Modern Mechanix, August 1933

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| DEPRESSION SPURS age LOST GOLD TREASURE HUNTS

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2,000 i Miles Extra | Wear GUARANTEED Spreads on like butter on bread! Dries overnight. | Wears like part of the tire itself. Anyone can apply it. Mail Coupon for FREE sample of SPREAD-A-TREAD on tire fabric, special agent’s exclusive territory offer and FREE illustrated BOOK- LET. I will also show you how other men are making up to $6.00 in an hour with this amazing product that is bought eagerly by owners of mo- tor cars and trucks, Chaulfort made over $16 his first three hours, Flood made $168 his first week. Pegram made $182 in eleven days. Mail Coupon today. PLASTIC RUBBER COMPANY OF AMERICA Cincinnati, Ohio Dept. H-235, E. Court St. a S a 4 m & © H 4 E © S 2 i = o a = 5 SPREAD-A-TREAD— The new sensational discov- ery. Covers old worn tires with a new, tough, flexible, long wearing tread for as low as 75c. Repairs a worn spot fora few pennies, At least 2,000 additional miles GUARANTEED. Many Spread-A-Tread applications wear 6,000 to012,000 miles, An amazing opportunity for agents to make up to $6.00 in an hour. Rich territories now being allotted—act today to reserve yours. Mail Coupon for FREE Sample Made $1,734 in Two Weeks Harry Gillig, of Kansas, forms his own sales company for distributing SPREAD-A- TREAD. In2weeks he sold 7 gross giv- ing him a profit of $1,734. Hundreds of others making big money in spite of “Hard Times.” You have the same op- portunity. SPREADS on witha knife—Dries over night Anyone can apply Spread-A-Tread. An old knife is all you need. No other tools necessary, It spreads on like spreading butter on bread. Dries over night—tough, flexible and long- wearing. CAN’T come off. Ends Costly Tire Repairs — Helps Prevent Accidents SPREAD-A-TREAD ends costly vulcanizing or re-treading. Saves buying new tires. Helps prevent skidding, punctures, blowouts and accidents due to poor -“tires:--Seals holes -and:cracks. “Rebuilds tire from outside without taking off car or even letting out the air. Reinforces weak spots. Vulcanizes itself to the old tire so that it cannot crack or peel off. Saves delays and repairs. Protects fabric against water, grit, rot and wear. Makes driv- ing safer. Test SPREAD-A-TREAD at my risk. Per oad kr PLASTIC RUBBER CO. OF AMERICA, Dept. H-235, E. Court St., Cincinnati, Ohio. I am interested in SPREAD-A-TREAD. You may send me the Free Sample of SPREAD-A-TREAD on tire fabric and Free illustrated Booklet. Also tell me how other men are making up to $6.00 in an hour.

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will Train You at Home “Made $6,000 in 2 Years’! “Soon after the depression Started, I found myself without a job, but I was well protected withN. R. 1. training. I swung right to full-time Radio servicing and I have made over $6,000 in a little over two years.” —WM. SPARTI- VENT, Sparty Radio Ser- vice, 93 Broadway, New- ark, N. J. v $120 a Month in Spare Time “I’m servicing from 3 to § sets daily in Spare time, and average $12) 2 month from my Radio work. still hold my regular day Rep I ous my success to A. E. FARMER, 1012 Denison St., Muskogee, Okla, Increased Salary $1,000 a Year “Now I have under con- struction an up-to-date transmitter, for Station WAMC, of which I am engineer, My salary has increased $1,000 per year since entering Radio, due to your “splendid training.” JULIUS C. VESSELS, Radio Station WAMO, Anniston, Ala, in your spare time Get away from disagreeable jobs with no future. From skinny, little pay envelopes. From skimping along, Just barely getting by, but not gelting ahead. DON’T PUT UP WITH THEM ANY LONGER. Get into a field with a future. Act today to put yourself ahead. Mail the coupon for my free 64-page book that tells how you can train at home in your spare time to be a Radio Expert; about my course that doubles and triples the pay of many who take it. MAIL THAT COUPON NOW and take the first step toward a real future. Real Opportunities Ahead in Radio for Trained Men It’s hard to find a field with more opportunity awaiting the trained man. Why in 1931—right in the middle of the depression—the Radio Industry sold $300,000,000 worth of sets and parts! Manufacturers alone employed over 100,000 people! 300,000 people worked in the industry. In 1831 broadeasting revenue jumped 20 per cent over 1930, and 1932 is even better. It’s a gigantic business, even in the worst business years! And look what’s ahead! Mil- lions of sets becoming obsolete annually. 16,000,000 scts in operation that need servicing from time to time! Over 600 great broadcasting stations furnishing entertainment and news to 100,000,000 people. ‘hese figures are so big that they ure hard to grasp! Yet, they are all true! Here is a new industry, just 12 years old, that has grown into a commercial giant, No wonder great business leaders pre- dict a brilliant future for this great and growing business. Get Into This Field With a Future There’s opportunity for you in Radio. Its future is certain. Television, short wave, police Radio, automobile Radio. talking movies, public address systems, aircraft Radio—in every branch, developments and improvements are taking place. Here is a real future for thousands and thousands of men who really know Radio. Get the training that opens the road to responsibility, good pay and success! Send me the coupon now, and get full particulars on how easy and interesting I make Yearning at home. Read the letters from grad- uates who are today earning real money in thls faselnating industry. Turn Your Spare Time Into Money| My book also tells how many of my students made $5, $10 and $15 a week extra in spare lime, soon after they enrolled. I give you plans and ideas that have made good spare-time money—$200 to $1,000 a year—for hundreds of fellows. My course is famous as “the one that pays for itself.” Money Back If Not Satisfied I am sọ sure that N. R. I. can train you satisfactorily that I will agree in writing to refund every penny of your tuition if you are not satisfied with my Lessons and Instruction Service upon completion. You'll get a copy of this Agreement with my book. 64-Page Book of Information Free Get your copy today. It’s free to all residents of the United States and Canada over 15 years old. It Lells you about Radio’s spare-time and full-time job opportu- nities; it tells you all abaut my course; what olhers who have taken it are doing and making. Find out what Radlo offers YOU without the slightest obligation. MAIL THE COUPON NOW. J. E. SMITH, President National Radio Institute, Dept. 3HH Washington, D. C. YA EATA i Thank You for Mentioning Modern Mechanix and Inventions for August When Writing to Advertisers SPECIAL Radio Equipment f = a for Broad Practical Experience Given Without Extra Charge My course is not all theory. I'll show you how to use my special Radio equipment for conducting experi- ments and building circults which illustrate important principles used in such well-known I have doubled sets as Westinghouse, General Elec- trice, Philco, R. jestic and others. You work out with your own hands many of the things you read in our lesson books. C. A., Victor, Ma- This 50-50 method of train- ing makes learning at home easy, interesting, fascinat- ing, intensely practical, and tripled the. EILL QUT AND THIS COUPO salaries of many Find out about this tested way MAI J. E. SMITH, President National Radio Institute, Dept. 3HH Washington, D. C. Without obllgating me, send free book about spare-time and full-time Radilo opportunities and how I can train for them at home. particularly interested in the job checked. () Service Manager for Retail Stores, ( ) Set Servicing Expert. ( ) BroadenstEngineer { ) Operator in Broadcast Station, { ) Aircraft Radio Operator. ( ) Operator of Air- way Beacons. ( ) Servico Man on Sound Picture Apparatus. NAMH. s.es. uernnerereeneees sorting, erewsia® ADDRESS CITY (Please print plainly) I am ( ) Operator of Sound Picture Apparatus. ( } Ship Operator. ( ) Service Man on Public Address Systems. ( ) Installation Engi- neer on Public Address Systems. ( ) Sales Manager for Retail Stores. ( ) Auto Radio Installa- tlon and ServiceMan_ ( ) Television Broadcast, Operator,

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August 1933 Donald G. Cooley EDITOR aa ae VOLUME X PRICE 15 CENTS NUMBER 4 (20 CENTS IN CANADA) SPECIAL FEATURES t SHORTER FEATURES Air Achievements of the Month- - - 30 Arane Ooa Scenery -S7 37 Streamline Train Heralds New Era 5 Tekin Dep oee to Help i for. Railroads - " ` . g aoe Braving the Inferno of a By Roy Dean Volcano = 5 = + 53 é š Electric Violin Has N Things You Mustn’t Miss at Chicago’s Sounding Board S oss World Fair S . 5 5 z - 38 Economic Science Explains 3 Help Bobb Meaning of Inflation - 57 Trick Camera Shots Help Bobby Jones E lx - S54 Teach Golf - - - - . - 42 By Nic Sprank Depression Spurs Lost Gold Treasure aE a eer Oe Hunt Je n 5 È S 5 - 44 Single Control ’Gyro Elimi- By Bennett Lincoln nates Wings- - - - 71 ‘ {n Mechanical Aids for the Secrets of Cures by Ancient Medicine Men 52 Housewife - - - - 78 By Earle R. Buell Coaches Are Waiting Rooms on Non-stop Railway- - 80 Getting More Light on the Moon - - 60 Radio Divining Rod Finds By Calvin Frazer Historic Treasure - - 81 Fortunes Waiting for Inven- Finding Cleopatra’s Fabled Emeralds - 62 COIR Ge tai ee By Count Byron de Prorok Better Investment Than Ga ee = 8 2 = 122 - - - 123 Science Finds Amazing New Uses for Dug SE REAN Microphones - -— - ‘ š - 68 BIG HOW-TO-BUILD ARTICLES | 1000 Ways to Make a Living . - « 74 A “Desert Town” Canoe - 93 Ni : id M By A. A. Murdoch Mechanics Ai Art to Create Mural Trailee Carries Porrable Masterpieces - = - - - - $2 | Knock-down Cabin to By Don Black |, ARBRE Pst See Se ps 3 (Continued on page 6) | Published monthly by Modern Mechanix Publishing Co., at 529 7th Street So., Minneapolis, Minn. MODERN MECHANIX AND INVENTIONS entered as second class matter September 20th, 1928, at the Post Office, Minneapolis, Minn., under the act of March 8rd, 1879. Douglas Lurton, Managing Editor. Copyright 1933. Advertising Offices: Chicago office, 85 East Wacker Drive (Phone State 2955); New York office, 52 Vanderbilt Avenue, (Phone Murray Hill 2-1555). All manuscripts should be addressed to our editorial office at 529 So. 7th Street, Minneapolis, Minn. Manuscripts will not be returned unless accompanied by return postage. Advertising forms close on the 20th of the third preceding month. Price 15 cents a copy; $1.50 a year in the United States and possessions, In Canada, 20c per copy; per year $2.25. Other Postal Unions, $2.00 per year. Printed in U. 8. A. ` A a) 4

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THAT MADE A MA OUT SF LISTEN HERE, MAC, 1 FACE- ONLY YOU'RE SO SKINNY YOU MIGHT DRY UP AND BLOW AWAY. SEE YOU LATER, GIRLIE... HEY! QUIT KICKING THAT SAND IN ^ our Face! / THE BIG BULLY! OH DON'T LET No, 'M AFRAID) Vparn it! PM SICK AND TIRED OF IT WAS NICE GRACE. CAN I -ER- COME ‘AROUND SOME EVENING ? an I I'LL GET EVEN IT BOTHER YOU, NOT.IM PRETTY ||. BEING A SCARECROW! CHARLES some pay OR LITTLE Boy! ||) TO MEET You, BUSY. GOOD-DAY!] | ATLAS SAYS HE CAN GIVE ME A REAL B0DY. ALL RIGHT! I'LL GAMBLE. A STAMP AND GETS His FREE scox! Ñ WHAM! - NOW ITS YouR TURN TO ORY UP AND BLOW Away! IT DIDN'T TAKE ATLAS LONG TO DO THIS FoR me! LOOK AT THOSE MUSCLES BULGE OuT NOW! THERE'S THAT BIG STIFF AGAIN, SHOWING OFF IN FRONT OF GRACE AND THE, CROWD. a GS, WELL IT'S } MY turn é n. à this Time! AKS A x ARE a l Z n REAL MAN | The 97-ib. Weakling Who Became ‘“‘The World’s Most Perfectly Developed Man” TE used to think there wasn’t much hope for me. I weighed only 97 pounds. I was a sickly Scare-crow. Then I discovered Dynaniic-Tension. It gave me the body that twice won the title ‘‘The World’s Most Perfectly Developed Man.’’ Now I make - 3 a ROG ee offer. At my own risk Vl give you -a e m m m a in just 7 days that my same method can make you | over into a NEW MAN of giant power and energy. Boe eee ATLAS ’ -r (ll PROVE You Can Have a Body Like Mine! 133 E. 23rd St., New York City No “‘ifs’*—‘ands’’—or ‘‘maybes.”” Just tell me where 7 z 7 you want handsome, steel-like muscles. Are you fat I want the proof that P pyeten ol and flabby? Or skinny and gawky? Are you short- Dynamic-Tension will ma rs bay and winded, pepless? Do you hold back and let others of me—give me a healthy, hus sy DOSY, fre walk off with the prettiest girls, the best jobs? » bis muscle development. | Send me your bree Give me just 7 days! V'll PROVE that Dy- book, “Everlasting Health and Strength. namic-Tension—without any pills, or unnatu- ral dieting or welghts and pulleys that may strain your heart or other vital organs—can maka 3 j Sou a healthy, a pov rTu H ENTANS m usta few minutes a day! Mail coupon or my Ìl- CHARLES ATLAS lustrated book, ‘Everlasting Health and Strength.” Tells all Holder of the title: “The about Dynamic-Tension. Shows actual photos. It’s a valuable World’s Most Perfectly book! Andit’sFREE. Send foryourcopy today, Address me Developed Man” personally: Charles Atlas, Dept. 6-8, 133 E. 234 St., N. Y. City. NAMO -rasreserenenereenes ertene pererees (Please print or write plainiy) Address 1... cece eee e eee e eee e een eens E ana an KRA State.......... © 1933 C. A. Ltd. -m e A «chi Thank You for Mentioning Modern Mechanix and Inventions for August When Writing to Advertisers 5

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TABLE OF CONTENTS — Continued From Page 4 BIG HOW-TO-BUILD ARTICLES Complete Vacation Receiver in a Cigar Box Plans for a Dirt Track Racer = e By Ray F. Kuns How to Build a Simple Chemical Refrigerator 112 By John Cartright Building Telescope for “Star Gazing”, Part II 116 By E. Willard Pennington Build “Old Man River’—a Scow Houseboat By Jarvis L. Stumpf NEW MECHANICAL INVENTIONS Echo Sounding Device Locates Schools of Fish 36 - 100 - 104 - 120 Sleeve Repairs Heating Coil ~ = 2 = 36 Book Turns Own Pages, Speaks - - - 37 Hump Makes New Pins Pull-proof - - - 37 Coils in Soles Give Springy Step “+ +=, 40 Pipe Grid Keeps Tobacco Dry - - - 41 Key Ring Hooks to Clothing - - . 41 Motorized Eyebrow Tweezer Werks Rapidly, Painlessly - - 48 Wheel Lays Perfect Paint Stripe - 2 + 48 Foot-powered Outboard for Fishing - - - 50 Cap on Paste Tube Can’t Be Lost - - - 55 Self-shifter on Popular Car Eliminates Gear Shift Lever - - - 5 + 56 New Spark Plug Is Self- Cleaning: - = + 56 Polo Has Mechanical Mounts - - - 58 25 H. P. Outboard Speeds Midger Racing Car 100 m.p.h. - - 58 800,000-volt X-ray Fights Cancer. - = = 66 Home Coolers for Summer Comfort - - 67 Piccard Gondola May Set Stratosphere Record 72 Ultra-vi»let Health Lamp for the Home - - 78 Heat Control Plug forIron - - - - = 78 Coin in Slot Lock - - + + - + - 78 De-mothing Blower- - - - + + + 79 All-room Temperature Indicator - + + 79 Grapefruit Conquered at Lass - - - - 80 Converts Sew Machirie to Jig Saw - «+ = 80 Pencil Carries Own Tablet - - - + - 81 INTERESTING SCIENTIFIC ITEMS Skunk Odor Saves Miners’ Lives - - 40 Police Plane Takes Off Prom Car to Hünt Down Crooks - 40 Balloons Fly in Tandem t to Check Stratosphere Speed - - - 41 Model Masterpiece Built Frem Odd Parts - Proper Hand Position for Driving - >» - Rash Turns Negro Man White - . -+- - 58 Young Champs Stage Own Race- + + - Legs Armorplated to Protect Against Rattlesnakes - =- - - = - - 66 Re-silvering a Telescope Mirror - - + + 72 U. S. Had World’s Hottest Spot - - + - 80 FOR THE HOME CRAFTSMAN Silhouettes Decorate Lamp Shade - - - 36 Easiest Way to Fix a Puncture - =- - - 5Ẹ Keeping Birds From Flower Beds - 2 + 5E Restoring Typewriter Tampon - - - - 72 Unusual Ideas in Rustic Woodcraft - - + 73 Motor Wheel Makes Shop Power Plant - - 95 Anti-slump for Music Sheets - = = + 9 How to Convert Band Saw Into Polishing Machine - - 96 Developing Eslatgements Too Big for the Tray 96 Sports Model Side Car Is Easy to Build - - 97 Set Up Portable Swim Pool in the Back Yard 103 Two Simple Puzzles That Are Stickers - + 109 Something New in Diving Thrills - - +110 Tennis Court Marker Makes Straight, Clean-cut Lines - - - -= lll Continuous Fuse for Experiments - + lll Ride This Wooden Seahorse 5 m.p.h. - -114 Improve Your Health in Lawn Solarium - - 115 A Fifteen-dollar Greenhouse - -= = = 118 Planning a Sail Rig for Your Boat - - ~- 119 FOR RADIO FANS Key Click Eliminates Transmitter Thumping - 102 Shock-proof Handle for Plugs - - - - 102 Handy Improvised Tube Socket - - - - 102 The shop mail box will be found this month oa Page 10 HANDIKINKS Novel Sunlight Photography on Wood - - 86 Interesting Barometer Made From Scraps - 8&6 Making Artistic Portraits Is Great Fun - - 87 Novel Serving Trays for Bridge Guests - - 87 Knob on Dash Adjusts Charging Rate - - 88 Suction Pump Tests for Loose Bearings - - 88 Pin Keeps Hammer Handle Tight on Head - 89 Plane Gauge for Squaring Up Boards - - 89 An Optical Toy forthe Kiddies - - - + 90 An Effective Scarecrow for the Gardens - - 94 Countershaft Bearings From Pipe Fittings - 91 1000 Ways to Make a Living—Profits in synthetic toadstools; Servicing Automobiles; Sharpening Ra zor Blades; Income for Radio Fans; Money il Bleaching Water; Bantam Lunch Boxes; Polishi: § Auto Head Lights; Keeping Up Vacant Hous: ¢ Money-making Ad Stunt; Gather Up Pine Cones Glass Signs for Offices; Installing Glass Windows: Circular Delivery Route; Classified Mailing List; Indexed Recipe Books; Advertising for Theatres: Salvaging Used Containers; Start a “Worm Farm” Whitewashing Basements; Watch for Motorbike Smashups; Basement Battery Shop; Help on Mov- ing Day; Money in Rough Rock; Profits in a Ceme- tery; Income for Painters; Sell Home Photographs. EDITED BY EXPERTS Listed here are the members of the Modern Mechanix Board of Editors, all qualifed by national repute to serve as authorities. They will gladly answer questions from readers if stamped envelope is sent. Address them in Raymond F. Yates Patent Expert Douglas Rolfe Plane Talk Editor Pitot Gene Shank Famous Aviator, Holder of Light Plane Endurance Flight Record Weston Farmer Consulting Editor J. Russell Dye Associate Editon care of this magazine, 529 S. 7th St., Minneapolis, Minn. A. Neely Hall Author of ‘ “The Boy Crafts- Alfred Albelli a Now York Editor S. S. Rabil L. B. i Ray F. Kuns Seaplane Designer and Nationally Known Radio Principal, Yoinctnnati Auto- Naval Architect Expert motive Trade School Roger Fawcett Associate Editor

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elias ok ON A Naa. | S GASOLINE — WINS ECONOMY CONTEST Company. driving. ups—and quick stops, How Whirlwinds Save Gasoline The principle of the Whirlwind is to slightly compress the partly vaporized gasoline as it passes thru the raised venturi, Extra air enters from four air inlets at such a tangent as to pick up the unvaporized gasoline parti- eles, whirling them into action. The turbulence created breaks them into a vaporized gas, giv- ing better, smoother power, quicker starting, cutting gaso- line waste and carbon formation. Car owners all over the world are amazed at the results of their tests. “I have more speed, power, and in- creased mileage,” writes Henry Bomberger. “Hills I used to take in second I now make in high.” Anton Wetsch: “I wouldn’t take the Whirlwind off my car for any money. I am certainly - conyinced.” W. B. Fountain: ‘My mileage has increased greatly. My car has plenty of pick-up and starts like a whip.” SALESMEN AND DISTRIBUTORS WANTED To Make Up To $100 A Week and More Whirlwind men are making big profits taking care of Jocal business for this fast selling device that car own- ers cannot afford to be without. Good territory is still open. Free sample offer to workers. Full particulars sent on request. Just check the coupon, WHIRLWIND MFG. COMPANY Dept. 968-A Station C Milwaukee, Wis. 49 MILES Takes 2nd Place Winning Cars Equipped With WHIRLWIND GAS SAVERS Automobile owners who have been worrying about gasoline expense will be interested in an amazing test recently conducted by a Texas Motor Car any. Twenty-three cars were entered in a mileage economy test, the winning car running 51 miles on a gallon of gas, the second car 49 miles on a gallon. When official test records were published it was found the two winning cars were both equipped with Whirlwind gas savers. “Peak”? Contest Mileages The amazing results obtained in this mileage contest are naturally great- er than those obtained in ordinary Careful throttling, economical speeds—no traffic hold- no waste of power thru help to bring about ` these “peak” mileages, A Test On Your Car More power, faster pick-up, less carbon, quicker starting, and in- ereased mileage is what users say in telling of their experience with the Whirlwind. Every motorist owes it to himself to test the Whirl- wind to prove the results on his own car. FITS ALL CARS In just a few minutes the Whirl- wind can be installed on any meke of car, truck or tractor. It’s actu- ally less work than changing your oil or putting water in the battery. No drilling, tapping or changes of any kind necessary, It is guaran- teed to work perfectly on any make of car, truck or tractor, large or small, new model or old model. The more you drive the more you save. GUARANTEE No matter what kind of a car you hava or how big a gas eater It is the Whirlwind will save you money. Whilə we do not claim to produce 49 to 51 miles om ordinary driving, we do guarantee that the Whirlwind will save Its cost within 30 days or the trial will cost you nothing. We invite you to test it at our tisk. You are to be the sole Judge, FREE OFFER COUPON most Mrs. C. P. Blalock, contest winner a WHIRLWIND MANUFACTURING CO. Dept. 968-A, Station C, Milwaukee, Wis. Gentlemen: You may send me full particulars of your Whirlwind Carbureting device and tell me how I can get one Free. This does not obligate me in @ any way whatever. a - a ADDRESS stcsscccsniaard teaseanendeece Aeon ees : CITY oosisuericissiroreres sanan O TATE [O Check here if you are interested in full or part time salesman position. i Ipo. Thank You for Mentioning Modern Mechanix and Inventions for August When Writing to Advertisers 7

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| At Last= Garbo’s True ‘Life Story! Garbo’s ex-secretary lifts the veil of mystery and tells the true story of her life and career in pictures for the first time. Scores of hither- to unpublished facts and anecdotes and an insight in- to Garbo’s personality that you’ve never had before. You'll thrill and be delighted with tions! its amazing revela- Depression Spurs Treasure Hunt (Continued from page 47) shire. IL was sure I would be dead in a matter of moments. I was down under pressure of 400 pounds to the square inch. My breathing became more difficult.” In these waters of black menace, more horrible than any. of Poe’s tombs of living death, Courtney struggled for a half hour that seemed a month— tugging frantically at his signal cable, getting no response, losing blood from the frightful gash in his side and suffering excruciating pain from his shattered wrist. Minutes dragged past, each heavy with the conviction that the next moment would bring a rush of. death-dealing waters—and then the cables stirred. Forces of the current were bested at last, and Courtney was lifted to the surface, “Several hours later I happened to be looking in a mirror, for curiosity rather than for vanity. To my amazement I discovered that my hair had | Pardon Our | Operations— Get Your Copy TODAY! If your news dealer is sold out, send 10c, stamps or coin, to SCREEN PLAY, 529 South 7th St., Minneapolis, Minn., and a copy of the August issue will be mailed to your address. What do the stars think of when they’re on the operat- ing table and death seems at hand? Look for the absorb- ing story of the stars’ thrill- ing hospital experiences. Also: Ruby Keeler’s Sensa- tional Rise to Stardom; Charlie Farrell Tells the Whole Truth; The Love Let- ters of Jimmy Durante to Garbo; Mae West’s Broad- way Adventures and other fascinating features of the stars and Hollywood life too numerous to mention. Read them in— SK S ESSN turned almost white from the frightful experience I had in Neptune’s chamber. But I’m happy to say it. was just another set of mixed tumblers locking a vault out of which I was very lucky to escape. When I returned to the tranquil routine | of my West 125th St. shop during the latter part | |. of last May, I had 12 stitches in my side and my wrist. was encased in a plaster cast.” After that catastrophe, work of salvaging the Hampshire was postponed until late summer. It is rumored that the British government is nego- tiating to buy up the rights of Mr. X and his co-workers. Interest in salvaging operations is world wide. Efforts are being made to obtain the $5,000,000 which went down with the English frigate Lutine which sank off the mouth of the Zuyder Zee in 1799. Still others are trying to get back $10,000,000 in Spanish gold which sank with the frigate De Braak off the Delaware Capes in 1798. There are several other similar expeditions. Some of them are working secretly. Only recently a specially-equipped submarine steamed out of New York harbor on a salvage mission. No one knows the mysterious craft’s personnel, no ope knows her destination. No one knows with any authority exactly how many treasure ships lie in unmarked graves. Only recently Allan C. Robertson, searching through dingy old records, came across accounts of the sinking of the De Braak in colonial days, carry- ing a reputed $40,000,000 in gold—under only 70 feet of water. One of the illustrations with this article shows the recovery methods he is pur- suing in seeking this fabulous treasure. One of the most remarkable of the new treasure salvaging: devices is the diving suit shown on page 46, developed by J. S. Peress, of Byfleet, England. It is extraordinarily strong, enabling descents to 1200 feet, a previously unheard of depth. The diver carries his own air supply on his back, eliminating pumping lines. Despite its size, the suit is very flexible under water, the joints moving in an oil cushion. Pincer-like claws at the end of each arm function like fingers. The depths at which the new suit can operate brings such treasure ships as the Lusitania, lying in 700 ft. water, within range of diving operations tree ‘Thank You for Mentioning Modern Mechanix and Inventions for August When Writing to Advertisers

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So you’re going BACK ‘TO WORKe THATs FINE! And more good news is that im- proved business conditions are sending thou- sands of other men back to work. But don’t let your enthusiasm dim the facts. Business today, and from now on, has a new standard of service. It is a standard of efficiency —of training—and to ignore it is inviting another long stretch of unemployment. For your own sake, man, for your family’s sake, do not flirt with this disaster! Especially foolish when you can acquire so easily the training you must have ... when you can make yourself more valuable on your job by devoting a small portion of your spare time to study. In years past millions of men have come to International Correspondence Schools for this training. Today, with its unusual conditions, is bringing many of these men back for additional training, to meet and solve the problems of a new day—and many thousands who have decided to face the facts and assure their own futures. Will you face the facts? Do you want to assure your future? Then this coupon is a challenge to you! Why not mark and mail it—right now? If de- sired, you can arrange to complete the course of your choice through easy monthly payments. INTERNATIONAL: .CORRESPONDENCE SCHOOLS “The Universal University” BOX 2320-T, 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 D Architect O Architectural Draftsman CG Building Estimating O Wood Millworking O Contractor and Builder O Structural Drafisman 0 Structural Engineer O Electric Wiring D Electrical Engineer OC Electric Lighting D Welding, Electric and Gas O Reading Shop Blueprints O Business Manegement U Office Management O Industrial Management O Personnel Management O Trafic Management O Accountancy Name..... D Telegraph Engineer D Telephone Work D Mechanical Engineer O Mechanical Draftsman D Machinist D Toolmaker 0 Patternmaker C Pipefitter U Tinsmith D Bridge Engineer D Bridge and Building Foreman O Gas Engines OC Diesel Engines D Aviation Engines O Automobile Mechanic O Plumbing O Steam Fitting O Heating O Ventilation O Sheet Metal Worker Steam Engineer D Steam Electric Engineer O Civil Engineer O Surveying and Mapping O Refrigeration OR. R. Locomotives OR. R. Section Foreman OR. R. Bridge and Building Foreman BUSINESS TRAINING COURSES O Cost Accountant O C. P. Accountant D Bookkeeping O Secretarial Work C Spanish O French O Salesmanship O Advertising O Business Correspondence DD Lettering Show Cards O Signs D Stenography and Typing O Complete Commercial O Civil Service i UO Mail Carrier seer Address D Air Brakes O Train Operation O Highway Engineeriog O Chemistry O Pharmacy D Coal Mining Engineer D Navigation D Boilermaker O Textile Overseer or Supt. O Cotton Manufacturing D Woolen Manufacturing O Agriculture O Fruit Growing O Poultry Farming O Radio D Marine Engineer O Railway Mail Clerk O Grade School Subjecta O High School Subjects D College Preparatory C Illustrating O Cartooning O Lumber Dealer Uf vou reside in Canada, send this toupon to the International Correspondcnce Schools Canadian, Limited, Montreal, Canada I} a Thank You for Mentioning Modern Mechanix and Inventions for August When Writing to Advertisers

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“Just to use up an old cut,” explains Andy, “I’m answering a host of nuts whe wrote in wanting another lock-see at the seaplane job (non-flying) that ran Jast month. Here she is before covering, Shot was taken by Sam Wing.” Andy’s Shop Mail Box Andy takes himself a well-earned vacation in California, and prior to shoving off he leaves a load of threats to keep things going smoothly for his pet pig while he’s away. HE time has come, as the Walrus said, to look at many things. Tve been sitting on my haunches in and about the old Robbinsdale hangar now for a couple of years without ary being able to get away, and now what with summer coming, Pm loading up the old DH Moth with an extra quart of oil, sewing a five dollar bill to the underside of the cockpit cushion to protect me from myself in my wild-sailor spending sprees, and one of these days you guys in California will see me hopping over. the hedges to Louse Angles, where theys a lot of stuff I’ve been missing and need This Comedy Ford at last has been claimed by her owner and builder, an anonymous nut who lives in Soquel, Calif. 10 to get caught up on. TIl be there when you read this, And before I go I’m laying down the law to keep things intact until I get-back. More of that later. * * * I’ve always made it a rule not to run an anonymous letter. And the only reason this is anonymous is because I lost the envelope con- taining the gent’s name. But the text is worth digesting: Soquel, California, P. O. Box 283. Dear Andy and Gang: Boy, I’ve got to hand it to you and Double M for publishing the sweetest mag I ever read. I have enjoyed reading letters in your mail box next to what you have to say for yourself, I am sending you a picture of the Comedy Ford which I built from details which ap- peared in the February issue of the good old M.M. Wow, talk about a riot, you would think a circus was in town the way people run out of doors and alleyways, people on the side- walks all come to a stop to watch old Liz caper around and do her stuff. I nearly got a ticket for blocking traffic. Everybody stopped to watch old Liz perform her new- born self, Modern Mechanix ant

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Built by a pal of Leslie Long’s, this Church Mid Wing bas given a rousing account of herself with that highly succese« ful Long-designed motor, the Harlequin. I have two more short jack shafts for Fords, so if any of the gang would like one, to build up their Comedy Ford, I will sell them reas- onable. Always yours for old M.M. and M. P. mags. THE CALIFORNIA GREASE NUT. P.S. Since reading the good old M.M. I can just about make or repair anything you want except a broken heart. +o k Here’s a chap-who has taken a Modern Me- chanix and Inventions design and done an in- telligent job of following the plans. Witness the views of Mr. Warren La Barre’s “Whizzer,” de- signed by Westy Farmer and included in the cargo of “How: to- Build 20 Boats.” Mr. La Barre’s letter: Dear Andy: This is the first. time I have written to you although I get the M.M. every month, and I think it is a swell mag. I am sending you a couple of snapshots of the boat I built from your plans of the “Whizzer” but I changed some of the things a little. The. hull is made of 1⁄4” plywood which I soaked in linseed oil, painted with three coats of paint and two of varnish. It does not leak a drop. It weighs about 175 {bs. with motor and draws about 4 in. of water. The motor is a HD-74 and is mounted on part of the frame. It is braced up with 1” water pipe and %” steel cable crossed, with turnbuckles to steady it. The prop is made of three pieces of ma- hogany glued together, It is four feet long Les has more to say anent the motor and ship elsewhere in the column. and has a four-foot pitch. It will go about 25 to 30 m.p.h., depending on the wind and current. Everything else is made from the “Whizzer” plans. Always a M.M. reader, Warren La Barre, 903 N. E. Portland Blvd. Portland, Oregon. x ok & Later Pm running a letter from Harry Lowe Brownback, a swell gent, by the way, who has something to say about the matter of patents on these hydro-gliders, ` * * $ This letter might be prefaced with a thousand comments. I’ve written all of them and scrapped all of them, so I’m running it as is, wiping a salt tear away from my face for you-know-what: Dear Andy: Looks as though you were leaning slightly away from amateur light planes. I would be sorry to see you leave the game. I wish you could see fit to run the article and sketches en changing my Longster over to take the Harlequin motor. You will recall that you had me make up the drawings and the article was promised for publication in MM as soon as the Harlequin series was done. I have had a number of letters asking when it would be out. Last winter I sent you a couple of shots of a Church midwing powered with a Harle- quin, and these have not showed up either. Wish you could run them in Andy’s strip. The motor is certainly satisfactory, There (Continued on page 12) These views are of the “Whizzer,” built to Farmer’s plans, by Warren La Barre, of Portland, Oregon. Mr. La Barre says he gets about 25 miles per hour. Lef¢, the little hydro out of her element, and right “getting out and on it.” Inventions for August 11

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Adventure! Thrills! Read “Gambling Ship” -~a red-blooded yarn of racketeers on the high seas, for the thrills of real You'll see the picture on the screen soon— adventure! read the story first. Read, also, the stories of other current movie hits—‘Hold Me Tight,” “The Power and the Glory” and “When La- dies Meet”—written by the leading writers of the day and. published in this popu- lar magazine of the screen. You'll find many other stor- ies about your favorite stars and doings of the picture folk, countless gorgeous pic- tures and other fascinating features in— @AUGUST HOLLYWOOD MOVIE NOVELS NOW ON SALE If your news dealer is sold out, send 10e in stamps or coin to HOLLYWOOD MOVIE NOVELS, 529 South 7th Street, Minneapolis, Minn., and your copy will be mailed to you. nd ANDY’S SHOP MAIL BOX (Continued from page 11) has never been the slighest trouble in any so far made. They just naturally have the stuff. I have made a few changes and have in- creased the output. If you feel like it try to run the red paragraph. Leslie Long, Cornelius, Oregon. Les Long, designer of the well known Harle- quin, has made some changes in the motor since the series of articles on its construction were printed. The displacement has been increased to 96 cubic inches, increasing the horsepower to approximately 35. The bronze bushing used for a rear main bearing has been replaced by an SKF ball bearing which considerably simplifies the construction and adds to the efficiency. De- tails on these changes may be had from Mr. Long. tok Many clever chaps while away hours of genius out behind the old homestead barn. One of the neatest farm-produced contraptions I have seen in many a moon was.made with a handful of junk by Art Brown, of Brimfield, Mass. I am running a pic of his saw rig, and the letter that reached me from him. Tower Hill Road, Brimfield, Mass. Gentlemen: I herewith inclose two photos of a portable (Continued on page 17) This sweet little saw rig was made by A. E. Brown, of Brim- field, Mass. She is turned over by an old Reo chug-chug. c 12 Thank You for Mentioning Modern Mechanix and Inventions for August Vhen Writing to Advertisers

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Secrets of Ancient Medicine Men (Continued from page 5+) human eye was one of the superstitious eures for eye trouble. A prescription for stomach ache called for the removal of the heart of a living lark and its being worn on the left thigh. Epileptics were instructed to gather peonies at night when the moon was on the wane and, wrapping them in linen, to wear them as an amu- let: A nail from a cross, removed and suspended about the neck, was another prescription for the epileptic. Since some forms of epilepsy have been listed as highly curable under the new system, it is pointed out that this superstition may have pro- duced many actual cures in spite of the ridicu- lous nature of the instructions. A difficulty encountered is the fact that practi- cally all minor ailments, most physical injuries and a considerable number of serious physical disorders generally end in recovery of the pa- tient. It was this fact that convinced the savage that his medicine man had supernatural powers and it still operates to convince the followers of modern cults of miraculous cures. Experimenters delving into the subject, taking account of the fact that most persons recovered from their ills in time, set out to learn whether the followers of healing cults recovered more rapidly than the non-believers and their experi- ments are said to have borne out the belief that they do. To discover the reason for this, a study of gen- eral physical effects traceable to purely mental or spiritual causes was undertaken. It was noted at once that fright quickened the heart beat, that worry upset the digestion, that envy, jealousy and hatred affected nerves, glands and blood vessels. This indicated that there were certain emotions that could be tabulated as harmful. Among these were: pessimism, dissatisfaction, grief, alarm, tim- idity, anxiety, despondency, suspicion, hatred, worry, cowardice, anger, moroseness, remorse, vacillation, selfishness, envy, jealousy. These, upon analysis, were found to be merely different forms of fear, selfishness or discourage- ment. For a working hypothesis it was con- sidered that these harmful emotions generated through the glands, blood stream or other physi- cal agencies of the body a sort of poison which caused illness or a predisposition to illness. Leaving to the doctors the problem of finding an antidote for the poisons, an effort was made to find antidotes for the harmful emotions and this proved easier. The beneficent emotions were soon listed to include: optimism, satisfaction, hap- piness, confidence, assurance, trustfulness, hope- fulness, certainty, love, cheerfulness, courage, pa- tience, enthusiasm, conscientiousness, determina- tien and the like. To build up faith or trust, to inspire hope, to inculcate charity or love as an antidote to selfish- ness and envy, it was found necessary to bring to the patient some authority of a philosophical or religious nature. In general religion was believed to be the most powerful agent although anything of an inspirational nature was found valuable, one STARTLING Daeatve ADVENTURES START DETROIT’S UNHOLY ALLIANCE OF SNATCHERS | A colorful fact story of the most outrageous gang of kidnapers in the history of the nation packed with thrills and fully illustrated. This powerful tale begins in the August issue. Also— READ The Ransom of Peggy McMath An astounding detailed and gener- ously. pictured account of Cape Cod’s’ blackface abductor and the courageous little girl who kept her ‘nerve through a horrible expe- rienee. This and other outstanding stories graphically told. All TRUE Cases August Issue NOW ON SALE 15c If your news dealer is sold out, send 15c (stamps or coin) to STARTLING DETECTIVE ADVENTURES, 529 South Seventh St. Minneapolis, Minn., and your copy of the August issue will be mailed direct. Thank You jor Mentioning Modern Mechanix and Inventions for August When Writing to Advertisers

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Solar Telescope—‘1.25 Maa NEARLY 21] 3 FEET LONG The new Excelsior Solar Telescope is a large and serviceable instrument, nicely made and accu- rately fitted. When extended it is almost three feet in length, and when closed measures not quite twelve inches in length. Telescopes of this size usually sell for many times this price, but by importing them direct, from a large European manufacturer, we are enabled to offer them to our customers for ONLY $1.25 each, at which price they ought to sell readily. The lenses are well made, the sides are brass bound, and the four sections are perfectly fitted. Here is your chance to obtain a Telescope for a nominal sum. It will be sent postpaid to any address upon receipt of $1.25 in any convenient form. Postage stamps accepted if more convenient. 770 page Catalog of novelties, tricks, jokes, etc., 10c. RADIO | 250 MAGIC TRICKS SILENT DEFENDER MADE An ercellent Little book EASY containing nearly 300 tricke Used by police officers, detectives, ty, for parlor or atage that sny- sheriffs, night watchmen and others one con do. patie rae k as a means of self-protection. Very Serta Bottles, atria. ates effective. Easily fits the hand, the V Also Second Sieht, Shadows 4 fingers being grasped in the four Wt graphy, ete. Prolusely il- holes. Very useful in an emergen- f.. IENT ted. 100 post, r F cy. Made of aluminum they are very RADIO GETS” shows how to make and me i Es tustrated. TOa postpaid. light. weighing less than 2 ounces. Operate inexpensive Radio Sote, the ma-| 125 CARD TRICKS and sleight of hand. Hanuy pocket size always ready for instant use. i hased for a ma o atest and best card tricka as i : P ee Oe ee eee Sarah, performed by gelebrated mae ciane, vith ers _ Price 25¢ 6a., 2 for 45¢ postpaid. 770 page Catalog of i inging in foreign stations, | posure of card tricks use rofeasional ; it Dolise calle, ships ot eee, et¢~ ONLY 180 p-pd. | gurablers, Price 2senostpald. Coin or stampa, Se SE ee eee “RAINE ET DIDIL zx. °zcLBPDICE MATCHES rinian with Z5illustrationsfor MIDGET BIBLE SURPRISE MATCHES Boy Electrician zit (gitustrstions ter woes al More fun than Motors, Telegraph a] paratus, Telephone, Lighta, Oghting with your Bells, Alarms, Coils, “Wireless” Current Reverser, wife, Look just g _ | Electric Engine, Radio, etc. By electrical experts so that anyone llke ordinary à ¢an understand it. With big novelty catalog. All 10c Fostpaid. matches. As the JOHNSON SMITH & CO., Dept. 919. RACINE, WIS, victim tries to light ag i a AA E 3 Wonderful Saepe S sue g 35¢ LOOK: timent. Price t0¢ per box, 3 boxes for 25c, #2 for 75 cenls. es s BS Greatest Teciated. Make good money STAR TOY MAKER thing © church acqueintanc Greatest boys’ hook | aimi yet. Nine |. 3 for 400, 12 for written. Tells how to make separate 100 for $7.50. Also obtainable I e Pinhole Camera,s Canoe, Binding, with gold edges. P mode! Railroas f 1 W articles each, 3 for $1.25, $4.50 o! ™ phone, Boomerang i In one. fying Glass (or uss with Midest Bi raph Instroment, i Li * Everybody de- SERPENT’S EGGS Mlcrossape = Elec tris a lighted with it. T otor, Electric Door Hell, F Odd, Curlous and interest- M Water Wheel. Paddle Raft, a palr of Skis, Ing. Lotsof pleasure as well a Dog Sied, Bird House, Rabbit Vard, etc. as very useful. It ts a double Microscope for ex- 4 paged. 100 neirations, PRICE” 100: amining the wonders of nature. It ig also an BOY'S OWN TOYMAKER, A new book. Opera Glass, a Stereoscope, & Burning Lens, a Reading delle how to make chemical, toys. electrical |G . & Telescope, a Compass, a pocket Mirror, and a love, Grdboatd ete, hee eae ets og | Laryngoscope—for examining eye, ear, nose and throat. It illustrations. Price 2%c postpald, Ig worth all the cost to locate even one painful cinder in the FUN WITH MAGNETISM. 50 novel and [€Y@, Folds flat and fits the pocket. Something great—you Withabunech | unique experiments in MAGNETISM that need ons. Don’t miss It. Sent by mall. Only 35¢ or 3 for $1.00, of these bills, emacs ot Fa Berform with the RilewFwnrne Alm. MRO Zi} Bid of d ti Et ig easy TOF | g m t tegi PISTOL CIGARETTE CASE gad spinning needle, nail and of limited Š ball cluster, magnetic fish, Tt looks like a deadly weapon, but it Js merely & menns to | top, motor, magnetic billiard balls, many other: novel Cigarette Case. This clever contrivance appear | punts. Aleo interesting information. about has proved {tselt better than the real thing 1p prosperous | \adestone, magnetiam, electria ty, ete. PRICE many an awkward encounter. Great fun by flashing | go0K on BOATS. How lo build rowing. “sticking up" your friends. They squirm a roll of j| asiling boate. hi taining to boat: and protest it might be loaded. Pull the these bills ctplnined tn plain terms co anyone ean Under 4 we. trigger and the slide files at the|etend. Iltutrated. 10¢ p.nd. k 3 open disclosing the clga- cee .-BLJgproper| S-MINUTE HARMONICA COURSE. A rettes. Well made, light time and peellng of a genuine bil] | now easy self-teaching method. Teaches how Yand compact. Welght or two from the paige of the g5 ieper ao pe E tremolo, fully only 2 ounces. the efect ereated w o found TO | eee eee Tee Pos Ba Ce o MONEY MAKING SECRETS. Golden oppor. 1c 5 be all that can be desired. Prices, | tunities f e oaee copyrighted f į c postpald: 40 Bills 206,228 ter Soc, book chock full of money-making ideas, reelpen POSTPAID $3.50 thousand postpald, | formulas, wrinkles, trade secrets, etc. sio | amaai A that be atarted th little or no a ae ee eee ioe postpaid, LEARN to NOSE FLUTE | tricks a sociat ENTERTAINER. Co ‘ i j i | With the ald of = +f The Maglo Nose Flute, or Hus j tains hundreds of simple tricka, illusions, di- eae e col H notize i that anyona can do. Aleo explains 4 i nag s 3 o, Snjaue, and decret of second eicht. Priee 25c postpald. end fortune K ZA y l M S ae ee : teller. The key y AA This remarkable F =| T . pe WONDERFUL x RAY. TUBE f gem pii Y yone faturs. Ce book tells how. ‘lucky în love? xplains all instrument pro- Sue cesstul in Exp i ¢ i bout Hypno- optica é business? Will al filGaiens prea 7 yoube wealthy? | § =: tism. how to surprising and |K Ss Complete Sith hypnotize, how ; ri startling. With it dictionary Qf | to produce sleep, how to is no Gingering, end once you have mastered the bones of | descriptions and correct interpreta- | awaken a subject, how tonyp- it you osn play all kinda o music with fscility b eo ben ben a the ins tions, with lucky numbers, fortu- notize animals. hypnotism in y wp, and many othes |nate days, oracles, divination, palm- | Jiseases, hypnotism for scien- tor 25 i > JOHNSON SMITH_A ÇO. similar Musions,_Enise 100, 30 SMITH & CO: Oe, Jir gats bry cates, Alea tells ener. ‘ey tific practice, illusions and JOHNSON SMITH S COn |ti: te by im | hatucirations, personal mag" a ges, by marks, sears, or moles, mis- . netism, „thought traneference, . a ma mes ecards, lucky te. tten in jain, everyday Dept. 919 RACINE, Wi Soya. AEn months yeara; howto | fangaage that anybody can under- copy of our NEW CATALOG mailed on receipt of 10c. or the De-|recelve oracles by dreams, finger | stand. PRICE 10c postpaid. puxe dition with ciot binding 250.Bigger and better than ever.Only|nail observations, etc. PRICE 10c st g ook of its kindin existence. Nearly pages of all the latest tricks (eRe in magic, the newest novelties, puzzies, games, ers rubber stamps, unusual and interesting books. curiceittes fnecee as FORTUNE TELLING BY CARDS aoe and plants, ete. unproç irabis sisewhgre Pomir by, Colne Money 64-page book tells how. Gives the meaning of each ana every, e F Unuge: |. S. y at ed above. Canadian money, stamps and Postal Notes accepted at card, how to deal and lay them out. Everything explained in current rate of exchange. simple language. PRICE {0cpostpald. 770 page catalog 10c. ' Address orders for all goods on above and on following page to Johnson Smith & Co., Dept. 919, Racine, Wis, aoc 14 Thank You for Mentioning Modern Mechanix and Inventions for August When Writing to Advertisers

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Elect BOYS tic Telegraph Set {A private Electric Telegraph Set of your a own for 15c- Lots of fun sendin messages to your friends. Brg-# still get two sets, hook them up as shown in the daii SAGES (sending esi: to operate with compsny each set. ns, for TWO-WAY MES- ceiving). No trouble at all the simple instructions that ac- Operates on any standard dry battery obtainable every- where. With tht; gxtfit you can learn to transmit and medwe messages by the Morse Intemaäonal Code, and in a very short time become an ex- pert operator. Mounted on wooden base measuring 4 x 3 in., first class construction tkspughout, complete key, sousi5ar, magnet, min- jature Westen Union blanks, packed in na% box with full illustrated instructions — ALL FOR 1& C battery) postpaid (Canada and Foreign 20c.) 770 page catalog of novelties, jokes, tricks, puzzles, etc. 10c. SMITH & CO. Racine, Wis, with hook Jo Dept. 919, Button nsefal for hundreds 2¢ axperiments along speakers, ete. Many fascinating stunts may be devised, suchas. holding © throat or chest to reproduce speech without sound waves. Í DOT N. POTN PASH m 10c Add 10c for 64] page book, all about electricity written specially for boys. Tella how tomake batteries, dy- namos, motore, radi telegraph apparatus, telephones, lights,electric bells, alarme. coila, electric engines. PRICE 10cppd. ‘without BUTTON any thie You can easily make a highly Bensitive detectophoneby pelog. hie yo Transmitter Button to collect the sound waves, You‘can bn! orn outfit without buying expensive ulpment. It:ie simple and icaxpensive. You can Install an outfit in your home and hear con- versations being held all over the house. You can connect up differ- ez: rooms of a hotel. This outfit was used by secret service opera- tives during the war. It is being used on the stage. I]t is ultra-sen- itive and is the greatest invention in microphones. You can mount the button almost anywhere—cardboard boxes, stovepipes, stiff eaJendars, on the wall behind a picture frame. ete. Button is so light and emall it cannot be detected. Persons can be overheard without suspecting It. You can listen in on conversations in another room. A deaf person in the audience can hear the speaker. Con- ' nected to phonograph, plano or other musical instrument, music can be heard hundreda of feet away .Button may, be used to renew tel- ephone transmitter; often makes an old line ''talk-up’’ when noth- ing else will. The ideal microphone for radio use; carries heavy cor- rent and isextremely sensitive, Ampllfies radjo signal. Countless other elmiler usea will suggest themeelves. Exper!menters findthe e lines of telephones, amp ifere, loud the Button egainat $5.00 is given to anyone who sends in a new suggestion for the use of the Button providing the manufacturers find it suitable for use in their literature. PRICE $& TPAID. ELECTRIC MOTOR An Electric Motor for Only 10 cents. Sounds almost un- believable but it is perfectly true. For ONLY 10 cents we send you all the parts neces- sary packed in a neat box with full printed and Wus- trated directions for assem- ling. No trouble at all putting the parts to- gether, in fact It is FUN. Just follow a few simple, instruc- tions and in a few minutes the motor is ready to run. 10c S ENTERTAINER Curt-oute (=z Ck... 16 and Chess, 180 Jokes and Riddles, 34 Magic Tricks, 54 Parlor Games, 73 Toasts, 15 Card Tricke, 9 Fairy Tales, 50 Money-making Secrets. 10 Funny Readings, 3 Monologues, 21 Puzzles and Problems, 5 Comic Recitations, Dominoes, Fox and Geese, 9 Men Pa Morris, Spanish Prison Puzzle, Game of Anagrama, etc. All for 15c postpeid. a ——— Dent, 919, — 8 CO. EO i emcee ete. = ured! sew! ad oi S. Postage Stam Maney, stamps nnd Postal 770 page Catalog of novelties, jokes, tricks, etc., 10c. JOHNSON SMITH & CO. RACINE, WIS. of our NEW CATALOG malled on recelot of 10c.. 2. th cloth binding 25e. Bigger and tha kiyi i Nearly 800 4i planis, ml M Chack or s for all ariicioe listed abo’ Canadian ates accepted si current rate of Exchange. Feat You for Mentioning Modern Mechanix and Inventions tar Augue VREI Triine 40 Advertisers Electrician] f ` NEW POWERFUL 2 5 Add 10c for postage and packing toys. A great blg steam engine, measuring 7 inches in helght by 2% Inches in dlameter cents., You should see it run, too. It's a revelation to see the fly wheel spin around up.” Just light up, fill the boiler with water, and in a few minutes the engine is runs on alcohol or canned he2t—MORE POWER. Has fly wheel for running small GUARANTEED TO RUN Tt is foolproof, harmless, fully tested and guar- principle of the ateam turbine. Rune for hours on one filling of water. Every boy should have one. Selle for ONLY 25¢, with 10c extra for postaze and packing. Ensily worth double. Electric Model of same z =. Crystal Radio Receiver, $1.00 Say what you will about CRYSTAL set has them all beat for simplicity and clear- lutely no noise and no distor- tion—no batteries to buy—no tenance expense whatsoever, Cost nothing to operate and tion is loud and clear. This Receiver is guaranteed to work equal can buy. Hae a receiving radiue of over 25 miles, or under favorable con- of the finest materiale throughout, in- cluding supersensitive crystal, neaure MODEL JUST OUT The world's biggest value in mechanical (7% inehes in circumference) for ONLY 25 at a great rate as soon as you “get steam { running at top speed. New model just out, mechanical toys. anteed to run. A scientific toy that illuetrates tho Wonderfully well made—splendid value for the money. Engine also araùable. Price S6¢, postage 10c extra. Electrical and Battery Sets, a ness of tone. There ig abso- tubes to wear out—no main- will last indefinitely. Recep- to the mont expensive Crystal Set you ditiona up to'100 miles, Conetructed ing quick results, PRICE of Receiver only $1.00 postpald. Or completo with Ear Phone and Aeris! Kit—everything all complete—nothing more to buy, $2.95 postoald. JOHNSON SMITH & CO., Dept.919, RACINE, WIS. Single and 100-Shot AIR PISTOLS Just what you've always wanted. A powerful high grade Air Pistol, shaped like Automatic, pocket sino, Fires B. B. shot obtainable any where. Very powerful yet perfectly. ane for boys to handle, Two styles—Bingle Shot Pistol or Repeater. The Repeater fires 100 ahote in one loading. The Single Shot Pistol shoots Air Rifle Darts in ad- ’ dition to B. B, Shot. Well made and durable; all metal partsinickel plated; natural grain wood stocks. Front and rear eights, Welzhs about 10 ounces. Better than en sir rife. By Express only. Ne id. PRICES: Single Shot Pisto! 100-Shot Repeating Pisto BLANK CARTRIDGE PISTOL Protedion against Burglars, Tramps and Dogs Prices 50 c a $ 1 00 Shipped by Exprese only. tol Dropald. Well made and effective; modelled on latest typo lof Ravolver; appeatance atone ie enough to eraro a burglar, When loaded jit may be ae efiective as a real revolver without danger to life. It takes standard .22 Ca). Blank Cartridges obtainable everys where. Price 30c. Supertor quality, $1.00. Stank Cartridges, 500 100. Holster (Cow type) for Blank Cartridge 1. 50c. Shipped by Exprens only. BOYS! THROW YOUR VOICE 41%) 2, Into a trunk, under the bed or anywhere. Lots $ of fun. fooling teacher, policeman or friends. a little instrument, fits in the mouth out of sight, used with above for Bird Calls, etc. Anyone can use it. Never falls. A16 page course on Ventrilo- quism and the Ventrilo. All for 10 cents postpald. JOHNSON SMITH & CO., Dept. 919, RACINE, WIS. s 15

