern Mechanix "His nose knows." This Federal agent can tell in a few seconds whether or not a shipment of powdered eggs is in satisfactory con- dition by merely smelling the product. However, to make doubly certain he will take along samples to be scientifically tested in Food and Drug Administration laboratories. АЦ to safe- guard your family’s health. ир August, 1937 facturing bakery іп Westchester County, seiz- ing and destroying all shipments sent out on the same day as the food poisoning outbreak, and identifying the deadly bacteria that caused the large-scale illness. Thrills are commonplace to these health sleuths, who are known unofficially as Uncle Sam's “Poison Squad." Their job is to guard the safety of your pantry by tracking down, armed with ingenious laboratory and field methods, outstanding cases where moldy fruits and vegetables, contaminated sea foods, spoiled canned goods, and doubtful-looking imported edibles offer a serious menace to the health of the nation. Just a few of the Poison Squad’s recent achievements, besides the settlement of the poisoned pastry case, include: the rounding up, during a three months period, of nearly a quarter million shipping cases of canned salmon, an apprecia- ble percentage of which was spoiled; the investigation of a food poisoning outbreak in Philadelphia somewhat similar to the one at White Plains; and the discovery of the cause of a strange “epidemic” of the “Looks mighty suspicious,” says this laboratory expert as he pro- ceeds with tests to determine whether a can of corn is safe for your palate or whether it is teem- ing with health-destroying bacteria. Poisoning from canned foods has decreased greatly since adoption of improved canning methods, but the Federal chemists are vigilant. 31

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At Langley Field, Va., the National Advisory Committee for Aeronau- tics maintains a mammoth wind tunnel in which a completely assembled airplane can be tested to determine its aerod y- namic qualities (above). уеп by engines pro- ducing 4,000 horsepower each, two 351^-foot pro- pellers blast the air past the airplane's controls at velocities up to 118 m.p.h. The tunnel is 43412 feet long, 222 feet wide, 97 feet high. by Don Glassman OBODY knows how long the present speed marks can endure. In a world of sudden change and far-reaching discoveries, the mortality rate of speed records is high. All the racing heroes want to hang up un- beatable records. Gradually, but surely, they have been approaching the speed beyond which they cannot go, for there is a law which no speeder can break. Nature laid it down without consulting us. A 575-mile per hour speed limit for mod- ern airplanes was recently determined at the Langley Field, Va., "super-speed" wind tun- nel by the engineers of the National Advisory Committee for Aeronautics. With present designs, you may be sure that no man will surpass that figure. Beyond the 575-mile critical speed, forward motion is checked by a “shock wave” of 36 Major James (“Jimmie”) Doolittle, famous American speed and stunt pilot, conducted risky flight teste that helped determine the ac- celeration speeds of various aerial maneuvers. Modern Mechanix A too-sudden change in acceleration while testing a new Navy plane is believed to have caused Jimmy Collins, well known test pilot, to become uncon- scious, resulting in the crash that caused his death. turbulent air that travels from front to rear of an airplane wing and wastes the energy. Result:—the wings lose their lifting power. In engineering language this "shock wave" of air is called the "compressibility burble." The violence and turbulence of the burble August, 1937 In the Macchi-Castoldi-72 seaplane shown above, Lieut, Francesco Agello, Italian ace, set a world's speed record of 440.67 m.p.h. in 1934. The plane's 3,000 h.p. Fiat engine had tandem propellers re- volving in opposite directions to eliminate torque. causes a severe drag on the wings. The power that was intended to support the wings is spent as useless heat. The burble is not a factor in airplane speed until the free stream of air approaches the velocity of sound—750 miles per hour. With each increase in speed, the burble travels farther from front to rear of the wing, and dissipates still more energy as heat. If we could travel beyond 750 miles per hour sound waves could never catch up with our flight. That would be “supersonic” speed. These facts hold good for the types of air- plane wings in use today, and it is highly probable that a corresponding burble could be found for every common form of trans- port if desired. . With suitable wind tunnels, опе could de- termine the critical speeds of ship, train, auto, and dirigible forms, but at the present stage of development there is no point in making such experiments, since all these transports are still very far below their respective criti- cal speeds. With the airplane, however, the speed record now held by Italy stands at 440.67 miles per hour, only 135 miles per hour below the critical speed. The Speed School at Densenzano, Italy, has specialized in the training of crack speed pilots for years. Premier Mussolini told these men to work for a velocity of 600 miles per hour. In the light of present knowledge about 37

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the burble, the Italians seek to invent a new type of air foil with a higher critical speed. And that is not impossible. What about man’s own engine? Do our bodies have a critical speed? As I sit on my chair, I am being whirled through space at the dizzy velocity of 1,140 miles per min- ute—the earth’s speed. It is said that 36 dis- tinct motions are involved. Nobody feels any ill effects from this pace, although it is far beyond the critical speed of the airplane. There is quite some difference, however, between traveling through space with Mother Earth and traveling at 400 miles per hour in an airplane. In our joy ride on the earth we do not turn sharp corners or experience sudden accelerations. Traveling along a straight line at any speed seems to make little difference to our bodies. But the experience of speed pilots tends to show that taking curves at high speeds is something positively annoying, and probably injurious, if carried to extremes. у The “blank out” experienced by speed and test pilots is a sensation caused by the blood rushing away from the head, creating a short- age of oxygen. In highspeed aerobatics, the centrifugal force makes one’s body feel much heavier than it actually is, and one finds it difficult to raise an arm or to stand up. To counteract this sudden drain of blood from the head, test pilots wrap their bodies in bandages, or tight belts. Sudden acceleration and quick change in direction are the chief difficulties man has to contend with when attempting to set new 38

Designed, built and flown by Comdr. Frank Hawks, noted speed pilot, the airplane shown above lived up to its name—Time Flies—by attaining speeds exceed: ing 300 m.p.h. before it was wrecked in landing. The eraft featured an air-cooled engine of 1,150 horsepower. seaplane (right), ajor Alford Williams hoped to win the Schneider Cup for the U. S. in 1929. Unfor- tunately, the plane was damaged be- fore the race and could not compete. | In this Mercury Speeding along a straight path seems to have no ill effect on the human body, but a sudden change in direction or acceleration, as sketched at left, causes a speed pilots mind to "blank out." X ~A | ps |

Exactly 7 hours, 28 minutes and 27 seconds after he zoomed aloft at Los Angeles, Calif., in his specially built speed plane (above), Howard Hughes, wealthy sportsman pilot, landed at Newark, N. J., having averaged 332 m.p.h. for the 2,490-mile flight. Hughes is shown walking at the tail of his plane as it was wheeled into a hangar. Below—Chart showing the steady climb in speed records since 1910.

