Mechanix Illustrated, June 1938

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€ "| worked side by side with those | know them. They're my friends—and they're mighty fine chaps. But come back two years from today, and “THEY KNEW ME WHEN... men for years. you'll see those same men at those same desks. "They lack sufficient training to go much farther in this business. So did |—until | faced the cold, hard facts of my own case. It wasn't long after that that | enrolled as a student with I. C. S. The training | got in that course fitted me for advancement — and I've been on the up-grade ever since." How about yourself? Are you honestly equipped to hold a bigger job? Think it over. The coupon below is the same one that started thousands of men toward success. INTERNATIONAL CORRESPONDENCE SCHOOLS * BOX 2319-Q, 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: TECHNICAL AND INDUSTRIAL COURSES O Architect O Architectural Draftsman O Building Estimating O Contractor and Builder O Structural Draftsman Q Structural Engineer LI] Management of Inventions O Electrical Engineer O Electrio Lighting O Welding, Electric and Gas O Reading Shop Blueprints O Heat Treatment of Metala O Business Management O Industrial Management D Traffic Management DO Accountancy O Cost Accountant П С. P. Accountant О Home Dressmaking D Sheet Metal Worker , D Boilermaker D Telegraph Engineer O Telephone Work DJ Radio Lj Mechanical Engineering O Mechanical Draftsman O Machinist O Toolmaker L] Patternmaker D Diesel Engines D Aviation Engines O Automobile Mochanie D Commercial Refrigeration DL] Plumbing O Steam Fitting O Heating D Ventilation D Air Conditioning and Cooling О Steam Engineer O Steam Electric Engineer D Marine Engineer OR. R. Locomotives D R. R. Section Foreman D Air Brakes [] R. Qt. Signalmen D Highway Engineering D Civil Engineering OD Surveying and Mapping BUSINESS TRAINING COURSES LI Bookkeeping D Secretarial Work D Spanish L] French LI Salesmanship O Advertising D Service Station Salesmanship O First Year College Subjects D Business Correspondence O Stenograpby and Typing LI Civi! Service DO Mail Carrier D Railway Mail Clerk DOMESTIC SCIENCE COURSES O Advanced Dressmaking O Professional Dressmaking and Designing Name. City... If you reside in Canada, send this coupon to the International Correspondence Schools Canadian, Lim D Bridge Engineer E] Bridge and Building Foreman O Chemistry LI Pharmacy E] Coal Mining D Mine Foreman [Q Fire Bosses O Navigation E] Cotton Manufacturing O Woolen Manufacturing G Agriculture O Fruit Growing © Poultry Farming O Grade School Subjects D High School Subjects D College Preparatory O Illustrating O Cartooning O Lettering Show Cards O Signs D] Foods and Cookery O Tes Room and Cafeteria Management, Catering Montreal, Canada When Answering Advertisemciuts Please Meution Tune Mechaniz Illustrated 3

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PRICE JUNE 15 CENTS 1938 SAME PRICE Volume XX IN CANADA Number 2 Circulation over 250,000 Copyright 1938 by Fawcett Publications, Inc. SPECIAL FEATURES MECHANIX ILLUSTRATED is not a new magazine. It is the former MODERN MECHANIX in Science Is King! - - - - - - - - 35 new dress, with more pages, more By Lowell Thomas and bigger pictures, more human- interest articles, more craft and hobby projects than ever before. Steel Backbone Of The Modern World - - 42 New readers will quickly see that By Robert W. Gordon MECHANIX ILLUSTRATED is y Ў fresh, lively, entertaining. Old readers already know that it is Built To Win - - - - - - - - - 54 accurate, authoritative, inspiring. By R. De Witt Miller Show this copy of MECHANIX ILLUSTRATED to your friends and tell them to look for future issues on their local newsstands. Be sure to say MECHANIX IL- Opportunities For The Small Inventor - - - 63 Fighting Water Famine - = = = = = 66 LUSTRATED to your newsdealer, By D. A. Lane and you will get the biggest 15 cents worth of magazine on the market! MECHANIX ILLUSTRATED in the Movies - - 70 Drive Next Year's Car Today - - - - - 74 Camera Section By Frederick C. Russell Winners Of Photo Awards - 119 War Postmarks As Collector Items - = = 86 What To Do About Parallax - 120, By Montgomery Mulford The MI “Minineg” Enlarger - 122 The Spring Overhaul On The Boat - - -100 Rotary Safelight Lamp Saves By Sam Rabl Darkroom Time - - - - 126 Photo Short Cuts - - - - 128 Chemistry Of Microscope Slides - - - - 104 By Julian D. Corrington, Ph.D. Kid Stuff - - - - - -130 [Continued on page 8] Amateur Photo Puzzlers - - 132 Published monthly by Fawcett Publications, Inc., 11th St., & Broadway, Louisville, Ky., U, S. A. Business office, 22 West Putnam Ave., Greenwich, Conn, Entered as second-class matter under the Act of March 3, 1879, at the post office in Louisville, Ky., with additional entry at Greenwich, Conn. Editorial offices: 1501 Broadway, New York, N. Y, Not responsible for unsolicited manuscripts, In U, $- and Possessions and in Canada, 13c a copy; $1.50 a year. Send subscriptions to Greenwich, Conn., address. Other Poslal Unions, $2.00 a year. East Indian Agent, P. C. Eranee Sons, Bombay, India. Printed in U. S. A. Advertising forms close ihe first of second month preceding date of Issue. Advertising offices: New York, 1501 Broadway; Chicago, 360 N. Michigan Ave.; San Francisco, Simpson-Rellly, 1014 Russ Dldg.; Los Angeles, Simpson-Reilly, Garfield Bldg. Member Audit Bureau of Circulation. W. H. FAWCETT, Publisher RALPH DAIGH, Managing Editor ROBERT HERTZBERG, Editor AL ALLARD, Art Director JOHN L. SCHERER, CLIFFORD PETERS, Associate Editors S. S. RABL, Naval Consultant

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NEW CONDITIONS IN MY WORK === What About + Promotions Pay A Raises e] WHERE DO YOU GO FROM HERE? OU’RE like a million other men—you're facing a big question, The depression turned business topsy-turvy and now the rebuilding period stares you in the face. Are the things that are happening today going to help or hinder you—what will they mean in your pay check? Where will they put you five, ten, twenty years from now? How can you take full advantage of this period of opportunity? We believe you will find the answer here—a suggestion the soundness of which can be proven to you as it has been to thousands of other men. The whole trend today—legislation, spirit, action —is to put men back to work, raise earning and spending power, give every man a fair chance to work out his own salvation. The road to success remains unchanged but, bear this in mind, what it takes to win is radically different! No employer today would dare risk an important st in the hands of a man who had not learned the esson of '29. Why should he, when right at this moment he can pick and choose and get almost any man he wants at his own price? Business organizations are rebuilding—reorgan- izing forthe new conditions. Before it is over every man and every method will be judged in the cold light of reason and experience —then dropped, re- made or retained. This spells real opportunity for the man who can meet the test—but heaven help the man who still tries to meet today’s problems from yesterday’s standpoint! Out of the multitude still LASALLE EXTENSION, Dept. 6493-R, Chicago Please send me—without cost or obligation—full information about how I can, through your training, equip myself for the new problems and opportunities in the business field I have checked, Law: Degree of Traffic Management Commercial Law Bees Management Business English Stenotypy Н Salesmanship (J) Modern Foremanship Office Management Higher AERE Business Management LL.B. When Answering Advertisements Please Mention June Mechaniz Illustrated Business Correspondence jobless there are sure to be many frantically eager to prove him wrong and take his place. Some Men Have Found the Answer Seeing these danger signs, many aggressive men and women are quietly training at home—are wisely building themselves for more efficient serv- ice to their employers. You naturally ask, ‘‘Has your training helped men withstand conditions of the last few years?” Our answer is to point to a file of letters from many of our students reporting pay raises and promo- tions while business was at its lowest ebb—together with a myriad of others telling of greater success during these recent months of recovery. Amazing evidence is ready for your investigation. We have assembled much of it in a booklet that is yours for the asking, along with a new and vitally interesting pamphlet on your business field. This is a serious study of the possibilities and opportunities in that field. It is certain to contain an answer to vital questions bothering you today about your own work and earning power. Send for these booklets—coupon brings them free. Be sure to check the LaSalle training that in- terests you most. We will tell you also how you can meet and take fullest advantage of today’s situation, No cost or A É obligation—so why not A mail the coupon now? Qa

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FOR QUICK ACTION MODELS AND FINISHED DRAWINGS UNNECESSARY Don’t spend money or time on finished models or drawings before you know your invention may be patentable. Our large staff of experienced patent searchers can handle a search from your description and roughest sketch. The main thing is to put it in our hands as promptly as possible. DELAYS ARE DANGEROUS IN PATENT MATTERS 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 invention. In such case, the burden of proof rests with the last applicant to file. Sometimes a delay of even a few days in filing the ap- plication means the total loss of the patent. LOSE NO TIME. How To Determine The Patentability Of Your Invention Before you spend money in making a model, or spend weeks in its design, we advise you first to have a preliminary search made through U. S. Patents in the U. S. Patent Office to see if there are inventions like yours already on record; and, if so, let us give you our opinion as to the patentability of what you have. We employ experienced searchers to perform this service for you. From the reports of our searchers we can quickly form our opinion as to whether your invention is confronted with obstacles in the form of already granted patents. First get our FREE BOOK and read the chapter on “How Can I Know Whether My Idea Is Patentable?” Latest Facts On Inventions, Patents and Markets For Inventions The very latest. information on all matters affecting your invention—all inventions. Don’t act until you get this Free Book! It reveals important information on obtaining patents, establishing a market for in- ventions, getting financial aid, using patent to secure commercial success. 48 pages crammed full of illus- trations, helpful and interesting statistics, Patent Office data, rulings, a detailed guide on how to patent and protect your invention. This new book will be sent promptly—have the most up-to-date guide to the things you must know to simplify patent procedure and save time, the vital thing to you! FACTS ABOUT OUR SERVICE We are registered U. S. Patent and Trade-Mark At- torneys, serving inventors all over the United States. Our organization is complete in every particular. We have Draughtsmen, experienced Searchers, and At- torneys to serve your interests. We have had years of experience in patent matters and know every angle of legal approach. We will secure protection for your invention if it can be done! But the longer you delay the harder it may be for us to serve you. CLARENCE A.OBRIEN & HYMAN BERMAN- 317-D ADAMS BUILDING, WASHINGTON, D. C. Registered Patent Attorneys 'before U. S. Patent Office

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THIS FREE BOOK TELLS HOW Your Patent Application is made; what kind of sketches or drawings are necessary; what other papers must be made out; how the Patent Laws protect you; why it is important to avoid loss of time in getting your application filed; and many other important points. Even a very simple in- vention, if new and useful, may prove very valuable. You may have much to gain and nothing to lose by sending for this book TODAY. THE FIRST STEP When you place your invention in our hands, we are in position to proceed at once to secure protection for you. Our fees are rea- sonable, and, if you desire, we can arrange convenient terms of payment. We will send you our Record of Invention form FREE, This blank will enable you to make a sketch of your invention in proper form and have it witnessed in such manner that it may be of value to you as evidence should the occasion for evidence arise. In our book, we tell you how to use this form to protect your interests. Every year thousands of Patents are granted. Very few, however, represent the discovery of entirely new principles. Most of them provide new methods of doing some everyday thing in a better way. These improvement Patents offer large chances for profit if commercially useful. The business world wants improved products and services. OUR OFFICES IN THE HEART FREE RECORD OF OF THE NATION’S CAPITAL INVENTION FORM If you prefer to use a form made specially for Located in Washington, D. C., within a few blocks of the U. S. the purpose of recording the descriptive outlino ‘ 1 : ` of your invention for our searchers’ use at the Patent Office, we are able to give you immediate advice and uS Patent Office, write today for our Record : : 7 ; i of Inventlon form—it will guide and asslst you. accurate, authentic information on all matters concerning It enables you to make a sketch of your inven- Patents and Trade-Marks, particularly if it is necessary to Hon and have it witnessed n a manner of value examine the records in U. S, Patent Office. you as evidence should the occasion for eyi- dence arise, Our FREE BOOK tells you how to use thls form to protect your interests, үп Бе зл A ps ER UE M UD NS UR Uo m mm mu um UN isheartened about the fu- * ture until you get our FREE E CLAREN СЕ A.0 BRIEN BOOK and learn how other €E HYMAN BERMAN inventors succeeded de- spite lack of funds, remote- ness from market, lack of 317-D Adams Building, Washington, D. C. 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, This request does not mechanical skill, education, TRES and other handicaps. Send нонро, анадан анараа анода о fedt pad Uns coupon for this FREE BOOK м today! ГАТ ЖИКС Т УЛ ГГ ГГ О ТҮ КК КГК Т

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to Protect and , CONTENTS-—Centinued from page 4 capitalize on your INVENTION Get these FREE BOOKS Of IDEA’ Opportunities Is your idea patentable? Has it commercial possibililies? Those are thethings you want to know-- and interesting information on these questions can be found i in our books “How We Protect You” and ` “Suggestions on How to Commercialize Your Invention’. We will send you these absolutely FREE.- together with our Certification of Invention form, if you mail the coupon below NOWI OUR EXPERIENCE GUIDES YOU You can feel perfectly sure in dealing with this reputable firm. C. A. Snow & Co. has ae еш, been securing patents of every description Gui es m ti for 63 years. Save time and expense now m SM by getting advice based on our W WN long patent experience. C. A. SNOW&CGQ | Reg/stered Patent Attorneys Since 1875 wk DEPT. 368 SNOW BUILDING, WASHINGTON, D. C. ш Gentlemen: Please eend me absolutely free and without obli- nu ш sation | on my part. your original document ‘‘Certification of nvention'', together with your two ‘How We Protect You" and mercialize Your Invention’? uides for inventors, "Suggestions оп How to Com : ш н Street and No, a.. W city oc Town. c cc ca unean FERBREEERRERRRERRESNHENNERA BE SUCCESSFUL DIARY OF INVENTION, When you bare little money do you know how to protect your invention! This diary is a pocket size hook for keeping a diary record to protect Your pri rights, Price 25¢. INVENTION & FINANCE MAGAZINE is writien for intelligent inventors who ave willing to earnestly work for success, Two year subscription $1,00 entered upon promise to pay on receipt of first copy. PLACE YOUR ORDER by checking item you desire, Then cut out and mail this advertisement, © Send subscription O Send Diary INVENTION & FINANCE MAGAZINE 80-H Wall Street, New York, N. Y. patent problems. Send PERSONAL SERVICE me a model or draw- ing, or sketch and description cf vour invention, and $5.00. I will make a search and report promptly as to its patent- ahility and send vou a copy of my 72-page booklet. Or, if you prefer to read my bocklet first, АОН today for FREE copy. Registered Patent Attorney. L. F. Randolph, 761 Victor Building, Washington, D. C. My Personal service assures strictest con- filence on al your The Plastex Industry necds manufacturers on big production of Art G and Marble Imitation. xperience unnecessa Equipment and slmpie instructions furnished for speed production, Small invest» ment brings big returns, Nation-wide demand for these low priced foods. Ambitlous men have chance for real prosperity. Our free book will interest and benefit you. Bis wholesale season now Amiens K RASTEM INDUSTRIES, Dept. 3. 1085 Washington Ave., ew or. 1 scale and for оойе. Novelties. Souver , ete.. X in Plastex 8 досе? SHORTER FEATURES Setting The World’s Largest Stage - - - Freak Roadside Stands Attract Patrons = -= New Giants Of The Air - - - - - - - Aluminum Mirrors Reveal Unknown Stars HOW.-TO-BUILD FEATURES Wet And Dry Bulb Thermometer For 75c The MECHANIX ILLUSTRATED Are Welder - - = = = - = = = = & Building "Patty"—An 814 icu Convertible Sailing Skiff - - - - ME eC ee Range Finder For Model Planes - -= =. > Operating Two Trains On One Track - - - The "2-3" Portable - - - - -= Craftsman’s Method Of Making Pitchers - - FOR THE ORS FAN Uses For "Water Glass" - - - z A Dowel Step-Up - - - - - - - - - Orange Crate Porch Office - - - ‚за How To Get A Master Finish With Unskilled Hands - - - - = eee m Truck Inner Тире: Makes Efficient Shop Bellows - - - pru Saw Becomes Grooving Tool = = > = = Burrs Improve Box Wrench - = = e = AUTOMOTIVE Car Features Two Types Of Engines - - - Portable Car Heater - - - - = = = ~ Auto Safe Thwarts Holds Ups - - - -= Wheels Protect Rear Of Car =- = e = = Flat Pack Holds Auto Tools =- = = = œ Bumpers Become Brackets - - - - - - Nail Polish Aids Windshield - - = = = ANIATION New Transport Plang Possis Increased Flight Safety - - - - ->a = = > Builds Gas Model оғ Douglas Plane - - - Invents “Disc-Rotor” Aircraft - - - - - | New Type Airship Flys By "Kicking" - - Transparent Weather Chart Aids Flyers NEW MECHANICAL DEVICES Cooking Pot Has Clamping Lid - - - - Two-Way Wrench Opens Tight Jars - - - Electric Polisher Runs Dual Blocks - - - Fire Piping Has Remote Control = = = = Novel Skate Has Ball “Wheels” - - - - “Iron Mother” Unit Saves Babies =- e =- - One-Man Cross Cut Saw Fells Bene Trees Quickly - - - - - a um Polaroid Lighting Unit Gives Glareless Illumination - - -= ae гш Ош [Continued on page 10] No Substitites! Akcays Insist on the Advertised Brand! 40 49 50 82 87 88 94 114 115 116 118 92 106 107 108 112 112 112 52 62 64 103. 103 103 103 48 61 73 83 84 39 39 41 41 48 53 60

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“HE sai my face was more or less familiar and he remembered seeing me around, but he didn’t even know my name until the I. C. S. wrote him that George Jackson had enrolled for a course of home study and was doing fine work. l “Who's George Jackson?’ he asked. Then he looked me up. Told me he was glad to see I was ambitious. Said he'd keep his eye on me. *He did too. Gave me my chance when Frank Jordan was sent out on the road, I was promoted over older men who had been with the firm for years. *THE BOSS DIDN'T EVEN KNOW MY NAME" *My spare-time studying helped me to get that job and to keep it after I got it. It certainly ‘was a lucky day for me when I signed that I. C. S. coupon." How much longer are you going to wait before you take the step that will bring you advancement and more money? It takes only a moment to mark and mail this coupon and send it to the International Correspondence Schools at Scranton. Yet that one step may be the means of changing your entire life: Isn't it better to get the facts than to wait a year or five years and then wish you had? BOX 2320-Q, 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: TECHNICAL AND INDUSTRIAL COURSES O Sheet Metal Worker 4 O Plumbing Ll Steam Fitting O Boilermaker O Heating D Ventilation © Telegraph Engineer L] Air Conditioning and Cooling LI Telephone Work O Radio O Steam Engineer O Mechanical Engineering O Steam Electric Engineer O Mechanical Draftsman L] Marine Engineer O Machinist O Toolmaker O R. R. Locomotives O Patternmaker L] R. R. Section Foreman L] Air Brakes [] R. R. Signalmen O Highway Engineering O Automobile Mechanic O Civil Engineering O Commercial Refrigeration O Surveying and Mapping BUSINESS TRAINING COURSES O Service Station Salesmanship D First Year College Subjects L] Business Correspondence O Stenography and Typing L] Civil Service E] Mail Carrier П Railway Mail Clerk DOMESTIC SCIENCE COURSES E] Home Dressmaking O Advanced Dressmaking O Professional Dressmaking and Designing O Architect Architectural Draftsman Building Estimating Contractor and Builder п O Bridge Engineer Q E B Structural Draftsman Q O Bridge and Building Foreman O Chemistry O Pharmacy O Coal Mining O Mine Foreman O Navigation O Cotton Manufacturing O Woolen Manufacturing O Agriculture DO Fruit Growing O Poultry Farming Structural Engineer Management of Inventions Electrical Engineer O Electric Lighting O Welding, Electric and Gas O Reading Shop Blueprints O Heat Treatment of Metals O Fire Bosses LI Diesel Engines O Aviation Engines O Business Management D Industrial Management O Traffic Management O Accountancy O Cost Accountant O C. P. Accountant O Bookkeeping O Secretarial Work O Spanish LI French O Salesmanship O Advertising O Grade School Subjecta O High School Subjects O College Preparatory D Illustrating O Cartooning " O Lettering Show Cards [Signs O Foods and Cookery O Tea Room and Cafeteria Management, Catering Name. „Address... Present Position... orrespondence Schools Cam When Answering Advertisements Please Mention June Mechanix Illustrated 9

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Les gattery POWERAY bove Der 6-volt electric lan. tern with powerful Te sper beam, 00 hours light. 4/2 in. reflector. ор езт а fens. POWERLITE cat side) America’s finest elec- trle lantern. 6-volt. 2 reflectors — front, shoots 800 ft. beam; to ion dt: light. г lens, At sport, hard- ware and дека! dealers or write direct to Ё Delta Electric Co., Marion, ind. Dept. 450 G Se Sate Simple scientific way of removing nicotine and €&uj tars from cigarettes is taking the country by storm. Vou can taste the cool clean smoke and see what's eliminated on the inside. cigarette. Саа Big money placing cards with dealers. Retails only 50c. Rush 25c for sample and details. GORDON MFG. CO. 310 E. 23rd St. Dept. NF-15, New York, N. Y. CONTENTS—Continued from page 8 Giant Machine Sews Ten-Foot Blankets - 62 Hand Guides Giant Riveter - - - - - 64 Device Converts Sawdust To Log - - - 65 Rural Mail Box Tilts Open - - - - ə =- 72 Levers Control Bike Brakes - - - - - 72 Photo Cutter Is Self Honing - =- - - - 72 Machine With Spiked Frame Aerates Lawn Soil - - - - - =- = = = = 79 Portable Pile Driver Works Like Diesel Engine - - - - - = «= . 19 New Device Wiese essispiosenty Of Lake Waters - - - - - - - - - - 8&8 Student Constructs Loud Speaking Electric Guitar - - - - =- =- = a > $I Mechanical Bed Is Boon To Patients - - - 83 Enamel Baking Lamps Resemble Clam Shells 84 Stubby Farm Tractor Has Single Tread - - 84 Switching Locomotive Has Four Engines - 85 DEPARTMENTS Chips From The Editor’s Workbench - - 14 Nic Sprank’s Oddities - - - - - - - 34 Crafts And Hobbies - - - - - -- 84 Photography Section - - - - - - - - 119 MISCELLANEOUS Transparent Oil Cans Developed - - - - 39 Device Measures Heat Of Skin- - - - - 4 Old Coin Weighs 44 Pounds - - - - - 48 Creates Novel Job To Pay Schooling - - - 52 Starts Sea Voyage In 18-Foot Ketch - 52 Constructs Printing Press From Old Clothes Wringer - - - =- - = - - = - = 53 Surgical Mask Made From Transparent Material - - - - - - - - - - 53 Robot Checker Player Is Undefeated - - 61 Puppet Show Teaches Traffic Laws - - - 61 Solitaire Bridge Board Gives Expert Opposition - - - -- 62 Builds Model Hanedos From 10, 000 Matchsticks - - - - - - - 64 Welder Makes Own белен - - = = = 65 Lightning Poses For Photo - - - - - - 65 Builds 8-Foot Cottage Model - - - - - 72 25,000 Bowlers Participate In National Contest 73 Trailer Photo Lab Developed - - - - 7 Carpenter Builds Bandsaw From old Automobile Parts - - - - - - - 7 Home-Built Catapult Löwers Trap Shooting Costs - - - - - 80 Welder’s Goggles Feature Hinged Lenses - - 80 “Sea Monsters” Are Log Rafts - - - - - 80 Mailbox Picks Up, Delivers Mail - - - - 83 Carves Scale Model Of Ocean Liner - - - 85 Midget Steam Engine Has Thimble Boiler - 85 10 Accept No Substitutes! Always Insist en the Advertised Brand!

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As nearly all manufacturing and building starts on the drafting table, the draftsman is one of the first to be hired, last to be laid off. His blueprints, his specifications, give the final word in what the workmen are to do. Good Pay The draftsman has been called the Junior Engineer, which accurately describes his work, position and pay. He combines knowl- edge of principles, mechanism and construc- tion details with ability to draw plans and indicate methods. Usually his salary is con- siderably above the wages of the mechanic and, of course, less than that of the engineer. Chance for Promotion Helping design new buildings, machines or R E icm What happens to the average man? Not having thorough be th : ; s training for a worth-while job, he goes along year after year, wish- ва ing he had a good job, but wishing was never a substitute for sults. These contacts, plus his experience, t*@ining. $40 a weck is about his top, usually never that high. place him in an excellent position for promo- rows old on the job, starts down at 40, finds himself slipping tion when next there is a good opening. in speed and salary. Young at 40 Security for Yourself and Family Athletes, farmers, factory and shop workers Even if you are now only 18, 25 or 30, youshould look ahead — all who rely on muscle often are old at 40. —begin training TODAY for the job you want at 50. Training Office workers — executives, teachers, profes- helps you to be independent—-self-supporting. It helps you to sional men, drafismen—just approach their enjoy associations denied to untrained men. Training helps you prime at 40 to 50. Training increases your to offer your family advantages far in excess of what you could value AT ONCE and continues to help boost give them as an untrained man. Investigate NOW. your earning power as you mature. American School, Dept. DDA 28, Drexel at 58th, Chicago rss POCkot fa i: aE У TEE (LOU) WORLD'S SMALLEST REAL PERFORMING Amazing midget radio com. lete in one unit—woei only wit : LEARN QUICKLY AT HOME BY LATEST EXPERT METHOD An easy, quick, thorough Home Study Course. Oldest and largest school in Ihe world TEACHING PHOTO-ENGRAVING by correspondence and residence. Many unusual fealures-£xperimenial Equipmen! for home use—Rare Reference Books—Camera Journalism, Plate Layout Examples, Lilelime Consulling Service. "30 Photo-Engravi Ways to Make Money from the Day You Stert Your, Studie: à All included at no extra cost. Write lo for Free 38:page Opportunity Booklet... g AURORA SCHOOL OF PHOTO-ENGRAVING Dept. 668 AURORA, MISSOURI ozs. Receives stati ä clear beautiful tone. Not to be confused with cheaply made Imitatlons. MANUFACTURED BY THE ORIGINATORS OF THE POCKET RADIO. Mechanical Patent No. 2074887 covers come plete construction. Programs come directly from front of radio. Uses Self-contained peakophone'' unit which gives superior performance. NOT A TOY! Absolutely complete with instructions for use In homes, hotels, boats, ete, TAKES ONLY A SECOND TO CONNECT. No hook- ups to any current. THOUSANDS OF SATISFIED OWNERS in all parte of the world report wonderful service with their sets. Two color cabinets. | Six colors augale, i ly $2.99 pl tay a ostman only . us post SEND NO MONEY! bay arrival or send $2.99 (Check, M. os Cash) and yours will be sent postpaid. GUARANTEED. А most une usual value. ORDER NOW! TINYTONE RADIO CORP. DEPT. M-6 KEARNEY, NEBR. AC-DC ELECTRIC DRY SHAVE RAZOR COS [ 3 00 At last a Guaranteed streamlined precision-built Head and Motor Electrie Dry Shave a Razor at the world’s lowest price that makes selling a cinch! We welcome comparison to $15.00 competition, But don’t wait! Get complete A BIG $2.00 PRO FIT FOR YO U. facts quick—Hurry! "Yours Free" plan tells all! UNIVERSAL INDUSTRIES, 6227 BROADWAY, DEPT. 266, CHICAGO sas AUTOPOWER tells you how in plain, easy, simple and illustrated instructions that anyone can follow. Change auto generators into useful, practical A C and DC generators and motorg with voltage from 2 to 1,000 volts, for power, light, welding, radio, sound, ete. No previous experience nor speclal tools needed. Generators ean be driven by wind, water, fan belt, etc. INSTRUCTIONS FOR BUILDING AN AC WELDER THAT ACTUALLY WORKS UP TO A 3/16" ROD. ALSO COMPLETE PLANS FOR WIND AND WATER POWER PLANTS. Send for your copy of ‘“‘AUTOPOWER.” Already used and en- dorsed by thousands. Only $1.00 postpaid. S. W. DUNCAN, Publisher 412 S. Hoyne Ave., Chicago When Answering Advertisements Please Mention June Mechanix Illustrated 11

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‘PATENT YOUR INVENTION > > > -иәлш sni л0у JpOstMIy paysmMsursip opes Suréphys sem oym Хоф WALZ 9 í*lourgD puri ou) pojusaur Agdeidojoqgd anazyewme sem Aqqoy ssoym yap ue e fouoydayay oy} padoyaAap quunp рит jeap ay) Zur -цэвәу ш рәлцетоойє оца иеш е iaujpqoeur 3uraos oui оз Зигүол 59пәшәлолаші зиррлойші әреш “вишо цээш рец оцм 3sod e :цаелЗәрәј эу розпәли 9 paipnjys oym 151316 Peapod ұу — :suopiuoatl рәңлом элец ѕәреу рие ѕиотѕоа ји» r Up UW (“618954 әлу-Аұпәмӱ 182ү oy} Jo suorjuaAur 215024 оцу [[E 3sOtu[e pap[siK oatt[ Jo[qqoo рие opməsnoy ‘ләр S,I9jutid 1 ays 94, °° * 4, *pi?s 92uo sjuajEq jo Jouorsuuwop yWesISSy ISA YANAL SIKƏIH #104 1941044 01 МОН 84315 ЧУЧ ГУЗ GEND SKETCH ORAR MODEL TO 12 Accept No Substitutes! Always Insist on the Advertised Brandt

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Built by Lloyd Spriggle, this trim streamlined motorboat is certain to win the admiration of ali boating enthusiasts. [т WILL take you longer to read this issue of Mecuanrx ILLustraTep than previous issues of your old friend “Modern Mechanix,” for the simple reason that we have added 16 solid pages to the editorial section! I am sure that you will like the many extra articles, the descriptions of new ideas and inventions, the big pictures, and the enlarged drawings of construction projects. True to its name, MECHANIX ILLUSTRATED will em- phasize illustrations of mechanical developments; it will publish live, human-interest photographs that you will find interesting, instructive and helpful. Workshop fans will, I am sure, þe pleased to know that more space will also be given to the ever-popular “Workbench” Department. Every month we receive hundreds of fine letters and pictures showing shop projects made from our plans and blueprints and we intend to publish as many as we can, to show how capable and skillful Mecuanix ILLUSTRATED readers really are. Send in your letters and photos for judging in next month's Workbench contest. LLLI First on the line this month is Lloyd Spriggle, of Bay City, Wis. who was awarded a $5 prize for his photos and letter describing his home- built boat. He writes: 14 Game err ee) Dear Editor: ] I am enclosing prints of my home- built boat. The rumble seat is en- closed by a cover which has sliding doors. When closed, the doors drop flush with the top creating a perfectly streamlined unit, which is strong enough to walk on. Lloyd Spriggle. You didn’t supply any informa- tion about speed, construction time, etc., Lloyd, but I just had to award you a prize because of the boat's appearance. It sure is a beauty. LLLI Remember the photo enlarger plans that ap- peared in our March issue? Well, C. E. Prange, of Toledo, Ohio, scored a $3 prize by sending in a photo of the enlarger that he built from those plans. He Says: Dear Editor: Here is a photo of the enlarger that I con- structed f ro m the plans in your March issue. It gives excellent re- sults. Your amateur photography section is great and I have re- ceived some good ideas from it. C. E Prange. Thanks for C. E. Prange built this photo enlarger from plans in our March, 1938 issue. Johnnie Bray and his home-built “five mule-power”’ tractor. Mechanix Illustrated—June, 1938

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the kind words, Prange. ГЇЇ do my best to keep you amateur photo fans supplied with practical suggestions and how-to-build. articles. Incidentally, the enlarger plans are reprinted in our new PHOTOGRAPHY HANDBOOK, now on sale at camera stores and on | newsstands everywhere. жж Im not a farmer, but I can tell a good tractor when I see one, and that’s why I sent a $3 award to Johnnie Bray, of Pinson, Tenn., whose letter reads: Dear Editor: The enclosed photo shows a tractor built by my brother and me. It features a four-cylinder engine and differential which were salvaged from old autos. The machine does the work of five mules and has six forward speeds and one reverse. The total construction cost was only $20, as we used parts from seven old autos and one tractor to build it. . Johnnie Bray. I wish I could invest $20 as profitably as you apparently have done, Johnnie! «oe You fellows who itch to get behind the steering wheel of a little four-wheeled “put-putter” will be interested in the letter I received from William Graham, of Hazel Park, Mich., who was Santos, William Graham built this midget car for his son. formerly Modern Mechanix racer was Harold Huntley sent in this photo of a racer buile by a friend. Capable of going 40 m.p.h., this tiny built by Froilan de los in far away Manila, also awarded a $3 prize. He says: Dear Editor: Enclosed is a photo of the midget racer which I built for my son from your plans. It is powered by a 1!4-horsepower lawn mower engine hooked up with a chain and V-belt drive. For safe operation I geared the car so that it will go 10 т.р.ћ. William Graham. I bet young Graham gets as much thrill when going 10 m.p.h. in his racer as some of you older fellows do. when you eat up the road at 70 or even 100 m.p-h. Take it easy, fellows, or “life may end at 40!” P. I. Жжжж From the far away Philippine Islands I received a letter from another midget-racer enthusiast, Froilan de los Santos, who was also winner of a $3 award. His letter reads: Dear Editor: I am a constant reader of your magazine. It is the real thing when it comes to dishing out information on mechanical projects. The en- closed photo shows a midget racer which I con- structed with the help of your information. The car is powered by a motorcycle engine and goes 40 m.p.h. at full gun. With the excep- tion of the engine, wheels and headlights, every- thing is home-built, even to the small steering wheel. Froilan de los Santos. [Continued on page 16] 15

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Chips From The Workbench [Continued from page 15] i E. Langille's version of Dorothy," a MECHANIX ILLUS. TRATED boat. He deviated from plans only in adding a pilot house, making it a good all-weather craft. As the saying goes, Froilan, "you've got some- thing there." wok There's no escaping these midget-racer fellows. Harold Huntley, of Kings Park, L. L, sent in a photo and letter that reduced the MI (MEcHANIx ILLUSTRATED, to you) treasury by $3 in the form of a Workbench award. He says: -Dear Editor: I am enclosing a photo of a midget racer that a friend of mine constructed It is powered by a 3/4 horsepower washing machine motor and runs all day on a gallon and a half of gasoline. The car operates under a regular license and is capable of a speed of 25 m.p.h., but cannot be reversed. It is started by stepping on a pedal connected to the engine. Howard Huntley. If Harold shares his $3 award with his friend, he will be able to buy enough gas to run his midget car for—well, you figure it out. »olek Being a boat lover myself, I warmed right up to a photo and letter sent in by E. Langille, of San Francisco, Calif. (The "warming up" cost MI a $3 prize.) His letter states: Dear Editor: Here is a photo of "Dorothy" which I built from plans in your book—How To Build 20 Boats. I added a pilot house, but the rest of the boat is constructed exactly according to your plans. The boat has. proved to be a good rough-water craft and I can assure you that the open Pacific Ocean is not always what its name implies. E. Langille. If anything, Langille, the pilot house has added to the boat's appearance. Good work! Awk D. B. Thomson, of the National Aero Reserve, 16 whose letter on the home-built airplane situation in our December, 1937 issue resulted in a flood of letters to the MI office, requests that all present and would-be plane builders contact the NAR regarding a bill that organization intends to pre- sent to Congress in an effort to secure modifi- cation of the laws governing the flying of home-built planes. Be sure and include a stamped, addressed return envelope when writing to the National Aero Reserve at 114 West 16 St, New York, N. Y. By the way, if any of you fellows think that the home-built plane situation is hopeless, wait until you read the article on the State of Oregon’s handling of the matter in a future issue of MI. ‚ня Powered scooters are becoming more and more popular. A photo and letter I received from Russell Harter, of New Castle, Ind., thoroughly merits the $3 award which was sent to him. He writes: Dear Editor: Enclosed is a photo of a three-wheeled power scooter which I constructed from odd parts. The complete frame is made from gas pipe and fittings. Powered by a one horsepower, four-cycle motor, the scooter can travel 27 m.p.h. and will -carry me 80 miles on a gallon of gasoline, The scooter features two speeds, an internal brake, universal joint steering, a spring seat and pneumatic tires. Russell Harter. The “voice of experience” tells me that there Ready for a jaunt over neighborhood roads at 27 m.p.h., Rus- sel! Harter sits comfortably on his home-built power scooter. will be many requests for reader Harter’s address as MI craftsmen feel the urge to duplicate his [Continued on page 18]

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AUDELS NEW 1938 AUTO GUIDE Practical Information in Handy Form,1540 Pages —15490 Illustrations. KNOW YOUR C A R: AUTO REPAIRS & SERVICE HELPS Allthe Parts of an Automobile—Au. tomotive Physics—The Gas Engine— How & Gas Engine Works—Gas En- gine Principles—Multi-Cylinder En- gines—Horse Power—Automobile Engines—Ingines: Stationary Parts — Engines: Moving Parts —Pistons— Piston Rings—Connecting Rods— Crank Shaits—The Valves—The Valve Gear —Cams and Cam Action— Valve Timlng—Cooling Systems— Gasollne—Fuel Feed Systems—The MIxture—Carburetors— Automatic Choke—Super-Chargers—Transmis- sions—Synchro-Mesh—Clutches— Universals and Propeller Shafts —The Differential—Rear Axles—The Run- ning Gear—Brakes— Wheel Allgn- ment—Knee Action— Steering Gear —Tires— Lubricants and Lubrication —Automotive Electricity —Ignition Systems—Magneto Ignition—Spark Plugs—Ignition Coils—Distributors —Automatie Spark Control—Igni- tion Timing — Generators — Starters— Generator and Starter Testing— | Lighting Systems—Storage Batteries —Battery Charging—Battery Test- ing Troubles. AUTOMOTIVE DIESEL ENGINES Including Questions and Answers The contents is progressively ar- ranged; thus making *. a text book and a reference book, to which you will refer again and again. INSIDE VIEWS OF ALL AUTOMOBILE PARTS FULLY ILLUSTRATED. GOOD NEWS—JUST OUT AUDELS NEW AUTOMOBILE GUIDE is NEW from cover to cover. Explaining the Theory. Construction and Servicing of modern motor cars, trucks and buses; and the application of auto type Diesel Engines. Written by an enginecring authority and presented with forcefuldirectness in plain language and simple terms, L^: generously illustrated. Itis an up-to- į date authoritative book of instruc- tions giving a new vision of the auto- motive field. Covers the entire subject in every detail. Does not dealinidle theories, but gives definite directions telling exactly what to do and how to doit. Itis packed full with important information. indispensable to auto mechanics, service men and owners. TO GET THIS ASSISTANCE FOR YOURSELF SIMPLY FILL IN AND MAIL COUPON TODAY ШҮ ШШ Ш CeCe 5 Please send me postpaid 4 + AUDELS NEW AUTOMOBILE о GUIDE ($4) for free examination, I£ I decide to keepit, I will send you $1 within 7 days; then remit $1 monthly o? until purchase price of $4 is paid, Other- wise, I will return it to you promptly, ЧТ; Name.....eeeoeooeeeeososoutoessosevessosoete 1540 PAGES $e 1540 ILLUSTRATIONS A SEE ^O Address......... esssvssocosena ‚зене еөз вв» ова FLEXIBLE BOUND:HANDY SIZE IT! 249° Оссирайоц....................5 РОУ йуж УЙ AUDEL, PUBLISHERS, 49 West 23rd Street, New York City a Teferenee:is eerie seonsedesetediii next «8M ek завот . MN? When Answering Advertisements Please Mention June Mechanix Illustrated 17

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Write today for ALLTED'S hig : 164 page Spring Catalog—packed with everything in Radio—at sensationally : low prices! 56 new, supervalue KNIGHT Radios, including Push- Button Tuning Models, latest Auto, Farm Radios, Phono-Radios—sets for AC, AC-DC, 6 volt, 2 volt, and $2 volt Operation—nt unequalled low prices! Latest Set-Builder’s Kits, Newest Amateur Gear, Sound Systems, Test Equipment; over 12,000 parts, books, tools, ete. Your every Radio need in one complete book—fast, dependablo service, lowest prices always, Send Coupon now for Free new Calalog. FREE! BUILDER'S PARTS LISTS We supply Free Parts Lists of matched kits for bulldi.g any circuit described in this or any Other magazlne, Just specify where seen. Allied Radio Corporation 833 Jackson Blvd., Dept. 6-F-8, Chicago O Send your new Spring-and-Summer Caialog- FREE. f c ATALO Га Address аашаа E a LP E TM Learn Profitable Profession е à S CE 3 in 90 days at Home: A Salaries of Men and Women in the fascinating mx B fession of Swedish Massa, е гоп ая high D to $70 per week but many prefer to open thelr own of- fices. Large Incomes from Doctors, hospitals, sanl- tariums and private patients come to those who шау through our training. Reducing alone offers rich rewards for specialists. Write for Anatomy l Charta, and booke let—They’re FR THE College of Swedish Massago ev 1601 Warren Bivd., Dept A38 - Chicago (Successor to National Codepneos Massaan you SE TEACH yo $ J LET US'u AT HOME eR Ete s n N БД о ЗЕТУ" № Write Dept. A REGINA SCHOSE OF LETTERING Washington Train at this Govern- ment Approved School for Good-Pay position Airlines need Trained Pilots Airplane Manufacturers need Lincoln Trained Men in demand. Comet to Lino as Pllot or Mechanic, and Maintenance Men. skllled Mechanics. Be a Pilot. Lincoln TraWing prepares you for Gov- ernment Rating as Private, ited Commercial or Transport (Commerctal) Pllot. 14 Modern Training Planes, Be an Airplane Mechanic. Lincoln Tralning repares you for Government Mechanle's License. rou get Practical experience In Alrplane and Engine Mainte~ nance, Overhaul, Assembly, Repalr. Sheet Metal, Welding, Radio. Aviation is Calling You. | Now is the tlme to train at Lincoln. Write Today for complete information. LINCOLN AIRPLANE & FLYING SCHOOL 506 Aircraft Bldg., Lincoln, Nebraska Chips From The Workbench (Continued from page 16] Constructed by Walter Ward, this two-masted schooner model would be an appropriate decoration for a boat lover’s “den.” scooter. How about it, Harter. letters? Will you answer жж Are you enough interested in stamps to corre- spond with an enthusiast living in England? If you are, the following letter will be of interest to you: Dear Editor: I wish to express my appreciation of your very fine magazine. There is no worthwhile counterpart of it over here and I always make a point of passing my copies on to friends. I should like to correspond with ether MI readers who are interested in stamps. My address is: 55 Bearton Road, Hitchin, Hertfordshire England. Harold T. Brown. жж Have you ever yearned for a “den” decorated with ship models? If you have, you will know how I felt when I saw the photo of the scale model of the schooner shown above. Sent in by Ila M. Ward, of Worcester, Mass., the letter accompany- ing the photo reads: Dear Editor: I am enclosing a photo of a model schooner built by my younger brother, Walter. The model has an overall length of 23 inches, stands 20 inches high and every inch of it was built by Walter, including sails, anchor, bells, lifeboats etc. The hull is made from four pieces of wood glued together. It is painted black with a white waterline and red bottom. The sails were made from an old shirt. Ila M. Ward. I am pleased to send Miss Ward a $3 prize. Her brother’s craftsmanship is certainly first class. —The Editor 18 Accept No Substitutes! Always Insist on the Advertised Brand!

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Staining Solution Improves Fingerprint Technique Crime prevention has gone into the biologist’s laboratory for its newest weapon. Fingerprint technique has been made more positive and ac- curate through the adoption of a staining solution known as Flemming’s reagent, which blackens the slight fatty deposit in fingerprints and makes the telltale marks show up plainly in many cases where they are too light and faint to be detected by methods previously used. Science’s newest aid to law enforcement comes through the ingenuity of Dr. Francis F. Lucas of the Bell Telephone Laboratories. Dr. Lucas had noticed that on many fingerprints the fine pow- der commonly employed by the police technicians does not stick. He knew that the stuff that holds the powder on a “good” fingerprint is a slight deposit of the body’s natural oil. The problem therefore was to find something to make even a slight trace of this oily material highly visible. He talked the problem over with some biologi- cal friends. They told him of Flemming’s solution, which has long been used in preparing tissues for microscopic examination. It is a mixture of solutions of osmic and chromic acid, which turns any fatty or oily substance intensely black. Dr, Lucas proceeded to work out an adaptation of the biologists’ technique for finger- printing use. ‘Paper bearing suspected fingerprints is first treated . with Flemming’s solution, and then dipped into a dye which under ultra-violet light glows with a brilliant blue-green hue. The fingerprint stands out black and stark against this shining background. Its finest details can be examined under a low-power microscope, or it can be photographed up to any enlargement de- sired. If the paper bears print or handwriting, filters over the camera lens can cut off the ink from registering on the film, leaving only the boldly showing fingerprints. Patents Hole-In-Wing Method To Slow Plane Landing An ingenious suction method for simultaneously slowing the landing speed of a high speed plane and for increasing the lift of its wings is revealed in a patent granted to Major Alexander P. de Seversky, famous New York designer of high performance military aircraft. Ports placed near the leading edge of the wing connect with suction ports on the under side of the wing toward the rear. Suction thus created simul- taneously slows the ship and cuts turbulence on the upper side of the wing, the inventor explains, thus increasing lift. Slowing by one means or another the extremely high landing speeds of military aircraft is a prob- lem of growing severity and interest to aircraft designers, it will be recalled in connection with the patent. When Answering Advertisements Please Mention June Mechanix Illustrated Be an the Payroll... Train at Home us п If you want to learn drafting as a profession—or if you want to learn drafting to advance in your present work—Engineer Dobe can train you at home in your spare time by his long established, proven- practical “Work-Job” Method. You'll be amazed at the speed with which you can learn in your spare tima by Engineer Dobe's Practical Method. Send coupon TO- DAY for frea book entitled “Success in , Draftsmans ship.” Engineer Dobe can pre« pare you just as he has trained thousands of suc- cessful students, aged 16 to 18 to past 50. His prac- tical ‘“Work-J ob” method requires no previous ex- perience. High school education not needed. He offers you a real oppor- tunity to get & complete training in drafting right in your home in a surprisingly few months. Engineer Dobe teaches his students until thoroughly trained and until holding a good paying job. Send for FREE BOOK The draftsman has rich opportunities for advancement and better pay in scores of fields. In Machinery, Building, Aviation, Electricity, Transportation, Automotives—drafts- men must be used. Many trained draftsmen will be needed on better jobs at better pay and shorter hours. Mail the coupon today for FREE Complete Outfit illustrated book ‘‘Successful Drafts- Furnished manship'^ and full details of Engi- neer Dobe's remarkable offer that in- fÆ cludes all necessary tools and : equipment. Learn just how you can be trained success- fully at home in your spare time. Now is the time to pre- pare, Send the coupon NOW, Doce €—X—— 1 I ENGINEER DOBE, Div, A473, Libertyville, Ill. 1 1 Send me your free book ‘Successful Draftsmanship.’’ I Please explain how you assist your graduates to good і positions us draftsmen. І |o —————————— =l I | AGO C59 coo ннн — Ó — — MÀ [ l ТОШ эзел д сыге a e a шы aaa a a [ E Stute ess Age... І П ас inl 19

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PEET NTO A BUSINESS THATS | resto, BUSINESS THATS G JAIR CONDITIONING AT HOME with iron AFTER crapuariac arn this new booming business thr. ter the modern **movie" way—right: illed engineers teach you pers m the screen—right in your iting for slower students, no: , BUYS THIS AMAZING NEW. $ ELECTRIC SALVA Close, ick shaves with the Hunter El Shaver! Operates on sensational ''vibrato ciple. Just plug into A. C. Outlet and i Pays for itself in a dozen ways y blades, brushes, soaps, lotions. eic. Ffoeatures—self-starting. self-cleaning, sel tug, self-oiltug. Priced amazing Plus easy- payment terms of only тс а а w everyone can afford to sbave by electric Your Own Shaver FREE! Get full details of our Fr Plan for user-agents. Demonstrate to ——collect enormous profits. All shaver: Day Free Trial, plus 1 year guarantee. _ minute while your territory is орот ticulars, address HUNTER SHAVER CO., St., Dept. G-S1, Newark, N. J. HUGE PROFITS ror SALESMEN” 100/13: SS ТИЙ It's easy and economical to suppiy your own power for oper- ating ah types of machinery. and da more: work for Tess money, Simply remove the engine from a used automobile or truck, set it up where you like, attach a PIERCE UNI. VERSAL GOVERNOR. start the engine and you have con- stantly controlled power for the operation of electric light- ipa plante. are nodes refrigerating units. air compressors, e inders, hoists, saw mills and in: * ap. РИ le s innumerable other ap e load may change but the PIERCE UNIVERSAL GOVERNOR will maintain a uniform engine speed. For close regulation of speed and dependable per- formance TIERCE GOVERNORS аге never equalled. Installation Is simple. Either V or flat belts can be used. Com: plete Governor outfits are also available for nearly all makes and models of in- *ustrial engines. Write for illustrated literature and Trices. THE PIERCE GOVERNOR COMPANY 1522 Ohio Avenue, Anderson, Indiana PIERCE GOVERNORS THE BRAINS OF ANY GAS ENGINE ~ | World's Biggest Welded Boat Shown above is a night view from the bridge, looking aft, of the world’s largest welded ship, a new 18,500-ton tanker, the S. S. J. W. Van Руке. The vessel.has a cargo capacity of 6,552,000 gallons of gasoline—enough to supply the aver- age requirements of nearly 10,000 motorists for a full year. Her overall length is 543 feet; her sea speed 13.25 knots. The J. W. Van Dyke is now in service between Philadelphia and Texas Gulf ports, carrying gasoline produced by a well known oil refining company. Chemical Preserves Fish A dilute solution of hydrogen peroxide is being used by the fisheries industry of Germany to aid in the preservation of fish, according to Industrial and Engineering Chemistry, journal of the Ameri- can Chemical Society. Eviscerated, marine fish or fish fillets are given a brief preliminary treatment with a 30 per cent solution of hydrogen peroxide that has been di- luted in the ratio one to 100. The treatment is carried out as quickly as possible after the fish are landed and before they are iced for shipment. In odor, appearance and taste the fish thus treated remain in satisfactory condition about three to six days longer than untreated fish. Craters bored by falling meteorites are known only in a few places on earth. The silvery look of a dirigible is due to an aluminum coating, which reflects light and keeps the interior cooler. 20 Accept No Substitutes!’ Always Insist on the Advertised Brand!

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Photography Used To Detect Counterfeits Of Rare Books W 7H famous early printed books, and even those not so ancient, selling for as much as $5,000 a copy, there is every reason to watch for forgeries or facsimiles that are intended to trick the unwary collector or librarian into paying more than a thousand times what the books are really worth. Facsimile copies of rare books serve a very useful purpose in making classics available to scholars who can not consult the highly prized and closely guarded originals. But when they are allowed to creep into valuable collections in the guise of the originals themselves, it is like circulating counterfeit money. One of the leading bibliophile detectives is Dr. L. Bendikson, chief of the Huntington Li- brary's department of photographic reproduc- tions. He tells how to distinguish between a photolithographie copy of a rare document—the most deceiving sort of reprint—and an original. A portion of the disputed page and the corre- sponding part of the original are photographed upon 35 mm. micro-film and then enlarged. The letters of the lithographed reprint will be found to be not clean cut as they are when they are printed from type. They bulge irregularly in different parts and are irregular in outline. One look is enough to show that the two copies are not the same. Various lights, microscopy and chemical analy- sis are also used in this literary detective work. Sometimes the paper or the ink can be shown to be modern whereas the document is supposed to be old. A letter written by Christopher Columbus in 1493 to announce his discovery of what proved to be a new world was the subject of one of the most famous of literary counterfeits, so pronounced in a famous lawsuit in 1899. Shell Develops High H.P. At least 10,000,000 horsepower is developed by a main battery or coast defense gun during the short interval in which the projectile moves through the bore, it is revealed in ballistic physics tests made at the Naval Proving Grounds at Dahlgren, Va. à So powerful is a single gun of this type while hurling its ton weight shell that for the moment it has an output greater than the combined output of the power plants propelling the battle fleet of the United States Navy, it is asserted. Piano keys can be made of plastic in place of the usual ivory. "I'll prove in only 1 days Ican make YOU a NEW No other Physical Instructor has ever DARED make such an offer By CHARLES ATLAS Holder of the Title: * The World's Most Per- fectly Developed Man" OU don’t have , to take my word —nor that of hundreds of my pupils who have added inches to thelr chests, biceps, necks, thighs and calves. Prove fer pourscli in just me week that you, too, ran actually become ao husky, : healthy, NEW MAN! My Dynamic Tension system does That's bow I built myself from a 5 GT-pound weakling to “Тһе World's Most Perfectly Developed Man.” Let me prove that you can get a big bal- anced muscular development in the same casy way. Gamble a Stamp — Mail Coupon for FREE Book! Dynamie Tension is a natura] method of developing you, inside and out— without using any pills, unnatural dietlng, or tricky weights or pulleys that may strain your heart or other vitul organs, It goes after such ailments as constipation, pimples, skin blotches, and other conditions that keep you from really enjoying life. Gamble a stamp today. Mall coupon for 2 [ree copy of my new illustrated book, “Everlasting Health and Strength.” IL shows you, from actual photos, how I have dereloped ray pupils to the same perfectly balanced pro- porttons of my own physique. Jot your name and address down on the it STERLING SILVER CUP BEING GIVEN AWAY This valuable cup stands about 14” coupon, Send it to me personally. CHARLES E ATLAR, Dept, 66, 115 East 23rd Street, J DB on a, black New N. X. k I will award it - ча "= к= тыш иш иш Eu шз гн иы тз ua жь (0 my pupil who 1 CHARLES ATLAS, Dept. 66 Trapróvement ТЩ 115 East 23rd Street, New York, N. Y. his development I want the proof that your system of Dynamic Tension will make a New Man of me—glve me a healthy, husky body, and big muscle development, Send me your free book, “Everlasting Health and Strength." within the next three months. Name ........ оосо VP UTR ol sescotoosoveveseos (Please print or write plainly) FUUI „аладан еке serta m setresevosspascoteooe СИУ „заа vett m T PERLCDCSYTEETEDETET When Answering Advertisements Please Mention June Mechanix Illustrated 21

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[кыен ==» e kai = a] SS SS кекек =н 0—1 —— ——_ BEC к= иш ч a | a ке PARARE wN ka [pel on approval, Just mail the coupon and we'll send you a set of these remarkable auio books, just off the press, Whether you are a mechanic or helper, ex- Pert or apprentice, auto owner or driver, if you’re interested in knowing ail about automobile mechanics, take advantage of this FREE OFFER! GET A BETTER JOB К \ 2 & better Job—in ne glgantig joule une justry, BIGGER PAY—a chance to go into CAN YOU FIX IT? business for yourself and get & share of step by step HOW to the huge profits, aro waiting for any man jake out "play" in dif- who even half tries to improve himself. ne "un ud dii the Learn aulo engineering with these wonder set TIMING—how to put books a new way—without studying or your finger Instantly, on memorizing, k и use the JIFFY IN- де топос ать en DEX to look up the answer to any auto the quick export Way tO problem, Built by eleven of America’s provements greatest automobile engineers, and written in simplo language so you can understand "Very newest cars, all covered, FREE Privilege of consulting Automobile Engineers of Amer- ican Technical Society for one yeat without cost if you mail coupon immediately Books also include valuable articles on Service Shop Management, fully cov- ered. Equal toa complete trade course at less than jt, a fourth the cost. = 6 BIG VOLUMES Brand New Edition 2500 pages, 2000 illus. trations, wiring dia- grams, ete., including Marine Engines, Avia- tion Motors, Diesel en- gines, ес, De Luxe que ion, gold-stamped flex- ible binding. P AMERICAN TECHNICAL SOCIETY Drexel Ave. & 58th St., Dept. AA 320, Chicago, IIl. I would like to see the new 6-volume edition of your AUTO BOOKS. I will pay the few cents delive charges only, but if I choose to, I may return them express collect. If after 10 days use I prefer to yeep them, I will sen ou $2 and gz the balance at the rate of only $3 a month, until $24.80 is paid. Please include free Ruling membership as per your offer above. Powerf ul—A4ccurate—Economical—Practicai— AdjustableShootingForce—Amazing Maximum Vel ary cal. 177 or 22 and BB—For Target and 5 Small Game—the only Genulne Compressed T Alr Pistol for Shooting BB on the market—Single Shot with Holt Action—Hamrner Fire—Halr Trigger—Safety. Price $7.50. Holster $2.00. Aleo 177 and 22 Single Shot Air Rifles $7.50— Single Shot BB Alr mure юр Shot BB Repeater Air Rifle 50-1 rect—No license required—Safe for in- EU use. FULL DETAILS TARGETS FREE WRITE TODAY. Benjamin Air Rifle Co., 831 Marlon St. St. Louis, Mo. TRIAL LESSON IN More good Jobs now in Drafting. Learn AT HOME in spare time (orat our Chicago School). Send post card for FREE TRIAL LESSON and, see how easy to learn and get & good job. CHICAGO TECHNICAL COLLEGE G263 Tech. Bidg,, 118 E. 26th St., Chicago, II. Iffyou can go away to college to_learn, Drafting, Engineering, Architecture, Miectricity, Air Conditioning of Radio—send for FREE Biue Book. Onan A.C. plants furnish same B current as city lines, 110 Volt, в 60 Cy For farms, camps, con- struction jobs. Operate radios, water systems, all appliances. New modeis, 350 to 5000 watts, 6, 12, 32 and 110 volt D.C. B Models $57 50 and up Alsog combination A.C -D.C units. | Shipped complete, ready to run. E _ Write for details, D. W. ONAN & SONS 1756 Royalston Ave Minneápolis Minnesota Curved Floor Dryer Speeds Up Cleaning Process Speedier floor cleaning is said to result through the use of a newly developed curved-blade floor dryer. The blade, made of rubber, holds the water with cleaning material in its curve, carry- ing it where the operator wants it. As the dryer removes all the water from the pores of the floor and since the water is not picked up until the entire floor is cleaned, fewer rinsings are needed. The device can be used for sweeping the floor without raising dust by placing a damp cloth under the blade. Praise For Women Drivers Science has come to the defense of the woman driver. If she is not so efficient as are the men, it is not because of her sex or innate abilities but merely because she lacks the driving experience necessary for greatest skill. This is shown by test of more than 2,000 persons on vision, reaction, time, and other essential abili- ties for the automobile driver, made by Dr. A. R. Lauer, associate professor of psychology at Iowa State College. __ Only in strength of grip was there any difference between the sexes, Among the younger persons tested, the men were somewhat better than the women in judging distance. Women were some- what inferior in tests of performance .of skills resembling auto driving, due to the Jack of experi- ence of those tested. 23 Accept No Substitutes! Always Insist on the Advertised Brand!

