Popular Mechanics 1928-10: Vol 50 Iss 4

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2OPULAR MECHANICS MAGAZINE WRITTEN SO YOU CAN UNDERSTAND iT #CGO TRACE MARK GREAT BRITAIN No. 410426 alg oe ee Ve gh os _—- . — NEPTUNE S BATTERING RA 5 A s - s

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- 2s Lh SL Sk lk A dk A hl A A A 2 A A A A A Make an Electric AC. Set of your Present Radio! ()! course you want electric operation of your radio. Everybody does! Radio was never so convenient, never so carefree as now when its only demand on you is the snap of an electric switch. But if you have a good radio now, don't discard it. A good time-tried circuit, using efficient time-tried tubes is naturally better than new untried circuits and tubes. There isn't a better A. C. set made than your present radio converted to use A. C. power. You don't have to change a single wire or alter the set in any And Kuprox has made conversion so easy ! way. No harnesses or adapters... no tricky wiring . not even new tubes are Just connect the Kuprox A. C. Power Pack to the battery terminals of your set, plug it into the nearest lamp socket, and your radio operates entirely from A. C. necessary. Then compare your radio with the best A. C heard. set you ever Compare the tone, the power, the dis- Kuprox Multi-rate Rectifier, for trickle charging, dynamic speaker operation, etc. Ad justable rate up fo l-ampere Kuprox Replacement | eliminates acids, | bulbs on all standard trickle chargers ’ Price $11.50 Price $5.00 . %,. ei mi *, Nay” 4 A a ve f oe f tance getting ability, the selectivity and eas« of control! In your set there's not the slight est hum, no distortion or crackling because of faulty tubes, none of the failings that varia tions in electric current can cause in A. C. sets A good battery set, Kuprox equipped, is A. ( reception at its finest! The Kuprox A. C. Power Pack contains no moving parts, nothing to wear out or break down. It is a permanent addition to yo radio that does away with all attention. Sey eral models are offered, some supplying fila ment (A) current only for those who already have a ‘‘B” eliminator, some supplying plat (B) current only, and several compact unit that supply all current (A, B, and C) a make the entire set A. C. from $32.50 up, and any good radio deal They are pri can show you the Various models. In case you first desire more information, specific information about your own set, f in the coupon, tell us exactly what set y have and the number of tubes. We'll recon mend the proper model Power Pack you nee and send you literature giving a full descrip tion. THE KODEL ELECTRIC & MFG. CO. Formerly the Kodel Radio Corporation 517 E. Pearl Street - - Cincinnati, Ohio PROX POWER PACK

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Popular Mechanics Magazine 200 E. Ontario Street, Chicago, U.S. A. H. H. WINDSOR, Founder H. H. WINDSOR, Jr., Editor and Publisher London: Hachette & Cie., Paris: Hachette & Cie., Melbourne: Gordon & Gotch ’ King William Street, Charing Cross, W.C. 2 111 Rue Reaumur 509-513 Little Collins St. 5SUED MONTHLY SUBSCRIPTION: SINGLE COPY, 25 CENTS In United States and its possessions, also Canada, Cuba, and rama per year, sine - $2.50 To all other countries in the Postal Union - : : - : 3.00 All subscriptions are discontinued at expiration. Please examine the date steal on your wrapper. Entered as Second Class Matter Sept. 15, 1903, at the Post Office at Chicago, Illinoia, under Act of March 3rd, 1879. Entered as Second Class Matter at the Post Office Department, Canada. shed monthly by POPULAR MECHANICS Co. Copyright, 1925, by Popular Mechanics Co. Copyright in Australia. Copyright in France Vol. 50 Contents for October, 1928 No. 4 Special Features Can Flyers Conquer Thunderbolts pe OR eee .. SS Guardians of the Sea. . pee oknneeombaliee staves teas 546 Trapping Wild Elephants... ......... eee. ao 557 Solving the Secrets of Life eR es idacue nee, BAS cenans 563 Fighting Fire with Fire Pere ere ba be tananas 570 Making Aircraft Airworthy eee scat seamew a 580 Sunspots Forecast Better Radio........................ Beas 594 Teaching Bees New Tricks er heme iae nny ickhsosberentex 603 Learning to Fly, concluded PLR URe resco ke eeddsentebeas 611 Neptune’s Battering Rams. __. pars Aeapabasennts ee A New Highway for an Old Empire ee ts eee 627 Growing Wings for the Army . baa ; | | 642 Advertising Aviation flying billboard has lights underneath wings 552 aided by old fire engine as cleaner for motors 578 plane as flying billboard shows signs by flags 579 airplane loaded in flight from metal chute 591 tank in form of pineapple for canning plant 560 air sickness prevented by pungent vapor 609 Agricultural Impleménts—cultivator saws the soil for air sign boards aid flyers win endurance record 574 better planting 552 glider sails four hours on American flight 592 Airplanes road sign for air travelers shows wind direction 600 fly from ocean liner with aid of catapult 545 Baby Carriage—fly screen guards infant's sleep 625 queer new, tailless, with movable wings 632 Bath Attachment—fountain for soapsuds and other Archzology—Ur tombs reveal ancient sacrificial cus- toilet preparations 602 toms 630 Boats and Boating Architecture—new ideals of beauty shown in European boat inflated like tire, fits in knapsack 555 cities 588 boat propelled by pumps develops high speed 647 Astronomy—world’s biggest lens to solve Mars riddle 636 electric lifeboat launched in three seconds 592 Automobile—combined with bike for deliveries 593 folding boat fits on auto running board 598 Automobile—Accessories outboard hull like plane gives high speed 607 bed concealed in top simplifies touring 617 sailing boats with big kites is latest water sport 591 folding armrest adds comfort in driving 576 Borax—to kill mosquitoes 562 safety seat for baby 568 Building Construction top over rumble seat quickly taken off 569 hoist run by truck is latest aid 617 Automobiles—Batteries—oiler for storage prevents cor- houses built flat on the ground and raised to posi- rosion 561 tion 635 Automobiles—Driving Corks—easily removed without turning 636 “cat’s eye” traffic lights guide motorists 602 Cotton—gas mask protects driver of duster for boll four-wheel brake tester aids safer 609 weevil 637 Automobiles—Equipment and Supplies Digestion—human body portrayed as a factory 626 gasoline vaporizer replaces carburetor 592 Doors roof top rolls back at pull of tab 619 folding partition is substitute for 608 Automobiles—Repairing rubber cushion silences slamming 553 trouble lights worn on head aid 553 Door Snubber—ends slamming and Guin fight flies 577 vacuum cleaner to paint car and oil springs 630 Electricity Automobiles—Tires—twin, decrease jars 555 power from a new kind of perpetual motion 554 Automobiles—Touring—washing cabinet contains first- power tapped from wire without stopping cars 577 aid kit ; 601 Electric Plug—with safety light to help prevent fires 636 [Continued on Page 4]

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[4] [Contents—Continued] Fire Fighting—rubber suits for dock firemen keep wearers afloat Floors—block, without nails, deaden sound Furnace—air moistener promotes health Gas, Poison—carrier on motorcycle is latest army unit Highway—super, proposed for autos to cross the nation Hoe—with adjustable head saves extra tools Household Devices House Plan Humidifier—air in homes is “‘washed” to guard health Incinerator—in form of tree improves looks of yard Keys, Automobile—case prevents rattling and loss Lathe—to true brake drums for servicing Light Waves—easily bent around ball Milk Can—cooler for, simplifies handling Mines and Mining—Edison’s miners’ safety lamp to prevent explosions Motorcycle—center rest aids flying start Moving Pictures—camera in phone box helps trap crooks Music Lessons—on multiple keyboard aided by lights Newsstand—portable, helps patrons catch cars Nuremberg Castle—magic beauty revealed by floodlights Police motor tricycle carries five men walking faults revealed by treadmill test Pump—three-way spout eliminates adjustments Radio headgear for airmen to aid communication headphones on loud-speaker lines * identification of aerial and ground connections neutralizing r.f. stages Radio—Aerial handy kink misused antenna insulation Radio—Applications—new tests for radio waves as dis- ease cure Radio—Broadcasting—tower on mountain reached by cable cars Radio—Eliminator build this compact B direct A-supply from charger Radio—Installation—better reproduction Radio—Loud Speaker dynamic, is operated from light socket novel unit Radio—Pictorial Radio—Receiver a Spanish-desk cabinet keeping the set dry modernizing old installations portable, is equipped with screen-grid tube Radio—Reception fading signals in a.c. sets razor blades make headphone diaphragms Radio—Repairing A. F. transformers safety insulation for screwdriver Radio—Television—new parts for experimenters Railroad—two-deck sleeping car has hotel comforts Razor, Safety—sharpener whets both edges Reflection—of sun and moon upon ice-crystal clouds Rifle—fired with one hand, wins British prize Roadster—electric, seats two and goes anywhere Roller Skate—quick clamp prevents accidents Safety Device and Measures escaping gas sounds alarm to prevent accidents fog lamp for traffic police Sand, Beach—screened for lost valuables Saws and Sawing—portable electric in kit carried like baggage Senses—tested by looking at world upside down Ships and Shipping illuminated flagship in fleet display stainless-steel propellers reduce shipping costs Shoes—wheel to assemble speeds production Siphon—automatic, also filters ; Smokers Accessories—cigar lighter without wire latest auto convenience Submarine—Uncle Sam’s biggest mine-laying Swimming portable camp bathing pool serves auto tourists rubber tube harness helps beginners Swing—fiying, like airplane adds to child’s sport Target Practice—bullets trace lines of fire to aid marks- men Taxicab—with radio to attract passengers Tear-Gas—club for policemen to help conquer crooks Telephone directory in outdoor booth serves public wires in plant form show cable structure 633 636 609 591 561 633 638 703 578 575 616 625 574 €41 586 575 555 619 587 601 608 618 630 587 663 664 664 662 663 560 568 649 660 653 651 651 659 654 662 660 653 661 661 664 663 652 569 633 599 632 640 553 545 637 640 641 562 629 634 577 593 551 586 600 599 641 576 Tires—gauge and deflator helps protect valves Tool, Metal Worker—three-in-one latest shop aid Traffic—danger bell traps autos running past lights Window Cleaning—safety brush to be used from the inside AMATEUR MECHANICS Advertising—novel window manikins from pipe cleaners children Automobiles—guard from meddling Automobiles—Repairing—anti-rattlers for hood clips Automobiles—Tires—trough for testing leak slowly Belt—expansion buckle Boats and Boating handholds facilitate carrying rowboat more speed from the outboard boat Bookplate—how to make a color stamp Boomerang—throwing is great sport Camping large, folding grate for campfire old auto chain holds pots over campfire salt and pepper shaker for the starter keeps Clothesline—preventing double from slipping on pulley Cockroach—sure-catch trap Corks—to remove from bottles Dents—removing from metal ware Door, Basement holder for simple base prevents sagging Fish and Fishing holder for the fishing rod loosening stiff fishing-rod joints two handy tools for the fisherman Flashlight—carried on boot House Numbers—made from old auto license plates Lantern—medieval easy to make Locks—for windows Motor, Automobile—governor for stationary Motor, Outboard—preventing loss of propeller Razor—using carborundum stone for sharpening Rings—cleaning large set Shoestring—splicing broken Sink—clean-out plug for drain Stirring Rod—heavy, for chemists Stove—substitute for broken oven-door spring Stumps—pulled with help of a keg Tennis—a solo game Tents—elastic stay ropes for Tools—porch cabinet for garden Trap—unusual for rats Trap, Bow—how to make Windows, Porch—hinging to avoid trouble Wire—unrolling, single-handed SHOP NOTES Angles—laying out accurately Automobiles—Repairing—device helps to reline brake bands Blueprints—holder prevents soiling Boats, Toy—your boy will like this liner Cabinet Work—attractive wooden trim for Clamp, Spring—for leather workers Corn, Seed—storage shed for Drilling—kinks for accurate Furniture—designing, to cover radiators Gauge—for duplicating diameters takes place of caliper Incubator—reading the thermometer Lathe—to turn a large pulley Linoleum—fitting snugly against raised concrete border Machine Parts—accurate measuring of keyways and grooves Milk Can rack for auto truck rack for draining Photography—holding small steel articles for photo- graphing Pipe, Brass—how to handle Reaming—with drill press Saws and Sawing handy pocket saw how to cut duplicate pieces on a bandsaw Steel—prevention of scale when hardening Tools—cementing tangs in handles Tractor—inexpensive, for light farm work Wall Studs—spotting Washers—counterboring those that 598 551 562 648 668 666 679 678 667 681 666 675 676 685 683 684: 670 685 694 691 696 699 701 700 696 695 699 695 701 689 702 695

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598 551 562 48 80 RE —— ae. a. 0 Popular Mechanic REGISTERED IN VU. S&S. PATENT FF € Magazine WRITTEN SO YOU CAN UNDERSTAND IT Jol. 50 OCTOBER, 1928 No. 4 = ] George K. Eastman, Left, and Thomas A. Edison at the Former’s Rochester Home When He Demonstrated before the Inventor of the Movies the New Amateur Color-Film Process we ES in color, produced by an inex- 1 pensive and practical process, the dream of producers for years, have arrived, but the infant of the movie industry, the amateur who makes his own pictures, will have the exclusive use of this invention. When George K. Eastman, of Kodak fame, demonstrated the new color-movie process recently in his Rochester home before Thomas A, Edison, Gen. John J. Pershing and a host of other eminent guests, he pointed out that it will be of no value for professional use, for it cannot be reproduced in a large number of prints, the original film being the only one. The colored movies are made without color in the film. Instead, a myriad ot microscopic lenses, molded of the film ma- terial itself, and a pair of color filters, one on the camera and one on the projector, produce color as an optical illusion. When the amateur movie process was developed in 1923, it was brought within reach of the average pocketbook by eliminating the ex- pense of printing a positive film for pro- jection from the negative made in the camera, Instead, the camera negative was, in the development process, reversed to form a positive. Because of this reversal of the original negative duplicate prints are impossible. A comparatively unknown member of the Eastman research staff, John G. Cap- staff, is given the major credit for develop- ing the new process, but insists on sharing the honors with Dr. C. E. Kenneth Mees, director of the Eastman laboratories. It was Mr. Capstaff who worked out the process for the original black and white amateur movie film five years ago. The color process was developed from an idea patented in France before the war, but never perfected. The Eastman company bought the rights, and since 1918 Mr. Cap- staff has been at work on it. On the side of the film which is exposed 529

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530 POPULAR MECHANICS different from the making of plain black- and-white movies. The film is developed in the usual way, and, to the eye, looks like an ordinary film, since it comes out in black and white and various of gray, with no hint of color. But when it is placed in the projector and a light passed through it, the embossed lenses re- verse the process and refocus their par- ticular rays to pass again through the proper sections of a color filter placed in front of the projector. Red of the orig- inal goes back through the red of the filter, and blue and green do the same. The effect of the rapid movement of the pictures completes the shades FILM BASE optical illusion, just as PER INCH SIDE VIEW OF LENS FRONT VIEW OF FILTERS = Dr. C. E. K. Mees, Head of the Eastman Laboratories, ing How a Filter and Embossed Film Make Colored Movies Possible to the light, millions of tiny lenses, hardly one-five-thousandth of an inch in depth, are embossed, placed so close together the On the opposite, the back side of the film, is the sensitive emulsion coating which re- cords the picture. they completely cover surface. In front of the lens of an ordinary amateur movie camera, a color filter is in- stalled. The filter is segments colored Slipping t into three and blue. he filter into place and loading divided red, green with the special film is all that is required to take colored movies. When the uncovered and the crank begins to turn, a third of the light entering the camera passes through each segment of the filter. One admits only red rays, one blue rays and one those that are green. The tiny embossed lenses focus parts of the light beams on their portion of the film. is lens The rest of the process is no 559 EMBOSSED LENSES HORIZONTAL SECTION EMBOSSED FILM the effect of movement in the film is itself an illu- when the eye tricked by the succession of images. Almost simultaneously with the Rochester dem- sion 1S BLUE-GREEN PURPLE > wire onstration, scientists of the Westinghouse eléc- my tric and manufacturing EMULSION) company, at East Pitts- || COATING " . 1] burgh, gave a public ex- hibition of radio movies. Developed in the space of only two months’ work, the radio-movie projector, which, in its workings is not essentially different from and a Diagram Show- television, thay, it was said, soon be ready for the market. While movie films have been transmitted by radio before, the Westinghouse dem- onstration was radically different in two prime factors. The first the use of scanner disks of sixty holes each drawing was sixty lines to the picture, and the second the use of a powerful mercury-vapor lamp for projection, instead of the red-tinted glow of a neon lamp. Within the space of little more than a vear, television apparatus has progressed from scanner disks of twenty-four lines to the inch, to more than thirty, then forty- eight, and now The addition of every few lines means more clarity in the received image. With sixty lines, the re- ceived picture is as clear as the average newspaper half-tone illustration, which has just about the same number of lines. sixty.

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POPULAR

MECHANICS 531

| Dr. Frank Conrad, Assistant Chief Engineer of the Westinghouse Company, Demonst ing the lio M Picture Projector; the Scanning Disk Is in the Center he successful use of a powerful pro- ansmitting movie t ection light, however, is even more im before the sca r each | rtant. All television processes hereto- the new scanner has six cl re have used the fluctuating beam of a_i picture, it means that 960 of t ttle holes eon lamp, operated directly by the re- in the scanner disk flasl p< the O ived current, to produce the necess ir ele ic cell each second | ( ) idations in color, which, in combination electric cell empl a rial th the revolving scanner disk, produced hich, because o : é é e the illusion of a picture. ess, is replacing the la ele The light output of a neon lamp of a um cells used in the 1 \ ug ze that could be operated by the fairly selenium cells have been us¢ r eak current available was necessarilve tally for some fift 1 ce ist low, and the picture could not be pro- beginning to develop the su ute jected in any size onto a screen With New cht o the ri ni yf p ure the Westinghouse discovery, the radio cut movie or still, w c ect vl 11 rent is used to control the mercury-vapor Mees told the American ¢ iety lamp just as it controls the valve of aradio that the science of photos ¢ on tube. As the received current varies in the fact that cows ¢€ ind othe strength the mercury lamp grows bright ylants which 1 1 u1 or dim. e cow’s ski ( The increase in the number of scanner e which ge to le e lines was made possible in turn by the resence of t een development of a more sensitive photo- found, is responsible the e l ac electric cell. The limit on the number of tion of the metallic silve e sensit lines per picture is always the ability of coating, which, instead of me- the cell to absorb the fleeting impressions. tallic silver should, appears under e mi- transform them into electrical impulse croscope like dark bits of coke he sen- send the impulses and prepare itself to sitiveness of high-speed film is credited repeat the process for the next line. In entirely to the action of these impuritie

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wn 32 POPULAR MECHANICS MOVIE NOISE “FACTORY” ADDS REALISM TO FILMS Inventor with Noise-Making Outfit Which Reproduces Scores of Different Sounds to Add Realism to the Films; Many of the Devices Are Operated by Electric Motors Scores of different sounds are accu- rately reproduced on an electrically oper- ated noise maker to be used with motion pictures. Small electric motors, controlled by push buttons, actuate most of the sound combined and altered distant units which can be to produce fading, and other ef- fects The entire outfit is con pactly con- structed ina single cabinet or table. about five feet high and less than two feet deep, intended to be The ass, trolley and is operated by the drummer. sound of falling tree crashing gl cars, doors slam- ming, few of the handsaw and acetylene torch are a that this unit noses unusual succe sfully imitates, How the sound of the trolley car was produced gives an idea inventor took in He first and then made of the elaborate care the constructing the apparatus. studied the noise carefully repeated experiments at duplication, finally ucceeding in the hum of the motor, the bell, air imitating the sway of trucks, the brakes and other parts. The wheels of six pairs of roller skates, numerous gears and : pulleys, two motors and compressed air vere finally arranged to make all the usual motion, and noises of an electric car in Jt a) i“ jyexwyvyvy,’ y in starting and stopping. Lights are ar- ranged to illuminate part of the machine when desired. ELECTRIC SEALING-WAX SET ELIMINATES FLAME Sealing packages and letters with wax has been simplified with an electrically that « bothet Op- unit liminates the use of a and Wax is mel a si iall crucible erated ome hand ted by an el "tlame other proc- +c } eSSES. ectric heat- ng element in and is ap- plied through a hollow shaft con- nected to the Wax container. The seal is at the base of this shaft. It is moistened with a sponge and then pressed upon the hot wax. The out- fit is especially use- ful in offices where ee a large number of articles is handled daily of such nature and value that they need to be sealed for shipment.

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above trenches, might put little harm. To puta city POPULAR MECHANICS CHEMICALS TO REPLACE GUNS IN WARS OF FUTURE \ thousand airplanes, ich carrying 5,000 —a sunds of chloroform, suld put the inhabitants cities as large as Chi- igo or New York to leep in a few moments, n time of war, according to Dr. Gustav Egloff, a esearch chemist, who oints out that scientists re developing means for iking war more hu- ane instead of more orrible. He suggests that anesthetics, far more ffective than are now own, may be intro- luced in the near future nd that applications of them from planes flying vhole batta ions o! sol- liers to peacetul slumber. hey could be awakened later and suffer relatively to sleep, the chemist de- clares, it would only be necessary to mix the air with anzsthetic amounting to no more than one per. cent by volume, and such doses could be so administered that the use of masks would be futile. WEED FATAL TO MOSQUITOES PUZZLES SCIENTISTS Man has a valuable ally in his warfare against the mosquito in a humble aquatic plant that grows in many parts of the United States. According to Cornell Uni- versity scientists, it not only prevents mos- quito “wigglers” from growing to ma- turity, but actually kills them. The spe- cific property that makes the plant deadly to the pests has not yet been discovered, and the plant itself is something of a mys terv. In some ways, it seems to be related to the seaweed family, but, in others, it stands alone in the plant family, a sort of botanical orphan. wn ww a On Its Way to the Launching; the Fuselage Factory in Berlin 4) of the Seaplane “‘Romar’’ Being Hauled from ‘ \ 2 ———____—_—— » of + be . ; . " i ‘ : | ee | Pes 0 a GIANT TRI-MOTOR SEAPLANE TRAVELS IN STREETS lo launch the huge seaplane “Romar” its fuselage was trundled from the factory through the streets of Berlin on a specia truck recently. The big plane has three motors of a combined capacity of 7 200 horsepower, it can carry more than 2,000 gallons of gasoline in the wiyg tanks and 1 other containers, and has a cruising radius » of 2,500 miles. SUGAR PREPARED FROM CORN MAKES “LEMONADE” Lemonade or orangeade can be made without the fruit by using a special sugar that absorbs the acids ot the e D1 xlucts chemists reported recently The sugar manufactured from corn by a process de- veloped for this particular purpose

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Jt w +e POPULAR MECHANICS “Roman” Riding on the Waves with Hobbyhorse Surfboards, a Popular Sport That Requires Skill in Balanc- ing, Especially When Changing Positions on the Way HOBBYHORSES AS AQUAPLANES TEST RIDERS’ SKILL Additional thrills are derived from the sport of aquaplaning with hobbyhorse boards. Each accommodates two riders or more and gives the passengers ample opportunity to test their skill at balancing while standing on the backs of the horses after the manner of Roman riding on real horses. A fast motor boat is used to tow the boards. CORROSION OF OIL-PIPE LINES LAID TO ELECTRICITY Corrosion of pipe lines that carry oil has perplexed scientists for some time, but bureau of standards investigators, after a number of tests, have announced that they are of the opinion the action is due to electricity. Running through soils where the ground is of different chemical com- position and of varying moisture content, the pipe is subjected to the results of a dis- charge and a collecting of electrical cur- rent at different points. The earth, in other words, becomes a sort of huge bat- tery of cells formed by the different soil sections. By measuring the electric cur- rent on several parts of an oil-pipe line, it was discovered that, at some points, elec- tricity was being collected and, at others, it was being discharged. The places of discharge corresponded, on the whole, with the places where the line was corroded. CRYSTAL BALL BURNS HOLES TO RECORD SUNSHINE One of the instruments used at the Brit ish air ministry to record weather condi tions, is a crystal ball that burns holes ina strip of cardboard as the sun_ shines through it. The board is marked off in hours and the ball acts as a burning glass, focusing the rays of the sun so that they record their shining in a parched path along the cardboard. J Part of Crystal Apparatus and Card That Has Been Scorched by the Sun’s Rays

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f h POPULAR MECHANICS 535 (MICROBE TO FIGHT CORN BORER AND SAVE CROPS Scientists in France are udying a malady some- hat like the silkworm sease which caused Pas- ur so much trouble but iso brought him fame. his sickness attacks the orn borer, and it is oped that, if ways can e found to spread it mong the pests, an effec- ve means will have been liscovered for checking he inroads of the de- structive insects. The ckness is believed to be aused by tiny single- elled animals which are parasites and are found in the internal igans of the borer larva. Another dis- ease that may be directed against the corn pest, spreads like an epidemic, destroying the digestive organs of the borer. HOPPER FOR RECEIVING CHANGE PROTECTS GLASS COUNTER To eliminate the inconvenience of picking up small change from the top of a glass counter, and to protect the cabi- net from breakage and stains, a hop- per cup has been introduced, Coins are placed in the top and the customer receives them by placing his hand under the hopper, rais- ing a square tube underneath a trifle, which allows the money to fall into his open hand. There is nothing about the unit to get out of order, and the base may be used for advertising legends. @ Those wishing further information on anything described in the editorial pages can obtain it by addressing Bureau of Information, Popular Mechanics Maga- zine, Chicago. Temporary Flume for Trans- porting the Cane, and View of a High One Spanning Ravine SUGAR CANE FLOATED TO CARS IN PORTABLE FLUMES Portable wooden flumes are employed on some of the sugar plantations in the Hawaiian islands to convey the cane from the fields to the cars in which it is shipped to the mills. These movable flumes, which are placed from 250 to 300 feet apart, carry a powerful current of water which is turned on after the cane has been piled into the trough. The ducts lead to the permanent or main flume which takes the cane to the central loading station. CHEMICAL EXPLODES IN WATER AND TAMES GAS Chemistry has given man another valu- able aid in a substance that is expected to prove of great service in war and in peace, a preparation which explodes with great force in water and also neutralizes poison gases of various kinds. Dr. C. R. Kokat nur, a consulting chemist, recently de scribed the compound as an organic per- oxide. In some forms, it will explode with terrific power in water—a valuable characteristic when it is considered that most of our present explosives are useless when damp. It can also be used to tame vapors such as mustard gas. A counter cloud of it. the chemist declared, might render destructive gases harmless,

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There Is No Authentic Record of a Have Been Destroyed and "RWO a rplar es crashed a few eeks ago, one 1n Ne W Jer eS al d one in Pennsylvania both, presumably, shat- tered by lightning. In the first Capt. Emilio Carranza, Mexican flving ace on a good-will vovave to T e U ited state died, and in the other perished Morris M litter ductor compass that guided ] ston, inventor of the earth-in- ndbergh to Paris, and a woman flying pupil. Six weeks earlier, lightning destroved three balloons in the national balloon race i few miles from the start at Pittsburgh. lwo of the balloonists were in tantly killed and a third terribly burned. Phe question immediately arose whether an unlooked for peril had cropped up to menace aerial navigation. That Capt. Carranza was a victim of lightning is in doubt, despite the first re ports to that effect \ tion of the indicated he careful examina scene probably had lost his direction in a terrific thunder- “ar co ss wa ey ww a = *lane in Flight Ever Being Struck by Lightning, Their Pilots Killed by Bolts a Though Many Balloons storm and flown blindly into the earth while under the impression that he was at a safe altitude. There were marks of his plane along the tree tops for 1,800 feet before the final crash. That a direct lightning bolt or by the wrecking Titterington was killed either by of his plane by lightning is also doubted by both flyers and lightning experts, fo in all the history of flying there is no I in the air. That the ever, is beyond question, and there are abundant cases of roved case of a bolt striking a plane while balloons were struck, how similar accidents o1 record for 200 years. What happens filled with inflammable hydrogen, is struck, was graphically told by Ward T. Van Orman, the Goodyear-Zeppelin international races when a balloon, pilot, winner of many national and whose bag was destroyed and whose aide, Walter Morton, was instantly killed msaewsreire«ewwsearwirtce

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“T was looking directly at the flash,” Van Orman said. “The thing that im- pressed me was its small- ness, hardly thicker than my finger, certainly not more than five-eighths or three-quarters of an inch. “It passed within two feet of my eyes. I had time after the flash to look up over the edge of the ‘rain dodger’ we had spread across the top of the basket and note that the bottom of the bag ap- parently was still intact. Probably it was two or three seconds after the flash before the concussion knocked me unconscious. “How high we were, I don’t know. A few moments before, in the terrific rain- storm, we had been blown down until we touched the ground, then bounded up again. It was a typical summer line squall, like the one that destroyed the ‘Shenandoah,’ with rising and descending air currents moving at high speed only a few feet apart. As we were blown down to the ground, we passed within 500 feet of Capt. E. W. W. Kepner’s army bag, go- ing up. We were so close, his aide, Lieut. W. O. Eareckson, shouted across to me. “It was only a few minutes later that we were struck, probably the army bal- loon was within a few hundred feet of us, though neither of them saw our bag burn. We might have been 300 feet up, or we might have been a thousand. “After I passed out, the bag burned and the basket, with Morton and me in it, fell to earth. It hit hard enough to burst the pontoons underneath, and cans of food among our stores were telescoped by the impact until they were an inch shorter than originally. The basket turned over on its side, and, still unconscious, I got a ‘ ” eae sf SN } The Bird in a Cage, Immune Because the Current Passes through the Metal, Suggests a Way of Safeguarding Balloonists bump on the back of the head that kept me out for three and a half hours “When I came to, my head was lying outside the basket, with rain falling on my face. I felt Morton beside me and tried to take his pulse, but could find no sign of life. Thinking he must be seriously in- jured, I jumped up to run for help, and discovered that my leg was broken and my back so badly injured I couldn't even crawl. I began to vell for help, and, for- tunately, i woke up just about that time, a farmer, living half a mile away, found his bedroom was getting stuffy, and, as the rain was nearly over, he got up to open the windows, heard my cries and came to the rescue.” Asa result of the disaster to the balloon race, the army, navy, weather bureau, sev eral universities and the Goodvear-Zepp« lin company have set to work to mak: lichtnit ballooning safe from The adaptation of an old laboratory stunt in solution, thev believe, lies in an which a canary in a metal cage is hung between the electrodes of a high-frequency machine and artificial lightning shot at it The metal of the cage conducts the elec tricity, and the bird is perfectly safe. A metal birdcage, built into the balloon basket, is to be tried in an effort to pro vide sufficient electrical capacity to save the pilots from shock. If the pilot can

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POPULAR St. Elmo’s Fire, Above Flaming from Lightning Conductors in an Alpine Village, end, at Richt, the Army “No 3” Leaving Pittsburgh Shortly Before Lieut. Paul Evert Was Killed by Lightning | be protected, the firing of the balloon bag is not a seriou matter, as the bal loonist can pull the rip cord, deflate the bag its vas, and let the bag parachute within it net to afely ot burning bring him down, that should fail, can leave the basket with his own parachute. When lightning hits a balloon it always picks one of the two oc- cupants as the target. Thus Mor- ton instantly killed while Van Orman escaped, and Lieut. Paul Evert, of Langley field, was In the third bag destroved in the Pittsburgh or, in Case Was killed and his aide escaped. race, James P. Cooper, aide of the “City of Cleveland,” was struck and_ badly burned, but survived, the only man in his- tory to live after being struck by lightning in a balloon. Eight balloon accidents have been due to lightning in recent years. In 1897, a 540 POPTTAR MECHANICS balloon, not in a race, was destroved and both occupants killed, one by lightning and the other in the fall. In 1923, when the international balloon race was held in Belgium three bags were destroyed in the air and that of Captain Honeywell, the American, on the ground. Five of the six in the bags destroyed met death, the sixth pulling the rip cord and parachuting the bag until he was low enough to jump into a swamp, breaking both legs. Two of the dead were Americans, Lieuts. Olmstead and Choptaw, in an army balloon. They were blown into another bag at the take-off, but managed to get clear, only be struck by lightning, Olmstead being in- stantly killed and Choptaw dying the fall. The following year, 1924, two more American bal- loonists were killed to in in a storm in IIli- nois. ‘J hey were Dr. C. LeRoy Meis am ~ | The World’s Tallest Lightning Rod, the Thousand- Foot-High Eiffel Tower in Paris, Photographed Just as It Was Struck in a Storm MECH ANTCS

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POPULAR MECHANICS A Variation of the Birdcage Theory Being Tested in a Los Angeles Laboratory as a Mea Storage Tanks from Being Fired by Lightning inger, a weather-bureau scientist, who had been making a study of thunderstorms by fiving through them, and Lieut. James T. Neeley, an army-balloon pilot from Scott field, Belleville. Dr. Meisinger was struck and killed by the bolt. Lieut. Neeley did not have his parachute tied to him, but grabbed the rope and jumped, attempting to hold the rope in his hands. When his body was found, the palms were badly burned from friction, showing he had been unable to keep his hold until he reached the ground. Curiously enough, the huge Zeppelins, with millions of cubic feet of hvdrogen compared with the few thousands in a free balloon, are immune to lightning. More than 100 of them have been struck, but a Zeppelin never has been destroyed in that way. The birdcage nature of their metal framework is responsible for their im- munity, it is believed. The great mass of the metal absorbs the shock. Part of the metal fuses under the intense heai, but the bolt passes out, leaving no serious dam- nek sa ns of Pr tecting Oil age behind. The only dirigible on record as being destroved by a bolt was one of the Italian semirigids, lich had only a metal keel, instead of a complete metal framework. There is no evidence, according to Van Orman and to lightning experts of the underwriters’ laboratories, that either a raction the path balloon or an airplane, has any att for lightning. If one is hit, it is just accident of fate that placed it in the bolt passing between two cl a cloud to the earth. A drifting the wind, doesn t even build its speed is virtually of a from before up a frictional static charge, and hence there is no triction hi shown by the absence of St. Elmo’s fire on balloon rigging. An airplane flying through a storm, on the other hand, is frequently covered with the ghostly radiance of the St. Elmo fire Under such conditions sparks four or five I inches be from metal parts by advancing the finger toward them long may drawn

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540 POPULAR MECHANICS Another Birdcage Installed over a Huge Oil Reservoir in California; the Network of Grounded Wires Absorbs the Charge and Carries It Safely Away from the Liquid One interesting possibility, which has been advanced to explain some of the airplane accidents in storms, is that the pilot re- ceived such a shock and was so surprised he lost control of his ship and went into a spin from which he could not recover. St. Elmo’s fire is often seen at sea, playing about the rigging. It resembles the pur- ple corona glow which can be produced bv a Tesla coil when the electrodes are too far apart for the energy to jump the gap. The problem of protecting balloons, and possibly airplanes, from lightning, opens a whole new field of research. Lightning protection on the ground is fairly easy, inasmuch as it providing conductors of sufficient size to carry the current down to the ground. But in the air, with no ground connection, the prob- lem is radically different. The success of the Zeppelins shows that, given metal of sufficient mass to absorb the shock, the airship is safe from destruction, but whether-enough metal can be added to a balloon basket without destroying the lift of the bag remains to be seen. only involves €s9 PDAONPTITT AR The group working on the problem is collecting the experiences of all the flyers who have met lightning in the clouds, to study its manifestations and its actions. One difficulty is the fact that the eve may frequently be fooled. Stories of the queer pranks of so-called “ball lightning” are fairly common. Observers have described balls of fire coming into their homes, roll- ing down the stairs, across the floors, and disappearing through the windows. A fa- mous ball-lightning story in the west is of a ball of fire that rolled along the backs of a tight-packed herd of cattle, until it finally fell off one cow’s tail, hit the ground, ex- ploded and killed a score of cattle. Actually, scientists now believe, bal' lightning does not and never did exist. It is merely an optical illusion. The eye has a habit of retaining bright images for some seconds. Look directiy into an in- tensively bright light, an are or one of the Kleig lamps used by the movies, then shut your eyes and turn your head away, and the image lingers in the eye for a period of several seconds, MECHANTCS

