Modern Mechanix, May 1933

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'Topay we are going through a period of revolutionary change. The science. of chem- istry has played an impor- tant part in our present prog- ress; it will play an even more important part in the progress to come. This profession is teeming with opportunities. Some of these opportunities will be realized by the scientist in his completely equipped laboratory. Others will be realized by men endowed with a knowledge of chemistry, inspired by an insatiable desire for greater knowledge, working in their own iaboratories. In your own spare moments, you can prepare yourself for a career in chemistry. The courses offered by the Interna- tional Correspondence Schools are thorough and modern, yet simple, clear and easy to understand. Thousands of men have studied them and started on roads to success, Stop and think, this coupon may be the means of changing your whole life! Mark it, mail it for information on chemistry, or any other subject in which you may be interested. “INTERNATIONAL CORRESPONDENCE. SCHOOLS a

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D Architect D] Telegraph Engineer D Plumbing O Steam Fitting [] Air Brakes [O Train Operation D Architectural Draftsman O Telephone Work O Heating O Ventilation O Highway Engineering T O Building Estimating O Mechanical Engineer L] Sheet Metal Worker DL] Chemistry “0 Phatmacy D Wood Millworking O Mechanical Draftsman L] Steam Engineer < O Coal Mining Engineer O Contractor and Builder O Machinist O Toolmaker O Steam Electric Engineer O Navigation D Structural Draftsman O Patternmaker D] Civil Engineer O Boilermaker O Structural Engineer O Pipefitter D Tinsmith O Surveying and Mapping L] Textile Overseer or Supt; O Electric Wiring O Bridge Engineer O Refrigeration O Cotton Manufacturing D Electrical Engineer L] Bridge and Building Foreman [O R. R. Locomotives O Woolen Manufacturing D Electric Lighting - O Gas Engines [] Diesel Engines [] R. R. Section Foreman D Agriculture O Fruit. Growing D Welding, Electric and Gas O Aviation Engines O R. R. Bridge and Building O Poultry Farming U Radio D Reading Shop Blueprinta O Automobile Mechanic Foreman L] Marine Engineer BUSINESS TRAINING COURSES j C] Business Management E] Cost Accountant DO Business Correspondence O Railway Mail Clerk O Office Management OC. P. Accountant D Lettering Show Cards (Signs [O Grade School Subjects O Industrial Management O Bookkeeping -D Stenography and Typing O High School Subjects O Personnel Management O Secretarial Work O Complete Commercial O College Preparatory D Trafic Management L] Spanish E] French D) Civil Service O Illustrating O Cartooning

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9 ee. Thank You for Mentioning Modern Mechanix and Inventions for May When Writing to Advertisers 3

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MAY, 1933 Se VOLUME X NUMBER 1 Donald G. Cooley EDITOR Er PRICE 15 CENTS (20 CENTS IN CANADA) CONTENTS FOR MAY SPECIAL FEATURES Spot News of the Month - - . - Jap Pilots Ride to Death on Flying Bombs By Ray Holt Pulling Power From the Skies- - When You’ve Found Gold—Sluice ’er Out - - 3 č By Arthur H. Carhart Complete Coal Mine in Museum Room Getting Personal With World’s Biggest Bears - - - - By James Nevin Miller Freakish Dramas of Ocean Bottom - By C. Moran At Last a Convertible Airplane-Auto By Theodore Hodgdon Fighting Chinese Pirates With U. S. Marines - - - zv et 2 By John Clovelly New Thrills From Freak Spills of Auto Ball - By Ed Harlan Gibson 1000 Ways to Make a Living - - - Plants Grow “Blood” for Human Health Sea Courts Explain Accidents With Models = eee SHORTER FEATURES Electric Shovel Is Mechanical Monster - Everest Plane Has Unusual Equipment Movies “Submerge” Fake Seadrome - New Devices Make Housekeeping Easier a 36 38 A2 48 66 70 74 76 80 86 46 ol 52 56 4 SHORTER FEATURES Oddities of Science T Disc-shaped Rafe Has Air- ship Ancestry - - - Six Hours to Europe in Stratosphere Liner - - Escape Conduit Rescues Trapped Miners - c; Fortunes Waiting fór Inven- tors " = a w - Probing Magnetic Secrets of Your Watch - ee Dream House for Techno- cratic Age - - - Hobby Department LONGER HOW-TO-BUILD ITEMS Building the Cabinette Cruise Trailer - =- =- = 98 By Jim Allenby Wooden Water Wheel for Farm Stream - - = - 106 By John C. Carpenter Tabor Saving Photo Developer - - . By Robert C. Quigley Plans for Scram—Part II - 116 By Weston Farmer Talk With Continent on 20 Meter Radio - + 124 Midget Vacuum Sweeper Cleans Table - 5. e 127 INTERESTING SCIEN- TIFIC ITEMS Latest in high speed photography - + 5 44 Machine Gunners Practice on Model Plane - - - 44 . (Continued on page 6) - 112 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 3rd, 1879. Jack Smalley, Managing Editor. Copyright 1933. Advertis!ng Offices: Chicago office, 35 East Wacker Drive (Phone State 2955) ; New York office, 52 Vanderbilt Ave., Room 1603 (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 retupned unless accompanied by relurn 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. S. A. |

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Are You Working Part Time? -or at a Reduced Salary? A you tired of taking wage cuts— sick ot 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 situ- ation that is facing you today. If you take ad- vantage 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—then you are in danger of losing even what you have left. 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 pros- perity 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 re- quire every drop of fighting blood—to win back those salary cuts and a bigger, better job! 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 1908-1933 LaSalle Extension University raises. Don't take our word for it—read some of their most recent letters in our new booklet, *100 Pay Raises Today." = They havent all been luckier than you—they haven't all 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 business 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 before—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 knowl- edge that may banish your business worries for- ever. Simply mark and mail the coupon below. 25 years of service to over 800,000 members LA SALLE EXTENSION UNIVERSITY, Dept. 5493-R I'd like to see that booklet, "100 Pay Raises," and have the facts about your training plan that you think will help me to larger success in the business field I have checked below. O Higher Accountancy (] Business Management O Modern Salesmanship O Law O Traffic Management L1 Office Management [] C. P. A. Coaching | O Railway Station Management O Commercial Spanish (1 Stenotypy OD Effective Speaking O Business Law QO Industrial Management O Foremans'! O Personnel p anagement DL] Business Correspondence OD Business Englis! O Credit and Collection Correspondence Chicago Thank You for Mentioning Modern Mechanix and Inventions for May When Writing to Advertisers 5

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TABLE OF CONTENTS — Continued From Page 4 INTERESTING SCIENTIFIC ITEMS FOR RADIO FANS ; ; ; Gs. e e Sparks From the Radio Editor - - - - 123 p File ot um auc MEE A dc Boosting Volume of T. R, F. Receivers - - 123 Planet Model Is Mechanical Marvel - = 47 Arbor for eund Fine wire 1 RM Y e 15: Oxygen Chamber Transported by Plane - 69 Ma ing 85 Millihenry ORE NOM Nr ums (UR 124 Hospital Model Wins Gold Medal - - - 69 Building a 20 Meter Transmitter - =- - Tog Compass Cuts Navigation Peril - - - 73 NEWS from SCIENCE LABORATORIES How Modern Prince Tours Desert - - - 82 Diatoms Make Sea a Soup for Fish P edd NEW MECHANICAL INVENTIONS Strange Facts About Explosions - 0. 5 46 New Streets to Stop Trafic Jams - + 2. 47 Handy Lamp Attaches Anywhere - - - 44 Condemn “Frills” in Education =~ 2 + 47 Walk on Water With Novel Buoy - - - 45 Feed Birds From Window Trays - - - 53 Colored Tires Match Your Car - - - + 45 Tire Cement Repairs Screen Holes - - - 65 “Ear Gymnasium” Restores Hearing - + 47 Stars Say This Is Year 1940 - + + + 69 Board Reproduces Football Game - - - 47 Why Flies Prefer White to Black - - - 73 Die Recuts Bruised Threads - - + + 51° Six Reasons Why You Get Sick - - - - 82 Trap Electrocutes Flies - - - - -* 52 Insulated Babies Grow Faster - - - - 84 Radio Machine Hunts Pirate Gald - * -* 53 Explosion of Sun Overdue - - - - - 84 Shades for Auto Lights Cut Glare - - - 53 Credit Insects With Intelligence - = . 85 Meter Analyzes Auto Carburetion - - - 53 Phonograph Warns Miners of Perils - - 89 Shuttered Lamp Shade Adjusts Light eee Home Dispenser for Ginger Ale - . . 56 The Shop Mail Box Will Be Found This Month Handy Electric Lunch Cooker - - - 56 on Page 10 Thumb Switch for Electric Iron - - - - 56 Kitchen Shower Brush Se vies - 0. + 56 HANDIKINKS Jar Opener Fastens to Wa - + 2 + 57 ; Revolving Wall Cabinet Saves Space . . 57 Hgndy Long-range Dipper for Camp - - 90 Radio Looks Like Pair of Books - . . 69 Red Welded to Club Aids Putting - ~- - 90 Face Harness for Milady’s Beauty - - - 69 Amusing Game Improves Golf Stroke - - 90 “Hoot-nanny” Traces Million Designs - - 82 Pencil Keeps Books Open - - - + - 90 Car Wheels Have Separate Motors - - - 82 Lights for Outdoor Games - - - + - 91 Cigarette Factory in Tobacco Can - - - 84 Oiled Broom Sweeps Without Dust - - - 91 A Perfect Secretary—a Machine E g4 Fumigate Crop With Old Auto Tires - - 91 No Noise From Electric Rifle - - - - 84 Lawn Sprinkler From Gas Burner - - 91 Portable Bar for Home Parties - - - ~- 85 Handy Household Knife Sharpener - - - 92 Triple Magnifiers for Jewelers - - - «+ 85 ee ros Em e Oil Paper- - 25 S Di ; ink to Reset Latch Socket - - - - - Electric Light Warns Deaf Typist - 89 Table Salt Prevent Burning of Jam.. | l 92 Fan Purifes Workshop Air - - - - 93 FOR THE HOME CRAFTSMAN Small Bench Vise From Strap Iron - - - 93 Bread Knife Cuts Slices Evenly - 65 Rope Removes Pipe Coupling - - - - 93 Cellophane Tail Light for Hikers - 85 Simple Home-made Micrometer - - - 93 Vibrometer Makes Radio Music Visible 102 Remote Control Toggle Switch - - - - 94 Make Spring Profits on Outdoor Ideas Electric Question Game Educates - Ride in Backyard Steeplechase - - 103 Keep Warm With Stove Made From Drum - 94 104 Old Clock Wheel Makes Paper Perforator - 94 105 Favorite Tune Rouses You in the Morning - 95 Shock Type Screwdriver Loosens Screws - 105 Towing Glider With Your Auto - 0. = 95 Lamp Has Glass Rod Sides - - - 109 Making Titles for Home Movies - - - 95 Converting Boat Motor to Plane Motor - 110 Repairing Broken Hack-saw Blades - - - 95 Refuse Collector for the Yard - " - - 110 Heat Basement Without Fuel Cost - - - 96 It Pays to Know These Stunts -+ - - 111 Door Knob Used as Bit Brace - - - - 96 Machine Rolls Your Smokes - - -114 Extra Blade for Hoe - . - = 5 96 Vacuum Cleaner Motor Powers Shop Drill - 115 Window Lock Made From Checker e. + 696 Sell Refreshments From Folding Playhouse - 121 Flaps for Garage Door - - - 6 = 97 Junked Motor Makes Windmill Water Pump - 128 Eliminating Noises in Auto Badio - = = 97 Hobby Horse Rides With Lifelike Gallop - 129 Flexible Magnetic Fishing Tool - - - - 97 Douglas Rolfe EDITED BY EXPERTS Raymond F. Yates Listed here are the members of the Modern Mechanix Patent Expert Plane Talk Editor Board ed Editors, all qualified by national repute to serve VENTURE " as authorities. They will gladly answer questions from Pilot Gene Shank readers if stamped envelope is sent. Address them in Weston Farmer Famous Aviator, Holder of care of this magazine, 529 S. 7th St., Minneapolis, Minn. Consulting Editor Light Plane Endurance Flight Record A. Neely Hall : J. Russell Dye Author P ‘The Boy Crafta- qguiteed Alballi ‘Associate Editon k Ray F. Kuns Principal, Cincinnati Auto- Roger Fawcett motive Trade School Associate Editor

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RULES FOR CONTESTANTS This contest open only to amateurs, 16 years old or more. Professional commercial artists and Federal students are not eligible. 1. Make drawing of girl 54 or 6 inches wide, on paper 614 inches square. Draw only the girl and not the lettering. 2. Use only pencil or pen. 3. No drawings will be returned. 4, Write your name, address, age and occu- pàtion on back of draw- ing. 5. All drawings must be received in Minneapolis by April 25, 1933. Prizes will be awarded for drawings best in pro- portion and neatness by ederal Schools Faculty. — «v COMPETE FOR AN ART SCHOLARSHIP ! . . . Copy this girl and send us your drawing—perhaps you'll win A COMPLETE FEDERAL COURSE FREE! This contest is for amateurs (16 years of age or more), so if you like to draw do not hesitate to enter. PRIZES Prizes for Five Best Drawings—FIVE COMPLETE ART COURSES FREE, including drawing outfit. (Value of each course $185.00.) FREE! Each contestant whose drawing shows sufficient merit will receive a grading and also expert advice as to his or her chance of success in the art field. The quality of instruction in the Federal Course develops your natural talent to a practical earning ability in the shortest possible time. It has been the start for many Federal Students, both men and girls, who are now commercial artists and illustrators, earning $2,000, $4,000 and $5,000 yearly—some even more. The Federal Schools has won a reputation as the "School! famous for successful students”. Enter this contest ... a splendid chance to test your talent. Read the rules and send your drawing to * FEDERAL SCHOOLS INC. - 594-C FEDERAL SCHOOLS BUILDING on Thank You for Mentioning Modern Mechanix and. Inventions for May When Writing to Advertisers MINNEAPOLIS, MINNESOTA

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Become an Expert Draftsman Good Pay Steady Work Advancement E You high school graduates who haven't been able to go to college— You college students who had to drop out after a year or two— You shop and industrial office workers who are stuck in routine jobs— should look into Drafting and Design, because it offers you congenial work, good pay, and steady advancement. The most thrilling and interesting work in the world is building machines and rail- roads, highways and skyscrapers, autos and 1001 other manufactured products—on paper in the drafting room. How would you like to be & Draftsman for an Architect, Contractor, factory, railroad, etc.? Junior College Training Fits You for Best Positions The worth-while Drafting jobs require training of college standard; but if you can’t afford to spend four years at a resident college, our Junior College home-study course will fit you for the best-paid posi- tions in two years. We cut the time in half by omit- ting advanced theory, research work, and cultural subjects, and concentrating on vocational training in the Drafting branches. Our special texts were prepared by over 200 authorities of national standing, and are used by colleges, U. S. Navy, and Province of Manitoba, Canada, Our School is chartered for educational service—not for profit—like the leading colleges Free Lesson Coupon See how we teach Drafting - American School Dept. D-533, Drexel Ave. at 58th St., Chicago If a knowledge of Drafting will enable me to do work of a technical nature in office surroundings, and bring me into frequent contact with influential men, then you may send me —iree and without obligation—one of your special Drafting texts being used by resident schools. KITE AIRPLANE Loops, Stunts Zooms, Dives MANEUVERING HARNESS Byjerkingon the string at proper intervals this big kite is made to do any stunta good pilet can do. This shows only _ afew, Note the 100-foot tail. Kite comes complete in big box, ready to fly. š ee — This Big Kit Complete AV! 9 f Here's the biggest man's size thrill in kite flying ever to take the air! Open the big box we send you and get the thrill of your life. The airplane kite with roaring motor comes to you ready to fly. String aplenty is included. Box 15 x 23 inches. Ready to Fly with 100-foot Tail! Get the feel of flying a fighting plane! The 100-foot tail holds the secret of this stunter's amazing ability to imitate every airplane maneuver. Directions with each kite. : Send 49e Today? (Stamps or Coin) and by return mail we'll shoot you this unusual kite bargain. AIRPLANE KITE CO. 529 South Seventh Street Minneapolis Minnesota 8 Thank You for Mentioning Modern Mechanix and Inventions for May When Writing to Advertisers

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“Enter the Radio Business? ..» YOURE FOOLISH!” they Shouted —yet in a few months I was earning more than any of them You_ should have seen their faces when I told them that in just a few short months I jumped from $35 to $75 a week. "No more scrimping and saving pen- nies for me!" I said. "I've got a new car, and before long I'll have a home of my own. No more slaving for a boss, either. I'm my own boss since I went into Radio—and the work's like play." Just a short time ago they had laughed at my decision to enter the Radio busi- ness. "You're foolish! You'll lose your shirt,” they roared. “Youre no me- chanic, you don’t even know the differ- ence between a grid and a primary coil.” And now it was my turn to laugh. They were astounded that I made such a success in so short a time. They fired uestions at me from all sides. How id I do it? Where did I learn? What school did I go to? “I didn’t go to any school at all,” I told them. “I learned right in my own home—in my spare time—the quick, easy National Radio Institute way. It was actually fun learning. Everything was right before me— working outfits of parts, and instructions with pictures that showed me exactly how to do every- thing. I could hardly help learning. And best of all, almost from the very first lesson I was able to earn money in my spare-time fixing sets in my neigh- borhood. Before I had been studying three months I more than paid for the price of the course. I'll say that Radio is the di biggest paying business I ever found!” This story is typical of hundreds of National Radio Institute students all over the country. Young men with am- bition and foresight everywhere are getting into Radio now. Wm. Sparti- vent, 93 Broadway, Newark, N. J., lost his job, turned to Radio, and has aver- aged $3,000 a year. B. Morissette, 733 Somerville St., Manchester, H., writes that he still has his regular job but averaged $80 a month in Radio work in spare time. The amazing growth of Radio has opened hundreds of new jobs for trained men. Radio manufacturers employ test- ers, engineers, service men, and buyers for jobs paying up to $6,000 a year. Broadcasting Stations use engineers, operators, station managers and pay up to $5,000 a year. Hundreds of operators enjoy world-wide travel and adventure in the employ of. shipping companies with all expenses paid and a good salary besides. Talking Movies pay as much as $75 to $200 a week to men with Radio training. Radio deal- ers employ trained men to buy, sell, install, and service sets, and pay well for good men. Opportunities for ambitious men in Radio are almost un- limited. An amazing 64-page book called “Rich Rewards in Radio” tells all about the many opportunities you can find in Radio—and this book will be sent to you absolutely free! It will also tell you about the fa- mous National Radio Institute plan that has helped others to earn $50, $60, $75 a week and more; also all about the remark- able lifetime employment service. Name Address Le "(— The National Radio Institute course is thorough. You learn by actual prac- tice with working outfits, not just by theory alone. First, you are told how to do it, then you see how by photo- graphs, and then you do it yourself. Even the most modern and complicated sets hold no secrets from you. Yet this amazing course is simple, easy tomaster. No need to give up your present job. Keep it until you prove to yourself that Radio will raise your pay. For the National Radio Institute course is guar- anteed—if when you complete it you aren't fully satished with the lessons and instruction service, every cent you paid will be instantly returned. Send the coupon below at once for the book, “Rich Rewards in Radio.” It will be sent to you absolutely free! Learn how many have more than doubled their pay—see for yourself the wonderful opportunities for you in Ra- dio. No obligation. Mail the coupon right now. ee ee eee ee ee National Radio Institute, Dept. 3EH, Washington, D. C. Gentlemen: Send me your book. I want to see what Radio offers. this request does not obligate me, I understand ed L- Thank You for Mentioning Modern Mechanix and Inventions for May When Writing to Advertisers 9

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Lawrence Pykosz, of Hammond, Indiana, drives this light skimmer with a Henderson motor. A speed of 35 miles can be maintained in a heavy dew, on account of the boat (says Andy) has nothing on the bottom but the usual paint. Andy's Shop Mail Box Herewith is the harrowing tale of a pig who made a jump without a parachute, and how he applied at Andy’s abode for flying lessons in the dark of night, adopting Andy as a step-dad. AYBE its the spring fever. I dunno. But I been moonin’ around the hangar for three days‘now hoping to hit on a good punch line to start the bleat out this month. I been writing about Kings and Queens and fancy aviators (lo- eal canned variety) so long that I sorta out of habit look for something like that to remark about first off. But the king and queen business ain't what it used to be, I haven't got enough energy to keep from murdering my pronouns and verbs, and the home grown air cowboys ain't been hedge hoppin’ much what with the soft field, I have decided to write about a pig. Yessir, you really don't know me till you know about my Irish bedfellow. A nice little Hampshire boar I found by the roadside one night. * * * ' À couple of weeks ago I heard the gol darn- dest squealing outside the hangar. I woke up with a start, pulled on my boots, turned up the wick in the lantern, and fetched forth to quell the riot outside the door. I found the hungriest, shiverinest little shoat you ever see, blacker than all the colors of mid- night colored black. This animated strip of pork scuttled inside the hangar and ended up in my bed like a long lost brother. It was colder than charity out- side, and I peered acrost to the main highway leadin’ past the field. I figgered some farmer had been drivin’ to market, and that this little 10 hunk of pork had smelled airplane, stuck his nose out between the slats of the farmer’s truck, figgered he had a tail wind and was out of fuel, so he sailed out into the night forgetting his’ parachute. A born aviator—catch the idea? That’s the first time I ever had a flyin’ student apply for lessons in the middle of the night. I cleaned the bed up, stuck piggie near the stove where he swore and cursed all night long. Next day I rigged up a helmet to hold bran mash so he could nuzzle it, and now the maga- zine and the field and old Andy have a mascot. He’s learning the flying game, and his name is Parachute. * * Today he’s King of the Tarmac, tomorrow he’s Ham. * * * But now that we have a mascot and I’ve got this bucket of tripe going, let’s have a look into what the Gang has been up to since the last effusion of colorful hooey. Take a look at the little airdrive boat whose pix graces the head of this month’s col. No it is not Whizzer as designed by Westy Farmer, but. Whizzer was her inspiration. No, she doesn’t go so fast that her bottom burns up right on the water. No, she—well, let’s let her builder sound off: Dear Andy: I am sending you a picture of the boat which was built from one of the many issues of Modern Mechanix books I have. Modern Mechanix and

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Step tight up gents! tube by Guy Nelson, of Council Bluffs, Iowa. The town of Council may on the same principle. Meet Buddy, Billie and Darrel, Gang! The boat was of my design (I mean the body). I used a Henderson engine but the prop was home made. It did not take much water to put it in because it was so light. It's 12 feet long, and makes about 30-35 mi. per hr. Wish you would put the picture in your column, as I am a good reader of your book. Yours truly, Lawrence Pykosz, 4222 Wabash Ave., Hammond, Ind. Why, sure, Larry—you are a good reader of Modern Mechanix. I don’t doubt that your bus makes that speed, but bear in mind Gang, that that hull is light, or it'd never get up on top. Once out and on the surface, it doesn't take much power to step the speed up. Most build- ers of this kind of boat get their hulls too heavy, their power too low. * * w And next we have the second 32 em cut— the one of the sweet little neat little fleet little aero ice sled built of steel tube by Guy Nelson, of Council Bluffs, Ia., who says: Council Bluffs, Iowa. In your Dec. 1931 magazine you published a picture of an ice boat sent in by Ed. Schneider of Schenectady, N. Y. I thought it a mighty neat outfit, so decided to construct one. This one is made entirely of steel tub- ing, welded. It is covered with fabric. We used it some last winter but made a few changes in it this year. It works perfectly. Guy Nelson. It is fun to run pix of home vegetated stuff like this, because it shows that our ideas are permeating into intelligent minds who are will- ing to take advantage of the experience we have plastered into this well known Family Almanac. "ook 9 Three good troupers who have waited for quite a while to see their little wagon in print (full spindle here, gents) are Buddy Henry, Billie Mason and Darrell Boyles. They sent quite a long letter and I’ve had to wait until I got room to run it. Listen: 1107 23rd Street. Fort Madison, Iowa. Dear Andy: I have been a reader of the M. M. for a long time but as yet have never sent in any Imventions for May On the one hand we have a nifty little ice sled built right in airplane fashion out of steel be built on a bluff, but the sled is not run T'other side shows three fine lads old Andy is proud of. Their own home-built car is with ’em. articles or pictures, so I have decided to try my luck at having one of the pictures and the letter published in your mag. ` I am sixteen years old and Billie Mason and Darrell Boyles are 12, respectively. We have endeavored to build what is known to our neighborhood as the “What-you-may-call- it.’ It is a crude design of a midget auto which I have put together with my own ideas after several tries with various washing ma- chine motors. As you can see from the picture the auto is not much for looks, but it serves the pur- pose very satisfactorily. We have obtained tricycle wheels for the front and wheel-chair wheels for the rear. The steering apparatus is not so clever but it works as a brake and as a steering apparatus as well. Angle iron serves as the frame and has one inch pine boards for the cross pieces. A small washing machine motor is used which develops 94 horsepower. We have a direct belt drive with a six to one ratio, for an increased power. We go right down the street at a 18 m.p.h. clip with little difficulty in keeping out of the way of passing motorists. We can run all day on one quart of gasoline, which the tank holds. You may use any part of my letter for publication or all of it as you wish. Anyone interested in model autos please write to me as I am very interested in such. Am going to build a much neater rigging powered by an Indian single cylinder of the 1918 model machine with a friction clutch. Hoping to see my picture and letter in print I remain a faithful and anxious reader of the double M. An Auto Pal, Buddy Henry, Billie Mason, Darrell Boyles. *» k + From way up in the cold country, where the snows have probably not yet started to melt, comes a letter from H. Bergman, of Norman, Ontario. Note the chilly billy surroundings. Dear Andy: Here are a few pix of my snow sled. The specifications and other data are as follows: (Continued on page 14) 11

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Delays are Dangerous in Patent Matters HE FREE BOOK shown here was prepared for inven- . Q Q tors, to show them exactly what steps they must take to secure : a PATENT. 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. Remember, inventing an article is one thing— securing the exclusive 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 lf. è to do to protect yourse I Serve You Quickly and Secretly Anything you write me or send me is strictly confidential between us. Al letters and draw- ings are kept in strong, steel, fire-proof files, which are open only to myself or authorized members of my staff. Ihave secured patents for inventors located in every state in the Union. My organization is a large and efficient one. My practice is confined entirely to Patents, Trademarks and Copyrights. Ihavehad years of experience in Patent Matters. When you place your idea in my hands, I am in position to proceed at once to secure protection for you. My fees are reasonable, and, if you desire, I can arrange convenient terms of payment. 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 coupon on next page 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. v.e eo o9 oe I CLARENCE A. O'BRIEN Registered Patent Attorney 317-Z Adams Building, Washington, D. C. (Practice Confined Exclusively to Patents, Trademarks, € SMALL IDEASEEMAYEHAV EXE RGEPS ^COMMERCIAL POSSIBILITIES Gonyrightr) a iE oe 12 Thank You for Mentioning Modern Mechanix and Inventions for May When Writing to Advertisers

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This Book Tells: How your Patent Applica- tion is made; what kind of Sketches or drawings are necessary; whatotherpapers must be made out; how the Patent Laws protect you; why it is important to avoid loss of time in getting your applieation filed; and many other important points. Even avery simple idea, if new and useful, may prove very valu- able. You may have much to - gain and nothing to lose by sending for this book TODAY. FREE Record of Invention Blank Along with my book, I willsend youmy Record of Invention form, also FREE. This blank will enable you to make a sketch of your idea in proper form and have it witnessed in such manner that it may be of value to you as evi- dence should the occasion for evidence arise. In my book, I tell you how to use this form to protect your interests. My Location in Washington My offices in Washing- ton are convenient to the Patent Office, and I and my assistants can, therefore, B appear promptly before the Tre ES, : PDC : Registered Pat officials and Examiners. WAS HINGETO. Reasonable Fees and Convenient Terms J have served thousands of inventors in all parts of the United States and I am able to serve you very reasonably and extend liberal terms of payment. So don’t waste valuable time. CLARENCE A. O’BRIEN, Registered Patent Attorney, 317-Z Adams Bldg., Washington, D. C. Please send at once your FREE book. “How to Obtain a Patent” and your “Record of Invention” form. NAME,..eesscacsvececceoconceseveceececeeecocscscecieo ADDRESS.....eseoocecocesceeecteteoeecessosveevcveoe I l i l i l I I I í wp 13 ee eee eee eee ee ee ee (Be sure to write or print name clearly.) - I I I ! I l l I l l J l l l l I I I I l I I E Thank You for Mentioning Modern Mechanix and Inventions for May When Writing to Advertisers

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WOOD COMES RIGHT OUT OF A CAN! NEW, QUICKER WAY TO MEND BREAKS, SEAL CRACKS, MAKE REPAIRS — EXPERTLY Try This New Kind of Wood That Does Everything Glue or Putty Will Do... Does it Better, Easier You can do almost any- thing with this new kind of wood thathandles like soft putty and quickly hardens into wood— waterproof, weather- ptoof wood you can carve, turn, paint—wood Mends Breaks that takes and holds nails and screws and outlasts natural wood. Even if your fingers are all thumbs you can | do an expert job with PLASTIC W OOD-seal cracks, hide nicks, mend Seals Cracks breaks, anything that glue or putty used to be used for. Nothing bet- ter for making perfect models. Try it. You'll be surprised. Paint, hard- ware and department Holds Screws and Nails stores sell PLASTIC WOOD in 9 colors. Geta can or tube, today. PLASTIC WOOD Handles Like Putty—Hardens Into Wood ANDY’S SHOP MAIL BOX (Continued from page 11) Henry Bergman of Norman, Ontario, built this puddle flyer and makes 30-ft. leaps across open ice—if it is not too open. Skis—14 feet long, 12 inches wide, the edges being beveled. The span from center of one ski to center of the other is 8 feet. The over- all length of the completed sled is 19 feet 6 inches. It is powered with a Chev. of my own conversion, Turning a 4-foot, 6-inch four-blade prop with a 46-inch pitch at 2,000 R.P.M.’s. J am putting a new one on to hold it down to 1,600 R.P.M. The speed on moderately soft snow is 40 to 50 miles per hour with one or two passen- gers, the skis sinking 2 to 3 inches. I expect more speed on hard snow but:have not had any as yet. The day these pix were taken it was very mushy. The skis sinking from 4 to 7 inches and slush all over the ice, so I could only get 30 to 35 per at top speed. The sled rests on coil springs and is very flexible, the springs and axles allowing an up and down movement of the skis up to 2 feet, 6 inches, as the front axle is secured only at the center. If you are interested I can furnish you with plans and the instructions for building the sled and converting the motor. My sled will jump an airhole 30 feet long traveling at 40 per. Pretty near met my “Waterloo” the day I took these pix. Too many holes in suc- cession to be comfortable. I can also get you the plans for my Fire Fly of last season. You have the pictures of it. Hoping to be of ser- vice to you, I am, H. Bergman, Box 355, Norman, Ontario, Canada. P. S. I have read your magazine since you published the plans for the Heath Parasol and never had any reason for complaint. Shoot a few of the grumblers and watch the wheels go ’round. I built a sport plane too, but I had too much ambition and short on brains and experience. I get a bang out of Mr. Bergman’s little “sermoan” in his postscript. Months of toil, dreaming and final defeat are summed up in the phrase “too much ambition and short on brains and experience.” Out of such stuff are flyers made. * + + I frequently get letters from fellows who want to find a motor, or a prop, or something else on (Continued on page 16) 14 Thank You for Mentioning Modern Mechanix and Inventions for May When Writing to Advertisers

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Don't Lose Time--Send For Big FREE BOOK ACT AT ONCE—and protect your idea. Remember, to get the benefits of your invention, you not only have to invent it—you have to PATENT it. Many men spend years perfecting an invention, only to find that someone else thinking along the same lines has already received a patent on the idea, When we think of all such cases that have come under our personal observation, we cannot urge too strongly that you take steps to protect your idea IMMEDIATELY. Delays of only a few days may be vitally important to you. Do not lose all the benefits of your hard work in planning and perfecting your invention. Mail the Coupon for FREE Book Today — It is of tremendous importance that you flle your application for a patent at once. Our ES free book tells you how to proceed, what you need to know about patents in general and gives & A:N R:N: A Aa you an estimate of our reasonable fees. We also send you a ''Record of Invention" blank x free. Take the first step toward getting your patent now. Mail the coupon at once. If you & OF INVENIION BLANK BECDUTRX€E and degrription of your invention, we will promptly write you what, E T in our Spinion, ought to bedone in order to protect it, and for which service. there will > E e no charge. Highest References—Strictest Secrecy 34 Years of Proven Service he o of he tna of itor J. Evans & Co. are registered Patent attorney es s ur legal and technical forces include lawyers, registered patent attorneys, patent drafts- Mail the coupon today, and in addi- men and searchers. Our Patent Office and Federal Court practice is confined to patents tion to the free book, we'll send you and trademarks. We specialize In these two subjects to the exclusion of all others. In without charge a Record of Invention our 34 years of patent practice, we have successfully served thousands of inventors to Blank, This form, when properly filled whom we can refer. It is a distinct advantage to an inventor to employ an attorney out may be of value to you as evidence located in Washington as the U, S. Patent Office has no branches. should occasion require it. There is no charge or obligation for this service. Here’s How We Operate Mail the coupon NOW. As soon as the description of your invention comes into our office, it is Immediately put in charge of an attorney, who is particularly familiar with the kind of invention you have perfected. Under his close personal supervision, patent searchers and skilled drafts- Men work, He personally sees your ease through io its conclusion. You have the advantage of highly skilled and experienced Service. Reasonable charge. Deferred payments. Here’s What the Coupon Brings Mail It Now Mail the coupon today and take the first step toward protecting your idea. You will receive the FREE Book, a FREE Record of Invention Blank, and information on our fees. You create no obligation by mailing this coupon. Our service is complete, our fees reasonable, and our terms convenient. Don’t waste price- less time; mail the coupon NOW. E yo VER 2898 REGISTERED | PATENT ARRA MAIN OFFICE : 605EE Victor Building, Washington, D. C. BRANCH OFFICES: 1640 EE Conway Building, Chicago; 233 EE | Broadway, New York; 828 EE Fidelity Philadelphia Trust Building, Philadelphia; 514 EE Empire Building, Pittsburgh; 1010 EE Hobart I Building, San Francisco. Please send me your free book, “How to Obtain a Patent,” and your | “Record of Invention Blank.” Name................. Thank You for Mentioning Modern Mechanix and Inventions for May When Writing to Advertisers 15

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mU e in Lost legacies, miss- ing deeds, dazzling fortunes discovered between the covers of a book—an old and oft used theme of the atory writers. Unlike many good plots, it has under it the solid foundation of fact—it’s a true story. THERE IS MONEY IN BOOKS. There is a fortune for you 1000 those hooks ANDY’S SHOP MAIL BOX (Continued from page 14) a sort of cuff or shirt tail deal. Here is one such. I don’t mind running the letter, but take no re- sponsibility in connection with any such trades effected. If you have stuff like this, and want to get rid of it, maybe I can find room for worthy swap artists. As a sample here’s this for a starter. Please don’t write me—the address is given in the letter. Andy’s Shop Mail Box. Andy: Could you please, tell me where I could obtain a Henderson motor sitnilar to the one shown on a snowsled built by Manville Hut- temeier. I'm referring to the March issue. If it's impossible to obtain such a motor, please let me know of one just as good. Thanking you in advance, Herbert Wilke, 62 North Ave. Owego, N. Y. in these books—information in every sentence—knowledge that men have fought for, dug for. From your comfortable easy chair you can catry away equipment for your life work—high paid, steady occupation and sure advancement. AUTO ENGINEERING 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 profits, are waiting for any man who even half tries to 1m- prove himself. Here is nn amazing speclal offer to you if you seriously want to get ahead. 6 great big Auto books with jiffy index which mokes all facts instantly available. 2500 pages, 2000 illustrations, everything right up to the minute—synchro mesh and other newest im- provements. These books are yours on our new FREE EXAMINATION plan. BRAND NEW EDITION John Wocheck, of Danbury, Conn., built this pippy little car for his youngster. Nice, eh? Factory Supt., Garage Owner, Expert Mechanle, Auto Designer, Sales Englneer, these and hun- dreds of other blg Jobs are to be fillld by tralned men. YOU GET 6 Big Auto Books—Flexo Bind- ing, Membership in American Technical Society, entitling you lo full consultation privileges with 18 experts for one year. Imagine books which are so new that every page is right up to date—wiring diagrams, construction details, service problems—are all right up to the minute. Nowhere else can you get as complete and up-to- date information. Over a mil- lion dollars of resources have enabled us to give you the most authoritative books on the sub- ject ever published. Everybody interested in automobiles in any way will welcome these books, published by the world’s largest publishers of Techni- cal Cyelopedias (est. 1897) with agencies all aver the world. In volume 1, Nos. 3 and 4 of the Packmag, we ran dope on the construction of midget autos. A few of these copies are still available at this office by mail for 35 coppers the book. Much interest was tapped by these articles, and Sam and I have been flooded with pix of home- built cars. One of the most interesting is a pic- ture we get from John Wochek, of Danbury, Conn. John says: 32⁄2 Westville Ave. 3 Danbury, Conn., Dear Sir: Have been reading the M. M. since the first Send this Coupon NOW American Technical Soclety,*Dept. AS320, Drexel at 58th St., Chicago 1 want to get shead. Send me your6 Big Auto Books for 10 days’ free exam- ination. 1 will pay the few cents delivery charges only. If I decide to keep them I will send you $2.00 in ten days and $3.00 per month until the total price of only $24.80 (for everything) la paid. You are to include a year’s memberabip in e American Technical Society entirely Free. Name Aleo give the names and addresses of two business men who know you, Bs refer- ences if you want the benefit of this extra llberal offer. Gil 16 issue, but as yet have never dropped in a line to the shop mail box, so this being my first offense you will have to excuse me. I built this auto for my son out of a wash- ing machine engine and a few scrap parts and it sure is a knockout. Does the boy look happy? I'll say he does. So if you care to publish this in the mail box am sending you m photos of it, or do you need the negatives or it Would like to get in touch with Stanley Schmidt of Kansas who had a garden tractor made out of one of these engines. I would (Continued on page 18) Thank You for Mentioning Modern Mechanix and Inventions jor May When Writing to Advertisers mpre

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Give me your measure and Pil PROVE You Can Have a Body like Mine! "LL gi PROOF in 7 DAYS that I NOTE: No other ` ve you in S that I can : i I tutti. d too, into a man of might and : Physical Instructor muscle. Let me prove that I ean put layers in the World has of smooth, supple, powerful muscles all over your = ever DARED make body. such an offer!. If you are underweight I'll add the pounds where they are needed and, if you are fat in any spots, I’ll show you how to pare down to fighting trim, And with the big muscles and powerful, evenly-developed body that my method so quickly gives you, I'll also give you tbrough-and-through health—health that digs down The 97 Ib. weakling who became into your system and banishes such things as constipation, twice holder of the title: “The B World’s Most Perfectly Developed Man”’—won in international cone test against ALL strong men will- ing to compete with him. pimples, skin blotches and the bhundred-and-one other ailments that rob you of the good times and the good things of life, Here’s All You Do! Just jot down your name and address on the coupon below, mail it to me—and I'll send you, absolutely free, a copy of my new book, “Everlasting Health and Strength.’ It reveals the secrets that changed me from a 97-pound, flat-chested weakling into.a husky fellow who won the title of “The World's Most Per- fectly Developed Man” against all com- ers! And it shows how I can build you into an ‘‘Atlas Champion”’ the same easy way. Thaven’t any use for weight or pulleysthat may strain your heart and other vital organs, I don’t dose you or doctor you. Dynamic- Tension is all I need. It’s the natural, test- ed method for developing real men inside and out. It distributes added pounds of powerful muscles over your body, gets rid of surplus fat, and gives you the vitality, strength and pep that win you the admira- tion of every woman and the respect of CHARLES ATLAS As He Is Today. CHARLES ATLAS, Dept. 6-5, — 133 East 23rd Street, New York City. I want the proof that your system of Dy- namle-Tenslon will make a New Man of me— give me a healthy, husky body and big muscle development. Send me your free book, **Ever- fasting Health and Strength." Gamble a Stamp—-To Prove I Can Make YOU a New Man! Gamble a stamp. today by mailing the coupon for a [ree copy of my book, ‘Everlasting Health and Strength.’ It tells I you all about my special Dynamio-Tension method, and what it has done to make big-muscled men oui of run-down speci- mens. It shows you, from actual photos, how I hnve developed l my pupils to the same perfectly balanced proportions of my { own physique, by my own secret methods, What my system did for me, and these hundred of olhers it can do for you too. Don’t keep on being only 25 or 50 per cent of the man you can be! T'ind out what I can do for you. I Where shall T send your copy of ‘Everlasting Health and Strenpth''? Jot your name and address down on the coupon, and mail it today. CHARLES ATLAS, Dept. 6-5, 183 East Zürd Street, New York City. Name.........ssceereeeees a reh pentes (Please print or write plainly) Sta 1 (€) 1933 C. A.Ltd. [J| B E I D E iliam ed LII.-c- Me Thank You for Mentioning Modern Mechanix and Inventions for May When Writing to Advertisers 17

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BOYS?! Own the snappiest boat afloat! . the 18 Ib. nonsinkable MEAD "KI-YAK"! You can | assemble it in three days from our cut-to-fit "Ki-yak Kit" for only $11.75 ($6.50 starts you!). Are you going to "hang around" on shore and try to "bum rides" this Summer, or are you going to be the envy of all your Íriends by owning this graceful, speedy craft? For sheer beauty of line, speed, and safety, the MEAD “KI-YAK” stands alone;. there is nothing else comparable to it on the market. You can lift it with two fingers; you can carry it on your bicycle! It will carry you in three inches of water. It rides the breakers like a Hawaiian surf-board. WE HAVE A REAL MONEY-MAKING PROPOSITION for the first Ki-yak owner in each town. Don’t let your neighbor yet the jump on you; write for full information right NOW! (Enclose a dime to cover postage and circulars.)' MEAD GLIDERS Dept. M-53 12S. Market St. Chicago, Illinois RCA INSTITUTES Recognized Standard in Radio Instruction Since 1909 TechnicalTraining Courses in Radio and Associated Electronic Arts Practical Radio Engineering. Sound Engineering Broadcast Transmission Radio Servicing Commercial Radio Operating Resident Schools at New York and Chicago EXTENSION COURSES FOR HOME STUDY under new "no obligation" plan, with privilege upon graduation of 2 weeks' intensive practical train- ing without charge at either Resident School. = Mail Coupon for Illustrated Catalog. RCA | INSTITUTES, INC., L7 fil nil Dept. MM-5 75 Varlek Street, New York, N. Y. 1154 Merchandise Mart, Chicago, UII. 1 l Please send with no obligation to me: | { ) Illustrated catalog and information about resident school | | courses. i | ( ) Information about extension courses for study at home, | | together with illustrated catalog. | ANDY'S SHOP MAIL BOX (Continued from page 16) Donald Schultz's "Arctic Special" which developed a sure cure for headaches. like to build one too, possibly he could : give me a few pointers on the constructing of it Could you send his address? If you can use these photos and anyone wishing any information Í. would gladly sup- ply it. If you can’t use the photos throw them in the waste basket anyway. Yours until I rig up some other contrap- tion, ; John Wochek. You may be able to see that Wochek’s bus has a steel frame, and that the axles and spindle units were hooked from an old model T Ford. Welding them together on the "short side of the ledger,” as bookkeepers say, produced a swell- running, if not beautiful, little car for the youngster. * * * Whoa, there, Parachute! Git out from under this desk. My corns ain't acorns. Li » i Be a nice piggie and go away or Papa Andy will connect with whichever end is nearest the toe of my No. 11’s. Skaraam!! * 0 *— x Another ice sled addict comes up in the pouch from Ioway: Silver City, Iowa. Dear Andy: Have been following your column with in- terest nigh onto two years absorbing every- thing but contributing nothing. Am herewith submitting a couple of shots of our version of an ice boat built by my brother and myself during spate time. The craft is powered by a revamped Star four motor swinging a 5" 1' Flotorp prop that was once swung by a Szekely 40. This craft is of practically all Ford and Star parts with a sprinkling of Dodge. Although the motor seems a trifle overloaded the result is speed plus. . Must call your attention to the windshield and headrests, We tested this machine with- out them and immediately contracted a ter- rific headache and almost unconsciousness before we got wise to what the trouble was. Equipment of the rear cockpit consists of (Continued on page 24) . pee 18 ` Thank You for Mentioning Modern Mechanix and Inventions for May When Writing to Advertisers

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GEORGE F. JOWETT *'Chatipion of Champions'" World's Record Holder One of the world's strongest men. Winner of numerous contests for strength and phy- sical perfection. Acclaimed best developed man in contest open to the world! ns YOU Proud you too can have a perfect physique, if you will only follow my weight-resistance method of Physical Instruction ... for fifteen minutes a day! I promise that you too will-have arms of steel... a mighty chest . . . a broad back . . . and powerful legs, with muscles that you will be proud of...and I don't mean cream-puff muscles either! You will get real, genuine he-man muscles that will make your men friends respect you, and women admire you! So sure.am I that I can do all that I say, that I make this unqualifed guarantee . . . the guarantee that no Physical Instructor has ever DARED to make... » » | Guarantee to Add... j INCHES TO INCHES TO YOUR CHEST YOUR BICEPS +». oF it won't cost you one cent!” Signed GEORGE F, JOWETT Test my full course, if it does not do all I say—and I will let you be the judge—then it won’t cost you one penny, even the postage you have spent will be refunded to you! FROM LIGHTWEIGHT TO HEAVYWEIGHT A man of 130 pounds can by exercise and diet develop him- self into a 190 pound giant! I know, for I did it myself... increased my weight from 154 pounds to 195 pounds in less than one year...and all muscle too... with a 49 inch chest and an 18 inch bicep! Once I was a sickly boy ...envying the strength and health of others... but always with a great desire to have a stron; body. I studied the methods of famous strong men... too the best of their teachings...added my own ideas and gradual- ly developed my famous WEIGHT-RESISTANCE method of Physical Training...the system I have taught to over 10,000 men! FREE BO o RUSH THE COUPON TODAY ANDI WILL INCLUDE A FREE COPY OF l “Nerves of Steel .. Muscles Like Iron” l Ir explains why I am called “Champ: [ jon of Champions"— and there isa "thrill" in every page! It isa priceless book to che strength l fan and muscle builder. Full of pic- tures of marvelous bodied men who tell you decisively how youcan build symmetry and strength che equal of. | their owg, Reach out... Grasp This Special Offer. l Thank You for Mentioning Modern Mechanix and Inventions for May When Writing to Advertisers : WITH PHOTOS OF of YOUR Body? MY PUPILS HAVE BECOME NATIONAL AND INTERNATIONAL WEIGHT-LIFTING CHAMPIONS Nothing can take the place of WEIGHT RESISTANCEin the development of a strong body! My system does not depend upon the mere "flexing" of muscles... I use disc dumbbells that can be graduated in weight for the reason that no other method can give you strong, supple, weight-lifting muscles! By graduating the weight of these dumbbells, from time to time, in a scientific manner, I will quickly develop your muscles and broaden your chest so that the heaviest weight will seem almost as light as a feather to you. I'll teach you all the strong man stunts...from wrist turning...to hand wrestling...I will show you how to tear a pack of cards or a telephone book in half with ease e.. I will also teach you the Four Key" Bar Bell Lifts! Don't wait any longer, get going NOW —Try one of my test courses first—it will give you the big URGE— Send for **«Moulding a Mighty Arm" a Complete Course for only 25c. In one inexpensive book you can get a complete course on Arm Building. It will be a revelation to you. You can't make a mistake. The guaranty of the strongest armed man in the world stands behind this course, I give you all the secrets of strength illustrated and explained as you like them. You, too, can get an unbreakable grip of steel and a Herculean arm. Mail your order now while you can still get this course at my introductory price of 25c. I will not limit you to the arm, try any one of my test courses at 25c. Or, try all six of them for only $1.00. Dept. 37Sb, 422 Poplar Street, Scranton, Pa. Dear Mr. Jowett: Your proposition looks good to me, Send, by return mail, prepald, the courses checked below, for which I am enclosing $. à D] Moulding a Mighty Arm, 25e C Moulding a Mighty Back, 25e D) Moulding Mighty Legs. 23c D Moulding a Mighty Grip, 25c © Strong Men Stunts Made Easy, 259 CJ All 6 Books for $1.00. Name____ Age ] Address. O Moulding a Mighty Chest, Be Ree 19

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order. Classified Advertisements Rates for classified ads, 10c per word per insertion. n Closing date flrst of second month preceding date of issue. Address Classlfied Mgr., Modern Mechanix and Inventions, 35 East Wacker Drive, Chicago, lll. AGENTS MAKE your own products. Employ Agents yourself. Toilet articles, soaps, extracts. We furnish everything. Valu- able book Free. National Scientific Lab- oratories, 1964 Broad, Richmond, Va. BIG MONEY and Fast Sales. Every owner buys Gold lnitials 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 Booklet describes 87 plans for making $20-$100 weekly in home or office business of your own. Elite Co., 214-G, Grand St, N. Y. FREE literature describing many mon- ey-making plans. D-Belfort, 4042 N. Keeler, Chicago. WHERE to buy at wholesale 500,000 i Free circular describes 100- page Directory. Maywood Publishers, 925'Broadway, New York. (Dept. MM.) AGENTS WANTED YOU" ARE wanted to resilver mirrors at home. Profitable business plating auto parts, tableware, etc. Sprinkle, Plater, 850 Marion, Indiana. AGENTS’ Gold Sign Letters for store windows. 500% profit. Free sample. Metallic Letter Co., 426 N. Clark, Chicago. extracts. We furnish everything. Valu- able book Free. National Scientific Lab- oratories, 1964 Broad, Richmond, Va. BIG MONEY Taking Orders. Shirts, Ties, Underwear, Dresses, Hosiery, Raincoats, Coveralls, Pants, Uniforms, Playsuits. Outfit Free! Nimrod Co., Dept. 132, 4922.28 Lincoln Ave., Chicago. MAKE Money applying Initials, Mono- grams, on Automobiles, Suitcases, etc. Quick, easy profits. No experience needed. Free Samples. 'Ralco", 1084 Washington, Boston, Mass. METALLIC LIQUID—Repairs Metal, Wood, Everything without heat. Sells 25c. Sample Free. Bestco, 4323-W Irving Park, Chicago. 500,000 ARTICLES Wholesale. tory 1500 jobbers $1.00. Arts, B-1611-H, Denver. NEWEST money maker: Wondo polish- ing cloth, cleans all metals, one opera- tion, no muss. 25c sample Free. Wondo Míg. Co., B-2377 N. 39th St., Milwau- kee, Wisconsin. GERHART of Pa. cleared $772.46 from ONE idea. Send dime for 36 page pub- lication containing opportunities galore and distributor's proposition. Pruitt Press, R. Elburn, Ill. $ 50c SELLER. First Aid Kits. Auto- ists, Campers, Offices, Homes $2.50 doz. Send 25c for sample. Presto Bandage Company, Geneseo, Illinois. Write | RAZOR and blade sharpener, fully pat- ented, Size 3x2 inches. Counter and . Get our proposi- tion for protected territory. 50c. Write today. Co., 823 S. Sample Black-Stone Mfg. Wabash, Dept. 165, 15076 profit. _ National, 600-J, N. AGENTS, distributors. Sell Moth cakes, paks, bowlizers, metallic cement. People buy millions. Large profits. Patterson Z-Co., 4111 University, Des Moines, Towa. AUTOMOBILES THE FORD Model “A” Car and Model “AA” Truck—Its Construction, Opera- tion and Repair. This new edition in- cludes all new material and suggestions that have been made by Ford dealers and service men for improving and bringing this book right up-to-date— tions, 529 South Severith Street, Min- neapolis, Minn. AVIATION ARMY air corps gives free flying train- ing to Cadets. Our booklet ‘ i qualify for this training. post peed: Federal Equipment Co., Dept. 23, Deerpark, Ohio. ships, $248.00; H.P. motors, $75.00. Photos, i tion including leather bound Flying Manual, 25c. Hibbs, Ft. Worth, Texas. BUILD Corben Baby Ace, complete kits including factory welded fuselage, tail unit, under carriage. Folder, dime. Cor- ben Sportplane Co., Madison, Wis. DOPE, Newplane Nitrate for Airplanes, Gliders, Models. Highest quality non- blushing. Lowest prices. Write. Flex Products Co., 7 Duggan Bldg., Osh- kosh, Wis. NEW low prices on SB Aircraft en- gines, propellers, i parts, etc. folder to Sensenich Brothers, Depart- ment M.M., Lititz, Pennsylvania. PROPELLERS make your craft per- form when designed and built by us. New low prices, Send stamp for circu- Lorenzen Propellers, Niles, Mich. BE PREPARED in aviation for the next boom. Write for new home study tuition offer. Major Robert Rockwell, Dayton, Ohio. USED Airplanes $50 and up. Cata- log 10c. Federal Equipment Co. Deer- park, Ohio. Minimum 10 words. Cash should accompany DON’T Buy anything until you get Ort’s 1933 Aviation Material Catalogue. Prices are lower. Send one thin dime today. Karl Ort, 675 W. Poplar St., York, Pa. FOR SALE slightly used Waco Glider parts in first class flying condition, also other bargains in small motors and propellers. Send 10c for lists. Heine Motor Works, Orwigsburg, Penna. ADVERTISING AGENCIES 50 MAGAZINES year, $24. Wood's Popular Services, Atlantic City. BUSINESS OPPORTUNITIES ARTIFICIAL marble sanitary flooring, instructions covering wood or cement flooring % inch thick, fireproof, all col- ors, low cost. Ornamental casting, con- crete plaster, papier-mache decorations, garden furniture, statuary, flexible molds, particulars and illustrations free. W. Mahler, Elmont, N. Y 700 MONEY Making Secrets will help ou start a business of your own. Write linois Universal, 800-M, N. Central Ave., Chicago. SELL by mail: books, novelties, bar- gains! Large profits. Particulars free. H. Elfco, 525-S Dearborn, Chicago. MAKE your own products. Employ oratories, 1964 Broad, Richmond, Va. AMATEUR cartoonists, earn $25.00 week, spare time, copying cartoons for advertisers. Three-M Syndicate, Argyle. is. 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. TATTOOING outfits supplies, illustrat- ed list free. Waters M-965, Putnam, can Bullfrog Industries, 100-MM. Fre- mont, Ohio. MAKE Artificial Marble, Colorful glossy titles, no polishing, rather un- canny. Novelties, tabletops, bookends, floors, whetstones. Hard, inexpensive, fireproof, enamels wood. Secret_cement methods. Amazing samples 3c. John H. Payn, 945 Grande Vista Drive, Los Angeles, Calif. RECEIVE 100 letters and dimes daily. Guaranteed instructions, 10c. Write H. L. Dawe, 6249 Mershon St., Phila- delphia, Pa. MAKE Concrete Pottery. Birdbaths, vases, etc. Easy, guaranteed system. No molds used. 2,500 designs. Full range colors, Highest quality at frac- tion cost by other methods. 500% profit. Book free. National Potteries Com- pany, Minneapolis, Minn. —————————————Á— 1 20 Thank You Jor Mentioning Modern Mechanix and Inventions for May When Writing to Advortisers