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Device Uses Light Beams To Test Paper Surfaces How smooth is a piece of paper? Seems simple, doesn’t it, when you contrast the feel of a glossy “quality magazine with the rough coarseness of the so-called “pulps.” But your finger will not be sufficient if you are a printer and have to choose the proper ink. To give a definite numerical basis for paper smoothness a device has been patented (No. 2,050,486) by N. M. Davis and H. E. Malmstrom of Appleton, Wis. A photoelectric cell, glass prisms and plates, a small hydraulic press and a light beam pro- jector are essentials of the device, which utilizes well-known principles of optics. One of the best known feats of the science of optics is to bend light around corners with in- ternal reflection in prisms. High-grade compact field glasses and submarine periscopes are only two of many devices which use this well-known phenomenon. If, however, a piece of paper is pressed against the back face of the prism which reflects the light, some of the light is not reflected but passes out of the prism and is lost. The degree of re- flection depends on how good is the contact between the prism face and the paper. Good contact great reflection loss; poor contact little light loss. In the new device a beam of light enters the prism, strikes the two back faces in succession and is caught by the photo cell and turned into electrical current which can be measured. The smoothness of the paper sample under test is determined if it is pressed against the back face and reduces the light intensity coming out. Smooth papers make good contact and greatly lower the intensity, while rough coarse papers cannot make as good contact and dim the light less. The amount of electrical current generated in eaeh case is thus a measure of the smoothness of the two papers. The moon gives off no light of its own, but it reflects light from the sun which travels to the earth in a little over a minute. Sponge rubber is being used like cement in tree surgery to fill cavities. Silicosis, a lung disease contracted in dusty oc- eupations, is called the greatest single occupational hazard in this country. A new farm machine invented in Russia is a beet harvester combine that pulls up beet roots and removes the earth and leaves clinging to them. Red or yellow ocher mixed with road surface material is a new safety idea, because the ocher makes the road somewhat luminous at night. When Answering Advertisements Please Mention June Mechanix Illustrated D With Gillette's. lew Senator- Model Razor. — Tor DEMPSEY is right. Gillette’s new one- piece Senator is a knockout. And at only 69¢, including 5 Gillette Blades, it’s the greatest shav- ing value ever offered! You'll like this new- type razor. It’s sturdy, good looking and amaz- ingly convenient. Actually you can change blades in three seconds. The head opens and closes with a simple twist of the handle. There are no loose parts to drop. See your dealer. Ask for the heavily nickel-plated new Gillette Senator Razor with five blades for only 69¢! Gillette’s New Brushless Shaving Cream Prepare your beard for perfect shaves with Gil- Jetce's New Brushless Cream. Made with peanut oil,it softens wiry whiskers, stays moist, speeds shaving, won't clog your razor. Try a tube. You'll like it! Large tube only 25¢. 23

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AND BLUEPRINTS FOR PRACTICAL MEN VLA These MECHANIX ILLUSTRATED Books Will Help You To Get Maximum Benefit From Your Hobby Or Workshop HOW TO BUILD 20 BOATS Plans and construction details for easy-to-build boats ranging in size from 7 to 27 feet, and a wealth of incidental information for the man who already owns one. Complete instructions for reconditioning boats, handikinks, navigation tips, etc. 144 pages, jns d "——— M —— наө БОС PHOTOGRAPHY HANDBOOK A complete photo manual that tells in non-technical language how to develop, print and enlarge films; how to make your own darkroom equipment at small cost; how to improve your camera and how to make good pictures. No matter what kind of a camera you own you will find this book an inval- table aid. 144 pages, price... БОС HANDY MAN’S HOME MANUAL You don’t have to be an expert mechanic to keep your house in tip-top condition, Secure a copy of this book and you'll save its cost over and over by learning to make simple repairs and improvements without the need of calling in outside help for it is FN filled with practical how-to-make, how-to- ^w improve and how-to-repair kinks. 144 = . eee PAGES, PTICE crrcrrerrsrerrsetereeerreres БОС ыта "- CUT OUT ea AND MAIL TODAY! “=e BL P FAWCETT PUBLICATIONS, Inc. GREENWICH, CÓNN. m: Enclosed is a money order or check for sse = “me ЫД Send me a copy (or copies) o£ «essere DL] Three cents enclosed. Please send me a Blueprint Catalog. Address ... SPORTSMEN'S ANNUAL Do you fish, hunt, or camp? If you do, you'll find this book a veritable encyclopedia of outdoor in- formation—new angles for the angler, handikinks for the sportsmen and new ideas for campers. You'll like this profusely illustrated outdoor book. 144 pages, price .......... сынны анн ннн ннн ЕКЕ Енен ЕККЕН Бос HOW TO BUILD TRAILERS Follow the open road in trailer built by yourself. This book features complete plans and construction details for building seven different cabin trailers, two boat trailers,-delivery trailers and many trailer kinks, shortcuts and camping tips. 144 pages, PTICE ынан ннн ин рны ннн ннн ыиы БОС HOW TO BUILD IT Whether your workshop is small or large, you'll find projects in this book that will supply ample outlet for your skill with tools. Complete plans and con- struction details for building a midget auto racer, model locomotive, gas-powered airplane, play- ground equipment, toys, etc. 144 pages and the price A S mier etre erc rd E Eee ied poc ALL BOOKS SENT POSTPAID FREE!— A copy of the MECHANIX ILLUSTRATED Blue- print Catalog will be sent to you free upon receipt of a three-cent stamp to cover mailing. The catalog lists all available MI blueprints and many technical and hobby books. 24 Accept No Substitutes! Always Insist on the Advertised Brandt

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Model Normandie Powered By Small Steam Engine A model of the transoceanic liner Normandie, which is powered by a small steam engine, was recently constructed by Henri Devoize, of Paris, France. The engine is removable, the super- structure of the model being so designed that it clamps into position on the hull. When run- ing, the smoke from the steam engine pours from one of the model liner's funnels, creating a very realistic apoearance. The model weighs 30 pounds completely equipped. Invents Practice Ray Gun A practice machine gun that sounds, and even jams like the real article and, in fact, does about everything but fire bullets has been patented (No. 2,069,750) by Capt. Charles H. Coates, of the U. S. Army, stationed at Vancouver, Wash. Moreover, the practice gun gives a visual ap- pearance to the operator, of firing actual bursts of bullets. This it does by “shooting” a cone of light rays at the target instead of bullets. By observing where the light rays strike and light up the target, the gunner knows whether he has made a hit. Captain Coates’ practice machine gun has as its nucleus a real machine gun. To such a gun, he attaches a long bar under the gun barrel in parallel arrangement with the axis of the bore. The outward tip of the bar carries a focussing lens. i To shoot, first the gunner sights the gun on the target, then pulls the trigger. This closes a switch on the trigger. A flashlight goes on, the lens catches its light and sends rays streaming toward the target. Simultaneously a clapper sounds out a “rat-tat-tat.” By pulling and re- leasing the trigger, the operator controls the length of the bursts of light “bullets.” When Answering Advertisements Please Mention June Mechanix Illustrated $1260 to $2100 a Year | 42,766 Appointments Last Gov’t Year MANY 1938 APPOINTMENTS EXPECTED Railway Postal Clerks Railway Postal Clerks get $1,900 the first year regular, being paid on the first and fifteenth of each month. ($79.17 each pay day.) Their pay is automatically increased yearly to $2,450. Advance may be had to Chief Clerk at $2,700 a year, ($112.50 each pay day.) e =z * d Z 3 Days On—3 Days Off—Full Pay Railway Postal Clerks on long runs usually work 3 days and have 3 days off duty or in the same proportion, During this off duty their pay continues just as though they were working. They travel on a pass when on business. When they grow old, they are retired with a pension. City Mail Carriers, Post Office Clerks Clerks and Carriers now get $1.700 the first year on regular and automatically increase $100 a year to $2,100 and $2,300, Customs Inspector Salary $2,100 to start. Men 23 to 45. Work connected with examining baggage and merchandise entering the country from foreign parts covering boats, trains, roads, automobiles, etc. Many Other Positions Many other pogitions are obtainable. Those wishing these positions should qualify at once. Get Free List of Positions Fill out the following coupon. Tear it off and mail it today—now, at once. . . . This investment may result in your getting a big-paid government job. BER RE REP RS ER EE SETS ЕШ щш Шы ил їн ПШ иш eee ни FRANKLIN INSTITUTE, Dept. R263, Rochester, N. Y. Rush to me, entirely free of charge (1) a full description of U. S. Government Jobs; (2) Free copy of illustrated 32-page book, ''How to Get a Government Job'"; (3) List of U. S. Government Jobs; (1) Tell me what to do to qualify for a U. S. Government Job, Name ....eeeeeee enhn езж о» reer rere rer er ee errr rere re j Address ,..... desechos rsen катаа жж» : Use This Coupon Before You Mislay It, Write or Print Plainly. 25

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e 37 Be Your Own. MUSIC Teacher LEARN AT HOME by wonderful improved method. Sim- ple a s A-B-C—a child can learn it. Your lessons consist of real selections, instead of tiresome exer- еіѕеѕ Each of these delightfully easy lessons add a new ''plece" to your list. You read real notes, too—no ‘‘numbers” or trick music. Method is so thorough that many of our 700,000 students are band and orchestra LEADERS, Be Popular Everything is in print and pictures, are told what to do. Then a picture shows you how, In a few short months you may ресопе an excellent musician—the life of every party Free Book and Demonstration Lesson Write at once for our illustrated Free Book &nd T'ree Demonstration Lesson, Please men- tion your favorite Instrument, No obligations. Instruments supplied when needed, cash or eredit, (Fortleth Year—Est. 1898.) U. S. 2626 вен БООР, ОК, Мизс М. Ү, RAISE POULTRY FOR PROFIT START AT HOME. MARKET WAITING. barn or backyard all that is needed. NS arn eet methods from our Home Study Course and put cash in your pockets every day. We train you, help you, Get facts ‘about our unusual offer NOW! Men ‘and ing money in every state—town M try. Send for illustrated FREE BOOK todayl oe NATIONAL POULTRY INSTITUTE cD Dept. 132-D Adams Center, N. Y. First you Hawaiian Steel Guitar .. Trumpet , Piano Accordion Plain Accordion Voice and Speech| Culture Harmony and Composition Drums and Traps ss BY SHOP WORK I'll Finance Your Training . Prepare for jobs in Broadcasting, Talking Pictures, T'elevision, Wireless, etc., by 12 we weeks practical shop training in Coyne Shops. Free Employment Service. Many earn while learning. You don’t need previous experience or a lot of book P- learning. Write for BIG FREE RADIO and TELEVISION gf BOOK aud my 7 Pay Tuition After-Graduation’? Plan. ‚©. 3, Pres., 10 DIV.. Coyne Electrical School 500 S. Paulina Street Dept: A8-1H Chicago, Illinois a Day for a 60 sec- ond Demonstration, EVERY HOME CAN AFFORD THIS AMAZING LOW COST NEW IMPROVED ELECTRİC WATER HEATER. Made by an OLD Reliable Company. Amazing New Principle Heats Water Instantly, Just plug in the light socket. SELLS FAST and Pays Agents up to 233% PROFIT. FREE SAMPLE OF- FER—No Risk, Write at once for details, THE LUX COMPANY Dept. 635, Elkhart, Ind. 26 Accept No Substitutes? BIG MONEY Assembling NEW BOAT! Make big money on each 20-Ib, Mead KI-YAK you easily assemble at home _ from complete ''cut-to-fit" Kit at amazing 7 LOW COST! Seaworthy, Fast! Snappiest 1 GIVEN! = thing afloat. (Complete Sailing Rig, a 436 Double-blade few dollars extra.) Rush 10e for illus- Pd dm TON trated folder and $6 Paddle Gift Offert |EPYan-at you MEAD GLIDERS, 15 S, Market, hurry! Dept. M-68, CHICAGO, ILL, MAN IN EACH TOWN To Plate Auto Parts Xtefleetors, Bicycles, Fixtures, Mirrors, by late method. Simple plan of manufacturing at home starts you IN GOOD PAYING BUSINESS. Write today for FREE particulars and proofs. GUNMETAL CO., Ave, P, Decatur, Iii. TYPEWRITERS —DUPLICATORS— ADDERS—FOLDERS— ADDRESSOGRAPHS Less Than Half Original Cost FREE TRIAL! MONEY BACK GUARANTEE! Typing Course & Table Free. Write for Bargains! Name what you want. Send No money! Low as 10c a day! CHICAGO PRUITT CO., 935 PRUITT BLDG., MAKE MONEY AT H Amazing rubber mold-making outfit makes perfect flexible molds of plaques, ash trays book-ends, etc. Molds cost from 6¢ to 25c each. Each mold makes hundreds of novelties and gifts to sell up to $1.00 apiece! No experience necessary. Everything furs # 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- tions. 50-.0 WORKS, Dept. F-82324, Cincinnati, Ohio. Te Ug The new WHIZ ELECTRIC TOOL DRILLS is the handiest, most useful | GRINDS | power tool ever made. Not delicate instrument but a rea rugged tool, equally effective for SANDS SAWS both power and precision work, Drills through 14 ineh iron plate in 42 seconds or engraves intri- cate designs on jewelry. Handles any material 8-Woods-Al- loys-Plasti Glass - Steel-ete. Saves time. Eliminates tedious labor. Plug into any_socket AC or DC, 110 volts, Chuck 14" capacity. Ball bearing thrust. Powerful, triple-geared motor. “Worth its welght in gold,” to mechanic or handy man, STANDARD MODEL with Normal Speed (uses 50 Gifferent accessorie: nstantly interchangeable). Special Introductory Price for a limited time, only $6.95. FREE Accessory outfit (Value $2) includes set of drills, mounted 114” grinder, sanding discs, cutting wheels, mounted brush, polishing wheel, carving bur, FREE with each outfit ordered NOW. We pay postage on all shipmne: Will send C.O.D. if deslred. 10 DAY TRIAL—MONEY BACK GUARANT к ecla EED High Speed one outfit (uses 200 complete. with same accessory outfit (val PARAMOUNT PRODUCTS CO. 48 W. 48th St., STOP /ckrackingz == Haven't you often t driven the wrong road and had to backtrack many miles? The Hull Stream- 2 line Auto Compass always shows your direc- tion of travel, prevents backtracking, saves money and time for only $2.95 at your dealer. Two-piece model $1.95. Write for eircular. HULL MFG, CO., P. 0. Box 245-M2, WARREN, OHIO Always Insist on the Advertised Brand!

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Stereoscopic Projector Aids In Making Of Aerial Maps 1 1 ad 1 Aerial mapping is now reaching a stage of ac- curacy and speed which is destined to relieve the surveyor, with his transit and theodolite, of much of his roughest work. Jobs that would have taken him weeks can now be accomplished in a few hours by the use of a plane, a camera, and a new stereomapping projector which has been developed by a well known optical firm in Rochester, N. Y. An automatic camera in the plane, shooting at regular intervals, makes pictures a mile apart. Terrain features are thus seen from different positions in succeeding photos just as the two eyes, seeing things from slightly different posi- tions, get depth perception. If the two eyes re- spectively see the views taken a mile apart, the effect is as if the mapmaker had eyes a mile apart. To achieve this, the 7"x9" film negatives, each covering from the usual altitude of 20,000 feet, about 13 square miles, are printed on small glass plates about the size of two special delivery stamps. The utmost exactness is required in the adjustment of the instruments since a difference of one ten-thousandth of an inch might mean a difference of feet in the field. From the glass plates the picture is projected down on a drafting table by two adjacent projectors operating in red and blue light respectively. With six separate adjustments on each pro- jector set to produce exactly the same angular position that the camera occupied when making the corresponding negative, the mapper, wearing spectacles with one red and one blue lens, sud- denly sees a single illusory three-dimensional model of the terrain on the table before him. The effect is so realistic that he may feel an impulse to pat the top of a smooth hill or prick his finger on a telephone pole. types INTERNAL COMBUSTION ENGINES, ELECTRIC POWER GENERATION, Etc. YOU MEN who are sincerely ambitious to make good in the Diesel and related industries, want to know the true facts—you want to know about employment opportunities and employment requirements, For 83 years, National Schools, à recognized leader in the field of trade education, has played a vital part in helping wide-awake men to qualify for success in industry, National Schools—a million-dollar trade school—will supply you with a sincere, honest statement of facts on what you should do to get into the profitable Diesel Industry, No exaggerations—no mls-statements, YOU NEED REAL SHOP EXPERIENCE WITH TIME-TESTED TRAINING. Mail the coupon below, In the literature you will be sent, you will see exactly how other men like you are preparing lhemselves for success in Nationals modern training shops. You learn on the latest, finest equipment, You do real job work, You learn by time-tested, shop-practice methods, ‘Your training is fascinating in every detail. You are taught how to make good, and helped to make good after you graduate, All of this and much more is clearly pictured for you in the Free Book of Facts we will send to you. TRANSPORTATION ALLOWED TO LOS ANGELES National Students are allowed coach railroad fare from any point in U. S. (Canadian students [rom nearest point of entry). Student social life includes inspection trips, excursions, athletic activities, etc, Special doctor service, Personality coaching. Many students are helped with spare-time jobs to earn room and board while learning, (Canadians excepted.) Graduate employment cooperation, ALLONAL SCHOOLS NN NANA NAN pre Free Book € NATIONAL SCHOOLS [established 1905) Dept. MMA-6 € 4000 South Figueroa Street, Los Angeles ( Please send me, without obligation, your FREE BOOK and information ~ regarding Diesel Employment Opportunities and Requirements, NAME comes nu l-—-——— iU ER STATE LL LL PPA PDD LDP PDD GA SOINS GÀ NGI CI SANG SQ SQ SG SG SG kawra When Answering Advertisements Please Mention June Mechanix Illustrated 27

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Grab thie opportunity to get the most up to date in- formation on this new pro- žesaion, which із bound to Tevolutionize building, From starb to finish these б great books cover the whole fleld. from ait conditioning old houses, converting old heating eysteme to the proper, method of design and installation for use in tho most modern buildings. It won't be long, befuro every corpenter every architect, every plumber or anyone who hag anything to do with building will be expected to be iully familiar with the ecience of air conditioning Here is your opportunity to get this information FRESE for trial. Over 2000 Pages - 800 Illustrations These books are beautifully bound in modernistic binding simulating leather and are chock {ull of invaluable information for any one in the building field. Whether you are a beginner or on expert, you should have a set of these books which will be sent to you upon our FREE examination offer. Send the :oupon—the full Membership o9 biz volumes will be forwarded promptly. — FREE: Bend now and we will mclude a membership in the American Tech- nical Society giv- ang privilege of consultation with @ur engineers lor ne year on any New Money Making Profession Air conditioning is new but it is already in great demand and men who are smart enough to get into thia work now arc bound to profit by their foresight. Up to now very little infor- mation hag been available. Men who knew wuch about the subject have guarded this information jealously, but here ia the most up-to-date information and it all comes to you with- oub any obligation other tlun to examine it before you decide whether or not you want to keep the books. Don't delay. n Be the first in your locality to fit yoursetf lor a profession which diffcult — problem will probably grow like wildfire a8 soon as the coming building without cost. boom gets under way. Send the coupon today. Amerlcan Technicai Society Drexel Ave. & 58th St.. Dept. KA320, Chicago, IIl. I would like to see the new 6-volume edition of your Air Conditioning Booka, 1 will pay tho few cente delivery charges only. but if I choose to, I may return them express leot. If after 10 days use I prefer to keop them, I will eend you $2 and pay the balance 26 the rate of only $3 a month. until $24.80 is paid. Please include free consulting imembership as per your offer above. State č ago, occupation and name and address of employer and that least arie business mnn as reference, © REAL MONEY -x 2-—»« New RANGER SCOOTER There’s big money selling this new, marvelous improved RANGER SCOOTER to all stores needing quick, cheap delivery—or renting to riders! ood territory still open. ^ ER SCOOTER is safe, Sturdy -sets 120 КЕЕ EASY TERMS RENTING cm to gallon at 30° m.p.h Á folder. Special Low A Mis for кез DAC. folder. Special Low Agents’ Prices $7 MEAD CYCLE CO. : 0* = MECHANICS Mand. Complete courses in are and acetylene welding, metal finishing, body УЯ (O FINANCED. Act now! Dept. DS-279 Chicago, U. S. A. Auto Mechanies and Welders are in big de- and fender bumping, spray painting. Special low rates. Pay after Graduation fer Plan. Write today. | Е Р E Е MICHIGAN TRADE SCHOOL NTWTET 3763 Woodward Ave., Detrolt, Mich. l ‘We supply you 2 separate outfits of Electri- f p REAL. n" Sorte hd you legen Bractcal е EQUIPMENT cost to help you learn t RIGHT IN YOUR your own Home Shop. No previous experi- enceor adyanced education necessary. Life- time Employment Service. Write for Big OWN HOME Free Electrical Book Today! No obligation. Bol ELECTRIC INSTITUTE, Dept. 48G, Hinsdale, Ill, ШУ dd Old And New In Projeciors The great advances which have been made in the design and construction of motion picture projectors is shown in the photograph above. B. A. Cawthorn, a projectionist in a theater in Jacksonville, Florida, is holding an 1890 model projection machine which was capable of handling about 100 feet of film and boasted a small acetylene lamp as a light source. The huge modern projector shown in the photo has a 7000-watt light source and handles about 3000 feet of film. Clipper Airplanes Can Make Full-Speed Turns On Water A sober picture of the performance char- acteristics of the giant transoceanic clipper flying boats that have excited the admiration of the entire world was presented to the national aero- nautic meeting of the Society of Automotive Engineers held in Washington, D. C., by Wil- liam K. Ebel, engineer of the Glenn L. Martin Company, builders of the Pacific and Soviet clippers. The great metal birds can figuratively turn on a dime even when taxying at high speed pre- paratory to taking off, Mr. Ebel told his audi- ence. Should an obstruction appear on the water lane down which the boat is roaring for the take- off, the pilot can cut two motors on one side and swing his rudder at the same time, taking the boat quickly and safely out of harm's way. 28 Accept No Substitutes? Always Insist on the Advertised Brand!

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IN THE JULY ISSUE OF MECHANIX ILLUSTRATED SMALL DIESELS—NEXT BOOM INDUSTRY— A leading Detroit manufacturer is preparing to spend several millions on new factories, new machines, new tools and ideas for the mass production of small size Diesel engines for many applications in the home, the shop and the farm. Almost overnight a boom industry is developing, and is creating many oppor- tunities for men versed in Various phases of Diesel design, construction, sales and maintenance, NO MORE MOTOR FEVER—Car owners spend time and money preparing their cars for winter driv- ing, but neglect to condition them for hot weather driving. This authoritative article contains many helpful and valuable suggestions that every driver сап read and profit. METAL LUNGS GIVE LIFE—Many a potential victim of infantile paralysis has been saved from painful suffocation by artificial respirators, popularly known as “iron lungs.” Do you know how they work? This interesting article tells (literally) the inside story. Don't forget that MECHANIX ILLUSTRATED runs the largest and best Photography Department in print! The July issue will have 15 pages of practical, useful data for all camera owners, includ- ing the following articles: “What the F. Numbers Mean;" “Close-Up Camera Takes Big Pictures;” “Toy Motor Makes Tank Agitator; “Simple De- veloping Rack;” and many ingenious kinks and short cuts. Also in the July issue: hobby, craft and shop projects; auto, household, shop and camp kinks; boat and model airplane plans. Don’t miss this big 15 cent magazine, on sale at all newsstands! College Physicists Achieve Levitation Scientifically Real levitation has been achieved at the Uni- versity of Virginia, but not by supernatural means or for purposes usually associated with the word. Dr. F. T. Holmes and Prof. J. W. Beams of the physics department spin a rotor 1,200 times a second as it is suspended in a vacuum in their researches. A clever balancing of the downward thrust of gravitation by an upward thrust of mag- netic forces is the way the levitation is accom- plished. So free from friction is this type of suspension that once the rotor gains its top speeds it deceler- ates at the rate of only one revolution per second, in a time of eight minutes. This means that if the balancing forces were applied continuously it would take six and two-third days for the rotor to come to a stop once it attained its velocity of 1,200 revolutions a second. Powerful centrifugal forces are created in the rotor which finally tear it apart; in fact the upper limit of speed is limited only by the strength of the material in the rotor. TOMMY LOUGHRAN Undefeated World Champion, Photo taken Feb., 1938 STOP Kidding the Undertaker When you jump out of bed in the morning, are you all pepped up and raring to go? Do you walk down the strect with a spring to your step and a feeling of real buoyancy to your whole body? If you don’t, you are only kidding the undertaker, You are half dead—but you don’t know it, WAKE UP AND LIVE Come on! Snap out of it! You were meant to be strong. Yes, your whole body was meant to be covered with muscles and bubbling over with vitality and power. Don’t tell me you’re different. Any man or boy that makes up his mind to have a powerful physique can get it. And that’s not all. . A NEW LIFE If you only knew the joys of a strong, virile body, you would not let another day pass without striving to attain it, It not only means broad shoulders and massive arms, It means a deep, full chest in- haling life-giving oxygen. This helps to purify your blood and shoots life and vitality throughout your whole system. It glves à sparkle to the eye and a clear thinking brain. It sends a tingle into every minute part of your body, You will fear nothing nor anybody, You will feel like shouting: ‘‘Come on—bring on those wild catsl'' CHOOSE YOUR TEACHER Don't leave as an important a task as this to just anyone, Don't think just any kind of muscle will do. ‘This is a scientific job and needs à capable instructor, J am not boasting when I claim I can turn the trick for you and do it right. A world champion should know what he is talking about, As a kid, J was a pitiful weakling, but I made up my mind to find out how this thing could be done. It cost me piles of money and many years of constant research, You can skip all thls, What I have learned I am now ready to pass on to you. Send for My FREE Book ‘‘Puissant Body Building’’ 'This contains numerous photos of the athletes and strong meu I have tralned, It will be an impetus and an inspiration to you. I don’t ask you to buy it, I want to spread the glad news, It is absolutely free, Yours to keep. Don’t delay, This does not obligate you in any way whatever, It is merely an inspirational talk and will show what I have done for so many others, ACT TO-DAY Do you wish these mighty musceles for yourself? Write at once and J will tell you how you can soon possess them. You will feel the thrill of a new life pulsing through your veins—you will shout to the world "I'm a man and I ean prove it." TOMMY LOUGHRAN 4 So. 15th Street, Philadelphia, Pa. FREE For the next thirty days I will send you with my free book, a beautiful reproduc- tion of my portralt, made by a famous artist. Only those who send for my booklet will have this autographed repro- duction, Dept. 55, TOMMY LOUGHRAN, Dept. 55 4 So. 15th Street, Philadelphia, Pa, Dear Tommy :—Please send that book ‘‘Puissant Body Bulldins.” I want a strong, active body like yours. Thls book is absolutely FREE with the understanding that I am not obligated in any way. Name .....2... es Qeoseesooossessaesuesebeteveveoeecececeves When Answering Advertisements Please Mention June Mechanix Illustrated 22

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Here’s the catalog that will make “photographic value” history. Never before have you been able to buy cameras, films, supplies at such tre- mendous savings. They’re all here— names like Kodak, Weston, Wirginex, Gewirette and many others. Send for your FREE copy. Use coupon TODAY. CAMERAS UMOLEGRLE RADIO SERVICE 5? NEW YORK, N: Y. e CHICAGO, ILL. ¢ ATLANTA. GA. 1OQ0 $:XTIH AVENUE 901 W. JACKSON BLVD. 265 PEACHTREE STREET BOSTON, ats e BRONX,N.Y. e NEWARK, N. J. e JAMAICA.tL. i. | 100 SIXTH AVE., NEW YORK, N. v. Г Ug RUSH FREE CATALOG NO. 71-2aF 8 Wem Lea Always some place to go—somethijng thrilling to do! Fun. excitement, new friends, fine pals! That's motorcycling—today'’s greatest outdoor sport. Get into it—NOW! See 1938 models at nearest Harley-Davidson dealer. Wrlte for FREE сору of motorcycling magazine, “The EN- THUSIAST." Harley-Davidson Motor Co., Dept. MM-638, Milwaukee, Wisconsin. ©) HARLEY-DAVIDSON MOTORCYCLES SPORTSMEN'S ANNUAL—1938 EDITION Order Your Gopy Now! 200 pictures At your newsstand, or order from FAWCETT PUBLICATIONS, INC. . Greenwich, Conn. 144 pages PRICE SOc Fawcett Bldg. For several years, Diesel engines have been replacing steam and gasoline engines in power plants, motor trucks and busses, locomotives, ships, tractors, dredges, pumps, etc. And now the first Diesel-powered passenger car is on M the market. Our home-study course offers you a real op- portunity to prepare for à worth-whlle position ір this new field. Write TODAY for full information, No obligation. American School, Dpt. DA 28, Drexel at 58th, Chicago LEJAY WELDER Now Only $1.00 $1.50 foreign Complete kit of parts for mak. Hing our genuine LeJay Welder A which has proved such a sensa- | tion. Thousands sold to satis- fied customers at $2.50 each. LeJay now offers this famous —. E tool in kit form at a saving of ncmpe = жа m= $1.50. Complete with welding, brazing rods and carbon tip. Easy to assembie—no other parts needed. Operates from car battery. Welds most metals. Your first repair job will more than pay the small amount you spend for this amazing tool. Send $1.00, plus 19¢ postage for wen, welder today, Satisfaction guaranteed or money refunded, es We also ship C. O. D. LEJAY MFG. CO, 1314 LeJay Bldg., Minneapolis, Minn. Gas Engine Drives Tiny Pump Easily carried by one man, this portable self- priming centrifugal 3-inch pump has an hourly capacity of 15,000 gallons with a guaranteed suction lift of 28 feet. It is built to handle muddy water with solids. This unusual pump weighs but 93 pounds, complete with a built-in air- cooled gasoline engine. A high-tension water- proof magneto shoots a hot spark and makes starting easy. The pump is sturdy and weather- proof and it will not overheat or freeze. The principal parts are made of a special abrasion- resistant aluminum alloy which weighs but 1% as much as cast iron. It is economical—1 gallon of gas pumps 35,000 gallons of water. It can be compactly stored in a contractor’s tool box or carried in an automobile. Its easy portability puts the pump on the job, pumps out the hole, and permits the men to start working before large pumps could be moved to the job and be set up, thus speeding construction. This pump will be found especially useful for pumping out cellars in areas troubled with spring floods, 30 Accept No Substitutes! Always Insist on the Advertised Brand!

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Preserved Brain Specimens Exhibited In Museum PORTIONS of actual human brains, so treated that they will remain in the same state of preservation indefinitely, have been placed on exhibition at the New York Museum of Science and Industry in Rockefeller Center in New York, N. Y., as the latest example of what the development of modern plastics means to scien- tific progress and resulting gain to modern life. There are six specimens in the collection on view at the Museum, two of them showing sections of the normal brain, two presenting different views of cerebral hemorrhage, one showing a condition of brain tumor and one a tumor of the pituitary gland. In appearance, they resemble slices of petrified wood, and while they would probably break if dropped or given a sharp blow, ordinary conditions of handling cannot harm them or affect their characteristics in any way. This remarkable state of preservation, brought about by soaking the brain in a solution containing a powdered resinoid substance, makes these specimens ideal for use in medical schools, research laboratories, and all other places where such tools of work are required. Recent experiments have demonstrated that other human organs can be treated in the same way with equal success. Wheels Test Road Material The popular belief that you never get anywhere going around in circles is being disproved at the Arlington testing laboratories of the U. S. Bureau of Public Roads, where two automobile wheels rotating on the surface of a small circular track are revealing the relative stabilities of various low-cost road surfaces. There are two of these apparatus, one indoors and the other out, with five or six sections of different bituminous mix- teres making up the surface over which the wheels rotate. Tests are made of one variable factor at a time, such as the quantity or the consistency of the bi- tuminous mixture, and are run until the relative wear on each section reveals the comparative sta- bilities which 1esult with regard to the several circumstances of the variable. The wheels, which exert a force of 80 pounds on the road surface, are mounted on the ends of a centrally pivoted steel beam which can be driven at three speeds, the maximum being 9 miles per hour. The track itself, laid in a concrete trough, is approximately 37 feet in circumference, 18 inches wide, and has a mean depth of 1215 inches. Dis- tribution of the "traffic" over the width of the surface during compaction is made possible by shifting the pivotal point of the steel beam back and forth by means of a hand-operated wheel. Here in CHICAGO án the famous COYNE TRAINING SHOPS YOU CAN FOR = TUITION AFTER GRADUATION You don’t need advanced education or previous experience. Don't let shortage of cash hold you back. Send coupon today for details of this offer. We will train you in the Coyne Shops and then give you over one year to pay your Tuition AFTER you graduate, EARN LIVING EXPENSES WHILE TRAINING _JOB HELP AFTER YOU GRADUATE You train on modem Motors, Generators, Dynamos and other electrical cquipment. Many do part time work to help earn living expenses, After you graduate my Employment Service gives you valuable Job help throughout your life. Training in DIESEL, Electric Refrigeration and Air Conditioning -NO EXTRA COST fm nea SEND SQUCON COR FULL PETAS umm eu, BH. C. Lewis, President, g COYNE ELECTRICAL & RADIO SCHOOL g°00 S. Paulina St., Dept. A8-53, Chicago, IM, «end me your Big Free Book. Give me all details regarding B “Pay After Graduation” Plan and training in Diesel, Electrical 8 Refrigeration and Air-Conditioning. ИМАМЕ; аеннан usd i PR ADDRESS aS Ya STATE imi mi vm un Gm о бн оа ба ве на ьа ьа Д —PARKS AIR COLLEGE PARKS AIRPORT . "EAST ST.LOUIS, ILL Offers YOU COLLEGE and PROFESSIONAL TRAINING Majoring in AVIATION FOUR courses lead to B.S, degrees in Professional Piloting, Aviation Operations, Maintenance Engineering, Aeronautical Engineering. TWELVE TRAINING PLANES are used in professional flight train- ing which prepares graduates for airline Alght operations, 71% of graduates enter air transportation in North and South America. 64,000 hours flight training given, 650 hours being flown monthly. FACULTY of 33 specialists in various fields of aviation. 1477 graduates, Capacity enrollment of 302 for Fall term. 100-acre airport, 14 buildings devoted to school purposes exclusively. Dormitories and dining hall on the Field, Accredited by the Illinois Superintendent of Public Instruction. Government approved as a Transport Ground and Flying Sehool and Mechanles’ School, Open to high school graduates, Fall Term September 26th, Send postcard for new GO0-page catalog. Registrar, Dept. MM-6 11thYEAR PARKS AIR COLLEGE, East St. Louis, I. Pays up to $2 or $3 an Hour in Spare Time—No experience needed A FOLEY Automatic Saw Filer files hand, circu- lar and band saws better than the hest hand filer. Cash business, no canvassing, no eye- strain. Louis P. Wadowick, Ohio, says, *'I have filled 764 saws in spare time and have earned $350.00 in carpenter work due dlrectiy to my saw filing contracts." Send coupon for FREE PLAN, no obligation. FOLEY MFG. С0., minneasotisy mnn: Minneapolis, Minn, Send Free Plan on Saw Filing business. Name ...-- = Address When Answering Advertisements Please Mention June Mechantx Illustrated 31

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Righ School| Ur е е Т Many Finish in 2 Years Go as rapidly as your time and abilities permit. Equivalent to resident school work—prepares for entrance to college, Standard H. S. texts supplied. Diploma awarded. Credit for H. S. subjects already completed. Single subjects if desired. Bulletin on request. Specialized training is absolutely essential to Success today. Over 150 noted Educators, Engineers and Business Men helped prepare our ape- clal instruction material, used by C О u rs е S avy and Province of Mani- toba, Can. Train at home for best-paying lines as listed below. No Interference with present earn- inge while preparing for better Job. American School, Chicago рэпу ендеп афо and colleges, Mail Coupor far information—No Obligation American School, Dept, HA 28, Drexel at 58th, Chicago "Tell me how to train for pecas In line checked. High School Course in 2 Years Air Conditioning poni Electrical Refrigeration Architecture and Building Highway Engineering Automotive Engineering Liberal Arts (College) Aviation Mechanical Engineering Business Management Private Secretary Civil Engineering Professional Accounting Complete Law incl. C. P. A. Coaching Diesel Engineering Radio and Television Drafting and Design. n Satesmanship Electrical Engineering Steam Engineering Name... Address HAVE YOU SOME SPARE ROOM a basement or gavage where you can do light work? We can offer you a profitable proposition, casting 5 & 10¢ novelties, ashtrays, toy autos, etc. as Manufacturer for firm of many years standing. No experlence necessary as we furnish full Instructions with moulds. If interested in devoting spare or full time to profitable work write AT ONCE stating age and space available as we are now closing anrüngements for 1938 supply of our goods, METAL CAST PRODUCTS CO. Dent. 2, 1696 Boston Road, New York, N. Y. TAN at HOME Splendid opportunities. Prepare quickly in spare time. Easy method. No revious experience necessary, common school education su nt. any earn while learning. Send for free booklet ‘Opportunities in Modern Photography", particulars and requirements. ..,. AMERICAN SCHOOL OF PHOTOGRAPMY | T 3601 Michigan Avenue Dept. 205A Chicago, Ilinois New Catalog of TRAILER PARTS New calalog of trailer parts at bargain prices, Axles, stralght, $4. Drop center axle, $7.50. Drop cente: le undercarriage, $19.50, complete less tires, Cable-controlled brakes on asle, $15 extra, Electric brakes—prices on request. Send for FREE Catalog today, Shamroch Trailer Parts, 12319 Turner, Detroit, Mich FOLLOW THIS MAN Secret Service Operator No. 38 ia on tbe job | | Running down dangerous Counterfeit Gang. Tell- F | tale finger prints in murdered girl’s room. The Confidential Report ree Operator No. $8 made to hie chief, Write for $t. Earn a Regular Monthty Salary YOU can become a Finger PrintExpertat hame, in your spere time, at small cost. Write for con- fidentlal full report and detalle. Literature will be sent only te persons staing their age. INSTITUTE OF APPLIED SCIENCE 1920 Sunnyside Ave. Dept. A-235 Chicago, lll. 32 Radio Filter Helps Pilots Get Weather, Range Signals A new radio filtering device which permits air- plane pilots to receive either, or both, radio range signals or weather reports has been developed by the Western Electric Company. A three-position switch permits reception of both radio range beacon signals and weather re- ports. Turn the switch one way and only the beacon signals come through. Turn it the other and only the weather reports are received. Purpose of the device is to permit pilots to hear either beacon or weather which are now, under new regulation, both broadcast simultaneously. This twin broadcasting is an improvement on the old method which made it necessary to shut down beacon signal transmission when weather reports were given. Justified complaints were received from pilots trying to follow beacons in bad weather when the beacons were turned on, even for only short in- tervals, It did these pilots little good to be told that it was foggy right down to the ground, when they were flying blind already. What they wanted, and have received by the new system, is con- tinuous operation of the beacons at all times. Selective reception of the twin radio airline signals is accomplished in the new instrument by blocking out a narrow band of frequencies from the much broader band that carries the human voice. This narrow band carries the dots and dashes of the range beacons. Removal of the narrow beacon frequencies from the voice transmission distorts the signals slightly from normal but does not interfere with intelli- gibility of the speech. The elimination of the voice on the beacon signals is said to improve their reception greatly since the noise-to-signal sound level is markedly decreased and the signal is better received. Spectroscope Helps Experts Build Better Guns Uncle Sam is using the keen eye of the spectro- scope, science’s powerful research tool, to make sure he gets the best grade steel for his guns, according to Major J. L. Guion, who, in an address at Massachusetts Institute of Technology, at Cam- bridge, Mass., explained how the instrument has replaced chemical analyses in the Army’s efforts to detect impurities. Particularly, the spectroscope has been used to test steel for molybdenum and vanadium, metals often found associated with steel. The best steel for guns or armor-plate has from four to six parts in 1,000 of molybdenum and one or two parts in 1,000 of vanadium. More than this, or even less, makes the metal brittle and liable to crack under pressure of repeated explosions. Accept No Substitutes! Always Insist on the Advertised Brand!

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Hospital Has “Blood Bank” dd 7 .A hospital in Los Angeles, California, is equipped with a specially designed refrigerator which serves as a “blood bank,” storing quantities of human blood for later use in cases requiring blood transfusions. The "blood bank" is expected to save more than $10,000 annually and eliminate delays in operations. The refrigerator is kept at a temperature of four degrees above freezing, an alarm being automatically sounded when the temperature varies. The blood is kept on hand not longer than two weeks, a fresh supply being secured at regular intervals. New Type Electromagnet Built Like Jelly Roll An electromagnet, believed new in construction principles, is reported by Harvey Allison of Bridgeport, Conn. Known as the “roll” magnet it consists only of iron or steel and insulating varnish. To make one you use the technique of the housewife for making a jelly roll. Remember, she cuts the dough in a long strip and rolls it up into a cylinder. Mr. Allison’s invention has iron “dough” and insulation for the “jelly.” Mr. Allison makes his roll magnet out of a strip of thin sheet steel, four inches wide, four one-thousandths of an inch thick and fifty feet long. He simply rolls the strip compactly and putting electrical connections at each end, passes current through it. A brand new Evinrude . . . amazingly light, handy and powerful. eighs only 16 lbs., and cruises 3 hours on a single fill! Literally backed with big-value features including famed Hooded Power — Evinrude Co-Pilot — Underwater Silenc- ing. Starts instantly! | — spins into action with a flick of the starting cord. Costs ? less than 3¢ an hour to operate. Send for catalog! ELTO PAL only $37.50 Elto PAL (built by Erin- rude) weighs only 14 pounds, and drives boats at twice the speed of | oars. Elto ACE, $47.50 A — the husky Handi- twin, only $07.50. Rach an outstanding valuel Address EVINRUDE MOTORS, 5484 N, 21th St. Milwaukee Prices F. O. B. Factory FREE \ — Catalogo! \ «S Write for Аа 1998 Evinrude \\ 3 and Elto cata- logs... Boat Directory and Boat-and-Mo- tor Selector. CARRY EXTRA PERSON OR 250-LB. LOAD IN y Real sensatlon! i) familly roadster! —great for trips, pic- New 2-passenger or nies—only Vee А, comfortable! c 7 deliveries—increasing store delivery per mile to operate— Also widely used for business 5 to 8 times!—redueing costs Heavy steel trunk, re- movable cover, lock. Slde-kar unlt Am s on or off in 5 min. Fowerrul 1м or 49: 23 H.PP engine, 2-Spee Tansmissio Aree i8 t0 1 fatio In low), Clutch, Brake, A Balloon Tires. Windshleld avail- AM ^ able. Other models. Ww R і T E for photos, complete de- tails and the very Low Price, Send postcard or letter today. THE CUSHMAN MOTOR WORKS, Dept. T-6, Lincoln, Nebr. DEALERS Get Special Cffer. 4519.38 0 = IN GAS” ON TRIP SAN FRANCISCO TO CHICAGO Saya J. Smead: Auto owners of every make write us our Amazing Improved Auto GAS ECONOMIZER helps them to get more miles Get Big Money рег wallon of gasoline and SAVE up-keep | Making Plan costs, Self-regulating—anyone can attach. offer of no-cost GAS ECONOMIZER SENT ON TRIAL | 10:0: 20-002: For 30 DAYS—Costa nothing if it does not save 2 gas, save running expense. SEND name and ше: pe DUM address and make of car—a lc postcard will do. your locallty, 1. A. STRANSKY MFG. CO., G-600,, Pukwana, So. Dakota When Answering Advertisements Please Mention June Mechanix Illustrated 33

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Islands Float on Florida Lake Nic Sprank Offers $5.00 For Best Oddity [8: одтімо ISLANDS! ON ORANGE LAKE IN FLORIDA CAN BE SEEN THE FAMOUS “FLOATING ISLANDS? EACH OF WHICH VARY IN SIZE FROM A FEW SQUARE FEET TO SEVERAL ACRES. TREES MEASURING UP TO TWENTY-FIVE FEET IN HEIGHT GROW ON THESE FREAKS OF NATURE. 4 WPetterson,JSacksouville Beach, Fla. = Non- RUSTING IRON!— A CHEMIST POINTS OUT THAT THE FAMOUS IRON PILLAR OF DELHI, INDIA, HAS LASTED 1600 YEARS WITH ALMOST NO RUSTING BECAUSE ITISINADRY CLIMATE, AND NOT BECAUSE OF SOME MYSTERIOUS LOST ART OF HANDLI NG METAL — BEHE WORLD'S COLDEST SPOT/-NOT AT THE NORTH OR SOUTH POLES,BUT AT TUE E m S EQUATOR IS THE WORLDS COLD: E Bi S: * | EST SPOLTEMPERATURES AS о АѕѕЕ5 Е ROADS E: STATE OF MYSORE, INDIA, И КАЛ КСЫ ао Б Е DUST.— SA Spicer Owen Sound Ont, Carade. bob becker, SaltLake Cy, tak Five dollars will be paid for the oddity selected by Nic Sprank as the best of the month. One dollar will be paid for all others used on this page. Send your oddity to Nic Sprank, Editorial Office, MECHANIX ILLUSTRATED, 1501 Broadway, New York, N. Y. Source or proof of each oddity must be given. Send "all oddities separately, not with other manuscripts or letters. 34

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"Men who made civilization what it is today were not famous statesmen. conquerors or philosophers. They were—and are—men engaged in the mechanical sciences.” BY LOWELL THOMAS Vol. XX June No. 2 1938 W. H. FAWCETT Publisher VER the airwaves comes a desperate appeal to the radio station at Nome. "For God's sake, send help, if you can. We're starving and dying. "There's an epidemie. Almost everybody is flat in bed." "What do you need? Food?" “Food, yes, and milk. But above all, serum. This whole settlement will be wiped out if we don’t get serusd." By dog-sled and man-power it would take two weeks and a lot of luck to carry the needed supplies to that stricken community. But there is Joe Crosson with his plane. Can he make it? The problem is put up to him. “We'll do our durndest,” he re- ' plies, speaking for himself and plane. We won't go in to the trouble and danger he goes through. For one thing, it's an old story to Joe Crosson. He has done it before probably will have to do it again several times. The point at this moment is that he does it. An en- tire settlement in the frozen North is saved from extinction. Such an episode, not uncommon in these days, serves here to The great debt which the modern world owes to the man in the laboratory and the man in the workshop is brilliantly discussed in this article by Lowell Thomas, internationally famous radio commentator and author, below.

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dramatize the crescendo advance of civiliza- tion. I believe everybody agrees that one of the two highest functions of this civilization of ours is to diminish disease. A generation ago the saving of that Arctic settlement would have been impossible. To whom did those stricken people owe their lives? All honor to Crosson. He did his errand of mercy with courage, fortitude and skill. But without the work that a num- ber of men did before him, some in factory and machine shop, some in chemical labora- tory, some in astronomical observatory, all of Joe’s courage and fortitude would have been unavailing and there would have been no call for his skill. No call for help could have been flashed through the air if the physicist Hertz had not discovered the uncanny properties of the waves named after him and if Marconi— who was not educated. as a physicist to begin with—had not, later on, developed the means of using those waves and thus made it pos- sible for us to.communicate from anywhere to anywhere else witbout the aid of wires. Crosson could never have flown to the rescue of that settlement but for the experiments of a couple of bicycle mechanics named Wright in Dayton, Ohio. Going back a bit, Wilbur Сгкоззоп (аБоуе) f hves, and th LK X; 5 h:made possible by th xperiments of the Wright = one of whose early pl. з. ‘Clipper picture abo. and Orville Wright never could have made their strange machine fly if Gottlieb Daimler had not produced the gasoline engine." And Joe could not have navigated his airship but for the contributions of Copernicus, Galileo and Kepler, the great trio who may safely be called the fathers of modern astronomy. Finally, would he have had any serum to stop that epidemic if Edward Jenner had not in- troduced vaccination and thus become the originator of serumtherapy? : From all this, it seems to me, one fact emerges clear. The men who have made civilization what it is were not the famous statesmen, conquerors or even the philoso- phers. They were—and are—the men en- gaged in the mechanical sciences. Do you object that I have included a physician ‘amongst them? Then I refer you to Arthur Keith’s “The Engines of the Human Body” or Dr. Crile’s brilliant work on “Man as an Adaptive Mechanism.” Or watch a skillful surgeon at work. You will see that he is ac- tually a super-mechanic plus, of course, a complete knowledge of the human anatomy. Again, it is generally conceded that William Harvey was the father of modern medicine. Consider his great discovery, the circulation

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of thé blood. It was the first true explanation of the mechanies of the life-stream. Upon it has de- pended every advanee that we have made in the prevention and cure of disease. The fact that I have stated above will not go undisputed. The highbrows will say: “To the pillory with him! He blas- phemes the memory of the great: philosophers.” Whereupon it occurs to me that I have heard scholars remark that, actually, philosophy has not advanced a single step in any im- portant direction. There have been different sys- tems of philosophy, true, but admittedly none greater than that of the ancient Greeks. And, frankly, I am one of those who are convinced that neither Schopenhauer nor Kant nor Spinoza nor Deseartes nor even Papa Plato himself has con- tributed one jot or tittle towards the saving of a single human life, the curing of a sick child, the alleviation of poverty. And what of the great conquerors? I can think of only one or two whose achievements had any lasting and beneficent Benjamin Franklin (above) — first tempted a spark from the skies; today De- Robert J. Van de Graaf, of the Massachusetts Institute of Technol ORY, creates 7,000,000 volts of arti ficial Bghting with the man-made ap- parstns shown st feft.

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effect. Alexander spread the culture of Eu- rope, such as it was, through Asia and brought back some of Asia’s lore to Europe. But his work, like that of even Julius and Augustus Caesar, has left but few traces. “That which is done violently always has to be done over again.” Caesar, Hannibal, Ham- mureahi, Genghis Khan, Charlemagne, Na- poleon Bonaparte—you can have the whole lot of them, for what do we owe them? I recall a line in “Man and Superman” by Shaw: “Commander, when the soldier ap- proaches, Mankind hides away his women and buries his forks and spoons.” | Statesmen? Most of them have been para- sites on the soldier’s back. The best that can be said about them is that the more intelli- gent have protected and encouraged the experts in the mechanical sciences. But usually the scientists had to obtain this pro- tection by dint of their capacity for destroy- ing human life, not saving it. Archimedes, discoverer of the lever and the greatest of Greek scientists, was employed by the Tyrant of Syracuse because he invented artillery en- gines. Leonardo da Vinci, one of the greatest minds of all time, sought the favor of princes not because he was the foremost of Italian artists, a poet and mechanical genius but because he was a brilliant military engineer! As this is being written I can think of just two statesmen who contributed something imperishable towards civilization. And in [Continued on page 134]

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Cooking Pot Has Clamping Lid NEWLY developed aluminum cooking pot features a clamping lid which can be instantly re- leased by pressing down on a special trigger. An ad- justable air vent in the lid takes care of the pressure created within the pot while cooking. Two-Way Wrench Opens Tight Jars HE annoying matter of attempting to pry the cover of a jar loose by pry- ing it with a knife or placing the jar in hot water is said to be eliminated through the use of a recently pat- ented two-way jar wrench. The device, which is made of stainless steel, features a series of various sized rings designed to fit the caps found on the majority of jars in which fruits, jellies, etc, are packed. The wrench is easy to use, the proper ring merely being slipped around the jar top and the two sides of the wrench handle then pressed together while an anti- clockwise motion is applied. It is only the work of a mo- ment to select the proper ring for the jar at hand. Transparent Oil Cans Developed EIGHING one-third less than metal types and unaffected by oils, gaso- line or their derivatives, oil cans made of transparent plastic material eliminate the usual messy preliminary quirt to see if they are filled. The transparent cans are fitted with metal spouts.

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Above-—When the curtain rises at Radio City Music Hall in New York, N. Y., the audience sees a completed and colorful setting, but few of the theater's 150,000 weekly patrons realize the planning and work involved in making the sets. In the model room (above), Nat Kar- son, art director of the Music Hall, looks over minia- tures of settings used іп previous productions. A model of every set is carefully stored. At the left, Art Director Karson is shown making a watercolor sketch that will serve as a guide for the thea- ter technicians who fashion the huge settings for the Music Halil stage from canvas, wood, steel and paint. Every set planned for the Music Hall’s mammoth stage is first worked out in detail on a miniature stage (above), which has three elevators and a turntable, enabling all technical problems to be solved at small expense before costly full-size sets are constructed. UST as important a task as getting the per- formers ready for one of the gay spectacles presented on the mammoth 144x80-foot stage of the famous Radio City Music Hall in New York, N. Y., is the enormous mechanical and artistic job of creating the settings which transform the bare : stage into a wonderland of illusion. Every set planned for the huge stage is first worked out in miniature on a tiny stage which, like its prototype, is equipped with three elevators and a turntable so that the settings can be moved about just as on the real stage. The miniature sets are constructed from cardboards, celluloid, glue and pins, enabling all scenic effects to be carefully studied and changed before engaging in building of costly full-sized sets.

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Device Measures Heat Of Skin CIENTISTS at the Uni- versity of Illinois have devised an apparatus that measures changes in skin temperature caused by changing air conditions. The patient’s feet are encased in boxes and a stream of cold air directed upon them while an electrical reading of skin temperature is taken. Electric Polisher Runs Dual Blocks MPLOYING two rub- bing blocks simultane- ously, a newly developed machine which sands, rubs and polishes can be plugged into any convenient electric current outlet. The dual block arrangement makes it especially useful for curved surfaces and inside corner work. The blocks are de- tachable and interchangea- ble and the machine is fur- nished with one set each of sponge rubber and felt blocks. 'The complete unit weighs only ten pounds and is easily handled. Fire Piping Has Remote Control IRE protection piping is prevented from freezing or leaking by a new type of valve, which is of the re- mote control type and can be located some distance from the piping, where it is warm. No water is kept in the exposed section of pip- ing but it is available within a few seconds after the control is pressed.