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POPULAR n the same way a person dazzled by a nding flash of lightning may shut his and turn his head but the ion persists and seems to be a ball of re rolling around the room, wherever the es are turned, until it gradually dims and nally vanishes, One of the most interesting experiments th lightning is now being conducted in he foothills of the Allegheny mountains ear Lake Wallenpaupack, Pa., where en- neers have been making experiments to es away, certain the effect of lightning on high- oltage trans- nission lines. fhe latest ichievement is photographic ecard ofa ightning troke. rhis picture, taken on a Fri- the t of its kind made in world, re- stroke trans- wires day nooh, fit ever the veals a on the mission of approxi- mately 2,500,000 volts. It made automat- Was ically by a high- speed camera which can re- cord what hap- pens in a mil- Photographing Electric Flashes with a Moving Cam- era; the Plate Separates the Discharges, Top Picture, into Many Separate Flashes MECHANICS hd nt el ft Min Vet : aay ee splash or ripple then « ture was made w: pectation of conti natural lightning, a great deal practical solution of | transmission systems @ Halibut weighing have been caught. lionth of a second a1 to below dangerous millionths of a second a total of forty-milliont] The mountain labo1 ues with the real of data will iy 1 mucha lionth of a sec- ond, or even a fraction of such a brief interval. The negative showed that be five-mil- lionths of a sec tore ond had passed, the voltage wave on the 220,000-volt line had climbed to more than 1,- 500.000 volts. A lecal disturb- ance, due to an induction flash- } over and reflec tion caused a 1 i (HP CMM) ration tft be required htnit Qo control on s 650 pounds

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542 POPULAR Ecce es OL BE & 1 MMe MECHANICS BOILERS SHAPED LIKE TOWERS DEVELOP HIGH PRESSURE Steam pressure of 3,375 pounds to the square inch is developed in a battery of boilers recently tested in Charlotten- burg, The plant involves several interesting features. In the first place, the boilers are shaped like slen- der, octagonal towers and the fuel, coal dust, is blown in the top together with a blast of preheated air. bustion takes place in the open space at the center of the boiler which is sur- rounded by the water tubes. An extremely high fire-box temperature Germany. at Com is Truck Equipped as Scoreboard and Radio Apparatus, to Announce Progress of the Games; Phonograph Music Also Is Furnished RADIO TRUCK SHOWS SCORES OF BASEBALL GAMES inter- ested in sports, welcome the appearance of an advertising truck equipped. with an efficient radio receiver on which the latest As inning, shown in squares on the exterior of the truck. Residents of a mid-western city, news of the baseball games is heard. scores are announced, inning by they are visibly The traveling news also has a phonograph with am- station as plifying = produced in this manner and steam raised to ovet 3,000 pounds to the square inch and to a temperature of 450 degree; Centigrade. The amount of ash produced is small and falls out at the bottom, while the combustion gases are turned back to warm up the preheater for the air blast. So completely is the heat consumed that the outside of the towerlike boilers is said to be but little warmer than the air. SUPPORT FOR ROD IN TROLLING HELPS HOOK FISH apparatus ponrenemnceeini to entertain listen- ers with music when there is a lull in the game reports. BLACK SHEETS INDUCE SLEEP using black and pillow instead of Italiar reports By sheets Cases white, physician good results in per- suading unruly in- sane patients to go to sleep. The doc- tor declares that the plan effective with sane persons an is im insomnia cases. Wuwersrwyyvwyyr y A Pole Hoider That Helps Hook the Fish vs Clamped to the seat of the boat with thumbscrews, OE a a steel for the fishing support rod is said to be of special aid when trolling for game fish be- cause of the posi tion in which it keeps the rod. It holds the pole rigid, so that when the fish strikes, the rod springs back, help- ing to set the hook. The holder may also be used when stillfishing from the boat, although not primarily made for that purpose. FrFMur Peak ¢ = we we Fe

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POPULAR MECHANICS 543 HOW TO UNMIX OIL AND WATER BAFFLES CHEMISTS Oil and water do not mix as a chemical ompound but mingle as an emulsion, that with extremely fine drops of one sus- pended in the other, and how the two can be separated without troublesome and ostly processes is something that oil pro- ducers and chemists would like to know. \ccording to Dr. Gustav Egloff, there are more than 100,000,000 barrels of this emul- ified crude eil in storage tanks and sump oles in the ground, and refiners are seek- ng a cheap way of separating the oil from the water, as the emulsified product rep- resents many millions of dollars of poten- tial value. One of the chief aims of the refiners is to produce lubricating oils that will not emulsify in motors and turbines under service conditions. DESK AND TABLE COMBINED TO ENCOURAGE STUDY Equipped with a removable drawing board, charts and other appliances, a com- bination child’s desk and table is adjust- able to different heights as is the seat that comes with it. On one side of the board, is a slate which takes colors for sketching or painting, and the desk part may be taken off so that the table can be used separately, if desired. The charts are on scrolls that can be quickly changed. Child’s Desk That Folds into a Table and Has a Re- movable Drawing Board Setting a Pole After the Hole Is Dug; the Endless- Tread Tractor Is Fitted for Rough Travel HOLE BORER AND POLE SETTER AIDS POWER LINE WORK Constructed for duty in rough country, a combination unit for boring holes and setting power and telephone-line poles, has been introduced. It is run on an end- less-tread drive so that it can climb hills, traverse ditches and surmount other ob- stacles, and is equipped with an efficient auger for boring the hole in any kind of soil as well as at angles and also has a derrick arrangement for hoisting the pole and lowering it into the hole. It can han dle poles forty-five feet long, and may also be used for dragging them from the sup ply pile to the place where they are to be set. In digging, the dirt is piled at the side of the hole for convenient refilling. SOAP FROM WASTE FRUIT Avocados, not up to market standard, contain oil that can be successfully util ized in the manufacture of hard soap, chemists of the department of agriculture have discovered. Tests have shown that the oil does not become rancid even after a year’s storage under ordinary conditions.

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544 POPULAR ELEVATOR ON HOME STAIRWAY AIDS INFIRM PERSONS , Elevator in Use, and As It Appears When Folded against the Wall at Bottom of Stairs For installation on the stairway of a private home, an electrically operated ele- vator has been introduced. The occupant sits in a comfortable chair or seat and controls the lift with switch buttons on the car and at the top and bottom of the stairs. The carrier runs on a roller track alongside the stairs. When not in use, the platform and seats fold up against the wall so that they take up but little space and do not interfere with the ordi- nary use of the stairway. BUFFALO HUNT CENTURIES AGO SHEDS NEW LIGHT ON MAN Interesting evidence on the question as, to when man first appeared in North America, has been discovered near Fol- som, N. Mex., in stone arrowheads lying close to the bones of bison of a kind sup- posed to have been extinct long before the white man arrived on this continent. If the arrows were shot at the living game, as the evidence indicates, the conclusion of some scientists is that the hunters must have been there at least 25,00) years ago, possibly even several hundred thousand years. The bison bones were fossilized and there have been no discoveries to MECHANICS show that animals of this variety have ex- Addi- tionai clues as to the age of the bones and of the weapons are the depth and forma- tion of the earth in which they were found, The excavations were conducted by the Colorado and the American museums of natural history. isted in America in recent times. NON-ELECTRIC DAYLIGHT SIGN SHOWS BRILLIANT LETTERS Davlight is used as a substitute for elec- tricity in an advertising sign recently mar- keted. It is of simple construction, con- sisting of but three parts, a special glass on which the legend is painted, a reflecting mirror and the inclosing box. The glass forms the top and is so made that its grained or pebbled surface functions as thousands of minute prisms which focus and intensify the light that shines through the glass. Letters in the sign are formed by blocking out the space around them with opaque paint, leaving the characters clear. They are projected through the open front of the box by means of a mir ror set at an angle of forty-five degrees. By using stained glass, signs may be made in any color or combination of colors. The letters have no halo of light around them as often occurs in electric signs, so that they can be identified at great dis tances, there is no operating cost and practically no upkeep expense and the sign is simple to install. It is adapted es pecially for automobiles and trucks, store fronts, windows and road signs. Experi ments are being made in illuminating the prismatic glass in order to achieve the same brilliant display effects after dark. Drawing of the Lightless Sign, Showing How Letters Are Reflected by Mirror through Prism Glass @ Five feet, five inches is the average height of human beings. | |

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POPULAR MECHANICS 545 Catapult on Steamer “Ile de France” to Launch Planes; the Biplane Shown Here Was Superimposed on a Photograph of the Vessel PLANES FLY FROM OCEAN LINER WITH AID OF CATAPULT Flying service from the “Ile de France” to the shoré is expected with the installa- tion of a catapult to launch the planes from the liner’s deck. The apparatus is similar to that used on battleships and will. make possible quicker landings of passengers, mail and other “rush” cargoes. ESCAPING GAS SOUNDS ALARM TO PREVENT ACCIDENTS Gas is made to sound its own warning, should it escape from the mains, in an alarm device demonstrated by an eastern inventor. It is so sensitive that it will re- spond when the air space in a room con- tains as little as one one-hundredth part of gas, the inventor declares. In a recent test, an open bag of illuminating gas was held near the alarm, a boxlike contrivance, and in a few seconds, an electric bell con- nected to the box, rang the warning. The signal is applicable to various home and industrial uses, and could also be emploved to detect the presence of war gases, it is claimed. As a guard against explosions, it has been adapted to use in gas plants, CIGAR LIGHTER WITHOUT WIRE LATEST AUTO CONVENIENCE One of the chief features of a cigar lighter, especially adapted for use in an automobile, is that the heater itself may be re- moved from its socket and passed around in the car eliminati bother of cords iti 4 clamp-on bracket for the base, simplifies instal lation, and there are cords for connection from the battery circuit to the lighter.

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ARLY in June an old-time windjam- mer set sail from the coast of Connec- ticut carrying beginners in the art of sea- E; manship. The boys aboard came from all parts of the United States—from farm, office and shop. To many of them the voyage brought the first taste of the sea. Three months later, the young landsmen went ashore at New London versed in the language of salt water and well grounded in the science of navigation. They were landsmen no more. Ninety days of brisk training had transformed them into sailors. The cruise is a part of the plan for training men officers the United States coast guard, that arm of the gov- ernment which maintains the life-saving service on stormy coasts and treacherous waterways. Their craft is the “Alexander Hamilton,” practice ship of the coast- guard academy, with a colorful record in the navy as the gunboat “Vicksburg.” In her new life, the vessel bears the name of the father of the coast guard—Alexander ot as 546 “140 msmarwwnmnvwerf+ery aa vy Hamilton, first secretary of the treasury and the man whose formal recommenda- tion resulted in the creation of the organ- ization which was the foundation of the present service. The coast-guard academy, at New Lon don, has kinship with West Point and Annapolis as a training school for the of- ficers of the future. Members of the cadet corps are selected youths, appointed for their seeming fitness. They receive pay and allowances similar to those granted West Pointers and navy midshipmen. Graduation is followed by appointment to the rank of ensign, as in the case of the man who graduates at Annapolis. From this commissioned grade the promotions’ follow the course prevailing in the navy, with the post of admiral as the ultimate possible goal. The academy itself the center of training and educational activities, but the real romance of the work belongs to the sea, aboard the barkentine practice 1S arvrworeerewyrwypraé't'‘Twrwse£#rtey

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ship, a three-master of a thousand tons. In this craft, the cadets have a seagoing college, 168 feet long, thirty-six feet wide, and drawing twelve feet of water. In her early days as the “Vicksburg,” the vessel formed a part of the blockading squad- ron off the harbor of Havana, during the Spanish-American war. Later, she car- ried Brigadier General Frederick Fun- ston in the Philippines, for the capture of the rebel chief Aguinaldo, returning to Manila with the leader and his fellow- prisoners on board. The period of the uropean war found the vessel in active patrol duty on the Pacific coast. When the youth from the farm or shop enters the coast-guard academy, his first contact with the sea comes with the prac- tice cruise of the “Alexander Hamilton.” The voyage may take him and his com- rades to various European and north African ports, affording a touch of travel combined with a course of elementary training in seamanship. On this cruise, the green hand is taught to be a sailor in the real sense of the word, for the coast- guard policy is that no man belongs in the life-saving service until he is a full-fledged seaman, capable of doing everything that may be required of a sailor, and doing it in approved fashion. This sea training carries the full flavor of the days when commerce was borne on sailing ships. From the beginning of his ae “uh liye tiene course, the cadet is surrounded by the ro- mance of the sea. He studies salt water as the collegian studies books. His cam pus is the broad Atlantic, his schoolroom a “Nautilus” of a past generation. When the “Alexander Hamilton” puts out to sea, the new cadet goes through a course of training which gives him a true taste of the thing for which he entered the academy—the life of the ocean. Start ing with such simple tasks as splicing knots and handling lines, he is taught to manipulate sails, man the small boats and carry on the general work of a sailor, in- cluding the care and upkeep of a ship at sea. That he escapes deck scrubbing is due to the custom of leaving this task to the crew while the student learns jobs of greater importance Growing familiarity with the workings of the ship brings the newcomer’s introduction to the of taking sights, mysteries the sun and stars for calculating the vessel's position, figuring out 1 “shooting” the position by means oft dead reckoning, and similar fundamentals of navigation. like- wise to train the cadet in the work of the This introductory cruise serves ship’s lookout—the man who stands for- ward and reports “sail to starboard,” “whale off the port bow,” or “smoke dead ahead.” Another bit of con- nected with his future work as a life-saver is afforded by frequent turns at the “life schooling

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buoy watch,” during which the cadet stands by the buoys for prompt action in case of “man overboard” or similar emergency. He receives, too, a course of training at the wheel, with a second-year student in- structing him in the proper handling of the steering apparatus. The practice cruise affords practical appli- cation in the theoretical : subjects taught in the academy. Added value arises from the opportunity given the officers aboard the ship to observe and study the individual inclinations of the cadets when they are away from their ac- customed land environment, to note their fitness for a seagoing occupation, and to instill into them the traditions and stand- ards of the coast-guard service. After the first summer’s cruise, there comes a winter’s study at New London, during which the cadet is introduced in the theory of navigation in its scientific aspects The following summer brings a second cruise, giving a chance to apply the theory acquired in the winter studies at o—_- -—- cawes = POPULAR MECHANICS the academy. In this cruise, the student may become a coxswain, or he may attain the post of captain of a gun’s crew. Either position affords a lesson in giving orders to the new crop of first-year men undet him. Experience has shown that the worl of the second summer does much to per fect the cadet’s knowledge of navigatio: and to fit him for the post of cadet office: of the deck, achieved a year later, during his third cruise on the school ship “Alex ander Hamilton.” The duties of the cadet officer of th: deck tend to transform the student into a real navigator and captain of men. Un der the watchful eye of a commissione: the cadet take responsibility for han dling the ship at sea ancl in port, getting unde: way, dropping and rais ing the anchor, docking and undocking, and do ing the various things that are supposed to be done by one of the mates. In this work the commissioned office: leaves the cadet office: officer, A Breeches-Buoy Rescue from “Swan”; Life-Line Firing Practice, and a Cutter Tow- ing a Disabled Steamer in Bering Sea the Mine Sweeper eee ee ee

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nt lin ler ars ler rk POPULAR MECHANICS 549 The Coast-Guard Training Ship “Alexander Hamilton,’ the Handling of the Fast Disappearing Type of Sailing Cutter to his own devices and does not interfere with his activities, except in cases of emer- gency where more seasoned skill is de- manded. By the end of this cruise, the successful cadet is a qualified navigator. The academy gives a comprehensive course of studies which is intended to produce well-rounded men for the com- missioned personnel of the coast guard. As the oldest armed force for the protec- tion of the American seacoast—antedat- ing the navy—the service has built for it- self a tradition covering 138 years of achievement. No branch of the national defense takes greater pride in living up to its traditional reputation for gallantry in action and for readiness to serve. The guard’s sphere of usefulness is both civil and military, with the primary object of saving life and property, but with addi- tional duties covering the various mari- time functions of the federal government. Because of its wide range of activity, the coast guard requires. officers of su- perior type—men who are capable of in Which the Recruits Are Taught Seamanship and meeting situations of diversified character. For aiding vessels in distress and effect- ing rescues at sea, there is need for hero- ism of the highest type and the ability to lead men in the face of the utmost peril. The destruction or removal of wrecks, derelicts and other floating menaces to navigation calls for resourcefulness of an- other sort, requiring judgment and skill of more than ordinary character. Still other forms of ability and training are demanded in the ticklish work of pro- tecting the government against custom smugglers and rum-running enterprises In these undertakings, the coast guard acts as an armed force which must be ready to compel respect through the use of three-inch guns whenever there is occasion for such drastic treatment of a situation. Further duties involve the enforcement of navigation laws and quarantine regu- lations, the suppression of mutinies on l and other fisheries in Alaskan waters, and the merchant ships, the protection of sea

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wn ur =~ _— POPULAR MECHANICS — $$$. $$$ All Night Long, the Coast Guards Patrol. Their Beats, and When a Wreck Is Sighted, a Rocket Summons the Entire Crew with Surfboat, Breeches Buoys and Lyle Gun to Aid in the Rescue summer patrol of the iceberg regions off the Grand Banks of Newfoundland. Added to these responsibilities is the task of po- licing regattas and marine parades in the interest of public safety. With this varied program of routine work, and with the additional prospect of serving as a part of the navy in time of war, the coast guard stands forth as a versatile service requiring the highest type of commissioned officers. The training afforded by the academy and the practice ship is of a nature designed to produce the desired material, The cadet who mas- ters the course acquires academic educa- tion as well as seamanship. His courses have embraced English and French, math- ematics and such studies as mechanics and chemistry, gunnery and physics. He has studied the science of ballistics, deal- ing with the travel and force of projec- tiles, their pathways and their impacts. He has been schooled in drill regulations, service regulations, the custom laws of the United States and the general aspects of international law as pertaining to the seas. ._In short, his preparation for the coast guard has qualified him to appear to good advantage wherever he may be thrown, and to uphold the traditions of the guard. The full course occupies three years. Its satisfactory completion marks the be- ginning of the graduate’s work in the gen- eral organization of which he has become a full-fledged part. Life on the “Alexander Hamilton” pos- sesses the lure of the sea in its fullest as- pects. In the whole realm of American shipping, there is no better place for ab- sorbing the traditions of salt water or ob- taining the thrill that comes with a favor- ing wind and full sail ahead. GRASS PUSHING BACK THE SEA TO AID FARMERS Acres of land which is covered by the tide twice daily, are gradually being won from the sea and turned soil for farming, by valuable means of a special It is a rushlike variety and about its fine roots and Inch by inch, it builds up into kind of grass. collects mud slender stalks. the shore level.

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POPULAR MECHANICS 551 RIVETLESS BOAT CUTS PATH THROUGH ICE FIELD That the cutter “Northland,” the suc- cessor to the veteran coast-guard boat “Bear,” is well constructed for its duties n the north was shown by its recent vic- tory over an ice field off Point Barrow. It came through unscathed after ripping and plowing its way through ice six inches thick. The test was considered a point for the special type of construction of the vessel. There are no rivets in the hull, the body being electrically welded throughout. Some engineers predicted that this form of hull would not stand the strain of the ice but would buckle. No uch trouble occurred. On the other hand, the “Bear” once suffered a couple of cracked timbers while breaking through ice but three inches thick. THREE-IN-ONE METAL WORKER LATEST SHOP AID For general use in a sheet-metal shop, a bench machine with interchangeable faces has been introduced, It may be employed in wiring, turning or burring, the different faces being easily removed and attached to the shafts. Adjustments are made for material of different thicknesses and the gears are completely inclosed for longer life and added safety. Metal-Working Unit and Three of Its Operations; Note the Inclosed Gears Airplane Thrill Is Pro- vided for the Youngster in This Flying Swing FLYING SWING LIKE AIRPLANE ADDS TO CHILD’S SPORT Shaped like an airplane with a spinning propeller at the front, a child’s swing now on the market holds three youngsters at a time and is suspended at four points so that it cannot tip. The wings are of wood, the body is four feet long and there is room for a passenger in front and behind the pilot’s seat. The swing can be set up in a few moments and is suitable for out- door or indoor use. STAINLESS-STEEL PROPELLERS REDUCE SHIPPING COSTS Stainless-steel propellers have been at- tached to four ferryboats operating in San Francisco bay, and their use is ex- pected to effect a saving of at least $25,000 a year by eliminating some of the drydock intervals necessary with the usual equip- ment for repairs and renewals. A further economy is promised in a reduction of fuel consumption, as the propellers are more efficient than the usual kind. The blades do not deteriorate so rapidly and can be re-pressed into shape more easily than those of cast steel.

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POPULAR MECHANICS construction. They work in heat comparable with that of a Turkish bath, as they are surrounded by big steam pipes. The main problem involved is to extend the present foundations to a point below the level of the floor of the subway. The supports for the foundations are steel cy] inders in sections, vary- new Lighted Letters on the Plane Wings Are Visible from Great Distance and Are Interchangeable FLYING BILLBOARD HAS LIGHTS UNDERNEATH WINGS Effective use of airplanes for night ad- vertising is seen as a possibility in an ex- periment in Berlin, where a huge three- motored ship was fitted with lighted letters yn the under surface of its wings which { had a spread of ninety-five feet. The letters could be interchanged automati- cally to enable the display of more than one The sign could be read when the plane was more than a mile high. message, BURROW UNDER SKYSCRAPERS WHILE DIGGING SUBWAYS While millions of persons walk about in the heart of New York’s financial district, a crew of men toils far below the surface, bolstering up the foundations of the huge buildings while the new subway is under ing in diameter from twelve to sixteen inches, and in thicknes from one-eighth to three-eighths of an inch. In placing these sections, a small pit is dug under the column to be supported and a hydraulic jack set in position be- neath. The cylinder is then pressed down by the jack, since the building column can- not be raised. When the jack has been ex- tended to the limit, pressure is released, and another section of cylinder placed on top of the first and forced down until the bottom unit reaches such hard ground that it will go no farther. To hold up some of the columns, more than twenty steel piles will have to be forced down. CULTIVATOR SAWS THE SOIL FOR BETTER PLANTING Applying the principle of sawing to the soil, an Indiana man has devised an im- plement that plows, disks, harrows and rolls the ground, all in one operation. Large revolving blades with sawlike teeth are said to cut into the ground to a depth of ten inches, pulverizing it and, at the same time, destroying weeds and rodents. Cultivator with Whirling Saw- Tooth Blades That Cut the Soil and Destroy Weeds

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POPULAR MECHANICS 553 STEEL PILOT GUIDES PLANE WITHOUT HUMAN HELP \ “steel pilot’ which operates an air- ine without human help, was tested suc- ‘ssfully recently at-Istres, the great mili- ry airport near Marseilles, France, by rench army flyers. The mechanical pilot, vented by Major Max Bouchard, weighs ly sixty-seven pounds, and it is claimed r it that it is far more effective than human pilot, and makes it impossible to et a plane into such a position that flying eed is lost, the trouble that usually pre- edes a tailspin. Flying blind, in fog or ther conditions that make it impossible ir the pilot to see some object by which e can fix his position, is the cause of any tailspin accidents. Unable to orien- ite himself by a glimpse of ground or sky, the pilot loses all sense of direction, unless e watches his instruments carefully and obeys them rather than his own sensa- tions. The steel pilot consists of electric motors which operate the longitudinal and lateral controls and also steer the ship. SLAMMING DOOR IS SILENCED BY RUBBER CUSHION DOOR JAMB, Mounted in the a / face of the door frame, a small | rubber buffer ef- he ly fectually silences a iy ’ the slamming door. Projecting rubber tips absorb the shock. The EZ cushion is easily soon / attached, a small EA brass frame giv- ing it a secure foundation, RECESS ~_ WHEN GEESE WEAR SHOES Geese are often driven long distances to market in central and southeastern Europe and, to protect their feet on hard roads, they are given curious “shoes” of tar and sand. They are first made to walk over an area that has been coated with the tar and when their feet are thoroughly smeared, they tread over sand. These shoes wear well, even for severai days. Changing Tire with Aid of Electric Lamps That Are Worn on Headband for Better Vision TROUBLE LIGHTS WORN ON HEAD AID IN FIXING AUTO Connected to the automobile batteries and worn on a band about the head, two efficient electric lamps direct their rays where most needed when repairing the car, are not in the way and need no extra adjustment after once put on. The head band is comfortable and secure, both hands are left free for use, and each light can be turned so that the rays may be thrown in any direction desired. QUICK CLAMP ROLLER SKATE PREVENTS ACCIDENTS Roller skates that can be put on in less than two seconds, the manufacturers state, have an adjustable clamp with a lock- ing device that fits into a slot on the heel. Once fas- tened, this catch cannot come loose accidentally. For stage work, the skate is especially desirable, as it is light and com- fortable and may be put on in the wings, saving the risk of walking from the dressing room while wearing the rollers.

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wn oa + POPULAR MECHANICS POWER FROM A NEW KIND OF PERPETUAL MOTION

oy < 7 i a Pt m7 hg ey rae, sie Ae: a As Pig Ft x. be 5 %

The Nearest Approach to Perpetual Motion Is This Hydroelectric Plant That Generates Current to Pump Water up a Hill, So It May Flow Down and Generate More Electricity Generating electricity from water power, and using the current to pump the water back up the hill and let it run down again to generate more electricity looks like an attempt at perpetual motion, but is actu- ally being done with success at the Rocky River plant of the Connecticut light and power company on the Housatonic river. As losses from friction, plant inefficiency and other causes make it impossible to pump as much water as was used to gen- erate the current consumed to do the pumping, the arrangement does not ap- pear profitable, at first glance, but actu- The answer is that the river is on the job twenty-four hours a day, gen- erating current, without regard to noon hours, Saturday afternoons, Sundays, holi- days and night time, when the demand for electricity drops as the factory load is shut off. The water flows whether or not cur- ally it is. rent is required, and once it passes over the dam cannot be recalled. So the engi- neers did the next best thing and arranged to utilize the power that otherwise would be wasted. Two motor-driven centrifugal pumps, each with a capacity of 112,500 callons a minute, elevate the water 230

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” a Si POPULAR MECHANICS 555 et up the hillside back of the power suse and pour it into a reservoir in the ext valley. Then, when a peak load mes and more generator capacity is eeded, the water runs back down the me pipe and turns the turbine wheels, isses on into the river, and flows down } operate other power houses farther wn the stream. Another advantage of e scheme lies in the fact that the stor- se reservoir in the next valley has a ca- icity of 45,000,000,000 gallons, but the atural drainage into its basin supplies nly about one-quarter of that amount, eaving space for the pumps to fill. TWIN TIRE ON AUTO WHEEL DECREASES JARS A new type of wheel having two tires, one within the other, and said to be adapt- able either to motor or trolley cars was exhibited recently. The outer tire is of solid rubber, the other, inside it, is pneu- matic and is incased in a steel frame next to the hub. This arrangement is said to take the strain from the outer tire while the inner one acts as a shock absorber. Punctures are also eliminated. BOAT IS INFLATED LIKE TIRE AND FITS IN KNAPSACK Designed especially for camping trips, a rowboat, exhibited in Germany recently, can be folded into a knapsack and, when ready for use, is blown up like a tire. In addition, it has a waterproof covering that fits over the top as a tent to protect the occupant from inclement weather. “Tire” Boat in Use; It Is of Fabric That Can Be Folded into Small Bundle When Deflated Automatic Telephone Box That Conceals a Motion-Pic- ture Camera for Trapping Criminals MOVIE CAMERA IN PHONE BOX HELPS TRAP CROOKS Inclosed in an automatic-telephone box, a motion-picture camera devised by a western inventor, takes pictures of per- sons without their knowledge. It is in- tended to be of aid in trapping bank rob- bers and others. The camera carries six- teen feet of film, is operated automatically and, in tests, has taken pictures of persons eighty-five feet from the instrument, NEW PAPER MONEY TO BE AGED TO PROLONG WEAR The life of paper bank notes is about eight months but this might be increased to a year, treasury officials declare, if the paper were aged properly before being circulated. The process delays cracking and tearing. Between 1917 and 1920, the calls for currency were so heavy that the bureau of printing and engraving was un- able to keep the pace and new money was issued without the usual aging period. The new notes, which are to be about two- thirds the size of the present ones, are to be thoroughly aged before being issued, the treasury department reports. They will resemble those in use in the Philippines.

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A Wild Elephant Charging through the Main Entrance to the Keedah, or Stockade, Used to Trap the Jungle } Herds in the Round-Ups in Mysore State, India; the Guards on the Second Gate Are Armed to Check Any Attempted Stampede, and the Fence Is Protected by a Deep Ditch 7 gcaQ WAI DIYTyT a ww t1rwoesomyrmTrae't’ Trea

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Seer ows ethiae ike ‘ 4 ies se " * PTT is ¢ , Cee ta cat arta , 7. », ok wet The Tame Squad Waiting for the Signal to Enter the Stockade and Start Cutting Out the Wild Animals, One by One, So They Can Be Hobbled and Chained to Trees By CAPTAIN J. P. WILLIAMS f Peeertecantes wild Indian elephants, to be domesticated for circuses and parks throughout the world, or put to work pil- ing teak and doing other heavy work at home, is a regularly organized business in the native state of Mysore. A vast wild-elephant preserve, a hun- dred miles from the state capital, has been set aside to raise the tuskers. At least once a year a jungle round-up, carried out in many ways like a cattle round-up on a ranch in the western United States, brings of the animals, with their and calves, into the fold. Pleasure is usu- ally combined with the business, and the round-up becomes a gala celebration in honor of distinguished guests. scores COWS Weeks of preparation are necessary be- fore the actual elephant drive starts. An enormous stockade, built of logs driven into the ground and chained together, is erected in a jungle clearing. Inside the fence a deep ditch, carefully revetted with Dry DIrryr ay? AXA TL sharpened poles, is dug around the clear ing, except in front of the The ditch discourages an organized attempt to which probably gates. uproot the fence, would crash if an entire herd could run into it. From the stockade, a long and broad avenue is cleared through the jungle, the undergrowth being piled along the edge to encourage the elephants to keep to the open path. Four to hundred native of the district usually sted a beaters, and a herd of tame work dames is brought from My road Six are enl down sore city in specially constructed rail cars, eacl built to hold one animal. When the appointed day for the round he beaters, distributed start their firing up arrives, t around miles of territory, work, beat and fire po jungle ing drums and pans, works, sible. begin to mill about, er there 1s guns and making as much noise as The startled elephants in the until they find in one quart no noise, so they head in s ABIES n yi =)

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558 POPULAR MECHANICS some are stubborn and lie down and re- fuse to move, while others quickly accept the new order of things and yield. For several days the captives are kept chained to trees. Then they are yoked one by one to tame elephants and led down to water, and permitted to take a dust or mud bath. The same training goes o; day after day until they become sufficient], broken to be worked alone. It usually takes a month or so to tame them suffi ciently to be yoked to work animals, and several weeks more before they are suffi ciently domes ticated to he worked alone. Then comes the annual ele phant auction, attended by ele phant buyer from all over 2 India, as well as zoo and circu that direction. The gathering herd eventually tumbles on the cleared road- way and takes to it, as offering an easier ave- nue of escape than the track- less forest. ™™ , | agents from foreign land The best of the work animals ! t MI go to the lum bering opera- tions, where they are able to carry enor- mous logs with their tusks. Down the roadway the herd stampedes until they reach the stockade gate and pass through it. The watchers, hid- den in near-by trees, release the catch and the gate falls, barring escape of the herd. The tame elephants are then brought up and picketed near by, waiting until the captured wild animals get over their first fright. As they calm down, the gate is opened and a troop of wily old tuskers, able to fight if need be,.and trained for the work, march in and surround the nearest animal, forcing him out away from his mates. Once outside, he is shoved and pushed around until he reaches a picket tree, when natives attach hobbles and chains and tie him up to get used to cap- tivitv. One by one the entire wild herd Going to the Round-Up by Bullock Cart; Half-Tamed x , Young Elephants in the Stockade, and a Wild One is treated in the same manner. Some fight, Being Led to Water =/f.ft mrrwmsFrYy swt maeweinowwraaTrTwesr

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les r POPULAR MECHANICS 559 The Arrival of a Wily Old Tusker at the Round-Up Scene; the Tame Herd Is Transported a Hundred Miles by Specially Built Railroad Cars, Each De- signed to Carry One Elephant, and Equipped with Special Shackles to Pre- vent an Accident if the Occupant Be- comes Frightened during the Journey; Below, the Pit That Guards the Stock- ade against Attack by the Wild Herd; the Deep Ditch Is Revetted with Sticks to Further Discourage Any Attempt at Rushing the Wall

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560 POPULAR Water Tank in Form of Pineapple at Canning Plant in Honolulu TANK IN FORM OF PINEAPPLE ADVERTISES PRODUCT Water for the sprinkler system in a can- ning plant at Honolulu is contained in a huge tank, shaped like a pineapple to ad- vertise the company’s product. The tank holds 100,000 gallons, is sixty-four feet high and is mounted on a steel tower, 135 feet tall, so that it can be seen from almost any part of the city. Painted sheet-metal strips were used to form the crest of the “pineapple,” which weighs fifty-five tons. PUTTING MOLD TO WORK Mold, a form of plant growth which spoils bread and other foods, is being put to constructive work. It long has been employed in the making of cheese and now scientists have found use for it in produc- ing citric acid, formerly derived chiefly from lemons and other sour fruits, and to reduce the cost of another useful sub stance, gluconic acid. This formerly cost $100 a pound. With the aid of mold, it can now be made for some thirty cents a pound. In the opinion of H. T. Herrick, of the department of agriculture, chem- istry is just beginning to realize the possi- bilities of this queer fungus growth. It MECHANICS may be harnessed to perform many othe useful tasks, he believes, when the righ kinds of food are supplied for it and more is known about its functions. MAGIC LANTERNS IN SUBWAYS ENTERTAIN PASSENGERS Patrons of a Paris subway line are en- joying picture shows as the trains speed through the tubes. Four magic lanterns have been installed in each car, two o1 each ‘side, and the views are projected on the dark walls of the subway. Advertise ments, pictures of celebrities and other features are shown. The lanterns operate automatically, and the show’ begins soon as a train leaves the station. RADIO AS DISEASE CURE GIVEN NEW TESTS To test various theories as to the effi- ciency of radio waves in treating disease a special apparatus has been devised i: France. It is so arranged that the radia tions may be better directed upon the af fected parts and, at the same time, there is a means for measuring the amount oj absorption. In a test, a coil of copper eau Part of the Apparatus Used in French Laboratory to Test the Curative Power of Radio wire is wound around the arm, leg or other part, acting as a radio receiver.

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er ‘ ht d n Ol A TT. LLL SSS ee POPULAR MECHANICS 561 SUPER-HIGHWAYS FOR AUTOS TO CROSS THE NATION Sketch of Proposed Automobile Highway across the Country; the Inner Lanes Would Be Devoted to Heavy Bus Traffic, the Outer Ones for Pleasure Cars Two wide automobile highways, span- ning the country, one on the north and one on the south, are proposed by R. A. Carpenter, chief engineer of a Chicago park system, to provide for the great in- crease in motor traffic. The southern road would run from Savannah, Ga., to Los Angeles, Calif., a distance mately 2.800° miles. The northern route vould extend from Boston to Portland, Oreg., some 3,350 miles. Each roadway would be 250 feet wide and have four dif- ferent traffic lanes, two on the outside for lighter traffic and the two inner ones for heavy bus and truck business. The lanes would be separated by curbs and on each side of the highway would be a sidewalk, six and one-half feet wide. Mr. Carpenter proposes to havea right of way acquired for the roads, just as was done in building the railroads. He estimates that both lines could be constructed for $4,600,000,000, including the cost of the land which could be, obtained by con- demnation proceedings. Although the sum is a large one, it is believed that a toll charge would rapidly defray the cost, and that the highways would be,heavily pat- ronized, as they would eliminate delays, of approxi- permit higher speeds than now maintained and eliminate detours. The big roads would be devoted chiefly to commercial and through traffic, entrances -would be provided at intervals of ten miles or more, and it is thought that they would form the basis for a later system of lateral highways to connect them. OILER FOR STORAGE BATTERY PREVENTS CORROSION Troublesome corrosion of automobile storage-battery terminals is prevented by an oiling unit devised by an Ohio inventor. It consists of a lead oil reservoir, shaped like a large washer, which fits about the battery- terminal post, and a felt washer above the reservoir. The two pieces are held in place by the terminal clamp Lubricating oil is poured into the reser- voir, a few drops being added each month. It forms a thin film on the terminal.