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BUSINESS OPPORTUNITIES. DRAWING FREE booklet describing 87 tested suc- cessful home money making opportuni- ties without canvassing, outfits, expe- rience or capital. Dept. 88, Egard, 106th St., Broadway, N. Y. OPERATE Chain amusement machines. Be independent for life. Start small, grow big. S Goodbody, 1826 East Main St., Roches- ter, N. Y. HANDY MEN. A new money maker, nothing to sell. Plans one dollar. Ser- vice Company, 21870 Ball Ave., Euclid, Ohio. PROFITABLE Spare Time Mailorder Business! Read Mailtrade Tribune, 3c. 6450 Kenwood, Chicago. MANUFACTURE- ell your own bev- erages, extracts, candies, soaps, per- fumes, etc. Free booklet. Truway Lab- oratories, 1623 W. Grand, Chicago. MEN—WOMEN interested money home, write for details. F-277 Broadway, New York. BOOK PUBLISHER ABSOLUTELY mew vital health se- crets disclosed. Amazing results guaran- of vending and earning Eller, teed! Write! Vitalis System, AA- 1214 East Colorado, Pasadena, Calif. BOATS BUILD your own boat using Brooks (Originators of Knock-down System) ready-cut materials and save two-thirds regular builders’ costs, have more suc- cessful seaworthy craft. Frames fully assembled. Cruisers, Runabouts, Launch- es, Outboard Motor, Row and Sail, in- cluding Rudder’s Snipe Class Sailer. Also complete assortment Propellers, Shafting and Accessories. Send 10c for catalog. Brooks Boat Co. Inc. Box MM-39, Saginaw West Side, Mich. C ——"RLUEPRINTS —— ——— BUILD your own bench shaper for home shop or commercial machine shop. We supply complete blueprints and rough castings. Send for free descrip- tion and price list of parts. P. W. Cor- nelius, 2457 E. Washington St., Indian- apolis, Ind. CAMERA and PHOTO SUPPLIES MAKE Money in Photography. Learn quickly at home. Spare or full time. New Plan. Nothing like it. Experience unnecessary. American School of Pho- tography, Dept. 2049, 3601 Michigan Avenue, Chicago. CARPENTRY CARPENTRY: A very popular book for carpenters and apprentices dealing with carpentry and joinery in all its 326 pages, 431 illustrations, cloth bound: Price, postpaid, $2.00. Modern Mechanix and Inventions, 529 S. Seventh St., Minneapolis, Minn. CHEMICALS HANDBOOK for Chemical Experi- menters, hundreds of experiments, 50c. Booklet of Experiments, 15c. ‘Chemical Catalogue, 10c. Lowest prices. General Chemical Co., Reading, Pa. : DETECTIVES 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. DOGS FOR SALE SF. BERNARD puppies, beauties, large type. Paramount Kennels, 5345 McKenna, Montreal, Canada. pce ss BN RN Thank You for Mentioning Modern Mechanix and Inventions for May When Writing to Advertisers 2 ` ing: This 160-page cloth bound book with its 65 illustrations and specimen plates is an excellent treatment of the subject. Price, postpaid, $1.50. Mod- ern Mechanix and Inventions, 529 S. Seventh St., Minneapolis, Minn. 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. ELECTRICITY ELECTRICITY for Beginners, E. Har- per Thomas. 196 pages, 24 illustrations, $1.50. This is exactly what the title im- plies, a real elementary treatise. Pre- pares the reader for a more advanced study of the subject, and considers and explains many of the common terms and everyday manifestations of electricity. House Wiring, by Thomas W. Poppe. Describing and illustrating up-to-date methods of installing electric light wir- i Contains just the information needed for successful wiring of a build- ing. Fully illustrated with diagrams and plans. It solves all wiring problems and contains nothing that conflicts with the Rulings of the National Board of Fire Underwriters. Including Direct Current Motor Connections—Diagrams of series wound motor—and Motor Wir- ing. 208 pages, 160 illustrations. Sixth edition, revised and enlarged. Price $1.00. Modern Mechanix and Inven- tions, 529 S. Seventh St., Minneapolis, inn. ENGINEERING COLLEGES BRACHELOR Science Degree two years. Electrical, Civil, Chemical, Radio En- gineering. Earn board. Catalog free. Indiana Technical College, Washington. Ft. Wayne, Ind. FINGER PRINTS FINGERPRINT experts required; va- rious branches government; porations; particulars free. System, 2640. Y Broadway, N. Y. FORMULAS FORMULAS—all kinds. Guaranteed. Catalog free. “Kemico”’, B-16, Park- ridge. Ill. MONEY making formulas. Write for catalogue. Formico, 3737 Olcott Ave., Chicago. FORMULAS, business plans, Litera- ture Free. D-Belfort, 4042 N. Keeler, Chicago. FOR INVENTORS OUR manufacturer-clients now want additional improved inventions, patent- ed or unpatented. What have you? Chartered Institute, 531 Barrister Build- ing, Washington, D. C. FOR SALE SPECIAL attachment for broken hack- saw blades 25c. Frank Morella, 1417 S. 56th St., West Allis, Wis. ANTI-GLARE Shield Patent No. 1,790,965. Every Buick or Chevrolet owner a prospect. Address Box K., Nora Springs, Towa. FANCY pigeons, racing homers, ban- tams, rabbits, guinea pigs. The Morris Farms, Lincoln Highway, Batavia, Ill. HELP WANTED—MALE INSTRUCTION DETECTIVES. Work home or travel. Experience unnecessary. Wirite, Ameri- can Detective System, 2640-T Broad- way, N. Y. .MAGIC INVENTIONS INVENTIONS Commercialized. ented or unpatented. Write Fisher Mfg. Co., Louis, Missouri. Pat- Adam $82 Enright, St. your inventions patenting. Free particulars. Write W. T. Greene, 942 Barrister Building, Washington, D. C. INVENTIONS commercialized, at- ented, unpatented. Contact manufac- turers. Precilla Company, Call Build- ing, San Francisco, California. JEWELRY LEARN Watchmaking. Lesson Practice Movement 25c. Any watch repaired, $2.50. Old gold bought. Stewart's, Carleton Building, St. Louis, Mo. MAGIC 35 MAGIC Tricks, 10 games, and all magic catalogs 20c. Gilmagico, Morgan Park, Chicago. LEARN MAGIC. Large catalog of tricks you can do, Holden, 237 W. 42nd St., N. Y. MAGIC catalogue. Wonderful knock- out card trick. -10c. Singer, 444 Han- cock, Wisconsin. BAFFLING Hindoo Magic Wire Trick 10c; Book of 250 Magic Tricks 10c. Catalogue Free. Reeder, 733 4th Ave., Clinton, Iowa. AMAZE and Mystify! Fool your friends with Magic. Be Popular—earn money. No skill required. Send today for Free Catalog Magic Tricks, Puzzles, Joker’s Novelties. Or, send 25c for 240 page Professional Catalog. Lyle Doug- las, Station A-4, Daltas, Texas. atalog 20c. Lynn, 105 Beach, Dept. 1, Jersey City, N. J. MALE HELP WANTED FOREST JOBS easily available. $200 month. Cabin. Hunt, trap, patrol. Get details immediately. Rayson Service, K-32, Denver, Colorado. MEN to distribute advertising, samples for manufacturers. Good pay. No sell- ing. Work immediately. The South- ern Advertiser, Tampa, Florida. Stamp. MANUFACTURING illustrated 25c. mechanical line. Models, experimenting, production. Parma En- gineering Works, Cleveland, Ohio. MANUFACTURING, Models, dies, stampings, brasswork, moulds for cast- ings, vulcanizing. Circular free. Baums Metal Specialties, Kansas City, Mo. MODELS INVENTORS: Send us sketch or crude model of your idea. Crescent craftsmen will develop it into a prac- tical working model. 30 years of suc- cessful experience and thousands of satisfied clients. Confidential service guaranteed. Bank references furnished. Free illustrated book: “Making Inven- tions Pay.” Crescent Tool Co., Dept. T-5, Cincinnati, Ohio. MODEL ENGINES “REAL” Motor, gasoline, for model airplanes, boats, 34”x34”, ™% bop. weight 1 1b., 3200 r.p.m. Catalog “Real Boats," motors, fittings, 20c coim. P. Loutrel, 96 McDonough St., Brooklyn, New York. MOTORS H. P. rebuilt 2 cycle gas engines 2.00, 14 H. P. motors standard makes .00. S. and B. Sales Co., 619 S. Sec. ve. W., Newton, Jowa. (Continued on page 22) RAR po T

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CLASSIFIED ADS MISCELLANEOUS EFFECTIVE sales letters $3.00; ads 1.00; 12, $10.00, ''Superad" Service, ox 250, Ithaca, N. V. LOCKSMITH directory, locksmith in- i books on Houdini, Hardeen. Send stamp for list. Nugent. 30 North Third. Richmond, Virginia. LORD'S prayer size of pinhead 25c. W. Keyser, Irvington, N. J. SEND 5c for catalog. Boat accessories, railroad cars, airplanes and supplies. Selley. 1375-A Gates Avenue, Brook- lyn, N. Y. FREE Hornesteads—some improved. Forfeited; 18 states; maps, ‘‘700 facts," 40c. MY-33, Modern Mechanix and Inventions, Minneapolis, Minn. MARBLEIZING Cement. Applied over anything, or in molds, sets quickly. Re- sembles polished marble. Practical mold making. Rubberite composition flexible like rubber. Send dime for Rubberite sample and sample Marbleizing Cement, directions to use. Cowell Institute, Grayling, Mich. BE INDEPENDENT! Learn tattooing! Outfits $7.84 up. Free instructions in- cluded. Write to Chicago Tattoo Sup- ply House, 432 So. State, Chicago. OIN. American Amateur Chemists ciety. Particulars, Journal 10c. Box 476-C Lansing, Michigan. MOTORCYCLES SEND 15c for illustrated used Motor- cycle catalog. Large stock. Bargains. Indian parts. Accessories. Indian Mo- torcycle Sales, Kansas City, Mo. HENDERSON, Excelsior, Harley, In- dian, used parts, alloy pistons, catalogue and wings pin 10c. Ballak, 100 N. 12th, St. Louis, Mo. MUSICAL INSTRUMENTS MAKE your own guitar, grand concert size, on straight lines. Plans 25c. Boyd Stevenson, Effingham, Illinois. ia ren ru ai e t rir nai et m ade OLD GOLD WANTED TEETH Bought. Mail us your crowns and bridgework, also broken and scrap jewelry. Rings, pins, chains, watches and silver. Articles returned if offer unsatisfactory. Ideal Jewelry Refining Co. Dept. 112, 737 So. Grand Ave., Los Angeles, California. i OLD MONEY WANTED Coin Value Book, 4x6. Guaranteed Prices. Coin Exchange, Box 56. Le Roy, New York. PATENTS GET your own patents; legal blanks, complete instructions $1. Cudding Sons, Campbell, Calif. INVENTIONS Commercialized. Pat- ented or unpatented. Write, Adam Fisher Mfg. Co., 582 Enright, St. Louis, Missouri. PATENTS-—Small ideas may have large commercial possibilities. Write immediately for information on how to proceed and *'Record of Invention" orm. Delays are dangerous in patent Clarence A. O’Brien, 28-M Adams Building, Washington, D. C. M. H. FORD, registered patent attor- ney, specializing in difficult cases; easy payments; free preliminary information. 225 Broadway, New York, N. Y. PATENT for sale, automatic, backstop for automobiles. A. ply O. Bjork, Box 401, Kamloops, B. e. Canada. d 22 .wave receiver, (Continued from page 21) PATENT ATTORNEYS 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 EE Victor Bldg., Washington, D. C. INVENT something! New discoveries have cured previous depressions. Un- patented ideas can be sold. I tell you how and help you make the sale. Free particulars. Write W. T. Greene, 958 Barrister Building, Washington, D. C. PERSONAL x MAKE new friends California and elsewhere, California Letter Club. Pri- vate or General Membership. P. O. Box 3642 San Francisco. BORN Clairvoyant. will reveal your future. Five questions answered for $1.00; Forecasting on stocks. ''Arlitt", Lock Box 278, Wilmington, Mass. WHY be Lonely? You can make new friends. Particulars Free. The Ex- change, Box 38V, Hickman Mills, Mis- souri. ESCAPE from your lonely existence! Valuable information free. Write today. Box 128-MM, Tiffin, Ohio. FIVE Spirit Mind-reading Stunts, $1.00 postpaid. J. Tillberg, Proctor, Vermont. BECOME a Faith Healer. Arouse latent Christian Powers. Box 70, Wa- tertown, Mass. LONELY HEARTS—Join our Club, the world’s greatest Social Extension Bureau. Meet nice people; correspond- ents everywhere. Photos, descriptions free. Standard Box 601, Grayslake, Il]. PRINTING 1000 BUSINESS Cards, card case, $1.50, Miller, Printer, Narberth, Pa. QUALITY Printing. Exceptionally low prices. Print anything. National, Syra- cuse, Indiana. PRINTING OUTFITS AND SUPPLIES PRINT your own circulars, envelopes, with home-made press costing less than $1.00. Illustrated instructions, Dime. en Dawson, Box 392, Coshocton, io. PROPELLERS PROPELLERS—Designed for boats, sleds and planes. State your need. S. B. Henderson Motor, A-1 Condition. The J. B. S. Propeller, Lititz, Pa. RADIO GUARANTEED *'Pocket-Radio", $2.00 postpaid. Marvelous reception. Short- $5.95. Catalogue 10c. Neil Tasker, Shamokin, Pennsylvania. SHORT wave sets, kits, supplies. Cry- stal Radios 65c. Headphones 90c. Mi- crophones 60c. Wholesale catalog 10c. Federal Radio & Telegraph Co., 4222 Cliford Road, Cincinnati, Ohio. 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. RAZOR BLADES RAZOR blades resbarpened keen, ic each. Petter G, Wetterquist, Rockford, Illinois. SECRET SERVICE SECRET Service Methods. Particulars free, Excellent opportunity. Experience unnecessary. Write, Wagner, 2640-Y, Broadway, N. Y. SONGWRITERS SONGWRITERS! Poems, melodies. Astounding proposition. Hibbeler, D195X, 2104 Keystone, Chicago. SALESMEN WANTED WANTED: Man in each county who will be satisfied with $25 to $35 a week earnings in the start doing service work and demonstrating new Automatic Fire Alarm in Schools, Homes, Hotels, Thea- tres, Public Buildings, etc. Write quick for county appointment. Fire-Cry Com- pany, Dept. 616, Dayton, Ohio. AMAZING new plan offers earnings up to $85 weekly. Life and disability pro- tection at cost. Not insurance. Bene- fits up to $1,000. Membership and Re- gistration only $6. You keep $5. Every- body, ages 1 to 80, prospect. American Aid, Dept. M-2, South Bend, Ind. MANUFACTURER guaranteed quality shoes, 29 years in business, wants sales- men. Big profits daily. No experience necessary. Sales outfit free. Write Mason Shoe Mfg. Co., Dept. D31, Chip- pewa Falls, Wis. SHORT STORIES SHORT Stories Revised. Typewritten, Marketed. Details Free. Hursh Service, Box K-1013, Harrisburg, Pa. SONGS, POEMS, WRITERS. SONG writers wanted now. 50-50 plan. Indiana Song Bureau, Salem, Indiana. STAMPS STAMPS! 100 diff. 2c; 500 diff. 35c.; 1,000 diff. 90c. Tatham Stampco, D9, West Springfield, Massachusetts. 25 DIFFERENT Stamps for 3c_pos- tage. Approvals on request. Otto Berg- man, 4715 S. Hoyne Ave., Chicago, Ill. 5 YEMEN, 5 Charkari, 5 Afghanistan, 15c each packet. Unused stamps accept- cd Imperial Stamp Co., Allahabad 74, ndia. : 105 (CHINA, ETC.) 2c. Album (500 illustrations) 3c. Bullard, 446P, Tre- mont, Boston. WORTHWHILE Penny Approvals. Magnificent Sets. Elyria Stampco, Earleourt, Elyria, Ohio. UNITED States—Nine stamps cata- loguing $1.00. Special 10c. Superior, Box 1276, Palm Station, Los Angeles, Cal. STAMPS FREE Canada and New- foundland bumper packet sent approval applicants who send 5c to cover cost of mailing. Jackson, 1761 6th Ave. E. Owen Sound, Ont. Canada. 5 SCARCE triangles, Philatelic Maga- zine, 10c. Albert Gardner, 5220 Cuth- bert, Baltimore, Maryland. UNITED STATES Stamps, $1, $2, and $5, with Tanganyika, North Borneo, etc., for 10c to approval applicants. References: Drisco, 882 M. 57th, Brook- United States price list 10c. Seidenberg, Baroda, Mich. VENTRILOQUISM LEARN Ventriloquism by mail; small cost, 3c stamp brings particulars. Geo. W. Smith, 125 North Jefferson, Room S-558, Peoria, IIl. Thank You for Mentioning Modern Mechanix and Inventions for May When Writing to Advertisers

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for Germany? Thrill to this true story of how Friedrich Wilhelm von Bergersfeld, Operative No. 9 of the German Imperial Secret Service, diced with death in the world war—a remarkable story written in exile. | O’Leary’s Tank Busters A complete novelet based on records and citations of the "Treat 'Em Rough" outfit, a thrilling front line story of fighting Yanks by the world's foremost author of war stories. BY ARTHUR GUY EMPEY Thrilling True War Stories A complete magazine of true war tales. There are hours of thrills with heroic fighters on land and sea and in the skies in this great issue of a great magazine written by decorat- ed fighters of various nations. FAWCETT'S \ BATTLE STORIES If your news dealer is sold out, send 10c in stamps or coin to BATTLE STORIES magazine, 529 §. 7th Street, Min- neapolis, Minn., and a copy of the current issue will be mailed to your address. Now On Sale! 10 CENTS ‘plane enthusiast. Gasoline Driven Models CARLSON ALBATROSS 6' 4" Span — 3' 6’’ Length — Total weight 2.5 Ibs. The Carlson “Albatross” is the only ship of its kind on tha market, lt really FLIES using a Knight one cylinder gasoline motor. Full description given in circular. RUBBER DRIVEN MODELS C. G. ATTACK CARLSON GULL ATTACK 17'^ Span, 1812'' overall, double surface wing, bent bamboo parts. Modern design has made the performance of this gull-wing attack the sensation of the model world. We invite you to compare ite price, unique design, and dazzling flying abilily with anything on the market. All bamboo and wire parts are bent; ribs and bulkheads are printed on balsa. All other material necessary, including plans, colored paper, cement and dope are furnished in kit. This model has everything—it’s the finest of them all. Priced very low, only 75e posipald in U, S. FREE Plans for Laird Super Solution with every folder. SEND 10c for il- lustrated folder giving prices for all Gasoline and Rubber powered models. CARLSON MODEL AIRPLANE CO., Dept. K-3 134 S$. CLINTON ST., CHICAGO, ILL. . For Knight-gasoline motors to power the “Albatross” see Power , Model Boat and Airplane Co. ad on page 136. 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- Here’s a sample of some of the high spots in the Edition: 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 If 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. Thank You for Mentioning Modern Mechanix and Inventions for May When Writing to Advertisers 23

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MEN WOMEN WEEKLY REVOLUTIONARY NEW, LOW-COST LIFE PROTECTION All your life you've longed for an opportunity such 8s this an opportunity for you to have greater Prosperity! $5 PROFIT FROM EVERY $6 ORDER UP TO $25— 340 DAILY, EASY The wonderful feature of Natlonal Ald Soclety’s Plan is the steady, ever pyramiding income that awaits you. A cash-in- advance profit beckons from every door—actualiy $5.00 profit on every $6.00 order! You do not spend a penny for your selling equipment which you ean easily carry in your pocket. It's furnished you entirely FREE. Write just one $6.00 order and pocket e Five Dollar profit for it then and there! No waiting for deliveries, no future tollections, no C. O. D.'s to be returned. MAKE 4 AND 5 SALES EVERY CALL National Ald Society Plan appeals to every member of every family, and the good news spreads from neighbor to neighbor. You can eften actually pocket $10 to $15 at a single call! A NEW ADVANCED FORM OF PROTECTION The NATIONAL AID SOCIETY is not an insurance Company. It is organized under the laws of Indiana, not for profit. Its Purpose is to provide protection for all who otherwise could not elsewhere secure such protection excepting only at prohibitive costs. It offers Safe, Sure, LIFE AND PROPERTY PROTECTION MERELY AT COST. YOUR FIELD UNLIMITED No Medical Examination! Practically No Age Limit! You can sell two memberships to any one Person, thereby doubling these benefits—and doubling your profits as well. THIS COUPON BRINGS YOUR FREE STARTING OUTFIT Begin Making Money Same Hour You Hear From Us! Mail Coupon Now and we’ll send you, ENTIRE- LY FREE everything you need to start. Within ten minutes after opening our letter, you can START COLLECTING FIVE DOLLAR BILLS! Write your address below—and mail the coupon NOW. National Aid Society Dept. 953 Springfield, HMlinols RUSH THIS COUPON TODAY, NATIONAL AID SOCIETY, Dept. 953, Springfield, IHinols Rush me Free Complete Starting Outfit, full details of your Profit-Sharing Plan and Big Money Making proposition. | | NOMG cp ena c eee caves esos see ere tase eereee ne eee sees rass | Address ........ 4c sores ee haa osbassenéssat khe "m ANDY'S SHOP MAIL BOX (Continued from page 18) steering wheel, spark and gas controls, self starting switch, ammeter, brakes, etc. Although this (Arctic Special) cost ap- proximately $35 we got that much kick out of building it. However, the real thrill comes in the driving. It handles like a homesick Cadillac. Sincerely, Donald Schultz. Now ain’t that something? I am glad to see that comfort has been thought of by our Donnie boy. I am now wondering whether he needs springs on the bus or not. I have had many an afternoon’s fun with this kind of breeze buster, and really the: ice gets quite rough, although it looks smooth. I didn’t know what the head- aches came from, but am glad to know that it was wind. I thought it was rough ice and still think that no design for one of these contrap- tions is finished until springs are allowed for. An afternoon’s ride is provocative of quite a pain in the piazza. * * * Now comes old Dad Storms again, that in- defatigable Nawth Ca'lina flying pioneer. Head what: 88 Charlotte St., Asheville, N. C. Gentlemen: Here are.two snapshots of "The Bug," a Model A Ford-powered flivver built by J. E. Kennedy and Claude Beamgard of Clover, S. C. The little ship is strongly built, weighs about 700 pounds and is a fine performer with the Model A motor. Both of these boys have taught themselves to fly it by taxiing it on the Spartanburg Air- port until they could handle it on the ground almost as well as an automobile. This practice was followed by short hops a foot or two above the ground until they could land more or less smoothly, They now make excellent take-offs and landings and handle the ship well in the air. The plane lands at 25 m.p.h., has a high speed of about 75 miles, and cruises at 65 m.p.h. If either of the photos is clear enough to print please use one or both in an early issue. Yours very truly, N. E. Storms. Here's a ship snapshot which is sent by iN. E. Storms, of Asheville, N. Ca'lina. A Ford “A” job with nice charac- teristics, aloft or afield. (Continued on page 28) Ipse 24, Thank You for Mentioning Modern Mechanix and Inventions Jor May When Writing to Advertisers

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They dared Officer Kane to play en- .. and his snusi THEL’S house party was at its height—when suddenly there came an ominous knocking at the door. Ethel ran to open it—there stood Police Officer Kane. "I want to see the man of the house," thundered Kane. "I'm sorry," stammered Ethel nerv- ously, “but my father is not at home.” “Well, what’s goin’ on in here any- way?" continued the officer sternly. “Every one on the block is complainin’ of the noise. I’ve a good mind to arrest the lot of you.” Ethel was mortifled—what o disgrace! “Oh please,” pleaded Ethel, ‘‘please don’t do anything like that.'" Then Kane burst out laughing. "Don't worry, lassie—you were all havin’ such a fine time I couldn't help droppin’ in,” he explained. “Oh,” sighed Ethel, “chow you frightened me. Won't you join us?” Kane Joins the Party "Ha," laughed Kane, as the Victrola Started again, ‘why must you play that canned music—can’t any of you play this beautiful piano? Sure, I'd like to give you a tune myself." "I dare you to play for us," shouted Ted Plano Strong. ans "I'm afraid I'll.have Cornet to be goin'," stammered Trombone PICK YOUR INSTRUMENT "'More—more," "That's great—play an- other," they all shouted as the last 2 notes of that snappy march song dled away. Jane then started that stirring old soldier song, “On the Road to Mandalay,” following it with song hits from the latest shows. “Well,” he laughed, as they finally let him get up from the plano, 'I'l have to be on my way now.” “Thank you for your lovely music,” Ethel. years?” "'Sure, and I haven't been playin' long at all."* Then the questions came thick and fast. “How did you ever learn so quickly?'" ‘When do you find time to practice?" ‘Who was your teacher?'" Kane Tells His Story said “You must be playing a good many Violin Clarinet Flute Saxophone Harp Piccolo Mandolin “Well, to teil you the Kane, embarrassed. z Guitar "Cello truth I had no teacher. "Mr. Kane, I think Hawailan Steel Gultar I've always loved music, you might play for me Sight Singing but I couldn't take reeur after the fright you Piano Accorülon essons on account of my gave me,” smiled Ethel. “Well, b’gorry, maybe I wlll,” agreed the officer. And as he sat down at Lhe piano everyone laughed. But thə noise stopped when he struck the first rollicking notes of the famous '"'Song of the Vagabonds.’’ coh Thank You for Mentioning Modern Mechanix and Inventions for May When Writing to Advertisers Volce Specch Culture Harmony and Composition Drums and Traps Automatic Finger Control Banjo (Plectrum, 5-String or Tenor) Juniors' Plano Course duties as a policeman. Then one evening, I saw a U. S. School of Music advertise- ment, tellin’ of a new way of learnin' to play. I didn't believe it myself, but I sent for their Free Demon- stration Lesson that showed me how easy it was, so I wrote for the whole course. ic held them spellbound “There were no tiresome scales or tedlous exercises. I played real pieces almost from the start. Now I’m playin’ classical num- bers or jazz, havin’ the time of my lte.’ * * * This is not the story of just one isolated case. Over 600,000 people have learned to play by this simple method. You can, too. Even if you don't know one note from an-- other you'll grasp it in no time. First, it tells you how to do a thing—then It shows you how in pictures—then you do it yourself and hear it. You teach yourself—right at home—wlth- out any uninteresting finger exercises, tedious scales of other humdrum methods. Free Booklet and Demonstration Lesson To prove how practical this course is, the U. S. School of Music has arranged a typical demonstration lesson and_explanatory booklet whlch you may have Free. They show how anyone can learn to play hls favorite instrument by note in less than half the time and at a fraction of the cost of old slow methods. The Booklet will also tell you all about theamazing new Automatic Finger Control. Don't delay—aet at once—fill in and mail the coupon below today—no obligation what- ever. (Instrument supplied if desired. cash or eredit.) U. S. School of Music, 2625 Bruns- wick Bldg., New York City. U. S. SCHOOL OF MUSIC . 2625 Brunswick Bldg., New York City Please send me your free book, 'How You Can Master Music in Your Own Mome,” with inspiring message by Dr. Frank Crane, Free Demonstration Lesson and parliculars of your easy payment plan. I am interested in the following course: Have You fees teen eee ene Instrument? ......... NADiBe zioiaes2ekewsam emen PR RU e KR x ard une Address 1.06.0 ee eee ee eee nnn t City..... secesesssars State...... tsss

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THIS GREAT BIG 29 The world's biggest value in mechanical toys. STEAM ENGINE POWERFUL NEW MODEL JUST OUT Add 10c for post- age and packing A great big steam engine, measuring 7 inches in height by 2% inches in diameter (7!2 inches in circumference) for ONLY 25 cents, You should see it run, too. It's a revelation to see the fly wheel spin around at a great ratę as soon as you "get steam up’’. Just fll] the boiler with water, light up, and in a [ew minutes the engine 1s running at top speed. New model—just out— runs on alcohol] or canned heat, has fly wheel [or running small mechanical toys. FULLY TESTED— GUARANTEED TO RUN It is foolproof, harmless, fully tested and guaranteed to run. A sclentific toy that illustrates the principle of the steam turbine. water. 25e, with worth double. Runs for hours on one filling of Every boy should have one. Wonderfully well made—splendid value for the money. Sells for ONLY | ness. {0c extra for postage and packing. Well MAMMOTH NOVELTY CATALOG 10c Add 1t before. JOHNSON SMITH & CO. MIDGET BIBLE GREAT CURIOSITY BrmalleatHibla In the World. Bise of a poste b stamp. 200 Pages, Baid (o bring good luck to be seen to ba ^ppreoiawsd, — Muke good mop. selling tbem to friends, churob ‘acquaintances, eto. PRICE 186 eniri. 3 for 400, 12 for ' $1.35, 100 lor $7.50. Also obtainable in Leather Binding. with gold edges. Price 500 $1.25, $4.80 per dor. Magni- tor use with Midget Bible 156 SERPENT'S EGGS Boz contains 12 erg». When a lit with e match, each one graduelly becohes Iteali into a b s Withabunch of these bllls, it ig easy for each persot of limited means to appear DU BbshibE y Nashin a rollo é these bills i at the " proper tlme and peeling off a genuine bil) or two from the outside of the roll, the effect created will be found to be all that oan be desired. Prices, postpald: 40 Bilis 20c, 220 for 50c, or $3.50 thousand postpald. NOSE FLUTE The Magic Nose Flute, or Hu- a unique and instrument that ith nose and mouth . There Je just a knack Sn pi a liitle prace nable you yery awe that somewhat 3 resembles a flute. There is no fingering, and once re have mastered it you can pley ell kinde of muic with facility z nd ease. JOHNSON SMITH & CO. lOc more if you want our gigantic catalog, nearly 800 pages puzzles, tricks, jokes, ete. of electric and other novelties, You never saw a book like Only catalog of iis kind in existence. Dept. 919 RACINE, WIS. SURPRISE MATCHE More fun than rA fighting with your wife. Look just like ordinary matches. As the victim tries to light one he gets quite & surprise. ^: Price 10c por box, 3 hoxeg for 25c, 12 for T5 conis. STAR TOY MAKER Greatest boys’ book written. Tells how to make a Pinhole Camera, a Canoe, model Railroad, a Tele! phone, merang, Tele granb Instrument, B o x| ite, Talking Machine, Microscope. ectridg Motor. Electric Door Bell, Water Wheel. Paddle Raft, a pair of Skis, a Dog Sled, Bird House, Rabbit Yard, etc. 64 pages. 150 Nlustrations. PRICE ‘100. BOY'S OWN TOYMAKER. A new book. ‘leila how to make chemical toys, electrical galvanic toys, mechanical toya, paper loye, cardboard toye, boata, traps, eto. 200 fllustrations. Price 25c postpald. FUN WNH MAGNETISM. 50 novel end unique experimente in MAGNETISM that you can perform with the 4 ai] aid of an ordinary magnet: magnetio chain. seing and Tare Spinning needle, nail sn — ball cluster, magnetico fish, top, motor, magnetic billiard balls, many other stunta. Aleo interesting information about ledeatone, magnetism, electric ty, etc. PRICE 10c p.pd. BOOK ON BOATS. How to build rowing. sailing boate. Everything pertaining to boate explained in plain terme eo onyono can undore stand, Illustrated. 100 p.pd. pm S.MINUTE HARMONICA GOURSE. A new ensy self-teaching method. Teaches how to play, to use the tongue, tremolo, fully illustrated. Price 15c postpald. MONEY MAKING SECRETS. Golden oppor- tunities for everyone. 64 page copyrighted book chock full of money-making idese, recipes. Íormulas, wrinklem, trade secrete, etc. Busi- nesaea that can be started with little or no capital at home in apare time. _10c postpald. RICKS & SOCIAL ENTERTAINER. Con taine hundreds of simple tricks, illusions, di versione that anyone can do. Also explains secret of second sicht. Price 250 postpald. WONDERFUL X-RAY TUBE A wonderful little instrument pro- Qucing optical . illusions both eurprising and startling. WItbit ily the bones of pencil, tbe In nd many othe: terior ope: similar Ma ftot 250. JOHNSON SMITH & CO. Dept. 919 xek In magi rubber heed ed above. RACINE, WIS. of our NEW CATALOG mailed on recelpt of 10c. or the De- dition v ith cloth binding 250-Bigper and better than ever.Qnly| $ book ofits kindin existence. the newest novelties, puzzles, tamps, unusual and Interesting books, curiosities in seeds, and plants, etc., unprocurable elsewhere. o rder, Check or unused U. S. Postage Stamps, for all articles I early 800 pages of all the latesttricks james, Sporting goods, Remit by Coin, Mone ist- Canadian money, stamps and Postal Notes accepted if 20 per cent added for Exchange. Address orders Jor ail goods on. above and on following page 26 CAMERA AND COMPLETE OUTFIT {Add 10c for Postage and Packing} _ Although this apparatus is so MARVELOUSLY CHEAP, it is quite efficient, and will take SPLENDID PICTURES. Just the thing for beginners in photography. It takes pictures not quite 2x1% inches wilh clearness, sharpness and distinct- Loads in daylight. Has a VERY GOOD LENS; BRIL- LIANT VIEW FINDER, a simple yet effective SHUTTER, time and instantaneous, leatherette handle. Comes complete with 4 FILMS, 1 package of PRINTING PAPER, a neat little PRINTING FRAME with glass iop, and a SUPPLY OF CHEMICALS fer developing, fixing and turning out the finished picture. Full printed instructions so plainly written that a child cannot fail to understand. Never before has such an inexpensive opportunity been offered of indulging in the fascinating art of photography. With this outfit you can take portraits of your frlends, views of places of tnter- est you may visit, and snapshots of curious events and quaint characters. The CAMERA AND COMPLETE OUTFIT FOR ONLY 35c (Canada and foreign 50c) with 10e extra for postage and packing. EXTRA FILM (0c per package of 5 Films. EXTRA PRINTING PAPER 10o per package. JOHNSON SMITH CO., Dept. 919, RACINE, WIS. LOOK 356 LOOK ee EN. instrument. Greatest thing yet.NIne Beparate articles 1n one. Everybody de- 5 lighted with it. Odd, Curlous and interest- ing. Lots of pleasure as well as very useful. It Isa double Microscope for exe amining the wonders of nature. 1t l8 also an Opera Glass, a Stereoscope, a Burning Lens, a Reading Gloss, & Telescope, a Compass, a pocket Mirror, and a Laryngoscope—for examining eye, ear, nose and throat. It 18 worth all the cost to locate even one painful cinder in the eye, Folds flat and fits the pocket. Something great—you need one. Don’t mise It. Sent by mall. Only 950 or 3 for $1.00. PISTOL CIGARETTE CASE It looks like a deadly weapon, but It Is merely a novel Cigarette Case. This clever contrivance has proved itself better than the real thing in many an awkward encounter. Great fun “sticking up” your friends. They squirm and protest itmight beloaded. Pull the trigger and the slide files open disclosing the ciga- @rettes. Well made, light and compact. Welght only 2 ounces. IPosPAD 35€ LEARN to . Hypnotize TThis64- page book tells how. Explains all about Hypno- tism, how to 3 hypnotize, how to produce sleep, how to awaken a subject, how tohyp- notize animals, hypnotism in diseases, hypnotism for scien- tific practice, illusions and halucinations, persona] mage netism, thought transference, . Written in plain, everyday for With the aid of thifdream book and fortune- teller. The key to your future. Will you be lucky in love? Suc cessful in business? Will you be wealthy? Complete with dictionary of dreams with descriptions and correct interpreta- tions, with lucky numbers, fortu- nate days, oracles, divination, palm- istry, ete. Also ‘tells how to tell fortunes by various methods, by grounds of coffee or tea, by domi oes, by marka, scars, or moles, mis- Sellaneous, games with carde, lucky d x 7 AYS, Woka. TIDADIA, VERTA age that anybody can under- receive oracles by dreams, finger language thet a loc hostpaid. nal! observations, etc. CE 10c FORTUNE TELLING BY CARDS 64-page book tells how. Gives the meaning of each and every card, how io deal and lay them out. , Everything explained iu simple language. PRICE 10c postpaid. 770 page catalog 10c. to Johnson Smith & Co., Dept. 919, Racine, Wis. Thank You for Mentioning Modern Mechanix and Inventions for May When Writing to Advertisers

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A PRIVATE TELEGRAPH SET of YOUR OWN Here you are boys! A private electric j telegraph set of your own for 15cl Lots of fun sending messages to your friends. Get two sets, hook them up as shown in the directions, for two-way messages for sending and receiving. No trouble at all to operate with the simple instruc- tions that accompany each set. Operates on any standard dry battery oblainable everywhere. ‘With this outfit you can learn Nvv. Md Educational " Entertaining to transmit and recelve mes- national Code, and ina very / short time become an ex- /” on wooden base meas- Sending uring 4x8 inches, and Receiving tion throughout,com- Plete with key,sound- Become an expert ture Western Union blanks, packed in a neat Dor Telegraph Operator with full illustrated Instructions—ALL FOR 15o JOHNSON SMITH & CO. Dept. 919 RACINE, WIS. ——Á—M——MÀÁÓÁÁM——ÉÉÓÁÉÁÉÁNS made and effective modeled ~ a on thepattern. "eee. type of Re- volver, the ap- pearance of which alone is enough to scare a burglar, whilst, when as effective as a revolver with real bullets, without the danger to life. Blank Cartridges, that are obtainable most everywhere. d Even the most timid woman can use it with perfect Eae anyone else. A Great Protection Agalnst Burp!ars, Tramps and Dogs. You can have it lying about without the danger at- and superlor quality for $1.00. Blank Cartridges .22 cal., 50¢ per (00. Cowboy type Holster 50c. Not prepaid. Shipped Express only. Used by police officers, detectives, sheriffs, self-protection. Very effective. Easily fits the hand, the fingers being grasped in gency. Made of aluminum they are very llght, weighing less than two ounces. Handy pocket each, 2 for 49c postpald.770 page catalog lOc, MAKE YOUR OWN sages by the -Morse Inter- pert operator. Mounted | first class construc- emere er, magnet, minia- ^. — (without battery) postpald, Canada & Foreign 20c. in a very short lime This well A : PRICES ER Pistol e of the, latest tm loaded, it will probably prove just It takes the standard .22 Calibre safety and frighten a thle? without risk to herself or tached to- other revolvers. PRICE ONLY 50 CENTS. Better make JOHNSON SMITH & CO., Dent. 919, RACINE, WIS. night watchmen and others as a means of the four holes. Very useful in an emer- Bize always ready for instant use, Price 25c RADIO RECEIVER Enjoy the concerts, baseball games, market reporte, latest news. etc. This copyrighted book “EFFICIENT RADIO SETS” shows how to make and operate inexpensive Radio Sets, the materials for which can be pur- chased for a mere trifle. Also tella how to build a short-wave Recelver for bringing In foreign stations 180 Jokes and Riddles, 21 Puzzles and Prob- lems, Gypsy Fortune Teller, 50 Money Mak- ing Secrets, 36 Experiments in Magic, 58 Verses in Comle Poetry, 7 Parlor Games, 15 Gard Tricks, 10 Funny Readings, 71 Toasts, Cut-outs for Checkers and Chess. Domi- noes, Fox and Geese, 9 Men Morris. Ana- hips at sea, etc. ONLY grams, ete. AllfordSe. Postpai 770 page catatog 10 REPEATING AND SINGLE SHOT AIR PISTOLS police calls, 15c, postp: Just what you've slways wanted. À powerful high grade Air Pistol, shaped liha an Automatic, pocke! eize, Fires BB. shot obtainable eny- Very powerful yet perfectly safe o handle, Two stylee—Bingle etol or Repeater. The Repeater fres 100 shota In oneloeding, The Single É Shot Pistol shoots Air Rifle Darts in ad- dition to B. B. Shot, Well made and durable; all metal parta nickel plated: natural grain wood stocka. Front and rear hte. Wei hs about 10 ounces. Better an an al e. jo license required. PRICES: Single Shot Pistol $2.75, 100 Shot Repeating Pistol $5.00. Not mallable. Shipped hy Express only. Not prepatd. Send remittance (Postage Stamns accepted) for all articles listed above, also In our other ad on previous page Thank You for Mentioning Modern Mechanix and Inventions Jor May When Writing to Advertisers BOYS! BOYS! BOYS! HROW YOUR VOIC p. Into a trunk, under the bed, x JA ! under a table, back of the door, i A into a desk at school, or any- å h where. You get lots of fun fooling the teacher, policemen, , peddlers, and surprise and fool all your friends besides. The Ventrilo is a little instrument that fits in the mouth out of sight. Cannot be detected. It is used in connection with the above, and with’ the aid of this wonderful DOUBLE THROAT, OR_VENTRILO, .you can imitate many Kinds of birds, animals etc. Remember you. get everything for ONLY TEN CENTS—a booklet giving you full instructions how to become a ventriloquist and throw your voice, also the Double Throat, or Ventrilo, the Original Bird Call ‘and Prairle Whistle for giving imitations of birds and beasts, etc. 10c All Sent Postpaid to Any Address for Only MAGICIAN’S BOX OF TRICKS Apparatus and Directions for a Number of Mys- terious Tricks, Enough for an Entire Evenings Ente. nt., sesion BIC-ANYONE CAN DO THEM 1t ia great fun mystifying your friends. Get this Conjurer's Cabinet, and you will be the oleverast fellow in your district, It containg the apparatus for ten firat-class tricke, inciud« ing The MAGIC BALL AND VASE TRICK (a wooden ball is placed inside, and upon re- placing the lid bas disappeared and i Ja found meone else's pocket); e RUE TED oed IBN no less then five times): = NG COIN BOX tu corn, placed ia tee Priden box, vanisber entirely or ohanges into a col of another denomination); The GLASS GOB- LET TRICK (a coin In dropped into a glass of water and when the water is poured oat the coin bas vanished and is found somewhere else): the RIBBON FACTORY FROM THE MOUTH TRICK (a seeminrly endless supply of colored paper ribbo put of your meutb); ie DIBAPPEARING HANDRERCHIEF [a bandker In tho hand pona Vanishes); the WIZARD'S RING COIN TRICE; the EN- CHANTED BOTTLE (no one but yourself ie able to make it lay down); the GREAT HAT AND DICE TRICK (a large dice is placed on top of a hat, di found underneath yet no one hus touohed the hat), PHANTOM CARD TRICE, or two from five leaves nothing: Full instructions ere sent for performing each trick. In addition to the above, a number ot other feats and illusions ara fully explained for which you can eneilv mnke or procure the necessary Apparatus. Price complete $1.00 postpaid. JOHNSON SMITH & CO. Great Book for Boys, Post- BOY ELECTRICIA Students, Etc.—Only 10c paid oz The HOW and WHY of electricity fully told in elmple lenguace that any boy can understand. Scores of plans and instructions for making-—dry batteries, dynamos, electrio motors, telegraph apparatus, telephones, electric lights, electrio door belle, alarms, electric engine, rheostat, mail box alarm, electroemognete, automatic incandescent flash, elecirig shocking machine, wireless telegraph apperatus, induction coil, ero light, current reverser, etc., eic. Tells all about electric wiring, statio electricity, magnets and magnetism, conductors and insulators, electrostatic in~ duction, the electroscope, the electrophorus, con- denters, the Leyden iur, dynamio electricity, the yoltaie cell, electromagneta, electrolysis, electro-plat- ing, eleetretyping, eto, Also tells how to bulld a radio receiving set for afew cents. Nearly 100 illustrations. Sent postpaid to any address on receipt of ONLY 100, coin or stamps. 770 page novelty catalog 10c. 250 MAGIC TRICKS 1 0c For Parlor or Stage An excellent little book containing nearly 300 a comes ief held ieappeats, ond ie d Inst, but not least, the GREAT. MADE UCM "5 Tricks for parlor or etace. "Tricks with carde, coine, OP bandkerchiefa, eges, rings, glasses, Bowers, thimbles, spoons, bottles, string. rplaine the mystery of the floating head and scores of other nmazina feate of maglo and illusions. Also Second Sight, Bhadowgraphy, etc. So simple a child can perform them. Profusely illustrated, ONLY 10c. ————————— 125 CARD TRICKS and eleight of band. Con- teins all the latest and best card tricke as performed by celebrated magicians, with exposure of card tricks used by professional camblersa. Price 26¢ m grite Wonder Grystal Radio Receiver $1 Say what you will about Electrical and Bat- tery Sets, a CRYSTAL set has them all beat for simplicity and clearness of tone. There is absolutely no noise and no distortlon—no bat- teries to buy—-no tubes to wear out—no matn- tenance expense whatsoever. Cost nothing to cperate and will last indefinitely. Reception is loud and clear. This Receiver ts guaranteed to work equal io the most expensive Crystal Set you can buy. Has a receiving radius of over 25 miles, or under favorable conditions up to 100 miles. Consiructed of the finest materials throughout, including supersensitive crystal, assuring quick results. PRICE of Receiver only $1.00 postpald. Or complete with Ear Phone and Aerial Kit—everything all complete— nothing more to buy, $2.95 postpald. . Pert Racine, Wis. 27

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——a—— Y When Doors Won't Open Furnaces Don’t Heat Faucets Drip Windows Stick —Fix Them Yourself In these times when pennies count, many home owners put up with the inconven- lence 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 repair plumbing, plaster, concrete, electric equipment, etc., 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. Itis, 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. Thank You for Mentioning. Modern Mechanix and Inventions for May When Writing to Advertisers Í Enclosed fnd $1.00 (eash, stamps or M. O.) for which please send me it ul BOOKS SENT FREEI ON APPROVAL 5 VOLUMES BRAND NEW EDITION OnlyI5rminutesa day wlth theseWONDER BOOKS will prepare you for a good draftin job in less than a year. Mechanical an architectural drafting from simple stralght lines to Important complex plans. A step at atime? Built especially for beginners, for men with only grammer schooling. Draft- ing room practice, PLUS ENGINEER- ING, made easy and clear. Includes com- plete course In Bir aded brin Big Field Big Demand ig Pa 2,000 pages, 1546 blue- pies e. s urgently needed right now Y prints, charts and oll building and manufacturing lines at $50.00 to i z 100.00 k. T he be diagrams; prepares JDeiPTSMEN HAVE THE BEST CHANCES FOR you for a good draft- ADVANCEMENT. _Pleseant, fascinating work ing job in mechanical easy to learn and do. Learn quickly with these books or architectural lines. J: year's consulting membership in 3) For Beginners Written, so you can understand every word, by 22 famous engineers and archi- tects. DeLuxe flex- ible binding, nearly —send coupon for a eet FREE and see for yourself, ? ‘American Technical Sociely now giten free Sent for 10 days’ free to"all readers of thit famous cyclopedia of |e useif you mail coupon drafting. Many say that i ts worth immediately. than the cost of the books. Complete set of drawing instruments if you send for these drafting books NOW, These instruments are made of the finest of German silver, are absolutely accurate - and are packed in velvet lined leatherette pocket case. Real $10 value, but free to you with these books. AMERICAN TECHNICAL SOCIETY Dent. D-5320, Drexel at58th St.. Chicago, lll. — —— —— ÉL ILL American Technical Soclety, Dept. D-5320, Drexel at 58th St., Chicago, lil, Send for 10 daya’ free use New 5 volume set of drafting. | will pay the few centa delivery charges. If 1 wish, 1 may return books in 10 days and owe you nothing but if | decide to keep them, I will send $2.00 after 10 days, then only oe a month until $19.80. the specia) introductory price, Is paid. Send Brand New ed- more ition and Include drawing instruments. Áddress.... Embloyer's Nam. Address. DL] Merten ar aoe eet . 5 sections, brass bound. Big 3f e Telescope 10-mile range. Study Moon, Stars and dis- lant objects with this powerful 8-x instrument. Speclal eye plece for viewing Sun included FREE. Makes an ideal Micro- aopen Guaranteed. Blg value. Postpaid $1.75. C. O. D. c extra BENNER & COMPANY, T-75, TRENTON, N. J. 20-lesson Portfolio, com» plete with instructions on drawing for comic papers, cartoons, pretty girl features, ete, y NICK NICHOLS, Cartoon Instructor at Chi- cego Academy of Fine Arta, Art Director of Associated Editors’ Newspeper Syndicate, and creator of Just Supposin', Peter Pen (the Bottle Imp), Young Upstarts, Otto Watt, Radio Comics, etc. Gives valuable tips on trade secrets, how end where to sell, eto. Special introductory offer for limited time only. Don’t delays eend coupon and $1.00 NOW and get started. nS Se a uum Gs n: Studio of Nick Nichols, 157 E. Erie St., Dept. 26, Chicago, Ill. your COMPLETE Cartoon Course and trade cecrets. ]

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Build your boat now for that spring launching fever that hits you every year. "How to Build 20 Boats" will give you endless hours of fun. Build Your Own Boat! 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 Here's your copy of this eagerly sought file of the i designs, sharpen up that pencil, grip that Book hammer and satisfy that old urge to build for ALL BOAT BUGS!... your own boat. ON SALE EVERYWHERE PARTIAL LIST OF CONTENTS: Plans for Gannet, Ford powered cruiser—Dorothy, 24-foot sea- If your local newsdeal- going motorboat—Buddy, a Habl tabloid cruiser—Mayfay, wonderful little ralsed deck crulser—Wanderboat, a 16-foot er cannot supply you, outboarder—All Sorts, a 10-foot combination ice, sall and motor- boat—Scram, sensational performing Ford A runabout—and send 50c stamps or coin thirteen other designs for all Kinds of boats. to FAWCETT PUBLICATIONS, Ine. 529 SOUTH 7TH STREET MINNEAPOLIS, MINNESOTA di 30 Thank You for Mentioning Modern Mechanix and Inventions for May When Writing to Advertisers Rae

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ANDY'S SHOP MAIL BOX (Continued from page 28) We had a lot of fun with our little Packmag Pietenpol model. At Christmas time a west coast department store magnate wired us to ship it off Bang, bang, bang. Now speaking of engines and exhaust noises, glimpse yonder X engine built by Russell (L.) Bourke, of Petaluma, Caylifornyia. It, like Parachute, our pig, will run day and night in any position. Sweet work, Russ. to him, and off she went as a gift to some lucky ; kid the old man wanted to please. Now to keep the continuity, we reach up into the old sleeve again and say “Bang, bang, bang.” That is the sound of an exhaust. Now speaking of exhausts reminds me of the motor that Russ Bourke of Petaluma, Cal., built. Here’s his letter and a pix. Box F 2, Petaluma, Cal. Dear Sirs: Being a constant reader of your magazine, and deriving the most enjoyment from read- ing about all the new scientific and mechani- cal advances, and what other readers are doing in their shops, I thought perhaps some of your readers would enjoy reading about my "Silver Eagle," a small, Radial-Ex Aero- plane engine, which I built in my home work- shop. It weighs forty-five pounds, and develops 40 h.p. at 1,400 r.p.m., is air cooled, has full- splash lubrication, crankcase holds 3 pints of oil, no oil is mixed with the gasoline. It is a modified 3-Port, 2-Stroke cycle prin- ciple, having no valves or gears. As there are four power impulses to one revolution of the crankshaft, I use a four- cylinder distributor from a car, directly con- nected to end (rear) of crankshaft. It has a 2V5-inch bore, 2-inch stroke and the two main and connecting rod bearings are “S. K. F.” ball bearings. The crankshaft is a two-piece single throw, without counter balances, which are unnecessary due to the power overlap—(power impulses every 90°.) I will not mention the full consumption , only to say it is most economical, for no one would believe it. It runs either clockwise or anti-clockwise, right side up, or down, crankshaft in a hori- zontal or vertical position, with the same effi- ciency. The dimensions are 17" frontal height, and width, 6” long—front to rear. I am planning to build a larger one this spring, of 100-150 h.p., as I feel a material reduction in weight per h.p. can be effected. Wishing you continual success, I remain, Respectfully, Russell L. Bourke. do Thank You for Mentioning Medern Mechanix and Inventions for May When Writing to Advertisers HowTo SecureA W oome nh Tells About These and Other Positions RAILWAY POSTAL CLERK $1850 to $2700 a Year POSTMASTER $1200 to $2500 a Year | CITY MAIL CARRIER m $1700 to $2100 & Year R. F. D. MAIL CARRIER $1800 to $2300 a Year FREE BOOK tells how I can help you get a Gov- ernment Job. For 8 years I was Civil Service Ex- aminer—have helped thousands. Yf eitizen, 18 to 50, you can qualify. Get ready NOW for a posi- tion in the future! Send for free book. Write or mail coupon TODAY. -— — u— EM im MEER GENE unum GEM = == A ae = A. R. Patterson, CIviI Service Expert,435 Wisner Bidg., Rochester, N. Ys Please send me your free book ‘‘How to Secure a Government Position.”’ AMS: c2ciamaserecsnhwd cadaniedsvemnievanwes adaee wudeweeuweneess Address SPECIAL MAIL TRADE SERVICE Mail Order Dealers’ Annual Year Book, 35¢ postpaid. Uebersee Post, Importing and Exporting Journal. Sample copy 60c. Subscription 12 issues, $3.15. FRED HETTICK, Secretary Mail Order Dealers’ Association BISMARCK, N. DAK. WAS the BODY of the LINDBERGH BABY REALLY FOUND? The most astounding develop- ment that has yet been brought to light; amazing discrepancies in official measurements of baby found and the kidnapped child. * Several other fascinating true mysteries from the police records including the story of How a Kidnapped Boy Defied Killers Who Terrorized Chica- go Courts. € MAY ISSUE NOW ON SALE EVERYWHERE 3

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BLUEPRINT Get your copy of Modern Mechanix and Inventions’ big Blueprint Book— it’s free! 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 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: own shop. 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 but 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 feer 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- prihts 6 swe oH ... 91.00 M-M SPORT ROADSTER—Cus- tom-built to your own fancy! Four- cylinder motorcycle engine, chain drive, wood frame, Model T Ford differential unit, four wheel brakes. With these cheaply acquired units, the car does 65 m.p.h. Body of fabric construction, easy to work. Blueprints ........-- 5...82.50 M-M SPEEDSTER BODY-—Rac- ing body for a Model T Ford or similar chassis. Wooden frame, wire .covered, then a layer of cot- ton batting held down by imitation leather. Blueprints ....... $1.00 "n 2€. ast pnt Nieto" AIRPLANES AIR CAMPER —Pietenpol'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- DHÜIS :coacuensuhgo enn $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 rear with motorcycle engine. Motor should be of at least 20 h.p., not over 125 pounds weight. Blue. prntS ....-...2 dos ss $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 hull. 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 8500, depending on locality. Blue- prints i.2z:lacerasnueea pgdbu $2.00 CANVAS CANOE—By Chester Nedwidek. Length, 16 ft., plank. ing of 5/32.in. cedar covered with No. 8 canvas. $15 should turn out the complete job. Blue- prints «oe. ++ $1.00 MODERN MECHANIX AND INVENTIONS, 529 S. Seventh Street, Minneapolis, Minn. : Genttemen: Please send me my copy of the big new Blueprint Book by return mail. This comes to me without the slightest obligation. I enclose $............ in payment for blueprints of........ Pee ae (Note: This form can be used if you wish any of the prints listed above without walting for the descriptive booklet.) CTO suc wasser 32 Thank You for Mentioning Modern Mechanix and Intentions for May When Writing to Advertisers New PLANS for the Shop Worker