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BLAST FURNACE

The diagram shows a cross-section of a modern blast furnace. The coke, limestone and ore are dumped in at the top. The molten iron and slag col- lect at bottom of furnace where they are drawn off at regular intervals. “—~DAMPER => CHIMNEY

PROCESS OF REDUCTION CHECKERS TO HEAT AIR PROCESS OF HEAT ABSORPTION

PROCESS OF FUSION < PROCE SS EOF em COMBUSTION IRON LADLE

HOIST ENGINE COLD AIR І y^ FROM BLOWER i E CUT Eesti SY а сгоз8-весїоп _ оў са Беззешег сопуепег. б consists’ of «a. huge péar-shaped steel pot, lined with. beat-resist- ‘ing brick, ~ In use, the converter is. tilted on: its: side and: filled. . with molten. iron,. Carbon and manganese are added: to: make ` {Һе steel. hard and elastic: When the converter is Beaute! IO upright position, air is forced | EUIS TE e LU ML TS tom.- After the fiery liquid. 1s *'" boiled for about twenty. minutes, - pure" tton. and manganese are added. Another boiling period — and the white. hot steel is poured ~ off ERI а саа Тае." BOTTOM FULL OF HOLES LIKE THIS. INRUSH OF AIR HOLDS UP THE METAL = (васи: — T Open Н furnaces : today produce 91 per cent of MEO ru um vnu бїа{ев. EE тишин сысы eM olten гой ап о{һег їта(етаїз _ ^ are placed on the clay and brick A B ES SEMER | : ‘af S lined hearth: Hot air and gas Р ~ CONVERTER 1 TEN from a nearby. oven blow over = И =. i Meee фер. The molten steel is — * е = г : i - . drawn off from. furnace: bottom. - i

OPEN HEARTH FURNACE

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—Photos Courtesy Republic Steel Corporation WORLD without steel—try to imagine it! Without steel, the whole physical struc- ture of the modern world would collapse. Lacking this one all-important substance, the civilization we know would cease to exist. There was, of course, civilization long before the discovery of steel, but it was vastly dif- ferent from ours; so different that it requires an effort of the will to picture a world without steel. Without steel— There would be no buildings higher than walk-up distance; no airplanes, no automo- biles, no modern railways or fast steamships. by Robert W. Gordon A silhouette of a large steel mill. Bessemer converters emit tongues of fire which can be seen for miles at night. The color gradually changes from red to a yellowish white. Lefr—Blast furnaces and ore docks at Cleveland, O. he blast furnaces are at the left and right. The round struc- tures between are stoves which heat the air for the blast. Without steel— Foodstuffs would be largely limited to what could be grown locally, and the threat of famine would be ever present. The horse and the sail would still be the principal means of transportation. Without steel— There would be no modern factories, in- dustry, cutting tools, or power machines. Countless features of the twentieth century world would be non-existant. The United States would be back in the era of the horse and buggy. The changes wrought by steel have been 43

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Looking up toward the top of a blast furnace. The first step in the production of steel is the changing of the ore into molten iron. À modern blast furnace produces G00 tons а day. Right —— Stainless steel being polished. This is but one of the 500 differ- ent iron and steel products available today. Chro- mium added to steel pre- vents it frota corroding. so vast and staggering that it is difficult to realize that the Steel Age is comparatively young. As recently as 1880, it was still gain- ing momentum. It wasn’t in full swing until 1900, and its peak is not yet in sight. Iron and steel were known before the Steel Age began. The first iron on record was placed in an Egyptian pyramid more than 5,000 years ago. The Romans used a lot of it, but with their methods of production a ton of raw iron would cost $1,000. Today the average price of finished steel is only $55 a ton. A medieval furnace could produce 100 to 150 tons of iron a year. A modern blast furnace produces 600 tons a day. A hundred. years ago a blast furnace con- 44 A close-up view of a Bessemer converter in use at night. In 1890, nearly 90 per cent of all steel was produced by this method. Charcoal was sisted of a stack and a blower. the only fuel, and the bog ore was hand se- lected. The chief customers for the 25 or 30 tons produced a week were the nearby blacksmiths, who hammered out ferrous products by hand. In those days the principal metals were cast and wrought iron. Cast iron was hard but brittle. Wrought iron resisted shock but was soft. Steel was needed, for steel is strong, wear-resisting, and tough. There was blister steel and crucible steel, but the methods of making them were slow and costly, and totally incapable of producing the metal in quantity. Blister steel was produced by placing char- coal and wrought iron into clay boxes or

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jars, and heating for days, until the iron had absorbed enough carbon to become steel. Crucible steel was melted in a pot, along with carbon. The method gave us the famous Sheffield steels, excellent but rare and costly. Ninety years ago Henry Bessemer of En- gland and William Kelly of Kentucky, work- ing independently, conceived the idea of refining iron by blowing air through it. Bessemer patented the process in 1855, but Kelly erected the first commercial converter two years later. The two interests merged in 1866, and became generally known as the Bessemer process. A Bessemer converter is a huge, pear- shaped vessel made of steel plates and lined with heat-resisting brick. It is open at the top and mounted on hollow trunnions so it may be tilted. The base is perforated, so that ELECTRIC FURNACE Stainless and heat resisting steel, and other high quality alloys are made in electric furnaces. These furnaces can produce and control accu- rately heat up to 3,800 de- grees. Left—Charging a modern electric furnace. air blown through the trunnions passes through these holes to bubble through the metal. In operation the converter is tilted on its side and filled with from 10 to 25 tons of molten pig iron. The rush of air, turned on as the converter is returned to a vertical po- sition, prevents the metal from running through the holes. As the blast is turned on a brilliant shower of sparks bursts from the mouth of the con- verter, to be followed at once by short, ruddy flames, and a cloud of reddish fumes as the silicon and manganese combine with the oxygen and burn. The ruddy flames gradually change to a yellowish white tongue of fire as the carbon in the iron burns; and for about ten minutes the sky is lighted up for miles, while the con- Left—Small objects of jewelry made of stainless steel—An interesting Right—A modern kitchen using stainless steel. modern development. See ELECTRODES.

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A, spectacular sighte—tapping an open hearth furnace. An average heat is 90 tons and requires from ten to fourteen hours to make, depending upon the type of steel wanted. verter emits a deep roar from the boiling mass of metal. Suddenly the flame drops, and the con- verter is tilted again before the iron can burn. Ferro-manganese is added to the molten mass to absorb the gases and kill the boiling action. This ferro-alloy furnishes the metal with the desired proportions of carbon, sul- phur, manganese, phosphorous and silicon, turning it into steel. When the alloy has had time to do its work, the converter is tilted still further, and the molten mass is poured into a giant ladle from which it is teemed into ingot molds. It was this Bessemer process of refining steel cheaply and in large amounts that intro- duced the Steel Age. In 1890 nearly 90 per- cent of all steel was produced by this process. Today open hearth furnaces produce 91 per- cent, with Bessemer a poor second at seven percent. | Bessemer steel, however, has certain defi- nite advantages. Its high sulphur content makes it ideal for machining, for it cuts clean. It can be drawn into stiffer wire, and to finer sizes. It also makes the best welded pipe. Its low standing today is due to the demands for “tailor-made” metal, the manufacture of 46 which can be controlled better in open hearth and electric furnaces. The coming of the Bessemer process co- incided with the fever of railroad building, and greatly accelerated it. Railroads paid $80 a ton for inferior iron rails in 1867, and could secure only 460,000 tons. They paid but $32 a ton for 1,500,000 tons of steel rails: in 1884, the peak of railroad building. With the growing demand for steel, it be- came necessary to produce raw iron in enor- mous quantities. Blast furnaces increased in size, until now one can turn out 600 tons of iron a day. A blast furnace is an enormous steel shell, lined with heat-resisting brick, and often 100 feet high, Alternate layers of iron ore, coke and limestone are fed in at the top, while a blast of superheated air is blown in from the bottom. The coke burns in the hot oxygen, and the whole mass settles, the iron forming a molten pool in the bottom. The limestone also melts, absorbing the coke residue and earthy matter in the ore, and forming a molten slag that floats on the iron. The slag and iron are tapped several times a day, while the charge of raw materials is constantly re- newed at the top of the furnace. A furnace

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will operate continuously, until shut down for repairs, or because there is no longer a demand for its product. The tapped metal is cast into molds called pigs, unless it is to be used on the spot in the manufac- ture of steel, in which case it is taken in a ladle to a huge vat called a mixer, where it is kept in a molten state until needed. The open hearth furnace was originally designed in 1864 to pro- duce steel without infringing on the Bessemer patents. It was 20 years later before this type of fur- nace was operating on a commer- cial basis. An open hearth furnace is a huge oven in which the hearth or floor is exposed to the sweep of the flames which melt the metal. The fuel, which may be gas, oil, tar or powdered coal, is blown in at one side of the furnace, along with heated air, through a checkerwork chamber of brick. The smoke and combustion gases pass off at the other side through a similar checker chamber. Every fifteen minutes or so the flow is reversed, so that the incoming fuel and air pass through a heated chamber. This reversal of flow conserves heat, and makes pos- sible temperatures that could not otherwise be obtained without an enormous consumption of fuel. The open hearth may be charged ' [Continued on page 149] A wire fence making machine in operation. Wire fencing is but one of tbe countless products the modern steel industry. made possible by When the bloom is made into bars it passes through sets of rolls several times. depending om the size and shape desired. Sach time its cross section is reduced and its length increased. Lefte-Seamless steel is fested Бу waren u high pressuce. (his is bu one of the many steps Pecessary for сорт qe consumers with pre day high quality materials

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New Transport Plane Boasts Increased Flight Safety ROCLAIMED by its designer, Wally Timm, of Los Angeles, Calif, as having more safety features than any airplane built, a new twin-engined transport is equipped with a tricycle landing gear, wing slots de- signed to prevent tailspins and wing flaps that are said to reduce the landing speed con- siderably. The new plane is a high-wing, semi-cantilever monoplane and is powered by two 425 horsepower engines. Old Coin Weighs 44 Pounds N UNUSUAL copper coin which was re- cently placed on exhibition in Stockholm, Sweden, is 25x12 inches in size and weighs about 44 pounds. Dated 1664, the coin’s origi- nal value approximated 150 U. S. dollars. Novel Skate Has Ball "Wheels" TTACHED to the sole and heel of a shoe by means of small clamps, a newly developed German skate rides on three one and one-half-inch ball bearings protruding from cylindri- ea] supports instead of the customary wheels.

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This igloo roadside stand helps to create an atmos- phere almost as cooling as the ice cream sold inside.

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SEVERSKY *SUPER-CLIPPER” TOTAL H.P: ESTIMATED CRUISING SPEED: 250 M. P.H. PASSENGERS; 100-120 SPAN:250FT © HERMETICALLY SEALED CABINS FOR CRUISING AT HIGH ALTITUDES BOEING "STRATOLINER* TOTAL H.P. (4 MOTOR): CRUISING SPEED(EST):200M.P.H. . PASSENGERS: 33 DAY-25 NIGHT SPAN: (O7FT, Shown below is Col . Alexander P. de Sever- sky with a scale model of his proposed 120- passenger transoceanic twin-hulled flying boat. THESE 4 GIANTS OF THE AIR ARE DRAWN TO APPROXI- MATELY THE SAME SCALE 16000 | M "LANDING" FLOATS RETRACTED “DURING FLIGHT TO COMPLETE Se, STREAMLINE SHAPE OF FUSELAGE ү The comparative sizes of і the proposed Seversky sea- plane (250-foot span) and other airliners now under construction, as well as a present day transport plane, are graphically shown in the artist's sketches on this page. NEW DOUGLAS DC-4 —3= TOTAL H#L4MOTOR): 5,500 CRUISING SPEED: 2IO MPH. ~ PASSENGERS: 42-CREW: 5 LANDING GEAR EXTENDED TO — SHOW TRICYCLE ARRANGEMENT 4,400 TYPICAL TRANS-CONTINENTAL AIRLINER IN SERVICE, TODAY. DOUGLAS DC-3 and DST MAXIMUM H.P, (2-MOTOR)? 2,000 CRUISING SPEED: 190- 200 M.P.H. PASSENGERS: 24DAY-16 NIGHT SPAN: 9SFT. LARGE 3 BLADED TRACTOR AIRSCREWS EACH DRIVEN BY TWO 2,000 H.P. ENGINES э LANS for a super-clipper seaplane capable of carrying 120 passengers at 250 m.p.h. for about 5,000 miles non-stop have been submitted to Pan American Airways by the Seversky Air- craft Corporation. The proposed air giant, with its wingspan of 250 feet, would dwarf the huge | Boeing Stratoliner and Douglas DC-4 transport planes which are already under construction. (See accompanying sketches.) Mechanix Illustrated—~June, 1938

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The novel chart at the right provides a visual comparison of the power and pay load capacity of the projected and present day airliners. The Seversky plane, a giant among giants, will be capable of flying from New York to London in 14 hours.

Qoumuomour

| EACH COMPLETE | | SYMBOL EQUALS | | 2.000 HORSEPOWER |

NEW GIANTS OF THE

panes tip ee EACH COMPLETE SYMBOL EQUALS | 5.000LBS USEFUL | ; LOAD(PASSENGERS | | AND BAGGAGE). | —— DOUGLAS || BOEING || DOUGLAS SEVERSKY /} TYPE DST | TRATOLNER| TYPE DG4 || SUPER-CLIPPER</ eee d

POWER & PAY LOAD CAPACITY OF PROJECTED AIRLINERS COMPARED WITH TYPE NOW IN USE -

AFT STARBOARD DINING SALOON AND AFT ENGINE й ENGINE HOUSING PROMENADE LOCATED COMPARTM'T 2 | ON EITHER SIDE MS 22 ` i RELATIVE SIZE j = à OF FOURPLACE jf STATEROOMS . dou FLOAT SEAPLANE

CONTROL BRIDGE OF NACELLE AND OFFICERS! QUARTERS GALLEY | Í COCKTAIL LOUNGE | | ANDOBSERVATION i. 4 CABIN 28

Ў STARBOARD FUSELAGE | ~ ARRANGED SAME AS PORT SIDE 4-BLADED PUSHER AFT FUSELAGE AIRSCREW DRIVEN STATEROOMS BY TWO 2,000H.P. j | = GEARED ENGINES 4 LEP

=, LANDING

~-CREW'S QUARTERS —-7 WASH ROOMS dibus BETWEEN CABINS AFT PORT ENGINE ————— DRIVES 3- BLADED PUSHER AIRSCREW 5 CARGO SPACE IN BOTH PONTOONS

WING STATEROOMS FWD. FUSELAGE STATEROOMS

"y do PORT FWD. ENGINE 7 COMPARTMENT The elaborate interior and constructional fea- tures of the proposed Seversky super-clipper are sketched above. The hulls are retractable. formerly Modern Mechanix

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Creates Novel Job To Pay Schooling UTTING his high school biology studies to practical use, 18-year-old Sam Saikin, of Chicago, Ill., has created a grow- ing business which, he hopes, will finance his college educa- tion. The business consists of supplying biological laboratories throughout the country with preserved parasitic growths and pig embryos which he obtains from local stock yards. Starts Sea Voyage In 18-Foot Ketch TOCKING a rugged 18-foot ketch with food and marine gear, Al Lastinger, of Lakeland, Florida, recently set sail for Italy. Along with his passport and clearance papers, the 26-year- old sailor carried a letter from Governor Cone, of Florida, to Premier Mussolini, inviting the : Italian dictator to enter an ex- hibit in the De Soto Exposition being held in" Tampa. Lastinger is making the trip entirely un- aided, the rigging and steering gear of his small craft being ar- ranged to permit efficient one- man handling. Car Features Two Types Of Engines ESIGNED especially for high speed travel, a newly developed German automobile features two engines. One, a 150 horsepower airplane en- gine, is mounted externally at the rear of the car and drives an airplane propeller when the car is out in open country. The other motor is an ordinary auto type, housed under the front hood, which is used when the car is passing through towns.

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Constructs Printing Press From Old Clothes Wringer XHIBITED at a science fair held in Boston, Mass., a novel printing press built from an old clothes wringer by Frank Jawroski, 18, created considerable interest among the spectators. "Iron Mother" Unit Saves Babies UTOMATICALLY produc- ing the precise conditions of humidity, temperature and air circulation as determined desirable for each individual infant, a new type of incubator is said to be invaluable in sav- ing the lives of premature babies. The incubator con- sists of a portable metal cabinet which houses a crib, water reservoir, air purifier, ete. Surgical Mask Made From Transparent Material NVENTED by a well known doctor, a new type of surgical mask is con- structed from transparent material and, due to its flexible metal frame, can be in- stantly adjusted to fit the contour of the face. By permitting lip reading, the trans- parent mask enables doctors and nurses to converse more conveniently during an operation. An opening in the bottom of the mask permits air to circulate. ali ol

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BUILT TO WIN Fred Offenhauser is the man who answers the speedway demons’ prayers for engines that “can take it.” by R. De Witt Miller “ ODS of Roaring Road, give me a motor that will stand up! TIl do the rest.” Every Memorial Day at Indianapolis thirty- two men mutter that prayer, pull down their goggles, adjust their crash helmets, and think ahead of the 500 terrific miles between them and the checkered flag. Out of that ever greater need for motors that will hold together for four to five hours at an average speed of better than 110 m.p.h. has come a new profession of master crafts- men: they are the geniuses of precision con- struction who build racing motors. And the dean of them all is Fred Offenhauser of Los Angeles, California. His story runs like fiction, a full-blown action story of a mild mannered, bald-headed man who is afraid to ride in a racing car, and yet has built Indianapolis winners for the last 54 Wilbur Shaw crossing the finish line as victor in the 1937 Indianapolis Speedway Race. motordotm's classic. Shaw drove his home-built racing car at an average speed of 113 m.p.h. four years. Once about twenty years ago Offenhauser rode in a racing car. When he got out, he leaned weakly on the hood and said: “I think these things would run a lot faster if I stayed in a machine shop.” So he hibernated in a shop for a long time, and when he came out the world saw a motor that could go alongside the famous Liberty engine as one of the supreme pieces of me- chanical perfection which America has built. But that’s a bit ahead of the story. Offenhauser first got into the motor build- ing game in 1916, when a French motor broke down in Los Angeles. The nearest parts were in Paris, and the race was a week off. Some- body remembered that Offenhauser, then working in a small carburetor plant, had a genius for building precision parts. The job was presented to him with a lot of French adjectives. Offenhauser paid no attention to the adjectives, and duplicated every one of the parts perfectly. This brought him to the attention of Harry Miller, at that time the world’s foremost builder of racing motors. A few years later, Offenhauser was in charge of Miller’s shop. In 1933 Miller went out of this type of busi- ness. Offenhauser was left without a job.

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He returned.to Los Angeles, scrapped to- gether all the money he could, bought some of Miller’s heavy power tools, and set up in the motor building business. But his motors no longer had the magic name of Miller, which had become synonymous with perfec- tion. Many of the drivers knew him per- sonally, but they thought of him as the foreman of a shop, not a designer. Early in 1934 Kelly Petello, daredevil little Italian, came to Offenhauser, looking for a motor to power his car in the coming Indi- anapolis race. “Look here, Fred," he declared, "I've got enough money to buy a car, but I haven't a cent left for a motor. I want to take a crack at Indianapolis this year. Would you build a motor and take your money out of the prize —if I place?” : Offenhauser wiped his hands on his bald spot, squinted at the plans for a motor he had just designed, and agreed. Two weeks before the race, Kelly drove out on the Indianapolis track for a trial. The car turned up an aver- age speed of better than 120 m.p.h. Both Kelly and Offenhauser were jubilant. The car was, however, using too much gas. A wire was installed by which the mechanic could turn off the idling jets when the car was running at high speed, and a second trial was run. within a few days. And then disaster struck. The motor broke .down, making a complete overhaul job necessary. Kelly was in despair, but Offen- hauser wasn’t beaten. During hectic days he wrought black magic. Night and day he worked on the dismantled motor. And just five minutes before the trial period closed, Kelly again rolled out on the track. He qualified easily, but went into the race as the rankest kind of outsider. For five hundred miles Offenhauser’s motor took every strain the track and the anxious Kelly could give it. And when the checkered flag swished down, it was in front of Kelly’s car. Offenhauser had built his first winner. Precision construction is the secret of the ability of racing car motors to bear up under the gruelling grind of a long high-speed race, so Fred Offenhauser’s shop in Los Angeles is equipped with some of the finest power tools pro- duced. Shown above is a crankshaft being machined for a specially designed motor. Craftsmanship in steel is shown in the photo at left. The racing car engine crank- shaft was machined in the Offenhauser shop from a bar of special nickel alloy steel such as shown at the left in the photo. Not one of his motors has ever failed during a race and many have powered cars of many winning drivers.

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That was in 1934. In 1935 an Offenhauser motor again won the classic and other of his power plants were in the money. Then in 1936 the black curse of breakdown struck once again. On a practice run Louis Meyer's motor threw a connecting rod through the block. But Offenhauser was prepared this time. He had brought along a spare motor and this was hurriedly installed. The jinx, however, was as resourceful as Offenhauser. On the next trial run another eonnecting rod snapped, and for the second time sliced Louiss motor almost in two. That looked like the end. But Offenhauser is a tough guy to beat. He wired Los Angeles and had a new block shipped by air express. Forty-eight hours later it was being installed in Louis's car. Again Offenhauser stared at his watch and pulled out his hair. And again the car quali- ficd minutes before the trials closed. Louis Meyers was the first driver to see the checkered flag when the race was run. In 1937 Offenhauser motors took first, second, fifth, eighth and ninth places. In those four years not one of his motors ever broke down during a race. Drivers were forced out because of trouble with the chassis or bodies, but never because an Offenhauser motor couldn’t take it. How can a man practically remove the chance of mechanical failure from a motor which must stand the hardest test an internal combustion engine ever receives? Will he do it this year? The best way to answer these questions is to tell the story of how an Offen- hauser motor is built. The first step is to select suitable materials. The motors must be light, and yet stand up under terrific strains. The four-cylinder Offenhauser motor turns up 5,500 r.p.m. (The average six-cylinder motor in a medium priced standard car is capable of 4,500 r.p.m. —but try and drive it at that speed for four hours). The compression ratio of the Offenhauser power plant is twice that of a normal motor. For the block a nickel alloy iron is used, which gives maximum hardness and a very fine-grained casting. The crankshaft is nitralloy steel which is cast at only 1,000? F., giving a very high tensile strength. It is then treated in a special air-tight furnace. The crankease, timing gear housing, camshaft housing, and intake manifold are from an aluminum alloy. Manganese bronze, having terrific strength, is used for engine brackets and bear- ing supports. In fact, the Offenhauser motor is a dramatic textbook on the latest in metallurgy. ‘T always investigate any new metal or alloy,” Offenhauser says. “My ex- perience with Miller taught me the importance of eter- nal testing and checking of new materials.” Considered the dean of racing car engine builders, Fred Offenhauser, shown making an adjustment on one of the giant gear cutting ma- chines with which his shop is equipped, eared the title by sheer mechanical genius plus plenty of hard work over a period, of years.

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Driver and builder get together to discuss business. Louis Meyers, fa- mous racing car driver (left) and winner of the 1936 Indianapolis Race, and Fred Offenhauser, master engine builder, examine castings of a trans- mission case constructed for a racer. All new materials are given hardness, tensile strength, expansion, and heat tests. When the metals are selected, they are cast to the rough shape desired. Then the machinery in the Offenhauser shop goes into action. Some of the finest heavy duty power tools in the world are used in this work, An ordinary looking bar of nickel steel, two or three feet long and about six inches in diameter, becomes beautifully turned crank- shaft. Rods and housings begin to take pre- cise shape. Then comes more testing. A casting may go through all the machining, look perfect, and still have a hidden flaw. Such a casting will play the very devil with the most careful work. Recently, however, two methods have been devised to eliminate this bugbear of mo- tor designing. Some castings are tested by X-ray. An even more delicate method, known as the magnaflux test, has been developed during the last two years. A casting to be checked by this test is first immersed in a bath con- taining lamp black and iron filings. Next the casting is placed between the poles of a special electro magnet. It is then washed. Any internal flaw will cause an opposition of the positive and negative magnetic fields at the point of the flaw. The iron filings will collect at this point, and the lamp black will leave a mark exactly corresponding to the shape of the flaw. After all the castings to be used in a motor are tested and found perfect—and perfect ac- cording to the Offenhauser standard means something approximating the theoretical ab- solute—the fine machine work is done. Racing motors are not, however, fitted as tightly as those of standard cars. Compared with the motor of the average pleasure car, a racing power plant seems extremely noisy. The large amount of clearance is needed to allow for expansion of the parts under the super-heated conditions of a race. But don't let the noise of a racing motor foolyou. Each part is machined with almost The X-ray plays a part in the eternal checking which is so vital in producing Indianapolis Race winners. Shown above is a crankshaft being submitted to an X-ray examination. The rays from the tube pass through the casting and leave a record of its internal structure on a photographic plate beneath it. unbelievable accuracy. In fact, these motors are so accurate that they require no breaking in. When they leave Offenhauser's shop, they are ready to race. A few slow laps to heat the oil and water, and the power plant is prepared for the big grind. Accuracy, accuracy, ACCURACY—that is the eternal password among the builders of racing motors. As Offenhauser says: “Drivers can afford to be superstitious, I can't. There's one “throttle thumper” who has fits if anyone in his pit eats peanuts during a 37

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Exacting tests of all machined parts are made before Offen- hauser assembles a motor deemed worthy to bear his name. To the eye these castings appeared identical and perfect, but when submitted to a magnafluxing test, the details of which are explained in the text. the casting on the right showed two flaws that would have caused a breakdown during a race. 58 A winner! This is the Offenhauser motor that Wilbur Shaw used to power his home-built racing car with which he broke ten years bad fuck to win the 1937 Indianapolis speed classic. This engine’s compression ratio is twice that of plain types. race. Another driver won’t drive until he’s eaten a dish of chow mein. Another fellow carries a girl’s handkerchief inside his crash helmet. But I can’t be superstitious. I have to go to a testing laboratory, instead of a fortune teller.” Anyway, you don’t have to go to a fortune teller to predict that Offenhauser motors will be in the money this year. Four years and four winners is a pretty good record. Which brings us to this year’s race, and the new problems which come with each suc- ceeding session on that famous oval. A good many of these problems will be met by the drivers in some split second decision, but a good many more will be solved in the shop Mechanix Iliustrated—] une, 1935

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long before race time. Most racing motors are ordered at least four months before the race. Power plants have, however, been built in eight weeks. When you have to construct a tailor-made motor in that time, you work night and day, and use up your vocabulary. The four-cylinder Offenhauser motor, with- out a supercharger, costs $2,500. This year the principal alteration in motor design is the result of the rule change which permits the use of “doctored” fuels. Last year only standard gasoline could be used, but when the starting bomb is fired in 1938, the gas tanks will be filled with all sorts of fancy mixtures containing tetraethyl, benzol and alcohol. Some cars will use pure alcohol, although this will add a new problem, due to the larger fuel consumption. The restric- tion on the amount of fuel consumed during the race has been eliminated, but the restric- tion imposed by gravity hasn’t been repealed yet. Extra fuel means extra weight. To get the maximum out of these condi- tions, the timing of Offenhauser motors has been lengthened. This will give greater speed and power but will cause the motors to con- sume more gas. The blocks have been slightly lengthened. More straight-eight motors will be used this year and the compression ratio has been increased to 14 to 1. The majority of Offenhauser motors have four cylinders. A mysterious straight-eight or two are, however, being constructed. The eight cylinder jobs have greater smoothness and acceleration, but they consume more [Continued on page 136] Radio announcers crowd around Wilbur Shaw and his me- chanic, Johnson, a few minutes after he crossed the finish line as winner of the 1937 Indianapolis Race. One can readi- ly appreciate the endurance and precision that must be built into a racing car engine by Pondering the fact that Shaw’s car traveled the 500 miles in 4 hours, 24 minutes. formerly Modern Mechanix Capable of standing the most terrific punishment to which parts of an internal combustion engine can be subjected, yet so light that a woman can support it on two fingers, this aluminum alloy manifold may play an important part in the 1938 Indianapolis Race. Every part of the winning engine must be perfect, for breakdowns mean a lost race. Kelly Petello, daredevil Italian racer, was the first man to drive a winning car powered by an Offenhauser motor. In the photograph above, he is shown just after receiving a golden helmet after winning a dash on a western track. When he entered the 1934 grind, Kelly staked his sav- ings from years of driving on the Offenhauser engine. 59

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60 Жаза, Bed, | ) void Toa | y udi 1\4 One-Man Cross Cut Saw Fells Large Trees Quickly HIS one-man cross cut saw easily fells large standing trees, and cross cuts logs and timbers of any size lying on the ground. It does the work faster than two men with the conventional type saw, and with less than the usual amount of effort. The saw blade is attached to a frame or carriage, which is securely clamped by three large claws to the standing tree or log that is to be cut. The frame is 63 inches high and the saw blade is 59 inches long. The blade is moved back ‘and forth on a curved arm or handle which is suspended from a large curved flat spring. Artist Finds Making Weather Vanes Profitable Hobby EVERAL years ago Henry Marx, an artist living in Beverly Hills, California, started making weather vanes and metal art novelties as a hobby. Visitors to his home sought to purchase his product, and soon Marx de- veloped the hobby into this unusual business. He creates the weather vanes from sheet metal, adapting drawings and pictures from various magazines. His interesting weather vanes include ships under full sail, covered wagons, a hunter and his dog, and many other suitable subjects. When placed at the top of a flag pole or house, they lend a pleas- ing appearance, as well as serve a useful pur- pose. If desired, they can be painted with bright colors. Many metal craftsmen will find weather vanes a new subject for their metal cutting shears. Polaroid Lighting Unit Gives Glareless Illumination EVOLUTIONARY in performance and design, this Polaroid lighting unit is in- tended primarily for desks. Presented. as the only known method of completely eliminating glare, optical and illuminating authorities hail the lamp as a forerunner of a new era in light- ing. The glareless feature permits focusing of light on the working plane and gives even distribution over the entire surface. Polaroid lighting has no reflected glare; therefore vi- sion is easy and precise. Colors are enriched, contrasts increased, and detail is intensified. Mechanix Illustrated—June, 1938

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Builds Gas Model Of Douglas Plane EPRESENTING about 900 hours. work, a gasoline-pow- ered model of a Douglas DC-3 air liner constructed by James Beard, of South Bend, Ind., is valued at $2,000. The model de- viates from its prototype in that it has pontoons and only one en- gine, which is said to fly the three and one-half pound replica for 27 minutes on one ounce of fuel. The model has a wingspan of 66 inches and features cellular con- struction. Puppet Show Teaches Traffic Laws HE ancient art of puppetry has been enlisted by the Bureau of Public Safety of Detroit, Mich., in a novel campaign to cut the accident toll of modern traffic. A play—"Stop, Look and Listen"— enacted by marionettes, is being shown at all of the city's schools in an effort to impress children with safety rules. The cast of marionettes features a policeman, a teacher, children, stop lights, and traffic in the form of model au- tomobiles, which are actuated by motor-driven belts. Robot Checker Player Is Undefeated WNED by Frank Frain, of New York, N. Y., a mechan- ically created robot is said to have played in more than 25,000 checker matches without being defeated. Sponsored by a well know radio manufacturer, the “Magic Brain Checker Player,” as the robot is known, is making a tour of the country. Standing six feet tall and weighing 500 pounds, the robot disdainfully sweeps the checkerboard clear of checkers if its opponent attempts to cheat. formerly Modern Mechanix 61

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Solitaire Bridge Board Gives Expert Opposition SOLITAIRE bridge game with this board supplies the player with expert opponents and ап expert partner. The player bids only his hand, and the partner and opponents automatically bid correctly, no matter how inexpert the player may be. The bidding is adaptable to all systems. It is claimed that with a rudimentary knowledge gained from any self- teaching bridge book, a player can perfect his game by using this board. In use, the board’s hands are played exactly like those in a game of contract. After the bid- ding is finished, playing starts. The player can make errors, but because the opponents are ex- perts, they capitalize on mistakes. Giant Machine Sews Ten-Foot Blankets WELVE rows of stitches are sewn simultaneously by the largest sewing machine in the world. This machine is used to stitch cloth onto ten-foot wide blankets of glass wool five inches thick. Because of the resilience of the fibres in the “wool,” there is no tendency to settle under con- tinuous vibration, thereby making it especially useful for insulating trucks, buses, refrigerator cars and air ducts. Flash Takes 2 Bulb Sizes NEW synchronized flash-gun attachment for cameras features an adjustable reflector designed to center exactly over flashbulbs of both small and large sizes. Portable Car Heater AKING it unnecessary to heat the entire garage, this gas- electric warmer uses any type of gas for fuel, and electricity to operate the blower motor. The heated air is forced through the louvre openings. 62 Mechanix Illustrated—June, 1938

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Opportunities For The SMALL INVENTOR Water skiing, a new sport packed with thrills, has been promoted in this-country through the help of Northill water skiis, which feature an adjustable foot receptacle. MPHATICALLY answering the fre- quently-heard question — “Do small inventors have a chance today?"—a Los Angeles concern has been proving for some- time that inventors not only do have a chance, but that money is to be made for everyone. Today the company has direct sales offices in principal American cities; it has inter- national representatives scattered through twenty-nine nations around the world; it has leased manufacturing rights on several of formerly Modern Mechanix In their offices, Ada Wil- bur (left) and Blanche Hill inspect an hydraulic pump. In the back- ground is an anchor which will hold a twenty- foot boat. _John K. Northrop, fa- mous airplane designer, with one of his light- weight folding anchors which does the work of other anchors weighing 20 to 30 times as much. its items to a British firm for overseas manufacturing; it has the services of an internationally known engineer as active con- sultant and a staff of engineers under his direction, and it has built itself an ultra- modern building in Los Angeles to house its executive and sales staff and its assembly and shipping departments. Blanche Hill and Ada Wilbur, president and secretary-treasurer respectively, of the [Continued on page 140]

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Builds Model Bungalow From 10,000 Matchsticks OMPRISED of more than 10,000 burnt matchsticks, which his friends collected for him, a novel model bungalow has recently been con- structed by Russell A. Dade, of Montreal, Can- ada. Furniture for the bungalow’s tiny rooms was also built-up from matchsticks. No nails or pins were used in assem- bling the model, each matchstick being held in place by glue. About three pints of glue were required for the job, Sd к, which represents five MERI lia months spare time. Auto Safe Thwarts Hold Ups O THWART hold ups of its drivers, a delivery firm has equipped its autos with safes attached to the truck with tamper-proof bolts. Keys are kept in the main office. Hand Guides Giant Riveter XERTING a force of 40 tons on huge rivets used in construction work, a new hydraulic riveter weighs four tons, but is so delicately balanced that it can be tilted or swung by a mere touch of a workman’s hand. 64

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Welder Makes Own Oxygen TILIZING an old gas tank holding car- SING a special high speed camera, bon, an electric motor, a tank for acety- Géneral Electric engineers obtained lene gas and a wheeled frame, a Michigar this unusual photo of the Empire State craftsman has developed an outfit that en- | Building in New York, N. Y., being struck ables him to make oxygen for welding. _. by lightning 11 times in 0.36 of a second. Device Converts Sawdust To Logs LEAN sawdust and shavings, fed into the hopper of a newly de- veloped machine, emerge a few seconds later in the form of a hard, round log. The machine consists es- sentially of a large wheel containing individual holes into which a ram under pressure of 185,000 pounds is guided, compressing the mass of shavings in each hole to one-ninth its former volume.

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JBNNYHI Чалы s^, uva аззуошш i зампоно ONIMIVSedS OL Wy Wous оз5узлза AYiVnGVuD ualvAM *( xe) ur влеәйде иодеиеуахд) ‘sesodand эцвәшор 10; ләзем ства рәјѕем оззәуич әлләвиоо оу рие вроор зиәләз@ оў вләәш пә Auman sepsuy soy 4q dn jas “d}0 ‘suiseq aSe10}s punod83epun | ‘шер 2 asks 043 sheajsod шесе uoexs sagspnae smp, VO 3OvHOLS lO "NOLLVAMIISN SUBLYM MONS ОМУ TivaNIVY Ошу SIMS 7 NIVINNOW NO SWYG 1 WOSHO 3208 ану gsnug 1938 Illustrated—]J une, Ix Mechan 66

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FIGHTING WATER FAMINE Scientific water conservation methods are man’s salvation. НЕ floods which spread devastation and death in southern California last March brought home to the nation once again the terror that lies in water when it breaks beyond man’s control. Properly harnessed and handled, water is a boon without which life would cease to exist; out of control it becomes one of man’s most dreaded enemies. It is both killer and life-giver—friend and menace. The spectacular nature of the recent floods dramatized the destruction which water sometimes inflicts, but there is another side to the problem which is far more threatening and which is not generally realized. Too much water means loss of life and property in restricted areas; but too little water threatens the very basis of human existence in vast sections of the country where population is thickest. That is why engineers viewed the catastrophe of last March not only in terms of lives lost formerly Modern Mechanix ‘water like huge sponges. by D. A. Lane Water Development Engineer Los Angeles Department of Water & Power i I | Above—This home was wrecked as a result of a cloudburst near Montrose, Calif., before proper flood control methods to divert rain waters into the ground were adopted. Left— An engineer using a device that gauges a rivet's rate of flow. and property destroyed, but also in terms of waste—waste of precious water that could be hoarded and put to work serving man instead of destroying him. For some time, engineers in the West have been working on ingenious systems to pre- serve water and thus protect millions of people who live under the threat of water famine. The engineers are employing one underlying principle to meet this great prob- lem of modern times: To save water, pour it into the ground! This sensational new system of water- saving causes wells to flow backward and rivers to run upside down. Mountains dotted with hundreds of miniature dams soak up , Runaway water- courses are equipped with flexible bottoms, tailored to fit like gloves. Underground wells, drilled on their sides, draw millions of gallons daily from an empty river whose bot- tom is dry as dust. Billions of bacteria, con- tained in yeast are made to digest raw sewage, miraculously purifying it into spark- ling clean drinking water. A crisis came when wells supplying water for the city of Los Angeles dropped ominously low. Slow seepage from the ocean began to turn some wells to brine. Thirty-four had to 67

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be abandoned. Over an area of 162 square miles, the subsurface water-level dropped below the sea. The city still had the man- made river built twenty years ago by William Mulholland, which brings water 250 miles from the high Sierras, but local sources which for years had supplemented it were failing. Geologists spoke plainly when asked for advice. Twenty-six great underground lakes, they said, supply all wells in the region. During the wet season, rainfall recharges this great natural reservoir. But since the cities have grown, the rain, now falling on acres of washes and stream beds to vanish into the ocean without adding more than a small amount to the contents of the underground basins. They saw an earlier flood submerge farms and city streets, doing $10,000,000 damage while more than a million dollars’ worth of water was being lost—enough to supply the needs of 450,000 people. The floods of last: Spring brought the problem into sharper focus than ever before. We must make the mountains absorb more water, engineers said. The mountains must suck up rain like sponges, instead of allowing Above—Hinged concrete slab beds and concrete banks are fitted to runaway teservoirs. roofs, and on more than fifty square miles of paved streets, is carried off in storm drains to the ocean instead of returning to the ground. Meanwhile, a growing population draws more and more heavily on the rapidly falling sub- terranean lakes. In our modern homes water is wasted Shamefully. Every time a housewife wants a cupful of hot water, she goes to the faucet and runs about a gallon of cold water into the drain. Americans use about 140 gallons a day per capita, on the average. On the other hand, citizens of Berlin, London, and Paris, use only about 45 gallons a day. The average American wastes that much every twenty- four hours! Engineers looked about for new sources of the precious fluid. They saw the storm drains carry away whole rivers of water. They saw rain-washed mountains sbed racing torrents which swept down gravel 68 watercourses so that the water can be carried to specially located spreading grounds where it will gradually be absorbed and stored in subterranean Right—Laying a section of typical aqueduct pipe in place. it to race down the slopes, scouring gullies and stripping away vegetation. Cooperating agencies of city, county, state, and the federal government began to gather data. Rainfall was measured at 310 stations. Twenty-seven hundred wells were sounded regularly; streams were gauged at 1,500 points, At 57 stations high in the mountains, snow-shoe crews punched through the snow blanket with circular core-samplers, cutting cylinders which they weighed to estimate the amount of water thus stored. Other ob- servers estimated the amount of debris carried away, and measured precipitation and run-off. United States Geological Survey field men supplied still more figures. Workmen were set building check-dams. All over the hills they piled brush, drove posts, and poured concrete. High up on the mountains they erected tiny barriers of stone, branches, and wire netting at points where Mechanix Illustrated—June, 1938

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gullies converged and channels were forming. Lower down, they built more substantial dams with cement foundations. These bar- riers were not to store the water, but merely to check its onrush, allowing it more time to soak in and tremendously reducing its power to strip off the topsoil. Rains brought down debris which matted and chinked up the dams. Shrubbery grew thicker. Gradually the mountains were car- peted with a spongy litter of leaf-mould, twigs, and branches, which absorbs water readily and lets it percolate slowly into the ground. Experts estimate the value of this cover at from $250 to $1,000 per acre. Having stopped the little leaks at the source, engineers next planned to trap the heavy floods which still roared down the canyons during rains. Mountain reservoirs Left—This large city reservoir is small when compared to the huge underground storage basine created by engineers. Above—A rock, wire and brush check dam that serves to slow the onrush of water down a mountain side, allowing it time to soak into the ground. would not do, for in order to harvest a large enough “water crop” lakes of terrific size would have to be impounded. Sunshine absorbs tremendous quantities of water from open reservoirs, but water poured into granite basins below ground remains. To place these dams strategically, an air- plane survey was made.. Mapping planes zigzagged back and forth above the moun- tains, snapping photographs which were then pieced together into a mosaic. Engineers studied this under a stereoscope, choosing the ten best sites, avoiding “live” faults, where earthquakes might bring slippage. These dams are part of a bigger scheme to save the water by pouring it into the ground [Continued on page 142] Beautiful] curves lend strength to the Big Dalton Dam which impounds drinking water for the Los Angeles County area. formerly Modern Mechanix 69

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| These pictures are | representative of | the effort and facili- | ties put behind Vitaphone pictures. Above: A railroad sequence being i — "shot" on location. |^ Below: “Holly- | wood-in-Brook- iyn”; one corner of | a huge sound stage |. in the Vitaphone | studio in New York, where more than a hundred "shorts" are pro- | duced every year. OMETHING new and unusual in movie “shorts” will be offered to the public when the first of a series of Vitaphone- MzcHANIX ILLUSTRATED films is released soon to theatres throughout the country. Made in full natural color by Warner Brothers’ Vita- phone Studio in collaboration with the editors of this magazine, these absorbingly inter- 70 "Mechanix Illustrated" £ esting movies will take audiences into sci- ence’s laboratories and industry’s factories, and will show for the first time how many of the marvels of our modern civilization are conceived and produced. The films will run about ten minutes and each will deal with four specially chosen topics. However, months of preliminary in- Mechanix Illustrated—June, 1938

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| Vitaphone In The MOVI (uu | In Natural 2 3 Color Will m — Be Unique, Interesting Above: Sam Sax, head of Warner Brothers’ Vitaphone Studio, Brooklyn, N. Y., under whose supervision the | MECHANIX ILLUS. | | TRATED films are be- | ing made. The two pictures on the | teft show Vitaphone camera crews on the job. Top: filming the permanent model rail- road built up by the Mew York Society of Model Engineers. Left: і The color camera re- | cords a wool dyeing op- | eration in a factory. Setting up a heavy camera and a battery of powerful lights some- times takes hours, while the actual shooting may take only afew minutes. | Don't miss first Vita- phone-MECHANIX ILLUSTRATED film! Mail us the convenient ; coupon below on write us a postcard if you do not want to cut your copy of the magazine. No obligation on your part, of course. жй а ть иа нї ип иа эң ки ШШ И TITS Editor, MECHANIX ILLUSTRATED 1501 Broadway, New York, N. Y. I want to see the first of the Vitaphone-MECHANIX ILLUSTRATED Shorts. Please let me know when my local theatre ........... ccc RR ene (please fill vestigation and preparation have been put into them. Warner Brothers production experts and cameranien, accompanied by members of the MxzcuHANIX ILLUSTRATED edi- torial staff, visited many locations in their quest for colorful, human-interest material. and spent many hours on research before [Continued on page 144] in its name) will show it. City State formerly Modern Mechanix 71 та n ни жа рш иа аш ша шї ша ив иш иш ши ип иш иш рш ши ша жа аш иш йш та э шп пш шр 2 р В о

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Rural Mail Box Tilts Open N AUTOMATIC rural mail box, which tilts forward when opened and allows the mail to slide into the cover where it is easily removed, has recently been invented by a resident of Minneapolis, Minn. The old type stationary mail box is sometimes diffi- cult to empty from a wagon or automobile, but the new mail box is said to eliminate this trouble entirely. When the door of the new box is opened, the flag drops automatically, the box tilts forward as shown in the photo and the contents slides into the cover. Upon removing all the mail, the hinged cover au- tomatically closes. Levers Control Bike Brakes FRONT wheel brake, operated from the handlebar and a two-speed rear wheel coaster brake, operated by a lever mounted on the frame, have been developed for bicycle use. The rear brake has a change speed gear which provides extra power on hills, quick pick-up, and more speed. Photo shows finger- tip controls. 72 Builds 8-Foot Cottage Model EATURING a floor size of eight by ten feet and a height of about eight feet, a perfectly detailed model of a Cape Cod cot- tage was recently constructed by George Brink, of Waterloo, N. Y. The little house contains four rooms and a bath, hard-wood floors and is completely furnished with furni- ture also made by Mr. Brink. The living room of the model home has a stone fireplace, the chimney running up the side of the house. Stone steps lead to the door of the house and, together with the gut- ters and little green blinds on the windows, help to create a real New England appearance. Photo Cutter Is Self-Honing OUNTED on rubber-tipped feet to keep it from sliding, a newly developed photograph trimmer features a patented hinge and suspension spring that holds its two knives in such a position that they rub against each other, honing the blades. The trimmer is equipped with a gauge that shows exactly where a photo is to be cut. Mechanix Illustrated—fJune, 1938

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29,000 Bowlers Participate In LOSE to 25,000 bowl- ers, members of 5,000 five-man teams, recently gathered in Chicago, IIL, to attend the mammoth competition sponsored by the American Bowling Congress. The competi- tion lasted for one and a half months and the prizes totaled $290,000. Because of the large number of contestants, the competition was de- clared to be the nation’s most extravagant sports event. More than forty alleys were constructed at the contest site to accommodate the bowlers. Invents "Disc-Rotor" Aircraft LAIMED to combine the best features of the airplane and autogiro, a “disc-rotor” aircraft has been invented by J. S. Caldwell, of Washington, D. C. The new plane cannot tailspin or nosedive, according to the inventor. The craft’s overhead disc-rotor is locked in place during flight, but rotates freely during landings, making vertical descents possible. Trailer Photo Lab Developed HOWN below is a photograph of a service test of anew mobile photographic labora- tory developed by the U. S. Army Air Corps. A plane has just landed "behind the lines" with negatives showing infantry maneuvers. Rushed to the darkroom, the negatives are soon developed and finished prints are handed to the pilot for delivery to regiments occupy- ing “front line" positions, Mechanix formerly Modern National Contest

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Drive Next Year's Blowouts or bumps mean nothing to a car when it is ` equipped with a hydraulic steering stabilizer. This device takes control of the wheel in an emergency and prevents the car from leaving its true course on the highway. Right—The stabilizer fastened in place. HETHER your car is a sparkling 1938 model or something which you are obliged to drive another year, it has never been easier to have a taste of tomorrow’s motoring—now. The idea is suggested by the offering of an unusual number of ingenious and practical accessories. These new gadgets banish some of the ancient fears in driving, shorten the time required to keep the car up to par, and step up performance in a num- ber of ways. Do you drive in constant fear of a blowout? Are you annoyed by the penalty for for- getting to add water to the battery? Do you feel that the engine should give better per- formance, and would you care to try super- charging? Are you still changing engine oil every thousand miles? Do you envy those who are enjoying many new conveniences which you assume are available only on new cars? If so, step right up to the accessory counter and take your pick. Your 1939 car is ready! Automotive engineers are looking over the present automobile with a view to seeing what new uses they can find for principles 74 It was this policy that already employed. helped in the creation of a device that takes the hazard out of blowouts. If hydraulic shock absorbers control spring action, why not use a special shock absorber on the steer- ing tierod? Why wouldn’t this device effec- tively check the tierod’s movement, in event of a front tire blowout, and prevent the steer- ing wheel from snapping out of the driver’s hand? When an automotive engineer asks “why?” he generally ends by providing the answer. So a four-star accessory is born. With this large hydraulic hand on the car it is possible to strike a railroad tie with one of the front wheels while the car is traveling sixty miles Mechanix Illustrated—J une, 1938

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Car Today by Frederick C. Russell Ingenious new accessories will put your car a year ahead in comfort, convenience and safety. This device provides air conditioning for the car. Using the cowl ventilator as an intake, it purifies, warms and circulates air in the car. Tests | have shown that this | device is particularly helpful when the out- side air is very dusty. Imagine driving up to your garage, touching a button on the dash and having the doors open automatically and close when the car is inside. Why wait for it to become standard equipment? this magic feature now. an hour—and live happily ever after, even if the driver takes his hands from the wheel! No one wants to try that stunt, but the steer- ing stabilizer is built to give that much margin of protection. Whether the car’s stability is endangered by road obstruction or by tire collapse it continues in a straight- ahead direction unless the driver finds it necessary to steer to the right or left. To- morrow’s car will have this protection, but you can have it today. Solving the problem in a somewhat differ- ent way is the special inner wheel which serves to prevent that dangerous drop which occurs when a tire blows. The inner wheel takes over the job of supporting its end of the car until the driver has a chance to slow formerly Modern Mechanix You can have down and stop. Instead of dropping the dan- gerous distance to the rim the troublesome wheel drops only an inch or so to the edge of the safety inner wheel. Even though flat as a pancake the tire cannot offer that ter- rific resistance which usually is sufficient to throw a car out of control. With either or both of these devices on the car, and with those special inner tubes which are being offered by major rubber companies, the fear of sudden tire collapse is definitely out of the picture for any motor- ist who wants his future motoring today. These safety inner tubes do away with the annoyance as well as danger from punctures. There is no particular magic about it. The thick center section of such a tube is turned 75

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Above — Smeared or dirty windshields will be a thing of the past when this automatic wind- shield washer is used. (THOROUGHLY ATOMIZED | | VAPOR Genuine supercharg- ers are expensive. However, simpler types that help the engine breathe can be installed easily. 76 inside out so that when punctured the rubber closes in around the sharp object or fills up the cut left when the object is withdrawn. One of the tire companies recently an- nounced a new chemical which, when in- jected into the inner tube with a special pressure gun, will cause punctures to close up immediately and permanently. Rotation of the wheel spreads the coating evenly. The protective coating remains in place as long as the tire stands, and it will not clog the valve. The whole appearance of the car can be changed by a process of retrimming the hood and sides of the body. Fresh air advocates can have the sunshine tops installed in their present cars. Now that this familiar taxicab feature is available for all cars even the man with a sedan can enjoy a convertible feature that will doubtless be standard equipment in the years to come. More radical is the new control system which consists of full power brakes, clutch and throttle, operated by vacuum cylinders which are, in turn, operated by a control wheel. This special wheel is mounted just below the steering wheel on a collar which allows it to rotate freely and to be carried with the steering wheel when turning. It also slides up and down the column, this special motion con- trolling the valves and thus the car. Designed especially for paralytics and others who have the misfortune of not being able to use their feet when operating a car, this highly efficient A new wheel safeguard makes it possible to continue driving after a blowout without dam- age to the tire or the wheel. Mechanix Illustrated—June, 1938

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and extremly simple control system may eventually hasten the demise of all foot con- trols. Last year this system looked unwieldy be- cause the average driver shied at the idea of having anything in the way of a control under the steering wheel. Today, with so many of the 1938 models featuring remote controls for shifting gears, the system looks far less un- usual, Tomorrow it should look as simple as hydraulic brakes, but why wait until to- morrow? For those who want to take the step in in- stallments, why not consider a power brake hooster? Such a device operates from engine intake vacuum. Its piston draws on the brake pedal arm and thus can be used with either mechanical or hydraulic systems. A control knob attached to the rim of the steering wheel will aid in handling the car in traffic or in parking. The horn ring, which has become so popular with today’s car, can be attached to any of the cars manufactured within the last few years. It is fitted to the inner part of the horn control, the button proper being replaced when the ring is at- tached. This is a great improvement over the former method of using a suction cup to hold the ring in place. In the line of new controls perhaps the most unusual is the rear-door safety lock which comes as a blessing to parents who happen to own cars of the four-door type. Children fidgeting. around the tonneau cannot open the doors while the car is in motion nor until the person at the wheel releases the special remote control lock. The idea has other. uses. There is greater convenience in locking and formerly Modern Mechanix No longer is it necessary to get out of the car to adjust the “buggy whip” antenna. This new type can be taised or lowered quickly and easily from the inside. Here is a convenience many cat owners will appreciate—an automatic storage battery filler. Left—Small tnetal weights are inserted in the rubber blades of this defrosting fan to re- move all excess vibration. 77

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Deren Op— emonstration car, equipped with special tires, about to run over spikes to cause blowouts. having unusual safety features. Below—A cutaway drawing of a tire In the diagram, "A" indicates the valve stem, "B" is a vent hole, and "C" the inner air chamber which will support the wheel even though the casing and tube has blown. үтте e E: A 4 a Се 2 n = = = | 7- CASING MAY BLOW! | 2-TUBE BLOWS, ALSO!| 3-Syth YOU STOR SAFELY unlocking the doors, and locking out a would-be intruder is short work. Since the doors cannot accidentally fly open there are other advantages to this control system which anyone who has ever ripped off a door will appreciate. Does this sound like something that would be about as cheap as buying a new car? Well, here’s good news: a pair of these rear-door locks sells for less than five dollars. Another gadget that should prevent many accidents is a button control for selecting radio pro- rams. Instantly you can tune your car re- ceiver to any one of six favorite stations. You do not have to take your eyes off the road, because it is easy to learn the position of the buttons and you can easily feel them even in the dark. Cars of tomorrow will all carry automatic station selectors, but you need not wait for this. The convenience and safety of button tuning is here now. Unusual is the newest of the wide assort- ment of buggy-whip adio aerials for the car. You have doubtless seen, and perhaps tried, the type that is adjustable as to length, but 78 now there is one that can be raised and low- ered without the necessity of reaching out the window or leaving the driving compart- ment. It is attached to the instrument panel, its tip passing up through the car's roof. An- other welcome idea is the special mirror which clamps to the top hinge of the left front door. Its function is to give you vision to the rear in that special "blind spot" formed by the rear panel of the body. Looking into this special mirror you have the impression of being able to see behind as easily as if the car were a roadster with the top down. Have you, among other things, ever stopped to wonder what would happen if your car upset and the engine continued to run? You might easily escape injury as a result of the upset, for the modern all-steel top is a re- markably strong piece of construction, but with the engine running and gas and oil spill- ing all over it there might easily be a fatal epilogue in the form of a fire. This can be avoided by installing a simple little protection switch which automatically turns off the [Continued on page 149] Mechanix Illustrated—June, 1938

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Carpenter Builds Bandsaw jj о F tomobile Part - Wa rom Old Automobile Parts : Ҥ VN AKING wood working machinery out of с Р discarded auto and electrical parts is oe the hobby of W. S. Wagner, a carpenter in 1 came Y Grand Island, Nebraska, who recently com- ze BE Уда pleted the construction of a heavy-duty band- saw. The machine cost only $18 to build and cuts wood up to four feet wide. For the frame of his home-built bandsaw, Wagner converted a couple of old bedsteads. An automobile differential was used as a support for two wheels around which the bandsaw revolves, the wheels themselves being taken from an obsolete automobile. He then secured a one-half horsepower electric motor from an old washing machine and con- nected it to the wheels by means of a belt. The saw has a throat of 28 inches, which is considerably larger than the average. Machine With Spiked Frame Aerates Lawn Soil RECENTLY developed machine simpli- fies the job of aerating the soil beneath alawn. The machine features a series of steel spikes attached to a square frame in such a manner that when it is pushed over the lawn the steel spikes are forced into the ground. As the frame turns, a new series of spikes makes more holes in the ground thus making it easy for air and water to enter. One person can operate the machine and cover a large area in a single day's work. Portable Pile Driver Works Like Diesel Engine Ce with a light tripod mounting, a newly developed portable Diesel pile driver features a. 660-pound hammer that strikes a blow of 3,630 pounds at a rate of fifty to seventy times per minute. The device operates all day on three quarts of fuel oil, costing about six cents. When released, the hammer falls upon a heavy block with a piston protruding up- wards. Air in the cylinder is compressed by the hammer’s fall and, at the same instant, fuel oil is ejected. The resultant explosion throws the hammer into the air again. The hammer stroke varies from 2% to 5 feet. formerly Modern Mechanix 79

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Home-Built Catapult Lowers Trap Shooting Costs T A COST of only one dollar for lumber, two California trap shooting enthusiasts rigged up a catapult which, as shown in the ac- companying photos, hurls old tin cans into the air as a substitute for clay bird targets. Welders’ Goggles Feature Hinged Lenses EVELOPED for use by welders, goggles designed by a Reading, Pa., manufac- turer feature colored lenses hinged over clear lenses so that they can be raised to permit the welder to inspect his work. The colored lenses are designed to protect the eyes from the infra rays of the welding arc. "Sea Monsters" Are Log Rafts ESEMBLING huge marine monsters, rafts consisting of thou- sands of logs bound together with chains to- taling 175 tons in weight are a common sight on the Columbia River in Ore- gon. The logs comprising the rafts are sold to nu- merous paper mills and lumber firms en route. 80 Mechanix Illustrated—June, 1938

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New Device Measures Transparency Of Lake Waters HE instrument shown at the right measures the passage of solar radiation through lake waters, furnishing a basis for the addition of fertilizer to bring about a more abundant growth of plant life for the propagation of fish. The sun’s rays striking the instrument cause a reading on a meter in the boat. Student Constructs Loud Speaking Electric Guitar ARL WISCHMEYER, Yale engineering student, is shown with an electric guitar he con- structed. For use on regular house current, it is claimed to have better tone and more volume than.the conventional type instru- ment. At the left is shown the loudspeaker and amplifying equipment used for producing varying degrees of volume, from a mere whisper to the maximum possible with this particular amplifier. With equipment such as this, a musical instrument can be given a voice loud enough to be heard for miles, if desired. In- struments of this type are be- coming increasingly popular in dance orchestras, because nor- mally soft voiced instruments can be made as loud as conditions re- quire. Played like a conventional guitar, volume is increased merely by turning up the volume control. formerly Modern Mechanix 81

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ИЧИМ МЇНВАЙ Reveal Unknown Stars gre in — aluminizing їсаЇ telescopes. i s Examining some small mirrors that have been given a new reflecting surface. The vacuum chamber is first tested out with small mirrors before larger ones get their "shot" of aluminum. 82 Adjusting the pumps that reduce the air pressure within the aluminizing chamber to one-millionth of outside pressure. NEW aluminizing process by means of which a film of metallic aluminum only four-millionths of an inch thick is applied to the mirrors of astronomical telescopes, is said to increase the efficiency of the telescopes, making it possible to reflect the invisible ultra-violet light of stars much better than silver-covered mirrors. The aluminum is ap- plied to the mirrors by placing them in a sealed chamber from which the air is evacuated for eight hours while an electric current, passing through tungsten wire, evaporates two small pieces of aluminum over the surface of the mirrors. Mechanix Illustrated—J une, 1938

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Mailbox Picks Up, Delivers Mail QUIPPING an ordinary rural type mailbox with a small electric motor and mount- ing the box on pulleys to per- mit its passage over trolley wires, R. H. Bess, a rancher in Downey, Calif., devised a mail pick-up system that saves him a half-mile walk every day. By pressing a button in his home, the rancher causes the elec- trically powered mailbox to leave his porch, travel down the trolley wires to the roadside and return with mail after it has been deposited by the postman. Bess is said to have applied for a patent on his traveling mailbox, which is shown in photo at right. Mechanical Bed Is Boon To Patients ESIGNED primarily to eliminate bed sores, the bane of all bedridden patients, a newly developed mechanical bed gently rolls a helpless patient on his side—right or left—or raises him to a sitting position at the mere pressing of a. button held in his hand. Developed by Dr. C. E. Sharp, at the Ohio State University laboratories, the mechanical bed is actuated by a small elec- tric washing machine motor connected to a pulley system. New Type Airship Flys By “Kicking” MODEL of a new dirigible was recently placed on exhibition in Washington, D. C. The dirigible design fea- tures a novel:method of pro- pulsion whereby air sucked through a tube is ejected at the stern, providing a propulsive “kick.” formerly Modern Mechanix

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Transparent Weather Chart Aids Flyers NVENTED by Kenneth and Dennis Bartlett, of London, England, a new three-dimensional aviation weather chart is said to make it possible to chart weather conditions at various altitudes over the 2,000-mile flying route between Ireland and Newfound- land. The chart consists of a six- inch, cubic, transparent box which is fitted with shelves to represent different altitudes. Imperial Air- ways will test the chart on ex- perimental flights. Enamel BakingLamps Resemble Clam Shells EPLACING conventional bake ovens, “clam shells" equipped with hundreds of infra- red ray reflectors are now being used for baking enamel on auto- mobile bodies in the plant of a car manufacturer in Rouge, Mich. : Mounted on conveyors, the shells fold around the automobile body and proceed with it to the end of the baking line, providing con- stant, controlled heat throughout the entire baking process, thus in- suring an even coating and har- dening of the enamel on the body. Stubby Farm Tractor Has Single Tread ONSUMING only half a gallon of gasoline per hour, a newly developed farm tractor features a single tread mechanism which is powered by a two-cylinder motor- cycle engine. Designed to replace a team of horses, the stubby tractor is easily handled and can be turned in very small circles. The machine has a wheeled draw- bar which can be replaced by any standard farm implement.