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POPULAR MECHANICS | BORAX FATAL TO MOSQUITOES One and one-half part , or boraxtoa thousand oO! fatal to Cornel] vater proved mie squito larve, University scientists have | found. They used it wit] good results on rainwater barrels, cisterns and other places where the mosqui toes multiply, and disco ered, also, that the borax holds it larve-killing powers for a long time One experiment lasted nearly two months but oe J the solution did not lose Traffic Light with Alarm Attachment Rung If Car Crosses the Line; the its strength. The investi Signal Wire Is Seen at Right DANGER BELL TRAPS AUTOS RUNNING PAST LIGHTS One policeman can supervise the lights along half a mile of streets under a system recently introduced in England. It oper- 1 ates in somewhat the same manher as the automatic signal controls except that the } human attendant makes the changes by x 7 ~ 7 » means of an electrically operated lever. Should a car run past the stop light, it wire which causes a bell to ] ie motorist and ring, warning t at the same time BIG WINDMILL RAISES WATER NINE HUNDRED FEET Using windmills to pump water, gener- ate power and perform other tasks is not a new idea, but not many persons realize vhat great improvements have been made in the mills in the last few years. Wheels are now made as large as twenty-two and have ta pered roller bearings, unusual oiling ca- one-half feet in diameter, they pacity and are otherwise equipped for long service with a minimum of attention. On a southwestern cattle ranch is a wheel six- teen feet in diameter, used to pump water from a well 900 feet deep. It is mounted on a tower thirty-five feet high and the complete millhead weighs 2,800 pounds. In spite of this great lift, the pump is op- erated efficiently even with little wind. tors add, however, that the borax should be used only where effects on animals and on plant life will be of no serious consequence, LOOK AT WORLD UPSIDE DOWN TO TEST SENSES Glasses that show all objects as thoug! inverted, are worn by subjects tal special tests at an eastern university. Since they isolate the sense of sight from co-ordination with the other senses, the help determine how intimately the sense are related when the subject tries to pet form tasks while gazing through them ~*stne il Looking at the World through Glasses That Show Ob- jects Upside Down to Test the Senses

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| Se lving thesSecret Se Ray Keech, ¢ motor racer, Wien dari ive a specially built at a velocity of 205 les an hour, shatter- . ll automobile-speed ecords, the world ac- iimed his feat. Yet the thrilling speed } ] he attained was a rich Lil’s gait compared ith the possible veloc- and their The latter, which are following cir- of atoms electrons, cular and elliptical courses, make tril- lions of revolutions a second at peeds which man cannot even con ceive. An atom of air moves a mile a second—twice as fast as a bullet move Ina single gram of radium, for example, many billions of atoms explode every sec- ond, each a helium-atom nu- cleus 12,000 miles a second or sending out shooting electrons with approximately the speed of light. Radium emits a new kind of high-fre- quency radiation called “gamma When exposed to these rays, iron is as transparent as glass. Eleven distinct ex- plosions occur in the various transmuta- rays.” tions of radium atoms and after each ex- plosion, the atom changes into an entirely different element. An atom is the smallest unit possessing the characteristic properties of anv chem- Small wonder they are dif- for forty thousand million ical element ficult to study, million of them at cover an but inch. If were as large as baseballs, a mere thimble- would | rest would area of one square atoms ovide enough to bury blanket 1,000 indescribable ful of air the United States under a thick. Despite the smallness of atoms, science has developed method of treet an effective weighing them ?¢ Model the Quartz Crystal, with a Knotted Thread Markir Each Electron Illustrating, in Six Spirals, the Formation of atter they are shot from electric guns They also have been photographed. The atom in action resembles a shooting star through space. Its collisions produce lig! speeding with other atoms t or fire By proper amplification, the sound of an atom striking a target can be tuned to the perception of the human ear. The cherished dream of the alchemist may eventually become a reality if future adventures in atom hunting valuable discoveries as have past experi mental quests. Atoms of mat already have been broken up by shooti: electrons from these atoms or shattering their nuclei. Scientists now seek to build up such nuclei at master that art, science will be qualified to trans- mute elements—an epocl al eventualit Once the world ought there e1 elements—fire, air, earth and ite 1 the number kept on increasing until, about e middle of the last ee 1 €

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564 POPULAR MECHANICS into gold were working on the right idea Strangely enough, one of their favorite experiments was to try to Change mercur’ into gold, and mercury and gold are just one electron per atom apart. The alche- mists chose mercury because it is the only metal which is fluid at ordinary tem- peratures, and they reasoned it was al- in such an unsta- ate that it might be ] easy to make gold out of it. Recently scientists ave demonstrated that t is probably entirely feasible to make the change, but that it would cost so much for elec- tricity that it would not be pre fitable But why does science know that there are only et two element Mr. H. D. Hubbard with Three Models; Carbon Nucleus, Left, Carbon Atom, e answer is that. ; Center, and Diamond, at Right ’ e electrons are added le Now science has cut the number the structure of an atom becomes increas down to just ninety-two, of which ninety ingly complex until finally it reaches re known. The question immediately stage where it is no longer stable. The re ces o! how science could W rite down sult is radioacti tv, hich is pe ssessed the list from hydrogen, No. 1, to uranium, not only by radium, eightv-eighth on the No. 92, and put a period there, definitely list, but also by the four that follow: ac- ing there is nothing beyond uranium, tinium, thorium, uranium X, and uraniu: othing before hydrogen, and nothing in hese five, being unstable. are constant] etween the element on the list. breaking cd vn and chang ng into e answer jis that every element is com- pler lorms, and it seems certain that he posed of atoms, and every atom is made ond uranium the atomic structure would ip of one proton, a unit of positive elec be so intricate that it just could not live v, and a varving number of electrons, he alchemists, whose misplaced eff« negative electricity, the latter revolv- ere tor so long a joke ei were scie ¢ around the proton, tific in their wa and laid the cornerstone e atoms of the variou element are oO! moclern cl emistrv. One ot them ow believed to be made up this w. the Brand of Hamburg, Germany, sought to difference between any two consecutive make gold by combining everything he imbers in the list of elements being one could find in his retorts, and eventual] electron per atom. In other words, hy- discovered phosphorus, the first element drogen, first on the list, is made up of ever discovered in a laboratorv. More toms having one proton and one elec- than fiftv vears later a Swedish chemist, tron—the simplest structure of all. Helium, Gustav Brandt, investigating some curious [ the rare gas used to inflate American diri- ore found in German copper mines, dis gibles, comes next, with one proton and covered another. The ore looked like two electrons per atom. Lithium is third. copper, but the miners had found the If science could find a way to add one’ could extract no copper from it, so the) ») electron to each atom of hydrogen, that called the stuff “Koboid,” after a demon highly inflammable balloon gas would be who was supposed to be intent on annoy- converted into safe helium. ing miners, From the ore Brandt ex- cted and named our modern cobalt. In 1, the German chemist A. F. Cornstedt, In other words, the ancient alchemists tt who sought to transmute other elements 17 al

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POPULAR MECHANICS 565 é = Bh Periodic Chart of the Atoms and a Group of Atom Models Devised by H. D. Hubbard, Secretary of the Bureau of Standards, to Illustrate Theories of the Composition of Matter »y the same methods, extracted another element from the same ores, which he named nickel, taking the word from “kup- fernickel,” meaning “copper devil,” an- other name the miners applied to the de- mon Kobold. Those discoveries were the foundation of modern analytical chemistry. In the latter half of the eighteenth century, Henry Cavendish discovered an old formula writ- ten three centuries earlier by the great alchemist Paracelsus and from it prepared i gas he called “inflammable air.” That eas was hydrogen, still used to fill balloons and airships when helium is not available. The element nitrogen, that forms four- fifths of the ai nist, Prof, rpg of the university r, was discovered by a bota- of Edinburgh, 772. Two vears later, Joseph P edie of Philadelphia, separated the life-giving element of air, oxvgen. In the same vear Scheele, of Sweden, discov- ered the element chlorine, first poison gas used in the World war, and the purifying agent in most municipal water plants, By 1804, twelve new elements had been added to the list of such common ones as *. . . - gold, silver, copper, iron, tin and a few others known to the ancients. Three vears later, Sir Humphrey Davy, the in- ventor of the miners’ safety lamp, added a whole list of new substances. Davy, a druggist’s clerk, had discovered nitrous oxide, and on the strength of that ob- tained a chemical appointment. Experi- menting with the effects of an electric cur- rent on various chemicals, he discovered sodium, potassium, calcium, strontium and barium. His was one of the greatest achievements in chemical research, until the invention of the spectroscope initiated the method of investigation used today. The spectroscope is simply an arrange ment of prisms to break up light into its primary colors, producing artificial rain bows by refracti Its value lies in the fact that when any element is heated to the point where it gives off light, that light, when analyzed, contains exactly the Same wave bands as anv otnel sample Oo light from the same material It is be cause of this that astronomers know what elements are in stars millions of leg! vears away. With the spectroscope to uid them scientists added new elements rapidly. By 1920. there were onlv six of the ninety two missing, and now all but two been found. The last one located nium, was found by Prof. B. S. Hopki of the University of Illinois, and named for his state The two missing ones are Nos. 85 and 87 in the scale No. 85 is expected to be

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( ¢ at r »¥ the tam r ele ent ¢ ad NO S/ ¢ De ed to ¢ e erie of all i met I : m n p sium, u aium C ) Be e ot its location next ¢ C t to t also is cot dered pro ] that traces of radioact ( ot the credit ( the € ( on ( e atc c theo TOC to He D Hubbard € € I of the | »s. | 1 I le rds and con} or the p¢ lic ( t of the toms used in ¢ 1 in- ction The cl t is reall the tounda- ion of modern chemistry and the alpha- et ot the universe He also has origi- ed numbers of models to 1‘ the re of rious mater! als One of his sets of models de picti tne ( tion ot carbon nuclei, carbon atoms nd diamonds, visualizes the hidden reasor for the diamond's exceptional hardness and trength, as well as its clarity. Strength and hardness are due to the +) | arrangement and clarity to which their ment provides Pure ie atoms, the “space patterns” peculiar arrange- silicon, gra (,e1 manium and tin have about the same gen-

MECHANICS eral structure as the diamond. but both its stupendous strength and de and the space patterns that make th precious stone transparent. maison once aid that some day t s l say to an atom in a re se, ‘come a go into this other flowe1 Science read: s able to acc mplish transt tions much more subtle. for. bv mere snooting electri of the right speed ( use of ravs of light of the right fre quency t can Cl ige the electron rangement ot an atom. “We are { 7 > 4X7 a) learning,” savs r. Hubbard, “the exac , Oitage to use in remo ig any electr Irom atl atc l I OT moving suc Cle tens m level , ’ trons om <¢ energ level to a ( ( at will 1s work that the Ge n IS are atte pting to trap 30.000 Uf olts of lightning on a Swiss mount op d scientists of the ( ecie | tion are attempt ’ to produce eg p Man-made ¢ Y Charge + | , Teil \\ 2. 5n8.8.| r S é é ( De oken ( ‘ © ‘ ¢ ‘ T t< ire ci ‘ » Some othe eiement 1 , £ } + ¢ \\ s a. gre p Ol Col t Magne Cc ed 1 celluloid 1 about the size of golf 1 Mr. Hubbard illustrates the ) t1 OT at s through the arrange ent of electr« al t the cent pre | 7 x I ced on <% ooth Liass de K TO] 4 a: 2 ‘ 41 ‘ 1 or floated in ate the magnetic | iS +1 ] ] F é re €1 r ¢ n Characteristic . y ? 7 7 \\ | el accé ( h oO Cll IDE V\ ‘ pe ve ' cleu ‘ d ‘ e¢ eg ¢ 1 . 1 1 1 ele ( s, the i r bs Ss \ . a < LOTHI1 . st. af P ¢1 ‘ i ore | Vitn the pos e « € e cente and tne three neg tives grouped arot d it equic tant Irom each other i jie can i e jiggled about and moved at will. but when released will always return to the own arrangement. positive and two negatives a f as ‘ot. of . a? ’ iorm a line, with the positive in the mi dle. Two positives and one ne the same sort of line, with the negative be tween the other two. Three negative ball placed in a of water move as far for like charges’ repel It is the attraction of « pposites that kee] basin as possible, the electrons grouped about their proton in the atom, and the oppositi n of lke charges that keeps the electrons distrib-

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POPULAR | in their space pattern. In one of Hubbard’s demonstrations, two posi- e and two negative balls form a cube he water, with plus and minus alter- i around the square. Each edge of quare, with one positive and one neg- e ball, represents a hydrogen atom, | the entire square a hydrogen molecule. he arrangement of the atoms is re- ynsible for the various characteristics of ch element. Lead, aluminum and sim- metals are soft and ductile because ir flat, cubelike atoms are face-cen- tered, that is, their flat surfaces face each her, and atoms in one layer can slip moothly across those in the next. On he other hand, iron, tungsten and similar ird metals have body-centered atoms, terlocked so that they do not slip easily. One of the marvels of modern chemistry the way in which the experimenter takes he atoms and fits them together into new nthetic products. Phousands of these atom groups have been produced by the chemist, such things as thein or caffein, which stimulate gently without developing intoxication; like ad- renalin, which duplicates nature’s control of the heart and lungs; like the synthetic dyes that produce new colors, the syn- thetic perfumes that rival the flowers of nature, and like the many medicines that heal disease, relieve pain or produce sleep. “Atoms are veritable wonder workers,” concluded Mr. Hubbard. “They are re- sponsive as. living MECHANICS 567 Cd ‘ m A's ae ipa; UN Leading Dog to the Training Grounds; Animal is Watching the Man He Is to Attack TRAINING SCHOOL FOR DOGS AIDS POLICE DEPARTMENT lo train dogs for police duties, special schools are maintained under the direction of experts who understand the animals and know the tactics of criminals. One of the teachers wears a padded coat so that the dog cannot injure him. GUARD FENCE AROUND PLANE PROTECTS AIRPORT CROWDS things, and they also may be ener- vized like the human body; they labor industriously as jewelers of nature | and crystal builders, while they are also the expert makers of molecules, and even manufacture | far-away stars. We | stand on the thresh- old of the very mas- tery of nature | through the control of atom combina- tions and the re- lease of the energies | Spectator have caused sO many 4 | near-accidents at the Oakland, Calif airpor that officials have constructed a portable lence to keep persons away from the propeller As soon as a plane lands and has taxied to its position on the field, the guard is immediately et in place around the hip so that Visitors are kept at i safe distance from the whirling pro- they can absorb.” Fence in Front of Airplane to Protect Visitors peller blades.

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Seat in Place How It Is Adjusted under Cushion, and 1 Use, with Straps about the Baby SAFETY AUTO SEAT FOR BABY SAVES MOTHER WORRY ' } 7111 wnhile with nts ride in tne automobdiie itn fety when strapped to a special seat that 1 ‘ , ; , ¢ Ss securel\ DV the adrivers side t ts unde e«< ( I ositio lile S ched | ( ¢ C re « ed pout d ext he 17 S ALTIMETER TO DEFEAT FOGS AIDS SAFER FLYING Among the devices being tected } P } ‘ corps for re er fy ng re } | ed altimeter t it registers the € t nce between the plane and the ground bjects bel t all times. This would e a pilot reliable information as to | were fiving throu ! 4 i tude even if he s or in darkness. Instruments now in e are operated by atmospheric pressure d show distance above sea level. Few f them are effective below 1,000 feet. her experiments are being made with an llation to reduce the danger of land- ings'in bad weather. ’ + It is a series of wires, radiating’ from the center of the airport and from each wire signals are sent to the MECHANICS receiving apparatus in the plane, telling the pilot he to govern his descent when visibility is poor. RICHES FROM THE JUNK PILE CUT RAILROAD EXPENSES Bright new tin buckets, cups and other articles are being manufactured from old metal roofing, empty powder and carbide containers and other junk salvaged by the railroads. Old broom handles are into staffs for made signal flags, old canvas transtormed into curtains for the locomo tive cabs and coaches, steam-pipe cover ings and aprons. ‘Thrift practices such a these save the carriers hundreds of thou sands of dollars annually, according to the American Railway ociation. RADIO TOWER ON MOUNTAIN REACHED BY CABLE CARS Radio waves speed to all parts of the world from station WOKO at Mt. Beacon, Mh; 2s wet to towers, visitors use a cable car on reach the broadcasting one ot the steepest inclined rail try Che h Vavs in the coun y. ligh steel supports, resembling ] re ler weh whe huge spider webs, when CA Saf ; at ] O4U TeE€ viewed from be above sea level. | if

: . rach. wes: \ Weta

Looking Up under One of the Radio Broadcasting Towers at Mt. Beacon, New York

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POPULAR MECHANICS 569 TWO-DECK SLEEPING CAR HAS HOTEL COMFORTS — —_ At Left, Lower Room of Double-Decked Sleeping Car, with Berth Made Up, and, at Right, Steps Leading to Platform, and View of the Upper Berths with the Washstand between Them Conveniences of a hotel room or a liner cabin may be enjoyed on the railroad in a double-decked sleeping car designed by an eastern architect. It provides better facilities for dressing, greater privacy, and each berth, or room below, has an indi- dual washstand and other plumbing, while the same advantages are provided for each pair of upper berths. Instead of the usual center aisle, a passageway runs ilong the side of the car for about two- thirds of its length. From this passage even rooms open, each with complete plumbing. The ceiling height is about seven feet. There is a comfortable arm- chair and a seat which, at night, forms part of the double bed and, during the day, may be shifted to any position desired. An ample recess provides space for luggage. Between the rooms, and opening from the passageway, are steps leading to the upper berths. There are sixteen of these cross- wise of the car, with.a window at either end. There are also lockers for luggage, and the berths are two feet longer than the usual kind. The steps lead to a plat form between the berths. At the foot of each bed is a washbasin and other plumb- ing, and under the basin is a stool that may be used in dressing and to a t a person in getting into bed. Passengers occupying ‘duplex” berths also have access to a day room, which may take the place of the club or lounge car. these TOP OVER AUTO RUMBLE SEAT QUICKLY TAKEN OFF For the protection of perso In the auto’s rumble seat, a top has been intro duced that can be taken off or put on in ° 1 a few moments. It is snapped int: piace To Shield the Riders in the Rumble Seat, the Adjust- able Top Stretched from Back and keeps off sun and dust. Side curtains may be added for protection against rain.

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In the Dugout Where Bureau of Standards Scientists Took the Pulse of a Burning Building by Batteries of Electrical Thermometers in the Search for New Facts about Fires \ JHAT happens when the water hits the fire? and does the water, as many experienced firemen claim, make the fire burn just at first? The fire goes out, true; but why, does it zo out right away. or with a fiercer blaze Firemen have been pouring water on fires since the days of volunteer bucket bri- dozen of them what happens when the water meets the evades, but ask anv halt flame and there is apt to be a disagreement. On a recent Sunday morning the cream of Washington’s fire department, sup- ported by rows of policemen, turned out to watch the government burn down a five-story brick building with a two-story annex. It was a different sort of fire, for not a drop of water was spilt, and the firemen stood at while the floors crashed to the and the walls tumbled out on vacant lots on either side. ease basement For days afterward, they kept watch while flames continued to play through the de- bris until the last stick of inflammable ma- terial had been consumed and the iron and red-hot almost molten bricks cooled down to normal temperature. It was a scientific fire, and, in a heat- proof dugout several hundred feet away, groups of scientists, working in relays kept watch for days over the recording ends of several score electric thermome- ters which had been placed throughout the building and crashed with it. They learned things about fires which had never been known before, particular! the things that happen when a conflagra tion section of the city and spreads so fast firemen can’t reach thie heart of it with their hose lines. Keeping watch with them were repre sweeps a sentatives of every important office-safe and filing-cabinet maker in the country, for each had placed samples of his product, shiny in new paint, in the buildings, stuffed them with old ledgers and papers and then watched them go down with the ruins. Days later, when the ruins had cooled down, the safes and filing cabinets were

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T Just as the Walls Began to Fall; a View of the Five ment Scientists to Study the dug out, jimmied or burned open, and the contents examined to see if they had come through intact, charred but yet readable, or whether they had been completely de- troved. For the first time science learned the temperatures which can be reached in an unchecked fire. Some of the 110 electric thermocouples recorded temperatures as high as 2,500 to 3,000 degrees. At noon the next day, thirty hours after the walls had crashed to the ground, recording in- struments in the debris were still showing temperatures of 2.000 degrees, which is 400 degrees above the fusing point of iron. Hlad water been turned on the fire at its steam generated from some blanketing in the air from the flames effect is the chief one 1

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POPULAR chief infor- mation the bureau of standards tained from its per The ob- conducted fire in Washington, sonally however, is the tem- peratures a fire can reach when uncon- trolled, and the time it can linger in the debris. The buildings burned were part of a row two being removed to make way for new gov- ernment structures. To prepare them for the fire, a new steel roof was installed, to keep sparks from being carried upward and spread over the city, and the brick walls of the five-story structure were re- inforced top rods, half thick, stretching near the with heavy steel an inch and a from wall to wall, The heat, however, was so intense that the mortar and bricks gave the rods did not hold the walls up for more than ten fifteen would have stood alone. way, and fire experts estimated longer than they W hen the bricks the whipped through the air like rubber bands and fell in an adjoining lot. or minutes on one side gave way red-hot bars To duplicate conditions in an 150 tons of old lumber was average office building, stored in the building, representing the fuel that would be furnished by a normal quantity of office furniture. In one ment of the building, the fuel loading was seg - seven and a half pounds per square foot MECHANICS ot floor space, in another double that, and in a third, it reached thirty pounds to the foot, the amounts representing three type of office and factory conditions. Scattered the Various the thirty-two safes and on floors were steel cabinets. In each one was an alarm clock, with an in genious trip lever to stop it when the safe tumbled through the floor, giving the ex moment which it fell. The > ranged from 600 to 3,200 pounds in W eight act at sates and they fell from fifteen to fifty feet, de pending on the floor on which they were placed. Besides the alarm clocks and thei: load papers, of books and each sate contained from tv to four maximum temperature re- cording thermome to rFeatest 1 he show t heat 1 within the v1 reached steel container. The actual test while the walls and floors held, was not that the SO severe as given safes in } Rigging the Thermocouples, Setting an Alarm Clock in One of the Safes, and, Bottom, the Basement-De- bris-Temperature Takers

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POPULAR e underwriters’ labora- ( where they are eated for hours in fur- | es and then dropped | ree floors onto a hard nerete platform; but ter the building col- psed the containers lay the intense slowly days in eat of the debris. cool- The bureau of stand- erected and rned a number of uildings during the last most of them

ds has

e years, ne-story brick, tile or ood structures, packed th obsolete furniture | | om various government | ] The oppor- epartments. however, to de rov a five-story struc- ure in the heart of a bis was unique. A mass information has been lected from the fires d is being used to de- elop standards for fire- sting building mate- als and construction. lypes of construction

th different materials are first tested in gas- | MECHANICS

xy NI w

and the they will stand. for thicknesses, Then experimental buildings are with heated furnaces, me varying charted. ¢ rected, loaded hed off. rd the temperatures reached. furniture, and while electric thermometers A sam- le ofhce-building fire, with twenty pounds combustibles to the square foot, is equivalent to a two-hour furnace test, and rece oO! AUTO LIGHT THAT PIERCES FOG PROMOTES SAFETY For automobile lamps or airplane land- ing-field lights, a special lens now on the arket, projects an amber-colored beam vhich is said to penetrate fog much more effectively than the usual white light. The produced the rays shining through a curious mixture of minute me- color is by The Fire at Its Height, a Few Minutes after the Start; in the Backgr« Is the Post Office Building th fhiltyv-f € pound t< the ( e TOC t 1s equal to 1 eig! t 1 l ce fire Brick walls stood the flames for at hour ‘mn +1 . ‘ inch Iact J in the case of ftour-inch unplastered \ to thirteen hours, for foot-thick one Plaster on both sides incre fire resistance about two and a half hour tallic particles that give the beam a con trasting shade as it is reflected fre highly polished metallic mirror Phi makes it much more visible through the white mist, and the lens also reduces the glare. Pilots at a landing field in Califor nia report that one of the small light vit] a lens of this kind, can be seen throug! fogs and at distances when the big 7,5 (()-candlepower beacon 1s invisible

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574 POPULAR MECHANICS Scoreboard on Ground That Told the German Endurance Flyers How Many Hours They Had Remained Aloft and Gave Them an Encouraging ‘‘Bravo”’ AIR SIGN BOARDS AID FLYERS WIN ENDURANCE RECORD One of the aids to the German pilots who recently set a more than sixtv-five hours of continuous flying, was record of a large scoreboard that showed the num- ber of hours the men remained in the air. he figures were changed as the race pro- gressed so that the flyers could tell at a glance by looking down on the board on the ground, just what performance they had made LIGHT WAVES EASILY BENT AROUND BALL That light waves can be bent around a solid object as easily as sound waves over- come obstacles has been demonstrated by Mason E, Hufford, of Indiana University, Photograph of Woodrow Wilson, Left, and Photo Made with Steel Ball as a Lens Original to Cheer Them On who takes pictures using a steel ball for a lens. Mounting a picture in a small hole cut in a l from a carbon-are lamp through the hole, Dr. Hufford suspended a steel ball halt way between the box aperture and a pho box, and focusing light waves tographic plate, and succeeded in obtain clear photograph, instead of the shadow of the steel ball that might have been expected. The light waves, striking the ball, have their paths changed as they pass into the shadow behind the ball until ing a they either unite or destroy each other, so that the ball acts as a focusing lens. By placing a figure of any kind in the open ing in the box, an inverted image is ob tained on the plate. Moving the ball closet to the negative enlarges the picture, while moving it toward the photographic plate reduces the size of the image. SIX-HEADED CABBAGE PLANT HAS EIGHT-FOOT STALK That controlled temperature has a more important effect on various crops than is generally known, has been shown by ex- periments at Cornell University, where a six-headed cabbage plant was grown on a stalk eight feet high after two vears’ cul- tivation under a constantly high tempe1 ature. Only when the plant was removed to a cooler place—it had been grown un der seventy degrees Fahrenheit and above

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POPULAR MECHANICS did it stop producing heads and form ceeds. The tests indicated that the plant ntinues its growth so long as it is kept . higher temperature, and seeds are not oduced until a lower temperature, re- iting in changes in the plant, is induced. irther experiments show that a cabbage nt requires only a two months’ rest riod in storage at thirty-five to forty Fahrenheit before it can be nsplanted to a greenhouse for seed oduction, Ordinarily, farmers and seed- rowers put the plants in storage through e winter and set them out the second to produce seed. The newer compresses the two-year cycle nto one. Other experiments with cab- the department of agriculture shown that increasing the amount light to which the plants are exposed little or no effect in hastening ma- turity, but that the temperature control of prime importance. vrees pring ethod bage by ave CENTER REST FOR MOTORCYCLE AIDS FLYING START Faster starts on the motorcycle with less trouble are possible by using a support that is adjusted to the bottom of the frame near the center of the machine. It elimi- nates lifting the rear wheel, as is necessary ith the old type of stand, is easily and quickly attached and folds back against the Support for Motorcycle Which Permits a Faster Get- Away and Is More Easily Lowered footrests, out of the way, when the cycle iS in motion, 575 RUBBISH BURNER IN TREE FORM IMPROVES LOOKS OF YARD | - _— Rubbish Burner Disguised as a Tree Stump; It Concrete and Realistically Grained In place of the often unsightly inciner- ator, a concrete burner in the form of a tree trunk has been fashioned bv a Califor nia man. It is finished in realistic color and graining to resemble a stump. WAR ON BLINDNESS Although some fifteen per cent of the 100,000 blind men and w the United States lost their sight through ac- cidental causes, there has been reduction in the number of person blinded through industrial mishaps in the last few years, according to the national society for the prevention of blindness. Educational work has been done among more than 3,000,000 men industry, during the last vear, them the importance of correct lighting omen in a marked and women in teaching and other ways to conserve their eyes and prevent accidents to them. @ Whenever you find that you wish to know more about any article in this maga- zine, write of Information, Pop ular Mechanics Magazine, Chicago. Jureau

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576 POPULAR It Resembles a Plant, but Is a Sec- tion of Phone Ca- ble with Smaller Wires Exposed PHONE WIRES IN PLANT FORM SHOW CABLE STRUCTURE To illustrate how a large cable is made up of London arranged the small many wires, a company strands of a section into the form of a plant. In all, there were 2,000 pairs of wires, and the novel display showed how they were wound and grouped, FOODS MADE BY CHEMISTRY TO PREVENT FAMINE Science will prov ide food no matter how rapidly the population increases, Dr. H. E. Barnard, an industrial chemist, declared held by universal recently in discussing a theory some persons that famine might result should the world become crowded with ple. Legislation will possibly a oT = peo- prevent such an oc- Bar- believes, but currence, Dr, nard even if the popula- MECHANICS plants to work to make food, thirty men, working in a factory the size of a city block, could produce as much food as 1,00 men cultivating 57,000 acres under present conditions. New types of vegetation that will store up solar energy with the same efficiency that coal has done, can be cul- tivated in parts of Sahara the earth such as the where a land, torty miles square, receives in six hours desert. section of as much solar heat as is produced by all the coal burned in throughout the twenty-four hours world. If necessary, chemists can extract fats and sugars from shale oil, coal or petroleum, and the vita- mines necessary for growth and health can be synthesized in the laboratory. has reduced the average working day from fifteen hours to eight, Prof. Harry N., Holmes of Oberlin college declared, Science MILL USES SALVAGED LUMBER AND CUTS LOGS IN SHAPES Logs are cut into shapes instead of into Hat boards by a system of sawmill opera- tion introduced on the west coast. Sal vaged lumber is also utilized to make built- up flooring. Scraps as small as one and one-quarter inches wide and sixteen inches long can be employed in fabricating room rhe new method is said to offer distinct econo- lengths in strips seven inches wide. mies in mill operation and in freight costs. FOLDING ARMREST FOR AUTOIST ADDS COMFORT IN DRIVING f For the conve- nience of the auto- mobile armrest, easily at- tached to the door or interior of the driver, an body, has a folding sill that rises flat tion should erow until there re- mained only one square yard of ara- ble land for each human being, man still would be able to nourish himself with svnthetic food. | By putting yeast Drawing of the Armrest, Showing How It Tilts against the side when not in use so as to be out of the way. The attach- ment is of special when the benefit glass is closed, can be put on quickly and will not damage the upholstery. 578 POPULAR MECHANICS

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POPULAR MECHANICS 577 rEN-MESSAGE CABLE TO SPAN THE ATLANTIC len messages may be insmitted at the same ie, five outgoing and e incoming, on the lat- Atlautic cable being | from Newfoundland » the Azores. Engineers eclare that it will be the stest in the world. It corporates an electrical rinciple known as “ta- ered loading” which per- ‘its it to be operated luplex” or at full capac- ty, in both directions. he line will bring the umber of Western Union cables in the At- intic up to ten and will ifford connection from New York to Germany, [Italy and Africa through 1utomatic relays at New foundland and the Azores. Since the beginning of the World war, cable trafic under the Atlantic For Tired and Dusty Auto Tourists, the Portable Swimming Tank Set Up has doubled, officials re- port. Last year, 93,000,000 words were handled, as compared with 39,972,000 words in 1913, the year before the war. DOOR SNUBBER ENDS SLAMMING AND HELPS FIGHT FLIES Doors cannot be noisily slammed and are kept tightly closed by means of a sim- ple snubber unit which can be attached to any door in a few moments. It is merely a plunger-and-cylinder arrangement, the evlinder being placed on the door frame and the plunger on the door, at top, middle or bot- tom, and directly opposite the cyl- inder so that the plunger will enter the cylinder when the door closes. A special feature of the device is the adjust- ment screw, whereby the plunger may be made to fit properly into the cylinder. at Western Camp Accommodates a Number of Swimmers PORTABLE CAMP BATHING POOL SERVES AUTO TOURISTS Motorists visiting a western tourist camp enjoy the luxury of a swimming pool, provided in a portable canvas tank. It is easily moved from place to place, ts large enough to accommodate a number of swimmers at once and can be set up in a short time. TAP POWER FROM TROLLEY WIRE WITHOUT STOPPING CARS Electric current may be tapped from the trolley wire with a recently introduced de- vice which does not have to be removed when the street car passes beneath it and, so, does not interfere with traffic or with the work in progress. The unit consists of a special clamp that makes contact with the trolley wire and is attached to a sup port by a hinged arm so that the trolley wheel of the car can pass along the wire without interference. POPULAR MECHANICS 579

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578 POPULAR MECHANICS Drawing to Show Installation of the Air-Washing Cab- inet; the Spray Is behind the Wall AIR IN HOMES IS “WASHED” TO GUARD HEALTH Connected to the main water-supply system and easily installed in new or old buildings, an air-washing unit has been introduced to maintain healthy humidity of the air inside at all times of the year. It is essentially a spray and air circulator which cleanses and moistens the air, evap- orating sufficient water to keep an average humidity of about forty per cent. Water is tapped from the city main and passes out at the top of the cabinet, which is in- stalled within the wall, through two fine spray nozzles. At the top of the cabinet is a register, flush -— lar supply of fresh, clean, moist air is al- ways discharged. The washer operates cheaply and with practically no noise FLOWERS FIFTY CENTURIES OLD FOUND IN EGYPT Varieties of plants and flowers that flour- ished in Egypt fifty centuries ago, still grow in the valley of the Nile just as they did in ancient times, study of specimens found in sepulchral monuments reveals An interesting collection of floral memen- toes has been gathered in the national mu- seum of Egyptian antiquities at Bulak, near Cairo. They indicate that the same kinds of flowers that the boy Moses or the children of Joseph probably liked to pick still bloom unchanged in form or colo: The larkspur which loving hands laid upon the bodies of those who died 1,000 years before Abraham and Sarah went into Egypt, still blossoms in sprays of blue as it did many centuries ago. In some of the tombs of later date, various fruits, vegetables and found with hollyhocks mums. down grain have been and chrysanthe Around the necks and upon the breasts of those who died at the time Solomon reigned in Jerusalem, garlands of celery were discovered. The plant does not appear to have been used as a vege table at that time. Plants intended for funeral ceremonies were subjected to great heat, the process helping to preserve them. OLD FIRE ENGINE AIDS AVIATION AS CLEANER FOR MOTORS with the wall, where the air is drawn in. The water falls as a fine mist to the bot- | tom of the cabinet, | where the excess | flows off to a drain pipe. The humidi- | | fied airis forced out through another | near the base of the washing chamber. A con- stant, even circula- tion is thus tained and a register main- : Old Fire Engine regu- Cleaning Motor No longer useful for fighting blazes, an old horse-drawn fire engine, in St. | Louis, has been adapted by an air- plane manufacturer | to clean the motors. Steam is generated in it and blown over the engines through a flexible hose to re- move grease and oil before and after the motors are over — hauled and given running tests.