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New PLANS for the Shop Worker Get your copy of Modern Mechanix and Inventions’ big Blueprint Book— it’s freet Projects shown in the book are the most popular how-to-builds run by the magazine, and on every one of them large size, genuine blue- prints are available at low cost, making it easy to build the items in your own shop. Boats, airplanes, trailers, home built autos—take your choice from these and scores of other subjects! Thousands of Modern Mechanix and Inventions projects have been built from these blueprints; they’re the cream of all how-to-build articles published during the past five years. A few of the plans are listed below: NEWEST PLANS ESKIMO KYACK—Simple little one-man rough-weather canoe, com- pletely covered except for space where paddler sits, making it prac- tically impossible to swamp. Con- struction is simple, layers of tough kraft paper, bound with varnish, being used for covering. Tested and designed by Sam Rabl. Price of blueprints ........... $1.00 DIVING HELMET—With this helmet, constructed of odds and ends which cost bute a few cents, you can explore lake bottoms as deep as 30 feet. A fascinating new world opens up before your eyes. Money can be made with it, too, recovering outboard motors and other objects lost in the water. Blueprints .............. $1.00 ELECTRIC REFRIGERATOR— Blueprints show you exactly how to construct an electric refrigera- tion unit, and printed directions supplement the diagrams. At a cost of around $40 you can con. struct an electric unit for your icebox that serves as efficiently as a manufactured model costing five times as much. Blueprints. . $1.50 SCRAM—Newest addition to the boat plan list. She is 1514 feet of dynamite, inboard motored—will do around 40 with Ford A engine. Forward and aft cockpits, with mo- tor between. Can be built in a garage, and is a flashy performer. Prints include drawings for marine conversion of Model A Ford mo- tor, Blueprints ..,.......$3.00 AUTOS BUNGALOW TRAILER — The most popular trailer design ever published; thousands have been built. Two wheeled, folding de- sign—folds together compactly for traveling, can be opened up in camp. Weatherproof; built-in beds for four adults; running water, household. comforts. About $30 should build her—much less, if you have a few parts lying around. Wheels and axle from most any discarded car chassis will do. Blue- PRIMIS nse cae eS ee whe a $1.00 AIRPLANES AIR CAMPER—FPietenpol’s mas- terpiece, the most popular light plane for amateur construction ever designed. Two place, model A Ford motor, high-wing monoplane. Costs $500 to build, including mo- tor. Thoroughly tested out in cross-country service. Prints give conversion details for Model A motor. Blueprints........$7.50 SKY SCOUT—A smaller Air Camper, single place, using Model T Ford engine. Designed for easy building, safety rather than speed. Wood fuselage. Blueprints. . $4.00 GERE SPORT BIPLANE—The leading light biplane design. Suit- able for Model A Ford motor. Single place, rarely beautiful in appearance; an Army pursuit plane in miniature. Steel fuselage. Blue- EMIS ic doe Sey Aang Wet $5.00 BOATS PUNKIN SEED—An 11-foot hy- droplane that cleans up in compe- tition with the right outboard on her stern. Capable of 45 m.p.h. Concave V-bottom with one step. Blueprints .............. $1.00 WHIZZER—An air-drive speeds- ter, one step scow type hydroplane, driven by air propeller at tear with motorcycle engine. Motor should be of at least 20 h.p., not over 125 pounds weight. Blue- PISI 2. ee ee es $1.00 DOROTHY—A John Hanna de- sign, auxiliary cruiser with 10 h.p. motor, two sail plans. Two berths, five-foot headroom in her 24-foot null, A deep water boat by a mas- ter designer.. Blueprints... $2.50 GANNET—24-foot cruiser with bunks for two, complete galley, nicely boxed-in Ford engine in- stallation. A very popular de- sign by Charles Hall. Total cost, including motor, from $300 to $500, depending on locality. Blue- BEINGS: os scieicst ode Se Bens $2.00 CANVAS CANOE—By Chester Nedwidek. Length, 16 fe, plank- ing of 3/32 in. cedar covered with No. 8 canvas. $15 should turn out the complete job. Blue- 2 7ER ae any Seco prints ........ M-M SPORT ROADSTER—Cus- tom-built to your own fancy! Four- cylinder motorcycle engine, chain MODERN MECHANIX AND drive, wood frame, Model T Ford Sireen Minean ipeventh differential unit, four wheel brakes. Gentlemen: Please send me my copy of the big new Blueprint Book by return mail. With these cheaply acquired units, This comes to me without the slightest obligation. ue car does 65 m.p-h. Body of I enclose $........5 ++. in payment for blueprints of.....--- settee eee e eee Senne abric construction, easy to work. (Note: This form can be used if you wish any of the prints listed above without Blueprints ........+0..-.- $2.50 waiting for the descriptive booklet.) M-M SPEEDSTER BODY—Rac- Name .. ing body for a Model T Ford or Aaa similar chassis, Wooden frame, Sis wire covered, then a layer of cot- ton batting held down by imitation leather. Blueprints ....... $1.00 1 a HEED 8 16 Thank You for Mentioning Modern Mechanix and Inventions for August When Writing to Advertisers

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ANDY’S SHOP MAIL BOX (Continued from page 12) wood-sawing outfit built by my brother and myself about a year ago. The power plant is a Reo 4 cylinder engine, and the trailer on which it is mounted is a 1926 Essex chassis, shortened up, and a léad pole attached. Because of the simplicity of construction and the fact that various makes of motors and chassis can be used for building the rig, I thought that this project might be of interest to some other M.M. fans. If this can be of any use to you, I can furnish a set of plans, and give the details on the construction. The machine can be built at a cost of not more than $25.00, including tires for the trailer. If you cannot use this idea, please turn the photos over to Andy’s Shop Mailbox. Andy may find some use for them. Yours truly, Arthur E. Brown. No, Our Sam Wing does not run this de-buttoning estab- lishment. A friend in Ava, Illinois, has sent us the shot so we can deny it. Bill Bartlett of Ava, Illinois, wuz in t? Chicaw- go th’ other day an’ saw a Chinee Laundry run by a guy named Sam Wing, who is probably saving up punched money t git back to China in his ripe old age. Bill sent me a letter that Tm runnin’ while Sam is acrost the field dingin’ up a model boat at the edge of th’ lake: Ava, Illinois. Dear Andy: ° Enclosing an interesting and illuminating insight into the intimate industrial inclinations of one Sam Wing, your competing contem- porary on the vacationing Packmag person- nel. This de-buttoning establishment is to be seen on West Addison, in the Windy City. And now, Andy, as one prodigal pelican to another, I might as well tell you how to end (Continued on page 18) PATENT four ideas Small Ideas May Have Large Commercial Possibilities If you hope to realize profits from your invention, you must protect it with a U.&. zovernment Patent. Otherwise, you may find thal us: your tim and labor have been lost, because it often happens that other inventors are working on the same idea. I" YOU HAVE AN IDEA, TAKE STEPS TO GET A PATENT AT ONCEI Your first step is to get my FREE BOOK. It tells you in simple, plain language just what you must do, how you must proceed in order to secure Patent protection- I Serve You in Secrecy You can communicate witn me In perfect confidence. Any drawings, sketches or letters you send me will be kept in strong, steel, flre-proof files that are accessible only to authorlzed members of my staff. I haye served inventors located in every state inthe Union, My service is prompt, careful, efficient. Your first step—the move you should make today— is to SEND THE COUPON FOR MY FREE BOOK. g Book shows how “Record of 7 77 Invention FREE!‘ you act promptly I will send you this valuable Record of Invention blank absolutely FREE. It may help you to prove your right to your invention later on. CLARENCE A.OBRIEN Registered Patent Attorney WASHINGTON, D.C. l Clarence A. O’Brien, Registered Patent Attorney, t l 3175 Adams Building, f i Washington, D. C. l į Please send me your free book, “How to Obtain a 4 y Patent,” and your “Record of Invention” form without 4 i any cost or obligation on my part. i I U Naitieenndidclatee alee aca aa iioi in t t i B AdireIS inin vere reason ASETE RE ETEN EREE sar rae NENS t i I I l 1 i y- i l i l ) i i bannnan a a en Thank You for Mentioning Modern Mechanix and Inventions for August When Writing to Advertisers 17

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@O@GOLD waned We pay the highest p rices and send spot cash by return mall for discarded Jewelry, dod Coins, Dental Gold. Old Watches and Rings, Plated Articles, Sliver, Platinum, etc. WE WANT MEN EVERYWHERE. to act as our local buying agents — Good pay— Positively No Selling. We teach details and fnance purchases. Write today. C. J. CLARK REFINING CORPORATION 109 N. Wabash Ave, Dept. D-8 Chicago, II. Build This GYPSY Trailer for g Vacation Time © This Bungalow on Wheels —sleeps four adults —costs $30 or less to build —folds up to car width when on the road —carries all household equip- ment, including running wa- ter and built-in beds. —is completely weatherproof O WONDER this trailer has proved to be the most phenomenally popular how-to-build project in years! Literally hundreds of them have been built since the plans originally appeared in the May, 1932, issue of Modern Mechanix and Inven- tions. The illustration above shows the outfit in camp for the night, unfolded as a house. For travel- ing, the side balconies are folded inward, the roof top down, and presto! you have an easily towed trailer which allows complete vision from the rear window of your car. LUEPRINTS show the trailer layout with all dimensions. Prints are large size, specially made for shop use, easy to read. Any man who can tell a hammer from a saw can put this trailer together to last for years. Price of blueprints, g postpaid 1.00 Modern Mechanix and Inventions 529 S. Seventh St. Minneapolis, Minn. oul ANDY’S SHOP MAIL BOX (Continued from page 17) the depression in the magazine business and please our discriminating, although nearly forgotten ‘brother-under-the-skin, Mr. G. L. Farrar. Here’s the dope. Each month, I sug- gest you run a picture of a gorgeous gum- T grinding Gertie at the head of your column. (blondes by preference, with an occasional brunette thrown in for variety). And perhaps a few dozen closeup views of a bathing beauty contest in a —————colony would go well with your clientele. No doubt other patient perusers of your putrid punk will agree with me. I believe this would please all, from our fastidious friend Farrar, down to myself, who each month meanders metropolisward, and trickles through ticklish traffic, to slap my hard earned nickel and dime down on the newsstand line—all this for the rather doubt- ful privilege of browsing over your enigmatic epidermics. I don’t doubt but what this will coax Prosperity from around that chronic corner, and sic ’im onto the seat of the circu- lation manager’s pants. Going, going, gone, BILL BARTLETT. I’m running the pix, Bill, to prove for all time that our Sam Wing is an Englishman and not a de-buttoner with almond eyes. Gotta make a memento of some sort. Sam’ll thank me for this favor. # * * From ’way up in Camrose, Canada, I have re- ceived this script from Bill Gardener. (Wonder, if he knows, being a boat fan, that one of the. best naval artichokes who ever lived was named. Wm. Gardener?) Well— Dear Sirs: Would it be possible to send one of these booklets to Mr. J. Pratt, of Camrose who is also interested in boat building. Together we built a very successful “Sun Ray” sloop last year and later we intend to each try another type. The “Sun Ray,” despite many pessimistic opinions turned out good and we had a lot of fun out of it. It sure sailed fast and on tacking in a good wind it would come around like a well trained horse on a gallop. Your plans are as complete as it is possible to be and so plain that anyone can read them. We find that the greatest requirement was patience. It took most of our spare time after work for six weeks to complete it, but it was worth it.. Hoping you may oblige, I remain, Yours truly, Wm. E. Gardener, Camrose, Alberta, Can. That gives you an idea of what “Sun Ray” can do and how long it takes to build her. She can be had in plan form in our How to Build It book, available at this office, ahem, for fifty cents. ipe 18 Thank You for Mentioning Modern Mechanix and Inventions for August When Writing to Advertisers

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ANDY’S SHOP MAIL BOX Much experimenting is being done with minature gas pow- ered airplanes that really fy. Here is one built by Juniors of the Pasadena Technical High School. One horsepower. Up above you will see a sweet little monoplane built by members of a Junior class in a Pasadena high school. This little ship is to be powered with a small one-lung two-cycle engine similar to the Wall engine “Mighty Atom” which ran com- plete—plans and all—in the Packmag, Issue No. 1. I got a letter from a lad in New Jersey recently (just a short one) telling me his gas powered midget had flown out of sight and was found wrecked three miles from the Teterboro airport. 1000 Ways to Make a Living (Continued from page 77) of wood about four inches by six. Next to each picture he places a small pad of paper, a calendar, or a thermometer to increase its usefulness. Farm Exchange Business Starting with an old touring car a farm worker in Pennsylvania has built up a really “big busi- ness.” He hired neighbors to pick huckleberries and blackberries that grew wild in his territory, then sold them on a commission basis in towns near by. From this business he made enough money to buy a truck to handle all kinds of farm products. Soon he was covering over two hun- dred miles of territory. Then he got an agency for farm implements, taking part pay in farm products. All farmers, he says, have something they want to sell for whatever they can get, and you can sell it if you work hard enough. Furniture Painting Shop -Almost every home has some piece of old furniture which could be made colorfully at- tractive with a fresh coat of paint or enamel. One man sent out form letters soliciting the work of painting such furniture and soon had all the work he could do. He carried color cards with him and suggested color schemes and dec- orations. The work at first was usually done right at the customer’s home but, when neces- sary, he took the furniture to his own workshop at his home. At first he used brushes exclusive- ly, but business increased to a point (he now makes $35 to $50 per week) where he had to buy a paint sprayer to enable him to work faster. fi Turns 2s = Spare Time Into Money! Up to ‘40 a Week! without Leaving the House We show you how to make big money decorating fast-selling Giftwares and start you off with the big, complete $10 Artist’s Outfit shown above. Also Free Idea Book that has started hundreds of men making big, easy money. One Fireside Member says, “I made $100 on furniture in one week.” Another writes, ‘‘My sales were $500 for 5 weeks. This is my first year.” R. M. P., of Illinois, says, “I did $3500 worth of business last year and over $12,000 this year.” D. W., New Mexico, reports, “L would not take $1000 for my Course." If you really want to make big money, a guaranteed income opportunity is now ready for you with Fireside. No tire- some study. You learn by doing. You make good money practically from the start, Our FREE Book tells you how. NO SOLICITING---- NO CANVASSING It’s easy to dispose of everything you Make, Our new ‘‘AutomaticSalesman’” does all the selling for you. This vendor is designed to quickly And cash buy- ers for all the Giftwares you can turn out! No soliciting or house to house canvassing required under thls method. Nor do you need any artistic ability in order to succeed. Simple ‘‘3-Step Method” makes the work easy to learn and easy to da Under new Plan your membership need not— should not—cost you a penny. Get full details. Coupon brings everything. REE Book on Decoration 5 Mail the coupon NOW for the beautiful new Book on decorating at home for big money. A new Plan that gives youa quick start included free. Mail coupon now while openings for new mem- bers are still be- ing offered. FIRESIDE INDUSTRIES Dept. 142-K Adrian, Michigan a m e es ee es ee ee Fireside Industries, Dept. 142-K, Adrian, Michigan. Send me FREE Book on Home Dec- orating for a big steady income. Also how to get the big Artist’s Outfit. "Send the coupon for it, Thank You for Mentioning Modern Mechanix and Inventions for August When Writing to Advertisers 19

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CLASSIFIED ADVERTISEMENTS Rates for classified ads, 10c per word per insertion. order. Mechanix and Inventions, 35 East Wacker Drive, Chicago, III. ADVERTISING AGENCIES ADVERTISE: 24 words in 250 news- papers $10. Lists Free. Advertising Service Bureau, 4650 Drexel, Chicago. AGENTS BIG MONEY and Fast Sales. Every owner buys Gold Initials for his auto. You charge $1.50; make $1.45. Ten orders daily easy. Write for particulars and free sample. American Monogram Company, Dept. 11, East Orange, N. J. FREE Literature describing many money-making plans. D-Belfort, 4042 N. Keeler, Chicago. ams AGENTS WANTED YOU are wanted to Resilver Mirrors at home. Profitable business „phting autoparts, tableware, etc. rite— Sprinkle, Plater 850, Marion, Indiana. AGENTS’ Gold Sign Letters for store windows. 500% proft. Free sample. Metallic Letter Co., 426 N. Clark, Chicago. METALLIC LIQUID—Repairs metal, wood, everything without heat. Selis 25c. Costs 6c. Sample Free. Bestco, 5005-W Irving Park, Chicago. BIG MONEY applying gold initials on automobiles, Easiest thing today. No ex- perience needed. Free samples. “Ralco,” 1084 Washington, Boston, Mass. GOOD income plating auto parts, re- flectors, mirrors by new method; outfits furnished; free particulars. Gunmetal Co., Avenue A, Decatur, Tl. p AIRPLANE PAINTINGS BEAUTIFUL painting of your plane from plans or photos by famous cover artist. Josef Kotula, 70 East 45th St., New York. AVIATION BUILD Corben Baby Ace, complete kits including: factory welded fuselage, tail unit, under carriage. Folder, dime. Cor- ben Sportplane Co., Madison, Wis. NEW low prices on SB Aircraft en- gines, propellers, hubs, conversion parts, etc. Send one dime for latest folder to Sensenich Brothers, Depart- ment M.M., Lititz, Pennsylvania. BROTHER can you spare a dime! If you can, send it to me and I’ll send you my 1933 Low Priced Aviation Ma- terial Catalogue. Karl Ort, 683 W. Poplar St., Yark, Pa. 60 HORSEPOWER Aircoold Parasol monoplane, $150. Aircoold 90 horse- power eight cylinder motor, $100. Law- tance 28 Twin, $30. Converted Ford “A”, $65. Plain “A”, $25, Other Bar- gains: Ships, parts, materials, blue- prints. Allison Airplane Co., Lawrence, Kansas. BARGAINS in small engines for light- planes, boats, midget cars, air propellers, hubs, wheels. Circulars, 10c. Storms Aviation Co., Asheville, N. C. PROPELLERS built to order to be used on crafts for Air, Land, or Sea. Circular 3c stamp. Lorenzen Propel- lers, .Niles, Mich. 3 USED AIRPLANES $85 and up. Cat- alog 10c. Federal Equipment, Deer- park, Ohio. “AIRCOOLD FOUR”. Only $25 for steel cylinders, valves, pistons, rings, pins. Assemble on automobile crank- case, making 60 horsepower aeromo- tor. Lighter than Ford “A”. Flight tested. Photos and Instructions, $1. Allison Airplane Co., Lawrence, Kans. AVIATION-Propellers for boats, sleds and planes. Small metal propellers: State your need. The J. B. S. Propel- ler, Lititz, Pa. ARMY AIR CORPS gives one year free flying course, 250 hours solo flying, salary while learning. Send 20c for information booklet telling how to quali- fy and apply. Federal Equipment, Dept. 23, Deerpark, Ohio. LISTING bargain stocks used, surplus airplanes, engines, wheels, tires, sup- plies over the entire United States, In- valuable. Aerobuilders Service, 1315 South 12th St., Lincoln, Nebraska. METAL Tipped Propellers; Fords, $9.98; Henderson, $8.98; Harley, un- tipped, $4.50; New Improved Heath ships, $248.00; Bristol Cherub Tupe 40 H.P. motors, $75.00. Photos, informa- tion including leather bound Flying Manual, 25c. Hibbs, Ft. Worth, Texas. BUSINESS OPPORTUNITIES THE PLASTEX Industry needs manu- facturers on small scale and for big pro- duction of Art Goods, Novelties, Souve- nirs, etc. in Plastex and Marble imita- tion. Experience unnecessary. 2c ma- terial makes 25c articles. Rubber moulds furnished for speed production. We place orders and buy goods. Small in- vestment brings big returns. Interest- ing booklet mailed free. Plastex Indus- tries, Dept. R, 1085 Washington Ave., New York. $$$$ $40,000—I made it. Plan 10c. “MooreMade,” Lapeer, Mich. FASCINATING new business—build new batteries from old. Work at home. Quick cash daily demand. Big profits. Particulars, catalog. Lightning Co., St. Paul, Minn. 700 MONEY Making Secrets will help you start a business of your own. Send stamp for the Open Book to Opportuni- ty. Illinois Universal, 800-M. T Cen- tral Ave., Chicago. OPERATE Chain amusement_machines. Be independent for life. Start small, grow big. M. Goodbody, 1826 East Main St., Roches- ter, N. Y. MEN—WOMEN interested money home, write for details. F-277 Broadway, New York. REGULAR income, at home; no can- vassing; men, women, anywhere. Mc- Arthur Co., Dept. 19, Butte, Mont. MAKE big money collection business. Easily learned. Free details. George Cole, Pres., Tower B, Syracuse, N. Y ` of vending and earning Eller, in_ the. mercantile Minimum 10 words. Closing date first of second month preceding date of issue. Address Classified Mgr., Modern Cash should accompany TATTOOING Outfits, logue. Guaranteed Remover. M-965 Putnam, Detroit. RECEIVE 100 letters and dimes daily. Guaranteed instructions, 10c. Write H. L. Dawe, 6249 Mershon St., Phila- delphia, Pa. SELL by Mail. Books, Novelties, Bar- gains! Large Profits. Particulars free. H. Elfco, 525-S Dearborn, Chicago. START profitable Fixit or Swap shop. Instructions $5.00 each. Adams, 1822 Park, Minneapolis, Minn. COMPLETE Chemical Service, Analy- sis, Formulas, Consultations. State Licensed Chemist. Twenty-five years’ experience. Write for literature. W. L. Cummings, Ph.D., 428 Gordon Avenue, Syracuse, N. Y. MY PRACTICAL, proft-producing plans describe amazingly simple, ethical methods for making excellent money— without capital, experience, or mer- chandise. Not formulae nor mail order, Graham Stokey, Box 1115, Los Angeles, California. MAKE Artificial Marble, Colorful glos- sy tiles, no polishing, rather uncanny. Novelties, tabletops, bookends, floors, whetstones. Hard, inexpensive, fire- proof, enamels wood. Secret cement methods. Amazing samples 3c. John H. Payn, 945 Grande Vista Drive, Los Angeles, Calif. AMATEUR cartoonists, earn’ $25.00 week, spare time, copying cartoons for advertisers. Three-M Syndicate, Argyle, is WISE MEN Get Money Easy! Plan 10c. ‘‘Mooremade,’? Lapeer, Mich. ` , CAMERAS BARGAINS, Slightly Used, 3-A. East- man Kodak, 'F:6.3 Lens, $17. 50. 2%4x 34 Folding Eastman, F:6.3 Lens, $9.50. “Waters,” 21x414 Eastman Special, F:6.3 Lens, $17.50. 9x12cm. Welta, Carl Zeiss Tessar F:4.5 Lens, $37.50. 34x44 Graflex, F:4.5 Lens, $47.50. 154x214 Eastman V.P. Kodak, F:4.5 Lens, $14.50. Send in for our new Bargain Book listing hundreds of other values. Central Camera Co., 230 South Wabash Ave., Dept. MMES, Chicago. CHEMICALS HANDBOOK for Chemical Experi- menters, hundreds of experiments, 50¢. Booklet of Experiments, 15c. Chemical Catalogue, 10c. Lowest prices. General Chemical Co., Reading, Pa. JOIN American Amateur Society. Journal, Lansing, Michigan. DUPLICATORS DUPLICATING Machines $3.85 to $95. Rotary Stencil, Clay Composition, Gelatin Film. Most Complete Line in America. Photo-Litho Folder Free. Pittsburgh Typewriter Supply, Suite 551, Pittsburgh, Pa. f Chemists particulars, 10c. dea U I 20 Thank You for Mentioning Modern Mechanix and Inventions for August When Writing to Advertisers

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DETECTIVES LEARN hotel detective work—Complete course in every detail $1.00—Room 210, Terminal Building, Hoboken, N. J. DETECTIVES. Earn Big Money. Ex- cellent opportunity. Experience unnec- essary. Particulars free. Write, George Wagner, 2640-V Broadway, N. Y. BE A Detective. Make secret investi- gations. Experience unnecessary. Write United Detective System, 1623 W. Grand, Chicago. ELECTRIC BUILD your own fans. 20-inch alumi- num propellers for aeroplane fans $3.85. Shipped collect. Michael Electric Co., Fort Worth, Texas. EDUCATION PREPARE for prosperity—our twenty week electrical engineering correspond- ence course attracting worldwide atten- tion—Basic electrical, radio, public-ad- dress, photoelectric theory covered— Experimental laboratory apparatus free with course—Attractive tuition rates— Delayed payment plan for jobless men —Write Lincoln Engineering School, 855-L South 37th St., Lincoln, Ne- braska. ELECTRICAL EXPERIMENTS EDUCATIONAL, Entertaining, Elec- trical laboratory experimental kits (mi- crophones, transformers, receivers, gen- erator, ringer, condenser, etc.) $3.27. Hand driven a.c. generators, 91c. Mi- crophones, 44c. Complete two way tele- phone kits, $1.69. Instructions with all. o toys. Western Electric, Kellogg, Stromberg-Carlson salvage equipment. Bargain bulletin, stamp. Engineering Service Company, Drawer M, 1718 So. 14th Street, Lincoln, Nebraska. FINGERPRINTS FINGERPRINT experts required; va- rious branches government; large cor- orations; particulars free. i ystem, 2640-Y Broadway, N. Y. FORMULAS í SUCCEED With Your Own Products. Make—Sell them. Formulas, Processes, Analyses. Catalog Free. A. Thaxly Co., Washington, D. FORMULAS—all kinds. Guaranteed. Catalog free. ‘‘Kemico”, B-16, Park- ridge, Ill. tobacco habit, or money refunded. Harmless, yet effective; enables you to stop at once or regulate amount used. Formula sent for $1.00. Joseph Wolk, 2683 Deacon, Phila. - FIREWORKS FIREWORKS!! All kinds! Spitfire, flashes, torpedoes, pinwheels, sparklers, giant caps, etc. Make them! Sell them!! Easy to make—Complete directions now only 35c. Dr. E. A. Tampa, 10327 Throop, Chicago. FOR INVENTORS SCIENTIFIC DATA compiled. Accu- rate information on mechanical, electri- cal, physical and chemical properties. Technical advice. Computations. Access to greatest scientific libraries and in- stitutions. Confidential. M. S. Burger, we Ingleside Terrace, Washington, SOUND inventions now salable before patenting. For information, i Chartered Institute, 514 Barrister Building, Washington, D. C. FROG RAISING “BULLFROG RAISING!” — PAYS BIG MONEY! Investigate this (New Industry). our valuable (FREE) book, “Fortune is Bullfrogs.” American Bullfrog Industries (119). Fremont, Ohio. ee HELP WANTED—MALE INSTRUCTION DETECTIVES. Work home or travel, Experience unnecessary. Write, Ameri- can Detective System, 2640-T Broad- way, N. Y. INSTRUCTION WANTED: Men — women, 18-50, Jobs. $105.00 - $175.00 month. List po- sitions FREE. Write today sure. Frank- lin sees Dept. L94, Rochester, INVENTIONS INVENTIONS — Patented, Unpatent- ed. We buy outright, royalty. Grant- Dacanay Co., Hewes Building, San Francisco, California. are the source of wealth and independence. What have you? Write National Service Bureau, Dept. H, St. Louis, Mo. INVENTORS ee INVENTORS—Sell_ your inventions before Ferenting. Free particulars. SEs reene, 942 Barrister Write Building, Washington, D. C. INVENTION FOR SALE NEW lifting jack, only four mechani- cal movements. Positively safe lock up or down. Universally adaptable. Roy- alty basis. Anthony Horvath, 9 Spring St., Wallingford, Conn. JEWELRY ee LEARN Watchmaking. Free beginners’ tools. Movement instructions 50c. Any watch repaired 1.50. Experimental movements 10c. Catalogue, details 5c. Stewart’s, Carleton Building, St. Louis, Missouri. ! Guaranteed work- manship and prompt service. J. B. Blanquart, Collinsville, Til. MAGIC LEARN MAGIC. Large illustrated catalog of tricks you can do, 25c. Holden, 222 W. 42nd St, N. Y. MASTER MAGIC—Joker’s novelties. Catalogue free. Chelsea Magic Com- pany, 1136-M Fox Street, New York City. NOVELTY motion picture and illus- trated magic catalog 10c. Macardill Co. Dept. A, 1369 Herschell St., New York. SEND 25c for six big magical catalogs, bargain lists and trick book. Over 2000 items. Gilmagico, Morgan Park, Chi- cago, Ill. MAGIC GOODS MAGIC catalogue. Wonderful knock- out card trick. 10c. Singer, 444 Han- cock, Wisconsin. MALE HELP WANTED FOREST JOBS easily available, $200 month. Cabin. Hunt, trap, patrol. Get details immediately. Rayson Service, K-32, Denver, Colorado. MISCELLANEOUS EFFECTIVE sales letters $3.00; ads $1.00; 12, $10.00. “Superad” Service, Box 250, Ithaca, N. Y. HELP organize a coast to coast snap- shot exchanging club. Stamp; 62 Bid- well, Jersey City, N. J. FREE Homesteads — some improved. Forfeited; 18 states; maps, “700 facts,” 40c. MY-33, Modern Mechanix and Inventions, Minneapolis, Minn. MOTORCYCLES MOTORCYCLES, $25 up; used tires, $2.50, new, $5; engines for boats, pumps, aeroplanes, ice sleds, motor- cycles, $10 to $75: wheels for midget cars, aeroplanes, $1 up; frames, forks, cylinders, handle bars, saddles, 3-speed assemblies, crank cases, generators, mag- netos, and other parts. Bicycles, $9.50, tires 70c; motor bicycles $55. Cheapest and oldest house in U. S. A. Send 39c for catalogue, Price Cutter Deninger, Rochester, N. Y. SEND 15c for illustrated used Motor- cycle catalog. Large stock. Bargains. Indian parts. Accessories. Indian Mo- torcycle Sales, Kansas City, Mo. MODELS YOUR Ideas developed into practical, working model, 30 years successful 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. cinnati, Ohio. MODEL ENGINES “REAL” Motor, gasoline, for model airplanes, boats, 34°x34", % h. p., weight 1 1b., 3200 r.p.m. Catalog “Rea! Boats,” motors, fittings, 20c coin. P. Loutrel, 96 McDonough St., Brooklyn, New York. MODEL Gasoline and Compressed Air Motors, 14 h.p. for model boats and air- planes, Illustrated catalogue 10c. Min- iature Aircraft Corp., 83 Low Terrace, New Brighton, New York. MOVIE CAMERAS MOVIE CAMERAS, projectors, films, large library, catalog, free membership. Mogull Bros., 1944-G, Boston Road, N.Y.C. in- PATENTS PATENTS—Small ideas large commercial possibilities. immediately for information on how to roceed and “Record of Invention” orm. Delays are dangerous in patent matters. Clarence A. O’Brien, 28-S Adams Building, Washington, D. C. PATENTS—Reasonable terms. Book and advice free. L. F. Randolph, Dept. 341, Washington, D. C. “PATENT Pointers for Inventors,” 10c. Mechanics handbook 25c. Jobn Smith Press, 792 Distel Avenue, De- troit, Michigan. LET us introduce your patent to thou- sands of people who have money to buy or develop them, National Listing Ser- vice, 5213 Litchfield Street, Philadel- phia, Pennsylvania. INVENTIONS, Ideas Copyrights Improved, Revised, Mar- keted at once. I. R. Vier Co., 411 Clunie Building, San Francisco, California. PATENT ATTORNEYS PATENTS—Procured, any country, reasonable, Ramsay Co’y (Registered), 273 Bank St., Ottawa, Canada. PATENT Your invention now. Little ideas may have big commercial_possi- bilities. Send for free book, “How to Obtain a Patent,” and free “Record of Invention Blank,” In business since 1898, specializing in patent matters, we have successfully served thousands of inventors. Delays are dangerous in patent matters—act at once and protect your idea, Reasonable fees. Deferred payments. Write us today. Victor J. Evans & Co., 647-H Victor Building, Washington, D. C. -> o C || a + Thank You for Mentioning Modern Mechanix and Inventions for August When Writing to Advertisers 21

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CLASSIFIED ADS PATENT ATTORNEYS INVENT something! New discoveries have cured previous depressions. Un- atented ideas can be sold. I tell you ow and help you make the sale. Free articulars. Write W. T. Greene, 958 arrister Building, Washington, D. C. ae aa ee ee t PERSONAL “PALMISTRY at a Glance.” 125 pages, Tells all. Over 1000 markings explained. Instructs you in reading palms. $1 postpaid. Chiromant, 1539 West 7th, Los Angeles. 25 LESSONS in Hypnotism, $1.00. J. Tillberg, 140 Eighth Ave., New York City. RAZOR BLADES TO INTRODUCE Norwalk. Blue Blades (any Gillette type), package of five for 25¢ (coin). Distributor, Box 3422, San Francisco. RADIO GUARANTEED “Pocket Radio”, $2.00. Catalogue, 10c. Neil Tasker, Shamokin, Pennsylvania. SHORT WAVE Sets, Kits, Supplies. Wholesale catalog 10c. Federal Radio & Telegraph Co., 4222 Clifford Road, Cincinnati. REAL ESTATE OZARKS—Five acres timbered river (Continued from page 21) ROOTS AND HERBS JUST OUT! World’s greatest ‘Herb Almanac.” Beautifully illustrated. in natural colors. Contains over 500 old- fashioned herb medicine recipes and In- dian secrets for home use. 10c (coin) postpaid. Worth dollars! Bontanics, 145 W. 112th St., Chicago. SECRET SERVICE SECRET Service Methods. Particulars free. Excellent opportunity. Experience unnecessary. rite, Wagner, 2640-Y, Broadway, N. Y. SONGS, POEMS, WRITERS SONG writers wanted now. 50-50 plan. ie we PHOTO FINISHING frontage, DEVELOPING and Printing roll films, 25c; reprints, 3c each; beautiful 8x10 enlargements, 25c. Cardinal Photo Lab- oratories, Summit, N. J. PRINTING PRINTED bond envelopes, (814x11) letterheads; 85c per 1,000; Two color printing; samples 10c. Midwestern, 3 West Ohio, Chicago, Kans. boating, shooting—$100, $5.00 monthly. 1 bard, 224 Grossman Bldg., Kansas City, fishing, Classified Ads Get Re- sults—only 10c. a word pearling, Indiana Song Bureau, Salem, Indiana. Tbe |e eae RE ee Ge, aa MAKE MONEY writing songs. Free booklet. Stan Tucker, 1619-B Broad- way, New York. TRAILERS CATALOGUE of camp trailer plans now available, Enclose 10c to cover mailing cost. Toellen Trailer Service, Box 25, College Park Sta., Detroit, Mich, Getting More Light on the Moon (Continued from page 61) R. W. Wood, of Johns Hopkins, who has photo- graphed portions of the moon with color screens and plates sensitive to different regions of the spectrum. Comparison of the photographs with those made of sulphur-coated rock in the labora- tory shows almost certainly that there are deposits of sulphur on the moon. As sulphur is often found in the materials ejected from volcanoes, Prof. Wood’s discovery supports the old idea that the thousands of so- called craters on the moon are the vents of extinct volcanoes, but there are some serious objections to this idea and a different one is now favored by many authorities. The moon is undoubtedly hit by millions of meteorites every day, and some of these bodies are cer- tainly big enough to make conspicuous scars on its surface. Even the earth, though well pro- tected by its atmosphere, is now known to be scarred in many places by meteoric bombard- ment as witness the long-famous Meteor Crater in Arizona. Bullets have been fired into a little leaden moon by some investigators and craters have been produced very similar in appearance to those seen in lunar photographs. The terrific impact of a big meteorite, traveling at enormous speed, would produce enough heat to melt and volatilize the rocky surface of the moon over a large area. Here we have a possible explanation of the long white “rays” that extend for hundreds of miles from some of the larger craters and have caused more controversy among astronomers than any other feature of the moon’s surface. These rays may have been formed by the splash- ing of molten rock when an exceptionally large meteorite hit the moon. One of the first uses made of the Mount Wil- son telescope already mentioned—the largest in the world—was to take a series of photographs of the moon, which revealed hundreds of craters and other details previously unknown. At the same institution a remarkable campaign of lunar mapping has now been undertaken by a com- mittee of the Carnegie Institution. The new system of mapping employed at Mount Wilson consists of taking numerous sec- tional photographs of the moon, which are pro- jected by means of lantern-slides and concave mirrors upon the surface of a small globe coated with magnesia powder, as illustrated. A All objects appear on the globe in their true shapes and positions and photographs made from the illuminated globe give an accurate map. A contour map of the moon is also being made by a process of stereoscopic photography similar to that used in mapping the earth from an air- plane. It is, of course, well known that the lunar attraction, combined with that of the sun, causes tides in the ocean and also in the solid crust of the earth, and some seismologists believe that it plays a part in causing earthquakes. Many of the other effects that the moon has been alleged to exercise upon the earth, including the control of weather, are mere “moonshine.” One remarkable and mysterious influence, however, has recently come to light. Studies by H. Munro Fox and other biologists show that a number of living organisms, particularly marine animals, exhibit a lunar periodicity in repro- duction. Thus a species of sea urchin living in the Red Sea always spawns at full moon, and the palolo worm, living in Pacific coral reefs, spawns once a year exactly at the last quarter of the October moon. This curious coincidence of reproductive ac- tivity with the moon’s phases appears to be well established but has not been satisfactorily explained. Perhaps, after all, there is something in the old idea that moonlight stimulates human love-making! 22. Thank You for Mentioning Modern Mechanix and Inventions for August When Writing to Advertisers

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Finding Cleopatra’s Fabled Emeralds (Continued from page 65) the mysterious history of the “flames of the devils.” The Tuaregs explained to me that sometimes at night, while lighting their campfires, tremen- dous flames surged up. These strange fires caused consternation among these primitive chil- dren of the desert. They did not realize the truth of the matter, namely, that no doubt sparks from their fires sometimes light up petroleum wells, which situation is common enough in Penn- sylvania. Oil in the Sahara? I have no doubt any more about that. At some geological epoch centuries ago the Sahara was a part of a vast, interior sea, where layer after layer of petrified fish gradually accu- mulated, forming itself into oil, just as was the case in the great American petroleum regions. What a treasure to contemplate if some great nation or business concern would investigate the petroleum situation throughout the vast Sahara wastes. But to return to our expedition. After many more weary days of march in the desert’s scorch- ing sun (just how many days is hard to say since we lost track of time) we reached our big objec- tive—Garama, once the ancient capital of the Garamantes, whose kingdom was among the Sahara’s most powerful, in early times. I humbly believe that this discovery remains unique in the records of ancient finds in Africa. We had found the greatest Paleolithic walled city ever known to modern science—with walls 30 feet high and eight feet across, surrounding an area of three square miles. Very thoroughly, considering our limited time and funds, we explored this ancient city, discov- ering countless grottos whose statuary will no doubt throw important light on the problem of man’s origin in North Africa besides thousands of practical remains of a mysterious and novel civilization—such as carved stone implements and curiously wrought flint artifacts. Our discoveries in the city were a prelude to the discovery of the gems of Cleopatra in the subterranean chamber in the hill near by. After my find the expedition continued its excavations in the city of Garama and brought to light hun- dreds of relics of immense value to archaeology. Our work finished here, my next objective was to return to civilization and raise enough funds to explore the fascinating region further. True it is that once away from Africa, I long to return as soon as possible to the desert land of gold and sand and ruin. WANT TO BUILD THINGS? Send for Modern Mechanix and Inven- tions’ FREE Blueprint Book.—Lists plans available for boats, airplanes, trailers, mo- tors, radios, jig saws, etc. 529 S. Seventh St., Minneapolis, Minn. we Working Part Time? —or at Reduced Salary? Arr you tired of taking wage cuts—sick of part time work? Are you worried about further cuts—and questioning about ever getting back to the old salary? Listen, then, to a few frank words on the situation that is facing you today. If you take advantage of it— you can better safeguard yourself against slipping further and put yourself in line for better things in the future. But if you let the situation take advantage of you— teon you are in danger of losing even what you have eft. You can't skimp along on the present basis much longer. You don’t dare let go—too many men are hunting jobs, eager to change places with you. And you can’t depend on returning prosperity to bring back to you pay raises and promotion—that, after all, is your individual battle. When you can’t stand still, or afford to fall back, there is only one line of action open to you—go ahead. And that line of action will require every drop of fighting blood—to win back those salary cuts and a bigger, better jobt YES—Pay Raises—TODAY You can do it. Some men and women have already proved the way for you. Now right in the midst of the depression—they are reporting salaries kept up—even in some cases promotions and pay raises. Don't take our word for it—read some of their most recent letters in our new booklet, ‘100 Pay Raises Today.” They haven't all been luckier than you—they haven't ali been smarter—they really haven't worked harder. Their employers have kept up their salaries or even paid them more because they knew how to get results. Through LaSalle training they gained the new busi- ness technique needed to produce results today—and through the LaSalle Success-Building Plan, they learned to make that technique worth more to their employers and to themselves. ASK Us for the PROOF The same opportunity is before you now. All you need is the courage to start and the persistence to keep going—LaSalle will do the rest. If you are of average ability—but ready to study and think—LaSalle will help you qualify for what you want and need. And the terms are so low you can fit the payments into your present-day budget. After all, you have thought of LaSalle training be- fore—now you have plenty of time for it—so why not start it immediately? At least, find out how this proved plan is bringing prosperity back to others— gamble a postage stamp against knowledge that may banish your business worries forever. Simply mark and mail the coupon below. LaSalle Extension University 1908-1933—Twenty-five years of service to over 800,000 members LASALLE EXTENSION UNIVERSITY Dept. 8493-R - CHICAGO I'd like to see that booklet, 100 Pay Raises,” and have the facts about your training planthatyou think will help me to larger success in the business field I j have checked below. O Business Management OLaw DModern Salesmanship O Foremanship OTraffic Management O Industrial Management OC Office Management OHigher Accountancy Name... cece taupa kees HELEN nei DRS EEA oe Position ANAE ele sieie et Cae. Oa sae Betis Viele ete ° Addregs. ccc cece eee ete n ere e reer enae ove Thank You for Mentioning Modern Mechanix and Inventions for August When Writing to Advertisers

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HAENEL “100 SHOT” ee $ 4-95 Latest Model 1933 Haenel repeating pistol. Sturdy, massive construction, easy cocking lever, 100 shot magazine. Accurate for target. Powerful for small game. Blue or Nickel finish, shoots B. B. steel shot. Weight 18 oz. Price with 500 i shots Free - $4.95—$2.00 deposit on C.0.D. Free Catalog—Colts, S.GW. Rifles, Binoculars, etc, HUDSON SPORTING GOODS COMPANY M-52 Warren Street New York Clty, N Sell Your SNAPSHOTS Magazines, Asg papers and Advertisers’ clamoring if you learn h how to go ab for new pictures. They’Il bay them from Y: ake your camera pay yon Eo good Son D thine or full time. how others dọ it. Send f: **Cashing in on Your Camera. Rea her right while you learn how to take Ore kind of newsy,human-interest pictures that pul lications want== and how and where to sell them with help of our uplimi Mar! keting Service. Mail card or letter. Addres FREE BOOK: UNIVERSAL PHOTOGRAPHERS, Inc. we Dept. 399. 10 West 33rd Street, New York HIGH BLOOD PRESSURE QUICK RELIEF, OR YOU ONLY PAY . WHEN SATISFIED If you suffer from High Blood Pressure, dizziness, ringing in the cars, can’t sleep at night, feel weak and shaky, bad taste, nervous, ìf your heart pounds and you fear-a paralytic stroke, to demonstrate the value of my successful prescription I will have sent to you, postpaid, a regular $1 treatment on absolutely FREE TRIAL. While it is a non-specific, many cases report remarkably quick relief; often symptoms diminish and quiet normal sleep returns within 3 days. Does not contain any salts, physics, opiates or dope of any kind. Absolutely harmless. You can continue with any treatment you are now taking, as it can not conflict. Perfectly safe with any diet schedule. PAY NOTHING UNLESS GREATLY IMPROVED. Then send me $1. If not your report cancels the charge. Write to Dr. H. L. Hayes, 3022 Coates House, Kansan City, Mo. The 1933 FLYING MANUAL is now ready for YOU! e Crammed with plans for light monoplanes, seaplanes, aviation motors and countless other items of vital interest to the light air- plane enthusiast. Here’s a sample of some of the high spots in the Edition: out it! Ma PIETENPOL SKY SCOUT—Plans for this one- ‘place monoplane powered by Model T Ford motor. CORBEN CABIN MONOPLANE-—Also shown as open cockpit job. Cabin plane costs only $220 for materials, less motor! HICKMAN BABY SEAPLANE—A one-place twin-pontoon biplane seaplane. GERE BIPLANE—Neat ship for Ford or Chevrolet power plant, resembling an army pursuit job—and many others. PRICE 50 CENTS Tf your news dealer cannot supply you, send 50 cents to Fawcett Publications, Inc., 529 S. Seventh St., Minneapolis, Minn., and a copy of the 1933 Flying Manual will be mailed to you at once. - A Telescope for “Star Gazing” (Conlinued from page 117) tamination with the previous abrasives. This is important! Polishing is done on a pitch tool or “pitch lap.” This is prepared as fóllows: Place the mirror and tool in a dish of water and gradually heat to a temperature of about 125 degrees. Meanwhile melt your pitch in another receptacle but do not let it come to a boil. Pour a bit of the pitch on a scrap of wood and let it cool at which stage if you can just crease it with your thumb nail it is of the proper ‘hardness; if too soft continue heating until some of its low temperature frac- tions are evaporated and test again; if too hard, add a few drops of turpentine but remove it from all proximity to the flame when adding turpen- tine! When the pitch is of the desired consistency remove the tool from the warm water and place it back in its working position between the cleats and pour pitch on the convex surface of the tool. Next, having previously mixed some rouge in water to a consistency of cream, take the mirror from the warm water, paint its concave surface with the rouge and press it firmly and vertically down on the pitch-covered tool; work it about very slightly, Just enough to allow the surface of the pitch to conform to the shape of the mirror —this condition can be observed through the upper surface of the mirror—then put the mirror back in the lukewarm water. The surface of the pitch-lap must now be given polishing facets. This is done with a hack saw with the result as illustrated above Fig. 2. The facets do the polishing and the grooves provide ventilation so cut the grooves deep and V-shaped. The facets are about an inch square and it is imperative that the grooves be so laid out on the surface of the pitch that no one facet, or no intersection of grooves, occupies the center of the tool—therefore the “design” is something less than an inch off- center. Next, put the pitch-lap back in the warm water until it has attained the same temperature as the mirror, then put the pitch-lap back in its working position, paint the surface of the mirror with the rouge and place it back on the facets of the pitch-lap and weight it down to an extent of about twenty pounds and let remain until the pitch is cool. This will insure that the facets of the lap have been brought back into conformity with the surface of the mirror in the event they were disturbed by the grooving with the hack- saw. Proceed now with the polishing, using the same motions as in grinding. To produce a curved surface most mathemati- cally and actually precise for a telescope mirror it has to be depressed a few millionths of an inch in its central area which changes the surface from spherical to paraboloidal; necessary because a parabolic curve is the only mirror surface which will bring all parallel light rays to a single and accurate focal point. This is accomplished by wear- ing away the center more than the edge by using. the longer stroke in the final polishing. Needless to say it is useless to hope to work within such infinitely fine tolerances unless one has means of testing the surface of the mirror for variations as fine as two or three millionths of an inch. 3 ee -24 Thank You for Mentioning Modern Mechanix and Inventions for August When Writing to Advertisers

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A Telescope for ‘Star Gazing” One “grab-bag” combination of such apparatus is clearly illustrated near Fig. 6. The test is known as the Foucault Shadow-test and the simple requi- sites for it are as follows: A light source consist- ing of a frosted or opal light bulb; a tin can shield for the light and suitably supported around the bulb and having a 44-inch or so hole punched in it opposite the center of the bulb; over this hole is clipped or fastened a piece of tinfoil with a very fine needle hole puncture; so much for the light source. The other accessory is a knife-edge oe blade supported as illustrated—and that’s all! The condition of the mirror and the exact shape of its curve at various times during the polishing and the final parabolizing is found very accurately by this Foucault knife-edge or shadow test. The schematic and optical arrangement for conducting this test is depicted simply in Fig. 6. The mirror is supported on edge (after being thoroughly washed of all rouge) and at a distance from it equal to its center of curvature or spherical radius the light source is positioned on a level with the cen- ter of the mirror and an inch to the right of its projected center. The razor blade is at the same level and is manipulated just to the left of the mirror’s axial center. The operator’s position in relation to the apparatus in conducting the shadow test is illustrated just above. The light, shining through the pin-hole placed near the center of the sphere of which the sur- face of the mirror is a small part, is reflected back to a point of light close to the pin-hole source. If the eye is placed at this point the mirror will appear as a brightly illuminated disk. Now the razor blade is slid into the line of sight from the left and cuts across the converging bundle of light rays at a point just in front of the eye. If the razor blade is cutting across the reflected rays inside the center of curvature, or “R”, Fig. 6, it will cause a shadow to move across the face of the mirror in the same direction as the knife edge is moved. If the reflected rays are cut outside the center of curvature, the shadow appears to move across the mirror opposite to the motion of the razor edge. From these two observations the true center of curvature or exact “R” may be found and measured. If the surface were per- fectly spherical, the mirror would appear to darken uniformly when the rays are cut at the exact center. Since the curve is not absolutely exact, faint shadows will appear on it, indicating certain areas of the surface a little plus or a little minus from a true sphere. By careful polishing, these irregularities of the surface can be con- trolled, so that the curve may first be made as spherical as possible and then deepened just per- ceptibly in the center. The end result, a slightly parabolice curve is attained when the shadow- graph shows an apparently depressed center and edge, resembling in shape the well known “life- saver” or a flat dough-nut. Silvering The glass, which is now ready for silvering, must first be thoroughly cleaned. This process of depositing a thin film of silver on glass is such a delicate one that a minute amount of grease or (Continued on page 27) Qik In 1934 We Hope to Place 500 Draftsmen ahd T T Every Draftsman in this room—or in any other Draft- ing room—started by prac- ticing on simple problems with simple instruments like this Test Outfit. Here Is Your Chance Drafting is fascinating work—pays well—offers steady employment under ideal conditions—leads to many of the biggest jobs in engineering, building, and manufacturing. . Are you dissatisfled with your present prospects— undecided what line to follow? Then why not give Drafting a tryout? its combination of head work and manual skill makes it a real Job. 30 Days’ Free Instruction If you want to find out how fascinating Drafting really is—how easily you can learn it at home in spare time—the quickest, surest way is to try It! Send us 50 cents for a Test Outfit, and we'll give you 30 days’ free instruction in actual Drafting prac- tice. That will show you definitely whether you would like a Draftsman’s job. The Test Outfit includes 2 Drafting Lessons and—Pencil Compass— 12-inch Rule—Pencil—iraser—0 Sheets Drawing Paper—Thumb 'Tacks—Heavy Cardboard Drawing Board—all that you need to handle these beginning problems. If you can do satisfactory work with these simple instruments, you can soon learn to handle bigger and More difficult jobs wilh a standard oulfit. Get Ready for Better Times The vast public works projected by the U. S. Gov- ernment—the general pick-up in manufacturing lines—the revival of building—will require thousands of Draftsmen to develop plans, design equipment, and prepare the working drawings that ‘“‘boss” all engineering and industrial activities. By 1934, this country will be well on its way back to normal. But if you’re not prepared for a worth- while job now, you can’t expect to get ready in less than a year. So we urge you to make this quick practical test at once, Then if you find you like Drafting, you will have ample time to prepare for a good job in 1934, With the Test Outfit we'll send you List of Local Students and Graduates, who will be glad to tell you personally of their experience in gelling money-making training by home study. Also ‘‘Selective Employment Service,” explaining how we have helped hundreds of advanced students and graduates to find good jobs. Dept. DC-23, Drexel Ave. at 58th St., Chicago I accept your offer of 30 days’ free Drafting instruction (without obligation), and enclose 50 cents for Test Outfit. 1o- Thank You for Mentioning Modern Mechanix and Inventions. for August When Writing to Advertisers 25

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j Build your boat now for that summer launching | fever that | 20 Boats” will give you endless hours of fun. hits you every year. ‘How to Build Build Your Own Boat! 26 Here’s the Book for ALL BOAT BUGS!... PARTIAL LIST OF CONTENTS: Plans for Gannet, Ford powered cruiser—Dorothy, 24-foot sea- going motorboat—Buddy, a Rab! tabloid cruiser—Mayfay, wonderful little raised deck crulsor—Wanderboat, a 16-foot outboarder—All Sorts, a 10-foot combination ice, sail and motor- boat—Seram, sensational performing Ford A runabout—and thirteen other designs for all kinds of boats. Send for this new 144 page book ... “How To Build 20 Boats” JUST OUT! For that fireside or springtime boat fever there is no richer treat than this collection of famous boat designs—some of them hitherto unpublished. All have been test- ed in actual use; there are no “duds”. Get your copy of this eagerly sought file of designs, sharpen up that pencil, grip that hammer and satisfy that old urge to build your own boat, On Sale EVERYWHERE DOC If your local newsdeal- er cannot supply you, send 50c stamps or coin to FAWCETT PUBLICATIONS, Ine. 529 SOUTH 7TH STREET MINNEAPOLIS, MINNESOTA Thank You for Mentioning Modern Mechanix and Inventions for August When Writing to Advertisers

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A Telescope for ‘Star Gazing” (Continued from page 25) foreign matter may greatly mar the finish. The surface is cleaned with alcohol, rubbed vigorously with cotton, and washed with strong acid followed by strong alkali, and finally thoroughly rinsed with distilled water. An alkaline solution of silver nitrate, contain- ing just enough ammonia to form the silver- ammonia complex, is reduced by simple sugars to metallic silver which deposits on the glass as a very thin film. A strip of paraffined paper may be wrapped around the edge of the mirror to form a wall or dam, and the silvering solution poured directly into this. The silver will deposit in a few minutes, depending on the temperature. As soon as the process is completed the mirror is washed, for the surface will appear bleached if allowed to stay under the silvering solution too long. The film of silver should be protected with a transparent film of diluted lacquer. Assembly and Mounting The most frequently described and cheapest for amateur construction invariably are mounted on wood backbone assemblies and consequently are far from rigid and tend to vibrate when touched or when in a slight breeze. The design presented herewith for Modern Mechanix and Inventions readers gets away from such ailments in a fool- proof and positive manner, i.e., by employing pipe fittings for the mounting of the telescope. The complete lay-out was shown in part 1, last month, and is quite self-explanatory. The only critical dimension involved is the one labeled: 50” minus the * * etc. * *. This needs studying because of the varying values which may occur in the dimension “X” in the same diagram, as no two builders would get the 8-inch octagonal mirror cell positioned exactly the same distance from the 14-inch pipe forming the main longitudinal member of the telescope. The side diagram gives the remaining details of mounting and assembling. The mirror is backed by a disk of sponge-rubber cut from a kitchen “kneeling-pad” procurable in any dime store; this in connection with the three wing-nuts allows the mirror to be centered exactly on the little 45- degree diagonal mirror at the other end of the tube. The one-inch magnifying lens used for the eye-piece is mounted as shown in detail. A piece of wood stock is fashioned as shown for holding the eye-piece and the brass brackets which in turn support the smaller block of wood holding the little flat mirror at a 45-degree diagonal. The eye-piece block proper is made from a 14-inch square stock and the most important and original feature of this design is the end of this block which is turned down to a dimension which allows it to fit into the end of a 114-inch pipe. The final: alignment of the optical system is attained by removing the eye-piece lens and sighting through the eye-piece lens hole at the 45-degree diagonal mirror. In that little mirror will be seen a reflection of the large mirror and in the large mirror an image of the small one. This latter image should be in the center of the large mirror; if it is not the large mirror can be cor- rectly adjusted by means of the three wing-nuts around the cell. 17M STILL MAKING i E pR “Irs not as much as I have made, that’s true — but business has been going through a pretty tough spill, Things look brighter now, it’s my hunch better days will soon be here. “Sometimes I wonder where I would have been in these times if I had not studied that International Correspondence Schools Course a few years ago, I give that home-study course credit for all the raises I’ve had. It’s the real reason I have a job and a regular income now. If I had not taken it, the chances are I’d be one of the unemployed today.” When promotions come, they are going to the men who are prepared for them! Why not begin preparing yourself today? Make an in- vestment in yourself and in your future—an J. C. S. home-study course is the first step. Mail the coupon for complete information, It’s free, INTERNATIONAL CORRESPONDENCE SCHOOLS “The Universal University” Box 2321-T, Scranton, Penna. Without cost or obligation, please send me @ copy of your booklet, “Who Wins and Why,” and full particulars about the subject before which I hava marked X: TECHNICAL AND INDUSTRIAL COURSES O Architect O Automobile Mechanic a D Architectural Draftaman DU Plumbing D Steam Fitting OD Building Estimating DO Heating D Ventilation O Wood Millworking O Sheet Metal Worker UO Contractor and Builder O Steam Engineer O Structural Draftsman O Steam Electric Engineer O Structural Engineer O Civil Engineer 7 OD Electric Wiring D Surveying and Mapping O Electrical Engineer O Refrigeration | O Electric Lighting O R. R. Locomotives O Welding, Electric and Gas OR. R. Section Foreman O Reading Shop Blueprints OR. R. Bridge and Building Foreman D Telegraph Engineer D Air Brakes | ] Train Operation D Telephone Work D Highway Engineering UO Mechanical Engineer O Chemistry O Pharmacy O Mechanical Dreftaman O Coel Mining Engineer D Machinist O Toolmaker D Navigation O Boilermaker O Patternmaker O Textile Overseer or Supt. O Pipefitter O Tinsmith DO Cotton Manufacturing O Bridge Engineer Woolen Manufacturing — | UO Bridge and Building Foreman D Agriculture O Fruit Growing O Gas Énginea O Diesel Engines O Poultry Farming D Radio D Aviation Engines O Merine Engineer BUSINESS TRAINING COURSES O Business Management O Business Correspondence O Offce Management O Lettering Show Carde D Industrial Management D Stenography and Typing DO Pereonnel Management O Commercial U Traffic Management D Civil Service O Accountancy and D Mail Carrier C. P. A. Coaching O Railway Mail Clerk D Bookkeeping .. O Grado School Subjecta O Secretarial Work [O Spanish O High School Subjecta © Cost Accountant [French ( College Preparatory D Signs 0 Salesmanship (O) Advertising L Illustrating D Wallpaper Decorating jaleamane! O Cartooning O Lumber Dealer „Ago. Occupation... sessoss-neisseroscsvausevsreeccenesorarensesereosevreressisissstertrtereeras rertaoa If you reside in Canada, send this coupon to the Internattonal Core respondence Schools Canadian, Limited, Montreal, Canada itil) s+ Thank You for Mentioning Modern Mechanisz. and Inventions for August When Writing to Advertisers 27