A | В E 1950 zi < 2. 33. i 21 1945 : zi] | g^ A 1940 Pg | L-41 о. 440 pe” | Ш 1934 —- 1 ES M В 357 d . |1930 $4 | Е. 278 | zi 1925 in | fat 194 | 1ш 1920 i гыг iz i 1915 126, — i | 2 А " 1 speed records. То visualize what hap- ВЕ ee $ ; i ion: 100 200 300 400 500 pens in a case of extreme acceleration: [cies 6 ase Sed ЕЕЕ Em

if an airplane could take off with the acceleration of an automobile piston, the pilot's effective weight would become 20 tons and his body would flatten like a pan- cake. A burst of speed can break a man's neck unless he has a solid head rest. A free body falling in space falls 16 feet in the first second of its descent and gathers speed at a rate of 32 feet per second. This rate of fall is called one-gravity. If the ac- celeration is increased to about three times the normal acceleration of gravity, you ap- proximate the takeoff speed of an airplane launched from a catapult. An acceleration of three-gravity is 100 times the normal ac- celeration of a steam locomotive. An auto- mobile starts off only one-sixth as fast as the catapulted airplane. Some interesting discoveries in the field of [Continued on page 122] 39

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The nose already a mass of burning wreck- age, the flaming tail of the giant German Zeppelin Hindenburg settles to earth after exploding while landing at Lakehurst, М. J. Naval air base on May 6th, 1937. O MOST of us Earth-bound mortals, there is something singularly terrifying about death from the sky. The only terror equal to it is death from fire. When the two horrors are combined in one spectacular disaster such as overtook the airship Hindenburg, we of panicky imaginations are prone to ignore facts, prone to throw up our hands and cry, “That is enough!” Yet the men who must face this fate again if airship progress is to continue are far from ready to cry enough. Every uninjured sur- vivor of the Hindenburg crew hurried back to Germany, that he might get a berth in the next great Zeppelin, the LZ-130, rapidly nearing completion. And this attitude is not mere heroics. Air- ship men really believe that the rigid dirigible is a reliable means of transporta- 42 tion. Disasters? Of course they encounter disasters. “What mode of transportation does not?” is their argument. And they make a pretty good case for the airship, too. They will tell you, for instance, that dirigibles have carried more than 250,000 paying passengers, yet up until the time 12 of the 36 passengers on the Hindenburg’s last Modern Mechanix Е * s Ciouds of smoke still rise from the twisted steel frame (above) of the ill-fated air- ship as rescue workers ar- tive to search for possible survivors, The Hinden- burg had just completed her 21st crossing from Germany to the U. S. when the tragedy that caused the world to gasp in horror oc- curred. Right-—Aerial view of the airship's charred re- mains at Lakehurst base. August, 1937 ds Prove That t. n t A by Bob Gordon trip were killed at Lakehurst, not a single passenger of any airship had ever lost his life. You don’t believe this? Well, here are the figures. On the three commercial Zeppelins built and flown before the World War, 37,250 passengers were carried without even a serious injury. Immediately following the war, the Nordstern and the Bodensee carried several thousand passengers before being seized by the Allies. .Goodyear blimps have carried 180,000 passengers in perfect safety, while the Graf Zeppelin and the Hinden- burg carried 16,000 on regularly scheduled runs. As to crew casualities, aside from one blimp pilot and two members of a ground crew killed when their ship was wrecked in a violent gale, after being torn from its moorings, no crew member of a commercial ship had been killed before the Hindenburg carried 24 of its 66 members to a fiery death. There have been only 156 large rigid dirigibles built in the history of the industry. Twenty-nine of these were built and flown in Germany before the war. Several of the first ones were wrecked, but no one was killed. Count Zeppelin, a balloon observer for the Union Army in the American Civil War, devoted practically his entire lifetime to building and flying

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Thwarting human ex- planation for centuries, homing pigeons mi- raculously return to lofts many miles away. ACING the homing pigeon is a very in- teresting sport, and yet there are many people who are unaware that such a sport exists although it is one of the leading sports in England, Belgium, Germany and other European countries. To give one an idea of the vast number of racing enthusiasts par- ticipating in this sport in these countries as Modern Mechanix by W. R. Stamford Shown above is the liber- ation of almost 1,000 pigeons at Wilmington, Delaware, for a race to New York. A blue checker hen fed the field, making a flight of 112 miles in 2 hours, 6 minutes. Right—- "Swiftwing, blue checker cock, winner of the Chat- tanooga National Race in 1936. Owned by F. E. Gorely, of Washington, D. C., this pigeon flew 534 miles at average speed of 1036.42 yards per minute. August, 1937 ae Lnd well as the United States, the following figures are presented: s There are some 300,000 fanciers in England, 35,000 in France, 350,000 in Belgium, 10,000 in Germany, 20,000 in Holland, 8,000 in Italy, 3,000 in Portugal, less than a thousand in Switzerland, about a thousand in Austria and 10,000 in the United States; a total of some 800,000 fanciers and this is not counting the fanciers in Brazil, Spain, Poland, Cuba, etc. Mons. Hansenne, a Belgian who lived in Verviers, was, before his death, a most noted racing pigeon fancier. His fame and reputa- tion as a breeder are known throughout the racing pigeon world. During the last three years of his life, he averaged $15,000 a year from the sale of his birds and their winnings. One of his favorite racers, “Good Blue,” won $10,000. J. W. Logan, an Englishman, is known to have sold a pair of his birds for over $1,400. A few years ago a Dr. Anderson, of Scotland, - paid to Mons. Stassart, of Belgium, $1,000 for “Epinard,” one of the greatest champion birds he ever owned. European birds and ‘their progeny have performed wonderful feats, but some of the records of the U. S. birds are really extra- ‘ordinary. The conditions they must fly under in this country are very trying. On the Pacifie coast they have to contend with the terrific heat blown in from the desert, flying over the mountains four to five thousand feet high. Over these mountains they must come on their way home from a race, as there is no easier way round. In the central part of the country they encounter dust storms, strong head winds and intense electrical storms, which arise out of nowhere. Along the Eastern seaboard they have to fly over the high Alle- gheny Mountains which are nesting

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grounds for fierce hawks. Is it any wonder why the racing pigeon fancier becomes so attached to his little feathered racers? How are racing pigeons trained?) When young racing pigeons are 7 to 10 days old a seamless aluminum band is placed on one of their legs. As the bird’s leg and foot grows, the band will soon be impossible to remove. On the band is stamped, in raised letters and figures, the initials of the organization to which the fancier belongs, year of hatch, initials of the fancier’s club, and a number. At 12 weeks of age, when these young 52 Sealed timing devices Vero are used by pigeon fanciers’. clubs. When a bird “homes” in a race, the fancier removes a countermark from its leg and places it in either of the timer’s two holes. Turning a dial locks the countermark in timer and stamps the time on slip. The important parts of a “stop and start” timer are shown above. When timer is to be used, the nut A is unscrewed from post. Both clocks are wound and case B is then slipped over timer and nut A replaced, a string and seal being attached to it. Re- turned pigeons’ countermarks are inserted in the holes. The manner in which pigeons are countermarked before a race is clearly shown in the photo at left. Notice how rub- ber countermark is stretched to allow the bird's foot to be placed through it. When the handle is released, the counter- mark automatically flies off Prongs onto the bird’s leg. Below — Countermarked, the bird is ready for shipment to the point of liberation. racing pigeons—called youngsters—have be- come settled to their loft, they should be exercised 30 minutes or more each time they are let out of their loft by their owner. This exercise strengthens their wing muscles, de- velops the respiratory organs, and gets them familiar with the country surrounding their loft, developing their instinct. .Birds that are let out to exercise hungry should *'trap" into the loft when they alight after the exercising flights. “Trap” is the racing pigeon fancier's word for birds enter- ing the loft. If the birds were put out to exercise not hungry, they would soon get into the habit of loafing on top of the roof once they lit. This is the worst habit a racing pigeon can have, and unless it is corrected as a youngster, the bird is of no use to its owner. A pigeon race cannot be won if the bird sits on the roof when homing from a race. Young birds should be ready for their first training “fly” at the age of four or five months. They are taken about a mile away from their loft in baskets and p liberated. On these “flys” the birds are taken away hungry, so that when they return to their loft they will "trap" „Ф into it. The above dis- á tance is gradually in- 4 creased to 15 miles, Д then to 25 miles, ete. After the birds are thoroughly trained up to 60 miles, they will in most cases be ready for their first competitive race, which is 100 miles. Old birds W. O. Maybury, said to be the oldest pigeon flyer in » Pittsburgh, Pa., shrewdly in- s start of a race. The physical condi- tion of a bird is only one of the factors that worry racers. Winds and type of terrain en route are equally important. spects his champion bird before CM that have been inactive during the Fall, Win- ter and early Spring months will need a few training flights previous to the “old bird” race, to freshen their memory and sense of direction, but they, like the young birds, must exercise during the races. There are two series of races every year for the fancier, provided he lives in a city where pigeon races are conducted. These series are known as the "old" and "young" bird races. The old bird races are for birds bred previous to the year in which they are to compete, while the young bird races are for birds bred the same year in which they are to compete. The old bird race schedule consists mostly of 100, 200, 300, 300, 400, 500, 500-mile hops and generally ends with one 600-mile race, although special races are sometimes held by clubs for longer distances such as 700 and 1,000 miles. This series of races starts about the first of May and