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Getting Personal With Biggest Bears (Continued from page 60) "Her mate was just behind on a little knoll, but as soon as that old sow let out that roar, he came in sight over the hill. He stopped for just a second to size matters up, then charged straight for where the two of us were standing, right out in the open. I knocked him down with the first shot, breaking his left front leg but he got up and kept a-coming. My partner and I hit that bear 11 times while he was coming not over a hundred yards and when finally he went down he was less than a dozen feet from us. Don’t ever tell me a brown bear won't charge." “Stopping a charging brownie at close range,” says Jay P. Williams, Forest Examiner for Alas- ka, “demands only a moderate amount of skill as a marksman, but does place a great deal of emphasis upon steadiness and coolness, The roar of one of these big brutes at close range, and especially if wounded, is disturbing and nerve-wracking but it must be met with the single-minded determination to aim carefully, squeeze, not jerk, the trigger, and with faith in a favorable result. To get away with it suc- cessfully even once means a great strengthening of morale and self confidence which will prove to be a valuable and steadying influence in the next encounter.” Mr. Williams is convinced that these bears rank with many of the most dangerous jungle animals in Africa. He explains: “While it is not generally recognized, it is really true that hunters and other visitors to the Alaskan forests are sometimes called upon to face a situation fully as critical and death- dealing as those which confront the African big- game hunter. Whether the brownie has thirty or forty times more power than is necessary to mangle an unarmed man is not pertinent to the situation. The important fact is that the animal must be stopped virtually in his tracks to in- sure a man’s safety. “It was the opinion of a celebrated African big-game hunter and writer, whom I met last summer, that it is easily possible to encounter these giant bears under conditions and situations which are on a par with those which the Afri- can hunter is called upon to face. A lion may cover ground faster, but his charge is generally met in the open while a charging bear is gener- ally encountered in heavy cover. Even a small brownie, weighing perhaps only 1,000 pounds, is probably a harder animal to kill than is the lion, especially when enraged, which is another pecu- liar feature. When a bear's fighting blood has been thoroughly aroused, no matter how many times he.has been hit, he keeps on charging. "There has been much recent discussion of this whole subject. Some people advise you to run away and climb a tree, since the brown bear does not climb. This may be advisable under some conditions but in many other cases it is not possible. There are situations when the only salvation is to shoot it out.” Of course, however, this ferocity of the brown bear towards human beings is only one angle of (Continued on page 34) dn make Crowns, Plates, Bridgework, etc., for Dentists. Easy, prac- tleal way to learn mechanical dentistry at home in spare time. Full equipment of TOOLS AND MATERIALS INCLUDED WITH COURSE FREE. Low tui- tlon, Easy terms. Write for FREE BOOK about this money making profession that js not affected by machine age. McCarrie School of Mechanical Dentistry 316 S. Wabash Ave. Dapt. 532 Chicago, It. Dirt Track Racing Now you can break into the racing game. How to build your racer, contest rules, supercharges, bal- ance, speed, "revs," compression ratios—a complete racing treatise illustrated. Postpaid $1. Madisonville, Cincinnati, Ohio. RAY KUNS, Dept. A, Home Automatic Cigarette Machine Amazing Invention Put tobacco and block of papers in machine, TURN THE CRANK end PRESTO CIGARETTES. simple. All metal construction. Guar- a anteed. lo cloth ribbona; no special tube or mmed papers required. Automatically feeds andseals papers. Saves 2-3 the cost of ready made eivarettes. ASK FOR FREE ILLUSTRATED FOLDER. Price $1.85 Postpaid. Tobacco and papers included. (Formerly $5.00.) Agents. Bir demand. Thousands in use. Write today. AUTOMATIC CIGARETTE MACHINE WKS. 1055-1057 Sherldan Rd. Dept. MM Chicago, Il!. Size bxbx8 in. , Handsome enama el & nickel finish. How to Make and Use a Small Chemical Laboratory, by Raymond Francis Yates. Price 75 cents postpaid from Modern Mechanix and Inventions, 529 S. Seventh St., Minneapolis, Minn. Want a Big-Pay Broadcasting Job? If you have talent here's your chance to get inte Broadcasting. New I'loyd 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. Glve age. FLOYD GIBBONS SCHOOL OF BROADCASTING 2000 14th St. N. W., Dept. 3E42, Washington, D. C. E A PASSENGER TRAFFIC INSPECTOR GOOD PAY--SPLENDID OPPORTUNITIES ACTIVE MEN--19 to 55--trained asS, B. T. I. Pa enger Traffic Inspectors for Bus and Rallway Work ere in demand. Interesting, bealthful (outdoors), travel or stay nearbome. On completion of our easy home-study course in a few weeks, we'll place you in & positlon (orrefund money) paying up to $140 per Beant, Ps SP Gree Bocklen, Standard Business 0 per month. Free Booklet. Training Institute, Div. 6105, Buffalo, N. Y. 5 Master Keys Work like magic in emergencies or prove whether your door or padlocks are burglarproof. 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NEW [Jp pe LOW PRICES |; Nx f YoucanrelgonChica- MAN o'8 oldest, moat reliable rub- .S, A. prove standard bra: reconstructed by Midland are best. Long, hardservice op rough roads guaranteeds REG. CORD TIRES Size Tires Tubes ea $1.90 $1 E $1.90 $0.85 0. UNNNNNNe NNUOOO NO! res. prooop8 issn 00 a gu W a nt ES DRAG " Di o sETof NON-GLARE HEADLIGHT LL TUBES NEW | REE ‘ORS GUARANTEED FREE WITH EACH S ORDER FOR 2 TIRES Send $1. 9 » Dopod v with each tire ordered. 50% more Balance C. you gend cash in fuil ii deduet 5%. You are guaranteed a year’oserv- ice or replacement at }4 price, Order today. MIDLAND ,TIRE & RUBBER CO., Dept. 3023 1000-20 West Sixty-Third Street, Chicago, Illinois EASY $5.A DAYS possible with new magic invention — nnn RA | e. P. FEFEETEECT m A., aab ai GOD o B s c S a R $ 1 2.10 2.15 2.20 2.25 2.60 2.60 2.65 2.75 2.75 2.95 2.95 2.95 2.95 2.95 2-00 uiro ODDO at fad ptt a oo os ELD (b 0D (D: L BBR ADR m ww BN oo eum to e ihat lights gas instantly without sparksor flame. A sure sale where- ever gas is used. Retails for 25c. MYSTERY CAS-LIGHTER N fetim on this Peckedon individual cards with Instructions. 9G MONEY Sample 10c. Rush $9 per gross or $1 per dozen. MAKER— NEW METHOD MANUFACTURING CO. X. ACT NOW . New Method Blds., Desk MG-5, BRADFORD, PA. E PASS dS Class pins— any letters, any any colors. Silver plated, 12 or more, 25c each; 1 to 11, 30c. Gold @ plated, 40c; sterling, 45c. Class rings, medals, ete. BIG CATALOG FREE. METAL ARTS CO., Inc. Factory 45 Rochester, N.Y. 1000., Needed Inventions by Raymond Francis Yates. $1.50 postpaid. Modern Mechanix and Inventions, Minneapolis. Double the life of your coat and vest with correctly matched pants, 100,000 patterns. Every pair hand tailored to your measure; no *readymades.'* Our match sent FREE for yous . K. before pants are made, Fit guaran Send plece of cloth or vest today. SUPERIOR MATCH PANTS COMPAN 115 S0. Dearborn Street, Dept. 32 oF Y Chicago Pays AGENTS Y% va Hour SPREAD-A-TREAD repairs worn spots for . Spreads on witha knife. A Driesoverni ing. 2,000 additional miles guaranteed. Enda costly re-treading. Savea buying new tires, ı Write for Free Sample showing ‘work done $ end special Agents’ Offer. Plastic Rubber . Of America, Dept. E-235, E. Court St Cincinnati, O. t. Tough, flexible, long woar~ § Getting Personal With Biggest Bears (Continued from page 33) the situation, so far as Uncle Sam is concerned. Our government realizes that this interesting animal, the largest carnivorous land mammal in the world, is very valuable for scientific reasons and a great attraction to tourists. Which ex- plains why the Senate’s special committee on the conservation of wild life resources recently completed a study of the brown bear, offering these conclusions: “It is recommended that Afognak Island, which is immediately east of Kodiak Island, be set aside by Executive Order as a perpetual sanctuary for this bear. It is fur- ther recommended that the Alaskan Peninsula, the Kodiak Island group just south of the Alas- kan Peninsula, that part of Alaska south of the Alaskan range west of 141 parallel longitude, and the islands of Chichagof and Admiralty, the principal range of this bear, be specially watched and the natives in this range be put on the same basis as the non-resident sportsman, instead of being given unlimited privileges without re- striction as to season or bag limit. “This would mean that the native and the resident Alaskan would be allowed to kill not more than two bears a year, and only in the open season, which is now from September 1 to the 20th of June following. This would furnish a record of the kill, put everyone under the regulation, and the seasonal bag limit could then be easily reduced to one bear if the situation so warranted.” Since this recommendation was made by the Senate’s special Committee acting under the Seventy -second Congress, an official govern- ment brown bear census has been completed on Admiralty Island, located in southeastern Alaska. The nearest point on the island is about 12 miles from Juneau, the capital of the territory. The island is 100 miles long, north and south, with varying width, averaging approximately 25 miles, Admiralty has an area of 1,664 square miles, is heavily timbered with dense forests of spruce and hemlock and an isolated mountain range. The census was made through a cooperative field trip by the Alaska Game Commission and the Alaska branch of the Forest Service. The num- ber of large brown bears and grizzlies on the island was estimated at about 900—about one bear to every 1% miles. These figures, according to government investigators, since they were taken on one of the best known “brown bear” islands in Alaska, refute conclusively the widely spread tales about the bears “being on the verge of extermination.” The conclusion of the Feder- al experts is: “In the huge reserves of Alaska not only are the bears thriving but they continue to range in undiminished numbers throughout the greater part of the territory." TELESCOPE Build your own powerful telescope and see the Craters on the Moon, the Rings of Saturn, Jupiter and its Moons, Spiral Nebulae and countless other wonders of the heavens. We fur- nish complete kit—nothing else to buy—at a remarkably low price. Anyone can do it—no special tools required. Same type instrument as the 100-inch Mt. Wilson telescope. Write for complete information. AMERICAN TELESCOPE CO., 4008 Addison St., Chicago, II. Re- 34 Thank You for Mentioning Modern Mechanix and Inventions for May W hen W riting to Advertisers

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Build This GYPSY Trailer for 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 —can be set up anywhere. N° 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 tor 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. Chassis of the trailer is built up out of the front axle unit of a junked car—almost any type will do. Only ordinary tools are required. Roof is of water- proof canvas. Bedsprings are contained in the pro- jecting balconies. Provision for running water and household equipment is made. 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, $ postpaid 1.00 Modern Mechanix and Inventions 929 S. Seventh St. Minneapolis, Minn. E Thank You for Mentioning Modern Mechanix and Inventions for May When Writing to Advertisers | | | STOP LEAKS STEAM—WA 'ER-GAS—OIL '$MOOTH-ON No. 1 stops leaks of water, steam, oil, gas and smoke. Makes a pressure-tight seal at joints, cracks and breaks in pipes, boilers, radiators, tanks, ovens, hot-air and smoke ducts, pails, etc. Tightens loose handles on tools, cutlery, push brooms, umbrellas. Makes stripped nuts, bolts and screws hold. Tightens loose locks, hinges, casters, hooks, stems, chair arms and legs, posts set in metal or concrete, etc. Stops leaks | in automobile radiators, hose connec- 5| tions, cracked water jackets and gear ^| cases, oil and gasoline lines, keeps nuts, lubricator connections, hub caps and wood screws from coming loose, makes headlight and dash supports tight and proof against rattle. Applied cold and holds in any metal, concrete, masonry, tile or wood. HOME am AUTO REPAIRS Making these repairs yourself avoids expense and delays and is easy if you follow instructions in the Smooth-On Repair Book which will be mailed on request. Get the booklet from us and Smooth-On No. 1 in T7-oz., 1-]b. or 5-lb. tins from any hardware store. | SMOOTH-ON MEG. CO., Dept. 69 574 Communipaw Ave. Jersey City, N. J. Write for FREE BOOK Success FOR YOU in PHOTOGRAPHY Thousands of money-making opportunities await trained photographers everywhere. Fascinating work. FREE BOOK tells how you ean quickly qualify at home or in our studios as OJ Motion Picture Cameraman and Projectlonist CJ Commercial, News, Portralt Photographer State which interests you—WRITE TODAY NEW YORK INSTITUTE OF PHOTOGRAPHY 10 W. 33rd St.. (Dent. 153) New York, N. Y. Fi N D GOL D With Guggenheim Gold Detectors NEVER FAILS Guaranteed to detect gold and silver anywhere. Used by Prospectors, Miners, Tourists and Treasure Hunters everywhere to locate lost jewelry, buried treasure, rich gold pockets and mines. Many recent fortunes mado by gold seekers. Sonora prospector located $2000 in gold nuggets. Send $1 for small size, $1.50 std. size, or $3 for professional size.in leather case, and directions. 10-day money refund guarantee. GUGGENHEIM EQUIPMENT COMPANY Dept. 30-E, 156 Montgomery St. San Francisco, Callf. HENLEY'S BOOK OF PROCESSES AND FOR- MULAS—10,000 money-making formulas, many of them trade secrets never before published. Price of 800 page book, $4 postpaid, from Modern Mechanix and Inventions, 529 S. Seventh Street, Minneapolis, Minn. PrintYourOwn Cards, Stationery, Advertising, labels, paper, circulars, tags, ete. Save money and time. Sold direct from factory only. Junlor Prese $6.80, Job Press, $11. Power $149. Do popular raised printing like en- graving with any of our presses. Print for Others, Big Profits. Pays for itself in & short time. Easy rules sent. Write tor free eatalog of outfits and all details. The Kelsey ¢o., K-98, Meriden, Conn. T 35

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5c coins stamped out of wood now circulate in Blaine, Wash. 36 Special camera keeps 3-dimen- sional portrait records. & SPOT NEWS of 9 In the World of Non-binding garters built right into the sock are the latest beon to men bothered with complaint of slipping-sockitis. Last word in streamlined cars is this German Maybach, built by the famous manufacturer of airship engines. It’s a 12-cyl- inder. Inside room is great because of utilization of run- ning-board space for seats. Modern Mechanix and

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the MONTH Science and Invention Special catapult for launching seaplanes is built lengthwise of the floating airport. Map showing where the floating ship island will be anchored on lane of south Atlantic air travel where regular passenger line : N . A is being established. /, /} Seaplanes are pulled aboard ship by derrick after they have oy i taxied up on a canvas drag whose lower edge floats just un- der the surface of the water and is supported by pontoons. German liner Westfalen which has just. passed tests to prove her efficiency as a mid-ocean base for seaplanes crossing the southern Atlantic. Note derrick at stern and the catapult rail. Inventions for May 31

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ap “Pilots Ride to “DEATH The current conflict between Japan and China has brought out an amazing tevelation of the methods by which Japanese pilots assure air bombs reaching their target by putting a man inside to steer them. Why? Read the reasons in this article, and you'll have a better understanding of Japanese psychology toward the machines of war. MAGINE yourself strapped within a hoi- - low chamber inside a huge air bomb, surrounded on all sides by high explosives. In front of you is an airplane type rudder which steers the tail unit of the bomb. Win- dows in the nose enable you to see ahead. You're loaded into the bomb, which is placed in its nest under the fuselage of a bombing. plane. The bomber takes off, soars above a target—-say, an ammunition dump of the enemy. Up above you, the pilot of the plane pulls a lever. Down you go, plunging toward the ground with terrific speed. You see that you aren’t going to strike the ammunition dump, but will land many yards to one side of it. So you twist the control rudder, swerving the bomb’s course. Success! The dump looms up directly below the windows of your bomb. And that is practically the end of things for you. i Sounds like the superheated. imagining of a Jules Verne, doesn’t it—the sort of absurdity that a sensible man would laugh off as being unheard of, an astounding, amusing impossibility? I It’s nothing of the sort. It's an actual fact of warfare, a method used by Japanese pilots who deem it an honor transcending all others to ride to glory for the mother country. They know that their memory and their families will be forever honored in their homeland. ën os Rumors of the flying bomb death ride have filtered out of the conflict now being waged by the Japanese and Chinese. Neces- sarily this information has been of a confi- dential, undercover nature, but not long ago it was given nation-wide publicity by a radio commentator on international affairs. Japanese and Machines To make the man-steered bomb a credi- ble actuality, an understanding of the pecu- liarities of the Japanese character is neces- sary. And some such understanding may sooner or later be forced upon the great powers of the world who are all too likely to become involved in the aggression of Japanese militarists in China, where the United States, Great Britain, France, Italy and Germany do much business. In the field of machinery the Japanese mind is at a peculiar disadvantage. They Where the U. S. government expedition is now conducting a survey of the Aleutian islands, looking toward the possibility of establishing weather station, air base, naval base and possible fortifications. Note the proximity of the islands to Japan and the great circle course of steamers. Planes are being taken. with which to make an aerial survey of the islands. 38 Modern. Mechanix and

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on e ying BOMBS > Ror a are able to turn out an exact copy of any mechanism that comes into their hands, but the type of mechanical imagination which went into its original creation—which, for want of a better term, is sometimes known as Yankee ingenuity—they are at a loss to duplicate. The simple truth of the matter is that a man is practically required to steer Japanese bombs to their mark because they haven’t been able to develop the bomb- sighting machinery which makes Uncle Sam’s flyers, for instance, so deadly in their accuracy. Peculiar Oriental Psychology As to why Japanese soldiers fight among themselves for the honor of being the bomb pilot who can look forward to being blown to certain oblivion, that’s a matter of psy- chology not so easy to understand. Patriot- ism rules the Japanese to an almost fanatical degree, and love of country is so bound up with religion—the emperor being regarded as an incarnate god—that to be blown up in a bomb to further the successes of Nip- pon becomes something to be desired above all things. When one understands the popularity that hara-kiri, a form of suicide by self- disembowelment, has had among the Jap- anese for centuries, the national willing- ness to dive to death in a bomb, or in any other way, becomes credible. Hara-kiri, as formerly practiced, was Riding to glory for the mother land, a Japanese pilot inside a bomb dropped from an airplane steers it to destruction because Japanese mechanics are unable to design: elaborate sighting devices which would assure reasonable accuracy. ‘Inventions for May 39

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Uncle Sam's Latest Bomber Is High-Speed Destructive Terror of the Skies NEW U.S, BOMBER _OLD' TYPE BOMBER — base = SPEED —— 200 M.P.H. SPEED—120 M.P.H ALL-METAL CONSTRUCTION (OOD RETRACTABLE LANDING GEAR FABRIC WINGS Top photo shows new U. S. bomber; lower picture is Curtiss bomber used by army up to now. Insert drawings show comparative performances. Superiority of the new design is evident. from windstream and makes for accurate shooting. compulsory upon a noble of the higher class who received a courteously phrased mes- sage from the mikado intimating that he must die for some offense of lawbreaking or disloyalty. The suicide, using a jeweled dagger customarily sent by the mikado for performing the act, proceeded in a pre- scribed ritual. Seated on a dais, surrounded by officials and friends, the suicide plunged the dagger into his stomach below the waist on the left side, drew it slowly across to the right, and turning it, gave a slight cut upward. This compulsory suicide has been abol- ished, but the idea has such a striking ap- peal for the Japanese imagination that some 1500 hara-kiris take place annually as a purely voluntary gesture. In the final analysis, the amazing thing is not that the Japanese should succeed in finding pilots for their man-bombs, for vol- 40 The revolving turret protects the gunner All-metal construction lessens danger of fire from incendiary bullets. unteers for such a mission of certain death can be found in any army in the world, but that such a weapon should be necessary. It simmers down to the fact, as hinted at above, that the Nipponese are conscious of their inferiority in developing new and fearful weapons of war, and are forced to rely on man-power. A country like the United States would approach the problem of directing bomb flight in an entirely different way. Some method of mechanical control of the bomb would be sought—in fact, the idea of con- trolling a bomb or gun shell by radio is already being worked on, as described in MopERN MECHANIX AND INVENTIONS some months ago. It will be seen that, entirely aside from making the sacrifice of a man’s life unnecessary, radio control of a bomb is much more accurate and less liable to error through the failure of the human Modern Mechanix and

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machine in a moment of critical nervous tension. Superiority of American enn oM brains over the Oriental variety is wel demonstrated in the newest United States army bombing plane, a photograph of which is reproduced in these pages. It is a monoplane of all-metal construction—no wood or fabric to catch fire from incen- diary bullets of the enemy—and is so well streamlined, with its landing gear pulled up under its belly, that it can do a top speed of 200 miles an hour, fully loaded with a two ton cargo of bombs. This is 80 miles an hour better than the speed of the Cur- tiss bomber, a biplane, previously used by the air corps. Features of U. S. Bomber A revolving turret to protect the gunner in the nose of the ship is another feature. It diverts the rush of air and makes accu- rate aiming much easier. At high speeds, the windstream is so powerful that, in an ordinary ship, it has a tendency to wrench a swivel mounted gun out of the gunner's control. In connection with the possible need of protecting our country from Pacific aggres- sion, the news that a government expedition has just left for an extensive survey of the Aleutian islands (which constitute the tip of the Alaskan peninsula) is important. À map, reproduced herewith, shows the ex- tremely important location of these islands in their relation to Japan and the Orient. Geologically, these islands are thought to be the sunken peaks of land that once con- nected the mainland with Asia. Siberia is but a stone's throw distant, and the north- ern islands of Japan not much farther away. Since, by a recent bill passed in Congress, the United States has relinquished control of the Philippine islands, we will have no Pacific base of importance other than Hawaii and Guam, which makes the Aleu- tian chain all the more important in the scheme of national protection. Strategic Importance of Islands Airplanes are being carried by the expe- dition and these will make a careful aerial survey of the islands. A weather observa- tion station will probably be established on Tanago or Adak island, and the best suited of the nearby islands will be chosen as a possible base for an airplane field. Harbor facilities will be carefully charted with a view to possible installation of a naval base for ships and submarines. Alaska, of course, is a United States possession which we are free to fortify as we may see fit. An incident of the World War which has just come to light illustrates the ingenuity of the western mind in the world of ma- chines. German engineers designed a mine fitted with clockwork which permitted the device to float in toward English shores when the tide was right. When the tide ebbed, the mine automatically sank to the bottom, where it waited the proper interval and then released itself again to float closer to the shore. The British were unable to figure out how the mines got there. Inventions for May Puppets Stage Shows for Children L Top picture, puppeteers manipulating strings; center pic- tures, two views of puppets in action; bottom photo, pup- pets with child on stage for comparison of size. EVEN years of experiment were required to bring to perfection the life-like pup- pets shown in the series of pictures aboye. They are the work of Blake Wagner, Holly- wood motion picture cameraman. He uses the puppets in giving shows. The same stunt has proved a money-maker for many men out of employment, who are able to arrange with departmentstoresto giveenter- tainments in their children's departments. Al

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NOVEL NEW MACHINES T mL U L L I N G T THE endless quest for cheap sources of E two proposals have recently been advanced which demand serious consider- ation, both for appeal to the imagination and the possibilities of practical operation. The high speed windmill shown on this page is the latest development of Volf's labor- atories in New York. The first of these power producing units will be in operation by May first. Three fans are provided so that one is always facing a wind current. The fans are geared to a gyro stabilizer which runs on inertia so that the fans will not run down in calm intervals between gusts of wind. A generator is driven by the geared shaft, producing current for storage batteries. In actual practice three or four small generators will probably be used, one or more of them being automatically cut out when wind velo- city falls below a certain point. Another idea, less close to realization than Volf’s windmill but involving natural phe- nomena just as dependable, partially owes its inception to the stratosphere balloon as- cents of Prof. Auguste Piccard. The extremes of temperature encountered by Piccard, in which the outside air was around 75 degrees below zero while interior temperatures of the gondola were around 100 degrees, makes possible the operation of a thermal engine as described in detail on opposite page. Search li CINE ; In circle, how three fans are geared to driveshaft in Volf windmill. At right, working model of the design. Cylindrical unit behind fans is a gyro stabilizer which assures smooth run- ning in gusty winds. 42 Modern Mechanix and

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“POWER from the SKIES Principle of operation of a thermal engine is simple. In this instance, alcohol or similar liquid with low freezing, high boiling point, is imprisoned in piping. Top chamber of gondola is painted black, to absorb sun’s rays (as was proved successful in Piccard gondola, shown in insert photograph). Lower chamber is aluminum finish, reflect- ing sunlight, consequently remaining at temperature of outside air, around 80 below zero at these heights. Liquid turns to steam in top chamber, passes through pipe which drives turbine generator, is condensed in cold chamber, and returned by pump driven by portion of electricity generated. Prof. Piccard himself expects that mysterious cosmic rays will some day be harnessed for power. This thermal power plant, anchored by captive balloon high above the clouds to operate through heat of sun and cold of atmosphere, is an idea based on sound physical laws, demonstrated in Piccard balloon ascent a year ago. Inventions for May 43

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Anti-Aircraft Machine Gunners Practice on Model Plane German gunners blazing away at cardboard plane towed across “sky” on cable. Speed is regulated by winding drum. Latest in High Speed Photography HOWN below is a remarkable photo demonstrating what happens when you shatter an electric light globe. What makes the study possible is an amazing new super-snapshot camera which records im- pressions more swiftly than the human eye. The snapshots are taken at the terrific speed of 4,200 a second, exposures ranging from one one-millionth to one five-hun- dred-thousandth of a second. The high speed camera was developed at the Massa- chusetts Institute of Technology. This photo, taken with high speed camera in one one-mil- lionth second, shows how glass flies when you smash globe. 44 ITH their fighting equipment drastical- ly restricted by Versailles Treaty, Ger- man military experts have devised an in- genious method for giving anti-aircraft machine gunners an opportunity to de- velop their marksmanship. As demonstrated in the photo at the left, a small cardboard plane is drawn across the sky on a cable, the speed being reduced to a scale commensurate with the reduced size of the midget plane. On the ground, accoutred as in war time, a machine gun crew blazes away, riddling the plane as effectively as its marksmanship will allow. Practice with this method, tests reveal, Soon develop the soldiers into crack shots. Handy Lamp Attaches Anywhere NEW hand lamp now on the market has a clever gripping device which makes it possible to attach the globe al- most anywhere, leaving both your hands free to do the work. It can be adjusted so that the lamp hangs perpendicular, regard- less of the angle of the gripping device. A wire guard protects the bulb against rough treatment. This handy lamp may be at- tached anywhere with the clamp on the socket base, leaving hands free to perform other tasks. Wire guard pro- tects against rough treatment. Diatoms Make Sea a Soup for Fish HE most important creatures of the sea are not the gigantic whales or the fero- cious sharks, but are tiny plantlets called diatoms, so small that more than a hun- dred of them can lie side by side on a pin- head but so numerous that they convert the surface water of the whole ocean into a kind of thin vegetable soup which then supports all the other sea creatures, even the whales and the sharks. Each living diatom contains a tiny oil droplet, constituting from one-fifth to one- half of the plantlet’s bulk. This oil is pro- duced, just as are olive oil and cotton- seed oil on land, by the chemical process called photosynthesis. The tiny sea plants absorb sunlight and use this energy to manufacture new chemical materials from water. ` Modern Mechanix and

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Novel Buoy Permits Swimmers to Sit or Walk on Water HEN Miss Marcelle Edwards. former “Follies” beauty, took her i-ital dip at Palm Springs, California, recently, she introduced a novel floating device which enabled her to sit comfortably on the sur- face of the pool or actually to walk through the water by moving her legs. The water walking device consists of an inflated bag shaped like a doughnut, as illustrated in the photo, and strapped to the back with a leather harness. Inflation is effected with an ordinary tire pump, or even a pair of hefty lungs. : When not in use the air can be exhaust- ed as in an auto or bike tire, so that the gadget can easily be transported. Ideal also for floating lazily in the sun-warmed water. Tires Piled Up 150 Feet High Sell Them Quickly T° ATTRACT attention, a Hollywood garage owner who had a large stock of used tires he wanted to dispose of stacked up a couple of hundred of them and put a life-like dum- my on the top. The stunt got results. While waiting to see if the stack would fall, an astonishingly large number of people bought tires, bringing the depression io an end as far as the tire dealer was concerned. The secret of the stacking lies in the telegraph pole running up through the cen- ter, thus holding the column vertical. In the accompanying photograph the dummy is seen atop the tires which were piled over 150 feet in height. Most spectators actually be- lieved the dummy was real; and wondered how he got there. There’s a hint in this spectacle for other tire deal- ers in like predicament. - This attention getting stunt—used tires piled up 150 feet high, surmounted by dummy—=solved depression for dealer. Inventions for May Here is fair bather at Palm Springs, Calif., wearing floats which permit her to sit on water or walk partly submerged. Colored Tires Match Your Car HE use of colored auto tires to harmonize with the body color scheme, an event long desired by many fastidious motorists, has been made possible by the develop- ments of a prominent tire manufacturer. Exhaustive ex- periments were required to pro- duce these tires because of the de- structive effect sun and weather have on color. The sidewall of the casing has a mot- tled effect, thus making many col- or combinations possible. The tread is so impreg- nated with the col- or pigments that color is never lost even after thou- sands of miles. Something new for motorists— colored tires to harmonize with body of your new automobile. The sides have mottled effect while the tread is solid color. 45

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Electric Shovel is cMechanical MONSTER Enormous size of this electric excavator may be realized by comparing with it the man pointed out by the arrow. Its huge shovel will pick up 18 cubic yards of dirt and deposit its load 200 feet away on top of a seven story building. Device Renews Typewriter Ribbon ACDELE device, which can be operat- A ed by any stenographer, is said to make new typewriter ribbons out of old ones, and to reduce the average wear of ribbons by about 80%. The device injects a solvent evenly throughout the old rib- bon and is rapidly applied by winding the ribbon from one reel to the other. The device is refilled with solvent from time to time as needed, and can also be used to renew ribbons on bookkeeping and add- ing machines. Typewriter, bookkeeping and adding machine ribbons are renewed by this new device which applies solvent to the cloth as demonstrated. Reduces average wear 80 per cent. 46 AEN monster in the mechanical world has made its appearance in the form of an electric excavation shovel of almost incredibly gigantic dimensions. Shown above, the shovel has a dipper that will scoop up 18 cubic yards of dirt at one sweep, and will dig enough in a 24-hour day to fill 7,500 motor trucks of 4 yards each. A seven-passenger car can be driven through the dipper with room to spare. The enormous reach of the shovel is illustrated in the fact that it can pick up a dipper full of earth, rotate, and dump it 200 feet away on the top of a seven- story building. Strange Facts About Explosions OW human senses may play their own- er false in emergencies is evidenced by the report of a British miner who hap- pened recently to be in the very middle of a mine explosion, yet survived and was conscious chiefly of a lot of coal dust in his mouth, without perceiving or remem- bering the blast of fire which burned him severely. Evidently the mental shock was so great that the burns were not felt until afterward. Only the strange experience of a mouth inexplicably full of coal dust was remembered. Modern Mechanix and

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Ear Gymnasium Exercises Diaphragm to Restore Hearing ESTORATION of hearing has been ac- complished in more than 300 cases with a new device producing controlled tonal vibrations. The “ear gymnasium,” or Aura- tone, as the device is called, is used to main- tain, over the various bands of frequencies in which the subject is hard of hearing, a volume at which a sensation can be per- ceived in the ear. Thus, inactive parts of the ear are aroused and re-educated, while hearing is strengthened. Tones are produced by an audio oscilla- tor generator. Advantages of the device are found in exercising those parts of the ear which are partially deaf to sound. Board Reproduces Football Game Spectators watching this scoreboard can follow football game play by play. Names of players are flashed on panels, while ball moves on grid according to original moves. N ingenious “grid-graph” foot ball score- board recently displayed at a Los An- geles inventor’s exhibit scores the games, and shows the personnel of each play by flashing lights as well as diagramming it in lights on a gridiron as the play is made. The board can be operated at any point by direct wire from the field to practically replay the game. Spectators at remote points can watch the actual motion of the ball on the field, which is shown by a light that indicates the moves of the pigskin. New Streets to Stop Traffic Jams UR antiquated system of street corners, inherited from the horse and buggy days, is blamed by a prominent traffic ex- pert for the majority of traffic accidents and delays. The ordinary type of level, right- angled crossing at the street corners do not have anything like the traffic capacity of the streets themselves; hence the conges- tions. Continuous movement of traffic would increase street capacity enormously. One proposed solution to the problem is two- Jevel crossings, such as is found on railroad lines. This would eliminate the stop-and-go system of traffic control which halts traffic all too often. Inventions for May Audio oscillator of the "Auratone" at right generates vibrations in phones to exercise insensitive diaphragm of ear and restore hearing to the deaf and partially deaf. Condemns "'Frills" in Education [RETO of public school systems to in- clude only a limited number of essen- tials and to leave out many of the “frills” now taught is advocated by the distin- guished South African educator, Professor H. B. Fantham. The only real educational essentials, Prof. Fantham believes, are read- ing, writing, arithmetic, the language of the country, a little history, some economic and human geography, biology, a brief out- line of other sciences, and some art. Planet Model Is Machine Marvel ONE of the most remarkable pieces of mechanism in the world is a working model of the sun, moon, and earth, which is on display in a famous planetarium. Shown below, the model duplicates with perfect fidelity the relative motions of the celestial bodies, reproducing the daily ro- tation of the earth and its daily revolution around the sun, the monthly revolution of the moon around the earth, and the sun’s rotation on its axis. Crank operates mech- anism. Relative motions of sun, earth and moon are reproduced on this amazing working model, which accurately predicts forthcoming eclipses, solar and lunar, twenty years ahead. 41

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Sluicing methods have not changed radically from early days. This photo, taken in the sixties near Central City, Colorado, shows a group of miners shoveling pay dirt into a sluice fundamentally identical to those in use today for hand operations. ‘When You've ound Gold— Epiror’s NOTE: This is the second of a series of articles on prospecting and recovery methods used in the new gold rush. The first article, which appeared in the April issue of Modern Mechanix and Inven- tions, described methods of locating paying gold deposits. yo have found gold! But the ground is not rich enough to make wages by hand panning. Still, if you could handle two yards in- stead of a half yard, you would make good wages. You keep on testing with the pan to see how much placer ground you have found and how rich it may be. As you do this you keep your pan clean, especially free from grease, and you have picked out a number of par- ticles of placer gold large enough to be handled with a fine pair of tweezers. The finer concentrates you keep separately to be refined or you have amalgamated them with “quick” (mercury) and will send them to some metallur- gist. You cannot risk the poi- son fumes of the mercury or you might do the refining of the amalgam yourself. There is one way you can do this without much danger and with small quantities of Dredges enable gold to be recovered at a profit from placers too poor to be worked by hand. Dirt as poor as 15 cents to the ton returns a handsome profit through use of dredges like this. Of course, deposit has to be of considerable extent. Capital can be interested to the extent of supplying dredges if the prospector can prove the productivity of his placer field „on the basis of test borings extending clear down to bedrock, Thousands of tons are handled per day in this manner. 48 Modern Mechanix and

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SLUICE 'er OUT ! 4 Catar 18 GAUGE SCREEN amalgam. By putting the amalgam GRAVEL IN inside a big raw potato, then bak- t. HOPPER OR & ing it in a fire outdoors, until well done, the mercury will be driven out into the potato pulp, leaving a | M59 ACEITE button of gold. Unwire the potato, WHiLe SEUICING; IS put away the gold, squeeze the mer-. cury out of the cooked potato by hand, using a.basin of water to help the separation. But all your panning has shown you must increase your efficiency, handle four to six times as much earth per man per day, if you are going to make wages. How to do it! The actual business of working placers ranges from the hand pan- ning of very rich, limited pockets to expensive dredges that cost sev- eral hundred thousand dollars, but operate profitably in low grade dirt. More recently there are *placer ma- chines" costing from $200 to $30,- «€ 000 that handle low ^ IRON PEG grade dirt to advan- US s ars, tage. hight off : 2 - FROM yousay you are : g OFF BASE not t in any suc bulk - handling machinery. But if you have lo- cated a big = * APRON WITH ER "SAG"POCKET l X tj SMALL ROCKER OR CRADLE Construction of a sluice and details of a rocker or cradle are given in the drawing. Gold amalgamated with mercury is recovered by put- ting inside a potato; heat will drive mercury into pulp, leav- & ing gold for recovery. Compare the gold rush of 1932, pictured in the photo above, with the photograph of the fifty-niners at work on the oppo- site page. Man power plus pay dirt plus a knowledge of the tricks of the trade, wins a living wage for hundreds of present-day prospectors who are combing gold-bearing territories. And there’s always possibility of scoring a ten-strike. When intending to try their luck in the field they should know how to identify gold when they have found it, and how to .recover it profitably when found—information which is all contained in this interesting series of articles. Inventions for May 49

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Sluice, Rocker and Long Tom Adapted to Different Operating Conditions placer running from 15e to 25c per ton, and cannot work it yourself by any small means, you might be able to interest some- one with capital to work that placer with a machine on shares, provided you had gone over that placer, surveying it to bed- rock in many spots, and could show that it was a machine proposition. So, do not turn aside from a placer that shows low values if that placer is big in extent. It may make you far more money than any small, rich placer you might find. But suppose, now, that we have found a few acres of fairly fat bench, overlooked in early days, running around $2 per yard. By handling two yards per day per man you can make grub money and a fair margin. An occasional nugget in the day’s clean-up will boost the total. All right, let’s go! First we must have water that can be ditched to your placer. If you have a “dry placer,” deposited by waters long since gone, you have a different and difficult Here is a.type of gold machine for medium-scale produc- tion which fits into the picture somewhere between the indi- vidual placer miner and the huge dredge outfit. It’s used in deposits too thin to warrant hand methods, not ex- tensive enough to justify a dredge. A Wa R WATER AND GRAVEL IN HERE Yo" TO I”DROP PER FOOT OF LENGTH d Ud e d TM VEXIO r - NN ae qe mE Oe Nee IAN Wat « zi VN SSNNAEX RUINED WITH Ví sHEET À IRON .] WATER,GRAVEL, AND fe EARTH MIXED HERE; fi. proposition. But with even a little water we can rig up an outfit to wash out our gold. Even a stream that runs only through early summer will help. Rough lumber, nails, common carpen- ter’s tools, and we are ready to build a sluice. The Riffle Principle The sluice is a straight-sided trough, with cleats or “riffles’ across the bottom. It is set at a grade sufficient to wash lighter gravel right through the trough while heavier mineral sinks, lodges back of a riffle, and is recovered. At the end of the day, clean-up time, riffles are spooned. out, after which. concentrates can be further washed in hand panning, or “quick” is used to produce an amalgam with finer gold. z Riffles are of 1x f's, or of angle iron, or poles, or rocks of an inch or two in diameter are packed in the bottom of the sluice. The thing required of the riffle is to form pockets holding back heavy miin- eral that sinks. To be effective there must be a *boil" created to prevent heavy sand packing in and filling the riffle, to pro- duce a washing motion that will sort gold into the bottom, but not enough to wash out finer gold. i The size of the gold particles, the type of earth washed, the volume of water, the type of rifles, -determines the grade from the upper to the lower end, and the amount of “boil’ required. If water is limited a steep slope will handle a greater amount of earth. Swift water spread out thin will catch fine gold better than deep water. The usual pitch of a sluice is from 15" to 1” per lineal foot. Water required for a sluice varies from 3,500 to 8,000 gal- a of water per cubic yard of earth han- ed. Materials of the Sluice The sluice is made of rough lumber, usually 1” x 12”, either in 6’ or 12’ lengths. Braces across the top of the trough keep it from spreading because of outward pres- sures. Riffles usually are 1”x1” or 1” x- 1%” cut in length to fit across the bottom of the box, held in place by nails driven through the sides of the sluice, but nails (Continued on page 135) pe 12” 0,» SCREEN IBGAUGE, ^-... l/;HoLES = Although sluices. are preferred if there is plenty of water handy, the “Long Tom,” construction of which is shown above, requires less water and can handle up to six yards per day with two men. Pretty fair wages on dollar gravel. 50 Modern Mechanix and

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Everest “PLANE SHas Unusual Equipment IAT? GENERATOR. DAIVEN GY MOTOR "HE formidable Mount Everest, which to this day stands unconquered by man, may soon behold the humiliating spectacle of a mere airplane sailing audaciously over its sky-piercing peak. The most interesting feature about the forthcoming attempt to surmount the 29,- 141 ft. peak of Everest is the specially equipped plane which will negotiate the 34,000-ft. altitude demanded in the feat. As illustrated above, a supercharged Bristol-Pegasus III engine will power the Houston-Westland plane. The air screw, driven through a reduction gear, is so de- signed that it will not exert full horse- power till a height of 13,000 feet is at- tained. Through this system, maximum power is available at all altitudes. An electrically operated and heated camera built into the floor of the observa- tion cockpit will record a 30-mile strip of the mountain country with the help of infra-red photography and clear mountain air. The rarified atmosphere and excessive cold encountered over Everest will neces- sitate the use of oxygen helmets and elec- Inventions for May FOLDING EAT. Here is equipment for plane which will seek to surmount Everest’s peak. Flight begins at Purneah, 116 miles away. trically heated flying suits. The pilot sits in an open cockpit as shown, while the ob- server inspects the mountain tops through a glass-covered port in the floor. Die Recuts Bruised Threads RUISED and battered threads can now be repaired quickly with a new slip-on re-threading die now being marketed. In use, the die is clamped around the dam- aged portion as illustrated below. A clean, smooth job is promised, with no cross threads, filing or spoiled parts. The dies resemble round die, cut in half. Damaged threads are repaired cleanly and quickly with this die, which clamps around battered section, as illustrated. 1 ci

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eMovies Submerge FAKE SEADROME Underside view shows the huge piles which supported the drome platform. Tide rising around these pillars made them appear on the picture to sink, submerging the drome. GERMAN film recently produced gave a film realization to the seadrome plans that have long been brewing in the minds of aeronautical engineers. Although the seadrome was a fake, it had all the features of the genuine article, and illustrated in a highly vivid manner the dangers to which a mid-ocean landing field might be subjected. A view of the seadrome looking offshore. When filmed further out the drome appears to be floating in mid-ocean. Note the passenger depot and crane for hauling up planes. The structure, shown in the photos above, was erected on the North Sea coast, with one side resting on the shore, while the other was supported by huge pillars sunk in the water a little offshore. Photo shots were all made in a seaward direc- tion, so that the drome appeared to be floating in mid-ocean. Shots made on the underside of the structure showed the giant pillars to further heighten the il- lusion. The scenario called for the submer- gence of the drome in the ocean when the pillars weakened. This was effected by taking an underside shot when the tide was rising, so that the giant columns ap- peared to sink down in the water, when in fact tbe waters were rising about the columns. The thrill of the picture was provided by the takeoff of a plane which brought to the scene a steamer that rescued the crew of the drome before it was engulfed. Fly Trap Plugs Into 110 Volts, Electrocutes All Flies Lighting on Wires NKNOWN inventors on the Pacific Coast were recently given an oppor- tunity to display their creations at a pat- ent exhibition in Los Angeles. One of the outstanding items was an electric fly catcher, shown in the photo at the right. In the center of the contraption is a can which is filled with bait for the un- wary flies, and for their accommodation they are provided with a landing field whose surface is a maze of wires. When the flies alight on this field to go for the bait, however, they make the biggest mis- take of their lives, for they get a shot of 110 volts through them that immediately renders them defunct. The trap may he set up anywhere a 110 volt outlet is accessible. While the trap will by no means exterminate the species, it. will rid a fair sized room of a nuisance. 52 Flies lighting on wires of trap are instantly electrocuted. Modern Mechanix and

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"Mineral Radio Survey" Machine Hunts for Pirate Gold ARLY legends of Los Angeles name a spot on a hill near Fort Moore as the place where treasure was buried by ban- dits and pirates several hundred years ago. Ray Martinez, of Los Angeles, claims he has in his possession an ancient sheepskin map which shows the position of the gold, and he has interested Rex McCleary, an en- gineer who has perfected a mineral radio survey machine that, it is claimed, will detect the presence of oil, water or min- erals. Preliminary tests with the treasure finder has lead the inventor to guarantee that gold will be found about 25 to 28 feet below the spot he will point out. No con- structional details of the apparatus are available. Shades for Auto Lights Cut Glare SHADE for automobile headlights re- cently invented greatly reduces glare and the percentage of accidents resulting therefrom. The shade is drawn out over a set of auxiliary lights by pressing a but- ton on the dash, the procedure being en- tirely automatic. The device is ideal for city driving Shade extending out over auxiliary set of headlights elimi- nates glare. Operated by special button on dash of car. While driving in cities main headlights are extinguished. Feed Birds From Window Trays IRD trays placed outside house win- dows as attractive resting and feeding places for bird visitors are suggested for amateur nature lovers. A convenient form is described as a shallow wooden box a foot wide by about a foot and a half long, fastened permanently to the window sill. Inside this box is a tight-fitting but re- movable tray of metallic zinc, which does not corrode in the weather and which makes the whole device easy to clean. On this zinc tray put a shallow dish of water for the birds and some suitable food, which may be bread crumbs, nuts and small meat bones. Half a cocoanut is an- other appreciated delicacy. Inventions for May Mining engineers searching for buried treasure on Los Angeles hill with mineral radio survey machine which pene- trates to depth of 28 feet to disclose presence of metal. Meter Analyzes Auto Carburetion UTOMOBILE owners can now effect a great saving in gas consumption of their cars, thanks to the invention of an analyzer which reveals at a glance wheth- er gas-air mixture is too lean or too rich. In the test, a hose connects to the ex- haust as demonstrated below. If the mix- ture is too lean, the pointer swings over to the lean side of the scale; if too rich, to the rich side. A correct mixture can be obtained by adjusting the carburetor while the analyzer is attached to the exhaust. Meter indicates whether gas-air mixture is too lean or too rich when hose is attached to exhaust of idling motor. 53

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A Complete COAL eMINE HEN the Rosénwald Museum of Science and Industry opens in Chicago May 1, visitors will be treated to a trip through a real, working coal mine, despite the fact that the nearest coal deposits are 200 miles away. They will descend in a real mine cage to a depth of 500 feet and take a trip of more than a mile on a real mine train through the workings. Or at least, such will be their impression. Actually the de- scent will be but 50 feet, to the museum's sub-basement, and the entire mine is packed into a space of less than 100 by 200 feet on two floors. s Visitors will descend in a real mine car: capable of holding 30 passengers. The car starts, stopping without the passengers re- alizing it while 450 feet of shaft wall, on The Rosenwald Museum, °% of Chicago, in which the model coal mine shown above is constructed, is shown in the upper photograph. The mine occu- pies a space 100 by 200 feet in the museum building. 54 an endless belt, flashes before their eyes to give the illusion of continuous descent. At the same time they feel the rush of cool mine air, chemically charged with the de- cayed vegetation odor of a mine, forced from a blower at the bottom of the shaft. Emerging, they watch an endless string of coal cars being unloaded. Illusion again! The “coal” is a cork imitation, wired to a screen on top of the cars which folds up and disappears at the touch of a button. Simultaneously a can of gravel, attached to a microphone and radio am- plifiers, is tipped into a metal hopper to produce the din of coal sliding down a chute. ‘The visitors get into two mine cars, ap- parently pulled by an electric locomotive. They round a corner, pass through a fire door, and roar down a stretch of track. Actually, the train stops while an endless belt, car- rying papier-mache reproduc- Modern Mechanix and

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Undercutter " : SiS tions of actual coal seams in | an Illinois mine flashes past them. Fan blowers, radio amplified sounds, and a sparking trolley wire over- head complete the illusion of motion. The mine train is one of three, each mounted on the same cable which circles around the mine. The locomotive does no hauling. While one train is being loaded, the other has stopped opposite the moving walls, while the third pauses alongside a low-vein cutting machine in action. In traveling alongside the moving walls, long, dimly-lighted galleries are seen leading off into the distance, where trains of loaded cars can be seen and heard rumbling over crossings. The trains, toy size, are less Inventions for: May Cars for passengers .fixedto endless belt |: ATI Dump platform cars contain card board. coal that folds up at touch of button. Ingenious methods by which the illusion of a 500-foot descent into a coal mine and a mile ride within its tunnels is created, are shown in the above drawing. Actually the model mine is compressed into a space 100x200 feet, and is two floors in depth. The use of radio with sound movie film for creating appropriate sounds, and of fan blowers to circulate through the tunnels air which is chemically treated to simulate the typical mine odor, are outstanding features of this most ingenious exhibit. The mine trains, actual size, ate not pulled by the electric locomotives, but are drawn around on an endless cable. than 15 feet away, and the sounds are radio amplified. A real battery of mine pumps will be seen in operation, pumping real water trickling down the gutters. The operators of the machines are also genuine, being union miners from southern Illinois. From the operating mine, visitors will pass through another type of mine, where the vein ascends on a slant, instead of be- ing laid flat. That is all that will be in operation this summer, but later the journey will con- tinue through lead, zinc, silver, gold, and diamond mines, finally ending up with a 1,200-foot ascent in another mine car (again compressed into 50 feet). f 59

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Shade f : | = Ginger B ale : Dispenser , Handy dispenser Shuttered sides and bottom of new lampshade punches hole in bottle permit adjustment for any degree of light. cap, utilizing gas pres- sure to deliver ginger ale. Turning bottle to left starts flow of liquid, turning to right closes the valve tightly again. Electric lunch cooker Breakfasts, lunches are prepared quickly by placing this electric cooker over dish in which edibles are contained, as demonstrated. New electric iron has button switch in forward part of handle, within easy reach. Dish washing brush has a soap receptacle in handle through which water is forced. Rich suds are sprayed out of bristles to cut grease. 56 Modern Mechanix and

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Mere twist of the jar unscrews cap when it is wedged into jaws of this new opener. Fastens onto wall with two screws and is ad- justable to take any size lid. Device is also convenient to put lids on tightly. Secured to door or wall, new type cabinet swings around completely out of the way to solve problem of limited storage space. Conserve coal by burning old magazines, which last for 25 minutes when suspend- ed from wires on grate rack as shown. Unbreakable rubber dishes and utensils are being made from “Plioform,” a rubber base product. Resists hot water, will not scratch. Inventions for May 57

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Getting “Personal with the This skin is from a grizzly which weighed 1500 Ibs.—some 500 Ibs. less than the brown bear attains. Size can be judged by the seven-column newspaper on which the skull rests. 58 A most remarkable surprise picture of an Alaskan brown bear, snapped at imminent risk to the photographer. No other living animal is a match for the brown bear in quickness and strength. Photo reproduced through courtesy of Nature magazine. In circle, at left, is shown measurement of bear tracks—seven inches across! by James Nevin Miller Have you always believed that the grizzly. is the biggest and most dangerous of all bears? If so, it will surprise you to learn that the grizzly averages about half the size of the great Alaskan Brown Bear. This article will upset a lot of your pre- vious notions about bears in general. HILE official Washington is all agog about whether the famous brown bear of Alaska, whose tremendous skin ranks among the most prized trophies in the world, is being exterminated by over- zealous hunters, almost countless stories are being told by bear experts concerning thrilling and almost unbelievable experi- ences of hunters, prospectors, guides, nat- uralists and government investigators who were unfortunate enough to meet some of these iungle monarchs unexpectedly. Modern Mechanix and

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Action! .One of the rarest of all brown bear photos, showing ‘a- ton’ of muscle and. bone making a bee - line toward a hunter who has aroused his anger. A tiger or’a lion would be helpléss in combat with this powerful. beast. The map at right shows habi- . tat of the Alaskan brown bear. Shaded sections indi- cate areas proposed as game reserve where hunting of such bears shall be restricted. Kodiak and Afog- nak are the famous islands of the Aleutian group that attract hunters of the brown bear. < gg The Alaskan brown bears form a group of gigantic animals peculiar to North America and limited to the coast and is- lands of Alaska from the head of Norton Sound to the Sitka Islands. ‘On Kodiak Is- land they attain weights sometimes ex- ceeding 2,000 pounds, and their skins have been mounted measuring 13% feet from tip of nose to tip of tail. They can be likened only to the great cave bears which were the haunting terror of primitive man- kind during the old stone age in Europe. In color the animals vary considerably —from a dull golden-yellowish shade to a dusky brown, becoming almost black in some species.: Some of the darker types are indistinguishable from the great grizz- lies with which in places they share the range, but the relatively shorter, thicker and more strongly-curved claws on the front feet are distinctive; moreover, the grizzlies average about half the size of the *brownies." Certaim species occupy open, rolling or -hilly:tundras and others live on the steep- est. and most rugged mountain slopes and Inventions for May

T S^ RES f ^ “a *"

“ve oisi d 5 A v ^ N € KENAI PENIN. J YT goo BE OGNAK |. à uu etu 1 wee Ds f CHICHAGOF ISLAND

Bears are good fishermen. This Alaskan Brownie is spearing salmon from a stream. Brown bears, incidentally, aren’t always brown—some of them are almost black in color. His temper is uncertain, no one being able to predict whether he'll charge a human being or turn tail and run. 59

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Lion Is Backwoods Amateur for Brute Strength; Brown Bear Holds Title BROWN BEAR -—2000 LBS GRIZZLY —1500 LBS What chance would a lion, the usual standard of animal ferocity, have with a bear? These size-diagrams tell their own story of their comparative killing power. This bear is just a baby of the species, but his skin will make an impressive rug. He tried to flee from his hunter, but, according to the stories that experts tell of bears, they are just as likely to attack as run. glaciers, rock slides and perpetual snow- banks. On the approach of winter all re- treat to dry locations, usually in the hills, where they dig dens in the earth, or seek other cover to which they retire to hiber- nate. Here the young, usually two or three in number, are born. They ordinarily emerge from hibernation in April or early ay. Opinions differ about the ferocity of the average brownie. Some experts claim he’ll never charge a human being unless wound- ed; while others insist he is dangerous to man at all times and will charge him en- tirely without intimidation. One thing, at least, seems certain—the Alaska bear has been endowed with a fabled ferocity—in a real sense he is the heavyweight cham- pion of the world. John W. Eddy, famous naturalist, points out: “In mortal combat, the giant bear, 60 LION 400 LBS Camp of U. S. ranger who helped make official census of the brown bears on Admiralty island. On this island, 100 miles long and 25 miles wide, some 900 bears were counted. with his great strength, weight and quick- ness, could defeat any other animal. Imag- ine a lion weighing 400 pounds (they sel- dom weigh so much) springing on the back of a bear weighing 1,600 pounds. It would be like an active child of 50 pounds undertaking to fight the champion heavy- weight pugilist weighing 200 pounds.” H. E. “Colonel” Revelle, one of the best known big-game guides on the Kenai Pen- insula, says: “No man living can tell what a brownie is going to do until he does it. In the early days on the Kenai Peninsula I hunted bear for the hide markets and I know a brownie is not afraid of anything that walks. He may not come at you, but its not because he's afraid of you, it's be- cause he doesn't like the smell of à human being. I’ve seen an old sow run away and leave. her cubs, and I’ve seen ’em come at you without any warning at all—just let out a roar and come a-running the minute they get your scent. “I remember one spring, my partner and I were hunting on the mountain back of where Seward now stands. We sighted a brownie up on the hill and made a sneak across to get within range. The bear was fast asleep in the tall grass and we got plenty close for a good shot. When we fired together that bear let out a roar like they all do when they’re hit, but we dropped her cold before she could move. (Continued on page 33) Modern Mechanix and

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Oddities of SCIENCE ^ 53 WATER CAN BEC COOLED TO 130° BELOW ZERO ..- B WITHOUT EREEZING. -Daniel R C. i Monteos! Quebec Wu FORCE OF en HIGH EXDLOSIVES IS so GREAT THAT A GREEN LEAF CAN DE IMPRINTED BETWEEN TWO SOLID BLOCKS OF STEEL BEFORE THE LEAF HAS ACHANCE TO FLATTEN. Earnest G Hayman, Crenby “OOK. Fre HEIGHTOEA mouNTAIN CAN DE MEASURED BY THE |-~* SWING OF A PENDULUM CLifFor Jackson, Fortine, Hice CAN BE MADE INA RED-HOT VESSEL. | ' Charles Cody, Jr, Faifimrore, Mat. ici OF THESE TWO WEIGHT UNITS WEIGHS i 3 THE ey SEEN THE : 2 Sonané—z 1000 L2. WEIGHT IS = * UICE THAN TEE TWO ames Weleh, FEA EXPLANATION OF ESL ODDITIES WILL BE FOUND ON PAGE 134 | SOOLP.WEIGHTS. Seattle Mash. Harold Aponenberser Cleveland, OHO, ONE DOLLAR vill be paid by Nic Sprank for oddities of science used on this page. 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 May 61

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Here Dr. Longley, head of the Tortugas biological station, prepares for a 55-ft. descent to sea bottom in 85-Ib. diver’s helmet. Undersea photos are taken with waterproof camera. TUE tentacles of an octopus crept stealth- ily out from an overhanging ledge and seized its unwary prey. A four-foot barracuda—“tiger of the sea”—with one lightning dart and a single quick snap of its powerful jaws cut a sil- „ver snapper in two. ` The stalks, branches and blossoms of plant-like structures that swayed every- where in profusion were in reality clever devices for catching, devouring, and as- similating living organisms. We watched this drama from a passage- way on the bottom of the sea off Dry Tor- tugas Islands that mark the extreme west- ern limit of the Florida Keys. The octopus paid no attention to us, if indeed he saw us at all, or possibly was repelled by our grotesque under-sea helmets and the tenu- ous air lines rising to the Anton Dohrn resting gently on the surface of the sea fifty feet overhead. The barracuda came near, nosed our garments, and slid away through the opalescent water. I We walked among the coral polyps and their cousins the anemones of every con- ceivable color—brown, violet, pink, white, yellow, purple, bright blue, vivid scarlet. Then my breath caught. All about us lay what appeared to be petrified human brains. I learned later that they were only “brain coral,” whose skeletal support re- 62 GREAKISH DRAMAS 0 Here’s a flashlight picture of a school of yellow goatfish and yellow grunts taken on sea bottom of Florida Keys. EAST ER E at D : peor ”A BIG PINE KEY eo é TORTUGAS, wee £ RoUrsAS ES Map of Florida Keys shows Dry Tortugas (extreme left), locale of extensive undersea exploration being conducted by Carnegie Institute Biological station under Dr. Longley. sembles the convolutions of the human brain. Troops of fishes that have changeable color patterns darted about among the coral formations. My companion unslung his water-proof camera, and with the aid of an electric flashlight took a few photo- graphs of schools of gray snappers, yellow goatfish, and yellow grunts. Dr. Longley, the scientist in charge of the marine biological station at Tortugas, has spent more than 3,000 hours in all on the bottom, watching and recording the ceaseless under-sea drama where the rule of the jungle, “kill or be killed,” predomi- nates, but where some extraordinary part- Modern Mechanix and