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O When Doors Won’t Open Faucets Drip Windows Stick —Fix Them Yourself In these times when pennies count, many home owners put up with the inconven- ience of household devices which don’t operate at full efficiency because they hesitate to run up a big bill with the repair man. Wise householders make their own small repairs—and big ones, too—enjoying the full efficiency of their homes and keeping dollars in their pock- ets to spend for other things. Any handy man will find it no trick at all to re- ‘pair plumbing, plaster, concrete, electric equipment, ete., following the explicit directions in the Handy Man’s Home Manual This book, just off the press, answers just the questions you would ask of an expert if he stood at your side to advise you on your repair job. It is, in fact, the work of many experts, specialists in their fields. The numerous photographs, explicit drawings and clear, easily un- derstandable text reduce the problem of household repairs to such simple terms that no man who can handle a hammer and saw need be fearful of his ability. Now on Sale at All Newsstands PRICE 50c If your news dealer is sold out, send 50 cents to Fawcett Publica- tions, Inc., 529 South Seventh Street, Min- neapolis, Minn., and a copy of the Handy Man's Home Manual will be sent to you at once. . ~ Plans for a Dirt Track Racer (Continued from page 108) been mounted in the frame with the transmission in position and for this reason the overall length is not indicated in the drawing. Standard Modél T axle shafts are not strong enough to stand the tremendous buffeting given these units when the racing car is driven at high speed. For this reason it is necessary to make use of smaller roller bearings in the housing and heavier shafts. These may be secured from the racing car parts supply house or the Model T truck shafts may be used and turned down to fit the bearings, using the smaller rollers. Some of the speed merchants are making use of the late model Chevrolet rear axles. The hubs used in this design are Dayton wire wheel, provided with taper bore to fit the axle shafts used. The wheels are 17x5.50, giving a larger tire with better traction at the rear. The brakes used on this job are external con- tracting, fitted over the Model T brake drums and being controlled by means of a hand lever con- nected to a cross shaft, receiving at its outer ends the flexible cable which runs to and controls the contraction of the brake band and the drum. For cars of this type it is necessary to secure a racing type steering gear. This is illustrated in the several figures, the one shown being of Ross manufacture. The steering wheel recom- mended is a flexible spoke wheel. It may be secured from the manufacturer. Sometimes these are fashioned from a circular saw steel, blank. These may be worked out in the home shop, al- though it is quite a chore. If this work is under- taken the blank or spider should be provided with a rim and hub, the hub to fit the shaft of the steering gear and the rim being of a size de- signed to come just within the cowl of the body. Note that the steering gear is mounted on several brackets which are made from angle iron. The leg of the angle iron is turned out and bolted to the frame side member, other brackets (usually furnished with the gear) being bolted to the verti- cal section of the bracket. The Pitman arm and drag link are usually secured with the steering gear, although it may be necessary to make up the latter owing to the fact that the location of the steering gear affects the length of this. Although hydraulic shock absorbers may be used with success on the dirt track, most of the boys still hold to the Hartford type. These are set up quite tight so that there is very little action of the springs. The best practice is to mount the outer ends of the shock absorber arms as near the road wheel position as possible. This is claimed to be better practice than the method illustrated in the photos of the car shown. In the case of the car shown the transmission is a Model A, in which the second speed cluster is special, having a higher ratio. By means of this higher ratio it is possible to speed up the car quite rapidly in second gear, thus effecting a rapid pick-up and get-away. The clutch used is a mul- tiple disk Model A Ford, as is also the flywheel which has. been turned down to approximately half its original weight. Inasmuch as the engine used in this car is a Fronty Ford, which is de- signed around the Model T block, it is. necessary Re 28 Thank You for Mentioning Modern Mechanix-and Inventions for August When Writing to Advertisers

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Plans for a Dirt Track Racer to have a special bell housing to fit the Model T block and the Model A transmission, assembling and aligning them thereto. : It is not the purpose of this article to go into the construction of a race car power plant. The reason for this is that many Model A or Model T conversions can be mounted in a frame of this type. Many circumstances direct the building of an engine and individual preferences are not always the same. As a matter of fact, this par- ticular car frame has had mounted within it sev- eral Model T conversions, the one shown being a moter driven for many laps by Gus Schrader and purchased from him last season by Don Campbell. The radiator, which is approximately 13 inches wide and 25 inches high, is provided with a 4-inch core and is manufactured by the Peters Cartridge Co. The shell is approximately 13 by 26 inches and is the product of Dryer of Indianapolis. Cir- culation of the water is by pump. Four water out- lets are provided on the top of the engine and four inlets on the side. The manifold pipe is so baffled on the side of the engine as to give equal distribution, of the cooling water to the cylinders. The engine temperature is indicated by a Boyce indicator, mounted on the steering column. One feature which occasions all beginners in this field much trouble is the layout and con- struction of the body. It is almost useless to give minute dimensions for body work. This also holds for minute dimensions of the frame or chassis. The all-steel body illustrated is approximately 19 inches in width at the central portion. The welded gasoline tank is fitted within the body and supported by the body frame. The method of framing up the body is shown in several of the pictures. The cowl and deck sections are designed to slide over the frame sections support- ing them and are anchored to the car frame with 5/16 inch cap screws. The general design of the steel frame of the body is shown. It will be noted here that 1-inch angle iron is formed for the “U” members, one of which receives the fire wall and supports the rear of the hood, the other receives the instru- ment panel and supports the steering gear. It will be noted that there are two braces between these two “U” members, one being a horizontal brace and the other one an angular brace, designed to take thrust and stiffen it. The body metal is de- signed in two sections (hood and deck) so that they may be repaired and easily assembled. When building the body first lay out the 14”x 1%4,"x1)4” angle iron sills and bend them to the form of the body plan. This is determined by dimensions of the sections A, B, C, D and F at their open ends, which are later welded to the sills. Next make up and erect curved sections A, B, C and D and the square section F. Next make up and run in sections E, H and also section G, which is made from %4"x1" flat steel: All other sections are made from 1%"x1"x1” angle iron. All angular braces and horizontal rails are made from 14’’x1"’x1" angle. INVENTORS PROTECTION AS POWERFUL AS PATENTS VERY SMALL COST Why pay $125.00 to $500.00 for a patent and wait up to two years for action from the Patent Office when this cheap, sure-fire legal system cuts the cests to a week’s pocket money and gives you the same right to sue and protect yourself that a patent gives? Manufacturers buy IDPAS, not fancy look- ing patent papers, Remember that a patent is NO GUAR- ANTEE that an idea is good. Good unpatented ideas properly Protected sell even faster than patented ideas at times because action is quick. New-found weallh may be yours tomorrow. DON’T WAIT 6 MONTHS TO 2 YEARS FOR PATENT OFFICE The Patent Office is months behind in its work. No waiting necessary with this new system. Jt is fast, sure and binding. $100,000,000 waiting for new ideas for our Technocracy. Never before hag the American and Canadian inventor been faced with such opportunity. Manufacturers are begging for new inyentlens but they must have them QUICK. QUICK, SURE LEGAL ACTION WITHIN TWO WEEKS’ TIME Inventors properly exercising ALL of their common law rights together with my new legal system may laugh at patents. Indeed they can protect 20 ideas for the cost of one patent. Think of it; twenty chances to win for the cost of a single patent! But speed and actlon is necessary. i . $ Brings Full Complete Details |} There 1s no other money to me. The rest simply depends upon how fast # YOU ACT. This may mean the turn- ing poinl of your whole life. Here is | your chance, | RAYMOND F. YATES Room 435 : : | BrisbaneBldg., Buffalo, N.Y. 39,000 Inventors Have i Come to Me for Aid C-------------= Raymond F, Yates | Room 435, Brisbane Bldg., Buffalo, N. Y. | Dear Mr:. Yates: Please send me this new Triple-Protection Plan for Inventions and tell me how I can get my invention SAFELY in the hands of manufacturers within a month and at 1/10th to 1/20th the usual cost. I am enclosing. $1.00. l (Please PRINT your name and:address) l The cowl section and the deck section are | NAMB... ieee eee ee cee cnet cate e eens ee tees toate ee ken eee we I joined at a point approximately even with the | | STREET NO. .......... cece eee cc tee ee eteeeeees | (Continued on page 125) Bocmty. nee eee ee ees STATE. ..........: i wo oee Thank You for Mentioning Modern Mechanix and Inventions for August When Writing to Advertisers 9

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. Jumps fiom plane mile se Falls 144 m.p-h. Speed slows f to120 mph. f in denser atmosphere J Opens chute at S500ft ean aan Gat EEE OE OO eS Si World’s record for a delayed- opening parachute jump now rests with John Tranum, English jumper. He leaped from a ship more than four miles high, fell to within 3500 feet of the ground be- fore pulling the rip cord. He was falling slower when he opened chute than before. Another trans-continental non-stop record was set by Capt. Frank Hawks in his fast Northrop plané. Elapsed time of 13 hours 26 minutes from Los Angeles to New York cut more than an hour from his own previous non- stop record. Most notable feature of flight was the fact that “Mr. Zilch,” Hawks’ robot pilot, flew the ship most of the distance. The robot pilot, gyroscopically com- trolled, has previously been described in this magazine. 30` Modern Mechanix and

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4 A genuine flying wing is the bat- wing plane shown above, created in South Bend, Indiana. Safety is the prime feature of design, the ab- normally large wing surface ena- bling ship to descend nine feet a second, a gentle speed compar- able to that of a chute jumper. Setting a new record in his 51-hour hop between New York and Norway, Jimmie Mattern, on a round-the-world flight to better Post and Gatty’s record, encountered difficulties farther on and contented himself with establishing a record on a solo world flight. Interesting is the fact that neither Mattern’s nor Post and Gatty’s flights was truly “round the world,” but rather “top of the world” trips. A true circle flight around the world would cover 25,000 miles, divide globe in two, as indicated in drawing. Inventions for August 31

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treamline (RAIN Heralds STREAMLINE ESI “WEIGHT OF GHT OF ; | ORDINARY THREE-CAR `, PULLMAN “STREAMLINED TRAIN Interior of new aluminum Pullman car, weighing but half as much as conventional steel car. Note air ducts in ceiling. 32 ELECTRIC MOTOR” eae FRONT TRU n Features of carefully streamlined train under construction for Union Pacific Railway ate given in drawing. Note clean, cinderless Power mechanism—Diesel engine hooked to generator and motor on front trucks. At left, three-car streamlined train weighs no more than ordinary Pullman. by ROY DEAN Super-speed railway trains are here— rivaling airplanes in swiftness, gliding along in luxurious silence, resembling trains no more than the Leviathan looks like the flagship of Columbus. An amazing new era in railroad transporta- tion is forcing present-style trains toward the junkpile. The “why” of this aston- ishing revolution in travel style is given in this absorbing article. FEW months ago MODERN MECHANIX AND INVENTIONS published an article calling attention to the need for an entirely new type of railroad train which would give passengers cool, clean, quiet transpor- tation free from the annoyances of cinders, blasts of desert air from outside, the jerk- ing and swaying of cars in motion, and the endless click of wheels against rail joints. Now such a train is in actual process of construction for the Union Pacific Railway, and transportation experts are unanimous in the opinion that its design opens up a new era in rail travel which will eventu- ally force the heavy steel trains of today, with their fuming coal-burning locomo- tives, onto the scrap heap. A real revolu- Modern Mechanix and

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CW Cars of streamline train are articulated—one truck between two cars and the cars hinged to- gether. By eliminating or RAILROADS I VENTILAT- TING DUCT ` INDIRECT —\ LIGHTING slack motion, this im- proves riding quality. At right, how speed is gained by streamlining. tion in train design is well under way— belatedly enough, when one considers that except for size our present locomotives are not essentially different from those used a hundred years ago, and there have been few new principles in passenger car structure since someone thought of putting a roof over a floor on wheels. Competition of automobile,. bus, truck and airplane has finally forced the rail- roads out of their inertia, made them real- ize that plenty of passenger business is theirs to command if they furnish the pub- lic what it demands in the way of economy and comfort. Power Needs Reduced by Half That the Union Pacific train fills this bill to a T, there can be no doubt after a study of the design reproduced above. It is fully streamlined, and this, in conjunc- tion with its light weight (the three-car train weighs no more than an ordinary Pullman) makes possible speeds of 110 miles an hour. To the airplane is due the development of aluminum alloys which reduce weight two-thirds. Each car of the new train is tubular in shape, giving great strength. Streamlining of the train is. carried farther than ever before, so efficiently that it is esti- mated power requirements at 100 miles an hour will be only half that required for con- ventional trains. Windows are placed flush with the walls, ~ vestibules between cars completely covered over, and headlights and other projecting units are recessed into the body. Outside air never enters the train. Three ducts keep Inventions for August Right above, cross section of new train. Note the three ducts for forced ventilation of washed air. All cars are completely sealed against outside air. Note the tu- bular construction of body which gives great strength. Rounded. end of new Pullman car, interior of which is shown on opposite page. Steel, too heavy, is out of the picture in new railcars; light metal alloys take its place. 33

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Europe Has Long Had Motor-Driven Trains Developing 100 M. P. H. [How sPE A Swiss adaptation of air- driven rail coach is shown above as planned for manu- facture. 223 m.p-h. is prom- ised. Note that wheels are mounted at 30 degree angle. 34 ED-CAR HOLDS RAILS European nations have up to now set the pace in motort- driven trains. This “automotrice”, whose 115 m.p.h. ate said to make it the fastest rail motor in the world, seats 52 persons. It is shown in the Gare St. Lazare, Paris, France. it perfectly ventilated; in summer the air is filtered and cooled, in winter, heated. Silence comes from use of heavy body in- sulation, use of rubber in trucks, and a re- silient wheel to absorb the impact of rail: joints. Trucks are swung between each two cars, the front end of one car resting on the same truck which carries the rear end of the preceding car. Power comes from a Diesel engine with direct connected. electric generator and motors on the wheels of the forward truck. Thus smoke, cinders, and soot of the steam locomotive are entirely done away with. So much for the Union Pacific train. It is now under construction and will be used to test its feasibility for transcontinental travel. It should be pointed out, however, - that though this is by far the most advanc- ed design of its type, European nations for some time have “had the jump” on us in developing motor driven trains. Foreign Super-Speed Cars A government-owned French railway has successfully tested a double-decked rail car at 125 miles an hour, with an 800 horse- power engine using benzol or alcohol. The Bugatti “automotrice,” illustrated else- where in this article, has long been popu- lar. In Germany, a Zeppelin car, streamlin- ed and driven by an air propeller, has been in use for three years. An air-driven car has been designed by a Swiss inventor which he claims is cap- able of 223 miles an hour. Although his car has not been constructed yet, because of financial difficulties, a study of his idea as reproduced with this article indicates that Modern Mechanix and

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Most Railway Speed Records (Regular Schedules) Are Held by Europe The Royal Scot, England’s most famous train, is on exhibit at the Century of Progress. British locomotives cannot approach American engines in size because of restrictions as to clearance and size made necessary by low bridges, etc. it is entitled to be taken seriously. His method of holding the car to the rails at extreme speeds by mounting the wheels at a thirty degree angle is ingenious. With this difficulty overcome, it is a simple prob- lem in mechanics to install a motor power- ful enough to drive the train at airplane speed. Most train speed records, as shown on an accompanying chart, rest in European hands. It must be remembered, how- ever, that trains are rigidly kept be- low certain speeds for reasons of operation. Wear and tear, fuel con- sumption, possibility of accident or derailment, and dozens of other fac- tors hold down American train speeds below what could easily be attained. Weight of cars is much greater in this country than in Europe. Nevertheless, an interesting side- light on the rate of advance ‘of rail design is afforded by the fact that the speed record of 112.5 miles an hour still stands—and this was set 40 years ago when famous old.Engine 999 hauled the Empire State Express at this rate. The 112.5 miles an hour speed is just about what a well streamlined train should do hour after hour if Mr. Train Rider is to be satisfied that the railway is keeping up to date. Inventions for August ROYAL SCOT. (BRITISH) AOOMILE RUN-- LONDON TO GLASGOW ene CENTURY | TED- 9S60MILE RUN, | new E CHICAGO — =: f FASTEST TRAIN FOR SO. GREAT A-DISTANCE, = FLYING HAMBURG J ER (GERMANY) DIE SEL-DARIVEN LOCOMOTIVE NORD RAILWAY = $ CPASTESTIN FRANCE) CHELTEN HAMI FLYER (BRITISH) FASTEST TRAIN OM REGULAR SCHEDULE TRAIN SPEED RECORD Various speed records for trains are given in the drawing above. Note that the highest speed rec- ord has remained untouched for 40 years. For that matter, today’s lo- comotives are larger but not essentially different from the first engine used in America. 35

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Echo Sounding Device Used to Locate Schools of Fish OSCILATOR eed 1S ane PSUR Nia geod Teale Nee ae REFLECT. The echo-sounding device, adapted to fishing fleet purposes, locates schools by projecting sound waves downward then listening for echo, Fish schools have characteristic echo. Silhouettes Decorate Lamp Shade BY USING the lampshade as a frame, the family silhouettes may be grouped in a unique manner. An octagon-shaped lamp- shade, some black silhouette paper and glue are ma- terials required. Sketch the pro- files of thepersons whose silhouettes you desire, then cut out the draw- ings. Glue or paste each picture in a separate panel of the shade, as illus- trated at the left. Give the inside of the shade a coat of clear shellac to keep the silhou- ettes from curling. Silhouettes are pasted on sides of the lamp shade with glue. 36 [o Ton of schools of fish by shooting sound waves down at them and listen- ing to the echoes, is a development forecast by a British radio engineer. The proposed fish detector is described as a modification of the echo sounding device now widely used on ships to determine the depth of the sea bottom. Echoes of distinctive char- acter are returned by different types of sea bottoms, and it is expected data can be worked up that will permit fishing fleets to tell just where the sea underneath them is populous enough to make it profitable enough to let down nets. Sleeve Repairs Heating Coils SIMPLE little sleeve now on the market makes repair of broken electric iron and heater elements an easy job. The two ends of the bro- ken element are inserted in the sleeve, which is then pinched with a pair of pliers. This makes a firm joint and saves expense of new element. Pinching sleeve joins wire ends. Making Odd Masks Is New Hobby AKING masks of celebrities from unique materials is a new hobby for the artis- tically inclined. Below are shown two of the masks, one of George Bernard Shaw, the famous Irish author, and the other of Greta Garbo, movie star. Mr. Shaw’s face is made from tin, his whiskers from brush- es. Garbo’s hair is made from steel wool. Old brushes form the whiskers on tin face of Bernard Shaw mask. Garbo mask has gilded steel wool for hair. Modern Mechanix and

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Artificial Opera Scenery on Lantern S lides Book Turns Own Pages, Speaks N OUTSTANDING mechanical attraction of the World’s Fair in Chicago is an “automatic talking book.” Shown be- low, it’s a book whose pages are almost ex- clusively devoted to illustrations. The cover opens automatically and the pages turn of their own free will. As the pages turn, a voice from a loud speaker lectures to you on the photos displayed at the moment. The voice is synchronized with the illustra- tions, so that you receive the impression that a human lecturer is speaking. Outstanding attraction of Chicago Fair is this book which talks to you about pictures as pages turn automatically Inventions for August Artificial scenery 19 projected om back-drop from lanterns in the rear of the stage as illustrated here, eliminating elaborate props. Images are superimposed on the screen to give a startling effect. HE necessity for economy was the mother of an invention which has elimi- nated elaborate operatic stage settings, sub- stituting in their place a translucent back drop on which is projected the atmospheric scenery. The “scenery” is painted on three lantern slides, as illustrated above, and is repro- duced on the screen with a projecting lan- tern. Startling effects not obtainable with ordinary settings are achieved by superim- posing the distorted images on a curved screen which gives a strange illusion of space. Hump Makes New Pins Pull-proof HE corkscrew has a mate ina new type of pin recently invented. Unlike its fellows, this new pin hasa hump in the mid- dle which makes the pin hold fast in any material. An attempt to re- move it from the cloth makes the hump bind slight- ly in the hole, and it is this pressure which prevents the pin from working out. The hump on this new pin holds it firmly in anv fabtic. 37

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“OHINGS ‘You Mustn’t eiss Ce Century of Progress Exposi- tion—more familiarly known as_ the World Fair—has been open long enough for visitors to realize that if they are to “do” the show completely, passing up none of its features, they will have to devote all their waking hours for the next six months to the purpose. So crammed is the exposi- tion with marvelous exhibits from all over the world that some sort of guide to the high The Fair grounds are more than three miles long, half a mile wide. Visitors may not realize that much of the ground on which the buildings are erected wasn’t naturally ground at all, but the bottom of Lake Michigan, Dredges reclaimed it for the use of man, creating real estate values out of worthless mud. 38 spots will be welcomed—hence the picture map reproduced on these pages. It doesn’t pretend to exhaust the possibilities of the Fair; it would take a volume about the size of an unabridged dictionary to do that. But it does point out features which early Fair visitors have found to be the most interest- ing of them all. If you have only a day or two at the show, take the map along for your guidance. Daily the pageant of trans- portation is.presented in the Travel and Transport building —an education- al show in which every mechanical means of transportation is seen “in l person. ” The amusement section in the Midway is crammed with entertainment’ concessions which relieve with a sideshow touch the serious purpose of the Fair. Modern Mechanix and

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at Chicagos WORLD Yair \ Field Museum Natural histor exhibits fullo a i Sa Sig Sky Bide! ; igdest thrill of hes-from sar. Pee position: EB : es to sharks Scoot between ‘ = apanese Village [towers in rock . section right, hanging 2 zut of old 7 ippon. Adler ae eg : - Planetarium. | Streets of Paris eS Where sun moon) : Another high and stars do- t -cafes dane SP? nalis “ete.” | through their. A i z ts i peces for yot- musements 57 varieties Ata : nehanted Island Paradise for the youngsters -cand ynountains, toy iants, n every- thing ( park the kids here) blades without | injuring humen hands- ete. World’s largest stage is be- ing built in Soldier’s Field. BA Inventions for August 39

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Police Planes Take Off From Car to Hunt Down Crooks When alarm comes in, Oregon state police pursue fugitive criminals in this small plane, which takes off from plat- form mounted on top of a touring car as shown above. Skunk Odor Saves Miners’ Lives HE smell of a skunk as a danger signal in mines, warning everybody to get out quickly in case of fire or explosion, has proved its value in Canadian mines accord- ing to recent government reports. Sealed bottles of a chemical having a skunk-like odor, are kept at hand in blower houses or similar places through which air is supplied to the mines. In case of an alarm the engineer in charge breaks bottles of the malođorous chemical in the air ducts lead- ing to the mine. UGITIVE criminals stand little chance of escape when the Oregon State police take out after them. They are hunted down from the air by a plane that takes off from the top of an automobile, which then goes after the felons on the ground. How the scheme works is illustrated at the left. The small plane rests on a plat- form on the top of a sedan and has folding wings to facilitate storage. When an alarm comes in, the wings are unfolded, the motor car speeds up to 25 miles per hour, and the ship takes to the air in search of the fugi- tives. Dick Rankin, Portland, Oregon, avia- tor, is the originator of the stunt. Coils in Soles Give Springy Step HE springiness oe z provided in the p> soles of a newtype of shoe on the market greatly re- duces the shock of walking on hard sidewalks. As shown at theright, the coil springs are fastened to a metal plate that is inserted between the inner and outer soles. In ac- tual tests the cush- jioning effect of the shoe proved to be superior to that given by rubber, inventor claims. Springs in soles of shoes absorb shock of walking on concrete. Movie Mechanics Rebuild 13-year-old Car Into Ultra-Modern Limousiné OLLYWOOD was set agog recently when 2 an automobile of startling, ultra-mod- ernistic design appeared on the streets. The creation, shown below, was the work of Hollywood carriage-makers, who built it from an old bus that had been prowling the streets since 1920. The “chariot on wheels,” as the bus is called, is to be used in a movie telling a fantastic story of events in a mythi- cal kingdom. Though the car seems to represent a fabulous cost, in reality it cost less than the price of two small cars. Latest creation from Hollywood—a sumptuous automobile made from old car for appearance in mythical kingdom picture. ‘40 Modern Mechanix and

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Balloons to Fly in Tandem to Check Stratosphere Speed . REPETITION of Professor Piccard’s . stratosphere balloon flight made last year, but using two balloons in tandem in- stead of the one balloon, has been ap- proved by the Belgian National Fund for Scientific Research. Previous flights were handicapped by the fact that both ascent and descent hap- pened too quickly, so that many observa- tions planned for intermediate heights could not be made. That is the reason for the plan of a second balloon, fastened be- low the chief one, as a kind of aerial brake. This lower balloon will be piloted by an aeronaut in an open basket. The tandem arrangement is expected to rise about six miles, where both balloons will hover for several hours to make observations. Pipe Grid Keeps Tobacco Dry TINY coil grid built especial- ly for use in pipes prevents tobacco from being packed down into the wet bowl. The cooling air space keeps the weed dry as it burns down towards the bottom. When the tobacco in the pipe is firmly tamped down it is said to dry like a well made cigar. The grid is made of es- pecially tempered alloy and will outlast the average pipe. Coil grid placed in pipe prevents tobacco from becoming moist. Key Ring Hooks to Clothing SIMPLE, safe and handy key ring, which the belt or any part of the cloth- ing, has just been patented by a Los Angeles inventor. The hook, shown at the left, is made from two pieces of tem- pered spring steel. The front piece carries the ring, and, being rigid, may be pushed down, allowing the two small, sharp prongs to sink into the belt or cloth to which you want it fas- tened. New key ring attaches to belt or any part of the clothing. Inventions for August can be attached to . REAL Drawing shows how balloon will be hooked to stratosphere gondola to prevent too rapid ascent into rarified atmosphere. ERE’S a formula for removing old oil, paint, or varnish coats: Apply a mix- ture of about 5 parts of potassium silicate (water glass 36 per cent), about 1 part lye or soda (40 per cent) and 1 part ammonia. The composition dissolves the old varnish. 4l

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“ORICK (Camera Shots He FRONT VIEW— FOLLOW THROUGH. SIDE VIEW— FOLLOW THROUGH Photo at right shows how to bring the powerful muscles of the mid-section of body into action behind the stroke, Silane . 5 z HT ARM Above—All!l in white, Bobby shows ALS IN correct position of the entire body in ADDRESSING following through after hitting the § BALL ball. Right—hie right arm, standing out in’ ddzzling white contrast, in Proper position for addressing ball. ‘HE use of the movie camera in teaching golf is nothing new— it’s been used any number of times to explain fine points of the game’s technique in such a manner that Mr. Duffer can presumably- go out on the course, after studying the movie, and wind up joyfully at the 18th hole with a card of 120 or thereabouts, repre- Photo below shows position of left arm, Note also how Bobby stands behind the ball permitting bim to move into the shot as he swings. senting something like a oe PEE 25-point improvement. : AIER But it has remained for Bobby Jones, king of them : T all, to devise some brand new photographic tricks MEO aisioes for his new Warner Brothers movie “How to Break À EAE 90.” In addition to stop-motion photography, which enables Bobby to halt his swing in mid-air while he stands alongside himself and explains what he is doing, he wears an assortment of trick black and white costumes which emphasize the action of dif- ferent parts of the body in executing the perfect golf stroke. Some of the striking results of this photographic technique are presented on these pages. With Bobby standing against a black backdrop, dressed entirely in black except for the limb clad in dazzling white whose action is. explained, the eye is not distracted by extraneous details. z Essential points of the Jones golf technique are brought out in these photos for the benefit of MODERN MECHANIX AND INVENTIONS readers who may wish to 42 Modern Mechanix and

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SBOBBY JONES FRONT VIEW AS DOWN _- - STROKE’ STARTS—NoTE HOW LEFT.HIPIS Manat 5 Te is important, says Bobby, that left side be taut from hip to hand, as shown at left, when starting the downstroke. Above—Bobby points to a stop-mo- tion picture of himself and explains what he is doing. Left—thie picture TOP OF. tells better than a thousand words SWING— the importance of a straight right leg Nonae to give driving power, on the teat licthaaache familiar fulcrum and lever principle. PUTTING POWER . è improve their game. Cor- Downstroke swing should be inie tiated by the hips rather than arms. Photo below shows proper grip. EER Oa rect address or position as one stands to the ball is well shown in three of the pictures. Note that Bobby stays behind the ball where he can move into the shot as he swings through. He says it is best to avoid try- ing too hard to force the body into a mechanically set position, as it is likely to set up muscle-stiffening tension. Few golfers, Bobby says, move their hips in the correct way to add force to the drive. Powerful F muscles of the back and waist cannot be brought JIRE properly into action unless the hips are turned Seara enough to enable the club to swing down to the ball “DRESSING from the inside. Slicing and pulling are attributed tals to this fault. In the photo illustrating the top of swing, note how Bobby’s right leg, in white, is placed to bring the powerful body muscles into play behind his stroke. The front view of the downstroke gives a tip on the important matter of handling the left hip. Bobby regards it as important that the hips should move first on the downstroke, before the arms, the left hip leading the turn back to the ball. The entire left side should be taut, from hip to hand, when the club is at the top of the back swing as illustrated. In the actual movie, slow-motion photography is used while the sound track carries Bobby’s own voice. Inventions for August 43

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“DEPRESSION Spurs Lost Charles Courtney, master locksmith, who recovered part of the sunken He tells of his adventures in this article. gold of the Hampshire. {{OLD, down through the ages a symbol of wealth, has now become so doubly priceless that we in this country may not even legally possess it! Beyond a doubt that is one reason why so many expeditions are at work today recovering the gold of other ages—gold which went down weeks or years or centuries ago, and since that time has been resting uselessly in the mud-filled hulks of ancient galleons. Just how many submarine treasure-hunt- ‘ing expeditions are at work today it is im- possible to say, since many of them sur- round their activities with a veil of absolute secrecy. The purpose which this secrecy serves is easily understood when one rea- lizes that the treasure lure may bring rival 44, by BENNETT LINCOLN Treasure long lost under ocean waters is the golden loot which is luring half a dozen expeditions to recover it, spurred on by the urgent need for gold developing out of the present economic - conditions. Charles Court- ney, master locksmith who battled death to recover $60,- 000 from a sunken treasure ship, tells his story of high adventure in this fascinating atticle. l salvors to the scene ready to do battle for sunken loot. . A few days ago a coast guard. cutter was despatched to a point 60 miles off the Vir- ginia Capes where two rival treasure ships were threatening open conflict. The lure in this case was the sunken Merida, which went down 20 years ago after a collision, carrying a reputed $6,000,000 in gold. The trawler Theresa and Dan and the tug- boat Salvor were both anchored in the vicinity of the sunken ship. Each called for assistance to prevent an open clash. Even- tually both ships retired and the Merida’s gold still remains for the lucky salvor. Perhaps the most striking of recent hunts for lost ships is that in which $60,000 was recovered from the sunken Hampshire, the ship on which Lord Kitchener per- ished June 5, 1916. With the boat went down millions in gold which was being } carried to Russia. Just how the wreck of the Hampshire was located in the face of unbelievable difficulties by a “Mr. X” who spent four years tracing down a Ger- man who worked on the boat which left the mine that sank the Hampshire, is a story in itself. More thrilling were the adventures of Charles Courtney, master lock- smith, who personally recovered a strong box from the Hampshire’s safe containing $60,000. Readers of MopERN MEcH- ANIX AND INVENTIONS At left—Courtney bored open the sunken Hampshire safe with a grindstone drill and removed a strongbox containing 360,000 in gold. He had to work with extreme care to avoid setting off possible T.N.T. triggers within the safe. Modern Mechanix and

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old “REASURE Hunts WRECK OF | KITCHENER SHIPS Charles Courtney’s long battle with death when treacherous currents crushed him irresistibly against the hulk of the sunken treasure ship, is illustrated. In circle—how telephone communication is maintained. Map shows sunken Hampshire. Inventions for August 45

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Treasure Wrecks Dot Shores of Our Continent—Many Still Unfound “GOPHIA AND {SLANDER post miners golg Brand new diving ap- paratus, suitable for treasure salvaging, just tested by British officials. Air supply is carried on back of the suit, making air lines to surface un- necessary. Limb joints move flexibly on an oil cushion. will remember Mr. Courtney’s own story of his methods of opening the safe on the sunk- en Egypt in an eminently successful salvage venture which up to date has recovered $3,250,000. Mr. Courtney is president of the Ameri- can Association of Master Locksmiths, and so widespread is his fame that when a man was needed to unlock the safes of the 45 Some of the wrecked treasure ships of the American continent are pointed out on this map. These are only those which have been definitely located and on which salvage work has been done. Scores of others lie in spots as yet unknown, waiting to be found through old records—just as the location of the De Braak with its fabulous $40,000,000 in gold was recently discovered after long search. Hampshire, Mr. X came from the other side of the sea to seek his services. Courtney accepted the commission, veiled in secrecy, little knowing that before he had completed his contract he would very nearly have paid with his life, and that he would carry a shattered wrist and hair prematurely whit- -ened by terror as a permanent reminder of a disastrous bout with death. Sitting in his New York office, the master locksmith told me the terrifying story of. his experiences for readers of this maga- zine. He told me of being taken aboard the salvage ship, of a zig-zag course taken to the treasure site to elude possible pursuers, of the location of the wreck—and finally of his own part in the drama. “Right after the ship was identified, I started my diving work. I went down and with the use of a grindstone drill succeeded in boring open a built-in safe in the ship. That was a mighty difficult job, cracking that safe. I had to guard against T-N-T triggers or other safeguards which its mak- ers might have secreted init. I blew it open without mishap, however, and withdrew from it a strong box which I later dis- covered contained about $60,000 in gold. “I went down once again after recover- ing that strong box with the $60,000. You see there was no possible way of opening those safes without my presence down there. It was impossible to calculate the nature of the tumblers because of the havoc: Modern Mechanix and

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Long Lost De Braak, Carrying $40,000,000, Found After Long Search of time. The only method we could employ was to locate the safes and figure out the best and most harmless way of blasting them open, and still regain the treasures they held. “By April 24 there had already been a great deal of blasting work. This was the day when we were to reap our hard-fought for harvest. There was $10,000,000 lying there waiting for us to bring it back to civilization. “Down we went, Costello, Samuel Mansfield, an adventurous youth from Virginia, and myself. We had the customary equipment and auxiliary devices. We used our telephones constantly, keeping in com- We were in our aluminum suits. munication with the engineers on deck: of the salvage boat. As my two companions and myself were let down on the second descent the first 100-foot drop was without a hitch. At 200 feet I was suddenly seized with misgivings. Something was wrong. “I was cut off from communication with my other two comrades. Fear of darkness overcame me—darkness as smothering, as all-enveloping as the inside of a coffin. “Bring us up quick! We've been struck by an undertow!’ I yelled desperately. “But no response. No signal or other token that those on the surface got my S O S. Having had experience as a diver I tried to be calm. I figured, or tried to ‘figure as calmly as I could, that those above were waiting for the current to ease. I Inventions for August The De Braak, sunk off Cape Henlopen, Delaware, decades ago, is a hulk reputed to contain $40,000,000 in gold, It has just been located by Allan C. Robertson after a long, romantic search through records of the period. Salvaging will be done by pumplines, sucking up mud and cleaning the “bones” of the hulk to make it easy for divers to lay bands on the drowned gold. Inset photo shows the powerful pumplines being tested. The photo at right shows weird machine used by syndicate to recover gold from the Islander, sunk off Alaska. Some gold was recovered when dissension among members forced temporary abandonment of scheme. could not budge the cables. The electricity was cut off so that there could not be a short circuit. “In another moment I was seized with a terrifying sensation. As I dangled there helplessly, hoping and praying for rescue, my suit was cut in the right side. I was flung violently against the side of the Hamp- (Continued on page 8). 47

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Motorized Eyebrow Eyebrows are given that fashionable high arch with a minimum of pain to the vain one with this new motor driven tweezer. The specially designed puller on the end of the flexible shaft from the motor extracts hairs painlessly. Wire Breaks Cast Without Pain THE torture of removing a plaster cast from a patient’s leg is greatly reduced by the use of a new method devised by surgeons, When the cast is first shaped around the injured limb, a wire is embedded in the plaster, the ends protruding at top and bottom. When the cast is to be taken off, the medicos run the wire through a slot in a rectangular board, and then twist it around a key. When this key is turned in the same manner that you turn a key on a sardine can, the wire is ripped from the cast, thus breaking it apart. Cast is broken apart for painless removal of limb by tucning the keys which wind up the wire embedded in the material forming the cast. Hammering and chiseling is eliminated. 48 Tweezer Works Rapidly, Painlessly HE painful yanking of eyebrows with tweezers in order to obtain the high- arched brow, the fashion now prevailing among the feminine sex, is a thing of the past, thanks to the development of the machine shown in the photo at the left. The instrument, inventors claim, not only pulls the hair out by the roots, but also does the job in a painless and perma- nent manner. Power is furnished by a small motor through a flexible cable, to the end of which is attached a hair-ex- tracting device of special design. Wheel Lays Perfect Paint Stripe HIS automatic striper for autos, furniture, toys, etc., is said to lay a perfect stripe by means of a revolving wheel. A slight pressure on the thumb trigger releasesthe wheel and the paint is applied by its rim which passes in and out of a color chamber. With this tool any tyro can now do a perfect job of striping. Odd Device Makes Music From Air -Pressing trigger starts the stripes. Rene Bertrand, French engineer, operating his new instru- ment which, he claims, produces music through electrical transcription through the air. FRENCH engineer, Rene Bertrand, has developed an instrument which, he claims, will produce music through elec- trical transcription from the air. How the apparatus operates has not been di- vulged by the promoters, save for the in- formation that it is far superior to the instrument devised by the Russian scien- tist, Prof. Theramin. Tone and volume of the music is controlled by the dials on the two cabinets, while the sounds issue from the two large speakers. Modern Mechanix and

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Tennessee Project to Help “Whip Depression Cove Creek Dan- 55,000 acres flooded’ tocontvol river waters Flood prevention. in Tennessee, Mississipp Ohio River regions. aclamation of millions ofacres of fertile lands for farming 75,000, 000 bhisoil de uscle Shoals {Developing 206, OOOHR at costof cent per Kil-hour = Muscle _ Shoals Here is picturized one of the most astounding projects yet advanced to whip the depression—the industrial de- velopment of the Tennessee River valley, site of the famous Muscle Shoals dam. The plan, still controversial in many of its aspects, is here visualized in picture form. Recently brought to national prominence by President Roosevelt, the plans call for che expenditure cf a billion dollars and the employment of 200,000 men. Twenty-two gigantic dams Inventions for August Sass Reforestation 100, 000,000 acres r a Water power= 22 i dams. generatin 3 3,500000 HR N Producing heap fortilizer-TNT for Wartime — would be built along the. river to generate 4,000,000 h.p. for cheap distribution to Midwest cities. A 9-foot channel would be dredged from Knoxville to the Mississippi. Huge nitrate factories at Muscle Shoals would turn out fertilizer for farmers, high explosives in wartime. Criticism of the plan revolves around its economic aspects, some authori- ties being doubtful that the huge cash outlay would ever be returned by operations, 49

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Model Masterpiece Built From Tin Cans, Old Clocks, Etc. Harry Windsor, of Inglewood, Calif., with his model of the S., S. Majestic, which he built. Pronounced a master- piece by experts, the vessel has all machinery of its big sister. Easiest Way to Fix a Puncture ELATIVELY few of the millions of S drivers of small cars with drop center rims are aware that it is easier to repair a puncture without removing the casing entirely from the rim than to sweat and swear through the usual routine of taking off the casing. . After you have jacked up the car lo- cate the source of the puncture, then pull out the offending tack or nail and mark the location on the casing, as demonstrated in the accompanying photo. With tire tool and screw driver pull off the outer bead of the casing just sufficiently to permit the inner tube to be grasped with the fingers or a pair of pliers. Pull out the tube, put on the patch, rein- sert the tube and inflate. And it’s all done so easily that you will adopt this stunt as the most handy of all. Pull off outer bead of casing, take out inner tube to repair. 50 wat an expert modelmaker can do when he puts his heart and soul into the job is seen in the photo at the left. Its the S. S. Majestic in miniature. Said by experts to be one of the finest jobs of its kind, the model was built chiefly from pop corn cans, shoe eyelets, parts of old alarm clocks, piano wire, pins and similar odds and ends. The hull is of metal and veneer. Within is machinery to operate anchors, booms, windows, screws, and lifeboat launching devices. Length of the remarkable vessel is 7 feet, height 2.feet, beam 12 inches. Eleven months of delicate and tedious work went into construction of the ship. Foot-powered Outboard for Fishing ITH an ingenious foot-operated device for propelling a boat through the water, the hands are left free to fish, shoot, or what not. Generally stated the device consists of a regular outboard motor type of propeller on a vertical shaft connected to the foot pedal mechanism by belts, and a canvas-back seat in which the operator sits. The belt runs in rollers at the top of the shaft and, traveling around the sides of the boat, it connects with two foot pedals equipped with heel sockets. This device cannot drive a boat as fast as an outboard motor but it has ordinary rowing beat a hundred ways. It folds, seat and all, into a 29-pound package for trans- porting. Ideal for fishermen is boat with outboard mo- toc type of propeller on vertical shaft con- nected to foot pedal mechanism by belts. Thrusting both feet forward at same time drives the boat straight ahead. Advancing left foot more than right steers boat to right and vice vetsa. To put in reverse the right foot is pushed all the way forward, pedalling con- tinuously at same time. Modern Mechanix and

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Braving the INFERNO of a VOLCANO Amazing plan to descend flaming crater hanging in cage from a derrick! Above photo shows scientists lowering a crate of guinea pigs into volcano near Tokio to test deadliness of fumes. poo to a depth of a thousand feet in the boiling, fume-filled crater of Mt. Mihara, near Tokio, Japan, scientists who are now carrying out an amazing program of volcanic investigations will hang in a tiny metal cage over a bubbling flood of molten lava, suspended only by a thin steel cable. Details of the device are given in the accompanying drawing. A live mon- key, guinea pigs and rabbits were used in testing the toxicity of the volcano’s gases. Mt. Mikara is a favorite spot for sui- cides, 50 people having leaped to their death since January first. In a cage of metal lined with asbestos, with quartz windows which resist heat, scientists will make observations inside the crater of Mt. Mihara, near Tokio, Japan. A derrick will be used to raise and lower the cage. A supply of oxygen is carried in containers, enabling the men in the cage to stay down for long periods. Communication with the derrick operator is maintained by telephone. In circle—this monkey was lowered into crater to test effect of fumes on man. Although over- come when removed, as shown in picture, he speedily recovered and scientists decided that with proper protection men could descend into the crater with impunity. Inventions for August 51

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TWINS The ancients believed that the stars determined the course of human affairs, Astrologers consulted the zodiac, shown above, to learn when it was safe to bathe, get a haircut, take medical treatment, and so forth. by EARLE R. BUELL Shrine at Lourdes, France, showing crutches discarded by afflicted per- sons cured by faith. Cheer up, have faith—it’s good for. your health. That’s the verdict of scien- tists who have been experimenting to determine effectiveness of remedies em- ployed by ancient medicine men, as- trologers, and modern faith healers. This article explains why some people actually do get well when they have a strong belief they are going to get well. PTIMISM is better than apples for keep- *ing the doctor away. _ There is a scientific basis for faith heal- ing. Even some ancient superstitions had healing power and the hocus-pocus of the tribal medicine man may have saved many ives. These are some of the conclusions arrived at by.a group of experimenters who have been endeavoring to test out the effect of states of mind upon the general health. Applying the scientific methods of the clinic and the laboratory to their work, the investigators at first set out to find out which if any of the healing systems widely practiced by various cults could be shown to have any therapeutic value. Very much to their amazement they found evidence that not only these cults but any religion de- voutly accepted by the individual had cer- tain definitely traceable physical effects of a beneficial nature. The discoveries went even farther, indi- 52 Worry, desponden- 183 HIGH BLOOD PRESSURE, cy, grief, pessimism are fatal to health. These emotions cause high blood pressure. Victim may seek relief from nervous tension in drink, which leads to weakness of heart and early death. cating that any optimistic or inspiring thought was valuable for healing and that some miraculous appearing cures had actually been effected by the reassuring words of a doctor in whom the patient had confidence without any treatment at all. On the other hand, it was found that a long list of emotions related to fear had ex- actly opposite effect and that to embrace a philosophy of pessimism was about on a par with warming an asp in the bosom. Modern Mechanix and

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Ancient

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AW ye IN H Flan Y É ww A ; WN GEENA FON < De While mystice hocus-pocus of atn- cient medicine men was scientifi- cally impractical, it actually cured some sufferers who strongly be- lieved they were going to get well. by means of the blood

NORMAL BLOOD PRESSURE TYPE Optimism, faith, cheerful- ness tend to keep blood pressure normal, resulting generally in long life and vigorous old age. No strain is put upon heart, so that it remains sound through- outlife. Religious faith thus has a scientific justification. Instead of being able to find out which sect was nearest to the truth as had been intended, experimenters found that truth or falsity of a sincere belief seemed to make no appreciable difference in its curative effect. This gave rise to the realization that countless supposedly silly superstitions had probably improved the health of those who believed in them. As a result, there arises the possibility of testing the sincerity of religious convictions Inventions. for August pressure gauge and other Worshippers pray- instruments and, while it ing at grave of is not suggested that iest for deliver- ) ; ate from physical these instruments will be ailments. Belief. in installed at the church potency of prayer altars, there is said to be frequently results : ample evidence that posi- tive results could be ob- tained by this means. The findings of the experimenters have dovetailed to a large extent with those of Dr. William S. Sadler of Chicago Uni- versity, although the experimenters were without a knowledge of Dr. Sadler’s works, in cure, experimen- ters have found. .and they are taken to be mutually cor- roborative. They are said also to be in line with the prophecy of Dr. Charles P. Steinmetz, fa- mous physicist, who shortly before his death predicted that science in the near fu- ture would turn to spiritual matters and that developments in this field would be similar to those in the physical and mate- rial realm. One of the more remarkable discoveries recently made is that there is apparently a scientific basis for the healing principles of faith, hope and charity or love as described in the Bible and it is indicated that any in- spiring writings and the encouraging or uplifting words of any admired or revered speaker may be sufficient to effect rather startling cures in some instances. The time may very well come when a doctor’s prescription will read: “See your priest, minister or other religious adviser.” Public intuition has for some time been directing large numbers of persons back to their churches for physical as well as men- tal and spiritual assistance, it is said, and a period of increased interest in the church is prophesied. ; Beginning first with a study of religious 53:

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Religious Emotions Carry Gandhi Safely Through Fast of Three Weeks Conclusive proof that the mind affects the heart is given in situations illustrated here. Fright, love, superstitious fear speed up the pulse, putting heavy strain on the heart. healing and recognizing the fact that savage races since the beginning of history have looked to their medicine men both for re- ligious guidance and physical healing, ex- perimenters have followed the course of healing through the story of many religious sects to the present day. They found that belief in faith healing or prayer cures had never died out though 54 Power of mind to control body is demonstrated in this experiment. blood to head, weighting down upper end, Thinking of feet SUBJECT THINKING INTENTLY OF FEET Mental work drives reverses the process. Above left— Mahatma Gandhi, whose faith and religious zeal car- ried him safely through three weeks’ fast, de- spite warnings that he could notsurvive. Right —How yeu would look after going without eats for 40 days. Fasting ex- periment was under- taken by Battle Creek, Mich., man to prove that 40 days of absti- nence from eating is beneficial to the body. it had often fallen into disrepute. In study- ing the superstitions. of other days, they found many that dealt with healing and came to the conclusion that even the most ridiculous might effect cures if completely accepted by the patient. That some of these must, however, have severely taxed the credulity of the individ- ual, is indicated by some of the supersti- tions studied. A cure for warts and corns was found which required the patient to lie on his back along a boundary line on the twentieth day of the month with the hands extended over the head. With whatever thing could be grasped while so. doing, he was to rub the waris and they would immediately dis- appear. Corns were to be cured by watching for a shooting star and, on seeing one, imme- diately pouring vinegar upon “the hinge of a door. For headache, the patient was instructed in one instance to tie about the forehead a piece of rope used previously for the hang- ing of a criminal. The eye of a wolf rubbed upon a diseased (Continued. on. page 13) Modern Mechanix and

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Electric Violin Stas No Sounding “Board Below is a close- up view of the Magnetic pick- up removed from its hous- ing underneath the bridge of the violin. This device converts vibrations of sounds into electrical energy for amplifica- tion and repro- duction over the speaker. Cellos, guitars, ukuleles are similarly equipped. Keeping Birds From Flower Beds SAN ANTONIO, TEXAS, amateur. gar- dener has devised a simple stunt to keep sparrows and other birds away from his flower beds. He places a stick in the ground on each side of the bed and ties a string between them, as illustrated in the photo below. From this string he hangs other strings about ten inches long, to which are tied small pieces of bright tin or other metal. The metal pieces flutter in the air and keep the birds frightened away, the device at the same time being somewhat ornamental, too. Best results will be had if you keep the metal bits polished brightly at all times. Pieces of broken mirror are suitable. Predatory birds are frightened away by small pieces of tin attached to string depending from string hooked to posts. Inventions for August A recital being given with one of the new violins and cellos. Output of the pick-up is here seen utilizing amplifier and speaker of ordinary home radio set for reproduction. Volume from violin fills auditorium. A VIOLIN that has no sounding board has made its appearance in the musical world. Instead of the usual tone chamber, this violin has only a light skeleton frame, but concealed under the bridge is a small pick-up of the electro-magnetic type. When the violin is being played, the vibrations of the string and bridge are con- verted into electrical energy by the pick-up and this energy is then carried into an am- plifying unit and a loud speaker. On the amplifier a variable tone and vol- ume control changes the timbre and gener- ates a volume that fills an entire auditorium. Cap on Paste Tube Can’t Get Lost ODERN MECH- ANIX AND IN- VENTIONS Needed Inventions depart- ment has borne fruit in a unique tube cap which is now being mar- keted. Shown at the right, the cap unscrews like its brothers, but will not come off and get lost. When screwed down tight, the opening in the top is closed, but when untwisted, the tip opens to permit the outflow of paste, cream, etc. Screwing down cap closes the opening, unscrewing opens tip. 59

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Self-shifter on Popular Car Eliminates Gear Shift Lever To start popular new car without gear shift lever, driver simply moves the selector on the dash, releases the clutch and steps on the gas. “Low,” “second” and “high” is then thrown in automatically as the car gains speed. Proper Hand Position for Driving HE correct way to hold the steering wheel of an automobile when driving is specified as the “twenty minutes past ten” position by the National Safety Council. This means that the driver’s left hand grasps the rim of the wheel at about the place of the ten o’clock hour figure on a clock dial, while the right hand grasps the wheel about where the clock’s minute hand stands at twenty minutes past the hour. There is no time magic in these posi- tions. They merely are the places where each of the hands has the most desirable leverage on the wheel in case of sudden emergency and where the driver’s bodily position is likely to be safest and most suitable in other ways. Also, these posi- tions bring right hand close to gear shift lever so this can be reached in a hurry. Drive with the left hand on 10, right hand on 4. N OUTSTANDING motor car manufac- turer is now producing a car without a gear-shift lever. To get away from a standing start, it is only necessary to move a “selector” on the dash, release the clutch and step on the gas. , The action from this point on is auto- matic and the car is said to move forward with the silence and smoothness of a steam car, as the new device progressively selects the proper ratios to synchronize with the car’s momentum. The device is said to function perfectly, all the way from a snail’s pace to maximum speed, with infinitely more consideration of the engine than 99% of drivers have. The absence of the gear-shift lever also provides more room for driver and passengers. New Sparkplug Is Self-cleaning CONTACT CAP Above is seen the new self - cleaning sparkplug ready for installation. Drawing at right illustrates construc- tion and operation. Feed pipe passes a small amount of gas into the chamber before each spark. Constant ignition of this gas keepsthe interior clean and Prevents accumu- lation of carbon. Ace sparkplug now on the market is said to be self-cleaning and to outwear the automobile in which it is installed. The feed pipe passes a very small amount of gas into the chamber before each spark. The constant ignition of this gas keeps the in- terior thoroughly clean and prevents the accumulation of carbon. The amount of gas used by these plugs is negligible. They are said to actually re- duce gas consumption by insuring a steady flow of power from all cylinders. They can be quickly installed in any ordinary motor. The plug acts as a primer and it is not necessary to use choke in cold weather. Modern Mechanix and

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Economic Science Explains the Meaning of Inflation EVERYBODY’S TALKING ABOUT IT—HERE’S WHAT IT IS: How Inflation = _ The effect is to lower the per- is Accomplished chasing power of the dollar 3 : eres $ ee BD 2 Overissue of Te, +> , paper money -25o -~ ie fe cr e Increase in “hS ‘Silver money cas. — = es al ž This makes it easier for the debtor to pey off his debts in dollars worth -say 75 cents X T Wages and salaries do hot rise as fest as prices - creditor Who loses by Inflation? The wage earner - until wages ‘catch up to prices -ənd | everybody with money on deposit -in hend -or in invest- _tments making a fixed cash Who gains by Inflation? . Corporations with lerde —~ bonded indebtedness = heavily bonded cities - life insurance ~— companies -railroads - agile speculators return The Gold Standard When gold, given d _ fixed “price is the Can Inflation be kept within bounds? Difficult because con: Bimetəllism -The free coinage of two metals (33 gold trolled inflation doesn't produce startlin : enough results - Inflation raises all prices propor- tionately -doesn't adjust plequalities of the price: structure. Inventions for August . Ineasure of valve of a ard. Inthe United “§tates there is but currency, the country is on the gold stand- a cents in gold back of every dollar. drive out derer. aS and silver) in fixed ratio to each other is. bimetallism. Diff-. iculty of bimetallism is in Keeping the ra- tio. constant, cheaper metal tending to 57

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25 H. P. Outboard Speeds Midget Racing Car 100 M. P. H. Billy Betteridge, of Los Angeles, starting outboard motor which powers his neat little 100 m.p.h. midget racing car. Rash Turns Negro Man White HE second negro in medical history to turn entirely white has been reported to the American Medical Association. In a case of rash which he contracted seventeen years ago, white spots appeared on his skin which have since spread until they cov- ered his entire body. Young Champs Stage Own Race NE of the high points of interest in the ‘preliminaries of the recent Indianapo- lis speed classic was a display of automo- tive. talents by the younger generation. They are seen preparing to strut their stuff in the photo below. The midget rac- ing cars are demotorized, power being fur- nished by a pusher bringing up the rear. The young speed demons, who will be the racing champs of tomorrow, get all the as of the speedway heroes they are emu- ating. TS Billy Betteridge, of Los Angeles, should be awarded some kind of a prize for the craftsmanship that went into the construc- tion of a keen little midget racing car job he turned out in his workshop. The power plant of this remarkable ve- hicle is a 25 h.p. outboard. Installed under the hood as illustrated at the left, the motor drives the bus along at an exhilarating clip of 100 m.p.h. Special mountings allow the metor to be taken out and replaced in a oat. Dimensions of interest are: Length, 7 feet; wheelbase, 65 inches; tread, 40 inches. The body is of aluminum, while the tail, hood and pan were made from an old air- plane cowling. Photo shows Billy starting motor of his neat little bus. Polo Has Mechanical Mounts Water sport—water polo—played on pontoon “mounts.” Water sportsmen are never lacking in ingenuity. Their latest creation is “water polo,” played on motor-driven pon- toons. Their “mounts” have a framework like a bike, except the steering mechanism, which is a single lever affair, as seen above. Budding speed demons lined up for start of race over speed way. 58 Í “Motor” is pusher bringing up rear on end of sticks Modern Mechanix and

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Oddities of SCIENCE > gs SPRANK OF A CANDLE HE GPS | ony. m X FLAME WILL [JNE UNIT OF RADON Y BANA fe A NOT IGNITE A GAS WEIGHS FOUR \Vagieee A MATCH — DIMES AS MUCH es i A (Center iscoal, ASA COMPARABLE Si bs composed of UNIT OF IRON — n : vaporized. \ Zd Sawyer Pasadena, Cal, Pe ies aran) Sherrill NS -OF SOWING BACKWARD AND : ORWARD THE SAME TIMES: oer Chawkit, eis | TE MI oo ‘led! up snows e T E E ; Say BM end aged, Ss slowly To Lae vee Slacier melts at lower ear (berg, 7 a a - tozi, ORLO. end, moving backward) ONE DOLLAR will be paid by Nic Sprank for oddities of science used on this pag& Send in your ideas—no limit to the number: of. suggestions you may make, but be sure to enclose proof of your statements. Maybe your ideas will be better than those shown on this.page—if they are, Nic Sprank wants them and will be glad to send you a check. Address suggestions to Nic Sprank, care of Modern Mechanix and Inventions, 529 South Seventh Street, Minneapolis, Minn Inventions for August $ 59