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Carves Scale Model Of Ocean Liner EPRESENTING nearly 12 months work with knife, wood and thread, a three-foot model of the Queen Mary ocean liner has recently been completed by F. Ratcliffe, of Cheshire, En- Bland. The model was carved to scale from measurements deter- mined by a careful study of pho- tographs of the gigantic passenger liner. The model liner is Mr. Ratcliffe’s latest effort, but he has also carved excellent tug and barge models, as shown in photo. Midget Steam Engine Has Thimble Boiler O SMALL that it can be con- cealed in the palm of the hand, a novel working steam engine re- cently placed on exhibition in New York, N. Y., features an ordinary small-sized sewing thim- ble as its boiler. Because of its diminutiveness, the flywheel, piston, connecting rod and other parts of the steam engine had to be specially constructed. Despite its compactness, the engine is said to.be powerful enough to drive several small toys. Switching Locomotive Has Four Engines OWERED by four Diesel en- gines, any one or all of which may be used according to the load, a new type of railway engine is said to provide an economical means of switching a few cars or an entire train. Constructed by a Davenport, Iowa, firm, the new engine weighs 102 tons. To re- verse direction, the engineer sim- ply moves from controls at one side of the cab to the other.

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War PO AS COLLECTORS ITEMS _ Гу Montgomery Mulford Shows shove are jae kanan and Соп ‘military : 2 рш which were issued а the Boxer Rebellion. Many mae scies n possess d Bened interest. Shown B eee here the | was t ev. 1 Wedd Wa tee apa mail postmarks date wu 1661, i A S, det appeared during : Wars h which ied. in 1854. 86 HE first regular mail postmarks were adopted in England by William Dockra in 1661, and used until 1787. Since then, post- marks have been essential to mark or cancèl mail, and will be seen to be generations older than adhesive postage stamps. When armies went into the field, it was found that postmarks of special kinds had to be made, showing the source of letters. It is said that the first military, or war post- marks, appeared during the Crimean War. Since then, armies in the field have generally had their own individual postmarks, many of which are collectible items today, some quite rare. There are a number of World War postmarks which are quite elusive now, al- though common in 1917-18. Rarity, in most instances—as in the case of the World War ‘particularly—has resulted from the fact that “the folks back home” seldom preserved the soldiers’ letter envelopes, although the letters themselves were treasured for sentimental reasons. When an army takes over a section, or occupies a place—whether a city or an entire country—postmarks are necessary. Thus the Chinese Boxer Rebellion of 1901 resulted in several postmarks, now sought after eagerly. This article pictures three types, from Japan, Russia, Germany. Thus, also, when the Ger- man armies occupied such countries as Bel- gium or Rumania, special postmarks were again essential to mark and cancel mail from the armies of occupation. The postmarks of the Teutonic World War armies are quite fascinating, and numerous in types. This is because special postmarks were provided for various services on the march or in stations. The guard, the infantry, the cavalry, and other sections of the army had their own distinctive markings. The headquarters of the High Command also had [Continued on page 140]

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y John Edwin Hogg E NE of the most interesting and useful ` of weather instruments is the dry and wet bulb thermometer. It is the only type of thermometer which means anything to those who realize the vast importance of temperatures and their relationship to dryness and humidity. In the middle- West, for example, summer heat becomes almost unbearable above 90 degrees (F) with the intense humidity that follows a thunderstorm, while a temperature of 120 degrees causes little discomfort in the bone-dry atmosphere of Death Valley. The old superstition that thunder causes ' milk to sour was born of failure to recog- WET AND DRY BUL TH Ё R M 0 ‘BASE OF. ALUMINUM FOR METER; nize that thunderstorms — not the thunder itself—usually brings the condition of tem- perature and humidity that actually does sour the milk. Temperatures are one thing and temperatures with relation to dryness and humidity are quite another. Thus the read- ings of the dry and wet bulb thermometer make a world of difference to the rangers who are fighting a forest fire, to the farmer, the shipper of perishable goods, the retail grocer, the photographer and anyone else who may have a greater interest in the sub- ject than his own physical comfort. Before starting construction, obtain two thermometers having similar readings. The glass tube to hold the water can be purchased [Continued on page 143]

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A- total. of twelve pounds of wire; is ~ required for both coils. The primary uses six pounds of No. 12 single cotton covered en- : amel, and the sec- ondary six pounds of No. 10 wire of the same type. Several thicknesses of paper are held to the core with a piece of friction tape. Note strips of gauze, which facilitate removal of the core. “Mechanix Illustrated” Left—Tap each layer of wire neatly in place with a rubber or wood mallet. Right—By tapping the end of the tapered wood core on a hard surface, coil will slide off easily. Ends of gauze etrips are tied to hold windings intact. ROM an examination of the design of the MI Are Welder you will see that its prin- cipal features are simplicity of construction and low cost, but you will have to hold the electrode in your hand and give it an actual trial in order to realize the amount of sizzling, crackling heat it will generate. The cost of building a welding transformer is in close ratio to the amount of current it will deliver without overheating. For ex- ample, you would need about 36 pounds of wire for one rated at 2,500 watts, and only 12 pounds of wire for one of one-third that ca- pacity. When the former is used for light work, a reactance coil is needed to reduce the amount of current. Having in mind the needs . 88 of the man in the home workshop, the M I Arc Welder was designed exclusively for light work. It consumes less than 1,000 watts and therefore can be plugged into almost any 110-volt a.c. socket. It does not require the further expense of an auxiliary reactance coil. In addition to doing light welding, it is ex- cellent for quickly soldering large work. The voltage is low so that even a child cannot re- ceive the slightest shock. Finally, unlike outfits of larger capacity, it may be used con- tinuously without overheating; ordinarily it will barely become warm. For the primary and secondary coils of the transformer you will need a full 6 pounds each of No. 10 and No. 12 S. C. E. (single Mechanix Illustrated—June, 1938

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Left— Covering. the coil with cotton, gauze: The ‘outside of each coil then is coated with white shellac. -Right— The three wires. from each ehd of the secon- dary ‘are soldered ‘to the heavy. electrode. . and ground cables. ARG WELDER cotton enamel) magnet wire. by Kenneth Murray с Ще The primary coil consists of я of 300 turns of the No. 12 wire and when in place over the iron core of the transformer it is connected directly to the 110-volt, 60-cycle alternat- ing current line. The sec- ondary coil consists of three coils of 60 turns each of No. 10 wire, which are wound one over the other and the ends of each then connected in parallel. This delivers the heavy current necessary for welding. The winding form consists of a 12-inch length of wood that is 24% inches square. Taper it slightly towards one end, so that the finished coils can be slipped off easily. Then sand it smooth and ap- ply a coating or two of wax. In order to confine the coils to a width of 4 inches you will need two 5-x5-inch squares of wood, one of which is screwed to the larger end of the form. Cut a 2%-inch square hole in the center of the other and slip it over the form so that it is 4 inches from the first, then wedge or screw it tightly in place. Cover that part of the form between the squares with a thickness of waxed paper, then lay a 15-inch length of 2-inch cotton gauze bandage tape lengthwise of each of the four sides of the form. The ends can be held out of the way formerly Modern Mechanix

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Top—Building three sides of the core. When this step is completed, the closed end is bolted between the angle-iron supporting pieces. Above—To make a tight fit, the iron core is partially covered with friction tape before slipping the coils in place. with thumb tacks; their purpose, when the ends are later tied together, is to hold the turns of the completed coil in place. Three turns of 4-inch wide heavy wrapping paper are then wound in place and held with a strip of friction tape. If you have a lathe, the form can be set up as shown, otherwise drill a hole in one end and slip it over the end of piece of pipe or metal rod that is firmly fixed, so that it turns easily. Start with the primary coil by passing about 6 inches of the No. 12 wire through a hole drilled next to the form in one of the wood squares; then turn the form slowly while winding the wire in place neatly. Tap it at the corners to assure a neat bend. The space available will allow about 40 turns per layer if they are wound tightly together. Give the first layer a coat of white shellac, cover it with one thickness of heavy wrapping paper, and continue with the next. Seven-and-a-half 90 FIRST LAYER OF | IRON LAMINATIONS AFTER COILS ARE IN PLACE, WEAVE IN REMAIN! 2"X 5" PIECES The remaining pieces of iron are woven into the open end of the core and then bolted between the two angle-iron supporting pieces, as shown above. layers’ will be required for the 300 turns. Then bring the end of the wire out alongside the beginning. Tie the ends of the four cot- ton tapes together tightly, remove the loose wood square and jolt the end of the form lightly. The coil will slide off evenly. The secondary is wound in a similar man- ner, but in three coils of 60 turns each. Be- cause the space will allow only 30 turns of No. 10 wire per layer, each 60-turn coil con- sists of two layers of 30 turns each, the ends of all three issuing at one side. When the

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windings are completed, bind the lead wires of each tightly in place with friction tape so that they cannot become loosened, then re- move the gauze ties one by one while wrap- ping each coil tightly with fresh gauze from the roll. Coat them inside and out with white shellac. A 6-foot or longer No. 14 extension cord should be soldered to the two leads from the primary, insulating them well with friction tape. The six wires from the secondary will have to be separated into two groups of three each so that the three coils are in parallel, as shown in the drawing. To each solder a 6- foot length of No. 5 rubber-covered welding cable, one of which will later terminate at the welding electrode and the other at the ground connection. Ordinary stove iron is used for the core because it is less expensive and more gener- ally obtainable than regular transformer steel, You will need about 150 pieces 2-x5- inch, and 150 pieces 2x64 inches, which should make a pile 4 inches high of each size WIND ALL SECONDARY COILS IN SAME DIRECTION Above — The wiring diagram of the arc welder. Upper right —Details of the carbon-hold. ing electrode, and the ground connection which is connected to the work. Right—The com- pleted unit is mounted to a piece of heavy plywood. when they are tightly compressed. In order to bolt the laminated core together and sup- port it, make four angle-iron legs 915 inches long with a 2-inch foot turned at right angles to an end of each for bolting to an 8x10-inch plywood base 1 inch thick. Drill holes 7% inches apart in each leg to take 214 inches by %-inch machine bolts. The drawing and the photograph shows how the pieces of stove iron are made into the transformer core. One leg with friction- taped bolts is placed on the plywood base and the laminations piled on it so that when three sides of the core are completed all that you have to do is to slip the other leg over the bolts and draw them up tightly. When laminating the core, make sure that the edges of the different pieces of iron do not overlap each other. You can then carefully tip the par- tially-completed core on end and wrap the two upright portions with sufficient friction tape so that the coils will fit over them tightly. The remaining half of the shorter pieces of [Continued on page 141] CUN ШШ UU IO V. 60 C. A. C. WELDING CABLES SOLDER LEADS TO CABLES

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USES FOR by Raymond B. Wailes Sodium silicate solu- tion has many com- mon uses, several of which are shown in _ Ete these photographs. _ Diluted with three | parts of water and - applied with a wide brush for speed © (above), water glas | solution can be used to waterproof ce- | ment walls. Several -coats should be Qo applied, aliowing | | enough time between - coats for the solution to dry thoroughly. ^ A half-teaspoonful of water glass. added to the water in laundry tubs will increase the amount of suds and soften water, effect- ing a saving in soap (above). eo water glass and whiting is excellen? cracked ceramics (above). Water glass nite shattered glass objects. Applied with a broom (above), a dilute solution of water glass - and three parts of water makes an ideal treatment for cellar workshop floors, eliminating the carrying of concrete-dust footprints to other parts of the building. The solution can also be applied just as effectively with a small stiff brush. Many grease spots that cannot be removed with ordinary cleaners can be removed by applying water glass to the spot and rubbing vigorously with a clean rag (above). 92

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- Glass tubes ; bé f hid in metal dir (above) by using a cement made of water glass. and whiting. H a cement me resistant to acid is desired, prepare cem The. adhesive e ote water iioi is A. їп the а above. ‘The cardboard flap was coated with water glass and held against the building where it stuck immediately. The solution fireproofs materials somewhat. Apply it to amateur stage scenery. Applied without айишїїпа, water. glass can be used to Ў cement rubber matting to an automobile running board.

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This photograph of Patty just before launch- ing shows clearly her trim lines. Her light weight makes it easy to put her in or take her out of the water when the sail is over. by J. Julius Fanta O END of service can be derived from this snappy skiff, Patty, an ideal project for the home workshop. Constructed during leisure hours, this craft with many purposes will be ready when the "sailing bug" comes around again. Patty is eight and one-half feet long, roomy enough for four persons without crowding and is rowed as easily as a canoe is paddled. Patty makes an ideal dinghy, or tender, for a small yacht—sail or power—as she is feather-weight for hoisting and compact for stowing on deck. Propelled by a light out- board motor attached to the transom, she is a fast job. On fishing trips, this type and size is just the thing for hauling atop the car or on a two-wheel trailer. In fact, this flat-bottomed skiff with lap-strake construc- tion is adapted to serve your every need. Safe in rough water, Patty rides waves like a cork without shipping water. The lap- strake planking method makes the "skin" durable and stays leakage. Planks are fas- tened with clout nails. If a sailing dinghy is preferred, it is a relatively simple matter to install a centerboard, or a detachable fin. 94 Inexpensive and easy to build, this small sailing skiff will give many hours of enjoyment to its owner. The fact that the mold frames serve as the actual frames of this boat saves much time and effort in construction. Additional ribs to stiffen the hull are put in later. To begin with, make the keel out of 1%4"x3” white oak 7 ft., 844” long. Cut the stem piece out of 1144” white oak to the shape shown in the accompanying sketch, and rab- bet accordingly. Notch the stem and splice; water-proof the notches with marine Mechanix Illustrated—June, 1938

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e- e" SPA 30" FRAME | gTATION 9 g e V A \ T glue and bolt the joint with 38"x3" carriage bolts. То the top of the keel fasten a le"x4" oak keelson with 14%” No. 8 flat-head galvanized or brass screws. For best results make a full-sized paper pattern of the stem as well as of the three frames, transom and knees. Reproduce the half-breadth drawings to full size on paper. Frames are of 34"xl!4" white oak. Fasten frames joints with 144” screws, leaving the formerly Modern Mechanix A 2 E € г 2A s quay seat a є sueca | msER c ' PAC AAA If Patty is to be taken from the water often, round the end of the skeg to prevent it from catching on the edge of the dock. corners clear for notching out for chines. The 3$"xl'4" white oak chines should fit flush. Brace the tops of the frames with temporary cross-pieces until the hull is planked. Square and line up the frarnes at their given stations, holding them with C-clamps until fastened with 21⁄4” flat-head serews to 95

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3/8" x 3" i Tree Y SECTION THROUGH STEM AND DETAIL OF b JOINT SLOT FOR STEM 1" М. ОАК MORTISE FOR SHEER CLAMP DETAIL OF OAK BREAST HOOK FIT WITH PATTERN FRAMING ASSEMBLY READY FOR PLANKING At the right is shown Patty ready for planking. The transom is secured in position by 2-inch flat-head brass screws. MORTISE CHINE INTO TRANSOM 96 j = 14 #8 Ғ.Н. GALV. WOODSCREW SECTION THROUGH KEEL & KEELSON the keelson. Bevel the keel and keelson to the correct angle of the transom, then screw the transom into position. Use 2" flat-head screws, counter-sinking them and covering the heads with plastic wood. At the inter-section, brace the transom with a knee of 1" white oak, made as shown. A cardboard pattern will help to get a perfect fit. The breast-hook and transom knees are of 1” white oak. Mortise each piece 58” for the sheer clamps. These clamps are of 59”x14” white oak screwed or riveted to the insides of frames and to the mortised breast-hook and knees. P If not done before, notch the frames for the chines. Middle clamps which serve as seat risers, or stringers, are fastened to the insides of frames. Seat risers are of the same stock as other clamps. Now steambent ribs of 5$"x1" white oak should be spaced evenly between the frames. Soften the ribs for bending by boiling them in a long water-filled iron pipe, six Ne MORTISE FOR SHEER n 7^ CLAMP ON TWO x 4 ОЕ ТНЕ КМЕЕЅ / Ke 6" FIT WITH MORTISE TO FLUSH FIT AT FRAMES | |] | АТ] = I" GALV. WOODSCREWS OPTIONAL FRAME JOINT

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inches in diameter, capped at one end. Here is Patty still in the P x : workshop but almost Prop the open end with bricks and build completed, Screws are used to fasten the planks to the stem and transom. a hot fire under it. Handling the ribs with hot-pads, fasten them with screws to the top of the keelson and to the outsides of clamps. Use C-clamps to hold the ribs, eight of which are sufficient. Now for the planking. Use %”х6%” cedar for this. First lay the garboards, or the planks next to the keel, coating the edges with white lead or marine glue. It is well to lay a strip of caulking cotton between the overlap the keelson and gar- boards. Use 34” flat head screws to fasten garboards to the keelson, stem and tran- som. Use 1%” copper clout nails for the BOLT THRU KEELSON rest of the planking, except when stipu- ,, lated otherwise. To clinch the nails, алан | hold an iron block inside while ham- CURVE f mering. Planks overlap each other 1”. The ends must be scarphed, tapering a foot, as shown, so that they fit flush at the stem and transom. Make sure that all over- lapping edges are well-coated with water- BUILD UP FROM V2" X 6" PINE - FRONT SEAT SIMILAR ORDER OF PLANKING A 1/2" X 6" CEDAR 3/4" PINE SEAT SCARPH TO FLUSH FIT E NOTCH FOR · } SEAT RISER y 14 GALV. THE COMPLETED HULL . SHOWING THE SEAT ARRANGEMENT AND OTHER DETAIL proofing before clamping each plank in place. Before laying outside planks of the bottom, start the side planking, working up from the 97

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10'-0“ LONG TO sTEP OUTBOARD PROFILE WING SAILING RIG IE: ANY STANDARD TYPE - RBOARD MAY BE SUB- 1 UTE ‘OR FIN SHOW! 22222225 3 DETACHABLE FIN chine. The bottom edge of the first side plank should be flush with the chine. Clout nails should be used only for securing to the ribs, frames and chines, while the ends should be fastened with screws to the stem and transom. With the side planking on, finish the bot- tom. Trim the over-hanging edges after fastening the inside edges of the last bottom planks with nails and the outside edges to the side planks with screws. Saw off the excess with a key-hole saw and plane flush. Screw a 1” half-round, white oak, along BRASS OR GALV. IRON CHAFING PLATE 7] DRILL 5/8" DIAMETER ORILL FOR SCREWS COUNTERSINK HEADS MAKE 4 OARLOCKS THUS OF [3/4" x 7" w.OAH SCREW TO THWARTS I2" AFT OF FORWARD & CENTER SEAT the gunwhales to provide a fender strake. Keep the hull inverted to put on the 1"x5" white oak skeg which runs the full-length of the bottom. Drill 44” holes through the 98 Беа The rudder and tiller are | cut from 3⁄4 inch oak stock. hinges consist of inter- locking screweyes. fin becomes necessary only when a sail is used. 3x 2£ scor- cur SLIGHTLY LE UNDERSIZE ON LENGTH A i 2 2, DOWEL LEE TAPER WIDTH 22 TOWARDS END TAPER i6 TO SUIT RUDDER & TILLER CUT FROM 3/4" WHITEOAK BEVEL EDGES BELOW LWL. TO SUIT-GRAIN-LOCK ON LOWER EDGE IS OPTIONAL, 3/8" DOWELS 77 7 Vip UME SECTION THRU FIN SHOWING CUTWATER END 15" 1/8" X 6" IRON STRAPS BOLT OR SCREW ` TO SKEG BOLT OR RIVET Ee white The rudder //7 Sa AK Uf The if DETAIL BOTH ENDS OF FIN AS DESIRED skeg and keel, and use carriage bolts of necessary lengths to hold it. Bolt-heads should be countersunk and covered with putty. Seat supports of 34”x1%” stock are notched at the ends to fit the seat risers, to which they are screwed. Boards for the forward and stern seats are l5"x6" pine, running fore [Continued on page 138] Mechanix Illustrated—June, 1938

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by Martin Gardner GREAT many interesting and enter- LA taining tricks can be performed with ordinary bottles, and some of the tricks afford excellent illustrations of various laws of physics. For example—the next time you purchase a cold bottled drink, pour the liquid into a glass and try this experiment with the empty bottle. Place a dime over the opening and moisten it around the edges to make the bottle air tight. Do this by dipping your finger in some water and allowing a few drops to fall from the finger tip to the edges of the coin. In a few moments the dime, apparently of its own accord, will begin to click up and down at regular intervals! This is because the cold air inside the bottle is beginning to warm. When air is heated it expands, so the expanding air forces its way out past the edge of the coin. You can speed the motion of the dime by placing your hands around the bottle. The heat from your hands warms the air inside more rapidly. The same experiment can be per- formed at home by placing an empty bottle in the ice box for a short time before you begin. MILK BOTTLE-EGG TRICK A somewhat similar type of trick makes use of an empty milk bottle and a hard boiled egg from which the shell has been removed. Place the egg on the opening of the bottle and challenge anyone to make the egg pass through the neck to the inside. It is [Continued on page 134] formerly Modern Mechanix COIN CLICKING ON BOTTLE TOP (2 № SHELLED HARD- 1 BOILED EGG | LABEL SET INSIDE BOTTLE BOTTLE FILLED WITH WATER LIFTING BOTTLE WITH STRAW

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GO OVER BOAT WITH KNIFE “TG . TO DETERMINE ROT UNDER PAINT . REMOVE || SCARS IN Ù MOLDING b REMOVE rd Й ROTTEN PLACES i IN THE STEM .GRAVING PIECES = Т BOAT COVERS SHOULD BE AIRED AND CLEANED BEFORE STOWING EXAMINE FOR BRO < RAILS AND GUARD CLEAN OUT GREASE AND OILS AROUND Dx, AND UNDER MOTOR .RE- PAINT WITH \ WHITE LEAD TINTED OPEN ALL WINDOWS AND CABIN PORTS TO AIR OUT BOAT IF CANVAS IS BAD OVERALL,RENEW. LAY NEW CANVAS IN MIXTURE OF WHITE LEAD AND VARNISH OR LIQUID "NS ; MARINE GLUE D ze “4 BAD SPOT CAN BE PATCHED IN NEAT SQUARE LAID IN PAINT OR GLUE. TACK THE EDGES.

SHEET LEAD OR COPPER PATCH AS A LAST RESORT CAULKING SPLINE ^ FIXING A BAD SEAM

RENEWING A PIECE OF PLANKING HE SPRING OVERHAUL | by Sam Rabl ITH the advent of the first housefly, or the song of the first robin, those of us who own a boat begin to get itchy fingers and soon saunter down to the boat yard “just to look her over.” A casual inspection will reveal enough to get started on but with the beginning of every season the inspection of any boat should not be “casual.” There is a set system of ex- amination that those who have owned a boat for a number of years have found to be the best and that in the long run will cut the time in- volved in the overhaul to a minimum. The first looking-over should be for the dis- covery of any defects. The old timer will get out his pocket knife and start poking into the wood to discover any “soft spots” hidden under the paint. Paint has a bad habit of hiding the effects of rot, and the seasoned boat owner knows just where to expect to find this menace if it is present. He will start poking the planking at the rabbet in the stem and follow its line from the top to the point where it joins the keel. Should the knife enter very easily at any point, he will start digging away the paint to discover the reason. Let us assume for example that a bad spot does exist. The rotten wood must be removed and graving pieces or “dutchmen” se- curely fitted so that the strength of the little ship is not impaired. If many rotten areas are found, the entire member should be replaced. Around the transom and along the keel are other likely places to look for rot. Exainination should be made also for damaged timbers due Mechanix Illustrated—June, 1938

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SCRAPE WELL WITH REMOVE OLD PAINT WITH TEND OVER AT LEAST BH REPAIRING -BROKEN FRAME possibly to that hard knock the boat got against the dock last year. Where a plank is badly scarred it would be well to renew the affected length. Any renewed plank should extend over three frames at least, and should be cut at the center of the space between the frames so that butt blocks may be fitted. Never splice in a new plank depending on the frames alone to cover the joint. This is some- times done in some cheaply constructed boats. Where frames have been broken, a length of new frame should be bent in alongside of the damaged ones so that it will cover at least three planks each side of the break. It should be securely fastened to both the broken frame and to the planking. Worn and scarred places on the rails and guards should be renewed by fitting an entire new piece, or by graving pieces. After all of the bad places in the hull have been re- paired, another thorough going over should be given the hull. In the meantime, if she had a winter cover, this should be given a thorough airing and drying before it is stowed away for the next lay-up. All of the win- dows or cabin ports should be propped open to air the inside of the boat. The interior around the bilge should be given a thorough scrubbing and cleaning and all old oil and grease removed from the interior below the motor. Grease and oil, besides appearing messy, create a fire hazard. After the bilges have been cleaned they may be painted with a good white lead paint, tinted gray. They may also be given a coat formerly Modern Mechanix RENEW TRANSOM PLANKS WHERE DAMAGED-EXAM- INE WELL ALONG KEEL ON THE BOAT 144" MASONITE TOP SECTION THROUGH EDGE OF WEATHERPROOF COMPANION HATCH 178" SAW CUT. 1410" Х 1-174" BRASS SCREWED TO SLIDE 3/4" MAHOGANY SLIDE of pine tar oil or creosote, both of which are somewhat smelly; or they may be given a coat of whitewash which will give the boat a sweet and clean odor and which will in a great measure protect it from dry rot. A strong solution of salt water in all the dark places will also be a good preservative from rot. The decks and cabin top should now be gone over and any bad places repaired. If the canvas is worn and cracked in many places the best thing to do is to renew it. All the moldings should be removed and the old canvas torn off. The new canvas is laid in a mixture of white lead and varnish or in liquid marine glue, made especially for this purpose. A good trick after laying canvas is to prime it with a thin coat of casein glue, which when set can be sanded to a very smooth surface. If the canvas is bad only in spots these can be repaired with neat squares of new canvas laid in paint or glue and their edges neatly tacked. Another good trick is to apply hard 101

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A COMMERCIAL PAINT AND VARNISH SCRAPER REMOVABLE BLADES marine glue (which is sold for canoe re- pairs) around the edges and iron this down to a thin edge. Leaks around the skylights or ports should be repaired with seam putty or stick marine glue. Another way to stop a deck leak is to apply some of the new elastic cement made for this purpose. This new type of cement, when applied, runs like water but finally hardens into a rubbery substance which is truly eternally elastic, resisting the twisting of the hull without ever breaking loose and leaking again. With the hull in tip-top condition, and if time is available, give some thought to improvements before starting to paint. For instance, it might be well to renew her old painted moldings with new ones of ma- hogany or oak to give her a more snappy appearance. Nothing sets a boat off more than a little varnished wood or “bright- work,” as a yachtsman would call it. We might want to make a more weatherproof companion slide or to fit a hatch forward in the cabin that may be hinged to give better ventilation and give access to the bow without going over the cabin top, which is a hazardous undertaking in rough weather. Time and the condition of your pocketbook will decide just how much of the work will come under the heading of im- provements. Now for the painting. The one best rule in any kind of paint work is: “Start from the top and work down.” First of all, no paint work should be started, other than priming coats, until all the dirty work on the hull and motor is complete. Then start with the re- moval of any of the cracked and blistered paint. There are any number of good paint removers of the paste or liquid type on the market, but most of the old timers around the waterfront still prefer to remove their paint with a blow torch and a putty knife. This of course will introduce a fire hazard to the novice. With all the old paint removed, the bright work should be gone over, removing 102 REMOVE BOLTS FROM COUPLING ~INSERT 3 BRASS SHIMS TO үк REVOLVE COUPLING ———»7[o WHEN TESTING TEST STRIP CHECKING ALIGNMENT OF MOTOR AND PROPELLER SHAFT IF OUT OF LINE, MOTOR MUST BE RESET TO CORRECT RN im = SCRUB SAILS AND HANG TO DRY. IF BADLY MILDEWEO MA DD DYED IN UE CHECK OVER NEGLECTED DOCK LINES AND MOORING ROPES. RENEW IF ,. IN BAD CONDITION the old varnish with a liquid remover, and finishing up with a cabinet scraper or a piece of broken glass. There are some very handy little scrapers on the market which are easily sharpened and do a much better job than any piece of glass will do. The bare wood of the bright work should then be given a coat of linseed oil, and if a darker color is desired the oil should have a little oil stain mixed in with it. After the oiling, it is sanded down smooth and the first coat of varnish applied. Cheap varnish is worse than useless. To pre- serve the finish, buy the best varnish that you can afford. The new bakelite resin types are excellent for boat work. All bright work should be given at least four coats, which should be thoroughly sanded with fine sand- paper after each coat. No varnishing should be done on a damp day or when dust is flying. [Continued on page 145] Mechanix Illustrated—June, 1938

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LD automobile bumpers can be used to make neat and modern appearing shelf brackets. For the shelf shown above, # by 2-inch iron is used for the rear members, to which are fastened the curved bumpers.— R. L. Kunau. Wheels Protect Rear Of Car Rp E HEN present day low slung cars go up or down steep driveways, the edge of the bumper often strikes the ground. If two small rubber tired casters are fastened to the bot- tom of the bumper as shown in the above pho- tograph, this problem will be eliminated.— Fred Parks. formerly Modern Mechanix Flat Pack Holds Auto Tools OW to keep the auto tools handy, clean and quiet usually is a problem to the average motorist. However, the flat tool kit Shown above becomes an easy solution. Two pieces of three-eighths-inch plywood, nine by twelve inches, are required. The tools to be contained in it are placed on one of the boards and an outline of each is drawn. The outline then is cut on a jig saw. The other board is fastened to the cut out piece with small nails. The tools are held in place by small wire clips.—Arnold S. Lutes. Nail Polish Aids Windshield коныр HEN safety glass windshields are cracked, the air enters between the two pieces and the pane often clouds over or be- comes opaque. If a small quantity of ordinary nail polish is flowed into the crack when this first happens, no air or moisture will enter and the windshield will not change in appear- ance.—W. C. Wilhite. 103

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CHEMISTRY MICRO- SCOPE SLIDES ттт ETT A washing bottle is a very convenient aid for specimen preparation. Note the small spring on the end of the short tube. It prevents the specimen from clogging the outlet. by Julian D. Corrington, Ph.D. N ORDER to get living materials into the form of permanently mounted microscope slides, many steps must be used—some chem- ical, others mechanical. Collectively, these processes constitute the. science of micro- technique, and they fall into five principal groups—fixing, sectioning, staining, clearing and mounting. Last month we detailed the methods and steps in sectioning; this chapter gives information on fixing, and the whole will be completed next month when the re- maining three steps will be considered. Fixing is a general term to include a num- 104 Above are shown typical materials used for processing microscope specimens. The glassware is quite inexpensive. ber of stages that are actually separate, but are customarily lumped together as a single operation because they are done with a single chemical and as one job. The first accom- plishment in fixing is that of kil "ng, which in microscopy refers to the ling substance within cells and tissues rather than to the animal or plant as a whole. It must be done quickly, to prevent post-mortem changes. Secondly, fixing performs a poisoning that will prevent attacks by bacteria or fungi which would otherwise cause decay; it im- pregnates the tissue with metals and pre- serves them permanently. Lastly, the material is hardened so that it cuts better, and prepared to take certain dyes. One of the best single reagents for fixing is 10% formalin, made by adding ten volumes of water to one of commercial formalin. A better one for most purposes, however, is formol-acetic alcohol, the formula for which is: 5 ec. full strength commercial formalin, 5 cc. glacial acetic acid and 90 ce. of 50% alcohol. This can be made up at-any drug store, but if one is to do any serious work in miscroscopy he must learn to prepare his own reagents, so we will go into the matter briefly of how such solutions are concocted. In all technical work the unit of weight is the gram, abbreviated g., and of fluid meas- urement the cubic centimeter, ce., also termed milliliter, ml. These are equivalent, one gram of water measuring one ce. Formulas are figured on a basis of 100% equal 100 cc., hence percentages indicate the number of ce. or ‘g. If larger amounts are desired, multiply all Mechanix Illustrated—June, 1938

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An improperly fixed specimen of a lilac leaf. This appears mushy and some details are eliminated entirely. volumes by two, three or any other desired amount of increase. Solids must be weighed, involving the use of a precision type of scales known as a chemical balance. A very fine and expensive instrument is not needed in general micro- scopy, but only one that will weigh out as small a quantity as a single gram. For measuring fluids the apparatus is simpler: one or more graduated cylinders. If only one is purchased, get the 100 cc. ca- pacity; if two—and it is better to have a large and a small—secure one of 25 and one of 250 ec. The cost averages around sixty-five cents each. Balances, cylinders, beakers, watch glasses, chemicals and many other materials needed in this work may be purchased from any of a great many scientific supply houses, and: from local dealers in the larger cities. We are now prepared to measure out every- thing in the foregoing formula except the alcohol. The making up of various per- centages of this important reagent has to be done constantly and so to this step we now direct our attention. Full strength commercial alcohol is 95% in purity; that is 95% alcohol and 5% water and it is this mixture that must be diluted in making up lower percentages. In our present example we need 5095 alcohol How does one obtain a 5095 mixture from one of 9595? Sounds like a problem in arithmetic, but the procedure is really simple. Since 50 is the strength wanted and 95 the percentage to be diluted, subtract 50 from 95 to find the propor- tion of water to be added. Hence 45 parts water plus 50 parts 95% alcohol will yield 95 volumes of 50% alcohol. In actual usage this is automatically ac- formerly Modern Mechanix e 1 However, when directions for this important step in microscope technique are followed, slides of striking clarity and detail are obtained. Here is an example of a properly fixed specimen. It shows an infinite amount of detail under microscope. complished by filling a graduated cylinder with 95% alcohol up to the same number as the required percentage (50 in this case) and then with water to the 95 cc. mark. To make 70% alcohol, pour in full strength alco- hol up to the 70 ce. level, then add water to bring the whole to the 95 ec. mark. Water used in making up fixtures may be tap water, whereas that taken for compounding staining solutions should be distilled. Different writers on microtechnique em- ploy a series of alcohols varying according to individual preferences, but we recommend that you make up 95 cc. each of 35, 50, 70 and 85 percentages. Pure grain (ethyl) alcohol is preferable but difficult to obtain. Wood (methyl) alcohol serves nearly as well but is extremely poisonous and must be handled with care; hence it is not recommended for inexperienced workers. Denatured alcohol, the kind most readily procurable, is ethyl alcohol to which small amounts of some poisonous substance, such as pyridine or methyl alcohol, have been added to make the mixture unfit for internal consumption. There are many denaturing formulas, some better than others for microscopy. Try to get formula No. 1 if possible. Thus: far, we have made up our formol- acetic alcohol fixer; now how to use it? We need some suitable glassware, and our title illustration gives an idea of the variety avail- able. A small, straight-sided glass called a tall Stender dish is one of the best, obtainable from a supply house. Most five and ten cent Stores carry a similar small glass; those in which cheeses for sandwich spreads are now sold are perfect for this purpose, and any [Continued on page 143] 105

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SS TEP-UP -by Dale R. Van Horn UPHOLSTERED HINGED TOP TURNED DOWN FOR USE AS A STEPLADDER WHITE PINE OR 3/4” PLYWOOD SIDE VIEW FRONT VIEW TA DOWEL OUR boards and four dowels form this smart kitchen adjunct. Anyone with no other tools than a saw, square, brace and bit and screwdriver can make it. Four 1-inch maple dowels, 23% inches long, are required. You will also need four white pine boards, each 12% inches long and of the following widths: ‘two 6% inches wide, one 9 inches wide, and one 11%4 inches wide. Bevel the two ad- joining edges of the two top pieces, allow- ing for the hinge pins and the upholstery cloth thickness. Pad the hinged piece with batting, and over this lay a piece of heavy cloth 615 inches wide by 1215 inches long. Over all this lay the piece to be used for the covering. Fold all four edges over and tack to the under side. Hinge the two pieces together after the 1-inch holes have been bored in the under side of the top %-inch deep. Bore 1-inch holes through the corners of the other two steps—those at the back corners being put through vertically while those in the front corners are bored at an angle easily determined by laying the step-up on its side on the bench and tracing angle lines on the edges of the steps. The tops of the dowels are glued in place, but all other step-and-dowel unions are joined by driving 8-penny finish or casing nails through the edges of the step, through the dowel itself and into the inner portion of the step. Be- cause maple is quite hard, holes slightly smaller than the nails to be used should first be bored through the dowels at the correct places. For a finish, the edges of the steps can be painted Chinese red and ‘the rest painted ivory. The dowels are also given the red trim coat. Mechanix Illustrated—J une, 1938

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PORTABLE desk constructed of materials usually found in the average home will be useful for the man of the house as well as for children attending school who have home work to do. An orange crate is partitioned to hold a portable type- writer, reference books, stationery and miscellaneous papers. A cigar box divided off inside, and with a pull knob, is a handy drawer for rubber bands, paper clips, stamps and other small odds and ends. A tin can fastened under one of the shelves will hold pencils and fountain pen. A short length of rubber hose makes a convenient handle for carry- ing the box where ever work is to be done. A board across the arms of a rocking chair will make an excellent desk. The board can be fitted with pegs on its under side to prevent it from slipping on the arms while ORANGE CRATE = by . Bertram . Brownold | PORCH OFFICE in use. The same board strapped across the front of the crate becomes a cover and prevents anything in the box from falling out while being carried. Any number of partitions or sections can be built into the box, depending on the requirements of the user. For the man who occasionally has office work to do at home, this portable desk will be very useful. Many times it is not convenient to work in some particular room in the house because of visitors or for some other reason. At this time, the “office” can be picked up and taken to some other loca- tion. During warm weather, many persons would like to work outside if it were not so much trouble to take all the necessary material outside. With everything necessary in one box, any desired location immediately can become a private office. A little sandpapering and a coat or two of paint dresses it up so that it presents a pleasing appearance. formerly Modern Mechanix

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ODERN paints give to the amateur the ability to do a paint job possible in past years only by the skilled craftsman. Manu- facturers and experienced chemists have been working hand in hand to improve finishing materials so that anyone who can wield a paint brush at all can secure results that would astonish the old-time professional decorators. Much of the experience that was formerly required in manipulating the brush is now incorporated in the paint itself. This is par- ticularly true in the case of interior finishes such as enamels and varnishes. А great many of them are “self-leveling,” which to the layman means that brush marks left by an awkward hand will automatically be leveled out of sight. Most of them will dry in four hours or so, which means that home routine need not be disrupted for days at a time as in the past. “What make of finish shall I use?” is not such an important question if it is asked regarding any of the well-known brands. The manufacturer, proud of his product, states on the label in simple language ex- actly what it is intended for and how it is to be used. You can rely on that informa- tion; it has been tested time after time. 108 A simple means of determining if the surface is dry is to sprinkle some salt over a test piece of wood painted at the same time as the original. If the salt brushes off without marring the finish, it is dry. Above—An example of the value of sandpapering. Top strip was not smooth when finish was applied, while bottom section was thoroughly sandpapered. Below—A coat of enamel makes this table look like new.

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However, what about the cost? This good paint, good varnish or enamel, certainly ap- pears to be expensive. A small can of it may cost a dollar or more, while down the street you can get a similar-sized can for a fourth of the money, perhaps with a brush included. Experience is a good, but very costly teacher where paint is concerned. A cheap four-hour enamel may possibly be applied with the same amount of time required to brush on a reliable make. It may dry in four hours, or it may still be tacky a week later, Above (left) —T'o test the quality of enamel ot varnish, coat a small piece of tin. When it is dry, the finish should not crack, peel or check when the tin is bent around a Va inch rod. Above—To make cleaning of the hands easy after the painting is done, rub some vaseline over them before starting to paint. Left—4A small sprayer will give a fine finish tc small articles. Use a spare tire for the compressed air supply according to the luck that the manufacturer had with the compounding of that particular batch. The most disappointing part, how- ever, is its inferiority on the points most de- sirable in a good finish. These are (1) the ability to preserve and protect the surface to which it is applied. (2) Appearance; it should brighten the interior or exterior of a home. Thirdly, it should promote sanitation and be easy to keep clean; finally, a durable. lasting finish meeting the foregoing qualifica- tions should increase the value of the prop- erty. These requirements are obviously not met in a cheap material that quickly becomes dull, fades, may become tacky during humid weather and is liable to peel or crack after a few weeks or months. A good finish is one that dries hard, yet re- tains enough flexibility and elasticity so that it will not check when the surface to which it is applied expands and contracts due to temperature changes. To make a good com- parative test, coat a small strip of tin with the paint, varnish or enamel and allow it to dry well. It should not check or show the least sign of stress when the strip is bent around a 44-inch rod (such as the shank of a drill bit). Some good grades of enarhel, 100

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(f. when your finger is rubbed over a painted surface, some of the paint rubs off, immediate repainting is necessary. when put to this test, can even be crumpled and pounded and not the least sign of a crack will appear. Perhaps you are wondering just what color or shade would be most suit- able inside or out- side your home. Much depends on whether you wish to brighten up a dark room, or to tone down the bright- ness. Good paint will do either. The “brightness” of a film of paint or enamel indicates the percentage of light that it will reflect. Some time ago an accurate check was made of the reflecting powers of the different colors of pigments used in good quality finishes, and it is quoted here to aid you in controlling the brightness range of a room you intend partially or entirely redecorating. The figures refer to the per- centage of light reflected: Always start painting a house on the north side. Work around so that the sun remains ahead. Good white paint ....8496 Pearl gray ........... 1296 Light green codice etie entend 10% = 110 ВиЁ. .............. 55% Pale sea green ........ 54% Aluminum ..41% Medium : Бгау ........ 38% Battleship gray .......... 20% Dark chrome green 11% Dark red ...1095 Black .............. 2% Good house paints consist es- sentially of a decorative and After the paint has been mixed with a paddle, it should ; be “boxed” sev- eral times, that is, poured from one container into an- other several times. Mechanix Illustrated—June, 1938

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protective pigment suspended in a drying oil, which serves as a binder, with a thinner and other ingredients added to suit the type of work to be covered. Ordinarily the pigments consist of zinc oxide and The proper method of applying paint is as follows: Dip the end of the brush into the paint; slap it lightly against the side of the pail, and give the brush a half turn before applying it to the surface. This prevents paint from dripping from the brush. Work it out with the grain, and then across the grain. Finish with light strokes with the grain. white lead, with the addition of a smaller quantity of tinting pigments. On the pro- » portion of zinc and lead depends the suitability of a paint for a given purpose. A paint composed mostly of zinc will have great covering ‘power, because of its greater ability to reflect light, but as it ages it unfortunately becomes brittle and cracks, and can easily be chipped from the un- protected wood with a finger- nail. On the other hand, a lead-type paint does not have a tendency to peel but it does, When painting sash, it will be easy to remove dabs from the glass if the edge is first coated with whiting-and-water paint. formerly Modern Mechanix on becoming old, dry out into a chalky powder which readily rubs off. These two counter influences are taken advantage of in good quality paints by combining the lead and zine in scientifically correct propor- tions so that each counteracts the deficiency of the other. If the job is one of repainting you will save money by seeing that the old surface is absolutely clean, free of dirt and oil, and in [Continued on page 145] 111

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Truck Inner Tube HE construction of this bel- lows, suitable for shop use, is simple, and the parts are those usually found in the junk box. If the air requirements are not too great, a single unit will be suffi- cient, but if more air is needed a double acting unit can be built. When the dual unit is to be used, the handle is extended to accom- Makes Efficient Shop Bellows

HANDLE & PIVOT д "хт" THIN STRAP IRON 77a WT SPRING г — (STEEL 3 CLAMPS 6" ig xim < ee STRAP 4 4 RUBBER IRON : x " Р; f ‘VALVE TRUCK- 10 DETAIL INNER INTAKE TUBE modate the second bellows at the opposite side of the pivot point. An almost continuous supply of air then is available because one bellows inhales while the other exhales. All the wooden dises are one- inch thick and have a diameter one and one-half inches larger than the inside of the inner tube when it is unstretched. The 3⁄4- inch pipe nipple for the air hose should be smeared with strong glue before it is screwed into a snug fitting hole.—T. L. Moore. Saw Becomes Grooving Tool SAW BLADE i HD

HIS handy tool will save considerable time when making grooves in window frames or screens. It consists of two hard- wood blocks, approximately seven inches long, to accommodate a five-inch compass saw blade. The distance that the saw blade projects above the edge of the strip will de- pend on the depth of the cut desired. Also the guide block’s distance from the saw blade will regulate the distance of the cut from the edge.—M. A. Hall. 112

Burrs Improve Box Wrench ANY times when a box wrench is used on a long shank bolt, the wrench falls below the nut unless held in place. This difficulty can be eliminated by crimping or burning the top edges of the jaws so that the opening at the top is reduced sufficiently to prevent the wrench from falling below the top of the nut. This can be done easily by center punching the edges. This does not in any way reduce the usefulness of the wrench. —4A. M. Chester.