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Just what prompts and enables pigeons to return to doors are sealed shut with regulation club At Fort Monmouth, N. J. the lofts located hundreds of miles away has never been U. S. Army Signal Corps maintains satisfactorily explained. The birds are taught to be- seals and sent to the railway express station. lofts, (below) for breeding and lieve that food can only be obtained at the home loft. ЕЕ training. of Pigeons, During the but what guides them unessingly over mountains and After the shipping costs for the baskets are . Mihiel drive in the Worl ar, lains to their respective lofts оѓоз on pages i - 567 birds were released with mes- 54:55 by courtesy of the U. S. Army Signal Corps.) paid to the express agent by the club secre sages, attesting to their importance in large scale military operations. tary, they are then placed in charge of the convoyor who directs the placing of the bas- kets in the railway express car, which has been hired for this purpose by the various clubs. A convoyor is a person sent with racing pigeons whose duty it is to liberate them the morning of the race, weather per- mitting. On the long grinds such as the 300, 400, 500 and 600-mile races the birds are fed and watered in the baskets by the convoyor at the race site station on the day previous to being liberated. How a liberation is conducted and prepared is told in The American Racing Pigeon News by a man who has convoyed Pittsburgh, Pa., pigeons for almost two decades: "About four days before I make a trip [Continued on page 124] Homing pigeons were used by both sides during the World War. Pre-eminent was the work of “Cher Ami," shown above. Lib- erated with an important message during intense machine gun and artillery action, this bird flew 25 miles to deliver its mes- sage. Examination showed that one leg had been amputated and its breast pierced by a machine gun bullet. The message tube, intact, was hanging by a ligament. Below-—“'Spike,”” another battle veteran. continues until mid-summer. The young bird race schedule generally consists of 100, 100, 130, competing birds must be 200, 200 and ends with a 300-mile countermarked by this race, this series starting a few weeks after method, the old bird schedule is completed and last- The countermarked bird is ing until the Fall months. Short races are then placed in the club's ship- flown in most cities on Sunday, and the ping basket. These baskets longer ones on Saturday. are of different styles and hold Birds that are entered in a race must be about 50 birds with space to countermarked at the fancier’s club house feed and water them when on the night preceding the day of the race they are on the longer races. on short races, and two nights ahead for Straw or shavings are placed longer races. A small charge is paid by on the bottom to keep them in the fancier for each bird entered in the race, a sanitary condition. When a countermark being received for each bird. the shipping baskets are filled A countermark is a rubber ring with two with countermarked birds, the different numbers stamped upon it—one * number inside, the other outside. The coun- stubs, if he is flying more than one bird, and sealed. All The two photos at the termark is attached to a stub of paper called the countermark stub, which has the same numbers staniped upon it as the marker itself. When a bird is countermarked, the countermark is placed on the bird's leg (by a hand-operated appliance made for this purpose) and at the same time the bird's band number is written on the stub from which it was removed. This stub is then placed in an envelope (whieh has the fancier's name on it) together with other Modern Mechanix right show a close-up of one of the lofts at the Army Signal School at Fort Monmouth, N. J., and a series of the Army's extensive pigeon raising and training quar- ters. The pigeon's mili- tary value is established, the Japanese army main- taining 20,000 of them. Experiments are being conducted in which the pigeons wear tiny cameras strapped to their breasts, timed to take photos at regular inter- vals during their flights. August, 1937

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sS HE young inventor looking for new worlds to conquer would do well to in- vestigate the vast but little-explored domains of electrochemistry. Hundreds of new prod- ucts and inventions difficult or impossible to discover during the countless ages of the past with mechanical skill alone are today readily possible through the combined power of electricity and chemistry." Thus Professor Colin G. Fink of Columbia University presents an invitation — and a challenge—to inventive minds everywhere. He sees no reason why young men with courage and imagination should not play an important part in future scientific development and he believes his own field offers un- limited possibilities for advancement. When I called on him in his laboratory at Columbia, I told him the readers of MopERN МЕСНАМІХ were particularly interested in needed inventions and I asked him to name a few of the problems which, in his opinion, demanded the greatest attention at this time. "Our basic engineering metal is iron," he began. "It is the most abundant and has the most valuable properties, such as high tensile strength, high fatigue value, etc. The world produces more of iron and steel than all the other metals put together. For every 100 tons of iron and steel, only 2 tons of copper are preduced—and copper occupies second place in quantity and importance among metals! “With ever rapidly increasing utilization of steel in railroads, automobiles, bridges, buildings, high transmission towers and other articles, the problem of eliminating rust and protecting steel products and costly structures against corrosion is undoubtedly the biggest problem confronting the chemist and engi- neer. Metals rust as a result of electro- chemical action. If we eliminate this, we eliminate rust! The young men of the com- ing generation will solve this problem; marked progress towards a solution already has been made. “We are also badly in need of an electric source of illumination suitable to our eyes which will operate at 90 per cent or better in 60 Aninterview with Professor Colin G. Fink Head, Division ofElectrochemistry Columbia University by Richard H. Parke “Scientists are baffled in their efforts to release gold from sea water cheaply. Through the application of electrochemistry. Pro- fessor Fink believes that the growth of fruit and. vegetables can be greatly incteased and that metals can be prevented from efficiency instead of less than 10 per cent as at present. Electricity is modern man's in- dispensable and versatile servant; eliminate it and civilization would drop back 100 years. But, although electricity has increased the efficiency of old hand-operated machines and Modern Mechanix Photo-electric generator celís mounted on roof tops will be used to sup- \ ply electricity \ for homes, pre- dicts Dr. innumerable devices a thousandfold or more, it has so far not accomplished anything near as much for artificial light. “The tungsten lamp in the average man's home furnishes but 5 cents’ worth of light for every dollar's worth of electricity. The August, 1937 rusting and corroding. | Winner of the Perkins Medal of the Society of Chemical Industry and the Acheson Gold Medal for outstanding accomplish- ments in the field of elec- trochemistry, Professor Colin G. Fink now heads Columbia University’s De- partment of Chemical En- gineering. Discoverer of a platinum substitute used in manufacturing incandes- cent lamps, Dr. Fink seeks lamps that will be ninety per cent efficient instead of ten per cent as at present. balance, 95 cents, is lost as useless heat. Modern homes and towns need a lamp that will furnish at least 90 per cent light and only 10 per cent heat. The little firefly, or glow- worm, operates its light at figures even better than 90 per cent. The lamp of the future may very well be based on principles similar to those of the firefly’s glow. “A simple means of electrically controlling rainfall—keeping it out of the cities—is an- other important problem to solve. The Cottrell electrical precipitation process is used at factories all over the world to precipi- tate fumes, dusts, smoke and vapors of all kinds. It requires very little development to apply this same process to the precipitation of rain in localities outside of towns and cities. Millions of dollars’ worth of shoes, clothing [Continued on page 118] 61