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GETTING eMore Moon’s diameter, 2,160 miles, may be vivid- ly perceived by this comparison of lunar area with area of Texas. Right is seen a sea urchin, inhabitant of Red Sea, which spawns only when moon is full. Scientists are now trying to determine whether moon is re- sponsible for this periodicity of reproduction. T IS unwise to dogmatize about the fu- ture, and hence a cautious man of science would hardly make the positive as- sertion that human beings will never visit the moon, though the difficulties involved in such a journey now appear insuperable. On the other hand it is quite safe to as- sert that, without leaving his own planet, man will learn much more about the earth’s satellite in days to come than he knows today. This.expectation is based upon the remarkable progress accom- plished in the study of the moon in recent years. Here are a few achievements that would have seemed utterly and forever impos- sible to astronomers of a century ago: It has long been realized that the lunar surface must get intensely hot during the long lunar day and intensely cold during the long lunar night, as the moon has no atmosphere—or none to speak of—to tem- per and conserve the heat of the sun’s rays. Science could only speculate, how- ever, about lunar temperatures until a re- cently invented instrument, the vacuum thermocouple, was attached to the big 100- 60 Some astronomers believe that giant lunar craters were created by terrific im- pact of meteorites striking the surface, digging huge pits, as illustrated here. Lines radiating from these craters, scientists believe, are streaks of molten rock that splashed out when monster meteorites collided with the moon, Entire surface of moon is spotted with these exceptionally large craters, similar to one in Winslow, Arizona. Modern Mechanix and

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GLOBE WITH. SILVERY. fee VEIN es Features on moon’s sut- = ae face appear in true perspective when section photo is projected on globe. This remarkable drawing shows you just how an eclipse of the earth would appear to an inhabitant of the moon. Invéntions for August On the ceMOO CALVIN FRAZER Ce When sun’s rays strike vertically on moon’s surface, temperatures immediately beneath and at edge of illuminated area vary to extent illus- trated here. With no sunlight, thermometer drops to —240 F. Atleftis supersensitive ther- mocouple which measures stellar temperatures. inch telescope at Mount Wilson Observa- tory and applied to the actual measure- ment of these temperatures from point to point on the surface of the moon. These measurements show that wherever the sun’s rays fall vertically upon the moon the surface becomes a little hotter than boiling water, while at the edge of the illuminated area the surface is nearly as cold as liquid air. When the solar rays are withdrawn during the lunar night, which is half a month long, the surface gets colder and colder until its tempera- ture is probably as low as 240 degrees be- low zero Fahrenheit. A range of about 450 degrees between midday and midnight is one of the reasons why human visits to the moon are appar- ently impossible! Though bygone astronomers did not be- lieve the moon to be made of green cheese, they did not know, as we do today, that the surface material must consist mainly of some material similar to volcanic ash or pumice. This has been proved by Prof. (Continued on page 22) 61

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Count de Prorok peering into subterranean chamber, unvisited for 20 centuries, in which he discovered priceless emeralds of Cleopatra. OR twenty centuries amazing tales of the legendary emer- alds of Cleopatra, supposed to be buried somewhere in the desert sands, have intrigued the imagi- nations of adventurers, sent them wandering over burning deserts, lured by the quest of fabled jewels once worn by the most romantic woman of all history — jewels which Antony may have given her, which she may have worn in those fabled scenes of history by COUNT BYRON de PROROK Priceless jewels worn twenty centuries ago by Cleopatra, vampite queen of ancient Egypt, have at last been found deep in the torrid, sandy wastes of the Sahara. Here the leader of the intrepid expedition, famous archaeological explorer, tells of the amazing adventures he met with on the perilous quest. that have come down to us as the most glamorous of legends. : This much was fable, but was there any basis to the legend? In years of explora- tion in desert regions, I had heard this whispered tale a thousand times, hardly daring to believe, or to hope that I might find them. But I have! In a mysterious cavern on the heights outside the desolate city of Garama I came to the end of my long hazardous quest for the hidden jewels. There after two years of scouring the torrid desert, I ended an adventure that had included skirmishes with wild desert tribesmen, tortuous treks over thousands of miles of sandy wastes, and discoveries of cities long lost to civili- zation. While the expedition worked among the ruins of the old Garamante city, I explored the neighboring territory, and came upon the dark mouth of a cave which, my guide. pointed out, held the possibility of contain- ing the long-lost gems. Ancient symbols carved on the rocks gave me the first token of my quarry. Torch in hand I crawled into the narrow opening, and after moving forward a few Modern Mechanix and

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yards, found I could stand upright. About me lay a strange breath-taking scene. The flickering light of my torch threw grotesque shadows on the walls, re- vealing rows of ancient hieroglyphics. , In the dim light I stumbled upon the remains of old household utensils and implements of war—swords, arrows, spears. Down in the midst of these objects I spied a dust-encrusted bundle wrapped in a winding sheet. I prodded it with my stick and it fell open— rotten with age. But as I thrust about seeking to de- termine its contents, an amazing scene greeted my eyes. There among some bits of broken pottery lay the object of my quest—a handful of deep-green stones. It is difficult to describe my joy as I examined these relics of antiquity and realized that I was holding ornaments that once bedecked the person of the famous vampire queen of Egypt. To make sure that I had found the gems I was seeking, I compared them with several emeralds I was carrying that I had taken a few years pre- viously from a beautiful necklace I dug out of the ruins of Cleopatra’s summer palace at Merza Matruh, where she and Antony had spent their last hours together. The Merza Matruh stones were of the same quality of the ones I had just found, so I knew I had found the long-sought emeralds. How my expedition, made under the auspices of the Italian’ Government, toiled over the barren wastes of Africa’s Sahara, makes a thrilling story. ‘Ever since I first visited Africa I had been hear- ing weird stories about the mysterious emeralds * of Cleopatra, reputed to be of fabulous value, from divers historical and native sources. It appeared that most of these stories, originally told by the ancient Egyptian, Roman and Cathaginian nobles, were still being told in the city of Ghat, far South in the desert, once the great slave center of the Sahara. With Premier Mussolini’s personal permission I was able to lead the first scientific expedition across the newly conquered Italian Libya to this legendary city of Ghat. Our personnel was com- posed of 18 men, including. ten moving picture men — mechanics, students and specialists — as well as two Arab guides. Our caravan, while it in- cluded a number of well-trained camels to be used for short trips, consisted mostly of six especially constructed French Delahaye Inventions for August Count de Prorok on his favorite camel on which he explored the mysterious regions of the Libyan desert. Below—the Prorok expedi- tion camps in the ruins of Leptis Magna, a city founded centuries ago by the great Emperor Septi- mius Severus. The explorers are the enjoying that rare luxury of desert—a bath and a shave. pem

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Expedition Penetrates 2,000 Miles I - wealth to build and countless men to de- Members of Prorok expedition unearthing ruins of Leptis agna. Note the tall stone pillars which supported roofs of the great houses of the nobles of the famous city. trucks. After months of preparation our truck section of the expedition left Tripoli and penetrated into the desert, escorted for many miles by a section of the Italian Colonial army. No mere words can adequately describe our sensations when, after a week of the most heart-breaking struggles over tower- ing sand dunes, ravines, veritable moun- tains of rock and cactus and dried up river courses, we blazed and blasted our way through to the “Dead City of Ghirza.” With perhaps a hint of pride that I hope is par- donable, may I point out that this was the first time in history that this legendary city had ever been visited by automobile? ` We could see for two days its weird, un- earthly shape, outlined tantalizingly on the horizon—so clear, so near in the sun- parched desert—and yet, so far. Imagine a dead city in majestic ruins, ris- ing out of the sands, hundreds of miles from the nearest Arab village. Without life or trees, or even known history—veritably a masterpiece of desolation and decay. . Truly this 25 century old city is a sad- dening sight today. The city does not exist any more as a living thing. Through its well laid passageways which cost untold é a nto Sahara in Search of Emeralds vise, never a living creature penetrates, ex- cept for skulking Jackals and vultures who break the silence where once marched an empire. For days we explored this most stupen- dous of all the Sahara’s half-buried cities, and in one tomb we found several magnifi- cent emeralds. Whence did they come? From the South? Possibly so. Ever further south we blazed our way. Our objective now was Garama, the most southernmost Roman ruin in the world. | Not long after departing from Ghirza, having now pushed deep into the desert wastes, we suddenly came upon many im- portant Libyan and Roman inscriptions. These indicated, to my very great joy, that we had actually stumbled upon the ancient route which had been utilized at least 20 centuries ago by the Carthaginians and Romans to penetrate the heart of black Africa... ; I hardly need say that our imaginations were inspired at finding again this ancient ‘route of the Garamantes,” one of the major objectives of the expedition—an intermi-- nable route where once passed 2 gigantic caravans which headed A towards Leptis Magna, Car- thage and Rome. ` Modern Mechanix and

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Find Ancient Caravan Route Where Thousands of Slaves Died of Thirst P ras Important discovery of the Prorok expedition was the “toute of the Garamantes’’, a route along which passed great caravans bearing treas- ures to Carthage and Rome. There were troops of gaudily arrayed elephants, cargoes of ivory and powdered gold; chariots drawn by buffalos transport- ing famous gems of the Garamantes and treasures of Ethiopia for royalty like Cleo- patra and Messalina (third wife of the Roman Emperor Claudius). This was in- deed .a_ death-dealing journey—one in which thousands of slaves perished of hunger and thirst, en route to the markets of Rome, Carthage and Alexandria. From time to time along our wearisome march we found, mummified remains of these caravans — gruesome proof of the havoc burning sands. can wreak. Some day, perhaps, I hope to achieve what others have been aiming towards for centuries—dis- cover the vestiges of the army of the Persian king, Cambyses, who was buried under a tempest of sand while marching towards the oasis of Jupiter Ammon. Meantime we continued our march ever towards the South, passing by Oeddan. Not so many miles from here (it is well nigh impossible to estimate dis- tances precisely in those vast waste regions) we made another important discovery, finding 37 idols of unknown gods buried un- derneath piles of drifting sands. Was not that an indication that we found positive evidences of a lost civilization? Now. we were Inventions for August ae ee me ES A7, MUBZUCH | Here is seen the route traveled by the Prorok expedition into the Sahara. Cleopatra’s emeralds were discovered outside the city of Garama, abandoned for many centuries. finally at Ghat, the famous sacred city, half buried in the Sahara, oftentimes spoken of as the “city of slaves” because of its ancient claim to this title. We were the first scien- tific expedition to reach this long-sought goal of archaeologists. Along with Kufra and Timbuctoo, for a hundred years this aly has been the explorer’s dream of Para- It was in the environs of Ghat, near the famous “Mountain of the Demons,” that I saw traces of oil, shining in the rays of the sun. Here the indigenous Tuareg ; ’ tribes tell in a low voice and in a su- perstitious way, from behind their eternally veiled faces, (Continued. on page 23) 65

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Stove Pipe Armorplates Legs Against Rattlesnake’s Fangs

Lengths of stove pipe worn over legs protect fishermen against deadly fangs of rattlesnakes lurking among rocks. To Bed at 8, Up at 3 for Health THe old proverb stating that one hour’s sleep before midnight is worth two hours’ sleep afterwards is confirmed by tests conducted by a German scientist. Sub- jects improved in health when they went to bed at eight and rose at three in morning. < LEAD-LIN PATIENT'S

See new in fishing equipment is armor-plated legs. The armor plate in the case illustrated in the accompanying photo is not exactly bullet-proof, but it does stay the deadly fangs of rattlesnakes that lurk among the rocks on the edge of the fishing stream. The stunt was introduced by three Ore- gon men who were not going to be kept from their trout by mere snakes. Lengths of stove pipe worn over the lower leg ren- der the lunges of angered rattlesnakes harmless, and fishing goes on unhampered. Largest X-ray Tube Fights Cancer ARKING a notable advance in the battle of medical science against cancer, the Mercy Hospital Institute of Radiation Therapy in Chicago has installed a new 800,000-volt X-ray tube, which, it is claimed, furnishes an economic solution to the treatment of the dread disease. The most powerful X-ray tube ever put into practical use, the apparatus is expect- ed to be especially effective in treating large, massive and deep-seated cancers. Radiations emitted by the tube are equal in quality to radiations from $75,000,000 worth of radium, so that X-ray equipment to care for a given number of people will cost only one-sixth as much as radium re- quired for the job. The giant tube is 14 feet long and com- posed of two sections.

The 800,000-volt X-ray tube at Mercy Hospital, Chicago. 66 Tube emits radiations of $75,000,000 worth of radium. Modern Mechanix and

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Balloon is “Sky Hook” in ‘Radio Aerial Test Artist’s drawing illustrates how vertical antenna was suspended from captive bal- loon to test directional qualities. Electric winch shown in top photo, paid out and reeled in cable. XPERIMENTS to improve broadcast transmission involve many stunts that mystify the layman, but perhaps none is more puzzling than an idea recently put to atest by KDKA engineers. The idea involved the employment of a captive balloon, from which an antenna was suspended as depicted in the accom- panying artist’s drawing. The balloon was anchored.by a cable in the usual manner. The object of the test was to determine the efficiency of a vertical antenna, and for this no more ideal “sky-hook” could be had than a captive balloon. Directional effects of this type of antenna were given a thor- ough test, but no data has yet been made available to indicate results. Home Coolers for Summer Comfort EALTHFUL, comfortable air for all kinds of interiors is fur- nished by air-con- ditioning. equip- ment now being marketed by a large manufactur- er. At left is seen portable cooler which has proven popular. Its func- tion is to cool the air and reduce the humidity on hot, sticky days. Portable f cooler de-humidifies hot summer air. Inventions for August Captive balloon employed in KDKA directional antenna test ready to be released for ascent. Spoiled beer may be restored by pouring into the cask or bottle a.small quantity of powdered chalk. Allow to remain until completely precipitated. A bit of coarsely powdered charcoal will also do- the job : satisfactorily. Syrup or molasses will re- store taste to distasteful beer. 67

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How central stenographer in Los Angeles concern takes dictation from many offices over mike circuit. At:the stenographic end of the microphone circuit over which letters, contracts, etc., are received from offices. When office door opens a light flashes on the switchboard. If occupant is out the operator takes the message. i 68 § Broadcast technique of singers is greatly improved by small auxiliary microphones placed over nose sinus and chest. It is unnecessary to “hug” the mike during performance. Once merely a device for transmitting conversations, the microphone has gtown today to an instrument of the most diverse uses. Read here how this amazingly simple, yet amazingly sensi- tive, electric “ear” can guard our coasts from surprise naval attacks, how it warns of perilous pressures at mighty dams—and how it serves with equal effi- ciency the surgeon and auto mechanic. JERHAPS the most amazing evolutionary progress of modern days, as differen- tiated from purely inventive progress, has been in the field of the microphone. So much so is this the case, that it might almost be said we are living in the age of the microphone. Far afield has the microphone gone from merely translating human voice into electrical impulses and back to voice again. In the vitals of mighty dams in the Rocky Mountains, imbedded microphones keep the observers in watch-towers constantly in touch with conditions down deep in the masonry. Earth slides under, or at the sides of, dams are heard in the microphones long before they become dangerous. Excessive pressures of water against the masonry. cause significant sounds in the microphone circuits. When the dam care- takers hear these sounds they press buttons which. open spill-ways to evacuate water until safe pressure limits are reached. 4 Modern Mechanix. and.

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How net of marine microphones strung along coast 30 miles out at sea pick up sounds of enemy ships approach- ing shore. Operator at listening station can immediately locate the fleet by zone indicators. In the surgical wards of a great hospital, surgeons and nurses bend tensely over an abdominal operation. Instead of the meas- ured voice of the nurse calling off the con- dition of the heart, often distracting the at- tention of the chief surgeon, a pulse of low, soft sound spreads through the whole room. It is the sound of the heart itself, beating over a microphonic circuit. If it slows: dangerously, or otherwise weakens, the surgeon takes appropriate steps to restore it to normal. Thus he is not suddenly obliged to stop his careful work at a dangerous point. Instinctively, he lis- tens to the beat as. he proceeds with his work, guiding his work according to the heart’s condition. The sound of the heart could be amplified until it churned with the roar of Niagara. This, however, is never done, unless by internes or scientists ex- perimenting with healthy persons. Indeed, the day is not far distant when the doctor will entirely dispense with his stethoscope, so long the badge of the medi- cal profession, and simply place a micro- ‘phone over the patient’s heart and listen Inventions for August Picturized diagram here illustrates how enemy fleet ap- proaching coast is located in war time. Sounds of churn- ing propellers are picked up by the operator at listening station who immediately transmits firing data to coastal fort. Ships can thus be spotted before they come in firing range.- 69

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Mechanics Shoot Trouble in Motor by Listening to Sounds Over Mikes ee NE R HEART Above, trouble shooting in an engine with a “mike. > Left—Heartbeats coming over speaker telis condition during operation. Oil engineer listening in with supersensitive microphone to determine if water is entering the oil pipe at any point within ite hundred feet of length. very comfortably for any significant sounds. For the examination of lungs, too, the microphone is proving an ideal instru- ment. All meaningful sounds can be picked up and accurately classified. | Plans have been prepared, in event of war, to place a first-line net of microphones all: along the coasts, so that trained men ashore may read the sounds of all ships passing. With knowledge of where our own ships are cruising, we thus can tell whether or- not enemy vessels are approaching our shores. Heavy ships, capable of carrying long-range guns, can always be thus an- nounced long before their guns come within range of our shore, and appropriate meas- ures taken to resist them. š The microphone thus eliminates thou-. 70` constantly in touch with conditions in masonry. LISTENING TATION _ SOUNDS O| JSTRAIN PICKES 7 UP BY MIKES Microphones embedded in the vitals of mighty dams keep expert observers in watch-towers ti When certain sounds indicate excessive pressure is being exerted against dam, caretaker opens spillway to evacuate water till safe limits are reached. Mikes also warn of landslides. sands of scout vessels which would other- wise be necessary. The value of this ex- pedient to a nation with a long coast line, such as our own, is manifest. The new condenser and carbon type microphones, highly refined for use in the talkies and in modern radio transmission, have made possible truly amazing applica- tions to many phases of modern life. Ships at sea are now being equipped with a thermostat and a microphone in every compartment that lies along the keel and hull. If fire breaks out, the thermostat re- - (Continued on page 137) Modern Mechanix and

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Gyro With Single Control Eliminates os 3- BLADED IS PLACED FAR \FORW Pilot has perfect control of new Cierva ’gyro at all times, even when it is flying at speed slower than that of running man. Here a package is being picked up from dropped line. REMARKABLE advance toward sim- plicity in the construction and opera- tion of the autogyro is represented in the development of a wingless plane by Senor dela Cierva, famous Spanish gyro designer. What in particular has attracted the at- tention of aeronautical engineers to the new craft is the elimination of the usual controls, namely, ailerons, elevators and rudders. Instead of these elements, the ship Inventions for August STREAMLINED HUB- HOUSING CONTAINS CONTROL MECHANISM FOR TILTING ROTOR NORMAL DISTANCE BETWEEN CENTERS OF LIFT & GRAVITY TILTING ROTOR IS SOLE MEANS OF CONTROL OLD STYLE 4-BLADED a ROTOR WITH EXTERNAL BRACING WIRES Yaa TRIMMING FLAP (ONE SIDE ONLY) FIXED FIN IN PLACE OF USUAL RUDDER TAIL WHEEL „FOR STEERING ON GROUND ahe} THE EFFECT OF TILTING — Efe) ~ -| THE ROTOR IS TO ALTER A NORMAL DISTANCE BE- TWEEN THE CENTER OF LIFT AND THE CENTER OF GRAVITY...AS THESE POINTS ALWAYS STRIVE TO REMAIN CONSTANT, THE NET RESULT WILL BE THAT THE MACHINE AUTOMATICALLY TENDS TO FOLLOW ANY CHANGE MADE IN THE POSITION OF THE ROTOR......- CENTER GRAVITY CENTER OF uer Atei Drawing illustrates how tilting the rotor puts plane into a climb or dive. Tilting rotor to right or left banks the plane to right or left respectively. Lever is only control on ship. has a single joy stick with which the pilot can tilt the rotor in any desired direction, giving perfect lateral and directional con- trol. How the banking, climbing and diving maneuvers are performed by manipulation of the control lever is shown in an accom- panying drawing. To bank, the pilot tilts the rotors downward on the side toward which he wishes to turn. The body then swings around until the lift line passes through the center of gravity. Another outstanding feature which won approval of the aviation world was the take-off of the machine. When fully loaded and taking off in a dead calm, the plane gets into the air after a 25-yard run, and when lightly loaded with a five-mile breeze, it can take off with a 15 ft. run. Other noteworthy points of interest about the craft are: It is powered by a 100 h.p. Armstrong-Siddeley “Genet” motor, and attains a top speed of 100 m.p.h. 71

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Here’s Gondola That May Set New Stratosphere Record air. the ascent. Jean Piccard, brother of the stratosphere record holder, inspecting gondola in which he will seek to establish new altitude record, ascending from Soldier’s Field, Chicago. Re-silvering a Telescope Mirror WICE a year half a dozen men must spend two days and nights spreading the equivalent of a silver quarter over the face of the largest telescope mirror in the world, that of the 100-inch telescope at the Mount Wilson Observatory in California. The Jayer is less than one-hundred-thou- sandth of an inch thick, and is deposited on the glass by mixing a solution of silver with rock candy, forming metallic silver which adheres tightly to the glass. Restoring Typewriter Tampon HE tampon of your typewriter—that rub- ber-covered cylinder which the keys hit and which fre- quently becomes pitted and hard— may be made al- most as good as new with a piece of very fine sand- paper tacked over a wood block. Hold the sandpa- per against the tampon and turn the knob until the rubber is worn : Turning tampon against sand- ` paper smoothes rubber surface. 72 softens .tampon. smooth. This also. ERY soon now the stratosphere will receive another visit from the earth. Hoping to beat the altitude record of 10% miles established by Prof. Piccard in his flight into space, Lieut. Commander T. G. W. Settle, of the U. S. Navy, and Jean Piccard, brother of Auguste, the record holder, are making preparations for a journey into upper This time Chicago is expected to be the scene of The gondola which will house the stratosphere expedi- tion is seen in the accompanying photo, topped by Jean Piccard. It weighs 200 Ibs. and closely resembles metal balls previous- ly used. An innovation this trip will be a wireless transmitting outfit which will keep the world below informed of the prog- ress of the air explorers. Lathe Device Turns Many Shapes VALS, squares, triangles, hexa- gons — any shape up to 16 sides, ei- ther flat, concave or convex—can now be produced with a device that rests on the tool- carrying bridge of the lathe. With it, also, it is possible to bore, turn.and face shapes other than round. The turned shape fits so perfectly into the bored piece that light is practically ex- cluded when they are fitted together. Pieces turned from lathe de- vice which produces any shape. New Beer Truck Speeds Delivery HE heavy demand for 3.2 per cent beer has been responsible for the develop- ment of a new type of beer truck which is expected to cut in half the time of loading and delivering the beer. Shown below, the truck carries 56 barrels. In'the unloading process, when one barrel is removed from the rear platform another automatically falls into place. Operation of a lever un- loads the entire truckload of empty barrels in one minute. Barrels roll down on platform to be unloaded from truck Modern- Mechanix and

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Unusual Ideas in ‘Rustic ‘WOODCRAFT Ideal for cool refuge on hot summer days is this fresh air cabin, Dimensions are 10’x15’x9’ high, with 2’ drop of roof to rear. Roof is of old time con- struction, consisting of 4’ lengths of sapling Tree crotch forms. legs split wedge-shaped and laid shingle fashion for double-deck table. in rows, the joining between rows being covered Sides of the two tops are by small straight saplings bound to corners by trimmed with split branch- fence wite as shown. Vines add to coolness. es of small diameter. Decorative: windows for the fresh air cabin are shown here. Use any design your ingenuity suggests. This inviting breakfast nook is made by selecting bent lengths of sapling, = cutting them in halves lengthwise and fitting the halves opposite each other. Assemble parts with heavy iron nails. Purely otnamental is old man of the well. Head is hand carved from block of wood, body is wood frame covered with clothes. S Dog is made from „odd shaped branch, Rustic but sturdy bridge over artificial stream has flooring of split saplings trimmed down to canine shape, and mount- supported by crooked young tree trunks, while fence is supported at corners ed as shown, to make unique ornament. with tree crotch. Arbors in background are crooked saplings wired together. Inventions for, August . 73

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Profits in Synthetic Toadstools Something strikingly unique in yard or- naments are the concrete toad stools which a Portland, Oregon, man makes for 15 cents and sells for 75 cents to neighbors, who are glad to purchase such a novel decoration. Making the toadstools is surprisingly easy. Into a mould made from an old chopping bowl—over the inside of which has been spread a layer of old newspapers—pour some: cement, imbedding in the bottom a short length of pipe to serve as the stem. The paper forms creases in the top, while painting different shades of green and brown enhances attractiveness of the stools. They-should be “planted” in the ground in groups—which will mean more orders for you.. Servicing. Automobiles Enterprising but jobless auto mechanics wilffind a lucrative source of income in a maintenance scheme being worked by a New York ex-garage man. The plan re- quires. no shop—you call at the auto own- er’s garage and service his car four times a month. On the first call, you check the ignition; on the second, check brakes and steering; on following calls you grease and tighten up. In short, you keep the car in perfect condition. Giving each car ah hour’s work you can service eight cars a day, totaling 48 cars each .week and paying you at least $200 a month. A few hundred circulars explaining your services will help to bring you the 48 customers. It will pay you to. employ a helper. to clean interior, windows, dust body, etc., gratis. 74 A “Ohousand ‘WAYS This month Modern Mechanix and Inventions proffers another group of tested money making ideas that have - brought comfortable depression incomes to readers who con- tributed them. Look the items over carefully—one of them might be the means of solving your unemployment problem. Sharpening Razor Blades An inexpensive razor blade sharpener was the nucleus of a lucrative repeat busi- ness worked up by an ex-soldier in Creston, Iowa. At first he set a price of a cent a blade, and sharpened them right at the house. Later he purchased wholesale a large number of wine glasses which he left with the customers so they might have a receptacle in which to deposit the dull blades until he returned, thereby increasing business a great deal. Eventually he started a mail order sharpening service in addition, which kept him busy far into the night. Now he has a comfortable living from a Jong list of satisfied customers. Income for Radio Fans A radio fan living in Atlanta, Ga., capital- ized upon his hobby and now earns a com- fortable income selling old radio parts to fellow fans who “build their own” sets. Visiting all the radio shops in town, he found that each had one to two dozen obso- lete “trade-in” battery sets which they were glad to get rid of for as little as 50 to 75 cents each. Next, in his radio work shop, > he dismantled each set, salvaged all the use- ful parts, then had a radio repair man test them to determine their values. An ad in- serted in a local paper to the effect that used radio parts were for sale at a fraction of their regular prices brought $5 profit the first day. Advertising in papers in sur- rounding small towns brought his income up to $50 a week. Money in Bleaching Water Forty dollars per week is the average income of a New York city man who man- ufactures a bleaching water for clothes. His product is manufactured at home from a formula he found in Henley’s 20th Cen- tury book of Formulas and Recipes, and sells for 30 cents a gallon. Housewives found his product so satisfactory that he has been able to build up a regular route. He earns now more than he did during boom time, and is thankful he got laid off. Bantam Lunch Boxes Selling “bantam lunch boxes” to workers in factories, on construction jobs, and in offices remote from a convenient lunch room brings Edwin Delvin, of Springfield, Mass., a profit of $35 to $50 weekly. He gets around to his customers in ‘his Austin business coupe which he has converted into a veritable rolling restaurant. His equipment, occupying all space but the Modern, Mechanix and.

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TO MAKE a SHELVES FOR 2 FOOD S-BURNER GASO~ SLINE STOVE Artist’s drawing above shows con- struction of the various compart- ments of the. Bantam lunch box. driver’s seat, consists of a small 3-burner gasoline stove built across the rear inside, a smal] thermos ice box at the front, and sufficient shelves at sides and top to carry such edibles as bread, cheese, hot dogs, etc., as well as cooking and eating utensils. A small show case across the window sill displays cigarettes, candy, etc., at standard prices. Polishing Auto Headlights Cleaning and polishing headlights of autos belonging to business men, store managers, shop and factory workers con- tacted during the dinner hour is the in- genious scheme employed by an Oakland, California, man to rake in depression shek- els. Few inexpensive materials needed are denatured alcohol, a dime’s worth of lamp black and some cotton. Mixture of alcohol and lamp black is rubbed on the glass lenses and reflectors and when dry is rubbed off clean with a piece of cotton, leaving a bril- liant polish. You can carry a can of metal polish to take care of rust or deep tarnish. A charge of 25. cents per job satisfies your customer and brings you a sizeable profit. Keeping Up Vacant Houses A Seattle, Washington, university stu- dent, faced with the possibility of having to quit school for lack of finances, has con- vinced owners of vacant homes for rent that a well-cared-for appearance is as much a psychological aid in affecting rentals as it is in selling one’s own services. He found, after contacting a number of owners, that they were invariably willing to pay him for keeping up the grounds. He bought a second-hand car and necessary tools, and each evening after classes and all day Sat- urday he .mows lawns and trims hedges, visiting each-house on his list once a week. Inventions for.August Money-making Ad Stunt Thirty-five dollars a week is the profit netted by an enterprising Kentucky man from a novel advertising stunt he devised. Here’s how -you can work it. Find out if there is on the statute books in your state a law requiring hotels to have posted in each room the law governing hotel oper- ation. If this is the case, secure permission from local hotel owners to have some 8x12 in. cards printed with the law set forth in the middle. On the sides of the cards rule off about 20 spaces for advertising and sell them at $2 to $3 each to local merchants. When you’ve covered your town on this stunt, try your neighboring villages. Gather Up Pine Cones If you live in a region where pine trees srow abundantly you’ve no doubt noticed hundreds of pine cones lying around on the ground in the wooded regions. If you gath- er up these cones you can sell them to almost any forestry station for one to three dollars a bushel. It’s advisable first to con- tact your forest ranger station to get prices. A good days work, with prices fair, should bring you an income of five to eight dollars. Glass Signs for Offices Making and selling glass signs to dentists, doctors, stores, offices, etc., will bring you in a heaping handful of extra dollars. Signs most easily sold bear business names or house addresses and are about 3”x9” in size, $1.50 being a fair price. Signs of larger size can be disposed of at prices up to $5. An accompanying drawing shows how these signs are made. If you are not familiar with lettering, secure a book on the subject from the library. Lettering is made from tin foil cut out with a razor blade and pasted on with transparent glue. The bevel- 75

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: HED PLATE BEVEL A GLASS 3°x 9", Sonim WATER PROOF HOLES. | BLACK PAINT FO R:SÇREWS ERS CUT UT OF TIN FOIL WITH RAZOR ing of the glass is done with an ordinary file, and the drilling with a broken off drill. When soliciting customers you'll boost bus- iness by carrying a sample of your work. Installing Glass Windows iA factory man who lost his job at the beginning of the depression now makes a good living for his family of seven by re- pairing, puttying, and installing new glass in windows, mirrors, cupboard and book case glass doors. First he called on a whole- sale plate glass company where he obtained all the glass he wanted, provided he bought a certain quantity at a time. Armed with his wholesale list, he took orders till the stipulated quantity was covered. Then with his glass fastened to one running board and two second hand ladders on the other, he set out to install the pieces. For three years now he has been carning a good pine from a growing list of satisfied cus- omers. Circular Delivery Route Contracting to deliver circulars for mer- cantile firms at a flat rate per thousand has been the source of steady employment to many men suddenly thrown out of work by the depression. The plan usually em- ployed is to contact prospects with quota- tion of rates. A thorough canvass of business houses in your community should be the first step. Your delivery system should be planned according to districts, with the approximate number of homes in each dis- trict tabulated for the convenience of the advertiser. When merchants are convinced you are reliable, it will mean steady em- ployment. Classified Mailing List ‘Names and addresses of a mailing list are of little value unless they are classified. If for instance it is known that John Doe is interested in music and buys his supplies by mail, his name would be valuable to a mail order house publishing music. Pro- curing data such as this for a mailing list is a highly profitable job. You can obtain names by sending out circulars offering a premium to persons sending in names and addresses from their locality. Explain in your circular that you want to mail out advertising. Lists of these names with ade- 76 quate data furnished to mail order houses will bring you $1.00 to $3.50 per 500. Indexed Recipe Books A former typist now earns her living by providing the housewife with a.systematic means of keeping “pet” recipes. For $2 she will furnish a card-case, a set of twenty- five index cards, and will type on cards to fit the case any 50 recipes. Additional recipes she will do for 2 cents each. She purchases the card-cases at 50 cents each, the set of index cards at 25 cents, and the cards at 10 cents per 100. Her earnings average around $20 a week and are grow- ing, because housewives recognize the con- venience of having family recipes. Advertising for Theatres In towns where there are several theatres changing their bills twice or three times a week, a handy amusement guide can be published each week to bring you a “hard times income.” These guides are placed near cashiers in restaurants, drug stores, hotels, soda fountains, in fact, anywhere people can gct at them. On the guide are small panels in which are inserted adver- tisements solicited from beauty parlors, restaurants, taxi lines, night clubs, etc., while in the center is the current program of all the town’s theatres. It’s advisable to use colored paper and colored ink thus giv- ing a flash piece to attract the eye. Salvaging Used Containers Making a living out of cast-off pickle bottles, jelly jars, condiment containers, etc., may seem far fetched, but one woman manages to support a family of four in this way. Being handy with a paint brush, though entirely untrained, she collects these cast-off articles and decorates them to make attractive vases, lampshades, console. sets, kitchen sets, etc. Her unemployed husband makes daily visits to hotels and restau- rants in search of used containers of at- tractive contour. They are placed with florists, gift shops and novelty stores on commission. She has gradually branched out until she is now busy all the time. Start a “Worm Farm” A Canadian earns a good living in the fishing season by supplying fishermen, sporting goods stores and summer resorts with live fresh worms regularly twice a week, put up in lots of 25, 50 or 100 in card- board boxes. The worms are raised in wooden pails filled three quarters full of soil, into which is mixed twice a week a small quantity of corn meal and coffee grounds. The worms multiply so rapidly on this food that a dozen or so containers will furnish enough worms for one season. They can be sold direct to fishermen at 60 to 75 cents per hundred, and to stores at $1 per hundred. It’s advisable to make the rounds on your route each Friday morn- ing so as to provide fresh bait for Saturday and Sunday. Whitewashing Basements _ Neighbors viewing a neat white washing job done by a Wesleyville, Penn., man were Modern Mechanix and

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the first customers. in a basement white- washing business that has proven surpris- ingly lucrative. Three dollars was the price charged for each job—a price that most any home owner is willing to pay. Mate- rials, which are furnished by you, are: one ten-quart pail, a good brush, twenty pounds of white wash lime. Stock a few purse bags to put on the floor to keep it clean. Watch for Motorbike Smashups _Smashed motorcycles can be rebuilt to yield a profit by a mechanic who knows his motorbikes. Bikes that have been in acci- dents are grist for your mill, so its advis- able to keep a lookout for smashups. A Des Planes, Illinois, man who earns extra income this way recently. made a profit of $35. on one job. He bought the wreck for $15, spent $10 for repair materials and sold the rebuilt machine for $60. The overhaul- iùg took only three weeks of spare time. Basement Battery Shop An ex-garage worker, thrown out of work two years ago, now has a thriving battery business which he carries on in his base- ment. He makes the rounds of garages, junk-yards, etc., picking up old batteries for 50 cents apiece. These are then rebuilt and sold for two dollars, taking the old battery as a trade-in, which is then rebuilt and sold again. A few hundred cards passed around to auto owners will bring you a good supply of customers. The library will supply you with books on battery repairing. Help on Moving Day ` People who are moving into new homes would generally like to have someone to help them straighten up. You can take ad- vantage of this need by contacting moving companies and finding out who is moving, and then soliciting the movers, asking that for a reasonable price you be allowed to meet them at their destination, straighten up, wash windows, beat rugs, and aid in all tasks incidental to the shake-up. A Wis- consin man who works this idea averages five days work a week, Money in Rough Rock Homeowners who like to decorate their yards with rough rock walks, rock gardens, rock-lined fish pools, and rock walls will prove a lucrative source of income for you CASH FOR MONEY-MAKING IDEAS! Have you worked out some ingenious, practical way of making money, either as a full-time job or a spare time activity? Perhaps some friend or neigh- bor, thrown out of work, has used his wits to devise some money-making scheme which brings better . returns than the job he lost—-this very thing has happened so often recently that many men look on depression aó a blessing. in disguise. For all accounts . used in this money-making department of the maga- zine, payment will be made at regular rates. Contri- butions will not be returned unless postage is enclosed. Keep your article brief, and address it to Modern Mechanix and Inventions, 529 S. Seventh -F Street; Minneapolis, Minn. ` lg : Inventions for. August if you have an idle truck and can scour the countryside for rough rock. Most farmers whose lands are afflicted with boulders will be glad to give or sell them to you—any- thing to get rid of them. You can contract with your customers to provide them with oe and even build the ornamenis your- self. Profits in a Cemetery An enterprising widow supports herself and her small child by decorating graves that have become run down because of neglect. She first wrote relatives and chil- dren of the deceased, describing the un- sightly conditions of the mounds and offer- ing to care for them for a few dollars a year. A surprising number of people living far away but yet desirous of honoring the dead with a well-kept grave were glad to avail themselves of the widow’s services. She clipped the grass regularly, planted flowers, and occasionally replaced a head- stone or monument. On holidays she deco- rated the graves with wild flowers, and in general kept them in a neat condition. Income for Painters A painter who lately lost his job in Wash- ington hit upon this idea by which he could start a business of his own. With a can of varnish, a paint brush and some old rags he started out to canvass the neighborhood around his home. Calling at each house he asked if he might varnish their front doors at 25 cents each. Doing this he was able to make about $2.50 daily working 8 to 10 hours. At each house where work was done he left his name and address in case they wanted more work done. In two months his business was so good that he hired a painter and says it’s easy to make $30 weekly with a growing business. Sell Home Photographs An unemployed photographer makes enough money each week to support his family nicely. Here is his method. He takes pictures of houses, preferably small bunga- lows where it is easily seen that the owner is proud of his home. He develops the pic- -turės himself, then mounts each on a piece (Continued on page 19) TT

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echanical “Aids Make Life UltraViolet Heakh Lamp Heat-Control: Electric Plug You can convert your bridge lamp into an ul- tra-violet lamp with a special transformer and socket adapter now on the market. The sun- bulb is inserted in a special reflector which fits lamp socket. Turn of switch floods room with health-giving rays. THIS BELL WILL NOT. RING WITHOUT INSERTING DIME. —el ON WILENG BE REFUNDED TO CRAVASSERS OB | PEDDLERS : : š Inserting coin in slot of this unique lock opens door, Coin is re- funded when housewife admits you. Plate is put over slot when you go out. Labor of shelling peas is reduced to absolute minimum with this automatic sheller now on market. The peas are fed into the hopper with the left hand while the crank is turned with the right. The peas or beans roli out into the dish while the empty pods drop on the other side. Clamps to table as shown, and does a clean job of removing strings and separating peas and pods. 78. Temperature control for electric iton, percolator, heater, etc., is provided with this plug having rheostat to govern current flow, Six degrees of heat are at absolute control of the operator. Like everything else, bowling is being deflated too. For instance look at the photo above. Here is a midget bowl- ing alley now on the market which is lots of fun for a quiet little game at home. Its played pretty much like the regulae “ten-pin” game at the big bowling alleys. Ball is slightly larger than a baseball and it rolls back to you in a groove just as in regular game. Modern Mechanix and

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Shifting nozzle on this new hand vacuum cleaner converts it into a de-mothing blower. Bread Slice Gauge : This handy little invention attaches to the bread knife and enables you to „cut. even slices of bread of any de- sired thickness quickly .and easily. Cake Breaker By: using this new cake breaker, you can divide the most delicate angel food cake into thin perfect slices without even cracking the icing., The prongs are inserted down into the. cake, the breaker is :twisted slightly, and presto! the piece comes away intact, without-a crumb turned the wrong way. Durable prongs refuse to bend under. heavy use. Inventions. for August “Temperature Pen Indicator Indicator has a dial which tells temperature of any room, base- ment, garage, etc., by turning knob to room in question. Drain Cleaner Recently made available to housewives, this drain cleaner shown above opens up clogged drains by water pressure, doing job more thoroughly than hand suction pumps, it is claimed.. It comes with different attachments which per- mit. its use. in kitchen sinks, bath tubs, etc. May. be attached to any type of faucet. i

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Coaches Are Waiting Rooms on Non-stop Railway Project: No-delay railways promised with de- velopment of scheme to hook passen- ger cars onto reat of onrushing trains. FOR NEXT TRAIN Passengers wait in coach for their train. station master launches the car down incline as illustrated. When it passes U. S. Had World’s Hottest Spot HE United States may possess, after all, the hottest spot on earth. At Furnace Creek Ranch, in the famous Death Valley, regular weather records have been. kept since 1911. The hottest day recorded was July 10, 1913, when the temperature reached 134 degrees. Nine years later, however, French ob- servers at Azizia, on the edge of the Sa- hara Desert in Africa, recorded an air temperature of 136 degrees, two degrees above the Death Valley record. However, the weather station in Death Valley is 98 feet above the Valley’s bottom. Accord- ingly the deepest part of the Valley prob- ably is several degrees hotter than the weather station—at least 137 degrees. Grapefruit Conquered at Last T LAST the grapefruit has been conquered. The weapon em- ployed in the con- quest is an brella spoon,’ shown at left, which automati- cally opens into a large shield when you gouge down into the meat of the fruit. When youraisethe spoon to your mouth the shield closes. Umbrella-shaped shield opens to protect you from grapefruit. 80 Launched with precise timing, the coach rolls down into main line just at right moment to hook onto the speeding train. ue elimination of railroad waiting sta- tions and station stops is the object of a striking scheme devised by French en- gineers. How the scheme operates is dem- onstrated in the accompanying drawing. - Instead of fretting and fuming in a rail- road station, the people waiting for their train take their seat in a passenger car waiting on an elevated side track. Then when the train comes along, the station master releases the car, which slides down an inclined track. Momentum carries the car onto the main line, where it couples onto the rear of the onrushing train. Converts Sew Machine to Jig Saw Te rear guard of the jig saw puzzle fans will be interested in an attachment which hooks to a sewing machine to con- vert it into a jig saw. The device cuts wood up to % inch thick and can be in- stalled or removed in a fraction of a second. Attachment for sewing machine converts it into jig saw to cut out jig-saw puzzles. Handles wood up to %4’’ thickness. Modern Mechanix and

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“Radio Divining Rod Finds Historic Treasure METAL DETECTED, BY BUZZ IN “PHONES Operation of the treasure finder is illustrated here. Long radio waves radiat- ed from the transmitting coil penetrate the earth, and when. they strike metal objects they are re- radiated and picked up by the receiving coil. Presence of metal is registered in the phones by a distinct tonal buzz. Amplifier and battery are tarried by an assistant. MoPEEN SCIENCE has joined with the historian in providing a simple fool- proof, portable instrument that eliminates guesswork in locating historical relics, buried treasure, and other hidden metallic objects. The device, which has already been em- ployed with astonishing success in a num- ber of projects; was developed by Prof. R. B. Abbott of the Purdue University physics department. It is in reality a sim- plified sending and receiving outfit with which the operator “feels” out the ground. _During the feeling procedure, the trans- mitting coil emits a long wave that pene- trates the ground to locate the buried metal. When the wave strikes any metal objects, it is reradiated and picked up by the receiving coil. A distinct tonal buzz then sounds out in the earphones notify- ing the operator he is over a metal. The instrument proved its practicability recently when it located a number of old cannon, broken shells, and various other pieces of military equipment which had been abandoned back in 1775 by General Braddock when he was compelled to make a.hasty get-away from the Colonial army. Inventions for August Broken shells, horseshoes, and old guns unearthed after being located by finder. OO WEST VIRGINIA | MD Prof. R. B. Abbott, inven- tor of the treasure finder. 7 ERADDOCK ik DUNBARS CAMP MD Map above shows locale of treasure find — Dunbar’s camp where Gen. Braddock made hasty retreat, leav- ing cannon, shells shown at right. Pencil Carries Own Tablet ATEST in writing con- venience is a pencil that car- ries its own tab- let right along with it. This tab- let is a roll of pa- per in the top of the peneìl which may be unwound and torn off when you feel the urge to write. When one roll has been used up new filler rolls are: set in place. One roll holds 10 feet of paper. Paper unrolls from pencil: top. 8

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e*(ECHANICS Aid Art to Dean Cornwell, distinguished artist, who created the mural masterpieces along unique lines. Five full years were re- quired to plan and complete the murals, which comprise twelve paintings containing some 300 human figures. jf ie me li Si; ICG d S Making Preliminary Sketches Photographing Working Cartoon by DON BLACK It seems a far cry from mechanical engineering to the esthetic intricacies of an oil painting, but the mural mas- terpieces of Dean Cornwell just hung in the Los Angeles Library would have been impossible if the mechanic and artist had not worked hand in hand. Methods em- ployed in fabricat- View of the Los Angeles Central Library lobby ° e a with the Corawell muras ing these paintings in place. White lead ` binds them to the wall. are described here. EAN CORNWELL, internationally fa- mous young artist, has just completed the world’s largest mural paintings. Today they hang on walls of the Los Angeles Central Library, a colorful and arresting tribute to the esthetic genius of this man and a challenge to posterity. But of the thousands who will linger be- fore them in awe and admiration, few will ever realize that these vivid panels depict- ing the early history of California are more than an artistic triumph, that the finished work represents also a distinct achievement in mechanical engineering. For an explanation of this statement, a proper conception of the physical ele- ments involved is essential. In the first place, with a combined total area of 9,000 square feet, these murals dwarf in size the most ambitious efforts of previous masters. Four of the twelve CNY Weaving Special Canvas Step by step process of making the murals. A thousand preliminary sketches were made from living models, then these individual sketches were arranged in ordered groupings and photographed. Canvas, woven in Belgium, cost $23,000. 82 Modern Mechanix and

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Create eMural cMasterpieces Section of one of the large paintings, Colors in the origi- nals were carefully chosen for harmony with the library background as well as within the painting itself. paintings are 40 by 40 feet square, the les- ser eight panels being 20 by 40 feet. Ready for mounting on walls of the library rotunda, the smaller pictures weigh an even ton, the four major can- vasses 3,000 pounds each. More than 300 pounds of liquid blue paint was required to paint skies alone. A total of 100 living models posed for the artist’s preliminary sketches, while the completed murals con- tain approximately 300 human figures. Three scparate and duplicate coats of paint were applied as a protection against cleaning, dust, light and the ravages of time. Finally, it took five full years of painstaking, unremitting toil to complete the :task. i When awarded the contract in 1927, Cornwell’s first step was an exhaustive research to which months were devoted. When thoroughly steeped with this lore and symbolism, he went to New York and How paints were applied from a chair scaffolding moved set to work. from spot to spot by an assistant standing on the floor. ae \ Photographs of the working cartoons were thrown on the canvas by a powerful projection machine and the outlines traced in exact accuracy. Three separate coats of paint were applied to protect against dust and time. Large murals weigh 3000 Ibs. Inventions for August 83

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Single Painting Weighs Ton and a Half; Three Coats of Paint Applied In hanging the murals, they were hoisted in rolls by block and tackle, anchored at the top, and bound to the wall with white lead against which the canvas was flattened while the lead was still wet. Note intricate scaffolding employed. With the size of cach painting arbitra- rily set by the library spaces to be adorned, the artist divided his subject matter into twelve groups. Taking each in turn, his material further was segregated into de- tailed “blueprints.” He then plotted the five successive processes through which he hoped to develop his material to the fin- ished work. The first stage was that of preliminary sketching. These rough draughts were produced to ordinary drawing board size and sketched from living models. More than 1,000 of these sketches were made, another labor of many months. 84 Some idea of the proportions of the murals can be gained by comparing the background painting with the figures of the artists. At right above, a section illustrating technique. Cornwell took his sketches to London. There he worked them over into ordered groupings on the larger scale of three inches to the square foot. This was the second stage outlined. The third stage was enlargement into a “working cartoon” seven feet square. Here the drawings were completed to final form and detail. They were then photographed and reduced to camera plate inches. This idea was a complete departure from all precedent in order later to insure absolute fidelity to the true perspective of his orig- inal sketches. The next, or fourth step, carried the project into the all-important field of color. Not only must he choose a corre- lated color scheme but one completely reconciled to the library background. Com- plete harmony was of course an elemen- tary mandate. Meanwhile in Belgium special looms and workmen were weaving his virgin can- vasses. Tough, durable, of costliest materi- als, specially treated for time -resisting qualities, they were intended to be as in- destructible as human ingenuity could make them. The cost, delivered in Los Angeles, before a stroke of the brush was approximately $25,000. This is probably the top figure ever paid for artist materials. In Los Angeles the artist long sought in vain a studio both fireproof and sufficient- ly large for his purposes. He at length found a four-story wooden structure once used as a motion picture studio. But it was far from immune to fire and Cornwell’s days and nights for more than two years were harried by the fear of flames. After nearly two and a half years of pre- liminary work, however, the artist was now ready to proceed. (Continued on page 127) Modern Mechanix and

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Fortunes ‘Waiting for Inventors Three needed inventions—an econom. & i ical electric iron, a crystallized form of james coffee, and a universal pot holder. W MERICA appears to be going invention- mad. During the last few weeks a number of letters from manu- facturers and finance agencies have been re- ceived asking for new ideas. There is a great wave of stimulation go- ing on in our business and everywhere the cry is for more inventions, more clever ideas with which to start the wheels of industry. Readers are rapidly growing more conscious of this need and they are writing in great numbers asking for larger lists of needed inventions. For that reason this month we go into less detail in connection with each listing and in place of this detail list a larger number of items. , Here they are: 1. A simple little ten-cent gadget is needed with which a housewife may skim the hot grease from the top of cooking soup. Tt should be some sort of a syphon device and should work in a simple manner. 2, A method of supplying thermal insu- Jation to an clectric flat iron that will pre- vent such a large wastage of heat through the top of the iron as is now the case. If this were prevented, irons would operate with the consumption of half the current they now use. 3. A simple anti-draft attachment that can be placed on the front door windows of old cars. Something that could sell for about two dollars would make a big clean- up due to the heavy advertising of this fea- ture by General Motors. 4. A pressure gauge for automobile tires in combination with the valve. In other words, a gauge that will be sold with each tire and will permit the car driver to note the tire pressure at all times. 5. Some kind of a simple little alarm for gasoline tanks that will warn the driver when the gas is very low. The present gauges last for a short time and then fail to work properly. 6. An improved method of steering a vice on Inventions for August Money-Making Ideas Awaiting Solution Editor’s note: Questions of readers desiring ad- how to secure patents, on methods of procedure, or on ideas for inventions, will be answered when such requests are accompanied by a stamped, self-addressed envelope. send models as they cannot be accepted. Address inquiries to Patent Editor, Modern Mechanix and Inventions, 529 So. 7th St, Minneapolis, Minn. Lite > Cn 5 X X ei More fortune-making inven- tions—a slip-proof shoulder strap, a buttonless collar, etc. four - wheeled trailer when the driver of the power truck is back- ing up. Some sort of control over the front wheels of the trailer is needed. 7. A captive golf ball for practice work that when struck will tell the would-be player how long the drive would have been in yards. 8. An ammunition feed belt for machine guns that will be made of paper and cheap enough to throw away when emptied. 9. A simple goggle that will be more per- fectly ventilated and prevent perspiration about the eyes when they are worn for long periods. 10. A means by which essence of tea or coffee can be crystallized and the respec- tive beverages made by the simple applica- tion of hot water. Here is a quick fortune. 11. A universal handle for pots and kettles is needed. By this is meant a de- tachable handle that can instantly be ap- plied to pie tins, cake tins and other kitchen ware when it is hot. It should sell for twenty-five cents and will bring a big for- tune to the lucky inventor. 12. A simple electric chandelier for the dining room that may be raised or lowered over the table without the use of counter- weights. ; 13. There is needed some sort of a simple device that can be attached to the front of a baby carriage so that it will mount curb stones more easily. 14. A change making machine to be in- stalled near telephone booths so that when a dime or quarter is inserted the proper number of nickels will be returned. 15. A means of determining the amount of grease in the rear end or differential housing of a motor car without the neces- sity of removing the plug. 16. A window puttying machine that will feed the putty in a triangular strip, thereby speeding up the operation. 17. Some sort of a simple little me- (Continued on page 136) Never 85

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HANDIKINKS Aids that will help you in mechanical work about the house, in the garage, in the shop, basement work nook, or any place where new short cuts will save time and trouble, are included in these handikinks. Novel Sunlight Photography on Wood PERSON handy in working with wood can make a great many beautiful articles such as trays, panels of furniture, ctc., by taking advantage of the propensity of the sun’s rays for turning woods, such as the 5 year fir and the cimbra pine, a rich brown after a couple of weeks’ expo- sure to its rays. A pierced stencil of tin or heavy black paper bearing the stenciled design is pasted to a freshly planed piece of wood. This is clamped down to prevent warping. A two weeks’ exposure to the sun will turn the exposed portions a rich brown. The design may be fixed by apply- ing clear varnish.—Robt. W. Gordon. BOARD TO BE TREATED TE- CURTAIN FRAME SEASONED CLAMPS WOOD STRIPS Interesting Barometer Made From Scraps N ACCURATE forecaster of rain may be made at no cost at all from scraps available around any house. Make a rigid frame consisting of a board with two end pieces, which should be braced to prevent them from pulling inward. Bore a hole through each end piece and insert a length of wool cord, rope, tow, or any cordage. Wool rope such as is used for bath- robe strings is best. The cord should be thoroughly wet and drawn tight through the holes, and knotted at the ends. When the cord dries it will sag. When ERL air becomes moist as before a storm the rope will en ODEN S tighten.—Walter Brixius. This “Bim Gump” Ash Tray Is Easy to Make From Common Materials N a disc of wood 4” diameter by 1" thick, of plaster of Paris and mounted on the a tin collar is mounted and painted disc. A 4%” bolt is used to hold the turned white. A lobster claw, one preferably about tray down to the head and base disc. The 5” long and a nice pink color, is cut at the base is finished by gluing felt on it. Bim’s joint so it can be opened, the finger form- countenance is painted on the upright or ing Bim’s nose. This is then poured full fat part of the claw.—o. E. Olson. fc’ FILL WITH PLASTER OF PARIS X a 86 l Modern Mechanix and

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Making Artistic Portrait Masks Is Great Fun E YOU’RE in the least artistically inclined you’ll find heaps of kecen fun making portrait masks of your friends. The stunt is simplicity itself, and makes use of only three materials—a basin of water, a little cold cream and a roll of gummed paper tape like druggists use in sealing packages. First coat the vic- tim’s face with cold cream, then dip the paper tape in water and apply to the skin as illustrated. The moisture makes the tape perfectly pliable. When the first layer is put down, the second layer of paper is added, the mask constantly being moulded to the shape of the face. When completed, the mask is removed gently and allowed to dry, after which it will hold its shape permanently. Finish the mask by painting in lips, eyebrows, warts, etc.—R. A. Neiss. Novel Serving Trays for Bridge Guests OUR attractive serving trays in triangular shape, which form a compact square when placed to- gether, can be made easily with plywood and mould- ing. Cut a 29-in. square of 3/16-in. plywood, and then quarter it by diagonal cuts. Smooth the edges and fit half-round moulding, rabbeted as shown in the sectional drawing, around the edges. Corners are mitered and the pieces then glued to the plywood. varrouno| The trays should be thoroughly sandpapered and finished to suit individual taste. A black lacquer, following a wood filler, and several coats of shellac properly smoothed with steel wool makes a striking finish. A decalcomania design in each tray adds an effective note.—Earl Boynton. Iron Wheel Makes Camp Stove } sel ve TE drawing at the right shows you how ) you can make a simple camp-stove from a discarded iron wheel and axle. Heavy wires are threaded between the spokes to form a grill work on which to set cooking utensils. Hub is driven into ground.—James Mason. METAL GUIDE we) STRIP unch Model Planes UST as do powerful hydraulic catapults launch hydroplanes from ships at sea so will this little catapult launch your model plane. The baseboard of the catapult should be about an inch wider than the wheels of your plane, and about three feet long. From another board of the same width, saw a wedge, then nail the two pieces together as shown in the drawing. Cut the stop blocks from soft pine to the shape of the wheels of your plane and attach them to a guide strip made of heavy galvanized iron. Finally at- tach the rubber bands, and nail on the stop- ping piece. To launch a plane, place the wheels in the blocks, and wind up the pro- peller. At the right moment release the tail and propeller and let ’er fly into the air.— Dale Van Horn. Inventions for August 87 A~ | Catapult to La BASE’ PI ECI