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i]- Cs POPULAR MECHANICS 579 CHEMISTS DECLARE MAN IS WHAT HE EATS That man is modified the soil on which he ves, just as plants adapt emselves to their sur- undings, is the opinion chemists who are tudying the effects of irious kinds of food pon the human body. he relation is not so di- ect as in the case of lants but is definite and far-reaching, the scien- ts declare. For in- tance, when food sup- ies were almost wholly if local production, va- ious diseases were de- eloped in certain sec- tions more than in others ind could be traced to leficiencies in the soil if those regions, In parts of Switzerland, dwarfish- ness and feeble-minded- ness were pronounced. “——— aan howed that there was ot a sufficient supply of iodine. In other ections of the world, there is not enough ulphur, lime or phosphorous materials ind this lack is manifest in various racial characteristics among the people. The value of insulin in the treatment of dia- hetes, is believed to be due to the fact that it contains certain chemicals that re beneficial to the human_= system iflicted with the disease. The relation of food to the body is still involved in mys- teries, the chemists admit, among them, the riddle of why certain persons are sen- itive to certain substances, For instance, vhy do some persons acquire the hives ifter eating certain kinds of fruit, why do ome sneeze when sleeping on a downy pillow or why do others cough when walk- ing through the woods? These are mys- teries, but chemistry may offer a solution, the experts believe. @ Paper is being made from grape-vine cuttings in California. Ixamination of the soil Chain of Flags Bearing Letters and Towed from Plane to Form Message Which Is Visible for Many Miles PLANE AS FLYING BILLBOARD SHOWS SIGNS BY FLAGS Sky writing with flags is the system a foreign pilot employs in displaying adver tising and other messages. There is a let ter to each banner and the flags are carried in a cartridgelike container under the fuselage. When released, they drop out and form a chain of letters in the prope order, and trail behind the plane like the tail of a kite. The words are visible at a considerable distance. HORSE’S HOOFS START FIRE More than 2,000 acres of forest land in California were swept by fire recently, the blaze being started by sparks from a horse’s hoofs, according to the report of the state forester. This is believed to be the first verified instance of an occurrence of this kind although other fires, starting in this manner, have been reported

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Examining a Model of One of the NC-Boats, the Navy’s Flying Ship That First Crossed the Atlantic; Models of Every Type of Airplane Are Built for Wind-Tunnel Tests ing Aircraft a? Tr J Mes ae ee ee Ca | Scale By K. M. PAINTER “*ET CAN’T be done—a man might as well try to fly.” When a man said this,” remarked Wilbur Wright, “he was understood as expressing the extreme limit of impossibility.” From earliest records, the faculty of flight has been given to the spirits, the gods and their satellites of mythology Strange tales of flying deities, dragons, and demons; winged angels, aerial horses, the antics of and religion. witches and sorcerers, fill the poetry and But man willed to fly and the projects, attempts, achieve- ments, and legends of the centuries. failures of aerial locomotion for centuries were targets for the shafts of short-sighted scientists, critics, authors, and the world at large. The invention of the balloon and Fra dition of dirigibility added only new fuel nklin’s proposed ad- to the inventive fire. In the days when aviation was young, aircraft were designed on inspiration by geniuses who generally had nothing more exact than their own theories on which Every test of a new plane that might bring with it important improvement necessitated the actual risk to base their designs. SRO oe 582 POPULAR of the pilot’s life, and even these tests, made at such great risks, were highly in- accurate as well as tremendously expen- sive. Designers were against a stonewall of fact. : the performance of a plane without actu- ally building it and attempting to fly it. That many of these attempts ended in dis- aster and retarded the progress of avia- tion was inevitable. There was no way of predicting The wind tunnel was the means devel oped to remove the hazards and guess work from the designing of aircraft and substitute a practical, exact, scientific way of testing new designs with no risk at all to human life. Thus, today, before a plane of a new design takes off, the wind tunnel has given an affirmative answer te the question, “Is this craft airworthy ?” One of the first tunnels to be built is located at the navy vard in Washington, and in it all the proposed designs for naval airplanes and airships are tested. The tunnel is made of wood and takes the form of an elongated doughnut. A large fan (or propeller), driven by a 500-horsepower motor, furnishes the wind at a maximum MECHANICS

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/ I te of 180 miles an hour, hen a new design is un- r consideration, an ex- t scale model of it is ide at the government ops under the supervi- on of R. F. Smith, chief raftsman of the tunnel erations. This model is iced in the tunnel, at- iched to recording in- truments that show the perator (in the control om above) the amount pressure expended pon the model at vary- vind velocities. And exact calculations it is ible to figure the lift, and pitching mo- nts of the surfaces pre- ed to the wind. By smbining engine and ypeller statistics (also etermined by wind-tun- N ests) with these 4 ructural data, predic- ons are made with cer- y as to.the performance of the pro- ed craft: its high speed, cruising speed, mntrollability. (nd in due course of operations, the new dirigible for which congress recently ippropriated building funds is “on the block” at the navy yard wind tunnel. This leviathan of the skies is to take the place of the ill-fated “Shenandoah,” having three times the capacity of its predecessor. it will be recalled that the “Shenandoah” as lost in a squall encountered near Zanesville, Ohio, in 1925. . The force of the elements tossed the ship around until the structure broke in two, and the control car very quickly wrenched free in the air. To avoid a recurrence of this mishap, the new dirigible will have a larger diameter in proportion to its length— will be “fatter.” Tunnel experiments have The Control Room of the Navy Wind Tunnel; the Operator at the Desk the Foreground Charts the Returns from the Instruments in shown that the new shape affords much greater strength, and, surprisingly, pre sents less wind resistance, giving greate1 speed in proportion to power Also for trength. it will have two keels instead of one, thus distributing the strain and gi\ ing the five engine nacelles or “powet eggs” better support. The control car, in stead of being merely fastened to the framework by a strut structure, will be directly attached to the frame of the ship. When the proposed model of the dirigi- ble was first tested in the tunnel it had eight control surfaces on the tail, but the wind tunnel showed this to be undesirable, and, eliminating one at a time, the most efficient number finally was found to be four. This elimination of tail surfaces saved thousands of dollars for the navy department, and was a direct result of the wind-tunnel findings. 281 POPULAR MECHANICS 583

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Pal oe bo POPULAR MECHANICS STRAIGHT WING DIHEDRAL ANGLE INCREASES cTAR TY LATERAL SWEEP BACK INCREASES LATERAL STABILITY NORMAL WING POSITIVE STAGGERED WINGS INCREASES LONGITUDINAL STABILITY AND GIVES BETTER LIFT NEGATIVE STAGGERED WINGS SAME EFFECT AS POSITIVE THE EFFECT OF THE SLOT ON THE PASSAGE OF AIR OVER AN AEROFOIL military load of 190,000 pounds. And airship tests form a small part of the rou tine work in the tunnel Through extensive re search it is about anticipated that the world airplane speed record will soon be won again by the United States, and if it is, the wind tunnel should ce: tainly share in the glory Models of the record breaking “Mercury” race that is to be built for Lieut. Alford J. Williams, U. S. N., are now tested The plane will be pow ered with a new twenty four-cylinder X-bank that develops about 600 horsepower. being for airworthiness. motor Wind-resistance experi- ments proved that the best type of craft to main- tain the astounding speed that must be made by this hope of a nation would be a monoplane, and, fur ther, that could be gained by plac much speed ing the wing midway of the height of the fusel- age, that is to say, ona Some of the Important Things Airplane Designers Have Learned Since the Days of the Wright Brothers’ First Crude Ship The wind tunnel was instru- mental in proving that as airships become largely larger, the ratio of useful-load capacity to structural weight improves materially, and that to double the volume and gross lift of an airship requires only an increase of twenty-six per cent in linear dimensions. From this it can be seen that it is per- fectly possible and highly practicable to build dirigibles of enormous lifting capac- ity without sions. reaching prohibitive dimen- A ship of this type, inflated with 10,000,000 cubic feet of helium gas, would be able to accomplish a non-stop round trip to Europe, about 6,000 miles, return- ing with a reserve fuel supply for an ad- ditional 3,000 miles, and still transport a level with crankshaft. Racing planes are no- tricky and even racing pilots fear the effects of kinks in new designs, but this one has been thoroughly tested for unusual behavior and all the discover- able kinks eliminated in the wind-tunnel tests. The results of these tests are for the most part confidential, but there is little doubt that Lieutenant Williams will come very close to the unprecedentea 400- mile-per-hour speed, and none at all that he will break all existing speed records. the engine toriously Two extremes—our largest airship and the world’s fastest airplane—owe their air- worthiness to the wind tunnel. And then there are the usual everyday findings that save thousands of lives and millions of dollars in an unassuming, unrecognized 584 POPULAR MECHANICS

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lit POPULAR iv. Little wonder that pilot ot today looks the wind tunnel as to closest friend, and kes the findings for life lue. lhe perfection of the ew Handley- Page itted wing, American hts to which, for mili- ry use, have been pur- ed the govern- ent so that it can be ap- ied to all army and navy by credited to ines, 1s I saring a Model f Test, Top, and Mounting One ir . the Background Is the Blowe id 1 nel observations. T he slot 1s de igned to eliminate the fatal accidents vhich result from stalling an airplane in light. When the speed of the plane falls velow flying speed, the air flowing over e top surface of the wing, where the i greatest lift normally is exerted, becomes turbulent and broken into eddies, lessen- ng the lift. When that happens, the wing lot opens automatically and begins feed- ing additional air to the top of the wing, drawing it from the underneath surface With the additional air, the wind-tunnel i tests showed, the air stream on the top of the wing was restored. In actual flight, planes with slotted wings POPULAR MECHANICS can be put 11 ing eé m { iptain to improve knowledge about tl th most how plane design at are safe in flight | show hey T e ( tions of what airplane designers angle, dihedral r, all make a plane less SW eepb i k stagge ali uw ~ we through land, the famou British designe var-time plane was pro aneuver©’rs, Geoffrey de nose | duced in quantities for the American army fitted slots to one of hi ht planes and foun it impossible to put the hip into a tailspin fror a stall, as the wing slot he Wind Tunnel alwavs brought it int level flight. He allows the plane to stall, and, with the slot working, came vertically downy 1 unt he struck the ground with sufhcient fore to crumple the landing gear—yet escape unhurt in the crash Wind-tunnel tests also have done muc tvpes ol stable at I th win id ‘ombina call e d inclined to get out of flying position and go into a spin. The dihedral angle is the angle at which the wing tips are sometimes ele vated above a straight line; MECHANICS SW eepback uw e =) ws

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584 POPULAR MECHANICS nounced the opening oj an air-research tory and a giant wind tunnel. The most out standing research labora tory in the United State for airplane development however, is that of the army air corps, at Wright field, near Dayton, in which air conditions are exactly controlled by in- genious mechanical means. The new dyna- mometer laboratory of the army air corps takes into outstanding features of modern aircraft engine labora consideration two The Models to Be Tested Are Carefully Checked; the Tester Is Going Over a Wing Surface to See If the Curve Is True a similar angle, seen when looking up to or down on a plane whose wings, instead of extending straight out at either side, are inclined backward at the tip; and stagger is the placing of the lower wing of a biplane either slightly back or slightly in front of the upper wing. Boys who fly model planes learn much about the effect of a high dihedral angle and sweepback, for both give a plane more lateral stability, thus preventing the ship from falling off on one wing and going into a tailspin. The ship with a straight wing looks faster and more trim to the eye, but isn’t nearly so safe. Wing stagger, on the other hand, pro- vides more longitudinal stability and in- creased lift, for the arrangement of the wings disturbance between them, increasing their lifting effect, and the ratio of total wing depth of the plane is greater, so it has less tendency to soar or dive. lessens air A new plane designed at the California Institute of Technology has an adjustable lower wing, so the pilot can move it for- back to reduce or increase the amount of stagger while in flight. As a result, he can vary the lift to suit the speed of the motor, and can diminish the landing speed of the plane so much that it will come to a stop within thirty feet after touching the ground. ward or The university of Michigan recently an- 586 POPULAR development—air - cooled engines and greater horsepower. The facili- ties for testing have been increased re cently by fifty per cent and the large dy- namometers will be capable of absorbing 100 horsepower in a single unit. A feature of the dynamometer laboratory is a blower system for furnishing a blast of air to the air-cooled engines that will simulate the speed of normal flight and cool the en- gines under test. Another new apparatus will measure the performance of engines at simulated alti- tudes, that is, the air entering a specific carburetor will be conditioned so that the volume and temperature of air can be definitely measured and controlled and temperatures as low as sixty degrees be- low zero obtained. The wind-tunnel in- stallation consists of a and a fourteen-inch tunnel. The former is ca- pable of a wind speed of 240 miles per hour; the latter of 500 miles an hour. When funds become available, it is planned to erect a ten-foot tunnel which will materially enlarge the scope and ac- curacy of aerodynamical tests. five-foot Aside from the improvements in air- plane design, based on wind-tunnel exper- iments, the navy laboratories likewise have done much to improve engine design. The famous Wright “Whirlwinds” that carried Lindbergh, Byrd, Chamberlin, and a host of other flyers, overseas, were developed in co-operation with the navy department, to meet the navy’s need for an efficient air- MECHANICS

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POPULAR MECHANICS uw ie =) uw a eee i R. N. Smith, Chief Draftsman of the Navy, with a Model of the “‘Mercury”’ Racer, Which, It Is Hoped, Will Bring the Speed Record Back to the U cooled engine. The navy experts helped the makers until the engine had been per- fected, and gave the initial orders which put the factory on a_ production basis. Similarly, naval orders were the incentive behind the development of the Curtiss racers that won the Schneider cup for America. The making of an airplane engine that will stand up hour after hour under the grueling load of running “all out,’ or even at cruising speed of 1,900 revolutions or sO a minute, is a miracle of science. Special alloys have been developed to give lightness and strength and, for every part, a metal particularly suited to its purpose is evolved The crankcase alone of the Wright “Whirlwind” has been described as the finest aluminum casting ever made. In its making, metallurgists, engineers, draftsmen, foundrymen and machinists have co-operated. The alloy which goes into it is mixed only from new and unused metal—no melted-down scrap being per- mitted—and from every crucible of molten alloy a bar is poured for rigid chemical S. ; on the Table Is a New Dirigible Model and physical tests, on the results of which the entire heat of metal is either accepted or rejected, Each crankcase is subjected to heat treatment to assure full strength in every section: each is tested under water by air pressure to make sure there are no porous passages or blowholes. and each one 1s acid-etched to make sure that no minute defects may pass unnoticed. The machin ing, too, is an exacting and slow process. The navy standard for several years has been fiftv-hour tests. An engine had to run successfully for that length of time before its type was approved. At the time the test was established, no airplane had remained in flight for anywhere near that length of time, but within recent month the world’s endurance record has beet broken three times, and now is abov sixty hours. On the basis of past developments, it i probable that future refinements within a few years will produce engines capable of running for more than 100 hours at cruis ing speed, and that the endurance record will be boosted accordingly. POPULAR MECHANICS 587

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POPULAR MECHANICS Geometrical Pattern in Lines of Light Formed by Tracer Bullets during Night Target Practice with Machine Guns; the System Provides a Visible Means of Sight Adjustment BULLETS TRACE LINES OF FIRE TO AID MARKSMEN University of Missouri blackboard and bullets as chalk during gunnery practice at Che bullets lines of fire from the muzzles the sky as a Cadets at used the tracer recent maneuvers. blazed ot the guns c nd, when several fauns were g fired at once, a geometrical pattern The lines assisted the produced. marksmen in adjusting their sights for night firing, EDISON’S MINERS’ SAFETY LAMP TO PREVENT EXPLOSIONS Edison is and one of \lthough he is past eighty, 1 still busy with his inventions, | | Edison with Model of the Safety Lamp Which Has a Battery Involving 50,000 Experiments POPULAR the latest is a safety lamp for miners, to reduce the likelihood of gas explosions. Its special feature is a battery on which Edison is said to have performed more than 50,000 experiments, to improve it to its present high state of efficiency. FOURTH OF ACCIDENTAL DEATHS OCCUR IN HOMES Figures gathered by the national safety that accidental deaths in the council show yximately one fourth of all United States occur in homes. Last between 23,000 and 25,000 persons killed by falls, burns, causes in their dwellings, appr vear, were suffocation or other ibout the same number as died from industrial accidents For each home fatality, an insurance com pany paid 200 claims for non-fatal acci that 5,000,000 non-fatal mishaps occurred in American dents, so, on basis, some homes. Thirty-five per cent of the fatal ities were due to falls, nineteen to burns and but two tricity. During the four weeks, per cent per cent to elec ending July 14 of this year, automobiles were re sponsible for the deaths of 514 persons in the seventy-seven large cities of the United States, the council reports. Last year, the that approximately 23,250 were killed in automobile acci dents throughout the country, not includ ing fatalities in figures show persons collisions of automobiles with trains or street cars or in motorcycle the total is The 1927 figures represent accidents. Counting these in, nearly 25,800. MECHANICS

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POPULAR increase of nearly 21,000 over 1911, also in increase in the number of deaths per 100.000 population but a decrease per (0,000 automobiles registered. In 1926, ere were but 170 airplane deaths as com- pared to 185 in 1920. Between 1918 and 1920, the average number of miles flown per fatality in airway operations 97.587. Between 1924 and 1926, it 387,964, showing there has been a marked mprovement in safety. was was MOTOR FUMES INJURE TREES WITH ROUGH LEAVES Chestnut and other trees with furrowed leaves along Paris boulevards, have been injured by sulphurous dust from motor- exhaust fumes, experts report. On the other hand, trees with smooth leaves have not suffered to any noticeable extent be- cause rains and winds keep the leaves Dust clogs the pores of rough leaves, interfering with their “breathing.” clean. PORTABLE NEWSSTAND HELPS PATRONS CATCH CARS An enterprising newsdealer in England has devised a way to give his patrons aid in catching street cars. On a rack above the stand are large numbers announcing the route number of the car next to leave, and his booth is on wheels so that he can reach more customers in the area. News Booth on Wheels and That Carries Schedule of Departing Cars on Rack Above MECHANICS POPULAR MECHANICS 587 RADIO HEADGEAR FOR AIRMEN TO AID COMMUNICATION Aviator Helmet That Carries Head- phones; the Mouthpiece Is Adjusted for Convenient Talking with Wireless messages will be received and sent more easily from airplanes, it is pre dicted, by using an improved headgeat recently tested by men of the signal corps. The phones are inclosed in a snugly fit- ting helmet which shuts out most of the noise, and the mouthpiece of the trans mitter is securely held convenient position for clear speaking to the chest in a CANDLES AT MOUNT VERNON REPLACED BY ELECTRICITY Without marring the estate, electric lights have been installed to replace candles in most of the buildings at Mount Vernon, the home of George Washington and the shrine of the nation. All the except itself, are supplied with current through underground and carefully shielded duits to make them inconspicuous and to The old kitchen spots at Mount ? tely electrified beauty of the structures the mansion con reduce the fire hazard. one of the most interesting Vernon, has It now has an electric been comple range and an elec Other estates near Mount Vernon have also been tric refrigerating system. historic electrified. manv of the fixtures being ex act reproductions of the candle } olders on the walls of Washington’s home 589

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588 POPULAR MECHANICS UNUSUAL BUILDINGS SEEN IN EUROPEAN CITIES Modern Architecture Ap- pears in Bale, Switzerland, in This Massive Structure, a Temple Erected in Honor of Goethe, the Ger- man Poet; at Upper Right Is Tower at the Entrance | to Stadium, in Amsterdam, Where Olympic Games Were Held; It Harmon- izes with the Modern Lines of Other Buildings Surrounding It — “Slums” of a Progressive City of Today; Building Erected by Amsterdam Municipal House Corporation for Its Poor; Design Affords Ample Light 590 POPULAR MECHANICS

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we POPULAR MECHANICS 589 REFLECT NEW IDEALS OF BEAUTY AND UTILITY ee Modernism Reaches Out to Japan with the Result on the Left, a Building Being Erected in Commemoration of the Coro nation of Emperor Hirohito; Little of the Pagoda Influence Is Seen; Above, an Office Building in Hanover, Germany, Which Is an Interesting Adaptation of the Dome and the Long Lines of a Modern Skyscraper ? Church of St. George in Frankfort, Germany, Em bodying Late Ideas in Architecture and, Above, the Oddly Shaped Structure Devoted to the Uses of a Modern Religious Cult; It Was Recently Dedicated ; ’ , in Amsterdam s POPULAR MECHANICS S01

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590 POPULAR MECHANICS MULELESS ARMY OF FUTURE SEEN IN MOTOR UNIT Just as the motor has replaced the horse to a large extent, so it promises to send the mule to the discard in strongholds, the army. one of its last A completely mo- STUDY THE BRAIN WITH X-RAYS TO LOCATE TUMORS Operations on the brain may become less hazardous as a result of a Swiss phy- sician’s use of the X-rays to examine the organ. He finds tumors with the aid of the rays by pumping air into the cavities of the brain. If one tains a tumor, the of the cavities con- torized unit has been assembled at Fort Leonard Wood, composed of about 200 vehicles 1100 men. A test march was recently staged, although old-time and soldiers wondered Part of the Motor Unit in Mule- less Army Column; in the Rear Is the Special Anti-Aircraft Gun on Its Truck how “an outfit mules.” could do any marching without One of the pieces of equipment was a special anti-aircraft gun, hauled on a fast four-wheel-drive truck and capable of being fired while in motion. Records were kept as to the speed made and so flows down, appearing as a black strip. If there is a tumor in the canal, the strip stops ac the edge of the growth. Experiments with a lighter oil may locate the lower edge of the tumor. CHANGEABLE-DATE LICENSE TAG REDUCES EXPENSE To reduce the air cannot pene- trate, and the fact is disclosed on the X-ray photograph by the absence of the usual white patch that indicates a cavity filled with air. Oil is employed in examining the part of the just above the spine. brain cost of making automobile license tags, a marker, pat ented by an Oregon | man, has a.charge- able date tag, the numbers remaining fixed. When a new license is necessary, the numerals form- ing the proper year are simply inserted The oil is heavier than the spinal fluid 592 POPULAR License Tag with Changeable Date Insert Which Elimi- nates Necessity of Attaching Complete New Tag in the slot that is cut for them. MECHANICS

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POPULAR MECHANICS 591 FIVE TONS OF BEEF REQUIRED FOR BYRD EXPEDITION Estimating food and other supplies to ast sixty men two and one-half years is one of the tasks Sydney Greason, chief teward of the Byrd antarctic expedition, as had to handle, and his figures, compiled after determining the probable daily ration per man, will interest everyone who has ad to plan a camping trip. Among the articles Greason is providing are two tons of ham, three of bacon, five of beef and one of chicken. Five hundred cases of eggs will be carried, two tons of tinned butter, a ton of powdered milk, 1,200 pounds of cookies and a ton of jams, jel- lies and marmalade. The men will be equipped with sixty razors and 1,200 packets of blades, nearly 9,000 cakes of hand soap and 1,200 sticks of shaving soap. Five tons of dried fruits will be taken and two and one-half tons of candy.. The cooking utensils will weigh one ton. The expedition’s stores will include 800 sheets, 400 pillow cases, five folding bathtubs and a number of folding cots and chairs, be- two electric washing machines, twelve barrels of washing powder, thirty dozen tooth brushes, five dozen hand brushes and the same number of hair brushes. Most of the equipment is for use at the base camp on the Ross sea. sides GAS CARRIER ON MOTORCYCLE LATEST ARMY UNIT For rapid transportation of containers of poison gas in the army, the French have Motorcycle Sidecar Equipped as Poison-Gas Carrier for a Unit of the French Army devised a motorcycle carrier. A _ large holder is placed on a sidecar support. The new unit was demonstrated recently at special maneuvers. POPTIT_AR MEFRCHANICS Model of the Pick- Up Apparatus for Loading Planes in Flight; the Chute Is Shown in the Foreground AIRPLANE LOADED IN FLIGHT FROM METAL CHUTE Airplanes can pick up supplies while in flight from a special loading unit developed by a western inventor. It is of metal and is shaped somewhat like a funnel split in two, being wide at one end and tapering down to a narrow mouth where the pack- age to be picked up is placed. A cable and ball on a reel are lowered from the plane into the wide part of the funnel, the package attached, and then automatically shot out to relieve the strain of a sudden jerk as the plane flies away. SAILING BOATS WITH BIG KITES NOVEL WATER SPORT Visitors at a Wisconsin lake enjoyed a novel form of boating by using large kites as substitutes for sails to propel the craft. One sportsman had good results with a five-foot kite which he released to an alti- tude ef about 700 feet. By changing his position in the boat, he was able to be of help in guiding it. @ Popular Mechanics Magazine does not publish the name of the maker or seller of any device described in its pages, but this information may be obtained, free, by ad- dressing our Bureau of Information. S02

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592 POPULAR ELECTRIC LIFEBOAT LAUNCHED IN THREE SECONDS Lannea Model of the Lifeboat Which Can Be Launched in Few Seconds by Pressing a Button An electric apparatus by which lifeboats can be launched in three seconds, accord- ing to reports, has been devised by a west ern sea captain. The control buttons are in the pilot house and simply pressing one sends the boat dow . OIL TANK BLASTS PREVENTED BY WASTE GAS By utilizing the waste gases from the ship's boiler fires, a way has been found to prevent explosions on a large tank ves- sel. The method seems incongruous at first as the vapors leave the stack at a temperature of 400 MECHANICS prevent an explosion. Experience ha shown that one of the common causes of such accidents as the tanks are being pumped out, is that the atmospheric oxy gen, mixing with the vapors remaining form an explosive gas, extremely dange: ous. The waste fire gases effectively re move the oxygen. An additional precau tion has been taken when filling the tanks Under old methods, explosions sometimes occurred when incoming oil drove out gases through vents in the tanks where they combined with the oxygen in the ai: and blew up. In this tank vessel, the vapors are forced into the hollow mast of the ship and discharged at the top at a safe elevation above the deck. GLIDER SAILS FOUR HOURS ON AMERICAN FLIGHT Peter Hesselbach, German pilot, re- mained aloft over four hours in a glidet during a recent flight above the cliffs of Cape Cod. The feat constituted an unoffi cial record for America, the previous mark being held by Orville Wright, who re mained up nine minutes and forty-five seconds in 1911 while experimenting with Hesselbach’s American perform ance is far short of the world’s record for gliders, planes. however, as a solo flight of more than fourteen continuous hours was made Hesselbach has flown in a motorless plane for more than five with a passenger. His glider is launched with elastic ropes in Germany some time ago. hours GASOLINE VAPORIZER FOR AUTO REPLACES CARBURETOR to 500 degrees Fahr- enheit and it would be supposed that they would prove a menace when intro- duced into the oil tanks. But the gases are first cooled with a salt-water spray before being let into the tanks and, as they are devoid of oxygen, they act as an effective “smoth- Saving of fuel and more efficient opera- tion of the motor are claimed for a gas- oline vaporizer that replaces the carbu- retor, according to reports. It is said to supply “dry” gas to the cylinders, re- ducing waste, giv- ing more complete combustion and eliminating most of ering blanket” to Drawing to Show the Vaporizer Installed the carbon troubles.

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POPULAR MECHANICS PLANE SETS WORLD’S RECORD FOR NUMBER CARRIED What is probably a world’s record for e number of people flown in one airplane a short time was set recently in -otland, when 2,100 people took joy rides a single airplane in the course of two nsecutive days. The plane, one of the int twentyv-passenger cross-channel air ners of the imperial airways, had flown » Scotland in a race with the “Flying famous non-stop pas- nger train, beating the train by a good irgin. It remained two days at the ‘lasgow airdrome and, in that time, the lot made 105 flights with a full passenger thin i otsman,” the t each time, at a price of half a guinea ($2.50) per passenger, earning a total of more than $5,000 in the two days. No rouble marred the unusual performance. AUTO AND BIKE COMBINED FOR DELIVERIES Features of an automobile and a motor- cycle are combined in a delivery car that has a spacious compartment for packages front and a saddle like that of a cycle for the operator to sit on. This is con- dered car seat as he can get in and out of it more quickly to attend to The vehicle has four wheels, but is said to be as more efficient than an ordinary his deliveries. Rear View of Combination Auto and Cycle, Which Af- fords Fast Delivery Service easily managed in heavy traffic as a motor- cycle and develops high speed. Henry Mi Floating with the Tube Suits, and How the Preservers Are Worn without Hampering Movements RUBBER TUBE SWIM HARNESS HELPS BEGINNERS Pneumatic tubes, the body in such a way that they offer a mit worn about imum of interference to the swimmer’s move ments, have been introduced to help the adjusted there is no risk of their coming off. beginner. They are easil and CLOUDS BOMBED TO PREVENT HAILSTORMS In an effort to break up a hailstorm and prevent damage to crops, Swiss scientis recently bombed the clouds with high-ex plosive rockets. Opinion after the expel iment was divided, however, as to the value of the results achieved. The hailstorm, which swept the Swiss-French fronties caused enormous damage. Hailstones as large as plums stripped fruit trees and en- tire vinevards were washed away. @ Popular Mechanics Magazine does not publish the name of the maker or seller of any device described in its pages, but this information will be furnished, free, by our Bureau of Information,

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. A t : i ha ul | a fl Oty FI ye. bas, f “iy a Captain T. J. J. See, Director of the United States Naval Observatory at Mare Island, California, at One of His Instruments; the Naval Astronomers Are Seeking New Stars aan fee radio reception for the next few vears, and also a decrease in sun- burn for summer bathers, were predicted recently when the Astronomical society of the Pacific met to compare notes on a year’s observation of the heavens. The good news for wireless fans and swimmers is credited to the same cause, a decrease in the number of sunspots, or solar hurricanes. Judging by past per- formances, the number of sun storms will decrease steadily for some years, and then slowly increase until they reach a maxi- mum again in about eleven years. The present cycle, which reached its maximum about March, 1927, followed the previous one by only 7.3 years. but observations stretching over more than a century indi- cate it may be another hundred vears be- fore such a short cycle is reached again. The last previous one was the storm max- ima of 1829 and 1837. Sunspots are responsible for the mag- netic storms and unusual displays of the northern lights, which register on the ra- dio receiver as static. Also, according to Dr. Edison Pettit, there is a striking agree- 594 596 POPUTAR ment between the number and size of the spots on the sun and the amount of ultra violet light reaching the earth, and ultra violet rays are the ones that cause sun- burn, when the body gets too much of them. For four years, Dr. Pettit has mea ured the ultraviolet rays received at Mt Wilson observatory by passing the sun- light through a filter of thin gold and a similar filter of silver, the one cutting off the short violet rays and the other pass- ing them without obstruction. At times, there was a fifty-per-cent variation in the amount of ultraviolet light within the space of a month, and each time the rise or fall of the amount of short rays coin- cided with the rise or fall in sun storms. Another discovery made at Mt. V/ilson as a result of work by Dr. Seth B. Nichol- son, the astronomer who, in 1914, won for himself a place in star history by finding an unknown moon of the planet Jupiter, is the presence of boron, the chief element of the familiar boric-acid eve lotion, in the sun, thereby clearing up the identity of hitherto unknown lines in the sun’s spectrum. None of the lines of boron MECH ANT CS

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2 lo ateditntae eCasReter - 2 > beta, ut fe. - 96) on me 5h ed 52] ae ! The Corona of the Sun during an Eclipse Seen in England Last Year; the Event Was Photographed by As- tronomers Flying in Airplanes Far above the Cloud Line alone have ever been found in an analysis of the sun’s light, as it is broken up by the spectroscope, but when Dr. Nicholson combined boron with other chemicals, characteristic light bands in its spectrum checked with some of the unidentified ele- ments of sunlight. The present year may go down in astro- nomical history as one of the greatest since the invention of the telescope, for, somewhere out in space, near three bil- lion miles away from the earth, a new planet may possibly be rushing into view. Prof. William H. Pickering, head of his own observatory in Jamaica, has spent several years observing mysterious devia- tions in the orbits of Saturn, Uranus and Neptune, outermost members of our solar system. On the basis of his calculations, he has advanced the theory that the only explanation lies in the presence in their vicinity of an unknown planet, of a mass as great, or greater, than that of our earth. Yerkes observatory, at Williams Bay, Wis., the Harvard observatory, at Cam- bridge, Mass., Mt. Wilson and Lick, on Mt. Hamilton, in California, the observa- reirr.wnrweywyT@ a ww tory at Flagstaff, Ariz., and others in Peru and Chile have been busy tor several months photographing the heavens in the region beyond Saturn's rings and between Uranus and Neptune in hope of finding a ninth planet, but so far without success. That there probably is one more and pos sibly two undiscovered planets, is gener ally accepted by astronomers. While Di Pickering’s calculations are not entirely approved, his standing as the discoverer ot the ninth satellite of Saturn lends weight to his theory. More than thirty years ago, he calculated that this unknown moon must exist, and figured that it should be found in a certain location. When the telescope was trained on the spot, he found the satellite, to which the name “Phoebe” was given. His theory of a ninth planet far out be- yond the limits of the known solar sys- tem is based on the erratic behavior of Neptune. The eight known planets, in their order from the sun, are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Ura- nus and Neptune. Johann Elert Bode, a German astrono- 95 mn zagwumyar4seyetyryiaAaAth&T CUT et ce id 6 ora

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member of the solar family, if it exists, must be a couple of bil- lion miles farther away. How far, it is impossible to actually say, for law is only roughly correct, showing an ap preciable error in the case of Neptune, for example. Accord ing to the rule, the planet should be nearly thirty-nine times as far from the sun as the from the sun to the earth whereas actually the distance i about thirty times. Bode’s distance pa

Flaming Storms on the Sun’s Surface, with Streamers 85,000 Miles High; the Small Circle Indicates the Comparative Size of the Earth; at Right, Huge Spots When the Storms Were at Their Maximum in 1926 mer, who died in 1826, established the fact that the planets are arranged in regular order from the sun, in a proportion which is represented by adding four to each number of the series 0, 3, 6, 12, 24, 48, ete. In other words, as the distance of Mer- cury—36,000,000 miles—is represented by four, then three plus four represents the distance from the sun to Venus, and so on. The distribution of the planets, ac- cording to checked so per- fectly that, when it was found there was Bode’s law, none between Mars and Jupiter, where the distance represented by twenty-four plus four called for one, astronomers de- cided the planet in that location must have met with an accident, and so began looking for the fragments. Since that time, hundreds of small planetoids have been found, until the number known is now more than 700, and growing at the rate of about thirty a year. The two larg- est are onlv 400 miles in diameter, and the majority are probably not more than fii- teen or twenty miles across, If there is another planet outside Nep- tune’s orbit, the Bode law fixes its posi- tion as almost inconceivably remote. !t is 2,796,528.000 miles from the sun to Nep- tune, and 92,998,000 miles less from the earth, so that astronomers must look with the eves of their cameras across nearly two and three-quarter billion miles of space be- fore they reach the farthest known planet, at the period when it is closest to the earth, and, according to the Bode law, the next

= * “s ] » x > “<7 ae -

canes al If another planet outside of Neptune is found, its period of rotation around the sun will be measured in hundreds of years. It takes Neptune 165 years to make the complete circuit, and, as it was not dis- covered until September, 1846, it has not as yet made one trip around its orbit un- der observation. Neptune had been discovered, however, its presence had

Before been deduced from the eccentric conduct of Uranus, just as Neptune's fram its charted course gives rise to the deviation conclusion that it is being drawn away by the force of gravity exerted by some tre- mendous mass farther away from us. As early as 1834, astronomers, following Ura- nus’ path, began calculating the position of a possible planet farther away, and by 1846 had determined not only its probable location, but the path it must be traveling. The calculations were so exact that when, on a September night, the Berlin observa- tory started the search, the planet was lo- cated within a few hours.

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POPULAR MECHANICS 597 The next year Sears Cook Walker, of the ational observatory in Vashington, started mputing the past po- tions of the planet, and covered that it was lentical with a star ob- erved twice by Lalande t Paris in 1795. Search of the records in Paris disclosed that the French astronomer, Spectroheliogram of the Sun on May 2 of This Year, Showing a Double Chain distat of Sunspots; Right, Telescopic Camera with Five-Inch Lens and Focal ; far from Neptune as the latter is from Uranus, probably would have to be of even greater mass to have any observable effect The « rbit of Nep- tune has been more or 1 less of a puzzle from the start, as it is more near a circle than the usual elliptic path of planets, stars and comets [If found, the ninth planet probably will be a frozen world, for temper- atures fall rapidly with ce from the sun. Depth of Fifteen Feet, Used at Lick Observatory in the Search for a New The normal temperature Zone of Planets finding his two observations did not agree in position, decided one was in error and marked the other doubtful. Had he gone back to his telescope to determine which of his figures was correct, he would have found his supposed star had moved again, and thereby discovered the planet half a century before it was actually found. The probable size of Pickering’s sup- posed planet, if it exists, is also of interest » astronomers. Neptune, located be- cause of its influence on the orbit of Ura- nus, is the larger of the two. The sus- pected ninth planet, being nearly twice as of Neptune is estimated at 218 degrees below zero, centigrade, whereas the earth’s normal, according to the same scale, is nineteen above zero, FLOODLIGHTS IN CHURCH At night and on dull days, persons at- tending an English church may still enjoy the effect of stained-glass windows by means of a special system of colored flood- lighting. The lamps are controlled from central points and different effects can be produced to harmonize with the various stages of the services.