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the OCEAN “Bottom C. MORAN hs Remarkable undersea photo taken with flashlight bulb shows a school of gray snappers foraging for food. Freak of the deep is Tortugas crab which conceals itself beneath a bit of sponge, which in short while takes root and grows on crab's shell. Offensive taste of the sponge protects crab against enemies. Photos show crab with and without sponge. nerships among widely different types of organisms have also been formed. One of these partnerships is between a coral reef crab and certain anemones. The crab removes anemones from the rocks to which the latter adhere and carries them fully expanded in its first or clawed pair of legs. When the crab is attacked it de- fends itself by pushing -the anemones to- ward the assailant; as the anemones, in turn, capture food, the crab transfers part of it to its own mouth. - There are crabs that tear bits of living sponge off the rocks and hold them on their own shells until the sponges take Inventions for May A group of living coral polyps with fringe of ten- tacles on top for gathering food from the seawater. Dr. Pearse, Duke University biolo- gist, shown above as he sets out for day’s exploration on bottom of sea. root and begin to grow. Thereby the crabs secure effective. protection from their enemies, for the species of sponge which they thus utilize is dis- tasteful to many creatures as it is packed with flinty, needle-like bodies and gives off a disa- greeable odor. There is a vividly colored fish, about an inch and a half long, that is always hover- ing about the giant sea-anemone. Upon the slightest alarm it darts for the anemone “blossom” and disappears among its feath- ery tentacles. When danger passes the finny occupant emerges from.its protec- tive cover. It is said that this fish is so dependent upon the anemone that it dies if the two are permanently separated. Sucker fishes which attach themselves to larger fishes are common at Tortugas. (Continued on page 145) i 63

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Desperadoes Attempt Jail Break With Home-made Pistols These two crude pistols, made secretly in prison workshop, aided two desperadoes in attempted break at Folsom prison. Find 76,000 New Universes in Sky EVENTY-SIX thousand new universes, each of them presumably consisting of a gigantic cloud of stars millions of bil- lions of miles across, have been discovered in a recent photographic survey of the southern part of the heavens. Dr. Harlow Shapley estimates that the total number of these distant universes in all directions from the earth probably is at least 300,000. Smoke Trail Shows Bridge Route PECTATORS at the ground breaking ceremonies of the world’s largest sus- pension bridge which is soon to arise across the -famous Golden Gate in San Francisco, were shown very plainly where the bridge would be located. Following the bridge route, a navy plane sped across the water, emitting a streak of smoke, showing just where the bridge would be erected. The bridge is to cost $35,000,000 and will have one span over a mile long. ECHANICAL ingenuity serves many purposes, the latest and strangest be- ing its application to plans for a jailbreak at Folsom Prison, California. Two desperadoes, Marty Colson, in for murder, and Lloyd Sampsell, “Yachting” robber, worked for months with their own hands and prison tools making pistols for the big day. Finally, armed with these weapons, they made a desperate attempt at freedom, held up five employees in the administration building, and sent a mes- sage to summon the warden. . The warden got the jump on the crim- inals, however, and surrounded the prison with armed guards. Sampsell finally sur- rendered, but Colson turned his home- made pistol on himself and fired a home- made bullet into his heart. Ticket Printers for Busses Ticket printer is carried by conductor as shown here. ONDUCTORS on London omnibuses print their tickets nowadays right on the scene, just as they are needed for issu- ance to passengers. What makes this con- veniehce possible is the invention of a ticket printing device which may be car- ried by the conductor, as demonstrated in the photo above. i Laid down by navy plane in ground breaking ceremonies, trail of smoke across Golden Gate, San Francisco, showed spectators where the bridge would be erected. Costing over $35,000,000, the bridge has one span over mile in length. 64 Modern Mechanix and

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Shock Absorber Springs Make Chair More Comfortable NER rockerless porch or easy chair will be much more comfortable if you fit a couple of springs on the bottom, as illus- trated in the photo at the right. The springs used in this case were taken from old Ford Model T shock absorbers. They form a cushion that gives the seat a flexible, springy, riding effect, like the seat of an automobile. The legs of the chair may be shortened slightly if you like your chair to be of normal height. Bread Knife Cuts Slices Evenly FAIRLY heavy copper or brass strip soldered to the ends of the bread knife blade as illustrated below will make the cutting of even slices of bread a very simple task. Cut the strip to a width of about % in. and bend the ends so there is a space of % in. between the strip and the knife blade when it is attached. Solder or bolt the flat ends of the strip to the ends of the blade so that the slice of bread is guided by the space formed by the strip. Copper strip is shaped as illustrated here and soldered to the side of the blade, leaving a space of 3 of an inch, which will be the thickness of the slices of bread. Tire Cement Repairs Screen Holes OW that it’s about time to get out the window and porch screens, you’ll be wondering how you can patch up holes that have rusted in the wire. Here’s how. When the small holes are first noticed, spread over them a film of ordinary tire cement. This forms a thin film that will keep out flies and other insects. When you have time, however, it’s advisable to make a more permanent repair. When this time comes, simply wipe away the cement with a rag soaked in gasoline. The permanent patch is made with a small square of screen which is sewed over the hole with strong thread of wire from which the screen is made. Here's a formula for a good universal cement: Take gum arabic, 100 parts by weight; starch 75 parts; white sugar 21 parts; camphor 4 parts. Dissolve gum arabic in water, likewise the starch. Mix, add sugar and camphor. Boil on a water bath until paste is formed, which, on coat- ing, will thicken. Inventions for May Springs from shock absorbers out of old Model T Ford are fitted onto end of chair feet to increase sitting comfort. Grip to Tighten Faucet Handle AUGETS which turn very hard may be worked more easily by use of a grip cut from a 1 in. wooden block. Find the exact shape of the faucet handle and cut the pat- tern from the block with a coping or band Saw. Shape a handle on the block then tack a tin back to one side as il- lustrated. AI- most any leak- ing faucet may be tightened with this handy device so that it does not leak. If leaking is ex- cessive replace washers. With band saw cut out the board to shape of the faucet ‘handle. Tack tin on back to hold the handle in place. 65

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AT L,AST— A STARTLING new vehicle which may be used in the air as a fast, sturdy airplane, and on the ground as a speedy, comfortable two-passenger coupe car, will shortly be available to aviation enthusiasts. The craft is really a streamlined mid-wing monoplane of 30-foot wing span, propelled by a 125- horsepower air cooled motor of regulation aircraft type. For ground use the ship may be quickly converted into a stream- line car, simply by removing the wings and the rear end of the fuselage, leaving the closed cabin body resting on its three wheels, ready to drive through the streets. This transformation occupies about 20 minutes, by means of quickly detachable joints. . "The development of the “Ascender,” as the new ship is called, has taken many months of painstaking work in the selfsame Engineering Department which produced the fastest airplane in the world, Doolittle's “Flying Silo” which set a new world’s rec- ord of 296 m.p.h. at the Cleveland air races last fall. The first Ascender has already been built and flown enough to prove itself a most unusual craft both in the air and on the ground. Control of this craft, in the air and on The convertible airplane-auto has been designed by the makers of this famous Gee-Bee type sport- plane which won the Cleveland ait races last summer at 296 mph. i Brakes on aH. Rattan individua Sprang. ~y a Convertible the ground, is by an automobile type steer- ing wheel, a foot accelerator, and hand and foot operated brakes which act on all three wheels. While on the ground the ship rests on a three wheel landing gear, each wheel of which is equipped with internal brake and hydraulic shock absorber, as well as a large airwheel tire. The front wheel is steerable with the rudder of the ship, so that when the pilot moves the steering wheel to right or left, either on the ground or in the air, he guides the direction of his craft as he would a motor car. On the takeoff there is no necessity of getting the tail up and balancing on two wheels while steering the ship down the runway by means of a rudder bar, as one is obliged to do in piloting the ordinary airplane. In this new craft, one merely sits behind the wheel, opens the throttle, and drives the ship down the field or runway as.one would a car, with no possibility of “nosing over" even if brakes are applied suddenly, or from obstructions such as bumps, ditches, or soft spots. When suffi- cient speed has been attained the driver has merely to pull the wheel slightly toward him, whereupon the front whecl leaves the ground. and the ship “takes the air.” Landing the Ascender is a simpler task than in the ordinary. airplane. It is no. longer necessary for the pilot to judge his speed. and distance so that the ship will stop flying directly over the spot in the field where he wishes to land. With this craft, he need merely throttle the engine, point the nose down until the ship assumes a normal glide toward the field and set the ship onto the ground at a speed much greater than is safely possible in the ordi- nary airplane. As soon as the two rear wheels touch the ground, the front one is forced down, and brakes may be immedi- ately applied to bring the ship to a smooth stop. . — Visibility an The airplane is made ready for street use in 20 minutes by removing the wings and tail unit, easily detachable. Note the location of motor where it serves equally well for ground or air use. Angle of visibility is exceptionally broad. 66 Modern Mechanix and

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AUTO-PLANE ^ *Xopecon Rudder end front. wheel synchronized Two views of the “Ascender,” showing appear- ance in flight, and method of converting into an automobile. On the ground, a wire screen is usually employed around the propeller as a safeguard, though the arc of the blade is well within the confines of the car, Inventions for May 67

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Mike and Speaker on Phone Make Talk More Convenient New telephone mike and loudspeaker which amplifies in- coming and outgoing veice, eliminating necessity of holding transmitter to face when speaking or listening to conversation. Smoke Cuts Daylight 14 Per Cent porre per cent of a year's daylight in the city of Baltimore, Maryland, is thrown away by allowing smoke to get into the city's air, according to a Public Health survey recently conducted. To make the measurements, one photo- electric cell sensitive to light was set up on a building inside the city and con- nected with electric apparatus to re- cord the illumination minute by minute throughout the day. The conclusion was that city smoke causes very substantial losses of daylight and boosts light bills. TUE latest gadget for attachment to your telephone is an amplifier and loud- speaker which permits you to speak and listen without holding the transmitter up to your face. As shown in the photo at the left, the transmitter-receiver piece is hung on a special device which feeds into an ampli- fier that boosts both the incoming and out- coming voice. The former issues from a loudspeaker, while the latter is picked up by a super-sensitive microphone. Dialing is accomplished in the usual manner. The device is the invention of Hans Schmidt, a Berlin Engineer, who labored for five years on the development of his creation. Radio Modernizes the Old Hayrake que old hayrake has gone modern, and is now on par with the automobile. Take a look at the photo below and see what happened when a young fellow with a radio bee in his bonnet took it upon him- self to modernize the rake. The installation of the radio was effect- ed when a young lady from the city volun- teered to help rake the timothy while on her vacation at a Butler, New Jersey, farm. To keep her entertained, the farmer’s 12- year-old son fastened his home-made radio receiver to the rake and wound a loop an- tenna on a couple of sticks. The signals came in clear and strong over the head phones during working hours. The old fashioned hayrake has been modernized by installation of a radio to keep young lady city vacationer from being bored while she assists Farmer Jones in harvesting his crop of timothy. Note the loop antenna wound on the cross piece. 68 Modern Mechanix and

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Oxygen Chamber Taken to Dying Mayor Cermak by Plane C which developed in the lungs of Mayor Cermak of Chicago after he had been shot in Miami necessi- tated the administration of oxygen in a hurry. Unfortunately there was no equip- ment for this in Miami, so an oxygen tent had to be rushed from New York, packed in the passenger compartment of a plane as illustrated at the right. The feat was a marvel of aerial medical rescue. The tent arrived and was set into operation immediately, but gangrene later developed in the Chicago mayor's lung and shortly after he died. Radio Looks Like Couple of Books New radio has external appear- ance of sumptu- ously bound book, but opens up disclosing tun- ing dials and loudspeaker. Ac- curate idea of size may be gained by comparing the cabinet with the comely young lady in the photo. Ideal. for small zpartments. NEW radio receiver now on the mar- ket has the appearance of a pair of gorgeously bound books, as shown above. One lid opens up to give access to the tuning and volume knobs and the loud speaker. Face Harness for Miar s Beauty NEW facial harness now on the market lays claim to the ability to im- prove milady's beauty. How the device is worn ^ is illustrated in the photo at the left. Sagging chins are lifted and unbecoming wrinkles are smoothed out around the lips, cheeks and fore- head, manufac- turers claim. It is worn over- night, removed in morning. Strap smooths wrinkles, lifts chin. Inventions for May Oxygen equipment employed in attempts to save life of Mayor Cermak is packed in plane for shipment to Miami. Hospital Model Wins Gold Medal MASTERPIECE of the modelmaker’s art is the prize-winner of the 48th an- nual exhibit of the architectural league held recently in New York. Patterned from the New York hospital, the model, shown below, was the handiwork of a prominent Boston architectural firm, and won the gold medal for the orderly ar- rangement of the parts, for the excellence of the plan and the originality of design. Model shrubbery and trees further height- en the illusion. Model of New York hospital which was awarded gold metal in 48th annual exhibit of the architectural league. Stars Say This Is Year 1940 STRONOMICAL reasons for regarding this year as really 1940 instead of 1933 are presented by a German professor. Since historians admit that the exact date of Christ’s birth is unknown, the professor believes that his calculations, made from star data and biblical history, show the early winter of B. C. 7 the most probable date, so that the present year really is the 1940th after the birth of Christ instead of the 1933rd. 69

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Looking down on the mighty Yanztze, 1500 miles up- stream from Nanking. The prow of a British gunboat is seen in the foreground. The patrol is carried into the rich province of Szechwan, which has three-fourths the popu- lation of the United States. DO Dee OPERATING BASE OF AMERICAN GUNBOATS The beginning of the tremendous gorges of the Yangtze— noted for their dangers because of the swift rise and fall of the waters. A French gunboat was once left stranded 24-ft. above the river when waters fell that distance in a day. HILE riding through an almost endless succession of dangerous rapids, whirl- pools and currents in the Yangtze River, about 160 miles above Hankow, a mer- chant vessel operated by an American, named Captain Baker, suddenly went aground. It was night-time and a stone’s throw away could be dimly seen the craggy outlines of the shore. Nine times out of ten such an accident results in a bandit attack in this remote section of China. But hardly had the American given the order to his Chinese crew to arm themselves when things be- gan to happen. Not a single warning sound was heard and yet, within five minutes’ 70 Modern Mechanix and

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with U. S. by JOHN CLOVELLY Seven Yankee gunboats, patrolling the Yangtze river in conjunction with those of other nations, wage constant war against the bandits who infest this dis- trict which boasts one-third of the world's population. Little known activi- ties of this romantic branch of the for- eign service are described in this article. time, every coolie had been disarmed and bound by as villainous a gang of cut- throats as Baker had ever seen. Armed with sawed-off shotguns and wearing filthy rags, they looked as if they would commit murder for a dollar. However, their leader calmly announced that he would release the American upon receipt of two million dollars! Of course he did not make good on this fantastic de- mand, but his thugs seized Baker's boat containing perhaps $10,000 worth of car- go, and kept him prisoner for three months. At which time, thanks to friends, Baker raised a couple of thousand dol- Jars and was freed. Such instances happen again and again in the region of China’s mightiest river, which rises in the snow-capped mountains of Tibet and winds its way irregularly in a generally seaward direction for nearly three thousands miles to the ocean, empty- ing into the Yellow Sea a few miles from Shanghai. Small wonder, what with trade trans- actions such a tremendous gamble and human life a thing to be sneered at, that the gunboats of our Navy, Great Britain, France, Italy and Japan, regularly patrol the length of the Yangtze for nearly 1,700 miles, a distance as great as that from the BASE MONOCRAC Inventions for May U. S. tar watching a junk suspected of being one of a pirate group. Construction of the junk is typical; sails ate of bamboo matting. Note the control ropes of the sail. mouth of the Mississippi to Hudson Bay, Canada. The American patrol force consists of seven regular gunboats and, according to the seriousness of the emergency, any one of four “spare” gunboats. Each vessel carries three to four ship’s officers, one ‘doctor, and a crew of about 50 enlisted men. The boats are distributed through- out the Yangtze region as follows: At Hankow, 600 miles up the river, is the regular operations base for the Luzon, Graphic presentation of the perils which beset transportation of the Yangtze is given in the drawing herewith. Piracy became widespread -fol- |i lowing the opening of the upper river to steam- boats.

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Special Gun Swivels Enable Naval Marksmen to Repel Sudden Attack Note the peculiar gun swivels. They permit Navy tars to swing guns in a wide angle, always in firing position. flagship of the force, under command of Rear Admiral Yancey S. Williams, besides the gunboats USS Palos, Tutuila and Cahu; 500 miles up the river is the base for the gunboat, Panay, at Mowangtsui; at Ichang, 1,000 miles up the: Yangtze, is the gunboat Monocacy; and at Chungking, 1,500 miles up the river, is the gunboat, Guam. At Nanking, 150 miles up the Yangtze, no reg- ular patrol boats operate, but in emer- gency cases any one of the following seagoing gunboats is utilized: either the Fulton, the Asheville, the Tulsa or the Sacramento. The British maintain about 12 gunboats with similar personnel and procedure as the Americans; the Japs have about the same number; the French, three boats, and the Italians, one. Untold millions of dollars worth of foreign capital are tied up in industries located in the Yangtze region patrolled, which region, by the way, contains about a third of the world's entire population. The city of Hanyang, the Pittsburgh of China, with its towering steel mills, ad- joins Hankow, but is separated from it by the Han River and diagonally across the Yangtze on the south bank eight miles away is Wuchung; geographically these three cities are not unlike Manhattan, Brooklyn and Jersey City. That romance and adventure are not alone the lot of those who *go down to the sea in ships," but also of those who go up the Yangtze in gunboats, is more readily understood when the nature of their tasks is better known. Well advertised have been the Volga boatmen, famous in Russian lore. But 72 U. S. sailors fraterniz- ing with crew of junk, who are as likely as not to be pirates. Japanese gunboat used in Yangtze patrol. Great Britain, France and Italy also cooperate in defending the river. when one learns of the endless toil of the Chinese in “tracking” junks throughout the countless years in navigating that part of the Yangtze River known as the “gorges,” more than a thousand miles up- stream, one wonders how indistinct is the line which divides man and beast. From Ichang, the head of navigation for moderate draft steamers, 1,000 miles up the river, and 400 miles above Hankow, which is the upstream port for ocean- going steamers, the river enters the famous Ichang gorges—a succession of dangerous rapids, whirlpools and currents. From Ichang to Chungking, a city of 300,000, the river port of the rich province of Szech- wan, the distance is 358 miles. The stretch from Ichang to Wanhsien, at the upper gorges, has more than its share of “human interest.” The American shallow draft gunboats, Palos and Monocacy, not only negotiate these dangerous waters year in and year out, but proceed 200 miles further up- stream from Chungking to Suifu, at the confluence of the Yangtze and Min Rivers, (Continued on page 143) Modern Mechanix and

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*Disc-shaped ‘Raft Has Airship “Ancestry Frame of the disc-shaped boat is section from dura- lumin airship girder reinforced with smaller ring of duralumin tubing and covered with balloon cloth. Such a craft may prove useful as life rafts on airships. NOVEL disc-shaped type of boat de- veloped by an Akron, Ohio, inventor is a direct descendant of the Akron and Macon. As shown above, the unique craft has a ring-shaped frame made from a duralumin airship girder section, and re- inforced with a smaller ring bent from ;duralumin tubing. This framework is covered with bal- loon cloth like that used in blimp envel- opes. The completed craft is shaped like a thin drum or flattened bubble. From this boat was developed several other types similar in construction. One, a collapsible form that can be carried about in an airplane cockpit or motor car, has a ring of rubber and fabric tubing that can be inflated with a tire pump til! it is rigid as metal. The inventor believes craft of this type can be utilized as life rafts on large airships. Why Flies Prefer White to Black ESTAURANT managers who want house flies to keep off their tables should use colored table cloths instead of white ones and people who want house flies to avoid them should wear dark clothes instead of light, according to a re- port given to the American Physical So- ciety. What attracts insects to certain fabrics and repels them from others is believed to be warmth. The lighter colors and shinier surfaces apparently impress the fly’s tiny brain as being like sunlight. Inventions for May Fog Compass Cuts Navigation Peril OGS, one of the deadliest menaces of the sea, may no longer hold any terror for navigators, thanks to the development of a new type of compass which indicates the direction of an approaching vessel. The heart of the compass is a cathode ray tube on whose screen plays a pencil of light pointing out the danger angle. No information is given, but the tube pre- sumably operates in conjunction with a radio compass. The apparatus fits into the cabinet shown below, only the meter panel and the screen of the cathode ray being ex- posed during the direction-finding pro- cedure. Pencil point of light on screen of cathode ray tube indicates direction of ship approaching in fog, eliminating hazards. T3

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New HRILLS from Greak PILLS! Thrills! Smashups! Constant danger. Daredevil drivers strapped in odd looking, speeding cars, bouncing a huge ball about the race track. Spills? Sure there's one! Dust clouds rise as a little car does a crashing “barrel- roll.” Then another, farther up the track, fairly leaps into space as it turns over. The air about the grandstand has the tainted odor of burning rubber from spin- ning wheels—wheels spinning first back and then forward. Cars skid, slide about, swap ends like a wild bucking broncho. Spectators at auto ball games are treated to all manner of freak accidents. Here a machine is seen climbing an opponent in furious clash. Spills like this are common. Note how car rolls over on the sturdy hoop built onto stern and bow of the machine, by ED HARLAN GIBSON Another crash. A breath-taking spill. Wheels smash to splinters. For an instant the driver is hidden from the spectators’ view. The driver! He’s killed? Smashed? No! There he is under the car, hanging in his safety belt with 1,600 pounds of iron and steel above him. Those who are near can smell spilled gasoline. An oil spattered face smiles out at the spectators. Maybe he is bruised and injured, but still the driver smiles. It's. a game he is playing and he loves the dan- gers it involves. Game of Hairbreadth Escapes The roaring motor now above him is barking out a sharp, angry exhaust. The smell of gasoline becomes stronger. From his upside-down position the driver can watch the gasoline drip uncomfortably close to the red-hot manifold. Just a few drops landing directly upon it and instant- ly flames will be lapping at his feet, scorching his hands and face. ‘In the nick of time attendants tip the car back upon its wheels. . . The game goes on. More spills and hair- breadth escapes. Contenders fighting with cars for scores and, above all, aiming to give their spectators a thrill A startling novelty; better than auto racing. It is the Gibson troupe in action. The game is auto ball. The place? Any county or state fair that has contracted with the players to give their public a really thrill- ing attraction—a novelty that is different. There are six specially built cars in the outfit. Four are used in each game, leav- ing two in reserve to use when wheels or other parts are broken. The object of the game is similar to that of football. One team endeavors to push the large ball through the opposite goal and, above all, to give the spectators unusual entertain- ment while doing so. . The ball used is also especially made. It is four feet high when in- In the heat of the battle. Two machines pursuing the ball have just clashed, resulting in a spill for both. In the Auto Ball games, which are staged by intrepid drivers at country fairs, four vars specially built to withstand heavy punish- ment, take part, two machines being held on sidelines for emergency use. Object of the game is similar to football. 74 Modern Mechanix and

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SPILLS of AUTO “BALL flated. Six plys of rubber and fabric are used in its construction which resembles that of an automobile tire. It weighs ap- proximately seventy - five pounds. Many times these cars, weighing close to sixteen hundred pounds, are driven completely over the top of the ball without puncturing it. Again it is bounced ten to twenty feet into the air and well over the opponent’s car. This is called a kickoff. In the course of a game accidents are constantly expected and taken merely as a matter of course. The large ball, sailing through the air, has often caught a driver unawares, knocking him completely un- conscious. Again, striking the steering wheel, the ball has smashed it between the hands of the driver. Fire Most Deadly Menace Fire is another hazard to contend with. Running wide open, the motors soon be- come red-hot. Then just a few drops of gasoline falling from the carburetor onto the red-hot manifold, while the car is up- ‘side down, will instantly ignite it. Breath- less moments follow. The attendant’s first thought is of the driver. With flames already spreading about the oil-covered machine, they un- strap him. This he cannot do un- assisted because of his weight hanging in the belt. Airplane safety belts have been tried. The quick way of hooking them was handy; too handy, for the jarring and jolt- ing of the body unhooked them during the game. Fire in a night game is a spectacular sight and women in the grandstand have even fainted watching the flames enveloping the car. Thus far the driver has been removed invariably unharmed in all cases. Typical action shot here shows one contestant doing a “barrel roll,” while opponent maneuvers into position to give the ball a sock towards his goal. When in upside down position, driver’s life is greatly endangered - by gas dripping on overheated manifold. The motor is kept running always. Inventions for May Driver is held in seat by heavy leather belt. Experience has taught the drivers the knack of keeping their motors running in all positions, be it upside down or how. These drivers in auto ball claim a record of their own for spills, which in sport par- lance means the complete overturning of the cars. In a short game of five minutes of play as many as fifteen spills have been made. This is action in the raw. The grand- stand reaction is deafening applause as only a thrill loving satisfied crowd can give. An auto ball car stripped for action. Speedster body has reinforced frames, with steel hoops on front and rear. Made of six plys of rubber and fabric, the ball is four feet in diameter, weighing 75 pounds inflated. 75

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1000 ‘WAYS to CAKE a Silverware Rebufiing Regardless of how careful the housewife is, her silverware will gradually become scratched. .The fellow in the neighborhood with a small buffing outfit and a stick of plater’s rouge can be of great help and earn himself a dollar or two at the same time. Such ware does not need to be re-plated. As a matter of fact, re-plating will not remove the scratches—only buffing will do that. One man who makes upwards of $5 a day in this way, solicits business on a piecework basis, charging three cents each for knives and forks, more for pitchers and plates. He finds that much of his business comes from word of mouth advertising of those pleased with his work. The only way to restore scratched silverware to new condition is to re-buff it with the equipment shown above. Empty Store Windows A young Canadian is making a nice living out of empty stores! He lives in a suburban district of some 100 stores, a dozen or more of which are vacant. He acts as agent for the rental of those vacant store windows, finding that the landlords are invariably glad to accept any small sum in the way of revenue. Users of billboard space are good prospects for the rental of windows for displays; public utility companies, tobacco manufacturers, and owners of adjacent stores who wish to extend their display space, are also good customers. The young man keeps the windows clean, charging a monthly rental, and picks up additional income from setting up displays and doing the window trimming. Conducting a Doll “Hospital” For more than seven years an elderly woman has kept young and made a living as a specialist in repairing worn or broken dolls. Such handicraft as might be used in mending pottery, painting china, arranging hair and sewing dresses makes up the unique qualification of the doll doctor. Charges are based on the time and material required on each “case.” The testimony of a customer that “our doll means more to 76 my little girl than you could imagine” re- minds one that business built on simple sentiment is none the less real business. One factor that makes many sales is that the human hair of any member of a family can be made into a doll wig and thus kept as a souvenir of sentiment. The doll hos- pita) is also an agency for the sale of new dolls. New Income for Radio Men Thousands of readers of this magazine are rather proficient in radio and could very well profit by the experience of a young Buffalo, N. Y. repairman who, with things so quiet recently, got several big contracts from the larger music teachers of the town. He thought it would be a fine idea if he sold those teachers of voice cul- ture a recording outfit so that their pupils could correct their mistakes by listening to their own voices. After each lesson the pupil could sing a number that would be recorded and then take the small, inexpen- sive record home to let the family hear it. Other teachers flocked to have similar sys- tems installed and several thousand dollars worth of business was developed within a few months. It was the type of installation that could be handled by any good radio experimenter. Electrice Gas Stove Lighters ‘If a chap wants to go to some of the automobile junk yards today he will find that he will be able to buy all of the old Ford ignition coils that he can carry home for ten cents apiece. With two dry cells (of the small type that may now be purchased in the chain stores for ten cents apiece) these old coils make an excellent source of high potential for lighting gas stoves. The only other thing that is needed is a high potential electrode that can easily be made in the home shop. We still have in use many thousands of gas stoves that have to be light- ed by matches and each user of such a stove is a good prospect for such an instal- ation that may be made very profitably for about two dollars. An electric gas stove lighter, operated by Ford ignition coil and dry cells, is welcomed by many housewives. Modern Mechanix and

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LIVING .^ PAINT BACK WITH BLACK ENAMAL Custom Built “Coasters” _A California man got his big idea while replacing a broken window pane in his house. Out of work for some months, the idea occurred to him that the glass could be used for making *coasters"—which, if you have never heard of them, are small plates on which wet glasses are set to avoid marring the surface of a varnished table. Scraps of window glass, cans of auto enamel, a glass cutter, brushes, sand stone and felt are all the equipment required. The steps of manufacture are well shown in the illustration above. Any magazine drawing which lends itself well to silhou- ette can be used. The outline is painted in black enamel, and after it is dry colored backgrounds painted over it. Felt or velvet is then glued to the base to prevent scratch- ing furniture, and the edges of the glass beveled off on a small grinding wheel. The originator of this idea finds that he can secure enough orders in one day’s solicita- tion to keep his factory busy for a week. Glass can be salvaged from broken panes. Neighborhood Small Stock Butcher An unemployed man, seeking to “earn his eats” by odd jobs around produce mar- kets and grocery stores, discovered the need for a small stock butcher at these places. The dealers, preoccupied by the many details of the day’s business, are glad to turn over the task of dressing poultry and rabbits to this man. With only slight experience on farm and game fields he soon became rapid and skillful in dressing these meats to the satisfaction of the customers. The larger part of the difference in price Inventions for May Continuing the presentation of a series of articles on money-making ideas which have been proved out in practice. Steps in making coasters: Sil- houette design is traced, colors applied, coat of enamel painted on, felt glued to back, and edges beveled off. BEVEL EDGES OF GLASS between live stock purchases and dressed meat purchases goes to him as his fee. There are two side-lines to this job that bring additional profits: making quick deliveries for the dealers, and killing and dressing poultry for housewives who find such a task far from their liking. Now the new special- ty butcher serves three dealers; he is pul- ling through the dark days with a moderate livelihood and he is laying the foundation for his own poultry and rabbit market that he has planned to start. Spring Housecleaning Opportunities With the spring season for housecleaning under way, the man who has a few pieces of household equipment which he can throw into his car will find his services welcomed by many housewives. A vacuum cleaner with attachments for cleaning mat- tresses, mouldings and baseboards, a carpet beater to accommodate the woman who still prefers to have her rugs taken outdoors and beaten, a chamois and window clean- ing materials, floor waxer and polisher and a good furniture polish, will bring many an hour’s work. 77

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Tumblers From Bottles Old bottles accumulate around every home in such quantities as to become a nuisance. Seizing upon this fact, a couple of enterprising men set up in partnership in the business of custom-building old bottles into fancy tumblers with mono- grams or other designs etched into them. Their success is attested to by the above photo, which shows the outfit set up in a store window. The customer supplies the bottles, usually of colored glass, and of uniform size. The partners cut off the bottle neck and smooth down the edge with a grinder. Etching is done either by a sandblast method or by the use of hydro- fluoric acid. Fancy prices are obtained with ease, the usual charge being $4.50 for a half dozen tumblers. Bird House Reproductions When a Springfield, Ill, sign painter was hit by the depression, he turned to constructing bird houses, featuring a wren house which was a miniature of Abraham Lincoln's Springfield home. It found a ready sale locally and elsewhere. The same idea can be carried out in any com- munity, using well-known local buildings. Paint Brush and Paper From Texas comes this suggestion, proved out by a man fairly handy with a show card brush: He bought a quantity of paper scrap trimmings from a print- ing office and made up a few sample signs, such as “Sugar—1l10 lbs. 55 cents," etc., suitable for display in the front window of a grocery. He sold six grocers on the idea of using his signs for giving their windows a gala look on sale days. Part of his payment he takes in groceries, the rest in cash. Materials cost practically nothing, so his income is mostly net profit. For the Fishing Season A youth fond of fishing had difficulty finding worms just when he wanted them on hot summer days. So, when doing 78 spring spading in his garden, he buried a large size tub in a corner and every time he turned up a worm tossed it into the tub, along with some dirt. He mixed cotton seed hulls and coffee grounds with the dirt and kept the layout damp with water and burlap sacks spread over the top for shade. His worms grew up to 12 inches long and %-inch in diameter, finding a ready sale to other fishermen at from one to three cents each, depending on size. Fly Paper Advertising Make up samples first and take orders from merchants for sticky fly paper with their advertisement printed on the sheets and showing through the “stickem.” This especial- ly appeals to merchants as a medium for advertising spring and summer specials, since it serves a useful purpose and will last much longer than a handbill. Four dollars a hundred, including distribution by boys, is the charge established by a Michigan man who has found this idea a good source of revenue. Use manila paper, have the ad printed first, then ap- ply the following sticky formula with a brush: à 12 oz. boiled linseed oil 1 oz. resin 1 oz. castor oil New Slant on Chicken Money Chicken raising is a large industry in California and other parts. A truck driver for a feed distributing company was about to be laid off because of slackening busi- ness, so he figured out a scheme to boost feed sales which won him a raise in salary and a better job. The feed company sup- plies a certain number of its customers with 2,000 baby chicks each. Feed for them must be bought from the company. When the chicks are six weeks old, the customers return half the roosters (some 500 chicks) to the company, which feeds them for two weeks longer and disposes of them for 50 cents apiece, bringing back about double the original investment in chicks at six cents each, as well as the sale of feed. At the end of two years, when stock is customarily replaced, half the old hens come to the company for additional profit. An allowance of about 10% for death of chicks should be made. Catalog Distributor Twice a year the large mail order com- panies distribute a tremendous number of catalogs, especially in rural communities. One resident of an Ohio town who had lost his job wrote in to a large company and offered to make a personal distribu- tion of their catalogs in his community at a considerable saving over the cost by mail. They shipped the catalogs to him and he distributed them to the mutual profit of himself and the company. Modern Mechanix and

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Motorcycle Delivery Small parcels delivered in the sidecar | of his motorcycle bring a respectable in- come to a youth in Illinois who, when he lost his job, had little remaining in the way of tangible assets but his motorcycle. Determined to make his ma- chine return money to him, he gave the sidecar a fresh coat of point, stenciled a “10c Package Delivery” sign on it, and pro- ceeded to sell his services to local merchants too small to have their own delivery trucks. Drugstores he found particu- larly interested in his delivery service. A small ad in the lo- cal newspaper (he lived in a small town where a journal was published weekly) helped to inform the public of his business. Correct Time By Phone Recently an unemployed man in New York devised a clever advertising scheme. He first had some small handbills printed, advertising the fact that anyone could obtain the correct time by telephone, at no cost, and without speaking a word. It was only necessary to dial his phone number and the correct time would be given after a small advertisement had been read. He hired several small boys to dis- tribute these circulars throughout the town. He next sold advertising space to a number of local merchants at a weekly rate. As each subscriber called he read one of the advertisements, taken in rota- tion, and then stated the correct time. With the aid of his two daughters he was able to give 24-hour service by dividing the day into three 8-hour shifts. Thus he provided an indispensable service to tele- phone subscribers and an excellent medi- um of advertising for the merchants, as well as a substantial income for himself. Small Town Newspapers Nearly every small town now boasts a weekly newspaper and only the largest have a subscription solicitor employed regularly. Because they lack size their lists offer employment a few weeks only. The publishers feel it would be'impossible to find a capable person for so short a job. By interviewing several of these publish- 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? Perbaps 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 as a blessing in disguise. For all accounts used in this money-making department of the magazine, payment will be made at regular rates, Here's your chance to become an author! Keep your article brief, and address it to Modern Mechanix and Inventions, 529 S. Seventh Street, Minneapolis, Minn. Inventions for May ers located far enough apart so their lists don't interlock you can arrange a sched- ule. that will give you year-round work. Payment is usually by commission and is adequate. Publishers will be glad to give you pointers and often actual help, as you. both gain. The publishers gain subscribers and you gain a living. You will, of course, take renewal subscriptions as well as new ones and if you make good and return to each territory year after year you will find the work intensely interesting. Aid to Stalled Motorists A young fellow, handy around automo- biles, bought a second hand motorcycle, a tool kit, and a can large enough to hold five gallons of gasoline. On Sundays and holidays he patrolled the thickly traveled highways around his town and encoun- tered many motorists stalled with minor troubles. Since the motorists did not want to soil their clothes or did not know how to make their own repairs, they willingly paid rather high charges to the young man who brought service right to the spot, sav- ing tow-car expense. He also made a neat profit on the sale of his gasoline to those whose tanks had run dry. Saving Money for Gas Users Discovering that by wrapping asbestos around the home hot water tank he could have boiling water at half the gas bill, an Ohio home. owner has been making simi- lar installations in neighboring houses through word of mouth advertising. In- sulation also makes it entirely unnecessary to light the burner in the winter time in instances where pipes pass through the furnace. Any plumbing supply company will supply the raw materials for estab- lishing a profitable business of this sort. A Deal With Florists A New England man, 65 years old, found it impossible to secure a job, but he hit upon the idea of furnishing florists with plants that grow wild in the woods. Flor- ists demand such items for seasonal deco- ration. Pine and spruce cones bring him (Continued on last page) 79

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ants GROW “BLOOD” First step in production of chloro« phyll is drying of leaves in oven.,. Second step—-Dried leaves are placed in "ball mill" and ground to powder by stones rolling around in interior of re- volving drum. Mask guards lungs against dust from leaves. HE ancient sun worshippers, it now ap- pears, had a theory of life, and its re- lationship to man, which has now been proven scientifically sound. The chemists, biologists, physicians, have discovered that life comes from the sun. Furthermore, that plant life and hu- man life are chemically related if not one and the same basic thing. Out of the lab- oratory of the organic chemist comes sub- stances that show such a relationship. Physicians have for many years been advising people to eat more green vege- 80 Three stages of chloro- phyll production—the leaves, the powder and the pure chlorophyll. Third step—Liquid chlorophyll is run through silver lined centrifuge to remove all impurities. Dr. Schertz, who has achieved prominence for his experiments, is pouring. tables. “Old stuff!" you say? Yes, com- paratively. But the green foods, such as lettuce leaves, spinach, kales and others, contain vitamins, needed by the human laboratory of the body. Blood and the green of the leaves (chlo- rophyll) are practically identical. Chloro- phyH contains carbon, hydrogen, oxygen, nitrogen and magnesium. The only chemi- cal difference in the organic construction of the chlorophyll in plants and haemo- globin in blood is that the former con- tains magnesium while the latter contains iron. German chemists taking their chloro- phyll product that they derived from the leaves of growing plants, made them into pills which they gave to patients in clin- ics and hospitals, keeping a minute medi- Modern Mechanix and

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for HUMAN HEALTH Flaming surface of the sun, scientists believe, is source of the chlorophyll which colors plants and sustains life. Here’s a tube of pure chlorophyll, or “concentrated sun- light,” extracted from a batch of leaves. At right scien- tist is seen measuring work performed (consumption of oxy- gen) by man sawing, a board. Dosing with chlorophyll, tests showed, greatly increases energy production. cal record of results. These pills, which may well be called “concentrated sun- shine,” produced amazing results. The facts, as recorded in the unemotional, mat- ter-of-fact statements of the German scien- tists, would show that these chlorophyll pills reduced high blood pressure, elimi- nated anemia, made weak men strong, cured digestive troubles, and seemed to be in fact, a pill of youth. Once in the digestive stream chlorophyll immediately enriches the blood. The red blood cells immediately increase in num- ber while their haemoglobin content rises. (Hemin, of the blood, and chlorophyll, are practically identical. ) The blood thus en- riched and reinforced with new life is able to bring about amazing recoveries. The eating of green foods is taking chlorophyll into the body's chemical lab- oratory, but the taking of a concentrated form is merely a short cut in giving the body a tremendous amount of it and the reaction is positive. The sunshine that the plant caught and benefited by is thus passed on in the form of blood-life for the human being. Dr. Schertz, an eminent American chem- ist, suggests that chlorophyll gives us the clue as to just what life is, He has found a way to extract pure chlorophyll from plants easily and cheaply enough so that Inventions for May CARBON HYOROGEN-- ——— CARBON: HYDROGEN. L OXYGEN ^ -O NITROGE Mo IRON o CHLOROPHYLL CONVERTS CARBON DIOKIDE ISTO PLANT CELLS HAEMOSLO CONVERTS OXYGEN : INTO ENERGY Close relationship between green of plants (chlorophyll) and haemoglobin (blood) in human beings is seen in the chemical constituents of two life-giving substances. Note also similarity of the vital functions performed in organisms. it can be used commercially, although he was not the first to isolate it. The humanly useful place of chlorophyll is explained as the one link of nature for the converting of energy into matter. The energy reaches the earth in the form of sunlight and cosmic rays. By some mys- terious process this energy is transformed in the plant into matter. The chlorophyll plays the chief role. (Continued on page 141) 8L

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“Hoot-nanny” Traces Million Designs by Turn of Crank Millions of symmetrical designs can be traced on cardboard disk with this fascinating new toy, called a “Hoot-nanny.” esigns may be colored with crayons provided with toy. How Modern Prince Tours Desert DOUBLE deck caravan built on the lines of an open top bus, but otherwise of striking design, has recently been con- structed by the British Leyland Company for use by an Eastern Prince, H. H. Abbas Himli II, when he goes on desert tours. Shown below, the caravan has three lower deck compartments equipped with armchairs and settees which can be con- verted into a dining table or a complete bedroom suite, servants are accommodated on the upper deck where there are four cots and a tent roof. Eastern prince goes on desert tour with this specially built caravan, Interior has dining suite which may be converted into a bedroom suite or vice versa in just a few minutes. 82 F SPECIAL interest to children is a new sensational toy which forms mil- lions of symmetrical designs on paper disks. No particular skill is required in operation. À pencil is inserted in the posi- tion shown in the photo and a crank turned, whereupon the designs are traced with amazing accuracy. The designs can be colored with crayons that come with the toy. Just why, we don't know, but the toy has been given the unique name of *Hoot- nanny” by the manufacturers. Car Wheels Have Separate Motors ERMAN automotive engineers have come out with a car which merits es- pecial attention because of its unusual frontwheel drive. Each front wheel runs on its own axle and is powered by an in- dividual motor. Far greater flexibility is thus provided especially on rough ground. Another great advantage to this type of construction, engineers claim, is that a lower center of gravity is permitted, giv- ing the car increased stability, speed, and an improved general appearance. A clear idea of the construction of the bus will be gained from close inspection of the phantom view of the body below. Phantom view of new German auto shows wheels powered by individual motors, an arrangement which improves flexi- bility of the machine and permits a lower center of gravity. Six Reasons Why You Get Sick HAT medical science knows only six distinct causes of illness, was asserted in a recent lecture by an eminent English surgeon. One is injury, such as backache from a sprain or ill health as result of a wound. A second is malformation of some part of the body, such as a hunch- back or some other deformity at birth. Third is a defect of diet, causing scurvy, rickets or other such disease of malnutri- tion. Fourth is poisoning, including lead and carbon monoxide poisons. Fifth is infection by parasites, including the large number of diseases caused by germs. Sixth and last are what physicians call “neo- plasms,” including cancer and other malig- nant growths. Four most serious causes are injury, bad diet, poisoning and parasites. Modern Mechanix and

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Six Hours to Europe in Stratosphere Liner SHIP RESTS POWERFUL COMPREST AIR CATAPULT N ON LANDING ge - TRACKS ; M Mae : g Ne SoA 500 MILES AN POSSIBLE METHOD OF LAUNCHING STRATOPLANES OF TOMORROW “STREAMLINE SHAPED = : SLIDING- HULL COVERED WITH BERYLEIUM FIXED. yee = FORWARD : WING POWER EGG- Y y EACH AIR- TIGHT POWER G. CONTAINS CONNECTING: CORRIDOR ELEVATOR TO: CABIN Traveling three times faster and with greater safety than planes operating in the ordinary air lanes, great air liners of tomorrow will drone through the purple dark- ness of the stratosphere to connect the principal cities of the world in the space of a few hours, is amazing prediction of Prof, Piccard, conqueror of the upper atmosphere. The greatest obstacles to be overcome, protection against extreme cold, low atmospheric pres- sure, and the dangerous sun’s rays, will likely be con- quered by a plane having the features of the ship illustrated in the artist’s drawing above. Time between Paris and New York City may be reduced to less than six hours, when the stratosphere plane materializes. l The method of launching the stratoliner shown above SEET — BEUE- is a new development, made necessary by take-off CALWAYS- CLEAR. - difficulties incident to the design of a ship intended = € exclusively for cruising in thin atmospbere. Inventions for May 83

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Whole Cigarette Factory Contained in Single Tobacco Can Press a lever, out pops a cigatette, rolled, ready for light- ing with matches contained on side of this tobacco can. Insulated Babies Grow Faster "T9 MAKE your baby grow faster, insulate : his crib n the electricity of floor, walls, ground. To slow down his growth, ground his crib with flexible bands of metal. This is the extraordinary conclu- sion reached by M. Vles, of Strasbourg, France, who conducted such experiments on two groups of tbree babies. The insulat- ed set grew more rapidly tban the grounded trio, presumably pointing to the fact that the electrification of soil and air has a real influence on human growth. No Noise From Electric Rifle EW Army recruits suffer badly from nerves after their first session or two on the rifle range; headaches also result from noise and powder fumes. So a rifle instructor has invented an electric rifle, noiseless, powderless, harmless, since it shoots a spot of light instead of a bullet. A luminous target is first projected on the target board. When the electric gun trigger is pressed, a black spot appears on the tar- get at the point where the gun is aimed. An ingenious system of lenses within the bar- rel, with an electric light bulb as projector, constitutes the mechanism of the rifle. Light is shot instead of bullets in this electric rifle. It's a projection device, working through lenses in the barrel. 84 DD to your list of incredibilities this tobacco can cigarette factory, which nevertheless is an established fact, as our photo proves, though unlikely to cause stir- rings of uneasiness in the council chambers of the country's cigarette manufacturers. The invention is the creation of Dr. Edward P. Delevante, who has built a cigarette roller right into the bottom of the tobacco ean. At the twist of a lever the cigarette pops out ready for use, with matches handy for lighting on the side of the tin. The Perfect Secretary—a Machine EAVING his office for a few minutes, M. Keiser, inventor of the televoice, hooks up the gadget shown below with his telephone. Drama ensues. When phone rings, the machine lifts receiver, advises via phonograph record that “Mr. Keiser is notin, but requests that you leave your mes-. sage, which will be automatically record- ed.” Through a dictaphone arrangement, caller’s words are transcribed to wax cyl- inder, whence they are audibly reproduced for Mr. Keiser at his convenience, as often as he wants to hear them. ` If phone tings when occupant is out, this machine reports fact to caller, takes down any message on the dictaphone. Explosion of Sun Overdue CCORDING to calculations of astrono- mers, an explosion of the sun is some 600,000,000 years overdue, assuming that our private star has the same number of outbursts as the average star—which may not necessarily be correct. À definite num- ber of star explosions occur in a definite area of space in a piven period, and from these facts it is computed that the average star explodes once in 400,000,000 years. Modern Mechanix and

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Household Party Bar All Ready for Repeal of Prohibition SO-CALLED “rumpus cart” or portable bar has been put on the market by en- terprising furniture manufacturers who an- ticipate the repeal of prohibition. As shown in action at the right, the outfit provides sandwiches as well as liquid refreshments of a more or less convivial nature, and even furnishes a chair in appropriate barrel de- sign to harmonize with the ensemble. Cellophane Tail Light for Hikers ED warning lights for hik- ers walking along dark roads at night can be made from a sec- tion of red cello- phane or cellu- loid, attached to the trouser cuff as shown. A piece of tinfoil is placed behind the cellophane to act as a reflec- Foil-backed cellophane tail light. tor. A Transportation Problem Solved ARKING back to Indians who carry their papooses on their backs in slings, the parents shown in the picture below have improved on the idea and have worked out a scheme which divides the labor of carrying the baby between father and mother. Junior is inserted in a canvas box, legs sticking through, and one side carried by each parent. Seated in canvas chair, three-year old views passing throng with aplomb. Advantage to parents: 50-50 distribution of transportation effort. Inventions for May Space for cold drinks as well as a sandwich counter and batrel chair are provided in this portable bat, anticipating return of beer and consequent market for household bar to dispense spirituous cheer. Credits Insects With Intelligence NSECTS long have held the palm among scientists as examples of creatures with marvelously developed instincts, rigid but unalterable, which carry them through the normal vicissitudes of life. Now comes Maj. R. W. C. Hingston, noted nature observer, expressing the belief that certain insects may have intelligence as well, this being defined as the capacity to learn. An exam- ple is the ability of certain kinds of ants to stitch leaves together to make their nests, several ants cooperating to pull the leaf edges together and suiting their behavior to the characteristics of each individual job. Triple Magnifier for Jewelers ERALDED as the first improvement in the familiar jeweler’s magnifying eye- glass in 50 years, this triple lens magnifier has been devel- oped by a Holly- wood inventor. The lenses are hinged on top, can be used inde- pendently or in combination. Re- sult: choice of magnifying pow- ers of two, five, and eight times respectively. Entire outfit fits over ordi- nary spectacles. Watch parts pop up eight times natural size when jeweler brings to bear his triple battery of mag- nifying lenses shown in photo. 85

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SEA COURTS EXPLAIN STARBOARD Y RED TO PORT . WHITE LIGHT GREEN TO STARBOARD 7 WHITE Here is the usual complement of running lights on small ships. “Green to green, or red to red, — perfect safety; go ahead" is the sailor’s operating code. HeY would you like to sit in on a “traffic” case involving perhaps a million dol- lars for an accident that took place where there are no roads? Would the interpretations of the “rules of the road" bother you, especially if there- were no avenue names, no curbs, no sema- phores, no roads as we know them? You bet your life they would. As a mat- 86 Admiral Von Usslar, representative of the German Reich, at left, is conferring with nautical counsel regarding the merits of an accident which is impossible to re-enact for juries without use of models, as otherwise the jurors in- variably become confused with the unfamiliar terminology. The jatgon of the sea becomes doubly confusing to laymen who sit on juries that deal with nautical accidents. This article tells how models are used to re- enact the strange "rules of the road" for jurors who have never been to sea. ter of fact, the most highly specialized judiciaries in the world are the maritime courts where the judge must not only be a sailor who understands the jargon of the sea, but must also be an astute juror versed in the hodge podge of legal meanings and shades. The usual whereases, and deponent say- eths not of the courtroom are further mired in verbiage when the lingo of the sea is in- troduced. You can readily imagine what happens when a2 volley of words like *ves- sel of first part, being on port tack, deposes and says that vessel of second part, being also on port tack and converging upon course of vessel of first part, which un- laden, had right of way over starboard bow dead ahead—,” etc., are thrown at an ordi- nary jury. The result is chaos. Consequently America, England, France and Germany, all nations who do a great Modern Mechanix and

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ccidents Listing heavily as the beam wind strikes her sides, the finer "Atlantique" is here shown drifting toward the Cardiff cliffs of England, a mass of flames. This picture was taken but a short time ago, when the drama shown at right was enacted upon the high seas, demonstrating marine law. deal of shipping, have their own special courts in Marine Chancery. Here, to make things clear to the jury, who are selected from among seafaring folk, models are used to re-enact the accidents or points of dis- pute. The photographs show Admiral Von Usslar, representative of the German Reich, using some of there models in conjunction with charts to re-enact maritime disputes and accidents. In no other manner could the physical positions of the free vessel and the offend- ing vessel be kept clear in the minds of the untrained men who sit upon the case. All nations have uniform “rules of the road” in that great International occupan- cy, the Sea. The courtesies, the lights, the flags and the manner of conducting ship- ping are all uniform. Consequently, with so much room at one’s disposal, the rules for the high scas are rather simple. The left hand side of a vessel, facing the bow, is the port side. The right hand side is the starboard side. In sailor’s parlance, in which the courts are conducted, port, starboard, port quar- ter, starboard quarter, dead astern and dead ahead are commonplace designations. Even these terms are fairly clear to a lay- man. But when one vessel bears down on another, what are the rules to follow? Seamen have little ditties that hold good Inventions for May with eMODELS is FRENCH CAPTAIN HOISTS FRENCH FLAG f A ship afloat without crew is the property of any vessel negotiating salvage. Dutch trawlers hooked to the “At- lantique" at the same time French vessels made fast to the stern. A tug of war ensued, neither nationality victorious until the French captain of the "Atlantique" was put aboard again to raise a French flag on the jackstaff, as shown. in cases like this, On the port side are red lights, on the starboard side are green lights, on the bow of the ship is a white light, and high above, toward the stern is another white light. This is required by Interna- tional law. When ships approach each other, the sailor recalls, Green to green, or red to red, perfect safety—go ahead." During the day this matter is simple, but it is at night when the navigation of the ship becomes confusing and must be con- ducted according to light. Any other condition is met by another simple rule. Two vessels meeting head on will signal. If one has any special reason for wanting passage on a certain side, it will sound the whistle first. One blast means the vessel will pass to port, and two means it will pass to starboard. The other 97

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Diagrams Show Usual Privileges and Rights of Way on Sea Highways SAILBOAT HAS RIGHT OF WAY OVER MOTOR BOAT BOAT. WITH TOW HAS RIGHT OF WAY OVER OTHER. VESSELS Usual rule of the sea says the weaker or less controllable ves- sel has right of way. Sail-boats have precedence over power vessels, boats with tow have tight of way over all others, because they can't easily dodge out of the way of other ships. Models, correct as to main particulars, are used by Admiralty courts all over the world. Here is a set in use in the New York Customs Department where the fading terminology of the clipper ship era is made forcibly visible to the jurors through the use of models. Models are built to scale and arranged to re-create the exact conditions of accidents. vessel must answer according to the whistle signal heard, with either one or two blasts, as the case may be, and swing off accord- ingly. . For closed waters, there are a host of rules, such as harbor conduct, etc., that you can readily see would be necessary, and which are too lengthy to go into here. But it is the handling of just such in- fringements that is the specialty of the marine courts. And this is where the un- usual interest in these cases is brought to notice: Not only does the special termi- nology smack of romance, not only is it an interesting commentary on legal procedure to watch cases enacted with models and maps, but many poignant and unusual things crop up to brand this type of court 88 as one of the most dramatic of all. Let us enact a typical accident, e hie legal jargon to plain everyday English. Ship A is proceeding in a fog along to- ward evening. At intervals of two minutes she is required by the rules of the road to toot two blasts of her whistle. It is dark and foggy, and though her lights are lit, they cannot be seen by Vessel B, who is approaching head on. Both ships hear each other and so are proceeding slowly. Suddenly the fog lifts for a minute, and each ship can now see as well as hear the other. But as is the case in almost every instance, when the fog lifts there is a slight wind, and this time the skipper of vessel A, seeing the other ship’s lights, (Continued on page 136) Modern Mechanix and

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WATER MAIN,LIGHT AND TELEPHONE CABLES BENEATH FLOORING N THE majority of mine disasters due to explosion and cave-in, few men are killed by the actual falling mass of debris. Most fatalities occur among those who are im- prisoned in an air-sealed pocket in the cave-in. A Los Angeles inventor now proposes to fit mines with an invention that provides a means of escape. Partly buried in the floor of every tunnel is a thirty-inch steel pipe leading to the open air. At intervals of a hundred feet or so there is a closely fitting trap door giving access to the conduit. In event of a cave-in, the trapped men lift the nearest trap door and crawl out to safe- ty as illustrated in the drawing above. Ven- tilation is maintained in the pipe at all times, emergency oxygen tanks being avail- able in an emergency. Phonograph Warns Miners of Peril EW uses for modern electric phono- graphs in industrial psychology are suggested by an experiment begun recently at the Wyndham coal mines in Wales. As the miners of this colliery are about to enter the cage to descend into the mine, an elec- tric phonograph starts automatically to repeat warnings and instructions concern- ing special danger points underground. “Safety First,” the record begins. “Search your pockets for matches before you go down. Don't carry tools or blocks of timber in cage with you. Don't work under over- hanging coal unless securely spragged." And so on with other desirable warnings. Inventions for May Escape Conduit “Rescues Grapped eNCiners When cave-in occurs, miners make for the escape doors in the steel conduit and crawl to safety. Pipes are laid down as mine is worked, so that the pipes cover all sections. Electric Light Warns Deaf Typist Ą NOVEL arrangement has been con- trived by a typist who was unable to hear the warning bell of the typewriter an- nouncing the approach of the margin line. Seven spaces before the end of the line a light flashes on and remains on until a new line is started. This is effected by a small switch attached to the post on which the bell rest is turned on or off by the carriage of the typewriter. The light.is mounted on the end of the carriage as shown. Light turned on by a switch on the typewriter carriage warns deaf typist that the end of line is approaching. 89