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RESTOCKING The OCEAN | Federal Bu- reau of Fisher- les takes un- usual mea- sures to bal- ance inroads made by com- mercialfishers. HAT is probably the largest undertaking of its kind in the entire history of man has recently been completed, for, fan- tastic as it may sound, the ocean has been restocked by human efforts! This gigantic task was accomplished by the Federal Bureau of Fisheries which states, in part: “If all of the fish planted by the Bureau in the past fiscal year in the Atlantic and Pacific Oceans and in lakes and rivers were to grow to maturity and be caught, almost every man, woman and child in the United States could have approximately six pounds of fish every week for a solid year from this source alone.” The total was slightly over eight billion, and was composed of eggs, fry and finger- lings of forty-three different salt and fresh water species from eighty-four hatcheries in thirty-eight states. But why go to all this trouble to put fish into the sea? Restocking streams and lakes seems reasonable, but the ocean is a vast place, covering three-quarters of the earth’s surface. Won't the salt water fish wander off to Europe or South America after they've 62 been planted? How does the Bureau know that there will be any benefit reaped planting fish eggs and fingerlings in the boundless sea? The answer is, and most definitely, that the Bureau does know what will happen to a good majority of the eggs and fish it re- leases in Old Father Neptune's domain. This knowledge came about after long and ar- duous study of ocean currents (known as oceanography) and years of so-called "tag- ging" of various fishes to learn their migratory and spawning habits. The story of fish tagging is a tale in itself, but suffice it to say that by identifying fish by attaching tags on the fleshy part of the tail, or clipping certain fins and several other methods, the Bureau has unquestionably established many facts, such as: large quan- tities of codfish lay their eggs in Massachu- setts Bay, and ocean currents carry them to the famous Georges Banks, 150 miles away, Modern Mechanix Unloading a catch from one of the many fishing boats supplying the colos- sal public demand for this popular food. Nets make large scale catching possi- ble in a minimum of time. Because of the relentless demand for salt water fish, restocking is becoming necessaty to prevent extinc- tion of popular species. just in time to be hatched; that weakfish, a valuable commercial fish of New Jersey, go south to Chesapeake Bay and the Carolinas during winter to spawn; that salmon, when- ever possible, return to the identical stream where they were hatched to spawn and die. These are but a few instances of what the Bureau has learned about the. habits of the denizens of the deep. So, when it plants six bilion eggs and young fish in the At- lantic Ocean, you may be sure then an ap- preciable amount of them will end their careers in the frying pan of Mr. and Mrs. America. With rare exceptions, our native salt water fish do not leave our shores. Backing up this statement are the scien- tists of the Rockefeller-endowed Oceano- graphic Institution of Woods Hole, Mass., whose studies of ocean life have extended in the Atlantic from Labrador to the Equa- tor. They state, without qualification, that August, 1937 Тор of page—-Large numbers of per- sons now enjoy deep sea fishing on one of the many boats used for this pur- pose. With rods and reels, dozens of fishermen are taken to fishing grounds not usually available to the individual Below—One of the reasons why fis ingis one of the most popular pastimes.

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paratory to planting in suitable spa Banks, off the New England coast. grounds on the Georges Six billion eggs were planted. A Bureau rescuing unit salvaging fish trapped by overflow waters More than 47,000,000 fish were saved of the Mississippi River. in this manner during the past year and replanted up-stream. Removing fish from overflow waters during floods, for transfer to other sections of the country- This work saves many million fish which might have been killed when the flood waters subsided, marine life hardly exists over 200 miles from shore. In other words, our salt water fishes remain close to home. The Bureau of Fisheries scientists know where and when various fish spawn, where they migrate to (when they do migrate) and act accordingly in their vast propagation activities. Naturally. you're not going to eat six or seven pounds of fish a week, unless you’re more than crazy about sea-food or live in Alaska. So why this extensive planting of fish—the largest that the Bureau of Fisheries has ever accomplished in one year? Take one of our best known. com- mercial fishes—the cod, for example; for the past several decades we have consumed on an average of one hun- dred million pounds annually of this single staple marine product and practically all of it comes from the New England region alone! That gives an idea of the amount of fish we eat. Bear in mind the dozens of kinds of fish on the market today from our diversified and many fishing grounds, and it will be readily agreed that, taking the cod as an example, the American public consumes a staggering amount of fish. By far the greatest fisheries in the United States are those off the New England coast. They extend, roughly, from the east end of Long Island Sound to Nova Scotia and the New- foundland Banks. These grounds are more extensively fished than any others in the entire country. Huge fieets of fishing boats leave almost daily from Boston and Gloucester, Mass., and Portland, Maine, as well as numerous smaller ports, (The fish pier at Boston is the largest of its kind in the world devoted ex- clusively to receiving and packing fresh fish.) The aggregate catch of these ports is colossal. Better equipped and more nu- merous boats are bringing in sea- food delicacies at such a rate that nature, lavish as she is, cannot keep up with the inroads man is making. Today the fishing fleets must make longer and longer trips to get satis- factory hauls. Several important species are becoming alarmingly Modern Mechanix scarce. Yet the demand for cod, haddock, flounder, mackerel and other salt water products goes on re- lentlessly. This depletion does not confine itself to New England alone, for, according to Bureau scientists, it is true in varying degrees in prac- tically all of the nation’s commercial and sports fishing areas. Perhaps the public does not realize the situation, but five years ago the Bureau of Fisheries foresaw that unless something drastic was done, our fisheries would within a short time face an economic crisis. This huge industry, with its ramifica- tions, employing many thousands of workers, might conceivably cease to exist—and more than that—a tre- mendous source of food be denied the entire nation. What to do? Only one thing— increase the number of fish in the ocean and inland waters—somewhat of a job, especially the former. Whereupon two great hatcheries of the Bureau, one at Gloucester, Mass., and the other at Boothbay Harbor, Maine, began collecting eggs from fish caught during the spawning sea- son. Knowledge of the proper way to treat and handle the precious eggs grew with experiments, till today, the Bureau of Fisheries announces that it has planted the greatest num- ber of eggs and fingerlings of salt water fish that it has done in any one year in its entire history. Close to six billion potential fish dinners are now on their proper beds on the great Georges Banks and along the coast of Massachusetts and Maine, either in the fingerling and young fish state, or in the form of eggs, ready to hatch. A most stupendous ac- complishment! Cod and flounder head the list, the former with over two billion and the latter with a billion and а half. Pollock, a valued commercial fish re- sembling the haddock, makes its initial artificial spawning bow by placing third with over a billion. Haddock is represented by a mere 500 million, while the neglected mackerel has only an insignificant 100 million of its progeny planted [Continued on page 122] August, 1937 sh being disinfected at one of the Federal Bureau After these fingerlings are immunized against disease, they are released in waters suitable for their healthful growth. g bass fry in fresh water lake. More than four million were deposited in lakes and rivers throughout the United States in the largest propagation program ever carried out by the bureau. Bureau of Fisheries field man unloading fingerlings into a container preparatory to planting them in suitable water. There they will grow to maturity and stem the flow of many species toward extinction.