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598 POPULAR Boat on Auto FOLDING BOAT FITS ON AUTO RUNNING BOARD So compact that it can be collapsed into a small bundle for the auto running board, a folding boat is made of mahogany pieces joined by waterproof canvas and can be put together in less than two minutes. It weighs under 100 pounds, and is about ten feet long and three and one-half feet wide. No tools are required in assembling it, and it can be used with an outboard motor. TIRE GAUGE AND DEFLATOR HELPS PROTECT VALVES Fitted for testing all kinds of tires, a combination gauge, calibrated from ten to 160 pounds, has a deflator attachment so that air can be let out from the valves without using a match, the thumb- nail or other means likely to damage the part. The unit is of a size that prevents its becoming lost easily, yet can be carried in the pocket, and is durably built. Running Board, Ready for Use, and Partly Set Up; It Is Made of Mahogany Pieces Joined by Canvas MECHANICS NON-SKID MOTOR ROAD MATERIAL STOPS ACCIDENTS Interesting tests witha non-skid type of pave- ment on fifty miles of highway are being made in California. The sur- face consists of ninety- ‘ight per cent of hard, crushed rock or gravel, screened so that no piece is more than three- eighths of aninch in great- est diameter. This is thoroughly mixed with asphalt and the com- position is then spread and rolled into the asphaltic-concrete pave- ment while hot. tinued until the screenings are thoroughly impacted into the pav- Rolling is con- ing. The surface sheds water readily, resists accumulations of oil, is not expensive, and tests with it have been successful, according to the report of the highway commission. MOTH PREVENTIVE IN HOLDER PURIFIES AIR Besides destroy- ing and preventing moths, a chemical inclosed in a small container is said to purify air in bathrooms, closed cars and similar places. It gives no unpleasant odor, is effective in pro- tecting rugs, fur- niture and other articles, and al- though the chemical is volatile, a single filling will last about three months, CHART GIVES CORRECT TIME ANY PLACE IN WORLD A chart that tells the correct time any place in the world has been prepared by the bureau of standards for sale through the government printing office. It con- sists of a heavy cardboard disk mounted on a larger card. The revolving disk is

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' s POPULAR vided into fifteen-degree segments, half f which are in white, numbered from one twelve, for the hours from midnight to with the me numbering, for the period from noon dnight. The base card aiso contains rcle, laid off in yon, and half printed in black, fifteen-degree Sseg- ‘nts, with secondary lines every seven la half degrees, The principle of the 1 is that time changes one hour for fifteen degrees of longitude Be- tuse the astronomical day starts noon tead of midnight, time is reckoned from reenwich, England, the base longitude e, and the international date line, where halfway around the world, Knowing the local the change, is the 180th meridian. revolve e, it is only necessary to ] ner disk until the correct time is oppo- te the operator's local time zone. rh earth then be read from the outer circle. irrect time and place around the TEAR-GAS CLUB FOR POLICEMEN TO HELP CONQUER CROOKS Tear-gas “billies’” have been allotted to emergency squads of the New York police department to help them arrest criminals 1 he gas compartment is concealed in one end of what appears to be an ordinary ub rh arrangement permits intro lucing the gas through narrow spaces and nall openings that could be reached only vith difhculty by ordinary gas bombs, Tear-Gas Container in Policeman’s Club for Emer- gency Use in Subduing Crooks MECHANICS 599 yn Clouds of Tiny Ice Particles Reflection of the Sun a Phenomenon Observed from ICE-CRYSTAL CLOUDS MIRROR SUN AND MOON Mountain Peaks \ beaut! ul phenomeno! ymetinie een trom airplanes or trom the top of high mountait is the reflection of t sun or moon upon clouds tormed of t ce Pp ¢ I . is the « | I r he i high altitude and the retlection app only on their upper surface Che panying illustration of the Vas t iken trom the unimit or one ot t pe iks in tf ¢ yea} \ (occa ill t] e r ‘ or elliptical lo of mall d ete ry phenomen Tl cension of French balloonists in 1850, WORKERS WEAR TAIL LIGHTS “Trouble hooters” employed by the Cleveland electric railway ire ber equipped with belts of red reflectors sim ilar to those used at dangerous highway curves, to help prevent accidents. They can be seen at a considerable distance and will working on the lines warn other emploves that men are

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600 POPULAR BUY im wit THE wanes LARGEST TOBACCO MARKET ; For the Guidance of Airmen, This Sign Shows the Wind Direction and Points to Town ROAD SIGN FOR AIR TRAVELERS SHOWS WIND DIRECTION Development of aviation has brought a need for special signs to guard the aviator by day and night. One of the latest steps in this direction has been taken along a southern air-mail route, where a marker has been set up witha to show the direction of the wind, a large arrow painted with the name of the city or town to which it points and a smaller arrow that points due north. The sign thus gives the pilot three essential bits of information. It can be seen, when the weather is clear, from an altitude of 3,000 feet “sock” IDEA OF EXPLOSION ENGINE OLDER THAN STEAM Gasoline and other motors that operate by the force of an explosion are of such comparatively recent that few persons realize the basic idea of such development, engines was conceived long before the ap- pearance of the steam engine. In 1680, Huygens described an explosion motor which was to be operated by discharging a quantity of powder to drive the air out of a cylinder and raise a piston. To that MECHANICS point, his engine relied on a force some- what similar to the working principle of those today, but the useful work was to be done by the piston being forced down by the pressure of the atmosphere against it, thus lifting a weight or doing some other task. There is no record that this engine ever was operated. The steam engine of 1705 functioned on about the same plan, that is, steam was used to lift the weight of the piston, and after this was done, the atmospheric pressure was relied upon for the real work. After Huvgens, almost 100 years passed before inventors caught the vision of rotary motion from their engines. His idea simply involved a piston and a cylinder. In other respects, there was no more similarity between his engine and those of today than there is between a steam hammer and a stone hatchet RADIO FOR TAXI’S PASSENGERS HELPS ATTRACT FARES Radio music drowns the click of the meter and helps draw fares to a taxicab an eastern driver operates. He installed a set for his own amusement when not on the road. He soon found, however, that it proved popular with his customers and ar- ranged it as a permanent feature of his cab. It occupies a convenient space at Radio Set, Installed beside Cab Driver, Attracts Atten- tion of Public and Entertains Passengers the driver’s right where it does not inter- fere with the operation of the vehicle.

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POPULAR MECHANICS 601 Old Castle at Nuremberg as It Appears under the Floodlights; in the Foreground Is an Illuminated Stat Albrecht Durer, the City’s Most Famous Son MAGIC BEAUTY OF OLD CASTLE ance, they give off den e moke and a flame REVEALED BY LIGHTS that will stav lit for three minutes and 1 visible from a great distance f the sub One of the prominent objects in Nurem marine is moving, the distance betwee erg on festive nights is the floodlighted the bombs will in a measure indicate to the astle that stands on a steep sandstone _ rescuers how fast the cratt lt liff near the center of the city. It can be’ in what directior een from a great distance, towering high ibove the other buildings. This year, the WASHING CABINET FOR AUTOIST city is celebrating the memory of Albrecht CONTAINS FIRST-AID KIT Durer, its most famous son, and special llumination has been provided for his For the convenience ot tatue which stands in an open plot below cabinet tank and basin, to wa the ind he castle nd face. a ha 1 oO! T i mrst | pac € é SMOKE BOMBS ON SUBMARINES ape ; ink CO ul TO AID IN RESCUES encanta al So that persons on sunken submarines Ooze may signal their location to boats on the ! ind the urface, a system of smoke bombs has been developed by Swedish engineers. The ombs are placed in groups on the deck treatment which or the conning tower and are released by applied to it in the air pressure. When they burst at the sur- tank itse

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602 POPULAR Suds Tank Dispenses Need Lather Directly without the of Working It Up during the Bath SOAPSUDS FOUNTAIN FOR BATH LATEST TOILET AID Press a button and soapsuds, salt water, cented water or other toilet preparations gush from a spout in a bath attachment a California inventor has introduced. As many containers as desired can be con- nected to the arrangement and they are installed in a convenient position for use while bathing. PROPELLER RESEARCH AIMED TO IMPROVE FLYING [wo goals are being sought in the pro- peller experimental laboratory ot the army at Wilbur Wright field, Dayton, Ohio, to make flying sater and better. One is a metal propeller, to be strong but lighter even than aluminum, and the other is a variable-pitch propeller, the pitch of which can be changed while in flight. Frank W. Caldwell, who developed the composition propeller known as “micarta,” a pressed affair of fabric and glue, is in charge of the work. Present propellers are built with the most efficient pitch for the aver- age speed at which they are to be flown, MECHANICS but in landing and taking off, when th speed of the plane is below flying speed the pitch is entirely too high. Inventor for years have wrestled with the problen of designing such a propeller. RADIO KEEPS MILK FRESH FOR SEVERAL DAYS Wireless waves have been adapted by Vienna scientist to keep milk from spoi ing. A special generator is fitted to a pa teurizing outfit, or two cylinders are e1 ployed, the milk being heated slightly one and then subjected to the radio wave in the other. I so treated, is kept from turning sour fo four days and for a period of two to three weeks if it is cooled. According to reports, mi “CAT’S EYE” TRAFFIC LIGHTS GUIDE MOTORISTS In addition to the regular safety zone for the protection of passengers boarding and leaving surface cars, “cat’s eye” light signal towers introduced in Berlin. The units are simply that catch the glow from and are vertical support where they can be seen at a considerable distance. in warning have been reflector other source mounted on They are of particular service motorists to detour around the safety areas. “Cat's Eye” Lights on Safety Guards at Street-Car Loading Station Help Protect Passengers

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th >e(] or lem we 5 ae "ee Ascertaining the Egg-Laying Ability of a Queen Bee by Photographing Her Brood Comb, and Then Count ing the Sealed Egg Cells by Placing the Picture under a Magnifying Glass By G. H. DACY WH THER to “bee” or not to “bee” is a puzzling question, of personal interest to millions of folks both in this country and- abroad who would like to operate apiaries for profit and pleasure but are deterred because of the great amount of misinformation in circulation about ] oneybees. Twenty-five years ago, your Uncle Sam established the world’s largest bee-culture laboratory near Washington in order to solve mystifying secrets of apiculture and, as far as possible, to standardize commer- cial beekeeping. Bees win the blue ribbon as keepers of secrets. For some twenty centuries, scholars, scientists, philosophers and private experimenters have sought to unravel the baffling mysteries of the bee- hive and honeycomb, but how the bee makes honey remains an enigma. The government search for authentic facts and figures about bees has hatched out into a conquest. Our national experts and various co-operative research agencies have discovered more new facts about bees during the last decade than did the Egyp- tians, Greeks and Romans in several cen turies. Comprehensive experiments have disclosed that bees have measurable ca- pacity for learning and can be trained. Worker bees have been taught to distin- guish between different colors. For ex ample, a red light was placed near a food supply. The busy bees learned quickly to No matter where the red light was placed, the bees would find it and fly to it whenever they were hungry. If the food was removed from the neighborhood of the red light to associate that color with food a position near a green light, the bees, in stead of massing near the former, organ ized scouting parties and began explora- tions, seeking the disappeared food sta- tion. Having eventually found it near the green light, they soon learned to recognize that color as the dependable sign post that indicated food. This test was repeated time and again, until all the colors of the

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604 POPULAR MECHANICS pollen. It may be that during the yea: to come this distance can safely be i: creased to four mile 1 1 The selective breeding of bees will al make available nectat hich under exi ing circumstances is accessible but to limited class ot bees. Red-clover bk soms, tor example, have unusually des corollas and their nectar content can exploited only by bumblebees who tongues are quite long Future selecti “14 ; . ai = 41 Will aid In Vastiv increasing tne number -l hee Ch will r 31¢ 3 +} m9 such bees. nis W resu in e conse . . 1 , , 1 vation ot va uable nowetl nectar wh! + ‘ go 4 ' now goes to seed, because ordinary bee cannot reach 1% Weather conditions vitally affect honey -manufactu: ing activities of t beehive Any bee keeper KA 1] 11 for vou, tor example are gentie Wh 2 devine cohh. dead weather the insect had been used, and the bees spectrum never failed to fi the wanderin; ~ are irritable and yt? more nor to identify it for future reference. by the colored light which marked its position, The average life of a worker bee, it has been found, is six weeks during the peak of the hor lour weel of this nectar-gathering flight is spent in the hive. ing more robust, vigorous worker bees live longer and spend only one that will additional week in the field, can eventu- ally raise the American honey crop by about one-fourth. On the basis of last vear's output, this would mean an i over $9.000.000. creased cash return o The long-winded and better-flying bees of the future will facilitate the establish- ment of apiaries farther from satisfactory “pasturage.” The general practice at present is to locate beehives not farther i than two miles from an abundant and Studying the Effects of Weather on the Activities of Seeee _ r fl 21 sctar and Uncle Sam’s Bees, and, Center, an Electric Flight De- permanent source of Mower nectar an tector That Measures Their Trips

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of C- POPULAR MECHANICS 605 oever comes near their es. Selective breeding | facilitate the multi- cation of workers en- ved with remarkable istance against ither hardships and ease. This also will be lected in increased mney production. The nter losses in American aries throughout the w and cold-weather Its range from $8,000.- O00 to $10,000,000 a year. irious bee diseases col- ect an additional annual ibute amounting to at ist $1,000,000. Such onetary losses can be curtailed by breeding etter bees. And this is — exactly what science pur- Science Solves the Beehive Secrets by Watching the Busy Workers Day and poses to do. Special glass-faced hives which can be illuminated at night and are equipped with microscopes, so that the experts can keep tab on the events which occur in the honeycomb, have assisted markedly in un- twisting the tangled skein of normal bee- hive history. The observation hive, orig- inated by a Vermont banker who kept bees as a hobby, has been improved by the government. It is the dependable motion- picture show of honeycomb enterprises and beehive life cycles. Small wonder that national experts have sat by night and day with eyes glued to these micro- scopes. They have actually seen and in- terpreted the “daily doings” of these in- dustrious insects. You can watch the queen depositing the equivalent of her weight daily in eggs; eggs that are minute, elongated and no larger than two or three fine needle points. Three days after the egg is laid, the white, blind, footless larva emerges. During the next six days this larva performs a record feat in rapid growing. It increases 1,500 times in weight. If the average six-pound baby of the human family made corre- sponding growth, it would weigh four and one-half tons when one week old. Ex- actly twenty-one days after the egg is de- posited, the adult bee is ready to emerge and assume the duties of a nurse bee. Night in a Special Glass-Faced Hive You can even study the superior system of business management which dominates the beehive. Sanitary engineers maintain the honeycomb in cleanly, healthy con- dition. You can easily visualize bee po- licemen directing traffic throughout the congested chambers, cells and paths of this large insect tenement. Bees that be- come crippled or die are disposed of forth- with. The buzz of the beehive is an an- them of industry and not a signal of warn- ing. To certain bees is delegated the task of ventilating the hive during warm weather and of heating it during the sea son of cold. They flap their wings in uni son, simulating fans. To generate heat, they consume large quantities of honey— a ranking energy food—and indulge in bodily contortions. Bees have quickly in creased the temperature in the hive from fifty-seven to as high as ninety-five de- grees Fahrenheit. During the most severe winter weather, the bee-firemen maintain an almost constant temperature inside of the hive. German scientists claim that bees chat with one another by means of a vibratory dance. Their American cousins at the federal bee-culture laboratory have never verified this pretty theory. Uncle Sam’s experts, however, have observed these dances which are reputed to facilitate bee

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606 POPULAR MECHANICS water in a sack, while pellets of pollen are stored in stiff bristle baskets located on tl hindlegs. In the basement of the government lab oratory, a colony of bees—during tl summer flower season it contains fro1 80,000 to 100.000 worker bees—rests on ») ] } delicately adjusted balance which is co nected with continuous chart records i | and weighs the daily production of th ustling honevbees It records exact the time in the morning when they lea the hive, the frequency of return trip discriminates between sood and bad da for honey making and indicates correct! the approach of a storm ees are exci lent weather prophets and usually ma k to the hive se ’ 4 1 eral hours before th: rain or windstort hours, but, on bright warm days, leave t hive as early as 4:00 commun a. m. and continue There is their nectar flight said, tl until seven or eig! constant in the evening Che Storie } ged chars Each day weaker. pauses in of rebuilt tissue and restored energy. The worker bee resembles an electric battery. It starts out cl arged to capacity. Dav by | dav, it runs down and finally dies when it has exhausted the original charge. PR lacing } > f > , nd »V plac SY a Nnive O ees O l Sialie five miles from a source of flower nectar it has been demonstrated conclusively that the workers will fly that far in quest of food. In the mountainous states of the west, apiculturists report that honeybees have flown as tar as seven miles in search of raw materials for honey. The average worker bee weighs eighty milligrams and More Weather Observations, Top; the Electric Pen agi : man, Center, and a Recorder That Charts the Comings one-half its weight. It carries nectar and and Goings of the Bees is able to carry a burden in flight equal to

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are the the ym ah le he tly ps ZS POPULAR rious workers make from four to thirty ehts each day, the water carriers bring- » back more loads and making more fre- ient trips than do the nectar gatherers. nder ideal conditions, as much as twenty unds of honey have been made in this perimental hive in twenty-four hours. (nother interesting apparatus now in e at Uncle Sam’s scientific apiary is a echnical simulation of a flower which ntains a constant supply of nectar. The vice accommodates ten bees at a time nd is located outdoors near the sixty colonies, comprising a maximum popula- mn of 6,000,000 Italian honeybees. An ectrical contact device is hooked up with . float in the dish of bee food and records on a chart the amount removed, the num- her of times the bees visit the feeder and the effects of varying weather conditions on these flights. An efficient method of grading honey by color and flavor has been developed by the Washington specialists. An instru- ment originated by a physicist at Johns Hopkins university, which transmits va- rious wavelengths of light through the honey samples, makes honey grading a rapid and simple process. Honey is now inspected and graded like wheat, potatoes, tobacco, cotton and apples. Despite popular opinion to the contrary, worker bees do not recognize their owner and he is no more immune from stings by his own bees than the ordinary stranger. “If a honeybee stings you,” advises your Uncle Sam, “don’t run for help but stand tilland scratch. The bee that stings you injects its stinger, the poison sac and sur- rounding muscular tissue into the wound. It's your job to scratch this foreign ma- terial as speedily as possible from the MECHANICS 607 Wheel for Rapid Assembly of Shoes; It Makes 600 Pairs in Eight Hours WHEEL TO ASSEMBLE SHOES SPEEDS PRODUCTION Six hundred pairs of shoes can be made in eight hours with an assembling-wheel apparatus introduced in France, accord- ing to reports. Separate parts of the shoes are placed on holders about the cir- cumference of the wheel and the stitching and other processes quickly accomplished. OUTBOARD HULL LIKE PLANE GIVES HIGH SPEED Increased speed in outboard-motor boats has been attained in a craft with a body somewhat like the streamlined fuselage of an airplane. Features of the flying boat have also been applied to the craft to de- crease bottom friction. wound with your finger- nails. Dig it out at once and the wound will not swell while the pain will soon cease. The gov- ernment experts have never discovered any remedy for bee stings. The wounds are so small that it is impossible to introduce any solution in sufficient quantity into the tiny puncture to accomplish any good.” Outboard Boat with Hull like Fuselage of Plane, to Decrease Wind Re- sistance and Water Friction

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608 POPULAR MECHANICS outside the earth, th: For Emergency Police , , | Duty: This Motorcycle Kennelly -Heavisi- Unit Aids the Berlin De- laver. The vagr partment Where Traffic Is a Heavy, as It Is More Waves being phot Easily Handled Than an ‘ : ar | vrapned app: >t Vta Automobile gral hed ppasn itl) il an excursion sever! thousand miles mo } than the direct pa trom the transmittet the receiver, in opinion of Dr. J. Barto Hoag, one of the inve tigators, who is endea oring to record classifv the signals ype of co-ordinat hem with definite pl nomena on and abo MOTOR TRICYCLE FOR POLICE le believes that some of the waves ma h pole and return. Durt 1 CARRIES FIVE MEN circle the not mimic game of wariare recently, a rad Successful experiments have been con- operator received the code “4,” meat ducted in Berlin with a motor tricycle that to open the port of New York. r] carries four policemen and a chauffeur. It sender had relayed the message “V is speedy, easy to handle in heavy traffic meaning to close the port. The odd m and strongly constructed for the some- take had been caused by an echo Tr} times rough service it has to perform. receiving operator had caught a dot mal ing the sign “4.” In reality, it was not 1 RADIO-ECHOES SECRET SOUGHT (10! but the echo of a dash of the signs HIGH ABOVE EARTH \ It had passed around the world bu its echo had been received first One of radio’s most perplexing my teries, the strange “echoes” that some- FOLDING PARTITION LIKE DRAPE SUBSTITUTE FOR DOORS times cause serious contusion in receiving ' messages, being investigated by scien- tists at the university of Chicago. A pho Wall partitions that fold up when push tographic film that move five feet a back, and that may be covered with tape second on a re- plesinienhinesten trv or othe: materials to volving drum match the registers a Se@- ries of multiple, scheme of dec diminishing oration, hav “echoes” com- recently bee ing in at an in- introduced terval too short They are con for a complete structed with a journey around steel frame the world and work, do not too long for re- sag or get out flection from of order and, if the peculiar desired, may be strata of elec- trons that lie from. seventy- five to 150 miles made fireproof Another fea- ture is that thev absorb sound. Folding Partitions in Use, and Cross Section of One

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he it if e POPULAR CALL LETTERS FOR AIRCRAFT AID RADIO CONTACT fo simplify radio communication to and sm airplanes, the craft are assigned spec- ed call letters so that the identification a particular plane is positive and erators are spared time in sending and ceiving messages. The purpose of the in is essentially the same as the system designating broadcasting stations by a es of letters. As worked out by the ernational bureau, at Berne, airplanes have five letters in their calls. The will signify the nationality and the er four will be the registration mark the plane. AIR MOISTENER FOR FURNACES PROMOTES HEALTH To insure proper humidity in the home, moistening outfit easily installed in the hot-air furnace is said to greatly promote health and comfort and to save fuel. Its ential feature is that, as the water is iporated, a fresh supply is constantly Drawing of the Moistening Outfit Installed in Hot-Air Furnace; Note Supply Chamber at Right introduced from the house system through il automatically regulated valve that keeps the vaporizing pan filled to the de- sired point at all times. This eliminates the need of refilling the pan by hand. PLANT THAT RESISTS FIRE TO HELP GUARD FORESTS Further protection of forests from fires is seen in a plant imported from South \frica which is fire-resistant. It is com- posed largely of water yet is said to grow abundantly in arid regions and is good for cattle feed. It will especially help pre- vent brush fires, forest experts believe. MECHANICS 609 Inhaling Vapor to Relieve Air Sickness, through Appa- ratus Designed to Be Carried on Airplanes AIR SICKNESS IS PREVENTED BY PUNGENT VAPOR For the aid of persons who may become airsick while on flying journeys, an in- haling apparatus has been introduced. The ubject breathes a pungent vapor through a mouth and nose piece, the gas being re- leased in any quantity desired from a tank container. According to reports, the sub stance fortifies the system against nausea FOUR-WHEEL BRAKE TESTER AIDS SAFE DRIVING The braking power on each auto wheel and on all four at once is quickly and ac- curately indicated on a testing outfit that takes into consideration the weight of the car. It provides an effective means for equalizing right and left wheels and bal- ancing front with rear Testing Stand for Four-Wheel Brakes

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An Airport by Night; in Front Is the Main Beacon Tower, with the Search- light That Guides Flyers to the Field; behind It, Rising from the Hangar Roof, Is the Wind Cone, Illuminated by a Cluster of Lights; the Runways Are Illuminated by Powerful Flood- lights, So Arranged That Their Rays Are Spread across the Ground, Rising Only a Few Feet in the Air; the Border of the Field Is Marked at Reg- ular Intervals with Small Lights, While, in the Background, a Thin Pencil Beam, the Ceiling Light, Is Thrown on the Clouds to Show Just How. High Visibility Extends; the Lights Shown Are the Standard Equip- ment Recommended for a First-Class Airport by the Aeronautical Branch of the Department of Commerce

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Courtesy Aviation Service The Link between Instructor and Student Is a Voice Tube, Terminating in a Receiver Worn beneath the Helmet; after the First Flight the Student Moves to the Rear Cockpit By J. EARLE MILLER (Concluded from September Issue) VW" WILL practice landings again to- day,” says the instructor as the tudent straps himself into the rear cock- there is nothing new in the announce- ment. Taxi out to the end of the runway, turn the plane until it heads into the wind pen the throttle until the engine speeds ip to 1400 a minute, shove the stick all he way forward and keep it there until lving speed is reached and the pressure begins to lessen, then let it come slowly ind smoothly back as the plane leaves the ‘round, point the nose up a few degrees tor a slow, steady climb, and fly straight into the wind until you get enough alti- tude to make a bank sate. You turn then and fly across the wind, keeping well out from the border line of the field, turn again and go down the side with the wind, turn and cross the other end until you are opposite the end of the runway from which you took off, keep- ing 1,500 feet from the end, as the field rules require. A final turn, point straight for the runway, “cut the gun” until the engine idles down to three or four hundred revo lutions, immediately drop the nose to keep flying speed, and glide in in a long, gentle descent. Keep vour wings carefully ley eled up, shift the rudder, if necessary, to keep the runway flowing smoothly toward vou, pull up the nose a bit as you near the ¢round to level out and lose more flying speed, then, as the ship settles to the eround, ease the stick back farther and set the tail down just as the wheels touch. That's landing practice, to be done ovet and over again. If vou came in smartly you set her down near the end of the run way and can at once open the throttle and take off, “drag” the field and repeat Two or three rounds, and the instructor, instead of signaling for the final bank around to land, motions to keep straight ahead out across country. You leave the scattered houses behind and are over the 611

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612 POPULAR CARTWHEEL TURN HERE AS THE PLANE BEGINS (| TO PALL OWT OF THE _{ ~ ~ =_. STALL The “Split Ess” Is a Quick Way of Losing Altitude Gracefully; the Ship, with Power Off, Dives, Rises to a Stall, Does a Wing-Over and Dives Again MECHANICS open farmland. Straight flving has be come a habit, something to be done auto matically. You remember your lesson look first over the right side, then acros and over the left, watching the fields be neath. Each time your eyes sweep acro the instrument struments, board you check the i make sure the thermometer shows normal temperature, the pressure gauge the proper oil circulation, and the tachometer that the accustomed indicates engine i delivering the number 07 revolutions. Occasionally a pointed hand to left or right until you lose Suddenly the even roar of the engine dies to a soft signals for a turn. track of place and direction. purr, and you instinctively nose down té keep flying speed—vyour first lesson 11 forced landings. Ahead is a enough to fly a brick house into meadow, big It looks easy, and your gliding angle is just right to clear the near fence. Everything is rosy until the instructor opens his throttle again and wildly waves both hands. Some thing is wrong, but what? to the side, but esting over there. large level He points of see nothing inte He continues to point you and you obligingly bank around to go over and see what all the excitement is about Immediately the throttle is jerked back you nose down, and again the engine picks up its roar and you start to climb. Sud denly a distant smokestack, the black plume from a train or one of the many other wind gauges gives the clue. Teacher has caught the student napping with a forced landing and a tail wind. You should have circled into the wind and then picked out a field to land on, instead of trying to drop into the first one ahead Another lesson has been learned: always to remember where the wind is, and be prepared to turn instantly A plane lands and takes off into the wind, if there is time to into it in an emergency. always pick a field and the size and shape of the ground permit it. The lesson goes on, and at every turn you mentally recheck the wind, verifying your memory by watching for smoke, the rustle of the grass below, the movement of the trees, or even a washing flapping on a backvard clothesline That lesson out of the way, another fol-

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POPULAR MECHANICS 613 in short order. The signal comes bank, and another to come out of \ll the indications are that the ship being lined up on some object ahead. 11 check the wind, and find it dead ead. The throttle comes back, you wwe the stick a bit forward and begin iose down. The best field is quite a ahead, just right to reach with a long, ww glide. At that angle, the engine vling hides the view, but a glance over e side places the fence around the field, » vou know you can make it easily. The nce glides beneath, vou nose down to and directly in your se more altitude ith is a tree! feacher has carefully lined you up on n obstacle which calls for quick thinking nd quick acting, and you learn lesson umber two of the day. That's the wavy flying instruction goes. Very little is said on the ground before vou start, and if you are flying by signals, nothing is said in the air. After eacl twenty-minute hop, you taxi in to the line and get a critical review of the day’s mis- takes. As training progresses, you may et in two or three‘hops in a day, if you have the time and other students are not \iting their turns, or you may take forty minutes in one hop to get more landings ne day. Figuring eight hours dual instruction for he average student, three twenty-minute lessons to the hour, and allowing for bad veather, a flying course may stretch out ra month or more. Students have been iloed in one day, as a stunt, but in- tructors don’t recommend trying to hurry hings. Twenty minutes a day or forty later on, and then twenty-four hours to think it over, and digest what has been learned, is best, they say. Planes can fly in most any kind of weather, but students can't be taught landings on a windy, gusty day. It takes a trained pilot to keep his wings level in bumpy weather, and the slightest drop of a wing tip when landing at thirty-five or forty miles an hour may be serious for the ship, and probably for the passengers, too. Army experience has shown that three twenty-minute hops, on successive days, are nineteen times as valuable as one flight of one hour’s duration. Flying muscles have to be broken in to the work of con- Most Graceful but About the Mos: Difficult of All Acrobatics Is the Falling Leaf, the Plane, Stalled in Level Flight, Sideslipping Back and Forth

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614 POPULAR Taking Off in a “Swallow” Training Plane, and, at Right, the Whip Stall, in Which the Plane for an Instant Moves Backward before Whipping Around to Fall in a Nose Dive trolling a ship. After twenty minutes they be- gin to tire, and the stu- dent loses the “feel” of the ship as well as his mental alertness. It is better to come down then, for continued flight is more or less wasted. The better schools will not allow more than twenty min- utes to a hop, and re- MECHANICS there wasn't time to recover level flight and avoid a crash. A spin usually starts when the plane loses flying speed, though some of the modern ships will stall, then nose down and pick up flving speed without spinning The easiest way to deliberately spin a ship is to nose it up into a stall and give left or right rudder with corresponding stick If the spin occurs while flying under power, you immediately close the throttle —‘“cut the gun” is the flyer’s term—and come out of the spin by using opposite control. That is, if you got into the spin by pulling the stick back to lift the nose then to the left rear corner, at the same time applying left rudder, you come out by shoving the stick forward to the right, applying corresponding right rudder. A soon as the ship gets out of the spin, you nose down to pick up flying speed and quire at least three hours on the ground between these flights. Before the day comes for the solo flight, most of the schools give one lesson in “aerobatics,” teaching how to get into and out of the dreaded tail spin. Strangely enough, the dangerous tail spin is one of the easiest of all flying stunts, and is usu- ally the way out of all uncontrolled ma- neuvers, but is so easily stopped that, given sufficient altitude, there is never cause for alarm. The reason so many flvers have been killed by tail spins is that their spins occurred so close to the ground open the throttle. There is no hurry and no excitement about the stunt, given suf- ficient altitude to perform it safely. Tf you are using the voice tube, the instructor's voice, calm and collected, settles any feel- ing of panic. You learn another thing about aero- batics—that there is one position in flying when your ailerons become reversed, just as your ailerons work in reverse order when taxiing on the ground. That is ina vertical bank, and in all the acrobatics in which the plane passes through such a ‘ i

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POPULAR nk. In normal flight, e fore-and-aft move- ‘nt of the stick turns tail flippers, or ele- irs, up and down, to or climb the ship, | the rudder bar moves - rudder side to side, to n to left or right. But en the plane is in a with one ¢ pointing straight n to the earth, the wrmally vertical rudder in a horizontal position d acts as an elevator, o that the rudder bar limbs or dives the ship, d the usual horizontal elevators are in the ver- tical position, so they act a rudder. Outside of an emer- tical bank, MECHANICS 615 ~. : de f © 1 ie | t et eh turn to miss an- other plane, the commer- rency cial flyer has no occasion to make turns so tight as to require a ver- tical bank. In acrobatics, every half roll ind roll and Immelmann turn includes a moment when the ship is banked into that position, but they, with the falling leaf and ular stunts, are left for more advanced struction. The average training plane can do all but two of the aerobatic stunts (hose two are the Immelmann turn and which per- formed by less than half a dozen aviators. lhe training ships, usually fitted with an OX-5 motor, haven’t the power to do the half roll at the top of an Immelmann turn. This particular stunt, the invention of the famous German war-time ace, starts like a loop, but at the top of the loop the plane is rolled over until it is right side up but facing in the opposite direction. To get up enough. speed to do the roll at the top of low-powered ship would be dived from a great height, and might not hold together under the strain. the outside loop, has been a loop, a have to [t is possible, though, to do a cheat on the Immelmann, a tight, fast climbing turn, called a “chandelle,” which, from the eround, would fool anyone but an expert. All the while that air tricks are being learned, the landing practice continues. The Chandelle, a Cheat on an Immelmann Turn, Is a Tight, Fast Climbing Turn for Planes That Can’t Roll at the Top of a Loop A landing is easy to describe, but onl) constant repetition can make it perfect. You soon learn that a plane has but one landing speed—that at which the move- ment [ through the air ceases to be fast enough for the air to support its weight. It can't, therefore, land slower than that, trv to land the nose down until the wheels touch, the result is and if you faster. by forcing and as soon as you drop the tail, the wheels will bounce off the ground. The trick is to learn to and distance so perfectly that you can cut the gun, glide into the field a “two-point” landing, gauge height just above fiving speed, level out a few feet above the runway and then hold the stick neutral, with the tail up and the ship in flying post tion, until you lose the forward speed and the craft begins to settle to the ground of its own volition. At that stick is pulled back and the tail dropped until skid and touch simulta- neously in a perfect three-point landing The average student takes eight to ten hours before he is ready to solo—about three hours on straight air work and the rest on landings and air work combined When the final check pilot him around without advice o1 moment the wheels takes assistance, sees

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616 POPULAR MECHANICS him make a pertect landing the solo flight, the trick has been so well | | When Higher Clouds Throw Their Shadows across Those Below, Weird Pictures Are’ Painted in the Sky by Sunlight and Dark, and through Them the Aviator Wings His Way and authorizes the cost of repairs and upkeep, and each pays for his gas and oil. The latter, in the learned that it has no terrors. solo fly minute Most schools include an hour’s ing in their course—three twenty make a To take the the department of hops, which give opportunity to dozen or so landings alone training course, since commerce regulations went into effect, a candidate for flying is issued a student's examination Che student license, following a physical by an authorized phy covers the training period and the solo flvi1 vate pilot’ cense first ten hours of g He is then license. lo eligible for a pr get a limited commercial or industrial li- cense, to sengers or goods in takes fiftv hours, carry pa and a kind of requires designated areas full plane license: to flv anv load 200 hours, plus a rigorous examination transport anvwhere with any \ course of instruction, ground school, fifty the school, costs, on an flving training and hours’ solo in a ship owned by between $900 and $1,000, though the rates vary somewhat in different parts average \ school course and fly- ing instruction, including hour averages from $350 to $450 or $500. of the country. one solo, Some students cut their expense some- what by forming a club of twenty or more solo graduates, putting in about $150 each Chev then and buving a plane pro-rate Snip, Some costs from $2.50 to average training $3 an hour schools operate grad uates’ clubs in which title to the club ship school, and in exchange a remains in the furnished to super vise the club flights, make inspections and flights of day, licensed instructor is check the plane each and certify the members’ logbooks. Altogether it is a difficult to learn, not especially great game, not too dangerous, and tar than driving an more interesting automobile or a fast motorboat. CASE FOR AUTO KEYS PREVENTS RATTLING AND LOSS a Four ke\ a & and con a held ina ecurely veniently small that them from ractling leather case prevents against the auto dashboard and | also protects the pocket. The case insures against is SO ad that key is easily loss and justed any } i i one on selected for use.