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60 OHM RADIO RHEOSTAT ON DASH GROUND To FRAM 16 GAGE À | GR ARMORED 2 e EL OUND LEAD OF GEN, FIELD `X WIRE COILS Knob on Dash Adjusts Charging Rate CAR battery has to stand some heavy punish- ment, but not if you utilize this little kink, which permits you to adjust the charging rate by the twist of a knob on the dash of your car. On the dash secure a substantial radio rheostat and from its terminals run two leads of armored wire, one to the ground and the other to the generator lead that grounds the field coils. This hook-up puts the rheostat in series with the ground lead, and permits you to adjust the charging current. Inci- dentally set third brush on generator to maximum charging and lock it there. When rheostat is at minimum your battery gets maximum charge and vice-versa.—C. Meier. Ground one side of rheostat and run other side to genera- tor. Twisting knob -adjusts charging rate. Suction Pump Tests for Loose Bearings, Wrist Pins THE next time you have your engine head off try this stunt to test for loose bearings. A suction pump of the type used by plumbers is worked up and down in the cylinder. If the piston can be moved up or down the least bit by this stunt, you may rest assured that either the bearing or the wrist pin 4 is loose. How the pump is handled is shown at the right. §& z —aAvery E. Sewell. s A Keep Wiper Going W hen Car Stops RESERVOIR tank inserted in the wind- shield wiper line from the engine mani- fold will keep the wiper operating when you stop your car. The tank, which can be made from sheet metal, should be installed as illus- trated in the drawing. Air pressure built up in the tank while the car is running, keeps the wiper operating when the motor has slowed j l down. Pipe strapping or strips of sheet a iron will secure the tank to the rod above the motor. The tank for best results should be about two inches in diameter and about eight inches long.—George Norberg. DS am MANIFOLD TUBING RESERVOIR TO WIPER TANK AAG Wh Rebuilt Cut-out Prevents Ruination of Battery Due to` Over- charging ORE auto generators are ruined by over- charging than in any other way, so it behooves you to build this little protector from an old generator cut-out. The heavy wire winding over the cord of the cut-out is discarded, and the fine wire is wound carefully on a spool. Next the core is cov- ered with friction tape and the wire is wound back in place, the two ends being threaded through the hole in the base. Then the relay is assembled again. One end of the fine wire winding is soldered to the frame base of the cut-out, while the other end is soldered to a piece of lamp cord that runs to one of the headlight wires. Then bolt the relay to the frame of the car, forming a return circuit-ground. Finally wire in the resistance (6 to 10 amperes, de- pending on charging rate) as shown in the circuit. With the connections all made and the headlights of the car turned on, the generator is set for the high charging rate desired. In this circuit there is always the 88 same amount of charge to the battery, re- gardless of whether you are driving fast or slow or whether the lights are on or not.—Emil J. Novak. FROM SWITCH | BASE OF CUT-OUT SCREWED T FRAME OF CAR AS ® RETURN : HEAD-LIGHTS Modern Mechanix and

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Pin Keeps Hammer Handle Tight on Head AMMER handles, when they grow old, have a way of flying off and thus constituting a menace to life and property. Here’s a simple way to keepthem on and keep them thataway for a long time. first drill an %-in. hole diagonally through the end of the handle as illustrated in the accompanying draw- ing, then drive an %-in. rod through the hole_and bend over as shown. This little rod keeps the head firmly seated on the head of the hammer where it belongs. The stunt will work with any kind of ham- mer or hatchet. Another method is to drive a small metal wedge into the wood at the head of the handle. —Edward Sievers. Plane Gauge for Squaring Up Boards VERY shopman feels the need at times for a plane gauge to square up work when join- ing or dressing window frames, doors, etc. This need is greatest where power planes are not available. However, don’t despair, because here’s a kink that will take care of the job. Simply take a piece of hardwood and dress it down to dimensions 3 in. x 10 in. by % in. Then rabbet out a section 1% in. by % in. so that the plane bed will fit in the offset to insure a full edge cut. Next drill two %-in. holes through the side of the plane as illustrated in the accompanying diagram, then bore two %-in. holes through the wood gauge block to correspond to the holes in tae plane. Bolt the wood to the plane and as- sembly is completed. When you bear down on a surface you will have a guide that will give you a square cut. When the plane is to be used for large surfaces simply remove the guide bolts.—O. E. Olson. TEL g T D. C. Batiery Charging, Light System in One g 4 ee EERE is a method for charging your storage battery : on a D.C. line whereby you can have illumination at the same time. Use the circuit shown at the left. Throwing the single-pole, double-throw switch to the bottom position will cut in the lights only, while throwing the switch up to top position cuts in lights and battery. The bulbs will be a little dimmer when charging, but there will be plenty of illumination if 100-watt lamps are used. Positive pole of the line must be hooked to positive pole of the battery. The bulbs can be located at any point where you need illumina- tron—on the ceiling, roof, etc.—just as you wish.— Johnathan Askew. HOLE BORED THROUGH HEAD AND NAIL INSERTED STOVE - BOLTS Device for Sharpening Long Blades Puts Keen, Even E A Noth of cold rolled shafting. slotted with a ‘A B V-groove, makes a fine guide for sharpening long CHCLAMPSHI i ET shears, knife blades, etc., which must have an even 9 Z bevel to provide a satisfactory cutting edge. As illus- trated in an accompanying drawing, the knife is held in place by C-clamps secured to a small wooden plat- f 5! dge on Cutlery form. A 1x2 in. stick, with one end placed in the V-groove of the shaft, braces the blade for the cutting job.. Round the edge of the stick and grease the groove PRE and you will find that you can get a keen edge on your cutlery.—Weston Farmer. Inventions for August 89

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An Optical Toy for the Kiddies ERE’S one of the oldest forms of the cinema— an optical illusion which you can make for your children with very little trouble. It was used in physics classrooms in the seventies to illustrate the well known phenomena, “persistence of vision.” Take a fairly stiff piece of cardboard and on one side of it, in the center, place a picture of an empty bird cage. On the opposite side draw a bird, or a parrot, or some fitting object. When the card is spun between two tightly wound strings the bird will appear to be imprisoned in the cage. Other types of action you can invent readily yourself, and have no endoffun.—Geo. , S W. Davidson. An Effective Scarecrow for the Gardens À SIMPLE and effective scarecrow that will keep ISH any and all kinds of not only birds, but rabbits ORD and other rodents out of the garden or fruit and berry N z patches is easily made from an old graniteware slop Ae BROKEN MIRROR jar and a few pieces of broken mirror. The jar is [E/\== otpsiop| EMBEDDED IN given a coat of putty thinned to a paste with tur- IVER > YAR BUTI pentine and linseed oil, making the coat about one- eighth-inch thick. Small pieces of broken mirror are then pressed all over the outside of the jar. In a slight breeze, it will swing and turn, reflecting sun’s rays in all directions. These small rays strike birds in the eye and scare them away.—A. N. Waychoff. FOR those making jig-saw puzzles, the gluing of the pictures to the plywood often becomes a prob- lem. The best job can be done with a clothes wringer. Have the glue warm and also warm the plywood itself before applying the glue. Pat it down commencing at the center and radiating the pressure towards the edges of a piece of plywood. When this is done, place a sheet of waxed paper over the picture and run the whole affair through a clothes wringer with proper tension. Then cover with a piece of waxed paper, a board and last a weight.—L. B. Robbins. Entertain Party Guests With This Acrobat Booth FHE other cvening at a party the young host brought out this -acrobat booth and the effect certainly was startling. Without any apparent reason, the paper figures balanced themselves upon the thread which represented a tight wire. This acrobat booth was shown in a darkened room with the light from a flash light played upon the booth opening, thus increasing the effect. There were many guesses and ex- planations, but it took the owner to set us right about these mysterious figures and what kept them balanced on the thread. Materials needed for this booth are enough wood to make the structure, a bit of thread, some figures cut from thin paper, a few needles, rubber cement and a good horse- shoe magnet. Cut the ends, roof, front and back from thin wood and nail together. Fasten the magnet over the opening as shown in the drawing at right—-D. R. Van Horn. 99 Modern Mechanix and ` HORSESHOE ~ MAGNET

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Countershaft Bearings From Pipe Fittings ERE is the way to make excellent pillow blocks and countershaft bearings for the small electric bench tools so popular at the present time. The common shaft size is one-half inch so all measure- ments are shown for that size shaft. The bearings are composed of 4x%x1 inch pipe tees. Into the 1-inch opening is threaded a 1-inch . nipple and this is then threaded into a 1-inch pipe flange. The height can be gauged by the length of the nipple used. Drill and tap two small holes; one in the 1-inch part of the tee and one in the flange opening. These are for set-screws to prevent the parts from turning. Melt the babbitt and then pour rapidly into the top opening of the tee until the tee is completely filled around the shaft. Withdraw shaft when cool.—L. B. Robbins.

FOA POURING BABBITT NOVEL and effective way of dumping a wheelbar- row can be accomplished by mounting the body of a wheelbarrow on two extra pieces of wood which are fastened near the wheel with two bolts so the body can be swung forward and free from the handle bars, when dumping. This eliminates lifting the weight of the entire wheelbarrow. A handle for con- trolling the tipped up portion of the barrow is also shown in the drawing. This is made from strap iron and is riveted on the back of the bucket. The whole 4 arrangement will save much muscular exertion. Most Tonma 2 any old wheelbarrow is suitable for use with this POSITION S >> œn stunt—Fred W. Schneider.

HOLE FOR VENT PIPE Ik THE accompanying drawing is shown a A home-made forge that is made from an old. range boiler that is a valuable addition to any home or farm shop. The boiler is taken and cut out on the dotted lines for the forge itself, also a small hole for a cleanout for MITT ashes and a hole for the inlet of air. Also a hole is cut for a smoke pipe, which is set on the top as shown. A suitable air pipe is run in and bent up to the fire pot, shown by the dotted lines, which may be an old wash basin filed with concrete or fire clay. The opening r in abe Aotea lines leaves the BLOWER=>: opening for a throat to place work in the QLD HOT WATER < fire—A. H. Waychoff. BOILER DA Fool Proof Trouble Light Is Handy Article ERE is a light holder that may be jumped on, dropped or rolled without much trouble from the light source. Of course, you have to take that word “jumping” with a grain of salt, but it is com- fortable to know you have to work to hurt this ser- vice light. A coil spring from a lounge or any double taper bed spring will do the trick. Put the bulb in one side and the socket in another, and screw them together. It’s advisable to tape the wire to the top of the spring.—Altamount Cole.

Inventions for August 9]

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7 = 0246 ao rH 4 IEG- AAA NALS: oe = 22 =y E Pia tj iS f 7 6 YJ 4 Yok) : Se Sees panes io za “£65 SUDA LAY OUT JIG DE 8 ON WRAPPING. See wes 6 PAPER a TACKED TO Š J BASE z 2 1" SOUARES RIB PRỌFILES ElG-2 STEM JIG A 2 Ñ | A \ a H V HH JHH Ha at io H N 2 HH Hi4 z l6 7 prz FHH is 2618 16 412 10 02 10 12 14 16 1S 20 LAY OUT FOR RIB JIBS +_FIG-3 BALING WIRE: f THIS POINT (5 _4'-9" G"ARCH ff WALES i h, 200 $ xn BUNWALES = TOGETHER 15». FIG-4 = S METHOD OF 5 FORMING THE 64, = GUNWALE ENDS WHITE PINE 3°x T woe i A i E M ~M 92 A “DESERT Not a real Old Town canoe, but an amateur’s home built and very service- able “Old Desert Town” canoe is de- scribed here by Mr. Murdoch, who built one in Texas, You can do like- wise in graduating to the real thing. OR us who live where boats of any sort, even toys, are unusual, the simple joys of gliding over the smooth surface of creek or lake or bobbing over the small waves of cove or bay are experiences read about in books, or at best witnessed in some moving picture. But with mod- ern engineering and the construction of dams and extensive irrigation systems, there has come to even the desert dwel- ler the opportunity to do a little boating on his own. Naturally we don’t feel like putting out any considerable amount of labor or money on factory-built boats but we would like to have a light, ser- viceable craft of some kind to take with us on jaunts and picnics to the distant river, canal or reservoir. The duck sea- son will be around again soon and those otherwise inaccessible hideouts can be reached if we have our portable, light draft boat along. Thirty hours spare time and at most $10.50 in cash will provide the missing canoe, for which the mate- rials listed at the end of this article must be gathered together. For typographical reasons we cannot run this list here, so turn to the end of the article now if you want to learn the cost and function of the parts. The prices listed are the retail market prices for new, finished material. The cost of the canoe can be reduced, in most cases, one-half to two-thirds by the saw- ing of the different wood strips from %-in. white pine planks or other smooth- grained wood, by the use of discarded lattice or trellis work and the use of an old tent, porch curtain or tarpaulin. A similar canoe nine feet in length was built previously at a cash outlay of fifteen cents (for tacks) by using the makeshifts listed and asphalt roof- ing paint gleaned from forages into the Jeft-overs of several new houses. The cash outlay on the canoe shown in the accompanying photographs was cut from $10.50 to $5.60 by using a discarded tar- paulin, nails, wire and one quart of paint on hand. Place the barrel hoops and gun- wale pieces in water to soak. The Modern Mechanix and

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“own” (Canoe — by A. A. MURDOCH hoops will require only a tub or small pond of water but the gunwales will require a trough or ditch for entire submersion unless one end is done at a time, which was found to be satis- factory, and in which case three feet of each end is all that need be soaked. For want of anything more convenient, the rain trough under the eaves may be dammed temporarily and filled. While the wood is soaking, construct the jig for forming the ribs and bow- pieces. Lay out on a sheet of wrapping paper the cross-section of 1-in. squares and locate the points indicated by Fig. 1. The wood base for the jig may be a barn door, loading platform or rough frame made of scrap lumber. Tack the paper layout to the wood base and drive 6D nails to a depth of one-half inch at the points marked. When the hoops have soaked for at least five hours, bend them into the jigs. Three hoops are placed in form A, two in form B, two in form C, and one in form D. Two hoops remain; these are cut at the middle to make four pieces half length, which are bent all together into the bow-piece jig. When placing the hoops in the jig, alternate the thin and thick sides. This will allow more space and facilitate placing. The jig should be placed in the sun to dry for six hours. Bending the Gunwales Next bend the ends of the gunwales. If one end is being done at a time, this may be done while the other end is soak- ing. Bind both gunwales together with wire and bend by the method illustrated in Fig. 2, the center of the curve being 4 feet, nine inches from the middle of the gunwale. To hasten the drying, a tub was inverted over a gas stove with one burner lighted and the bent portion of the gunwales thrust up under the tub well away from above the flame to avoid burning the wood as it dried. Doing one end at a time does not make fast drying advantageous on the first end as it will dry while the other end is soaking suffi- ciently for bending. The same wire and form may be removed from the finished end and used again. To de- termine whether the wood is dry enough to hold its shape, loosen the wire at one end. If no appreciable loss of curve is noticed, it is safe to remove the wires. In damp climates the gunwales should be placed into fs NAIL THRE! PIECES TOGETH- CLEATED ON ff] THE | E SPACE" BET WEE! SLATS P TAAS their positions in the canoe without allowing them to lie around loose Inventions for August Construction details show simplicity of method of building. 93

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Lightness and Portability Characterize Canoe Built From These Plans Top view shows how the canoe is trussed to the side of a cae for a long trek to fishing grounds. Below you see the method of fastening the out- @ side stem over the canvas seam. CROSS SECTION =THRU CENTER The strips or rib bands are bound together temporarily with copper wire at the bow until the ribs are in. At left is shown the center section. Nail the ribs # to the keel with wt two 1-in. nails at the points marked by letters in Fig. 5 which correspond with the form letters on the jig, Fig. 1. Rib D is sawed longitudinally to provide two ribs of half width. With two 2-in. finishing nails, fasten the bow-pieces in the positions shown in Fig. 5. The nails will pro- trude slightly and should be bent over to strengthen. Screws were not found neces- sary as subsequent work at these joints provides all the additional strength required. It should be remem- bered that we want to have as light a craft as is consistent with the necessary strength, and we oe cut pee ae ; size and number o e dl md ce three frame members as much Š é i Working from the center at the keel the canvas as is advisable. cated in Fig. 3. The is tacked down at the edges and stretched with a Fi 7 sh th other two pieces are to pair of pliers as it is nailed. One works towards 1g. shows ẹ be screwed over the the ends. Mouldings are then put on over the method used in fasten- 5 seams and the tacks before final finishing. Marine i bows outside the cover- fite such as Jeffery’s “C” quality or Casco casein S the gunwales to the ing as shown in Fig. 11. glue will form good adhesives for the canvas. (Cont'd on page 130) 94, Modern Mechanix and long, as the dampness may cause them to lose their curve. While waiting for parts to dry, lay out the paddle as indicated in Fig. 4, using straight, knot- less white pine ‘‘shop lumber.” Cut out roughly with saw, hew down with hand ax or draw knife, and finish with hand knife, hand plane, sandpaper and two coats of paint. The making of the paddie occupied ap- proximately two and one-half hours. Remove the dry hoops from the jig, marking the center of each rib by the center line of the jig layout. Saw the four bow pieces longi- tudinally to make eight, six to be nailed togeth-

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eMotor Wheel Makes Shop ‘Power ‘Plant TEETH TO RECEIVE PLATE \ A= J) STEEL LOCK- PLATE \ BOLT TO Age MUDGUARD DETAIL OF EXTENSION PIVOT BOLTED INTO 2X3" UPRIGHT HEAT AND à TWIST HERE A HOLE FOR SPRING AND WIRE’ = ee Motor wheel attaches to wall by means of a pivot iron as shown. Throwing down tension lever disengages belt, allow- ing motor to idle, while letting up on lever sets machine to turning. Fan on motor shaft will prevent overheating. HOME woodworkers, ahoy! Here’s a cheap power plant for operating your lathe, jig-saw, bench-grinder, or what have you. You remember those little motor wheels that used to chug along astern a bike. Well, you can easily pick up one at most any machine “bone yard” for a dollar or two. Here’s how to put it into operation. First consult the drawing above. You'll notice that the pivot on the frame is secured to a pivot iron on studding in the workshop wall. Also you’]l notice that there is an extension arm bolted to the fender. To a hole in the end of this is attached a spiral spring and a wire leading down to the tension lever with which you start or stop the machines. This tension arm is held down to any position by catching the pin in the teeth of: a vertical plate under it. When the tension lever is raised the overhead spring pulls the motor up and thus causes tension on the belt. If you want to stop the machines without stopping the motor, pull down the lever until the belt is loosened. This allows the motor to idle. Inventions for August To start all you need to do is set the con- trols, turn on the spark, and pull down on the belt, which then is in tension. As soon as the motor starts adjust the speed and you are ready for an hour or two of work at the slight expense of a pint or two of gasoline. Anti-slump for Music Sheets USIC sheets that won’t slip on a piano may be made by running a length of No. 20 gauge copper wire along the edges and sealing it firmly in place with adhesive paper tape. Such treatment gives the music enough backbone to stand erect through- out the concert.

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How to Convert Your Band Saw Into Polishing Machine Twilled tape is fitted over discs in place of regular band saw as illustrated in photo above. Articles to be pol- ished are held against the tape as demonstrated in the inset. OU can convert your band saw into a useful polishing machine by making a “blade” out of five cents worth of twilled tape, % to % in. wide. Cut the tape at least % in. longer than necessary for passing around the wheels, to allow for splicing. You can sew or glue the joint together. Remove the regular band saw blade, guides and guards, and put the tape belt into place, tightening the tension moder- ately. Hold the article to be polished against the moving tape. Rouge or other polishing material can be used. The tape is particularly useful for buffing long, slender objects such as rods, pencils, candlesticks, etc. You may find it advan- tageous to place some kind of support be- hind the tape, so that you can employ greater pressure. This support should have smooth or rotating guides. You can purchase %-in. twilled tape at nearly all novelty or drygoods stores, six yards costing ten cents. For heavier work, you can use a woven cotton belt such as the kind sold for driving shop machinery. Endless belts of this kind can be obtained. When the job is finished the tape can be stored away and the saw returned to its position. MODERN MECHANIX AND INVEN- TIONS Editors will be glad to furnish you with necessary purchasing data, Two Simple Kinks for Developing Enlargements Too Big to Fit the Trays (ETN it is desired to make enlargements of a size far in excess of the size of the largest trays available. Development in this case may be carried out in two ways with- out the necessity of trays. By the first method, a quantity of pure glycerine is added to the developer, equal in volume to one-third of the amount -of developer used. The paper, before expo- sure, should be soaked in this solution for two minutes. The enlarging easel is then covered with a piece of oil cloth, and the sensitized paper then placed on this and the exposure made. The wet paper will remain in con- tact with the easel without fastening it in any other manner than just laying it on flat. Exposure and development will then pro- ceed together and the process can be waiched until the desired density is ob- tained, when exposure should be stopped, the print thoroughly rinsed in water, and placed in the fixing bath. It is better to expose slowly when using this method so that the development will be able to keep up with the exposure. , , Considerable. control over the print is obtained in this manner; development may be hurried or retarded in spots by brush- ing on more developer or water gently with a soft brush. By the second method, prints are made in the usual manner and after exposure are laid out on a slightly tilted board covered with oil cloth. They are then thoroughly 96 soaked with water, applied with a brush. When the soaking is completed the de- veloper is brushed on swiftly and evenly with a soft brush, first using up and down strokes and then cross strokes. Control over development is obtained in the same manner as mentioned in the first ‘method. This makes a very economical way of developing, as the amount of de- veloper required to make a large print is exceedingly small. It can be recovered if desired, and used again, though this is hard- ly worth while. Brush on developer using swift vertical, horizontal strokes. Modern Mechanix and

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Sports codel SIDECAR Js Easy to Build 1X1!" SEASONED ASH LONGERONS BE. == “| SHAPE AFTER STEAMING Ready for a long spin with a fair companion. Note the aero- nautical lines of the sidecar. ~ `, `a STEEL CROSS BODY BRACES CROSS SECTION OF BULKHEADS i REGULAR 13x Ys" oy ALUMINUM CAP > A poe SIDE CAR CHASSIS AND SPRINGS j 4 = REGULAR CHASSIS WHEEL IRON STEP ATTACHED E OLD AUTO = y E TO CHASSIS Drawing shows how sidecar body is mounted on two cross members of chassis, which can be obtained from any second hand dealer for a few dollars, if you’re a good bargainer. HERE are times when the motorcyclist wishes to have someone to share~ the joys of his traveling with him, and there is no better way of attracting such com- panionship than by owning this handsome polished aluminum sports sidecar. Very few tools are required in its con- struction, and the materials will not run to a very high cost. It is not advisable for the rider to attempt Inventions for August NT TO Above is seen the completed side- car in operation. This builder has his own ideas on decora- tion, but you. can apply yours to your own job. At left — framework of the body. Alumi- num is tacked over the longerons, and seams are covered with moulding. It’s advisable to brace the interior strongly with wire and turn- buckles. Windshield may be thin cellu- loid, framed with either metal or wood. to build the sidecar chassis. If you own a standard make of motorcycle, such as an Indian 45 or a Harley 45, you can probably buy a second hand chassis from your near- est motorcycle dealer for a few dollars. It’s advisable to select a chassis which has the mudguard attached to the chassis itself and, incidentally, make sure that you get all the fittings. The body of this sports sidecar is built with bulkheads of three-ply -veneer, while the Jongerons are of seasoned ash, properly bent by steaming and bending on a tem- plate or form constructed for the purpose. Fasten the body together with screws wherever possible, and to add strength put wires and turnbuckles across where neces- sary. The more bracing, the better. As soon as the frame has been completely assembled, it will be ready for covering with sheet aluminum, Fasten the aluminum with brass round-headed nails with fairly large heads, placed one inch apart. After one panel has been tacked on, be sure and trim it very carefully oe the edges be- fore tacking the next panel. If you want a really neat appearing job, obtain from an automobile body shop some fine aluminum moulding strips and fasten them along the seams. A polished alumi- num cap, obtainable at any hardware store, makes a neat tip for the nose. (Continued on page 134) 97

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“Orailer (arries This “Portable vi M S Ar AA hh UY YY Wye! YA WTI Wi YY MUM) ee, 7 ie 7 Le Vai Ae nnn Ns toro" wi LY ae } a ee Y [A Units of house are transported on trailer to camp site. 2x4’s underneath and on top are joined by iron rods to clamp the units into an easily shipped bundle. 2 rg" vr pee. ap r7" vee CORNER 3"'X 3" eR Assemble elements of floor and side as shown then cut down middle to form two hinged halves. Lag screws in side ate set in 3⁄4 in. holes in floor to hold house in place. HIS sturdy cabin has been designed for the fellow who wants to go somewhere and take a good shack along with him. It has the advantage that it can be slung on a trailer and taken wherever you can drive your car. . Once on the camp site, whether for 24 hours or a month, you flip the sections together and there before you stands a cabin you’ll be proud of. Beating rains can’t bother; the floor won’t sag, and with windows on each side you can regulate the ventilation to suit. The floor space is ample for 2 double beds, chairs, a small table—even a topsy stove 98 pe———— | ead AS ISEXTENSIO t h x for chilly weather. Let’s look into the busi- ness of building it. Briefly, this cabin is divided into 6 units —the roof, the two sides, the two ends and the floor. The floor, roof and ends are divided and hinged along the middle so that they may be folded to half their open area. A unique detail of locking the corners is by means of hinges screwed to the adjoin- ing surfaces. k To take the cabin apart, the center hinge Modern Mechanix and

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Knock-down (abin to (amp pins are removed, thus making this step simple and effective. Pins made from lag screws with the heads sawed off after be- ing placed, extend an inch below certain studding and the corner posts. These pro- truding pins fit into holes in the floor, locking the floor and side walls. To insure a tight fit at the ridge of the roof, a strip of canvas is nailed down under the hinges and over the roofing (if roofing is used) and this coated with hot asphalt. You'll find it advisable when making the flor to lay out your materials, then nail them together. When this is done, cut the piece down the center and apply the hinges as illustrated in an accompanying drawing. Each side is alike. For one, lay the 2 by 4 in. pieces which are 5 feet, 5 inches long on a smooth surface and after spacing them, nail on the drop siding. Note that the siding extends 1 inch past each corner post. These posts are 4 by 4 fir planed down to 3 inches square for less weight. The most practical way to install the win- dows is to hinge each sash as shown, cut- ting the opening through the side 1 inch smaller on each side than the sash. To make each sash fit quite snugly, cut and tack rubber strips (cut from an inner tube) around the four sides of the openings so that when the sash is closed, its four sides will press against the rubber. (Continued on page 134) HINGE x = ———EE Se eke le h 1! 10h 1 10” le’ gle" Gg! AN} REMOVABLE PINS HINGES `S CONNECT ON SIDES Plans for top and sides. Roof has notches in rafters to join with studding in the sides. Join hinges with pin to hold sides. Inventions for August 99

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Midgy Jr—omplete Vacation ELL, radio fans, here’s the latest in receivers. Here is a job that weighs less than four pounds including batteries. Lug it around like a camera or carry it in your brief-case, overnight bag, car pocket or even in a large over- coat pocket. It’s all the same to Midgy Jr. For local reception the only ac- cessory is a pair of headphones. For DX work you will, of course, need a coil of flexible wire for an antenna and a second short piece for a ground connection. So there you are. First clean off all tax tags, etc. from a cigar box and sandpaper the wood where necessary. Stand the box on end so the hinges are at the right. Across the box, 2% inches down from the inside of the top, glue in a horizontal partition as shown for the A and B batteries. The lower section is for the receiver parts in the circuit, which are arranged as shown in the photo and drawing. The parts can be wired with small flexible wire such as No. 22 or No. 24 cov- ered with spaghetti to insure against shorts. Solder all joints where necessary and make sure of all bolted connections. Winding the coils is a simple matter pro- vided the accompanying winding diagram is carefully followed. Use No. 24 DCC wire, winding on tube bases and using the large and small prongs exactly as shown. The ee ee large prongs are for the tickler coil connec- shown above, may tions and the small prongs for the grid coil. be carried like an Solder the ends to windings into the ordinary gamera. prongs and flood the turns with Duco camp in boat, or cement. The number of turns shown will in auto, a small suit the various bands although it may be antenna should necessary to add or subtract one or two bring in clear, turns from the grid coils to suit just the loud signals on points in the bands you may wish to reach. headphones. This is a matter of cut and try. On the inside of the cover fit in a piece of copper window screen wire for an an- tenna for local use. Connect this with a ANTENNA SCREEN ON K COVER 230 “@TICKLER COIL DETECTOR 7-9 MEGOHM GRID LEAK a 0001 FIXED CONDENSER — .000050 VAR, MIDGET COND. nE IRER L ~ A MIDGET BOOK TYPE BALANCING CONDENSER Wire up with this simple re- generative cir- ‘cuit. Tickler and grid coils are wound on old tube base as illustrated on opposite page. Tune with midget condenser and 50,- 000 ohm resistor. . 100 Modern Mechanix and 50,000 OHM RESISTOR REGENERATION CONTROL GROUND AND SHIELD

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“Receiver in a CIGAR BOX short piece of flexible wire to the antenna post on the outside of the box through a small hole for the same. Then shellac the outside of the back, where the tuning condenser and variable resistor shafts come through and press on a sheet of heavy tinfoil to cover the entire surface. Plenty of shellac will make the foil adhere nicely. Cut around every bolt and screwhead and projecting part so the foil will touch no metal part of the circuit. Then connect one corner of the foil to the ground post. This shielding is necessary to kill hand capacity that would otherwise make tuning very difficult. Put the two A battery cells (flashlight) in the case at the right and the 22%-volt B battery at the left. A suitable hold down can be made by jamming a slender stick of wood across the whole battery assembly between the sides. Then connect the A and B wires to the batteries, put in the phones and you are ready to go. As before stated, if there are no local stations, antenna and ground wires will be needed. For real portability, it is possible to coil. up some lengths of fine, flexible wire with clips on one end of each and tuck these inside the cover of the receiver. The extra tuning coils can be carried in the space above the tubes. (Continued on page 134) WIRE TIPS 4 TOGETHER CONNECTING IN TWO OR MORE PAIRS OF PHONES RESISTOR PRONG PRONG Í THESE WAVE LENGTHS METERS BARE ONLY APPROXIMATE 300-500) [JAS CONDITION OF PARTS 200-300) HAND ASSEMBLY WILL} 125-190) GOVERN USE OF COILS— 65-85 ETRY ONE ANO SEE WHAT 35-45 Ir WILL DO-THEN ANY, 16-25 DIFFERENCES CAN BE ADJUSTED IN WINDING OTHERS Diagram at right shows how patts are wired up in the cigar box. Copper screen antenna for local reception is secured. to inside of lid, and connected to the antenna post. Inventions for August Arrange parts in cigat box as illustrated in this photo. COPPER SCREEN WIRE —» INSIDE COVER HM FILAMENT |, -000050 MIDGET o

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Key Click Filter Eliminates NE of the chief problems of amateur transmitting is to keep the key clicks or “thumps” from disturbing the broadcast receivers in the neighborhood. The filter shown here seems to be very effective. It consists of two RF chokes in series with the key circuit and a fixed condenser in shunt across it, as the diagram shows. The chokes consist of from 100 to 150 turns of No. 32 DCC wire wound tightly over a 1-inch form such as a window shade roller, and cement- ed with Duco. Be sure that the condenser you use has a voltage rating at least twice that which is being used. That is, if you are using a. 500-volt plate power use a condenser of at least 1000 volts rating. Shock-proof Handle for Plugs ANT arubber handle for that receptacle plug? Then cut off about a 3-inch length of rubber tubing and run it down over the cord. Smear the edge of the plug with cement or glue and then stretch the rub- ber over it until it grips the edge all around. Allow to dry thorough- ly and then tape the upper end of tube to cord. Rubber tubing is slipped ever the wire and glued to the plug. Handy Improvised Tube Socket MANY is the time when the amateur oper- ating a transmitter cannot find a suit- able socket. Well, here’s what to do. Get a small block of wood and hollow out a place in the center. Line this with cotton and set the top of the tube right in that. Then sup- port the base, above, by means of a common hose clamp or similar arrangement. Solder or rivet the back of the clamp to an upright bracket, as shown in the accompanying drawing. Then fasten a pee-wee clip to each lead and clip these around h By SREE WEE TIED sose tpe prongs--and SR tiap there you are. A tube works just as efficiently upside down as it does in nor- mal position. The scheme works equally well with trans- mitters employ- ing high-power Hook tube into circuit with wires tubes. leading from the clip on prongs. 102 “Thumping” of Transmitter $ TO IMFD. PESEE TO Keying Ù i “CONDENSER CIRCUIT OF XMTR Transmitter “thumping” is reduced to minimum with this filter, which is hooked into the key circuit as shown here. Use condenser having rating of double plate voltage. Spool Makes Firm Shaft Connector F YOU’RE in need of a shaft connector to hook up a couple of variable con- densers, a common thread spool will do the trick nicely. Put the spools in a vise and with a hacksaw cut a wedge shaped slot lengthwise. Next drill a hole through the body of the spool and run a slender bolt through the hole, with a washer under the head and nut. Take up on the nut and the pinching action willholdthe shafts tight. In case the spool opening proves too large for the shaft you can use a little paper as a bush- ing. THREAD SPOOL CONDENSOR SHAFTS When nut is taken up, spool grips ends of condenser shafts. Simple Test for Radio Ground HEES a simple method for testing the efficiency of your ground. On a base- board mount a S.P.D.T. switch and a light socket, and hook up the arrangement as shown in the wiring diagram. Throw the switch to the side that lights the bulb. If the bulb shines as brightly as those of equal wattage in your house, your ground is fine, if it burns dimly your ground is poor and needs overhauling. SRDT. SWITCH 60 WATT BULB | E ROUND Mount parts of tester on baseboard and wire up as shown. Modern Mechanix and

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Set Up “Portable Swimpool in Back Yard OL LOE, SQUARE “SET DEEP T portable bathing pool for children is designed so that it can be set up. anywhere without damage to the lawn, or taken down easily and stored in small space. The tank itself is three ft. deep and ten ft. square, made of brown wa- terproof canvas sewn with double seams and folded at ends, as shown. A wide hem is sewn on each side for the pipe supports and there is a reinforcing gusset in each corner. In order that the bottom of the filled tank will not rest directly on the ground a substantial plank floor is provided, as illustrated. A short ladder and corner seats greatly add to the convenience of the pool. For draining, the water is siphoned out with a hose on to shrubbery or garden. The tank can easily be made two or three feet deeper, as well as wider, if desired. Drawings show how corner braces are erected to support tank. Note ends of horizontal pipes attach to fitting with pins. Inventions for August 103

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This is the Don ŅŲ> Campbell C-8 racer described below. At the important features of design of the Don Campbell C-8 dirt track racing car, which gave a good account of itself on the dirt tracks during the last racing sea- son, are illustrated in these drawings and photos. It will be noted that a standard tread of 56 inches is used, also that the wheelbase of the racer is 91 inches. In some instances the wheelbase is cut down to as low as 84 inches and in other cases it runs as high as 100 inches, for dirt track work. Note that the frame used under this racer is constructed from Model T Ford side members and cross members. Two front Tuu 104 “PLANS for for Dirt Track Competition end cross members are mounted, one of them being designed to carry the front spring Z-bracket and the other designed as an engine mount; the engine mount being 6 inches back of the front spring mount. The side members are cut off at the rear end and fitted to the conventional Model T rear cross member, which is used to mount the rear spring. The projecting ends of the BODY SILLS ARE £ x It x If ANGLES ALL OTHERS ARE 1/8" X I" xI" \ © \ GAS TANK \POSITION REAR Ng TIRES ARE N X 7X550 40" nA Modern Mechanix and

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sea OF NING, a “RACER F by RAY F. KUNS si LO E rear cross bracket are cut off. Special spring brackets are used which give an underslinging effect for the rear. The original width of the frame, that is, 23 inches, has been held to. The weight of one of these dirt track racers should not exceed 1500 lbs., the Right front wheel has no caster, left wheel having five degrees caster, for turning at speed. SHOWN BELOW ARE THE COMPLETE FRAME one shown being approximately 1400 AND BRACE PROFILES FOR THE VARIOUS STATIONS pounds. Owing forthe Piet that these cars are used on half-mile dirt tracks, it is neces- 8 c sary to give thought to their performance on this type of track. While the car must be low, it must not be too low or you will have what is known as a “floater.” A floater is a car which tends to slip away from [TOTAL H INCLUDE BODY SI RADIATOR SHELL E ; SUT STRAINER IN > = FILLER NECK. K $ : p be. zt "a HO 5 | FOR CLAMPING™ ~~ DOWN HOQD dannach aA ~ i ’ i ez = 4 Å= j AW ~~. LGAs FILLER TAP, N AND FLANGE. A RIVET TO BODY SSS IN BUILDING THIS K \, PORTION OF BODY \, CONSTRUCT WITH \ PAPER PATTERNS FIRST. ALSO BUILD IN FOUR 7 SECTIONS, TO CARAY FRONT. SPRING FRONT SPRING BUILT UP OF MODEL "T" FORD FRONT. SPRING Inventions for August 105

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Details of Chassis Reinforcement, Spring Suspension Told by Drawings BOCA METAL under you on the turns, much after the EROM SIEL TO fashion of a stone skipped over the water. m A Too much weight on the front end of a gP MooeL “T™ f racer used on dirt tracks is likely to cause the car to be carried out of its course, owing to improper distribution of load. On the other hand, the engine can be set back too far. Six inches is recommend- ed in this design to give proper balance. This car performs very well on the curves of the dirt tracks, showing that balance or MODEL "T" FRAME $ STEEL PLATE SIDES ADD TO STIFFEN FRAME ECROLLED EDGES Í MODEL "T" CROSS A MEMBER: ENGINE i MOUNT OUTSIDE LINE OF FRAME "ROSS" TYPE STEERING GEAR a BRACKET ADJUSTMENT NUT MODEL "T" FORD H MOUNT FOR SPRING BRACKET MOUNT CKET MOUN STEERING ARM E aN ; i N OF STEERING MOUNTING ' lu Borts } BP Pie D COMPLETE BODY Pyext ICONSTRUCTION AND a a, CHASSIS DETAILS Busano! /\ PDE VIEW OR a EA BONE PIECE E STEERING GEAR IN ASSEMBLY SHOWN FRONT AXLE — OVERLAND- 1925 SPRING — MODEL "T" RE-BUILT SPRING PERCHS — MODEL "A" SPINDEE BODIES — DODGE -1925 KING PINS — DODGE~ 1923 FRONT HUBS AND BEAR-, ARE DODGE-1925 ATTED FOR A fe . DAYTON WIRE WH tp Nim EEL ANETA VA an Wee SPINDLE gi Ly BODY SPINDLE meet REAR VIEW OF SPRING AND AXLE CAMBER RIGHT WHEEL 0 CAMBER LEFT WHEEL IS à STANDARD DODGE- i925. The tie-rod and radius red hook-ups are shown in the photo immediately above. Front spring suspension, spindle arm details, and method of stiffening frame are shown in the drawings. Note the taped front spring, which is rebuilt. 106 Modern Mechanix and

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Mounting of Radius Rods, Brake Cables Done With Eye to Accessibility distribution of weight is about right. It has a record of 24.2 seconds for the Cin-. cinnati-Hamilton half-mile track and 23.4 seconds for the Winchester, Indiana track. The ability to get around the track in rec- ord-making time is a question of car bal- ance. No matter how skilled the driver, the car must “handle.” The chassis of the C-8 will take any of the lighter four-cylin- der engines; in fact, has had several differ- ent engines in it. The front axle beam is a 1925 Overland BRAKE STOP PIN Immediately above is shown the disposition of the gas tank, seat and brake lever cross arm. To the right is shown rebuilt “T”? Ford rear spring, new perch and drum disc. SOME MAJOR DETAILS OF CONSTRUCTION IN CENTRAL PORTION OF BODY ARE SHOWN IN THIS PHOTO The steering wheel is set just off the center line, as shown above and in the top right drawing, opposite page. The placing of Pitman red and body frames is also shown here. Inventions for August En YY £ The brakes are external con- tracting type. This shows the cable to toggle, also upset spring and shock absorber. Note new perch for radius rod. Nt SIX LEAVES BEND END AS SHOWN MODEL"T" Foro NY IN] RE-BULT — e- S REAR-RADIUS ROD SS 7 9 B Š S Raer P REAR REAR UNDER AEs $ A N aA Roos o 5 x2" STEEL STRAP TELESCOPED AND WELDED AS SHOWN —S SS ee j ag" REAR RADIUS ROD DETAIL FRONT RADIUS 2r a» _o \ ROD DETAIL . ù MAKE ALL RODS FROM Th ll Immediately above are shown the dimensions of the front and rear radius red installations. These are all made from Ford model “A” radius rods. four. It will be remembered this axle made use of spring perches similar to the Model T and A Fords. Perches used in this case are Model A Ford. The spring itself is a Model T Ford, flattened out. It is necessary 107

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External Contracting Brakes Used for Simplicity and for Positive Action DE o © ADJUSTABLE SS=BRAKES co eee NUT ON EAR, to have the ends cut off and new eyes turned. Five leaves, in addition to the main, are used, these being tied together by means of friction tape and the “U” bolts, which clamp them to the special Z-bracket, which is necessary to support them in un- derslung position with reference to the front frame cross member. This bracket should be bent up from %4”x5’x16” steel plate with holes drilled to match the cross member and receive the U-bolts. Use a piece of steel plate 1144°x5"x%” as a filler block in the channel of the front cross member of the frame when mounting the spring. Dodge Parts Used The spindle bodies are 1925 Dodge while the king bolts are 1923 Dodge, as are also the bushings for the spindle bolts. The front hubs and bearings are 1925 Dodge fitted for the Dayton wire wheel. It will be noted that smaller tires are used on the front than on the rear, these being 18x4.50 heavy duty motorcycle tires. This is done in order to lighten the front end and get rid of any dangerous gyroscopic effect which may be set up at high speeds. The tie rod used is 1925 Dodge. The amount of caster provided is 5 degrees, while the toe-in is zero. The camber of the right wheel is zero—that is, the wheel on a level floor sets perfectly vertical with ref- erence to camber. The camber on the left wheel spindle is standard Dodge. The rea- son this design is used is to insure that the tight wheel, when rounding the turns, will tend to dig in rather than slide over as would be the case if it were provided with a standard amount of camber. The rivets are cut at the inner ends of the Model T rear axle housing tubes, where they are attached to the differential case. The brake housing and tube are rotated one-quarter turn forward and re-riveted to the differential case in that position. This provides for the underslinging at the rear. A special “U” shaped bracket is provided, 108 The torgue tube, left, is made up from portions of both “T” and “A” tubes. Lower left shows the brake cross arms and cable lever. Steering column brace is mecessary at dashboard, _This shows the way the 7 brake band is toggled for smooth and posi- tive action. Positive re- § lease is provided by the toggle. this being bolted on to the spring mounting posi- tion of the left hand brake dust shield. Use a 5%” bolt to fasten the U-bracket to the axle housing. ` This “U” shaped bracket is drilled to receive the shackle bolt, the left side being mounted to the spring end without a shackle, the bolt being passed directly through the eye of the spring and the sides of the U-bracket. The right spring end is mounted with a conventional Ford Model T perch and shackle. In order to accommo- date the Model T rear spring to this con- struction it is necessary to bend the ends of the spring. Model A Ford radius rods are used to provide the drive for the car and to keep the rear axle aligned. These are illustrated in the drawing and it will be noted that the forward end of the radius rod has been flattened and is bolted to the frame side member. Two Gear Ratios The gear ratio used is 11 - 40 on the mile track and 9-40 on the half-mile track. Special pinion gears are used so that the ring gear need not be changed for different tracks. The rear section of the torque tube is Model T, while the forward section is Model A torque tube. The propeller shaft is a Model T, fitted at the front end for a Model A universal and at the rear end for a Model T pinion. A special ball bearing thrust is provided at the front of the pro- peller shaft to keep it from floating rear- ward. These thrust bearings are variously used in automobiles and can be found in salvage shops. Two hardened steel grooved washers re- ceive the balls between them. Naturally it is necessary to calculate the desired length of the tube and shaft after the engine has (Continued on page 28) Modern Mechanix and k DETAIL OF 5 STEERING COLUMN BRAC

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The object of the cross peg puzzle is to jump the nails off the board after the manner of playing checkers, and to end up with only one nail on the board and have that nail right in the center, at hole No. 17 (see diagram). HE “cross” puzzle, as shown by the photo and drawing, is very easy to make. Yet it can be worked in only one way, and it will tax your wits every time. Take a %” block and lay out a cross three inches long and one inch wide. At half-inch intervals all the way along its face drill small holes to accommodate some light nails. These nails are put into each of the holes except the center one. The idea of the puzzle is to jump a nail over another to an empty hole (after the manner of jump- ing a man at checkers) and end up with only one nail on the board, and have that nail in the center. The solution is given in the table to the right. As to rules, there are none, except that only one nail at a time may be jumped, and that as soon as a nail is jumped it must be removed from the board. Usually you will find yourself with only two nails left, and those two too far apart to be jumped, let alone end up in the center. The second puzzle is a “jigstick”—a new version of jig saw puzzles. There is the same satisfaction in putting one together that there is with a jig saw of the flat variety. Take a block of pine about 2”’x2” by 3” long. It must be soft to saw well, as this is a rather thick piece for the little saw blade to handle. Saw off a layer on either side. Then as with a jig saw puzzle, saw off the sides into more strips. Then take the center and saw it up some more. As long as progressive slabs are themselves in turn sawed to intricate pieces, you can evolve as tough a puzzle as you care to. An interesting variation is to take minia- ture pictures and paste them on the faces of the puzzle. This will give you a four- sided jig saw puzzle with some intricate “meat” in its interior. Inventions for August SAW OFF SIDE LAYERS SECTION ee THROUGH LAYER SAW CENTER INTO LAYERS I-2-3-4 AND CUT EACH LAYER INTO STRIPS SAW SIDE LAYERS I-> INTO STRIPS —>~L) Above is shown the manner of sawing a jigstick puzzle. Below, diagram of order of jumps to work cross peg puzzle. How a jigstick puzzle looks when being put together. 109

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Here's Something New in Diving Chrills a e G new in diving thrills is provided at an Ohio bath- ing beach by a unique cable car system. The.diver climbs to an elevated platform, grasps a two wheel cable car, and takes off for a ride down the line till he comes to the end. Here he releases his grip and executes a fancy dive into the water. i How the contrivance is constructed is illustrated in accompanying drawings and photos, so that you can easily duplicate the job yourself at your favorite swimming hole. One end of the cable, you will notice, hooks to a tree, while the other attaches to the end of a pipe framework extending out over the water. The little cable car is simplicity itself. You can alter the dimensions of the car or of the framework to suit your individual requirements. Note that the beach end of the cable passes through a spring. This acts as a bumper to prevent violent shocks when me diver arrives at the end, ready for the ive. After the dive, the car is hauled back to the platform by means of the cord attached as shown in the drawings. The arrange- ment combines the thrills of roller coaster, airplane, and high-diving from a catapult! - How the diver is catapulted out into the water is illustrated in photo at top, left. In insert at left is seem a swimmer hanging onto the cable car while he speeds down the line for a dive. Erect the pipe framework as illustrated below. Note how cable is attached to tree. Pipe should be set in concrete. Swimmer grasping the cable car handle ready to take off for a thrilling plunge into the water. BUMPER U-STRAP 110 $ Modern Mechanix and

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Tennis Court Marker Makes Straight, Clean-cut LMOST any junk heap will furnish ma- terials for making this efficient tennis court marker. The lime container is a 2-Ib. baking powder can or a 1-lb. coffee can, with a good lid. In the middle of each end punch a hole with a 12-penny nail, then with a pencil mark off a strip 1% in. wide around the middle circumference of the can, and with an 8-penny nail punch this section full of holes, spacing them about % in. apart in every direction. The frame may be made from any kind of lumber, cut to the dimensions shown in the drawing. The three cross-pieces are 4% in. long. Two in. pieces of stiff wire are fastened with wire staples to the outside of the framework so that their ends come down ô in, to fit in the holes of the can. In use the can is filled half full of air- slaked lime and the lid is placed on. The two wires are pulled back slightly and the can is forced between them. The marker is then pushed over the court like a lawn mower, as accompanying photo shows. Continuous Fuse for Experiments SPOOL OF FUSE WIRE Whenever line is over- loaded in experiment, the fuse wire between the two binding posts goes blooie. All you have to do then to in- stall new fuse is pull wire through binding post holes, as shown. N CONDUCTING a series of rather dan- gerous experiments in which it was prac- tically impossible to overcome a rather rapid occurrence of short circuits, the writer built the little arrangement shown above. Here a piece of fuse wire is carried through the holes in two binding posts of the spring variety. When the fuse wire between the posts blows it is only neces- sary to run a fresh piece in place from the spool. Inasmuch as a pound of fuse wire may be bought very cheaply, this is a very inexpensive way of solving such a problem. TO 110 VOLTS ~A BINDING POSTS a Inventions for August Lines Marker is assembled as illustrated in the drawing. Can is filled half fuil of air-slaked lime, free from lumps, and rolled over the court like a lawn mower, leaving straight line. Improvised Motor Speed Indicator OT every mechanic has an expensive tachometer and yet many occasions arise where it is necessary to determine to at least a fair degree of accuracy the speed of a piece of machinery. This may be done with a threaded rod, a nut and a ruler used in the manner de- picted below. If the rod is threaded with an 8-32 die we know that the nut will advance one inch on the rod in thirty-two revolu- tions. If it advances five inches and by means of watching the second hand on a watch it is found that four seconds are re- quired for the movement, a very simple calculation shows the speed of the machine. Naturally this method has its limitations and it will be obvious that it could not be employed on real fast machinery. It is advisable to use a thin-threaded rod for measuring speed of faster shafts. Speed is determined from calculations involving length the nut travels and the number of threads to inch on the rod. Time revolutions with step watch for most accurate results. , 111

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CHOW to SBUILD a Simple Here’s an old schoolroom favorite—the cooler you used to see in physics class has been put to a practical experimental use by Mr. Cartright who shows how to build one of these simple affairs. CE boxes cool food because ice absorbs heat. As the ice melts, heat is required to raise its temperature to 32° F., the melting point. If we build a box and insulate it from the heat of outside air currents, place ice in the box, and then place food in along with it to furnish heat to melt the ice, a balance is soon struck between the meltin point of ice, which is always 32° F. an the temperature in the rest of the box. Gen- erally this is around 50° F. We make pro- vision to drain off the water from the ice tray, and presto, we have an ice box. a) CONTAINER CONTROL EE ORIP COCK BRACKET IS eee ts TO NNE CUT TOP OF CAN as VARNISH CAN TRAY CONTAINER TRAYS CONTAINING SALT AND AMMONIUM of TRAYS BUILT UP OF WOOD A couple of cans, some trays impregnated with paraffin, and a supply of common salt mixed with ammonium niteate constitute a fine ice box cooler for the summer camp, 112 Usually we think of the function of the ice box in reverse order. We think that we put food in to cool. But this is not so: there are several variations of the idea, looking at it from the standpoint of pure schoolroom physics. For instance, there are machines which will cool an ice box quite as effectively as ice itself. They work in somewhat the same fashion as ice. All of them are devices which allow gases to expand in “cooling coils.” This expansion in the coils is accompanied by a. much lowered temperature in the gas. Con- sequently the gas tends to soak up heat from the surrounding air, which in turn soaks up heat from the food in the box. As the gas travels through the coils it becomes warmed by the heat it has picked up, and it is car- ried (in mechanical types of refrigerators) to a compressor which squeezes the gas down again in volume. This also com- presses the heat to a small space, and the gas is run through a cooling coil outside the refrigerator through which a blast of air is run by a fan to get rid of the heat. Then the gas is passed to a reservoir waiting to be admitted to the expansion coil again. It is on the above principle that Frigid- aire, G-E, and other mechanical refrigera- tors work. Principles of Refrigeration Chemical, gas, or absorption machines as they are called, do the compressing chemi- cally, or by absorption of the gas into char- coal or other absorbent. While they need no pumps, there is a difference in pressures in the gases in the refrigerating system, and all such types must be of the sealed variety. That is, the refrigerating gas is sealed her- metically with the exclusion of air in a closed system of circulating pipes. Both ice itself and these mechanical re- frigerating machines operate on the same principle in an ice box. They soak up heat from the surrounding air and food. If we place food near them in a circulating space closed to outside air such as an ice box, we get an inverse result which is commonly thought of as the cooling of food. What really happens is the heating of the ice or the coil—a transfer which leaves the food in a lowered temperature. There is still a third way for obtaining lowered temperature within an ice box that is ideally suited to the needs of the camper, the motorist or the summer re- sorter who is out of touch with the supply of ice. This method is known as evaporative re- frigeration, and I am going to tell you how Modern Mechanix and

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Chemical REFRIGERATOR by JOHN CARTRIGHT to build a refrigerating unit that needs no motors, needs no heating of a ball in a kero- sene flame, and which needs no little gas pilot light to make it work. It is a refriger- ator built on the old schoolroom chestnut— “heat of solution.” You know what happens when you put alcohol on your hand? Dries up right away, doesn’t it? Feels cool too, eh? Or ether, which is even colder. Maybe you have seen canvas watcr bottles which cooled water because enough leaked through the bottle to keep the outside moist, and when the water evaporated it soaked up enough heat to leave the contents of the bottle cool. Cooling by Evaporation Now suppose we could make a unit that would take water drop by drop, absorb it, slightly change its chemical nature, and then evaporate it as though it were ether. We could have intense cold before very long, eh? Here’s just such a rig. It might cost you all of two bucks to build, too! Every high school chemistry student knows that water dripping on ammonium nitrate will cause the nitrate to go into solu- tion, and the resulting solution has a very low temperature and evaporates very rap- idly. This ċhemical ammonium nitrate is cheap too—it is merely good old fashioned farm fertilizer. Perhaps you’ve seen piles of it along the road in the fall or spring when farmers are spreading it out on impoverished fields. (Rain soaks through it and carries the nitrogen into the ground. Nitrogen is plant food.) Now if we take trays of ammo- nium nitrate, and fix it so that we can pass water through it at a rate just fast enough to allow it to make a normal solution of am- POTOM ASBESTOS monium nitrate, which will | SCHEMATIC VIEW —— OF UNIT, G DETAIL OF DRIP ROOF DRIP cock \ ROOF TRAYS Ba LOADED i TRAYS L z i? FUNNEL N TO THE BLOTTING OR immediately become cold, and then put in something which will keep the nitrate from crystallizing as it evaporates, we can put these trays in a metal box, arrange a drain, and have something nearly as good as a (Continued on page 129) BRACKET IS WELDED TO BOTH CONTAINERS Jð GA. SHEET METAL FUNNEL ALMMONIUM TYPICAL IRAY DETAIL VARNISH CAN SS ur The drain must be used to pipe off the solution which results when the water drips onto the ammonium nitrate. A drip cock trickling water on a tin roof evenly distributes the water through the top tray, whence it filters to the others. Inventions for August 113

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Ride this “Wooden Seahorse 5 m.p.h. YX 3" PRE SPROCKET YX 3)g NIPPLE -CROSS ARMS Side dimensions of the sea horse. Section through the bike sprocket shows how 34x3 in. pipe connects cranks. ROSS ARMS /— 2’% 3°X 30" = Five miles per hour is speed a good rider can make with this sea horse. Bike parts form the driving mechanism, HETHER you’re ten years old or sixty years young, you’re sure to like this novel water animal. Just watch that water REAR BIKE FORK | FR E ponTooN churn as you gallop along at a good five ewer miles per... see that head bobbing up and down ... feel that easy roll beneath your body. Start the construction by making the pon- toons, following the accompanying draw- ing. Locate the two end cross pieces so they will line up with the cross arms on the horse. The %-inch carriage bolts used for fastening are prevented from falling down into the pontoon by means of light straps of wood or metal nailed to the underside of the cross piece. The horse’s head is readily cut out on the band saw from two pieces of 1-inch stock. A large washer on either side makes the bearings, (Continued on page 135) Photo above shows horse in cutaway view. Note how the bike fork takes the paddle wheel., Hard wood cam striking against the wood piece causes the head to bob like a real horse going at a gallop. Shape the head according to the squared chart shown in the drawing and attach 34" rope Framework of the pontoon is covered first with 1⁄4” pine or with to halter. An old bike seat will serve as a saddle. sheet metal, then with heavy canvas. Wood straps hold bolts in place. 114 Modern Mechanix and