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many people hurriedly purchase dwellings in desirable and rapidly filling communities and learn only afterward that the down, pay- ment and the monthly installments do not cover a really complete home; they dis- cover to their dismay that the “ex- tras” add up to a considerable sum, some- times an appreciable fraction of the pur- chase price. Builders have found that average prices of $5,000 for a one-story house and about $6,500 for a two-story structure draw the greatest number of prospective TTRACTED by the low prices made pos- sible by large-scale, government-spon- sored production, thousands of families of modest income are buying homes throughout the country. The summer of 1937 will see a building boom of unequalled size, according to realtors everywhere. The advertised: prices of comfortable five- and six-room houses appear so reasonable, and the terms of payment so convenient, that Right—A stout fence to keep children and animals off the lawn is good insurance for grass and flowers. Costs vary according to type and general construction. Above— Window screens for summer use ' are important comfort aids to the home owner. During the cold months, the screens should be replaced with storm win- dows, thus eliminating "cold zones" in the rooms. Right—A typical example of what can be done with an average cellar. Covered' walls, floor and ceiling add a toom to the house, suitable for any use. (Photo courtesy American Radiator Com- pany's Castles Underground) 68 buyers, mainly because the carrying charges on these sums are smaller than rent for equivalent apartments. Such houses cannot include numerous accessories and attach- ments if they are to conform to the technical standards established by the government and still earn a legitimate profit for the builders. The latter therefore emphasize the minimum prices and simply do not mention the ex- iras. If you are in the market for a home, do not hesitate to ask many questions of the builders you meet. Start with the heating system, : which is undoubtedly the most important single mechanical ele- ment in a home. You wil be surprised to learn that standard equipment for the great majority of small houses is an old- fashioned coal furnace, Left—Rock wool insula- tion, shown being in- stalled in a top floor ceil- ing, is an efficient means of reducing fuel costs in winter and for lowering temperature in summer.

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DEMONSTRATE STEAM’S HEAT TRANSMISSION QUALITIES—-Water in a test tube is boiled and the steam car- tied into a glass of water by means of a rubber tube. In a short time the water in the glass will be heated although the condensed steam has added very little water to that already in the glass. Steam in addition to being hot gives up a large amount of heat when it changes to water. A REVOLVING COPPER DISC—A copper disc will revolve between the poles of a magnet if direct current is allowed to flow from center to edge or edge to center of the wheel. A drop of mercury supplies the contact for the current at the lower portion of the rim although very light contact with a piece of wire also will work. The disc revolves because the part of the disc carrying current between the magnetic poles is constantly being pushed aside by the magnetic field. 72 Modern Mechanix DILUTE HYDROGEN EXPLODES— Fill two balloons with hydrogen. Ignite one as shown in the photograph. It will blaze up with a puff of smoke. Permit the other to stand for several hours and then ignite in the same manner. This time it will ignite with a sharp “bang,” indicat- ing that air has mixed with the hydrogen. MIRROR REFLECTS HEAT—To demonstrate heat reflecting qualities of a mirror use metal one instead of glass. A piece of shiny tin will be satisfactory. If a piece of glass is held in front of the heater, it will be found that it will stop the heat rays just as effectively as did the sheet of opaque material. August, 1937 BALLOON LOSES HY- DROGEN FASTER THAN AIR—The bal- loons in the photograph originally were the same size. After fifteen hours they were as shown. The small one contained hy- drogen and the large one air. The hydrogen mole- cules pass through the rub- ber with less difficulty than air molecules because of their being smaller in size.

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76 tion that is hard to beat. As to the equipment necessary, it is far less elaborate than is im- agined by the average workman. Of course, each worker in the field has a great many special gadgets and pieces of equipment which he believes essential. In truth, they are essen- tial only to his particular technique. One of the purposes of this series of articles is to strip telescope making to its true, and remarkably simple, essential. On the other hand, it is obviously impos- sible to cover the whole field of telescope making and optical calculations in articles of this length. The broad outlines will be sketched and the major steps described. For the rest, the worker will have to rely on his own good judgment and understanding of mechanics to get him over the minor difficul- ties which are bound to arise. The worker who wishes to study the subject in more de- tail is referred to the numerous books on the subject. i During the grinding, polishing and testing ‚ of a mirror, the simplest home workshop, so long as it has an, assortment of common tools and a good, solid workbench, will be sufficient. The only truly essential thing is a good lock on the door, with the key reposing in the worker's pocket. Mirrors are very sensitive to heat, cold and shock. They do not make ideal playthings for Junior. The workshop must never be dusted while a mirror is in process of grinding. Particles of the rough grind- ing abrasive will Left——Mirror being polished by hand. The table shown is set in a heavy movable base. However, a barrel is a good substitute for the table. For grinding, a glass “tool” is used instead of the pitch lap shown. Below—Ex- amining the surface of the mirror for pits. A reading glass is used for this test. An out-of-focus sun spot reveals pits and scratches on surface of mirror. A drawing of the mirror grinding machine. Power obtained from the electric motor is transmitted to e two turntables through the shaft A. Gears reduce the speed to sixty r.p.m. for the eccentric table S, and to two r.p.m. for the grinding table G. The slot I makes possible adjustment for the eccen- tric motion of the arm Н. This arm is hinged at J to allow removal of the mirror К from the “tool” І. The bel for connecting the two pulleys is not shown. M is a counterbalance for adjustment of pressure of mirror against "tool." Above — Diagram showing method of grinding mirror by band. А "plumber's friend" is used as a handle for the mirror. A glass “tool” is under the mirror. Blocks of wood are used to hold the “tool” in place dur- ing grinding operation. | REFLECTION OF SUN ` Diagram showing rough test for de- termining the focal - length of a mirror. An image of the sun is brought into focus on a white board or wall; the distance between the image and mir- ror is focal length. invariably get on the surface of the mirror and scratch it. Therefore, women with dust- ing apparatus must be relentlessly kept out- side. The only known way to do this is with a lock. "EL If it is planned to place the mirror in one of the more elaborate metal mountings, cer- tain power tools will be found necessary, or at least a great help. This however, will be discussed in the third of this series of articles, which deals with types of mountings. There is one other necessary piece of equip- ment—a mechanical bent of mind on the part of the workman. This problem, however, usually solves itself, as anyone interested enough in telescope making to attempt it seri- ously is almost always at least a passable workman. The following items and equipment are necessary to begin the grinding and pol- ishing of a six-inch mirror. (A mirror of that size has been chosen for this discussion because it is simple to grind. If it is designed to have a speed of F. 11, it need not be made parabolic. However, mirrors from four to ten inches may be ground with only slight variations in the methods described in this series of articles.) The items in this list are the bare minimum necessary to attempt to grind a mirror: M M