Mechanix Illustrated—June, 1938

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NEW ANGLES FOR THE ANGLER TIN CAN - FRUIT, VEGETABLE OR COFFEE Bait Can Carried On Fisherman's Belt INDING a satisfactory means for carrying bait when fishing amidstream has caused no end of disgust for many fishermen. A simple way to solve the problem is to make a bait can that can be carried on the belt. A tin can with a smooth top provides a suitable container for the purpose. Slot it along the side with a can opener or chisel and spread the slot CAN LID IS ATTACHED TO py Bours тин with a screwdriver to = receive the belt — A. H. Waychoff. 174" PINT SCREW TOP TIN CAN Leader Box Clamps To Fishing Rod N ALUMINUM screw top container, such as used by druggists for salve preparations, makes a con- venient receptacle.for carrying leaders. A tin or copper strip is bolted to the lid of the container so as to permit it to be attached to fishing rod. Jewelry Clasp Aids In Attaching Lures ISHERMEN who find occasion to change their lures often can avoid tying and untying the line each time by using small jewelry clasps. Being inexpensive, they may be permanently attached to each line for use whenever the occasion arises. Tea Strainer Used As Minnow Dipper p CINE L O FACILITATE the removal of live bait from the z , minnow pail, an ordinary five-cent tea strainer is recommended. Ordinarily, it is necessary for the angler to “fish” around in the pail, with his hands, in order to remove one of the elusive minnows. After landing the bait, it is no uncommon occurrence for it to slip through the angler’s wet hand and gain long-sought freedom. Use of the tea strainer will pay for itself over and over again. A 1 gallon paint can with lid perforated with nail holes serves as a convenient and inexpensive live bait ра. —А. H. Waychoff. A § CENT TEA STRAINER Luminous Bobber For Night Fishing NLESS night fishing is done under moonlight, it is next to impossible for the angler to watch the movement of the bobber. With this handicap, it is impossible to “play” the line until a fish has actually “struck.” Embryo or veteran need not be dismayed by darkness. Luminous tacks pushed into the top of the bobber will show its location and movement even on the darkest night.—A. Tempe. formerly Modern Mechanix 113

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тод OC ALE FACTOR CARD ANG R X ANY model airplane enthusiasts would like to know the maximum height at- tained by their little craft. By following the instructions given here anyone can easily make a simple and surprisingly accurate altitude finder. The first step is to lay out a factor scale on stiff cardboard about 8%xl-inch in size. Draw a center line and on each side of it mark off the distances jl, 18, 1⁄4, %, 1, 2 and 4 inches along the edge. Notch these points as shown in the accompanying illustration, and mark them as indicated. Next, obtain a piece of doweling rod about 36 inches long with a 34-inch diameter, and a strip of soft wood %x2x82-inch. Scribe two center lines, lengthwise and across the strip, and where they join bore a hole large enough to let the dowel slide easily through it. Now, lengthwise of the edge of the strip saw a slot about 12-inch deep into which the 114 ARD HOLDER А 3/a"X 2"X 8-2 SCREW EYE FOR CLAMP cardboard scale is inserted, first coating its edge with glue, and then making sure the center line of the scale and the center line of the strip match up. Through the other edge of the wooden strip run a brass screw eye and blunt the point. This will act as a clamp to hold the sight rod in position. To use the finder put your model plane on the ground at any convenient measured dis- tance, say 30 feet. Sight along the rod and move the factor scale to a position where the plane wing-tips just fill the space between points 1-1. Clamp the scale here. When the plane is up in the air, again sight on the wing-tips and note what space they now fill. Suppose they appear to be just wide enough to fill the space between points 8-8. Then 8 is your factor to be multiplied by ground distance, 30 feet, giving 240 feet as the altitude of the plane. The ground dis- tance can be varied to suit, but, remember, always multiply known ground distance by measured scale factor. Mechanix Illustrated—June, 1938

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Operatinsc Two Trains On One Track PUSH CONTACT DISC TO BLOCK ` TO TRANSFORMER UGGESTION of operation of two model locomotives at the same time on the same track oval generally brings visions of com- plicated inter-locking controls, relays, and messy wiring all over the track bed. None of these is necessary with the system shown. Additional wiring is required, but this is carried on dummy telegraph poles. The track is laid off in blocks of three sections each (the distance usually required to bring a train to a complete stop). The third rail of each block is insulated from that of every other block by a fiber pin or a match stick. Each block has its own third rail wire from the control box. Normally, current flows uninterrupted to all blocks, but when a push button in the control box is depressed, the current in the corresponding block will be interrupted and the train will come to a stop in that block. As the train progresses around the oval, its progress will be followed on the control box panel by the flashing of small lights beside the block buttons. The position of a second train will also be indicated by lights. When the lights approach each other too closely, it is necessary only to press a button between lights and stop the following trains. The operation of the follower lights is entirely automatic. The connection of the buzzer coils may excite some curiosity. One is connected in series with the third rail wire to each block, and a follower lamp is connected in parallel formerly Modern Mechanix GLASS BEADS 3 SIMULATE " CIGAR BOX NAILS CONTACT NO.22 DSC W MAGNET T CROSS SECTION 3! а OF CONTROL ВОХ (8 INSULATORS © РАТТЕКМ КОК CONTACT DISC | CENTER OF CONTACT DISC “У $t |—BuzZER COIL Quotation with (across) each “magnet.” marks are placed around the word magnet because the coils are not used as magnets at all, but as impedance coils. Their resistance to passage of alternating current is utilized to provide a small voltage drop, which is suffi- cient to operate a 3.8 volt flashlight bulb. The impedance of each coil is so small (less than one ohm) that no slowing of the train will be noticed. The operation of the train follower is very simple. As the blocks are independent. when there is no locomotive on a block, there will be no current through the buzzer coil and hence no light. As soon as a locomotive enters the block, however, current will be drawn through the corresponding coil and its lamp will light. The other lamps will of course remain dark unless there is a loco- motive on another block, in which case its lamp will light. A little examination will show that the control box is nothing more than a circle of circuit-breaker push buttons. It may be made of wood or any insulating material. An ordinary piece of tin will be sufficiently elastic for the multiple contact disc. Note that [Continued on page 138] 115

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ES The completed set in use. antenna connection. HEN warm weather brings the urge to spend more time outdoors, some radio fans hesitate to build a portable receiver be- cause of the cost and trouble of construction. However, with this set, neither of these prob- lems is of large proportion. The cost of parts is sufficiently low so that almost any experi- menter will find that the pocketbook is not strained very much. When the junk box is brought out and examined for possible parts that can be used, usually the final cost will be reduced to a very few dollars. The actual construction is simple enough so that a single weekend of work will result in a completed set, ready for use wherever its owner wishes to take it. There is nothing tricky or odd about this receiver. It uses new tubes, but these are really *old tubes" with a different type of filament. These tubes are designed for bat- tery service and operate on 1.5 volts, thus permitting the use of a single “A” battery. The space thus conserved means that the set is much more compact and weighs consider- ably less than previous types of portables. The complete set, including everything but 116 The binding post at the left is for the All batteries are in the cabinet. // A” groes pa | == Е 5 HOLE > + 4 Hoc % HOLE p Poo 1615 1t I, HOLES 17 — —- FRONT VIEW lí the parts specified are used, the layout above should be followed. This view is of the front of the all-metal cabinet. „CHASSIS 1 4 ALUMINUM The positions for the holes to be drilled through the metal base are shown above. ca p BRACKETS FOR MOUNTING CONDENSERS The antenna condenser and the regeneration control condenser are mounted to the under side of the base. The bracket for C2 must be insulated from the chassis by means of fibre washers top and bottom. Metal washers should be used with the bracket for C3 so that the chassis rests level. the earphones, is contained in a split metal case 634 inches high, 5 inches wide and 834 inches deep. This case is available at most radio supply stores. The builder may want to use some other type of construction, whereby the earphones can be housed in a small compartment; he will find many other sizes and types of cases available, or he may even go so far as to construct his own case of wood. If so, a metal panel is recommended Mechanix Illustrated—June, 1938

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PORTABLE: =- _ Two tubesgive three-tube per- formance in this easily con- structed porta- ble receiver. This photograph shows the position of the batteries in- side the set. The tuning condenser is mounted on the front of the cabinet, while the other two are mounted below the chassis. The vari- ous small parts—condensers . and resistors-—are supported | by their own wires on the underside of the chassis. to reduce “hand-capacity” effects. A piece of 7” aluminum 5’x414” is used for the sub- panel. The midget condensers C2 and C3 are mounted underneath this aluminum plate. When they are fastened to the front of the case, they serve as a support for one end of the chassis. This makes a very convenient arrangement and it is necessary to employ only a long screw to support the rear of the base plate. The entire r.f. and audio portion is built on this small base. The antenna condenser C2 and the regener- ation condenser C3 are mounted on the under side of the base; so are the two tube sockets. The coil socket is mounted on top. This ar- rangement is absolutely necessary because the three sockets are so close together that they would interfere with each other if they were all mounted on the top of the chassis. Place small washers between the under- side of the chassis and the tops of the tube sockets, to prevent the rivets on the latter from “shorting” against the aluminum. Raise the coil socket about 34” above the chassis by small collars or piles of washers. [Continued on page 147] formerly Modern Mechanix 117

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CRAFTSMAN'S METHOD of MAKINE PITCHERS VERY art shop has an assortment of cop- per pitchers, few of which are hand made, yet, the making of a copper pitcher is simple, requiring no more effort or skill Э than many other hand made metal pieces. For the short pitcher, a 4” length of tubing is used. The metal is thoroughly an- nealed, and while resting on the anvil, one end is driven in evenly all around, grad- ually tapering toward the other end. The piece is annealed and the operation repeated several times, until the end is re- duced to about 2”. Then the tubing is placed over a length of 2” iron pipe and the The tube is expanded by ham- other end is expanded about 12”. The top mering it over a short á 2 s s length of pipe. is trimmed with tin shears to about the right shape, and then the spout is formed over the horn of the anvil, working from the inside. l A disk of 18 gauge copper is cut to fit tightly into the bottom, and soldered in place. The handle is cut, hammered, drilled and riveted on. The rivets should be of soft [Continued on page 147] Hammering the annealed copper tubing to make one c end smaller than the other, HANDLE BLANKS таннен уні ry Em FOR LARGE AND Ed SMALL PITCHERS RESPECTIVELY SKETCHES AT LEFT AND BELOW SHOW HOW OUTLINES OF PITCHERS DEVIATE FROM TUBING BLANK REP- RESENTEO BY DOTTED LINE

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MECHANIX ILLUSTRATED PHO TOGRAPHY | ist Prize—§i5—t0 Howard Ander- son, 413 Pacific Ave., Miles City, Mont, for this startling ‘“‘phots- montage", printed from two super- imposed negatives, Both pietures were taken against a black back- ground, with two ~ photofloods, Hunter and tripod were shot at distance of 15 feet, 5 seconds at f.8 on S.S.pan film in OxI2 em. pack camera, A big close-up was then made ої grasshopper, Va second at {.8. The two negatives were cemented together carefully and printed as one. This is a clever stunt, with mary possibilities. 2nd Prize--$10—1s Henry Olark, 46 Ft, Washington Ave, New york, N, Ya for this fine action shot of a model plane at the moment of launching, Picturos like this are not easy to make, as the plane moves so quickly. 3rd Prize---$5.00 ETT PAGES 119-132 ~to Rudolph Boger, 83111 Glen- weed Road, Brooklyn, N. ¥., tor this unusual photo of a girafe do- ing his stretching downward ine stead of upward! aught with a Super tkonta B, 1/50 second at 1.8, S.S.Pan fim, 4th Prize-- $5.00--to Donald Clements, Ken- nessey, Okla., whe ran for his Kodak Bantam and snapped this rare picture of a black erow sipping а black cats miik white the eat Jeake on in astonishment, Shutter sneed, 1/56 second, at £.6.3, of a sunny day, th Prize—$5.00—to Ellis Butler, Bowie, Tex, The beautiful moonlight effect was pro- . duced by over-developing the print, . Negative was made in a 120 Anseo - eamera using super«sensitive pan- ehromatic film, 1/50 second at 1.32. Tray developed for five minutes In D-52 developer: print en Vitava paper. MONEY FOR YOUR PICTURES! Get busy with your camera and send in unusual pictures of people, animals, machines, trains, airplanes, etc. Each month we will! pay $15 for the best picture received from readers, $10 for the second choice, and $5 each for the next three selections. Prints should be gíossy, as large as possible up to 8x20 inches (although a small, clear photo is more desirable than a big, fuzzy one) and should Be accompanied by the following data: make and size of camera, type of film, and how developed and printed, lens opening and shutter speed, and lighting conditions. Wrap all prints carefully, put your name and address on each, and include postage if you want them returned. Address all contributions to Photography Editor, MECHANIX ILLUSTRATED, 1501 Broadway, New York, N. Y. 119

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What To Do About RACTICALLY all cameras fitted with eye-level view finders suffer from a com- mon trouble known as “parallax.” Though not many camera owners recognize this word, ‘they probably all have sworn plenty at it. Parallax is the displacement of the image as seen in the view finder in relation to the actual image as recorded on the film. You hold the camera to your eye, squint carefully at a person six or eight feet away and move the camera around until you think everything is showing. When you develop the roll, you discover to your dismay that part of the head or legs is cut off, or the figure is off center completely. The error usually is greatest when close-ups are attempted at distances of three to five feet, which is about as close as most cameras will work without supple- mentary lenses. With miniature cameras parallax is a par- ticularly serious matter because the whole negative area is small enough even if all of it is used. If it is necessary to back away from the subject a good deal in order to be certain of getting a whole head, for instance, on the film, the resulting image is tiny and must be "blown up" considerably if a print of decent size is to be made. Beyond about fifteen feet the trouble practically disappears, as the ratio of displacement becomes very small Most eye-level view finders are very accurate from infinity focus to ten, twelve or fifteen feet (depending entirely on the par- ticular camera), not quite as accurate at 120 Above: Taken with the same camera, these pictures show that the view-finder is definitely out of line and needs adjustment. Below: Bringing the camera too. close to the subject sometimes gives this effect. slightly shorter distances, and quite inaccu- rate for intimate close-ups. A permanently fixed view finder is thus something of a com- promise. The makers of the more expensive minia- Mechanix Illustrated—June, 1938

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BLACK SCOTCH T. APE ANGLE ON WALL E PROPORTION How to set up a camera and check the accuracy of its view finder. lures frankly and honestly tell people what to expect in this regard. For camera fans who want to be absolutely certain of what they are "shooting," they supply separate, attachable view finders having micrometer adjustments that eliminate parallax entirely. The system is as follows: First you look through the range finder and focus carefully on the subject. You observe the distance on the lens barrel or focusing mount, and then simply turn the parallax adjustment to read to this same figure. What you then see through the special view finder is exactly what you will find later on the negative. The only catch to this ideal arrangement is that the view finders are practically minia- ture cameras in themselves, with finely cor- rected optical elements, and cost about $25. Fortunately for the owners of more mod- estly priced cameras, it is a very simple mat- ter to determine the accuracy of any view finder at specific distances, and to make ap- proximate but adequate provision for the parallax. For your test “image,” select any light colored blank wall in any convenient room. In any stationery or chain store, buy a ten- cent roll of black “Scotch tape.” This is like the old-fashioned gummed mending tissue you used in school to fix up torn pages in books, but it requires no wetting and is in- stantly removed from any surface without leaving marks. Set up the camera on a tripod or on the edge of a table. Adjust the focus- ing device so that the lens is out to the maxi- mum—the camera is thus set for taking pic- formerly Modern Mechanix FASTEN. TRACING PAPER NG WITH TAPE tures at its shortest possible distance. No film is needed; open or remove the back of the camera and by means of rubber bands or strips of the Scotch tape hold a piece of tracing paper, tracing cloth, a fine silk hand- kerchief, or even ordinary tissue paper over the space normally occupied by the film. The idea is to mark off a rectangle on the wall with the black tape and to illuminate it with any strong light; a photoflood is fine. The rectangle should be in proportion to the negative size. For instance, if the film mea- sures 244x3% inches, the black “frame” can be about 4x6 feet. Put a dark cloth over the camera, open the lens wide and set the shut- ier at "T" (time) and move the camera around until you can clearly see the black box on the improvised focusing screen. Line it up carefully so that it covers the full nega- tive area; if necessary, adjust the tapes to form a smaller or larger outline that fills the negative at the shortest focusing distance. Now lock the tripod adjustment and move your eye to the view finder. The extent of the parallax with your particular camera will then be instantly evident. Repeat the experiment with the camera moved back from the wall at various dis- tances, and at each stage, draw a rough pencil sketch showing how much “off” the finder is. You will then know how much to tilt the camera, and in what direction, in order to be reasonably certain of having the negative cover the desired subject at the critical short distances. (Continued on page 141]

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The upright is a 31” piece of 1” pipe, attached to a S-ply baseboard, 14x18", by a 1”: floor flange. with its threads filed off, slides on this pipe; a thumb- ‘screw on opposite side locks it in any position. A 1x4" nipple joins enlarger head to sliding Tee by means of © 90 degree elbow. EN-DIAMETER projection prints made with the “Minineg” enlarger have that crisp, wire-sharpness that you usually expect only of contact prints. This trim-looking, compact little device is versatile. It will en- large miniature negatives up to 244x2%4 inches in size and, like the 9x12 cm. MM Enlarger described in the March, 1938 issue, will handle small sections of larger negatives. The Minineg follows somewhat the de- sign of the 9x12 cm. enlarger, and uses the same baseboard and upright; a single bushing for the 1-inch tee makes them interchange- able. The unusual compactness is due to the use of a 50-c.p. automobile headlamp bulb, which is extremely cool in operation but supplies an adequate volume of light, Two 3-inch plano-convex condensers, located almost in contact with the negative, assure unusual brilliance and crispness of detail. In constructing the Minineg, three types are available for selection. They differ only in appearance, design and operation being identical. The cheapest to make is the Regular; then there are the Deluxe and the Super-deluxe. Exclusive of condensers and projection lens, you can make the Regular for less than a dollar; the materials consist of l4-inch black tempered Prestwood, with 122 Negatives from 35 mm. to 2% x 2% inches are handled with ease and can be Diora e 10 diameters, The 3" Tee, .. . The enlarger open, ready to receive negative. Film is simply placed, emulsion side down, on the lower glass; hinged top, section of enlarger is then closed down, thus flattening the negative and keeping it in position. focusing and lamphouse tubes formed of sheet metal. Materials for the Deluxe, which is shown in the illustrations, consist of a black Bakelite radio panel and Bakelite tubing of the kind used for winding radio coils. Lastly, for the Super-deluxe, use Catalin. This can be obtained in sheets and tubes and the cost will not run over several dollars. This beau- tiful plastic material is obtainable in many colors and will not require outside finishing or lacquering if a non-actinic red mottle shade is chosen. A special cement is de- sirable, although Duco cellulose cement will hold the Catalin parts quite well. You can get a pair of 3-inch unmounted condensing lenses for $1.50, and a good pro- jection lens will cost from $5.00 up. Used and Mechanix Illustrated—June, 1938

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new bargains are continually offered by the larger camera shops. A 3- or 34-inch anastigmat with aperture of f. 4.5 is standard for the Minineg. A shutter is not necessary. The Deluxe Minineg is shown in the illus- wations, and with the drawings you will not find that construction is at all difficult. You can get the Bakelite panel at any radio supply house, but to secure the correct sizes it was necessary to purchase the Bakelite tubing from two different concerns: 3-inch (inside diameter) tubing was secured from Allied Radio Corp., and 3-inch (outside diameter) tubing from Wholesale Radio Service Co., both in Chicago. The latter tubing makes a very smooth fit inside the former, and the s i 7 . The lamp unit. Holes price is only 7e an inch, and less in 1-foot in the cover pro- vide good ventilation. MAKE FROM CATALIN, FIBRE,OR nARDWOOD TO FIT RECEPTACLE, ‘REFLECTOR ^ 50 CANDLEPOWER AUTO HEADLAMP BULB FIBRE SPACING BAKELITE =- TUBING FUNG 2 RJ / 1% DIFFUSION p DISÈ СИР ТО нос GLASS SHEET ~ m CONDENSING TENS HELD IN PLACE BY SHEET OF GLASS COUNTERSUNK BOL! MEAD of CUT CORNERS OFF Й OF GLASS SHEET 7 TO MAKE ROOM FOR 5” CLIP ON UPPER A PANEL RING CEMENT- | ED TO TUBE 7 3 —ATTACH TO K PANEL WITH : d BOLTS з bs -=!\б ! "Focusimg „7? A 251: n “7 x CEMENT GLASS TO PANEL FILTER A WiRE RING COVERED WITH CELLOPHANE SLIDING TUBE SOLOER TO ^. BOLT HEAD sents KNOB formerly Modern Mechanix “means of a Ml Above — How the Minineg is. focused. The left hand: turns the focusing tube. in or out, and the right one locks it by means of a binding, post nut and a short ma- -chine screw | passing through both the fixed and sliding tubes. (See extreme ‘lower left detail in accompanying draw- ing.) Left-——Phantom cüt-sway view of the entire enlarger. Study this carefully. before Starting construction and you will have no trouble. Note par- ticularly how the lower Bakelite panel mounts to the short piece of piping by SI flange, a short nipple and a 90. degree el- ПУ СТТ expensive fittings, 12

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' Top—-Riveting the hinges to the Bakelite negative holders. Above—-Cementing the glass sheets in place: Old glass plate negativ are suitable for the purpose. lengths. From either of the above sources you can obtain small cans of radio (phenolic) cement, and crinkle lacquer. If you have a lathe, the parts are easily turned and the tubing accurately cut with special chucks. However, equally satisfac- tory work can be done with a 10c coping saw; no special equipment is required to make the Minineg. In setting the small hollow rivets for the hinges, use a prick punch to first enlarge the open end of each, then finish with a hammer. The butt hinges should allow the two parts of the negative holder to be exactly parallel with two sheets of thin glass between; for this reason it will probably be necessary to file down the rivet heads. If the parts are not then parallel, press the hinges in a vise, being sure to protect the Bakelite with small pieces of cardboard. To attach the 4-inch squares of glass, place a drop of cement at the four corners of each; then carefully drop them in place, so that the cement spreads out somewhat, and allow it to dry over night. These glasses, for sand- wiching the negative, are mainly intended for holding negatives smaller than 2% inches square. If all negatives to be enlarged are 214 inches square, or larger, the glass can be omitted and the Bakelite made to meet evenly so as to grip the edges of the film. As the top half of the glass negative sand- wich bears the weight of the lower condenser lens, cement alone may not hold satisfactorily. It is a simple matter to provide a more positive support in the form of small spring clips fastened to the upper Bakelite panel by means of screws or rivets, as the detailed drawings on page 123 show. The safety bracket or stop on the left side of the enlarger head is a narrow piece of Bakelite, notched at one end so that by pull- ing it forward with a finger when the holder is opened, the notch will engage and hold the surfaces apart for changing negatives. The device will disengage when the top of the enlarger is lifted slightly. Solder a brass sleeve to a suitable 3-inch reflector (one from an old flashlight will do) and enamel the inside white. You will find that the 50-candlepower headlamp bulb has the manufacturer’s insignia stamped oppo- site the base, and this must be removed by either buffing lightly and carefully on a wheel, or by rubbing briskly with a cloth Circle—Grinding the round diffusion glass with. valve grinding compound. and -water. Left—The oUa зл - the inner focusing tube is cut with a. short piece of scroll saw blade, and smoothed with the. nailfile.

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charged with metal polish. The socket can be obtained at an automobile supply store, or from an old headlamp. Other parts, and the manner of fitting them together, are made clear by the drawings. A ground glass diffusion disc may or may not be necessary, according to the curve of the reflector. Even illumination must be se-. cured. To make a removable diffuser, cut a disc of glass by running a glass cutter around a wood-dise template. On a lathe, the glass can be chucked and the cutter held against it, on the steadyrest, while the arbor is given one full turn (and no more) by hand. Make straight cuts from the circle to the edge of the glass, before attempting to part it. The ground finish is easy to secure; place a dab of valve-grinding paste on the disc, add a drop of water, and rub it with a circular mo- tion on another sheet of glass. More water must be added frequently. To correct a bright spot cast by the reflector, grind a spot in the center of the other side of the disc. A 3%-inch (focal length) lens was used on the enlarger illustrated, and the drawings give the correct measurements of the focus- ing tube for that lens. A 3-inch lens will cover the negative adequately, however, and in this case the minimum extension should be about 3 or 3% inches and the maximum extension 4% inches. This measurement is figured from the negative to the lens, and it will allow enlarging in excess of 10 diam- eters, or as little as 2 diameters when desired. Drill a hole at each extreme of the focusing range of the inner tube, then paste a strip of gummed paper on either side, between the holes, as a guide for cutting the slot for the tightening nut and bolt. Slight adjustments can be made later when the lens-holding disc “small transformer is desirable, secure even illumination. 6.3 VOLT BR FILAMENT TRANSFO f 10 VOLTS Se E ] LINE SWITCH LAMP IN ENLARGER — ELECTRICAL. CIRCUIT — How the radio or train transformer de connected to the house line. The switch is most conveniently mounted on the table next to the f base. -is cemented in position. A dise of red or amber celluloid or cellophane serves as a filter for use while the paper is being adjusted on the baseboard; a touch on the notched wheel serves to place the filter in or out of position. In finishing the enlarger, the Bakelite parts should be polished and the lamphouse and outer focusing tube coated with black enamel. Crinkle lacquer, as used on radio parts, gives a very attractive appearance, but you should practice applying it beforehand, on waste stock Although a 6-volt battery will supply cur- rent for the lamp, which makes it ideal for automobile travel, for practical home use a A toy train transformer or a radio filament lighting transformer is ideal; 6 or 8 volts is the recom- mended rating, and this will supply plenty ot light with very little heat. When first setting up the Minineg the lamp must be adjusted in the reflector, and. the reflector must be brought to the right distance from the condensers, in order to Left—Parts for the lamp-house, and the toy train transformer used for. power. Above-—How the Bakelite lens disc is cemented into the focus- ing tube. covers the fens while the: enlarging paper is being positioned. Notice the simple red filter, which 125

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ROTARY AFELIGHT LAMP by Walter E. Burton The photograph above shows clearly how the four-position safelight operates. Although light passes through all the safelights at one time. it passes out through the housing through only one section at a time. The corners of the rotor are padded with strips of felt to prevent the possibilitv of light leakage. SHAFT WITH DETAILS OF CLOSED NUT ANGLE STRIPS METHOD OF INSTALLING SHAFT MADE FROM 1/4" BOLT HE usual photographic darkroom ar- rangement of a single safelight lamp whose color screen must be slipped out and another one inserted every time a different type of paper or film is to be developed, can become a distinct nuisance, particularly when the changeover is attempted with wet hands. 4A rotary safelight lamp similar to that illustrated will eliminate such trouble by permitting screens to be changed merely by the turn of the knob. This four-position safelight unit consists of a rotor, carrying standard safelights, that re- volves inside a cylindrical housing having a rectangular opening in the side. A single lamp in a surface-mounting socket projects into the rotor, light from it passing through all the safelights at once, but emerging from the housing through only one at a time. 126 Corners of the rotor, which has a square cross section, are padded with felt strips, to prevent light leakage. Among the materials needed are the fol- lowing: One empty can of the type in which 5-pound quantities of sodium sulphite and sodium carbonate are sold by photo dealers, and measuring about 514 inches in diameter by 6%4 inches deep; a quantity of tinplate for the rotor (empty tin cans can be used); one l4-inch bolt 3 inches long; radio knob, to fit end of bolt after head has been removed; 4 strips of felt 4% inch wide and 5 inches long, preferably dark in color; one small angle bracket similar to those used for bracing corners and supporting shelves: one surface- mounting lamp socket and a 15-watt lamp, Mechanix Illustrated—June, 1938

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with necessary cord and plug; four rectangular safelights each measur- ing 3% by 43% inches; miscellaneous materials including black lacquer, solder, and casein-latex cement or similar adhesive for fastening felt to metal. Obtain the safelights and build the rotor to fit them, and at the same time fit it inside the can that is to become the housing. Wratten safe- lights are standard in this country, and can be purchased for about 40 cents each in the size specified. For complete flexibility with all photographic materials, the following are needed: Series OO, a clear yellow color, for use with contact-printing papers; Series OA, greenish yellow, for use DETAILS OF CONSTRUCTION AT OPEN END OF ROTOR LAYING OUT TINPLATE DISC TO FORM SEGMENTS —— p SECTION THRU SEGMENT AT ROTOR CORNER FRAME TO KEEP SAFELIGHTS FROM FALLING INWARD

SAFELIGHT GLASS

BUSHING FOR SUPPLY M WIRES CORNER PIECE

SOLDER

POSITION OF LAMP & I < AND SOCKET JU METAL’ SULATING X TUBE ү USHING b) OR:

formerly Modern Mechanix

with bromide enlarging paper and lantern slide plates; Series 2, red, for use with ortho- chromatic films and other materials sensitive to green but not red; Series 3, green, for use with panchromatic plates and films. For the extremely rapid panchromatic films that have been placed on the market recently, develop- ment in total darkness is best. Cut two discs of tinned sheet iron, such as that from the sides of an empty tin can, of a size that will permit them to be inserted, flat- wise, into the housing. In the center of one disc drill a- 44-inch hole, to receive the bolt to which the knob used to rotate the safe- lights will be attached. Mark out, on this same disc, a square whose sides are about 1/16-inch longer than the width of the safe- lights. Cut four pieces of tin to the same length, and about %-inch wide, and bend them lengthwise along their center lines, to make right-angle pieces. Solder these to the dise as shown, to form a square frame against the outside of which the ends of the safelights will rest. Cut four strips of tin measuring 1 by 433 inches, and bend them at right angles along their center lines, to form corner pieces of the rotor. Set the safelight glass temporarily in position outside the square frame, place the corner pieces outside the glass, and mark the places where the ends of these pieces meet the disc. Remove the glass and solder the corners in place, applying solder only along the outside, so it won’t pile up near the glass. Mark the other disc with a square the same size as the first one, and then make a smaller [Continued on page 136] 127

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Simple Woode A simple stand for a Brownie safe- light can be made from two pieces of wood, as shown at right. Make the mounting hole slightly smaller in diameter than the end of the socket which receives the lamp and then increase the diameter of the hole gradually with a file until the socket can be pushed through it in a snug fit. Glue, smeared on hole rim, will aid in anchoring the socket.

Developer Temperature Is Easily Regulated If you do your developing in the bathroom, it is a simple matter to maintain an even temperature of solutions in a tray. Simply float the latter in the hand basin, adding hot or cold water as indicated by the thermometer. Be careful water doesn't splash into the trav. n Stand Improves Brownie Safelight

Tape On Lens Gives Stereoscopic Effect

128 A flash-bulb that fails to go off in the usual manner can be made to fire by arranging it so, that the glass part just touches that of another good bulb (right). The “dead” bulb will fire when the good one goes off, its flash oc- curring only about 1/100 second later. <—« A strip of Scotch tape asted on the frone of a lens, as shown at left, will “fuzz” the background of any picture, making the object or person in the foreground stand out like a4 stereoptican picture. Tape should cover about one-fourth of the lens. Mechanix Iliustrated—June.

19348

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How To Grind Glass For Photo Use Make your own ground glass for enlargers, etc., by rubbing any paste abrasive between glass sheets with a circular motion (above). Lamp Shade Clip Improves Reflector It is sometimes difficult to make good pictures of people indoors with photoflood lamps unless the latter are diffused in some manner. A lamp shade adapter with its center hole covered by a washer and bolt (above) makes an ideal "cap" to clip over the end of a bulb so that only light from the reflector shines on the subject. Large prints can be vignetted smoothly and cleanly, fading out to a perfect white at the edges, by a chemical method instead of the usual dodging method. Expose the print without masks or dodging, dip into plain water and then dip the finger in developer solution and rub it over the part to be brought out (right). 2? ? formerly Modern Mechanix Clothespin Serves As Thermometer Handle Checking the temperature of developer solution in a large bottle with a slippery stirring rod is risky, especially when the fingers are wet. Clipping a spring clothespin on the thermometer, as shown above, will provide a satisfactory han- die and lessen chance of breaking the thermometer. Chemical Method Of Vignetting Prints 129

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HE only sensible advice that can be given to people who want to photograph chil- dren is: Shoot often and shoot a lot. Chil- dren are restless creatures, and change their moods and expressions from one minute to another. The successful child photographer needs a lot of film and a lot of patience, and the willingness to expend both. The most cherished pictures are those made while the child is eating, walking, playing or doing something else that is normal for its age. The most uninteresting baby shots are those made with the squirming victim tied into a studio seat, in an unaccustomed setting of arc lights and painted backgrounds. The subject should not even be conscious of the presence of the camera, and should never be told to “Hold it!” or to “Look at the birdie.” Baby pictures must be shot on the wing, so to speak. Many will be com- plete misses, but some are bound to be good. The photographer who obtains two or three negatives out of a 36-exposure roll over which he really can exclaim, “These are that only the permanent pictures made by a camera can help their parents remember what they looked like one month, two months or six months back. Taking pictures outdoors is, of course, no problem. However, the really “cute” shots are those of Junior or Little Dimples in his or her bath, crawling on the floor, spattering cereal over the kitchen, sparring with a kitten or puppy, thumping the piano, building block houses, riding piggy-back on Daddy, or doing any of the dozens of other mischievous things that babies have always done. Lighting be- comes a problem, but certainly not a difficult one in these days of super-super speed nega- tive materials and photoflood and photoflash lamps. The minimum requirement is proba- bly two photofloods in adequate reflectors. plus a camera with at least an f. 4.5 lens and loaded with fast film. A little experimenting with exposure speeds on the first roll will quickly tell if the light is bright enough. Although they appreciably reduce the vol- ume of usable light, diffuser screens of thin kid stuff by ROBERT HERTZBERG pe beauties! is really enjoying a high degree of success. Film is cheap, so blaze away! If the child is your own, no preparatory work is necessary. Just keep a loaded camera handy and be ready to use it when- ever lighting conditions permit. If the sub- ject is some other person’s offspring, it is a good idea to become acquainted with the child, by means of several preliminary visits, before you go to work in earnest. Some of the successful professional child photogra- phers make a practice of studying a child’s habits over a period of several days or even a week, and then arrange to do their actual shooting either indoors or outdoors when the child's activities present the best photo- graphic opportunities. At what age is a child ready for the camera? As soon as it is old enough to keep its eyes open for more than two minutes at atime! The parent-photographer who shoots a roll or more of film every single week- end, beginning when the baby is two weeks old, eventually compiles an absolutely price- less record of human development. Babies grow and change with such amazing rapidity 130 tracing ‘cloth are- a highly advisable, as they remove the cruel glare of the bulbs and make an anxious mother feel more comfortable. The ideal outfit for child photography is a camera equipped with a synchronized flashgun, permitting flash exposures up to 1/200 second. This speed will "freeze" any natural movement of even the most active child, and will shorten shooting time. How- ever, the advisability of using flash bulbs is open to question. Some children are fright- ened by the sudden, blinding stab of light, and go screaming to their mothers' skirts. For this reaction they hardly can be blamed: many adults are half-frightened out of their skins even when they are prepared for the flash. Some children, on the other hand. think the flash is a new kind of game, and enjoy it hugely. Try one flash experimentally and see how the intended "victim" reacts. Incidentally, flash bulbs are known to shatter occasionally because of the intense heat created inside the glass bulbs by the ignition of the foil. It isn't a pleasant pos- sihility to think about, but one such experi- [Continued ‘on page 138]

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at For this unheard of price, you can get the marvelous Dynamic Super- Charged Welder complete—all ready to plug in your light socket —nothing else like it has ever been made. This new Dynamic Super- Charged Welder is a radical departure from accepted welding practices. It will do the work of welders selling for much higher prices—such as cylinder blocks, bumpers, tanks, etc., and at the same time will solder and braze on the lightest material—and the cost is not $209.00 or $100.00—think of it, the complete price is only $19.75. WELDS CYLINDER BLOCKS, FENDERS, AXLES, BODIES, BUMPERS, FARM MACHINERY, ) CAST IRON RADIATORS, ETC. With the Dynamic Super-Charged Welder, a man without previous welding experience can make for himself as much as $5.00 on a repair job that can be done in less than one hour. Many welders make as much as $15.00 to $20.00 a day. Despite its serviceahility, the Dynamic Weld- 9 er is light and easily portable— can be carried around by hand and set on the running board of any car you are working on. | WORKS ON IRON, STEEL, TIN, BRASS, COPPER AND ALL OTHER METALS. With this welder you can work on all kinds of metal—nothing will stump you—you can tackle anything and in no time at all you will be able to do finished repair jobs that will do credit to an expert. Once you have the Dynamic outfit, you are all set .in a profitable welding business of your own—you boss it yourself. xN x —=ь- ——— e = AM . READ WHAT USERS SAY |, Electrician gays: ‘It is the best welding outfi I wish to tell you that I demonstrated your we ing outfit to a great many people, and they all agreed with me that it did the best welding job they ever saw. A. Bristol, Conn. Mechanic Praises Welder X have received my weldec and llke jt very much. I am a mechanle' and electriclan by trade, so I can appreciate its usefulness to others. P. C., Perry, N. Y. Repair Shop Owner Tells About Dynamic Y want to say I operate a repair garage and I am miore than satisfied with the welder, It will do more than you say. C. P., Butler, Ohio. Greatest Portable Out I must say it’s the greatest portable outfit any man could wish to own. You may put me on file as a booster. W. J. B., St. Jobn, N. B., Canada. DOES METALLIC AND CARBON ARC WELDING Can be used efficiently on both types of welding. The cost of using the Dynamic Super-Charged Welder is amazingly low —costs only a few cents an hour to oper- ate. It is built so strongly that repairs are practically unknown—yowll never have to worry about them. It cools so efficiently that you can use it continuously without ever having to stop in the midst of a job to let it cool down. These pictures show how easy it is to operate the Dynamic Super-Charged Welder. A ten year old boy can do a swell fender repair јо” -ап іпехрегі- eneed man soon can do all kinds of Welding. = аши иг You may send me full particulars on your big profit plan 5 DYNAMIC à AGENTS WANTED! Do you want something easy to sell? B 2226-EM silverten Rd. Chicago, Illinois k * . You can make big profits introducing и Gentlemen: ' ' ` to garages, factories, mechanics, janitors and maintenance men the E new Dynamic Super-Charged Welder—we'll let you try it for ten 1 and 10 day trial offer. days at our risk so .you can be convinced of the immense sales possi- I bilities. Get our big profit plan and ten day trial offer. Just send E Name ...- coupon below and mail it TODAY. т. о оо DYNAMIC WELDER СО. К лайев --------- 2226-EM SILVERTON ROAD, CHICAGO, ILL. i youn When Answering Advertisements Please Mention June Mechanix Illustrated

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MITT. 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 docs not permit publication of the question on this page, Send all inquiries to the Photography Editor, Mechanix Illustrated, 1501 Broadway, New York, N. Y. STOPPING ACTION I have a camera with an f, 4.5 lens. To stop action I snap it at 1/100 second. Could I set the lens opening to f. 6.3 or 1. 8 and get better results? When I have it at f. 4.5 fast action is a little blurred.— Joe Felice, Coal Center, Pa. What vou must do to stop action is set the shutter for a faster exposure, say 1/200 or 1/300 second. Closing down the lens diaphragm will only make matters worse, as this will reduce the amount of light admitted to the camera and will make the negatives underexposed, without affecting the “stopping” action of the shutter in the slightest. It the fastest adjustment on your camera is 1/100 second, your action pictures will be somewhat limited in scope. REMOVING EMULSION FROM OLD PLATES A commercial photographer recently cleaned out his dark- room and gave me several dozen glass plate negatives in the 5x7 and 8x10 sizes." How can I remove the emulsion easily, so that I can use the glass for making a contact printer, a negative sandwich for an enlarger, a retouching easel, ete.? A chemical method, whereby the plates are dipped into a solution of some kind, is desired.—J. P. L., Fort Worth, Tex. Soaking the plates in hot caustic soda or potash solution is the recommended chemical method. The solution is diluted to a hydrometer reading of about 10, and is used in a large glass container or vessel. Soak the plates until the emulsion is loosened, and then rinse them thoroughly in hot water. Of course, rubber gloves and aprons must be worn to protect the hands and clothing. The compounds sold under various trade names for cleaning toilet bowls and other ceramic fixtures consist largely of caustic soda and are obtainable in most hardware stores at low prices. ACETONE FOR CELLULOID TANKS I want to make those interesting celluloid developing tanks described in your December 1937 issue, but am having trouble obtaining the acetone called for. Can you help me? —A. Sinai, San Francisco, Cal. Acetone is a common and inexpensive chemical, widely used in finger-nail preparations. Your local drug store un- doubtedly has it in stock and will sell you small quantities. DARKROOM LOCATION The only two places in the house where I can build a dark- room are a large clothes closet and a corner of the basement. The closet is next to the chimney and is quite hot most of the year, On the other hand, the basement, which has a dirt floor, frequently becomes damp. Which location would you recommend?—R, Stotter, Bridgeton, N. J. The basement location will be better than the closet. Al- though excessive heat and humidity are both harmful to negatives and sensitized paper, it is much easier to enclose these materials in waxed paper envelopes or other tight con- tainers than it is to ventilate and cool a windowless closet. Furthermore, developing and fixing solutions are definitely damaged by excessive heat, whereas they are not affected in the slightest by occasional spells of high humidity, for the simple reason that they are liquid anyway and are kept in corked bottles. The availability of a convenient supply of water in the basement is another important factor. To protect your feet from dampness, build up some sort 132 of a rough floor. Level off the earth, tramp it down as hard as possible, and then cover it with a layer of crushed cinders about two or three inches deep. Over this place a wooden platform made of scrap lumber of any sort. Paint the boards generously with as much creosote as they will absorbs this will prevent rotting. A wooden floor is preferable to cement, tile or stone because it is much easier on the feet. FINDING FOCAL LENGTH OF LENS I have a fens from an old camera that I would like to use in a home-made enlarger, but I do not know its focal length. There is no marking on it. Is there any simple way of measuring the focal length? —A. H., New York. The familiar old "burning glass" stunt should be helpful. Using the sun or an unshaded electric bulb as the light source, move the lens back and forth in front of an upright piece of white cardboard until a sharp image or bright spot appears on the latter. This distance between the fens and cardboard, as measured in inches, is the focal length, SLIDES FOR PROJECTION How can I prepare small sheets of glass to take a positive image, so that I can project pictures on the wall? I under» stand that sensitizing solutions can be mixed using standard photographic chemicals.—"'Lecturer", Chicago, Ill. It is quite unnecessary to prepare your own plates. Lantern slide plates, which measure 3lJ4x4 inches, have been on the market for many. years, and are easily printed, developed, and fixed just like contact prints. If your local camera dealer doesn’t have them in stock, he can order them for you. USING PROJECTOR AS ENLARGER T can buy a used "silent motion picture projector very cheaply, but before doing so would like to know if it can be rebuilt conveniently to act as an enlarger for miniature camera film.—Phil Miller, Brooklyn, N. Y. Probably not. First of all, miniature "still" cameras using 35 mm. motion picture film take a double-frame image; the projector is designed only for the standard movie single frame. Second, the focusing arrangement does not have enough extension for making enlargements only a foot or so from the lens, as the projector was designed to throw images the length of a theatre. Third, most projection lenses are not sufficiently corrected for the making of fine still pictures, All in all, the best thing to do is to buy or make an enlarger intended specifically for the purpose you have in mind. MECHANIX ILLUSTRATED AWARDS $40 EACH MONTH FOR BEST PHOTOS SUBMITTED BY READERS The editors of MECHANIX ILLUSTRATED dis- tribute $40 in cash awards each month to the five persons who, in their opinion, submit the best pictures suitable for publication in the MECHANIX ILLUS. TRATED Photography section. Full particulars re- garding these awards will be found in this issue on page 119.

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!'Slices-of-life'' shets, speed shots, scenics, night work, full color . . . count on Retlna Call your shots... name your price There's a Kodak Retina that's right for you F your first camera, or your next cam- era, is to be a miniature, and you're looking about for one at your price that will give you all the pictures you plan to take—including gorgeous full-color Kodachrome—consider a Kodak Retina. KODAK RETINA II, f.2.0, $140 Coupled range finder. Body shutter release. Doubie-exposure prevention device. Auto- matic exposure-count dial. Lens, anastig- mat f.2.0. Shutter, 1/500 Compur-Rapid. Price, $140 (with sportsman's field case). KODAK RETINA II, f.2.8, $5 Identical with Kodak Retina II, f.2.0, except that lens is an anastigmat f.2.8. Price, $115 (with sportsman's field case). Only EASTMAN makes the KODAK There are three Retinas, all with the fast lenses and shutters, the speed and ease of operation, and the wide picture-taking scope necessary for brilliant work in the miniature field. At your dealer’s ... Eastman Kodak Co., Rochester, N. Y. KODAK RETINA I, f.3.5, $57.50 Lens, Kodak Anastigmat EKTAR f.3.5. Shut- ter, 1/500 Compur-Rapid. Finger and special plunger releases. Enclosed optical eye-level finder. Exposure counter. Price, $57.50. Soft black leather case, $1.50. Tan sole leather field case, $8.50. LOAD WITH A WIDE RANGE OF KODAK FILM KODAK PANATOMIC—Fine grain permits an amazing degree of enlargement. 18- and 36-exposure mage- zines. KODAK "SS5” PAN—Lightning-fast. ideal for snap- shots at night. 36-oxposure magazines. KODAK SUPER X—Fastor even than "SS." Invaluable Indoors and out. 18- and 36-exposure magazines. KODAK INFRA-RED—With a red filter, cuts through atmospheric haze, produces dramatic effects. 36- exposure magazines. KODACHROME—For full-color transparencies. No ex- tra equipment needed, 1B-exposure magazines. When Answering Advertisements Please Mention June Mechanix Illustrated 133

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Science Is King! [Continued from page 38] one case—that of Goethe—many people forget that he was a Privy Councillor at the Weimar court and an able administrator. But his mind was the only one in Europe comparable to that of Leonardo da Vinci. He was a poet, humanist and a pathfinder in the realm of Natural Science. The other name that comes to mind is that of Benjamin Franklin, inventor as well as states- man. His experiments will always be rated as a landmark in the history of electricity. In gen- eral, however, it is safe to say that all progress in mechanical as well as other science has been made in spite of statesmen. Most statesmen have stood for traditionalism. Their attitude is exem- plified in the action of the Holy Office in 1633, which brought Galileo Galilei:to trial and with torture made him recant and deny the scientific ‘discoveries he had made. `. If we examine the history of scientists and scientific discoveries, we will find that man did not really begin to think straight until the ar- rival of the mechanical age. Up to that time, practically all human thinking had ween deduc- tive. That was the weakness of even the great- ést minds among the Greeks—the reason why ‘they remained so backward in a mechanical sense. They were deductive thinkers, reasoning from the general to the particular. It was the mechanical scientists who started us thinking in- ductively, from the particular to the general. Bertrand Russell, in his brilliant work, “The Scientific Outlook,” attributes the beginning of modern thought to Galilei. When he discovered the four moons of Jupiter, with his primitive telescope, he did far more than add a little bit to the world’s astronomical knowledge. He es- tablished beyond doubt the truth of the theory that Copernicus had hit upon himself, but which Copernicus was unable to prove: that the Ptole- maic system, which had governed the world’s thought, was all wrong; in short, that our system is heliocentric, that we revolve around the sun. This seems like a rather dry commonplace to us today. The mere fact that it aroused the wrath of the Holy Office reminds us how elec- trifying, even how horrifying it was in the Seven- teenth Century. It was not only the ecclesiastical authorities who pounced upon Galileo. Some of his own students hissed him at his lectures. As Bertrand Russell points out, “The conflict between Galileo and the Inquisition is not merely the conflict between free thought and bigotry or between science and religion. It is a conflict be- tween the spirit of induction and the spirit of deduction. Those who believe in deduction as the method of arriving at knowledge are com- pelled to find their premises somewhere, usually in a sacred book. Deduction from inspired books is the method of arriving at truth employed by jurists, Christians, Mohammedans, and Com- munists. Since deduction as a means of obtain- [Continued on page 139} 134 Tricks With Bottles [Continued from page 99] impossible to push the egg into the bottle because there is no way for the air inside to escape. The problem is solved as follows. Light a small piece of paper and drop it into the bottle, then quickly replace the egg over the opening, standing it up- right on one end. The burning paper exhausts the oxygen inside the bottle, creatinz a partial vacuum which sucks the egg slowly inside! You are now faced with the problem of removing the egg. To do this, raise the bottle to your lips, bending your head back so that the bottle can be inverted. Blow vigorously into the bottle, then suddenly lift it from your mouth. The compressed air which you have created inside will cause the egg to pop quickly out of the opening! FASTENING LABEL TO INSIDE OF BOTTLE Transferring a label from the outside to the inside of a bottle is an amusing stunt to show your friends. Moisten the label with water until you can peel it from the glass. Roll it into a small roll (with the writing on the outside) and push it into the bottle, then pour in a small quantity of water. Hold the bottle horizontally and shake it gently. The water will cause the label to unroll and stick firmly to the inside of the glass! MARBLE OVERCOMES GRAVITY An interesting puzzle-problem illustrating tne principle of centrifugal force can be created with an empty milk bottle and a glass marble. Drop the marble inside. The problem is to turn the bottle upside down and carry it across the room, without permitting the marble to drop out. The trick is done by taking the bottle by the neck and giving it a circular motion causing the marble to run rapidly around the inside. Gradually raise your arm until the bottle is inverted, continuing with the circular motion. The marble will spin about inside the glass, just above the neck, enabling you to transport the bottle and marble where you please! STRAW HOLDS BOTTLE Lifting a bottle with a soda straw sounds like a difficult feat, but it is easy when you know the secret. Bend the straw at one end and push this end through the neck so that it will spring open on the inside of the glass as shown in the picture. It is now a simple matter to lift the bottle with the straw. MYSTERIOUS ROPE TRICK A trick with a bottle and rope has become quite popular recently among magicians. You can prepare it very simply. It requires a small bottle of opaque colored glass, a piece of soft rope about three feet long, and a small piece of [Continued on page 144]

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VACATION IN THE OPEN JUNIOR SCOUT Get out in the open this summer! Explore highways and byways! All outdoors is yours—for fun, excitement, adventure— when you ride a twin-cylinder Indian Junior Scout—the biggest "buy" in ell motorcycledom. - Su EASY TO OWN. AN INDIAN The new 1938 Indians aré as easy to buy as they are to handle, and you can't beat ‘em for economy and smooth, dependable ‘operation. Ask your Indian dealer to demonstrate an Indian—explain Indian's easy pay-as-you-ride plan. sasueusrecusestehennanenaeenm INDIAN MOTOCYCLE CO., Springfield, Mass, Please send me at once, without obligation, your illustrated Folder showing the new 1938 Indien Motocycles, and CERTIFI» CATE of VALUE entitling me to FREE RIDER'S HELME®- and INDIAN PIN, ee illustrated, when J place my order. 3 OTHER NEW 1938 MODELS DE LUXE 4—the only American-made 4-cylin- der motorcycle. CHIEF 74—a peerless HELMET and E “top speed” performer. INDIAN PIN SPORT SCOUT—2 MAIL COUPON TODAY! FREE! Getthis RIDER'S амм Please be sure to check your age group: MM68 016-19 years (120-30 years C331 years end up O under 16 yeare штар by a devasteting, sxplosten, ave Also: ‘bodies of three innocent children testifie Ж : " to a йеп fury. But a derer trap revealed — California's Passion Fiend and the Doomed Lovers the cruel killer. Don’t fail to read this gripping story in the June issue of STARTLING DETECTIVE ADVENTURES Trapping Denver's Wolf Gang under the title, And Many Others FATAL GIFT OF THE ON saz GREEDY KILLER —newss7Anps 15c Geisha's Death Kiss and the Laughing Cornse ADVENTURES aE Ur UN EUR VUE ДААА. AC I E MM TUR T CÓ When Answering Advertisements Please Mention June Mechanix Illustrated 135

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For Economy BUY—For Income SELL The EIFEL-GEARED DUERENCH KIT NEW 7" and 815" Sizes— Each with 3 instan Ily changeable Jaws „6: / A $50 Service atthe Cost of One Tool! @ MAIL this Ad Today with your address © Get FREE—7-Edge End-&-Angle Screwdriver; 101 Picture Manual of Mechanics, with ў (User Offer, or C) Distributor Territory and Free Kit Offer. S Bea PlieRench Man, They're making $35 to $85 Weekly! AMERICAN PLERENCH CORPN Мме-авин, ete. LECTRICA ° ENGINEERING * ONE YEAR condensed course prepares for technical work in the electrica] field. 'Thorough training in principles, with practical applications in laboratory and shop. High placement record. Modern buildings, dormitory, dining hall. Campus. 46th year. Catalog on request. ww BLISS ELECTRICAL SCHOOL 296 Takoma Avenue Washington, D. C. IN YOUR CAMERA! Others make good in- comes selling pictures to ublieatlons. FREE BOOK ET еза: home- Study course (which may paid for in easy Insta pe ments) ana tels "how vou eT A can do it UNIVERSAL P PHOTOGRAPHERS, Dept. 336, 10 W. E St, N. Y. C. 136 Built To Win [Continued from page 59] fuel, have more working parts to go wrong, and are heavier. Some of the best known drivers in the game will ride behind Offenhauser engines. Such men as Louis Meyers, Kelly Petello, and Wilbur Shaw will stake their chances of winning something upwards of $40,000 on Offenhauser motors. Asked which driver he thought would win, Offenhauser was noncommittal: “They’re all good drivers. It’s anybody’s race. The Indianapolis grind is one sporting event that’s never in the bag. I'll tell you the winner when he gets the checkered flag. Sometimes I prefer to have a conservative driver behind my motor. On the other hand, it’s a thrill to see your motor stand up under the punishment one of the daredevil drivers will give it. After all, I build my motors to win—not to keep for pets.” What causes a racing motor to break down? There are as many reasons as there are parts. Sometimes you get a plague of broken connect- ing rods, then it’s the valves; again it may be the timing chain. Recently, however, the chief trouble has been with overheating. When a driver is pushing the throttle hard, his engine may overheat to the point that the oil vaporizes, causing an extra stop to re-fill the crank case. This trouble was particularly acute in 1937 because of the heat wave which settled over In- dianapolis on the day of the race. To compensate as much as possible for weather conditions many drivers study a barometer and humidity gauge before adjusting their motors for the race. You can’t stop very often at Indianapolis—and get away with it. You have to do your figuring before hand. That’s what makes the builders of racing motors get gray. It takes a great driver to win at Indianapolis, but no driver can finish in the money if his motor won't stand up. The result of the race this year is in the lap of the gods that govern life and death on the oval—but the power plants won't fail—if human genius and patience can prevent it. Rotary Safelight Lamp [Continued from page 121] square inside it and about 11⁄4 inches smaller all around. Draw diagonals of the squares, extend- ing them to the edges of the disc. Cut out four segments, by following the boundaries of the smaller square, and the diagonal lines to the dise edge. Bend the tin at right angles along the lines made when the first square was marked. Solder the four segments to the free ends of the corner pieces of the rotor, as shown. You now have a framework completely surrounding the safelights when they are inserted into it as shown in the photograph. To prevent the safelight glass from | falling inward at the open end of the rotor, make Arcebt No Substitutes! Always Insist on the Advertised Brand!

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a square frame, with sides bent to form right- | angle sections, and insert it so that it projects downward inside the safelights. Fasten the frame in place with solder after the safelights are in place. With the dimensions given there will be a frac- tion of an inch clearance between the corners of the rotor and sides of the housing. Glue the strips of felt along these, to build them up to the full diameter of the housing. This provides an adequate light seal. Two or three linen threads wrapped around the rotor will hold the felt while the glue sets, and can be left permanently in place if desired. At a point in the side of the housing directly opposite one of the safelight areas when the rotor is resting inside, cut a rectangular opening measuring about 2% by 4% inches. Flare the longer sides slightly outward, so they will not catch the felt corners of the rotor when it is turned. In the center of the bottom of the can forming the housing, mount the lamp socket, running the wires out through holes bushed with small metal tubes or anything else that will pre- vent damage to the insulation. Caulk the holes with putty to prevent light leaks. Drill a 44-inch hole in the center of the can lid. Paint inside of housing and lid black, and the outside any color desired. Solder or rivet the angle bracket to the end or side of the housing, in such a manner that the light opening will be where it is needed in the darkroom-—usually directly above the developing area. Exact position of the bracket on the.can will depend on particular mounting conditions. Cut the head from the Y4-inch bolt, and run two nuts on the end until about % inch of the threaded portion projects. Tighten the nuts firmly against each other. Insert the end of the bolt into the hole in the closed end of the rotor, and anchor it in place with a lock washer and two more nuts. Insert the rotor into the housing, place the lid in position, with the bolt projecting through its center hole, and mount a radio knob on the end of the bolt, which now has become a shaft. The safelight lamp is now complete. A quarter turn of the knob will swing a new safelight into position. Check the device carefully for light leaks. You probably will find it necessary to caulk around the safelights a bit. For this, use soft cotton string cemented in position with black lacquer. Cost of such a safelight lamp, using Wratten color screens, should not exceed two dollars. The world’s worst weather is claimed for the Antarctic—the home of the blizzard. How planets are born is unknown, but one astronomical theory is that gravitational force may draw a planet from the surface of a star fenders and hood. Nee pu Pont, Pert MM.2, when another star passes close enough. Make your car sparkle like new! It's quick and easy to do it with Du Pont No.7 Polish, A little brisk tubbing removes dull TRAFFIC FILM and restores the original color and lustre. No. 7 Polish is made by DuPont, world's leading makers of ` modern car. finishes. Thats your assurance it’s right for the finish on your car. REG, US. pat OrF Sample for You! Send 6 3 ing cost, for sample can бона erie (Offer good ia Ù. When Answering Advertisements Please Mention June Mechantz Illustrated 137

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LENGTHY FISH POLES CONDUIT PIPE TENT POLES WITHOUT LOSS OR DAMAGE! Suction cup attachments hold firmly without slightest dam- age to car finish. Strong spring holds load tightly at all times. Quickly detachable. Carry pipe, boards, tent poles or bamboo fish poles easily, safely. Sports- "ren and mechanics—you need AUTO “KLAMP.” Send for a pair today. QUALITY HARDWARE & MACHINE CORP. 5849 RAVENSWOOD AVE. CHICAGO, ILL. EARN MONEY Make Color-glazed Concrete Products E New, perfected low cost method. No molds, power or costly tools. You build your own equipment from Š plans we furnish. Experience not necessary to make color-glazed concrete garden pottery, statuary casting, giftware—in home or shop—to earn money, MEN end 10c TODAY for booklet, decus of this money making business. gatio NATIONAL POTTERIES COMPANY Room 8, 13 W. 26th St. Minneapolis, Minn. кб SPECTOR. TODAY | EARN BETTERPAY WITH THIS TRAINING A GOOD POSITION is waiting for our trained Railway and Bus Passenger Traffic Inspectors. Sim- ple, home-study course quickly qualifies you and upon completion, we place Dod at up to $195 per month, plus expenses, to start, or refund tuition. Ambitious men advance rapidly. Free booklet gives our 19-yr. record. STANDARD BUSINESS TRAINING: арал Div. 6106 POSTPAID ON RECEIPT OF MONEY ORDER TO cotorplate, No obli- New 100 page book contains most complete list of woodworking supplies in the world— Standard Amerlean woods cut-to-size at bargain prices. Rare imported woods. Veneers, ply- woods, inlays, carved legs, mouldings. decora- tions, special tools, Hard-to-And ornamental hardware, scroll saw patterns, wood-finishing instructions—How to make Venetian Blinds at 14 store prices. Send only 10e for Catalog No. 10 to Craftsmen’s Wood Service Co., 2740 S. Mary Street, Chicago, Ill. Become an expert photographer for pleasure or career, Big money-making opportunities, Commercial, News, Portrait, Advertising, Candid or Motlon Picture photography. Instruction by noted experts. Personal Attendance and Home Study courses, Write ot. ree booklet, NE RK INSTITUTE. OF PHOTOGRAPHY 10 West 33 Sr (Dept.153) New York City 138 Accept Ne Substitutes! Always Operate Two Trains On Track [Continued from page 115] connection passes from the terminal of the trans- : former through the disc to each of the small stub | contact screws, thence through the lamp-and-coil combinations to the third rail of each respective block. The other terminal of the transformer is connected to an outside rail as usual. Number 22 Double Silk Covered Magnet Wire is best for use on the telegraph poles. If the outfit is not set up and taken down often, Enameled Wire will be much cheaper and some- what more realistic-looking. Fahnestock connectors taken from old radio batteries were soldered to the third rails, but it is necessary only to “tack” the end of the wire to the rail with solder if no connectors are at hand. An oval is not the only layout for which the circular controller will function. If other layouts are used, a cardboard disc may be fastened to the , panel and a diagram pencilled on it, indicating the ‘ block controlled by each button. A switch or crossing should not be included in two blocks, Spurs and side tracks may be readily ‘ handled as single blocks, switches being included in the main track blocks. Building “Patty”—812-Ft. Skiff [Continued from page 98] _ and aft. The seat amidships rests directly on the seat riser and is cut to fit the inside beam. This seat is 10” wide and 34” stock. Make four chocks for the oar locks so that Patty may be rowed from the middle or bow seat, or both. Oar chocks are cut to the shape shown cut of 134” white oak. Screw metal plates to the ‚ tops to prevent chaffing while rowing. Fasten the lecks 12" from the rear edges of the seats with 2" screws. Drill a 36” hole through the stem 6” from the top for an eye-bolt, to which the bow painter is tied or eye-spliced. Do a thorough sanding job. Then paint or varnish with two coats of yacht white, marine black or spar varnish, respectively, according to preference. If Patty is to be converted into a sailing dinghy, use the dimensions and details for a detachable fin keel given in the accompanying sketches. An appropriate rig is also suggested in illustration. A hole from the mast should be drilled through the bow seat 10” from the extreme bow. A half- inch lag screw with the head cut off, resting in a 34” socket, is a fitting mast-step. The mast is ten ! feet long and 2" in diameter. Kid Stuff [Continued from page 130] ence will end your career as a child photographer. Take no chances; put a Cellophane envelope on each bulb or wrap it in a thin silk handkerchief. Insist on the Advertised Brand?!