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N PIPE BEARING Z A section THROUGH Dy... TURNING MECHANISM |fear COTTER PIN COUNTERSUNK NUT as LOCK NUTS ON S/a" KING BOLT 2X4 I"MAT'L. DETAIL OF i Ý TURN TABLE DRUM Å 1y2 x24" DIAMETER Chassis of the solarium is 2x4’s triangular shaped as shown, and to it is bolted the turntable drum. The house of the solarium rotates on three casters, rotation being effected by turning crank beside the cot. Gore opens out, and roof lifts to admit sun’s rays. HOSE who have tried sun-bathing are enthusiastic over its benefits and many more would enjoy it except for the lack of suitable privacy in a sun-drenched area. Here is the design for a very complete solarium which will cover the require- ments of the most exacting sun-bather. It can be wheeled to the most desirable spot on the lawn, opened up to receive the full volume of the solar rays, and more- over kept toward the sun without the occu- pant rising from his couch. A small crank- handle in convenient reach is connected with a turntable and with a few turns al- most a complete rotation of the solarium can be made. Drawings above give general dimensions. One side opens out, with openings at the ends protected with cloth gores. The roof also can be raised to admit the full strength Inventions for August FRAME SLUNG BELOW AXLE alth in Lawn Solarium Rotated by crank at your elbow, this solarium permits the sun to be always full upon you, yet provides complete privacy in your yard. ‘BUILT-IN CANVAS COT gl SCREW EYE {2"COASTER WHEELS TRUCK CASTERS SCREWEDTO. FLOOR JOISTS ~} FLOOR PLA y H. + vo" T of the sun’s rays. There is a built-in canvas cot with the rotating crank installed be- side it. à The chassis is built on a triangular frame consisting of three two-by-fours with cross members as indicated. In the center of the triangle a platform is built of 1 in. material, and a turntable drum bolts to it. This drum, therefore, is fixed on the chassis, while the solarium proper turns around it, riding on three sub- stantial truck casters. A sectional view of the turning mechan- ism is shown. A %-in. carriage bolt serves as axis for the turntable. A wood spool secured to a vertical shaft by means of a pin carries two turns of the sash-cord cable, which encircles the large drum and is se- cured on the opposite or rear side to coil springs and a screweye. 115

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Building aSOELESCOPE for by E. WILLARD. PENNINGTON In this article Mr. Pennington shows how to polish and mount the mirror for which grinding directions were given last issue. Also the simple Foucault test is thoroughly ex- plained so you can have a mirror as accurate as the finest. E ARE describing the construction of reflecting telescopes, with particular emphasis on a 6” build himself. In the last issue we described the optical system, showed a frame, de- scribed the grinding of the lens up to the point of getting all the ma- terials and setting up for work. With a full understanding of the grinding the actual grinding may now be commenced. The surface is wetted, sprinkled with a little of the coarsest carborundum, the mirror placed in position of the tool and the “grind- ing machinery” set in opera- tion. You can soon tell by the sound and feel of the grinding when the car- borundum has ceased to cut, and when this stage is reached the charge of carborundum is replenished. We are work- ing toward a Mirror x Rubber f Sectional Vierv Either a wood frame or a metal pipe frame (as shown last issue) can be used to hold the mirror and the eye-piece of the simple reflecting type telescope. Above is shown the method of mounting the mirror on a rubber sponge. 116 $ Kneeling Pad MIRROR MOUNTING DETAIL spherical reflector having a focal length of 50 inches and such a reflector has a spheri- cal radius or center of curvature of 100 inches so in order to check the progress of the rough grinding it is necessary to pro- vide a thin metal template a little longer than the diameter of the mirror and having one edge cut accurately along an arc of 100 telescope which one can functions, Fue piere ma lagmfying Lens YA 1“Focus A ii Bracket. Ne Side View DETAILS OF EYE PECE Section The Eye Piece Hete’s a simple brass frame for the 1” focal length eye-piece which catches the image reflected in mirror. inches radius. This template should be cut as accurately as possible, so in lay- ing out its curve use a wood batten or joined laths for making the arc, rather than a string or cord as the latter would have too much stretch for exact work- manship. If the mirror tends to stick during the grinding process stop in- stantly and add water. When the ap- plication of the template to the washed surface of the mirror indicates that the right degree of curvature has been at- tained you are ready to proceed with the fine grinding. In preparation for this all traces of the previous coarser grade of abrasive must be removed from the work- ing surfaces, surroundings, clothes, hands and fingernails! At this stage as well as throughout all operations of fashioning the mir- ror the utmost need for scrupu- lous cleanliness can not be over- emphasized. The next grinding operation is performed with the Modern Mechanix and Concrete Base

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“STAR GAZING”- Par 1 next finest grade of carborundum, i.e., the No. 120. In mirror grinding, the grinding down to exhaustion of an application of carborundum and water is called a “wet.” Proceed, with as many “wets” of the No. 120 carborundum as are necessary to ob- literate the marks of the coarser No. 80 grade and then test again with the tem- plate. Continue with the No. 120 until good coincidence with the template is attained, as the succeedingly finer grades = not appreciably change the curva- ure. If your curved mirror surface is a bit too deep it can be made shallower by shortening the stroke; if it has not as great curvature as the template the cen- ter of curvature may be shortened by lengthening the stroke. When the proper curvature has been reached, “clean house” most thoroughly again and proceed with the successive stages of fine -and finer grind- ings. Each successive stage of fine grinding should involve about a half-doz- en “wets” of 5 or 6 minutes’ du- ration each; until when the No. 6F Turkish em- ery stage has been passed it sible to read fairly type through the glass. Dur- ing the fine grinding stages it is necessary to employ a more accurate means of testing for cur- vature than is afforded by the relatively Inventions for August Here is shown the method of using the simple Foucault apparatus for determining the spherical aberrations of the mirror. All that is needed in the way of materials are a light, a can, a piece of tinfoil and an old razor blade. OPTICAL SET Uo OF APPARATUS FOR FAUCAULT TEST Above is shown the diagram of the Foucault test. „If the mirror is truly spherical the pin point of light emanating from the tinfoil will appear to the eye as a bright flat surface throughout the face of the mirror. should be pos- - fine ` rough template. Wash the mirror and the tool thoroughly and dry them. Testing for Accuracy Across the concave surface of the mirror draw two or three pencil-line diameters. Lay the mirror back down on the tool and This will give very accurate results. Knife Eoge revolve it around its own axis. If the true spherical relationship has been maintained the pencil lines will rub out equally and simultaneously; if not, the higher or lower areas on the mirror’s surface may be equal- ized by changing the stroke as previously outlined. Upon the successful completion of the grinding stages the mirror is now ready for polishing. Polishing “Clean house” thoroughly again as before —more thoroughly if possible. It is a good precautionary measure to remove all sub- sequent polishing operations to another part of the shop to avoid any possible con- (Continued on page 24) 117

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cA Fifteen Dollar Greenhouse I ii) TA iy, Pe Ad) iit ty ge er Jeb ay X How to build a back- yard greenhouse that will pay for itself in short order. THE main problem in building a greenhouse is the problem of glass. If we sink our house half into the ground, we do away with a good bit of lumber, and, knock draughts and over- night temperature changes in the head. If we use old shiplap and a few 2x4s, we can hurdle that item nicely, for it costs next to nothing. And if we use what is known as “barn sash” to the mail order houses, we find we can get enough glass for $10.08 to make a 6 ft. x 8 ft. greenhouse that will give nearly forty usable feet for sprouting trays. A steady stream of early vegetables and flowers can be sprouted for later trans- planting, and we know of one woman who had a little house like this, costing about $15, who made the thing earn its original cost nearly two times over the first season. She went to a few friends and contracted to do their gardening, and dug their tulip bulbs in the fall, got them sprouted early in the spring, and charged a neat little sum for the service. This house is half sunk, a two feet by six feet by eight feet excavation being need- ed for head room, increased space. The excavation has the added advantage of keeping the day-round temperature nearly even. A good afternoon’s work, and the excavation can be sunk. Drive four posts each six feet long two feet into the corners of the excavation. On (Continued on page 126) K ‘ie I P 118 Í i ” 48X24 6 GLASS WINDOW re P B BEEE ELM Wa hn My 1 brttt p" n n Meh y ii laya EN VY W A i WITH BOARD TREADS . DOOR OF HEAVY CANVAS To save lumber and afford even temperature the house is semi-excavated. The framing plan is ultra simple. Cheap mail-order windows, costing 84c apiece, are laid over simple gutters which carry away rain water. The door is made from several thicknesses of burlap hung on a sliding rod, Modern Mechanix and

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“PLANNING a SAIL RIG for Your Boat JIB-HEAD CAT by SAM WING WO MULE correspondence has come in to the editors of good old MM that I have been asked’ to show you embryo sailors how to fix up that boat as a sailing job. : First, there are only a few types of small boats that make good sailboats. These are either old flat bottom rowboats, canoes, ordinary rowboats or the more modern broad sterned outboard boats. _ All of these can be converted to sail with little trouble. They will give very fair sail- ing qualities at minimum expense. Any other type of boat, such as a launch with- out an engine, or a flat bottom scow, can- not be converted with much success. Some sort of boat shape is needed to give decent qualities when beating to windward. Otherwise the boat will “fall off” and be good for nothing but running before the wind. Sail Area Needed From the chart you can see what amount of sail you will most likely need. There is no fast rule that can be used. On lakes where there is little wind, select your sail according to the weight of your boat, and take the next largest area. On ordinary waters choose the sail to correspond with the length of the boat. Where it blows hard, select the weight corresponding to your boat and use the area for the size under, as shown on the chart. I show the average length and average weight of boats of average build so you can have two vari- ables to base your choice of sail area on. The matter of balance is all important, and is little understood by the amateur, for all the simplicity of the thing. A good sailboat will exhibit a tendency to “come up into the wind” when the tiller is held normally. This is called “ardency.” All boats must have it to sail properly. This ardency is secured by placing the center of effort of the sail, which is theoretically taken as the geometrical center of the tri- angle it outlines, over the center of lateral resistance of the hull. Actually this works out a little different in practice, as PI short- ly explain. Lateral Resistance This lateral resistance is the underwater portion of the hull, and is the wedge against which the boat sails when wind pressure develops on the canvas. It usually, in small boats, must be equal to at least one-eighth’ of the sail area. The submerged portion of the drawing shows the lateral resistance of the boat. Where the hull itself has not enough under- water portion, as indeed few small boats have, a dagger board, center board, deep fixed keel or other area is added to bring the lateral resistance up to the required area. Now in actual practice when the sail is Inventions for August JIB-HEADED SLOOP GAFF-CAT GAFF SAIL AREAS ARE FIGURED BY OIVIDING SAIL INTO 2 A'S AREA= 5 AXB— > 10 SQ.FT ALTITUDE LINES BISECTING “SIDES GIVECENTER > OF: EFFORT: SAILING CENTER OF EFFORT STILL CENTER OF EFFORT BOW WAVE PILES UP AND SHIFTS CENTER OF LATERAL I PLANE FORWARD si TER OF LATERAL PLANE Above are shown a few of the more commonly used sail rigs. The area of a triangle is 1 base times the altitude. Below is expiained the reason that the center of effort of the sail must be placed slightly ahead of the center of lateral resistance when still, The lateral center travels forward faster than the center of the sail. Both must balance, or nearly so to give proper sailing ardency, or tendency to come up into the wind with a free tiller. “wung out” the center of pressure moves forward. But so does the center of lateral resistance, because of the bow wave thrown up as the boat heels over and travels. So the proper proportions of center plac- ing for proper ardency are found when the center of lateral resistance is placed slight- ly behind the center of effort of the sail, as this center travels forward faster than the center of the sail. (Continued on page 126) 119

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“How to ‘Build “Old Man EMEMBER the time you were out in.a boat in the moonlight, and the moon- path shone on the water, and peace and tranquillity were everywhere? In times like these it is good to realize that the woes of the world are man made; there is nothing wrong with Mother Nature. She makes the bees to buzz, and the corn to grow, the water to surge and the rivers to flow; let’s get away from it all and enjoy ourselves in spite of the Depression! Let’s take that trailer house we built from plans

TRAILER HOUSE FLOOR bonosa aa a ee eS eee

DOOR SLIDES

SCREENED

2"Xl2" Y. PINE FKA FIR T&G. CATWALK axa 4 FLOORING CORNER POST DECKING OF 2"X8" T&G, Y. PINE 2"xKB" END PIECE y le o UD ` F

CONSTRUCTION VIEW x NNR =9F_HULL SSSR SE” ny pn F HuLL 2° 6" STRINGERS __ 2"X4"STUDS

2" 8" Y PINE T.aG. SIDE PLANK ING in M-M a couple of months ago, and put a hull around her so she’ll float and then we can while away our time on some southern bayou, or lazily float down the Mississippi or Ohio or Monongahela or Hud- son or whatever stream happens to be nearest your home. Let’s go! Here’s how: The house is the same house as was fully and completely dimensioned and detailed in M-M for May. I have not shown this in repetition, for the only changes are the matter of extending the roof (now called a deck, since we’re going nautical) some six and a half feet on one end, and about five feet on the other. Under these slightly changed details we put a scow hull, which for all its simplicity has been carefully planned and is the result of experience I have gained with three other similar hulls.

ROOF, 4 PROJECTION | | <a WINDOW

HALF SECTION

The size of the hull is 22 ft. long by 8 ft. 2 ins. beam, by 24 ins. deep, It will draw about five inches of water. The details of hull construction as explained in the text apply to the middie and half section views. Note the layout is the same as the M-M Cabinette Trailer. The cabin is the same as the one described in the trailer plans which ran in May issue. 120 Modern Mechanix and

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iver” > a Scow SHouseboat by JARVIS L. STUMPF Under the ends of the roof—pardon me, I kitchen sink; lavatory, stove and toilet have should say deck, we put good old 4”x4” all been placed with an eye to trimming the fir pilaster (now called stanchions) and ship properly. If you go shifting the weights Ne ted our housebontl Due end of os boat around you will have a boat that will sit can be screened, and the other can have a Co tinued canvas pai ak Pine wn ao the rail on E ontinued on page 128) three sides to keep the fish from jumping s on deck when you keep your can of bait ~a ia ees a| Nek i wÉ S + outside, and the other side, say the port side, can be left open so you can board your yacht from a small row boat. The arrangement plan is the same as that worked out for the trailer, and I wouldn’t change it a hair. The doors slide to save space, and the ; STERN DEC UNSCREENED CANVAS ; = COVERED ` eee ae Se ee LAID IN PAINT Z HOUSE BODY 7i FROM, M.M, 4 WHEEL aman STANCHION Lee POSTS -| SCREENED PORCH -EXTEND TO SUIT. 4 TRAILING : of. oo on USE | ; f ane ; LINES INDICATE SUNK INTO HULL WALK HULL OUTLINE EEE SN COMPLETE HOUSE 4 A D'x 4" BEADED VIEW_OF KITCHE! BEE NN j = ASSEMBLY — ‘4° EXTEND CEDAR STAVING The thumb nail sketches show how attractive the interior can be made. The catwalk space of 12 ins. around the cabin is necessary for handling the boat. Elevation and isometric details show the plan of the outboard profile and how the roof of the trailer cabin is extended in the ends to make service and screened porches. Inventions for August 121

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Better Investment than old “Bonds DINING RN: ge ITCHEN vi-o 1 0-0 fk FT LIVING RM: 18-6 a 15" © SECOND FLOOR PLAN ° Floor plans for house No. 5-W-25, shown above. For complete blueprints for houses illustrated here send $1.00 to Modern Me- chanix Home Building Editors, 529 South 7th Street, Minneapolis, Minn. Two new plan books, “32 Low Cost Homes for Newlyweds” and “16 Selected Homes for Lean Purses” illustrating time, space and labor-saving bungalows, may be had for 15 cents each, or both for 25 cents, from Modern Mechanix home building editors. 122 House No. 5-W-25 is built in Colonial style—a style always popular. There are six rooms, bath and porch, which may be either open or closed. Cost of this beautiful home, designers assure, is very reasonable. by MAURICE I. FLAGG Bes it or not,.if you own a good house and lot and have built or bought them at a right price they can’t shrink over night, pass out of sight and become a flat tire like many a gold security has these past three years. Regardless of some fluctuation in the value of prop- erty, your house and lot remain the same size, they can be lived in, they are tangible, you can see them and unless an earthquake or fire wipes you out entirely the money represented in your property is safer, more secure than in many a so-called gold bond, Authorities and others predict that as we emerge from the depression, real estate and property owner- ship will prove the safest and wisest of all investments. And that’s something these days of rising prices, lower incomes and uncertainty ahead. You have in the house above (No. 5-W-25) a sum- mation of years of study and experience by practical builders in evolving what may be called a model home in room arrangement, good construction and dollar value. There are six rooms, bath and porch which may be either open or closed. If the porch is built to the rear of the dining room the house may be placed on a 40-foot lot. By slight readjustment of the second floor plan the sewing room can be made a bedroom. The house is all wood, siding painted white, green blinds ‘and green shingle roof. The style is Colonial which means that 25 years hence the style will be just as good as it was when Washington built Mt. Vernon. The cost to build is reasonable and depends upon equipment used and where you build. i

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FEY beginning collectors have not been puzzled at one time or another as to how to determine the country or origin of certain stamps, without a catalogue. Fre- quently the foreign terms used on stamps are so unfamiliar that the collector can do no more than hazard a guess as to their meaning. To make the identification prob- lem simple, the list below presents the for- cign words appearing on stamps and iden- tifies them by country. In some instances the term refers to the denomination of the stamp in foreign currencies, in other cases it is the native name for the country of origin. ADIOSUNE sosecesrsdexieratdens as Prussia ACOTES nan raaa EEE NEE Azores Algerie 1.2... ccc ccc cece eee Algeria Allemand ................0055- Germany Afehan giacig 34 hina sa sa es Afghanistan ANGOPPRE woe tei g sce ence nce ew cece deen Andorra Anna...... India, Mesopotamia, Zanzibar AUT s2c6d-ha dy hich « te as ec See stan ert ett Iceland AVOS © secs nvw taeais neni cece es iu Macao Aytomonoe .......... 0... cee eee Epirus AENTON oasa guine aiai an e a Greece Bani eisern nanan nrun Senk Roumania Bayeri osarurtraritas titia iais Bavaria Belgie Belgique ................ Belgium BOSTON) 6:8 ge tGrcadiacit. Rae Bosnia British South Africa........... Rhodesia CDG ei cassandra se tb ra i R ADA Cape Cameroun ............08. Camaroons Pins awe a aula ea-oe eee ane Ba aes Russia Cent ...... Luxemburg, Netherlands, Italy Centime .....-.........0000e Luxemburg Ceskoslovenska .......... Czechoslovakia COPECO <5.3)-5-3.5.9-6 20559 e388 Portugal, Timor Correos .. Cuba, Mexico, Nicaragua, Spain Cote D'Ivoire .........-.... Ivory Coast CR DAA: 6306-2455 oes ee ae a BESS Serbia Ctotahhkn. sccscscck csc cae teks Bulgaria Danmark .........0.000 cece eee Denmark Dansk vs sien voe oc aad yee gstanee-e arias Danish DOplata: cise siewesnwe sees Cent. Lithuania Deutsch sss dsceaensaeagade eins German Deutsches ........... 0c e eee Germany DURCH, oo cies a4 ds Soe ees eee B88 Prussia Hest! es c.aceseaaaneese cw ekew oe Esthonia Emirdities .............0220000- Albania FRPP! i asessien dai ed qe eee eee a eae Ireland ESPANA eie-c-n sare det iee eos take Med Spain Ethiopie si0ccccenssase sewers . Abyssinia E EEE E E EN E E AE Greece Eillert gf ide eases aE S Hungary FIQEDOSE: sss sca axes waa aes . Germany Francaise .......... 20 cece eee eee France Freimarke ...........00200 cece Prussia GEOSCHEN, 64s decease eis aes ee es Austria Guerches, os2ss262808 09s aes Abyssinia GUAYAaANe: b..0-2s acne Heese Saws Guiana GUITIES a. sl st sik haa tod ag ae Basen, ayace Guinea Haka esse par eeeses bene ieee Montenegro Haleritsicas ani gee gag eke Czechoslovakia Ha pO ei dene aves taceked deste Hal Ukrainia Helvetia ..............02066 Switzerland ODY ort ovaries inie aie warm eee @ x0) Montenegro ADs ss wee ne i denn dp bane eine Beis Upper Silesia FLAC Ec pcs San 8 eases 4 datos, PeageSoa eed Upper

Can you identify the nationality of the above stamps from the terms printed on them? The list published herewith makes the task an easy one. To make it even simpler, we'll identify these for you, from left to right: Latvia (Latvija); Spanish Guinea (Territorios Espanoles de Golfo de Guinea) ; Austria (Osterreich); Switzerland (Helvetia); Germany (Deutsches Reich); and Dutch East Indies (Ned-Indie). 123

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ADLETS FOR HOBBYISTS BARGAINS IN STAMPS ZANZIBAR! Packet queer freakish stamps from Zanzibar, Algeria, Sudan, Malay States, Victoria, Gold-coast, Nigeria, British Colonies, Souamericans. Don’t delay! Don’t wait. This whooping packet free for 5c postage. Gray Stampco, Dept. M.M., Toronto, Canada. ATTENTION: Send for our illustrated price list of sets and packets. We carry a stock of five hundred different at all times. Many bargains, postage (3c). Collins Stamp Co., 18 Kensington Ave., Jersey City, N. J. STAMPS! 100 diff. 2c; 500 diff. 35c; 1,000 diff. 90c. Tatham Stampco, D9, West Springfield, Massachusetts. STAMPS, 300 Different 15c, 50 Different African 15c. Lists free. Michael, 942 23rd, Bellwood, Ill. COLONIAL Collection (Catalogue $1000) $100 or Radio, Tools, Anything. 20,000 good duplicates cheap, approval selections. Particulars. “Bolton,” 38 Stretton Rd., Croy- den, England. 300 MIXED Quality Stamps Free to Approval Applicants sending 6c postage, Yakima Stampco, Yakima, Washington. FOREIGN STAMPS! On approval, 70% discount. Box 114 Minneapolis, Minnesota. 200 DIFFERENT, dime; fine stamps on approval, three for penny. Leo Zalucha, Bloomington, Illinois. 15 COMMEMORATIVES free to approval applicants. Hasselbaum, Times Plaza Station, Brooklyn, YY. $0 FINELY Assorted Japan 10c. Hollywood, California. Hollystamco, Box 1966, Identifying Nationality of Stamps (Continued from page 123) AMEE aa aN N. Ingermanland Jtaliane. mestrea a a e aa Italy Island senisoninti ih Sake aN ai Iceland Johore . Stts Settlements Kap ......... .. Latvia Kearolimeniiic.ctseesccccecicovsteecbectedsetseecteateeecaensecet Caroline Kedah ......... . Stts Settlements Kelantan .... Stts Settlements Kon ...... Batum, Far East. Republic, Finland, Latvia, Russia, South Russia, White Russia. pth po csccdcssssesecieasesevarsein aitevveesielavaver euvsrseseees ees Crete KUK. Austria, Bosnia, Jugoslavia XO Warten incinerate Wurtemberg Lattagule e e ce inshore iE Latakia Liban .......... .. Lebanon Libanaise .. Lebanon Lietüya oaeen ee aaaea a aE Lithuania Litwa ... Cent. Lithuania | Magyar sapen a ae aT E Hungary Mapka .... .. Russia Markkaa seniti tiorina iiai Finland Maroc ..... . French Morocco Moyen ........ .. Middle Congo Mocambique oo... eeeceseesssseescereereeseneee Mozambique Serbia, Montenegro Sere era ha sh kat a Dutch .. Netherlands, (Holland) INORG e ci25ecsisdazieccccesuaiverescessutuavsncguesvaitaccaniteadeteaes Norway Nouvelle- cesienan ei aes ean New N Semblin Stts Settlements Ore, ora .... .. Denmark, Norway, Sweden Ottomans: ..vsiss.cfsseesscseceacesvceccesiecosscattaneaitisdseese Turkey Osterreich nnii atA EE Austria PEDNINE niaren kita Eaa E nEs Germany Perak ........ . Stts Settlements Persane,-Sitecniaiidisniiescseerinieasesseacenyeaetey Persia Peseta .... Spain PleNMIg oo.esececscccsesscesssseeeeeeneeees Bavaria, Wurtemberg Piastres sh iviectag a a ia Palestine Plebiscit . Schleswig Poczta .... .. Poland Porto .. .. Austria Polska .. Poland Pyb ....... .. Russia Quintar . . Albania Recember 0.2... cceccsseeceeeeeeee: .. Macao REICH eiiiai Germany Ruandi Urandi . elgian E, Africa Rublis® cee severe Naa E iaa Latvia Saargebiet vn. cccccchisciseiecie hegeccenanietcseeeosdcasosaveneusiedts Saar Selangor .. .. Stts Settlements Sem E E T T asescenvteaess Japan Shqiptare . „ Albania SHS... Jugoslavia e E E EE Norway Cle a Endass Schleswig SO] r AO aa AAA AEA CEEE RA Peru Soumi ... .. Finland Stothnkn .... .. Bulgaria Suid Afrika oo... cc ccesccessectecesceeseneeees South Africa S Ujong ... Stts Settlements SVerige inan Ira e EE Sweden Tanga .... Portuguese India Tehad senaisiais aai i iii Chad Tebetalen n Foreris ui aAa Netherlands TOT e eA Err as ora tye teSessessanea etnias Tonga Touva ....... . Tannou Touva Trengganu Stts Settlements Uaka ..... . Montenegro Ultramar neneiia aA iay ara RERAN Cuba Vaticane .. Vatican City A a a a A E AN, Japan ZAT eadar ORS Republik Transvaal ZENA nye n R E A Aii South There are some stamps which can be identified as follows: Dnlama seco lai. adinndantnniins Symbol of Peru Lion and Sun .. Persia Hammer and Sickle .....eccccesecsececesecsteneees Russia Crescent and Star Turkey or Syria German stamps marked Nr. 21 ........0....0... Prussia Suppose you have a stamp on which is written what looks like “napa”. A glance at the list shows this to be either Serbia or Montenegro, Further study finds the word CPBnJA (with a hook on the B and N backwards). You will find that the stamp is then from Serbia and it may be placed under that country in your album. Stts Settlements is abbreviated from Straits Settlements. While not complete, this list should help any collector to locate nearly all of his stamps and as he becomes more advanced he should have little difficulty in identifying any stamp that he may come across. re gaa 0 Thank You jor Mentioning Modern Mechanix and Inventions for August When Writing to Advertisers

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Plans for a Dirt Track Racer (Continued from page 29) forward end of the driver’s seat cushion. A tongue and groove slip-joint is used.’ This is secured with bolts. The instrument board is bolted into the angle iron body frame and is made from a %” thick piece of plywood. The face of the instrument board is aluminum as is also the fire wall. It should be remembered that a fire wall between the engine and driver’s compartment of aluminum not less than 3/16”, is a requirement. This may be steel of a lighter gauge but must be metal. Floor boards must be of metal construction. Upholstering is the conventional type used in automobiles and is designed to fit over the deck and. seat portion of the body to which it is clipped by means of Dot or Snap-on fasteners. The seat cushion is relatively thin (about 2”) so as to bring the driver well down into the body. Those desiring to build all-steel bodies will find. that the most difficult part is forming the metal over the curves, such as are shown in the cowl and deck section. First build up the body frame and then use paper and lay it on the body frame to get an idea of how to cut the metal. Use auto body steel, 20 gauge. There are several ways to work body metal. It may be stretched by hammering or it may be shrunk by heating and hammering. The easiest part to make is the hood. This has but one uniform curve and a paper pattern will quickly show you how. The next thing is the cowl. Here the scoop effect may be secured by first bending the metal sheet to fit over the frame sections A and B without thought to the scoop. Next heat the scoop portion with a gas flame and hammer out and up with a wood mallet, with a rounded end. Work at it until the scoop is roughed out and then, with a dolly block and planishing hammer, smooth up the job. Another way to do this is to split the metal in the scoop and bend out the sections. Fit in other metal sections and weld in place. The rear section or deck is hardest. Experi- ment with paper patterns until you get it figured out to your liking. Then use the hammer and heat to stretch or to shrink, as needed. Perhaps the best plan is to make the deck from pieces, split along the back, down the tail and under- neath. After they are shaped to form, trim the edges and weld together to make one piece. The edges of the cowl near the wheel should be turned in around a 3/16” steel rod to form a rounded or wired edge. Likewise with the for- ward edge of the deck. When body steel hardens under the continued hammering, it may be soft- ened or annealed by heating to a cherry red. Watch that you do not burn it. Build up for a paint job just as any lacquered paint job is built up. Light colors are usually more striking. The C-8 is white, trimmed with maroon. BLUEPRINTS made from the original drawings illustrating this article, but done up in large size for shop use, are available for $4 from Modern Mechanix and Inventions, 529 S. Seventh Street, Minneapolis, Minn. oot Thank You for Mentioning. Modern Mechanix and Inventions for August When Writing to Advertisers ie 2 eee a OMO] a et CE-I HE CE- -5 iia — ee zE ENE a E e oge TETEE] oE CEECEE] or ia __ e = a we TEE ECI Ci- TE CEER- EC] ms mY Lt atl ON APPROVAL 5 VOLUMES BRAND NEW EDITION Only 15 minutes a day with these WONDER BOOKS will prepare you fora good drafting job in less thao a year. Mechanical and architectural drafting from simple stralght lines to important complex plans. A step at a time! Bullt especially for beginners, for men with only grammar schoollng, Draft- ing room practice, PLUS ENGINEER- ING, made easy and clear. Includes com- plete course In blue-print reading. 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PETRPHERBNGENOpPES: EEE EEES NN RN NTT Regardless of strength or size defend yourself and friends against any foul attack, from bullies or by gun, knife or elub. Subdue with ease persons much stronger than yourself, A complete course om approved American Pollce Jiu-Jitsu by internationally known police instructor. 151 Ulustrations with deta letalled instructions - pocket size. 13 knockout blows without using Ss. J. JORGENSEN 704 Maritime Building Seattle, Washington e WORDS, 25c, both 35e. Definitlon Stnd, Eng. Words winning first prize in recent Gold-Medal, Princess Pat, Pathfinder, Bisquick, Magnesia or Wheatles Contest, @ 50c, 3 for $1.00. List first-prize winners in 30 contests, Dept, M DeLONG AGENCY, INC. Lafayette, Indiana We Supply Stock and Buy What You Raise Established 20 Years, Big Profits in Chinchillas, New Zealand Whites, ete. Easy to start. Big rabbit bulletin showing prices we pay our breederssentforonly 10c. Address OUTDOOR ENTERPRISE CO., inc. fists. Send One Dollar Full price, or ©. O. LETTER WORDS opina 25c. Lists of words 25c. Copy of Contest Magazine, 25c. Full information on request. PAYING YOU HIGHEST PRICES— book catalog and monthly market NEW CITY, Rockland County, ÑN, Y. Box 403 LIGHT PLANE BUILDERS—The 1933 Flying Manual is 50 cents postpaid. 529 S. Seventh Street, Minneapolis, Minn. oct 126 Build a Fifteen Dollar Greenhouse (Continued from page 118) the six-foot side drive two more, eight feet long, so that when you have finished driving them they are forming the door sides on one side of the house, and serve to support the ridge poles at the other. Only two complete sets of rafters are needed. These are, of course, at the ends. They are four feet on a side to take the particular 48’ by 24” six paned windows which the mail order houses like Montgomery Ward are quoting at 84 cents apiece this spring. Place the ridge poles in and drive a couple of 20d spikes in each end. Cut a gutter for the water to drain off in. Never mind putting a pitch in the gutters. The water will blow off from the wind in a house this small, and if a drop or two gets into the house, what of it—it’s a greenhouse, isn’t it? In actual practice in big greenhouses the matter of watertightness is not carried beyond the point of shedding water. . Then the sills are put in. These too have gutters cut in them, and they are made to drain out- doors as the drawing shows. Order your windows, and then board up the sides for a height of two feet, and ceil the ends in with the same lumber. At one end a door is cut, and is closed against the winds in Indian fashion, with a thick piece of canvas, or old blanket, or burlap sewed together from potato bags. If you insist, being a city: dweller, a small frame can be made and screen-glass be put on it. This will make the little. house look very civilized. One of the fiat windows on the top should be pegged down instead of screwed, as are the others. On hot days you may want to raise it for venti- lation. Boiled oil and creosote will give a very finished appearance to the house, and then all you have to do is move in your watering pot, your trays, and let the sun shine. The temperature will almost take care of itself, and will vary but little. It will be colder inside the greenhouse daytimes and warmer nighttimes, particularly in spring. Special requirements can be met by watching a thermometer and varying the ventilation. Planning a Sail Rig for Your Boat (Continued from page 119) The most used small boat rigs are shown in the thumb nail sketches. The cat rig is the rig (no matter what the name of the sail that is hung on it) that has the mast stepped right up in the bow of the boat. In small boats this allows room for occupants, and places the center of effort at the right place. Thus we have the jib headed cat rig—(the cat rig with a jib headed sail hung on it) and we have the gaff headed eat rig (cat rig with a gaff headed sail). Both of these are largely used on small boats. Lately the gaff rig has fallen off in favor because the gaff is awkward, requires a lot of extra rig- ging, and slats badly when there is no wind to fill it. On slightly larger boats it may be difficult to get the proper center of effort placed right over the center of lateral resistance in one sail alone, so two sails are used. The areas of the sails are Ne Thank You for Mentioning Modern Mechanix and Inventions for August When Writing to Advertisers

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Planning a Sail Rig for Your Boat divided up into triangles, centered, and as for instance in the drawing where 200 feet of sail is offset somewhat by 10 feet of jib, and the jib is 10 feet from the center of effort of the big sail, the final center is figured by the method of moments, familiar to anyone who ever worked out a lever problem in school. We take the moment of the small sail as being 10 (its area) by 10 (its distance from the c.e. of the big sail) and we get 100. We multiply the area of the big sail by unity, and get 200, its own moment. Now the total moment is 300, and we divide this by the moment of the small sail, we get 14. Therefore the center of effort of the whole sail system is 14 the distance between the big sail and the small one, which makes it about 3.33 ft. down toward the jib from the center of the big sail. This gives the final center to use in placing the sail plan over the previously meas- ured center of lateral resistance. And a way to measure the center of resistance with or without a board is to pull the hull side- wise by a rope. Where it balances and pulls straiget sideways is the place where the center of lateral resistance is located. That is the point above which you must place your sail effort. Creating Mural Masterpieces (Continued from page 84) A canvas, rolled on drums like an ordinary window curtain but inverted, was suspended from the four-storied ceiling along one wall of the studio. It was then lowered to full length. On the other side of the studio a platform was erected about twenty feet high. Here Cornwell mounted a powerful projection machine and lens and by means of his photographic miniatures threw the greatly magnified image on his can- vas screen. In applying color, the artist again resorted to practical mechanics. A working platform was constructed in front of the canvas in fixed posi- tion. The sheet was then re-rolled on its drum and suspended from the ceiling this time exactly like a window curtain. Beginning at the bottom and working upward, the artist had the canvas pulled down to comfortable position before his working platform. First of the completed panels was turned out last summer and hung in the library. In placing the murals heavy scaffolding was first erected to a height of seventy feet. Elabo- rate block and tackle systems were then called into play. Rolled up on their wooden drums and cradled at each end in steel axle housings, the paintings were once more reversed and un- rolled slowly, the top having been anchored to firm wall piers capable of supporting their great weight. As the paintings were bit by bit unrolled, a dozen painters industriously applied white lead to the wall area. The canvas was quickly flat- tened against this film, it being essential to a perfect bond that the lead did not dry before the application. Proceeding a few inches at a time, the process of hanging each mural was a matter of many hours. Despite delicacy of the operation, however, all twelve were installed without a single mishap. LOOSE HANDLES QUICKLY MADE TIGHT Mix a little Smooth-On No. 1 into a putty, put this into the opening, force parts together, and in a few minutes metallizing of the Smooth-On produces pee lasting tightness. Such repairs save many dollars otherwise spent for renewals that are no better. Smooth-On No. 1 also stops leaks at cracks and. joints in pipes, radiators, boilers, tanks, in automobile radiators, engine water jackets, hose connections and in gasoline oil lines. Smooth-On No, 1 after set and metal- lized holds water, steam, gasoline, oil, etc., and may be applied to any metal. Use it also for anchoring and taking up looseness. Makes loose bolts, nuts, screws, etc., permanently tight. Holds in masonry, tiled walls, slate, wood, etc. Keep Smooth-On No. 1 ready HOME a AUTO REPAIRS Write for FREE BOOK for emergencies. Repair Book gives full instructions. Get Smooth-On No. 1 in 7-02., 1-lb. or 5-lb, tins at nearest hardware store, SMOOTH-ON MEG. CO., Dept. 69, 574 Cone Ave. CEMENTS oN A Jersey City, N. nk With this amazing instrument, ANYONE can locate buried treasure, gold, silver or other metallic ore. It is light, compact and inexpensive. It is used widely by prospectors, miners, engineers Public Utility companies use it to and geophysicists. locate lost pipe lines, rails, casings, etc. The Metallascope is not a trick machine, nor simply a radio or magnetic device. It is a precise, scientific instrument employing BALANCED ELECTROMAG.- NETIC RADIATION only. It has never failed to pass a test. No skill or calculations are required. It is used with unfailing success by anyone able to walk and hear. Penetrates 20 feet. Surveys 5 acres per hour. Untold millions in coin, currency and rich ore lie waiting for discovery. Will locate buried boxes containing papers or currency. If you have definite knowledge of hidden treasure, we will make you a specially attractive proposition. Write for full details of this efficient instrument. METALLASCOPE SALES CO. 1040 S. Broadway Dept. M Los Angeles, Calif. em ||P Thank You for Mentioning Modern Mechanix and Inventions for August When Writing to Advertisers 127

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Want a Big-Pay Broadcasting Job? If you have talent here’s your chance to get into Broadcasting. New Floyd Gibbons method trains you for the job you want, You learn at home in spare time. Fascinating course fully explained in Free Booklet, ‘‘How to Find Your Place in Broad- casting.” Send for your copy today. Give age. FLOYD GIBBONS SCHOOL OF BROADCASTING 2000 i4th St. N. W., Dept. 3H42, Washington, D. C. MINIATURE MODELS of HISTORIC SHIPS Realistic, beautifully decorated, 6-inch Models of . Colebrateđ Ships. Made of balsa wood, with details and coloring reproduced faithfully. Anyone can make them; Kits contain all materials with ‘Plans—Instructions for each Model. THE U. 8. $. CONSTITUTION and your choice of any one of the follows ing: Santa Marla, Flying Cloud, Half Moon, Mayflower 2 or Spanish Galleon ......0 For ec Postpaid Send 3c for Magazine-Bulletin of Airplane and Ship Models. IDEAL AEROPLANE & SUPPLYCO.,Inc. 26-28 West [9th Street, New York, N. Y. NEW CATALOG 16 AND DISCOUNT SHEET For Boilers, Gas, Steam Engines, Cast- ings for 40 kinds of these Engines. Pumps, ete., Blectrie and Water Mo- tors, Gears, Material, Piston Rings, Miniature Bolts, Nuts, Gauges, Valves, Rails. Blueprints free with Caatings. Send 25c for Catalog 16. Hefund on Ist order, HOWARD ENGINE & MFG. CO. 2417 N. Ashland Ave. Chicago = Slfinels TELESCOPE Make your own powerful telescope. Magnifies 1024 times the area with the eyepiece furnished. Magnification can be increased to 25,600 times by using other eyepieces, Equal in perform- ance to $200 instruments. Not a toy. Use ordinary tools found around any home to build it. Our instructions are so simple anyone can do it. Get your kit now before the price goes up. NO. 4-EDG KIT AND INSTRUCTIONS—$38.00 AMERICAN TELESCOPE CO., 4008 Addison St., Chicago, Ill. Dirt Track Racing Now you can break into the racing game. How to build your racer, contest rules, supercharges, bal- ance, speed, “revs,” compression tatios—a complete racing treatise illustrated, Postpaid $1. Madisonville, Cincinnati, Ohio. RAY KUNS, Dept. A, very STOP TOBACCO? Banish the craving for tobacco as thousands have. Makeyourself free and happy with Tobacco Redeemer. Not asubstitute, not habit forming. Write for tree booklet telling of in- jurious effect of tobacco and depend- able, easy way torelievethe craving many men have. FREE Newell Pharmacal Co: f ROOK E Dept 007, St. Louis, Mo. ENGINEERING and ARCHITECTURE Intensive Practical Technical Courses in Electrical, Me- chanical, Structural, Architectural Engineering. Degree in q 2 ym. Diploma in 1 E; hort courses in Electricity. Power Plant, Electric Refrigeration, Radio, Televiefon, Drafting. Nonesgentials eliminated. ime and money saved. Low tui- tion, Extensive modern equipment. Part time work during training. 38 yra, experience producing successful men. Write for catalogue, FINLAY ENGINEERING COLLEGE, 1002-5, Indiana Ave., Kansas City, Mo. 128 “Old Man River’? — Houseboat (Continued from page 121) To save space it is neces- sary to use sliding doors. This detail shows how they are hung, also the riser. in the water with a terrific cockeyed. list. So that leaves us with nothing but the hull to consider. If you are in the dark, that is as to house details, buy or send in to this office l5c for a copy of May M-M and the balance of the house details are made plainly evident for you. And as for the hull— It is a simple scow box 8 ft. 2 ins. wide, 22 feet long, and 24 ins. deep. It is made by making six frames out of two by fours of the same outside plan as the sides. Then these frames are planked at the ends first with 2x8” y. p. which are fast- ened with 20 d. galvanized spikes. Don’t use wire nails in a boat like this. The nearest local hard- ware man can have ordinary 20 penny spikes galvanized, and they hold. Bright wire nails won't, and they rust out in a couple of years. When the ends are on the hull, the thing is lined up and propped level, bottom side up. Then the bottom is planked on. Plank the bottom first, and then joint the sloping ends in last. Then turn the hull over, put in the flooring of 34" fir, and put in the partner and headledge pieces. Then deck in the same way you did the bottom. Nothing hard about this, is there? Then set the house in. Ceil up around the edge of the house with moulding caulked with cotton, and the job is done. Half inch cedar ceiling is used for the porch bulwark, same as the house is planked with, and there is your houseboat, Old Man River, ready for a couple of coats of paint—anything you choose, barn red, white, blue green or pink—as long as it has a lot of lead and oil in it. And you can slide her by skidding into the drink ready for adventure in far parts! Re Thank You for Mentioning Modern Mechanix and Inventions fot August. When Writing to Advertisers

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Build a Simple Chemical Refrigerator (Continued from page 113) eake of ice. Theoretically the temperature under ideal conditions would be 28° F. but practical limitations such as insulation of wood in the trays, etc., will cut our efficiency down, At that, intense cold will be produced and we can roll our summer’s supply of ice up to the camp in the form of sacked, greenish white, cheap powder. Here’s how to go at building a tray that will have what is known as an “ice melting capacity” of about 10 lbs. of ice. A varnish can is filled with little trays 5%” deep with galvanized (non rusting) screen tacked to the bottoms. The outside dimensions of the trays should be just enough to allow the trays to fit inside the can. The top of the can is removed cleanly with a can opener or tin snips. The trays are dipped in hot paraffin and pulled- out and swished around in the air to cool them and to shake the screen loose from clogging par- ticles of wax. Only enough paraffin is allowed to remain to chemical proof the wood. The am- monium nitrate is very mild, and has no injurious effect, but would stain the wood and rot it if this precaution were not taken. Then the tray bottoms are neatly covered with blotting paper. Each tray is filled with two parts salt to three parts ammonium nitrate, which can be had from your corner druggist very cheaply. If he hasn’t it in stock he'll order it for you from his chemi- cal supply house. An 14” copper tube is led from the can via a funnel to a drain. See drawing. A water drip through another 14” copper tube and stop cock is arranged to drip onto the little tin roof of the uppermost tray. All piping must be insulated, that is, the holes through the ice box must be caulked so no outside air can continue to bleed in. Also the ice box itself must be as tight as one used for ice. Other- wise we put our little doohicky to work for nothing. Installed, the thing to do next is to put some water in the reservoir, and let er drip. Just enough water should fall through the nozzle to produce an occasional drip at the drain. Experiment and weather will determine this. Cold weather re- quires less water than hot weather. The salt will keep the nitrate from caking. At the end of about 30 hours the trays will be satur- ated, and will lose their cooling power. Then they are placed in sunny spot to dry, as a new set of trays are slammed into the cooler. Takes but a few seconds attention every day, and is far less work than hauling ice. Eventually the ammonium nitrate will be re- duced in quantity through evaporation, and the trays will have to be restocked. If you save the drain water you'll recover most of the nitrate by boiling it out. At prevailing prices, the cost of the nitrate is about the same as that of ice. In out of the way places it is much more convenient, and there is no mystery about it. Anyone can build and run one. Larger sizes can be built for larger boxes. The larger the trays, the more nitrate evaporat- ed and the more food cooled. All very simple. oobi Thank You for Mentioning Modern Mechanix and Inventions for August When Writing to Advertisers JATZ” «onthe Saxophone Become a musician so quickly as to astound everyone. Learn by playing real music — instead of tiresome “exercises.”” You'll soon become the most popular. person in your “set.” New Easy Method js a revelation, Nothing else like it for thor- oughness and rapidity. So simple that young and old find it easy to pluy with LEARN TO PLAY ANY | amazing skill. No ‘trick music’’—but INSTRUMENT actual notes, learned quickly right in Drums and Traps | Your_own_ home. Harmony ana. FREE BOOK and Sight ‘Singing Demonstration Lesson Ukulele offers this wonderful musical opportunt- Piccolo ie ty. Send fop them today before copies Saxophone are exhausted. You’ll be astounded, Voice and Speech Culture | thrilled, fascinated, at this easy, rapid Automatic Finger ‘Control | way to become a veritable master of your favorite instrument. Instruments supplied when needed, cash or credit. Piano Acco Banjo (Plectru or Ten: ., New York City aster Music in Your Own U. S. SCHOOL OF musie, 2620 Brunswick Bid; Send me your amazing free book, low Yo '» with inspiri 3 by Dr. Frank Crane, also Free DEMONSTRA- A LESSON Tah does noe put me under aay obligation, (Please Write Plainly.) ADDRESS. Heave you INSTRUMENT —_—-—-—-—-----—=----~—-- this Instrument? —--___—-——- A LEAN For our NEW LINE of Cast Metal Novelties, BEER SEIDEL TOPS, Ashtrays, Radio Orna- ments and other all year sellers. No special place or experience necessary as we furnish full instructions with moulds and cooperate in selling, also buy finished goods. Chance of a life-time for man with small capital to get into this new and profitable industry. If you mean strictly business and are over 21 write AT ONCE for details as busy season is now starting. METAL CAST PRODUCTS CO. 1696 Boston Road DRILL INDEX Keep your drills in a Huot Drill Index! A drill stand and container, with tap information and decimal equivalents—like a card index. A flip of the wrist and the case is open—you can quickly pick the right drill. Eliminates end- Jess search; saves time. Made of cad- mium plated steel. Three sizes, Write for prices. HUOT MFG. CO. 100 Foot Schulze Bidg., St. Paul, Minn, SECRETS of Beautiful Dancing R EV EA L E thls remarkable new scientific method—the Danceograph. Make your dancing magnetic, fascinating, alluring, glam- orous, PROFESSIONAL. Learn what it means to really dance. Send only $1.98 for complete course—i0 easy lessons. 5 day trial. Money back if not satisfied. FREE with order—Fascinating Booklet, “‘Cap- ture the Living Glamour of Your Own Person- ality.’’ Mark X for course desired. D Ballroom O Tango O Tap and Clog DANCEOGRAPH DANCE ART, Inc. 555 Sutter St. San Francisco, Calif. Dept. 2 New York ipee 129

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ANYAS CEMENT FERDICO CANVAS CEMENT is un- surpassed for attaching canvas to canoes Send for free directions L. W. FERDINAND & CO. 599 Albany Street Boston, Mass. 6 sections, brass bound. Big 3ft Te 10-mile range. Study Moon, Stars and dis- tant objects with this powerful 8-x instrument. Special eye piece for viewing Sun included FREE. Makes A en Micro- acope: ; aquarnntecd: Big value, Postpaid $1.7 c. 0. D. C- extr: BENNER & COMPANY, T-75, TRENTON, N. J. Help Kidneys Ilf poorly functioning Kidneys and Blad- der make you suffer from Getting Up Nights, Nervousness, Rheumatic Pains, Stiffness, Burning, Smarting, Itching, or @ Acidity iry the guaranteed Doctor's Pre- scription Cystex (Siss-tex) —Must fix Cystex Me money back. Only 75c at 3 SOLE WORK SHOE $995—A MONEY-MAKER ! Sell this husky! 2 full leather soles and Uskide extra outsole and heel. Natural leather uppers—no dye. Also 16- Inch laced boot, $4.95. We pay postage. Write for Catalog and Salesmen’s Money- faking Proposition. DOUBLEWEAR SHOE CO., 168 E. Lake St., Minneapolis. Minn. W EASY +5, A DAY“ Possible with new magic invention Ie that lights gas instantly without sparksor flame. A sure sale where- ever gas is used. Retails for 250. MYSTERY GAS-LCIGHTER MN Golin om this Packedon indivldnal cardewith Instractiona. BIS MOREY Sample 10c. Rush $9 per gross or $1 per dozen. MAKER -~ NEW METHOD MANUFACTURING CO. ACT NOW = New Method Bldg., Desk MG-8, BRADFORD, PA. AUTOMOBILE COMPASS Have you ever taken the wrong road and traveled many miles before discovering your mistake? ‘This new AIRPLANE TYPE COMPASS constantly tells your direction of travel. Sticks to windshield. Illustration half size. ONLY $1.25 POSTPAID. SATISFACTION GUARANTEED or your money refunded if returned within ten days. Agents Wanted! WALTER E. HULL, Box 246-A, WARREN, OHIO ote 130 Build A "Desert Town” Canoe (Continued from page 94) end pieces. Stranded copper radio antenna wire was used and is much the most satisfactory. How- ever, solid soft copper, brass or soft galvanized iron wire, about No. 14 B & S gauge or the size of ordinary baling wire, will do. The same wire used in wrapping and bending the gunwales, about 12’ in all, was more than sufficient for com- pleting all the permanent ties in the canoe. The spreaders, one at the center 2’ 9” long and one at each rib B 2’ 344” long (Fig. 5) are made from two wood lath smoothed down and nailed together with lath nails, cleated over. Fig. 6 illus- trates the position occupied by the spreaders di- rectly below the gunwales. The center spreader. is provided with an upright from the keel. This upright is made from two thicknesses of lath 11” long nailed together with 1’ lath nails and bound in place by wire ties as indicated. The wire ties are necessary rather than nails due to this mem- ber being both a thrust and tension member al- ternately. The center spreader serves the double purpose of bracing the canoe and of furnishing a center of balance hand hold for lifting and hand- ling. This spreader is placed first to furnish fasten- ing points from which to form the gunwales. Fig. 6 indicates the method of fastening the center rib, the spreader, and the center of each gunwale to- gether. Two 114” wire nails are passed through holes bored through the gunwales and the cen- ter rib and bent over on the outside of the rib. Two 1” wire nails are driven through the gunwale downward into the spreader, and two 2” finishing nails are driven through the rib into the ends of the spreader. Wire ties may be substituted through holes drilled in each case but nails were found satisfactory. A small hand awl, made from an old ice pick sharpened to a wedge point was used in boring all the holes required throughout the job. Nails larger than those specified should not be used as the thickness of the gunwale does not permit of weakening with heavier ones. Care must be taken not to weaken the gunwales at this point by bruising as this will cause the wood to bend sharply, spoiling the smooth curve. All holes should be kept as small as practicable. As an aid in holding the members together while fastening permanently, the different parts were tied in place temporarily with soft copper wire ties. Twine may be used but it is a little more clumsy to handle. Next trim the ends of the gunwales to fit in place one inch below the tip of the bow-pieces, bore two holes through the ends and through the bow-pieces and tie permanently with wire ties as indicated in Fig. 7. Draw the ties as tightly as is practicable and twist the ends together with pliers. A wire binding was placed over the ends of the gunwales to insure against splitting. Now temporarily bind each rib to the outside of the gunwale with wire or twine, readjusting by sight for any apparent irregularities in symmetry of form. Do not fasten any of the ribs permanently except the center rib as this will prevent adjust- ments in the shaping when the longitudinal strips of screen moulding are placed. Invert the frame over a box or other support and temporarily tie into place the longitudinal screen mp» Thank You for Mentioning Modern Mechanix and Inventions for August When Writing to Advertisers

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Build a ‘Desert Town” Canoe moulding strips marked X, Y, and Z in Fig. 6. As the strips are a little longer than the canoe, the ends may be held in place temporarily as at A, Fig. 7. Both sides of the canoe should be worked together to insure symmetry. These three strips are placed first as they will reveal the ad- justments- necessary in the ribs to secure smooth, even contours. No nails should yet be used in plac- ing any of the strips or in fastening the ribs but twine or wire ties should be placed at each inter- section of strips and rib. After all irregularities have been eliminated by slipping the intersecting members about, in their ties, the distance from the keel along the outside of each rib to the top of the gunwales should be checked with the corresponding oppo- site side to prevent a warped appearance. Turn the frame right side up, and with a 1/16” drill or hand awl (the ice pick was used here) drill two holes, spaced about 1”, through the ribs and gunwales. 114” wire nails thrust through these holes and cleated down across the grain on the outside of the ribs furnish. strong joints. Use an old flat iron, sledge hammer, or similar backing in driving and. cleating all nails as the frame is too light to furnish sufficient resistance. Cut the ends of the ribs off flush with the top of the gun- wales, and touch-these nailed joints with linseed oil or paint to retard rusting and checking of the wood. Invert the frame, check the spacing of the longitudinal strips and nail them to the ribs with two %4” wire-nails, cleating over on the inside. Cut the ends of the strips to fit snugly to the inside of the bow-pieces and bind as indicated at B, Fig. 7. Chamfer the inside of the tips to pre- vent the formation of bumps along the bows. The wire ties used in holding these strips to the ribs can now be removed and reused in placing three of the other intermediate strips on each side, and so on until all nine strips have been placed. The frame will now appear as shown in photographs B, C, and D. Fig. 5 indicates the method of laying the floor with 4’ wood lath, planed smooth and chamfered on the top sides. Use 1” lath nails bent over where they protrude. No seat rail was provided as seats were not found necessary. However, the rails may be pro- vided by placing 34” x 14” strips, similar to the gunwales, along the inside of the ribs just above the longitudinal strips X. The style and spacing of the seats being dependent on the requirements of the individual, no attempt is made to specify in this regard. Experiment indicates that the rear paddle seat should be placed just back of rib C, and the front paddle seat between ribs C and B. The middle or “passenger” seat is best located with its back against the rear spreader at B. Wood lath smoothed down makes excellent material for building the seats. About twenty-five additional lath will cover. Each seat should be furnished with supports from the keel similar to the sup- port at the center spreader. This will reduce the necessary weight of the seats and distribute the load more evenly to the sides and keel. Two of the four remaining 14’ strips of screen moulding should now be placed in water to soak. If a trough, ditch or pond long enough to accom- Thank You for Mentioning Modern Mechanix and Inventions for August When Writing to Advertisers Oun the SNAPPIEST B OAT Hloat- Earn. Bullding It in 2 Days! wake 112e Profit on each 18 Ib. 1-YAK yon easily ily sapemb\s it, Nor cinkabie! l List it, with 3 lade pad- dle given free with the success! Order now or sh boat details and Great Mony- Making Pian! MEAD GLIDERS $353: Maret, chicage Choose. aviation.as your career and be sure of big-pay success quicker! Be a Lincoln- trained. pilot or mechanic and get the better aviation jobs. This World’s Best Known School graduates properly trained men who write us: «¢, . . Tsecureda position on the airport here as mechan- ic and: assistant tothe director. This pays mea goud salary . . . Yourinstruetors . . . Knowhow tosuccessfully im- part their knowledge toothers . . .’’ J. Kenneth Welgel. Government Approved School. Unexceiled equipment. Training by Government Licensed instructors, includ- ing blind fiying, cross country, acrobatics, etc. Aviation’s future looks brighter every day. Now I to start your training. Exception uth America as well as tion courses taught in either Pinel or Spanish. Writs today. State your age. INCOLN AIRPLANE & FLYING SCHOOL 406A alreratt Bldg. Lincoin, Nebraska 12-inch Flying Model SPARROW HAWK = A dandy Model of the fighting plane of the ill-fated Akron; with full Postpaid. fuselage body, carved balsa prop, metal z i motor plaie; also new 15 inch MONOCOUPE. (2 Kits 500) Both Kits contain everythlng to build the Model. INTERNATIONAL MODELS COMPANY 251 West 57th Street - WE ARE WORKING FULL TIME a NO DEPRES- sion WiTH B the time onal opportunitics. „din Central and Send 5c for Catalogue Kits 30¢ Each New York pa! Wh een E AL £ Do the same selling METLMACHES — THE MODERN MACH What is METLMACH? Ir’s a mach made of metal that will not burn up, no burnt ends or ashes; one mach can be lit 1000 timesor more; positively water, ratand child proof. Seemsimpos- sible butit’strue. Send $1 for 15 METLMACHES with display easel, sell them for 10c eachand make 50% profit. Sample 10c. SOLD AROUND THE WORLD IN 90 DAYS One man sold 100 gross in 3 days, making $227 profit. Exclusive territory, a permanent business. METALMATCH CORP., 112 Water St., WARSAW, ILLINOIS HOW TO BUILD 20 BOATS 50 Cents at All Newsstands aoe 131