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НЕВЕ are few subjects, if any, that create more general interest than the weather. If you are like the average American, the first item you read, when you pick up the evening paper, is the general forecast of weather con- ditions. The study of the weather in all of its many phases provides an interesting hobby that can be pursued by any man or boy. A recording rain gauge is only one of the many homemade weather instruments that will find practical application in the amateur meteorologist’s observatory, but the building of this interesting device will definitely prove the merits of this hobby and spur you on in making other forecasting instruments. The rain gauge, about to be described, not only indicates, graphically, the exact amount of fall, but shows, directly on the graph cylin- der, when the rain began and when it ended. Though its accuracy is comparable with the most costly of laboratory instruments, this recording gauge can be built for less than stwo dollars. Procure, first, a one dollar alarm clock, with a three-inch diameter face, to be used for rotating the recording drum. Remove the glass face and also the hour and minute hands, then to the minute hand rod, solder a strip of metal about 3% inches long with the ends bent up about 34 inch at both ends, at right angles to the face of the clock. Cut a disc from stiff cardboard 4 inches in diameter and to it fasten two right angle clips of 44-inch flexible steel. They should be placed opposite each other, 334 inches apart and fastened to the cardboard with small bolts. The clips serve to hold the re- cording drum on the face of the clock. Punch two holes in the cardboard disc for 80 by John R. Myers OLD ALARM CLOCK WITH STI TO PROTRUDING HAND ROD BEND UP METAL STRIP. 3/47 ON EACH END TURNED UP ENDS OF. METAL STRIP GOES THRU CARDBOARD . CARDBOARD _ ТО FIT OVER CLOCK FACE COUNTER- WEIGHT WIRES HERE -Ht FROM END HOOK FOR SPRING CROSS ARM 5" X 1/4" X 17164 1/2" SQ, BLOCK OE BALSA WOOD TO y HOLD PEN DRUM- CLIP 3/16" HOLE FOR РЕМ Y. The rainfall for a given period is recorded on a cylinder tc which is fastened a graph paper chart. An alarm clock, from which the face and hands have been removed, is fitted with a metal strip, soldered to the hour hand, to permit attachment of the chart drum, as shown above. Details of pen holder, drum clip and disc for supporting the chart drum are also indicated. the upturned ends of the strip soldered to the clock shaft. The cardboard disc is next set in place with the two metal ends pro- truding from the slots provided for them after which the two metal upright strips are Modern Mechanix for Operated by an alarm clock mechanism, this record- ing rain gauge provides the amateur meteorologist with a very accurate weather station instrument. ARECORDING RAIN GAUGE amateur weather en clinched to hold the disc in permanent posi- tion. For the recording drum, get a cardboard carton that is exactly 12 inches in circum- ference. An empty salt container works very satisfactorily. The two right angle drum clips will hold a drum of this size in perfect position by cutting the bottom out of the drum so the [Continued on page 130] THE FINISHED RECORDER SHOWN WITHOUT OUTSIDE BOX, А 9"X9"X 20" OIL CLOTHED HOUSING ы RECORDING DRUM SUPPORT- ING SPRING PER Le BOX SUPPORT TO DRUM The rain gauge, as it appears when completed, is depicted here. hen in use, the device is protected in a 9"x9"x20" oil cloth covered box. Mount the recording drum on a support of sufficient height so glass pen contacts chart. August, 1937 7«— — FLATTEN END OF FLOAT WIRE bs | H BLOCK WITH 1 5/8"HOLE TO SUPPORT FLOAT TUBE COPPER FUNNEL PUNCH OUT SMALL HOLE COPPER SHEETING FLOAT САР. WITH 3/32" HOLE FOR FLOAT WIRE SIDE ААМ-1/4" COPPER TUBE DRUM CARDBOARD En 1 TON COVEREI | x WITH GRAPH PAPER CIRCUMFERENCE OF | DRUM 15 12" i BALSA BLOCK... PEN-MADE FROM DRAWN HOSE OUT GLASS TUBE The rain gauge, proper, consists of a 115"x10" copper tube into which is inserted a cork float. A length of No. 12 wire connects to cork for operating the pen arm. Rain is collected in a 2" funnel, passing into gauge through a rubber tube. Details of the graph drum and glass pen, shown above, are described in the text. 81

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With the chassis con- structed as described in previous installments, the racing fan is now ready to build the special body. 20 GA. RIGHT- ANGLE FITTINGS Although it has the aspects of the finest full-size racing саг, “Arlen Special", shown here with Don Arlen, is constructed entirely from parts of junked autos. by Manley Mills PART III HE phenomenal success, during the past few years, of midget automobile racing has prompted hundreds of home mechanics and craftsmen to undertake the building of midget cars from whatever odds and ends they could salvage from old automobiles. Realizing that the popularity of the miniature racing car was steadily increasing, a lead- ing West Coast racing car designer, Don Arlen of Hollywood, set to work on designing a DY FRAMEWORK B (See DETAILS) 1 Т ALL JOINTS ARE ELECTRIC WELDEDY 1 ^2 SQUARE TUBING 20 GA. POSITION OF GAS TANK DETAIL CORNE truly authentic midget racer that could be constructed from materials procurable at any auto graveyard. The resulting car proved to This head-on view provides a true conception of the in- genious construction employed in the front-drive mechan- ism. A four-cylinder motorcycle engine provides the motive power to the converted Ford А transmission. Body frame construction is shown in upper diagrams. be a masterpiece in custom racing car design, since it not only had been assembled from motorcycle and automobile parts, but featured a front-drive transmission—a feature usually found only on custom-built racers costing Left—The gasoline tank is constructed from galvan- ized iron and shaped to fit in the tail of the “Arlen” body. Tank is installed in a rack formed from 1⁄2” sq.. 20-gauge steel tubing. Below this is shown completed instruments panel and cowl framework construction. Modern Mechanix $2,000 or more. Probably the most amazing fact concerning Don Arlen's racer was the cost. After all work had been finished and the car was ready for its first run, a check-up on expenses showed that the total investment was less than $100, or about one-twentieth the price of a factory built car! August, 1937 In the foregoing installments, which ap- peared in the June and July issues of Mop- ERN MECHANIX, construction of the chassis, axle, steering and front-drive mechanisms for the “Arlen Special" were discussed in detail. The builder has now reached the point where he is ready for making the racing body. 87

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Detail of the cowl and gas tank frame construction is described in the schematic plans at left. Frames are formed from 12” sq., 20-gauge steel tubing and all joints securely welded. Above—Completed cowl. The cowl, tail, and hood are made from 22-gauge body steel. You can easily make the hood and cowl—and possibly the tail. How- ever, you can have them made at any sheet metal shop for a nominal sum. It’s much easier to build the cowl without the 3” flare, but it adds so much to the ap- pearance of the car that it is well worth in- cluding. The tail and cowl are riveted to- gether, then the right-angle strips, made from body material, are riveted along the bottom edge on each side. These strips will rest on the side rails where they are bolted with 14” bolts. Hood and radiator shell are made in one. The pointed nose is made from half of an auto headlight shell. Bend a length of 2" square tubing to fit inside the front end of the hood where it is welded. Also weld the nose to the tubing. Ordinary screen wire is used to form the front end, A piece of 34” rod, extending down about 2", is welded into The “Arlen Special" body is formed from 22-gauge steel. The body is shown here before being installed on chassis over the cowl and tail frames. Modern Mechanix Gear shift levers on the “Arlen Special” are conventionally located on the outside of the chassis as indicated in the photographic decrip- tions at upper right. Profile and top views of the body, shown here, contain all dimensions for building a true-fitting racing shell. the ends of the square tubing. These rods slip into short pieces of round tubing, welded to the inside front ends of the side rails. Ordi- nary auto type hood fasteners hold down the hood. The rear end of the latter and the front end of the cowl rest on hood lacing, riveted to the front part of the сом] frame. A snappy paint job will add greatly to the attractiveness of the car. The color scheme is, naturally, optional with the builder, but as a suggestion a chrome yellow body and chassis, with red wheels, trimming and let- tering, is a good contrasting job. August, 1937 Anyone with average driving ability can easily handle this car up to about 65 miles per hour, without any previous practice. How- ever, beyond 65 miles per hour conditions change rapidly and it is then when you must exercise skill and caution so as to keep the car rolling on all four wheels. Numerous tests runs have been made on the Legion-Ascot speedway near Los Angeles, [Continued on page 126] ge