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Science Is King! [Continued from page 134] ing knowledge collapses when doubt is thrown upon its premises, those who believe in deduc- tion must necessarily be bitter against men who question the authority of the sacred books. Gali- leo questioned both Aristotle and the Scriptures and thereby destroyed the whole edifice of me- dieval knowledge.” Of course there was one good substantial rea- son for the hostility of the deductive thinkers towards the process of induction. The inductive method requires infinitely more hard, digging, exhaustive work. Each particular fact required for a general conclusion „has to. be laboriously sought out and established. Galileo almost with one stroke, demolished and made useless the con- clusions of those who went before him. Bertrand Russell says further: “As a matter of fact, knowledge is even harder to come by than Galileo supposed, and much that he believed was only approximate; but in the process of acquiring knowledge at once secure and general, Galileo took the first great step. He is, therefore, the father of modern times. Whatever we may like or dislike about the age in which we live, its increase of population, its improvement in health, its trains, motor-cars, radio, politics, and adver- tisements of soap—all emanate from Galileo. If the Inquisition could have caught him young, we might not now be enjoying the blessings of air-warfare and poisoned gas, nor, on the other hand, the diminution of poverty and disease which is characteristic of our age. “It is customary amongst a certain school of sociologists to minimize the importance of in- telligence, and to attribute all great events to large impersonal causes. I believe this to be an entire delusion. I believe that if a hundred of the men of the Seventeenth Century had been killed in infancy, fhe modern world would not exist. And of these hundred, Galileo is the chief.” Bertrand Russell ran into a great deal of criti- cism when he assigned to Galileo such an im- portant place in the history of civilization. To me personally, his idea seems fundamentally sound. At the same time, I admit it’s perhaps unfortunate that the credit for certain lines of progress in human civilization should be con- centrated so much on a few men. We talk of one man as being the Father of This, and the other as being the Originator of That, and a third as the Discoverer of So-ard-So, From the story of exploration we know that all discoveries really are the work of a great number of men, most of whose names have completely disappeared and been forgotten. Geographers no longer believe that Columbus was actually the first man since Leif Ericsson to rediscover America. All human knowledge is the result of a labor of a multitude of workers, many of them obscure. And this is particularly true in the mechanical sciences, par- [Continued on page 162] Treet Topics By DOING THIS: ТЕБЕТ MC. T. -AND TREET YOURSELF TO A PACK OF PERFECT SHAVES’ FOR GEM AND EVER-READY RAZORS- Treet Safety Razor Corporation, Newark, New Tél When Answering Advertisements Please Mention Jene Mechanix Ilustrated 139

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INVENTORS PATENT YOUR IDEAS SEND FOR FREE BOOK ===> HOW TO OBTAIN A PATENT Written by a Former Member of the Examin- ing Corps (1922-24) of the U. S. Patent Office, M you want to profit by your idea, you should take once. interesting steps to apply for a - . Patent at Your first sten is to get this Free Book. This illustrated book contains valuable information you should have. It tells you fully how to obtain a patent on your Idea in the quickest way. With this Free Book you will also recetve a ‘(Record of Invention’? form on whieh you m can easily record your jdea. Personal and Confidential B Service: Your case will be personally handled only by a Registered Patent Attorney who Is also a Former Member of the Examining Corns of the U. S. Patent Office. All 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 8 Woolworth Bidg., 35th Floor, Dept. 68B, New York City q MILLER BUILDING, Dept. 68B, WASHINGTON, D.C. Please send me your Free Book, “How to Obtain a Patent," and your "Record of Invention’’ form. I 1 3 ADDRESS r , OW ONLY N & m Over 7,000 GHQ Gas Engine Kits have been sold at $8.50. Now is your chance to buy the New Improved kit for $5.00. Absolutely complete with coil, plug, ete. Send only $1. Shipped Exp. Coll. for balance same day. Catalog 3c. Dealers write. 854A East 149 St., GHQ MOTORS, New York YOUR OPPORTUNITY To obtain the Camera or Equip- ment you want at BARGAIN PRICES. Our Tremendous Stock enables us to give you the opportunity of bringing your equipment up-to-date Economically. NEW YORK CAMERA EXCHANGE 109 FULTON ST., NEW YORK CITY, DEPT. MX6& SINCE CANDID BARGAINS PHOTOGRAPHIC ALMANAC. егу x Free 1938 Almanac in- cludes ‘1: Special month-by-month Photographio Gatendar. '2) Authoritative photographic article Н Exposure Table, Exposure Guide, (4) 100 pages of atill & movie cameras, films, lenges, enlargers, chemicale—everything photo- &raphic— many at big seving. UARANTEED on 10 Day Money Back Trial. (Used equipment accepted in trade.) Write for Free copy! CENTRAL CAMERA CO., (Est.1889) 230 S, Wabash, Dept, J-8, Chicago Stud BOUCHT- SOLD-RENTED ILLUSTRATED CATALOG tells all about this amazing service. Educational books on all subjects. offer sensational bargains. 100% satisfaction guaranteed on every transaction, Send postcard today for full details and big FREE eatalog. No obligation, PLYMOUTH SCHOOLS, Dept, 706, 432 Plymouth Court, Chicago. FREE 140 We buy for cash—we | Postmarks As Collector Items [Continued from page 86] its individual, easily identified postmark. Sometimes native postoffices have been used by occupation troops, but there have been sectors which have never had such offices. Consequently, “army posts” have had to be created. This was the case during the Boxer Rebellion and army of occupation postoffices sprang up in various sectors. such as between Peking (now Peiping) and Taku. Railroad stations generally became postoffices, Battleships and transports also be- came mail vessels! The technical story of war postmarks might fill a good-sized book. The late Dr. H. A. Cole- man compiled a splendid booklet of forty pages on the postmarks of the American armies in France. But today the booklet, though published not many years ago, is obsolete because many new types of markings have been found. These postmarks include those of places of occupation or stationing of U. S. troops, shore stations, war vessels, even of camps and forts in America. The postoffices for the troops were operated in the beginning by the Postoffice Department, but in May, 1918, they were turned over for operation by the army. Thus we find “M.P.ES.” inscribed in many postmarks of the war as an abbreviation for “Military Postal Express Service.” Opportunities For Inventors [Continued from page 63] Northill Company, Ine, explain the unique operating policy of the company this way: First of all, the inventor never has to relinquish con- trol of his invention. It remains his property and the company makes an agreement with him to pay a fixed royalty for the privilege of marketing the idea. The inventor is relieved of any and all financial responsibilities, while the company gambles its ability to pick a winner against all the preliminary expense necessary to develop and manufacture the idea into a salable item. So today there is a growing list of inventors, most of them heretofore unknown, who are being paid through this unusual arrangement. Among its highly successful products is the Northill light-weight folding anchor for marine and aircraft use, John K. Northrop, whose engineering pioneered all-metal aircraft construction, now universally adopted, is the designer of this remarkable anchor. Northrop’s interest in the organization has continued to grow and now the company retains his services as active consulting engineer and with his staff studies and passes upon all ideas submitted for possible manufacture, At least 57 of the world’s 92 chemical elements are found in steel mills. Accept No Substitutes! Always Insist on the Advertised Brand!

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The “Mechanix” Arc Welder [Continued from page 91] iron is then evenly woven into the open side of the core in order to close it. The electrode holder consists of an old electric soldering iron handle fitted with a 6-inch disc of pressed wood as a guard. Fit an 8-inch heavy copper pipe into the handle, with one of the welding cables soldered in one end and with the other drilled for the smallest size carbon elec- trode and a tightening screw. The ground con- nection is merely a heavy soldering lug soldered to the end of the other welding cable. In use, it is attached to the work with a “C” clamp. Inasmuch as this is not a high-power welder you will not require a face mask, although gaunt- lets for the hands are sometimes desirable. ‘The light of the arc is extremely harmful to the eyes, however, so you should use welding goggles with No. 8 lens, which cost from $1.25 to $2.00. Welding electrodes of 3/16-inch carbon are standard for the MI Arc Welder. Use only the smallest, flux-coated metallic electrodes. Merely touching the carbon electrode to the work will generate enough heat to cause solder to run freely at once, while by raising the electrode from the work a small fraction of an inch an intensely hot are will be created. Feeding small-size filler rod or wire into the are will cause it to be fused in- -stantly so as to weld parts of the work together. Inability to hold an are will be caused by using electrodes too large in diameter. As mentioned at the beginning of this article, the welder may be used continuously without overheating. What To Do About Parallax [Continued from page 121] If the camera is of the film pack type and is equipped with a ground glass focusing screen, these experiments will take only a few minutes. The folding-wire finders on most of these cam- eras get bent out of shape easily, so it is a good idea to check them occasionally by the target test as described. If your particular view finder shows very bad discrepancies, it might be advisable to mask it off with thin strips of friction or adhesive tape, carefully placed so as to correct the field of view. A valuable incidental feature of the target test is that it tells how far the eye must be kept from the view finder in order to see the photographic scene. Some people habitually bring the eye too close, others too far, and they are never certain as to how much picture territory they encompass. In connection with the parallax problem,. it might be mentioned that the reflecting type view finders supplied on most folding cameras above the "miniature" size suffer very little from the effect. This is due to the closeness of the finder lens to the actual camera lens, which permits the finder to intercept light rays only a small distance displaced from the rays that enter the camera. AMERICA'S 7/22 MOVIE CAMERA Richard Arlen, star of Columbia’s “No Time To Marry.” With F:3.5 Lens , . . $19.95 Why pay more for a movie camera when the lifetime UniveX costs only 39.95? Why pay more for film when UniveX Cine Film costs only 69¢ a roll—and takes theatre-quality movies at less cost than ordinary snapshots! Be smart! Be thrifty! Enjoy the thrill of taking all the personal movies you want, without counting the cost! Join the 200,000 enthusiastic fans who say, “There’s nothing like UniveX!” ~ a B " a 3 3 a 3 a a a a a a QUALITY MOVIE ACCESSORIES When you use a UniveX Cine ‘'8” you also save on accessories — for UniveX high- quality acces- sories are available at the lowest prices in all movie history! UniveX Projector Only motor-driven 8 mm. projec: tor under $26. Fifteea important features,.... $14.9 UniveX Titler Specially designed for UniveX Gai “8”. Title cards and lettering kit included..... $2.50 UniveX Exposure Meter Insures proper exposure under all light conditions... .. $1.95 UniveX Exposure Meter Case. "Dustproof... E 35e UniveX Splicer For any 8 mm. film. Makes strong splices quickly.Complete with cement........... $1.00 UniveX Flim Viewer Enables you to properly edit MOTIES, aea ern iia $1.95 Prices Higher Outside United States FREE BOOKLET UNIVERSAL CAMERA CORP. Dept. 63, 32 W. 23rd Se, New York City Send me free booklet ‘Take and Show Your Owa Movies.” Also catalogue of UniveX Cine Accessories. Name. Address. City Spat e. з тиа по ша шо ша ов шо OD тт из ай им ин иә из үн ан А ааны нан нн ан аннан нарин нарин нарин лы нынан” When Answering Advertisements Please Mention June Mechanix Illustrated 141

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DO YOU LIKE DOES THE FUTURE OF TELEVISION INTEREST YOU P ‘You men anxious to make good in radio and related industries want the true facts,—you want to know about employ- ment opportunities and requirements. National Schools, —a million-dollar trade school,—will supply you with a Send for out sincerely honest statement of facts on pice copy ante what you should do to get into the NO profitable radio industry. No exag- \ gerations,—no mis-statements, Mail coupon today, fSend for your free copy. Teal facts on radio employment re- quirements. TYou need real experience. National offers complete training with modern equipment, NATIONAL SCHOOLS Los 92/79 eguest for FREE BOOK of DETAILS NATIONAL SCHOOLS, “Dept. MMR-6, 4000 S. Figueroa St., Los Angeles, Calif. NAME ADDRESS CITY. Age AT HOME You сап 1сагп 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 positlon or start In business after completing ovr course of instruction, Good watch repairers are Іп demand and generally earn very good salarles. For par- ] ticulars apply to the WISCONSIN SCHOOL OF WATCH REPAIRING 524 E. Mason St., Dept. C, Milwaukee, Wis. BUILD YOUR OWN v Electric Outboard Motor from old auto generator. Clean—Silent. We show you how. Lightweight— Variable speed from standstill to maximum makes it ideal for trolling or casting. Operates § to 12 hours on 6 or 12 volt battery. Many other important Sp. features. Dime brings complete plans and valuable catalogue. d LeJAY MFG. CO. 514 LeJay Bldg., Minneapolis, Minn. * BOOKTET, YOUTHFUL " Enjoy the vigor that comes from relievin: machine on spinal nerves, 15 glorious minutes on Pandiculator gives pep like full gymnasium workout. Hundreds of hospitals, Sanitariums and doctors use this great spinal corrective appliance. Send for FREE booklet. PANDICULATOR CO. 416 Newman Stern Bldg.,Cleveland,O, 142 Fighting Water Famine - (Continued from page 69] just as rapidly as possible, for filling underground reservoirs is not like pumping water into a tank. It must be done gradually. Nature’s reservoirs are filed with sand and gravel, in which the water moves slowly, perhaps one to fifty feet a ! day. The new dams are to be merely tanks whence the water will be led downward by a set of giant wicks. Gradually released from the dams, it will flow over porous gravels in the old stream beds, sink- ing as it does until it has disappeared into the subterranean basins below. Engineers tailored new bottoms to the riverbeds. inventing a system of joined concrete blocks, each a foot square, slightly spaced and hinged together so as to adjust itself readily to the stream bed. Fifteen miles of this flexible apron have been built. Along the sides, workmen shot cement under high pres- sure through guns, building up a concrete river- bank three inches thick. Then 4,000 acres of spreading grounds were established, where porous gravel, hungrily absorbing water, con- ducts it downward to storage. Tunneling under the bed of an apparently dry river, engineers drove a horizontal well—a shaft from which extend many galleries. Water seeps in and is carried away in conduits. More than | 20,000,000 gallons daily are wrung from this “dry” ; Stream. Engineers viewed with jealous eyes the 127,- j 000,000 gallons daily pouring through the city's great outfall sewers—half again as much as the combined flow of the country’s three largest rivers, Of this volume, 9,996 parts out of each 10,000 are water. The engineers begged permission to ex- periment. Erecting a plant in one of the parks, they turned the raw sewage into tanks where it was scientifi- cally treated. Great paddles broke up the sus- pended “sludge.” Then yeasts and chemical reagents were added. Bacteria and microscopic fungi “digested” the organic material—literally burned it, by oxidation, to cinders. Chlorine and lime aided in the work of this giant stomach, which also produces valuable by-products. Gases evolved in chemical reactions provide fuel to turn the machines. The odorless solid remnant, dried and pressed into cakes, is sold as fertilizer. Water entering the plant contained 7,000,000 bacteria per cubic centimeter. On leaving, it had but 100. Pure drinking water may contain ten times as many, yet comply with legal require- ments. Chemists at the plant drink treated water and say it is purer than water from the ground. But the public would not drink reclaimed sewage, ! so the liquid is turned into spreading grounds, whence it filters through the earth to add its bit to the underground lakes. A large quantity of the camphor used is made synthetically from turpentine. Accept No Substitutes! Always Insist on the Advertised Brand!

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Microscope Slides [Continued from page 105] form of jelly glass is satisfactory. Retain the tin caps so as to keep your reagents covered. Pour the fixer into such a glass until nearly full, then put in the material to be fixed: for example, a tree bud such as we used for discus- sion in the May issue of Mopern Mrecuanix. The length of time for fixation -varies, but formol- acetic alcohol is very flexible and it is almost impossible to overfix with this reagent. "Over- night to twenty-four hours" is a frequent statement in the technique manuals, and may be regulated to suit one’s personal time schedule. Washing comes next and unless otherwise specified, this is to be done with tap water. A glass of water may be used, changed a number of times over the period of washing, which is the same length as that of fixing, the purpose be- ing to rid the tissue of all excess fixer. If a wa- ter tap is available in the workroom, however, a much better method is to rig up a running water washer, as follows: Select a wide-mouthed bottle of capacity from one pint to one quart. Bore the cork stopper with two holes for glass tubing, a long piece to reach almost to the bottom of the bottle, and a short piece which goes just through the cork. Hook up the long piece with rubber tubing to the faucet, and the short piece with rubber tubing which is for overflow and reaches to the sink. [Continued on page 158] Wet, Dry Bulb Thermometer [Continued from page 87] in a chemical supply house, or in some hardware stores. Using a bunsen burner, heat one end and shape it as shown in the photograph. The wick can be a corset string or any similar material. Briefly, the operation of the thermometers is as follows: When the liquid around the end of the thermometer evaporates, the bulb is cooled, thereby causing a lowered reading. The rate of evaporation depends largely on the amount of moisture in the room. The rate of evaporation controls the tempera- ture of the wet bulb thermometer, thereby caus- ing a difference in the readings of the two ther- mometers. If there is considerable moisture in the air, the rate of evaporation will be less than if the air is very dry. Therefore, in dry weather, the dry bulb reading may be 100 degrees, while the wet bulb reading will be 88 to 90 degrees. On damp days, the readings of the two thermometers may be almost the same, the wet bulb reading be- | ing but one or two degrees below the dry one. Distilled water should be used in the tube to prevent deposit on the wick. The mineral con- tent of tap water after several weeks of use may result in a substantial deposit on the wick, thereby reducing the accuracy of the reading. When Answering Advertisements Please Mention June Mechanix Illustrated | For Extra. сепгаеу 51һоос Хрегї .22°6:, NN ESTERN XPERT Long Rifle .22’s give extra accuracy without extra cost! Your shots go where you intend them to go. Buy XPERT for target marks- manship and all-around shooting. The .22 Short and .22 Long have comparae ble accuracy, CLEAN ammunition! Smokeless! Non-Corrosive! Lead lub- ticated bullets! Mail the Coupon now! Western Cartridge Company, l Depr. F-105, East Alton, Ill. | Send, FREE, the 72-page Western ааа е I | Handbook. A complete shooting guide. Tells all | about all Western cartridges and shot shells. | Names sexes eee sg signed gin deed Aye wan [Raa tees on Ses Ор ано Айри ыкы асры Ld | Post 101,7 — Бта PPP I 60 POWER TELESCOPE $2.19 VARIABLE EVEPIECE. 20X—40X—60X NEW! Three telescopes Inone. 3 different mage = nifications. 20 power for ultra-bright images with 40 and 60 power Pr otis long tange. Guaranteed Ac ring gintan rts events, for a ar the money, | Closes o lees than a. foori in length. Multiple lena syete: eui 90 mm. objective, in heavy н тава mount. Directions Included for using as a compound 4 lens microscope., American made, We pay the postage. Only $2.19. Catalog of Microscopes, Binoculars, eto. FREE on request. BROWNSCOPE CO., Dept. 76, 5 W. 27th St., ‘New York, Ne Yo the major cool of science, is a fascinating and educational home hobby for thousands. You, too, can explore the mysteries of the un- seen world, through the magic of the microscope. Bausch & Lomb precision amateur microscope Model R (left), 75 to 300 power; with 455-page book, $21. Osher models, $14.50 up. SEND FOR FREE BOOKLET (right). Bausch & Lomb Optical Co., 244 Bausch St. Rochester, N. Y. & 143

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GAS SOLDERING- TORCH for HOME Connects bo Home Gas Supply NO vr * NO Acetylene * NO Air Only $5.95 Postpaid. — FREE LESSONS On high strength sil- ver soldering, also soft soldering; by Prof. of Engrg, BS in ME, years of practical ex- perience. Free with S S тйтп torch, or $1 alone. Amazing speed in soft solder work, but especiall adapted to silver soldering which gives high os joints of 50,000 pounds per sq. inch. Use on steel, copper, brass, bronze, silver, gold, cte., wherever gas is available. Earn money fabricating models, toys. Make home repairs. Pays for itself easily. Price includes silver solder, flux, extra tips, postage. Patent Pending. Choate "Torch Co. 4 3464 Principio, Cincinnati, Ohio. WIND DRIVEN Electric PLANT Build Your Own—We Show You How 5 Make auto generator light bulldlngs, play radlo, run washing machine and other motors from FREE WIND POWER. Earn money making for others. Dime brings complete building plans and 198§ catalogue listing over 500 windcharger electrical items, Most complete wind- charger catalog; welders, electric fence, ete., over 100 other generator changes into 6-12-32 and 110 volt plants, LEJAY MFG. CO., 414 Lejay Building, — Minneapolls, Minn. TOOL OF 1001 USES Í ACTUALLY A WHOLE SHOP BFULL OF TOOLS IN ONE Se | Uses 200 different accessories, in- P i М $ stantly interchangeable in easy- sd B working chuck. For faster, Engraves H better work on all materi- Sharpens als, at home, in shop, Carves B or take to job. Plugs Cleans in any AC or DC Sands socket, 110 volts, Cuts = You'll be amazed at Ч Bits unmatched perform. Saws 8| ance, precision and almost T human response. е STANDARD MODEL 6 13,000 r.p.m. Weighs DE LUXE MODEL B 16 oz. $10.75 post. 25,000 r.p.m. Fastest, smoothest, ү paid with 3 Acces- mos* powerful tool for its type and sories. weignt, 12 oz. $18.50 postpaid with 6 Accessories, GET A DEMONSTRATION at Hardware, Tool or Dept. Stores, or let us send either model on 10-days Money-back Trial. Catalog Free. New ROUTER and SHAPER Convert your De I,uxe Handee into an easy-to-handle Router or Shaper that will inlay, rout, carve, make molding cuts to 100th of an inch CN $12.50. „Пері. Н, Chicago, Wt. B Send Catalog ti Router-Shaper S O De Luxe Model O Standard Model O Send C.O.D. Name | cork about the size of a marble. ! placed inside the bottle previous to your per- Tricks With Bottles [Continued from page 134] The cork is formance of the trick. To perform, push one end of the rope into the neck of the bottle, then invert the bottle as shown in the picture, holding the rope in place so that it will not fall to the floor. The piece of cork will roll toward the neck, and a slight pull on the rope will cause the cork to enter the neck slightly and wedge between the glass and the rope. You can now release the rope and allow it to remain suspended from the bottle. Then grasp the free end of the rope and allow the bottle to hang. Swing it back and forth several times to make the trick look more effective. The audience is amazed because they cannot imagine what is causing the bottle to remain fastened so tightly to the rope. Pushing the rope slightly into the bottle will dislodge the cork and allow you to remove the rope. Hand it out to someone in the audience. The bottle is held by the neck in the left hand and while everyone is looking at the rope, tilt the bottle slightly and permit the cork to drop into your palm. Then hand the bottle out for examination and leave the piece of cork in your pocket. "Mechanix Illustrated" In The Movies [Continued. from page 71] starting actual "shooting." The full technical and creative facilities of the Vitaphone Studios, headed by Mr. Sam Sax, are being put behind the MECHANIX ILLUSTRATED pictures. Few plants in the motion picture indusiry are better fitted for this difficult work than the Vitaphone unit, which covers an area of several square blocks in Brooklyn, N. Y. Here are four huge sound stages, equivalent to Hollywood’s best, with the very latest camera, lighting and processing equipment. The studios include one of the world’s largest film laboratories, where the countless negatives of all Warner Brothers and First National feature pic- tures are printed and distributed to more than 16,000 theatres. The new "Vitaphone-MECHANIX ILLUSTRATED "shorts" are directed by Ira Genet, who has pro- duced many popular and successful movies of this type. Look for them at your local theatre! Thirty years ago coal supplied 89 per cent of the United States’ fuel energy; now it supplies only 50 per cent. Geese as well as aviators can lose their bearings in a fog, judging by reports of geese seen in Great Smoky Mountains National Park, Accept No Substitutes! Always Insist on the Advertised Brand!

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Spring Overhaul On The Boat [Continued from page 102] With the varnishing finished, turn attention to the painting, starting first with the uppermost part and working down because you are bound to drop some paint, and should this land on a freshly painted surface below where you are working there is a mess of both words and paint. The best instructions for painting are issued by the manufacturer of the paint that you are using and are generally printed on the can. Follow these to the letter! The manufacturer of the paint wants |; his product to show at its best and has had ex- peris in this line write these instructions for him. | Between coats, treat your brushes with the fact | in mind that they have a long life before them if properly cared for. If you have to purchase them new be sure that they are good ones. Your paint salesman will advise you of the best types for the particular work you wish to do. In choosing your colors be sure that they do not clash. An exami- nation of the boats around you will suggest quite a few good color schemes. Don't use blue paint for the decks just becaus2 you have a lot on hand. Buy some yellow and turn it to green, which will be much better on your eyes and your neighbor’s disposition. At all times have a rag soaked in turpentine ready for use so that if you smear two different [Continued on page 161]

Master Finish [Continued from page 111] sufficiently good condition to support the new coats. Repaint- ing over dirt and oil or grease spots will not only spoil the eppearance of the new job, but may later result in peeling and checking. Be sure that the surface is clean! If the old paint is in bad condition, scrape or burn it off until a firm foundation for the new paint is secured. When old paint is burned off with a blowtorch, be sure to get the written per- mussion of your fire insurance company. If the wood is mildewed, clean it with a pound of tri-sodium phosphate dis- solved in fifteen gallons of water; then rinse the surface well with a hose. On new surfaces go over all knots and shiny spots with a coat of shellac, which will prevent pitch in the wood from coming through the subsequent coats of paint. On both new suríaces, and old^ones on which the wood has deteriorated until it soaks up paint like a sponge, the following is a good "priming" treatment that will assure a good foundation. Three thin coats of paint are used. Thin the first with equal parts of raw linseed oil and good turpentine (not turpentine Substitutes, by any means, as they invariably cause trouble later). This priming coat will sink directly into the cells of the wood and seal them effectively to a considerable depth. Thin the second coat with raw linseed oil. For the third coat, apply the well-mixed paint, and brush it out well. Keeping the paint well mixed is one of the secrets of good work. A wood paddle in the pail and occasional stirring is all that is necessary. When you open a fresh pail of paint, the ritual that has proven most effective is: pour off the clear oils that have gathered at the top, then vigorously stir the settled pigments until they are of an even, creamy, consist- ency. Pour back a little of the oils at a time, stirring mean- while. Afterwards “box” the paint a half-dozen times by pouring it back and forth from one container to another. After you have finished painting, and the remainder is to be stored for some time, a good trick is to tap the lid well in place, then store it away upside down. This will seal any possible crack through which air might enter and cause the oils to oxidize or thicken, New brushes for exterior painting should be soaked for a day beforehand in equal parts of pure turpentine and raw [Continued on page 146]

WHEN a car overheats—you lose power. You are headed for more serious trouble. Clean out radiators regularly, twice a year. You can do it yourself with Sant-Fiusu. It takes 10 minutes. It costs 10c. (25c for the largest truck or tractor.) Sanr-Frusn is a scientific preparation that removes rust, scale, sediment and sludge that clog radiators. Just pour a little in the cool- ing system. Follow directions on the can. Run the motor. Drain. Flush. Refill with clean water. That’s all! The delicate veins that circulate water are clean and open. The motor runs cool Samr-Frusnm is perfectly safe. Can't hurt engine or fittings. You'll find Sawr-FLusH in most bathrooms for cleaning toilets. Sold by grocery, drug, hard- ware, and five-and-ten-cent stores. 25c and 10c sizes. The Hygienic Products Company, Canton, Ohio. Sani -Flush KEEPS RADIATORS CLEAN

of my cruiser?’

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Complete 18 Make every step easy and full of fun. Seaworthy dream boat come true. today. SEATTLE MODEL BOAT CO. Dept. D, Box 333, When Answering Advertisements Please Mention June Mechanix Illustrated <t’s fun—and,. boy, am ] proud Say enthusiastic Plans in Color..... . 35¢ You'll thrill to see your Send 35c (stamps or coin) Seattle, Wash.

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NEW HEAVY BODY 3-IN-ONE OIL WILL | GUARD THIS Heavy Body 3-In-One Oil is made especi- ally for light motors, lathes, lawn mow- ers, washing machines, refrigerators, etc. Same uniform high quality as regu- lar 3-In-One Oil-famous for 44 years. Triple-action—it LUBRICATES, CLEANS AND PREVENTS RUST. od АТЛА 3-IN-ONE OIL “ALNICO” MAGNETS uokse tober BAR Newest and Most Powerful Magnetic A«oy | В Our 4 oz. ‘‘Alnico”’ horseshoe magnet will lift about SO times its own weight of soft iron. Many startling as well as_ interesting and useful experiments can be performed with it. With two of these magnets all the well-known experiments with permanent magnets may be performed. ATTRACTION AND REPULSION PROPERTIES IN THESE MAGNETS are greatly magnified. EX. AGGERATED AND STARTLING RESULTS CAN BE HAD. Gravity even may be defied. Catalogue 10c. a Horseshoe....... FE Oh $1.00 each postpaid No C.O.D. . .$1.50 per set postpaid No Stamps HARRY ROSS Scientific and Laboratory Apparatus 82 West Broadway, Dept. A, New York City Minnows. Eels, rats, etc., in large numbers with our Folding Galvanized Mink, Musk- i STEEL-WIRE TRAPS. They Кэз ЖО Catch Fish! atch rish: catch them Iike a fly-trap catches flies, Write for our FREE TRAP OFFER, bargain catalog and other specialties, SURE LURE, makes _'’em bite day or night. New principle used, it coaxes fish, Put up in tubes 5 inches, Price 30¢. 4 tubes for $1. P St. Louis, Mo. ROMANCE WRECKED BY UGLY PIMPLES? Here is how to help keep skin- irritating poisons from your blood Don't let repulsive-looking hickies rob you of charm -..ruin your chances for friendship and affection... Spoil your good times. Find out what the trouble may be, and take steps to correct it. А During the years of adolescence, from 13 to 25, important glands are developing. These gland changes upset your system. At the same time intestinal waste poisons are often deposited in the blood stream, and may irri- tate the sensitive skin of your face and shoulders, Pimples break out. Fortunately, there is a way to help keep these skin-irri- tating poisons out of your blood. Eat Fleischmann’s Yeast, 3 cakes a day. The millions of tiny, Living plants in each cake of this fresh food help to remove the wastes the nat- ural way and clear the skin of pimples. Thousands of young people get results in 30 days or less. Act now. Get Fleischmann's Yeast and eat it faithfully. See how your Bkin clears up. ——————————— À 146 Master Finish [Continued from page 145] linseed oil. A 4-inch brush is suitable for general use, and it sbould be augmented by one two-inch wide for working in corners and painting window frames. A one-inch flat sash brush is also desirable. It is poor economy to purchase cheap brushes, which are liable to shed their bristles and make the work more difficult than it really is, Outside painting is best done when the temperature is be- tween 40 and 80 degrees F., with fair weather expected. Start on the north side of the house, as early as possible in the day, and work around the house so that the sunlight is always ahead. It is a mistake to wait until the first coat is absolutely "dry bone" before applying the next; wait only until one coat is hard, then apply the next so that there will he a secure bonding of the two paint films. Fill the brush only partly full and brush it out well so that every minute pore and crevice is reached. Most interesting of the new devolopments in paint manu- facture during recent years is that having to do with enamels, and of course the varnishes from which enamels are made. Formerly consisting of various fossilized plant gums (as in the case of shellac, an alcohol varnish which stil] finds wide use), these modern finishes are made up with synthetic gums and resins which are a product of the chemist's laboratory. The pre-treatment of a surface to be enameled or to be varnished is quite the same, excepting that the transparent varnish may require an undercoating of stain. In either case, hawever, there is one fact that is of prime importance. The finished work will be no smoother than the surface on which it is applied. If this important point is remembered, half of the enameling or varnishing problem is solved. Particularly in the case of enamels, a glass-smooth surface having the appearance and feel of porcelain is desired. Modern enamels easily attain that objective and as a consequence they are ideal for brightening up the kitchen, bathroom, clothes closet; for application to practically any interior woodwork and furnishings. A damp cloth is all that is required for keeping such surfaces clean. . When the old finish appears to be in good condition and merely suffers from wear, it can be prepared for a new coat of enamel or varnish by the careful use of No. 00 sand- paper, Be sure to remove all scratches. If the old finish is badly worn, checked or marred, it should be entirely removed with either paint remover or hy sanding. When the bare wood is revealed you may find that it has been stained; in this case, Bive it a thin coat of shellac so that the stain will be pre- vented from working up through the new finish. When a new surface is to be varnished, the first operation is usually that of staining. Oil or water stain is not diffi- cult to apply; the former is more suitable for soft woods and will not swell the- grain of the wood. On the other hand a good water stain will give a richer appearance, and it is more permanent as it is less subject to fading. Before applying the latter, sponge the new wood with water, allow it to dry thoroughly, then sand it perfectly smooth, The stain should be tried first on a piece of scrap wood to determine the shade, and if desired it may be diluted with a little alcohol to secure greater penetration, In applying it to the work use a wide brush and quick, long strokes with the grain. Never go over the surface twice. If the surface is of open-grain wood, speed in applying is essential if you wish to avoid too deep a color. The appearance will be more uniform if you immedi- ately go over the work with a clean cotton (not woolen) rag. After the wood is thoroughly dry it will probably require a light sanding; then dust it thoroughly and apply a sealing coat of thin shellac. For that desired glass-smooth finish, open grain woods (such as walnut, oak, chestnut) should next have an appli- cation of paste filler. This must be thinned with turpentine or benzine so that it is of the right consistency to fill the open pores of the wood, as determined on a scrap piece. Use a somewhat stiff brush and work it well into the wood as if you were using a shaving brush. Almost immediately the filler will commence to set and then the surplus must be wiped off immediately with a clean cloth. This will be difficult if you wait too Jong. After the work has dried for at least thirty-six hours, smooth down the surface with fine sandpaper. The ultimate smoothness of an enamel or varnish finish de- pends considerably on the type of brush that is used, and a brush that appears to be a bargain when examining the price ticket will be found anything but that when you examine the result of your decorating efforts. It is good economy to pur- chase a good quality soft fitch brush, one two and one-half inches wide for general work and one one and one-half inches wide for narrow surfaces. Petroleum got its old name "Greek fire" after the Greeks burned a Scythian fleet by pouring oil on the sea and igniting it. Accept No Substitutes! Always Insist on the Advertised Brandt

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The "2-3" Portable [Continued from page 117] "Тһе circuit of this receiver is not the least bit complicated. The first tube, the RK-42, is used as a regenerative detector and is sensitive and smooth in operation, The other “dual-tube,” the RK-43 is used as two stages of audio frequency amplification, which provide more than sufficient volume for the earphones. The earphone jack is mounted between con- densers C2 and, C3 on the front of the set, and is insulated from it by fibre washers in back and front. Resistance coupling is used in the af. amplifier in order to cut down weight, as audio trans- formers weigh considerably more than the resis- tors and the fixed condensers, Regeneration in the detector is controlled by a 140 mmf. variable condenser, C3. This throttle condenser method, as it is commonly termed, pro- vides smooth control and is more economical than the potentiometer method, because it imposes no drain on the "B" batteries, Variable antenna coupling is obtained through the use of a 35 mmf. variable condenser, C2, con- nected between the antenna and the grid side of the plug-in coil. This condenser must be in- sulated from the front of the cabinet by means of fibre or bakelite washers. Make sure the mounting stud does not touch the metal of the cabinet. The main tuning condenser, Cl, is mounted directly on the front of the box or carrying case. By mounting the plug-in coil directly behind the tuning condenser, short leads can be used. Plug- in coils are used because they take up less space than a band-switching assembly. For conveni- ence in changing coils, there is a hole in the top of the case directly over the coil. A circular cover swings over the hole to keep out dust and to increase shielding. As for performance, this little portable leaves nothing to be desired. Short-wave stations from [Continued on page 148] Method Of Making Pitchers [Continued from page 118] copper, and should be driven in to prevent leak- ing. The taller pitcher is made from a 534" length of the same tubing. This, however, is driven in slightly at the bottom, and the top is expanded. The spout, the throat of which reaches nearly the entire length of the pitcher, is formed over a length of 58” round iron. The top of the pitcher is flared slightly all the way around. The bot- tom is soldered in, and the handle riveted on as before. The pieces are thoroughly cleaned with commercial nitric acid, washed, and highly polished. 'The finished pitchers may be chrome or silver plated if desired. When Answering Advertisements Please Mention June Mechanix Illustrated PLASTER FOR PATCHING THAT ANYONE CAN USE / Holes in walls are easy to repair with Rutland Patching Plaster. Makesa per- fect, lasting patch. BRONZE BEARINGS BALL BEARINGS THRUST COMPLETE AS SHOWN Weight 25 pounds—20 inch bed—12 inch between centers—5_ inch sw ing—3 inch | bronze bearln, Hollow spindles—Takes all No. OsMorse you could not buy for double the Better Built - Lower Prices Only Boats With Full Length Spray Rails Keep passengers perfectly dry—even at high speeds. Catalog also shows today’s five most popular models of sailboats. Two big facto- ries. Prompt shipmesic. Write f. aere FREE. kind of тс! ate Kin 5 boat! in Wh dcn you are interested. Very fast utility model o THOMPSON BROS. BOAT MFG. CO. (9? (either place) CORTLAND, N? Vo n St PÉSHTICO, wis. 147

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TEN-DAY Tia Guarantee :10 Months To Pay ' ; it ig EASY for every inventor, home workshop owner, laboratory, garage, repair shop, and factory to afford @ complete welding service for manufacturing, maintenance, €x- | perimeniai or repair work, Full size, heary-dutv Electric Are [ Welder—Commonwealth Model : ;36-FS-—yours for only 22c a day! Has efficiency of machines costing $250.00 to $1,000.00, Welds ali metals and alloys. Six heats handle everything from fenders and light sheet metal to motor blocks and heavy castings, Also Ane for soldering and brazing. WORKS ON 110 OR 226-VOLT A. C. Simpiy piug into 110 or 220-voit. 60-cycle A. C. ‘electric socket. Gosts only few pennies an hour to operate. Anyone can use easily. Comes complete with helmet, electrode holder, welding rods, full instructions, etc. Nothing else to buy. Fully guaranteed. WRITE FOR 22c A DAY PLAN Siop throwing away profits! Do your own welding. vienal facts about Model 120-FS and 22c-a-day plan. COMMONWEALTH MFG, CORP. 4208 Davis Lane, ELS Get sensa- Write todayl

Dept, J-52. Cinclnnatl, 0. INA WEEK g cash profits for you; full or spare pi. time? пе ver 250 household necessities— things people must buy. Proven fast Sellers: steady repeaters, earnings very 4 first да; FORD. TUDOR SEDAN GIVEN es YOU AS BONU; Il] show you how tc start á at once: send you everything—Big Display Out. y ft and quick’ cash plans. Details FREE—no obligation. Just send name on postcard. ALBERT MILLS, 5195 Monmouth Ave., Cincinnati, 0. í .Согге<ропбепсе Сойгвев 1п SPECIAL ES PER ERU SLE SS L1 3 4 LU $5 E EB" ELECTRICAL ENGINEERING 9%, хоо, gra 25 of wide electri- tal eid. Prepare ourself, at Low Cost, for secure future. Modern уопе сап understand quickly, RADIO ENGINEERING Extra fine course In radio, public address, photo-electric work. Trains you to be super-service man, real vacuum tube technician. Expertmental kits furnished. Diploma given on completion. Tuition, ONLY $25, either course. Deferred payment plan available. ' Send name quick for free copies of sehool catalozs a student magazines, complete details, SEND N LINCOLN ENGINEERING SCHOOL, Box 931 Lincoln, Ne

We paid M. M. $1174 for exceptional ‘‘cel- lar erop" SNOW KING mushrooms! Big free picture book tells if your cellar, shed, . barn, suitable. We furnish materials, buy all crops through our 25 branches, Write today for ‘Guaranteed Success Plan” backed by $5000 bond, Est. 1908. UNITED MUSHROOM Co. 3846 Lincoln Ave., Dept. 315, Chicago. PREVENT BALDNESS! ational new Vacuum Helmet stops falling hair, fills in ў spots. grows new hair on your head or it costs you scathing. Scientific principle. Send name for facts, price, termes. trial offer and guarantee, all Free. HYDRO-VAC. bne.. Dept, 246. Walnut Bldg.,

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Send postal for FREE BOOKLET of 381 different FrREWORK BARGAINS PARAMOUNT FIREWORKS CO., c. 213 East 42nd St., New York Cily

The "2-3" Portable [Continued from page 147] all over the world have been received with ex- cellent volume. The antenna used was a short piece of wire about 20 feet long. No ground was employed, although the use of one is strongly recommended, as it eliminates all possibility of body capacity effects. The ground wire, con- nected to a water hydrant, a drain pipe, or a metal stake driven in the earth, is hooked under any of the mounting screws of the metal cabinet. While this receiver was designed for the short- wave listener, it is a good portable for the ama- teur. The only thing lacking for the “ham” is band-spread.

LIST OF PARTS Hammarlund: 2—140 mmf. Micro cendensers (C1, C3) 1—35 mmf. Micro condenser (C2) 1—2.1 mh. choke (RFC) 2—4-prong isolantite sockets (for plug-in coil and RK-42) 1—6-prong isclantite socket (for RK-43) J—Set SWK 17-240 meters coil kit (four 2-winding coils) LR.C.: 13. -meg. 14 watt resistor (detector grid leak) 2—'% meg. % watt resistors (audio amplifier grid leaks) 2—50,000 ohm, % watt resistors (plate resistors) Cornell-Dubilier: 2—.01 mf. paper condensers 1—.0001 mí. mica condenser 1—.0005 mf. mica . condenser 1—.006 mf. mica condenser Raytheon: 1—RK-42 tube 1—RK-43 tube National Carbon Co.: 2—Small 45-volt “B” batteries, No. 738 1—Small 3-volt “A” battery, No. 723—(It i is necessary to rewire the four cells of this battery in parallel, to give 1%4 volts. This is a simple job and takes only a few minutes.) Wholesale Radio Service Co., Inc.: 1—Portable metal case Miscellaneous: i 1—phone jack, single open circuit 1—small dial, National Type BM. 2—knobs for C2 and C3 1—S. P. S. T. toggle switch 1—pair earphones, with phone plug

Earth Bulge Causes Quakes The enormous bulge in the earth that has its crest in the Himalaya mountains is responsible for the terrific earthquakes that sometimes rock interior Asia, Prof. D. Mushketov of the Lenin- grad Mining Institute states, after extensive ex- peditions in which thousands of observations were taken. The deep-seated forces pushed up the crust of the earth in this region as a man in bed pushes up the covers with his knees. Like the covers pulled over the knees, the thick blankets of rock are under tension. They give way from time to time, and that starts the earth- quakes. Accurate measurements made by Pro- fessor Mushketov show that in the Pamir region the curvature of the earth is much in excess of the average curvature of the earth as a whole.

“The stinkwood” plant yields a fragrant distil- late that may prove useful in perfumery. ccett No Substitutes! Always Insist on the Advertised Brand!

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Steel—Backbone Of World [Continued from page 47] with cold or molten pig iron, cold scrap, or any combination of these. Limestone is added as a scavenger. Floating on the molten metal as slag, it absorbs all impurities. Chromium, nickel, vana- dium, manganese, or any other alloying elements may be added to the charge at will to produce the type of steel desired. The charging is done by enormous mechanical arms, which pick up accurately measured con- tainers of cold materials, insert them through automatic doors, and invert them to dump their contents. Molten metal is charged by pouring from a huge ladle into a portable spout. If a housewife was to meke a cake as accurately as steel is made, she would have to measure the ingredients by ten-thousandths of ounces, and single grains of sugar. She makes only a pound or two of cake; a typical open hearth furnace makes a 200-ton batch of steel at one heat. Her oven reaches a maximum of 500°F. Steel bubbles in an open hearth furnace at 3,000°. There are now nearly a thousand varieties of alloyed steels, the ingredients of which are con- trolled within a thousandth of one per cent, yet prior to 1900 there was only carbon steel, with various percentages of carbon. Henry Ford is credited with forcing the steel [Continued on page 151] Drive Next Year's Car Today [Continued from page 78] engine when, and if, the car capsizes. Many trucks and buses are equipped with this device. It, too, is very inexpensive. In your special touring kit there should also be a new gadget known as a “lamp glove.” With this handy device you can remove broken lamp bulbs without the danger of cutting your fingers. It also removes lamps that are not broken but which are likely te break when you apply pres- sure. One of these “gloves” should be in the kit with your spare bulbs. It takes up little room. It’s part of tomorrow’s car. In the realm of the engine there are a lot of devices that will put any car years ahead Consider for a minute the situation in lubrica- tion. With one of the oil clarifiers and motor cleaners it is possible to keep lubricant in such shape that one filling, plus necessary additions, will be good for 8,000 miles. These clarifiers do require more frequent cartridge replacement than do regular oil filters, but savings in oil more than offset this. Clarifiers follow the theory of many engineers that well used oil, if kept clean, is beneficial to the engine. Of course if you do not feel like accepting this admittedly uncon- ventional theory you can at least treat yourself [Continued on page 150] When Answering Advertisements Please Mention June Mechanix Illustrated € PappLE the peaceful paths of beauty — with rippled reflections and dreams. Spend peaceful days on the waterways. Glide through the glories of Nature. An Old Town Canoe is easy to paddle. Quick to respond to the blade. True Indian lines — made steady and strong. Built for long years of hard use. FREE CATALOG shows all kinds of Canoes for paddling, sailing or outboards. Also Out. board Boats, including big all-wood family boats, Rowboats. Dinghies. Write today. Ad- dress Old Town Canoe Company, 466 Main Street, Old Town, Maine, MARINE CONVERSIONS FOR FORDS 4 AND 8 CYLINDER—ZEPHYR V12 FORD v8 SUPERCHARGER Full Marlne Conversions and Accessories Sendlóc | For Complete Catalog Learn how you can build up a profitabla spare or full-time business in your own home. This new book “How to Make Money in Woodworking’ is crammed with practical tested ideas, plans, and suggestions, Tells you exactly what to make, how to make 3t and how to sell 1t, Describes plans (hat have worked for others, Woodworking, the new way, ia light, pleasant, and profitable. Send only 10e and complete book will be Satisfaction guaran- Write to mailed postpaid, teed or money refunded. Dept, M938. 600 E. VIENNA AVE.- "MILWAUKEE, WIS--

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TION Men Southern California, world's aviation center, needs trained men to build and fly planes, Only trained men accepted. Get quicker, lower-cost training at California Flyers, leading flying- mechanical school in this great aviation center. Secure steady employment, make big money, get the thrili of a red-blooded job in aviation. CALIFORNIA FLYERS LOS ANGELES, CALIF. Send for California Flyers FREE Book California Flyers, Los Angeles Municipal Airport, Inglewood, Calif. Name. Address. State. MM6 eee T and EIS to 2% ina T Let me send you a fine all-wool union tallored suit FREE OF ONE PENNY COST. Just follow my easy plan and show tbe suit to your friends. Make up to 312 in a day easily. No experience—no house-to-house con- vassing necessary. Send for Samples—FREE OF COST Write today for FREE details. ACTUAL SAMPLES and *'sure-fire'" money-rettine& plans. Send no money. J. Collin, PROGRESS TAILORING CO., Dept. F-137, нё South Throop Street, Chicago, Wlinois. АКТОМ YOUR WAY Pr Success! 2S. DON’T COPY - LEARN TO ORIGINATE! RAYE BURNS will teach you HOW to CREATE ORIGINAL CARTOONS ac home that you can 355 85 SELL! Course has 26 lessons and 600 illustrations. Send name and address for free details. Only.. RAYE BURNS SCHOOL, Dept. F, Box 2194, Cleveland, Ohio Write for free booklet describing "107 Plans for B Operating a Successful Business of Your Own”. B Make from $20 to $100 a week starting in spare No peddling or house-to-house selling. Write for 8 REE BOOK ] time at home. i — B Booklet sent free, and without obligation. M your copy today. ELITE PUBLISHING CO. Dept. G. 214 Grand St. Мем York, N. Y. Every dea£ person knows that« Mr. Way made himself hear his watch tick after or batteries. Write for TRUE STORY. Aleo beoklet on Deafness, ArtifictalEar Drum THE WAY COMPANY 741 McKerchey Bldg. Detrolt, Michigan CHEAPER T E M N | Earn Money, Too ! NOW-—vou can buy Wills’ fresh, genuine Eclipse SPLIT GUT tennis strings direct-from-factory for as little as $2.25 PER SET postpaid. Also—ex- cellent quality SILK at only G5ec per 37 ít. coll, wostpaid. Rush | your order now! Satisfaction GUARANTEED. New 1938 CATALOG of Tennis Frames, Vises, equipment now ready. Get your FREE copy. Sénd today. H. E. WILLS CO., Dept. 47th St., CHICAGO, U, 5. A-235, 1047 W. Accept No Substitutes! Drive Next Year’s Car Today [Continued from page 149] to one of the new filters which is conveniently cleaned by the simple process of rotating the cleaning blades. And then when you want to drain off oil the ideal thing for the job is an automatic drainer. This is a special plug which replaces the engine's original drain plug. It is equipped with a remote control, so that by lifting the hood and inserting a key the owner of the car can drain off a portion or all of the oil anywhere he pleases. For re- moving crankcase diluent, which settles at the bottom, this is a handy proposition. It also helps the owner when he wishes to thin out the crank- case contents, or make it of a heavier average grade, by adding a quart or two of a different grade. For the lower end of the radiator overflow pipe there is a new gadget to prevent spilling the cooling system’s contents. That means less loss of anti-freeze in winter, and less chance of over- heating in summer. Now that so many cars carry the battery under the hood it is a simple matter to install one of the new automatic water feeding systems for the cells. For the carburetor there are various mileage boosters, not to men- tion some attempts at supercharging. The latter is costly if desired in genuine form, but anything that helps the engine “breathe” improves what engineers call its “volumetric efficiency.” Ac- cessory stores carry adaptors so that if your present engine uses the older type, larger spark _ plugs you can enjoy greater ignition efficiency by installing 18 mm. plugs. There appear to be endless ways of making your present car aS modern as you please, and no end to opportunities in the direction of in- dividuality. You can ride a dust storm with the new air conditioner and come out without a sneeze. You can gain more attention from those who follow by the simple process of replacing the conventional stoplight with a wig-wag lan- tern. A bumper jack in the tool kit saves all the annoyance of struggling to place the jack under the axle. Women motorists will appreciate the thrill of opening the glove compartment and discovering an illuminated vanity mirror on the inside of the door. And, incidentally, you can buy a keyless combination lock for this compart- ment. You will enjoy an altimeter for traveling in the mountains, and it will help you in understanding why the car behaves the way it does when handi- capped by a lower oxygen content. In your car of tomorrow, which we are offering you today, you do not have to guess at anything, much less gasoline mileage. There’s a new fuel meter for the instrument panel. Any half dozen of the newer devices mentioned will go a long way toward making your present car a close cousin to the creations which automobile designers now have on their drawing boards. Why wait? Always Insist on the Advertised Brand!

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Steel—Backbone Of World [Continued from page 149] companies to produce alloys on a quantity basis. He wanted to make a light, durable car, one within the reach of every man. Carbon steels were too heavy when strong enough, and lacked the desired fatigue resistance. Ford shopped among the big companies in 1907, but they refused to produce large quantities of the kind of steel he wanted. Republic Steel, then a young concern, agreed to meet his demands. With the new vanadium steel, Ford produced a car weighing 1,250 pounds, changed the auto from a plaything for the rich to cheap transportation for the masses. While the open hearth furnace produces most of the alloy steels—and nearly all steels are alloys today—stainless and heat-resisting steels, and other of the highest quality alloys, are made in electric furnaces, the first of which was built in this country in 1906. The electric furnace is a circular steel shell mounted on rockers, and resembling a huge tea kettle. It is brick lined, with a clay-lined spout for tapping, and doors for charging. Two enormous carbon electrodes project through the roof, and the current, arc-ing through the slag to the metal, produces an accurately controlled heat which may reach as high as 3,800?F. The metal being hotter under the electrodes than near the walls, the mass is kept in constant motion, so is thoroughly mixed and uniformly heated. The typical electric furnace has a ten-ton ca- pacity, and turns out three or four heats a day. The Bessemer process takes only 15 or 20 minutes, and a single converter can produce 2,800 tons a day. Open hearth furnaces produce up to 250 tons of steel at a heat, which requires 10 to 13 hours. Unless steel is made into a large casting, such as a heavy machinery part, it is cast into ingot molds. When the metal has had time to solidify the molds are stripped from the hot ingots, which weigh from one to five tons. The ingots are kept at rolling temperature in the soaking pit, where they are soaked in heat at a uniform temperature of 2,200 degrees. Usually the next operation is to roll the ingot into a bloom. Huge fir-ger-like tongs pick an ingot from the soaking*pit and carry it to the blooming mill, where it is kneaded and rolled between power-driven steel rolls, much as pie dough is rolled out by a cook, and for much the same reason—to improve its texture and change its shape. If the bloom is to be made into rails, it passes through another set of rolls nine times, during which its cross section is reduced and its length increased, while it gradually takes on the familiar “T” shape. It then passes through another set of rolls five times, becoming more rail-shaped with each passage. Still white hot, it finally passes [Continued on page 157] When Answering Advertisements Please Mention June Mechanix Illustrated rrt Nn Aue pn pru Pv Me Mcd PRACTICA; ЁЛ a Eoo cn d d niit od ——— ———— L——— Know Electricity as Experts Know It—and Get an Experts Pay! Recovery has begun! The months ahead are charged with signin- cance and expectation, What will you do to get the jump on the other fellow? Thousands of men have used The Croft Library of Practical Electricity The Croft Library is a complete electrical educator, It is founded on practice—on 20 years of shirt-sleeve experience—on work as it is actu- ally done. It Is jammed from cover to cover with the kind of hard- headed facts you want. Written so that the beginner can easily understand it, yet so sound, so thorough, that it is The daily guide of 59,000 highly ‘paid electrical workers and engineers. Croft tells you the things you need to know about moters, generators, armatures. Com- mutators, transformers, circuits, switchboards, ribution sys electrical machinery of every type—wiring for light and power—w of finished buildings—underwriters’ and municipal requirements. lumination in its every phase—the most Improved methods of Nahting— lamps and lamp effects, etc.—how to do a complete job, from estimating it, to completion. No money down~—easy payments Fill in and mall the coupon attached and we will send you the entire of seven volumes for ten days’ Free Examination. We take all the risk—you assume no obligation. If D decide to keep the hooks, send $1.50 in ten days and the balance at the rate of 82.00 a month, Send the enean VON and see the books for yourself. “FREE EXAMINATION COUPON | Send me for ten days’ free examination the Croft Library of Practical Electricity. If satisfactory I will_send you $1.50 in 10 days and $2.00 monthly until the price of $19.50 is paid. wanted, I will return the books postpaid, | shipment write plainly and fill in all lines.) Name Home Address .. City and Statc_ Position Name of Company. Print YourOwn Cards, Stationery, Advertising, labels, paper, circulars, tags, ete. Save money and time, Sold direct from factory only. Junior Outfit $9.00. Senior oulfits $17 and up. Do popular ralsed printing like eugraving with any of our presses. Print for Others, Big Profits Pays for itself in_a short time. 5 1f not (To insure prompt В с Казу rules sent Write for free catalog of ou s and a etails. EXCELSIOR ) KELSEY PRESSES, D-9, Meriden, Conn. Home Study Home Study Courses leading to Degrees in Arts and Sciences; Philo- sophy; Education; Writing; Psychology; Chemistry; Theology; Law; Agriculture; Business; Accounting; Sales; Advertising; Public Speak- ing: Electrical, Civil, Mechanical, Diesel, Architectural, Aeronautical, Automotive, Drafting, Radio, Alr Conditioning, Refrigeration, Chemical, Highway, Industrial, Mining, Petroleum, Steam Engineering. A good, practical education is the greatest dividend paying Investinent one can possibly make. If you are willing and ambitious—if you have the "I wlll? determination, we will show. you the way to success. FREE 10- Day Examination of Course Selected. McKINLEY-ROOSEVELT GRADUATE COLLEGE, 4223 Clarendon Ave , CHICAGO Equip it with ovr guaranteed qual- ity DISC WHEELS mounting Balloon Tires. Your choice of these famous makes GOODRICH — GOODYEAR — FIRESTONE } At lowest prices. We provide Scooter Kits, Midget auto klits etc. at great savings. Now is the time to build yours. We also carry a line of larger Tires and Wheels, Motors, etc. Write for prices. ! BILD-UR-OWN DEVICES : |] 5237 Lake St., Dept. B-6, Chicago, Ht. Ё 151

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Classified Advertisements Rates for classified ads, 180 per word (include name, address and all numbers), per insertion, accompany order and he mE in this office May Ist for t he July issue (on sale June 10th), Minimum 10 words. Cash must Address Classified Mar., Mechanix Illustrated, 1501 Broadway, New York City,

A. C. GENERATOR

P tonower. CONVERSION. Ford Generator to 110 volts, 200 watts. Plans two dimes. Henry Filson, Winston, Montana. ADVERTISING AGENCIES

newspapers, magazines, Free. Advertising Agency, 20-M West Jack- son, Chicago. ADVERTISE: 24 words in 250 News- apers $10. Lists Free. Advertising Service Bureau, 4515-B Cottage Grove, Chicago. kl FREE NEW advertisers rate guide. Brown Advertising Agency, 140 South Dearborn, Chicago. AGENTS WANTED AGENTS: Smash_go prices! Santos Coffee 12c lb. 4-oz, Vanilla 8vzc. Razor Blades 10 for 84%4c. 100 Sticks Chew- ing Gum 12c. 150° other bargains. Premiums. Experience Unnecessary. Carnation Co., MN. St. Louis, Mo. PROFIT with new products, Make, sell, Research. ree. Special prices, leads. Gibson „aboratory, Chemists, CE-1142 Sunny- side, Chicago. BIG MONEY Taking Orders; Shirts, Ties, Hosiery, Underwear, Raincoats, Pants, Uniforms, etc. Sales Equipment FREE! Experience unnecessary. Write NIMROD, Dept. 132, 4922-28 Lincoln, Chica*o. VERHAUL Your Motor— Without rebore or new rings for $2.95. Money- Back Guarantee. Write, Modern Spe- Hee

о cials, Box _6346D, Pittsburgh, Pa. Particulars Free. "Dealers & Agents Wanted. BIG Money applying initials on auto- mobiles, Easiest thing today. Free samples, Also, sideline salesmen for name plates and tire cover transfers.

AT HOME Your own manufacturing business, making popular $1.00 nov- elties. Cost you 3c to 15c. Everything supplied. Write So-Lo Works, Dept. F-.843, Cincinnati, Ohio. SOAP ROUTES OPEN, Apply at once. Start immediately; up to $45 first week. Automobiles given as bonus. Write Albert Mills, 6203 Monmouth, Cincinnati, Ohio. NO PEDDLING--free booklet de- scribes 107 money-making opportunities for starting own business, home, office.