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PENCIL FAR GAS UN Ya, GUN | ie 7 Protections = Nos 1 50 A POWERFUL GUN and Automatic Pencil Combined. ga Improved to Perfection. Shoots Tear Gas in its most highly WA concentrated form. All metal cartridges. A Sure KNOCK OUT! Most daring assallants are instantly stupefied and made helpless. An ideal protection for everybody. No skill required!—Every demonstration means a $3.00 sale. Our sample outfit with 20 cartridges to demonstrators $1.50, if palid with order. HAGEN IMPORT CO. 1019T Hagen Bldg. St. Paul, Minn. Write for free booklet describing ‘‘87 Plans for Operating a Successful Business of Your Own’’. Make from $20 to $100 a week starting in spare time at home. No peddling or house-to-house selling. Write for Booklet sent free, and without obligation. your copy today ELITE ‘PUBLISHING CO. Dept.G 214 Graad Ste _ New York, N. Y. WHY BEA LAUGHING STOCK? I guarantee new halr on your bald spols or money refunded. Dandruff, itching scalp, falling hair go overnight. Man past 70, bald 20 years, grew luxurious head of hair. My booklet “Scalp Health,” FREE in plain wrapper. -~ CLARA BELLE ATKIN COMPANY Suite A10 831 2nd Ave. So. Minneapolis, Minn. . « thousands of ways to make more money! NEW EDITION ° Henley’s Twentieth | Century Book of 10,000 MONEY-MAKING FORMULAS PROCESSES RECIPES and Trade Secrets H o WwW TO make all kinds of Adhesives and Alloys for every purpose; Anti-Freezing Solutions ; Bat- tery Fillers and Solutions ; Beauty Preparations; Beverages —all kinds ; Brass Re-finighing ; ; Bronze Powders ; Cements ; Cleaning Preparations ; 3; Cosmetics; Chromium Plating ; Dandruff Cures; Dentifrices; Dyes; Electroplating and Electrotyping ; Essences and Extracts of Fruits; Freezing Mixtures ; Glazes ; Inks of all sorts ; Insecticides ; ‘Lacquers : Laundry Preparations; Leather; Lubricants; and thou- sands of other practical methods for doing things. WITH THESE FORMULAS. MA KE MONEY Make hundreds of articles of every- day use for a fraction of the money you now pay in shops. By follow- ing plain instructions, you can easily make tooth pastes—cold creams —cosmetics—hair tonics—remedies—stain and spot removers—floor finishes—varnishes, puints—compounds for mending metal, wond, glass, New Edition contains hundreds of new recipes and formulas, a Buyers’ Finding List and Dictionary of Ingredients. Cloth. Prepaid to any address or = SENT C. 0. D. if desired. Price $4.00 Modern Mechanix and Inventions 529 So. 7th St. Actual size 6x9. 800 pages Minneapolis, Minn. Build a “Desert Town” Canoe modate the full length is not convenient, it will do to weight the center and allow it to sag into a smaller pool or trough. These strips are to finish off the top of the gunwales after the covering has been placed. The frame is now ready to cover. Medium weight tent cloth or canvas, sufficient to make a piece 14’ x 5’ 8” will be necessary. A five year old, medium weight camp tarpaulin was used in this case and has proved more than strong enough. Back porch curtains, old tents and simi- lar cast off sections of canvas can all be made to reduce the cash outlay, provided the material is carefully inspected and all rents sewed up with feather stitching and doped with “Duco Cement,” Ambroid, or airplane dope (all similar compounds), or in the absence of these, with sev- eral treatments of paint. Small holes and thin places are easily strengthened by two or three applications of the “dopes” mentioned. These can be procured at hardware stores, automobile top repair shops, airplane supply points or airports. Duco Cement is sold in convenient tubes for a few cents. Less than half a tube was used in doping a foot-long tear and a dozen small holes and thin spots. Ambroid, or airplane dope, is sold by the gallon. If you are fortunate enough to live near an airport, you may wish to secure enough of the dope to paint the whole covering, in which case a much tighter covering could be obtained due to the shrinking of the dope. In making up the 14’ x 5’ 8” cover from separate pieces, 14” lap seams with two rows of stitches should be used. Sufficient new canvas to cover the canoe will cost approximately three dollars at retail prices. Fold the canvas evenly down both centers as indicated in Fig. 8, and mark the folds with chalk, pins or soap. Invert the canoe frame over a box or other support, and place the canvas over the frame, making certain that the long cen- ter mark lies along the keel and the short center mark lies along the middle rib as indicated by dotted lines in Fig. 9. Tack temporarily along the keel at the three points shown. The two re- maining 14’ strips of screen moulding are now nailed over the canvas along the sides of the keel 14” from the bottom of the keel, Fig. 9. Use 1” nails at intervals of about 1%”, Tack the can- vas temporarily at the five points along the gun- wales as shown and turn the canoe right-side-up. Trim the covering to within three inches of the gunwales and to one inch of the bow-pieces. Starting at the center rib, fold the canvas double and tack to the underside of the gunwales with No. 2 tacks at intervals of three inches, see Fig. 10. The temporary tacks will be found to be causing wrinkles as you go along and should be removed. If a little care is exercised in stretching the wrinkles out in working toward the ends from the center, the covering will go on smoothly. The canvas is tacked to the bowpieces last by doubling the extra cloth back on the inside so that when stretched tightly the folded edge will just cover the front side of the bow. Tack at 1” intervals starting at the keel, and take up the slack in the fold caused by the curve of the bows a little every three inches. The finishing strips for the gunwales have been 2 IDO! Thank You for Mentioning Modern Mechanix and Inventions for August When Writing to Advertisers

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Build A "Desert Town” Canoe soaking and should now be quite pliable. They are nailed, flat side down on top of the canvas to the top side of the gunwales. Nail each at the center with one 1” lath nail, and temporarily tie the ends of the strips to the tips of the bows to hold in place while working. The nail at the center of each strip may tend to pull out under the strain of bending. If it does clamp the strip to the gunwale with a small clamp or wide mouthed pliers with handles held together with twine or tape. Nail the strips to the gunwales at intervals of 6” with 1” finishing nails up to the point of upward curve. A clamp helps at the curved point, also. 1” lath nails. should be used at the upward curve as the pull will tend to draw the small heads of finishing nails through the wood. There are left two of the narrow pieces of hoop formed for the bows. These are smoothed and rounded on the outside, drilled and countersunk at about 5” intervals and screwed with 1” flat head wood screws to the bows over the covering as shown in Fig. 11. Holes for the screws should be drilled into the inner bow-pieces to prevent splitting. Fig. 9 indicates the method of placing a short sheet brass, copper, or galvanized iron strip about a foot long over the joint of the finishing bow- pieces and the keel. The metal strip may be con- tinued along the full length of the keel to pre- vent wear from scraping, but the short length serves well enough for protecting the portion of the bow and keel that strike the shore. when beaching. Following is the list of the materials needed for certain parts, and what the cost of them was found to be in the vicinity of El Paso, Texas. , ; Approx. Cost Ribs and Bow-pieces—6’ Barrel Hoops—10... . $0.50 Keel—White Pine—114/'"34’'"12’ — 1.... .23 Gunwales—White Pine—34" x 2'"'x12'— 2.... .23 Frame Strips—White Pine—Flat Screen Moulding—14'’x54'’x14" —22.... 2.45 Floor, and Spreaders—4’ Wood Lath—25.... .25 Covering—Medium Weight Tent Cloth or Canvas—14'x 5’ 8” «2.0.0... ee, 3.00 Nails—-6D, 70 (for Jig); 1/' Lath Nails, 1% Ib.; 1” Brads or Finishing Nails, 4% 1b.; 34” Wire Nails, 4% Ib.; 114’’ Wire Nails, 4% 1b.; 2” Finishing Nails, % 1b.; Neo. 2 Carpet Tacks, TOO): se vei eins Gland ak nd eb Saale eam a eee 320 Screws—1'’ Flat Head Wood—12 ....... 05 Paddle—White Pine—6’x17/4’'x6''—1 -70 Paint—“Outside” or “Duck”? 4 gal. thinned with 1 qt: Turpentine ..............2........ 2.45 Permanent Wire Ties—-Stranded Copper Radio Antenna—=12’ ..... eee 06 Temporary Ties—Wrapping Twine of No. 20 B & S Gauge Copper or Soft Iron Wire—25’ .. .15 Totals 2snthie8 ot whe eae $10.37 Two coats of good “outside” or “deck” paint (1% gal. thinned with 1 gt. turpentine) on the out- side and one coat on the inside will ordinarily make the canoe water-proof, A primary coat of the airplane dope will greatly reduce the amount of paint required, and will make the covering shrink to a drum-like tautness. However, the dope may not be convenient to obtain, and the -cost will more than offset any saving of paint. ‘When the paint is thoroughly dry, a trial in the water will reveal any small leaks, which may be filled with paint. woe Thank You for Mentioning Madern Mechanix and Inventions for August When Writing to Advertisers A amier these nq ag AILMENTS! Are you “all in”? Suffer night ris- ..ing, constipation, pains in back, legs, feet, nervousness, mental depression? Science has discovered that these “after 40” ailments are often not merely the symptoms of approach- ing old age, but prostate gland fail- ure. If neglected it may mean grave surgery. Now a drugless home treat- ment is perfected that has brought amazing relief to thousands. Endorsed and ‘used by many doctors. Over 100,000 men have tested it. Many feel .10 years younger in 7 days. Write for Trial Offer and daring free book of startling facts about men past 40. W. J. KIRK, President THE ELECTRO THERMAL Co. 38668 Morris Avenue Steubenville, Ohio Brings BIG MONEY. 22 Bisscope Al: Metal Cam; 7 era takes, develops,tones and finishes in one minute two perfect Photo Buttons, aimul- taneously with one exposure, on positive paper direct, automatically discharged. V No Experience Neaded, No Plates, No Films or Dark Room Required The Hiagcope is loaded with two hundred positives in broad da: Smail Investment_-- Tremendous Opportunities for Women. MAKE 8c PROFIT ON ERY DIME. Photo Buttons are'all the rage this season. Big Mon- Š ey awaits you at Beaches, S \\ Parks, Fairs, Carnivals anı Coit omecomings. RIA LA FREE iOS TRATED fh raed ao BOOKLET R and SPECIAL OFFER to-our nearest branch. iigh M en and A FREE BOOK Develop your personal, creative power! Awaken the silent sleeping forces in your own conscious- ness. Become Master of your own life. Push aside Y all obstacles with a new energy you have over- locked. The ROSICRUCIANS know how, and will help you apply the greatest of all powers in man's control. Create health and abundance for yourself. Write for FREE book, “The Wisdom of the Sages". It tells how you may receive these teachings for study and use. It means the dawn of a new day for you. Address, Scribe N.P.U. ROSICRUCIAN BROTHERHOOD San Jose {AMORC) California 12-inch | Flying © & SCALE MODELS Full fuselage Models, guaranteed to fly, Each Your Choice of 8 Different Models complete in Construction Kit with all parts, Any 2 for materials and Plans—Instructions. Monocoupe Sparrow Hawk Puss Moth 50c Polish Fighter Fokker D-8 Fokker Triplane Boeing Fighter Sopwith Camel POSTPAID Send 8c: fur New Magazine-Bulletin of Newest Kits DEAL AEROPLANE & SUPPLY COMPANY, 1 Ine, 26 -28 West 19th Street New York, N. Y. ube 133

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And w defy anyone to e excel our: quality. Every brand CAN'T BEAT OUR PRICES BALLOON Tires ize Rim Tires Tubes $1- 80. ag Sos omm ou MAMAN | COONS ONONO D AGAR AULA OTOL =} UNNNNNNNEES NNNSN O NOOO Wi N! > QUANNU NAUNA RO 2 = TEPPA HEDEOSS RAAD NSARA AN, Afl Other Sizes WE WANT 1.35 DEALERS ŅAII Tubes auar aateed Brand Now SEND ONLY $21.00 DEPOSIT, on each tré ordered. We ship balance C. O. D. 3 per count for full cash with order. to giva 12 months’ service 76 GOODWIN TIRE & RUBBER CO. 202- 1840 S. Michigan Avew Chicago, M. “SILVERLITE" FREE.: Flashlight Lantern for 2 Tires NNOCOWOON Herren pe OSOS benno ope oe saumassa pm h D “Any tr ret ling ed at Meana “BOND ra EL Aarts TRICKS WITH 110 VOLTS Electric Fun! Make toy motors, buzzers, tops, machine guns, arcs, shockers, lights obedient. to the voice, window navelties, floating rings, spirit rapping—all kinds of amusing and practi- cal electrical devices. Our book gives full direc- tions for doing 200 stunts with 110 volts, A.C. Price postpaid $, 00. CUTTING & SONS D St. jusi an DON'T DELAY — ORDER TODAY. CAMPBELL, CALIF. Pay only government fees. Legal blanks and book with complete instructions, postpaid $1. CUTTING & SONS, 83D St, CAMPBELL, CAL. ee | ART OON voor way i P ccess/ SY J/Don’T COPY - LEARN TO ORIGINATE! RAYE BURNS will teach you HOW to CREATE 85 SELL! Course has 26 lessons and 600 ilk — Send name and address Yor oo luztadons | woe ORIGINAL CARTOONS at home that you can RAYE BURNS SCHOOL, Dept. F-X, Box 2194, CLEVELAND, OHIO Write for Tree List of ethical schools that successfully correct all sp speech a, Gefects. 38 Newbury St. Suite oa Boston, Mass. JOKE TO BE DEAF = EVERY DEAF PERSON KNOWS THAT George P. Way made himself hear, after belng deat tor 25 years, with Yartiticlal Ear Drums —his own invention. He wore them day and night. They stopped head i Moises and r g ears. They are ¥ invisible and perfectly comfortenle. No one sees them. Write for bis true story, ‘How I Got Sent" and Made Myself Hear.” dio Dook- > let on Deafness. Addr NO Artificial Ear Drum GEO. P. WAY, Ince, 741 neon Building, Detrolt, -Michigan eh 134 Sports Model Sidecar Easy to Build (Continued from page 97) Now for the upholstery. First, make a single panel for the back section, well padded, to fit down in place in the body. The sides of the passenger seat should be lined with cardboard, covered with a thin layer of upholstery wool, and then covered with Fabrikoid, of the same ma- terial used in covering the back. The bottom seat can be an old automobile cut down to fit. To finish off the job a neat airplane type wind- shield may be constructed of a large single piece of thick celluloid, such as is used in airplanes. Any airplane supply house will be glad to supply, you with this material. When the body is complete it should be mount- ed in place on the two cross members which will be on the chassis. _Midgy Jr.—Cigar Box Receiver (Continued from page 101) For use in a car equipped with spark sup- pressors, use the car frame as a ground and run the antenna wire out the window to a pole lashed to the side. In a canoe or other boat trail the ground wire in the water and fasten the antenna to the mast or fishpole. In camp, the well pipe can be used for ground- ing and an antenna erected in the usual. way. Now that the tubes are lighted you are ready to tune in. Rotate the tuning condenser with the lever, at the same time advancing the variable resistor until a hissing is heard in the phones. This should come in gently. If it plops in with a thud try a higher resistance grid leak (or a different one) or reduce the number of tickler turns on the coil. When a station is heard the regeneration should either be increased or backed off until the signal is at maximum without the set going into oscilla- tion. The circuit uses the following parts: Midget book type balancing condenser, .000050 variable midget tuning condenser (Pilot or similar), .0001 fixed condenser, (grid condenser), 00025 blocking condenser, 7 to 9 megohm grid leak, 8 ohm filament resistor, 50,000 ohm variable regeneration resistor, Small 3% to 1 ratio audio transformer, Two 230 type 2-volt tubes, Pair of phone tip jacks, A battery—two cells of flashlight battery, (234x13~ inches), 5 cents each, B battery—Burgess portable 2214-volt B or C battery measuring 3 5/16 x 2 1/16 x 25 inches. Trailer Carries Portable Cabin (Continued from page 99) To finish the sides, fasten the four hinges to each corner, evenly spaced as shown. As the accompanying sketch shows, the side studding is offset upward 1 inch. The projection of this studding at the top of the sides fits into the gp» Thank You for Mentioning Modern Mechanix and Inventions for August When: W riting to Advertisers

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notches in the rafters of the roof and locks stud- ding and ratters together. At this point turn the 3-in. diameter, 4 in. long, lag screws into the corner posts and the two 2 by 4 in. studs. Turn the screws in until 1 or 144 in. besides the heads protrude, then cut off the heads with a hack saw. With these pins in place, stand one side in place along one side of the floor and after making sure that the side is properly aligned, mark around the pins, then Jay the side away and bore % or 7/16 in. holes on these spots at least 1 in. deep for the Pins to fit into later. The other side is made in the same way but reversed. The illustration of the roof shows partial views of both the top and bottom. The rafters are 2 by 4 in. pieces spaced to coincide with the side studding. After completing the roof, turn it over and set it at the angle it will assume when on the cabin. In this position nail roofing paper, then fasten the canvas strip along the ridge with a little slack at the actual ridge. Use large head roofing nails for this. To finish, heat asphalt un- til it pours, then spread it over the canvas. When cold, fasten the hinges, one to a pair of rafters as shown. These various units are best transported on a trailer. You can get Ford front wheels and axle and make one for this special purpose at very low cost. To bind the units it is suggested that you obtain two 2 by 4 in. pieces of suitable length and four long bolts, say 34 in. in diameter, and use the method shown. Ride Wooden Seahorse 5 M. P. H. l (Continued from page 114) and these should be drilled and bradded in place so that the head can be mounted without a lot of fancy juggling. o pieces of 12-in. and one piece of 4-in. stock make up the body proper, together with a strip of lattice to gain additional clearance for the working mechanism. Bicycle parts make up the driving mechanism, with a few changes to fit the job. First on the list is the crank hanger. This must be cut in two since the original is not wide enough to span the two sides. The extension is made by slipping a % by 3%4-in. pipe nipple over the cut crank, welding it in position. The other end of the crank is fitted with a ¥-in. pipe coupling, likewise welded. Of course, the nipple turns into the coupling, and everything is made fast by means of a suitable metal pin. For the sprocket arrangement, take a 3-in. length of 34-in. pipe and fit a %4-in. waste nut to one end. Slip this through the sprocket, fitting bolts through the waste nut into the 2 in. thick hardwood cam which goes on the opposite side. You are then ready to mount the hanger between the wooden side pieces, using the original bear- ings. There is nothing very difficult about the paddle wheel. You will use a non-coaster, rear bicycle hub, recessing this in two hardwood blocks as shown in the drawing. The paddles are fitted around in regular order and should be securely screw-fastened. The mounting for the paddle wheel consists of a rear bicycle fork, cut to the desired length and flattened out so that it can be bolted into place. oo chat Thank You for Mentioning Modern Mechanix and Inventions for August When Writing to Advertisers = | on approval. Just mail the coupon and we’ll send you a set of these remarkable auto books, just off the press. Whether you are a mechanic or helper, expert or apprentice, auto owner or driver, if you’re in- terested in knowing all about automobile mechanics, then take advantage of this FREE OFFER. 4 DON’T SEND A PENNY! A better job—in the gigantic auto industry. # BIGGER PAY—a chance to go into business for yourself and get a share of the huge CAN YOU FIX IT? profits are waiting for any man who even These wonder books tell step half tries to improve himself. Learn Auto Py HO TE tale out Engineering with these wonder books ried play (ins ‘erentia’-- way—withoul studylng or memorizing. Sim~ pi basnimmy in steering-- ply use the JIFFY INDEX to look up tho your finger instantly on en- answer to any auto problem. Built by eleven gine trouble snd i ny the of America’s grentest automobile engineers, Newest Improvementa fully and written in simple language so you can covered, Equa! to a com- understand it. pete made conme at fess FREE! Privilege of consulting Auto- z mobile Engincers of Amertcan Techni- 6 Big Volumes cal Society for one year without cost Latest Edition if you mail coupon immediately. 2500 i = Hone. witing diaerame, ete AMERICAN TECHNICAL SOCIETY inelu lation Motors. Luxeedition, zold-stamp- Drexel Avenue & 58th Street ed flexible binding. Dept. AC-320, Chicago, tll. AMERICAN TECHNICAL SOCIETY, ' Dept. AC-320, Drexel Ave. & 68th St, Chicago, II, I would like toaee the new 6-volume edition of your AUTO BOOKS. [1 will pay the few cents delivery charges only, but if | choose to, 1 may return them express collect, If after 10 days use I prefer to keep them, I will send yon $2 and pay the balance at the rate of only $3 a month. until $24.80 is paid. Please include free consulting membership as per your offer above. NAE paei aae eR dy biog. wigta e E aE hE Address Employer's Address .. a FIND GOL GUGGENHEIM GOLD DETECTORS Lead You To It Guaranteed to detect gold Ae Cas ŞA and silver anywhere. Used HR TC ; by Prospectors, Miners, Touristsand Treasure Hunt- ers everywhere to locate lost jewelry, buried treasure, rich gold pockets and qe. Prospector in Merced Co. lo- POWER PLAGE MACHINE AND cated 2 gold claims in week. Ta rol the wold N Cranes Many recent fortunes made 0. in ordina: placer gravel. Eliminates rocker by gold seekers. Sond $. for and all losses from panning. small size, $1.50 for st . size, Saves smelting costs. Amalga- or $3 for professional size in mates and concentrates me same leather case, and directions. time. Can be used in arid re- -da ney refund guar- gions. 24 in. bowl, $150.00 aay money. E complete. GUGGENHEIM EQUIPMENT COMPANY Dept. 30-H, 110 Sutter St. San Francisco, Callf. HOME WORKSHOP MATERIALS HANDY BARGAIN PACKAGES Drill Rod, Steel Rod, Brass Rod, Tubing, Brass and Steel Plates, Machine Screws and Nuts, Drills, Taps, etc. Send stamp for descriptive literature and prices of these convenient and economical packages, You will also receive description of several artistic and profit-making articles easily made by the home craftsman. ADVA ENGINEERING CO. 205 W. WACKER DRIVE CHICAGO, ILL. HANDY MAN’S HOME MANUAL On Sale at All Newsstands for 50 Cents IRD es 135

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Vina MMERD =: i < x - Copy of ; T Write for Free “SPEECH” booklet ‘‘Helps for Stammerers” Free STAMMERERS' GUILD, 38 Newbury St., Suite 404A, Boston, Mass. PATENTS BOOKLET FREE HIGHEST REFERENCES PROMPTNESS ASSURED BEST RESULTS Send drawing or model. WATSON E. COLEMAN 724 9th St, N.W. Patent Lawyer Washington, D. C. venere p A ENS Write today for FREE BOOK, HOW TO OBTAIN A PATENT and RECORD OF INVENTION —or send Draw- ing or Model of your Invention for Examina- tion, MAIL COUPON TODAY! Prompiness Assured with Best Results

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REGISTERED PATENT ATTORNEYS | £638 Woolworth Bidg., Dept. B, New York City | | 203 EARLE BLDG. WASHINGTON, D. C, | | Please send me your Free Book, “How to Obtain a Patent,” and your “Record of Invention” form. | | NAME ceinen srn anea a iettesnaeed | | ADDRESS. dated enna | l i Ask Your News Dealer for “Handy Man’s Home Manual”—50c “cul 136

Fortunes Waiting for Inventors

(Continued from page 85) chanical or electrical device that will automati- cally .close a window in the case of rain. 18. A window that can be opened from the left, right, bottom or top to accommodate the wind. In other words, a window so hung that it will be universal. 19. An electric wall and ceiling washing ma- chine that can be operated by a housewife and that will not drip. It-should wash and dry as it went along. 20. A dog muzzle that will prevent a dog from barking and yet meet the S.P.C.A. specifications. 21. If an inventor can develop a simple little device that will prevent the shoulder straps from ladies’ undergarments from slipping off the shoul- der, he will never have to worry about income for the rest of his born days. Twenty million such devices could be sold in the United States alone during the first year. 22. A new method of attaching collars to shirts eliminating the well-known and thoroughly de- spised collar button. 23. An automatic cloak room for public places - where people may hang their coats and lock them into position using a simple key for their re- moval. This amounts to a lock-hook of simple’ construction so that a garment would have to be destroyed before it could be removed. 24. A simple little kitchen device that will shell peas quickly. It should sell for a maximum of twenty-five cents. 25. A simple thermo-static control that can be applied to old fashioned gas ranges in connection with the oven. ' 26. A cheap alarm for rural mail boxes that will ring a bell in the house for an instant and then stop. 27. A lip-stick holder that will feed the stick out only as fast as it is used. It should be un- necessary to pull the stick out each time it is used as is now the case. When one considers the fact that twenty millions of these things are sold yearly in the United States alone, one will see the great profit that would result from such a scheme. A penny a piece royalty would make a man $200,000 a year. 28. A cigarette case that will contain a tiny humidor to keep the contents fresh and moist. 29. A self-watering flower or plant pot that will make it possible for growing plants to be supplied with water over a period of a month. 30. Some kind of a simple device made of fabric that can be sewed inside the knees of men’s trousers that will prevent them from bag- ging at this point. If the method was good enough ENN EN A ea A ANN AAAA A TNA NAN À 160 MILLION-DOLLAR IDEAS What and How to Invent and How to Sell it— these books show you how! Edison’s Secrets of Si How to Invent shows inventors just how to apply the great Edison’s methods to their own problems— 50c. Protecting and Selling Inventions Without Patents tells how to turn unpatented ideas into dollars—50c. 160 Million-Doltar Ideas describes greatly needed inventions which will make fortunes for the men who develop them--60c. All three booka $1.25 postpatd. Free expert criticism and sales advice to readers of these booka. INVENTOR’S SERVICE BUREAU 1931-A University Ave., St- Paul, Minn.

gaes Thank You jor Mentioning Modern Mechanix and Inventions for August When Writing to Advertisers

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it could be licensed out to all of the large manu- facturers of clothing. 31. A new method of bringing rail ends to- gether to compensate for the great expansion that takes place in summer and winter. This has long been a major problem of the railroads and the lucky man to solve it will make many millions of dollars. Faster Mail Service to Readers Due to the very large volume of mail that has been received by this department in the past, it has been impossible to answer all of the inquiries as rapidly as could have been wished for. Now, however, due to increased facilities, I am pre- pared to answer all mail almost as fast as it has been received and I can at last promise my read- ers a service that will be up-to-the-minute. New Uses for Microphone (Continued from page 70) ports it automatically to the officers on the bridge. If the hull is injured and water begins pour- ing in, the microphone reports the noise loudly on the bridge. Thus ship’s officers know the con- dition of every compartment at all times. Any leak big enough to endanger the ship, conveys a significant microphonic sound to the bridge. In future war, sapping and mining operations will be prevented by alert microphones buried in the earth, which will report all sounds of mili- tary digging. Thanks to the “mike,” large concerns can speed up their stenographic departments. In a Los An- geles office building, a central stenographer takes dictation from many offices over a microphone circuit. A red light gleams if a door in one of the offices she serves is opened. If the man is out, she, many floors below, calls over the micro- phone, “Mr. Simmons is out; he will return at 3 o'clock. Will you wait, or shall I tell him you called?” The visitor speaks into the microphone and expresses his wishes. Thus one receptionist serves many offices. We are familiar with the use of the micro- phone in automotive mechanics. Microphones placed alongside, or even inside, engines, report by sound to the expert automotive worker just what condition the engine is in. Other microphones, placed at mechanical appa- ratus in factories, report to superintendents the activity of the machinery. In California oil fields which have.been sealed in accordance with the new regulations govern- ing conservation of oil, the movements of the oil deep in the earth are reported by microphone. If an adjacent field, lower in level, has not been closed in accordance with the regulations voluntarily accepted by the companies, the flow of oil to the field which is cheating can actually be heard over the microphone. The new condenser microphone, operating over a dural diaphragm placed in front of a gas chamber, was considered the finest microphonic development, until good old carbon again came to the fore with improvements in its design. The two types are now running nip and tuck. The carbon, carefully selected granules of anthracite coal, is placed, like the gas chamber of the condenser microphone, behind a gold-plated dural dia- phragm. coca Thank You for Mentioning Modern Mechanix and Inventions for August When Writing io Advertisers REG. CORD TIRES ‘Size Tires pubes 80x3 $L. “38 $6. 31 0. $ BALLOON TIRES Size Rites, T bes asl zaxa: 40-21 53. 90S -20 Bees SRT RAS WUNNNNNNer oa RNowoNNNOY AAMA: pre OOSOS stof NON-GLARE | HEADLIGHT REFLECTORS Lino ein: RANAR NNNNA GUARANTEED FREE WITH EACH AN a ORDER FOR 2 TIRES cs Seer een 50% more Send Sr oor De osit with each tire order: Balan apos ou send cash In ered eaaet s Y, You sre guarantse, d A year’B Berv- ice or replacement at 3 price, Order today. MIDLAND TIRE & RUBBER CO., pept, 2323 1000-10 West Sixty-Third Street, Chicago, illinois DOO DDOUIDAD NNO: Hennmo poog hi AON WWUNNNNNNNNNNNNYNN” a w Khi SooMMNAUNMUDOUONGS, ap COUPON BE ae | prase? send, mo ull Information ATEN £234 BROADWAY, 9 | 352, sue TRADEMARK ey ELEM MRA GLGM | S00’ Seiseotion: REG. PATENT ATTORNEY PROE ENGINEER i[ iene WHAT IS YOUR INVENTION? Send me a simple sketch of a model for CONFIDENTIAL ADVICE—DO IT CONFIDENTIAL ADVICE—DO IT NOW! 1!.............. Ue rasr ea Resse ty Cocca May Be Possibilities IN LITTLE IDEAS Your own ideas may have such possibilities. To benefit from the profits your invention may make possible, you not only need to invent it—you need to patent it. FREE Book--‘‘How to Obtain a Patent” Book tells you just what is necessary to do and how to do it. There Inventors praise our service, Established 35 years, Fees reasonable. Deferred payments if desired. MAIL COUPON TODAY l A Delay ETA re 8 vic ae ATT TORNEY Costly Ae Eke Sas ASHINGTON A Main Offices Pri fied Pe ila 605 Victor Building, Washington, D.C. (Branches in principal cities) Please send me your free book, 605 HH, ‘How to and your “Record of Invention Blank.’’ Brant Obtain a Patent,” Name Address ....

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A FREE BOOK about and TRADEMARKS Jor Inventors Small Ideas May Have Large Com- mercial Possibilities ... Delays Are Dangerous in Patent Matters The FREE BOOK shown here was prepared for inventors, to show them exactly what steps they must take to secure a PAT- ENT. If_you have an idea, you should send for this book AT ONCE. It will tell you exactly how an application for a Patent is made, what information you must furnish your attorney, and what steps he must take in order to protect your interests. Re- member, inventing an article is one thing—securing the ex- clusive right to manufacture it, use it or sell it is another. Without a U. S. Patent, you cannot expect to reap the profits that your invention may make possible. Send at once for this book. After you get that, you’ll know exactly what to do to protect yourself, I Serve You Quickly and Secretly Anything you wrile me or send me is strictly confidential between us. All letters and drawings are kept in strong, steel, fire-proof files, which are open only to myself or authorized members of my staff, I have secured patents for inventors located in every state in the Union. My organization is a large and eficient one. My practice is confined entirely to Patents, Trade- marks and Copyrights. I have had years of experience in Patent Matters. When you place your idea in my hands, I am in position to pro- ceed at once to secure protectlon for you. My fees are reasonable, and if you desire, I can arrange convenient terms of payment. This Book Tells How your Patent Ap- plication 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 impor- tant to avoid loss of time in getting your application filed; and many other important points. Even a very simple idea, if new and useful, may prove very valuable. You may have much to gain and nothing to lose by send- ing_for this book TO- DAY. IMPORTANT: Please understand that you are not under the slightest obligation in sending for this book. I will mail it, together with the Record of Invention form the same day I receive your request. Use the cou- pon below to save yourself time and trouble. After that, you will be in position to proceed or not as you choose, to make your application for a patent. CLARENCE A.O'BRIEN REGISTERED PATENT ATTORNEY WASHINGTON,D.C. My Location have it witnessed in such manner that it may be of value to you as evidence should the occasion for evidence arise. In my book, I tell you how to use this form to protect your interests (Be sure to write or print name “clearly.) in Washington 1 1 My offices In Washing- 5 Clarence A. O’Brien l ton are convenient to the t 9 Patent Office, and I and i Registered Patent Attorney t faa, dapae DOMN Be : 3174 Adams Building, Washington, D. C. ! fore the officials and Ex- 7 aminers, I Please send at once your book, “How to Obtain a Patent” l § and your "Record of Invention” form. i FREE Record of Invention Blank ! e l Along with my book, T will send you my Record of In- l Bidean ganei Ea R EVD eerren d vention form, also FREE. This blank will enable you , I to make a sketch of your idea in proper legal form and I ADDRES ehi a ena rA AARAA EENE SE ki abe iiie ane daa I i I I 1 : t HH Thank You for Mentioning Modern Mechanix and Inventions for August When Writing to Advertisers

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A Sales Opportunity for Every Man Record breaking is no new stunt for Pyroil. Since it was first intro- duced, this spectacular lubrication development has constantly “hung up” records of amazement not only in performance but in sales, as well. With its long record of achieve- ment, sales of Pyroil to thousands of enthusiastic users, filling stations, garages, automotive and accessory dealers, are practically pre-made. A tremendous, constantly growing demand for Pyroil exists in prac- tically every city, county and state in the Union as well as Canada, Alaska, Honolulu, Cuba, South America and other foreign coun- tries. Our continuous and increas- ing programs of International Ad- vertising assure this demand. It takes many men to adequately supply it. . (See Saturday Evening Post, June 17, 1933—Time Magazine, June 119, 1933.) Agents Constantly Needed To fully supply this already created, fast growing demand, Pyroil now offers one of the most attractive, quick money making op- portunities of all times to men everywhere. No experience needed. No large investment. Any man should easily qualify. Start im- ‘mediately, earn unusually big profits every day. Permanent or temporary, as you like. Openings no matter where you live. If you want to profit and prosper, don’t fail to investigate the Pyroil Opportunity without further delay. Pyroil is manufactured, Pat- ented and Guaranteed by Pyroil Company, W. V. Kidder, Pres., 683 Pyroil Bldg., La Crosse, Wisc, U. S. A. The proof of Pyroil is in its performance. Protects motors against wear and damage. Increases power. Frees sticky valves. Seals rings. Reduces carbon. Saves on oil and gas consumption, Saves repairs, Saves far more than its slight cost. YR “LUBRICATING PROCESS April 17th, 1933, Trough Brothers, Pawhuska, Oklahoma, ended a new World record dry-run of 903.4 miles with the Pyroil-treated Chevrolet automobile pictured above. At the start of the dry-run, all oil was drained from the crankcase and the motor sealed against tampering. The car was then driven loaded at speeds ranging as high as 40 miles per hour, for the distance of 903.4 miles. This entire test was officially attested and sworn to by Kenneth S. Trough, Pawhuska; Paul H. Smith, Commissioner Osage County, Okla.; E. A. Stone- house, Mgr. Southwestern Bell Telephone Co., Pawhuskas W. W. Greggs, gr. Railway Express Agency; O. W. Henson, motorcycle policeman; Leon Davis; Rev. Robert Thompson; Dr. J. D. Connell; Jas. R. Grinstead. (Former World’s Record of 745 miles, established under affidavit July 9, 1932, at Halifax, Nova Scotia, with a Pyroil-treated Jewett automobile.) Send for FREE DETAILS Genuine Pyroil is patented in U. S. and Canada by W. V. Kidder, its inventor, Packaged in copyrighted, lithographed cans, identi- fied by the winged Pyroil Trade-name (Reg. U. S. & Canada) and signature of W. VY. Kidder on every label. Not sold under any other name. PYROIL COMPANY 683 Pyroil Bidg. La Crosse, Wisc., U. S. A, Please send full details of the Pyroil Sales Oppor- tunity in my locality. Also Story of the New oo Record just established and Pyroil Trial Test er. Name session vice janie TEEN NEN President EEL BAAS sodus anisa DEn EEEE YannNNENERANANENNEZREANERNEN:

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“Just to use up an old cut,” explains Andy, ‘I’m answering a host of nuts who wrote in wanting another look-see at the seaplane job (non-flying) that ran last month. Here she is before covering, Andy’s Shop Mail Box Andy takes himself a well-earned vacation in California, and prior to shoving off he leaves a load of threats to keep things going smoothly for his pet pig while he’s away. HE time has come, as the Walrus said, to look at many things. Tve been sitting on my haunches in and about the old Robbinsdale hangar now for a couple of years without ary being able to get away, and now what with summer coming, I’m loading up the old DH Moth with an extra quart of oil, sewing a five dollar bill to the underside of the cockpit cushion to protect me from myself in my wild-sailor spending sprees, and one of these days you guys in California will see me hopping over the hedges to Louse Angles, where theys a lot of stuff I’ve been missing and need This Comedy Ford at last has been claimed by her owner and builder, an anonymous nut who lives in Soquel, Calif. 10 to get caught up on. I'll be there when you read this. And before I go I’m laying down the law to keep things intact until I get.back. More of that later. xo p Ive always made it a rule not to run an anonymous letter. And the only reason this is anonymous is because I lost the envelope con- taining the gent’s name. But the text is worth digesting: Soquel, California, P. O. Box 283. Dear Andy and Gang: Boy, I’ve got to hand it to you and Double M for publishing the sweetest mag I ever read. I have enjoyed reading letters in your mail box next to what you have to say for yourself, I am sending you a picture of the Comedy Ford which I built from details which ap- peared in the February issue of the good old M.M. Wow, talk about a riot, you would think a circus was in town the way people run out of doors and alleyways, people on the side- walks all come to a stop to watch old Liz caper around and do her stuff. I nearly got a ticket for blocking traffic. Everybody stopped to watch old Liz perform her new- born self, Modern Mechanix ant Shot was taken by Sam Wing.” EENM EE Built by a pal of Leslie Long’s, this Church Mid Wing has given a rousing account of herself with that highly successe ful Long-designed motor, the Harlequin. Les has more to say anent the motor and ship elsewhere in the column. I have two more short jack shafts for Fords, so if any of the gang would like one, to build up their Comedy Ford, I will sell them reas- onable. Always yours for old M.M. and M. P. mags. THE CALIFORNIA GREASE NUT. P.S. Since reading the good old M.M. I can just about make or repair anything you want except a broken heart. aoko Here’s a chap-who has taken a Modern Me- chanix and Inventions design and done an in- telligent job of following the plans. Witness the views of Mr. Warren La Barre’s “Whizzer,” de- signed by Westy Farmer and included in the cargo of “How: to- Build 20 Boats.” Mr, La Barre’s letter: Dear Andy: This is the first. time I have written to you although I get the M.M. every month, and I think it is a swell mag. I am sending you a couple of snapshots of the boat I built from your plans of the “Whizzer” but I changed some of the things a little. The hull is made of 1⁄4” plywood which I soaked in linseed oil, painted with three coats of paint and two of varnish. It does not leak a drop. It weighs about 175 Ibs. with motor and draws about 4 in. of water. The motor is a HD-74 and is mounted on part of the frame. It is braced up with 1” water pipe and Y4” steel cable crossed, with turnbuckles to steady it. The prop is made of three pieces of ma- hogany glued together. It is four feet long and has a four-foot pitch. It will go about 25 to 30 m.p.h., depending on the wind and current. Everything else is made from the “Whizzer” plans. Always a M.M. reader, Warren La Barre, 903 N. E. Portland Blvd. Portland, Oregon. *o k & Later Pm running a letter from Harry Lowe Brownback, a swell gent, by the way, who has something to say about the matter of patents on these hydro-gliders. ee | This letter might be prefaced with a thousand comments. I’ve written all of them and scrapped all of them, so I’m running it as is, wiping a salt tear away from my face for you-know-what: Dear Andy: Looks as though you were leaning slightly away from amateur light planes. I would be sorry to see you leave the game. I wish you could see fit to run the article and sketches en changing my Longster over to take the Harlequin motor. You will recall that you had me make up the drawings and the article was promised for publication in MM as soon as the Harlequin series was done. I have had a number of letters asking when it would be out. Last winter I sent you a couple of shots of a Church midwing powered with a Harle- quin, and these have not showed up either. Wish you could run them in Andy’s strip. The motor is certainly satisfactory, There (Continued on page 12) These views are of the “Whizzer,” built to Farmer’s plans, by Warren La Batre, of Portland, Oregon. says he gets about 25 miles per hour. Lefé, the little hydro out of ber element, and right “getting out and on it. Inventions for August 11 Mr. La Barre =

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Solar Telescope—s1.25 se Egustsicg Sonar a Wacn Ta A ey apam inuetoaaeay “Ate sm ee RH lo sito Cetated "wil a 1h JOHNSON a Dept. 215 HAGINE, Wis. FORTUNE TELLING BY CARDS| a auuany (22 dopuit Mbyn Wnting eo dduartiters STEAM con Electric Telegraph Set Ee Sar hat yon, Pi) atout ANE pitani Anta BLANK CARTRIDGE PISTOL oe Prices SQ $400 1s) fous gal, Bidcla, 38 THROW YOUR nto n trink, nder the bed or anywhere- Lots of fun fooling teacher, puliceman ne_triends: THE VENTRILO a lito the oul? 2 JUFINSON SMITH & CO. Dest m9, RACINE, W15.| pi ‘quisnt and the Tar 10 cents post EE Con Dept 919, Rcino, Wis, EM JUNASON SAITA A Cu Dept 19, RACINE, WIS: | a at oe At oe she Fhe Yuu Jor steaming atyases ‘gchaaie wad tmoresdons hy four Pie à 15

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+ Jumps from plane at en See ¢ Falls 144 i m.p-h. Speed slows to120 mph in denser atmosphere 4 l i 1 I I Opens chute at 5500ft, Worid’s record for a delayed- opening parachute jump now rests with John Tranum, English jumper. He leaped from a ship more than four miles high, fell to within 3500 feet of the ground be- fore pulling the rip cord. He was falling slower when he opened chute than before. 30 Another trans-continental non-stop record was set by Capt. Frank Hawks in his fast Northrop plane. Elapsed time of 13 hours 26 minutes from Los Angeles to New York cut more than an hour from his own previous non- stop record. Most notable feature of flight was the fact that “Mr. Zilch,” Hawks’ robot pilot, flew the ship most of the distance, The robot pilot, gyroscopically com- trolled, has previously been described in this magazine. Modern Mechanix and A genuine flying wing is the bat- wing plane shown above, created in South Bend, Indiana. Safety is the prime feature of design, the ab- normally large wing surface ena- bling ship to descend nine feet a second, a gentle speed compar- able to that of a chute jumper. Setting a new record in his 51-hour hop between New York and Norway, Jimmie Mattern, on a round-the-world flight to better Post and Gatty’s record, encountered difficulties farther on and contented himself with establishing a record on a solo world flight. Interesting is the fact that neither Mattern’s nor Post and Gatty’s flights was truly “round the world,” but rather “top of the world” trips. A true circle flight around the world would cover 25,000 miles, divide globe in two, as indicated in drawing. Inventions for August 31

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Streamline RAIN SHeralds “ WEIGHT OF {ORDINARY \PULLMA! Interior of new aluminum Pullman car, weighing but half as much as conventional steel car. Note air ducts in ceiling. 32 T Vie "e Features of carefully streamlined train under construction for Union Pacific Railway ate given in drawing. Note clean, cinderless Power mechanism—Diesel engine hooked to generator and motor on front trucks. At left, three-car streamlined train. weighs no more than ordinary Pullman. by ROY DEAN Super-speed railway trains are here— rivaling airplanes in swiftness, gliding along in luxurious silence, resembling trains no more than the Leviathan looks like the flagship of Columbus. An amazing new era in railroad transporta- tion is forcing present-style trains toward the junkpile. The “why” of this aston- ishing revolution in travel style is given in this absorbing article. FEW months ago Mopern MECHANIX AND INVENTIONS published an article calling attention to the need for an entirely new type of railroad train which would give passengers cool, clean, quiet transpor- tation free from the annoyances of cinders, blasts of desert air from outside, the jerk- ing and swaying of cars in motion, and the endless click of wheels against rail joints. Now such a train is in actual process of construction for the Union Pacific Railway, and transportation experts are unanimous in the opinion that its design opens up a new era in rail travel which will eventu- ally force the heavy steel trains of today, with their fuming coal-burning locomo- tives, onto the scrap heap. A real revolu- Modern Mechanix and New Cars of streamline train are articulated—one truck between two cars and the cars hinged to- gether. By eliminating slack motion, this im- proves riding quality. At right, how speed is gained by streamlining. tion in train design is well under way— belatedly enough, when one considers that except for size our present locomotives are not essentially different from those used a hundred years ago, and there have been few new principles in passenger car structure since someone thought of putting a roof over a floor on wheels. Competition of automobile, bus, truck and airplane has finally forced the rail- roads out of their inertia, made them real- ize that plenty of passenger business is theirs to command if they furnish tbe pub- lic what it demands in the way of economy and comfort. Power Needs Reduced by Half That the Union Pacific train fills this bill to a T, there can be no doubt after a study of the design reproduced above. It is fully streamlined, and this, in conjunc- tion with its light weight (the three-car train weighs no more than an ordinary Pullman) makes possible speeds of 110 miles an hour. To the airplane is due the development of aluminum alloys which reduce weight two-thirds. Each car of the new train is tubular in shape, giving great strength. Streamlining of the train is. carried farther than ever before, so efficiently that it is esti- mated power requirements at 100 miles an hour will be only half that required for con- ventional trains. Windows are placed flush with the walls, ` vestibules between cars completely covered over, and headlights and other projecting units are recessed into the body. Outside air never enters the train. Three ducts keep Inventions for August 2. SMOOTH AIRFLOW OVER STREAMLINED TRAIN Era for RAILROADS VENTILAT~ “ING BUGT INDIRECT À “LIGHTING = | Right above, cross section of new train. Note the three ducts for forced ventilation of washed air. All cars are completely sealed against outside air. Note the tu- bular construction of body which gives great strength. Rounded- end of new Pullman car, interior of which is shown on opposite page. “Steel, too heavy, is out of the picture in new railcars; light metal alloys take its place. 33

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HINGS ‘You Mustn’t Miss at (Chicago's WORLD Fair IHICAGO’S Century of Progress Exposi- spots will be welcomed—hence the picture tion—more familiarly known as the map reproduced on these pages. It doesn’t World Fair—has been open long enough for pretend to exhaust the possibilities of the visitors to realize thal if they are to “do” Fair; it would take a volume about the size as the show completely, passing up none of of an unabridged dictionary to do that. But heSky Ride/ | its features, they will have to devote all it does point out features which early Fair Jest thrill of | their waking hours for the next six months visitors have found to be the most interest- : gge tions a to the purpose. So crammed is the exposi- ing of them all. If you have only a day or he Exposition~ | tion with marvelous exhibits from all over two at the show, take the map along for ; , the world that some sort of guide tothe high your guidance. private lives of. fishes-from sar. dines to sharks Adler | Planetarium — Where ŝun tno and stars go through their paces for you dont go in here f you have il sins about mans power in the tniverse S 2 | Sereets of Paris 4 nother high spot -cafes dance -~ . palls~ete.° Amusements | 57 varieties of thrills- | Electricity 7 gull of marvels S that. keep Specs tators pop-eye suchas talki _kitchens-rays that melt saw blades without \ Enchanted Islond paradise for the youngsters-cand. Massacre, a mountains, toy | injuring huma mazing me -h every- A 3 ical ‘thril _ thing (park the hands- ete. World’s largest stage is be- : makers. ing built in Soldier’s Field. kids here) Daily the pageant of trans- portation is. presented in the Travel and Transport building—an education- al show in which every A mechanical means of transportation is seen “ini person.” The amusement section in the Midway is crammed with entertainment concessions which relieve with a sideshow touch the serious purpose of the Fair. The Fair grounds are more tban three milés long, half a mile wide. Visitors may not realize that much of the ground on which the buildings are erected wasn’t naturally ground at all, but the bottom of Lake Michigan, Dredges reclaimed it for the use of man, creating real estate values out of worthless mud. 38 Modern Mechanix and Inventions for August 39

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“ORICK (Camera Shots Help _ FRONT VIEW— FOLLOW THROUGH. SIDE VIEW— FOLLOW z THROUGH Photo at right shows how to bring the powerful muscles of the mid-section of body into action behind the stroke, Above—All in white, Bobby shows correct position of the entire body in following through after hitting the ball. Right—his right arm, standing out in ddzzling white contrast, in Proper position for addressing ball. HE use of the movie camera in teaching golf is nothing new—it’s been used any number of times to explain fine points of the game’s technique _in such a manner that Mr. Duffer can presumably. go out on the course, after studying the movie, and wind up joyfully at the 18th hole with a card of 120 or thereabouts, repre- senting something like a 25-point improvement. But it has remained for Bobby Jones, king of them all; to devise some brand new photographic tricks for his new Warner Brothers movie “How to Break 90.” In addition to stop-motion photography, which enables Bobby to halt his swing in mid-air while he stands alongside himself and explains what he is doing, he wears an assortment of trick black and white costumes which emphasize the action of dif- ferent parts of the body in executing the perfect golf stroke. Some of the striking results of this photographic technique are presented on these pages. With Bobby standing against a black backdrop, dressed entirely in black except for the limb clad in dazzling white whose action is explained, the eye is not distracted by extraneous details. Essential points of the Jones golf technique are brought out in these photos for the benefit of MODERN MECHANIX AND INVENTIONS readers who may wish to 42 Modern Mechanix and Photo below shows position of left arm, Note also how Bobby stands behind the ball permitting bim to move into the shot as he swings. SBOBBY JONES Geach Gol FRONT VIEW AS DOWN STROKE STARTS—notTe HOW LEFT HIP 1S MANAGED Te is important, says Bobby, that left side be taut from hip to hand, as shown at left, when starting the downstroke. = TOP-MOTION AT: BACK SWING. Above—Bobby points to a stop-mo- tion picture of himself and explains what he is doing. Left—this picture tells better than a thousand words the importance of a straight right leg to give driving power, on the familiar fulcrum and lever principle. TOP OF SWING— NOTE POSITION OF RIGHT LEG PUTTING POWER INTO STROKE improve their game. Cor- rect address or position as one stands to the ball is well shown in three of the pictures. Note that Bobby stays behind the ball where he can move into the shot as he swings through. He says it is best to avoid try- ing too hard to force the body into a mechanically set position, as it is likely to set up muscle-stiffening tension. Few golfers, Bobby says, move their hips in the correct way to add force to the drive. Powerful muscles of the back and waist cannot be brought Downstroke swing should be ini- tiated by the hips rather than arms. Photo below shows proper grip. PO s properly into action unless the hips are turned in NS enough to enable the club to swing down to the ball DR from the inside. Slicing and pulling are attributed zi to this fault. In the photo illustrating the top of swing, note how Bobby’s right leg, in white, is placed to bring the powerful body muscles into play behind his stroke. The front view of the downstroke gives a tip on the important matter of handling the left hip. Bobby regards it as important that the hips should move first on the downstroke, before the arms, the left hip leading the turn back to the ball. The entire left side should be taut, from hip to hand, when the club is at the top of the back swing as illustrated. In the actual movie, slow-motion photography is used while the sound track carries Bobby’s own voice. Inventions for August 43

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“DEPRESSION Spurs Lost Gold (REASURE Stunts Charles Courtney, master locksmith, who recovered part of the sunken gold of the Hampshire. He tells of his adventures in this article. {{OLD, down through the ages a symbol of wealth, has now become so doubly priceless that we in this country may not even legally possess it! Beyond a doubt that is one reason why so many expeditions are at work today recovering the gold of other ages—gsold which went down weeks or years or centuries ago, and since that time has been resting uselessly in the mud-filled hulks of ancient galleons. Just how many submarine treasure-hunt- ‘ing expeditions are at work today it is im- possible to say, since many of them sur- round their activities with a veil of absolute secrecy. The purpose which this secrecy serves is easily understood when one rea- lizes that the treasure lure may bring rival 44, by BENNETT LINCOLN Treasure long lost under ocean waters is the golden loot which is luring half a dozen expeditions to recover it, spurred on by the urgent need for gold developing out of the present economic - conditions. Charles Court- ney, master locksmith who battled death to recover $60,- 000 from a sunken treasure ship, tells his story of high adventure in this fascinating atticle. salvors to the scene ready to do battle for sunken loot. ; A few days ago a coast guard. cutter was despatched to a point 60 miles off the Vir- ginia Capes where two rival treasure ships were threatening open conflict. The lure in this case was the sunken Merida, which went down 20 years ago after a collision, carrying a reputed $6,000,000 in gold. The trawler Theresa and Dan and the tug- boat Salvor were both anchored in the vicinity of the sunken ship. Each called for assistance to prevent an open clash. Even- tually both ships retired and the Merida’s gold still remains for the lucky salvor. Perhaps the most striking of recent hunts for lost ships is that in which $60,000 was recovered from the sunken Hampshire, the ship on which Lord Kitchener per- ished June 5, 1916. With the boat went down millions in gold which was being } carried to Russia. Just how the wreck of the Hampshire was located in the face of unbelievable difficulties by a “Mr. KX” who spent four years tracing down a Ger- man who worked on the boat which left the mine that sank the Hampshire, is a story in itself. More thrilling were the adventures of Charles Courtney, master lock- smith, who personally . recovered a strong box from the Hampshire’s safe containing $60,000. Readers of MODERN MECH- ANIX AND INVENTIONS At left—Courtney bored open the sunken Hampshire safe with a grindstone drill and removed a a strongbox containing 360,000 in gold. He had to work with extreme care to avoid setting off possible T.N.T. triggers within the safe. Modern Mechanix and Charles Courtney’s long battle with death when treacherous currents crushed him irresistibly against the hulk of the sunken treasure ship, is illustrated. In circle—how telephone communication is maintained. Map shows sunken Hampshire. Inventions for August 45

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Treasure Wrecks Dot Shores of Our Continent—Many Still Unfound i, SOPHIA AND SLANDER, dost miners golg Mais Pi breasure ea joe, en ias i | region Ee 1AFITTE À me i W Brand new diving ap- paratus, suitable for treasure salvaging, just tested by British officials. Air supply is cartied on back of the suit, making air lines to surface un- necessary. Limb joints move flexibly on an oil cushion. will remember Mr. Courtney’s own story of kis methods of opening the safe on the sunk- cn £gypt in an eminently successful salvage venture which up to date has recovered $3,250,000. Mr. Courtney is president of the Ameri- can Association of Master Locksmiths, and so widespread is his fame that when a man was needed to unlock the safes of the 45 Some of the wrecked treasure ships of the American continent are pointed out on this map. These are only those which -have been definitely located and on which salvage work has been done. Scores of others lie in spots as yet unknown, waiting to be found through old records—just as the location of the De Braak with its fabulous $40,000,000 in gold was recently discovered after long search. Hampshire, Mr. X came from the other side of the sea to seek his services. Courtney accepted the commission, veiled in secrecy, little knowing that before he had completed his contract he would very nearly have paid with his life, and that he would carry a shattered wrist and hair prematurely whit- ened by terror as a permanent reminder of a disastrous bout with death. Sitting in his New York office, the master locksmith told me the terrifying story of his experiences for readers of this maga- zine. He told me of being taken aboard the salvage ship, of a zig-zag course taken to the treasure site to elude possible pursuers, of the location of the wreck—and finally of his own part in the drama. “Right after the ship was identified, I started my diving work. I went down and with the use of a grindstone drill succeeded in boring open a built-in safe in the ship. That was a mighty difficult job, crackin that safe. I had to guard against T-N- triggers or other safeguards which its mak- ers might have secreted init. I blew it open without mishap, however, and withdrew from it a strong box which I later dis- covered contained about $60,000 in gold. “I went down once again after recover- ing that strong box with the $60,000. You see there was no possible way of opening those safes without my presence down there. It was impossible to calculate the nature of the tumblers because of the havoc Modern Mechanix and Long Lost De Braak, Carrying $40,000,000, Found After Long Search of time. The only method we could employ was to locate the safes and figure out the best and most harmless way of blasting them open, and still regain the treasures they held. “By April 24 there had already been a great deal of blasting work. This was the day when we were to reap our hard-fought for harvest. There was $10,000,000 lying there waiting for us to bring it back to civilization. “Down we went, Costello, Samuel Mansfield, an adventurous youth from Virginia, and myself. We were in our aluminum suits. We had the customary equipment and auxiliary devices. We used our telephones constantly, keeping in com- munication with the engineers on deck of the salvage boat. As my two companions and myself were let down on the second descent the first 100-foot drop was without a hitch. At 200 feet | was suddenly seized with misgivings. Something was wrong. “I was cut off from communication with my other two comrades. Fear of darkness overcame me—darkness as smothering, as all-enveloping as the inside of a coffin. “Bring us up quick! We’ve been struck by an undertow!’ I yelled desperately. “But no response. No signal or other token that those on the surface got my S O S. Having had experience as a diver I tried to be calm. I figured, or tried to ‘figure as calmly as I could, that those above were waiting for the current to ease. I Inventions for August The De Braak, sunk off Cape Henlopen, Delaware, decades ago, is a hulk reputed to contain $40,000,000 in gold, It has just been locate Robertson after a long, romantic search through records of the period. Salvaging will be done by pumplines, sucking up mud and cleaning the “bones” of the hulk to make it easy for divers to lay hands on the drowned gold. Inset photo shows the powerful pumplines being tested. The Photo at right shows weird machine used by syndicate to recover gold from the Islander, sunk off Alaska. Some gold was recovered when dissension among members forced temporary abandonment of scheme. by Allan C. could not budge the cables. The electricity was cui off so that there could not be a short circuit. “In another moment I was seized with a terrifying sensation. As I dangled there helplessly, hoping and praying for rescue, my suit was cut in the right side. I was flung violently against the side of the Hamp- (Continued on page 8) 47

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Ancient Medicine Men The ancients believed that the stars determined the course of human affairs, Astrologers consulted the zodiac, shown above, to learn when it was safe to bathe, get a haircut, take medical treatment, and so forth. by Shrine at Lourdes, France, showing EARLE R. BUELL gots, osred sons cured by faith. Cheer up, have faith—it’s good for. your health. That’s the verdict of scien- tists who have been experimenting to determine effectiveness of remedies em- ployed by ancient medicine men, as- trologers, and modern faith healers. This article explains why some people actually do get well when they have a strong belief they are going to get well. PTIMISM is better than apples for keep- ‘ing the doctor away. _ There is a scientific basis for faith heal- ing. Even some ancient superstitions had healing power and the hocus-pocus of the tribal medicine man may have saved many ives. These are some of the conclusions arrived at by.a group of experimenters who have been endeavoring to test out the effect of states of mind upon the general health. Applying the scientific methods of the clinic and the laboratory to their work, the investigators at first set out to find out which if any of the healing systems widely practiced by various cults could be shown to have any therapeutic value. Very much to their amazement they found evidence that not only these cults but any religion de- voutly accepted by the individual had cer- tain definitely traceable physical effects of a beneficial nature. The discoveries went even farther, indi- 52 HIGH BLOOD PRESSURE HIGH B TYPE PRESSUR Worry, desponden- cy, grief, pessimism are fatal to health. These emotions cause high blood pressure, Victim may seek relief from nervous tension in drink, which leads to weakness of heart and early death. cating that any optimistic or inspiring thought was valuable for healing and that some miraculous appearing cures had actually been effected by the reassuring words of a doctor in whom the patient had confidence without any treatment at all. On the other hand, it was found that a long list of emotions related to fear had ex- actly opposite effect and that to embrace a philosophy of pessimism was about on a par with warming an asp in the bosom. Modern Mechanix and 4 a UNN OW While mystic hocus-pocus of at- cient medicine men was scientifi- cally impractical, it actually cured some sufferers who strongly be- lieved they were going to get well. by means of the blood NORMAL. BLOOD PRESSURE TYPE _ Optimism, faith, cheerful- ness tend to keep blood Pressure normal, resulting generally in long life and vigorous old age. No strain is put upon heart, so that it remains sound through- outlife. Religious faith thus has a scientific justification. Instead of being able to find out which sect was nearest to the truth as had been intended, experimenters found that truth or falsity of a sincere belief seemed to make no appreciable difference in its curative effect. This gave rise to the realization that countless supposedly silly superstitions had probably improved the health of those who believed in them. As a result, there arises the possibility of testing the sincerity of religious convictions Inventions. for August pressure gauge and other instruments and, while it is not suggested that these instruments will be installed at the church altars, there is said to be ample evidence that posi- tive results could be ob- tained by this means. The findings of the experimenters have dovetailed to a large extent with those of Dr. William S. Sadler of Chicago Uni- versity, although the experimenters were without a knowledge of Dr. Sadler’s works, and they are taken to be mutually cor- roborative. They are said also to be in line with the prophecy of Dr. Charles P, Steinmetz, fa- mous physicist, who shortly before his death predicted that science in the near fu- ture would turn to spiritual matters and that developments in this field would be similar to those in the physical and mate- rial realm. One of the more remarkable discoveries recently made is that there is apparently a scientific basis for the healing principles of faith, hope and charity or love as described in the Bible and it is indicated that any in- spiring writings and the encouraging or uplifting words of any admired or revered speaker may be sufficient to effect rather startling cures in some instances. The time may very well come when a doctor’s prescription will read: “See your priest, minister or other religious adviser.” Public intuition has for some time been directing large numbers of persons back to their churches for physical as well as men- tal and spiritual assistance, it is said, and a period of increased interest in the church is prophesied. Beginning first with a study of religious 53: Worshippers pray- ing at grave of a priest for deliver- ance from physical ailments. Belief. in potency of prayer frequently results in cure, experimen- ters have found.