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HANDIKINKS This is one of the most popular departments of Modern Mechanix and Inventions. Here you will find a variety of clever and simple stunts which will come in handy. Their nature is such that they are easily remembered. ome] Handy Long Range Dipper for Camp dud (UU ES of washing and cooking water up 4 a steep slopé offers many tiresome difficul- ties to tbe camper. There's a way out, fortu- nately. Here's what to do. Obtain an old sugar barrel and place it in a pool where the water is deepest, then fill it to the head with rocks. Around the sunken barrel secure tbe end of a length of clothesline wire, the other end of which should be threaded through a two inch pulley and secured to a post two or three feet back from the brink of the pool, as illus- trated at the left. Next suspend a bucket from the two inch pulley and to the bail attach a small rope of sufficient lensth to reach to the pool below. When the bucket is lowered it upsets and fills with water. The final task is to pull it up and take itloose. Of course, the idea is best adapted to | a permanent camp.— 5 Szt Ben Robinson. i E Rod Welded to Club Aids Putting HAVING trouble lining up your ball properly with the hole when on the putting green? Then try this. On the tip of your putter weld a piece of metal rod as illustrated in the draw- ing. When putting this welded piece serves as a straight edge to sight by. Line it up straight with the bole.—R. A. Phillips. | Eja 7 } igi METAL ROD WELDED ON HEAD a = Amusing Game Improves Golfing Stroke AY AMUSING and effective way to improve your golf stroke is afforded by the use of the simple device illustrated at the left. The golf club in this case consists of a stick as long as the regulation golf club and about % in. thicker, to which is bolted a spool about 2 in. Jong. Now this instrument is em- ployed to strike a ball made of cork or rubber. Through this ball however is driven a wooden peg. The point of the game is to strike the ball in suc a manner that the peg will be caught in the hole in the center of the spool. Practice with the club will improve your drive since unless struck accurately the peg will not be caught by the spool. —Louis Andrews. Keeps Book Open BOOK or magazine that won’t stay shut can be an awful nuisance. Here, however, is a way to cure a stubborn book of its irrepressible desire to get closed again. Simply stretch an elastic band around the center, as illustrated at the right, and then slip a pencil underneath the band. —Altamont Cole. 90 Modern Mechanix and

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Lights for Outdoor Games LOODLIGHTS are the most eco- nomical means of outdoor illumi- nation. A very efficient light can be made for a few cents with an old auto headlight reflector and a 100 watt lamp bulb. Accompanying drawing shows the simplicity of the construction. Here’s one important point: the lamp bulb must set deep into the reflector.to obtain the prop- er focal position. So a 2%” hole is cut in the back of the reflector to receive a long necked bulb. Before soldering the lamp socket perma- nently in the end of the can, a bulb should be put in place and moved in and out until a point is found where the floodlight yields a spread of white light free of all dark rings and spots. For best results, a highly pol- ished reflector should be used. To i safeguard the polish from the ele- ments, a disk of clear glass can be mounted on the front of the reflector. It is well to wrap the brass lamp socket with insulation tape and coat with shellac—John E. Hogg. WEEP easier SSOCKET SOLDERED = IN HOLE IN CAN PA, 100 WATT INSIDE FROST BULB i "AUTO HEADLIGHT REFLECTOR Iti PA TALL EVAPORATED & N "rh MILK CAN SOLDER of SOCKET MK 5 CÓ (i cup ‘nur HOLE TO TAKE SOCKET REMOVE ORIGINAL FITTINGS AND CUT 234! CONCENTRIC POST 8 FT, HIGI IN REFLECTOR. Oiled Broom Sweeps Without Raising Dust ING large floor areas is made considerably by the use of this device, which renders i / Auri Hh 1j jf osa) the strokes dustproof. The small round can shown in the accompanying drawing is attached to the handle of the broom with a pair of clamps. À piece of candle wicking is then fastened to a stiff wire and pulled onto the broom, as illustrated by the dotted line. The other end of the wick is run through a hole in the bottom of the can, which is kept filled with a good floor sweeping oil. This oil works its way down the wick and into the straws, preventing dust and keeping the straws pliable. One filling will last about a week.—A. H. Waychoff. Fumigate Crops With Old Auto Tires IRUCK gardeners make use of old auto tires by employing them to fumigate crops, burning them in the paths that criss-cross the fields. The fumes kill the insects and the burned rubber flattens down and hardens once more, providing a firm waterproof sur- face for the paths.—V. E. Barnes. Lawn Sprink- ler From Gas Burner HOSE burners yards can be The pipe which ATTACH HOSE OLD GAS BURNER TO'ARM Inventions for May found in old gas stoves lying around junk- pressed into service as garden sprinklers. leads to the burner proper is attached to the hose by means of a ferrule. When the burner is laid flat on the lawn it spreads the water over a surprisingly wide area. If the points of the burner are each bent down slightly this area will be increased considerably.— Wayne Wheeler. 91

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Handy Household Knife Sharpener BOUT the best little household sharpener we have run across yet is illustrated in the drawing at the left. Making it is sim- plicity itself. To two pieces of half inch round wood molding about 2% in. long are | glued pieces of carborundum cloth, as illus- | trated. These wood pieces are then secured to the spring and base of a piece of mousetrap with small nails. Several small holes are finally bored in the board and the entire con- traption is fastened to the wall. The knife is sharpened by slipping it back and forth between the carborundum covered surfaces. The abrasive surface should be as fine a grain as possible to prevent its scratching instead of sharpening.—Ben Lollen. Cheap Fuel From Waste, Oil Paper SLOW burning and very hot fireplace fuel can be had for nothing by utilizing crankcase oil and old newspapers. The papers are folded flat, about nine by twelve inches, and a number of them bound to- gether with baling wire. The blocks are then soaked several hours in a tubful of waste oil, after which they are hung up and drained. They should be stored outside, under cover, and stacked with blocks between to permit air circulation and prevent overheating and the hazard of spontaneous combustion. One block will burn for an hour or two, giving off a good deal of heat at practically no expense.—Bill Crothers. NEWSPAPERS SOAKED IN CRANKCASE, Kink to Reset Door Latch Socket NSIGHTLY and difficult shifting of the door latch socket to permit easy latching of warped or sagging doors can be easily avoided. Simply remove the socket frame and with a small three cornered file file down, or up or to the right to enlarge the socket. A knife or chisel can be used to enlarge the latch hole in the wood and the latch frame can be restored to its usual place. Sags or warps of more than one quarter of an inch can be easily accommodated in this Table Salt Prevents Burning of Jam HEN cooking marmalades, jams, or heavy liquids which require a slow fire for several bours, the danger of scorching may be prevented by the simple expedient of setting the kettle in a tin pan of table salt, as illustrated in the accompanying drawing. This salt serves as a cushion to diffuse the heat and prevent direct contact with the pan. The salt can be used over and over again. One precaution, however: do not use an alu- minum pie pan for the job, because it will burn through in a short time.—Hi Sibley. 92 way.—Bruce Ellsworth. Modern Mechanix and

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Fan Purifies Workshop Air | ysg weu ; SRED OE ON BENCH A í | || DRIVE SHAFT DUST ana mist from paint spray machines or grinders soon short- en. the lives of workmen unless Simple precautions are taken. For the small workshop, an inexpensive method of clearing the air makes use of: a second-hand auto fan which may be picked up at any junk shop. This fan is operated from-a pulley driven on the nearest motor drive shaft. The fan efficiently cleans the air by way of a wood or sheet tin air channel leading to the open.— Everett Folger. Small Bench Vise From Strap Iron XCELLENT for handling small work, this tiny bench vise is easy to make. The strap iron pieces should be bent to the shape jllustrated at the left and held together with small hinges attached with countersunk rivets. A carriage bolt takes the place of the screw, and tightening the jaws is accom- plished by twisting the large-eared wing-nut. To compensate for the angle at which the stationary piece leans, the bolt is bent slight- ly at the head. If the L by which the vise is bolted to the bench is omitted the device will serve as an excellent work clamp. The device is particularly useful where work with small or delicate units is involved.— Thomas L. Moore. Rope Does Duty as Vise to Remove Pipe Coupling T ERE'S a simple little kink for plumbers who have forgotten their * vise. It has to do with removing coupling. First a rope is wound around the coupling as illustrated and then a stick is inserted and twisted. Pull this stick around till the rope grips tightly, then give a.firm yank. The coupling will come loose easily. Wetting the rope will increase the firmness of.the grip. Good strong half inch manila rope will suffice for the task.—cC. J. Marek. f INSERT PIPE AND TWIST gy Home- Made Microm- eter HIS is not a substitute for a standard micrometer, but it will, if used carefully, afford some very close measurements, A Y6"x3$" bar of brass is used to form a horse- shoe of the size shown and another smaller piece of the brass is soldered on the end of the horseshoe to form the anvil. The opposite end of the horseshoe is drilled to take either a 10-32 thread or an 8-32 thread. The thin sheet brass disc is next divided up into sections and soldered to the thread- ed rod or screw in the position indicated. The pointer completes the job. When the 32 series of threads are used, we simply need to keep in mind the fact that such threads advance one thirty-second, or .030 of an inch every time they are turned once. A half turn would be 1/64th or .015, etc. The gadget will prove surprisingly handy for ordinary use.—haymond Francis. Inventions for May 93

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AA : Keep Warm With Stove Made From Oil Drum SWITCH SURPRISINGLY practical and sturdy stove can be made from an ordinary oil or alcohol drum, as illustrated in the accompanying drawing. The legs may be made from heavy strap iron, which is bolted onto drum. To make the door, simply cut out a section about 14x14, attach a pair of hinges to one edge, reinforce it with tin, then bolt back in the position shown. In the top cut a 6-inch hole and solder around it a piece of tin to take the chimney pipe. An old bike bell makes the draft on the door.—Thos. Rooney. A SECTION OF 77 BROOM HANDLE 7 COGWHEEL FROM CLOCK True Up Grindstone With Pipe and HE most effective way to true up your shop grindstone is with a pipe and fine sand as illustrated at the right. Bolt a piece of pipe to the frame of the stone. Then feed the sand by hand and tap the pipe up close as the stone cuts away. If your stone is very much out of true the bumps can be cut down quickly with an emery whecl dresser, using no wa- ter. Use water copiously with the sand, however. For a square face clamp the pipe crosswise.—E. Dorris. 94. Sand Remote Control Toggle Switch O NEED at all to get out of bed if you have this pull chain switch easily acces- sible to your hands. Simply reach up and grab a cord, pull it, and on or off goes the light, just as you wish. How the stunt is worked is illustrated at the left. In the handle of the toggle switch bore a hole to take a !4-in. stecl rod, bent at right angles, as shown. To the ends of this rod attach a pair of cords leading to the head of your bed. They can be passed through a pair of screweyes if the switch is in an awkward position.—V. E. Barnes. Old Clock Wheel Makes Paper Perforator EED a gadget to perforate pages or sheets of paper that have to be torn along an even line? If so, this little gadget will do the trick. The cutter is a cog wheel. taken from an old clock movement. The edge should be ground lightly till it is plenty sharp. For a handle, cut off a section of broomhandle about six inches long, and slot it in the end about two inches deep. The wheel fits in this incision. Perforation is per- formed as illustrated in the drawing. With a good cutting edge on the wheel the sheet should tear evenly and easily. Apply just as heavy pressure as you can without bending the wheel. It will probably be necessary to file down the clock teeth to sharp points in order to provide sufficient of a cutting edge. — A. H. Waychoff. Modern Mechanix and

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Favorite Tune Rouses You in Morning ETTING out of bed in the morning is a painless task if you are awak- ened by strains of your favorite tune, setto going on the phonograph by this little automatic switch. The trigger, made as illustrated in the accompany- ing drawing, is attached to the bell of the alarm clock, so that when the |——- alarm goes off juice to the electromag- TURNS C net is turned on. This latter part, taken from an old doorbell, has a pad on the bell clapper which presses against the turntable, setting it in mo- tion when the armature is drawn back. Before you go to bed, you should wind up the phonograph, put on the record, and set the trigger.— J. Vartalied. qowme your glider back to its starting point is unnecessary, for you can make 2zx— your auto do the pulling. Simply attach a . boom to the side of the car, as illustrated at the left, and hook the glider onto it and tow away. 'A cable from the front of the auto to the end of the boom holds the boom in position. One precaution: when you are towing, don't hit up a too high speed, other- wise the glider might take off for a short flight and come down on its nose.—Albert ; inox Hawver. Making Titles for Home Movies FONT of letters for use in making ama- teur movie titles can be made from a package of alphabet soup noodles. A piece of black paper over which is pasted a suit- able border makes a nice contrasty back- ground for the titles. The illustration at the right shows a simple and convenient method of clamping the camera over the edge of the table directly over the title board. If a hand operated camera is used two turns of the crank for each word used in the title will give the right amount of reading time. With spring motor type, one second of running time per word is sufficient.—Bruce Sifford. BROKEN ENDS Repairing Broken Hack Saw Blade SLIPPED INTO ROKEN hack saw blades which still have a good bite to them can be mended with the little stunt illustrated in the drawing at the left, which makes use of a round head bolt, a washer and a wing nut. The bolt should be slotted down the center of its shaft and slipped into position as illustrated. Then the washer is slipped in place and finally the wing nut, which is wound down till the teeth mesh. Make one or two of these gadgets and keep them handy in your tool box for emergency use. They'll come in handy when you're out of blades. When you have a bolt available you can get a lot more use out of a new blade that has just snapped.—Little Handy Andy. Inventions for May 95

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STOVE PIPE EXTENDS AROUND BASEMENT Wien a hole must be bored in a space too small to admit an ordinary bit brace, which requires Heat Basement Without Fuel Cost ASEMENTS can be heated without any additional fuel cost if the pipes leading from the furnace to the chimney are ar- ranged around the room in the manner shown in the accompanying drawing. The pipes will be kept quite hot by heat which otherwise would be wasted up the chimney. The same idea can be extended to an or- dinary coal stove to obtain the greatest amount of heat from a minimum of fuel. In effect, the pipes, which are of course unin- sulated, act as radiators. A garage can be similarly : heated. — Wil- liam Tatina. considerable elbow room for manipulation, an ordi- nary porcelain door knob can be used as a substitute. The knob has a square hole in its shaft which fits perfectly the tapering shank of the bit, and by simply turning the knob a hole can be bored as shown in the drawing.—George P. Ford. IRON STRAP Yandgxse Extra Hoe Blade yor hoeing between plants which are so close together that the large blade cannot be used, an auxiliary blade made from a piece of stiff iron or steel and bolted onto the hoe with two stove bolts, as shown in the drawing, will prove very useful. It can also be used for making rows when seeding. It is slightly bent, as illustrated, and dimensions are about five inches in length, 1% in. width and !4 in. thick.—M. Winterton. Window Lock Made From Checker HEN a window or similar vertical sliding panel or door will not stick in position when raised, but begins to slip, the simple checker lock shown at the right will come in handy. Drill a hole through the checker about three-sixteenths inch off center and insert a screw for attachment to the jamb. When the checker is pressed against window it is effectively locked in place. Release is effected by turning the eccentrically mounted checker in the other direction.—J. Marinac. Rain Warning Signal Made From Bulb OR those who wish to know at night the instant it starts to rain, the device shown at the left will be helpful. A filament electric bulb is cut off into cup-like shape and mounted as shown. Diluted sul- phuric acid is poured into the cup, bringing it almost to the level of the two platinum tips in the bulb base. When a few drops of rain fall, the level of the liquid will be raised, a connection made, and the bell sounded.—J. J. Brixius. Modern Mechanix and

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Angle Mirror for Your Auto E YOU are angle-parked alongside a truck and wish to back out into the street, you can do so only by being extremely cautious in your progress, owing to the impossibility of seeing around the truck into the approach- ing line of traffic. The ordinary rear- vision mirror is useless in such an instance, but if a mirror be set in place at an angle in the rear quarter of the car, as shown in the drawing, approaching vehicles can be plainly seen. It is recommended that the mir- ror be at least one foot long, and set: at such an angle that it can be watched from the front mirror.— Douglas Vreeden. Wf. MIRROR SET | | || AT ANGLE I MIRROR SHOWS < ONCOMING C

Automatic F TaN Close U p the Space Beneath Loose Fitting Caie Doors HEN garage doors are loosely fitted, as is sometimes the case when old buildings are used for housing the car, there is fre- quently an objectionable open space between the bottoms of the doors and the floor. Fold- ing flaps which rise or lower as the door is opened or closed, excluding cold air, snow, leaves, and small animals from the garage, can be constructed from the diagram given at the left.—Vance Bell.

SPARM SUPPRESSOR

Eliminating Noises in Auto Radio ITEGUEEED. with induction in your auto- mobile radio? Here's how to get rid of it. First remove all the leads from the spark- plugs and connect in the spark suppressors as illustrated in the drawing. These suppres- sors can be obtained at any radio shop. Then cover the entire plug with a rubber hood. This should eliminate the induction noises. Charging your radio battery en route may be accomplished with the circuitemploying = = | the D.P.D.T. switch.—_Thornton Hallett. FROM GENERATOR EXTRA BATTERY YZ FOR RADIO be y

Flexible Magnetic F ic Fishing Too g Tool Wien tools, nuts, screws, etc., drop into inaccessible places, their re- covery is often difficult. The writer

3" LENGTH OF 4” MAGNET STEEL

FIBER WASHERS. pL ER:

Pin T ACNE ae, So À DDES MAGNET WIRES CASE-20 INCH LENGTH eo FLEXIBLE TUBING PUSH-BUTTON|, FROM FLASHLIGHT Inventions for May

had his share of this sort of trouble until he rigged up the magnetic “fish- er" shown at the left. A five inch length of steel is wound as a 6-volt magnet and soldered into the end of a 20-inch Jength of flexible brass tub- ing. Wires pass through the tube to a push-button switch, with spring clamps for attaching to any 6-volt battery. When the juice is switched on, the magnet will pick up steel ob- jects weighing up to a pound.—John Edwin Hogg. 91

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Building the @ABINETTE Here is the trailer for the man who wants to see the country comfortably ‘in a mobile home of his own. It can be built for around $50, according to locality, and will prove a satisfactory place to live on a country-wide tour. HIS cruise trailer was designed to do but. one thing, and to do that.thing well: furnish a comfortable traveling accessory to the modern tourist in which he could live. There is room enough for four bunks, although only two have been shown. There is a water closet, and a sludge tank for dish- water and sewage can be installed under ihe house for use when parked in some place too pretty to despoil; there is an ade- quate galley or kitchen containing a sink with running water; there is a pantry for ihe storage of food; there is a bureau for nick nacks. Every function of living has been accom- modated simply, yet adequately. One can live, sleep, eat:aboard this cruising trailer, and carry his home with him wherever he goes." - $ The factor on which the whole design hinges is the chassis. We use an old Model T Ford chassis as they are the easiest of all old auto frames to procure, and as well are notoriously long lived and free from wheel trouble. Also the tires are dirt cheap. The best way to work is from the ground up, and the first thing to tackle is the con- version of the trailer. SPACE ROOF CARLINS 4 FIRST STEP IS AS SHOWN LEVEL WITH FLOOR OF TRAILER = The building of the body or cab is simple as we have designed it, but the matter of. underslinging a Ford chassis is a horse from another stable, and therefore let's go into this most important end thoroughly. ' As shown in Fig. 7, top, the Ford channel frame is 23 inches wide. It is four inches higher at the rear than at the front. Also. the frame proper is way up in the air, far too high to allow us to put on a cab body with nearly full 6-ft. headroom unless we- lower it. Make strap spring shackles for the rear end as the drawings show. Any-blacksmith can do this for you for very little money if you don’t have the facilities yourself. The idea here is to get the shackle long enough to let the whole frame down so it is level. The wheels are mounted into the 1-7" a H Al SEE DETAILS $ STEEL STRAP HINGE | ASSEMBLY { / / zx i£ BARS DETAIL. OF | { ADJUSTABLE | STEP HINGE ADAPT ENDS TO CAR DETAIL OF SHOCK ABSORBER BOLT AROUND STRINGE! SANNE TM TOGGLE 1 TOW HANDLE SEE DETAIL. WHEEL BASE INCREASED 8" TO 9" BY CHANGES The little drawing in Fig. 9 shows how to determine the right length of tongue for the towing arm. The middle inset shows a fine shock absorbing hook-up to be attached to the towing car. Fi ig. 11, below, shows how the stringers are attached to the channel frames after the chassis has been underslung. 98 Modern Mechanix and

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(?ruise «GR AILER .^ ie Trailer cruising has become really a smart thing for people to do. This Cabinette idea is just another step farther along toward the ultimate in inexpensive and practical trailers for tourists. new spring perches, see Fig. 3, and the radius rods heated with a welding torch, bent, and re-seated. This takes care of the rear end, just as simple as that. See Fig. 8. The front end underslinging is not hard the way 1 i J Here's the arrangement that will prove most satis- we have it doped, either. See Fig. 3. factory for extended cruising and living on the road. Remove the front axle from the . i ] spring. Turn it around, end for end. Shackles for the front spring. This part zs This now places the steering tie is highly stressed and nothing but “Ge rods forward. Bore out the taper Chrome moly will be safe. Plymouth a seats on the present spring Tear spring shackles can be adapted, or . perches, and re-bush the old 2" iron store or hardware store : ones so they have parallel Can order for you what you need, /4 . as they have wholesale service ao Nh shakes end bolt them up to their doors daily andit does 5 ine Then comes th ly littl not take long. i € only Nive The U shackles are 7f piece of fussing you are put to in doing the job. >. You must secure some = øs% Chrome molybdenum xxe Tod out of which you . can make the new U carefully heated, and SA slowly bent so there will D z IR A be no cold shuts in the [Agw ái angle. When these have se 5 Hin been turned out of %” % J ar The Cabinette cruising trailer can be wheeled to any spot, no matter how wild or how civilized, and be a self contained living unit with its own water and sewage system. Privacy, comfort and adequacy are all yours with this simple job. Inventions for May 99

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Steps to Follow in Conversion CLOSE HOUSING WITH STEEL PLATE FORD"T"CHASSIS TRAILER IORMAL WHEEL BASE 98" SPRING PERCH ‘15 TURNED UPSIDE DOWN FORD FRONT AXLE IS v TURNED END FOR END, ; | PUTTING THE STEERING RE NEESER OHACRLE | RODS IN FRONT, SO FRAME | CAN BE SUSPENDED AS D^ | SHOWN DN j FORD FRONT SPRING à LX FIG. S j à STEERING Eu AS NEEDE! IRS. REAM HOLE PARALLEL; - REBUSH AND REBORE SHORTEN TIE ROD FOR THE PROFER"TOE -IN" ` STEERING ARM FIG4 HOOK. AND f CLAMP AROUND "Se THE AXLE BEARING ARM WELDED : BOLT TOW HOOK-UP FOR FRONT AXLE ,| DRILL AND sPAcE $ HOLES AS SHOWN 100 T STL.PLATE stock for the ends to land in the spring and perches, they may be bent. The threading is, of course, done before any heating takes place. The front radius rod is bolted to the strap cross arm which has been moved to fit. See Fig. 2. The ball of the radius rod is softened by annealing, ground to wafer shape, drilled as the details show. Now this change will place the frame very close to the axle line. When the stringers for the body are bolted to the frame there : wil be about 4 jn. road clearance for the body—not much, but not any more can be doné with this item; remember this is an adap- tation, and we have to take the best we can get out of circumstances which are beyond our control. This one little point is the only thing where the whole design could be criticized. If one does not travel too fast over rough ground there will be no trouble. All rough corners should be taken easily, for it does not matter whether the axle comes in contact with the stringer as long as it is done gradu- ally. On paved or gravel roads you can e bounce along merrily. The front tie rod will have to be shortened so that the wheels have the proper amount of “toe-in.” Measure the distance between the wheels on the out- side and inside, back and front, and shorten the tie rod with a welding torch until the wheels track as they did before the axle was turned end for end. This point is highly important. If you do not do this, towing the trailer will amount to the same thing as trying to drive an auto backwards at high speed. It will wreck the trailer and throw it out of control. : For steering a special kind 1 of trailer hook up is made. ø g kz In this galaxy of draw- ings will be found the essential points covered in con- verting the Ford T chassis to an underslung trailer chassis. Fig. 1 shows normal Ford. chassis but with. tie rods in front. Below is shown chassis finally converted. Modern Mechanix and

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See Figs. 4, 5 and 6. The drawings show $ 4 ; a ea e arahi oon s Deut Details of Strong, Simple Framing around the axle, and secured with two %" hook bolts which can be made by any blacksmith. i A %” hardened steel pin is run through the towing tongue and this plate. It forms the pintle through which the towing and turning stresses are focused. It therefore must be this heavy, and be hardened. The Trailer Tongue : The tongue itself is of pipe. Two-inch pipe will do. An alligator mouth is sawed in one end, and a piece of hardened strap is riveted on the end. If the pipe is left top and bottom to carry the load it will soon chew off and you are in danger of losing your trailer. With a piece of hard- ened strap on the tongue you know that can never give way. The strap for the tongue makes this a universal joint, and it is stiff enough for towing and steering. An ideal arrange- ment, and it has proven itself on several hauls of over three hundred miles in length already. With these changes made, you are ready for the body, but I have one more word to offer. About the tongue length: Every car has its own turning radius, and so does a trailer. The two must have a tongue of just the right length, otherwise both towing and corner-taking will be (Continued on page 138) ROOF COVERING OF F y | METHOD O DX 4" BEADED CEDAR 2 NAILED- COVERED BIN REINFORCING CORNERS —— 77 ILLU CARLINS ARE x 1 E W.OAK ~ SPACE AS SHOWN IN FiG-11 jx 2" W.OAK p FRAMING ALL SIDES OF 3 X4" BEADED CEDAR, FASTEN WITH. SCREWS FLOOR OF ix4'rFR T COMPLETE FRAMING ASSEMBLY — — —— WHEEL BOXES 2"X4" STRINGERS S OF 20 GA. GALV. IRON pea FASTEN WITH SCREWS OF WOAR Top right shows rear elevation with miscellaneous details. Middle detail, Figs. 14 and 15, show framing and window details. Below in Fig. 16 are shown major elements in straightforward freming plan. Materials can be procured locally. Inventions for May 101

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Music and voice from radio is produced in sound patterns on the screen of the “vibrometer,” as shown in drawing above. OPENING FOR LIGHT BEAM LIGHT PROJECTOR 74 MELTED PARAFFIN LOUD SPEAKER UNIT ITH the simple little instrument here described, a whole new world of radio experimentation is opened to the amateur. On a screen you are enabled actually to see the strange effects of sound waves and the endless variety of patterns, many of them curiously beautiful, that are produced by the incoming music and voice in a radio receiver. The pattern producing instrument is made by placing a small radio loudspeaker unit, preferably of the Baldwin type, in a .tin can in the manner illustrated in the drawings above. A half pint lacquer or paint can is just the right size to accommo- date the average small unit. Two tin lugs are soldered to the can to 102 "Vibrometer" Makes "Radio eMusic Visible | nr -U oE à ISMALL, Ron WEIGHT! Interior view of the "vibrometer" shows how mirrors are mounted on the 2x4. Beneath is seen the can over which is stretched the tubber holding the pool of mercury. Light beam reflected from mirror fluctuates on screen due to motions of the mercury mirror. TRANSLUCENT SHEET TIN DETAIL OF MIRROR Details of construction are seen here. Con- siderable care is required in the ptoper adjust- ment of mirrors. Beam strikes center of screen. hold it down to the baseboard. Inasmuch as a dead sound chamber must be produced between the loudspeaker unit and the rub- ber diaphragm, it will be necessary to pour melted paraffine in the space that exists be- tween the loud speaker unit and the tin can. The rubber diaphragm must be very thin for best results. The writer used a rubber balloon and strong rubber bands to bind it over the top of the can. The degree of tautness of the rubber diaphragm will de- pend somewhat upon the power the loud- speaker and the current fed into it. It's mainly a “cut and try” job. Inasmuch as a small pool of mercury is (Continued on page 142) Modern Mechanix and

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Make Spring PROFITS on Outdoor J deas Home-owners Will Welcome These Backyard Accessories Sheet metal parrots, cut to shape shown here, can be sold to owners of rural mail boxes. The wooden tanager decorates hedge. Playground slides on estates of well-to-do people with children will yield profits. Plans are suggested in photo. You can gather in many half dollars manufacturing these elongated sprinklers. Attach to hose as. shown. Ornainental rock work like the above offers profitable field for masons. Few tools, some concrete and stone are all the materials you need. Inventions for May 103

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Electric Question Game cAmuses, Educates Interrogating party playing the question and answer game touches a nail in some question sector whereupon the “interroga- tee” touches a nail indicating the corres- ponding answer. If he hits it correct the bell will ring. Circles on the bristol board on which the questions and answers are written are divided into 12 sections for as many questions, as shown in photo. ALTHOUGH this simple form of electric question machine was made originally to interest a boy about ten years old, it was brought out at an adult party recently and served to amuse a number of guests for at least a period of one hour. Such is the fascination it offers. Begin construction by making two circles on a base board as shown, dividing it equal- ly in twelve parts. At every point a six- penny nail is driven into the base, bell wire being used to connect the two sets of nails together electrically. Stagger the connec- tions to confuse the players. Now a nail is driven exactly in the center of each circle and this is also connected in the manner illustrated in an accompanying drawing. Construction is continued by cutting out a piece of plywood the same size as the baseboard, with holes in it a little larger in diameter than the circle formed by the nails. Nailed down, this plywood covers up all of the connections. Connect up the board as illustrated in the wiring diagram. The circuit should be so laid out that when the nail on the question side is brought into contact with the nail near one of the questions, and when the nail at the 104 WRITTEN HERE CONNECTING WIRES Wire up as shown above, but stag- ger the connec- tions to confuse LAMP CORD players. QUESTIONS 34 PINE Nails are driven in baseboard in positions shown above and covered by the plywood to conceal the wiring. end of the flexible cord on the other side of the board is brought in contact with the correct answer, the bell will ring. To make the questions and answers, heavy paper or bristol board is used with circles cut large enough so that they will clear the nails. Each piece of paper or bristol board is divided into twelve parts and the questions and answers are placed in these sections. Naturally, when the cor- rect answer is given, it should not be written in way that will give the user a clue as to which nail should be searched out. Another thing worth remembering for those who use the game with children is that some effort should be made to link the questions and answers up with their school work. Thus the game is a sugar coated med of driving the difficult lessons ome. Modern Mechanix and

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Obstacles which collapse at a collision with the coaster are set up as illustrated here. Lay out your course in the manner suggested in the drawing at the top. HERE is an exciting game which can be played by all the neighborhood gang with the simplest of equipment. À winding course is made on a sloping sidewalk or driveway, the boundaries marked by a series of obstacles such as bottles, tin cans, cigar boxes and other objects which are easily toppled over. With a small coaster made of odd pieces of wood and a roller skate, as shown in the Shock Type Screwdriver Loosens TUBBORN screws can be easily loosened with a new kind of screwdriver, shown in the accompanying photo. This tool has a blade at each end to take Jarge and me- dium size screws. z Slipped over the screwdriver proper is a piece of iron pipe, both ends of which are cut half away so that the pipe can only turn on the screwdriver about half way before it is stopped by the pins. When loosening a screw. the tool is gripped by the pipe and turned quickly. The pipe stops on the pins and delivers a sharp blow on the screwdriver, with a much better loosening effect than the steady twist of a regular screwdriver. The screwdriver point may be made to fit loosely in the pipe to permit change of size. If you need a longer tool simply lengthen the pipe. The pins are made of small nails inserted in holes bored in the points. Let them come flush with the pipe. Inventions for May “Ride in Backyard Steeplechase; Here is seen how theskate wheels are mounted Keen Fun It takes real skill to negotiate the course without colliding with obstacles. 'The coaster is steered by leaning to one Side or other. Perfect score entitles you to another ride. perspective drawing, the player coasts down the line and attempts to avoid all the hazards. Steering is entirely by balance, and with practice one can become expert. Penalties are charged for knocking over the obstacles, the most unstable ones draw- ing a light penalty, such as one, and the most stable ones as high as five. A perfect score, or lack of any penalty, entitles the player to get another turn, or to ride until he does knock over an obstacle. A sugges- tion for hazards is given in the drawings above. Others more elaborate can be Worked out. Ordinary bottles and tin cans will make adequate obstructions. Tightest Screws With Little Effort When screw is to be turned with this driver, the point is set in place and the handle given a sharp turn, communi- cating a telling twist to the screw. Right—How pipe handle is cut away. 105

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cA Wooden ‘WATER Wheel oe All that is needed is a six-foot head on a 16’’x16’’ flume in order to get 114 h.p. from this simple wheel. It is of tbe overshot type, and housed in the dog house above are the pump and dynamo it is capable of driving day in and day out. This simple wheel will develop a full one and one-half horsepower on a head of only six feet through a sixteen inch flume. Many farms can take advantage of natural resources in securing light and power this way. by JOHN S. ERE are complete plans and instruc- tions to build a 5 foot rustic wheel for the farm—one developing under only 6 foot fall at full capacity, an honest 1% horse power! It will drive a 1 kilowatt electric generator at night and the house pump by day; furnish about 30 twenty five watt lights at night and lots of water by day. First, cut out 24 curved segments as shown in Fig. 1, to make the two side rims. Each rim is to have two layers, break the joints midway and nail together with ce- ment coated nails, if you can get them, on 3 inch centers. Cut the segments out on a band saw to dimensions. One segment takes a piece of lumber 11x %4 x30. inches exact. Now cut out 46 pieces of 3x%x19 inches long tongue and grooved boards and nail to the inside of the rings as shown in Fig. 2. Lay these tongued and grooved pieces up rather tightly, as they are meant to hold water under a little pressure, two nails each on each end. These go all the way around the inner rim. 106 CARPENTER Next make 14 water buckets as shown in Fig. 6, beveled at the tip where it cuts the water jet, and nailed with 5 nails to the backing piece. This will require 14 pieces each of 8x?4x16 inches long and 5x%x16 inches long. Using a scratch awl, lay off a circle 1 inch in from the outside circular rim, on the faces that are to be the inside of the wheel. Then lay off 14 spaces along these circles, with your rule, or dividers set at 12% inches, which will thus divide off equally, the bucket spacing. Set the beveled tips “A” Fig. 6, on these spacing marks all around the rims, so the buckets: will be correctly spaced and so the wheel will not run lopsidedly. Toe nail the buckets in the rims and see that the seat “B” comes down squarely on the %x3 pieces nailed inside the ring. If they do not, a little beveling at “B”, Fig. 4, will make it right. Be sure that the buckets fit rather snugly in the rims, but not excessively tight. To make the hub and arms, we first get a 1x% inch flange coupling and taking it Modern Mechanix and

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for the ARM STREAM apart, use half for each hub. Now get two discs of boiler iron or scrap sheet steel and have a 2 inch rough hole burned in the center of each disc. These discs should be 1, inch thick by 15 inches in diameter, shown in Fig. 4. They can be cut sufficient- ly round with the welder's cutting torch. Mark off and drill the discs centrally from the holes in the coupling halves and bolt the discs fast to the coupling halves. Have six %x1% wrought iron bars each 25% inches long welded to the discs as shown in Fig. 4, placing the arms radially on 29 inches radius. When the arms are spaced correctly around the disc, the dis- tance apart at the tips of same, center to center, will just measure 29 inches. Punch two % inch holes in one end of the arms 2 CEMENT COATED NAILS 30” | TONGUE AND GROOVE BOARD j| LING FLANGE f 30” ATOR BELT FIG.2 Le io" ' SECTION OF WOOD BLOCKS CAST WHEEL IN CONCRETE NAILS 3°C TONGUE AND Las BOARD E f Du N / Mes FIG.I pill iM CURVED SEGMENTS e FOR SIDE RIMS E ae $ LZ umm Curved segments, 24 in number, are used in the construction of the wheel as shown in Fig. 1. 4' 6” nl”. i Eg 3'4” | ! | SET " SE ICOLLAR WROUGHT i DIA. COLLAR | & Y q| IRONARMS | SHAFT |e d Era ZZ = 2 a EA Ed Jc CR [za c HALF COUP- ja PULLEY FOR GENER- as shown for bolting the arms to the wood rims with lagscrews. Now let us get the shaft ready. It should be of 1:5 inch diameter, 4 ft. 6 inches long, sawed off square on each end, but not necessarily turned off. We are now ready to bolt the arms to the wood rim and this should be done with the arms on the shaft, as in Fig. 4, so every- thing is lined up centrally. Using a rule, measure to see that the shaft is placed in the center of the wood rims, as this is important for good running balance. The shaft need not be key-seated, but the coup- ling hubs can be drilled and tapped for % inch setscrew in each and the cone points of the setscrews can be let into the shaft about % inch after the location has been found. Now we can mark off the holes for the arm lagscrews and thus bolt the arms fast to the wood rim. Should it happen that the wheel will not turn evenly when start- ed, we can drill new holes for the arms and plug up the old ones. SLOT FOR FLUME SEAT cU Um FIG.3 GENERAL VIEW OF WHEEL The centerline of the wheel is 40’’ above the run-off ‘water to get good clearance without sacrifice of head. Fig. 3 shows the concrete spillway. Inventions for May 107

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Plant Like This Supplies Current for Farm at Original Cost of Only $65! 4" HEAD WATER Y To the left above is shown the flume construction, and the gate for the spillway. Right lower view shows the method of beveling the bucket. For bearings, if economy of costs are very important, you can use oak blocks drilled for the shaft hole, and then bore a 4% inch grease hole thru the top for lubri- cation. These oak blocks should be 4 inches wide. Iron bearings can be often bought second hand and what we need here is what the trade calls solid journal bearings, babbitted. To keep the wheel from moving sideways use two set collars, one on each bearing, opposed. They can be bought cheaply solid, or in halves. See Fig. 2. Placing Wheel in Pit Now we are ready to place the wheel ‘in its pit, which we can make up of 10 inch concrete walls as shown in Fig. 3. We will bolt the iron bearings to wood blocks cast into the concrete walls, having carefully leveled the top of the blocks. The bottom of the wheel should not run in the water, but should be about 10 inches above the runoff water level, so that the center of the shaft will be about 40 inches above the runoff water level. Bring the water to the wheel thru a 16x16 square box wooden flume or a 16 inch steel pipe and end up at the wheel as shown in Fig. 5 with a gate box. The water chute should be 4 inches high and 10 inches wide horizontally. The gate should be of wood, at least 1 inch smoothed plank, 8 inches wide and 14 inches long. It should work in a slot and be raised with a lever and ‘wooden connecting piece. To regulate the Speed, you can prop the lever in such a way so that the gate will not move; in any con- venient way. B To connect to the generator, belting will 108 Center shows the method of making the strap iron web spokes. Bearings can be oak blocks. be the cheapest. Arrange the pulleys so the wheel will run at its proper speed, 25 revo- lutions per minute and using two steps you can easily get up to the generator speed. Using two pulleys on the wheel shaft, one can be for the pump and the other for the generator, by merely changing belts. You .can get small water pumps so cheaply now- adays, particularly those of the Myers make, with pulleys complete, that it hardly pays to get a second hand pump. The generator can be located in some used machinery shop and it will probably be best to use 115 volt current as all house utensils are made for that voltage. Direct current com- pound wound machines are best for this use. Typical Installation Cost $65 A man in my part of the country made his wheel, bought the generator, wired his house and farm complete for $65. He leaves his lights on all day so the wheel runs at steady speed. He milks his cows, pumps water, has lights and current for the toast- er, sweeper and icebox; all by electricity and while it’s not a show plant, he wouldn’t take $5000 for the plant. A very fine rustic effect can be obtained by covering the wood rims with hemlock bark and wiring pieces of bark to the arms. A heavy coat of pitch will preserve the wood for years. A little “dog house” built over the generator and pump will save it from the effects of the weather. This type of wheel is called the overshot wheel, and is more efticient than the under- shot wheel, other things being equal, and is easier to build. (Continued on page 142) Modern Mechanix and

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“Distinctive Lamp Has Glass Possessing a unique distinction, the towel rod lamp is an inexpensive ornament for the living room. If the rods do not fit tightly twist the top slightly to obtain the spiral effect shown above. The pull chain comes out the side, likewise the 110-volt cord. "CLASS rods form the shade of this lamp. Such rods, in the form of towel racks % in. in diameter and 17 in. long, are obtainable at any five and dime store. To cut the rods to length, rest the ends on a flat iron or other anvil and chip away the flange with a cold chisel. When all ends are roughed in this way, grind the corners to diameter, and cut them through the centers. Turn the base in a single piece, mounting a. 734-in. piece of rough 2-in. hardwood on a face plate. Shape the profile, sand, and turn the groove for the rods. Remove the base, smooth the bottom, and bore a center hole for the cord. Turn the top ring with the inside against the face plate and when turning the lid be sure to make it small enough to enter the ring without binding. To assemble the lamp, stand twenty-nine rods in the base groove. Then enter one or two in the top-ring groove, sloping the ring toward this point. It is easy to enter the other rods, one at a time, holding them with the thumb outside and the fingers in- side. When all are in, press the ring down. Fill the grooves outside, between the rods, with wood putty. To keep the socket and bulb from show- ing through the glass, crumple cellophane and tamp loosely in space within the shade. The color of the woodwork should suit the room it is to be used in. Black or jade praen is good. Use a sixty-watt frosted light ulb. Inventions for May “Rod Sides ge REMOVABLE LID | GLASS TOWEL wi RODS PORCELAIN SOCKET | e y EM ) TVs = DIAMETER Turn out top, bottom and lid to dimensions shown. Cord is brought down through hole, and out to side in a groove. Fill the rod grooves in top and bottom with putty to make sides substantial. Spirit Level and Square in One ERTICAL as well as horizontal beams may be trued with this improvised spirit Jevel that is constructed from a carpenter's square and a small 1%-inch bottle. Fill the bottle with colored water, cork it tightly allowing a small — I air bubble, and ] secure the bottle |- to the handle of the square with rubber bands. When measuring a vertical beam the blade of the square is merely held against the beam as illustrat- ed in the photo. If the square is to be used for checking a right angle the bottle is easily re- moved. Of course, the beam is true when bubble is centered. Rubber band holds vial in place. 109

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Ways of Doing It: Recognize it? The power head of an Evinrude 16 has been furnished with a radiator and a centrifugal pump and a propeller boss. It flies a lightplane very nicely. IHREE novel kinx have come our way that deserve a page all their own. One was spotted at a Chicago airport, another was seen in a home in Detroit, and the other was tendered by a reader. In seeking a motor for the lightplane which they had built, two Oak Park lads took the power head from an old Evinrude 16. They had in this motor the roller bear- ings needed for thrust bearings, and all that remained was to build a gooseneck to keep the carburetor in its original posi- tion and to build a bracket on which could be mounted a centrifugal pump of the kind you buy in supply stores to cool model T Ford cars with. The hook-up worked well. Above is shown the method of mounting. The procedure generally in use by home owners in keep- ing their Jawns clean is to let the wind do it. A De- troit residence owner built a lit- tle shingled post, hollow, in which he deposits pa- pers and refuse he finds about his lawn as he returns in the evening. Every so often he has a bonfire, and the lawn is kept neat with a minimum of nursing. Now for the blowpipe kink. It very often hap- pens that a very hot flame is need- Above photo shows a refuse col- lector for the yard made to match the architecture of the house 110 Engine, Mail Box and Blow Torch ed in the workshop for a short period of time for welding, melting, etc. In such cases the apparatus about to be described will do very nicely. It is merely the old- time chemical laboratory gas generator adapted for use in supplying a stream of oxygen to the ordinary blowpipe frame, and thus turning it into an oxy-hydrocar- bon flame for your shop use. The outer contain- er may be any sort of vessel that will hold water; a Mason jar or a Inner ; Contaimer [f An oxy-hydrocarbon flame for generating extreme heat for short periods as in the melting or welding of metals can be made in your own shop in the style shown above. tin can of any sort. The top of this is closed with a plug, of wood, cork, or even plaster of Paris may be used. This plug has a hole in the center to admit the inner tube or container, which holds the “oxy- gen cubes” commercially called “oxone.” About 1 in. from the lower end of the inner tube is placed a disc cut from screen wire, slightly larger than the inside diame- ter of the tube, so that the edge may be bent over, holding the disc in position by pressure. A piece of metal tubing is run through the plug of the inner container; a length of rubber tubing and a stop clip, such as used on fountain syringes and obtainable at any drug store, and a common jewelers’ blowpipe, complete the list of materials. In operation, the outer container is filled about halfway with water, and the plug is replaced. The plug of the inner tube is removed and some lumps of oxone dropped on the wire screen. Then, first making sure that the spring clip on the rubber tube is closed, so that no air can pass through, the inner tube is put in position. When the spring clip is opened, water flows up into the inner tube, reaches the oxone and generates oxygen with sufficient pressure to be used as a blowpipe stream. Modern Mechanix and

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Jt“ Pays to Know @hese Stunts Padlocks exposed to outside moisture soon rust into uselessness. If a new lock is care- fully stuffed with vaseline, forced into all the openings with a small knife, it will be T d practically rustproof, eliminating the possi- Liquids can be boiled bility of its some day having to be opened rapidly if the coil from with a hacksaw or a hammer and cold chisel. an electric heater is fit- ted in a socket, turned " : 3 on, and placed in an Heater Unit Keeping Shoes New empty- glass sitting in my the pan containing the ^ liquid to be heated. To avoid breakage, be sure the: glass is sitting in the liquid before the hot coil is put in place. Collodion, painted on the stitches of a new pair of shoes as shown, prevents the accumula- tion of dirt and mois- ture and preserves that brand new look for many weeks. One ap- plication of collodion will last several months If the unit of a bowl-type heater burns out beyond repair, a 500-watt electric bulb will make a serviceable substitute, though somewhat more costly to run than the original unit. A two-for-a-nickel mouse trap, tacked to the wall, makes a handy holder for grocery bills and other papers A large book makes an excellent tie press when large enough to admit full length of tie when folded into sections. Inventions for May 111

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This shows how the dryer and developing drum is set up on the apron of a sink. ote the jogged secondary trunnion support for the axle. This permits the drum to be raised free of the trays and thus allowing it to be speeded up for drying. Note the motor and a suggested drive. negatives tucked into the brass septums ready to be run throught the developer. To the left is an inset showing the Labor Saving Photo Developer by ROBERT C. QUIGLEY TEE professional photographer always has a lot of work on hand. The amateur, more and more nowadays, saves a batch of films and then does 'em all up in a hurry. Both of these gentlemen give splendid imitations of a one-armed paper hanger caught in a high wind when they get in their dark-rooms and try to wash each rint, one right after the other. Generally aw and order go up the flue and hit and miss arrive with a flourish. But here's a rig that organizes a relatively large amount of work and pushes it through the soup with a delightfully progressive orderliness. The machine is at once a developing ma- chine and a dryer. Tray Slips Under Disk Two wooden discs about 24” in diameter are mounted on an axle which is connected to a motor by gearing and pulleys so that the wheel will turn 78 r. p. m. on one belt and 300 r. p. m. on another. The axle mounting is loose so that the developer tray can be slipped under it when it is raised, and successive trays of Hex LODEIS water, hypo, and water can be used. Then the drum can be raised and the high speed belt used to whirl the negatives until they are dry. The same procedure can 112 be used for prints in their intermediary stages of drying before they become curled. and after they have dried sufficiently to be inserted in the brass septums. These marginal septums are made from brass rod and are spaced according to the size of the cut negative. There is a small slot run into them on the milling machine. If you do not have the facilities for making these slots any machine shop will welcome Mhe wank of putting them in for you on their miller. How the Film Is Held The ends are flattened and screwed to the discs. The film will snap out enough to be held with sufficient rigidity in the slots while the drum is rotating. Brass and bronze should be used for the fastenings as they are chemically inert to most of the mild acids once a salt has been formed on them similar to rust, and they do not deteriorate after that. No formula can be given directly for the exact size of the wheel and for the exact speed. So much depends upon the element of time used to develop, wash, fix and rinse. The way to approach the determination of speeds is to equate the time normally con- sumed in developing to the trip time through the developing bath, working Modern Mechanix and

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Developing, Fixing and Washing Done on Single Automatic Machine down from the speed of the motor and the pulley ratios, using a fixed motor speed of 1,750 r. p. m., which is the fixed speed of all induction motors running on 110 volts a.c. This will allow you to put in the films on one side and to take them out on the other, dropping them into the fixing bath. Another tray can then be lined up and the wheel run with its set of prints for the right amount of time in the hypo. Then the washing can be done for a much more thorough job in less time by continuing the same speed and running in a tray of mildly circulating water. In Use as a Dryer When thoroughly washed, the wheel is speeded up to the figure given, 300 r. p. m., which will create a breeze on both faces of the negatives and do a good job of drying. On my machine I found that water spots due to irregular drying were done away with, and the films dried without curling, due to the evenly distributed pressure over their faces because of centrifugal force. For a man with a lot of professional work to do such as is found in the 8-hour photo finishing service, these machines might well make the nucleus of a good business, especially in many of the smaller towns. In that case it would be a good idea to have several drums, and load one with ex- posed negatives, put it in the developer, and remove the whole wheel to the fixing bath, then move the.whole wheel on to the other baths, having a wheel for each of the baths if the, a of work warrant- ed it. [Lm Cats Considerable experiment- eptums fer ing will have to be done 44, ing Films WW with solutions, for while | wheel developing is much laboratory Cink more even on a given quan- Board tity of film, it is also a lot faster and youll have to monkey around with some . Brass Beari Take i ME read Old £L lectric fan i Plan Or Comprere ASSEMBLY Or DeveLorine WHEEL Upper right is a view showing the developing drum with tray under for washing of negatives. show the manner of grooving used in the brass rod septums. dri A suggested drive is shown to the lower left. Note the method of raising axle. screws to hold them to the discs. Inventions for May To Sink Boar. Dotted Line Trclcates Pasiti e : Wh " Dino in 9 tiln cmm. Secrion Tamu Seerums S Z Dia. Drass Exo View OF Woop Weer sample shots to find the right normalcy of solution for the most effective work. One kink which the amateur is generally not aware of is used by professionals in drying prints. That is bathing them in alcohol briefly after they have been thor- oughly washed, and then ironing them out on enamel plates with a squeegee. The alcohol takes the water into solution, and the print then dries with only the water of inclusion and the surface alcohol remain- ing to be evaporated. This will give glossy prints, and if you cannot find enamel plates with the baked enamel faces like automo- bile mudguards look when new, you can use plate glass as effectively. Prints after they have been partially dried in a machine like this should be press dried in blotting paper sold for the purpose by photographic supply stores. Frequently the amateur, and the profes- sional as well, is troubled with prints curl- ing after drying, owing to inequalities of surface tension set up by the emulsion. Large plants have devices which run the print through a series of rollers and so re- move the curl. The same effect can be secured by immersing prints for not less than five minutes, between washing and drying, in a bath composed of one part glycerin to seven parts water. - "DIO: riving Machanism End View. OF , Seeprum. Fraps The cross sections The ends of the rods are flattened and drilled for 113

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Paper placed on apron is smoothed down with blade to form a compact cigarette. Note how the handle is drawn back. WOOD BLOCK CUT OUT ON BAND SAW CURVATURE DEPRESSED FROM THIS POINT FORWARD ROLLER 34: COPPER TUBING HIGHLY POLISHED’ 34g HOLE TOBACCO IN SMOKI POSITION | SPARK PLUG TERMINAL NUT Make cigarette by placing tobacco in posi- 'tion 1. .'Then draw handle back to position -3 and your smoke will be delivered in rear. 114 Ig HOLES Yi APART + Wi SOFT STEEL —>| PLACE SUFFICIENT © ^ \ POCKET TO MAKE Y E ADJUSTMENT PIN W ROD HOLES TO ——M ADJUST SIZE þe—— » OF CIGARETTE goos to the stress of the times, many men have resorted to “rolling their own.” It is a truly economical measure, because the smoker does not have to pay the exceptionally heavy tax—30 cents per 100—assessed against “tailor-made” cigar- ettes. Why not make your own cigarette rolling machine? The construction is simple and material costs only a few cents. The accom- panying drawings show a machine which rolls cigarettes of four different sizes: a fat cigarette for an after-dinner smoke, a con- ventional size, a slender cigarette and a slim one. With the use of a machine, itis customary to roll a quantity of “smokes” at one time. The tobacco usually comes in a package as illustrated, and the whole is contained in a cellophane wrapper. To prevent drying, open the cellophane at the top and slip out the package. Now measure up the package the length of a cigarette and cut completely through with a sharp knife or scissors. Remove the contents. After the tobacco has been converted into cigarettes, they are packed into the lower part of the package. The top part serves as alid. The cellophane is replaced and twisted up. The cigarettes can be stored away indefinitely in this pack- age without drying out or deteriorating. Some smokers complain that the tobac- co in home-made cigarettes gets into their mouth. This difficulty can be avoided, and at the same time provide the cigarette with: a moisture- proof mouthpiece, by dip- ping the lip end into melted paraffin. When this is done the end must be pierced. . APRON- DRAFTSMAN'S TRACING LINEN: WIDE SAFETY RAZOR BLADE vg woop Y Y Y Y CIGARETTE PAPER, ^ 'UMMED EDGE UP Modern Mechanix and

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Vacuum (leaner Motor Powers Shop “Drill SCREW HOLES perfect ease. Completed drill, shown above, handles wood, hard rubber, bakelite up to V; inch with Copper, brass and soft iron up to % inch. h 14 GAUGE BRASS HANDLE- 14 GAUGE’ BRASS l^" wiDE POWERFUL and serviceable electric drill which will handle wood, bakelite and hard rubber up to a thickness of % in. and brass, soft iron and copper up to % in. can be easily made from a discarded vacuum cleaner motor by anyone handy with a few tools and with access to a lathe. ’ Begin by overhauling the motor, clean- ing it with hot water and gasoline to remove all traces of grease and dust. Then repack the bearing with hard oil and brighten the commutator with fine sandpaper. The fan should be removed from the shaft and the pinion secured firmly in place. The gear case can be spun or soldered into shape over a hardwood form the exact size necessary to secure a snug fit over the front of the motor housing. The position of the hole for the chuck bearing can be de- lermined by laying the pinion and gear in mesh on the front of the gear case and marking the center of the larger gear with a punch. One-sixteenth tolerance should be allowed between centers. ` Now get to work on the two-inch brass stock. Shape the nose and drill the 3⁄2 in. hole for the spindle, then cut the recess for the thrust bearing. With this accomplished, the bearing is off-centered % in. and the metal cut down to % in. to provide a shoulder. By rotating the spindle bearing before it is fastened in place the proper location can be readily determined by the sound of the gears. Inventions for May VACUUM CLEANER MOTOR = V4 CHUCK FLANGE TURNED AGAINST THRUST V3! THRUST ^acanNG BEARING (any REINFORCEMENT Here's how.to assemble the drill. Front of gear case is reinforced with disc of 14-gauge brass sweated into place. When the proper adjustment for the gears has been determined, drill the gear case and spindle bearing from the back and tap for round-beaded machine screws. The handle is bent as illustrated from 14-gauge brass strip. Sweating these brass strips together will give a handle of sur- prising rigidity. A tumbler switch mounted on the handle provides for easy operation of the drill. Likewise the handle is suitably drilled for the cord and leads to the motor. The handle is finally finished with two flat pieces of wood or it may be filled with plastic wood compound and covered with friction tape. For light work and model making, it will be found advisable to insert a resistance in the line to cut down both speed and power. Aside from the motor here are the chief parts you will need: %-in. grinding and buffing spindle with chuck, which may be obtained from any large hardware store for less than a dollar; %4-in. pinion for %- in. shaft; 1!5-in. steel gear with set screw for % in. shaft; 9°x9” piece of 14-gauge brass; thrust bearing; 2-in. round brass stock 2% in. long for spindle bearing; 3 feet of brass strip. The length of the cut down section of the spindle can be determined by drilling a hole in the center of the gear case. A piece of steel wire inserted through the hole until it touches the surface of the pinion gives the exact distance of pinion from front of gear- case. Drill shaft for set screw accordingly. 115

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Scram’s Simple Construction Is Strongest, Lightest and Tightest Known

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a wo x zz $9 ag wo J i av wi 22 aa or zx oz x ox at d wo ZJ Ba Ò zi : p ou = a o 59 2 oz < Pie FE STATION 1-A LOOKING AF T. BASE-LINE Here ia the construction plan of “Scram.” Don’t ask us to figure the bill of lumber for you; you can easily dope this, out from. the scantlings and sizes shown above. Topside planking is 34” Honduras. mahogany, bottom double planked of %'' diagonal spruce with %%'' fore and aft mahogany outside. The fittings for the struts and the cast- ing for the rudder and rudder stock can be furnished by our Experimental Station. The motor plans of conversion will be run next month, complete in all details. .. : : : g ; : 116 Modern Mechanix and