No outfits. Elite Co., 214-G Grand St, New York, FREE! Mexican Framed Feathered Picinres! 514x812" $1.00. Sample 50c stamps, refunded first order. Marquez-M, Apartado 1176, Mexico City. 152 costs 49c, retails 1000 BARGAINS, Drygoods, Notions, Drug Sundries, Specialties, Novelties. Agents undersell stores. Free catalog. Jobbers, Dept. 3098A, 930 W. Roose- velt, Chicago. WHERE To Buy At Wholesale 500,- 000 articles. Free Directory and other valuable information. Maywood MM. Publishers, 925 Broadway, New York. BIG money applying initials on auto- mobiles, Write for particulars and free samples. American Letter Company, Dept. 11, Dunellen. New Jersey. BUSINESS Proposition Resilvering Mirrors, Autoparts, Reflectors, Making Chipped Glass Signs. Write Sprinkle, Plater, 850 Marion, Indiana. PROFIT—The Perennio Cal- 400% endar 640 years. Vest pocket size, 24

pages. $5.75 hundred. Sample 10c. Box 388, Baltimore, Md. 500% PROFIT Selling Gold Leaf Letters for Store Windows. Free Samples. Metallic Со, 445 North Clark, Chicago. ATLAS Window Sign letters. Large Sizes, Penny Each, Beautiful Free Samples. Atlas, 7941-G Halsted, Chicago. AFTERNOONS Free! $340 mo.— home! No canvassing. Expect surpriset Folio-S, Sta. D, Los Angeles. AMERICAN POLICE JIU JITSU 13 KNOCKOUT Blows without use of fists, by internationally famous Jiu Jitsu instructor. Send 15 cents. S. J orgensen, 295 Maritime ийа; Seattle. Washington. ARC WELDERS 75-200 AMPERE arc welder from Dodge generator. Complete plans and valuable catalog 35c. 100 other gener- ator changes. LeJay Manufacturing, 314 LeJay Bldg., Minneapolis, Minn. ART MAGAZINE ART MAGAZINE. Helps you sketch

human figure, paint, model, carve, cartoon, sell drawings, exhibit, form clubs. Regular 50c value—two for 25c while samples last. Magazine, 320 West Doty, Madison, Wisconsin. Device Enables Auto to Run on Fuel Oil

which A compact conversion unit, enables an automobile to use cheap fuel oil instead of gasoline, has been produced by an Oakland, Calif., man- ufacturer. The unit has no moving parts to get out of adjustment and can be installed on an auto within a few hours, tools. using ordinary AUTOMOBILES ECONOMY! Performance! Mileagel Semi-diesel conversions for gasoline motors, $5.00 up. Manufacturer'a written guarantee, Learn basic facts from free literature. Houston & Logan Conversions, 1719 Addison, Berkeley, California. MIDGET Racing book; facts for fans, builders, drivers; track sizes, regula- tions; pictures, specifications, working drawings. $1.00 postpaid. $1.15 0O. D., Ray Kuns, Department 126, Madisonville, Cincinnati, Ohio. AUTO SUPPLIES & EQUIPMENT CONVERT your car to burn Diesel oil. Save up to 70% iuel costs. Cheap in- stallation. Wonderful performance, Proven factory method. Different and better. Costs nothing to investigate. Write for free circular No. 5A. Har- rington Company, 201-204 Manchester Building, Portland, Oregon. AVIATION GET Into Aviation. Air Transport pilots get up to $6,000 per year, me- chanics $2,500. Learn at this Govern- ment Approved School. Write for complete information. State age. Lincoln Flying School, 4002 Aircraft Building, Lincoln, Nebraska, FREE AEROPLANES with motor purchase at $149.95. Easy terms— $12.50 down. <Aeroplane—sled Pro- nellers $3.50 up. Sensational values. Illustrated information 25e. Universal Aircraft. Fort Worth, Texas. AVIATION Apprentices. Good Pay— Big Future. Write, immediately, en- closing stamp. Mechanix Universal Aviation Service, Strathmoor Station, Dept. A2, Detroit, Michigan, INEXPERIENCED workers, apply for aviation jobs now. Foll salary while learning. Details for stamp. Airploy- ment, Box 553, West Los Angeles, Cali- ornia,

PROPELLERS, Sled, Airplane, Tilus- trated catalog free. Woodcraft Propel- lers, Dallas, Texas. BATTERIES & GENERATORS 110 VOLT A. C. generators at bargain

prices. 175-3,000 watts. Guaranteed. Monroe Mfg. Co., Box 3342, St. Paul, inn.

BICYCLES REPAIR, Rebuild bicycles, full details $1.00. Sites Bike Shop—Broadway, Ft. Wayne, Ind. 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 by follow- ing the large pictorial blueprints avail- able, from Fawcett Publications, Green- wich, Conn., at 50c postpaid. ONE dollar brings four different Summer Bungalow 22" x 17" Pictorial Working Drawing Blueprints by noted architect; regularly $1.00 each. Char- terock, 79 Madison Ave. New York. BUILD automatic control; turns on and off radio any desired time, Blue- prints 50c. Talmadge Wilkins, Cape» ville, Virginia.

Accept No Substitutes! Always Insist on the Advertised Brand!

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BOATS LATEST Boat Sensation: New 20 Ib. Mead Sportsmans Ki-Yak assembled at home easily, quickly from complete factory-cut kit. $6.00 paddle now given with yours—if you hurry! Rush dime for catalog with pictures, description i. e. Mead Gliders, Dept. MC-68, Chi- cago, Ill. FORD and Lincoln Marine Conver- sions. Send 10c for information. Lehman Engine Co. Newark, N. J. BOOKS & PERIODICALS “CARTOONING & Advertising Art.” Six separate books, patented "'Lift-out" cover, one thousand illustrations, numer- ous charts, diagrams; sixty-six thousand words, hundreds money making pointers, all for $5.00. Teaches easily, quickly ; draw at home, sell by mail to syndicates, magazines, agencies. Parallels highest priced correspondence course. Based on thirty years experience. Five years in making. Nothing like it in history of art publishing. Free specimen pages to all who write. No salesman will call. Fox, Publisher, 1472 Broadway, New York. 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 a dozen times more enjoyable, Price 50c at your newsstand, or order directly from Fawcett Publications, Fawcett Bldg,. Greenwich Conn. INSIDE Legal Information. Make money by knowing the answers. Price 25 cents. Dept. E, 234 Hurst Bldg., Buffalo, N. Y. BUSINESS OPPORTUNITIES PLASTEX Industry needs manutac- turers on small scale and for big pro- duction of Art Goods and Novelties in Plastex and marble imitation. Cheaply and easily made in our guaranteed rubher moulds. We cooperate in selling goods, You are just in time for big 1938 wholesale season now starting. Interesting booklet mailed free. Plastex Industries, Dept. R, 1085 Washington Ave., New York, FASCINATING business. Repair, ad- just typewriters, addin; machines, Learn easily at home from factory expert. Earn up to $15.00 daily, Com- plete instructions covering rn makes $3.00 postpaid or sent C. O. D. Adding Machine Equipment service, 3601 Michigan, Dept. 204A, Chicago. 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- xs. Inc., Drawer 110, East Orange, MAN in Each Town to Plate Auto Parts, Reflectors, Bicycles, Fixtures, Mirrors, by late method. Simple plan of manufacturing at home starts You in Good Paying Business. Free par- ticulars and proofs. Gunmetal Co., Ave. A. Decatur, Illinois. MAKE artificial marble, glazed tiles, uncanny. Tabletops, plaques, floors, hones, novelties. ard, fireproof, inex- pensive, cement secrets. Brilliant tile and liquid rubber samples 3c. John H. Payn, 945 Grande Vista Avenue, Los A^- 'es, Calif. likE To Write? Clipping and preparing newspaper articles for publishers. Simple, fasci- nating, profitable. Stamp brings details. Division 76, National Press, 3923 West Sixth, Los Angeles, California. When Answering Advertisements Please Mention June Mechanix Illustrated Earn extra cash! , Handle on Saucepan Holds Tablespoon Readily attached to saucepans, a new type handle features a support which holds a tablespoon when it is not be- ing used for stirring the cooking food. The spoon stays cool in the handle and is ready for use when the cook needs it. COLOR concrete surface with chemical solutions. Beautiful pottery without moulds. Garden wishing-wells. Stucco rock. Glazing concrete. Sample 10c. Hollywood CementCraft, 8528 Wonder- land, Hollywood, California. FREE circulars describing hundreds of money-making opportunities by mail. Newest methods. Pleasant surprise. Write Now. Progress Publishing Com- pany, 2513B N. 9th Street, Milwaukee, Wisconsin. PROFIT with new products. Make, sell, repeat. Analysis. Research. Guar- anteed formulas. Biggest catalog free. Special prices, leads. Gibson Labora- tory, Chemists, CE-1142 Sunnyside, Chicago. IF YOU are looking for a chance to devote your spare or full time to profit- able work see our offer on page 32. Metal Cast Products Co., 1696 Boston Road, New York City. AFTERNOONS free for outdoors, movies, $340 month, home. Unique plan. No canvassing, Prepare for sur- prise. Folio-S, Station D, Los Angeles, IF YOU feel that you are capable and desire to learn chain store management, send quarter for trial instructions. Amidon Exchange, 237 5th, Elyria, O. SUCCEED With Your Products. Make- Sell Them. Formulas. Processes. Accurate analyses. Catalog free, A. Thaxly Co.. Washington, D. C “$35 WEEKLY for 3 hours bome-. work." 204 other moneymaking plans. Particulars free. Stamford, 836-Е, Riverside Drive, New York, NEWSPAPER — Magazine Clippings Pay. Complete Instructions 25c. Goodall Advertising Agency, 742 Market, San Francisco. FREE LITERATURE describes hun- dreds plans for making money locally or by mail, Gilbert Supply, 1107-M Broadway, New York. YOU'LL Like Resilvering Mirrors, Autoparts, Reflectors, Making Chipped Glass Signs. Write Sprinkle, Plater, 845, Marion, Indiana. | PROFITS and pleasure making shell jewelry, novelties—newest field! Stamp appreciated, Challenge, A-13, St. Petersburg, Florida. | FOR a highly profitable lifetime busie ness, operate a collection-credit agency. | Free information, Cole Associates, Syracuse, N. Y. MERCHANT'S attention, Proven sales ideas that bring real business. Send $1.00 for three. W. 8. Finigan, Oneonta, N. Y. SELL by mail and receive dollars daily. Orders filled free. Stamp brings details. Johnson, 126 Lexington Ave., New York. PLANT Chemiculture. Instructions, 10 formulas, $1. Dawson and Dorn, 4615 W. Washington Blvd., Los Angeles. Z Z o OPERATE IIome Mailorder Business. Plans, ads, full instructions given, 25c. Steitle, 6605 Murray, Mariemont, Ohio. AGENTS—To mail our literature. Good profits. Home business. М. Maywood, 149 Fifth Ave.. New York, SELL by Mail! Books, Novelties! Bar- gains! Big profits! Particulars Free! H. Elíco, BE North Wells, Chicago. EARN cash income, copying and dupli- cating simple cartoons for advertisers. 3-N Service, Argyle, Wisconsin. HOW and where to obtain capital fully explained, free particulars. Star Service, Wanakoneta, Ohio. MAIL Order Business—Big Profits— Amazing Method. DeGeorge, 651 North 6th St., Newark, N. J. PRACTICAL Money Making Plans. Literature Free. Silvester & Company, Old Bridge, N. J WANT Extra Money? Stietlee, 6605 Murray, Ohio. 107 NEW successful home business gee Century, 1261-M Broadway, New ork, 67 PROVEN Moneymaking Plans, 25c. Frank Turack, 123 Starr Bldg., Export, а. Send Stamp. Mariemont, BUSINESS SERVICES MESSAGE BUREAU. Mail forwarded daily. 200 Lumber Exchange, Minnea- olis, Minn, CAMERAS AND PHOTO SUPPLIES CAMERAS and supplies. Free illus- trated Photographic Almanac listing everything photographic—still, movie cameras, films, lenses—at iremendous savings. Hundreds of bargains, new and uséd. All guaranteed. We take your old camera or equipment in trade. Write for free copy of new Photo- graphic Almanac and m.oney-saving bargain book—just out! Limited edi- tion. Hurry! _ Centrai Camera Co, (Photographic Headquarters since 1899) 230 South Wabash, Dept, 6-J, Chicago. . ABSOLUTELY Free! Advertising Campaign! New Moviematic, All Pur- pose 3-in-1 Camera. Included with this remarkable Moviematic, All Purpose Camera—a Keystone Motor Driven Projector. It's simple to get it, Merely show the camera and projector illustra- tions to your friends, neighbors, asso- ciates, etc., and explain to them how they can obtain this at No Cost To You. Write Today—Right Now! Master Distributing Corp., 18 East 48th St. New York City. 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 Ave., Dept. 2049, Chicago. 153

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Giant Thrust Bearing Built for Dam Constructed for use at the Pickwick Landing Dam in Tennessee where it will support the weight of the dam's water-wheel generator, this huge thrust bearing has a diameter of 105 inches. In the photo above, a craftsman is smoothing the surface of the mam- moth bearing. Two of the bearings will be used at the dam, each sup- porting 1,250 tons weight. 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., New York. plete instructions, buyers, real informa- tion. ‘‘Photomarket,” 402-M Evans Building, Washington, D. C. DUPONT Superior Panchromatic, 35 mm; 25 ft. roll, $1.30, Optical Labora- tories, Larchmont, N. Y. CARTOONING CARTOONISTS—Make money i your home town. 25 Saleable Ideas— Illustrated—$1,25. R. Fox, 32 Fulton Waukegan, Illinois. CHARTERS DELAWARE Charters: Complete in- corporating and organizing service $35. Submitted forms. Chas, G. Guyer, Inc., Wilmingten. Delaware. B CHEMISTRY CHEMISTRY, Mineralogy, Micro- scopes, Binoculars. Catalog Free. Tecko, 5315K, Evanston, Illinois. CORRESPONDENCE COURSES 500,000 USED Technical and business books. Sold, rented, exchanged. All subjects. Satisfaction guaranteed. Cash paid for used books. Complete details and illustrated bargain catalog free. Send name. Nelson Co., 3230 Man- hattan Bldg.. Chicago. | DETECTIVES DETECTIVES. Маке Secret In- vestigations. Experience unnecessary. Detective Particulars Free. Write, George Wagner, 2640-V Broadway, BE A DETECTIVE. Make secret in- vestigations. Excellent opportunity. Free particulars. Raymond Stultz, Box 633, Elkhart, Indiana, 154 EDUCATIONAL & INSTRUCTION MEN Wanted—Learn Tool Making. Automatic Screw Mach. Machinist Trade. Big Demand. Actual Experience. Expert Supervision, Write for Free Book “M”. Allied Screw Machine Co., Ine., School Div., 603-9 Lake St., Chicago, WANTED Immediately, Men-Women, age 18-50, qualify for Government Posi- tions. Commence $105-$175 month. Common education sufficient. Valuable information free. Write, Instruction Service, 234, St. Louis, Mo. $105-$175 MONTH. Get U. S. Govern- ment Job. Men-women. Try next ex- aminations. List jobs and sample coaching—Free. Write today. Franklin Institute. Dept. S59. Rochester М, Ye ELECTRICAL SUPPLIES HEADQUARTERS for invaluable electrical information and hard-to-get materials in any quantity. Send for free Catalog. S. W. Duncan, 412 S. Hoyne Ave., Chicago. GENERATORS, Motors, Lamps, Sup- plies. Bargain List for Stamp. DENNIS ELECTRIC, STANCH- FIELD, MINN. ELECTRIC FENCING MAKE Electric Fencer. It's easy with our simple plans to convert Ford T coil. No further costs. Complete plans 35c. LeJay Mfg. 814 LeJay Bldg., Minne- apolis, Minn. — ___ ELECTRIC PENCIL ___ ELECTRO-SCRIBE: Electric Pencil Writes-—Engraves a]l Metals. $1.00 postpaid. Details Free. Beyer Mig. Co., 4515-Y Cottage Grove, Chicago. ELECTRIC SHAVERS FREE Royce flectric Dry Shaver! Few Moments Required! Illustrated Details, Card Sent! Hurry! Specialty House, 3835-M, Cambridge, Phila., Penna. ENGINES, MOTORS, ETC. WINDING Data, 225 motors, single and three phase. Price $1.00, Motor Date Service, Box 7631, Kansas City, 0. FARMS 40 ACRES, Near White River, un- improved; poultry land. $175, $5 down, $5 monthly. Free list and literature. TIubbard, 224 Grossman Bldg., Kansas City, Kansas. FEMALE HELP WANTED WEAR fine hose I send without cost with outfit while taking orders for amazing new hosiery. Replacement guaranteed against holes, snags, and runs. Rush name and hose size. Wil. knit, Desk 34-F, Greenfield, Ohio. FOR INVENTORS PATENT Your Idea. Write imme- diately for two free books, ‘Patent Protection” and “‘When and How to Sell an Invention." Full explain many interesting points to inventors and illustrate important mechanical principles. With books we also send “Evidence of Invention” form. Prompt service, reasonable fees, thirty-nine years’ experience, Avoid risk of delay. Address: Victor J. Evans & Co., Registered Patent Attorneys, 42-G Vic- tor Building, Washington, D. C. INVENTORS--Time counts — Don't risk delay in patenting your invention. Write for new 48-Page Free booklet, “Patent Guide for the Inventor.” No charge for preliminary information. Clarence A. O’Brien and Hyman Ber- man, Registered Patent Attorneys, 28-Z i Adams Building, Washington, О, С, Accept No Substitutes! Always Insist on the Advertised Brand! & Die Compact Device Helps Motorists Check Gas A newly developed automotive device enables a motorist to check the condi- tion of the gasoline or oil being used by drawing off a sample of either into a glass tube, which is part of the de- vice. A long flexible metal tube is inserted through the oil-filling hole in the crankcase or the gas tank opening and when the pump plunger on the device is pulled back, a sample of the oil or gasoline is sucked into the glass tube, as shown in the photograph above. INVENTORS: Send for my free 72- page book, Conscientious, prompt per- sonal service on all patent matters. Registered Patent Attorney, L. . Randolph, Dept. 341, Washington, » C. WE SUCCESSFULLY sell inventions, 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. FORMULAS, PLANS, ETC. ANALYSIS. Research, Newest guar- anteed formulas. Biggest catalog free. Special prices, ieads. Gibson Labora- tory, Chemists, CE-1142 Sunnyside, Chicago. SUCCEED With Your Products. Make- “Sell ‘Them. Formulas. Processes. Accurate analyses. Catalog free. A. Thaxlv Co.. Washington. D. C. FORMULAS: Tested Moneymakin: Formulas (15) for $1.00. Real Unusua Offers. Marvel Laboratories, 6629 No. Maplewood, Chicago. FORMULAS-—Latest money Literature free, D-Belfort, Keeler, Chicago. FORMUOLAS—All kinds. Guaranteed, Catalog Free. Kemico, 67, Parkridge. llinois. makers, 1042 N. HOME CRAFTSMAN SQUAREKNOTTERS! Make belts, handbags, etc. Quality cord samples with catalog, free. Beginners book, catalog and samples, 10c. Special! Regular $1 book with 50c beginners outht, all for $1. P. C. Herwig Co., Dent. R, 121 Sands St., Brooklyn, №. Y. EIGHT lawn ornament patterns, 10 novelty patterns (all actual size) 250. Earl Corr, Farmington, Minnesota, HOME INSTRUCTION HYPNOTISM HYPNOTISM. Complete 20 Method Course 25c, Western Institute Hypno- tism, MM-2984 North Ridgeway, Chi- cago,

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New Mattress Made of Foam Rubber Weighing about half as much as an ordinary mattress of equal size, a newly developed ''sleep-cushion" is composed of 85% air and 15% foam rubber (lower photo). The upper photo shows how the new type mat- tress shapes itself to the body contours of the sleeper, supporting every part of body in direct proportion to weight. INVENTIONS INVENTORS: Secure immediately effective patent protection through simple, direct filing, but pay single Government fee only. Complete details, free. American Patents Corporation, Dept. 5-E, Washington, D. C. INVENTIONS—Patented, Unpatented. Bought outright, royalty. Write Arel- lano-Power Company, St, Chicago, Illinois. INVENTORS: Write for free copy “Pointers on Promoting Inventions.” National Service Bureau, Dept. M, St. Louis, Mo. INVENTIONS Commercialized. Pat- ented or unpatented. Write Adam Fisher Co., 582 Enright, St. Louis, Mo. INVENTIONS WANTED SMALL inventions wanted by manu- facturers. I'll hclp you sell your in- vention. Write for free circular, S. Huli, 7829-L Fuclid Avenue, Cleveland, io, INVENTORS FREE Booklet (Copyrighted) for in- ventors explains selling facts and buyer locating method that may save you costly mistakes and lead to profitable sale of your patented, unpatented in- vention. Copy free by writing: Inven- tion Reporter, E-11236 So. Fairfield, Chicago. CASH for Unpatented or Patented inventions or ideas. Stamp for par- ticulars, Mr. Ball, 9441-F Pleasant, Chicago. GET Your Own Patents. Legal blanks, complete instructions $1. Cudding Sons, Campbell, California. MACHINERY, TOOLS & SUPPLIES GIANT Gadget Kit—Screws, nuts, bolts, washers, rivets, bushings, springs, tappingscrews, lockwashers, gears, brackets—experimental motor. 10 Ibs. —over 1.000 items. Price $1.49. Worth $7.50. Money back guarantee. Manu- facturers Supply, 207 W. Illinois, Chicago. LATHES, Woodworking Machinery, Electric Drills, Motors. Send stamp for list. Used Outboard Motors; Parts, Service on all Makes. Craftsman Spe- cialties, Box 446, Cedar Rapids, Iowa. When Answering Advertisements Please Mention June Mechanix Illustrated 15 | etc.—253c. 1 North La Salle | MAGIC TRICKS & NOVELTIES FREE! Magic Catalog 500 tricks, Amaze. Mystify freinds. Write today! Lyle Douglas, Station A-3, Dallas, Texas. WE SUPPLY every noted magician, Large Professional catalog 25c. Holden, 222 West 42nd St., New York. MALE & FEMALE HELP WANTED M, M. EARNED $267, three weeks, raising mushrooms in cellar! Excep- tional, but your cellar, shed perhaps suitable. We buy crops. Bock “ree. United, 3848 Lincoln Ave., Dert. 90, Chicago. MIDGET AUTOMOBILES MIDGETS! Plans, parts, building kits. New modern designs, easily built, lowest cost. Catalog—containing full construc- tion details latest sport midgets, racers, Circulars free. Shipps Midgets, Box 543-B, Zanesville, Ohio. BUILD a Midget Miller Racer., Com- plete plans for constructing this authen- tic midget automobile appear in the new 1938 edition of How-To-Build-It along with many other interesting home ani workshop plans. Send 50c for this 148- page book to Fawcett Publications, Greenwich, Conn. USED midgets—motors—parts service. Direct owner prices, Latest lists, 20c. Shipps, Box 543-B, Zanesville, Ohio. MISCELLANEOUS BE FIRST your community with decorated window screens. Painters order at once. Patterns, directions 50c. Home Ideas, Vernon, B , Can. ` OLD Razor Blades now worth 5c each. Proposition, 10c (refunded). Robert Company, Box 255, Syracuse, New ork, j MARK your Tools with a Steel Hand Stamp. Any Three Initials 75 Cents. Gideon A. Pike, North Attleboro, Mass. BURIED TREASURE, Minerals, free booklet, photographs. Fisher, Palmer Bldg., Hollywood. ; MODEL ENGINES CATALOGUE of over 40 Engines— Castings— Supplies, 25c. Refunded, Enico, 2417 North Ashland, Chicago. MODEL RAILROADING te a Model Railroad in 00 gauge (3% inch between rails). A complete catalogue of parts, construction kits, and completed units. One Dime. Nason Railways, P. O. Box 9, Mt. Vernon, N. ., Dept. 6X. MODELS & MODEL SUPPLIES YOUR Ideas developed into practical working model. 30 years successíul experience; thousands satisfied custom- ers. Confidential service guaranteed. Bank references. Send 3c ‘postage for 32 page book “Making Inventions, Pay.” Crescent Tool Company, Dept. T. Cin- cinnati, Ohio. ENGINE CE 20c. Particulars free. Evraymesco, 28 N. Clinton, Chicago. MONEY MAKING OPPORTUNITIES HUNDREDS of money-making oppor- tunities—for anyone—anywhere. Write | Ashland Technical Service Co. 6-al St., Boston, Mass. Enclose 10c. TAKE in the Dollars with the “Money By Mail” system. Particulars free. Key Systems, Box 323, Jeannette, Penna. Pipe Holder Fastens to Auto Dashboard For the motorist who smokes a pipe, a newly invented device enables him to keep the pipe safe and within reach on the dashboard when not in use. The device consists of a horizontal metal tube fitted with small springs inside, the springs being adjustable so that any size pipe stem can be held. MOTION PICTURE & SOUND EQUIPMENT | LEARN Motion Picture Theatre Busi- Home-Study Training: Manage- ment, Advertising, Projection. Tree Catalog. Give Age. Theatre ае 345 Washington, Elmira, N. 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. SEND 15e for illustrated used Motor- cycle catalog. Bargains. largest stock genuine Indian parts and motorcycles. Indian Motorcycle Sales, Kansas City, o. OFFICE EQUIPMENT TYPEWRITERS, multigraphs, address- ing machines, adders, dictaphones, dup- licators, sealers, folders. Save half, write Pruitt, 553 Pruitt Bldg.. Chicago. PATENT ATTORNEYS PATENT Your Idea. Write imme- diately 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 principles. With books we also send “Evidence of Invention” form. Prompt service, reasonable fees, thirty-nine years’ experience. Avoid risk of delay. Address: Victor J. Evans & Co., Registered Patent Attorneys, 41-G Vic- ter Building, Washington, D. C. INVENTORS—Time counts— Don't risk delay in patenting your invention. Write for new 48-Page Free booklet, “Patent Guide for the Inventor.” charge for preliminary information. Clarence A. O’Brien and Hyman Ber- man, Registered Patent Attorneys, 28-Z Adams Building, Washington, D. C. UNPATENTED Ideas can be sold. I tell you how and help you make the sale. Particulars, with list of manufacturers and wanted inventions, sent free on re- quest. Write Wilson Holmes, 905 Barrister Bldg., Washington, D. C. "INVENTOR'S Guidebook" containing 96 mechanical movements and advice about patenting, selling inventions, also “Record of Invention”, Free. Frank A. T.edermann, Patent Attorney-Engineer, 154 Nassau Street, New York. o ea

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Wristlet Buzzer-Light Aids Auto Mechanics Consisting of а әта light globe soldered to a buzzer box and affixed to an ordinary leather wristband, a newly developed "wristlight" helps garage mechanics to locate automotive electric trouble in minimum time. The device has a battery clip, which at- taches to any metal part, affording a common ground for both the buzzer and light circuit, and two detector points. One needle point attaches to any open circuit to light the lamp, which thus focuses a beam on the tool in use. The second point trails down “short”? by sounding the buzzer at each contact until the short is located. HAVE YOU a sound, practical inven- tion for sale, patented or unpatented? If so, write Chartered Institute of American Inventors, Dept. 5-A, Wash- ington, D. C. PATENTS INVENTORS-— Time counts— Don't risk delay in patenting your invention. Write for new 48-Page Free booklet, “Patent Guide for the Inventor.” No charge for preliminary information. Clarence A. O’Brien and Hyman Ber- man, Registered Patent Attorneys, 28-Z Adams Building, Washington, D. C. INVENTIONS Conmercialized, ented or unpatented. Write Adam Fisher Co.. 582 Enright, St. Louis, Mo. PERSONAL STUTTERING and Stammering cor- rected at home. Booklet free. Paul J. Wolfe, Box 52, Pittsburgh, Penna. PHOTO DEVELOPING THE PHOTO MILL. Immediate Servicel No Delay! Roll developed, carefully printed and choice of two beautiful 5 x 7 double weight profes- sional enlargements, one tinted enlarge- ment, or eight reprints for 25¢ coin. Reprints 2c each. The Photo Mill, Box 629-91, Minneapolis, Minn. FINER Finishing. Rolls developed and printed, with One Colored enlargement, or two professional enlargements, All for 25¢ (coin). Genuine, Nationally Known, Moentone Superior Quality. Moen Photo Service, La Crosse, Wis. 156 MINICAMERS — Sensational Offer, any 36 exposure roll developed and each good negative enlarged to 3"x4" for only $1.00. Prompt—Guaranteed Serv- ice. Minilabs, Box 485D, Madison Sq. Sta., New York. SNAPSHOTS in Colors—Roll de- veloped, 3$ Natural Color Prints—25c. Natural Color reprints—3c. Amazingly Beautiful. Natural Color Photo, C-39, Janesville, Wisconsin. SNAPSHOT Folder with every roll developed, 8 prints, painted enlargement —25c. | Reprints 3c. Fast service, Janesville Film, A-39, Janesville, Wis- consin. UNIVEX Movie Film—Develop Your Own. Simple method. Full instruc- tions and formulas $2.00. — Hobby aos 687-F Cheshire Ave., Eugene, re, ROLLS _ DEVELOPED—25c coin. Two 5x7 Double Weight Professional Enlargements, 8 gloss prints. Club Photo Service, LaCrosse. Wis. SAMEDAY Service: Roll developed, 8 glistening prints, 2 enlargements— 25c. Midwest Photo, B-39, Janesville, Wisconsin, SENSATIONAL Offer. Five 5x7 en- largements 23e, Cardinal Photo, Sum- mit, N. J. POTTERY COLOR-GLAZED concrete pottery, tiles, walls. Make glazed concrete lawn pottery without molds, power or costly tools. Cheap materials. Build own equipment from our plans. Gift. ware, statuary, novelties. New money- making business for Men. Booklet, colorplate, details 10c. National Pot: teries, 15 West 26th, Minneapolis, Minn. PRINTING 125 LETTERHEADS 8x1ll and 125 Envelones—$1.00 postpaid. Benneville, 907 West Roosevelt, Philadelphia, 500 Letterheads and 500 Envelopes, $3.25 cash. Barry, Babylon, New York. 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 Fawcett Publications, Fawcett Bldg., Greenwich, Conn, RADIO Engineering, aviation and police radio, Servicing, Marine and Morse Telegraphy taught thoroughly. All expenses low. Catalog free. Dodge's Institute, King St, Val- paraiso, Ind. RADIOS RADIO Easy Beginners—3 tube elec- tric or battery. Diagram 25c. Other diagram list 10c. Radio Electric Service Co,, Franklin, Tenn. RAZOR BLADES 100 FINEST Quality, blue steel razor blades. Double edge $1.00. Single $1.25. Guaranteed. Ashton Mdse. Mart, 63 Basswood, Lawrence, Mass broadcasting, . SALESMEN WANTED BIG commissions selling stores celluloid pricing tickets, metal shelf moulding, Menu covers, signs, chrome changeable letters. T. Pricing Press, 124 White S*.. New York. ATLAS Window Sign letters. Sizes, Penny Each, Deautiful Samples. Atlas, 7941-G Halsted, Chicago. SPECTROSCOPES SOLAR Spectroscope $1. ore spectroscope $2.50. Spectrometer $5. Cudding Sons, Campbell, California. TATTOOING SUPPLIES TATTOOING Outfits, Supplies Remover, Bargain List. Waters, M- 96% Putna, Detroit. TELESCOPES, MICROSCOPES, ETC. LENS SET—Makes 3” diameter 75- 150 power astronomical telescope. $1.00 postpaid. 60X, 2” kit 50c. Optical Works, MM6C, Milton, Pa. TELESCOPES, Microscopes, Binocu- lars; 1938 bargain catalog free, Rrown- scope Company, 5 West 27th Street, New York. TELESCOPES, Microscopes, lars, Mineralogy, Chemistry. free. Teeko, Evanston, Illincis. DUILD Reflecting telescopes; catalog free. Instructions 10c. Optical Labo- ratories, Larchmont, N. Y. VENTRILOQUISM LEARN Ventriloquism by mail; small cost, 3c stamp brings particulars. Geo. W. Smith, 125 North Jefferson, Room $694. Peoria, Ill. VIOLET RAY LAMP ULTRA Violet-Infra Red. Health Lamp. Two separate units in one. Promotes Sun Tan—Vitamin "D." Automatic control, AC-DC current. $3.90 postpaid. Details Free. Beyer Mig. Co., 4515-M Cottage Grove, Chi- cago. Binocu- Catalog WELDING ATTENTION! $1.00 brings big labo- ratory tested collection of over 125 of Arc welders from electric auto motors, light plants battery chargers, Dodge generators, D. C. power motors and generators. Fifty car generator conver- sions make wind light plants, wind chargers, À. C. and D. C. generators, motors. Old transformers make A. C. arc-welders, spot-welders, Satisfaction guaranteed. All in one book., Best Methods, Box 833, Minneapolis, Minn. DODGE Arc-welder 40 volts D. C. 25- 200 amperes. Positively no armature . Certified Instructive Plans C.O.D. $1.12. Airmail 12c . (Money Back Guarantee, if not satisfied.) Welders Club of America, DB-3432. M-Mart, Chicago. ARC WELDING Outfit $1.25. Weld fenders, braze, solder. Lavrow, 4368-W, Warren, Detroit, Stamp appreciated. GENUINE Dodge Arc-welder. (No rewinding.) Plans $1.00. Welders Club, BB-3432, M-Mart, Chicago. WIND DRIVEN PLANTS GENERATOR propellers, expertly de- signed, factory prices. Universal Air- craft, Fort Worth, Texas. WIND ELECTRIC PLANTS i your own Windcharger. material plus used car generator, Drawe ings—Instructions 10c, Wesco, Mine neapolis, Minn, Accept No Substitutes! Always Insist on the Advertised Brand!

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Steel—Backbone Of World [Continued from page 151] through the finishing rolls, a rail 120 feet long, to be cut into 32 or 39-foot lengths. Instead of rails, the bloom might become any one of the many structural shapes used in bridges and buildings. It might be rolled into billets for rods of various sizes, or into slabs, if its final form is to be sheets or strips. Many of the rods are made into wire, by drawing them through a series of dies while cold, each hole being smaller than the rod passing through it. Cast iron and alloy steel rods are used as dies for coarse wire, diamonds for the finer wires. There are 160,000 uses for steel wire. including fencing, paper clips, hair pins, guitar strings, and hairsprings in watches, There are wire springs so small it takes 83,000 to make a pound, and a ton of them is worth $200.000. And there are heavy machinery springs that require a weight of 14,000 pounds to depress them one inch. With- out springs we could have no watches, no internal combustion engines, no telephone bells or window shades. The continuous strip mill, though developed within the past ten years, has revolutionized the production of flat-rolled steel. A white hot slab is fed into one end of the mill, passes through ten sets of rolls in a straight line, and emerges as a steel strip several hundred feet long, and any desired width up to 96 inches. Since each roll reduces the thickness and increases the length of the strip, each succeeding set of rolls must run faster, until the white hot steel is traveling 20 miles an hour when it emerges. Separate electric motors drive each set of rolls, and their timing must be precise to the thousandth of a second to take up the slack, and prevent the white hot strip from kinking and running wild. If hot rolled sheets are being made, the strip is run onto a table and cut to the desired lengths. If the steel is to be cold rolled, it is coiled into enormous rolls. The principal products of continuous mills are sheets for stamping and drawing auto body parts, and tinplate. The cheapness and splendid appearance of the modern motor car is possible only because of recent developments in producing cold rolled steel sheets. In 1910 an auto body had to be bent by hand around a wooden frame, then riveted, brazed or welded into place. And it took twenty coats of paint, priming, and varnish to cover up the rough surface of the steel. Today body parts are stamped out cold in huge presses, the steel now being ductile enough to stand the stresses of such stamping. Cold rolling has given a surface that requires no priming or touching up, and can be covered with two coats {Continued on page 158] 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, Guadeloupe, Iraq, Sarawak, French and British Colonies, including natives, beasts, ships, ete. This entire packet for only 5e to approval applicants. Big a lists free. Feni Stamp Company, Box 87-Z (G.P.O.), Brooklyn. N. GENEROUS OEE Triangles from three countries, Afghanistan, Newfoundland Commemorative, Giant Map Stamp, United States $5.00 stamp, over fifty different others. Everything 10с to approval applicants. Tru-Value, Box M-1412, Hartford, Connecticut. REVISED 1938 Stamp Annual Free:— Describes and Ilus- trates Albums, Supplies, United States, Coronations, British Colonials, Canadians, Foreign Stamps. This ffty-page cata- Cae Gray Stamp Company, Dept. M.M., Toronto, anada 1897 GRANDE Comore Islands, Liberian Bongo Antelope, rare old genuine Baden, Turks Caicos, 33 S., British Colony Map Stamp, etc. Everything 3c Mii approvals. Viking, 1-MM Hanson Place, Brooklyn, N. Y DIAMOND Airpost Commemorative Issue Complete, Pro- letariat Portraits Complete, Dragon Stamp, with 117 addi- tional, cataloging $3.00, only 10c. Friendly Filatelists, Box 4428M, Philadelphia, Penna. NEW Rivera nude stamp! World's largest triangle! Congo, Sudan, South Seas, bicolors, pictorials and many others. Only 3c with approvals. Cactus Junior Approvals, Box 1870-D. Tucson, Arizona. g UNITED STATES—45 Different, Perforation Gauge, Hinges, Bargain Price List—all for 10c. Seidenberg, Baroda, Mich. COSTA RICA Philatelic Sheet, ten cents. To approval applicants only. K. Stamp Co., Perryville, Maryland. MIDGET MIXTURE—100 foreign stamps—Asia, Egypt, Europe, etc, 5f. Guy Elsea, Bowling, Green, Ohio. FREE!!! Postage 3c. Roberts, Two Coronation Sets. 312T Shearerbldg, Baycity, Michigan. COINS FREE: Foreign Coin, Banknote and Large Illustrated coin catalogue, for 4c postage. Approvals sent. Tatham Coinco, Sorin«field-9. Mass. COINS, Beadwork, Indian Relics, Minerals, Books, Curios, а Catalogue, 5c. Indian Museum, Northbranch, Kansas. 19 DIFFERENT coins, 25c; 50, $1.00. Bishoff, 500 E. 8th, Kansas City, Mo, COINS FOR SALE COMMEMORATIVE Malf Dollars. tain, Oregon, Texas, Cleveland, Island, $1.50 each. Illustrated Norman Shultz, Salt Lake. Utah. INDIAN CURIOS INDIAN CURIOS. 100 geod ancient Arrowheads $3.00. Lincoln, Stone Moun- Kentucky, San Diego, Long Cat:logue No. 14, 25c. Tomahawk Head 50c. Illustrated catalog 5c. H. Daniel COLOSSAI, OFFER! Afghanistan, Newfoundland, Giant H = * Мар, a. $5.00 stamp, дин. Colonies, over nity other s— Hot Springs, Arkansas. c with low-cost approvals conomystamps, Box 1543, Hartford, Connecticut. у TYPEWRITER PCRTRAIT STAMPS! 100 diff. 3c; 500 diff. 35c; 1.000 diff, 90c: TYPEWRITER Portrait of Abraham Lincoln. iaces Hlustrated Album (4000 spaces) 22c. Approvals sent. Tatham Stamp Co. (D9) Springfield, Mass. smiling likeness, Size 12" x I Copy $1.00. E. Drawer 1256, Charleston, W. . Smith, When Answering Advertisements Please Mention June Mechanix Illustrated 157

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ONLY CORONA HAS IT! Ask any “big machine” typist if Floating Shift doesn’t save work and wear, improve align- ment, add speed! Then look at all the other Corona features... Touch Selector, Speed Booster, All- atound Frame, etc. Match Corona улпш all comers. Easy to use...easy to pay .as little as $1.00 a week, Free case and touch chart. MAIL THIS COUPON LC SMITH & CORONA TYPEWRITERS INC., Desk 5, 783 E. Washington Street, Syracuse, N. Y. I'm thinking of buying a Corona, Send free descriptive booklet and terms, Name €€0900900900000900000000009€90^7^*292»5495660-^05c6060069000€9 State AMAZING MACHINE | GROWS HAIR 4777 **Interm!ttent — Vacue '* stimulates deepe lying scalp blood ves» I s—and w Stops falling ha ы Tones up scalp. Now hair often in 90 days, Easy to use this amazing machine at me. nly і $9.95 complete, Write quick for FREE TRIAL I GUARANTEED “"™* OFFER. RAND, Dept. J-1660, Newport, Ky. IREW ORK BUY THEM DIRECT, Assortments $1.00 and up or make your selection from FREE catalog. Send postal for it to-day. H. E. ROEHRS & CO. CLOSTER,, NEW JERSEY DEPT. 4, VENETIAN BLINDS Make your own at low wholesale cost. Tt's easy under 'our unique plan. All materials supplied. Send 20c for circular and samples of Ladder Tape, Cord, Rails, Slats, 15 color samples of tape and chart listing most decora- tive and attractive color combinations. VENETIAN BLIND MFG. & SUPPLY CO. Dept. E, 1769 Lunt Ave., Chicago, Ш. Decorative Decalcomania Transfers Imported Designs of all Sizes and Types— Flowers, Figures, Marquetry, Birds, Juve- nile, Borders, etc., for Furniture, Doors, Trays, Lamps and what not. Catalog with 800 illustrations in Color sent for 25c Deductible on first dollar purchase È c. WELLS, Dept. M86, 25 East 26th Street, New York 158 Steel—Backbone Of World [Continued from page 157] of enamel. It is almost entirely a matter of the quality of steel that makes the cheapest car today a far better product than the most expensive car of 20 years ago. So important has steel become in modern civili- zation that there are now 18,000 pounds in use for every person in the country—seven times as much as in 1900. The house you live in may have a steel frame or was cut and put together with steel tools. You sleep in a bed with steel springs, and a steel alarm clock wakens you. You don clothes made on steel looms and eat breakfast cooked in steel utensils on a steel stove. You ride to work in a steel auto, or on a steel trolley or subway train running on steel tracks. You work in a steel-supported building. You use steel tools, or your stenographer types your letters on a steel typewriter. You sign them with a fountain pen molded in steel. The food on your dinner table has been culti- vated with steel implements, milled with steel machinery, baked in steel ovens, preserved in steel cans or refrigerators. It was brought to you in steel cars over steel rails, in steel ships, or in steel trucks over steel-reinforced roads. The magazine or book you read was printed on a steel press. The paper itself is made from wood, cut with steel tools, processed in steel machines. There is scarcely a phase of your life today that is not touched, improved or made possible by steel. It is perhaps the most significant factor in twentieth century civilization. Steel is the back- bone of the modern world. Microscope Slides [Continued from page 143] A very slow and gentle stream is turned on and the tissue placed in the bottle. Now label a series of glass jars and fill each with its proper reagent—30, 50, 70, 85 and 95% alcohols and pass the tissue through each of these in succession, 30% first; a two-hour stay in each. If more convenient to fit a time schedule, a longer stay does no harm. These alcohols perform two steps in technique—hardening and dehydrating— the gradual elimination of water, and its replace- ment by increasing strengths of alcohol. Dehy-~ dration is necessary since tissues would rot in water, and also to be able to pass into chemicals that will not mix (are not miscible) with water. Paraffin, xyol and balsam, all used at some stage in these procedures, will not mix with water. Comes now this time to get rid of that last 5% of water remaining in the "pure" (9595) alcohol. The next step to come up is termed clearing and involves soaking the material in an oil to render it translucent and to permit passage into either paraffin for sectioning or balsam for mounting. Neither of these substances is miscible with al- Accept No Substitutes! Always Insist ou the Advertised Brand!

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cohol, but xyol will clear and will mix with alcohol on the one hand and with either paraffin or balsam on the other; hence it is generally re- garded as the ideal clearer. It will not tolerate even the smallest trace of water, however, and so two methods of passing the tissue into xyol are possible—either add something to the 95% alcohol which will take up the last trace of water, or put something into the xyol for this purpose. For the simpler method 100% alcohol is pre- pared—termed “absolute alcohol.” Get some blue crystals of copper sulphate and heat in a porce- lain evaporating dish over a low flame until the water of crystalization is driven off, leaving a white powder. Add a spoonful of this to a bottle ‘of 95% alcohol and shake. This form (anyhy- drous) of copper sulphate has a high affinity for water and will take it out of the alcohol, the powder turning blue, like the original crystals. Add powder until it no longer turns blue and keep this alcohol in a glass-stoppered bottle, with the stopper lightly greased with vaseline to ex- clude water vapor from the atmosphere. Let the powder settle to the bottom and pour off the alcohol slowly, as needed. The object being processed is now ready for sectioning by any of the methods described in the preceding installment. The most exact work would be done by using a hand microtome and the imbedding technique, in which case the tree bud or other object would be taken from xyol and bathed in the melted mixture of paraffin- vaseline for one hour, then placed in the well of the microtome, which is filled with the imbedding mixture, and sections cut when the whole is cold. The imbedding bath must be warm enough to keep the mixture melted, but no warmer and should not be too prolonged or it will “cook” and ruin the tissue. Next month, in connection with making your own slide dryer, we are going to describe a num- ber of devices that will be equally useful as a paraffin bath. For the present, try placing the imbedding mixture in a glass dish (e.g., a low Stender) together with the tissue, and lowering over this a gooseneck student reading lamp, ad- justing distance between imbedding dish and electric bulb until that temperature is reached that will just keep the paraffin mixture melted. The final installment in this series on micro- tecnique will tell how to stain your fixed and cut sections in the same way that professionals make their perfect slides, and how to mount and finish such a slide. Meanwhile, practice fixing and sectioning, and in order to see what your results are like up to this stage, stain a few of your best sections with tincture of iodine, diluted with ten volumes of 70% alcohol. Stain for one minute, wash off excess stain with fresh 70% al- cohol, pass through 85, 95 and absolute alcohol, five minutes each, then into xyol for five minutes and mount in balsam. If the stain is not sufficient- ly intense to bring out any structural detail in the material, allow a longer time in the iodine stain. When Answering Advertisements Please Mention June Mechanix Illustrated AUDELS Carpenters and Builders Guides GRU Th 4 vols.56 f Й Л. 7 ТУВ {nel Trade |, Information 2 ‘or Carpenters, Builders, Join- Сс Са Ие д т ers, Building Mochanics and "ТЕЧ ИГҮ all Woodworkers, These | Агент M A Guides give you the short-cut T i ТЕ T A instructions hat you wini En ALEI l ET including new rnethods, ideae, solutiona, plans, systems and money saving suggestions. AQ easy progreasive courae for tha apprentice ond etudent, Tactical daily helper and uick Reference for the master worker. Carpenters evorye where are using thesa Guides Ba a Helping Hand to Easier Work, Better Work and Bet+ ter Pay, To get this sasiste a: е впсе for yourself, вітрі, | | $ тт! 9 [» dorum ЕУ Eon Mcd ELA TATIN ATTS SIEA RAE АСВ $n and. mail tho FREE CO Inside Trade Information On: FON below. How to use the steel equare—How to file and веб saws-—-How to build furniture—How to use @ mitre box—How to use the chalk line—EHow to usa rules and scales—How to make joints—Carpentera atithmetic—Solving mensuration problems—Is- 4imating strength of timbers—How to Bet girders and sills—lIIow to frame houses and roofs—How to estimate costs—How to build houses, barns, gare ages, bungalows, etc.—How to read and draw plans—Drawing up epecificetions—How to ex- cavate—How to use settings. 12,.13 and 17 on the steel square—How to build hoists and scaffolds— skylights—How to build stairs—How to put on interior trim—TIlow to hang doors—lIIow to lath— lay floore—How to paint THEO. AUDEL & CO., 49 W. 23rd St., New York City Mal Audela Carpenters and Builders Guides, 4 vols., on 7 daya’ free trial. Tf O.K* I will remit $1 in 7 days, and $l monthly until $6 ie paid. Otherwise I will return them» No obligation unless I am satisfied, Address........ esee ett К rer rrr ТЫ: ‚экөө зө» Occupation. -.... ecce con нанне eeassevaesosesosereeveveceoscecooce emnmeneesen Ңе[егепсе....,...... РРТС FL soos M- M, AlL- PURPOSE MOTO-TOOL Everyone who works with his hands— at home, shop, school, or profession— can use the efficient, attractive Moto- Tool to advantage. Grinds, drills, routs, carves polishes all materials. Chuck uses many tools. You do in F seconds, jobs that require hours of hard, hand work. Sate, thousands in use. Two fine models. No. i weighs 6 oz. —about 20,000 r.p.m. No. 2 weighs 13 oz.—about 25,000 r.p.m. Order on 10 day money back trial, or send for free booklet. DREMEL MANUFACTURING COMPANY 1030CT Racine, Wis. $9 85 postpaid I0 Day Trial .. FüOD SENSATION. E CHEESE COATED POPCORN We furnish complete outfit enabling you to prepare new tasty food product. Made from fresh popcorn, blended with cheese. Men, women and children go wild over it. Sell your output at wholesale to stores, taverns, restaurants, eic. Startling profits. Equipment astoundingly low priced. Credit terms offered. Get into this money-making business while it is new. Particulars free. Send name and receive all the facts. j CHEESE-KIST CO., seninaritio, “ono 159

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No. 415-YA, 914” swing by 3’ bed Workshop Bench Lathe with Horizontal Motor Drive, 14 hep. Reversing Motor, Switch, Belts and Adjustable Belt Tension Countershaft. ($15 down—57 Monthly for 18 Months).......... REFLECTING 32 YEARS’ EXPERIENCE IN MAKING PRECISION LATHES ACHINING operations requiring the finest accu- тасу ате handled on the 9-inch Workshop Lathe with the same degree of precision that has characterized South Bend Lathes for 32 years. Con- structed from the same materials with the same work- manship as the larger South Bend Lathes, the 9-inch Workshop model proves a productive investment. Features—Precision Lead Screw for Cutting screw threads from 4 to 112 per inch, Twin Gear Reverse to Lead Screw, 94" spindle hole taking collets up to 14", Takes 38 attachments for milling, grinding, taper work, draw-in collet chuck work, and many other jobs, : SOUTH BEND LATHE WORKS ' 268 E, Madison St. South Bend, Ind., U.S.A. Write For These Books “How to Run a Lathe’—160 pages, with over 300 illustrations showing every type of work done on a lathe. Catalog No. 46 illustrates, describes and prices the 9-inch lathe in 3’, 34’, 4’, and 414’ bedlengths, and in 8 different drives. Contains value able shopinformation. Usethe Coupon. SOUTH BEND LATHE WORKS, 268 East Madison Street, South Bend, Ind., U.S.A.

O No. 46, 9” Workshop Catalog, Free. L] Easy Payment Plan, Class of Work. ........ Name.. «о оевазьво з о евае No. 33LB “How to Run a Lathe,” 25c. | [3 < Less Motor $117.00 Payments as Bere E Month for.12 - = to 18 Month B Other Sizes: 9^, 11", 13", 15" and 16” Swing. In 3’ to 12’ Bed Lengths. Priced from. $97 to $1500. Below is No. 117-C, 16” x 6’ Quick Change Gear Underneath Belt Motor Driven Lathe § 969 with 1 H.P. motor. Weight 2300 lbs, ($194 down, $38 Monthly for 22 Months) LATHES STOCKED IN PRINCIPAL CITIES Chicago—C.B.BurnsMchry., 541 W. Wash. Blvd, New York—AÀ. C. Colby Mchry., 183 Centre St. Philadelphia—W. B.Rapp Mchry., 132 No. 3rd. L. Angeles—Eccles & Davies Mch., 1910 Santa Fe. Detroit—Lee Mchry. Co., 6318 E. Jefferson Aves Milwaukee—Voell Mchry. Co., 1533 No. 16th St. Boston—MacKenzie Mchry. Co., 36 Oliver St. Cleveland—Reynolds Mchry., 2034 E. 22nd St.

Accept No Substitutes! Always Insist on the Advertised Brand!

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Spring Overhaul On The Boat [Continued from page 145] colors together they can be wiped off at once. If any paint touches varnish, wipe it off at once. And DON'T paint around wet varnish, or varnish around wet paint. Sand each coat of paint after it is dry if you want a smooth job. Where two dif- ferent colors separate it is well to cut a line with a race or scrieve knife so that the line will always be easy to follow. This will apply on the hull where the anti-fouling paint meets the topsides. Leave the anti-fouling until the very last, as you still have some work left on the bottom, which has been purposely laid aside until this time. After all the bad places have been repaired on the bottom, the hull should be worked over with a wire brush to remove all the loose anti- fouling paint. The whole bottom up to the topsides should then be given a fresh coat of anti- fouling. Just before the boat is ready to go in the water, the second coat is applied so that it will still be wet when the boat is floated. Seams that have opened with the drying out of the hull due to the warm and windy weather should not be caulked if they are less than a sixteenth of an inch, as the wood will go back this much when the boat gets in the water. The wider seams should be caulked with caution and then only with a thin strand of lampwick. Before the last coat of anti-fouling paint is applied and the boat is ready to go over, putty all the open seams with a mixture of tallow and red lead, which will keep the water out until the planks have swelled, at which time it will easily squeeze out of the seam. Yellow laundry soap and white lead make another good putty for this work. The soap is melted and white lead added to it. Whiting and tallow make another good putty. When it is launched have a can of dry oatmeal or sawdust on hand, If the hull is leaking badly and shows no sign of letting up as the wool swells, a handful of the meal should be placed as close to the leak as possible on the outside of the boat. The water working into the leak will carry some of the flakes with it and they will jam into the hole. With the swelling of the meal or sawdust the leak soon stops and a hauling-out is saved. Some leaks appear to originate at a spot which reason leads us to believe does not leak. The boat should be sponged and the trickle of water carefully followed. Some aluminum powder sprinkled on the water in the bottom of the boat soon will give us the direction of the flow and the leak may be traced to its source and stopped. Sometimes a little careful chinking of the leak from the inside will help a lot and last an entire season. The real cure for any leak on a boat is to fix it from the outside. If the boat is a motorboat, the motor should be checked for alignment by uncoupling the shaft flanges to determine if the two faces are parallel. If they are not, the motor should be shimmed up {Continued on page 162] When Answering Advertisements Please Mention June Mechanix Illustrated Works for State of Jilinois I had not taken your Course I would stll! be digging ditches. І ат working for the state of Illinois, operating the 1,000 watt transmitter, » А . LEW State Police Radio деп, WQPM, Mac Picked up $1,800 While Learning "I picked up 81.506 while studying. I call that easy m o n e y—the aime I gave my Radio work did not interfere other OTIS DENTON, Lorain Avenue, Cleveland, Ohio. orklng in & garage with no future in sight. My wife and I decided to put aside enough to wey, for my Course. | We have not regretted it. I have made as high as $400 a month in Radio," E. G. WOLFE, 1202 Eden St., Elkhart, Ind. ET J. E. SMITH Dear Mr. &mith: NAME land Full Time Jobs & in RADIO:- President National Radío Institute, Dent. 8FH, Washington, D, C. Without obligating me, send “Rich Rewards in Radio," which points out the spare time and full time opportunitles in Ttadio and explains your 50-50 method of training men at home in spare time to become Radio Experts, (Please Write Plainly.) you don’: һас» т leare home w 3 a become a Radio Expert, Many Radio Experts Make 330, $50, 575 a Week Radio broadcasting stations employ engi- neers, operators, station managers and pay up to $5,000 a year. are time Radlo set servleIng pays aS mi as $200 to $500 a year—tu]l time Rad vicing jobs pay as much as $30, $50, $75 a week. Many Radio Experts own and operate [uli time or part time Radio businesses. Radlo manufactur- ers and jobbers employ testers, inspectors, foremen, engineers, servicemen, paying up to $6,000 a year. Automobile, police, avia- tion, commercial Radio, and loud speaker Systems offor good opportunitles now and for the future. Television promises many good jobs soon. Men I have tralned at home have good jobs in all these branches of Radio, Many Make $5, $10, $15 a Week Extra In Spare Time While Learning Almoast every neighborhood needs a good spare time serviceman. The day you enroll I start sending Extra Money Job Sheets show ing how to do Radlo repair jobs. Throughout your Tralning I send plans and ideas that made good spare time money for hundreds. I send Special (артеле to pons duct experiments, bu elrcuits, get practi- са1 ех rience I ALSO GIVE You A COM- WAVE, ALL PURPOSE RADIO SET SERVIC- ING INSTRUMENT TO HELP SERVICE SETS I CRER SAVE TIME, MAKE MORE Find Out What Radio Offers You Mail the coupon now for “Rich Rewards in Radio." it's free to anyone over 16 yearg old. It points out Radio's spare time and full time opportunities and those coming in television; tells about my Training In Radlo and television; shows you letters from men I trained, telling what they are doing and earning: tells about my Money Back Agree- ment. MAIL THE COUPON in an envelope, or paste it on a penny postcard —NO W! J. E. SMITH, President National Ridio Institute Dept. 8FH il this Now - Get 64-page Book AGE

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Spring Overhaul On The Boat Science Is King! [Continued from page 161] on its bed until both flanges meet without any opening around their circumference. The joints of the fuel line should be gone over and checked for leaks, and if there is a strainer in the line (which there should be) it should be cleaned so that all of the last year’s sediment will not get back to the motor. The stuffing box should be repacked if it shows any signs of a leak and the gland should be set up again no tighter than necessary to stop the flow of water. The exhaust line should be examined and all badly rusted parts scraped and the pipe given a coat of aluminum paint. If you own a sailing craft the spars should have been scraped and varnished when the rest of the bright work was done. The wire rope rigging should be gone over for badly rusted spots and renewed if necessary. If the running rigging is worn at places and still looks good, it should be reversed or turned end for end so that the worn parts will not come in the same position as they did when last used. The sails should be spread out on the lawn to air and examined for bad places. Rips can be mended with baseball stitches or a patch. If the sail is dirty a good scrubbing on the dock with soap powder and a broom will work wonders. It should be rinsed overboard and if slightly mildewed it should be rinsed in a tub of clear water with some mild laundry bleach, and hung out in the bright sunlight to dry. Be sure that it is thoroughly dry before bending it on the boat. A hopelessly mildewed sail that I saw last spring was revived and modernized by dyeing it blue; this is the only color that will hide mildew. If you are purchasing new sails be sure to have them mildew-proofed by your sailmaker before they are placed aboard the boat. When all the sails are bent and you are looking about for other things to do, shine the long neglected brass work and nickel. This can be kept bright for half a season by applying some metal lacquer in a thin coat. The galvanized work can be brightened up a bit by applying a coat of aluminum paint. Last of all, look at the long neglected dock lines and mooring ropes. If they are in bad condition renew them, as they may fail at a critical moment and all the work put aboard the boat would be useless. With all the work finished you can at last loll on the deck satisfied that as the old sailors would say, “everything is ship-shape and Bristol fashion.” Traces of black, brown, and red color on the Egyptian pyramids have been studied by a Brit- ish scientist, who concludes these are not traces of ancient paint on the pyramids, but are natural coloring derived from the stone itself. Cigarettes gained popularity in the Crimean War when soldiers used cartridge paper to roll smokes. 162 (Continued from page 139] ticularly true since the world learned from Gali- leo the science of inductive thinking. And a tremendous volume of progress has been achieved by the labors of men quite without aca- demic background and education. One thinks immediately of the Wright brothers, who had a bicycle repair shop. The French Academy of Sciences and many other learned bodies be- stowed all sorts of honor on them in later life. But when they started out on those experiments that astonished the world, their book-learning was exceedingly small In "The Work, Wealth and Happiness of Mankind," H. G. Wells points out: "The activities of the gentlemen who launched natural philosophy upon the world needed to be supplemented by work of a coarser type before they could realize its vast potentiali- ties. There were practica! men, mostly mill- wrights and often with no education (Brindley could scarcely read and could write only with diffieulty), who understood the present needs of the day and the practical difficulties in the way of overcoming them." In a larger sense, however; all this discussion of who invented what comes down to a matter of almost legal quibbling. But it bears out the claim that everything in civilization today is the accumulated result of the work of thousands of minds, some of them working in obscure and for- gotten ehannels. I suppose the last place where such facts will be recognized is the school room. History con- tinues to be a recitation of the acts and achieve- ments of statesmen, soldiers, conquerors, many of them no better than gangsters. When the text books pay as much attention to Faraday and Oersted as they do now to Napoleon and Talley- rand, civilized thought will have advanced a bit further. Glazed Traffic Lines Terra-cotta is the latest material to be used for guide lines to separate streams of traffic. In the new Lincoln Tunnel under the Hudson River between New York and New Jersey a double line of white glazed terra-cotta blocks have solved the difficulty of painted marks, which wear off, and of concrete markers, which become discolored by traffic. The terra-cotta is white throughout its thickness, and remains white and shining regard- less of wear. Mineral wool is favored by many architects for insulating houses against heat and cold, but it is too bulky to be transported far by rail economically. : Television cameras, to be tried in England, are several times more sensitive than those previously used.