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tomb, in one compartment the bodies of two adults and a child. POPULAR MECHANICS 617 ICE KING’S TOMB FOUND ON ALEUTIAN PEAK The tomb of an ice king, who ed thousands of years ago, in at is known as the Stone Age, been found in the Aleutian inds, off the Alaskan coast, by e Stoll-McCracken expedition the American Museum of Nat- ral History. The expedition ent to the islands to seek mum- ies older than those of Egypt, a link with the civilization that ay have crossed the ancient land ridge of Bering strait, by which e animals of what is now the ;obi desert came to America. On he summit of an almost inacces- ble island they found a double mummy of a person apparently of igh rank, and in the other the \ll four were perfectly preserved, f\ | A Vi - ee ~ iz — vith their clothes, weapons and ther belongings. The ice king ore a tanned otter-skin coat over a shirt of bird skins, and was wrapped n a shroud of animal skins, which in turn vas inclosed in a layer of sea-lion intes- tine. It is possible the bodies may prove to be Stone Age Eskimos, or, perhaps, early Indians of a still remoter time. AUTO BED CONCEALED IN TOP SIMPLIFIES TOURING When not in use, a full-length bed in- ide the automobile is concealed under the top. It is quickly Auto Harnessed as a Hoist; Lowering of the Bucket without Re- versal Is Done with the Lever Control HOIST RUN BY TRUCK OR CAR LATEST BUILDING AID Easily installed on the motor truck or car, a hoisting outfit has been introduced to serve builders of all kinds. It can be adjusted in a few minutes, is detachable and interchangeable and is controlled by a single lever. It is quickly connected to a rear wheel, which is jacked up and is al ways turned in a forward direction, no reversing of the transmission and racing of the motor being lowered and the up- olstery of the top interior is unhooked to form covers for the sides. Further privacy is afforded ‘round the front of the car over the windshield. The ar- rangement is prac- tical for tourists and for doctors who Poe oS by a special curtain ae necessat to lower the bucket T | i q Popular Mechan- Ics Magazine does n + miwhlicl the 0 pu ) . Liic¢ . — | a ae el Tlie a . name of the maker | or seller of anv de vice described in its pages, but this in formation is kept on file and may be obtained, free, by use their cars as addressing Bureau Auto Bed Lowered for Use; in Daytime It Is Raised ambulances. and Concealed in the Top of Information

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618 POPULAR | | Testing a Policeman’s Walk on the Special Treadmill Which Helps Reveal Defects TREADMILL TEST FOR POLICE REVEALS WALKING FAULTS Correct walking is important to all, but especially to policemen who are on their most of the time they this feet are on duty. foot tested the pol cemen of To emphasize fact, a specialist recently Provi- dence, R. I., in a special treadmill, which enabled him to illustrate various points as the subject “ and revealed faults in his carriage, the manner of plac- ing his feet and other details. performed” HELIUM USED IN RADIO TUBES ALSO FOR DRYING Once considered a rare element, and ex- tremely costly to produce, helium is now available in commercial quantities and is hbe'ng utilized for many purposes, besides indating balloors ard dirigibles. It is es- pecially serviceable in the preparation of a synthetic atmos, here for deep-sea divers and caisson workers, where abnormally high pressures often cause “the bends” or - Caisson sickness. This painful and some- times fatal ailment is believed to be due to the release of nitrogen previously dis- solved in the blood. The advantage of he- lium, which is mixed with oxygen, is that MECHANICS it is not only more inert than nitrogen but has the lowest solubility in water oi any gas known. Its use therefore in creases the limits of the pressure at which work can be performed and also lessen the time of compression and decompres sion of the operator. Helium is gaining favor in annealing and other metal ope: ations as it is practically insoluble in molten metals. It is being used for filling radio tubes, and glow lamps and tube for signs, and as a cooling medium in elec tric transformers and high-speed genera tors. Because it is chemically inert, ha high heat conductivity and low density and can therefore be circulated rapidly, it is particularly suitable for drying o1 ganic and inorganic chemicals quickly. It is also used in toilet preparations. PLANTS TREATED WITH RADIUM TO SPEED GROWTH By coating flowerpots, vases and other containers with a substance that gives off radium emanations, a way has been found to stimulate the flowers. growth of plants and Used on stakes and other articles placed in the eround, it also helps tree and field ‘crops. As the emanation is given off, it explodes and produces a ga which is beneficial to the plant. The ma allie 1 Pa a ee NO,I | CITY WATER CITY WATER WITH ONE Pe, RADIALIFE DISK IN DISH es ee Results of Growth in Three Plant Specimens of the Same Kind, to Show Benefits of Radium Treatment terial lasts for many years, so that its effects are not diminished and the action continues, night and day and at all seasons,

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POPULAR MECHANICS 619 Teaching Four Music Pupils t One Time with Lights and Special Keyboard LIGHTS AID IN PIANO LESSONS ON MULTIPLE KEYBOARD Several children can be taught at once a multiple-keyboard arrangement for truction in piano playing. As the acher depresses a key, a small light ap- pears above a corresponding key on the pupil’s board. After a few minutes of ractice with the lights, a trial is given vithout them from memory. The method said to have been successful in helping he beginner to become familiar with the piano and to master both the white and black keys. The child is also amused by the lights and much of the drudgery of the lessons is eliminated. GAS IS BOILED OUT OF METAL IN ELECTRIC FURNACE Scrap metal is made to produce volumes of power gas by treating it in a high-fre uency, induction vacuum furnace. An old automobile piston gave up thirty-three times its own volume in fuel gas. Two cubic feet of cast iron furnished vapor vith energy equivalent to about ten horse- ower for a duration of some twelve min- ites. The gas hurned with a clear fame and had a heating value equal to three-fourths that of illuminating gas. After the va- por has been re- moved, the metal is more satisfactory or making mag- nets than ordinary ron, has a brilliant Top of Car Rolled Back, and Side View to Show the Interlocking System of Fastening sheen and holds its luster for several months. The treating furnace is an odd contrivance for, though it melts the hard- est metals quickly and would distil them like so much water were they left in long enough, it will not scorch a paper or burn the hand. The walls are of glass and the melting pot is a crucible surrounded by a coil of tubing. Electricity is directed into the tubing where it reverses itself 30,000 times a second, inducing a sympathetic current into the metal that has been placed in the crucible. Impurities evapo- rate and are pumped through suction tubes into containers for analysis AUTO TOP ROOF ROLLS BACK AT PULL OF TAB To admit light and air into the closed car, a style of body now on the market is equipped with a roll-back roof. It is held in place by interlocking links like those on traveling bags, overshoes,and other articles. To release the roof, a tab is simply pulled along and the top is fa tened by pullins tab back makes the change 1 he ? oe his from an open to a closed body an ex- tremely simple and easy operation,

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MPN ks a ES & wi ee aon ie CMB ys agi pee Sapo Mig . . tt Ae 1 Ls RS Ps a : Bi The American Steamer ‘‘Trimountain” with All Her Well Deck under Water as a Giant Atlantic Wave Rolls Over; the Battering of Tons of Water Can Do Immense Damage By CALVIN FRAZER | AST spring the “Leviathan,” the 4 world’s largest ship, arrived at New York with her superstructure badly damaged as the result of an en- counter with a huge wave. Her foredeck, forecastle sixty feet above the water, was stove in; seven steel stanchions supporting it were twisted: four large lifeboats were smashed to splinters; crew and third-class accom- modations were flooded, and a searchlight on the foremast, eightv-five feet above the sea, was broken bv solid water. Many similar cases are recorded in the newspapers every year, and a great many more reported to the hydrographic office and the weather bureau. more disastrous in Some are much their effects. Just a few vears ago, the Red Star liner “Arabic” came into port with seventy-five sengers on the injured list. They had been knocked about by an enormous wave which battered the ship from stem to stern and which, according to one account, was 100 feet high. The steamship “Rheinland” Captain Randle, was nearly sunk by a “solitary” wave some years ago while crossing the Atlantic. Her commander, from his ele- vated position on the bridge, observed a pas- POPULAR gigantic wave coming toward the steamer at high speed; tock precautions to insure a maximum of safety, and leaped from the Soon the submerged the vessel bridge to a more lofty position. sea so completely that Captain from 1 vantage, could distinguish only her fore- and funnel. Her whole hull was buried for a time. One man was washed overboard; the second mate, the carpenter and members of the fered from broken limbs; Randle, his coign ot mast watch suf- every boat dis- appeared, and the engine room was almost full of water. several There has been a great deal of discus- sion about the extreme height attained by waves. The usual method of measur- ing their height from a ship is for the ob- server to climb the rigging or otherwise place himself at such an elevation that, as the wave advances, his eye will be just on a level with its crest and the horizon when the ship is in the hollow. The height of the eve above the ship’s water line is then taken as the height of the wave. This method is subject to some errors, espe cially those due to variations in the alti tude of the point of observation on ac- count of pitching and rolling. In a few MECHANICS

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. ae tar. When the Sea Turns to Mountains; a Striking Photograph from the British Warship ‘“‘Snap- dragon” in the Bay of Biscay, Showing the Next Ship in Line in the Distance, While the “Snapdragon” Lies in the Trough of the Wave; Below, the Steamer “‘Discoverer’’ Bucking the Heavy Seas Crossing the Gulf of Alaska; Ships Bury Their Bows under the Waves, Then, as - — the Water Lifts, Hurl Tons of Water High into / the Air and Backward over the Bridge; as the / Bow Dips Down, the Angle Makes Waves Ap ( pear of Tremendous Height, Giving Landsmen an Exaggerated Idea of Their Size OI Waves. Cases a very sensitive barometer has been = she passes from trough to cre used to measure the lift of a ship while Many exaggerated reports concerning a) POPULAR MECHANICS 62.

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624 POPULAR 627 22 POPULAR the height of waves are explained by the fact that the breaking of a wave against an obstacle, such as the bow of a vessel, throws the water toa far higher point than the unbroken More- over, a vessel may encounter a wave while pitching forward, as her stern is lifted by a preceding wave, so that normally lofty objects, such as the crow’s-nest, are rela- wave could attain. tively near the water. In December, 1922, waves of extraordi- nary size were observed during a storm from the White Star liner “Majestic.” On account of the comparative steadiness of this great vessel, the conditions of obser- vation were unusually favorable. Several officers, including Sir Bertram Hayes, the commander, estimated the height of the waves at between eighty and ninety feet. Dr. Vaughan well-known English authority on waves, has accepted Cornish, the this figure as probably correct, though it greatly exceeds the maximum hitherto be- lieved to be possible for caused by ocean waves wind alone. Waves of this MECHANICS height, or higher, sometimes are produced by submarine earthquakes, Cornish states that the average height of the waves severt storm at sea is twenty feet, while the tall est waves in the same storm reach about thirty feet. encountered in a In storms of very exceptional violence the average may be thirty feet and the maximum forty-five feet. The same authority finds that, as a rough average the height of a wave in the open sea, in feet, is about one-half the velocity of the wind in miles per hour. How does the wind cause waves? Why should the movement of air over the sur- face of the ocean lift weighing thousands of their ordinary level? masses of water tons far above Complete answers to these questions cannot yet be given, despite the many studies of waves made by such brilliant scientists as Lord Kelvin, in the last generation, and Dr. Harold Jef freys, within the last two or three years It is well known that all earth’s winds near the surface are “turbulent’—full of Courtesy The Illustrated London News Destroyers, Those Lean, Overpowered, Tremendously Fast Terrors of the Sea, Are Among the Worst Storm Vessels Afloat, Continuously Swept by Waves in Every Tempest MECHANICS

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POPULAR MECHANICS 623 \ Courtesy The London Sphere A Battleship Weathers the Storm; H. M. S. “‘Marlborough” Plowing through the Combers in the Bay of Biscay, Showing How Small a Part of a Huge Vessel May Be Visible in Heavy Weather gusts and eddies, up-currents and down- currents. Thus a wind, besides tending to drag the water along by friction, must sub- ject it toa great deal of unequal pounding, which depresses it in some places and heaps it up in others. Once waves are formed by this process, there are two agen- cies that tend to increase their size and movement. One is what Jeffreys calls the “shelter” effect, due to the difference between the wind pressures exerted on the windward and leeward sides of each wave. lhe other is the suction of the wind on the convex surface of the waves—the same upward pull that helps to lift the curved wings of an aeroplane. Waves in the open sea, though they may race along at the speed of an express train, do not carry the surface water far with them. If we watch a floating log as a wave sweeps under it, we shall see that it makes little or no advance, but merely rises and falls and has a small movement to and fro. Each particle of water in a wave travels nearly in a vertical circle, returning ap- proximately to its starting point. It is the form and not the substance of the wave that moves along the surface. The depth to which ocean disturbance extends is not certain. Laboratory experiments indicate that it may reach downward 350 times the height of the wave, so that a twenty-foot wave would be felt at a depth of over 1100 fathoms. The movement at this depth would, however, be only a small fraction of an inch, The length attained by ocean waves the horizontal distance from crest to crest or from trough to trough—is as impressive as their height. The length of a wave in- creases with the force of the wind pro- ducing it and also with the extent of open sea over which the wind has traveled, this distance being known as the “fetch Waves 500 to 600 feet long are common The longest ever reported was measured by Admiral Mottez, of the French nav, in the Atlantic ocean a little north of the equator. Its length was 2,700 feet. In general, the longest waves and also the tallest are those of the “Roaring Forties” —the region between latitudes forty and fifty south—where the “Brave West Winds” have an uninterrupted sweep en circling the globe. Nowhere else in the world do waves have such a fetch, That a steel steamship should be bruised and battered by big waves breaking over her is not surprising when we consider the observed effects of waves on objects along exposed shores. According to Thomas Stevenson, who invented an instrument known as a “marine dynamometer” for measuring the impact of waves, the maxi POPULAR MECHANICS 625

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624 POPULAR mum force of an Atlantic wave is three ms per square foot. French state that the engineers however, force of the wave the times + Cherbourg d on breakwater a some amounts to three at i half tons per square foot Pe : the breakwater 120 feet and h ] weig! been thrown upward eterhea ater striking blocks of ling at th , feet above low At the Bishop Rock lighthouse, which is exposed to the full force of as displaced con- crete fortv tons heights of seventeen to irtv-Six water the \tlantic waves, an iron column weighing over three tons was thrown up twenty feet At the har bor works of Bilbao, Spain, a solid block of 1.700 was overturned by the waves and dropped ind landed on top of a rock the breakwater weighing tons into the ocean At Ymuiden, Holland, a block of concrete weighing twenty toms was lifted twelve feet by a wave and landed on a pier five feet above high water. The beating of the waves is constantly altering the shapes of the coasts, cutting cliffs, ter races and caves, and producing curiou sculptural effects. This process -is called “wave erosion.” Some shores are worn back by this process at the rate of several MECHANICS leet a vear. The island of Heligola: which in the year 800 A. D. had a circu ference of 120 miles, today has a circu ference of only three miles, and wou probably have been completely worn avy but tor artificial protection The landsman generally describes all ups and of the “waves,” but downs ocean surfa the sailor disti guishes between two kinds of waves, whi and “swell.” They may ex separateiy or together. by the wind blowi merely as ‘ he calls “sea” noe ris at the time and pla of observation, while swell is due to wit other of 1 ocean or winds that have blown previou at the place of observation. When way are once set up in the open sea they m travel great distances, ing in height but prevailing over some part gradually decrea retaining their origin length and velocity. Thus the ocean m be. heaving with a long, regular und lation even when the air is perfectly cal The appearance of swell is often the fi indication of the approach of a storm, e pecially a tropical hurricane, as the produced fear t much faster than the storm itself Wa' 1 ne storm center tra When swell reaches a coast, its chara Rearing Dozens of Feet into the Air, Tons of Water Fall Back with a Mighty Crash; the Picture Shows a Huge Wave Striking the Sea Wall at Colombo, Ceylon, in the Far East 626 POPULAR MECHANICS Sea is produc: (

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POPULAR MECHANICS 625 tics are often much changed. Shoal- water increases both its height and its ocity, and it therefore has much more erful effects than in the open ocean. he heavy seas, locally known as “re- is,” that occasionally visit the Bay of » de Janeiro and the adjacent coasts, rd another interesting example of swell veling for long distances and being con- rted from long, smooth undulations of water into leaping and destructive ives. At Rio these waves, on striking e sea wall, sometimes send a solid sheet vater 100 feet high. he dangerous swell that frequently oc- in the open roadsteads of Morocco enerally due to cyclonic storms cross the Atlantic. For the past seven years is been successfully predicted on the Adjusting the Tgansparent Screen over Infant in Car riage; Protector Is Concealed When Not in Use FLY SCREEN ON BABY CARRIAGE is of wireless reports from Portugal | the Azores of sea disturbance in those ons. There is an interval of about GUARDS INFANT'S SLEEP teen hours between the occurrence of To shield the baby from flies. dust and northwest swell on the Portuguese coast other disturbing and injurious things (d its appearance at Morocco. while in its carriage outdoors, an adju lidal waves,” so called, usually have no able screen for the front has been intro nection with true tides, This name is duced. It is securely attached and, when ietimes applied to abnormally large pot needed, tucks back into the hood ot itary” waves encountered by ships at the buggy, where it is entirely concealed but, in many cases, to submarine = and out of the way rthquakes, and sometimes to great waves cain eee wong LATHE TO TRUE BRAKE DRUMS g » Cal ; . SIMPLIFIES SERVICING orms or by earthquakes. True _ tidal ives, due to the pull of the moon and Truing brake drums and doing genera un, occur twice a day in all parts of the — servicing to all sizes and types of automo ‘cean, but their slope is so gradual that bile wheels are easily accomplished on a hey are quite im- | ——————— lathe with universal mandreland bearing perceptible as ives. Even at the head of the Bay ot adapters. It does all the jobs that are Fundy, where the performed on an tide rises and falls ordinary type of hity feet, there is lathe, but permit no appearance of a mounting the wheel ave, but in the on it in the same Petitcodiac river, manner as it i vhich discharges mounted on the nto this bay, the conflict of tide and current produces a axle, so that test and repairs may be made on the hub the brake drum felloe, hub flange and wheel rim. Ac conspicuous wave, called a “bore.” A similar effect is seen ied stan Auto Wheel Adjusted on Lathe Which Trues the Brake dal Trivers, Drums and Performs Other Service Tasks in several other curate results are thus assured

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626 POPULAR REASON INTELLECT GLAND EXCHANGE 4 RESPIRATORY EXCHANGE | NERVE EXCHANGE CARBONIC ACID ORGAN FOOD MECHANICS the blood. The oxygen-charged blood conducted to the heart, represented by a pump and is then pressure gauge, and the pressure raised high enough to start th: circulation through the system The dioxide set free by the various oxidations going on in the body is carried to the lung and through the nose Next food is shown entering the mouth, to be ground up by the teeth, represented wheels, mixed with passed down the gullet into the stomach. Here hydrochloric acid pepsin and rennet, the three secre of the stomach, start the chemical process of digestion The food is propelled on by a mo tor-driven carbon escapes shredding as saliva and tions conveyor, and passe through the pylorus, represented as a valve controlled by an attend ant, and into the intestine, where three more juices, bile from the the secretion the par creas and the intestinal juice, con tinue the chemical work. The ef fect of all to reduce food to its three great co: stituents : protei and fat. The first, in the form « sugar tablets, and the protein round disks, are shown entering the blood stream, by which they are taken tothe liver. There bot! liver, of these processes is carbohydrate, are further acted on, the sugar be ing stored as a variety of starch and the protein reduced, until eventually it passes, with some of the starch, into the once more a © Photo tT The Human System as a Factory, a German Diagram That Ex- plains How the Body Does Its Work HUMAN BODY IS PORTRAYED AS A FACTORY as a mechanical fac- tory was demonstrated at a récent exhi- bition of dietetics in Berlin. Starting with the introduction of oxygen molecules into The human body the nose, the graphic drawing showed a bucket-conveyor system carrying the oxy- gen to the lungs, where it combines with the hemoglobin in the red corpuscles of 628 POPT'T apr Inion blood stream. Bone-marrow sup ply, muscle motors, kept running by a pipe line from the blood stream, the intricate chemical plant centering in the kidneys, the bodily functions. The trolling the entire operation by nerve cen ters, is represented as the offices. Berlin complete brain, con @ Popular Mechanics Magazine does not publish the name of the maker or seller of any device described in its pages, but this information is kept on file and will be fur- nished, free, to anvone addressing our Bu- reau of Information. WIRCOTT ANT OS

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Combination Dynamite Drill, Stump Puller and Traveling Cook Shack, One of the Unique Tools Used to Build the Tamiami Highway through the Wilderness of the Everglades Jungle 5.000.000 home of giant Indians, acres of the alli- bril vaterlogged A MERICA'S one tropical jungle, the florida Everglades, itors, furtive Seminole ntly plumede tropical birds and. silent iter moccasitis, was opened to the world few months ago, when six years of road uilding ended with the completion of the miami trail. he jungle swamp is the shortest road be- veen Tampa and Miami, and one of the ‘enic wonders of the world’s highways. little party of pioneer surveyors vho staked out the route, spent more than hree weeks in forging their way across The new highway across he e narrow state, a distance of 110 miles. [heir transport was a weird six-wheeled utomobile that traveled on a roadbed of vire netting. While one roll was stretched front of the car, another was being picked up behind it. The automobile itself was a homemade freak. The drive was removed from the rear axle of a light car and fitted instead jackshaft stretching across the From this shaft it was carried to to a chassis. POPULAR a pair of huge tractorlike wheels, placed amidships. Their furnished traction, and the smaller wheels broad cleated treads fore and aft served onlv to balance the ma chine as it tilted and slithered through the muck. Where they went in twenty-three days of hard roadbuilders fol lowed, with tractors, steam shovels, dyna- mite and drills. Their mounted mostly on mud boats. traveling, the equipment was endless and The cook shack was carried along by building treads t as a second story over drill Now, vears of work, automobiles can cross the the scow that carried the used in setting dynamite charges. after six Everglades in a few hours, and the state is pushing the work of draining the huge swampland to release its 5,000,000 acres of productive muck and marl land for agri- cultural exploitation. Capt. George F. Cook, his son Erben, an experienced engineer, with four helpers, were the original trail blazers who con travel The riddles of tropical gasoline Gladelands quered the through the 627 MECHANICS §29

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628 POPULAR wheels of their homemade six-wheeled car, which they named a equipped with flat inches wide. “oadget,” wooden tires, were thirty Steering was done by brak- ing on first one wheel and then the other. “We started our land cruise,” Captain Cook said, “with the car loaded with one ton of supplies and two light pontoons for use, if necessary, when we reached the Gulf of Erben Two men on scouted a trail about third with a shovel dug wells as we had to run the car Mexico. drove the car. foot one-half mile ahead, and a constantly in low gear, so that the radiator was boiling all the time. was as slow as snail travel. On good days, we advanced about six “Progress while on rainy days in bad terri- tory we frequently traveled from sunup to sunset only 300 yards. At times, we had to pull the car out of holes with block and tackle. had to carry small trees long distances to get footing for the wheels. Sometimes, the car would sink so deep in the mire that all of us had to labor desperately with shovels to extricate the machine be- miles, On other occasions, we fore it was hopelessly ‘bogged down.’ “It was ten days before we sighted a human being. He happened to be a Semi- nole, a Shark river Indian. The gun he carried bore the manufacturing date of 1856. It was of the type that has hung largely on the walls of museums for the MECHANICS last half century. Our car was the first automobile he had seen. After examin ing it, he said, ‘Fool white man’s canoe: everybody walk and feed him water.’ “We shook hands with the Everglad: just as nature had left it, with difficult bay riers of fallen trees and water courses get ting deeper daily as we approached the Mexican gulf. Landmarks? There were We had no speedometer. Dail we retraced our many times. <A pocket compass was our only guide. Wi had to feel our way through the swam lands and sawgrass prairie But finally after many hardships, includ none. steps across the ing short rations for several days, we com pleted the exploration. The back trail t Miami was almost as difficult. trip led to a second several months late in which we four-wheel-dri tractor and trailer. However, after breal ing the king pin of the tractor, we wer forced to abandon it and again empl the ‘gadget’ as the most "Glades vehicle available.” The new highway is built of limestone rock blasted directly along its right « way. An abutting formed by this dynamiting campaign, t] This fis used a dependab| drainage canal w: rock being deposited as foundation m terial for the highway. The Everglades i a region anchored on a rock-ribbed base The decay of sawgrass and other organic material for generations has deposited a

The “Gadget,” a Homemade Six-Wheeled Auto, Balanced and Driven on the Two Huge Center Wheels, and Used by the Survey Party to Cross the Uncharted Everglades to Map the Road 630 POPULAR MECHANICS

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POPULAR er of muck soil from leep on The excavated to eight treet of this rock idbuilders the earth and con- ructed a pure rock-base vav. took three months hard and 00 to deliver and put labor cost work a compressed-air namite hole driller on but pical of the transporta- difficulties iob This was involved moving all the heavy ichinery toand through e waterlogged, isolated, habited domain. In- evolved es of the uity unique machines livered “— the mt.” | he compressed- Ivnamite drill was steel ditch- rare which was also vided drill pener, forge and sim- ] with a too s, as well as com- issary and living quar for the crew of five en, to work many miles lvance of the exca- ng shovels. MECHANICS §29 “ 1 Another “California at interesting Flagship the stump ling attachment of achine. It was ure was this remarkable built in kidder and consisted of the form of a small tractor ith the wheels removed, mounted on a meboat and geared slow so as to pro ce a dead pull of thirty-five tons on a teel cable 600 feet long. This stump ller vanked forty-foot trees, twelve to ehteen inches in diameter, from the earth’s crust as though they were no re firmly planted than jackstraws e Everglades is really a spacious prai dotted with wooded hammocks ele ited from one to three feet above sea vel The highest point along the Tami mi trail is about the center of the state. eing only twelve feet above sea level @ The tallest teen teet high trees in Iceland are but fif- POPUTLAR ’ as It Appeared during a Recent Display in the MECHANICS Hart nolulu, FLAGSHIP PUZZLE OF LIGHTS IN FLEET DISPLAY a Weird Structure of Lights Residents of Honolulu witnessed an un usual spectacle recently whet the U.S. S “California,” flagship of the fleet, was brilliantly illuminated at night while at anchor in the harbor The reflection of the powerful batteries of lights added to ' + 1e weirdness of the disp! PLOWSHARES FROM AUTOS scrap steel from old automobiles is to be used at a western plant the nu facture of plows and othe 1 impt ments The steel mill is 1 1 district vyhere a supply of natural iro re dit ficult to obtain. but it is equipped to han ale 10 (eK) ton 8) Cc! ip eac l ynth 631

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630 Using the Cleaner to Remove Dust from Car Interior and as a Sprayer for Painting- VACUUM CLEANER PAINTS CAR AND OILS SPRINGS For the convenience of the automobile owner, a combination vacuum cleaner and market. The air pressure is utilized to operate a sprayer has been placed on the spray gun for applying paint, to oil the springs, cut from the undergear and for many other operations. grease THREE-WAY SPOUT FOR PUMPS ELIMINATES ADJUSTMENTS Easily attached to the pump, a three-way water conductor permits filling three sepa- 4 * sunew J containers without removing it or making spe- cial adjustments of the pipe. One opening is made in the form of a spout for convenient filling of buckets, and to turn the water in any direction, all that rate AGE? EE TT a POPULAR MECHANICS is needed is to adjust a simple shifting de vice which is held in place by a notch The unit is of special usefulness in con nection with the farm pump. UR TOMBS REVEAL ANCIENT SACRIFICIAL CUSTOMS Fifty-nine servitors of a king and queen who died more than 5,000 years ago, were killed to serve their master and mistress in the next world, it was disclosed recently when the joint expedition of the Univer sity of Pennsylvania and the British Mu seum dug into the royal tombs of Ur of the Chaldees, better known as the home city of the patriarch Abraham. The king and queen whose retainers were slaugh tered to them in death were the Sumerian rulers, Mes-Kalam-Dug Queen Shub-Ad. Soldiers of the guard, women of the harem, men and servants, grooms, wagon drivers, harpists and even two children, probably pages at serve and wome! court, were the victims, as well as six oxen and two asses. The discovery of the tomb is the greatest find yet made in the exca vation of the ancient civilization of the Euphrates, and, because of the far greater antiquity, equals if it does not surpass any- thing found in Egypt. The royal tombs were placed one above the other, indicat- ing the king died first. The shaft through which he and his retainers had been buried filled with earth, but reopened down to the roof of the king’ had been was later tomb, and a burial place excavated for the queen. The burial party apparently took advantage of the fact to break through into the lower tomb and loot it of almost everything of value. The queen’s clothe chest was then placed over the opening Among the few things left in the king’s tomb, however. was a two-foot boat model in solid silver which bears a striking resemblance to the boats still used on the near-by Euphrates marshes, [ to conceal the robbery. Aside from the importance of the objects and the discovery of the sacri- ficial custom of killing a ruler’s household, the excavators disclosed in the tomb en- trance a true arch of baked bricks, the oldest example of this form of construc tion. The find moves the birth of one of the most important discoveries in archi- tecture back many centuries,

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POPULAR MECHANICS 631 [{UMAN SACRIFICES AT TOMB OF AN ANCIENT KING — a a - ee —————— -_ A “a F & Sleped Limestone blocks bernep secrificis Alter SHUB-AD ght, S. W. Clatworthy Artist’s Reconstruction of the Slaughter of the Royal Household of King Mes-Kalam-Dug of Ur, to Provide Attendants for the King and Queen Shub-Ad in the Next World; the University of Pennsylvania-British Mu eum Expedition Found the Tombs While Excavating Ur of the Chaldees

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632 POPULAR Plane with Movable Lower Wing and Fuselage Tail Clipped Short, Produced by California Experimenters 7 QUEER NEW TAILLESS PLANE HAS MOVABLE WINGS An airplane with its tail clipped short and the lower wing movable fore and aft, so that the pilot can change thé amount of stagger at will while in flight, has been developed by a western flying school and successfully tested. Airplanes are built with the wings staggered, one being set behind the other, to improve their longi- tudinal stability and increase the lifting power. By building the lower wings as a single unit, suspended below the fuselage on pivoted struts, and then arranging a control to move it back and forth, the lift can be suited to the speed of the motor, making stalling of the ship almost impos- sible, while, in landing, the set can be fixed to bring the ship to a stop in thirty feet. INVENTOR GIVES “PLANT PILL” DISCOVERY TO NATION The “plant pill” discovered by Dr. W. F. Gericke, of the university of California, which makes cuttings and other plants grow in water, without any earth, is to be given free to the people, the in- ventor has decided. Dr. Gericke, who spent the summer lecturing in Europe, ex- pects to place the formula of his discovery in the hands of state universities and agri- rose cultural colleges for free distribution next spring. Dr. Gericke found that small MECHANICS branches clipped from bushes in August placed in jars of water with his concentrated plant food added, could be raised in the house and would supply blossoms for Christmas time. rose HOT WAVES BORNE BY WARM AIR FROM GULF Heat waves that afflict the eastern part of the country in the summer are caused by warm air from the Gulf of Mexico weather experts declare. It passes over Texas and the central states, is heated during the long days and fails to cool sufficiently during the short night The process may continue until cold air from Canada pushes down from the north- west and mixes with the heated air. RIFLE FIRED WITH ONE HAND WINS BRITISH PRIZE A prize of $15,000 has been awarded Brig. Gen. John T. Thompson by the sritish war office for his rapid-fire rifle. It is operated in somewhat the same man- ner as a said to twice as rapidly as the usual rifle. . revolver, and is shoot Looks Like a Revolver, but It Is a Rifle; the One- Hand Weapon That Won Big Prize

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POPULAR COLOR-EATING GERMS BLAMED FOR FADING HUES Why colors fade, even though they may iss the usual light, damp and acid tests, is been solved by the analyzing micro- ope. The answer is a color-eating germ at thrives on the pigment in the paint, ve, ink or stain used. When it begins ork on printed matter, the color gradu- lly disappears, leaving first a yellow tint nd then successive darker stages until ll the pigment has been eaten away. ‘Jacing an infected sample under the mi- croscope and adding a drop of water, the lass shows millions of spindle-shaped ba- cilli swimming about. Poster work for outside display is immune from destruc- on, as the sun quickly kills all germ life. Printed matter and colored fabrics should ot be stored in damp, dark places. HOE WITH ADJUSTABLE HEAD SAVES EXTRA TOOLS Garden and field tasks that ordinarily would require different tools for satisfac- tory performance can be done with a hoe that has an adjustable head. It can be turned to any position sim- ply by loosening a bolt. By virtue of this arrangement, it can be used for plain hoeing, scraping, weeding or trimming the edges of turf and similar purposes. TAPE TO RECORD PHONE CALLS LATEST SERVICE AID Attached to the ordinary telephone in- strument and operated through the reg- ular circuit, a tape recorder enters the number of the telephone that makes the call when the person called is not present. (he number is perforated by means of a key arrangement operated at the other end. When he returns, the person called can tell by a glance at the-tape if his tele- phone has been rung during his absence. MECHANICS 633 - For the Firemen Who Serve vane én Wharves, This Rubber Suit Acts as Life Preserver RUBBER SUITS FOR FIREMEN KEEP WEARERS AFLOAT Designed especially for men who fight fires along the wharves at Calif., rubber suits devised. They keep the wearer cool and dry and prevent him sinking should he fall into the from the nature of his service, he is not unlikely to do ful tests were performed with ment during Long Beach, have been from sea, as, Success the equip a recent trial SHARPENER FITS ON RAZOR AND WHETS BOTH EDGES Both edges of the double safetv-razo1 blade are sharpened without removal from the razor by a com- bination hone-and- strop device re- & cently introduced. A few quick strokes back said to be sufficient keen The sharp and forth are to produce edges. ener is quickly ad- justed or taken off and strikes the blade while it is in the most suitable position for forming a sharp edge

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634 POPULAR MECHANICS UNCLE SAM’S BIGGEST MINE-LAYING SUBMARINE NY XY \, we The Navy’s New Submarine f . Mine Layer, Largest of Its | AN : AY. Type in the World, Has F " OM sane co ' Passed Its Trial Tests; 381 Feet Long, of 3,000 Tons’ Displacement and Carrying a Crew of Eighty-Three, It Is Armed with Six-Inch Gans as Well as Torpedoes and Mines ie -_ ——. —- ee Mon One Hundred and Six Safety Devices Are Included in the Ship; Top, Left, Air Valves en Deck for Rescue Ship to Connect To; Right, Ballast Blow Valves; Center, View Forward from the Conning Tower, and, Below, the ““V-4" from the Stern

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POPULAR MECHANICS 635 HOUSES BUILT FLAT ON GROUND LIKE SIDEWALKS Hlouses are built flat like pave- ents and then raised into posi- n by a construction méthod that intended to effect savings in me and money. The system was leveloped during the war in the pid erection of barracks and is id to have been applied to ace-time homes with good re- ilts. The foundation walls are hioned in special forms, using r paper, concrete, reinforcing nd an outside finish in rock-block r any other style desired. When he wall has dried thoroughly, it is hoisted into place on the founda- rion footings, cemented to them ind the ends laced together with ods and steel mesh. The corners are poured in special forms. Spaces for floor joists are formed hy wooden blocks, set at the right locations and removed from the vall. Side walls are built in the ame manner as those for the ioundations, except that an insu- lated fiberboard material is em- ployed instead of tar paper, and vindow sash and doors are set while spaces for plumbing and other niches are allowed. This method is applicable to a wide va- riety of architectural styles and effects and is said to permit build- ing a home that will compare fa- vorably with old-world houses that have stood for centuries. NEW KINDS OF CABBAGE TO REDUCE ROTTING Instead of cultivating larger cabbage heads, producers are now triving for smaller ones, to meet the needs of the small family and the city dweller whose storage space is limited. Heads that weigh but two or three pounds are pre- ferred. One of the latest varieties is a real red-head cabbage of far deeper color, and another that has grayish purple leaves, Top to Bottom, Finishing One of the Walls, Hoisting It, and View of Completed House

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636 POPULAR MECHANICS WORLD’S BIGGEST LENS TO SOLVE MARS RIDDLE In a few years, a hug telescope, ten times powerful as any now i: use, may give an answe to the question whethe: Mars is inhabited and may solve other celestia mysteries. According t Prof. G. W. Ritchey, wh has been working on th: Dipping the Blocks in the Special Preparation That Helps Deaden Sound; Fitting Together, and Section of Finished Floor BLOCK FLOOR WITHOUT NAILS DEADENS SOUND Handsome wood floors, in fabricated blocks put together with pegs instead of nails and laid in a special preparation that helps deaden sound, have been introduced to effect savings in construction costs and time. The blocks can be placed on top of cement or subfloors of wood, attractive patterns may be developed, and, when properly installed, they eliminate squeak- ing and sagging. The pieces are dipped in a special liquid preparation which is heated and quickly cools. SAFETY LIGHT IN ELECTRIC PLUG TO HELP PREVENT FIRES Intended to save current and pre- vent fires caused by leaving appliances connected too long, a safety light has been added to the plug. It shows through a small opening when the switch is on, giv- ing a warning that the toaster, iron or other appliance is still connected. instrument for four year it will make plainly visibl the features of the land scape on Mars and, al though the figures of an persons there cannot bi their habitation should be discernible, lh: The telescope is to be of the re lector type and will be mounted on th: edge of the Grand Canvon in Arizona, ac cording to present plans. seen, declares. CORKS ARE EASILY LIFTED OUT WITHOUT TURNING caps or and small, are easily removed with a small unit recently introduced. It has pins for taking out corks or milk-bot- tle caps, is simple Bottle corks, large to operate and saves purchasing extra tools BRIGHT BINDINGS ON OLD BOOKS ATTRACT MORE READERS Library workers have found that little- read books often become more popular when dull-colored or soiled covers are re placed with brighter bindings. A special cover, coated with a material similar to a chemical finish used on automobiles, has been introduced. It is waterproof, finger marks and stains may easily be washed off, and it can be obtained in a wide variety of colors and designs.