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CONDITIONING YOUR BOAT WASH BOAT THOROUGHLY WITH STRONG SOAP POW- DER. WORK BEHIND BULK- HEADS AND SCRAPE LOOSE DIRT E FLUSH WELL AFTERWARD WITH HOSE OR PAILS OF WATER After a winter's storage, boats should be removed of their tarpaulin and allowed to dry out in the sun. The interior and exterior of the craft should then be scrubbed with soap and water. If dry rot is present kill by pouring salt in cavity. WHERE PLANKS ARE CRACKED, BORE 3/16" HOLES AT BOTH ENDS. FILL HOLES WITH SOFT WOODEN PLUGS AND THE CRACK WITH SEAM FILLER CAULK WITH ^ SINGLE STRAND OF CANDLEWICK, DIPPED IN GLUE. FORCE IN LIGHTLY AND FILL WITH WI FILLER REPLACE FAULTY BUTT BLOCKS WITH NEW.OVERLAP — J THE PLANKS. SCREWING FROM THE OUTSIDE, COAT FIRST A) WITH GLUE. A yy BEFORE PLACING BOAT IN Д), WATER ВОВ LAUNDRY SOAP OR WAX OVER BOTTOM TO PREVENT SINKING FROM DRIED OUT SEAMS Cracks in hulls can be repaired by drilling holes at each end of crack and driving in wooden plugs, then screw on battens as shown above, Caulk open seams with single strand candle- wick which has been dipped in marine glue. To prevent a craft from sinking while swelling apply soft soap to seams. 94 ROT, WORKING ALONG THE STEM, KEEL OR FRAMES SHOULD BE COMPLETELY DUG OUT TO KILL FUNGUS AS SOON AS IT STARTS PACK DUG OUT AREA WITH WET SALT. FOLLOW LATER WITH MARINE GLUE OR PITCH FINISH SURFACE SMOOTHLY AND VARNISH Few boats receive the atten- tion they deserve. This article tells how many years can be added to the life of your craft by proper care of the sails, deck fittings, hull and finish. by J. A. Emmett VERY hour spent overhauling and fitting out your boat, whether it be a canoe, sailboat or motorboat, the latter either in- board or outboard powered, will not only return big dividends in the way of increased pleasure secured from your outfit, but add materially to the value of your investment in hull and gear. Thanks to American inventive genius and today’s wide awake manufacturers spring fitting out work is a comparatively simple matter to what it was not so many years back when less fortunate owners had to either use indifferent paints or mix their own, then wait days for surfaces to harden. Standardized small boats built of late years by reputable manufacturers are constructed of the best of materials; given halfway decent care struc- tural repairs will not be necessary for years to come. Modern marine engines, both inboard and outboards, are clean in operation and sound engineering practice insures such long life that, barring accidents, overhauls are necessary but once in five years time and even then manufacturers stand ready to give a thorough factory job at minimum cost. Better cleaners, abrasives, rot preventatives Modern Mechanix FOR SUMMER SAILING TO REPAIR TACKS IN CANVAS- FIRST TACK DOWN EDGES Sz. ALONG TEAR COAT SPOT WITH HEATED, HARD GRADE MARINE GLUE LAY MUSLIN PATCH OVER AND SWEAT INTO PLACE WITH HOT REMOVE OR SAND OFF — PAINT WITH ESPECIALLY, IF ONLY CRACKEO BLOW TORCH USE STEEL WOOL IF ONLY DULLED BUILO UP PAINTED SURFACE SLOWLY APPLYING 3 COATS,FROM pops TO STRAIGHT PANT Wee! Canvas deck repairs can be neatly made by applying marine glue to the torn area and allowing it to dry. А piece of new muslin or light canvas is then placed over the glued surface and secured with a hot flat iron. Old paint should be removed with a file tang and blow torch. In repainting a boat apply а thinned coating first, slightly thinned second coat and straight paint fer the final.’ Use turpentine for thinning the paint. and solvents enable the owner to secure a cleaner undersurface for later painting in the shortest possible time and quick drying paints developed especially for boat use shorten the finishing period, offset the unreliability of spring weather and give a surface to with- stand a full summer’s use. If your boat has been covered with a tar- paulin, get the canvas off the first warm day August, 1937 and let the air dry out the winter’s con- densation. Take out loose gear and remov- able fittings preparatory to a thorough clean- ing, unless removed last fall as they should have been. More washing and less covering dirt with paint will save fitting out time and money and add years to the life of your boat. Use a strong soap powder even if it dulls and washes off paint. Scrub into every corner, inside and out, especially behind bulkheads and in lockers. Scrape with a putty knife to remove loose scale and dirt and to locate possible soft spots, then flush clean with a hose or pails of fresh water. Soft spots caused by dry rot become apparent at fitting. out time. Look for them in unventilated places and where fresh water lodges. If located, do not leave because rot [Continued on page 132} ita WATER LINE IS NOT ALREADY SCRIBED,TACK BATTENS ONTO BOTH SIDES AND INDENT WATER LINE WITH A SHARP TANG 95

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by Dale R. Van Horn EW home workshop projects will find greater appeal during the hot summer months than will this turned walnut ice bucket. The hostess will take considerable pride in using it when serving party guests, for its antique design will undoubtedly bring many favorable comments. By slightly alter- ing the original dimensions, either larger or smaller, the bucket can be used also as a bottle chiller for tomato or fruit juices or as a smart container for candies and nuts. For the latter purpose, a spun copper lid provides the bucket with a distinctive closure. Get a solid piece of wood if possible or glue up pieces to give you a square slightly less than 5 by 5 inches and about 9 inches long. This particular job was turned inside with a metal lathe because of its depth and because the sides could be made more accurately. After the inside had been turned, the piece 98 Turn the ice bucket from a solid or glued-up block of walnut measuting 5 by 5 by 9 inches. The inside of the container is best turned on a metal working lathe in manner shown above. Modern Mechanix was transferred to a jig in the wood working lathe, snuggled to a tight fit, the tail stock brought into use and the outside turned down to the dimensions shown. Note that whereas the final outside diameter at the top is 4% inches, it is only 43$ inches at the bottom. The bottom diameter can be 4 7/16 inches if you care to work with close figures. The slight taper is not noticeable to the eye, but it does permit the tapping of each hoop to a snug fit after the ends are soldered. Cut the copper strips for the hoops 42-inch wide and of the necessary length, including a lo-inch overlap. To make a strong, yet scarcely noticeable, joint, lay 42-inch of each end of the hoop over the top of the vise and hammer flat until the copper is approximately one-half the original thickness. Turn the piece over and make the same mark on the opposite side of the other end. Heat these ends with a blow torch, one at a time, and tin them well by rubbing with solder. Make another check against diameter, clamp the joint at one edge with the pliers and again heat in the flame. When the solder is soft, quickly clamp the other side of the joint with another pair of pliers and hold until the solder has set. This makes a joint only slight- ly more than the original copper thickness and if you have matched the outside seam well it will be inconspicuous. The next step is to tap the hoop home on the bucket. A tri- square or any flat metal having square edges will do nicely. Turn the piece in the lathe continually as you tap it in position to prevent breaking the seam. If hook is too tight, [Continued on page 134] After completing the inside turning, remove the block from the metal lathe, turning down the outside to a diameter of 41/2 inches. Copper hoops are then driven over the cylinder and trued up with a tri-square, after which they are polished with a file and steel wool as depicted in the above illustrations showing construction through the various stages. The lid jig is turned from pine and the copper closure spun over it. After spinning the copper lid, trim off the edges abd remove pine jig. August, 1937 99