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NEW TIRE WINS IN SENSATIONAL NON-SKID TESTS ! YOU NEED THIS NEW KIND OF TIRE IN WET WEATHER READ THE REPORT- from America’s Largest IS EMERGENCIES LIKE TH Independent Testing Laboratory e Bor regular, and also the premium-priced tires of America's six largest tire manufac- turers were submitted to a series of exhaustive road tests made over a three months' period by us, to de- a resistance to skid- a ; E ха wear, with the following te . NON-SKID—The new Good- rich Silvertown with the Life-Saver oe Save greater skid resistance than any other tire tested, includ- ing those tires listed at from 40% to 70% higher in price, " MILEAGE—The Goodrich Sil- vertown gave more non-skid mile- age than any of the other tires tested in its Own price range—ay- eraged 19.195 more miles before the tires wore smooth." Stops Quicker, Safer Than Tires Costing up to 70?6 More! ERE, at last, is a tire so utterly different in action that, at the first sign of a skid, it turns the wet road under your car into a "ry" surface. In exhaustive road tests made by the largest independent testing laboratory inthe country, against regular and premium- priced tires of America's six largest tire manufacturers, no tire tested, regardless of price, came up to this new tire in non-skid action. For safety's sake, ride on Goodrich Safety Silvertowns. See your Goodrich dealer or Goodrich Silvertown Store now. Don't gamble on blow-outs. Every new Goodrich Safety Silvertown is con- structed with thenow » famous heat-resisting Golden Ply that gives you real protection against high-speed blow-outs. The never-ending spiral bars ofthe Life- Saver T'read act like a battery of windshield wipers—sweep the water right and left— force it out through the deep grooves... give the rubber a dry track to grip. RINTE, кеа U.S. A-

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4 = Chest MORE PLEASURE .. better taste .. refreshing тіне Copyright 1938, Liacerr & Myers ToBAcco Co.

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MODELS AND FINISHED DRAWINGS UNNECESSARY Don't spend money or time on finished models or drawings before you know your invention may be patentable. Our large staff of experienced patent searchers can handle a search from your description and roughest sketch, The main thing is to put it in our hands as promptly as possible. DELAYS ARE DANGEROUS IN PATENT MATTERS 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 invention. In such case, the burden of proof rests with the last applicant to file. Sometimes a delay of even a few days in filing the ap- plication means the total loss of the patent, LOSE NO TIME. CLARENCE A.0BRIEN & HYMAN BERMAN 317-D ADAMS Bi How To Determine The Patentability Of Your Invention Before you spend money in making a model, or spend weeks in its design, we advise you first to have a preliminary search made through U. S. Patents in the U. S. Patent Office to see if there are inventions like yours already on record; and, if so, let us give you our opinion as to the patentability of what you ave. We employ experienced searchers to perform this service for you. From the reports of our searchers ‘we can quickly form our opinion as to whether your invention is confronted with obstacles in the form of already granted patents. First get our FREE BOOK and read the chapter on “How Can I Know ‘Whether My Idea Is Patentable?” Latest Facts On Inventions, Patents and Markets For Inventions ‘The very latest. information on all matters affecting your invention—all inventions. Don’t act until you get this Free Book! It reveals important information on obtaining patents, establishing a market for in- ventions, getting financial aid, using patent to secure commercial success, 48 pages crammed full of illus trations, helpful and interesting statistics, Patent Office data, rulings, a detailed guide on how to patent and protect your invention. ‘This new book will be sent promptly—have the most up-to-date guide to the things you must know to simplify patent procedure and save time, the vital thing to you! FACTS ABOUT OUR SERVICE We are registered U. S, Patent and Trade-Mark At- torneys, serving inventors all over the United States. Our organization is complete in every particular. We have Draughtsmen, experienced Searchers, and At- torneys to serve your interests. We have had years of experience in patent matters and know every angle of legal approach. We will secure protection for your invention if it can be done! But the longer you delay the harder it may be for us to serve you. ING, WASHINGTON, D. €. Registered Patent Attorneys before U. S. Patent Office This FREE BOOK d [i THIS FREE BOOK TELLS HOW Your Patent Application is made; what kind of sketches or drawings are necessary; what other papers must be made out; how the Patent Laws protect you; why it is important to avoid loss of time in getting your application filed; and many other important points. Even a very simple in- vention, if new and useful, may prove very valuable, You may have much to gain and nothing to lose by sending for this book TODAY. THE FIRST STEP When you place your invention in our hands, we are in position to proceed at once to secure protection for you. Our fees are rea- sonable, and, if you desire, we can arrange convenient terms of payment. We will send you our Record of Invention form FREE, This blank will enable you to make a sketch of your invention in proper form and have it witnessed in Such manner that it may be of value to you as evidence should the occasion for evidence arise. In our book, we tell you how to use this form to protect your interests. Every year thousands of Patents are granted. Very few, however, represent the discovery of entirely new principles. Most of them provide new methods of doing some everyday thing in a better way. These improvement Patents offer large chances for profit if commercially useful. ‘The business world wants improved products and services. OUR OFFICES IN THE HEART OF THE NATION'S CAPITAL Located in Washington, D. C., within a few blocks of the U. S. Patent Office, we are able to give you immediate advice and accurate, authentic information on all matters concerning 8 Шот па ЧГ quide and asist yoi Patents and Trade-Marks, particularly if it is necessary to ton 'and haa 1t wtmane) i's mint of lle examine the records in U, S. Patent Office. FE + FREE. BOOK tells yon Row Storm à pied jou FREE RECORD OF INVENTION FORM Hb yon prefer to use a form made, specially fer The Purpose ul recording the esriptive euis зш invention oe oar earners” use at the TL Re patent Of write today ter ou бест Of Invention tormesic"will guide and шы Soa, Don't be discouraged or disheartened about the fu- ture until you get our FREE BOOK and learn how other inventors succeeded de- spite lack of funds, remote- ness from market, lack of mechanical skill, education, and other handicaps. Send coupon for this FREE BOOK today!

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ENT. FOUR INVENTION >> > ‘PATENT YOUR INVENTIEN >> «€ 5HDUH ee eee мом Py—Acjaq 3,uog эмшаипа модом 9-9 SASMUDAEE LNTIVd. O3H3ISIOSH dejs 3XeN тод SHO1N3ANI OL LNVILHOdMI n ; °з у SIHO]H #100 10311044 01 MON Sd3l$ 3JVL SLSLLUY = TU em M SOINVHOSR (7 2) suanuva Gre H3. dN35 XM: Asl SEND SKETCH ON MODEL iz BIA SEND: SHETCH OR Vit TO hear When Answering Advartisements Please Mention Fane Mechenie Uh Accept Mo Substitutes! Akonys Insist on the Advertised Brandt

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Built by Lloyd Spriggle, this trim streamlined motorboat Бан е ы баин ӨР АП Колын ашны І: WILL take you longer to read this issue of MtcuaNix ILLUsrRATED than previous issues of your old friend “Modern Mechanix,” for the simple reason that we have added 16 solid pages to the editorial section! I am sure that you will like the many extra articles, the descriptions of new ideas and inventions, the big pictures, and the enlarged drawings of construction projects. True to its name, Mecuanrx Intustratep will em- phasize illustrations of mechanical developments; it will publish live, human-interest photographs that you will find interesting, instructive and helpful. Workshop fans will, I am sure, be pleased to know that more space will also be given to the ever-popular “Workbench” Department. Every month we receive hundreds of fine letters and pictures showing shop projects made from our plans and blueprints and we intend to publish as many as we can, to show how capable and skillful MrcnaNIx ILLUsTRATED readers really are. Send in your letters and photos for judging in next month's Workbench contest. ^ First on the line this month is Lloyd Spriggle, of Bay City, Wis, who was awarded a $5 prize for his photos and letter describing his home- built boat. He writes: 14 Dear Editor: T am enclosing prints of my home- built boat. The rumble seat is en- closed by a cover which has sliding doors. When closed, the doors drop flush with the top creating a perfectly streamlined unit, which is strong enough to walk on. Lloyd Spriggle. You didn’t supply any informa- tion about speed, construction time, etc, Lloyd, but I just had to award you a prize because of the boat’s appearance. It sure is a beauty. *e- Remember the photo enlarger plans that ap- peared in our March issue? Well, C. E. Prange, of Toledo, Ohio, scored a $3 prize by sending in a photo of the enlarger that he built from those plans, He says: Dear Editor: Here is a photo of the enlarger that I con- structed f ro m the plans in your March issue. It gives excellent re- sults. Your amateur photography section is great and I have re- ceived some good ideas from it. C. E Prange. Thanks for C. E. Prange built this oto enlarger from plans in our March, 1938 issue. Johnnie Bray and his home-built “five mule-power” tractor. Mechanix Illustrated—June, 1938 the kind words, Prange. I'll do my best to keep you amateur photo fans supplied with practical suggestions and how-to-build articles, Incidentally, the enlarger plans are reprinted in our new PHOTOGRAPHY HANDBOOK, now on sale at camera stores and on | newsstands everywhere. s: Tm not a farmer, but I cen tell a good tractor when I see one, and that's why I sent a $3 award to Johnnie Bray, of Pinson, Tenn, whose letter reads: Dear Editor: The enclosed photo shows a tractor built by my brother and me, It features a four-cylinder engine and differential Harold Huntley sent in this photo of a racer built by a friend. which were salvaged from old autos. The machine does the work of five mules and has six forward speeds and one reverse. The total construction cost was only $20, as we used parts from seven old autos and one tractor to build it, Johnnie Bray. I wish I could invest $20 as profitably as you apparently have done, Johnnie! ss You fellows who itch to get behind the steering wheel of a little four-wheeled “put-putter” will be interested in the letter I received from William Graham, of Hazel Park, Mich., who was Capable of going 40 mp.h., this tiny racer was built by Froilan de los Santos, in far away Manila, P. I. wheel. William Graham built this midget car for his son. Lucky boy! formerly Modern Mechanix also awarded a $3 prize. He says: Dear Editor: Enclosed is a photo of the midget racer which I built for my son from your plans. It is powered by a l/zhorsepower lawn mower engine hooked up with a chain and V-belt drive. For safe operation I geared the car so that it will go 10 m.p.h. William Graham. I bet young Graham gets as much thrill when going 10 mph, in his racer as some of you older fellows do when you eat up the road at 70 or even 100 mph. Take it easy, fellows, or “life may end at 40!” m From the far away Philippine Islands I received a letter from another midget-racer enthusiast, Froilan de los Santos, who was also winner of a $3 award. His letter reads: Dear Editor: I am a constant reader of your magazine. It is the real thing when it comes to dishing out information on mechanical projects. The en- closed photo shows a midget racer which I con- structed with the help of your information. The car is powered by a motorcycle engine and goes 40 m.p.h. at full gun. With the excep- tion of the engine, wheels and headlights, every- thing is home-built, even to the small steering Froilan de los Santos. [Continued on page 16] 15

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The diagram shows a cross-section of a modern blast furnace. The coke, limestone and ore are dumped in at the top. The molten iron and slag col- bottom of furnace where they are drawn Off at regular intervals. CHIMNEY CHECKERS TO HEAT AIR PROCESS OF HEAT i ABSORPTION FIREBRICK| PROCESS Dres Team] |cAm] оғ EURO coL Am FROM BLOWER OCES: COMBUSTION а молн SLAG COKE | IRON IRON LADLE m ас == Se CALE А бк сая „ш E я. сыс IRON At right is shown-a er ‘a Bessemer consists of a hu steel pot, lined Lie BURNER Ps th heavresist- p tom: After the fiery liqu AR pure iron. and manganese are EI UT: and the white. parce urere S BOTTOM FULL OF HOLES LIKE THIS. INRUSH OF AIR HOLDS UP THE METAL Lo M rosy today produce 91 per cent o the steel in the United Molten iran and other mat RETI uo rp en from a nearby oven blow over them. The molten steel is drawn. off from furnace bottom. BESSEMER CONVERTER CHECKERS. | H | by Robert W. Gordon A silhouette of a large steel mill, Bessemer converters emit tongues of fre which can seen for miles at night. The color gradually ci changes from red to a yellowish white. Left—Blast furnaces and ore docks at Cleveland, O. The blast furnaces are at the left and right. The round struc- tures between are stoves wi heat the air for the bi —Photos mem Republic Steel Corporation WORLD without steel—try to imagine it! Without steel, the whole physical struc- ture of the modern world would collapse. Lacking this one all-important substance, the civilization we know would cease to exist. There was, of course, civilization long before the discovery of steel, but it was vastly dif- ferent from ours; so different that it requires an effort of the will to picture a world without steel. Without steel— There would be no buildings higher than walk-up distance; no airplanes, no automo- biles, no modern railways or fast steamships. Without steel— Foodstuffs would be largely limited to what could be grown locally, and the threat of famine would be ever present. The horse and the sail would still be the principal means of transportation. Without steel— There would be no modern factories, in- dustry, cutting tools, or power machines. Countless features of the twentieth century world would be non-existant. The United States would be back in the era of the horse and buggy. The changes wrought by steel have been 43

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THESE 4 GIANTS OF THE AIR ARE DRAWN TO APPROXI- MATELY THE SAME SCALE

"TURING FLIGHT TO COMPLETE ‘LIGHT TO COMPLET SEVERSKY "ETREAMUNE SHAPE OF FUSELAGE "SUPER-CLIPPER" TOTAL H.P: 16000 ESTIMATED CRUISING SPEED: — 250M P.H. PASSENGERS: 100-120 ‘SPAN: 250FT. The comparative sizes of the proposed Seversky sea- plane (250-foot span) and other airliners now under construction, as well as a present day transport plane, are graphically shown in the artist's sketches on this page. NEWDOUGLAS DC-4 —3-— TOTAL H.P (4MOTOR): 5,500. CRUISING SPEED:2IOMPM — — PASSENGERS: 42-CREW: 5 HERMETICALLY SEALED CABINS FOR CRUISING AT HIGH ALTITUDES LANDING GEAR EXTENDED TO —> SHOW TRICYCLE ARRANGEMENT

TOTALH.P.(4 MOTOR): 4,400 CRUISING SPEED(EST):200m.P.H.

TYPICAL TRANS-CONTINENTAL PASSENGERS: 33DAY-25 NIGHT Y AIRLINER IN SERVICE TODAY AND DST

BEANS | DOUGLAS DC. i MAXIMUMH®.(2-MOTOR): 2.000 CRUISING SPEED: 190- 200M.P.H PASSENGERS: 24DAY-16 NIGHT SPAN: 95FT.

Shown below is Col. Alexander P. de Sever- sky with a scale model of his proposed 120- : Passenger transoceanic twin-hulled flying boat. LARGE 3 BLADED TRACTOR AIRSCREWS EACH DRIVEN BY TWO 2/000 HP. ENGINES LANS for a super-clipper seaplane’ capable of carrying 120 passengers at 250 mph. for about 5,000 miles non-stop have been submitted to Pan American Airways by the Seversky Air- craft Corporation. The proposed air giant, with its wingspan of 250 feet, would dwarf the huge Boeing Stratoliner and Douglas DC-4 transport planes which are already under construction. (See accompanying sketches.) Mechanix Illustrated—June, 1938

ъз» ^s ^h. = "tes hes MM AA ARA Eo LOAD(PASSENGERS | | AND BAGGAGE). i. ———| PAY|LoAo 4 ooucLAS| BoEING | DoUGLAS || SEVERSKY / TYPE DST |STRATOUNER)| TYPE DC4 || SUPER-CLIPPER-/ POWER & PAY LOAD CAPACIT Y OF PROJECTED AIRLINERS COMPARED WITH TYPE NOW IN USE The novel chart at the right provides a visual comparison of the power and pay load capacity of the projected and present

day airliners. The Seversky plane, a giant among giants, will be capable of flying from New York to London in 14 hours.

o?monor

y

AFT STARBOARD DINING SALOON AND AFT ENGINE / ENGINEHOUSING PROMENADE LOCATED COMPARTM'T £ | е 1— RELATIVE SIZE ON EITHER SIDE = ч > OF FOURPLACE CONTROL BRIDGE OF NACELLE / STATEROOMS = 5 = FLOAT SEAPLANE AND OFFICERS" 4

QUARTERS GALLEY | COCKTAIL LOUNGE AND OBSERVATION | a CABIN T

L F h

Ў? STARBOARD FUSELAGE є ARRANGED SAME AS PORT SIDE

o

Ld < SLADED PUSHER ArT FUSELAGE АБАБ оно Ei GEARED ENGINES LANDING » PD cu E O CREWS QUARTERS — WASH ROOMS BETWEEN CABINS AFT PORT ENGINE DRIVES 3-BLADED PUSHER AIRSCREW =

‘CARGO SPACE IN BOTH PONTOONS: WING STATEROOMS FWD. FUSELAGE STATEROOMS PORT FWD. ENGINE COMPARTMENT The elaborate interior and constructional fea- tures of the proposed Seversky super-clipper are sketched above. The hulls are retractable. formerly Modern Mechanix

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“Mechanix Illustrated” These pictures are representative of the effort and facili- ties put behind Vitaphone pictures. Above: A railroad sequence bi a huge sound stage in the Vitaphone studio in New York, where more than a hundred "shorts" are pro- duced every year. OMETHING new and unusual in movie “shorts” will be offered to the public when the first of a series of Vitaphone- MECHANIX ILLUSTRATED films is released soon to theatres throughout the country. Made in full natural color by Warner Brothers’ Vita- phone Studio in collaboration with the editors of this magazine, these absorbingly inter- 70 esting movies will take audiences into sci- ence's laboratories and industry's factories, and will show for the first time how many of the marvels of our modern civilization are conceived and produced. The films will run about ten minutes and each will deal with four specially chosen topics. However, months of preliminary in- Mechanix Illustrated—June, 1938 In The MOVIES vestigation and preparation have been put into them. Warner Brothers production experts and cameramen, accompanied by members of the MEcHANIX ILLUSTRATED edi- torial staff, visited many locations in their quest for colorful, human-interest material. and spent many hours on research before [Continued on page 144] tormerly Modern Mechanix Vitaphone Shorts" In Natural Color Will Be Unique, Interesting SS Above: Sam Sax, head of Warner Brothers’ Vitaphone Studio, Brooklyn, N. Y., under whose supervision the MECHANIX ILLUS- TRATED films are be- ing made. ‘The two pictur left show Vi camera crews on the job. Top: filming the permanent model rail- toad built up by the New York Society of Model Engineers. Left: The color camera re- 1 dyeing op- p a heavy camera and « battery of powerful ii times takes hours, while the actual shooting may take only a few minutes, Don't miss first Vita- phone-MECHANIX ILLUSTRATED film! Mail us the convenient coupon below on write us a postcard if you do not want to cut your copy of the magazine. No obligation on your part, of course. Editor, MECHANIX ILLUSTRATED 1501 Broadway, New York, N. Y. I want to see the first of the Vitaphone-MECHANIX ILLUSTRATED Shorts. Please let me know when my local theatre ses ~. (please fill in its name) will show it. Name ....... Address .. City State 7

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Drive Next Year's Car Today by Frederick C. Russell Ingenious new accessories will put your car a year ahead in comfort, convenience and safety. Blowouts or bumps mean nothing to s car when it is equipped with a hydraulic steering stabilizer. This device takes control of the wheel in an emergency and prevents the car from leaving its true course on the highway. Right—The stabilizer fastened in place. HETHER your car is a sparkling 1938 model or something which you are obliged to drive another year, it has never been easier to have a taste of tomorrow's motoring—now. The idea is suggested by the offering of an unusual number of ingenious and practical accessories. These new gadgets banish some of the ancient fears in driving, shorten the time required to keep the car up to par, and step up performance in a num- ber of ways. Do you drive in constant fear of a blowout? Are you annoyed by the penalty for for- getting to add water to the battery? Do you feel that the engine should give better per- formance, and would you care to try super- charging? Are you still changing engine oil every thousand miles? Do you envy those who are enjoying many new conveniences which you assume are available only on new cars? If so, step right up to the accessory counter and take your pick. Your 1939 car is ready! Automotive engineers are looking over the present automobile with a view to seeing what new uses they can find for principles 74 already employed. helped in the creation of a device that takes It was this policy that the hazard out of blowouts. If hydraulic shock absorbers control spring action, why not use a special shock absorber on the steer- ing tierod? Why wouldn’t this device effec- tively check the tierod's movement, in event of a front tire blowout, and prevent the steer- ing wheel from snapping out of the driver's hand? When an automotive engineer asks “why?” he generally ends by providing the answer. So a four-star accessory is born. With this large hydraulic hand on the car it is possible to strike a railroad tie with one of the front wheels while the car is traveling sixty miles Mechanix Illustrated—June, 1938 от Imagine driving the doors open ai an hour—and live happily ever after, even if the driver takes his hands from the wheel! No one wants to try that stunt, but the steer- ing stabilizer is built to give that much margin of protection. Whether the car’s stability is endangered by road obstruction or by tire collapse it continues in a straight- ahead direction unless the driver finds it necessary to steer to the right or left. To- morrow’s car will have this protection, but you can have it today. Solving the problem in a somewhat differ- ent way is the special inner wheel which serves to prevent that dangerous drop which occurs when a tire blows. The inner wheel takes over the job of supporting its end of the car until the driver has a chance to slow formerly Modern Mechanix е garage, touching a button. lly and close when the car this magic feature now. Why wait for it to beco shown that this ice is particularly ful when the out. side air is very dusty | f dash and having . You can have tandard equipment? down and stop. Instead of dropping the dan- gerous distance to the rim the troublesome wheel drops only an inch or so to the edge of the safety inner wheel. Even though flat as a pancake the tire cannot offer that ter- rific resistance which usually is sufficient to throw a car out of control. With either or both of these devices on the car, and with those special inner tubes which are being offered by major rubber companies, the fear of sudden tire collapse is definitely out of the picture for any motor- ist who wants his future motoring today. These safety inner tubes do away with the annoyance as well as danger from punctures. There is no particular magic about it. The thick center section of such a tube is turned 75

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Pounds of wire is fequired for both Т Er Left—Tap each layer of vire neatly im place with « rubber or wood malle Right—By tapping the end of the tapered wood core on a hard surface, coil will slide off easily. Ends of gauze strips are tied to hold windinj ROM an examination of the design of the MI Are Welder you will see that its prin- cipal features are simplicity of construction and low cost, but you will have to hold the electrode in your hand and give it an actual trial in order to realize the amount of sizzling, crackling heat it will generate. The cost of building a welding transformer is in close ratio to the amount of current it will deliver without overheating. For ex- ample, you would need about 36 pounds of wire for one rated at 2,500 watts, and only 12 pounds of wire for one of one-third that ca- pacity. When the former is used for light work, a reactance coil is needed to reduce the amount of current. Having in mind the needs 88 of the man in the home workshop, the M I Are Welder was designed exclusively for light work. It consumes less than 1,000 watts and therefore can be plugged into almost any 110-volt a.c. socket. It does not require the further expense of an auxiliary reactance coil. In addition to doing light welding, it is ex- cellent for quickly soldering large work. The voltage is low so that even a child cannot re- ceive the slightest shock. Finally, unlike outfits of larger capacity, it may be used con- tinuously without overheating; ordinarily it will barely become warm. For the primary and secondary coils of the transformer you will need a full 6 pounds each of No. 10 and No. 12 S. C. E. (single Mechanix Illustrated—June, 1938 cotton enamel) magnet wire. The primary coil consists of 300 turns of the No. 12 wire and when in place over the iron core of the transformer it is connected directly to the 110-volt, 60-cycle alternat- ing current line. The sec- ondary coil consists of three coils of 60 turns each of No. 10 wire, which are wound one over the other and the ends of each then connected in parallel. This delivers the heavy current necessary for welding. The winding form consists of a 12-inch length of wood that is 2% inches square. Taper it slightly towards one end, so that the finished coils can be slipped off easily. Then sand it smooth and ap- ply a coating or two of wax. In order to confine the coils to a width of 4 inches you will need two 5-x5-inch squares of wood, one of which is screwed to the larger end of the form, Cut a 2Y4-inch square hole in the center of the other and slip it over the form so that it is 4 inches from the first, then wedge or screw it tightly in place. Cover that ч part of the form between the squares with a a thickness of waxed paper, then lay a 15-inch length of 2-inch cotton gauze bandage tape lengthwise of each of the four sides of the form. The ends can be held out of the way formerly Modern Mechanix [es ener rary ae coil with cotton; gauze. outside of cach coil then is coated with shellac. Right— EU Sama Ыс Dove eres dary are soldered to the heavy electrode. and ground cables. 3

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USES FOR by Raymond B. Wailes Sodium silicate solu- tion has many com- mon uses, several of which are shown in : these photographs. Diluted with three parts of water and applied with a wide brush for speed (above), water glass J Solution can be used $ to waterproof ce- ment walls, Several coats should be applied, allowing enough time between. coats for the solution to dry thoroughly. A half-teaspoonful of water glass added to the water in laundry tubs will increase the amount of suds and soften water, effect- ing a saving in soap (above). A cement made of water glass and whiting is excellent for repairing cracked ceramics (above). Water glass alone can be used to unite shattered glass objects. Applied with a broom (above), a dilute solution of water glass and three parts of water makes an ideal treatment for cellar workshop floors, eliminating the carrying of concrete-dust footprints to other parts of the building. The solution can also be applied just as effectively with a small stiff brush. Мапу огеаѕе ѕро{ѕ 1а? саппої Бе гетоуей міћ огдіпагу. cleaners can be removed by applying water glass to the spot уідогоц5ју мі а Сеап гаф (аһоуе). and rubbing 92 Glass tubes can be cemented in metal pipes (above) by using a cement made of water glass and whiting. M a cement more resistant to acid is desired, prepare a mixture of water glass, glycerine and litharge and apply profusely at joint where pipe meets glass. The adhesive quality of water glass is shown in the photo above. The cardboard flap was coated with water glass and held against ‘the building where it stuck immediately, The solution fireproofs materials somewhat. Apply it to amateur stage scenery. When it is desired to fasten glass to metal, make a paper gasket and place it between the glass and metal, using water glass as a cement on both sides of the gasket, as shown above. Apply the water glass on the gasket evenly with a small brush. Applied without diluting, water glass can be used to cement rubber matting to an automobile running board. р

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This photograph of Patty just before launch- ing shows clearly ber trim r light weight it essy to put ber in or her out of the water when by J. Julius Fanta O END of service can be derived from this snappy skiff, Patty, an ideal project for the home workshop. Constructed during leisure hours, this craft with many purposes will be ready when the “sailing bug” comes around again. Patty is eight and one-half feet long, roomy enough for four persons without crowding and is rowed as easily as a canoe is paddled. Patty makes an ideal dinghy, or tender, for a small yacht—sail or power—as she is feather-weight for hoisting and compact for stowing on deck. Propelled by a light out- board motor attached to the transom, she is a fast job. On fishing trips, this type and size is just the thing for hauling atop the car or on a two-wheel trailer. In fact, this flat-bottomed skiff with lap-strake construc- tion is adapted to serve your every need. Safe in rough water, Patty rides waves like a cork without shipping water. The lap- strake planking method makes the “skin” durable and stays leakage. Planks are fas- tened with clout nails. If a sailing dinghy is preferred, it is a relatively simple matter to install a centerboard, or a detachable fin. 94 Inexpensive and easy to build, this small sailing skiff will give many The fact that the mold frames serve as the actual frames of this boat saves much time and effort in construction. Additional ribs to stiffen the hull are put in later. To begin with, make the keel out of 1%”x3” white oak 7 ft., 8%” long. Cut the stem piece out of 144” white oak to the shape shown in the accompanying sketch, and rab- bet accordingly. Notch the stem and splice; water-proof the notches with marine Mechanix Illustrated—June, 1938 show \ " above struc "9 “ons yerails Pt soar m Bette, stays ayn доп. р б ше Se dead e сө thy it 59 gs saline Ра often, round l&"x4" oak keelson with 1%4” No. 8 flat-head galvanized or brass screws. For best results make a full-sized paper pattern of the stem as well as of the three frames, transom and knees. Reproduce the half-breadth drawings to full size on paper. Frames are of %4”’x1%4” white oak. Fasten frames joints with 144” screws, leaving the formerly Modern Mechanix If Patty із to be glue and bolt the joint with taken from the Mer 38"x3" carriage bolts. To of the skeg to prevent the top of the keel fasten a if, fom sepe оп s 951 corners clear for notching out for chines. Тһе 57х14” white oak chines should fit flush. Brace the tops of the frames with temporary cross-pieces until the hull is planked. Square and line up the frames at their given stations, holding them with C-clamps until fastened with 214" flat-head screws to 95

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GO OVER BOAT WITH KNIFE TO DETERMINE ROT UNDER PAINT REMOVE SCARS IN MOLDING or ROTTEN PLACES IN THE STEM GRAVING PIECES [эти он \ INSIDE NY SHEET LEAD OR oF HULL NN COPPER PATCH AS ALAST RESORT = CAULKING SPLINE = Y FIXING A se. BAD SEAM AcE eat BUTT NEW PLANK BUTT port Block BLOCK RENEWING A PIECE OF PLANKING THE SE RING OVERHAUL BOAT COVERS SHOULD BE AIRED AND AA ERTER BEFORE STOWING EXAMINE FOR BHOKEN RAILS AND GUARDS ‘OPEN ALL WINDOWS, AND CABIN PORTS TO AIR OUT BOAT IF CANVAS |$ BAD OVERALL, RENEW. LAY NEW CANVAS IN MIXTURE OF WHITE > LEAD AND VARNISH OR LIQUID PC MARINE GLUE by Sam Rabl ITH the advent of the first housefly, or the song of the first robin, those of us who own a boat begin to get itchy fingers and soon saunter down to the boat yard “just to look her over.” A casual inspection will reveal enough to get started on but with the beginning of every season the inspection of any boat should not be “casual.” There is a set system of ex- amination that those who have owned a boat for a number of years have found to be the best and that in the long run will cut the time in- volved in the overhaul to a minimum. The first looking-over should be for the dis- covery of any defects. The old timer will get out his pocket knife and start poking into the wood to discover any “soft spots” hidden under the paint. Paint has a bad habit of hiding the effects of rot, and the seasoned boat owner knows just where to expect to find this menace if it is present. He will start poking the planking at the rabbet in the stem and follow its line from the top to the point where it joins the keel. Should the knife enter very easily at any point, he will start digging away the paint to discover the reason. Let us assume for example that a bad spot does exist. The rotten wood must be removed and graving pieces or “dutchmen” se- curely fitted so that the strength of the little ship is not impaired. If many rotten areas are found, the entire member should be replaced. Around the transom and along the keel are other likely places to look for rot. Exainination should be made also for damaged timbers due Mechanix Illustrated—June, 1938 REMOVE OLD. 7 PAINT WITH rp TORCH OR, SCRAPE WELL WITH. WIRE BRUSH REPAIRING BROKEN FRAME INE WELL ALONG KEEL ON THE BOAT aam possibly to that hard knock the boat got against the dock last year. Where a plank is badly scarred it would be well to renew the affected length. Any renewed plank should extend over three frames at least, and should be cut at the center of the space between the frames so that butt blocks may be fitted. Never splice in a new plank depending on the frames alone to cover the joint. This is some- times done in some cheaply constructed boats. Where frames have been broken, a length of new frame should be bent in alongside of the damaged ones so that it will cover at least three planks each side of the break. It should be securely fastened to both the broken frame and to the planking. Worn and scarred places on the rails and guards should be renewed by fitting an entire new piece, or by graving pieces. After all of the bad places in the hull have been re- paired, another thorough going over should be given the hull. In the meantime, if she had a winter cover, this should be given a thorough airing and drying before it is stowed away for the next lay-up. All of the win- dows or cabin ports should be propped open to air the inside of the boat. The interior around the bilge should be given a thorough scrubbing and cleaning and all old oil and grease removed from the interior below the motor. Grease and oil, besides appearing messy, create a fire hazard. After the bilges have been cleaned they may be painted with a good white lead paint, tinted gray. They may also be given a coat formerly Modern Mechanix RENEW TRANSOM PLANKS: WHERE DAMAGED-EXAM- V/4" MASONITE TOP SECTION THROUGH EDGE OF WEATHERPROOF COMPANION HATCH 1/8" SAW CUT. Vien x 174s BRASS ER. Scheweo ro suid Be of pine tar oil or creosote, both of which are somewhat smelly; or they may be given a coat of whitewash which will give the boat a sweet and clean odor and which will in a great measure protect it from dry rot. A strong solution of salt water in all the dark places will also be a good preservative from rot. The decks and cabin top should now be gone over and any bad places repaired. If the canvas is worn and cracked in many places the best thing to do is to renew it. All the moldings should be removed and the old canvas torn off. The new canvas is laid in a mixture of white lead and varnish or in liquid marine glue, made especially for this purpose. A good trick after laying canvas is to prime it with a thin coat of casein glue, which when set can be sanded to a very smooth surface. If the canvas is bad only in spots these can be repaired with neat squares of new canvas laid in paint or glue and their edges neatly tacked. Another good trick is to apply hard 101

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ODERN paints give to the amateur the ability to do a paint job possible in past years only by the skilled craftsman. Manu- facturers and experienced chemists have been working hand in hand to improve finishing materials so that anyone who can wield a paint brush at all can secure results that would astonish the old-time professional decorators. Much of the experience that was formerly required in manipulating the brush is now incorporated in the paint itself. This is par- ticularly true in the case of interior finishes such as enamels and varnishes. A great many of them are "self-leveling," which to the layman means that brush marks left by an awkward hand will automatically be leveled out of sight. Most of them will dry in four hours or so, which means that home routine need not be disrupted for days at a time as in the past. "What make of finish shall I use?" is not such an important question if it is asked regarding any of the well-known brands. The manufacturer, proud of his product, states on the label in simple language ex- actly what it is intended for and how it is to be used. You can rely on that informa- tion; it has been tested time after time. 108 le means of determining if the surface is dry is to some salt over a test piece of wood painted at the " salt brushes off without An example of the value ‘was not smooth when finish was yn was thoroughly sand A coat of enamel makes this table | MASTER FINISH wrx UNSKILLED HANDS ...... However, what about the cost? This good paint, good varnish or enamel, certainly ap- pears to be expensive. A small can of it may cost a dollar or more, while down the street you can get a similar-sized can for a fourth of the money, perhaps with a brush included. Experience is a good, but very costly teacher where paint is concerned. A cheap four-hour enamel may possibly be applied with the same amount of time required to brush on a reliable make. It may dry in four hours, or it may still be tacky a week later, painting is done, rub some vaseli to paint. Lefe—A mall articles, Use according to the luck that the manufacturer had with the compounding of that particular batch. Thè most disappointing part, how- ever, is its inferiority on the points most de- sirable in a good finish. These are (1) the ability to preserve and protect the surface to which it is applied. (2) Appearance; it should brighten the interior or exterior of a home. Thirdly, it should promote sanitation and be easy to keep clean; finally, a durable, lasting finish meeting the foregoing qualifica- tions should increase the value of the prop- erty. These requirements are obviously not met in a cheap material that quickly becomes dull, fades, may become tacky during humid weather and is liable to peel or crack after a few weeks or months. A good finish is one that dries hard, yet re- tains enough flexibility and elasticity so that it will not check when the surface to which it is applied expands and contracts due to temperature changes. To make a good com- parative test, coat a small strip of tin with the paint, varnish or enamel and allow it to dry well. It should not check or show the least sign of stress when the strip is bent around a t4-inch rod (such as the shank of a drill bit). Some good grades of enamel, 100

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ainted surface, some of the paint rubs off, immediate repainting is necessary. when put to this test, can even be crumpled and pounded and not the least sign of a crack will appear. Perhaps you are wondering just what color or shade would be most suit- able inside or out- side your home. Much depends on whether you wish to brighten up dark room, or to tone down the bright- ness. Good paint will do either. The “brightness” of a film of paint or enamel indicates the percentage of light that it will reflect. Some time ago an accurate check was made of the reflecting powers of the different colors of pigments used in good quality finishes, and it is quoted here to aid you in controlling the brightness range of a room you intend partially or entirely redecorating. The figures refer to the per- centage of light reflected: Good white paint. Pearl gray Light green Always start painting a house on the north side. Work around so that the sun remains ahead. 110 Dark chrome green .......11% Dark red ....10% Black .. % Good house paints consist es- sentially of a decorative and After the paint has been mixed with a Mechanix Illustrated—June, 1938 protective pigment suspended in a drying oil, which serves as a binder, with a thinner and other ingredients added to suit the type of work to be covered. Ordinarily the pigments consist of zinc oxide and The proper method of. apply the end of the brush ii the side of the applying it to the surface. ats paint from dripping ftom the brush. Work it out with and then Acren te main. Finoh а к, the grain. white lead, with the addition of a smaller quantity of tinting pigments. On the pro- portion of zinc and lead depends the suitability of a paint for a given purpose. A paint composed mostly of zinc will have great covering power, because of its greater ability to reflect light, but as it ages it unfortunately becomes brittle and cracks, and can easily be chipped from the un- protected wood with a finger- nail. On the other hand, a lead-type paint does not have a tendency to peel but it does, if the edge c with whiting-and-water formerly Modern Mechanix on becoming old, dry out into a chalky powder which readily rubs off. These two counter influences are taken advantage of in good quality paints by combining the lead and zine in scientifically correct propor- tions so that each counteracts the deficiency of the other. If the job is one of repainting you will save money by seeing that the old surface is absolutely clean, free of dirt and oil, and in [Continued on page 145] nt

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The completed set in use. The g posi antenna connection. All batteries are in the cabinet. HEN warm weather brings the urge to spend more time outdoors, some radio fans hesitate to build a portable receiver be- cause of the cost and trouble of construction. However, with this set, neither of these prob- lems is of large proportion. The cost of parts is sufficiently low so that almost any experi- menter will find that the pocketbook is not strained very much. When the junk box is brought out and examined for possible parts that can be used, usually the final cost will be reduced to a very few dollars. The actual construction is simple enough so that a single weekend of work will result in a completed set, ready for use wherever its owner wishes to take it. There is nothing tricky or odd about this receiver. It uses new tubes, but these are really “old tubes” with a different type of filament. These tubes are designed for bat- tery service and operate on 1.5 volts, thus permitting the use of a single “A” battery. The space thus conserved means that the set is much more compact and weighs consider- ably less than previous types of portables. The complete set, including everything but 116 THE “2-3” Горана) FRONT VIEW If the parts specified are used, the layout above should be followed. This view is of the front of the all-metal cabinet x " „CHASSIS L— * —— feALUMINUM А The positions tor the be drilled base to T BRACKETS FOR MOUNTING CONDENSERS The antenna condenser and the regeneration control condenser are mounted to the under side of the base. The bracket for C2 must be insulated from the chassis by means of fibre washers 101 and bottom. Metal washers should be used wi the bracket for C3 so that the chassis rests level. the earphones, is contained in a split metal case 6% inches high, 5 inches wide and 8% inches deep. This case is available at most radio supply stores. The builder may want to use some other type of construction, whereby the earphones can be housed in a small compartment; he will find many other sizes and types of cases available, or he may even go so far as to construct his own case of wood. If so, a metal panel is recommended Mechanix Illustrated—June, 1938 PORTABLE >: =~ Two tubes give three-tube per- formance in this easily con- structed porta- ble receiver. This phos position of the batteries in- side the set. The tuning to reduce “hand-capacity” effects. A piece of yy” aluminum 5"x412" is used for the sub- panel The midget condensers C2 and C3 are mounted underneath this aluminum plate. When they are fastened to the front of the case, they serve as a support for one end of the chassis. This makes a very convenient arrangement and it is necessary to employ only a long screw to support the rear of the base plate. The entire r.f. and audio portion is built on this small base. The antenna condenser C2 and the regener- ation condenser C3 are mounted on the under side of the base; so are the two tube sockets. The coil socket is mounted on top. This ar- rangement is absolutely necessary because the three sockets are so close together that they would interfere with each other if they were all mounted on the top of the chassis. Place small washers between the under- side of the chassis and the tops of the tube sockets, to prevent the rivets on the latter from “shorting” against the aluminum. Raise the coil socket about 34" above the chassis by small collars or piles of washers. [Continued on page 147] formerly Modern Mechanix

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What To Do About IRACTICALLY all cameras fitted with eye-level view finders suffer from a com- mon trouble known as “parallax.” Though not many camera owners recognize this word, they probably all have sworn plenty at it. Parallax is the displacement of the image as seen in the view finder in relation to the actual image as recorded on the film. You hold the camera to your eye, squint carefully at a person six or eight feet away and move the camera around until you think everything is showing. When you develop the roll, you discover to your dismay that part of the head. or legs is cut off, or the figure is off center completely. The error usually is greatest when close-ups are attempted at distances of three to five feet, which is about as close as most cameras will work without supple- mentary lenses. With miniature cameras parallax is a par- ticularly serious matter because the whole negative area is small enough even if all of it is used. If it is necessary to back away from the subject a good deal in order to be certain of getting a whole head, for instance, on the film, the resulting image is tiny and must be “blown up” considerably if a print of decent size is to be made. Beyond about fifteen feet the trouble practically disappears, as the ratio of displacement becomes very small. Most eye-level view finders are very accurate from infinity focus to ten, twelve or fifteen feet (depending entirely on the par- ticular camera), not quite as accurate at 120 and needs adjustment 100 close to the subject s slightly shorter distances, and quite inaccu- rate for intimate close-ups. A permanently fixed view finder is thus something of a com- promise. The makers of the more expensive minia- Mechanix Illustrated—June, 1938 RECTANGLE ON WALL 15 SAME PROPORTION AS NEGATIVE How to set up a camera and check the accuracy of its view finder. \ures frankly and honestly tell people what to expect in this regard. For camera fans who want to be absolutely certain of what they are “shooting,” they supply separate, attachable view finders having micrometer adjustments that eliminate parallax entirely. The system is as follows: First you look through the range finder and focus carefully on the subject. You observe the distance on the lens barrel or focusing mount, and then simply turn the parallax adjustment to read to this same figure. What you then see through the special view finder is exactly what you will find later on the negative. The only catch to this ideal arrangement is that the view finders are practically minia- ture cameras in themselves, with finely cor- rected optical elements, and cost about $25. Fortunately for the owners of more mod- estly priced cameras, it is a very simple mat- ter to determine the accuracy of any view finder at specific distances, and to make ap- proximate but adequate provision for the parallax. For your test “image,” select any light colored blank wall in any convenient room. In any stationery or chain store, buy a ten- cent roll of black “Scotch tape.” This is like the old-fashioned gummed mending tissue you used in school to fix up torn pages in books, but it requires no wetting and is in- stantly removed from any surface without leaving marks. Set up the camera ona tripod ur on the edge of a table. Adjust the focus- ing device so that the lens is out to the maxi- mum—the camera is thus set for taking pic- formerly Modern Mechanix tures at its shortest possible distance. No film is needed; open or remove the back of the camera and by means of rubber bands or strips of the Scotch tape hold a piece of tracing paper, tracing cloth, a fine silk hand- kerchief, or even ordinary tissue paper over the space normally occupied by the film. The idea is to mark off a rectangle on the wall with the black tape and to illuminate it with any strong light; a photoflood is fine. The rectangle should be in proportion to the negative size. For instance, if the film mea- sures 244x344 inches, the black “frame” can be about 4x6 feet. Put a dark cloth over the camera, open the lens wide and set the shut- ter at "T" (time) and move the camera around until you can clearly see the black box on the improvised focusing screen. Line it up carefully so that it covers the full nega- tive area; if necessary, adjust the tapes to form a smaller or larger outline that fills the negative at the shortest focusing distance. Now lock the tripod adjustment and move your eye to the view finder. The extent of the parallax with your particular camera will then be instantly evident. Repeat the experiment with the camera moved back from the wall at various dis- tances, and at each stage, draw a rough pencil sketch showing how much “off” the finder is. You will then know how much to tilt the camera, and in what direction, in order to be reasonably certain of having the negative cover the desired subject at the critical short distances. [Continued on page 141]

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TheMI Minineg The upright is a 3. d, I4x18^, b; [CON TM as threads led n" EC өп ыз ‘on opposite side locks it in any posit mipple joins а Ер 0 degree elbow. EN-DIAMETER projection prints made with the "Minineg" enlarger have that crisp, wire-sharpness that you usually expect only of contact prints. This trim-looking, compact little device is versatile. It will en- large miniature negatives up to 214x214 inches in size and, like the 9x12 cm. MM Enlarger described in the March, 1938 issue, will handle small sections of larger negatives. The Minineg follows somewhat the de- sign of the 9x12 cm. enlarger, and uses the same baseboard and upright; a single bushing for the 1-inch tee makes them interchange- able. The unusual compactness is due to the use of a 50-c.p. automobile headlamp bulb, which is extremely cool in operation but supplies an adequate volume of light. Two 38-inch plano-convex condensers, located almost in contact with the negative, assure unusual brilliance and crispness of detail. In constructing the Minineg, three types are available for selection. They differ only in appearance, design and operation being identical. The cheapest to make is the Regular; then there are the Deluxe and the Super-deluxe. Exclusive of condensers and projection lens, you can make the Regular for less than a dollar; the materials consist of %-inch black tempered Prestwood, with 122 Negatives from 35 mm. to 2% x 2% inches are handled with ease and can be “blown up” 10 diameters, ‘The enlarger open, ready to receive negative. Film is simply placed, emulsion side down, on the lower glass; hinged top, section of enlarger is then closed down, thus flattening the negative and keeping it in position. focusing and lamphouse tubes formed of sheet metal. Materials for the Deluxe, which is shown in the illustrations, consist of a black Bakelite radio panel and Bakelite tubing of the kind used for winding radio coils. Lastly, for the Super-deluxe, use Catalin. This can be obtained in sheets and tubes and the cost will not run over several dollars. This beau- tiful plastic material is obtainable in many colors and will not require outside finishing or lacquering if a non-actinic red mottle shade is chosen. A special cement is de- sirable, although Duco cellulose cement will hold the Catalin parts quite well. You can get a pair of 3-inch unmounted condensing lenses for $1.50, and a good pro- jection lens will cost from $5.00 up. Used and Mechanix Illustrated—June, 1938 new bargains are continually offered by the larger camera shops. А 3- or 34-inch anastigmat with aperture of f. 4.5 is standard for the Minineg. A shutter is not necessary. The Deluxe Minineg is shown in the illus- wations, and with the drawings you will not find that construction is at all difficult. You can get the Bakelite panel at any radio supply house, but to secure the correct sizes it was necessary to purchase the Bakelite tubing from two different concerns: 3-inch (inside diameter) tubing was secured from Allied Radio Corp. and 3-inch (outside diameter) tubing from Wholesale Radio Service Co., both in Chicago. The latter tubing makes a very smooth fit inside the former, and the 4 t * The lamp unit. Holes price is only 7c an inch, and less in 1-foot in the cover vide good ventila MANE FROM Alay EBRE oR rARDNOOD o PIT RECEPTACLE. E] M REFLECTOR (/ 38, CANDLEPOWER ALTO NEADLAMP BULB LIP TO ex GLASS SHEET f- CONDENSING ms HELD IN PLACE. BY SHEET OF GLASS COUNTERSUNK BOL! HEAD w CUT CORNERS OFF / Sra 24 ae on UPPER РАМ Ring tement ED to TUBE C'ATTACH TO PANEL WiTH Bouts з; чо v endent cass T ў TO PANEL pater A N WAE Rinu Covent х злое tuwe эта оков 1077 тн ---нмов” formerly Modern Mechanix о WITH CELLOPHANE Above — How the Minineg is focused. The left hand: turns Xhe focusing tube in or out, and the right pam й Ьу теапз of a binding post prr pm through both the fixed and sliding tubes. (See extreme p ot this carefully before starting construction and you will have no trouble. Note par- ticularly how the lower Bakelite panel mounts to the short piece of piping by means of a small flange, a short nipple Cees

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The photograph above shows clearly how the four-p. Although light passes through all the safelights at through the housing through only one section at a tim. DETAILS OF CLOSED END OF ROTOR END OE ROTOR Co mo, HOUSING. ANGLE STRIPS HE usual photographic darkroom ar- rangement of a single safelight lamp whose color screen must be slipped out and another one inserted every time a different type of paper or film is to be developed, can become a distinct nuisance, particularly when the changeover is attempted with wet hands. A rotary safelight lamp similar to that illustrated will eliminate such trouble by permitting screens to be changed merely by the turn of the knob. This four-position safelight unit consists of a rotor, carrying standard safelights, that re- volves inside a cylindrical housing having a rectangular opening in the side. A single lamp in a surface-mounting socket projects into the rotor, light from it passing through all the safelights at once, but emerging from the housing through only one at a time 126 m safelight operates. The corners of the rotor are padded with strips of felt to prevent the possibility of light leakage. COLLAR METHOD OF INSTALLING SHAFT MADE FROM 174" BOLT it passes our KNOB Corners of the rotor, which has a square cross section, are padded with felt strips, to prevent light leakage. Among the materials needed are the fol- lowing: One empty can of the type in which 5-pound quantities of sodium sulphite and sodium carbonate are sold by photo dealers, and measuring about 5% inches in diameter by 6% inches deep; a quantity of tinplate for the rotor (empty tin cans can be used); one 44-inch bolt 3 inches long; radio knob, to fit end of bolt after head has been removed; 4 strips of felt % inch wide and 5 inches long, preferably dark in color; one small angle bracket similar to those used for bracing corners and supporting shelves; one surface- mounting lamp socket and a 15-watt lamp, Mechanix Illustrated—]une, 1938 with necessary cord and plug; four rectangular safelights each measur- ing 3% by 4% inches; miscellaneous materials including black lacquer, solder, and casein-latex cement or similar adhesive for fastening felt to metal. Obtain the safelights and build the rotor to fit them, and at the same time fit it inside the can that is to become the housing. Wratten safe- lights are standard in this country, and can be purchased for about 40 cents each in the size specified. For complete flexibility with all photographic materials, the following are needed: Series OO, a clear yellow color, for use with contact-printing papers; Series OA, greenish yellow, for use DETAILS OF CONSTRUCTION AT OPEN END OF ROTOR LAYING OUT TINPLATE DISC TO FORM SEGMENTS. у SECTION THRU SEGMENT AT ROTOR CORNER КЕТЕТ JO KEEP SAFELIGHTS КЕТЕТ FALLING INWARD HOUSING з BUSHING окута, sooga | LAIT en И лез POSITION GF LAMP AND S mut m formerly Modern Mechanix with bromide enlarging paper and lantern slide plates; Series 2, red, for use with ortho- chromatic films and other materials sensitive to green but not red; Series 3, green, for use with panchromatic plates and films. For the extremely rapid panchromatic films that have been placed on the market recently, develop- ment in total darkness is best. Cut two discs of tinned sheet iron, such as that from the sides of an empty tin can, of a size that will permit them to be inserted, flat- wise, into the housing. In the center of one disc drill a- 14-inch hole, to receive the bolt to which the knob used to rotate the safe- lights will be attached. Mark out, on this same disc, a square whose sides are about 1/16-inch longer than the width of the safe- lights. Cut four pieces of tin to the same length, and about %-inch wide, and bend them lengthwise along their center lines, to make right-angle pieces. Solder these to the disc as shown, to form a square frame against the outside of which the ends of the safelights will rest. Cut four strips of tin measuring 1 by 4d inches, and bend them at right angles along their center lines, to form corner pieces of the rotor. Set the safelight glass temporarily in position outside the square frame, place the corner pieces outside the glass, and mark the places where the ends of these pieces meet the disc. Remove the glass and solder the corners in place, applying solder only along the outside, so it won't pile up near the glass. Mark the other disc with a square the same size as the first one, and then make a smaller [Continued on page 136] 127

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Photo li Short Cuts Developer Temperature w To Grind Glass For Photo Use Is Easily Regulated M you do your developing in the bathroom, ple matter 10 even temperature of solutions in « tray. Simply float the latter in tbe hand b. hot or cold water as the thermometer. Be careful water doesn't wy into the trav. Simple Wooden Stand Improves Brownie Satelight Clothespin Serves As A simple stand for a Brownie safe- Thermometer Handle light can be made from two pieces of wood, as shown at right. Make the mounting hole slightly smaller im diameter than the end of the socket which receives the lamp and then increase the diameter of the hole gradually with a file until the socket can be pushed through in a snug fit. Glue, smeared on rim, will aid in anchoring the socket. Checking the temperature of the fingers are wet. Clipping for enlargets, etc., by rubbing any a spring clothespin on the sheets with а circular motion (above). Make your own ground paste abrasive between Lamp Shade Clip Improves Reflector Tape On Lens Gives Stereoscopic Effect A flash-bulb that the usual manner ide to fire by ging it so, that the ters par just touches that ote good bulb Tighe. The will fire “Then the good опе goes off, its flash oc curring only about 1/100 second later. It is sometimes difficult to make good pictures of people indoors with photoflood lamps unless the latter are diffused in some manner. A lamp shade adapter with its center hole covered by a washer and bolt (above) makes an ideal "cap" to clip over the end of a bulb so that only light from the reflector shines on the subject. A strip of Scotch tape ted on the front of a fen, aa shown at left, will "fure" the back : apy pices ‘mal Latge prints can be vignetted smoothly and cleanly, fading out ject or to a perfect white at the edges, by a chemical method instead the usual dodging method. Expose the print without masks or dodging, dip into plain water and then dip the finger in developer. Solution end rub it over the part to be brought out (right). 99" erson foreground ‘stand. out it a stereoptican picture. Tape should cover about one-fourth of the lens. 128 Mechanix IIlustrated—June 1938 formerly Modern Mechanix 129

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