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POPULAR YELLING HELPS CURE DIZZINESS IN HIGH-SPEED FLYING \ttacks of sudden dizziness while flying an airplane can sometimes be relieved giving a loud high-pitched yell, emit- as little breath as possible, naval ht surgeons declare. This forces blood to the smaller veins in the region of An aerial “jolt” often causes the ood to leave the veins temporarily, re- ilting in a sensation of dizziness. Dur- certain maneuvers at high speeds, a ecrease in the blood supply to the brain iv cause fainting, although the effects the individual. Yelling con- racts the abdominal muscles, the dia- hragm and chest muscles, and the pres- ure forces more blood toward the head. e head. irv. with GAS MASK PROTECTS DRIVER OF COTTON DUSTER To rid cotton plants of the destructive boll weevil, a poison-gas treatment has developed. The fumes are made from a special powder in a fire box on the which is driven the field. he heavy smoke settles and is confined a relatively small space within a canvas hield close to the plants where it kills the eevils. Enough powder to cover a field f twenty acres is carried in the hopper, peen machine, over nd the cost is about twenty cents an acre. he driver is protected by a gas mask. he mules or horses that pull the machine re out of the range of the gas. Treating Cotton Plants with Poison Gas to Kill Boll Weevil; Driver Is Protected by Mask MECHANICS 637 “Lighthouse Helmet” for Policemen on Foggy Days and Nights; Batteries Are Worn on Belt FOG LAMP FOR TRAFFIC POLICE PROMOTES SAFETY Traffic policemen in England have been equipped with head lamps, somewhat like those carried by miners, to aid them in guiding pedestrians and cars on foggy days and at night. The lights are supplied with electric batteries at- tached to the current belt Irom WAVES IN ASPHALT PAVEMENT REMOVED WITH SHAVER lo smooth the waves that form in as phalt pavements, a unit somewhat like a road grader has been introduced. It ha that shave off the irregularities, often caused by the heat of the sun. specially designed blades A light covering of thin ce ment is pressed into the pavement with a small roller, to complete the repair @ Those wishing further information on anything described in the editorial pages Bureau of Mechanics Maga can obtain it by addressing Information, Popular zine, Chicago.

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S Siia)/ays to avoid Added Amusement and Instruc- tion Are Afforded Children in This Combination Desk, Game Rack and Table Set; as Illus- trated, the Top with Holders for Games and Books, Folds Down to Become the Table Top Many Uses Are Found for Sponge-Rubber Dish Washer, Be- low, Especially Fitted for Clean- ing Interior of Bottles and Jars; It Has Extension Handle with Pan Scraper on One End These Perforated Aluminum Plates Form Air Space between the Food and Cooking Utensil So That Contents cf Dish Will Not Burn on Gas, Coal or Electric Stove; They Also May Be Used under Hot Dishes on Table Clothespins Are Not Needed with | This Twisted Line, Which Is | Easily Spread, to Admit Gar- ments, and Springs Back of Itself — to Hold Them without Tearing

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Decorative Window- Sill Shelves for the Flowerpots; Require No Screws, Protect the Sill and Keep Pots from Falling Cleanliness and Convenience Are Features of This Mop That Unwinds Fresh, Clean Fabric from a Roll at the Center and Supplies Oil or Water from Tank at the Top Baby Harness of Soft White Webbing, Easily Laundered, Keeps the Infant Securely in His Crib, Yet Permits Him to Roll Around in Comfort; It Is Especially Suited for Use When Traveling in Railroad Cars b or Steamers and Requires To Protect Hands and Fingers but Little Space While Sealing or Removing Jar Caps; a Rubber Wrench with Molded Threads Inside to Afford ——— a Firm Grip

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640 MINER SCREENS BEACH SANDS FOR LOST VALUABLES Screening the Sands at Swimming Beach in Hunt for Articles Lost by Bathers Articles of jewelry, coins and other val- uables lost by bathers at Venice, Calif., are often found by a former prospector who has been awarded the contract of keeping debris off the beach. He carefully screens the sands in a rocker sieve, which sepa- rates any lost objects from the material, and uses a hand scraper, specially made for the purpose, to collect the sand. ELECTRIC ROADSTER FOR TWO GOES WHERE AUTO WON’T POPULAR MECHANICS age to the grass. It develops a speed oi twelve miles an hour, is fully equipped with emergency brake, parking lock, light and other units common to the regula automobile, and is especially convenien for short trips when use of the larger ca: involves difficulties because it cannot- al ways be driven all the way to the destina tion. A smaller electric roadster is de signed for youngsters. JUNE WEATHER ALL THE YEAR IN BIG BANK BUILDING Electrical ice boxes will be hooked up with steam heat, air washers, air filter and giant ventilating fans to manufacture comfortable weather at all seasons of the vear in the Union Trust bank building now under construction in Detroit. On a hot day, the tenant will simply open a reg ister in his office, and clean, cool air, at a temperature of seventy degrees or les: will pour forth. Each room has its ow: air control. The building’s refrigerating plant, if used for ice making, would freeze 700 tons a day. The ventilating fans will blow 440,000 cubic feet or 33,000 pound of air per minute. EXPLORE MYSTERIES OF EELS IN TWO YEARS’ CRUISE In order to learn more about the habits of eels, Prof. Johannes Schmidt, of thx university of Copenhagen, has embarked on a two years’ cruise. He will endeavo: to solve the riddle of the spawning grounds and migration routes of the Pa cific eels as he did for the Atlantic species As far as it is now known, the story of the eel is one of the Operated from automobile storage batteries, anelectric | roadster seating | two persons has | many uses in sport and business, for it can be turned around in a narrow driveway, may be parked almost any- where and can be driven across the lawn without dam- Electric Roadster Saves Time to Golf Links; It Can Make Twelve Miles an Hour most interesting in natural history. For ages they were shrouded in mys tery. Young eels were never seen de scending a river, but old ones never went any other way. No one had seen an eel’s egg. The young ones came up from the sea, the old ones went down

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POPULAR MECHANICS the sea, but what happened ere remained a mystery for cen- ries. For seventeen years, Prof -hmidt labored on the riddle. e discovered that the young eels me up out of the sea and per- tently ascend the rivers. They ve and feed in fresh water for veral years. When full-grown, ey go down to the sea, swim ‘ross the width of the orth Atlantic to an area north- t and east of the West Indies, here they fertilize their eggs and The young eel larve are ii-shaped, flat,thin and as trans- How they find heir way back across the ocean thout guides, still is a mystery. ’ne of the strangest parts of the tory is that, though American nd European eels breed in the ame general region of the ocean, their respective young always inerringly find their way back, each kind to its own proper side of the Atlantic, a ligration which is said to take them three whole rent as glass. ears more or less. COOLER PLACED IN MILK CAN SIMPLIFIES HANDLING Mill < is quickly cooled without pouring it from the can by means of a revolving coil placed inside the container and connected to a faucet through a short length of hose. A small tur- bine, actuated by the water, turns the coil, which agitates the milk and so hastens the cooling process. Water circulates through the coil, emerges through small holes in the lid and then flows own on the outside of the can. The unit so constructed that no water can get into the milk. When the content is cooled sufficiently, the apparatus is easily lifted out and placed in another can

Operating the Saw, and as It Is Carried in the Fold- 641

Case PORTABLE ELECTRIC SAW IN KIT CARRIED LIKE BAGGAGE uilt ina sturdy frame that may be car- ried like a suitcase, a portable electric saw does rip or crosscut work, mitering, groov- ing and beveling, and will work lumber up to three inches in thickness. The quarter- horsepower motor may be used for driving other tools. and there is a long extension cord for power cot nection. DIRECTORY IN OUTDOOR BOOTH SERVES PUBLIC FREE directories are booths at City placed in outdoor filling stations an venient localities by a

Cleveland publisher. The attached to the door of the booth, opens like an old- fashioned desk, leaving the direc- book is which tory in convenient position for refer- ence, and may be tightly closed to protect the ume from rain, vol-

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(jrowin g Wings | for the AN AIR-corps primary training plane Ld skimmed gracefully in front of the operations office at Brooks field, Texas. It hesitated, wavered for an instant and settled to the ground in a three-point landing. The instructor in the front cock- pit raised his goggles to his forehead and turned around in his seat. “You're pretty hot this morning; skid- ding a bit on your right banks, but you'll do.” “Think you can take ’er around yourself without cracking up?” he asked. He climbed leisurely out. “All right, sir,” the young pilot laughed He was feeling a bit nervous by this time The instructor lighted a cigaret and the: walked away. His nonchalance gave the student more confidence in himself. Yet he was somewhat doubtful. He wished the instructor would “stick around.” Hy, thought: “What if I do fall into a spin Well, here’s one flying cadet who’s going to fly high!” He eased the throttle open. The mo “Yes, sir,” the pupil replied confidently; “shall I take off?” “Sure; and listen! The air’s pretty rough and you'll have to watch your turns; remember to keep plenty of speed. Don't try to turn until you have three or four hundred feet altitude. landing in a Come in for a straight glide—no funny Don’t level off too high; remember your tendency. business yet. Now, if you'll remember everything I’ve taught you, you won't have any trouble, but watch your step. You know how to get out of a spin, but if you fall into one, I'll break your neck, when [ get to you!” He added the last tence with a smile, sen- In Less Than Five Minutes He Will Be an Aviator; the Instructor Is Giving Final Orders to a Brooks Field Cadet Before He Takes Off on His First Solo Flight 642

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Testing Future Flyers on the Ground; the Pilot of the Ruggles Orientator Has Put the Student in ~ wyy: an Upside Down Position and Is Watching His Efforts to Right the “Ship” or ceased the plop-plop of idling and rose to a mighty The ship quivered, moved slowly out across the field and The controls felt light to his touch, the plane was almost ready to come off the ground. Cr-r-r-r-m-m-m! he heard the roar of The sound A shadow litted overhead and he caught a glimpse f a yellow-winged plane flashing past vithin ten feet of his upper wing! The man in the front cockpit was shaking his “What have I done ?”’ the cadet muttered. The ship steadily, roar, picked up speed, inother motor above his own. me to him as an angry growl. fist angrily. vrong now was in the air, climbing straight to its The ground seemed far away, and there came the thought that he was far removed The altimeter registered 800 feet; he was high enough. He banked over, remembering the times had said: “Gosh, Get that stick and rudder action holding course, trom every living being. his instructor you're dumb! together: get some coordination; want t spin us in?’ Easy now—that’s bette take off a little 1 followed instructions exactly and brought the ship ore rudder.” He around and headed back for a landing. 7 The time for landing had come, ane e viewed it with some misgivings. He sud denly found that he was tense: that he gripped the controls with taut muscle his legs ached from shoving on the rud der; there was cold perspiration on hands. No excuse for that: mavbe he \ scared. He drew a deep breath to quiet the pounding of his heart, idled the moto: and nosed the plane doy Nn. He listened to the whine of the wires and pulled the come in too fast, that hard to land. He instructions: “When vou nose up—mustnt was what made it thought of is j bounce, don’t wait until the ship has killed its speed; vou do that up. Gun’er right now!” He gripped the throttle tighter. “Don’t level off too high; that’s vour trouble,” he remembered 643

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644 POPULAR Wh-u-m-p! There a violent jolt. He slammed the throttle open and let the ship pick up speed again. Well, he had bounced, but he hadn't cracked up. He was still in- Was wondered if his landing geat tact; what if a wheel had the He the landing gear down tl on t eround, decided had He tightened his lips into a grim, straight line given way under > looked back over his < WmWh eTOU id. strain! shoulder at There was no eve he so he nothing broken. ‘and started around again. The second time he came in slower. [There was an agon heel of waiting just before S touched. d his w He juggled his stick a little and ease the plane down. The vheels rolled. He taxied back to where he instructor was standing, still puffing on a cigaret. Not bad,” the latter l “except you ilmost rt killed That ship almost landed on top of you; you know enough You } to look around before you take off. pull a stunt like that again and I'll wash you out!” “I won't, sir,” the cadet replied. He is

MECHANICS one of nearly 700 young men between t! ages of twenty and twenty-seven who a: nually begin flying training in the art air corps. His reactions, his fears and w r.es on his first solo flight are no differe from those experienced by any man wl flies alone for the first time. There probably more emotions packed into t five minutes of the first solo than other five minutes of a man’s entire life. The men to whom the army offers fly training are usually college graduates « have had two or three years of univer work; they are physically almost perfect they are without mental or moral flaw. short, they are the pick of the young me to are offered this training at throughout the who wish le to fly. They W h country cost atever; the army pays for eve: thing c nected with it. ' on of the course is one ye | oht months this of time are spent at o of the primary schools, Brooks field at S Antonio, or March field, at’ Riversid Calif. During the first eight mont! students learn to fly; in the remaini:

The Complex Coordinator, at Brooks Field Primary Training School, Tests the Ability of Flying Candidates to Make Their Hands and Feet Respond to Eye and Brain

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POPULAR MECHANICS 64 ui This Is the Reaction-Time Testing Machine, Which Measures the Interval It Takes the Hand to Respond to a Message Delivered through the Eye to the Cadet’s Brain nths they learn to use airplanes as mili- weapons. They learn to fire machine ns from the air, to drop bombs accu- tely, to master any of the difficult prob- ms Which arise in military flying, Flying is a misunderstood profession. A few days ago a man asked about the advis- ility of sending his boy to the air-corps l ools. 7 Benny is a fine boy,” he said; ed learn that stuff in a hurry. He's ot brains, .nd he’ll work hard; I'd rather ive him learn to fly in the army than nvwhere else.” “He might not get through if you send m to the army: he might be washed ut,” was the reply. “Benny? Don’t worry; he'll pass any- hing they have down there. That boy of ne has brains.” That seems to be the prevailing idea. a young man applies himself,.the lay- in thinks, he'll have no more trouble in if he were going to college—a com- nation of hard work, sand and persist- nee. But unfortunately that idea is er- meous. It seems never to occur to most iymen that there may perhaps be some- thing of an art connected with flying an airplane. But there is an art, a very dif- ficult art, and one which is as lacking in some students as the art of violin playing to the average bricklayer. The completion of the year of flying training in the air corps is to no individual at all certain. There is a matter of “in- herent flying ability,” just as in athletics there is an inborn ability in some indi- viduals which is more or less lacking in others. And for that reason, of each new class at the air-corps primary schools, perhaps only one of every five students will eventually become a skillful pilot, and graduate and receive his wings. In military flying a man must be able to fly. He must daily perform maneuvers in the air which in flying would be unnecessary and extremely dan- per- five or six commercial gerous. So, in the same way that haps only one person of any might be trained to virtuosity as a piano player, only the same average can be trained sufficiently to be safe in military flving And it makes no difference that a man works hard. ] ] He may actually slave to learn, yet be entirely incapable of over- coming his inherent lack of ability. To overcome some of the waste and de- lay in money and time, and to avoid as much as possible the disappointment cus- who fail to pass the course, the corps has devised several va- tomary to those ried and interesting tests by which the rel- ative degree of ability of each new student is determined. Flight surgeons and scien- tists have been working along these lines for several years, and are now able to tell with a fair degree of certainty whether or not a student will be able eventually to fly

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646 POPULAR MECHANICS - eS ) i) J ey fii VE : a’ ‘> The first four month at the primary schools are spent on flying instruc tions of an elementary nature. The student |; taught the ABC’s of fly ing in a small, rather low powered ship. He is ex- pected, of course, to get the plane up and get it down without wrecking it, but quite often he flie counter to expectation During the fourth mont he is taught acrobatic and in these maneuver he learns to be comfort able in any position « the plane, whether hang ing upside down by h belt or flying level. In the last four mont! school Mechanics Working on a Curtiss Observation Plane; This Type Has a High Speed of 140 Miles an Hour and this before the student has been near an airplane. One of these tests is performed with the aid of the Ruggles orientator. This is a device resembling the cockpit and fusel- age of a modern airplane. The cockpit is equipped with controls which function exactly as do the controls of an airplane in flight. With the student in the cockpit of the apparatus, an operator on the ground handles another set of controls, and is able to put the fuselage in any de- sired position, regardless of the wishes of the student. The length of time the stu- dent requires to recover from a given po- sition, such as upside down, furnishes an index to his reaction time, and hence to his native flying ability. There are other, and more involved, tests. In one of these, the student is seated before a board containing a num- ber of red, green and white lights. He has before him, in the same relative position as in an airplane, a set of controls, the move- ment of which will turn on certain lights. The problem is to line up certain lights on a given row. If the student is violent in his movement of the controls, that error shows immediately on a paper graph. Similarly, any and every mistake he makes is shown. at the primary the student is given worl with a service-type plane He undergoes a refining process, a devel oping of his skill to the point from whic! he can safely take up the problems to b: encountered in military flying He lear: to fly the plane by feel. No longer mu he thrust his head out of one side or the other to feel the wind blast for a side slip ora skid. The student of flying at the primar school graduates to the advanced schoo! with a new confidence in this ability. He is not overconfident to the point of cock iness, yet he has a healthy state of mind which brooks no fear of flying. At the advanced school, at Kelly field, he has four branches of aviation from which to choose in preparing to be a mil itary aviator. He has studied each at length and, depending upon his tempera ment, may choose either pursuit, observa tion, attack or bombardment. In pursuit, he will be able to satisfy his fighting instinct. Pursuit is contemplated for the sole purpose of combat; the ships have been designed with that in view; the plane reminds one of a huge, formidable hornet. The observation pilot and his observer, on the other hand, are not supposed to fight. Theirs is a peaceful mission—if possible; but on occasion they are capable

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POPULAR MECHANICS 647 Filling the Gas and Oil Tanks of a Two-Engined Martin Bomber, One of the Biggest Planes the Cadets Learn to Fly; the Cockpit in the Nose Is the Forward Machine-Gun Nest just as stubborn a resistance against ttack as the “pursuiter.” lhe students devoted to attack aviation re popularly termed the “Suicide Squad.” \ttack planes are those which sneak upon e enemy unawares, that dive over a hill d spray the enemy infantry with lead and are gone as suddenly as ey come. They fly just off the tree tops, tv feet or less, and if a motor fails when he plane is over rough country, there is » possible way in which the pilot can oid a crash, Bombardment aviation is perhaps less pectacular than the other three branches. operates at great altitudes and, usually drops the “pills” upon enemy ammunition factories, far to But while it bombs, citi, ns and he rear of the front lines. av lack in appeal the imagination, has dangers, too. ere isenemy pur- iit to think about, occasionally nti-aircraft fire, also the hought: “Ifa bul- et should hit one ‘f these bombs, e’'d be blown out of the sky.” ombardment } here is Rear View of Boat Showing Outlets through Which Water Is Forced to Propel the Craft It requires a year to develop the student’s wings, a vear of constant, grueling work. But that man, it molds his mind to new wavs of thinking. And as time goes on, and he flies day after day, vear changes a he discovers a more complete mastery of will. His sphere becomes the air; seated behind a his airplane, his nerves, his roaring motor, with the wind whipping back into his face, he is in his element. The plane becomes a part of him, some- thing to handle as subconsciously as one walks or talks or eats. BOAT PROPELLED BY PUMPS DEVELOPS HIGH SPEED As a substitute for the usual propeller arrangement, a_ western has rigged a boat which inventor is run by pumping water into two cy- lindrical pipes and discharging it at The rudder is also elimi- nated, high pressure. steering be- ing accomplished by shutting the water off in pipes other is left running to turn the boat. one of the while the

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648 POPULAR PUSH BUTTON TO FIT ANY IN. STOCK Adjusting the Window Brush; Close View of the Stick and Bristles, and Cleaner in Operation with Cloth SAFETY BRUSH CLEANS WINDOW FROM THE INSIDE Window panes are cleaned on the out- side from the interior with a safety brush now on the market. It is attached within the sash groove and extends the full width of the window, the bristles resting against the glass. A cloth, dipped in warm water, with ammonia or kerosene added if soot has gathered on the panes, is placed on the brush and by raising and lowering the window, a thorough cleaning results. The unit may be used for either the upper or the lower sash and is furnished in two sizes, for windows of varying width. NORTHERN LIGHTS HELP RADIO IN ALASKA, TESTS SHOW While the northern lights often seri- ously interfere with radio reception and sending in various parts of the world, F. P. Ulrich, magnetic observer of the coast and geodetic survey, reports that, at Sitka, Alaska, where he has been making tests for five years, they do not cause such difficulties. In fact, he says, “good radio reception is very much more apt to occur than poor reception during a bright or MECHANICS faint aurora.” He declares, as a result of his findings, that the condition of the earth’s magnetic field is no index of the quality of radio reception. The question remains one of the greatest scientific mys teries. For years, scientists have bee: making careful observations, recording the hourly and daily variations in the earth’ magnetic forces at widely scattered ob servatories from Samoa to Honolulu anid in Alaska. Efforts are also made to con nect the phenomena with such occur rences as earthquakes and sunspots in order to gather more knowledge of these mysterious forces, —_—_—_—_—e- MOVING A FOREST More than ninety trees, some of them over two feet in diameter at the base and from forty to fifty feet high, have been transplanted from a natural woodland to an eastern estate. The work was done in the winter when the earth was frozen in a ball around the roots. Holes to receive the trees were dug a foot larger than th: root clump, the space between being filled with fresh earth and the roots kept undis turbed. Winter is the best time for such work as the sap is dormant. SIPHON AND FILTER COMBINED RUNS AUTOMATICALLY For filling bottles, removing cream, draining goldfish bowls, and many other purposes, a siphon starts and stops auto- matically, can be run at different speeds or continuously and will not splash or foam, the manu- facturers declare. It eliminates the unsanitary suction methods usually employed. Extra attachments are provided so that it can be used for washing dishes, or as a grease gun. _ The siphon filters as it fills and the tubing is equipped with a spring clip to prevent kinking. —— } i |

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Build This Compact B- Eliminator By R.C. MORTON Te B-ELIMINATOR describedinthis the lamp cord so that the instrument can article is not only compact, but eco- be turned on and off. The top and front smical to build and highly efficient in op- consist of bakelite panels, “46 by 7% by ition, and will supply ample voltage for 8 in. and “46 by 4% by 8 in. in dimensions, e operation of any standard receiver respectively. All holes for mounting the hich may employ either a 112 or 171 various instruments are located by plac- wer tube in the last stage. ing these in position and marking the Begin construction with the box. Four points for drilling with a pointed tool. ieces of hardwood, 1 in. square and 44% +#The back panel is ‘46 by 4% by 8 in., and long, or eight brass corner pieces, asin the two side panels are “6 by 4% by 67¢ e model illustrated, may be used as_ in. Bakelite may be used if desired for races. These brass corners can be pur-_ these panels, too, but veneered wood was ased at most hardware stores for five used in the model described. t © B+ MAX. R, ~~ O B+135 = © B+ 90 85 MILL é RECT R. 3 TUBE é 0 B+ DET. | Ce [Cr Cg | \ - NDENS Cg | ‘6 ote eg 1000 VOLT CONDE ~aeed END 2 400 4 ° CONDENSER BLOCK 4 * ad ” “ (SEE MATERIAL LIST) j R,- 2000-OHM RESISTANCE WITH CENTER my SEE MATERIAL R2- 1000-OHM VARIABLE RESISTANCE ul NOTE - CASES ON TRANSFORMER, CHOKE AND CONDENSER BLOCKS GROUNDED TO B-NEG. cents each and also the rubber feet. If the eliminator is not to be used with a Inset, Front of the - oa ie , . Instrument; Above, Rear relay, it is well to incorporate a switch in View and Diagram 649

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650 POPULAR MECHANICS NO-VOLT A.C. LINE SEC. 7.5 -V. a ALL CONDENSER, CHOKE AND TRANSFORMER CASES GROUNDED TO O TERMINAL ON CONDENSER BLOCK CONNECTIONS FOR VOLTAGE REGULAR TUBE B+ 180 TRANSFORMER FILTER CHOKE SECONDARY B+135 B+ 90 B+ DET. ~~ B-NEG GND R3- 980 TO 1000 OHMS. NOTE - IF THE ELIMINATOR IS TO BE 4 1 2 im A mw (9X) Tie L =I ee 0 4 | 1 MFD. MFD. MFD. ese ¢ 400-VOLTS D.C.——> 3 by - - — BUFFER COND. | NL GROUND To // MFD MFD| _MFD. | MFD. r , Zs NOT CONNECTED’| conp. | 2 BLOCK / t | {Fp | 4g : Wry ' - i 2000 - OHM i RESISTOR | VAR. RESISTOR / 10,000 - OHM : re é O C O : O GND ~B +B +B +B +B DET. 9390 135 180 USED ON A SET DRAWING OVER 50 MILLIAMPERES THE RESISTANCE R3 MAY BE OMITTED AND + OF THE SOCKET CONNECTED DIRECTLY TO THE 90+ BINDING POST Simplified Wiring Diagram, and, Right, Photo of Bot- tom, Showing the Simple and Compact Construction The transformer and filter choke are now mounted on the top panel and the tube socket directly in front of the trans- former. The space in front of the filter choke is purposely left vacant in case the guilder wishes to add a voltage-regulator tube. Next remove the enamel from the side of the condenser block with a file or emery cloth, so as to make contact with the metal case and strap which holds it in position. The strap is 334 in. wide and 5 in. long, its ends being bent up over the sides of the condenser shown in photo on this page, and drilled to take two threaded brass rods, 4 in. long. The rods may be of the machine-screw type and are inserted through holes drilled in the top panel between the transformer and filter choke at front and rear. The sup- porting strap is then held in place by means of two nuts threaded on the rods. block, as a file remove the enamel o Now with the mounting lugs of the two-unit buffer condenser, which is then mounted as in dicated in the diagram and screwed to the side of the box by means of two short brass machine screws. The ground con nection for the shell of this condenser is taken from one of the mounting lugs and connected to the center terminal. A short wire is also used to ground the cases of the transformer, filter choke and large condenser block. This connection is made, on the underside of the top panel, to the mounting screws and rod at front. The wire is then soldered to terminal O on the condenser block, which is grounded to negative B To avoid confusion, these grounding connections are not shown in the diagram Place soldering lugs on all the trans-

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POPULAR MECHANICS ormer and filter-choke terminals, taps 2 nd 3 on the filter choke being joined by iIdering the lugs together. Use heavy ubber-covered flexible stranded wire for e circuit and run the leads down from he instruments mounted on the top inel through holes drilled at convenient Check all wiring with the diagram » make sure no mistakes have been made; hen assemble the side of the box and ehten the screws. [he instrument is now ready for use. sert the rectifier tube in the socket and smnect the eliminator to the set. Before i on the 110-volt 60-cycle house- rhting supply, place a 1-mfd. filter con- enser in series with the ground lead from he receiver. ints. 7Q ° In order to do this, disconnect the ground ire from the receiver and connect it to ne side of the 1-mfd. condenser, then run wire from the other side of the con- lenser to the ground post on the set. The round post on the eliminator is ected as shown in sketch. con- The condenser series with the ground lead to the set necessary where the 110-volt line is rounded outside the house, in which case the condenser will prevent any damage to the receiver. Turn on the set before switching on the eliminator and always turn off the eliminator before shutting off the set. A relay can be employed for this purpose, enabling the operator to control the en- tire installation with the set switch. The complete eliminator will cost about $38.50, the parts used are all high-grade, nsuring long service and maximum re- ults. If the builder wishes to add a volt- age-regulator tube, all that 1s necessary is to provide the additional tube and socket at an expense of about $6.50. The con- nections for this tube are shown in the diagram at the upper right on page 650. The schematic diagram on page 649 is given for those who prefer it to the sim- plified type. A material list specifying the make and cost of each item used in the construction of the eliminator will be mailed free to any address. A large blueprint of all wir- ing diagrams may be obtained from Pop- ular Mechanics radio department, 200 E. Ontario st., Chicago, for 25 cents to cover cost and packing. 651 Dynamic Speaker Is Operated from Light Socket Electrodynamic cone speakers are rap- idly gaining popularity with those who to realize the full wish possibilities of Left, Console Unit Showing Rectifier Element; Right, Unit Housed in Gothic-Type Cabinet power amplification. The free-edge cone unit is of the usual type, but the loud- speaker unit operates on a different prin- ciple from that applied in the permanent- magnet type. A large field coil is excited by an external source of d.c. in order to produce the necessary magnetic force. A moving coil is suspended in the field of this coil and is fastened directly to the The drive is ap- plied directly to the cone in speakers of this type and trou- bles, which are a frequent cause of dis- tortion in other types. There are several other advantages that make this type of speaker especially adapted for use with power amplification. small free-edge cone. eliminates drive-rod Novel Loud-Speaker Unit A novel loud speaker, which utilizes as a diaphragm any sur- face capable of vibration, has re- cently made its appearance on the market. It may be fas- tened to the wallofaroom, the top of a table, or the elass in a win- dow as shown in the illustra vibrating tip pressed against the used as the diaphragm. It tion, the being surface is claimed to give excellent rendition of music with any receiver capable of operating a speaker.

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POPULAR Left, Receiving Lamp; Right, Photo-Electric Cell Employed in the Transmitter New Parts for Television Experimenters The demand for reliable parts for use in television experiments has resulted in sev- eral new and efficient types of photo-elec- tric cells and neon lamps, as well as scan- ning disks and other necessary apparatus. The special receiving lamp shown in the photo at the left is simple in construc- tion and operation. The straight-sided, clear-glass bulb contains two flat metal plates placed parallel and quite close to- gether in an atmosphere of neon. If a voltage greater than 220 is impressed on the plates, the negative one glows witha vivid pink light. The ionized gas in the tube results in increased or decreased brillianecy with the slightest change in cur- rent intensity due to the amplified signals. It is this varying light, in conjunction with holes in the revolving scanning disk of the television apparatus, which weaves a pattern of light dots into a living image. The device is employed in place of the usual loud speaker in the output of a power tube. The photo-electric cell shown at the right is an improved device for translating light variations into varying signal intensities; it is emploved in the transmitter in the conventional manner of photo-electric cells. MECHANICS Practical Hints for Set Builders The best radio results are obtained sim- ply by close attention to details. The re- ceiver can be no better than its compo- nents, and to slight any detail, whether it be an instrument, a feature of the work of assembly and wiring, or a phase of the op- eration, is to invite unsatisfactory oper- ation. Good material should be used throughout. One inferior part may render useless an otherwise good set. Switch for Comparing Speakers With the rapid improvement of speakers and amplifying devices there is a demand for some quick method of comparing the merits of various speakers or amplifiers. The switch shown consists of a bakelite turret, molded in the form of a hollow truncated cone. Around the base of this cone five pin jacks are mounted, all oi which are connected to one side of the in put lead, and which form one series of outlets to five speaker circuits. Directly above each of the jacks, five others are mounted in such a way as to allow the switch arm to make individual contact with the terminal of each one of them The switch arm may be turned so as to connect five different speakers if desired for comparative tests. The device is also handy for set owners who have wired their homes fo: speaker outlets in various rooms. They can arrange ,the cir- cuits so that it is possible to project the output from a set to any one of five speakers located in different rooms. Purpose of the Speaker Filter The speaker filter is designed primarily for the purpose of protecting the wiad- ings of the speaker when used in connec- tion with tubes requiring high plate volt- ages, such as the 171 and 210-types. The high plate current of the tubes may be sufficient to burn out the ordinary speaker unit; hence the filter is used to isolate the speaker from the heavy direct current but permits the a.c. sound-carrying current to reach the diaphragm. It will not improve

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POPULAR MECHANICS 653

e quality of reproduction except here the a.c. impulses are greatly plified. If low power is used, ese devices sometimes cause a arp drop in volume and greatly ipair the tone quality.