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“Scram” in action reveals a brilliant boat with the so-called “level riding” any good design must exhibit, and as welt has thundering speed for a craft so tiny. Here she ig pushing the forty mack, Sweet running, and smooth, too. “PLANS for “SCRAM” PART II Here is the second installment of Westy Farmer’s most popular boat design. Further notes on her construction, with added plans and photographs, are shown in this month’s chapter. AST month we took you for a ride in this fiery little, sleek little, inexpensive little thunder boat, and got you started along proper lines in building her. This month we continue but before describing how the frames are got out let’s have a word for the men who are here meeting Scram for the first time: She is 15% feet long by 5 ft. 2%" beam, by about 15” draft. Powered with a Ford Model A engine (which we'll later show how to convert into a 65 h.p. high duty marine mill) Scram is easily capable of leaving all present day two-cockpit run- abouts of her size in the lurch when it comes to speed. She banks her turns like an airplane and is a sure cure for all who crave real speed thrills. Best of all is the matter of the motor. We are working out a list of costs on the matter of finished machined castings and parts needed to take a raw Ford A Inventions for May block assembly, costing $59 new, and turn it into a hot marine engine—not a make- shift, but a real one. You will be pleased to know that the whole engine can be made for about what a good used large model outboard can be bought for. The Ford motor as it stands can be con- verted three ways: it can be put in a boat just as it comes from a car, where it'll weigh close to 600 lbs. and take up half the boat, developing 30-38 h.p. You can convert it a second way, using Ford parts and putting on an oil cooler and reverse gear. This is but little better. Then there is the way we have doped it out: deep base, oil cooler, high compression head, cooled manifold, downdraft and reverse gear. Last issue we ran her lines, outboard profile, pictures of the boat in action, and showed how to lay the lines down. If you have followed us this far you are now ready to rough out the frames. 117

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Turn to page 116 to the construction cut shown on that page. You will see that the Írames used for making the molds, or for building the boat in other words, are at stations 5, 4, 3, 2 and 1. Now look at this page. Here you will see how the frames have been cross tied at the open part across the top, and how a 2" by 4" of some straight but scrap wood has been mortised so that the frame could be rigidly mounted on it. The 2" by 4" is held in line by two strong- back pieces upon which the frame is set up. The frames are properly spaced out on this strongback, and the intermediate frames are placed in the boat after the planking is 2"X2" WHITE OAK CHINE Above circle shows transom and chine de- tail. The center view shows how frame will jock on the strong- back. The two by fours and the braces are, of course, knocked out when planking is completed. .done. This saves a lot of fairing and fitting which would otherwise go to waste. The number of frames indicated are amply strong for building the boat. : The stem is cut and rabbetted as per the ‘drawing on page 119, which shows how the rabbet is cut and how. the clamps join the breasthook. It is easier to make little brass clips for the heels of the frames than ‘118 5 Showing Complete Frame Details 3-8" MAHOGANY TOP SIDE PLANKING ComPLeTe “Set Up" —FOoRScRAM. UU SAW HORSE RESTS STERN View AND FWD COCKPIT. .[RANSOM CONSTRUCTION UPRIGHTS FOR TRANSOM 7-8” MAHOG. Photo above shows how diagonal pieces ate fastened in. Drawings and photo to left and above show how boát is built without transom, which is fastened on out- *& side after the planking is done. This is easier, and’ just as strong construction. to lap the heels of the frames together. We can furnish you these clips cast in aluminum if you care to write us. The cost is moderate and the labor saved is enor- mous. Also the resulting job is stronger than as though the heels of the frame at the chine were riddled with screws in the wood that remains after the mortise for the chine piece has: been: cut. Modern Mechanix and

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The transom frame is put up at the same time as the others. The notches for the battens are done after the frames are up. There are four planks on the topsides, equally spaced in width at the frames. The battens are 3$" by 11!5" white oak. They may be spliced with feather edged splices if the stuff cannot be obtained in 16-foot lengths which will be necessary for the work. / The battens are DETAILS FoR SCRAM let in flush with the edges of the frame, which has, of course, been trimmed off the thickness of the planking as the lines are given to the outside of the planking. The stock for the frames is %” x 3%” mahogany on the main frame set ups, and %” by 3%” on the intermediate frames which are put in later. The battens are feather edged into the stem, and all fastenings are countersunk, be- ing brass screws, No. 7, %” long on the battens. Also the same for the clips at the frame heels. Chine Is Next The next piece of wood to be put in is the chine. This is a piece of 2” x 2” white Inventions for May CONSTRUCTION screwing transom onto hull. and second layer of outside 3⁄4” and marine glue. hull’s construction, photo shows method of using template for marking crown of the deck beams. oak, or preferably mahogany. Anchored to the transom through the corner edge of the chine piece, liberally countersunk (No. 8, 112" f.h. brass screw) the piece is successively fastened to the frames as they run forward, and is tapered and cut a bit toward the stem to make bending easier. A rope windlass will bring the à pieces in for fastening if you are not able to soften the wood with rags soaked in hot water. Then the bottom battens, underlaying the diagonally laid 3$" spruce inner bot- tom are put in. The method of notching is as follows: DECK BEAM CONSTRUCTION METAL. CORNER CLIPS: Top photo shows method of cutting off battens and planking flush with the transom frame before Left upper detail shows diagonal planking mahogany, which is laid over cloth Center isometric view shows cutaway details of the Frame and clamp details are shown also. Bottom Cut one notch in the frame forward. Spring the batten back over the frames, mark the spot it crosses each frame, then saw to the inside of these marks, and cut out the notch with a chisel. The battens are allowed to run past the transom frame, as the planking, battens and all are trimmed off the last thing prior to putting on the transom itself. Why this is done will be explained later. Topside Planking Comes First The topside planking comes first. The chine is rabbeted on both the bottom side and the topside, a rabbet, or groove, being cut deep enough to take %” planking on (Continued on page 140) 119

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Camero plate older Structural toys would be far more popular if snaps could be used instead of the usual bolts. Paper - ; He PI When buying a bottle of glue, you pay more for the bottle than the glue. Costs will be slashed by the invention of a glue that can be sold in ba!l form in pasteboard boxes. 120 Left—A brace that will hold plate glass windows firm against the onslaughts of hurricane winds is needed to re- duce glass insurance. Thief proof electric eye will bring auto- matic garage doors into vogue and win fortune for inventor. Editor's note; Mr. Yates, nationally known patent expert who conducts this department, will answer ques- tons of readers desiring advice on how to secure pat- ents, on methods of procedure, or on ideas for inven- üons, when such. requests are accompanied by a stamped, self-addressed envelope. Never send models as they cannot be accepted. Address Mr. Yates care of Modern Mechanix and Inventions, 529 So. 7th St., Minneapolis, Minn. by RAYMOND F. YATES Photo-Electric Cells and. Garage Door I confess that this idea calls for an un- usual trained inventor. At the present time these cells are being used to auto- matically open garage doors. This is a great convenience until one also considers the fact that should a prowler light a match in front of the cell while the family is away, the doors will obligingly open, which makes the use of jimmies and pipe cutters un- necessary. Naturally this sad shortcoming robs this wonderful device of many uses. Why can- not we answer the burglar with a photo- electric relay that will function only when it receives a series of light impulses flashed jn a certain code that can be projected upon it? We would have something unbeatable if we had that and electrically controlled garage and other doors would rapidly come into vogue. Specifications: Such a device should not add over 100% to the cost of present equip- ment. This would make the total cost about $250.00. : Exploitation: Should be sold outright to some large electrical manufacturer for $35,000. Inasmuch as. Europe is not the mechanized country that the United States is, this invention should be patented only in the United States and Canada. (Continued on page 144) Modern Mechanix and

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FEN Sell “Refreshments from Golding “Playhouse HIS little “timbered” cottage has a double attraction in that it not only can be taken apart for moving, but is designed for use as alittle ~~» shop from which to sell ,—~/ * refreshments or home- ( made novelties. Say 4 Construction is of ^ wall board or mason- ite on a light wood framing of ?74"x2" ‘Oregon pine, with flat sections hooked together so they can be knocked down and stored under the . With a coun- house or in the ter built be- garage. hind window ES the house 1s attrac- a ee tive refreshment stand. given in accompany- ing drawings. The timbered effect is ac- 36" complished simply by painting brown over the white or cream background of the wall- board, and the upright “timber” indicated effectually conceals the joint between the two front sections. The front wall shown in the drawings is typical construction. Horizontal members of the window frame have spliced joints and the vertical members are beveled. The “glass” is celluloid fastened on the inside with half-round moulding. An opening is left in the rear wall for a Kise Rn ERE door 24 in. by 72 in. The two sections of PAINTED ON this wall are joined just as the front wall FAINTED RED is. The joints on the roof sides are made waterproof by means of strips of muslin and casein waterproof glue. HOOK AND EYE MUSLIN AND ' | WATERPROOF GLUE a'o" CHIMNEY SET OVER SPLICED JOINT ` oUfsibEOE — REAR WALL: OR 48" X 60" EACH T e ipm WALL BOARD Z SECTION NC. HOOK LE Sections of house are spliced and held together with hooks. Parts may thus be disassembled for storage or transportation. Inventions for May I 121

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*Probing e7Y(agnetic Secrets of Your “Watch av SOLENOID 3”DIAMETER 4, 15 TURNS NO.20 WIRE Your watch can be de- magnetized by the sim- ple apparatus illustrated here. The coil is formed by winding 150 turns (not 15) of No. 20 DCC wire around 3 in. tube in solenoid form, with 100 watt lamp in series with 110 U.A.C. If the watch is inserted in the coil, with the current on, and When end of magnet is ap- plied to back of watch, the movement is instantly para- lyzed. Demagnetization will set it going again, accurately. 122 slowly removed, it will lose its magnetism. When a magnet is held in this position mag- netic lines of force pass through the watch, making it possible to exercise a rough control over the speed of the timepiece and, conse. quently, of the time it keeps. While all watches are slightly magnetized, this simple test will tell whether your watch has an overdose of magnetism. As shown, a heavy needle is sus- pended at the end of a thread and the watch is brought near. If the needle swings out violent- ly to meet it, your watch is heavily magnetized, and should be put through the demagnetiza- tion procedure illustrated in an accompanying drawing. Better yet, make an appointment with your jeweler and get him to overhaul your timepiece thor- oughly. How magnetized watches may be tested for polariza- tion. Placed face down- ward on glass, the time- piece will whirl into posi- tion relative to N and S pole of magnet shown here. Modern Mechanix and

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Boosting Volume and Sharpness of T. R. F. Receivers I5 EARLY electric receivers using ganged condensers, chances are that the set does not tune properly all over the band. By employment of this little kink, however, the reception is improved from a mere whisper to enough volume to fill the room. A variable condenser, which may be taken from an old broadcast receiver, and two lengths of shielded lead in wire will do the job. It's à good idea to mount and shield the condenser. Connect the device in the circuit as illus- trated at right. In operation, the condenser is opened and a station is tuned in in the usual manner. Then start tuning the con- denser until a maximum volume of undis- torted music is received. Once the music becomes distorted while turning the regeneration dial, it is time to retard the dial several points. Otherwise an ear-splitting howl may result. If your set uses all five-prong R. F.’s connect both wires to prong shown for A.C. detector. The Arbor for Unreeling Fine Wire TIRA ‘STATIONARY BLOCK HUA i COIL TO BE WOUND Wire spool is affixed to the rotating block, which permits the wire to unroll without strain, eliminating breakage. DEAL for winding coils with wire of No. 36 or smaller is this little arbor, which may be constructed from the dimensions given above. Fasten the wire spool to the center of the small board, as near its center as possible. The form to be wound is held in the hands and walked back a few feet, then wound up towards the arbor. For more wire, the worker walks slowly back until enough is unwound and the procedure repeated until the form is fully wound. The arbor winds easily with very little strain on the fine wire and no breakage. U Inventions for May [n SHIELDING ^7 | .06035 GROUNDED VARIABLE COND. HOOKUP FOR BATTERY AND D.C, SETS © it NC SHIELDING” 00035 GROUNDED VARIABLE COND. HOOKUP FOR A.C.RECEIVERS For increased sharpness and volume, hook the condenser in circuit as shown, shielding the wire to the prongs. last R. F..tube can be distinguished easily since it is the tube next to the detector in the direction of the antenna and ground terminals, When you’ve got the set working right, youll be amazed at the new volume and sharpness of your set. Making 85 Millihenry Choke Coil HEN a broadcast receiver hook-up calls for an R. F. choke it usually means one of about 85 millihenries. Here’s how they may be built. First get a small wooden film spool and strip off the metal ends. Now cut out four washers of stiff cardboard or fiber board and glue them on the spool as illustrated in the drawing below. Next scramble wind 500 turns of No. 34 SCC wire in the first section, 700 in the second, and 800 in the third. When completed fasten the ends of the windings and cover the turns with Duco cement. Of course, all three sections are one continuous piece of wire. Connect the coil in the circuit as illustrated in the drawing. 34 C. WIRE 800 550 TURNS 700 TURNS Three sections of No. 34 SCC wire are scramble. wound between the cardboard washers and inserted in plate circuit. 123

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Dalk with Entire Continent on Amateur radio station with 20 meter transmitter in operation, Fig. 1. Top view shows | rs ] = I/SCREEN mais VOLTAGE +, GROUND ON SHIELD KO -= =e .002 GRID a EL ee EP ———— FAHNSTOCK CUP o 00 TO ANTENNA FEEDERS = 3 SEE ANTENNA =a CENTER TAP coiL p= ave ES > E 10000 OHM 25 WATT GRID LEAK Signals from this little transmitter, which can be built for about $5, will put you in communication with all amateurs within 2000 miles. Get on the air with it and make radio friends all over the continent. HE little transmitter shown in the ac- A companying photographs and sketches has been designed for the amateur who wants to operate on the 20 meter band ex- clusively. The new power tubes called pentodes are used as the oscillators, a pair of them being used in a push-pull circuit. This transmitter is for code work only. Due to the push-pull circuit and its inherent stability, using a good DC power supply, with the circuit properly tuned, the note will have nearly crystal charactcristics and your reports should be consistently ‘Xtal, pure DC". : A pair of 247s using 500 volts will give an output of between 12 and 15 watts. Two 233 tubes at 180 volts will show consider- ably better than 6 watts. The transmitter as shown, exclusive of tubes and power supply, can be built by the careful buyer for less than five dollars. Using 247s over a month’s use, the set gave excellent results, and consistently contact- ed amateurs between 800 and 2000 miles. Note the neat appearance, All wiring is done beneath the baseboard as seen in Fig. 4, leaving just the dominant parts above deck. This base was a single board smoothed down and cut 15 inches long by 10 inches wide. The parts were arranged exactly as shown in Figs. 1 and 2. About 4 inches from 100-200 OHM = FIL.RESISTOR GUE À :000025 PLATE) 00025 VARIABLE CONDENSER GROUND ON SHIELD = Sa A LJ Fig. 2. When secured to baseboard, all parts are hooked up according to this diagram. Fahnestock clips for external connec- tions are disposed along sides and rear. Parts shown in dotted lines are mounted under baseboard, where all wiring is run. 124 Modern Mechanix and

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this 20 eACETER Cransmitter HOW TO BECOME A RADIO AMATEUR Want to get on the air and talk to the whole world with your key? How to build and operate your own short wave station, how to master the code, and how to procure your radio amateur’s license—everything you'll need to know is told in the booklet "How to Become a Radio Amateur” available for 25 cents at Modern Mechanix and Inventions, 529 So. 7th St., | Minneapolis, Minn. i each end and 2 inches from the rear edge place a sócket as shown. Use 5 prong sockets for the filament type tubes such as the 247 or the 233. For pentodes indirectly heated (having a cathode) use 6 prong sockets. Face the two heater prongs of each socket towards each other. Use an 0 to 200 milliammeter. To the back terminals fasten two stiff wire legs bending their ends at right angles to fit in the clips on the base provided for them. You can thus take the meter out quickly if necessary. Provide a small jumper wire with clip to shunt the meter out when keying. The grid coil consists of a piece of wood- en window shade roller 2% inches long. Using No. 30 DCC wire, put on two sepa- rate windings of 8 turns each, as illustrated. Space the windings about 1 inch. Fasten the winding ends under the heads of pins cut off and driven into the wood. Connect the two inside turns together to form the center tap. The .000025 midget tuning con- denser, of course, is mounted in front of the coil in a vertical position. . When the coil is finished flood the wind- ings with waterproof cement so the turns will retain their position. Otherwise any (Continued on page 136) 00025 VARIABLE CONDENSER PLATE COIL C S í fo S WAP. AT ANTENNA ANTENI NA XC Hn CENTER FEEDER RE CHOKE SEE FIG) d 3 0—200 00-200 0HM MILLIAMETER FILET RES ISTOR —— .002 FIXED CONDENSER QOOVOLTS ESTED) d) A VOLTAGE 2335, HAPPY à fOR.23NS 500 V.D.C.FOR 247'S GRID GROUND ON SHIELD 25V.FOR 24Ts Q FOR233,135-180 FOR 247'S R.F CHOKE FILM. SPOOL "SSE 60 TURNS 30-32 DCCWIRE 2}'———» connect c JTOGETHER WINDINGS EACH 8 TURNS 30 DCCWIRE WIRE LEGS FOR METER PLATE COIL 5 TURNS LY COPPER TUBING ANTENNA COIL 7 TURNS 410-12 COPPER WIRE ANT, COIL PLATE COIL’ Fig. 3. Milliammeter is supported on wire legs. Below, how plate and antenna coils are wound and fitted together. Underside view shows how wiring is done. Note cleats which hold board up from table, allowing space for wires. 233 0R 247 TUBES SHOWING CATHODE CONNECTION: GRID COIL B TURNS 330 D.C.C, WIRE ———P, -002 GRID CONDENSER 0OUUUU QU 000025 MIDGET COND, Ù PLATE) B= ANQ SCREEN VOLTAGE 2V. FOR Ó t KEY VOLTAGE TÉ —90y = GROUND ON SHIELD Fig. 5. Follow this diagram also when wiring up with layout scheme in Fig. 2. Lead marked to ground on shield at left may be taken directly to B minus lead, which takes both plate and screen voltage minus. Screen terminal is marked K on tubes. 125 Inventions for May

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eZ XCIDGET *Dacuum Sweeper Operating like vacuum sweeper, the little “eater” sucks the table clean of crumbs or clears work bench of shavings. Here’s how to tack the metal plate over the block with the V-shaped notch. End notch comes under the center of fan. NN E S rp LOCKING PIN AIR CURRENT Drawing shows details of the “electric crumb eater.” 126 Blades of fan, curved to a 2-in, radius, are soldered on the brass disc, with the small end in the center. Six blades are placed equidistantly apart. LTHOUGH designed primarily for pick- ing up bread crumbs,” the midget vacuum sweeper described here has been found useful for a great many things—col- lecting seeds dropped from bird cages, re- moving lint from odd corners, gathering up sawdust and chips after home repair jobs, cleaning the shop workbench, and SO On. The motor was part of an electric mixing device obtainable at 25c stores. After the parts of the device were discarded, the motor was mounted on a square piece of 14 in. plywood just large enough to extend a fraction of an inch beyond the fan edge. This fan is made from sheet iron or brass as illustrated in an accompanying drawing. Cut a disc 3.to 4 in. in diameter, and drill a hole in the center to fit over the motor shaft. Cut six blades to a shape that re- sembles half of an orange segment when seen from the side. Bend these blades until they are curved to about a 2 in. radius. Solder them at equidistant positions on one side of the disc, the small ends at the center. They should be placed so that the convex surfaces are towards the direction of rota- tion of the fan when mounted on the motor shaft. A collar such as that shown in the drawings, riveted to the disc, is suitable for mounting the fan on the shaft. Now, when the motor whirls the blades, air will be drawn in at the center and thrown out at the edges. Housing Made From Plywood Make the housing from % in. plywood, and miter the vertical corners. Then cut a lid to fit down inside the opening. Mount the motor at one end of the lid by means of two crosspieces connecting the under- side of the lid and the motor board. The crosspieces should be not less than ¥% in. thick, because one of them is to have a hole bored through it for receiving a locking pin. The lid fits down inside the box, and is held in position by corner blocks at the rear end. The front end is Modern Mechanix and

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eans ‘Oable or Workbenc The motor is mounted on a plywood bottom board, which is mounted in turn on two crosspieces. Mount the fan blades on the brass disc in the positions ‘shown here. The disc attaches to the motor shaft by means - of a collar, to which it is riveted. Note blade curvature. supported by a semi-circular metal guard that is fastened in front of the fan blade. ` In the.rear end: of the crumb eater cut out a decorative design with a jig saw. The openings are to permit air to escape, and are covered with a porous cloth that catch- es dirt but lets the air pass. Cut, for the bottom, a piece of plywood the exact dimensions of the lid, with the ‘exception that it is about % in. shorter. ‘This is to create a slit of “mouth” for the Sweeper, at the front end. "Next, make a block long enough to extend back from the slit to a point directly below the rear edge of the motor board. Then cut in: it the V-shaped notch shown in the drawings. Next, cut a piece of sheet brass ‘of such size that it will extend from. the _ Smear the vacuum cup with glycerine to strengthen grip. Inventions for May HOLE FOR LOCK PIN The top of the crumb eater is re- movable for dumping out debris col- lected in the bottom compartment. na go? The top is held in place by locking pin shown above. The furniture slides on bottom do duty as wheels for the "eater" and hold the box correct distance above surface being swept. inside surface of the front end of the box to a point 1 in. from the point of the V, and will go completely across the box from one side to the other. Tack this in place. This assembly, when the bottom is fastened in the box, forms a converging air passage from the slit to the center of the fan. After the lid is adjusted so that it fits snugly but does not bind, hold it in place (Continued on page 142) Making Rubber Vacuum Cups Stick UBBER vacuum cups have a way of los- ing their grip and thus becoming al- most useless. A way to restore their youth- ful condition .is to smear them with a generous quantity of glycerine, giving especial attention to the edges. Such treat- ment will improve their flexibility and also their air-tightness. When stuck on a smooth surface they stay put much more firmly than if left dry. Apply a fresh coat of glycerine every once in a while. 127

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Junked Motor Makes ‘Windmill ‘Water Pump center” N BEARING PUMP SHAFT AND YOKE STUFF WITH GREASED WHICH WHOLE ASSEMBLY IS FREE TO TURN Here is the pump in operation. The vane is constructed from corrugated iron sheeting reinforced with band iron. The lower end of the connecting rod attaches to the pump shaft which comes up through the axle housing. WINDMILL constructed largely from junked automobile parts is keeping George B. Evans, of Lake Worth, Florida, supplied with water. The mill pumps wa- ter from a well into a tank from which it is drawn as needed for watering a garden, and for household use. In constructing the windmill, the builder procured an old four-cylinder automobile engine. He broke the block in two and mounted one-half, containing two cylin- ders, in an inverted position on the large end of a rear axle housing that formed the pinnacle of the windmill tower. Then he cut the crankshaft in two and mounted one piece on the engine block. A connecting rod, fitted with a large grease cup for lubricating the bearing, was placed on the shaft, and the other end of the rod attached to the pump shaft that 128 | CROSS ARMS | OF FAN CAN Í BOLT TO FITTED WITH SWIVEL TO ALLOW THIS ASSEMBLY TO TURN WITHOUT TWISTING LONG BLOCK ——SHAFT— REAR AXLE BEARINGS ARE LEFT IN PLACE SEMI CROSS-SECTION OF MILL_ASSEMBLY Close-up view of the mill at the top shows how vane is attached to the motor, while below is seen the half-section of the motor which is utilized. Drawing illustrates assembly of the parts. Both the cylinder block and the crankshaft are cut in two. comes up through the axle housing. The wheel, built up of sheet steel segments made from the body of the car, is mounted on the projecting end of the crankshaft section. The vane was con- structed from corrugated iron sheeting re- inforced with band iron. Evans found uses for other parts of the. old car. One of the wheel rims encircles the wood tower near the top, making a strong brace. The other half of the engine block, crankshaft, connecting rods and the like were sold to a neighbor for use in another windmill. This Florida windmill, operating a small pump with a 4-in. stroke, can fill a 600-gal- lon tank in two hours. The only attention required other than regulation of the vane is an occasional greasing. Varnish, paint, etc., no matter how old and hard, may be softened in a few minutes so that scraping is easily done, by applying the following mixture to the surface. Water glass, 5 parts; soda lye, 40° B (27 per cent) 1 part; ammonia water, 1 part. Mix thorough- ly, apply with brush, and allow to soak in. Modern Mechanix and

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Hobby Forse Rides With Lifelike Gallop oo o ooo i] INNER TUBES BANDS —- Ring passes through | 3/16 in. hole % in. from edge, 1l5 in. down from the cleat. Dimensions of all parts for horse are seen here. Joints are reinforced with glue. Cut out the head to this shape and bore hole for the handlebar. Insert shows the 3x5 hardwood block which anchors the rubber strips to the baseboard. Lag screws are one-half by two and one-half. yIDING this home-built hobby horse is exactly like riding a real flesh and blood animal—the motions are almost the same. Six rubber strips 1% in. wide and 8 feet long cut from a heavy dis- carded inner tube provide the animation and counteract the weight of the rider as he moves from one extreme position to the other. Dimensions of all necessary parts are given in the accompanying drawings. Note that the rocker arms are of oak. These are 2 in. wide at the bot- tom and 1% in. at the top, have their ends rounded, and are set 14 in. apart at the bottom and about 12 at the top. Adjusting the tension of the bands might prove a delicate job. Start the 214 in. lag screws through the holes in the anchor blocks, which are centered at the ends of the frame bottom, and draw the ends of the rubber strips underneath until each are of.equal tension. Then turn the screws down tight. Each set of strips should be barely taut. Suit yourself about the color scheme. If there is any rubbing at.any point apply a little grease, - especially at the ends of the rocker arms. Inventions for May Here’s how you ride the hobby horse—- your hands on the bars and your feet on the foot rest. 129

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DREAM House for «Gechnocratic c AGE Unusually attractive in appearance and design is the house built from plan No. 5-W-10, shown here. Its chief advan- tage is that you can leave development of the two extra bedrooms on second floor till later, when money is available. FTECHNOCRACY may, in its readjustment of gainful occupations and adequate pay therefrom, prove housekeeping as much of a job for men as for women. If that time ever comes man will demand a smaller house which requires a minimum of work. And that’s why the little house No. 5-W- 10, illustrated above, should appeal to men and women who want plenty of time for play. This house is not only good to look at externally, but in plan, equipment and labor saving it's a model from several points of view. First, it is a house that can grow. That's important these penny splitting days. You can finish the first floor; enjoy complete bungalow equipment and later, if you wish, you may finish the second floor, which is large enough for two extra bedrooms. Re- member that most buyers generally ask for three bedrooms. Study the plan. Note how every inch of space has been used to deliver. a larger amount of service. An inside fireplace is a stroke of economy. There are sixteen win- dows on the first floor—which means plen- ty of sunshine, light and ventilation. A spacious living room opens onto a din- ing room, thus increasing the apparent size of both. There’s a modernistic bathroom, an efficiency kitchen with plenty of cup- board space and two fine bedrooms on the first floor. In all there's à possibility of four bedrooms in this house. The house is frame construction. with shingle sidewalls and shingle roof. This is the least expensive type of construction. 130 HOW TO GET BLUEPRINTS AND. PLAN BOOKS A one-sheet blueprint of any house appearing in Modern Mechanix and Inventions maga- zine may be had for $1.00, postage prepaid. Two new plan books, “Homes for Newly- weds,” containing 32 of the latest ideas for low cost homes, and “16 Selected Homes for Lean Purses” con- taining time, space and labor-saving bunga- lows, may be had for 15 cents each, or both books for 25 cents, pos- tage prepaid. Address Home Building Bditor; Modernistic bathroom fixtures save Inventions. space and enhance charm of home. BED RM 12-0 * 10-9 “LIVING RM: 2l-o % 13-0 BEP fM 13-0 1411-6 S-Waro Floor plans for house No. 5-W- 10. Note how ev- ety available bit of space is utilized to best advantage.

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IDE A MOTORCYCLE —because it's wonderful sport—because it's healthful and sensible—be- cause it saves money, saves time, saves energy. Join the Jolly Riders in their evening spins, club runs, -and glorious vacations. Harley-Davidson enthusiasts ‘ali, eager to welcome you into their fraternity of sport. Nobody has a better time—and it costs so little! See for yourself how easy it is to own a Harley-David- son—how low its upkeep is—and how much time and money it will save you. Ask your nearby Harley-Davidson Dealer about his Pay-As-You-Ride Plan—and mail the Coupon for free literature. Ride a ARLEY- MAIL THIS COUPON ————————— ee HARLEY-DAVIDSON MOTOR CO. Dept. MM, Milwaukee, Wis, Interested in your motorcycles. Send literature, H E. DAVIDSON My age is [O 16-19 years, [] 20-30 years, L] 31 years and up, [] under 16 years. Check your age group. : : noe- ' À Thank You. for Mentioning Modern Mechanix and Inventions for May W hen Writing to Advertisers 131

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What Price Condition? RICE is a factor, as it bears on stamps, which concerns every collector. Cata- log values serve as a handy scale in mak- ing estimates of the dollars and cents worth of a collection, but it is a well known fact that frequently stamps sell for but a fraction of their catalog value. The answer, of course, is simple—the condition of the individual stamp has everything to do with the price it brings. Factors bearing on condition are number- less. For one thing, there is the matter of proper centering. Note how the Soudan stamp at the left below is cut into by the perforations along the right edge, and compare it with the perfectly centered ex- ample alongside it. Examples of a poorly-centered and well-centered stamp. A Brazilian Rarity EVOLUTION in South America has brought out a series of stamps from a “nation” new_in the world’s issues—the State of Sao Paulo. This is the great cof- fee-growing province of Brazil which re- belled against the mother country not long ago. Cut off from the central government, it devised its own stamp issues, one of which is reproduced herewith. Locally designed and printed, the eleven values of the issue are rather inferior in execution, but no less in- teresting on that account. When the Sao Paulists were subdued by the Brazilian government, the stamps were Officially recognized and per- mitted to be used throughout =! the republic until Oct. 31. Portrait of Christ on Coin NE of the few portraits of Christ ever used on a national currency appears on a Byzantine coin dating from 650 A. D., reproduced herewith. An additional fea- ture of interest is the fact that the coin is cup-shaped, the photograph showing the piece from what would be the bottom angle—i.e., the edges around the circle of the design’ are bent inward on themselves to shape a cup-like depression on the other side. The portrait of Christ is distinctly Byzantine in treatment; in fact, accus- tomed as most of us are to the conception handed down by reli- gious artists of the middle ages, the por- trait is at first glance difficult to recognize for what it is. Byzan- tium was the Eastern Roman Empire which oariad from 300 to Rare Postmarks in Find HIRTY thousand letters, accumulated in the period between the Revolutionary and the Civil War, were recently unearth- ed in the pre-revolutionary home of Nicho- las Low in New York. They were con- tained in trunks in an attic which had been walled up years before, and its ex- istence forgotten. News of this find, which is now being valued by a New York philatelist, will no doubt stimulate a rush on old houses which may have. sealed-up attics, on the part of the collectors. Since postage stamps were a compara- tively Jate development in the postal sys- tem, most of the covers found are franked with postmarks or with the signatures of (Continued on opposite page) RICHM'D. Oct 10 , 1795, In early Colonial days postmarks served as stamps.

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New “Delta” Scroll Saw Earns Thousands of Dollars for Puzzle Makers For spare time, full time, ot hobby—you, too, can use this remarkable new“ Delta” tool to “cash in” on tremendous demand for jig-saw puzzles. Starting with one saw, some “Delta” users have as many as 50 units going at full speed. Offers many other op- portunities for woodworking for pleasure or profit. Send Coupon for Full Details New and radically different from any Scroll Saw on the market. At 1,800 strokes per minute the “Delta” Scroll Saw has such perfect balance, such absence of vibration, that a pencil can be stood on end on the saw table without tipping over. This is the only Scroll Saw of this type on_the Market today that can pass this rigid test. Pro- duces smooth, accurate work. Has many special features. The New ''Delta" Scroll Saw can also be used for filing, sanding, and honing. 10-Day Trial ‘Delta’? Tools are always available Easy Terms iita Raat cithous the sient est risk. Satisfaction guaranteed. For full details of this liberal offer, also Easy Payment Plans and FREE copy of illustrated 1933 ''Delta'" Catalog, send the cou- pon below — TODAY | No obligations ! DELTA MFG. CO., 3775 North Holton Street Dept. M-533, Milwaukee, Wisconsin ee uM Umm GEM Wux x GER mA UEM "M l A Complete Line of Modern Motor -Driven Tools “Delta” Woodworking Units are available in a large variety of combinations, and at prices to flt all needs, The “Delta” line in- cludes Jointers, Circular Saws, Band Saws, Scroll Saws, Wood- turning Lathes, Drill Presses Boring, Routing, Sanding, and Mortising Attachments, and & complete line of accessories, DELTA MFG. CO., 3775 N. Holton St. Dept. M-533, Milwaukee, Wisconsin Please place me, without obligation, on mailing list to receive the FREE 1938 “Delta” Catalog of Quality Woodworking Tools. l Also send full details of your 10-Day Trial Offer and Easy Pay- I l ment Pians. l I WA Send Coupon for Nate, ccce oceca tenaces testea eost Agel. i FREE Address... esses. eam etie cenae rere tS CATALOG uU ————————— State... sss. HOBBY | DEPARTMENT | HAENEL “100 SHOT” REPEATER local postmasters. A series of typical postmarks $ 4-95 is reproduced herewith, together with a letter s bearing the signature of Gouveneur Morris, who, | Latest Model 1983 Haenel repeating + * , lon, as a member of the Continental Congress, had | Pte Sfuedp, mati eher materie. the privilege of sending his mail free. Accurate for target. Powerful for small game. Blue or Nickel finish, shoots Postmarks date back to 1692, when the Massa- E. B. steel shot nee 18 oz. Price with 80 ol $ t shots Hree - = . lepos on C.O.D. x Å chusetts General Court enacted legislation com- Catalog Colts, S.&W. Rifles, Binoculars, etc. pelling every letter received at the postoffice to HUDSON SPORTING GOODS COMPANY be marked with a print showing the date of re- | M-52 Warren Street New York Clty, N. Y. WONDERFUL | NEW INVENTION SOLDERING IRON AND // BLOW TORCH IN ONE Pays for itself in one job! eeds no pump or pressure System — no stove — no char- coal—no separate blow torch. Burns an hour at less than 14 cent for gasoline. AGENTS’ OFFER WriteforSpecialOffertoagents. The Justrite is an ideal proposi- tion for either main line or side line — full time or spare time. JUSTRITE MFG. CO., j 2047 Southport Avenue, y Chicago, Ill. This old cover bears the signature of Gouverneur Morris, who, as member of the Continental Congress, had the privilege of sending mail free. Frank is in upper right corner. (Continued on page 134) uper Thank You for Mentioning Modern Mechanix and Inventions for May When Writing to Advertisers 133

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Students Individually Instructed Learn Autos IN LOS ANGELES A FEW SHORT WEEKS AT NATIONAL AND YOU'RE READY FOR A BIG PAY JOB! For 28 years National has quickly helped men get ready for good pay jobs, stead: lo; t in th. fitabl iste Relat” org zora new thes ayer before Bont | SPECIAL worry about previous experience or whether you're too i old or too young. e” in yon by * actual shop” High Speed methods on newest equipment--late model antos, Larg- Diesel Engine est School In West. Course — now belng ADDED Send for Free Book Complete Practical Auto Instruction Course trains you In every branch of auto repair qualify- Ing you to run your own shop or accept gi job. Don't worry about money. We'll help you secure part-time job to earn room and board while earning. Unlimited free Employment Service to graduates. Coach raflroad far allowed to Los Angeles. NATIONAL AUTOMOTIVE SCHOOL Los Angeles Dept. MMA-5, 4006 South Fi, St. Send Free Auto Book and Special offer. Name.. LIGHT PLANE BUILDERS—The 1933 Flying Manual is 50 cents postpaid. 529 S. Seventh Street, Minneapolis, Minn. Now You Can Have A New Skin In 3 Days’ Time! Visible Ugly Blemishes Vanish! GET THIS FREE —and learn that what wes considered impossible before—the removal of pimples, blackheads, freckles, tan, oily skin, large pores, wrinkles end other defects in the outer skin—can now be done harmlessly and economically at hore in three days’ time in many instances as stated by legions of men and women, young and old. It is all explained in a new treatise called “BEAUTIFUL NEW SKIN IN 3 DAYS” whieh is being malled absolutely free to readers of this magazine. So worry no more over your humillating skin and complexion or signs of aging if your outer skin looks soiled and worn. Simply send your name and address and name ihe skin blemishes which trouble you most to MARVO BEAUTY LABORATORIES, Dept. 343, No. 1700 Broad- way, New York, N. Y., and you will receive this amazing new treatise by return mall in plain wrapper, postpald and absolutely free. If pleased, tell your friends about it. HAIR Trouble? Learn the one correct and harmless way to remove all dandruff and any itch from the scalp; how to stop excessive hair loss, and how it is possible to grow back the lost hair. A famous scientist explains everything in a free booklet. "Write LINDAY, 36! W. 29th Street, New York City HOBBY DEPARTMENT (Continued from page 133) ceipt. The use of postmarks brings to mind the realization that letters had to be mailed directly at the postoffice, involving a cash transaction with the postmaster. Not until the postage stamp came into general use were such conveniences as mail- boxes on every corner made possible. What a Shekel Looks Like HE slang habit of using the word “shekel” as a synonym for money has made the term a familiar one, but not many people have actually seen a real shekel, or realize that it was a Jewish currency which has gained familiarity through Bible references. Note that there is no living im- age on the coin, the Jews obeying the injunction against “graven images” even in their coins. Jewish silver shekel which passed current in 133 B. C. Note .absence of graven im- ages on coin. Explanation of Nic Sprank's Oddities of Science HIS is the manner in which ice can be made in a red-hot vessel: Heat a platinum burner red hot and pour in some sulphuric acid, which will be found to become completely fixed in the hot crucible. Not a drop evaporates, since it is surrounded by an atmosphere of its own, and does not, in fact, even touch the sides. A few drops of water are now introduced, causing the acid to come in contact with the sides of the crucible and to fly off in sulphurous acid vapor so rapidly that the heat of the water passes off with it, causing the drops to fall to the bottom as ice, where, of course, they are swiftly melted unless removed immediately. The rate of vibration of a pendulum varies according to the pull of gravity; consequently the rate of swing can be computed into the height at which the pendulum rests. Two 500-lb. weights, placed one on top of the other, will not weigh as much as a single 1,000-Ib. weight of proportionate shape, since their cen- ter of gravity is further from the center of the earth, and weight varies with that distance. Since a boat displaces an amount of water exactly equal to its own weight, it is obvious that a vessel passing over a canal carried by an aqueduct imposes no additional weight on the structure. In chemical laboratories, water has been cooled to —90? Centigrade (—130? Fahrenheit) without freezing, as-long as it was kept abso- lutely without motion. At these temperatures, however, if the water is slightly jarred, it will instantly turn to ice. The speed of high explosives has been proved I —————————————— out in the manner described by tests of the Brit- Addresh ocpusitene p DUA M HEU URERad teres Seven ee eaioes ish Government Ordnance Department. «eui 134 -— 12 Thank You for Mentioning Modern Mechanix and Inventions for May When Writing to Advertisers

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When Gold Is Found, Sluice ’er Out! (Continued from page 50) with heads not driven down flush. Easy pulling nails may aid clean-up. Where gold is very fine, burlap or carpet or cocoa mats sometimes are substituted for ordinary riffles, either through- out the length of the sluice or at the lower end, the mat being held to the bottom of the box by wire netting. Worn-out sluices sometimes are. burned and gold washed from the ashes. Mercury can be put back of riffles where “flour gold” is found. Care must be exercised or the “quick” will be washed away or lost at clean-up. Several sluices can be rigged up in series if necessary. Sluices run up to 5’ deep and to 6’ wide on larger op- erations. On smaller sluices the hopper and screen sifts out and rejects larger worthless pebbles; in larger sluices this primary sorting is not so necessary. The “Long Tom” is an adaptation of the sluice. The whole first section is a washing- sorting box. Finer materials are washed through the screen at the lower end of this section while larger, worthless rocks are raked or shoveled out. Often a second riffle section is placed be- low the first, sometimes a third is used. By panning the “tailings” below sluice or tom you can determine if the outfit is catching all the gold. When gold is fine and a tom is used the lower riffle boxes sometimes are lined only with mats. These can be washed out in a tub to re- cover the gold, or burned carefully. The tom requires less water than a sluice and two men can handle up to 6 yards per working day. Sluices are preferred to toms if there is enough water. Where water is limited the cradle or rocker is used. It has a capacity of 3 to 6 yards per day if worked by two men and requires not over 100 gallons of water per cubic yard of earth handled. Sticky clay and cemented ma- terials should be soaked before being put through the rocker. The cradle or rocker is a trough or box mounted on rockers set crosswise beneath the box, and combines some of the washing motions of panning with sluicing. It is a sort of selec- tive, slow-motion sluice. Above the rocker box is a screen hopper where first washing and sort- ing takes place, and between the box and the hopper is the apron, a piece of canvas or carpet in a frame, with enough “sag” in it to form a preliminary pocket designed to catch the heavier mineral particles as the screened materials are washed down from the hopper. In operation the hopper is filled about half full, water is dipped in or slowly run in, and the screened material falls from apron to box, where it is subjected to riffle action augmented by the rocking motion. Extra long rockers with mats are needed for fine gold. In building this outfit smooth lumber is used and a single board is used t9 form the bottom. Slope of the rocker from hopper-end to lip varies but usually is around 2" for each 3' of length. Spikes in the rockers or pegs from the base fitting into rocker holes, keep the rocker from slipping “down-hill.” Always keep a check by panning to be cer- (Continued on page 141) d Thank You for Mentioning Modern Mechanix and Inventions for May When Writing to Advertisers

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GASOLINE MOTORS rr Boat and Airplane Model Builders Two Cylinder—76'^ Bore, 94'' Stroke—R. P. ML up-to 4500. ONE CYLINDER MOTOR FOR AIRPLANES Weight. 7% oz., Bore, %’’, Stroke, %’’, Coll Weight, 5 oz. Weights subject to allowances for casting variations. A real opportunity for the model builder who believes in making the most of his dollars. Send 10e in coin for complete information, including sectional view drawing of one cylinder motor. POWER MODEL BOAT & AIRPLANE CO. Dept. G-1, 134 SO. CLINTON ST. CHICAGO, ILLINOIS For airplanes to suit, the one cylinder motor see Carlson Model Airplane Company ad on page 23 SECTIONS- 3r. LONG See Miles Away! Distant people and objects seem close. Over 3 ft. long, brass bound, Made in Europe. Bbls. of fun. Thousands pleased. y On arrival pay With Send No Money! Postman special FRE Order price, only $1.75, plus postage. Two for $3.25. | Strong leatherette (Or send price and we pay postage.) Satisfac- Carrying Case and tion. guaranteed or money back. Send today. | Solar Eye Piece to Bargaln House, Dept. 66, Des Molnes, lowa C | RTOON YOUR WAY ^ ccess/ f COPY - LEARN TO ORIGINATE! RAYE BURNS will teach you HOW to CREATE ORIGINAL CARTOONS at liome giat Pau | = 85 SELL! Course has 26 lessons and 600 Send name and address for free o trat Ouly- RAYE BURNS SCHOOL, Degt. F-X, Box 2194, CLEVELAND, OHIO NEW CATALOG 16 AND DISCOUNT SHEET For Bollers, Gas, Steam Engines, Cast- ings for 40 kinds of these Engines, Pumps, etc., Electric and Water Mo- tors, Gears, Materlal, Piston Rings, Miniature Bolts, Nuis, Gauges, Valves, Rails. Blueprints free with Castings. Send 25c for Catalog 16. Refund on Ist order. HOWARD ENGINE & MFG. CO. 417 N. Ashland Ave. Minois Chicago di 136 Explain Accidents With Models (Continued from page 88) decides to pass to starboard, and sounds two blasts of his whistle. The other captain thinks this is merely the fog signal, and wants to pass to the opposite side, so he issues one blast. Skipper A, hearing faintly because of the wind, takes it to be two blasts in answer to his own, and then the fog shuts in. Both vessels have "turned out" for each other in the same manner that the fabled drunken Indian turned aside to "let the bridge go by" in his speeding auto. Both unwittingly bear down on each other, crash in the fog, and one sinks. Clearly someone is at fault, and only in a maritime court could such a case be tried. Another recent happening on the high seas is the matter of the burning trans-Atlantic liner Atlantique, which recently took fire and was abandoned in mid channel in the English Channel. Laws of the high seas say that any vessel saving another from destruction is entitled to salvage damages. Further, any vessel salvaging an aban- . doned vessel has full claim on her. The Aflantique was blazing merrily away, her fine new decks a holocaust of smoke and she was drifting at a rapid rate toward the Cardiff cliffs of England. If she beached there, she would belong to the Pagi who could salvage about $2,000,000 in stee Dutch trawlers hooked on, at the same time that French vessels came to the aid of their sis- ter of the French Merchant Marine. Both Dutch and French towed valiantly in opposite directions. And both, for the moment, according to sea law, were right. The French finally solved the problem by put- ting the Atlantique's captain back aboard thus making it illegal for the Dutch to claim her, and the captain accepted salvage tows from the French vessels, nailing a French flag to a jackstaff to in- form the Dutch trawlers of this Smart work, and it required the knowledge of the "rules of the road" on the high seas, where there are no sign posts, and the traffic cop sits at home a thousand miles away, judging cases on the merits involved in desk-top collisions with models as shown in the diagrams and photographs. Talk With Continent on Transmitter (Continued from page 125) slight shifting will alter the frequency relation. of the turns. The tank tuning condenser can be any suit- able receiving variable condenser of approximate- es capacity, with a pig-tailed rotor if pos- sible The diagrams show clearly the construction of the tank and antenna coils. The tank coil should consist of five full turns of 1⁄4 inch copper tubing wound about 2% inches in diameter, spacing the turns l4 to 5/16 inch apart. Bend each end out in a line and to their ends solder a large soldering lug as shown. With a tape, measure the exact length of the tubing and strike a point midway for the center-tap, soldering a wire at that point. Unlike the usual method, the antenna coupling Ies Thank You for Mentioning Modern Mechanix and Inventions for May When Writing to Advertisers

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Talk With Continent on Transmitter coil is inserted inside the tank coil, coaxilly with it. Wind this coil of any heavy copper wire, No. 10 or No. 12, and 1-inch in diameter. Seven turns is about right but not necessarily an exact num- ber. Make the coil slightly longer than the tank coil and bend the ends in a right angle relation to it and solder lugs to these also. Both coils are to be mounted on small Bee-hive insulators that stand above the base about 1% inches. In lieu of these small wooden supports can be used or even spark-plug porcelains can be made to do the trick. All wiring is done under the base using any suitable insulated wire of 18-gauge or larger. All connections should be well soldered and taped to prevent short circuits. The tank and grid coil center taps connect directly to Fahnestock clips bolted to the base as shown. These are then wired into the circuit. Follow the wiring diagrams (Figs. 2 and 5) closely and you can’t go wrong. Where “ground” is shown it is the same as B minus. In the matter of the grid coil; eight turns to a side may or may not be proper for the midget you are to use. If the radiation cannot be altered by operating this condenser, then take off or add one turn at a time to each winding until the con- denser has its effect. This can be noted by watching the milliam- meter. With the feeders disconnected, resonance of the grid with the plate can be determined by a dropping of the ammeter needle. In the matter of sockets once more. A five prong socket is marked H-H-P-G and K. For the use of pentodes ‘with no cathode such as the 247 and 233 the G terminal is the control grid (connected to the grid-leak) and K terminal is used for the screen. P is plate as usual. In the case of six prong sockets the tube cathode is connected to the K terminal of socket as intended and the two grids have separate terminals marked for them. Always shunt the milliammeter out when key- ing otherwise the meter needle may be strained out of position. If you have no milliammeter you can use a flashlight bulb in its place to indicate resonance. Shunt out the light when keying or the note will show a chirp makjng it difficult to copy at the receiving end. For power a single power pack or the required voltage can be used or two separate ones for plate and screen voltages. In the latter case say a 300 to 500-volt pack is used for plate supply and a 135-volt B eliminator is used for the screen volt- age. In this case connect the B minus of each one to the B minus clip and their high power ter- minals to their respective clips on the transmitter. Filaments for the 247s, etc., should be from a suitable filament transformer but for the 233s the filaments can be lighted direct from a 2-volt bat- tery. Any suitable antenna system can be used with this transmitter. Simply connect the feeders to the two clips on the antenna coil after the trans- mitter has been tuned to resonance and then tune the feeder system to it. This may throw the set slightly out of resonance after which it should be carefully retuned. Like any transmitter; this one must be licensed by the Federal Radio Commis- sion and you must have a license to operate it. 1 9 mm CO cyÓ Thank You for Mentioning Modern Mechanix and Inventions for May When Writing to Advertisers NO HOUSE-TO-HOUSE— Experience Unnecessary— No Costly Machine to Buy The new coast-to-coast food hit. You work at home, chips come to you already made. Simply drop into hot grease and they're ready to eat! No complicated work, no experience, no failures! Positive proof of opportunity to make up to $30 first day. Distributors now making high as $60 to $300 a week clear! Not a machine. No need to buy special equipment, Stores do your selling for you. NO LOSS on unsold goods—we take care of it! A phenomenal success! 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Ask for Catalog No. BAY CITY, MICHIGAN THE ALADDIN CO. FORTLAND, OREGON 137

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+ Hidden, denied, but not lost, is the miraculous wisdom of the ancients., Their methods of mental power in achieving SUCCESS and MASTERY IN LIFE are avoiloble TO YOU. Write for a FREE copy of the “Wisdom of the Sages” and learn how to receive this rare knowledge, MAKE YOUR LIFE ANEW, SCRIBE: P.D.O.. ROSICRUCIAN BROTHERHOOD SAN JOSE CALIFORNIA g 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. Booklet sent free, and without obligation. Write for -your copy today. ELITE PUBLISHING CO. Dept. G 214 Grand St. New York, N. Y. MIND READING MADE EASY «By this new fas- cinating method. Baffle and mystify strangors and friends at parties, banquets, etc. Twenty- five cents brings booklet with full instructions by return mail. HOLLYWOOD ORIGINATORS 3879 W. Sixth St., Dept M los Angeles, Colif. EARN UP TO $25 A WEEK, OR MORE Grow Mushrooms in your cellar or shed. Big demand. Expe- rience unnecessary—we tell you how. Illustrated book free. Start NOW-—write today. AMERICAN MUSHROOM INDUSTRIES, Ltd. Dept. 630 Toronto, Ont. Full Size 2" drawing of Gee Bee FR E E Supersportster & Heath Parasol a with introductory issue of new magazine for &à — ied model builders, x CLEVELAND MODELMAKING NEWS z & Practical Hobbies Everyone's talking about it! Published by Cleveland Model & Supply Co., Inc. Plenty of pictures, drawings and simplified steps about building authentic models of airplanes that fly, ships, trains, complete railroads, landscaping, etc., ete. Rush 25c (no stamps) at once for your copy (may be applied against subscription). Don't delay. Issue going fast. Send your 25c NOW. (Foreign, 5c extra.) Cleveland Mcdelmaking News, (866-LE, W. 57th St., Cleveland, Ohlo IT COSTS YOU NOTHING UNLESS IT GROWS YOUR HAIR à Ellminates Dandrutf...Stops itching Scalp We refund every cent of your money if you ure not more than satisfled. Nothing to lose. “The Bald Spots are Covered with New Tair,” writes E. I., among many others. Send NOW for FREE information in plain sealed envelope without any obligation. JACK SLAVIN SLAVIN CO., Dept. A-158 Treatments 209 Post St. San Francisco, Cal. THIS BOOK JACK SLAVIN fter Treatments NICKEL PLATE EI Your Auto, Faucets, Tools Without removing parts Outfit connects to your battery, $3.00 prepaid. Plating Powder plates heavy by rubbing. Half pint $1.00 prepaid. GUNMETAL CO. Ave, S DECATUR, ILL. oy 138 Building Cabinette Cruise Trailer (Continued from page 101) erratic and hard on tires. Instead of turning the corner the trailer will be dragged around it, and the whole thing is unscientific. ` The way to get the right trailer tongue is to take your car to some airfield, or other wide place where there is dust enough to see the tracks. Cramp the wheels and run the car in as tight a circle as it will go. This will make tracks as shown in the drawing, Fig. 9. Now bring on the trailer. Run it right in the tracks of the car on the same curve. When it approaches the car to the point where the tongue, either real or projected in an imaginary line, hits the towing bar, there is your tongue length. Anything different will result in diffi- cult, wasteful towing. Fig. 10 shows a shock- absorbing tow hook-up to be placed on the car itself, Body Now the body can be put on the trailer, with the underslinging and the towing arm made ready. White oak stringers, 2x4’ are used to mount the body on. These are bored and coun- tersunk for %” carriage bolts which go right through the frame. See Fig. 11. The last one toward the rear must be a U bolt going around the stringer, as there is too much weight hung cantilever at that point to risk cutting the stringer through for a fastening. On these stringers are bolted, with quarter-inch carriage bolts, the floors, of 2x2 white oak. On these floors is laid 34" t & g fir flooring. In lay- ing out, allow 9 inches wheel box space, and shorten the flooring and the floor beams at this point accordingly. With the floor built upon the trailer, the side framing and end framing are put up. See Figs. 15 and 16. The framing for such a body is sim- plicity itself, and the drawings specify all the required sizes of 1"x2" white oak stanchions, into which are mortised window clamps and roof beam clamps. See Figs. 14 and 15. These clamps are all fastened with two quarter-inch carriage bolts at each mortise, and are tied with cool rolled 16-gauge angle plates at the ends. Always use bolts in this type of construction, and rivets where specified. Use no screws. They work loose. The roof beams are steam bent, and it is sug- gested that you let your local blacksmith attend to this matter if you cannot handle the work as he is apt to have a steam box for bending felloes. Otherwise they can be cut to the crown of 6" in 6 ft. on a bandsaw, though this entails slight waste. The roofing is of ordinary 14’’x4” beaded cedar ceiling. This as in box car practice is nailed on with galvanized shingle nails. Canvas laid in paint and turned down with proper half round molding at the edges is used. The sides are ceiled with the same material. Or if you want to be real fancy, you can lay chicken wire over the frame work, pad it a little and use Fabrikoid as a covering, though this is expensive. The windows are spaced as shown, and a de- ue Thank You for Mentioning Modern Mechanix and Inventions for May When Writing to Advertisers