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GETTING More LIGHT On the eATOON & cm Frazee Moon’s diameter, 2,160 miles, may be vivid- ly perceived by this comparison of lunar area with area of Texas. Right is seen a sea urchin, inhabitant of Red Sea, which spawns only when moon is full. Scientists are now trying to determine whether moon is re- sponsible for this periodicity of reproduction. E IS unwise to dogmatize about the fu- ture, and hence a cautious man of science would hardly make the positive as- sertion that human beings will never visit the moon, though the difficulties involved in such a journey now appear insuperable. On the other hand it is quite safe to as- sert that, without leaving his own planet, man will learn much more about the earth’s satellite in days to come than he knows today. This expectation is based upon the remarkable progress accom- plished in the study of the moon in recent years. Here are a few achievements that would have seemed utterly and forever impos- sible to astronomers of a century ago: It has long been realized that the lunar surface must get intensely hot during the long lunar day and intensely cold during the long lunar night, as the moon has no atmosphere—or none to speak of—to tem- per and conserve the heat of the sun’s rays. Science could only speculate, how- ever, about lunar temperatures until a re- cently invented instrument, the vacuum thermocouple, was attached to the big 100- 60 AP > Some astronomers believe that giant lunar craters were created by terrific im- pact of meteorites striking the surface, digging huge pits, as illustrated here. Lines radiating from these craters, scientists believe, are Streaks of molten rock that splashed out when monster meteorites collided with the moon. Entire surface of moon is spotted with these exceptionally large craters, similar to one in Winslow, Arizona. Modern Mechanix and Piece eeu COATING: Features on moon’s sut- ET aa face appear in true perspective when section photo is projected on globe, When sun’s rays strike vertically on moon’s surface, temperatures immediately beneath and at edge of illuminated area vary to extent illus- trated here. With no sunlight, thermometer drops to —240 F. Atleftissupersensitive ther- mocouple which measures stellar temperatures. inch telescope at Mount Wilson Observa- tory and applied to the actual measure- ment of these temperatures from point to point on the surface of the moon. These measurements show that wherever the sun’s rays fall vertically upon the moon the surface becomes a little hotter than boiling water, while at the edge of the illuminated area the surface is nearly as cold as liquid air. When the solar rays are withdrawn during the lunar night, which is half a month long, the surface gets colder and colder until its tempera- ture is probably as low as 240 degrees be- low zero Fahrenheit. A range of about 450 degrees between midday and midnight is one of the reasons why human visits to the moon are appar- ently impossible! Though bygone astronomers did not be- lieve the moon to be made of green cheese, they did not know, as we do today, that the surface material must consist mainly of some material similar to volcanic ash or pumice. This has been proved by Prof. (Continued on page 22) This remarkable drawing shows you just how an eclipse of the earth would appear to an inhabitant of the moon. 6l Inventions for August

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by COUNT BYRON de PROROK Priceless jewels worn twenty centuries ago by Cleopatra, vampire queen of ancient Egypt, have at last been found deep in the torrid, sandy wastes of the Sahara. Here the leader of the intrepid expedition, famous archaeological explorer, tells of the amazing adventures he met with on the perilous quest.

that have come down to us as the most glamorous of legends. i This much was fable, but was there any basis to the legend? In years of explora- tion in desert regions, I had heard this whispered tale a thousand times, hardly daring to believe, or to hope that I might find them. But I have! In a mysterious cavern on the heights outside the desolate city of Garama I came Count de Prorok peering into subterranean to the end of my long hazardous quest for chamber, unvisited for 20 centuries, in which the hidden jewels. There after two years he discovered priceless emeralds of Cleopatra. Of scouring the torrid desert, I ended an adventure that had included skirmishes with wild desert tribesmen, tortuous treks over thousands of miles of sandy wastes, and discoveries of cities long lost to civili- zation. While the expedition worked among the ruins of the old Garamante city, I explored the neighboring territory, and came upon the dark mouth of a cave which, my guide pointed out, held the possibility of contain- ing the long-lost gems. Ancient symbols carved on the rocks gave me the first token of my quarry. Torch in hand I crawled into the narrow opening, and after moving forward a few

OR twenty centuries amazing tales of the legendary emer- alds of Cleopatra, supposed to be buried somewhere in the desert sands, have intrigued the imagi- nations of adventurers, sent them wandering over burning deserts, lured by the quest of fabled jewels once worn by the most romantic woman of all history — jewels which Antony may have given her, which she may have worn in those fabled scenes of history

62 Modern Mechanix and

yards, found I could stand upright. About me lay a strange breath-taking scene. The flickering light of my torch threw grotesque shadows on the walls, re- vealing rows of ancient hieroglyphics. . In the dim light I stumbled upon the remains of old household utensils and implements of war—swords, arrows, spears. Down in the midst of these objects I spied a dust-encrusted bundle wrapped in a winding sheet. I prodded it with my stick and it fell open— rotten with age. But as I thrust about seeking to de- termine its contents, an amazing scene greeted my eyes. There among some bits of broken pottery lay the object of my quest—a handful of deep-green stones. It is difficult to describe my joy as I examined these relics of antiquity and realized that I was holding ornaments that once bedecked the person of the famous vampire queen of Egypt. To make sure that I had found the gems I was seeking, I compared them with several emeralds I was carrying that I had taken a few years pre- viously from a beautiful necklace I dug out of the ruins of Cleopatra’s summer palace at Merza Matruh, where she and Antony had spent their last hours together. The Merza Matruh stones were of the same quality of the ones I had just found, so I knew I had found the long-sought emeralds. How my expedition, made under the auspices of the Italian Government, toiled over the barren wastes of Africa’s Sahara, makes a thrilling story. Ever since I first visited Africa I had been hear- ing weird stories about the mysterious emeralds of Cleopatra, reputed to be of fabulous value, from divers historical and native sources. It appeared that most of these stories, originally told by the ancient Egyptian, Roman and Cathaginian nobles, were still being told in the city of Ghat, far South camel on which he explored the in the desert, once the great slave center of the mysterious regions of the Libyan SENN Mussolini’ 1 fon camps Wo-the rine oe Tons i remier Mussolini’s personal permission I i OF otis was able to lead the first scientific expedition ane be Ae od noie acros the newly conquered Italian Libya to this oie Severus. The explorers are egendary city o at. Our personnel was com- Se tone E e OF ee posed of 18 men, including ten moving picture Serer <a. bach iend a: shares men — mechanics, students and specialists — as well as two Arab guides. Our caravan, while it in- cluded a number of well-trained camels to be used for short trips, consisted mostly of six especially constructed French Delahaye

Count de Prorok on his favorite

ae

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Aeneas: aged How central stenographer in Les Angeles concern takes dictation from many offices over mike circuit. va | At:the stenographic end of the microphone circuit over which letters, contracts, etc., are received from offices, When office door opens a light flashes on the switchboard, If occupant is out the operator takes the message. p 68 Broadcast technique of singers is greatly improved by small auxiliary microphones placed over nose sinus and chest. It is unnecessary to “hug” the mike during performance. Once merely a device for transmitting conversations, the microphone has grown today to an instrument of the most diverse uses. Read here how this amazingly simple, yet amazingly sensi- tive, electric “ear” can guard our coasts from surprise naval attacks, how it warns of perilous pressures at mighty dams—and how it serves with equal effi- ciency the surgeon and auto mechanic. PERHAPS the most amazing evolutionary progress of modern days, as differen- tiated from purely inventive progress, has been in the field of the microphone. So much so is this the case, that it might almost be said we are living in the age of the microphone. Far afield has the microphone gone from merely translating human voice into electrical impulses and back to voice again. In the vitals of mighty dams in the Rocky Mountains, imbedded microphones keep the observers in watch-towers constantly in touch with conditions down deep in the masonry. Earth slides under, or at the sides of, dams are heard in the microphones long before they become dangerous. Excessive pressures of water against the masonry cause significant sounds in the microphone circuits. When the dam care- takers hear these sounds they press buttons which open spill-ways to evacuate water until safe pressure limits are reached. 4 Modern Mechanix. and How net of marine microphones strung along coast 30 miles out at sea pick up sounds of enemy ships approach- ing shore. Operator at listening station can immediately locate the fleet by zone indicators. In the surgical wards of a great hospital, surgeons and nurses bend tensely over an abdominal operation. Instead of the meas- ured voice of the nurse calling off the con- dition of the heart, often distracting the at- tention of the chief surgeon, a pulse of low, soft sound spreads through the whole room. It is the sound of the heart itself, beating over a microphonic circuit. If it slows. dangerously, or otherwise weakens, the surgeon takes appropriate steps to restore it to normal. Thus he is not suddenly obliged to stop his careful work at a dangerous point. Instinctively, he lis- tens to the beat as he proceeds with his work, guiding his work according to the heart’s condition. The sound of the heart could be amplified until it churned with the roar of Niagara. This, however, is never done, unless by internes or scientists ex- perimenting with healthy persons. Indeed, the day is not far distant when the doctor will entirely dispense with his stethoscope, so long the badge of the medi- cal profession, and simply place a micro- ‘phone over the patient’s heart and listen Inventions for August ZONE INDICA Us-COAST TORS SHOW DEFENSE ENEMY FLEET LISTENING STATI FLASHES FIRING | DATA TO GUNNERS. Picturized diagram here illustrates how enemy fleet ap- Proaching coast is located in war time. Sounds of churn- ing propellers are picked up by the operator at listening station who immediately transmits firing data to coastal fort. Ships can thus be spotted before they come in firing range. 3 69

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Profits in Synthetic Toadstools Something strikingly unique in yard or- naments are the concrete toad stools which a Portland, Oregon, man makes for 15 cents and'sells for 75 cents to neighbors, who are glad to purchase such a novel decoration. Making the toadstools is surprisingly easy. Into a mould made from an old chopping bowl—over the inside of which has been spread a layer of old newspapers—pour some cement, imbedding in the bottom a short length of pipe to serve as the stem. The paper forms creases in the top, while painting different shades of green and brown enhances attractiveness of the stools. They-should be “planted” in the ground in groups—which will mean more orders for you.. Servicing. Automobiles Enterprising but jobless auto mechanics wil find a lucrative source of income in a maintenance scheme being worked by a New York ex-garage man. The plan re- quires no shop—you call at the auto own- er’s garage and service his car four times a month. On the first call, you check the igmition; on the second, check brakes and steering; on following calls you grease and tighten up. In short, you keep the car in perfect condition. Giving each car ah hour’s work you can service eight cars a day, totaling 48 cars each week and paying you at least $200 a month. A few hundred circulars explaining your services will help to bring you the 48 customers. It will pay you to. employ a helper to clean interior, windows, dust bedy, etc., gratis. 74 A “housand ‘WAYS This month Modern Mechanix and Inventions ‘proffers another group of tested money making ideas that have brought comfortable depression incomes to readers who con- _ tributed them. Look the items over carefully—one of them A might be the means of solving your unemployment problem. Sharpening Razor Blades An inexpensive razor blade sharpener was the nucleus of a lucrative repeat busi- ness worked up by an ex-soldier in Creston, Towa. At first he set a price of a cent a blade, and sharpened them right at the house. Later he purchased wholesale a large number of wine glasses which he left with the customers so they might have a receptacle in which to deposit the dull blades until he returned, thereby increasing business a great deal. Eventually he started a mail order sharpening service in addition, which kept him busy far into the night. Now he has a comfortable living from a long list of satisfied customers. Income for Radio Fans A radio fan living in Atlanta, Ga., capital- ized upon his hobby and now earns a com- fortable income- selling old radio parts to fellow fans who “build their own” sets. Visiting all the radio shops in town, he found that each had one to two dozen obso- lete “trade-in” battery sets which they were glad to get rid of for as little as 50 to 75 cents each. Next, in his radio work shop, he dismantled each set, salvaged all the use- ful parts, then had a radio repair man test them to determine their values. An ad in- serted in a local paper to the effect that used radio parts were for sale at a fraction of their regular prices brought $5 profit the first day. Advertising in papers in sur- rounding small towns brought his income up to $50 a week. Money in Bleaching Water Forty dollars per week is the average income of a New York city man who man- ufactures a bleaching water for clothes. His product is manufactured at home from a formula he found in Henley’s 20th Cen- tury book of Formulas and Recipes, and sells for 30 cents a gallon. Housewives found his product so satisfactory that he has been able to build up a regular route. He earns now more than he did during boom time, and is thankful he got laid off. Bantam Lunch Boxes Selling “bantam lunch boxes” to workers in factories, on construction jobs, and in offices remote from_a convenient lunch room brings Edwin Delvin, of Springfield, Mass., a profit of $35 to $50 weekly. He gets around to his customers in ‘his Austin business coupe which he has converted into a veritable rolling restaurant. His equipment, occupying all space but the Modern, Mechanix and. TO eMAKE a LIVING BBURNER GASO- LINE: STOVE SHELVES FOR -FOOD Arist’s drawing above shows con- struction of the various compart- ments of the Bantam lunch box. driver’s seat, consists of a small 3-burner gasoline stove built across the rear inside, a small thermos ice box at the front, and sufficient shelves at sides and top to carry such edibles as bread, cheese, hot dogs, etc., as well as cooking and eating utensils. A small show case across the window sill displays cigarettes, candy, etc., at standard prices. Polishing Auto Headlights Cleaning and polishing headlights of autos belonging to business men, store managers, shop and factory workers con- tacted during the dinner hour is the in- genious scheme employed by an Oakland, California, man to rake in depression shek- els. Few inexpensive materials needed are denatured alcohol, a dime’s worth of lamp black and some cotton. Mixture of alcohol and lamp black is rubbed on the glass lenses and reflectors and when dry is rubbed off clean with a piece of cotton, leaving a bril- liant polish. You can carry a can of metal polish to take care of rust or deep tarnish. A charge of 25. cents per job satisfies your customer and brings you a sizeable profit. Keeping Up Vacant Houses A Seattle, Washington, university stu- dent, faced with the possibility of having to quit school for Jack of finances, has con- vinced owners of vacant homes for rent that a well-cared-for appearance is as much a psychological aid in affecting rentals as it is in selling one’s own services. He found, after contacting a number of owners, that they were invariably willing to pay him for keeping up the grounds. He bought a second-hand car and necessary tools, and each evening after classes and all day Sat- urday he .mows lawns and trims hedges, visiting each-house on his list once a week. Inventions for. August Money-making Ad Stunt Thirty-five dollars a week is the profit netted by an enterprising Kentucky man from a novel advertising stunt he devised. Here’s how -you can work it. Find out if there is on the statute books in your state a Jaw requiring hotels to have posted in each room the law governing hotel oper- ation. If this is the case, secure permission from local hotel owners to have some 8x12 in. cards printed with the law set forth in the middie. On the sides of the cards rule off about 20 spaces for advertising and sell them at $2 to $3 each to local merchants. When you’ve covered your town on this stunt, try your neighboring villages. Gather Up Pine Cones If you live in a region where pine trees grow abundantly you’ve no doubt noticed hundreds of pine cones lying around on the ground in the wooded regions. If you gath- er up these cones you can sell them to almost any forestry station for one to three dollars a bushel. It’s advisable first to con- tact your forest ranger station to get prices. A good days work, with prices fair, should bring you an income of five to eight dollars. Glass Signs for Offices Making and selling glass signs to dentists, doctors, stores, offices, etc., will bring you in a heaping handful of extra dollars. Signs most easily sold bear business names or house addresses and are about 3”x9” in size, $1.50 being a fair price. Signs of larger size can be disposed of at prices up to $5. An accompanying drawing shows how these signs are made. If you are not familiar with lettering, secure a book on the subject from the library. Lettering is made from tin foil cut out with a razor blade and pasted on with transparent glue. The bevel- 75

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echanical “Aids Make Life Easier for the HOUSEWIFE € Ultra-Violet P Health Lamp - Heat-Control ‘ You can convert your bridge lamp into an ul- tra-violet lamp with a special transformer and socket adapter now on the market. The sun- bulb is inserted in a special reflector which fits lamp socket. Turn of switch floods room with health-giving rays. wo BELL WILL NOT RING WITHOUT. | INSERTING OIME COIN, WILL NOT | BE REFUNDED TO | CANUASSERS 0@ PEDDLERS ae 2 Inserting coin in slot of this unique lock opens door. Coin is re- funded when housewife admits you. Plate is put over slot when you go out. Labor of shelling peas is reduced to absolute minimum with this automatic sheller now on market. The peas are fed into the hopper with the left hand while the crank is turned with the right. The peas or beans roll out into the dish while the empty pods drop on the other side. Clamps to table as shown, and does a clean job of removing stcings and separating peas and pods. 78. : Electric Plug Temperature control for electric iron, percolator, heater, etc., is provided with this plug having rheostat to govern current flow. Six degrees of heat are at absolute control of the operator. Like everything else, bowling is being deflated too. For instance look at the photo above. Here is a midget bowl- ing alley now on the market which is lots of fun for a quiet little game at home. It’s played pretty much like the regular “ten-pin” game at the big bowling alleys. Ball is slightly larger than a baseball and it tolls back to you in a groove just as in regular game. Modern Mechanix and Shifting nozzle on this new hand vacuum cleaner converts it into a de-mothing blower. Bread Slice Gauge : This handy little invention attaches to the bread knife and enables you to cut. even slices of bread of any de- sired thickness quickly and easily. Bre ake r By: using this new cake breaker, you can divide the most delicate angel food cake into thin perfect slices without even cracking the icing., The prongs are inserted down into the cake, the breaker is twisted slightly, and presto! the piece comes away intact, without-a crumb turned the wrong way. Durable prongs refuse to bend: under. heavy use. Inventions for August Ss All-room mperature _ Indicator Indicator has a dial which tells temperature of any room, base- ment, garage, etc., by turning knob to room in question. Drain Cleaner Recently made available to housewives, this drain cleaner shown above opens up clogged drains by water pressure, doing job more thoroughly than hand suction pumps, it is claimed.. It comes with different attachments which per- mit. its use. in kitchen sinks, bath tubs, etc. May. be attached to any type of faucet. t 79:

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EMECHANICS Aid Art to by DON BLACK It seems a far cry from mechanical engineering to the esthetic intricacies of an oil painting, but the mural mas- terpieces of Dean Cornwell just hung in the Los Angeles Library would have been impossible if the mechanic and artist had not worked hand in hand. Methods em- ployed in fabricat- ing these paintings rade im trike wali, are described here. EAN CORNWELL, internationally fa- mous young artist, has just completed the world’s largest mural paintings. Today they hang on walls of the Los Angeles Central Library, a colorful and arresting tribute to the esthetic genius of this man and a challenge to posterity. But of the thousands who will linger be- fore them in awe and admiration, few will ever realize that these vivid panels depict- ing the early history of California are more than an artistic triumph, that the finished work represents also a distinct achievement in mechanical engineering. For an explanation of this statement, a proper conception of the physical ele- ments involved is essential. In the first place, with a combined total area of 9,000 square feet, these murals dwarf in size the most ambitious efforts of previous masters. Four of the twelve View of the Los Angeles Central Library lobby with the Cornwell murals Dean Cornwell, distinguished artist, who created the mural masterpieces along unique lines. Five full years were re- quired to plan and complete the murals, which comprise twelve paintings containing some 300 human figures. WA a i veia LER Making Preliminary Sketches Step by step process of making the murals. A thousand preliminary sketches were made from living models, then these individual sketches were arranged in ordered groupings and photographed. Canvas, woven in Belgium, cost $25,000. 82 Modern Mechanix and Create Mural Masterpieces Section of one of the large paintings, Colors in the origi- nals were carefully chosen for harmony with the library background as well as within the painting itself. paintings are 40 by 40 fect square, the les- ser eight panels being 20 by 40 feet. Ready for mounting on walls of the library rotunda, the smaller pictures weigh an even ton, the four major can- vasses 3,000 pounds each. More than 300 pounds of liquid blue paint was required to paint skies alone. A total of 100 living models posed for the artist’s preliminary sketches, while the completed murals con- tain approximately 300 human figures. Three scparate and duplicate coats of paint were applied as a protection against cleaning, dust, light and the ravages of time. Finally, it took five full years of painstaking, unremitting toil to complete the task. When awarded the contract in 1927, Cornwell’s first step was an exhaustive research to which months were devoted. When thoroughly steeped with this lore and symbolism, he went to New York and set to work. 7 How paints were applied from a chair scaffolding moved from spot to spot by am assistant standing on the floor. or i 2 i bh y ‘ $ E Retracing Sketches rrom Projected Lines Applying Color to Canvas Hanging Completed Murals ` Photographs of the working cartoons were thrown on the canvas by a powerful projection machine and the outlines traced in exact accuracy. Three separate coats of paint were applied to protect against dust and time. Large murals weigh 3000 lbs. Inventions for August 83

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Be ~ A “DESERT “Gown” Canoe

by A. A. MURDOCH

Not a real Old Town canoe, but an i i amateur’s home built and very service- haon: oe require: only ae able “Old Desert Town” canoe is de- require a trough or ditch for entire i submersion unless one end is done @ scribed here by Mr. Murdoch, who a time, which was found to be satis- WSS GE ORG A built one in Texas, You can do like- factory, and in which case hree fest 3 ypa ise i i ing. of each end is all that need be soaked. pe NALS goza re ! HE 22 wise in graduating to the real thing For want of anything more convenient, py Z 20 the rain trough under the eaves may be MA HH 6 OR us who live where boats of any dammed temporarily and filled. ; j HH sort, even toys, are unusual, the simple While the wood is Soaking, colsteuc! He AB 2 joys of gliding over the smooth surface the jig for forming t e n san ow- <= jo of creek or lake or bobbing over the small pieces. Lay out on a shee! P wrapping LAY OUT JIG HHS waves of cove or bay are experiences paper the cross-section of 1-in. squares s read about in books, or at best witnessed. and locate the points indicated by Fig. 1. 4 in some moving picture. But with mod- The wood base for the jig may be 2 barn : Hol] ern engineering and the construction of door, loading platform or pone rame ISOU Eea MIS) dams and extensive irrigation systems, made of scrap lumber. Tack the paper f y Š layout to the wood base and drive 6D tt at there has come to even the desert dwel y a hait neh At 4h t X n H2 ler the opportunity to do a little boating nails to a pepi of one-half inch at the HA AHHH eH 6 on his own, Naturally we don’t feel like points marked. | HEHH REH Aa putting out any considerable amount of When the hoops have soaked for at 4 rH ‘| k Hio labor or money on factory-built boats least five hours, bend them into the jigs. H H BPH Hiz but we would like to have a light, ser- Three hoops are placed in form A, two bt ae t tH ta viceable craft of some kind to take with in form B, two in form C, and one in Ji Boe Pepe ets us on jaunts and picnics to the distant form D. Two hoops remains these are 7 Sena EEEE E EEE rre river, canal or reservoir. The duck sea- cut at the middle to make four pieces HBBUPOREAT ODES ED son will be around again soon and those half length, which are bent all together LAYOUT FOR RIS JIBS _FIG=3. otherwise inaccessible hideouts can be into the bow-piece jig. When placing the BALING WIRE: f THIS POINT IS_4-98 reached if we have our portable, light hoops in the jig, alternate the thin and f FROM THE MIDDLE, draft boat along. Thirty hours spare time thick sides. This will allow more space 6"ARCH E a and at most $10.50 in cash will provide and facilitate placing. The jig should 5 4 J 20% z the missing canoe, for which the mate- be placed in the sun to dry for six hours. S J SUNNAT ES rials listed at the end of this article must Bending the Gunwales Š v sr Salers OE ET Next bend the ends of the gunwales. EG-4 2 i f For typographical reasons we cannot If one end is being done at a time, this S i run this list here, so turn to the end of may be done while the other end is soak- METHOD OF = = the article now if you want to learn the ing. Bind both gunwales together with | GUNWACE ENDS em Se cost and function of the parts. ' wire and bend by the method illustrated 3 WHITE PINE 3°x 5° The prices listed are the retail market in Fig. 2, the center of the curve being LE prices for new, finished material. The 4 feet, nine inches from the middle of cost of the canoe can be reduced, in most the gunwale. To hasten the drying, a cases, one-half to two-thirds by the saw- tub was inverted over a gas stove with ing of the different wood strips from one burner lighted and the bent portion %-in. white pine planks or other smooth- of the gunwales thrust up under the tub grained wood, by the use of discarded well away from above the flame to avoid lattice or trellis work and the use of an burning the wood as it dried. Doing one old tent, porch curtain or tarpaulin. A end at a time does not make fast drying

similar canoe nine feet in length was advantageous on the first end as it will built previously at a cash outlay of fifteen dry while the other end is soaking suffi- S cents (for tacks) by using the ciently for bending. The same wire makeshifts listed and asphalt roof- and form may be removed from the ing paint gleaned from forages finished end and used again. To de- into the Jeft-overs of several new termine whether the wood is dry houses. The cash outlay on the enough to hold its shape, loosen the canoe shown in the accompanying wire at one end. If no appreciable photographs was cut from $10.50 loss of curve is noticed, it is safe to

to #560 by using a fieatded tar remove ie wires. ae damp climates paulin, nails, wire and one quar the gunwales should be placed into k : of paint on hand. their positions in the canoe without Ht Pen LAL Place the barrel hoops and gun- allowing them to lie around loose Construction details show simplicity of method of building. wale pieces in water to soak. The Modern Mechanix and Inventions for August 93

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Units of house are transported on trailer to camp site. 2x4’s underneath and of top are joined by iron rods to clamp the units into an easily shipped bundle. 410" >} EXTENSIONS OF BOARDS Assemble elements of floor and side as shown then cut down middle to form two hinged halves. Lag screws in side are set in % in. hoies in floor to hold house in place. HIS sturdy cabin has been designed for the fellow who wants to go somewhere and take a good shack along with him. It has the advantage that it can be slung on a trailer and taken wherever you can drive your car. Once on the camp site, whether for 24 hours or a month, you flip the sections together and there before you stands a cabin you'll be proud of. Beating rains can’t bother; the floor won't sag, and with windows on each side you can regulate the ventilation to suit. The floor space is ample for 2 double beds, chairs, a small table—even a topsy stove 98 8°g" ——____________y for chilly weather. Let’s look into the busi- ness of building it. Briefly, this cabin is divided into 6 units —the roof, the two sides, the two ends and the floor. The floor, roof and ends are divided and hinged along the middle so that they may be folded to half their open area. A unique detail of locking the corners is by means of hinges screwed to the adjoin- ing surfaces. To take the cabin apart, the center hinge Modern Mechanix and Knock-down (Cabin to Camp pins are removed, thus making this step simple and effective. Pins made from lag screws with the heads sawed off after be- ing placed, extend an inch below certain studding and the corner posts. These pro- truding pins fit into holes in the floor, locking the floor and side walls. To insure a tight fit at the ridge of the roof, a strip of canvas is nailed down under the hinges and over the roofing (if roofing is used) and this coated with hot asphalt. You’ll find it advisable when making the fl-or to lay out your materials, then nail them together. When this is done, cut the piece down the center and apply the hinges as illustrated in an accompanying drawing. Each side is alike. For one, lay the 2 by 4 in. pieces which are 5 feet, 5 inches long on a smooth surface and after spacing them, nail on the drop siding. Note that the siding extends 1 inch past each corner post. These posts are 4 by 4 fir planed down to 3 inches square for less weight. The most practical way to install the win- dows is to hinge each sash as shown, cut- ting the opening through the side 1 inch smaller on each side than the sash. To make each sash fit quite snugly, cut and tack rubber strips (cut from an inner tube) around the four sides of the openings so that when the sash is closed, its four sides will press against the rubber. (Continued on page 134) HINGE, x OF WALL | Plans for top and sides. Roof has notches in rafters to join with studding in the sides. Join hinges with pin to hold sides. Inventions for August 99

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Midgy Jr.—Complete Vacation ELL, radio fans, here’s the latest in receivers. Here is a job that weighs less than four pounds including batteries. Lug it around like a camera or carry it in your brief-case, overnight bag, car pocket or even in a large over- coat pocket. It’s all the same to Midgy Jr. For local reception the only ac- cessory is a pair of headphones. For DX work you will, of course, need a coil of flexible wire for an antenna and a second short piece for a ground connection. So there you are. First clean off all tax tags, etc. from a cigar box and sandpaper the wood where necessary. Stand the box on end so the hinges are at the right. Across the box, 2% inches down from the inside of the top, glue in a horizontal partition as shown for the A and B batteries. The lower section is for the receiver parts in the circuit, which are arranged as shown in the photo and drawing. The parts can be wired with small flexible wire such as No. 22 or No. 24 cov- ered with spaghetti to insure against shorts. Solder all joints where necessary and make sure of all bolted connections. Winding the coils is a simple matter pro- vided the accompanying winding diagram is carefully followed. Use No. 24 DCC wire, winding on tube bases and using the large and small prongs exactly as shown. The Š large prongs are for the tickler coil connec- Sompletedreceiven tions and the small prongs for the grid coil. be carried like an Solder the ends to windings into the ordinary camera. prongs and flood the turns with Duco canoin boa, or cement. The number of turns shown will in auto, a small suit the various bands although it may be gitenna should necessary to add or subtract one or two bring in clear, turns from the grid coils to suit just the loud signals on points in the bands you may wish to reach. headphones. This is a matter of cut and try. On the inside of the cover fit in a piece of copper window screen wire for an an- tenna for local use. Connect this with a ANTENNA SCREEN ON “cover 230 @—TICKLER COIL DETECTOR 7-9 MEGOHM GRID LEAK a 0001 FIXED CONDENSER MIDGET BOOK PHONE —> TYPE BALANCING TIP JACKS CONDENSER n .000050 VAR, MIDGET COND. Wire up with this simple re- generative cir- ‘cuit. Tickler and grid coils are wound on old tube base as illustrated on opposite page. Tune with midget condenser and, 50,- 000 ohm resistor- Bt GROUND AND SHIELD 22hy. 100 Modern Mechanix and ‘Receiver in a CIGAR BOX short piece of flexible wire to the antenna post on the outside of the box through a small hole for the same. Then shellac the outside of the back, where the tuning condenser and variable resistor shafts come through and press on a sheet of heavy tinfoil to cover the entire surface. Plenty of shellac will make the foil adhere nicely. Cut around every bolt and screwhead and projecting part so the foil will touch no metal part of the circuit. Then connect one corner of the foil to the ground post. This shielding is necessary to kill hand capacity that would otherwise make tuning very difficult. Put the two A battery cells (flashlight) in the case at the right and the 22%4-volt B battery at the left. A suitable hold down can be made by jamming a slender stick of wood across the whole battery assembly between the sides. Then connect the A and B wires to the batteries, put in the phones and you are ready to go. As before stated, if there are no local stations, antenna and ground wires will be needed. For real portability, it is possible io coil up some lengths of fine, flexible wire with clips on one end of each and tuck Arrange parts copper these inside the cover of the receiver. The as illustrated SCREEN WIRE aei extra tuning coils can be carried in the in this photo. space above the tubes. (Continued on page 134) 000050 ri wire Tips g TicKEER TOGETHER? CONNECTING IN ala TWO OR MORE FILA i i PAIRS OF PRONG | PHONES PRONG 8 OHM FILAMENT cho bare ® paver PRONG PRONG i BAND | WIRE | GRID [TICKLE (Í THESE WAVE LENGTHS METERS |NO24 DCC] TURNS | TURNS JARE ONLY APPROXIMATE 300-500 " 145 A ÍAS CONDITION OF PARTS 200-300, 4 90 35 AND ASSEMBLY WiL 125-190 " 42 18 GOVERN USE OF COLS— 65-85 o 20 to [TRY ONE AND SEE WHAT 35-45 j 9 $ IT WILL DO-THEN AN) [DIFFERENCES CAN BE 16-25 n 5 6 USTED IN WINDING OTHERS cho GR Diagram at right shows how parts are wired up in the cigar box. Copper screen antenna for local reception is secured to inside of lid, and connected to the antenna post. Inventions for August l 101

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This is the Campbell C-8 racer described below. Att the important features of design of the Don Campbell C-8 dirt track racing car, which gave a good account of itself on the dirt tracks during the last racing sea- son, are illustrated in these drawings and photos. It will be noted that a standard tread of 56 inches is used, also that the wheelbase of the racer is 91 inches. In some instances the wheelbase is cut down to as lov, as 84 inches and in other cases it runs as high as 100 inches, for dirt track work. Note that the frame used under this racer is constructed from Model T Ford side members and cross members. Two front “PLANS for for Dirt Track Competition end cross members are mounted, one of them being designed to carry the front spring Z-bracket and the other designed as an engine mount; the engine mount being 6 inches back of the front spring mount. The side members are cut off at the rear end and fitted to the conyentional Model T rear cross member, which is used to mount the rear spring. The projecting ends of the a “RACER by RAY F. KUNS rear cross bracket are cut off. Special spring brackets are used which give an underslinging effect for the rear. The original width of the frame, that is, 23 inches, has been held to. The weight of one of these dirt track racers should not exceed 1500 lbs., the Right front wheel has no caster, left wheel having five degrees caster, for turning at speed. SHOWN BELOW ARE THE COMPLETE FRAME o i aei AND BRACE PROFILES FOR THE VARIOUS STATIONS ne shown being approximately 1400 pounds. Owing to the fact that these cars AZ" BRACKE" MODEL "T" FORD SPRING 104 Modern Mechanix and r l N are used on half-mile dirt tracks, it is neces- e mye thought to their performance pa a pr on 1S o i S Zeon sus ae Fi Rp aE ve type of track. While the car must ALL OTRAS ARE valet ow, it must not be too low or you will ea EN Sar HE have what is known as a “floater.” A floater \ GAS TANK. is a car which tends to slip away from \ [TOTAL HEIGHTS. INCLUDE —~ BODY SILLS Į Ct RADIATOR: SHELL STRAINER TY Sie FILLER NECK. REAR HEAVY n. : X> TIRES ARE DIAMOND. renee SX 7X550 a40" MEPRONT OE FOR CLAMPING ~~ Basre \ Se i DOWN HOOD = BarcLe dI qy y LZ 4 La Zi - GAS TANK J oe dL = i P a RND TARE NI 4 A me RIVET TO BODY 3 “S\N BUILDING THIS ` \. PORTION OF BODY \, CONSTRUCT WITH N \ PAPER PATTERNS FIRST. 12e BRACKET TO CARRY (ALSO BUILD IN R FRONT. SECTIONS SPRING FRONT SPRING BUILT UP OF MODEL "T" FORD FRONT SPRING Inventions for August 105

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Details of Chassis Reinforcement, Spring Suspension Told by Drawings ast: FROM SILL TO F = EDGE OF FRAME i BODY SILLS we } MODEL "T" FRAME § STEEL PLATE SIDES ADD TO STIFFEN FRAME ROLLED EDGES under you on ‘the turns, much after the fashion of a stone skipped over the water. Too much weight on the front end of a racer used on dirt tracks is likely to cause the car to be carried out of its course, owing to improper distribution of load. On the other hand, the engine can be set back too far. Six inches is recommend- ed in this design to give proper balance. This car performs very well on the curves of the dirt tracks, showing that balance or 20 GA. METAL, MODEL "T" MODEL "T" CROSS MEMBER ENGINE OUTSIDE LINE OF FRAME I "ROSS" TYPE STEERING GEAR STEERING \ COLUMN MOUNT FOR SPRING BRACKET MOUNT EEN A f KA ‘ f = K 1 k | re oe ARM ee T Ei MOUNTING A "y BOLTS ELN 1B x5" x5 STEEL PLATE OF ' z DLE ARM | SIDE VIEW OF s BUSHING! Z" BRACKET, 6 IN ASSEMBLY SHOWN z e FRONT AXLE — OVERLAND- 1925 SPRING — MODEL "T" RE-BUILT SPRING PERCHS— MODEL "A" SPINDEE BODIES — DODGE -1925 KING PINS — DODGE-1923 FRONT HUBS AND BEAR- INGS ARE DODGE-1925 g fe, BRACKET i, ADJUSTMENT //A "i NUT E MODEL"T" FORD || DETAL oF /ZZ FRAME CONVERSION| PIEMAN ARM Ze eer CONSTRUCTION AND CHASSIS DETAILS HOOD- ONE PIECE f COMPLETE BODY ao Z" BRACKET RFR REAR VIEW OF SPRING AND AXLE WHEEL SPINDLE GEARI HOUSING PITMAN ARM, TIE ROD= DODGE 1925 DRAG LINK DRAG LINK SO RADIUS, ROD RSS MODEL "ee N TIE ROD) a é SPINDLE ARM aoe" R Ne lE FRONT AXLE ¥ ia age CASTER 5° ‘SPINDLE BOD’ TOE-IN_ 0° TAPE EAER monr DEL g MBER LEFT WHI Z STANDARD DODGE -1925 . p 9, LEAVES SHOWN, RE-BUILT MODEL °T" FORD The tie-rod and radius rod hook-ups are shown in the photo immediately above. Front spring suspension, spindle arm details, and method of stiffening frame are shown im the drawings. Note the taped front spring, which is rebuilt. 106 Modern Mechanix and Mounting of Radius Rods, Brake Cables Done With Eye to Accessibility distribution of weight is about right. It has a record of 24.2 seconds for the Cin- cinnati-Hamilton_ half-mile track and 23.4 seconds for the Winchester, Indiana track. The ability to get around the track in rec- ord-making time is a question of car bal- ance. No matter how skilled the driver, the car must “handle.” The chassis of the C-8 will take any of the lighter four-cylin- der engines; in fact, has had several differ- ent engines in it. The front axle beam is a 1925 Overland | FILLER CAP) IGAS TANK. LEATHER. UPHOLSTERING E= STEERING WHEEL WAY HOUSING] HA T BRAKE DRUM g BRAKE CABLE, BODY FRAMING RADIUS ROD MODEL “At RE-GUILT) BRAKE STOP PIN Immediately above is shown the disposition of the gas tank, seat and brake lever cross arm. To the right is shown rebuilt “T” Ford rear spring, new perch and drum disc. SOME MAJOR DETAILS OF CONSTRUCTION IN CENTRAL PORTION OF BODY ARE SHOWN IN THIS PHOTO Bea The steering wheel is set just off the center line, as shown above and in the top right drawing, opposite page. The placing of Pitman rod and body frames is also shown here. Inventions for August Baie “Ut BRACKET a The brakes are external con- tracting type. This shows the cable to toggle, also upset spring and shock absorber. Note new perch for radius rod. SIX LEAVES REAR SPRING serne ce f PENE ETR ADJUST MODEL T" FORD PLATE RE-BUILT — —. > REAR-RADIUS ROD = A E 3 x2" STEEL STRAP DETAIL REAR‘ SPRI TELESCOPED AND WELDED AS SHOWN mair ag" REAR RADIUS ROD DETAIL FRAME: r —_——-2i" ae Wf YW h LATE a: FRONT RADIUS 24l N ROD DETAIL ~S MAKE RODS FROM MODEL "A" FORD RADIUS RODS _ — Immediately above are shown the dimensions of the front and rear radius rod installations. These are all made from Ford model “A” radius rods. four. It will be remembered this axle made use of spring perches similar to the Model T and A Fords. Perches used in this case are Model A Ford. The spring itself is a Model T Ford, flattened out. It is necessary 107

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SHOW to BUILD a Simple Here’s an old schoolroom favorite—the cooler you used to see in physics class has been put to a practical experimental use by Mr. Cartright who shows how to build one of these simple affairs. CE boxes cool food because ice absorbs heat. As the ice melts, heat is required to raise its temperature to 32° F., the melting point. If we build a box ‘and insulate it from the heat of outside air currents, place ice in the box, and then place food in along with it to furnish heat to melt the ice, a balance is soon struck between the meltin point of ice, which is always 32° F. an the temperature in the rest of the box. Gen- erally this is around 50° F. We make pro- vision to drain off the water from the ice tray, and presto, we have an ice box. uaa) Ps CONTROL, CUT TOP OF _ CAN (eaa 4 eNom) a WELDED TO BOTH CONTAINERS TRAYS CONTAINING SALT AND AMMONIUM ar. TRAYS BUILT UP OF WOOD A couple of cans, some trays impregnated with paraffin, and a supply of common salt mixed with ammonium nitrate constitute a fine ice box cooler for the summer camp, 112 Usually we think of the function of the ice box in reverse order. We. think that we put food in to cool. But this is not so: there are several variations of the idea, looking at it from the standpoint of pure schoolroom physics. For instance, there are machines which will cool an ice box quite as effectively as ice itself. They work in somewhat the same fashion as ice. All of them are devices which allow gases to expand in “cooling coils,” This expansion in the coils is accompanied by a. much lowered temperature in the gas. Con- sequently the gas tends to soak up heat from the surrounding air, which in turn soaks up heat from the food in the box. As the gas travels through the coils it becomes warmed by the heat it has picked up, and it is car- ried (in mechanical types of refrigerators) to a compressor which squeezes the gas down again in volume. This also com- presses the heat to a small space, and the gas is run through a cooling coil outside the refrigerator through which a blast of air is run by a fan to get rid of the heat. Then the gas is passed to a reservoir waiting to be admitted to the expansion coil again. It is on the above principle that Frigid- aire, G-E, and other mechanical refrigera- tors work. Principles of Refrigeration Chemical, gas, or absorption machines as they are called, do the compressing chemi- cally, or by absorption of the gas into char- coal or other absorbent. While they need no pumps, there is a difference in pressures in the gases in the refrigerating system, and all such types must be of the sealed variety. That is, the refrigerating gas is sealed her- metically with the exclusion of air in a closed system of circulating pipes. Both ice itself and these mechanical re- frigerating machines operate on the same principle in an ice box. They soak up heat from the surrounding air and food. If we place food near them in a circulating space closed to outside air such as an ice box, we get an inverse result which is commonly thought of as the cooling of food. What really happens is the heating of the ice or the coil—a transfer which leaves the food in a Jowered temperature. There is still a third way for obtaining lowered temperature within an ice box that is ideally suited to the needs of the camper, the motorist or the summer re- sorter who is out of touch with the supply of ice. This method is known as evaporative re- frigeration, and I am going to tell you how Modern Mechanix and Chemical REFRIGERATOR by JOHN CARTRIGHT to build a refrigerating unit that needs no motors, needs no heating of a ball in a kero- sene flame, and which needs no little gas pilot light to make it work. Itis a refriger- ator built on the old schoolroom chestnut— “heat of solution.” You know what happens when you put alcohol on your hand? Dries up right away, doesn’t it? Feels cool too, eh? Or ether, which is even colder. Maybe you have seen canvas water bottles which cooled water because enough leaked through the bottle to keep the outside moist, and when the water evaporated it soaked up enough heat to leave the contents of the bottle cool. Cooling by Evaporation Now suppose we could make a unit that would take water drop by drop, absorb it, slightly change its chemical nature, and then evaporate it as though it were ether. We could have intense cold before very long, eh? Here’s just such a rig. It might cost you all of two bucks to build, too! Every high school chemistry student knows that water dripping on ammonium nitrate will cause the nitrate to go into solu- tion, and the resulting solution has a very low temperature and evaporates very rap- idly. This chemical ammonium nitrate is cheap too—it is merely good old fashioned farm fertilizer. Perhaps you’ve seen piles of it along the road in the fall or spring when farmers are spreading it out on impoverished fields. (Rain soaks through it and carries the nitrogen into the ground. Nitrogen is plant food.) _Now if we take trays of ammo- nium nitrate, and fix it so that we can pass water through it at a rate just fast enough to allow it to make a normal solution of am- °° monium nitrate, which will | OF UNIT, =f EN g DRIP COCK ‘l ROOF TO THE or SCHEMATIC VIEW LOADED TRAYS tz $ FUNNEL ai Ee m BLOTTING OR 4 ASBESTOS immediately become cold, and then put in something which will keep the nitrate from crystallizing as it evaporates, we can put these trays in a metal box, arrange a drain, and have something nearly as good as a (Continued on page 129) BRACKET IS 5] WELDED To BOTH CONTAINERS oo 16 GA. SHEET a FUNNEL 1 1 ALMMONIUM NITRATE TYPICAL, TRAY DETAIL CUT TOP OFF. VARNISH CAN The drain must be used to pipe off the solution which results when the water drips onto the ammonium nitrate. A drip cock trickling water on a tin roof evenly distributes the water through the top tray, whence it filters to the others. Inventions for August 113

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Building aSOELESCOPE for by E. WILLARD. PENNINGTON In this article Mr. Pennington shows how to polish and mount the mirror for which grinding directions were given last issue. Also the simple Foucault test is thoroughly ex- plained so you can have a mirror as accurate as the finest. E ARE describing the construction of reflecting telescopes, with particular emphasis on a 6” telescope which one can build himself. In the last issue we described the optical system, showed a frame, de- scribed the grinding of the lens up to the point of getting all the ma- terials and setting up for work. With a full understanding of the grinding functions, the actual grinding may now be commenced. The surface of the tool is wetted, sprinkled with a little of the coarsest carborundum, the mirror placed in position and the “grind- ing machinery” set in opera- tion. You can soon tell by the sound and feel of the grinding when the car- borundum has ceased to cut, and when this stage is reached the charge of carborundum is replenished. We are work- ing toward a Mirror x Rubber $ Kneeling Pad TRNA Concrete Sectional Yew Base MIRROR MOUNTING DETAIL Either a wood frame or a metal pipe frame (as shown last issue) spherical reflector having a focal length of 50 inches and such a reflector has a spheri- cal radius or center of curvature of 100 inches so in order to check the progress of the rough grinding it is necessary to pro- vide a thin metal template a little longer than the diameter of the mirror and having one edge cut accurately along an arc of 100 3 Angle Mirrar Square oa Eye Piece And Brachet +, Moarutying Lert q Focus Side View DETAILS OF EYE PECE Section The Eye Piece Here's a simple brass frame for the 1” focal length eye-piece which catches the image reflected in mirror. inches radius. This template should be cut as accurately as possible, so in lay- ing out its curve use a wood batten or joined laths for making the arc, rather than a string or cord as the latter would have too much stretch for exact work- manship. If the mirror tends to stick during the grinding process stop in- stantly and add water. When the ap- plication of the template to the washed surface of the mirror indicates that the right degree of curvature has been at- tained you are ready to proceed with the fine grinding. In preparation for this all traces of the previous coarser grade of abrasive must be removed from the work- ing surfaces, surroundings, clothes, hands and fingernails! At this stage as well as throughout all operations of fashioning the mir- ror the utmost need for scrupu- “STAR GAZING”- Par 1 next finest grade of carborundum, i.e., the No. 120. In mirror grinding, the grinding down to exhaustion of an application of carborundum and water is called a “wet.” Proceed, with as many “wets” of the No. 120 carborundum as are necessary to ob- literate the marks of the coarser No. 80 grade and then test again with the tem- plate. Continue with the No. 120 until good coincidence with the template is attained, as the succeedingly finer grades h not appreciably change the curva- ure. rough template. Wash the mirror and the tool thoroughly and dry them. Testing for Accuracy Across the concave surface of the mirror draw two or three pencil-line diameters. Lay the mirror back down on the tool and If your curved mirror surface is a bit too deep it can be made shallower by shortening the stroke; if it has not as great curvature as the template the cen- ter of curvature may be shortened by lengthening the stroke. When the proper curvature has been reached, “clean house” most thoroughly again and proceed with the successive stages of fine-and finer grind- ings. Each successive stage of fine grinding should involve A about a half-doz- Ee en “wets” of 5 or é Here is shown the method of ‘using the simple Foucault apparatus for determining the spherical aberrations of the mirror. All that is needed in the way of materials are a light, a can, a piece of tinfoil and an old razor blade, This will give very accurate results. Knife Edge OPTICAL SET Uo OF APPARATUS FOR FAUCAULT TEST Above is shown the diagram of the Foucault test. If the mirror is truly spherical the pin point of light emanating from the tinfoil will appear to the eye as a bright flat surface throughout the face of the mirror. revolve it around its own axis. If the true spherical relationship has been maintained the pencil lines will rub out equally and simultaneously; if not, the higher or lower | areas on the mirror’s surface may be equal- ized by changing the stroke as previously outlined. Upon the successful completion of the grinding stages the mirror is now ready for polishing. Polishing “Clean house” thoroughly again as before —more thoroughly if possible. It is a good 6 minutes’ du- ration each; until when the No. 6F Turkish em- ery stage has been passed it should be pos- - sible to read fairly fine’ type through the glass. Dur- can be used to hold the mirror and the eye-piece of the simple reflecting type telescope. Above is shown the method of mounting the mirror on a rubber sponge. lous cleanliness can not be over- emphasized. The next grinding operation is performed with the 116 Modern Mechanix and ing the fine grinding stages it is necessary to employ a more accurate means of testing for cur- vature than is afforded by the relatively Inventions for August precautionary measure to remove all sub- sequent polishing operations to another part of the shop to avoid any possible con- (Continued on page 24) 117

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“How to Build “Old Man EMEMBER the time you were out in.a boat in the moonlight, and the moon- path shone on the water, and peace and tranquillity were everywhere? In times like these it is good to realize that the woes of the world are man made; there is nothing wrong with Mother Nature. She makes the bees to buzz, and the corn to grow, the water to surge and the rivers to flow; let’s get away from it all and enjoy ourselves in spite of the Depression! Let’s take that trailer house we built from plans OPEN. a A DECK NO RAIL HERE Z FOR_PURPOSE BOARDING TRAILER HOUSE FLOOR SCREENED = DECK 4X4" STANCHIONS. aa y -POSTS S COMPLETE PLAN ÖF HOUSE BOAT 1 2°xI2" Y. PINE. axa BX4FIRT.AG CATWALK CORNER FLOORING PLANK POST DECKING OF 2'x8" TRG, Y. PINE: 2o BOTTOM END PIECE PLANKING 2x8" X PINE CONSTRUCTION VIEW T&G. SIDE OF HULL. PLANKING in M-M a couple of months ago, and put a hull around her so she’ll float and then we can while away our time on some southern bayou, or lazily float down the Mississippi or Ohio or Monongahela or Hud- son or whatever stream happens to be nearest your home. Let’s go! Here’s how: The house is the same house as was fully and completely dimensioned and detailed in M-M for May. I have not shown this in repetition, for the only changes are the matter of extending the roof (now called a deck, since we're going nautical) some six and a half feet on one end, and about five feet on the other. Under these slightly changed details we put a scow hull, which for all its simplicity has been carefully planned and is the result of experience I have gained with three other similar hulls. =e_—_—— UIUIUOUN ROOF. 4 PROJECTION E a Th Š minnow SCREEN MOULDIN x AROUND F SIDES, 2"Xia" CATWALK FP exer, The size of the hull is 22 ft. long by & ft. 2 ins. beam, by 24 ins. deep, It will draw about five inches of water. The details of hull construction as explained in the text apply to the middie and half section views. Note the layout is the same as the M-M Cabinette Trailer. The cabin is the same as the one described in the trailer plans which ran in May issue. 120 Modern Mechanix and “River” a Scow “Houseboat by JARVIS Under the ends of the roof—pardon me, I should say deck, we put good old 4x4” fir pilaster (now called stanchions) and there is our houseboat! One end of the boat can be screened, and the other can have a canvas bulwark thrown about the rail on three sides to keep the fish from jumping x on deck when you keep your can of bait outside, and the other side, say the port x side, can be left open so you can board your yacht from a small row boat. The arrangement plan is the same as that worked out for the trailer, and I wouldn’t change it a hair. The doors slide to save space, and the L. STUMPF kitchen sink; lavatory, stove and toilet have all been placed with an eye to trimming the ship properly. If you go shifting the weights around you will have a boat that will sit (Continued on page 128) STERN DECK UNSCREENED. HOUSE BODY" ROM, M.M. 4 WHEEL AILER TRAILING I HOUSE |S SUNK INTO HULL ee COMPLETE HOUSE ~~ ——ASSEMBI CANVAS COVERED ~ CAID IN PAINT ara STANCHION $ a POSTS . SCREENED PORCH EXTEND TO SUIT HULL OUTLINE bX 4" BEADED LY CEDAR STAVING 4" EXTEND ‘The thumb nail sketches show how attractive the interior can be made. The catwalk space of 12 ins. around the cabin is necessary for handling the boat. Elevation and isometric details show the plan of the outboard profile and how the roof of the trailer cabin is extended in the ends to make service and screened porches. Inventions for August 121

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