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MICROPHONE ANTENNA -PIGTAIL STATOR PLATE $ 7 Ё. BAKELITE / MOUNTING if we TUNING CONDENSER [CD] | | ROTOR PLATE LATET t 5 x 4 SWITCH WOOD BOX 3'x 3h" x 2" DRILL HANDLE FOR GABLE 4 CONDUCTOR BATTERY CABLE y^ of the box, 102 Assemble the J4-teter transmitter components in a 3"x31^ box in the manner shown. each having a 34” radius. the back of the box, while the 200-ohm microphone is attached to the "t feont with a small machine screw. "ETHER IMP'— by Bill Bartlett RESENTING the "Ether Imp," perhaps the tiniest, and certainly one of the most fascinating radio transmitters ever designed. It is so light and compact that it may be car- ried about even more conveniently than the conventional sports mike used by profes- sional radio announcers at outdoor events. The battery supply for the transmitter is small enough to slip into coat or overcoat pocket and a small flexible cord from transmitter to pocket provides battery leads. The % meter band is destined to become popular with radio amateurs doing short dis- «D e о о о o. = = o SLIDING COVER 7/ \) ANTENNA INSULATOR R.F. CHOKE x2" plywood The tuning condenser, mounted on the side is homemade and consists of one rotor and one stator plate, The 955 “acorn” tube socket is installed in Make connections short as possible. Modern Mechanix A 3/4-Meter No larger than a sports an- nouncer's hand microphone, this tiny transmitter provides a novel method for transmit- ting on ultra-short waves. tance work. The range of this transmitter is from one-half-mile, under poor conditions, to as much as two or three miles, or even bet- ter, under more conducive weather condi- tions. This is the ideal outfit for the beginner who wishes to maintain contact with a friend over a short range, or for the amateur who wishes to conduct 34 meter field experiments during the summer. The transmitter is simple enough for even a beginner, with absolutely no experience, to build, since the parts are few and the dia- grams show clearly the situation and connec- tion of each part. The most important point of the construction is to keep all leads as short as possible since at this high frequency long wires in the circuit result in capacities that tend to pull the set out of its proper frequency band. The type 955 "acorn" tube accounts, in a large measure, for the set's tiny propor- tions. This tube, which is about the size of a person's little fingertip, has a glass envelope [Continued on page 130] ANTENNA RADIATORS TA x 3% COPPER STRIPS; SINGLE BUTTON CARBON MIKE | 90 VOLTS ии] Transmitter This simple wavemeter permits an accurate check of the trans- mitter's frequency. It consists of a 5’ long by №’ wide copper strip, mounted on a baseboard with stand-off in- sulators to form. а “U” shape. COPPER STRIP Connect a 0-200 milli- ammeter in series with plate lead, bring wave- meter near transmitter and slide bar along strips until highest reading is obtained. Measure dis- tance around bow to de- termine the wavelength. FEED- THRU STAND OFF INSULATOR MOUNTING OF соп Lr Уи NO. 32 0.6.6. WIRE CLOSE WOUND BAKELITE ROD This schematic diagram indicates the utter simplicity of the transmitter's circuit. The tuning inductance is wound with No. 18 enameled copper wire as shown in inset. Y4" Bakelite dowel. August, 1937 s i The choke coil is wound with No, 32 d.c.c. wire on a The antenna radiators, which mount to the stand-off insulators, each measure 71/4"K34". 105

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106 This looks like a cozy log cabin in the mountains, with the owner’s car ready outside the door to take him to town. Actually, this is a “table top" shot. The cabin is a cleverly-made model of lollypop sticks and cardboard, and the. flashy roadster is a rubber toy purchased for a dime in a chain store! This realistic lake scene will fool many people. The plane really flies, but it is only about a foot long! The placid “lake” is a mirror; the shore is beach sand; the “trees” are tiny twigs from window plants. An excellent example of ingenuity and good photography made with an ordinary hand camera. S ALMOST А every motion picture goer knows, the Holly- wood studios are continually fooling us these days with scenes photographed in miniature, such as a village street, rural winter snow scene, a ship at sea, an airplane wreck and what not else. So cleverly are these miniature “sets” designed and photo- graphed that in the picture their lack of re- ality defies detection, and when we are let in on the secret, we do not mind at all. In- deed, we admire the achievement. Have you ever tried creating miniature scenes yourself and photo- graphing them with your own camera? Itsfun. Depending upon your skill, artistic ability and the materials you employ, you may construct and photo- graph miniature sets in your own home that will rival the semblance of reality achieved in Hollywood; or, if you pre- fer, you may create scenes of fantasy, comedy or burlesque to compare with a “shot” in an animated cartoon. For a "still" camera, this is really nothing else than table-top photography, such Modern Mechanix focus camera, provided you These elephants must have heard of the song “Kitten оп the Keys’? and decided they'd try а tune themselves. A simple but effec- tive home-camera stunt, made by the light of a single flood lamp in а reflector. as has long been practiced by amateurs, but which now is photographically much easier for the amateur than it used to be, because of the recent introduc- tion for home use of more powerful artificial С lighting. For table- top photography you can very cheaply, with two or three of these brighter home flood light bulbs, rival the lighting equipment of Hollywood studios, and, what is more, do good work with an inexpensive fixed- use a portrait attachment to secure the necessary close-up focus. Constructing one of these sets \_ requires, of course, a certain * E^ Б : m Г E > a t hot h t lo- amount of time and patience, with : Pd да Adel Lu eben an for ihe the expense depending upon the ma- Rud mie MR Nee terials you put into it. Very amusing Club." Note the “fan dancer" per- forming for amusement of assembled guests. Specimens are held temporarily in place by specks of rubber cement. scenes may be created, however, with- [Continued on page 142] August, 1937 107

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~— WIRE TO BE CLIPPED ON CAMERA Fastened to the top of the camera, these handy exposure data cards in- sure successful “shots” by Everett Rudloff ESPITE new and clever cameras of all shapes, sizes and prices, there are thou- sands of camera addicts who have used the time-tried Graflex with great success. With some frequency, however, they would like to make it still more useful. Many photogra- phers build their camera equipment around a Graflex, adding other machines for special work from time to time, but falling back on the “old reliable” for their important shots. 108 A small toggle switch mounted on the side of the Graflex permits right hand to trip “photoflash” and left hand to snap shutter. The “photoflash” holder is made from flashlight case as described above. This metal indicator permits distances to be inscribed on focusing knob for instant adjustment, eliminating use of camera's focusing screen. PHOTOFLASH REFLECTOR WIRIN It is this kind of work which has inspired some of the “Graflex gadgets" described here. First in importance, because it may save the cost of the camera, is a neck strap. Neck straps are not new, except on a Graflex. Miniature cameras come equipped with the straps so that the camera may be carried at chest level all the time. While no one would choose to carry a heavy camera in that posi- tion constantly, there are occasions in news and commercial work when it is helpful to be able to let go of the camera and have your hands free. To make this strap, secure from the five and ten-cent store one web strap three feet long, two swivel snap hooks, such as are used for dog chains; two brass reinforcing strips, one inch long, and two half-inch screws. Run the plain end of the strap through the buckle and rivet it over one of the hooks. Find the Modern Mechanix mid-point of the camera case and fasten one brass strip on each side, with one screw, so that the other hole in the strip projects above the camera box, then ream the other holes to take the strap hooks. To use the strap, open the camera to work- ing position, snap the left hook, bring the strap around the neck and snap the right hook in position. Now, adjust the strap length with the buckle so that when using the camera in normal position the hands take the weight as usual, the neck strap being allowed just a little slack. When not in use, the strap is carried in the pocket and the two August, 1937 A neck strap, such as this one, permits more freedom of the hands when using the Graflex for news and commercial work. The strap, а 10с web type, is fitted with swivel snap hooks for fastening to camera box connectors. brass strips swung down along the body of the camera. A focusing scale is a real neces- sity, yet few popular Graflex models have one. The ground glass is ideal for most pictures, but there are times when the light is bad, the lens is stopped way down or a night picture with photoflash is necessary and it is impossible to see the image in the hood. An accurate focusing scale is provided by making a metal pointer for the regular focus- ing knob and screwing it to the camera at a 45 degree angle with the bottom and front of the box so that the pointer just clears the knob. The camera is then taken outdoors and a target set up on a support. With a lens of 612 inches focal length the following distances were measured off: 4, 5, 6, 7, B, 12, 15, 20, 30, 45, 60, 85 feet and infinity. With the lens over the 4-foot mark and 109

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