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Building Cabinette Cruise Trailer tail shows how both frames are cut for accom- modating screen or window panes at once. Right hand drawing, Fig. 15. The door in the rear end is sliding, made of a panel of 34" fir with plywood panelling. It slides instead of swinging, as swinging doors jamb, and take a lot of room. Don't use the 116" door shown on the drawings. Equipment The putting on of the ceiling will complete the body, and the trailer is now to be painted and furnished. The matter of beds is one which was given a lot of study, and it was decided that the best thing would be to use the type of bed known as Studio Couch, which can be had at any furniture store for less than 20 dollars completely equipped. These are best disposed as the layout shows in the arrangement plan. Up in the right hand forward corner, a small closet is made to accom- modate a water closet of the light, cheap kind, and also a'folding wash basin with drain to a : water boiler which is slung below the chassis. (Not shown.) This boiler can be equipped with | a valve so that after breaking camp one can drive to some side road for a minute, and open the valve, disposing of the sewage off to one side of the road. This will be found efficacious and unobjectionable and well worth the trouble. A water storage tank, in the form of a hot water boiler cut in half is hung above the sink, and piped to the water closet, to the wash basin : and to the sink. An outlet tap and a hose are carried, and at any filling station the hose can : be connected, the tank filled, and you can be on your way. ,, The matter of clothes storage is important, and if disposed as shown you will have room for guns, hunting equipment, or traps as well as for your store clothes and Sunday Go to Meetin’. . The pantry doesn't have to be large in a thing like this. Only the staples are needed, and you'll find you'll be buying nearly as many meals as you get yourself. An Albert Lea two-burner stove of the four dol- lar kind is more than adequate to heat and cook with and a pail and a mop and a broom complete the job. You are ready to move in, hook up and be off to the lake, or the mountain, and have no hotel bills! It really is becoming the smart thing to do. And this is the clear rig to try it in! Roosevelt Medal T? HONOR the new President, the Philadelphia Mint has prepared a-Roosevelt inaugural medal designed by Paul Manship, famous sculptor. Roosevelt’s portrait will appear on the obverse side of the medal, while on the reverse appears a full-rigged ship with an angel directly below it. The ship is tied in with a quotation from Long- fellow’s poem on the Ship of State—an especially appropriate design considering President Roose- velt’s fondness for sailing the sea in ships. Col- lectors can purchase the medals from the Phila- delphia mint. STOP BALDNESS New. 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I've already Bet of Soest SILE helped meny fellows make $20 to $60 and MORE STRINGS with illus | Finan ot it trated reaper Eu friend... your ht m e, clear, LPRE Campbell, Callf. or simis rer M dm ga . now make great opportunity ACK m erts tor FREE strucHons, AL! - cash thís season TD: 85e. ist? W. A. BICKEL, 803. W. Madison = : eat 23.88 ' CHICAGO, ILLINOE $299 woop TURNING LATHE You can turn candlesticks, lamp bases, cigar holders, spindles, vases, etc., etc., on “The Giftmaker’’ 2- speed wood lathe. Runs from your treadle or fractional H. P. molior. Fills need for inexpensive, smooth running lathe. Both face plate and driv. Ing dog attachments included; also Ilet cf 50 artleleg possible te ornon the Gift" i ostpaíd for $2.00, C.O.D., SEES oateldo U. S. A., $2.50. J. & H. Metal Products Co., HOW-TO-BUILD 20 BOATS — On All Newsstands for 50 Cents eh "The Giftmaker"" ; Specifications: 13’’ long overall, 6” high. Takes pieces up io 8'^ long, 234"' in diameter. All metal construction. Fully adjustable. 480 St. Paul St., Rochester, N. ¥. ee ROY Thank You for Mentioning Modern Mechanix and Inventions for May When Writing to Advertisers 139

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pou | Electric Starter,-Easy to PB 258 Lbs. (| Install S “Light Four BY o C] Jt AY” 4 cylinder, 4 cycle, 8.24 | xe hp. Marine Motor, with fll pressure lubrication, fuel pump, thrust bearings, starter and generator, Price as illustrated, $198. Extra for > clutch and reverse gear, $100. larger size Model "Four-208", 10 to 39 B h.p. Weight, 400 Ibs., $266, Extra for clutch and BB S reverse gear, $100. Also "Four-35B", 326x414, $995. hp. ; Ae Fours, Sixes, Eights and a 5 hp. Single § Gray builds a complete line of both Heavy-Duty and Racing QW. Engines, providing exactly the right power for avery erker, rune, . bout, work or fish boat, and auxiliary up to 60 feet. Grays ares used by more stock builders than any other moke. E Tell Us About Your Boat GRAY Marine Motor Compan £612 E. Lafayette Ave., Detroit, Mich, U.S.A. iEn $449 Jig Saw Plus Set of Adapters and 12 Assorted Jewelers' Blades from .006” to .012" in thickness. Adaptors enable you to use the finest jewelers’ blades specially de- signed for puszle making. Saw has V-pulley for your treadle or motor. All metal con- struction, 15” long, 9” high, 614” table, Sent postpaid on re- ceipt of $1.49; C.O.D. $1.74; outside U.S.A. $1.84. FREE booklet “Make Your Own Jig Saw Puzzles” with every saw. SPECIAL DEAL: Complete Jig Saw Puzzle Outfit, including (1) Jig saw, adapters , 12 blades, and booklet as above; (2) four pieces of }4 in. bass plywood each large enough for a 200-piece puzzle; (3) four full color Pictures: (4)_ six fine ju saw blades postpaid all for $2.35; C. O. D. $2.60; outslde U. S. A. $2.70..4 pleces of Qrgood g pictures and 6 blades oniy---postpaid---31.00; C. O. D. $1.25; outside J. & H. Metal Products Co., 480 St. Paul St., Rochester, N. Y. 5-150 h.p.- TODAY * The Puzzlemaker'* WE ARE WORKING FULL TIME NO DEPRES- SION WITH US METLMACHES — THE MODERN MACH What is METLMACH? It's a mach made of metal that will not urn up, no burnt ends or ashes; one mach can be lit 1000 times or more; positively water, ratand child proof. Seemsimpos- sible butit'strue. Send $1 for 15 METLMACHES with display easel, sell them for 10c each and 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 Plans for “Scram” (Continued from page 119). the bottom (two thicknesses of 36" stuff). The piece next the chine is cut to shape. It can be held to the boat for fitting by Clamps padded so that the wood will not be marred. Flat head brass screws, 34” No. 7’s are used. They are spaced about an inch apart along the stem, and about three inches along the chine and batten. Holes for guiding the screw, just a trifle smaller than the threads, are drilled for each hole with a small breast drill or a Yankee Mr. Punch, The screws are soaped with laundry soap to avoid twisting the heads off and to make for easier driving. Each plank is then fitted against the neighbor this way. Along the chine the screw heads are set just a trifle lower than flush, and at the stem and on the frames. The batten seams are screw fastened from inside, using 34" No. 6 round head brass screws with two brass washers under. This fastens the batten seams blind at about 3” intervals, and does away with difficult finishing on the outside of the hull. When the topside planks are all on the job looks like the photo on the bottom of page 118 and the top of page 119. - Bottom Planking The bottom planking, strips of 38" by 4" width spruce, is laid on. Just tack it with copper tacks, and where the frames have some concavity for- ward, screws can be used. You see, when you put on the outer layer of 38" mahogany the screws you use in this outer layer will also fasten the inner layer. This will be a good month's work in spare time if you are working it that way, and must suffice for this month's discussion. Next month we'll finish the boat and the motor too. BLUEPRINTS OF “SCRAM” Although all the details for the construction of Scram will be run in subsequent articles, we are now selling complete sets of blueprints for this wonderful little flyer at $3.00 the set. All dimensions and ma- terial details are covered in the plans, which come in one long roll. If you want to get started without waiting for the succeeding issues, get these prints and get going now! Address Blueprint Department MODERN MECHANIX AND INVENTIONS 529 So. 7th St., Minneapolis, Minn. oahu 140 Speed-boats L. W. FERDINAND & CO. 597 Albany Street, Boston, Mass. are made watertight with Ferdico-Jeffery's Waterproof E Marine Products TENACIOUS—RESILIENT=DUR ABLE Used on craft large and small for more than 80 years Send for free booklet, “Weak Spots” Thank You for Mentioning Modern Mechanix and Inventions for May When W riting to Advertisers

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When Gold Is Found, Sluice 'er Out! (Continued from page 135) tain you are catching the gold. And as you wash out rough material in the hopper of any of these outfits, keep alert for chunks of quartz containing free gold; that might indicate a lode mine up-creek. : These are simple, low-cost hand-operated, home-made pieces of placer working equipment that increase your efficiency from 6 to 12 times above panning. Your original prospector’s out- fit will cost less than $5; these machines should not cost more than $15 more. On $1 ground two men can make expenses or better if they are willing to work at sluice, tom or rocker. One important warning; always be sure you are to true bedrock, for the richest gravel is right atop the rock and pockets or old crevices overlooked by early miners may be the richest spot on your claim. In our next article we will give information regarding the low-cost, highly efficient, portable, ready-to-go outfits called “placer machines” which will double each man’s capacity and effi- ciency over cradle, sluice or long tom. One such machine has a record of producing about $1,200 per. month in rich ground. We are going to give ihe information regarding these machines be- cause the man who has cleaned up a little "stake" by pan or sluice can take another step | ahead in building up to good returns by using some of his capital to increase efficiency of each worker. Also in the next issue we will tell of the "dry washer" used on placers in the desert. Grow “Blood” for Human Health (Continued from page 81) Dr. Schertz’s extraction of pure chlorophyll is the result of 12 years of experimentation. He has produced this essence of concentrated sun- shine—so closely aligned to the blood itself— on the largest scale ever known. His apparatus consists of an electric drying oven, a “ball mill,” a “screening machine,” a silver-coated separator of the super-centrifuge type, and a group of large funnels, pyrex tubes, almost twice as tall as a, man, and numerous flasks. "My very first step,” explains Dr. Schertz, “is to select a desirable kind of leaf or plant. The kinds of plants most used in my tests, are blue- grass, spinach, cow-peas, or stinging nettles. “My next step is to have the entire plant structure cut clear down to the ground. Where- upon the stems, leaves and all are placed on a tray in an electric drying oven where they re- main for from 12 to 24 hours. Next the dried leaves and stems, along with a supply of stones, are placed in what is known as a ‘ball mill, and ground into a fine powder, which then is sepa- rated from the coarser stem material by a ‘screening machine.’ “Next comes the extraction process. The leaf powder is soaked in acetone and run through a large funnel where the four pigments are ex- tracted by the simple process of adding more acetone. The final stage is to run the liquid chlorophyll through a silver-plated separator of the centrifuge type, which removes all impuri- ties, and results in a solid mass of almost pure chlorophyll in the bowl of the centrifuge.” “ONLY ‘6975 Buys Newest Type Outboard Motor XTRAORDINARY value! New- powerful light motor has gearless Rotary Valve (never before offered on motors at near this price), Underwater Silencer, Carburetor Silencer, Flash-Start Primer, One Lever Control, Certified Horse- power and many other costly features. Drives family and fishing boats up to 9 miles per hour. Also a companion model that develops 5.1. N. O. A. certified horsepower at 3,750 R. P. M— only $99.75. COMPARE IT! Send Today for. Free Comparison Charts Write for free Evinrude and Elto catalogs and we'll include Comparison Charts that enable you to check the comparative values of all es. Get the most J for your boating dollars! Address, Outboard Mo- Corporation, , 5550_ 6th St., Milwaukee. tors No 2 EVINRUDE GET INTO THE TOY BUSINESS (jum AS OUR MANUFACTURER Earn Money casting our new holiow Toy Soldiers, Indians, 5 and 10c Automobiles, Ashtrays, ete. NO EXPERIENCE required as we furnish full instructions with moulds and cooperate In selling, also buy goods we need. A rare opportunity for these times for man with small capltal so if you mean strictly business write at once for full de- tails as 1933 Wholesale Season is Now Starting. METAL CAST PRODUCTS CO. 1696 Boston Road, New York CARVE, DISC, DRILL, GRIND, : POLISH A REAL TOOL— "WE ; Not a Toy MASTER BENCH HEAD °a'Uiretines” Each attachment is mounted on a mandrel and is in per- fect alignment. Tochange atachments, merely loosen handwheel and elip into draw-in collett. List price $4.00. H « Send $3.00f or Master Bench Head 4 Special Offer: sree CoD: Weel isend you FREE one 4''x 24'"all-purpose grinding wheeland 4'^ buff mounted on separate mandrels. Writefor booklet. WISCONSIN ABRASIVE COMPANY -Dept. 8503 Station A _ Milwaukee, Wis. Dept. 2 1 Ca A Thank You for Mentianing Modern Mechanix and Inventions for May When Writing to Advertisers 141

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Thousands of men past 40 havelosttheir health and strength—eand don't know the cause. They suffer frequent night rising, chronic constipation, backache, foot and leg pains, sciatica, nervous- ness, mental depression,etc. Many think itisapproaching oldage. Others wrong- ly attribute their trouble to bladder and kidney. This is sometimes a dangerous mistake. Science has discovered the real trouble is often prostate gland fail- ure—a grave affliction. But an amaz- ing new drugless home gland treat- ment has been perfected that thousands of users say has brought swift relief, and quickly restored normal activity. W. J. KIRK, President, The Electro Ther- mal Co., 3865 Morris Ave., Steubenville, 0. FOR YOU | ON NEW SELLS TO Retail Stores, Cafes, Drugstores, and Ad- vertising Departments of Big Companies No gadgets—no novelties, but a sound business necessity with a patented new improvement that makes asale every time. Green beginners have been making $10 a day and more, right now, in these times. All year long youcan sell repeats automatically hecause of nocompetition. Just three items in the line—all fast sellers at prices under $1, Easily demonstrat- ed—no “educational” or “get-rich-quick” sales talk needed. When you see our folder that explains all, you'll say, “IT'S A NATURAL.” This is a brand new deal—hot territories are open. Write or wire at once to Dept. 33 for our “SPOT CASH FOR YOU” plan and complete details. AD-HERE PAPER COMPANY 756 So. Spring Street - - - - - Los Angeles, Calif. FREE! So amazing in resultsthatthe inventor sends iton Free Trial.. Write today for facts and free book of star- tiing truths about men past DO You A le wins STOP TOBACCO? APO Banish the eraving for tobacco as thousandshave. Make yourself free and happy. with Tobacco Redeemer. Not asubstitute, not habit forming, Write for free booklet telling of in- jurious effect of tobacco and depend- able, easy way to relieve, the craving many men have, FREE Newell Pharmacal Co. BOOK Dept. 867, Clayton, Mo. This Money Making Business Is 3 Yourrs FREE: It Can Pay You ¥5 $4899 AWEEK No experience needed to act as \ our representative for Master Work Garments. Every business concern a prospect. Easy, pleasant work. You recelve pay daily inbig cash commissions. Advertising em- broldered on garments isa big sales feature, You can easily add up to $48.00 weekly to your regular in- tome. We supply everything need- ed to start Immediately. Write at once for FREE samples and full particulars, GEO. MASTER GARMENT CO., Dept. Vieonier, Tngiana, WEITE FOR FREE QUTF'IT, A Water Wheel for Farm Stream (Continued from page 108) The weight of water in the buckets keeps one side of the wheel constantly heavier and, of course, accounts for its turning power. The bucket placings are scientifically designed for quick loading and easy spilling, and please do not try to make them square “so they will hold more water" because they will not empty quickly, and so in carrying up on the other side the un- emptied water you will lose what you theoretical- ly gain by the opposite side's increased loading. This is simple language, and pertinent, for I have had this question brought up to me about another little water wheel which was run in this good sheet's brother mag, Mechanical Package Maga- zine, some time ago. If you have access to quite a head of water, part of which can be piped, I would suggest you write us concerning your needs. If half a dozen or so write in to Sam Wing, well run another little more complicated article on a vane type enclosed turbine that can be operated in a closed pipe line. Address me care Sam Wing, 529 So. 7th St., Minneapolis, Minn. "Vibrometer" Makes Music Visible (Continued from page.102) placed on the rubber diaphragm, it will be neces- sary to create just the slightest depression in the center. This is done by hanging a small weight from the center. The cabinet proper is made of plywood with a three-quarter inch soft pine base. The window in the front is cut out on a band or jig saw and provided with ground glass. The images of the sound waves are created by the light reflected by a series of mirrors, the mercury itself acting in the capacity of a mirror. These mirrors have tin backs of the size and shape illustrated and are attached to the posts with angles. The source of light may come from a small magic lantern or the experimenter may easily build himself a small light projector. The more powerful the source of light the better. It will be necessary to do a little adjusting to make this device perform perfectly. In arrang- ing the mirror at the correct angle, it should al- ways be borne in mind that the angle of incidence is always equal to the angle of reflection. In the use of this instrument, the builder will find that matters will be helped a bit if the inside of the cabinet is painted with dull, black paint. Midget Sweeper Cleans Dining Table (Continued from page 127) and drill a hole through the sides of the box and lengthwise through one of the cross pieces to which the motor board was screwed. This hole is of a size to receive a steel or brass rod which forms a locking device. i On the bottom of the box mount three or four furniture slides to raise the sweeper far enough from the table or floor to permit dirt to reach the slit. In operation, crumbs or other material enter the slit, travel to the center of the fan and are thrown out to the edges by the curved blades, landing eventually in the compartment at the rear, from which they are emptied at intervals. mo. Thank You for Mentioning Modern Mechaniz and Inventions for May When Writing to Advertisers

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Fighting Chinese Pirates (Continued from page 72) and then negotiate a still further distance up the Jatter river for ninety miles, which is within ninety miles of the capital city of the province of Szechwan, Chengtu. This province alone has a population estimated at three quarters of that of the United States. To better understand the reference to the Volga boatmen one has but to visualize the life of the “junkmen” in a round trip through the gorges and the part played by human labor. The voyage downstream from Chungking to Ichang, while extremely dangerous, is comparatively a time of rest for the crew. It is only a matter of skill to so handle the huge bow steering oar, assisted by the regulation rudder, as to keep the junk in the proper part of the channel. If all goes well the current does the rest. It was not until 1901 that steamer transporta- tion was. made possible through the treacherous gorges, thus infuriating the junkmen who saw their. sole means of livelihood diminishing. Up to this time the dangerous rapids, whirlpools and currents made navigation possible only by junks. When it is considered that three round trips between Chungking and Ichang was the entire life of the average junk, and the long time it took to make the upstream journey, it is 1e- alized why the pn rates were extremely high. The batred of the junkmen for the steamer companies thus engendered is mainly responsible for the reign of piracy in the Yangtze region, and no opportunity is lost by the junkmen to bedevil the companies, set fire to the steamers, intimidate the pilots, boycott the exporters, kid- nap the passengers and finally, for the renegade snipers stationed on the banks, to pick off the pilot, thereby wrecking the ship. JA Again and again the Yankee tars, comprising the crews of the seven gunboats which patrol the Yangtze for Uncle Sam, are called upon to engage in, hand-to-hand combat with the fero- cious river pirates. A striking instance of this sort took place some months ago when the gun- boat Palos, assisted by the British gunboat, Aphis and the Yankee gunboat, Guam, was re- sponsible for saving an entire town, with indus- tries and property valued at over $2,000,000, from what otherwise would have been certain destruction. ' " "The trouble started early one month when the Guam, cruising past Yochow, some 130 miles above Hankow, along the Yangtze at the junc- tion of the Yangtze and Siang Rivers, was sud- denly fired upon by bandits from tbe shore. Later that same month the bandits, thought to be communists, captured the city of Changsha. It so happened that the Palos was cruising near- by, besides the British gunboat, Aphis, and the Italian gunboat, Eermanno Carlotto. These vessels evacuated all the foreigners liv- ing in the town and then the Palos moved down the river just below the town to get out of firing range. A couple of days later, the Palos, on an inspection tour, cruised past the town. Then the fun began. An indeterminable number of pirates opened fire on them, finally being put to utter rout, fleeing, no doubt, deep into the hinterland. At any rate, the prompt action and vigilance of the Palos saved the city. och | Thank You for Mentioning Modern Mechanix and Inventions for May When Writing to Advertisers Just the LATHE for your HOME WORKSHOP! Here is just the thing you need to make that workshop of yours complete. An accurate 9” lathe with compound rest, automatic reversible feed, hollow head stock spindle, thread cutting gears, etc., complete as illustrated below for $79.00, less motor. Uses !4 H.P. motor, plugs | into light socket. Cuts standard threads from 4 to 72 per inch. 9” swing. 18’ between cen- ters. The greatest lathe bargain you have ever been offered. This price is possible only because of large production. 2 weeks trial. Satisfaction or money back guarantee. Manufactured by a company that has been making fine precision | machinery for 25 years. Easy terms. Write for free circular and full information. Atlas 9/4 Screw Cutting Bench Lathe g ? Complete j ; as shown, ATLAS PRESS COMPANY 1852 North Pitcher Street Kalamazoo, Mich. Jie V.S. AIR CORPS 4 Takes in 800 men this year for FREE FLYING TRAINING. Gives them 200 SOLO HOURS, Spe- celal Uniforms, BEANSPORTATION TO THE FIELD, Living Expenses, and pays each man $75 a month as salary for learning to. FLY. Course in MOTORS included. The Training costs absolutely ‘nothing. Let us Tel] You: How to Get In, Information about Uniforms, Rank, Leave, and Actual Life at the New $10,000,000 Field. Send your name. Hand postman $1 and postage when information arrives. It is Com- plete. Nothing else to buy. FLYING INTELLIGENCE BUREAU 401 Judson N. Rives Bidg. Los Angeles, Calif. ` GOVERNMENT ... JOBS FRANKLIN: INSTITUTE Dept. H310, Rochester, N. Y. Gentlemen: Rush to me FREE Men—Women—18to50 ,^ ^ Commen Education 4 usually sufüclent GU Mail Coupon e Today— 7 SURE list of U. S. Government. steady future positions, 32-page book de- scribing salaries, hours, work and how ^ to get a position. FI, Naüme......sseeoeee nasse tentent PIE 0 P"

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LEARN in CALIFORNIA TELEVISION: RÁDIO TALKING PICTURES EARN world’s leading industries, Talking pictares have brought new fire and opportunity to the Movies, Room and Board Now, Television is here with a promise of growth 75% of our students are and áctivity so great it cannot be estimated. Come earningtheirliving expenses to Los Angeles:and learn these fescinating Trades. While attending school now. help you get a job to pay BUT—YOU MUST BE TRAINED [hing expenses wile leatn: Times are getting better. The worst of the depres- f you are short ‘hougands of new jobs will call for juet a few years, Radi s money, Mire and captain TRAINED MEN. Will you be ready? Regardless Your proDiem e Also ai the times, the Tri ‘Trained man wins. Healway s has bw your Coach Rallroad and he always will. Take that fact as a guide and Los Angeles. your future is assur. k SPECIAL NEW COURSE—RADIO Send for Free Book BROADCAST TECHNICIAN here a positive revelation. Go at our new book, which Special course given to students who enrol] imme- ali the fac ntel We broadcast over our own station and hilzen- SEND COUPON diss by remote control. NATIONAL RADIO c ELECTRICAL | SCHOOL-/0s Angeles Dept. MMR 5, 4006 Figueroa St. Send Book and full details of Courses. b NAME COUPON Ee APR | pense send, me u. nrormation PATE EN 1234 BROADWAYE 1 | sna, terne REGISTER YOUR Protection with- TRADE: MARK BY 31sv. NEW YORK out obligation. REG. PATENT ATTORNEY PROE ENGWEER | Name WHAT IS YOUR INVENTION? Send me a simple sketch of a model for CONFIDENTIAL ADVICE—DO IT NOW! | HEAR GAS PENCIL GUN Now $1.50 A POWERFUL GUN and Automatic Pencil Combined, Improved to Pertection in Germany. Shoots Tear Gas in ¢) its most highly concentrated form. All metal cartridges. A Sure KNOCK OUT! Most daring assailants are in- stantly stupefled 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 paid with order. HAGEN IMPORT Co. 1019A Hagen Bldg. St. Paul, Minn. [^s TO BUILD THINGS? Send J st | ing Z Protection- = . Modern Mechanix and Inventions' FREE Blueprint Book. 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. Fortune Making Ideas for Inventors (Continued from page 120) A Device to Protect Plate Glass Windows During a recent visit to the city of Buffalo, N. Y., during a 70-mile-an-hour gale coming off the tip of old Lake Erie, I counted seven large plate glass windows on the main street that had been blown in. Here in one little spot on a single day—indeed in the space of one hour’s time— there was at least two thousand dollars damage. Why cannot some clever inventor think up a folding device of some kind that can be placed near a window and that can be used to press against its center during spells of high pressure from the outside? I cannot get over the notion that here would be an easy problem to solve and a real money-maker at the same time. Specifications: Should take the form of a fold- ing steel brace of some kind that could be pressed against the window at the point of greatest stress during high pressure winds. Should not cost over twenty-five dollars. Exploitation: An inventor of such a device would do well to first take the invention up with some large insurance company for its indorse-- ment which would be worth a great deal of money. If such a company would agree to lower its insurance rates where such things were used, the rest would be easy. This invention should be worth $25,000 on an outright sale. A Camera Plate Holder No matter how careful even a trained photog- rapher may be, he often makes the mistake of taking two pictures-on the same film or plate. What is needed is a plate holder that, once the slide has been removed and the picture recorded, will be impossible to use again until the plate has: been taken from it and developed. For instance, the photographer places his plate in the camera, removes the slide and takes his pieture. After that it should be possible to replace the slide in the plate holder ONLY in a certain way and after that it will be impossible to remove the plate holder slide by merely pulling on it. The photographer will know that the plate has been exposed before by the fact that it cannot be removed in the ordinary way. Specifications: Should not add a cent to the cost of making such articles. Should not be large or cumbersome. Exploitation: This idea is NOT worth a million dollars but it should be worth a nice little check for about $5,000.00. A New Mechanical Toy We all know how tremendously popular the idea of the meccano toy has been both in this country and in Europe. The toy could be many times more popular than it is, however, by ob- viating the necessity of using nuts and bolts to hold the various members together. Boys become impatient finally by the mere | boredom and monotony. What is needed is a meccano toy that will snap together so that a boy may make things faster. The pieces should be stamped in such a manner that they can be snapped together at any point without the use of any auxiliary equipment such as nuts, bolts or wire springs. Thank You for Mentioning Modern Mechanix and Inventions for May When Writing to Advertisers

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Fortune Making Ideas for Inventors Specifications: There is no need of saying that this method should produce a cheaper toy because if the problem is solved correctly, the snap feature being an inherent part of each member, the cheap- ness will solve itself. Exploitation: Should be patented in this coun- try and Europe and sold outright for $50,000. Paper Slippers for Shoe Shops It is an embarrassment of shoes-repaired while- you-wait-sbops that the person doing the waiting must sit barefooted while his or her shoes are being worked upon. Now where is the inventor of a simple paper or composition sanitary slipper that may be passed out to customers, that will be worn once and then discarded? Wearing such slippers, the customer would at least feel more comfortable and proper sitting with his feet encased even in such a makeshift. Specifications: The slippers should be made for two cents and they may even carry advertising on their toes. They should be wrapped in a smal] package and so fixed that they could not be used twice. Exploitation: Should be.sold on a strict royalty basis due to the fact that many millions of pairs would be used annually. The great volume spells royalty. Glue Balls, a New Idea It has been a long time since I have mentioned an idea that might be of some interest to my chemically inclined friends. A chemist recently told me of an idea that he had had in mind for many years but never got around to putting it in definite form. He wanted to put glue up in the. form of little balls or cakes that could be sold in the chain stores without bottle or con- tiner of any kind, which costs more than the glue. i Specifications: This glue, although it does not come in a container, must be protected in some way. so that it will not be affected by high humi- dity. When brought in actual contact with water, however, it should dissolve quickly. Exploitation: Should be sold outright for $50,000. It should be patented in the leading countries of^the world. Freaks and Dramas of Ocean Bottom (Continued from page 63) . The most notable of the group bears on its head a sucking disk which is a modified backfin, look- ing much like the corrugated rubber heels of shoes. This fish is frequently found clinging to sharks to which it affixes itself in order to ob- tain a free ride to the spot where a kill is made. Upon arriving it detaches itself from its host and feeds upon the fragments. The suctica of the disk is so powerful that the natives of Chinese waters use the fish for catch- ing turtles. They attach a thin line to its tail, and: cast it into the water near a turtle toward which it promptly darts and fastens itself quick- ly to the under surface. If the turtle is not too heavy: and powerful it can thereupon be drawn into the boat. : n eed Contractor ... Automobile Englneer -Civil Engineer -Structural Engineer -...Buslness Manager P. A. & Auditor High School Cou rse in This simplified, complete High School Course, specially prepared for home study byleading professors, meetsall requirementsfor en- trance to college, business,and leading professions. Over 200 noted Engineers,Business er Men, and Educators: helped pre- parethe specialinstruction which Courses you need for success. No matter what your inclinations may be, youcan’t hope to succeed with- out specialized training. Let us give you the practical training you need. American School Drexel Ave. and 58th St. Dept. H-533, Chicago Á Money Back When You Finish If Not Satisfied American School, Dept. H-533, Drexel Ave. and 58th St., Chicago Send me full information on the subject checked and how you will help me win success in that line. «..- Architect »... Electrical Engineer ..Bulldin .... General Educatlon 2... Lawyer Mach. Shop Practico ..-Moohanical Engineer ....Steam Engineer ».. Draftsman & Des!gner as High School Graduate T Bookkeeper eeessnssecseotesqosesoqobennoceecotoedoseceeceoosaeceva s.e State......, HANDY MAN’S HOME MANUAL On Sale at All Newsstands for 50 Cents INVE PP n3 YOUR IDEAS 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! Promptness Assured with Best Results MILLER & MILLER REGISTERED PATENT ATTORNEYS 1638 Woolworth Bidzg., 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. ipse Thank-You for Mentioning Modern Mechanix and Inventions jor May When W riting to Advertisers:

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Television and Talking Pletures comprise one of the world’s greatest industries and offer you an easy way to big pay and a brilliant fu- ture. Our Radio course opens the door of this world-wide fleld. COST NO LONGER AN OBSTACLE The cost of this ‘‘officlal’’ Training is so low, payments so easy that anybody, regardless of how small pay be gets, can take any one of these pay-raising courses. Write now...specifylng whether. your in- terest is in Avistlon, Electricity or Radio. Complete information Free. HOLY NAME TECHNICAL SCHOOL EXTENSION _ 29 Scuth Lasalle St., Dept. 19 CHICAGO, ILLINOIS Regardless of size or strength, defend yourself an: friends against any foul attack, from Batlies or pa gun, knife or club. Subdue with ease persona much stronger than yourself, even if violent & crazy. A complete course on approved American Police Jiu- Jitsu by internationally known police instructor, 155 illustrations mee letailed instructions, pocket size. 13 knockout blows without using fists. 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Write for catalogue. FINLAY ENGINEERING COLLEGE, 1001-8, Indiana Ave., Kansas City, Mo, No JOKE To BE DEAF EVERY DEAF PERSON KNOWS THAT George P. Way made himself hear, after being deaf for 25 years, With Artificial Ear Drums —his own invention. He wore them day and night. They stopped head noises and ringing ears. They are invisible and perfectly comfortable. Wo one sees them, Write for his true story, “How I Got Deaf and Made Myself Hear.” Also book- let on Deafness. Add Artificial ress Ear Drum George P, Way, Inc., 741 Hofmann Building, Detroit, Michigap d Thousand Ways to Make a Living (Continued from page 79) one cent each. Twigs of alder, bittersweet ber- ries, laurel and hemlock boughs tied in bunches also found a ready market. Sphagnum moss, the kind which is used in stuffing pillows and mak- ing wreaths, grows in swampy places around ponds. Raked out, dried and baled, or even thrown in the back of the car and sold damp, it finds a ready market with greenhouses be- cause of its ability to hold moisture for long periods, making it useful in shipping shrubs. A bale 24 by 30 inches brings from $2 to $3. Depression Magazine Subscriptions A Minnesota farmer suffering from the de- pression took the agency for a group of popular magazines. Approaching his neighbors and friends over a wide area, he offered subscriptions at the regular price of $1. They hooted at the idea till he showed them a chicken crate on the back of his car. "Pay me in chickens," he sug- gested. In the first sixteen calls, he made fifteen sales and cashed in his chickens at the nearby market well over the amount necessary to cover the subscriptions. Suit “Club” When his radio repair business turned dull, a Kentucky man secured the agency for a repu- table line of men’s suits selling for around $16. He then started a suit “club” among some thirty of his friends and acquaintances. Each member of the club pays him $2 a week for nine weeks. Each Saturday night one name is drawn from a box containing the names of all the members. This man gets a new suit for whatever sum he has invested up to that time—$2 the first week, $4 the second, and so on for the duration of nine weeks. At the end of this time everyone who has paid up his dues in full receives a suit. When a member wins a suit on a draw, he does not continue to pay and his name is eliminated from the remaining list of members. The or- ganizer of this scheme made well over $100 with a club of just thirty members in nine weeks' time. Mending “Club” One housewife whose husband’s salary had been cut till it covered only the bare necessities, discovered a way of making a few extra dollars each week by opening a mending shop in her own home. Young men who were boarding or living in hotels brought their socks to be mend- ed and their ties to be pressed. And several young married women who held office jobs sent not only their husband’s socks, but their own dresses to be repaired, and silk blouses and scarfs that were too fragile to be trusted to a laundry. Wood for Beach Parties Boys will like this one. A Wisconsin lad, need- ing spending money, looked around for ways of earning it. While swimming at a popular beach, he observed that many beach parties came pre- pared to toast marshmallows and roast wieners, only to have to scurry about for some time to find wood for their fires, since the immediate neighborhood was barren. He gathered up a few loads of wood, tied in bundles large enough for a campfire, which found ready sale among those who used the beach. iube. Thank You for Mentioning Modern Mechanix and Inventions for May When Writing to Advertisers

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Delays are Dangerous in Patent Matters HE FREE BOOK shown here was prepared for inven- tors, to show them exactly what steps they must take to secure a PATENT. 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. Remember, inventing an article is one thing— securing the exclusive 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. = P. p ? I Serve You Quickly TE and Secretly UA you write me or send me is strietly CODE confidential between us. All letters and draw ings are kept in strong, steel, fire-proof file which are open only myself or authorized members of my staff. Ihave secured patents for inventors located in eve: tate in the Union, My organization is a large and efficient one. y pri e is confined entirely to Patents, Trademarksand Copyrights. Ihave had years of experience in Patent Matters. When you place your idea in my hands, I am in position to proceed at once to secure protection for you, My fees are reasonable, and, if you desire, I can arrange convenient terms of payment. IMPORTANT Please understand that you are not under the slightest obligation in sending for this book. T wil mail it, together with the Record of Invention form, the same day I receive your request. Use the coupon on next page 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. e c? * c CLARENCE A. O'BRIEN Registered Patent Attorney 317-Z Adams Building, Washington, D. C. 6 SMALL IDEAS MAY'HAVE LARGE aes (Practice Confined Exclusively to Patents, Trademarks, COMMERCIAL POSSIBILITIES Copyrights) This Book Tells: neces ication filed; and ma t poin: gain and nothing to lose by sending or this book TODAY. My Location in Washington My offices in Washing- ton are convenient to the Patent Office, and J and my a tants can, therefore, appear promptly before the officials and Examiners. Reasonable Fees and Convenient Terms I have served thousands of inventors in all parts of the United States and I am able to serve you very reasonably and extend liberal terms of payment, So don't waste valuable time. How your Patent Appliea- tion is made; what kind of sketches or drawings are ‘yj whatother papers must be made out; how the Patent Laws protec you; why it is important to avoid Joss of time in getting your avery simple idea, i? new and. useful, may prove very valu- able. You may have much to E FREE ` Record of Inventi Blank Along with my book, I willsend Record of Invention form, ale ‘This blank will enable you to make sketch of your idea in proper form and have if witnessed in such manner that Te may be of value to you as ovi- lence shosld the accasioa for evidence arise, In my book, T tell you how to "uso this form to protect your interests. CLARENCE A. O'BRIEN Registered Patent Attorney LE WEGE ES C CLARENCE A. O'BRIEN, Registered Patent Attorney, 317-Z. Adams Bldg., Washington, D. C. Please send at once your FREE book. "How to Obtain a Patent” and your “Record of Invention” form. NAME. ADDRESS. (Re sure to write or print name elean! EE m oe UE m — 12 t iik Vou for Meniizning Modern Mechanic and Inventions for Moy When Writing to Advertisers — Thank You for Montioning Modern Mechanix and Inventions for May When Writing to, Advertisers 13

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THIS GREAT BIG STEAM ENGINE 230 POWERFUL | MEN MODE Add e be est: age and packing using oneal stor CAMERA AND COMPLETE OUTFIT dte ERIT bu 39 [Electric Telegraph Set 15c A PRIVATE TELEGRAPH SET ol YOUR OWN Become an expert Telegraph Operator ina very shor lime por BLANK CARTRIDGE PISTOL cu vm PRICES i 50c Bastonld: Car C3» THROW YOUR VOICE BOYS! BOYS! BOYS! Beg, Into a trunk, under the bed, Qu. 1298 under a tables back of the door, P intra denk av acho or apy? here, “You get ori of tan Fooling the teacher, policemen Peddlers, and surprise and fool Ri Sour friend besides, MADE EASY 250 "57065 10e m Fe REPEATING AND SINGLE SHOT| AIR PISTOLS trito, (Postage Siamas accented) Yor el artietas listed abeve [piso n aur ctor od on previous pane JOHNSON SMITH & CO. Fa Wonder Crystal Radio Receiver $1 dot yos e aoi aed Bat E oa re Ho hur $2.83 pesto “bg LID Wis. Mechanis and I 919 27 ntions for May When Writing

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SPOT NEWS of In the World of Non-binding garters built right into the sock are the latest boon to men bothered with complaint of slipping-sockitis. Special camera keeps 3-dimen- sional portrait records, 5c coins stamped out of wood now circulate in Blaine, Wash. the MONTH Science and Invention Special catapult for launching seaplanes i is built lengthwise of the floating airport. Map showing where the floating ship island will be anchored on lane of south Atlantic air travel where regular passenger line A is being established. Last word in streamlined cars ous 5, is this German Maybach, built by the famous manufacturer of airship engines. Its a 12-cyl- inder. Inside room is great = X because of utilization of run- ning-board space for seats. 36 Modern Mechanix and German liner Westfalen which has just. passed tests to prove her efficiency as a mid-ocean base for seaplanes crossing the southern Atlantic. Note derrick at stern and the catapult rail. | | Seaplanes are pulled aboard ship by derrick after they have taxied up on a canvas drag whose lower edge floats just un- der the surface of the water and is supported by pontgons. Inventions for May

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ap ‘Pilots Ride to^DEATH on Ylying ‘BOMBS ^ The current conflict between Japan and China has brought out an amazing tevelation of the methods by which Japanese pilots assure air bombs reaching their target by putting a man inside to steer them. Why? Read the reasons in this article, and you'll have a better understanding of Japanese psychology toward the machines of war. MAGINE yourself strapped within a hoi- - low chamber inside a huge air bomb, surrounded on all sides by high explosives. In front of you is an airplane type rudder which steers the tail unit of the bomb. Win- dows in the nose enable you to see ahead. You're loaded into the bomb, which is placed in its nest under the fuselage of a bombing. plane. The bomber takes off, soars above a target—-say, an ammunition dump of the enemy. Up above you, the pilot of the plane pulls a lever. Down you go, plunging toward the ground with terrific speed. You see that you aren’t going to strike the ammunition dump, but will land many yards to one side of it. So you twist the control rudder, swerving the bomb’s course. Success! The dump looms up directly below the windows TA ps @ c à 4 3 1 of your bomb. And that is practically the end of things for you. i Sounds like the superheated. imagining of a Jules Verne, doesn’t it—the sort of absurdity that a sensible man would laugh off as being unheard of, an astounding, amusing impossibility? I Its nothing of the sort. It's an actual fact of warfare, a method used by Japanese pilots who deem it an honor transcending all others to ride to glory for the mother country. They know that their memory and their families will be forever honored in their homeland. d Rumors of the flying bomb death ride have filtered out of the conflict now being waged by the Japanese and Chinese. Neces- sarily this information has been of a confi- dential, undercover nature, but not long ago it was given nation-wide publicity by a radio commentator on international affairs. Japanese and Machines To make the man-steered bomb a credi- ble actuality, an understanding of the pecu- liarities of the Japanese character is neces- sary. And some such understanding may sooner or later be forced upon the great powers of the world who are all too likely to become involved in the aggression of Japanese militarists in China, where the United States, Great Britain, France, Italy and Germany do much business. In the field of machinery the Japanese mind is at a peculiar disadvantage. They Where the U. S. government expedition is now conducting a survey of the Aleutian islands, looking toward the possibility of establishing weather station, air base, naval base and possible fortifications. Note the proximity of the islands to Japan and the great circle course of steamers. Planes are being taken. with which to make an aerial survey of the islands. 88 Modern.Mechanix and by RAY HOLT are able to turn out an exact copy of any mechanism that comes into their hands, but the type of mechanical imagination which went into its original creation—which, for want of a better term, is sometimes known as Yankee ingenuity—they are at a loss to duplicate. The simple truth of the matter is that a man is practically required to steer Japanese bombs to their mark because they haven’t been able to develop the bomb- sighting machinery which makes Uncle Sam’s flyers, for instance, so deadly in their accuracy. Peculiar Oriental Psychology As to why Japanese soldiers fight among themselves for the honor of being the bomb pilot who can look forward to being blown to certain oblivion, that’s a matter of psy- chology not so easy to understand. Patriot- ism rules the Japanese to an almost fanatical degree, and love of country is so bound up with religion—the emperor being regarded as an incarnate god—that to be blown up in a bomb to further the successes of Nip- pon becomes something to be desired above all things. When one understands the popularity that hara-kiri, a form of suicide by self- disembowelment, has had among the Jap- anese for centuries, the national willing- ness to dive to death in a bomb, or in any other way, becomes credible. Hara-kiri, as formerly practiced, was Riding to glory for the mother land, a Japanese pilot inside a bomb dropped from an airplane steers it to destruction because Japanese mechanics are unable to design: elaborate sighting devices which would assure reasonable accuracy. ‘Inventions for May 39

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NOVEL NEW MACHINES for “PULLING “POWER from the SKIES Sm E THE endless quest for cheap sources of = energy, two proposals have recently been advanced which demand serious consider- ation, both for appeal to the imagination and the possibilities of practical operation. The high speed windmill shown on this page is the latest development of Volf’s labor- atories in New York. The first of these power producing units will be in operation by May first. Three fans are provided so that one is always facing a wind current. The fans are geared to a gyro stabilizer which runs on inertia so that the fans will not run down in calm intervals between gusts of wind. A generator is driven by the geared shaft, producing current for storage batteries. In i actual practice three or four small generators ee will probably be used, one or more of them à E being automatically cut out when wind velo- 3 city falls below a certain point. | Another idea, less close to realization than i Volf’s windmill but involving natural phe- nomena just as dependable, partially owes its inception to the stratosphere balloon as- cents of Prof. Auguste Piccard. The extremes of temperature encountered by Piccard, in which the outside air was around 75 degrees below zero while interior temperatures of the gondola were around 100 degrees, makes possible the operation of a thermal engine as described in detail on opposite page. Principle of operation of a thermal engine is simple. In this instance, alcohol or similar liquid with low freezing, high boiling point, is imprisoned in piping. Top chamber of gondola is painted black, to absorb sun’s rays proved successful in Piccard gondola, shown in photograph). Lower chamber is aluminum finish, reflect- ing sunlight, consequently remaining at temperature of outside air, around 80 below zero at these heights. Liquid turns to steam in top chamber, passes through pipe which drives turbine generator, is condensed in cold chamber, and returned by pump driven by portion of electricity generated. Prof. Piccard himself expects that mysterious cosmic rays will some day be harnessed for power. In circle, how three fans are geared to driveshaft in Volf windmill. At right, working model of the design. _ Cylindrical unit behind fans is a gyto stabilizer which assures smooth run- ning in gusty winds. This thermal power plant, anchored by captive balloon high above the clouds to operate through heat of sun and cold of atmosphere, is an idea based on sound physical laws, demonstrated in Piccard balloon ascent a year ago. 42 Modern Mechanix and Inventions for May 43

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‘When “You've Found Gold— Eprrog's NOTE: This is the second of a series of articles on prospecting and recovery methods used in the new gold tush. The first article, which appeared in the April issue of Modern Mechanix and Inven- à tions, described methods of pr : locating paying gold deposits. Y?" have found gold! But the ground is not rich enough to make wages by hand panning. Still, if you could handle two yards in- stead of a half yard, you would make good wages. You keep on testing with the pan to see how much placer ground you have found and how rich it may be. As you do this you keep your pan clean, especially free from, grease, and you have picked out a number of par- ticles of placer gold large enough to be handled with a fine pair of tweezers. The finer concenirates you keep separately to be refined or you have amalgamated them with “quick” (mercury) and will send them to some metallur- gist. You cannot risk the poi- son fumes of the mercury or you might do the refining of the amalgam yourself. There is one way you can : do this without much danger I z a x and with small quantities of Sluicing methods have not changed radically from early days. This photo, taken in the sixties near Central City, Colorado, shows a group of miners shoveling pay dirt into a sluice fundamentally identical to those in use today for hand operations. Dredges enable gold to be recovered at a profit from placers too poor to be worked by hand. Dirt as poor as 15 cents to the ton returns a handsome profit through use of dredges like this. Of course, deposit has to be of considerable extent. Capital can be interested to the extent of supplying dredges if the prospector can prove the productivity of his placer field on the basis of test borings extending clear down to bedrock, Thousands of tons are handled per day in this manner. 48 Modern Mechanix and by Arthur Hawthorne Carhart SLUICE ’er OUT! Me amalgam. By putting the amalgam GRAVEL IN inside a big raw potato, then bak- x HOPPER ing it in a fire outdoors, until well done, the mercury will be driven out into the potato pulp, leaving a button of gold. Unwire the potato, put away the gold, squeeze the mer- - cury out of the cooked potato by ? ES hand, using a. basin of water to ZB elp the separation. But all your panning has shown you must increase your efficiency, handle four to six times as much J earth per man per day, if you are Ma ce going to make wages. How to do it! LAYOUT FOR SLUIGE The actual business of rking wz ind pane | ees | SS HOLES TO FACILITATE CLEANUP, CORKED WHILE SLUICING IS IN PROG placers ranges from the hand pan- ning of very rich, limited pockets to expensive dredges that cost sev- eral hundred thousand dollars, but operate profitably in low grade dirt. More recently there are *placer ma- chines” costing from $200 to $30,- 000 that handle low grade dirt to advan- tage. Right off yousay you are not interested in any such bulk - handling machinery. But if you have lo- cated a big SMALL ROCKER OR CRADLE Construction of a sluice and details of a rocker or cradle are given in the drawing. Gold amalgamated with mercury is recovered by put- ting inside a potato; heat will drive mercury into pulp, leav- ing gold for recovery. mE Compare the gold rush of 1932, pictured in the photo above, with the photograph of the fifty-niners at work on the oppo- site page. Man power plus pay dirt plus a knowledge of the tricks of the trade, wins a living wage for hundreds of present-day prospectors who are combing gold-bearing territories. And there’s always possibility of scoring a ten-strike. ‘When intending to try their luck in the field they should knowhow to identify gold when they have found it, and how to .recover it profitably when found—information which is all contained in this interesting series of articles. Inventions for May 49

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cA Complete COAL eMINE HEN the Rosénwald Museum of Science and Industry opens in Chicago May 1, visitors will be treated to a trip through a real, working coal mine, despite the fact that the nearest coal deposits are 200 miles away. They will descend in a real mine cage to a depth of 500 feet and take a trip of more than a mile on a real mine train through the workings. Or at least, such will be their impression. Actually the de- scent will be but 50 feet, to the museum's sub-basement, and the entire mine is packed into a space of less than 100 by 200 feet on two floors. B Visitors will descend in a real mine car capable of holding 30 passengers. The car starts, stopping without the passengers re- alizing it while 450 feet of shaft wall, on an endless belt, flashes before their eyes to give the illusion of continuous descent. At the same time they feel the rush of cool mine air, chemically charged with the de- cayed vegetation odor of a mine, forced from a blower at the bottom of the shaft. Emerging, they watch an endless string of coal cars being unloaded. Ilusion again! The “coal” is a cork imitation, wired to a screen on top of the cars which folds up and disappears at the touch of a button. Simultaneously a can of gravel, attached to a microphone and radio am- plifiers, is tipped into a metal hopper to produce the din of coal sliding down a chute. The visitors get into two mine cars, ap- parently pulled by an electric locomotive. They round a corner, pass through a fire door, and roar down a stretch of track. Actually, the train stops while an endless belt, car- rying papier-mache reproduc- s The Rosenwald Museum, of Chicago, in which the model coal mine shown above is constructed, is shown in the upper photograph. The mine occu- pies a space 100 by 200 feet in the museum building. 54 Modern Mechanix and tions of actual coal seams in 1 an Illinois mine flashes past them. Fan blowers, radio amplified sounds, and a sparking trolley wire over- head complete the illusion of motion. The mine train is one of three, each mounted on the same cable which circles around the mine. The locomotive does no hauling. While one train is being loaded, the other has stopped opposite the moving walls, while the third pauses alongside a low-vein cutting machine in action. In traveling alongside the moving walls, long, dimly-lighted galleries are seen leading off into the distance, where trains of loaded cars can be seen and heard rumbling over crossings. The trains, toy size, are less Inventions for May Cans for passengers xedto' endless belt. ei H i coal that folds upat touch. of button. Ta Ingenious methods by which the illusion of a 500-foot descent into a coal mine and a mile ride within its tunnels is created, are shown in the above drawing. Actually the model mine is compressed into a space 100x200 feet, and is two floors in depth. The use of radio with sound movie film for creating appropriate sounds, and of fan blowers to circulate through the tunnels air which is chemically treated to simulate the typical mine odor, are outstanding features of this most ingenious exhibit. The mine trains, actual size, are not pulled by the electric locomotives, but are drawn around on an endless cable. than 15 feet away, and the sounds are radio amplified. A real battery of mine pumps will be seen in operation, pumping real water trickling down the gulters. The operators of the machines are also genuine, being union miners from southern Illinois. From the operating mine, visitors will pass through another type of mine, where the vein ascends on a slant, instead of be- ing laid flat. That is all that will be in operation this summer, but later the journey will con- tinue through lead, zinc, silver, gold, and diamond mines, finally ending up with a 1,200-foot ascent in another mine car (again compressed into 50 feet). 55

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Ginger ale Dispenser Mere twist of the jar unscrews cap when it is wedged into jaws of this new opener. Fastens onto wall with two screws and is ad- justable to take any size lid. Device is also convenient to put lids on tightly. Handy dispenser Shuttered sides and bottom of new lampshade | Punches hole in bottle permit adjustment for any degree of light. cap, utilizing gas pres- sure to deliver ginger ale. Turning bottle to left starts flow of liquid, turning to right closes the valve tightly again. Secured to door or wall, new type cabinet swings around completely out of the way to solve problem of limited storage space. Breakfasts, lunches are prepared quickly by placing this electric cooker over dish in which edibles are contained, as demonstrated. Conserve coal by burning old magazines, which last for 25 minutes when suspend- ed from wires on grate rack as shown. New electric iron has button switch in forward part of handle, within easy reach. Dish washing brush has a soap receptacle in handle through which water is forced. Rich suds are sprayed out of bristles to cut grease. Unbreakable rubber dishes and utensils are l being made from "'Plioform," a rubber base product. Resists hot water, will not scratch. 56 Modern Mechanix and Inventions for May 57

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This skin is from a grizzly which weighed 1500 Ibs.—some 500 Ibs. less than the brown bear attains. Size can be judged by the seven-column newspaper on which the skull rests. 58 A most remarkable surprise picture of an Alaskan brown bear, snapped at imminent risk to the photographer. No other living animal is a match for the brown bear in quickness and strength. Photo reproduced through courtesy of Nature magazine. In circle, at left, is shown measurement of bear tracks—seven inches across! by James Nevin Miller Have you always believed that the grizzly is the biggest and most dangerous of all bears? If so, it will surprise you to learn that the grizzly averages about half the size of the great Alaskan Brown Bear. This article will upset a lot of your pre- vious notions about bears in general. HILE official Washington is all agog about whether the famous brown bear of Alaska, whose tremendous skin ranks among the most prized trophies in the world, is being exterminated by over- zealous hunters, almost countless stories are being told by bear experts concerning thrilling and almost unbelievable experi- ences of hunters, prospectors, guides, nat- uralists and government investigators who were unfortunate enough to meet some of these jungle monarchs unexpectedly. Modern Mechanix and Action! One of the rarest of all brown bear photos, showing ‘a ton of muscle and bone making a bee line toward a hunter who has aroused his anger. A tiger ora lion would be helpléss in combat with this powerful. beast. The map at right shows habi- tat'of the Alaskan brown bear. Shaded sections indi- cate areas proposed as game reserve where hunting of such bears shall be restricted. Kodiak and Afog- nak are the famous islands of the Aleutian group that attract hunters of the brown ear. s . ie The Alaskan brown bears form a group of gigantic animals peculiar to North America and limited to the coast and is- lands of Alaska from the head of Norton Sound to the Sitka Islands. ‘On Kodiak Is- land they attain weights sometimes ex- ceeding 2,000 pounds, and their, skins have been mounted measuring 13% feet from tip of nose to tip of tail. They can be likened only to the great cave bears which were the haunting terror of primitive man- kind during the old stone age in Europe. In eolor the animals vary considerably —from a dull golden-yellowish shade to a dusky brown, becoming almost black in some species. Some of the darker types are indistinguishable from the great grizz- lies with which in places they share the range, but the relatively shorter, thicker and more strongly-curved claws on the front feet are distinctive; moreover, the grizzlies average about half the size of the *brownies." Certain species occupy open, rolling or hilly: tundras and others live'on the steep- est. and most rugged mountain slopes and Inventions for May KENAI PENIN. AFOGNAK |. ge GB xooian 1 ge eich EBr x ISLAND Moss Bears are good fishermen. This Alaskan Brownie is spearing salmon from a stream. Brown bears, incidentally, aren’t always brown—some of them are almost black in color. His temper is uncertain, no one being able to predict whether he'll charge a human being or turn tail and run. 59

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Here Dr. Longley, head of the Tortugas biological station, prepares for a 55-ft. descent to sea bottom in 85-Ib. diver's helmet. Undersea photos are taken with waterproof camera. TEE tentacles of an octopus crept stealth- ily out from an overhanging ledge and seized its unwary prey. A four-foot barracuda—“tiger of the sea”—-with one lightning dart and a single quick snap of its powerful jaws cut a sil- „ver snapper in two. The stalks, branches and blossoms of plant-like structures that swayed every- where in profusion were in reality clever devices for catching, devouring, and as- similating living organisms. We watched this drama from a passage- way on the bottom of the sea off Dry Tor- tugas Islands that mark the extreme west- ern limit of the Florida Keys. The octopus paid no attention to us, if indeed he saw us at all, or possibly was repelled by our grotesque under-sea helmets and the tenu- ous air lines rising to the Anton Dohrn resting gently on the surface of the sea fifty feet overhead. The barracuda came near, nosed our garments, and slid away through the opalescent water. We walked among the coral polyps and their cousins the anemones of every con- ceivable color—brown, violet, pink, white, yellow, purple, bright blue, vivid scarlet. Then my breath caught. All about us lay what appeared to be petrified human brains. I learned later that they were only “brain coral,” whose skeletal support re- 62 GREAKISH DRAMAS of. the OCEA Here's a flashlight picture of a schoot of yellow goatfish and yellow grunts taken on sea bottom of Florida Keys. N 6 Bottom C. "m ee oe ee TEE Remarkable undersea photo taken with flashlight bulb shows a school of gray snappers foraging for food. A group of living coral polyps with fringe of ten- tacles on top for gathering food from the seawater. FEW THOUSAND t ISLANDS ORY, TORTUGAS. 28 aes, ES Map of Florida Keys shows Dry Tortugas (extreme left), locale of extensive undersea exploration being conducted by Carnegie Institute Biological station under Dr. Longley. sembles the convolutions of the human brain. Troops of fishes that have changeable color patterns darted about among the coral formations. My companion unslung his water-proof camera, and with the aid of an electric flashlight took a few photo- graphs of schools of gray snappers, yellow goatfish, and yellow grunts. Dr. Longley, the scientist in charge of the marine biological station at Tortugas, has spent more than 3,000 hours in all on ihe bottom, watching and recording the ceaseless under-sea drama where the rule of the jungle, *kill or be killed," predomi- nates, but where some extraordinary part- Modern Mechanix and Dr. Pearse, Duke University biolo- gist, shown above as he sets out for day's exploration on bottom of sea. root and begin to grow. Thereby the crabs secure effective. protection from their enemies, for the Freak of the deep is Tortugas crab which conceals itself beneath a bit of sponge, which in short while takes root and grows on crab’s shell. Offensive taste of the sponge protects crab against enemies. Photos show crab with and without sponge. nerships among widely different types of organisms have also been formed. One of these partnerships is between a coral reef crab and certain anemones. The crab removes anemones from the rocks to which the latter adhere and carries them fully expanded in its first or clawed pair of legs. When the crab is attacked it de- fends itself by pushing-the anemones to- ward the assailant; as the anemones, in turn, capture food, the crab transfers part of it to its own mouth. There are crabs that tear bits of living sponge off the rocks and hold them on their own shells until the sponges take Inventions for May species of sponge which they thus utilize is dis- tasteful to many creatures as it is packed with flinty, needle-like bodies and gives off a disa- greeable odor. There is a vividly colored fish, about an inch and a half long, that is always hover- ing about the giant sea-anemone. Upon the slightest alarm it darts for the anemone “blossom” and disappears among its feath- ery tentacles. When danger passes the finny occupant emerges from. its protec- tive cover. It is said that this fish is so dependent upon the anemone that it dies if the two are permanently separated. Sucker fishes which attach themselves to larger fishes are common al Tortugas. (Continued on page 145) 63

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cAT LAST—a (Convertible ZAUTO- PLANE. A.sebeboN. STARTLING new vehicle which may be used in the air as a fast, sturdy airplane, and on the ground as a speedy, comfortable two-passenger coupe car, will shortly be available to aviation enthusiasts. The craft is really a streamlined mid-wing monoplane of 30-foot wing span, propelled by a 125- horsepower air cooled motor of regulation aircraft type. For ground use the ship may be quickly converted into a stream- line car, simply by removing the wings and the rear end of the fuselage, leaving the closed cabin body resting on its three wheels, ready to drive through the streets. This transformation occupies about 20 minutes, by means of quickly detachable joints. The development of the “Ascender,” as the new ship is called, has taken many months of painstaking work in the selfsame Engineering Department which produced the fastest airplane in the world, Doolittle's “Flying Silo” which set a new world's rec- ord of 296 m.p.h. at the Cleveland air races last fall. The first Ascender has already been built and flown enough to prove itself a most unusual craft both in the air and on the ground. Control of this craft, in the, air and on The convertible airplane-auto has been designed by the makers of this famous Gee-Bee type sport- plane which won the Cleveland ait taces last summer at 296 mph. Brakes on all wheels— : individually The airplane is made ready for street use in 20 minutes by removing the wings and tail unit, easily detachable. the ground, is by an automobile type steer- ing wheel, a foot accelerator, and hand and foot operated brakes which act on all three wheels. While on the ground the ship rests on a three wheel landing gear, each wheel of which is equipped with internal brake and hydraulic shock absorber, as well as a large airwheel tire. The front wheel is steerable with the rudder of the ship, so that when the pilot moves the steering wheel to right or left, either on the ground or in the air, he guides the direction of his craft as he would a motor car. On the takeoff there is no necessity of getting the tail up and balancing on two wheels while steering the ship down the runway by means of a rudder bar, as one is obliged to do in piloting the ordinary airplane. In this new craft, one merely sits behind the wheel, opens the throttle, and drives the ship down the field or runway as.one would a car, with no possibility of “nosing over” even if brakes are applied suddenly, or from obstructions such as bumps, ditches, or soft spots. When sufi- cient speed has been attained the driver has merely to pull the wheel slightly toward him, whereupon the front whecl leaves the ground. and the ship *takes the air." Landing the Ascender is a simpler task than in the ordinary airplane. It is no longer necessary for the pilot to judge his speed: and distance so that the ship will stop flying directly over the spol in the field where he wishes to land. With this craft, he need merely throttle the engine, point the nose down until the ship assumes a normal glide toward the field and set the ship onto the ground at a speed much greater than is safely possible in the ordi- nary airplane. As soon as the two rear wheels touch the ground, the front one is forced down, and brakes may be immedi- ately applied to bring the ship to a smooth stop. Note the location of motor where it serves equally well for ground or air use. Angle of visibility is exceptionally broad. 66 Modern Mechanix and Rudder and front wheel synchronized Two views of the “Ascender,” showing appear- ance in flight, and method of converting into an automobile. On the ground, a wire screen is usually employed around the propeller as a safeguard, though the arc of the blade is well within the confines of the car. Inventions for May 61

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Looking down on the mighty Yanztze, 1500 miles up- stream from Nanking. The prow of a British gunboat is seen in the foreground. The patrol is carried into the rich province of Szechwan, which has three-fourths the popu- lation of the United States. The beginning of the tremendous gorges of the Yangtze— noted for their dangers because of the swift rise and fall of the waters. A French gunboat was once left stranded 24-ft. above the river when waters fell that distance in a day. HILE riding through an almost endless succession of dangerous rapids, whirl- pools and currents in the Yangtze River, about 160 miles above Hankow, a mer- chant vessel operated by an American, named Captain Baker, suddenly went aground. It was night-time and a stone's throw away could be dimly seen the craggy outlines of the shore. Nine times out of ten such an accident results in a bandit attack in this remote section of China. But hardly had the American given the order to his Chinese crew to arm themselves when things be- gan to happen. Not a single warning sound was heard and yet, within five minutes’ Modern Mechanix and with U. S. e9YCarines by JOHN CLOVELLY Seven Yankee gunboats, patrolling the Yangtze river in conjunction with those of other nations, wage constant war against the bandits who infest this dis- trict which boasts one-third of the world's population. Little known activi ties of this romantic branch of the for- eign service are described in this article. lime, every coolie had been disarmed and : bound by as villainous a gang of cut- throats as Baker had ever seen. Armed with sawed-off shotguns and wearing filthy rags, they looked as if they would commit murder for a dollar. However, their leader calmly announced that he would release the American upon receipt of two million dollars! Of course he did not make good on this fantastic de- mand, but his thugs seized Baker's boat containing perhaps $10,000 worth of car- go, and kept him prisoner for three months. At which time, thanks to friends, Baker raised a couple of thousand dol- lars and was freed. Such instances happen again and again in the region of China's mightiest river, which rises in the snow-capped mountains of Tibet and winds its way irregularly in a generally seaward direction for nearly three thousands miles to the ocean, empty- ing into the Yellow Sea a few miles from Shanghai. Small wonder, what with trade trans- actions such a tremendous gamble and human life a thing to be sneered at, that ihe gunboats of our Navy, Great Britain, France, Italy and Japan, regularly patrol the length of the Yangtze for nearly 1,700 miles, a distance as great as that from the Inventions for May U. S. tar watching a junk suspected of being one of a pirate group. Construction of the junk is typical; sails are of bamboo matting. Note the control ropes of the sail. mouth of the Mississippi to Hudson Bay. Canada. The American patrol force consists of seven regular gunboats and, according to the seriousness of the emergency, any one of four “spare” gunboats. Each vessel carries three to four ship’s officers, one doctor, and a crew of about 50 enlisted men. The boats are distributed through- out the Yangtze region as follows: At Hankow, 600 miles up the river, is the regular operations base for the Luzon, Graphic presentation of the perils which beset transportation of the Yangtze is given in the drawing herewith. Piracy became widespread -fol- lowing the opening of the upper river to steam- boats. n

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New ‘©HRILLS from Greak. SPILLS of AUTO BALL PILLS! Thrills! Smashups! Constant danger. Daredevil drivers strapped in odd looking, speeding cars, bouncing a huge ball about the race track. _ Spills? Sure there's one! Dust clouds rise as a little car does a crashing “barrel- roll" Then another, farther up the track, fairly leaps into space as it turns over. The air about the grandstand has the tainted odor of burning rubber from spin- ning wheels—wheels spinning first back and then forward. Cars skid, slide about, swap ends like a wild bucking broncho. " Spectators at auto ball gatnes are treated to all manner of freak accidents. Here a machine is seen climbing an opponent in furious clash. Spills like this are common. Note how car rolls over on the sturdy hoop built onto stern and bow of the machine, In the heat of the battle. Two machines pursuing the ball have just clashed, resulting in a spi Ball games, which are staged by intrepid drivers at country 74 by ED HARLAN GIBSON Another crash. A breath-taking spill. Wheels smash to splinters. For an instant the driver is hidden from the spectators’ view. The driver! He's killed? Smashed? No! There he is under the car, hanging in his safety belt with 1,600 pounds of iron and steel above him. Those who are near can smell spilled gasoline. An oil spattered face smiles out at the spectators. Maybe he is bruised and injured, but still the driver smiles. It's. a game he is playing and he loves the dan- gers it involves. Game of Hairbreadth Escapes The roaring motor now above him is barking out a sharp, angry exhaust. The smell of gasoline becomes stronger. From his upside-down position the driver can watch the gasoline drip uncomfortably close to the red-hot manifold. Just a few drops landing directly upon it and instant- ly flames will be lapping at his feet, scorching his hands and face. ‘In the nick of time attendants tip the car back upon its_wheels. f The game goes on. More spills and hair- breadth escapes. Contenders fighting with cars for scores and, above all, aiming to give their spectators a thrill. A startling novelty; better than auto racing. It is the Gibson troupe in action. The game is auto ball. The place? Any county or state fair that has contracted with the players to give their public a really thrill- ing attraction—a novelty that is different. There are six specially built cars in the outfit. Four are used in each game, leav- ing two in reserve to use when wheels or other parts are broken. The object of the game is similar to that of football. One team endeavors to push the large ball through the opposite goal and, above all, to give the spectators unusual entertain- ment while doing so. ; , The ball used is also * especially made. It is four feet high when in- Y? fairs, ment, take part, two machines being beld on sidelines for emergency use. fot both. In the Auto four vars specially built to withstand heavy punish- Object of the game is similar to football. Modern Mechanix and flated. Six plys of rubber and fabric are used in its construction which resembles that of an automobile tire. It weighs ap- proximately seventy -five pounds. Many times these cars, weighing close to sixteen hundred pounds, are driven completely over the top of the ball without puncturing it. Again it is bounced ten to twenty feet into the air and well over the opponent’s car. This is called a kickoff. In the course of a game accidents are constantly expected and taken merely as a matter of course. The large ball, sailing through the air, has often caught a driver unawares, knocking him completely un- conscious. Again, striking the steering wheel, the ball has smashed it between the hands of the driver. Fire Most Deadly Menace Fire is another hazard to contend with. Running wide open, the motors soon be- come red-hot. Then just a few drops of gasoline falling from the carburetor onto the red-hot manifold, while the car is up- side down, will instantly ignite it. Breath- less moments follow. The attendant’s first thought is of the driver. With flames already spreading about the oil-covered machine, they un- strap him. This he cannot do un- assisted because of his weight hanging in the belt. Airplane safety belts have been tried. The quick way of hooking them was handy; too handy, for the jarring and jolt- ing of the body unhooked them during the game. Fire in a night game is a spectacular sight and women in the grandstand have even fainted watching the flames enveloping the car. Thus far the driver has been removed invariably unharmed in all cases. Typical action shot here shows one contestant doing a “barrel roll,” while opponent maneuvers into position to give the ball a sock towards his goal. When in upside down position, driver's life is greatly endangered : by gas dripping on overheated manifold. The motor is kept running always. Inventions for May Experience has taught the drivers the knack of keeping their motors running in all positions, be it upside down or how. These drivers in auto ball claim a record of their own for spills, which in sport par- lance means the complete overturning of the cars. In a short game of five minutes of play as many as fifteen spills have been made. This is action in the raw. The grand- stand reaction is deafening applause as only a thrill loving satisfied crowd can give. Driver is held in seat by heavy leather belt. An auto ball car stripped for action. Speedster body has reinforced frames, with steel hoops on front and rear. Made of six plys of rubber and fabric, the ball is four feet in diameter, weighing 75 pounds inflated. 75

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1000 WAYS to ceMAKE a LIVING ^ Silverware Rebuffing Regardless of how careful the housewife is, her silverware will gradually become scratched. The fellow in the neighborhood with a small buffing outfit and a stick of plater’s rouge can be of great help and earn himself a dollar or two at the same time. Such ware does not neéd to be re-plated. As a matter of fact, re-plating will not remove the scratches—only buffing will do that. One man who makes upwards of $5 a day in this way, solicits business on a piecework basis, charging three cents each for knives and forks, more for pitchers and plates. He finds that much of his business comes from word of mouth advertising of those pleased with his work. The only way to restore scratched silverware to new condition is to re-buff it with the equipment shown above. Empty Store Windows A young Canadian is making a nice living out of empty stores! He lives 1n a suburban district of some 100 stores, a dozen or more of which are vacant. He acts as agent for the rental of those vacant store windows, finding that the landlords are invariably glad to accept any small sum in the way of revenue. Users of billboard space are good prospects for the rental of windows for displays; public utility companies, tobacco manufacturers, and owners of adjacent stores who wish to extend their display space, are also good customers. The young man keeps the windows clean, charging a monthly rental, and picks up additional income from setting up displays and doing the window trimming. Conducting a Doll “Hospital” For more than seven years an elderly woman has kept young and made a living as a specialist in repairing worn or broken dolls. Such handicraft as might be used in mending pottery, painting china, arranging hair and sewing dresses makes up the unique qualification of the doll doctor. Charges are based on the time and material required on each *case." The testimony of a customer that “our doll means more to 76 my little girl than you could imagine” re- minds one that business built on simple sentiment is none the less real business. One factor that makes many sales is that the human hair of any member of a family can be made into a doll wig and thus kept as a souvenir of sentiment. The doll hos- pital is also an agency for the sale of new olls. New Income for Radio Men Thousands of readers of this magazine are rather proficient in radio and could very well profit by the experience of a young Buffalo, N. Y. repairman who, with things so quiet recently, got several big contracts from the larger music teachers of the town. He thought it would be a fine idea if he sold those teachers of voice cul- ture a recording outfit so that their pupils could correct their mistakes by listening to their own voices. After each lesson the pupil could sing a number that would be recorded and then take the small, inexpen- sive record home to let the family hear it. Other teachers flocked to have similar sys- tems installed and several thousand dollars worth of business was developed within a few months. It was the type of installation that could be handled by any good radio experimenter. Electric Gas Stove Lighters ‘Tf a chap wants to go to some of the automobile junk yards today he will find that he will be able to buy all of the old Ford ignition coils that he can carry home for ten cents apiece. With two dry cells (of the small type that may now be purchased in the chain stores for ten cents apiece) these old coils make an excellent source of high potential for lighting gas stoves. The only other thing that is needed is a high potential electrode that can easily be made in the home shop. We still have in use many thousands of gas stoves that have to be light- ed by matches and each user of such a stove is a good prospect for such an instal- ation that may be made very profitably for about two dollars. An electric gas stove lighter, operated by Ford ignition coil and dry cells, is welcomed by many housewives. Modern Mechanix and PAINT BACK WITH BLACK Custom Built “Coasters” _A California man got his big idea while replacing a broken window pane in his house. Out of work for some months, the idea occurred to him that the glass could be used for making “coasters’”—which, if you have never heard of them, are small plates on which wet glasses are set to avoid marring the surface of a varnished table. Scraps of window glass, cans of auto enamel, a glass cutter, brushes, sand stone and felt are all the equipment required. The steps of manufacture are well shown in the illustration above. Any magazine drawing which lends itself well to silhou- ette can be used. The outline is painted in black enamel, and after it is dry colored backgrounds painted over it. Felt or velvet is then glued to the base to prevent scratch- ing furniture, and the edges of the glass beveled off on a small grinding wheel. The originator of this idea finds that he can secure enough orders in one day's solicita- tion to keep his factory busy for a week. Glass can be salvaged from broken panes. Neighborhood Small Stock Butcher An unemployed man, seeking to “earn his eats” by odd jobs around produce mar- kets and grocery stores, discovered the need for a small stock butcher at these places. The dealers, preoccupied by the many details of the day's business, are glad to turn over the task of dressing poultry and rabbits to this man. With only slight experience on farm and game fields he soon became rapid and skillful in dressing these meats to the satisfaction of the customers. The larger part of the difference in price Inventions for May Continuing the presentation of a series of articles on money-making | ideas which have been proved out in practice. Steps in making coasters: Sil- bouette design is traced, colors applied, coat of enamel painted on, feit glued to’ back, and edges beveled o EDGES OF GLASS between live stock purchases and dressed meat purchases goes to him as his fee. There are two side-lines to this job that bring additional profits: making quick deliveries for the dealers, and killing and dressing poultry for housewives who find such a task far from their liking. Now the new special- ty butcher serves three dealers; he is pul- ling through the dark days with a moderate livelihood and he is laying the foundation for his own poultry and rabbit market that he has planned to start. Spring Housecleaning Opportunities With the spring season for housecleaning under way, the man who has a few pieces of household equipment which he can throw into his car will find his services welcomed by many housewives. A vacuum cleaner with attachments for cleaning mat- tresses, mouldings and baseboards, a carpet beater to accommodate the woman who still prefers to have her rugs taken outdoors and beaten, a chamois and window clean- ing materials, floor waxer and polisher and a good furniture polish, will bring many an hour’s work. 77

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ants ROW “BLOOD” for HUMAN HEALTH First step in production of chloro phyll is drying of leaves in oven, Second step— Dried leaves are placed in “ball mill” and ground to powder by stones rolling around in interior of re- volving drum. Mask guards lungs against dust from leaves. HE ancient sun worshippers, it now ap- pears, had a theory of life, and its re- lationship to man, which has now been proven scientifically sound. The chemists, biologists, physicians, have discovered that life comes from the sun. Furthermore, that plant life and hu- man life are chemically related if not one and the same basic thing. Out of the lab- oratory of the organic chemist comes sub- stances that show such a relationship. Physicians have for many years been advising people to eat more green vege- 80 Three stages of chloro- phyll production—the leaves, the powder and the pure chlorophyll. Third step—Liquid chlorophyll is run through silver lined centrifuge to remove all impurities. Dr. Schertz, who has achieved prominence for his experiments, is pouring. tables. “Old stuff!” you say? Yes, com- paratively. But the green foods, such as lettuce leaves, spinach, kales and others, contain vitamins, needed by the human laboratory of the body. Blood and the green of the leaves (chlo- rophyll) are practically identical. Chloro- phyll contains carbon, hydrogen, oxygen, nitrogen and magnesium. The only chemi- cal difference in the organic construction of the chlorophyll in plants and haemo- globin in blood is that the former con- tains magnesium while the latter contains iron. German chemists taking their chloro- phyll product that they derived from the leaves of growing plants, made them into pills which they gave to patients in clin- ics and hospitals, keeping a minute medi- Modern Mechanix and Flaming surface of the sun, scientists believe, is source of the chlorophyll which colors plants and sustains life. E Here's a tube of pure chlorophyll, or "concentrated sun- light," extracted from a batch of leaves. At right scien- tist is seen measuring work performed (consumption of oxy- gen) by man sawing a board. Dosing with chlorophyll, tests showed, greatly increases energy production. cal record of results. These pills, which may well be called “concentrated sun- shine,” produced amazing results. The facts, as recorded in the unemotional, mat- ter-of-fact statements of the German scien- tists, would show that these chlorophyll pills reduced high blood pressure, elimi- nated anemia, made weak men strong, cured digestive troubles, and seemed to be in fact, a pill of youth. Once in the digestive stream chlorophyll immediately enriches the blood. The red blood cells immediately increase in num- ber while their haemoglobin content rises. (Hemin, of the blood, and chlorophyll, are practically identical.) The blood thus en- riched and reinforced with new life is able to bring about amazing recoveries. The eating of green foods is taking chlorophyll into the body’s chemical lab- oratory, but the taking of a concentrated form is merely a short cut in giving the body a tremendous amount of it and the reaction is positive, The sunshine that the plant caught and benefited by is thus passed on in the form of blood-life for the human being. Dr. Schertz, an eminent American chem- ist, suggests that chlorophyll gives us the clue as to just what life is. He has found a way to extract pure chlorophyll from plants easily and cheaply enough so that Inventions for May CARBON © CARBON HYDROGEN = HYDROGEN OXYGEN OXYGEN NITROGEN MAGNESIUM. _ NITROGEN -IRON CHLOROPHYLL x ʻi CONVERTS CARBON x DIOXIDE INTO PLANT CELLS. c , CONVERTS X YGER- ANTO ENERGY Close relationship between green of plants (chlorophyll) and haemoglobin (blood) in human beings is seen in the chemical constituents of two life-giving substances, Note also similarity of the vital functions performed in organisms. it can be used commercially, although he was not the first to isolate it. The humanly useful place of chlorophyll is explained as the one link of nature for the converting of energy into matter. The energy reaches the earth in the form of sunlight and cosmic rays. By some mys- terious process this energy is transformed in the plant into matter. The chlorophyll plays the chief role. (Continued on page 141) 81

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SEA COURTS EXPLAIN „WHITE LIGHT RED TO PORT GREEN TO STARBOARD M Here is the usual complement of running lights on small ships. “Green to green, or red to red, — perfect safety: go ahead” is the sailor's operating code. HY would you like to sit in on a “traffic” case involving perhaps a million dol- lars for an accident that took place where there are no roads? Would the interpretations of the “rules of the road” bother you, especially if there- were no avenue names, no curbs, no sema- phores, no roads as we know them? You bet your life they would. As a mat- 86 Admiral Von Usslar, representative of the German Reich, at left, is conferring with nautical counsel regarding the merits of an accident which is impossible to re-enact for juries without use of models, as otherwise the jurors in- variably become confused with the unfamiliar terminology. The jargon of the sea becomes doubly confusing to laymen who sit on juries that deal with nautical accidents. This article tells how models are used to re- enact the strange "rules of the road" for jurors who have never been to sea. ter of fact, the most highly specialized judiciaries in the world are the maritime courts where the judge must not only be a sailor who understands the jargon of the sea, but must also be an astute juror versed in the hodge podge of legal meanings and shades. The usual whereases, and deponent say- eths not of the courtroom are further mired in verbiage when the lingo of the sea is in- troduced. You can readily imagine what happens when a volley of words like “ves- sel of first part, being on port tack, deposes and says that vessel of second part, being also on port tack and converging upon course of vessel of first part, which un- laden, had right of way over starboard bow dead ahead—,” etc., are thrown at an ordi- nary jury. The result is chaos. Consequently America, England, France and Germany, all nations who do a great Modern Mechanix and eAccidents with e?YCODELS Listing heavily. as the beam wind strikes her sides, the liner "Atlantique" is here shown drifting toward the Cardiff cliffs of England, a mass of flames. This picture was taken but a short time ago, when the drama shown at right was enacted upon the high seas, demonstrating marine law. deal of shipping, have their own special courts in Marine Chancery. Here, to make things clear to the jury, who are selected from among seafaring folk, models are used to re-enact the accidents or points of dis- pute. The photographs show Admiral Von Usslar, representative of the German Reich, using some of there models in conjunction with charts to re-enact maritime disputes and accidents. In no other manner could the physical positions of the free vessel and the offend- ing vessel be kept clear in the minds of the untrained men who sit upon the case. All nations have uniform “rules of the road” in that great International occupan- cy, the Sea. The courtesies, the lights, the flags and the manner of conducting ship- ping are all uniform. Consequently, with so much room at one's disposal, the rules for the high scas are rather simple. The left hand side of a vessel, facing the bow, is the port side. The right hand side is the starboard side. In sailor’s parlance, in which the courts are conducted, port, starboard, port quar- ter, starboard quarter, dead astern and dead ahead are commonplace designations. Even these terms are fairly clear to a lay- man. But when one vessel bears down on another, what are the rules to follow? Seamen have little ditties that hold good Inventions for May FRENCH CAPTAIN HOISTS FRENCH FLAG A ship afloat without crew is the property of any vessel negotiating salvage. Dutch trawlers hooked to the “Ate lantique" at the same time French vessels made fast to the stern. A tug of war ensued, neither nationality victorious until the French captain of the * Atlantique" was put aboard again to taise a French flag on the jackstaff, as shown. in cases like this. On the port side are red lights, on the starboard side are green lights, on the bow of the ship is a white light, and high above, toward the stern is another white light. This is required by Interna- tional law. When ships approach each other, the sailor recalls, “Green to green, or red to red, perfect safety—go ahead." During the day this matter is simple, but it is at night when the navigation of the ship becomes confusing and must be con- ducted according to light. Any other condition is met by another simple rule. Two vessels meeting head on will signal. If one has any special reason for wanting passage on a certain side, it will sound the whistle first. One blast means the vessel will pass to port, and two means it will pass to starboard. The other 87

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Building the CABINETTE Here is the trailer for the man who wants to see the country comfortably in a mobile home of his own. It can be built for around $50, according to locality, and will prove a satisfactory place to live on a country-wide tour. (HIS cruise trailer was designed to do but. one thing, and to do that.thing well: furnish a comfortable traveling accessory i the modern tourist in which he could ive. There is room enough for four bunks, although only two have been shown. There is a water closet, and a sludge tank for dish- water and sewage can be installed under the house for use when parked in some place too pretty to despoil; there is an ade- quate galley or kitchen containing a sink with running water; there is a pantry for the storage of food; there is a bureau for nick nacks. Every function of living has been accom- modated simply, yet adequately. One can live, sleep, eat-aboard this cruising trailer, and carry his home with him wherever he goes. The factor on which the whole design hinges is the chassis. We use an old Model T Ford chassis as they are the easiest of all old auto frames to procure, and as well are notoriously long lived and free from wheel trouble. Also the tires are dirt cheap. The best way to work is from the ground up, and the first thing to tackle is the con- version of the trailer. SPACE ROOF CARLINS FIRST STEP IS AS SHOWN LEVEL WITH FLOOR OF TRAILER imi PES Hm STRAP HINGE ERI The building of the body or cab is simple as we have designed it, but the matter of underslinging a Ford chassis is a horse from another stable, and therefore let's go into this most important end thoroughly. As shown in Fig. 7, top, the Ford channel Írame is 23 inches wide. It is four inches higher at the rear than at the front. Also the frame proper is way up in the air, far too high to allow us to put on a cab body with nearly full 6-ft. headroom unless we lower it. Make strap spring shackles for the rear end as the drawings show. Any-blacksmith can do this for you for very little money if you don’t have the facilities yourself. The idea here is to get the shackle long enough to let the whole frame down so it is level. The wheels are mounted into the | ASSEMBLY, DETAIL OF. | STEP HINGE D 6X IË BARS ADAPT ENDS TO CAR MN DETAIL OF SHOCK ABSORBER SS BOLT AROUND STRING! D- CHANNEL AT» THIS POINT: == n ‘SPRING. E HANGAR 5 SEE DETAILS TOW HANDLE SEE DETAIL 8"TO WHEEL BASE INCREASED y BY CHANGES EIG.U TOGGLE ("BRAKE The little drawing in Fig. 9 shows how to determine the right length of tongue for the towing arm. The middle inset shows a fine shock absorbing hook-up to be attached to the towing car. Fig. 11, below, shows how the stringers are attached to the channel frames after the chassis has been underslung, re a Modern Mechanix and I — 19 — 4! t M 14 ————— ruise 'ORAILER P AY PA, NA VS INPS LEASES BASS PC Trailer cruising has become really a smart thing for people to do. This Cabinette idea is just another step farther along toward the ultimate in inexpensive and practical trailers for tourists. new spring perches, see Fig. 3, and the radius rods heated with a welding torch, bent, and re-seated. This takes care of the rear end, just as simple as that. See Fig. 8. The front end underslinging is not hard the way we have it doped, either. See Fig. 3. Remove the front axle from the Spring. Turn it around, end for end. ; This now places the steering tie rods forward. Bore out the taper E seats on tbe present spring perches, and re-bush the old ones so they have parallel shanks, and bolt them up- Here's the arrangement that will prove most satis- factory for extended cruising and living on the road. shackles for the front spring, This part is highly stressed and nothing but Chrome moly will be safe. Plymouth rear spring shackles can be adapted, or an iron store or hardware store i can order for you what you need, as they have wholesale service a side down. to pe apor daily and it does ý i not take long. aoe Then comes the only little The U SE. cities are piece of fussing you are put e to. in doing the job. carefully heated, and slowly bent so there will Vn Jou mut a ivbdenmn be no cold shuts in the S. rod t ot which Van angle. When these have ael can make the ew U been turned out of 34 802- TRAS S E The Cabinette cruising trailer can be wheeled to any spot, no matter how wild or how civilized, and be a self contained living unit with its own water and sewage system. Privacy, comfort and adequacy are all yours with this simple job. Inventions for May 99

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Steps to Follow in Conversion CLOSE HOUSING WITH STEEL PLATE FLATTEN HAND BOLT: rd | CHANNEL FRAME f RIVET TO È METHOD OF SECURING TH ERONT. RADIUS RO SPRING PERCH IS. A TURNED UPSIDE DOWN FORD FRONT AXLE IS TURNED END FOR END, i PUTTING THE STEERING VENGTE OF SHACKLES RODS IN FRONT, SO FRAME CAN BE SUSPENDED AS SHOWN AS NEEDED REAM HOLE PARALLEL, REBUSH AND REBORE SHORTEN TIE ROD FOR THE PROPER" TOE-IN* d HOOK AND ^. j CLAMP AROUND 7 THE AXLE BEARING ARM WELDED BOLT sw Fics TOW HOOK-UP LE DRILL AND SPACE $ AS SHOWN Ford. chassis but with. tie rods in front. 100 " E sTL.PLATES stock for the ends to land in the spring and perches, they may be bent. The threading is, of course, done before any heating takes place. The front radius rod is bolted to the strap cross arm which has been moved to fit. See Fig. 2. The ball of the radius rod is softened by annealing, ground to wafer shape, drilled as the details show. Now this change will place the frame very close to the axle line. When the stringers for the body are bolted to the frame there i will be about 4 in. road clearance for the body—not much, but not any more can be doné with this item; remember this is an adap- tation, and we have to take the best we can get out of circumstances which are beyond our control. This one little point is the only thing where the whole design could be criticized. If one does not travel too fast over rough ground there will be no trouble. All rough corners should be taken easily, for it does not matter whether the axle comes in contact with the stringer as long as it is done gradu- i ally. On paved or gravel roads you can bounce along merrily. The front tie rod will have to be shortened so that the wheels have the proper amount of “toe-in.” Measure the distance between the wheels on the out- side and inside, back and front, and shorten the tie rod with a welding torch until the wheels track as they did before the axle was turned end for end. This point is highly important. If you do not do this, towing the trailer will amount to the same thing as trying to drive an auto backwards at high speed. It will wreck the trailer and throw it out of control. SE s For steering a special kind I of trailer hook up is made. In this galaxy of draw- ings will be found the essential points covered in con- verting the Ford T chassis to an underslung trailer chassis. Fig. 1 shows normal Below is shown chassis finally converted. Modern Mechanix and See Figs. 4, 5 and 6. The drawings show how a plate of !4" wrought iron is bent around the axle, and secured with two W” hook bolts which can be made by any blacksmith. A 94" hardened steel pin is run through the towing tongue and this plate. It forms the pintle through which the towing and turning stresses are focused. It therefore must be this heavy, and be hardened. The Trailer Tongue . The tongue itself is of pipe. Two-inch pipe will do. An alligator mouth is sawed in one end, and a piece of hardened strap is riveted on the end. If the pipe is left top and bottom to carry the load it will soon chew off and you are in danger of losing your trailer. With a piece of hard- ened strap on the tongue you know that can never give way. The strap for the tongue makes this a universal joint, and it is stiff enough for towing and steering. An ideal arrange- ment, and it has proven itself on several hauls of over three hundred miles in length already. With these changes made, you are ready for the body, but J have one more word to offer. About the tongue length: Every car has its own turning radius, and so does atrailer. The two must have a tongue of just the right length, otherwise both towing and corner-taking will be (Continued on page 138) ROOF COVERING OF 3X 4" BEADED CEDAR * NAILED.~ COVERED ALL SIDES OF 3 X4" BEADED WITH BOZ. CANVAS: CEDAR, FASTEN WITH. SCREWS FLOOR OF x 4" FR COMPLETE FRAMING ASSEMBLY WHEEL BOXES OF 20GA. GALV. IRON Ees FASTEN WITH SCREWS Top right shows rear elevation with miscellaneous details. Details of Strong, Simple Framing / METHOD OF AR REINFORCING — x2" 4.0 CORNERS. bis FIGS LLL PD ia T ES CARLINS ARE [3X 15 W.OAK ~ SPACE AS SHOWN iN FIG=IT STUDS ARE I" x2" W.OAK Z"K4" STRINGERS OF W.OAK Middle detail, Figs. 14 and 15, show framing and window details. Below in Fig. 16 are shown major elements in straightforward frzming plan. Materials can be procured locally. Inventions for May 101

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A Wooden WATER Wheel for the ARM STREAM apart, use half for each hub. Now get two dises of boiler iron or scrap sheet sieel and have a 2 inch rough hole burned in the center of each disc. These discs should be %4 inch thick by 15 inches in diameter, shown in Fig. 4. They can be cut sullicient- ly round with the welder’s cutting torch. Mark off and drill the dises centrally from the holes in the coupling halves and bolt the discs fast to the coupling halves. Have six 14x114 wrought iron bars each 2516 inches long welded to the discs as shown in Fig. 4, placing the arms radially on 29 inches radius. When the arms are spaced correctly around the disc, the dis- as shown for bolting the arms to the wood rims with lagscrews. Now let us get the shaft ready. It should be of 15 inch diameter, 4 ft. 6 inches long, sawed off square on each’ end, but noi necessarily turned off. We are now ready to bolt the arms to the wood rim and this should be done with the arms on the shaft, as in Fig. 4, so every- thing is lined up centrally. Using a rule, measure to see that the shaft is placed in the center of the wood rims, as [his is important for good running balance. The ated, but the coup- Jing hubs can be drilled and lapped for inch setscrew in cach and the cone points All that is needed is 2 sixfoot head on à 167316" fume im order to get 114 overshot type, and housed in the dog house above are the pump and dynamo bp, from this simple wheel. It is of the is capable of driving day im and day cut. This simple wheel will develop a full one and one-half horsepower on a head of only six feet through a sixteen inch flume. Many farms can take advantage of natural resources in securing light and power this way. by JOHN S. (RE are complete plans and instruc- lions to build a 5 foot rustic wheel for the farm—one developing under only 6 foot fall at full capacity, an honest 1% horse power! It will drive a 1 kilowall electric generator at night and the house pump by day; furnish about 30 twenty five watt lights at night and lots of water y day First, cut out 24 curved segments as shown in Fig. 1, to make the two side rims. Each rim is to have two layers, break the joints midway and nail together with ce- ment coated nails, if you can get them, on 3 inch centers. Cut tbe segments out on a band saw to dimensions. One segment takes a piece of lumber 11x34x30 inches exact. Now cut out 46 pieces of 3x%x19 inches long tongue and grooved boards and nail to the inside of the rings as shown in Fig. 2. Lay these tongued and grooved pieces up rather tightly, as they are meant to hold water under alittle pressure, two nails each on each end. These go all the way around the inner rim. 106 CARPENTER Vext make 14 water buckets as shown in Fig. 6, beveled at the tip where it cuts the waler jet, and nailed with 5 nails to the backing piece. This will require 14 pieces each of 8x%x16 inches long and 5x%x16 inches long. Using a Seratch awl, lay off a circle 1 inch in from the outside circular rim, on ihe faces that are lo be the inside of the wheel. Then lay off 14 spaces along these circles, with your rule, or dividers set at 12% ‘inches, which will thus divide off equally, the bucket spacing. Set the beveled tips “A” Fig. 6, on these spacing marks all around the rims, so the buckets: will be correctly spaced and so the wheel will not run lopsidedly, Toe nail the buckets in the rims and see thai the seat "B" comes down squarely on the %x3 pieces nailed inside the ring. If they do nol, a litle beveling at "B^, Fig, 4, will make it right. Be sure that the ‘buckets fit rather snugly in the rims, but not excessively tight. To make the hub and arms, we first get a 1& inch flange coupling and taking it Modern Mechanix and tance apart at the tips of same, center to center, will just measure 20 inches, Punch two ¥@ inch holes in one end of the arms can be let into the shaft about % inch after the location has been found. Now we can mark off the holes for the arm lagscrews and thus bolt the arms fast to the wood rim. Should it happen that the wheel will not turn evenly when start- ed, we can drill new holes for the arms and plug up the old ones. LL Vt —| à Lf LAG scis" LL gh JONSUDAND OSAD : rl wrouchr oia. || corar j SPE ae A eed E pr Ce FLANGE LANE j PULLEY FOR GENER Aon ET FiG.2 SECTION OF WOOD BLOCKS CAST WHEEL TN CONCRETE . Aéscue aun | VL EBONo "NI cunved dents VOTRE Ros GENERAL VIEW OF WHEEL Curved segments, 24 in number, are used in the construction of the whecl as shown ig Fig. 1. The centerline of the wheel is 407 above the rinofl water to get good clearance without sacrifice of head. Fig. 3 shows the concrete spillway. Inventions for May 107

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This shows how the dtyer and developing drum is set up on the apron of a sink. | Note the jogged secondary trunnion support for the axle. This permits the drum i to be raised free of the trays and thus allowing it to be speeded up for drying. Note the motor and a suggested drive. 'To the left is an inset showing the negatives tucked into the brass septums ready to be run throught the developer.

Labor Saving Photo Developer by ROBERT C. QUIGLEY THE professional photographer always has a lot of work on hand. The amateur, more and more nowadays, saves a batch of films and then does "em all up in a hurry. Both of these gentlemen give splendid imitations of a one-armed paper hanger caught in a high wind when they get in their dark-rooms and try to wash each rint, one right after the other. Generally aw and order go up the flue and hit and miss arrive with a flourish. But here's a rig that organizes a relatively large amount of work and pushes it through the soup with a delightfully progressive orderliness. The machine is at once a developing ma- chine and a dryer. Tray Slips Under Disk Two wooden discs about 24” in diameter are mounted on an axle which is connected to a motor by gearing and pulleys so that the wheel will turn 78 r. p. m. on one belt and 300 r. p. m. on another. The axle mounting is loose so that the developer tray can be slipped under it when it is raised, and successive trays of developer; water, hypo, and water can be used. Then the drum can be raised and the high speed belt used to whirl the negatives until they are dry. The same procedure can 112 be used for prints in their intermediary stages of drying before they become curled- and after they have dried sufficiently to be inserted in the brass septums. These marginal septums are made from brass rod and are spaced according to the size of the cut negative. There is a small slot run into them on the milling machine. If you do not have the facilities for making these slots any machine shop will welcome eO of putting them in for you on their miller. How the Film Is Held The ends are flattened and screwed to the dises. The film will snap out enough to be held with sufficient rigidity in the slots while the drum is rotating. Brass and bronze should be used for the fastenings as they are chemically inert to most of the mild acids once a salt has been formed on them similar to rust, and they do not deteriorate after that. No formula can be given directly for the exact size of the wheel and for the exact speed. So much depends upon the element of time used to develop, wash, fix and rinse. The way to approach the determination of speeds is to equate the time normally con- sumed in developing to the trip time through the developing bath, working Modern Mechanix and

Developing, Fixing and Washing Done on Single Automatic Machine down from the speed of the motor and the pulley ratios, using a fixed motor speed of 1,750 r. p. m., which is the fixed speed of all induction motors running on 110 volts a.c. This will allow you to put in the films on one side and to take them out on the other, dropping them into the fixing bath. Another tray can then be lined up and the wheel run with its set of prinis for the right amount of time in the hypo. Then the washing can be done for a much more thorough job in less time by continuing the same speed and running in a tray of mildly circulating water. In Use as a Dryer When thoroughly washed, the wheel is speeded up to the figure given, 300 r. p. m., which will create a breeze on both faces of the negatives and do a good job of drying. On my machine I found that water spots due to irregular drying were done away with, and the films dried without curling, due to the evenly distribuled pressure over their faces because of centrifugal force. Fora man with alot of professional work to do such as is found in the 8-hour photo finishing service, these machines might well make the nucleus of a good business, especially in many of the smaller towns. In that case it would be a good idea to have several drums, and load one with ex- posed negatives, put it in the developer, and remove the whole wheel to the fixing bath, then move the whole wheel on to the other baths, having a wheel Speed 78 R. for each of the baths if the, TGs amount of work warrant- with solutions, for while Directiorr of Rotation, = PM. sample shots to find the right normalcy of solution for the most effective work. One kink which the amateur is generally not aware of is used by professionals in drying prints. That is bathing them in alcohol briefly after they have been thor- oughly washed, and then ironing them out on enamel plates with a squeegee. The alcohol takes the water into solution, and the print then dries with only the water of inclusion and the surface alcohol remain- ing to be evaporated. This will give glossy prints, and if you cannot find enamel plates with the baked enamel faces like automo- bile mudguards look when new, you can use plate glass as effectively. Prints after they have been partially dried in a machine like this should be press dried in blotting paper sold for the purpose by photographic supply stores. Frequently the amateur, and the profes- sional as well, is troubled with prints curl- ing after drying, owing to inequalities of surface tension set up by the emulsion. Large plants have devices which run the print through a series of rollers and so re- move the curl. The same effect can be secured by immersing prints for not less than five minutes, between washing and drying, in a bath composed of one part glycerin to seven parts water. -

edit. — o Buss Marginal | Considerable experiment- eptums fer <n | ing will have to be done 4, ing Films AN wheel developing is much more even on a given quan- tity of film, it is also a lot faster and you'll have to monkey around with some Brass Bearing b Take

Or Sewing Mach. Motor. o 5 Jew, ing Mach

ER Pound Belt I= jaian n cnr Lr i a AN AE Eu Gives Filo — heel speed

Plan Or Conr Assemely Or Develorine WHEEL labora tory Sink Board: Uo hele End Thrust End Members-Bolt EVELOPING pe Axle a lires Si b Sink Board Wreew-bithout the Old Electric fan = Dolled Line Driving Machanism| Lrotcates Fes: END Woop Whee

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Upper right is a view showing the developing drum with tray under for washing of negatives. The cross sections show the manner of grooving used in the brass rod septums. The ends of the rods are flattened and drilled for screws to hold them to the discs. A suggested drive is shown to the lower left. Note the method of raising axle. Inventions for May 113

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Scram's Simple Construction Is Strongest, Lightest and Tightest Known

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STATION 3 LOOKING FWD.

r1 kd : $ w = 7 5 2| Hi z% u 9 rz i 5 Ne Say zi 5a || Ii Eks dxá ix pri Wass | uic i. IL Quo xNE Fe hon DT "| a 2« zx SS Sud o Fila i = SS f H zz sS P ag 2a i ay [- ao ez z 5* at bo 23 i m ou =o ge, ow 5 z ra i ba 9| o: ul EH x «i E n i D 7 te E à d zs ó b es 3 Be z|o à b j s o z < Z| gz x jl gs rz os cix! x m m zr x x 3 zx = 5 8 z go Eio E MEE a= Here ia the construction plan of “Scram.” Don't ask us to figure the bill of lumber for you; you can easily dope this; out from. the scantlings and sizes shown above. Topside planking is J$' Honduras mahogany, bottom double planked of J$'" diagonal spruce with J$'' fore and aft mahogany outside. The fittings for the struts and the cast- ing for the rudder and rudder stock can be furnished by our Experimental Station. The motor plans of conversion will be run next month, complete in all details. 116 Modern Mechanix and

“Scram” in action reveals a brilliant boat with the so-called “level riding” any good design must exhibit, and as well has thundeting speed for a craft so tiny. Here she is pushing the forty mark, Sweet running, and sinooth, too. “PLANS for “SCRAM” PART II Here is the second installment of Westy Farmer’s most popular boat design. Further notes on her construction, with added plans and photographs, are shown in this month’s chapter. Lt month we took you for a ride in this fiery little, sleek little, inexpensive little thunder boat, and got you started along proper lines in building her. This month we continue but before describing how the frames are got out let’s have a word for the men who are here meeting Scram for the first time: She is 15% feet long by 5 ft. 2%” beam, by about 15” draft. Powered with a Ford Model A engine (which we'll later show how to convert into a 65 h.p. high duty marine mill) Scram is easily capable of leaving all present day two-cockpit run- abouts of her size in the lurch when it comes to speed. She banks her turns like an airplane and is a sure cure for all who crave real speed thrills. Best of all is the matter of the motor. We are working out a list of costs on the matter of finished machined castings and parts needed to take a raw Ford A Inventions for May block assembly, costing $59 new, and turn it into a hot marine engine—not a make- shift, but a real one. You will be pleased to know that the whole engine can be made for about what a good used large model outboard can be bought for. The Ford motor as it stands can be con- verted three ways: it can be put in a boat just as it comes from a car, where it'll weigh close to 600 lbs. and take up half the boat, developing 30-38 h.p. You can convert it a second way, using Ford parts and putting on an oil cooler and reverse gear. This is but little better. Then there is the way we have doped it out: deep base, oil cooler, high compression head, cooled manifold, downdraft and reverse gear. Last issue we ran her lines, outboard profile, pictures of the boat in action, and showed how to lay the lines down. If you have followed us this far you are now ready to rough out the frames. 117

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Turn to page 116 to the construction cut shown on that page. You will see that the frames used for making the molds, or for building the boat in other words, are at stations 5, 4, 3, 2 and 1. Now look at this page. Here you will see how the frames have been cross tied at the open part across the top, and how a 2" by 4" of some straight but scrap wood has been mortised so that the frame could be rigidly mounted on it. The 2" by 4" is held in line by two strong- back pieces upon which the frame is set up. 'The frames are properly spaced out on this strongback, and the intermediate frames are placed in the boat after the planking is 2X2" WHITE OAK CHINE Showing Complete Frame Details 3-8" MAHOGANY TOP ‘SIDE PLANKING COMPLETE "Ser Ue" —fFoRScRAM. STERN View AND FWD COCKPIT. TRANSOM Above circle shows transom and chine de- tail, The center view shows how frame will look on the strong- back. The two by fours and the braces are, of course, knocked out when planking is completed. .done. This saves a lot of fairing and fitting which would otherwise go to waste. The number of frames indicated are amply strong for building the boat. The stem is cut and rabbetted as per the drawing on page 119, which shows how the rabbet is cut and how. the clamps join ihe breasthook. It is easier to make little brass clips for the heels of the frames than ‘118 f Photo above shows how diagonal pieces are fastened in. Drawings and photo to left and above show how boát is built without transom, which is fastened on out- side after the planking is done. This is easier, and’ just as strong construction. to lap the heels of the frames together. We can furnish you these clips cast in aluminum if you care to write us. The cost is moderate and the labor saved is enor- mous. Also the resulting job is stronger than as though the heels of the frame at the chine were riddled with screws in the wood that remains after the mortise for the chine piece has: been: cut. Modern Mechanix and The transom frame is put up at the same time as the others. The notches for the battens are done after the frames are up. There are four planks on the topsides, equally spaced in width at the frames. The battens are 36” by 14%” white oak. They may be spliced with feather edged splices if the stuff cannot be obtained in 16-foot lengths which will be necessary for the work. ; The battens are CONSTRUCTION DETAILS FOR let in flush with the edges of the frame, which has, of course, been trimmed off the thickness of the planking as the lines are given to the outside of the planking. The stock for the frames is %” x 3%” mahogany on the main frame set ups, and %” by 3%” on the intermediate frames which are put in later. . The battens are feather edged into the stem, and all fastenings are countersunk, be- ing brass screws, No. 7, %” long on the battens. Also the same for the clips at the frame heels. Chine Is Next The next piece of wood to be put in is the chine. This is a piece of 2” x 2” white Inventions for May screwing transom onto hull. and second [ayer of outside 75" mahogany, which is laid over cloth and marine glue. Center isometric view shows cutaway details of the hull’s construction. Frame and clamp details are shown also. Bottom photo shows method of using template for marking crown of the deck beams. oak, or preferably mahogany. Anchored to the transom through the corner edge of the chine piece, liberally countersunk (No. 8, 112" f.h. brass screw) the piece is successively fastened to the frames as they run forward, and is tapered and cut a bit toward the stem to make bending easier. A rope windlass will bring the pieces in for fastening if you are not able to soften the wood with rags soaked in hot water. Then the bottom battens, underlaying the diagonally laid %” spruce inner bot- tom are put in. The method of notching is as follows: CONSTRUCTION METAL CORNER CLIPS: Top photo shows method of cutting off battens and planking flush with the transom frame before Left upper detail shows diagonal planking Cut one notch in the frame forward. Spring the batten back over the frames, mark the spot it crosses each frame, then saw to the inside of these marks, and cut out the notch with a chisel. The battens are allowed to run past the transom frame, as the planking, battens and all are trimmed off the last thing prior to putting on the transom itself. Why this is done will be explained later. Topside Planking Comes First The topside planking comes first. The chine is rabbeted on both the bottom side and the topside, a rabbet, or groove, being cut deep enough to take %” planking on (Continued on page 140) 119

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a Amateur radio station with 20 meter transmitter in operation. Fig. 1. Top view shdws he O NWH 233 OR o ont! Tus PLATE EKET VOLTAGE + z o ASH | (lig hs) D acfeen l/SCREEN m; ) VOLTAGE + GROUN 4 ON SHIELD [o ou» .002 GRID PLATE COI -> aee TO ANTENNA FEEDERS Pd - = N ANTENNA Eq CENTER TAP COIL SS ae ES aT «| FAHNSTOCK Lj CLIP COND. E d rs == Py G I 10000 OHM ———— 25 WATT GRID LEAK with Entire Continent on Signals from this little transmitter, which can be built for about $5, will put you in communication with all amateurs within 2000 miles. Get on the air with it and make radio friends all over the continent. HE little transmitter shown in the ac- A companying photographs and sketches has been designed for the amateur who wants to operate on the 20 meter band ex- clusively. The new power tubes called pentodes are used as the oscillators, a pair of them being used in a push-pull circuit. This transmitter is for code work only. Due to the push-pull circuit and its inherent stability, using a good DC power supply, with the circuit properly tuned, the note will have nearly crystal characteristics and your reports should be consistently ‘Xtal, pure DC". ` A pair of 247s using 500 volts will give an output of between 12 and 15 watts. Two 233 tubes at 180 volts will show consider- ably better than 6 watts. The transmitter as shown, exclusive of tubes and power supply, can be built by the careful buyer for less than five dollars. Using 247s over a month’s use, the set gave excellent results, and consistently contact- ed amateurs between 800 and 2000 miles. Note the neat appearance. All wiring is done beneath the baseboard as seen in Fig. 4, leaving just the dominant parts above deck. This base was a single board smoothed down and cut 15 inches long by 10 inches wide. The parts were arranged exactly as shown in Figs. 1 and 2. About 4 inches from . ~~ 100-200 OHM SUM FIL. RESISTOR gn Cem o Qum f TSA” FILAMENT * VOLTAGE Ex 1000025 d MIDGET CONDENSER (7 PLATE) £00025 VARIABLE CONDENSER GROUND ON SHIELD SS Wl y Fig. 2. When secured to baseboard, all parts are hooked up according to this diagram. Fahnestock clips for external connec- tions are disposed along sides and rear. Parts shown in dotted lines are mounted under baseboard, where all wiring is run. 124 Modern Mechanix and this 20 eACETER Cransmitter HOW TO BECOME A RADIO AMATEUR Want to get on the air and talk to the whole world with your key? How to build and operate your own short wave station, how to master the code, and how to procure your radio amateur’s license—everything you'll need to know is told in the booklet "How to Become a Radio Amateur" available for 25 cents at Modern Mechanix and Inventions, 529 So. 7th St., | Minneapolis, Minn. 1 each end and 2 inches from the rear edge place a sócket as shown. Use 5 prong sockets for the filament type tubes such as the 247 or the 233. For pentodes indirectly heated (having a cathode) use 6 prong sockets. Face the two heater prongs of each socket towards each other. Use an 0 to 200 millianmeter. To the back terminals fasten two stiff wire legs bending their ends at right angles to fit in the clips on the base provided for them. You can thus take the meter out quickly if necessary. Provide a small jumper wire with clip to shunt the meter out when keying. The grid coil consists of a piece of wood- en window shade roller 2742 inches long. Using No. 30 DCC wire, put on two sepa- rate windings of 8 turns each, as illustrated. Space the windings about 1 inch. Fasten the winding ends under the heads of pins cut off and driven into the wood. Connect the two inside turns together to form the center tap. The .000025 midget tuning con- denser, of course, is mounted in front of the coil in a vertical position. . When the coil is finished flood the wind- ings with waterproof cement so the turns will retain their position. Otherwise any (Continued on page 136) 00025 VARIABLI CONDENSER Q MECHANI=— e CAL CENTER | PLATE COIL Lar TOK, = ANTENNA ANTENNA f PULS coin —200 MILLIAMETER .002 FIXED B+. Ov.0.C. à FOR- 2335 500 V.D.C.FOR 247'S GROUND ON SHIELD E e^ RA CHOKE 2 BEE Fia] V PEZ = iame FILET RES A AVOLTAGE 2V.FOR &- 2335, 21V. FOR &47'8 GRID VOLTAGE e1 —90 FOR 233, 135-180 FOR 247 R.F. CHOKE FILM SPOOL "SSE 60 TURNS 230-32 DCCWIRE TO GRID " WINDINGS EACH 8 TURNS 330 DCCWIRE WIRE LEGS FOR METER PLATE COIL 5 TURNS JY COPPER TUBING ANTENNA COIL 7 TURNS #f10-12 COPPER WIRE ANT, COIL’ PLATE COIL’ LUGS Fig. 3. Milliammeter is supported on wire legs. Below, how plate and antenna coils are wound and fitted together. Underside view shows how wiring is done. Note cleats which hold board up from table, allowing space for wires. 233 OR247 TUBES SHOWING CATHODE CONNECTION: FOR 238TYPE| GRID COIL C.T.FIL. RESISTOR 0OUUUU UU 10,000 OHM 25 WATT LEAK 000025 MIDGET COND. (7 PLATE) B= ANQ SCREEN VOLTAGE O + = KEY v. E GROUNDONSHIELO ^ Fig. 5. Follow this diagram also when wiring up with layout scheme in Fig. 2. Lead marked to ground on shield at left may be taken directly to B minus lead, which takes both plate and screen voltage minus. Screen terminal is marked K on tubes. Inventions for May 125

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eZYCIDGET *Üacuum Sweeper Operating like vacuum sweeper, the | little “eater” sucks the table clean of crumbs or clears work bench of shavings, Here’s how to tack the metal plate over the block with the V-shaped notch. End notch comes under the center of fan. PIN AIR CURRENT Drawing shows details of the 126 “electric crumb eater.” Blades of fan, curved to a 2-in, radius, are soldered on the brass disc, with the small end in the center. Six blades are placed equidistantly apart. LTHOUGH designed primarily for pick- ing up bread crumbs, the midget vacuum sweeper described here has been found useful for a great many things—col- lecting seeds dropped from bird cages, re- moving lint from odd corners, gathering up sawdust and chips after home repair jobs, cleaning the shop workbench, and so on. The motor was part of an electric mixing device obtainable at 25c stores. After the parts of the device were discarded, the motor was mounted on a square piece of 14 in. plywood just large enough to extend a fraction of an inch beyond the fan edge. This fan is made from sheet iron or brass as illustrated in an accompanying drawing. Cut a disc 3.to 4 in. in diameter, and drill a hole in the center to fit over the motor shaft. Cut six blades to a shape that re- sembles half of an orange segment when seen from the side. Bend these blades until they are curved to about a 2 in. radius. Solder them at equidistant positions on one side of the disc, the small ends at the center. They should be placed so that the convex surfaces are towards the direction of rota- tion of the fan when mounted on the motor shaft. A collar such as that shown in the drawings, riveted to the disc, is suitable for mounting the fan on the shaft. Now, when the motor whirls the blades, air will be drawn in at the center and thrown out at the edges. Housing Made From Plywood Make the housing from % in. plywood, and miter the vertical corners. Then cut a lid to fit down inside the opening. Mount the motor at one end of the lid by means of two crosspieces connecting the under- side of the lid and the motor board. The crosspieces should be not less than 15 in. thick, because one of them is to have a hole bored through it for receiving a locking pin. The lid fits down inside the box, and is held in position by corner blocks at the rear end. The front end is Modern Mechanix and leans “©able or “Workbench The motor is mounted on a plywood bottom board, which is mounted in turn on two crosspieces. =—j SeTscRew Mount the fan blades on the brass disc in the positions shown here. The disc attaches to the motor shaft by means -of a collar, to which it is riveted. Note blade curvature. supported by a semi-circular metal guard that is fastened in front of the fan blade. ` In the.rear end: of the crumb eater cut out a decorative design with a jig saw. The openings are to permit air to escape, and are covered with a porous cloth that catch- es dirt but lets the air pass. * Cut, for the bottom, a piece of plywood the exact dimensions of the lid, with the ‘exception that it is about % in. shorter. ‘This is to create a slit of “mouth” for the ‘Sweeper, at the front end. Next, make a block long enough to extend back from the slit to a point directly below the rear edge of the motor board. Then cut in: it the V-shaped notch shown in the drawings. Next, cut a piece of sheet brass of such size that it will extend from the _ Smear the vacuum cup with glycerine to strengthen. grip. Inventions for May The top of the crumb eater is re- movable for dumping out debris col- lected in the bottom compartment. nd The top is held in place by locking pin shown above. The furniture slides on bottom do duty as wheels for the “eater” and hold the box correct distance above surface being swept. inside surface of the front end of the box to a point 1 in. from the point of the V, and will go completely across the box from one side to the other. Tack this in place. This assembly, when the bottom is fastened in the box, forms a converging air passage from the slit to the center of the fan. After the lid is adjusted so that it fits snugly but does not bind, hold it in place (Continued on page 142) Making Rubber Vacuum Cups Stick UBBER vacuum cups have a way of los- ing their grip and thus becoming al- most useless. A way to restore their youth- ful condition .is to smear them with a generous . quantity of glycerine, giving especial attention to the edges. Such treat- ment will improve their flexibility and also their air-tightness. When stuck on a smooth surface they stay put much more firmly than if left dry. Apply a fresh coat of glycerine every once in a while. 127

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