Better Reproduction The filter shown in Fig. 1 is de- igned to eliminate extraneous oises and consists of a bank of \w-capacity fixed condensers »nnected across the loud speaker. \ switch, of the tapped type com- only used for inductances, may mounted on a small board or inel and the condensers ar- inged for short connections. The from left to rht, should be of the following ilues: .001, .005, .01, .05 and .1 fd. The greater the capacity in xed condensers,

he speaker circuit, the better the elimination of the higher extra eous frequencies. Fig. 2 shows a varia- mn, the degree of filtering being con- trolled by the variable resistance. In Fig. 3 the filter is designed not only to cut off he high-frequency noises, but also to compensate for peaked amplifiers and re- roducers. As in Fig, 2, the degree of ltering is controlled by the variable re- istance. Using the given constants, the Iter will cut audio frequencies round 3,000 cycles most of all, and dimin- h higher frequencies somewhat. _ << a. a in TO | To RECEIVER : . SPEAKER down

Front View Showing Portable Receiver Ready for Use; Back Opened Showing Arrangement of Tubes and Batteries

Fic.| —lL.02 MFD r TO TO R = _0-50,000 ECEIVER =] gates SPEAKER = FiG.2 }p-0l MFD iy on oe EEE TE ee mn - 02 MFD. 1 02 MFD TO A To RECEIVER ee SPEAKER 50.000 OHM

Below, Portable Receiver Is Equipped with Screen-Grid Tube A portable radio set employing a screen- grid tube and four tubes of the 199-type is now available. It is so compact that it may be taken anywhere as easily as your luggage. Programs may be enjoyed from distant stations with this set because the screen-grid tube is many times more pow- erful than the ordinary tube, yet requires only .132 amp. fila ment volts. Therefore such a tube is ideal for portable sets where dry cells must be used for the A-battery supply. ume and fidelity of and operates on 3.3 The vol- tone are surprising: the loop antenna is inclosed in a frame in the hinged cover and need not be de- tached. Binding posts are provided for external antenna and ground connections when extra-loud on distant reproduction is desired The volume, when so connected, is equal to that of the aver When onlv 30 stations. age stationary, five or six-tube set. fully equipped the set pounds, and is not as large as the usual Gladstone bag. weighs cover is hinged to give easy access to the batteries. Three No. 6 dry cells furnish the A-supply and the B-battery consists of sized 45-volt units. 1e@ real two medium-

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— ] bl ddOMLN TT AAME POS Asi PART I "RHE CHEST desk or vargueno, a ch ished article of furniture in the homes of old Spain, is a cabinet easily adapted to contain a complete modern radio set. It harmonizes delightfully with the Span- ish furniture now in vogue. The cabinet illustrated was designed to suit the wood- working skill of the average home me- chanic, as well as to economize in the needed amount of rather expensive wal- nut. It will accommodate a panel from 18 to 34 in. in length, provided the con- trols are grouped in the 18-in. center sec- ion. ° The over-all dimensions are: height, 52 in.; depth, 17 in., and width, 36 in. The two center spindles of the stand ends, which carry the stretcher ends, are + t 654 pushed against the spindles for direct com Smooth the work at fairly high No. vith No. 00. Stop the lathe, and finish by rubbing, with the grain, with No, % grit parison, speed with Paint the turned parts with light-oak filler, diluted with gasoline. When this has dull, wipe off across dried the grain with a cloth. The end cor- ners of the square parts are slightly rounded, and a skilled lathe man can turn them. The pounding of the flying cor- ners, however, makes this dif- ficult, particu- stock short as length, but 1 in. to end makes the turning easier. Cen- ter the piece accurately, so as to get the full diameter called for. certain way to duplicate accuratel) is to cut a thin wood pattern, which can be 1 sandpa CENTER SPINDLE 2 REQUIRED may 2 ft. 2% in. in detailed at left in Fig. 1. The 3 by rough cut as =e 3-in. be spare on each > The most per, and then c Fic.| i ec: tea z 3 1] = 8 | Le as | 2 + one © ft] ] / il mS | 4 265 145° em ‘Riz SS ie a 4 >” i6~ a» WZ STRETCHER SPINDLE 5 REQUIRED

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POPULAR MECHANICS : 26)" CORNER SPINOLE, 4REQUIRED Left, Scribing the Centers of the Square Sections on the Center Spindles; Upper Right, End Elevation, Showing Rails, Corner and Center Spindles larly if a good-sized skew chisel is not at hand, and the home mechanic may find it easier to trim them after squaring up, us- ing a narrow chisel. When the dowels of a center spindle are turned, remove the piece from the lathe 1 to length. blocking the square sections if necessary, ind with dividers set to the center, scribe lines on two opposite sides the flat parts. From these base lines, draw lines establishing opposite sides and reduce one Then aline one face testing by sighting balanced id saw Lay it on a bench, of section to squareness. of the other section, over a straightedve on corre- rr ree i -_ a ’ Wa; Moe ‘ ‘ UPPER Rai 7 “el H | ‘| stop/ rey | ba | he ' ii i 2! | I~ ' ” ; N | ” - 43 43 An J : ; wv ™ | | | | | ' Right, Rounding the Corners; and finish sponding faces part. Lastly, round the corners to a ra dius of % in., and fill. The corner spin dles, shown in Fig. are turned from rough 2 by 2-in. stock. The upper rails are dimensioned in the end elevation at the right, Fig. 2 Cut 17-in. lengths of 3 by 3-in. pine or fir which, mill-surfaced on four sides, is about 214 in. veneering the net. Bore the dowel holes before sides Surface a piece of walnut, 234 in. wide, gauging the edges for a veneer thickness [ in. then Rip alternately from one edge the than of % and other. Veneers less

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656 Me in. thick can be cut in this way. The sawn sides, unless very rough, need not Cover them with glue, ap- ply glue to the sides of the rails and clamp together in one group, the edges of the veneers projecting evenly, the outer ones If hot glue is used, warm the wood and the out- be surfaced. being backed by heavy pine strips. side strips and rub the veneer to expel the air. On the whole, the home worker will probably have better luck with liquid glue, as it can de - worked more lei- surely and does not require so much equipment. al LIAM @ «Doo MATTING TOOL POPULAR MECHANICS the outline through ™%-in. squares, as shown in the same illustration. If a bandsaw is available, cut the rail ends with this, and the blocks removed may be used as cauls for clamping the ve neer. By hand, the easiest way is to make saw cuts to the lines, chipping out the waste and finally trimming smooth with a chisel. Fill the depressions with saw dust and glue, which will form a solid base for the veneer. Fic.3 | Upper Left, Photo Show ing Walnut Stock Clampe in Vise for Cutting the Veneers; Right, Alinins the Square Sections by Sighting over a Straight- ‘| he second coat of glue, to cover places where it has soaked below the surface, in- sures strength. edge Balanced on Corre sponding Faces; Below, Kerfing the Ogee Ends of the Lower Rails; In- set, Details of Stretcher Rails and Matting Tool for Finishing the Carved Groundwork on the Rails For the lower ° | rails, see Fig. 2. The cores, cut / 22 in. long from 3 by 4-in. stock, are bored in the upper edges to correspond with the mating upper rails. On the un- derside of the ends, nail ™%-in. strips for feet. Z For -the ogee EZ curves, make a cardboard tem- SECTION A-A plate by drawing

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POPULAR MECHANICS 657 | End Veneer | ped in Vise, Show- | e Method of Lacing eneer to the Curves G ing Below thing the Stretcher | Arches with a Half } File; Right, De- | f the Stop Blocks | e Carved Seashe!! | uments for the Stand | Upper Right, Shap | the Lower Rail Ends, | | ng Out the Waste | = nee eee —— Trimming Smooth ee nine with a Chisel | 4 iy } Che small vertical ” end venee it the t p oT the cu t can be held 1 pla hy t} e cla tT) ho ] iy the cut ed e nee? but the lo ‘ end eneel mt t he | 1ed Lite! tl irves af©re l¢ | ] ’ > : : oe r¢ og secures ) clamp leng é ot thre ra he top vene¢ n it on last. Whend , ¢h l; e ‘ ] to reve { rT | ' 1, drv while the the joints eers are being made. Glue on the side Fig. 3 dimensior the stret ers described for the upper rails, The upper is cut from 1 by 4 roug! ming them to the profile when dry. walnut, hand-surtaced to get the may it the curve veneers less than “6 1n. mum thicknes Cut to length and bor k and soak them in water. Glue in the four in. dowel holes in each end e while still wet, holding the upper Lay out the carvit ¢ and the arcl e noting ls with clamped blocks while lacing the that the centers of the latter are '% to the curves and using thin blocks to above the lower edge, to avoid the effect tribute the pressure, as shown in the of flatness. The lower edge of the carving pper left-hand photo in Fig. 4. Small is curved to a radius of 53 in.. centered 1 , . 4 " + , 2 o¢ . a4 edges, forced in here and there, will on the arch diameters and 23% 1 belo ten contrary places. Hold the ends the centers ith clamps improvised from pairs of Cut the arches with a kevhole saw icks held with bolts through the centers, Smooth them with a half-round file moved

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POPULAR from leit to right at right angles to the 1 sides, pushing forward with a twisting motion at the same time to get a shear Occasionally trim off the back ing cut. Sanding the Arches corners to prevent splinters from being raised. Use a sawed-out block for sand- paper backing. rhe lower rail is ™% in. shorter than the upper and bored with dowel holes in the upper edge to fit those in the upper rail. Most of the carving can be laid out with gauge and try-square. The curved centers are traced from a cardboard pat- tern. Outline the carving of both rails with a narrow chisel, held vertically be- tween the fingers and struck lightly with a mallet. Keep %e@ in. the lines. Trim the center to a flat ground, % in. may be pared to the inside deep, when the edges guide line Make a matting tool by filing a flat end on a large spike, across which two pairs of V gles to each other file With this ground, striking it light blows with a small the ends of the lower-rail line the and curving them back &% in. to shaped grooves are filed at right an- with a three-cornered tool, go over the carved hammer. Cut ornaments to with borders vertical bars, give the appearance of passing under. The depth at these points is “46 in. The are cut with four vertical strokes of a %-in. pyramidal center ornaments chisel, held beveled side in, the center then The hlossom ornaments on the upper rail con- bemg sloped from the four sides. sist ot four simple elliptical depressions. A \4-in. turning gouge is excellent for this part of the carving. MECHANICS urn the five spindles as dimensioned at right in Fig. 1, from 1l-in. stock. If flats appear, turn them to the back in assem bling, and they will not be seen. Fit the dowels loosely enough to the rails to pet mit trial assembling Assemble the end and set then in such a position that the rails will line with each other. before gluing uy frames, Test for squareness and allow the glue to dry. The stop blocks that hold the case place are detailed in Fig. 4. cleats are both glued and nailed to the The front with a carved seashell on each. Make paper pattern of the outline. With a coy ing saw cut out two blanks, to be shaps The d { i it) t The dove backs. blocks are enriche to the profile shown with a sharp chisel Draw the veins with a pencil. Cut the deeply with an eye tool and round off t! sections individually, smoothing well w The high spots may be rubbed off with sandpaper. Put a dab of glue the bloc} and press the shell in place with the sma a chisel. center of the carving and its end 1% in. from the top. When the stand ends are dry, mark the dowel-hole positions from the holes the stretcher, and bore them 1% in. dee] Assemble the stand by clamping as d rectly over the rail ends as possible, squar ing by holding a framing square again the stretcher tongue at the footrail. sighting across the To attach the stoy and NIOCKS, ore %4-in. 1o01es, vertically cer blocks, 1 A hol I] tered 34 in. from the ends of the upper rails. Saw out wedges 4 in. wide in front Drive the glued stop cleats in from above until the blocks project % in. below. (To Be Continued Next Month) Special Fuses Needed to Protect the A. C. Receiver The modern a.c. receiver should be pro- tected by small fuses in the supply line, a serious damage to the set before the 10 or 15-amp. house-line fuse would blow. A small standard fuse o about 2 amp. should always be includes as a part of the receiver installation and inserted in one side of the 110-volt line The use of such fuses will meet with the might occur approval of the fire-insurance underwrite and provide protection to the receiver and tubes at a cost of but a few cents.

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E. F. McDonald, the Arctic Ex- Demonstrating the New Automatic Radio eiver Which Is Operated by Pressing One of eries of Buttons That Automatically Tunes In Particular Station Desired; Left, an Interior View, Showing the Tuning Mechanism Profs. Knipp and Brown of Illinois University, with Their New Radio Tube, Requiring No B-Battery Facts and Fads for Radio Fans Above, Jerry Fasano, of New York City Build Loud Speakers in the Same Manner That a Violin, Man tolin r Guitar Is Made These Speakers Are Said to Reproduce the Clear Tones f Each Instrument in the Orchestra as Sent Out from Broadcasting Station the Builder Is a M 1S a In- strument Maker and Has Devoted Much of His Time Recently to Perfecting Loud Speakers of This Type; Left, Sergius P. Grace, of the Bell Telephone Labora tories, Demonstrating a New Electrical Machine for C verting Speech into Gib berish and Turning It Back to Normal at the Radio-Re ceiving End for the Pur pose of Transmitting Secret Telephone Messages

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660) POPULAR Modernizing Old Installations The radio installation of a or so ago, with the old-style gooseneck speaker and scattered yeal batteries around, is now Left, View, Showing Arrangement of Speaker and Batteries Front View with Set in Position; Right, Rear quite out of date, and justly so, both from a point of neatness and efficiency. The table housing the set is usually presentable and may be combirfed with a homemade console-type cabinet as shown. The cabinet is 44 in. high, 24 in. wide and 13 in. deep, the front and side panels being of three-ply taken from an old bed. The opening in the front panel may be cut with a coping saw or sharp knife and the edges neatly finished and stained. cabinet veneer wooden This opening is then backed with gold cloth in the manner of the usual console-speaker grill. The horn is placed just back of this opening, and the batteries In build- rules or may be arranged on either side. ing the cabinet, no set dimen- sions were followed. There is no need ofa hack, except a curtain to keep out the dust.—Irvin L, Oaks, Pleasant Hill, Ohio. Screen-Grid Tube Kinks wide-spread The screen-grid the many ex- perimenters to build sets employing them, but in the results were not what the builder expected, owing to his interest in new tubes encouraged some cases ignorance of their proper use and installa- tion. It must be remembered that in deal- ing with these tubes certain precautions must be followed if the extraordinary pos- sibilities of the tube are to be realized. MECHANICS The first is that of careful and complet shielding of each r.f. stage and the second correct design of the r.f. or coupling trans formers. There is nothing about the new tube that will eliminate undesirable inte: stage coupling in electromagnetic and elec- trostatic forms, and therefore shielding in a two-stage screen-grid amplifier must re ceive approximately the same attention a would be given to a four-stage r.f. ampli fier. To be at all effective, shielding must the metallic protectio: used to isolate each r.f. stage but also som: include not only means of preventing coupling through the Very this shields are practically useless; aluminur used for the purpose should be .08 in thick, copper may be thinner but shoul thickness. The lead from the plate of one tube to the co of the shielded by means of a small grounded metal coveri tubing. To eliminate batter coupling, use r.f. chokes and by-pass co battery or eliminator circuits. not be less than .05 in. in next should be Stage , such as densers in the plate circuits Direct A-Supply from Charger An A-filter device has recently made it appearance on the market which may be good 2-amp. charger fi complete elimination of the A-battery. | consists of the necessary choke attached to any combine ANY GOOD 2-AMP RECTIFIER CHARGER ' POWER CLAROSTAT 10 OHMS PLACE 6-VOLT SUPPLY — —> VOLTMETER HERE Simplified Diagram of Connections, Showing Variable Resistance in Output TO HOUSE in a single case with a condenser block of 7,600 mfd. A battery delivering 2 to 3 charger capable ot amp. and a means of taps -duty in the secondary, are required. voltage regulation, either by on the transformer or by a heavy rheostat A trickle charger cannot be used except possibly for 199-tubes, consumption not Trickle chargers cannot be used for more than two of the A-type tubes. dry-cell sets using the with a total in excess of the charger output. filament-current

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Fading Signals in A. C. Sets wiring e radio uset per ited et tvpe. One will ently for no reason, it The interesting thing about this ho has changed to an often puzzled by fad- moment the signal from 1 of time between the high and ' Ulpilinoss ; ij strength. This hold de\ ices only formers that occur in the bat et are immediatel duced supply. Volt loud and then, ap- are now on the mat will fade below at power houses wi prove conditio1 drop affects the \ uation, and closer attention to thi ill also do much t: The result is a drop in the signal house slightly, but the trans- furnish the current to the affected by the re ve-regulating device ‘t to relieve this tactot aa B. Bavley, chief en volume points, for the signal fades gineer, Station WAAT, Jersey City, N. J. rrolonged periods unlike the fading ed by natural conditions. The trouble Razor Blades Make Headphone t to be found where you would ex ; So, do not blame the tubes or the Diaphragms ll the. trouble lies in the supply Aboard ship, there are times when we rent. Upon checking up the current have to use headphones in officers’ quar from the house-lightinge circuit, it be found that es when an ex load ] Ls been iced upon the upply. Most houses re wired to handle ly a moderate mount of current, nd when electric eaters, toasters, icuum cleaners id flatirons, not to mention washing achines and re- devices, load the light circuit exceeds the carry ing capacity of the Irigerating re used, the fading occurs at the be sleeping. Phone Cap and Diaphragm Removed for Substituting Paper Disk and Razor Blade ters so as not to disturb those who might While experimenting with these in the usual loud-speaket jack to retain the full ef ficiency of the set, [ hit upon the fol lowing idea which smooths the volt and brings out the bass notes wi prising result Un screw the phone caps, take out the diaphragms and use thin safety-razor blades instead, plac ing one in each unit. Cut note-paper disks, using the dia- 661

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662 rOoOrtULAR phragm as a template, and place a disk in each unit so that the blade will not come in direct contact with the magnets of the phones; then replace the screw caps in the usual manner. Fairly heavy note paper the a Magazine cover to Snyder radio oper- San Oi good quality mav be used although made them from that thickness results A. R S. S. “Delta Queen,’ California write! hecause seemed give better tor Francisco, Keeping the Set Dry is cleaned and in wp : the fuse link | ; taken out, the cap at the up per end being left open by removing the large washer used for holding the link. This cap may be left off if there is no hole it the top, or a few small holes may be lrilled in the cap. The case is then filled with unslaked lime, which absorbs moi ture readily. A small clip, made of brass or copper, is fastened inside the cabinet a shown in the sketch, and the fu e case is then lipped into thi clip. To test the efficiency of the device place it under a glass with a few drops of water: if the lime is fresh the water will disappear almost immediately—H. R. Wallin, commercial radio operator, Brooklyn N. 7. Proper Tube Selection Phere are now a number of-special-pur pose tubes on the market designed for highest efficiency in the position thev are to be placed in the set. More and more radio builders are realizing the importance of selecting such tubes for specific posi tions, vet manv are still content to count the sockets and order as many A-type tube: Needle to sav, this 1s very poor pract.ce and the results will not be those MECHANICS Manufae turers of radio tubes are well informed to the of therefore, if the carton states a obtained by proper selection. characteristics their produet certain and C-voltage combination, use the volt Nev el 11 tery voltage beyond the limit marked op ages specified. crease the B-hat the packing slip and be sure the C-voltag: iS that value. may find that, when usi correct for Phe operat ng 135 volts of B battery, there is no noticeable differenc: in the loud speaker, whether 4'4 or 9 volt of C-hattery is used, but it difference in the life of the makes a b tube and B deciding to use a 17] 112 or 240-tube, look over the data on thess tubes use the to deter mine which you need in your particul set. employ special _ battery. Before and information inclined t po the Cl Some experimenter: are purpose tubes in not tio! ere thev are in cuit; sometimes they work, but appea *tube wil manufacturer has ances are deceiving ani | prol ably not last long to remeinbe that the sands of dollars spent the to deter ine t] e prope conditions under which the tube is to operated and the use will profit bv follo ing the directions carefully—John B. Ex cles, studio director Stati WIR iy troit, Mich. A Handy Aerial Kink When an indoor ora very sl] lort outdos aerial is used with the standard broadea receiver, a great deal of distance-getti ability as well as volume is lost This ma be remedied by means of a mall variab condenser of AERIAL the midget, or balancing type Remove the aerial lead from its bind ing post on the set and connect it di rectly to the grid of the

first tube, with

the midget condenser in Tee series, as shown in the sketch Bert | Smith, engineer, Allan D. Cardwell Mfe Corp., Brooklyn, N. Y.

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POPULAR MECHANICS 663 Safety Insulation for Screwdriver Vhen minor adjustments are necessary . radio set, the handiest tool available of course, the screwdriver, but to be | safely its metal shaft should be well tlated in order to avoid damages to the often expensive—through short-cir- ting. Select one having a long shaft ch will permit clear vision when work- in different locations and insulate the t with a length of rubber tubing long ugh to cover all the exposed metal face except the tip.—M. M. Paggi, chief neer, Station KF WO, Catalina Island, Misused Antenna Insulation Insulators, properly used, are an im- rtant part of the antenna system, but ny believe that the more insulators e uses the more effective will be the in- lation. This is not altogether true, as a tle thought will show. An antenna with he insulators placed as in Fig. 1 is a mon sight. No doubt it works, but designer not getting full benefit of ulators, as the total resistance of the tter, when connected in parallel, is much than that of one single insulator, iced as shown in Fig. 2. upply is plentiful, several may be used in If the insulator ies, as shown in Fig. 3, with greater efficiency, since the full resistance value equals the sum of the individual insulator lues. Another misuse is shown in Fig } The writer has noted that the tendency eems to be to use stand-off insulators wr the lead-in wire at points where they re not needed, hese insulators de crease the efficiency ——enr-|] it \ of the antenna and er re unnecessary if ———"Ss?) the lead in 1s eX- Fis.! tended beyond the building as shown Fig. 5. In this case, the lead-in may be brought directly to the set.—C. Har- old Campbell, en- oJ gineering depart- ment, Station —— WICC, Bridgeport, re Fis.3 Connecticut, Fic.2 7 Assembled Unit and BAKELITE | Schematic Circuit PANEL ~~>- Diagram CONDENSERS \ JACK » TO LOUD SPEAKER oo - 005 Wd 500,000 OHM VOLUME CONTROL Headphones on Loud-Speaker Lines An idea that I have found useful when small volume is required for operat! headphones from the same lines that are operating loud speakers, may be helptul to others rhe accompanyil vy sketch and illustration show how this may be done without reducing the volume ot the speakers. 1 he idea is especially applicable to home receivers where no pho ie jack is installed in the set. It is also handy where several speakers are used at remote points and the listener at some particular point desires less volume, A 500,000-ohm vari able resistance is placed across the phones to control the volume, and the fixed con densers 1n the line prevent shorting the loud-speaker leads which would reduce their volume. \ simple panel ar rangement such - a ae own - be handy tor tapping the speaker line at any convenient point. This unit can be permanently con- nected to the speaker line and the phones -} plugged in when- ever desired. —H. B. Nebe, chief engi- Fic.5 neer, Station WSMB, New Or Proper and Improper Use of Aerial Insulators leans, La.

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664 POPULAR Repairing A. F. Transformers rhe writer was recently called upon to rewire a radio set employing a two-stage tuned-impedance a.f. coupling unit. After z J (nd) f. Swe ” 3 iE is — B+ Fig | SHE “— ; Fic. 2 the set was completely wired, it was found that the first tuned-impedance coupling unit was open, that is, it out. As the cus tomer was in a hurry and the writer did primary winding of the was burned not have time to put in a new coupling unit, the repair method illustrated in Fig. 1 was used with good results. A > ductive resistor R, non-in 106,000 ohms, across the primary winding of about was shunted as Shown, and the ear could not distinguish then and coupling unit was installed. had a open was in the primary of an ordinary af. any difference in reception alter a new Later we similar case where the transformer. The same method was used here and with approximately the same re sults. A 100,000-ohm > resistor nected as in Fig. 2.—-G. N East Was Con- Garrison, Orange, N. J. con- sulting engineet Neutralizing R. F. Stages Oscillation in the r.f. stages may be con- trolled very simply by shunting a variable 800-ohm resistance across the primary of shown in the dia each r.f. transformer, as gram. Receivers employing this method Dx. work, and the quality of the signal is par of neutralization have done amazing IsTRE p S 20 RF 6 fi | f / { eA ' = : + + 800-OHM RESISTORS Diagram Showing the Variable Resistors Shunted across the Primaries MECHANICS The adjustment is very the dials at the lower end oj the broadcast band and adjust each re ticularly clear. simple; set oscillation will occur At this setting, will not oscillate at any point within the sistance so that no at this point. the receiver broadcast band, and is ready for opera tion.—M. J. Weiner, chief engineer, Sta tion WODA, Paterson, N, J. Reducing Local Interference Noises and interference picked up by receiver in a building lighted by electricit) are largely brought in over the supply lin reduced and ofte1 eliminated by using r.f. choke coils in the lighting line. These noises may be A coil consisting of 20 ft that wound on side of the of wire, of the same size as used in the house wiring, mav be broomstick and cut into each line at the meter. The coils will not in terfere with the light line but will choke r.f. currents that follow it ing the noises, thereby reduc They also prevent r.f. en the build ing from being transmitted to the neig] bors.—Chas. Middleton, WRAF,. LaPorte ergy generated by apparatus in chief Ind. engineet Station Aerial and Ground Connections Frequently the housewife would like to dust behind the radio console or radio ta hesi S ble, but ‘ pea re ) —— rr tates to do so Cc —f. ——Mip me for fear she MIDGET JACK AND PLUG mav seriously ° - wT , interfere with f . oe - —=—== = the aerial and MIDGET JACKS | ground con MOUNTING nections. The PANEL GND. AER | very simple & a REAR VIEW OF SET arrangement shown was devised by me lem \ hole long, was cut in the and has solved the prob- about 2 in. wide and 3 in. rear of the calinet two midget jacks were mounted as shown and and covered with a piece of bakelite; leads soldered to them and connected to the ground and aerial posts in the set. rhe external leads were identified with tags and connected to midget plugs. These plugs may be withdrawn when clean ing and then replaced.—J. B. Bayley, chiet engineer, Station WAAT, Jersey City.

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More Speed from the Outboard Boat By CLYDE HANSLEY T= OUTBOARD motor fan who would like to increase the speed of his at by from five to seven miles an hour | find the simple plan described in this ticle well worth a few hours of his spare e. It can be adapted to almost any pe of hull, and, for those who like speed This Simple and Easily Made Attachment Increased the “peed of This Boat by from Five to Seven Miles per Hour; It Is Easy to Adapt It to Almost Any Type of Boat but cannot afford a specially built boat, or their abilitv to build one, it The writer tried it out on an ordinary skiff, and who doubt offers a very satisfactory substitute. the results were splendid rhe first step is to take careful measure- ments of the keel of the boat. From these

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666 POPULAR measurements, make two duplicates of the keel the false keels—and screw one of these to the underside of the stern, on each side, as shown in the accompanying draw- It boat. the kee ing vill be noted that, on the original l isequently the false keels also, taper from the stern to a point + or 5 ft. forward If the keel on your boat is straight, it is usually not a difficult matter to replace it with a keel that will tape rom a 6 8 depth at the tra ) teé ibe » a thin section tor ward When atta keels, use either galvanized or bra 3 screws, or bolts Phey can be nailed in place, but nails may cause leakage and cracking later on. Next a piece of tin or light galvanized iron is cut to fit, bent and screwed , ; ; ward and along the sides of the tal yradded for e keels as in the drawing Chat is all there is to it When the hull is at rest, the course, be water between the re will, of metal plate and the bottom of the hull When the boat is under way. and hen a speed o1 more than eight miles an hour is attained, the hull will begin to “plane,” and the tern section Il olide ilk gy yng on the metal. This allows the water to drain out of the hollow stern, and see to form an ait cushio1 which adds to the peed as the stern, instead of d1 igging, now glides on the surface of the wate Locks for Windows Numerous houses in the vicinitv had been entered by thieve ind the problem of making the windows as secure as: po ible, came up the last minute before go ing on a summer vacation. Window catches in general use are so easily broken or sprung fasten vas decided to the sash by drilling a hole directly under | the catch from > the inside but 4 not quite { through the ) outer sash, and slipping ina ten-penny nail. This not reinforced only the catch, but pre- blade vented a MECHANICS from being slipped in between the sash t unlock the catch.—C. D. Paterson, Wo: Mass. cester, Repair of Rubber Balls Rubber balls of the air-filled type lo their bounce, if there is a small hole j them through which the air escapes Ay effective repair can be made by forcing ai into the ball with put holdi le while pum a bicycle Ip, the hose tightly over the he ing. Chen remove the | ose qu CKIY al ‘ ly ¢ Lhear tel he v9Tt ‘a } } apply a rubber patch, the surtace oft t ball having been previously cleaned a rubber cement should be thoroughly dry the patch.—F. H. coated with The cemen 1 before appivin ravlor, Stratford, ( an Loosening Stiff Fishing-Rod Joints joints of stick so that it is Telescope new fishing rod frequently extreme! dithcult to loosen them without damaging the rod A Wisconsin fisherman expr encing this difficultv, made a smali bo from a twig \\ and split the ; ends to re ceive alength yx! \ Q of fishline, as +. A 1) shown in the | \ ‘ aqdrawin:. \ Whentheline , is wrapped a few times ; tround the "a a oints of the pe rod, the bow Va is operated to lide the line over the joint This produces considerable heat, expand ing the outer ferrule of the joint so that the rod sections can be pulled apart with out the least difficulty Corkscrew for Untying Knots When to string which there is a hard-tied knot that de- it 1 well to try to unfasten it with the aid of a one wishes save a 11) fies ordinary means of loosening it, One trial will convince you that it is about the handiest and most effective tool for this purpose. small corkscrew,

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POPULAR Cleaning Old Paint Brushes which have been al- ved to become stiff or caked with paint uch an extent that turpentine does not en the bristles, can be softened in the lowing way: Take a package of any of e well-known brands of powdered soap d make a very thin paste, using cold ter. Let the brushes soak in this paste til they are soft. Any brushes worth ing at all will come out clean and pli- e—John M. Lang, Portland, Oreg (ld paint brushes, Pads for Winding Coils Prevent Finger Injuries ln winding radio coils or magnets one’s ger tips are usually blistered by friction inst the wire as it slides between them. pair of small pads for the fingers will make the job much more comfortable in his respect. Sew a piece of felt to the side of the thumb and forefinger of a pair of old gloves. When wearing these, e wire can be grasped? and allowed to ide through witheut risk of injury. House Numbers Made from Old Auto License Plates When it is necessary or desirable to pro- ide large house numbers in order to in- ure greater visibility, get some old auto- license plates. Cut out the numbers with a pair of tin snips, punch holes through each number at the top and bottom for small screws or nails, with which they are fastened. Such numbers are and can be seen tance —Frank W. \ alley lowa very neat for a considerable dis Bentley, Jr., Missouri Large, Visible House Numbers Can Be Made from Auto-License Plates MECHANICS 667 4 + * A SECTION OF; Elastic Stay Ropes for Tent Hold It Taut and Help Prevent Damage to Canvas Elastic Stay Ropes for Tents Rubber bands, made by cutting old in ner tubes lengthwise, can be used as part of the stav ropes of a tent, and will keep that it sheds Equipped with these, a tent will also withstand a the canvas taut, so water more readily. high wind without damage as the elasticity of the rubber pre vents sudden jerks, vas. Similarly, should trips over the stay ropes which strain the can damage is prevented if it happen that a person o1 animal Waxing Surface of Photographs \ pleasing finish can be given to phot graphs by waxing the surface with ordi nary floor wax. It is applied and polished in the same wavy that it is used on wood This kind of finish suitable for photos work. especially that have been tinted with oil or water colors, as it forms protective coating and at the same time removes many irregularities. Two apph cations may be necessary before a pet fectly even coating is obtained.—Walter EK. Burton. Kenmore, Ohio q I: rasers Cat lye by rubbing thet on fine sandpaper good condition

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668 POPULAR MECHANICS A Solo Tennis Game commodate the length of hose which came vith the cleaner. The hose was attache Pies ee eee eee 7 a very tennis player has felt the desire to the bellows, extended through the floor + I o get out and play at times when neither to the vacuum cleaner, which was set o court nor partner are available. As a a shelf just below the bellows. A swit near the kevboard controlled the cleane Plenty of pressure is obtained in this W -Warren Brown, Galesburg, Mich. Timesaving in Casting Type In print shops that do casting from ma it 1s otten necessary to cut a hole in t finished cast, inside of the border, to sert the firm name, or a price, ete. | average shop does not have a route ig saw with which to cut this hole, and is a long and tiresome job to do the wor by hand A quick and efficient methor providing for the hole at the time tl casting is done is to cut a block of wood the size of the desired hole, and nail it to the mat in the proper place The woo base of an old tereotvpe can be used f¢ Game for the Lone Tennis Player Which Gives Exer- cise and Tests Sk this purpose. When the cast is made, th metal will flow around the block and for substitute outlet for one’s energies, the the hole-—Fred Birch, Jr., Glendive, Mont simple game illustrated in the drawing has been found satistactory. Two boards, 4 Holder for the Fishing Pole in. wide and 3 ft. long, are attached to a wall about 1 ft. apart, the lower one 7 ft When fishing trot i dock o1 pier, on above the floor or ground. From a stand cannot lay the fishing pole down withou 12 it. away, the plaver serves the ball risking that it mav be pulled into the wate against the ground so that it rebounds by an ener . strikes the upper board and rapidly vi getic fish that brates between the boards for some time takes a notion Failing to do this, the ball rebounds and to bite just f returns to the plaver so that, if he i when you are 'é ae lg skillful, he can return it time after time not looking or, = = ~~ One such set-up | often been in use occupied in = t Fiswine /- continually the whole day, some players preparing bait » Art becoming able to place the ball betwee: etc One fish j / ™ » the boards several times in succession erman expe / — | riencing this " i i trouble had :; Improvised Blower for Church Organ ible had a simple holde: We have a large reed organ in ow made from a - church, and it requires a great deal ot piece of flat eet pedal work to keep the bellows inflated iron, bent to Klectric blowers for reed organs could not the shape =/ be had for less than $100, and we did not shown. It is “K P feel justified in making the purchase \ nailed to the good substitute, however, was impro edge of the dock so that the end of the vised An ordinary vacuum cleaner was pole can be inserted in it and will then be obtained and a hole was cut in both the held securely against the pull of any fish back of the bellows and the floor. to ac- W. Kuecker, Chicago, Ill.

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POPULAR MECHANICS 669 Make This Color Bookplate Stamp a good grade of glue. To insure that all the stamps register, or print in the proper For making a bookplate stamp, odd space, a clamp of the kind shown in the ces of rubber tile and smooth linoleum ring will be found handy, and _ this CARBON PAPER WITH ; ; CARBON SIDE UP ‘\ terial can be obtained almost anywhere. out the design on a piece of paper, king a reversed carbon copy on that per and on as many other sheets as are Attractive Bookplates in Several Colors Can Be Made by Means of This Simple Stamp, ia Which Is Cut from Rubber or Linoleum Flooring and Mounted on a Wooden Base Provided with a Handle ecessary to make up the desired number drawing can be made up. It consists of tamps for the various colors of the a base to which an L-shaped piece of wood ookplate Phe outline of the stamp in _ is attached, a flat spring being fastened to ctual size should be laid out at the same this piece as indicated, In printing, sey me so that both copies can be matched. eral sheets at a time are held in the clamp, Cut the linoleum or rubber to the size of and the stamp is held against the corner he stamp, making two, three or more of the L Each stamp is printed in it pieces, according to the number of colors color in turn. It is advisable to use to be used. On the smooth side of these printers’ ink on these stamp The ink pieces, glue carbon copies of the design. is spread out on a flat piece of metal, and he parts to be of one color can be cut a hard-rubber roller is run over the ink, n relief by means of a sharp safety-razor the ink adhering to the roller being trar blade. Cut away the part not to be printed, ferred to the stamp by passing the roller leaving only the design raised. To obtain over it. With reasonable care some fine traight-line cut, press the sharpened prints can be made in this way.—F. Paul- edge of the blade straight down or at a_— sen, Pittsburgh, Pa light angle into the material along the ne, as shown at A in the detail, and cut Q@Before storing rugs and carpets, clean vay the undesired portion at an angle, them thoroughly and, after spreading at B After cutting the patterns, they them out, cover with paper that has been can be mounted on wooden blocks to — sprinkled with turpentine; this protects hich suitable handles are attached. The them against moths. Also wrap them in mounting is done by means of tacks and paper, gluing all overlapping edge:

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670 POPULAR MECHANICS up all slack from the catch string so that tl aie aa aeaeal k STRING TO BOW} TRIGGER CATCH et —W. A, Bonstield

1e Adjust th fill th noose, noose will space in the box opening when the trap Wellesley, Mass Governor for Stationary Auto Motor 1 H lh Ir: ] : ithe drawing 1IOWS a uple govern to keep steady the speed of an aut \§ motor used as a stationary e 1e ry \\: : ue \ \e--Bow device was built around the steer \ | knuckle clamp portiol oO} peedot rete | | cable fitting Phe be 1 hou for t } TR : | rovernor spindie cot oO! i r th | teel tubing, held b I clamp, and 1 tl = end oT h cl ly onze bu ] 1 ° Lf pressed It ma be fou | ect il set ; R ot yme clamp to rea em out to fit t : ge r ’ : ty tub ne l s sha t carries a \ pulle VY : disk soldered to one end. and , or 4 and Mice . . Bele meds la ali lek tell ee How to Make a Bow Trap omitted a. shows The weiste lever A bow trap s easily ma le al d 1 vel fi ed from 6 b ] tee] i etu effective for killing rats and mice fitted The weights cot tot 4% fib make one bie tor rat nail togethe tubing, filled w nlaste ot pat Le our boards, 8 11 ong and 5 in. wide cannot be used because of it nertia [1 1} t se) Ol€ l tre one end to hol | high speed | he conrro le ¢ B mu the bow a own Also cut at opening be made to‘suit the thro of the t ot Z ! 1 the opposite end, for the lever on the carburetor used 1 bro trigget 1 two holes, 2 in. in front ot rod was used for this part 1 1 ori t t1 er ole tor the noose hich inal Phe beari cup on rod A is file hould be iade of fine ire | ra di led a inl licated. then iidered the ic] ed it the end ot the ro _ SPRING CARBURETOR 2 ; ould be quite sup p) CPT canadian oot ae eva re a atter the practi | , 43 ple ina trot ; h ~ that support t A , . i". 6 ROD SPRING a , - y \\ tle out the @ROD, | : _i| control 1ievel na Pa er — — 8 ——SS hl i i gh Sais ees | or Oo € ind catc¢ is tend bared een scre ed ’ ; , ARO? ind il i na ~ oA ft" place. A long rod BE NG U f 1 op of string to the shown at the toy ox to hold down cet ie A iow connects the cor one end of t oe i} trol lever to th ° - d catch, the trigger PULLEY ~ [9 FLANGE yy throttle lever on the being used to hold fa HT GAR \ carburetor, and a : a : SPEEDOMETER ; the other end. Tie s) vial he ‘ screen-door spring ; 3 -_ : f trings from the ; FIBER TUBING y} fitted as indicated — ' bow to the noose Bar a PLASTER vw serves to keep the en ~*~ PARIS WEIGHT indicated, carefully taking catch as nstructional Details of a Homemade Governor for a Stationary Auto Motor throttle closed and to adjust the speed.

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/ Boomerang | hrowing \ is Grea | oe Keenan \ H-Ward y Agathe Away it } “goes, skim- F - ' ning the surface cm »\ {the ground for oe ZoU distance of it. oF then, rising like a bird in its flight, it wheels and comes hurtling back to the thrower, landing al- most at his feet. Believe it or not, there’s real fall sport more, and in boomerang throwing. The boomerang comes from \ustralia, where the flat ountry makes an ideal arena for their manipulation. The little brown Bushmen of the \runta tribe, who depend on them almost entirely for hunt and defense, make no less than twenty different forms of boom ranging all the way from a 14-1n. hird stick to the heavy 4-ft. war boomerang Most Australian boomerangs are in the erangs, hape of an obtuse triangle, flat on one side and convex on the other, measuring about ft. from tip to tip. use acacia wood in their construction, but The brown men vour homemade one can be fashioned quite nicely from a piece of hickory or second-growth ash, %6@ in. thick In making your own first step is to map out the paper patter by 1234 Do this on a sheet of paper, 29Y in The paper plan is shown in Fig boomerang, the port Only a rough adherence to the pla 1 necessary in order to insure a successful Note that the width of the hoomerang arms, angle, is boomerang. near the 2 in while they narrow down to 1%¢ in. at the rounded extremities Cut out paper two lines across it in positions somewhat your model similar to those shown in the lower draw ing Now, pattern on the wood stock and trace out each half of the place vour hoomerang, as in Fig. 3, the portion of the pattern between the two lines being part of both halves After the been penciled in, take a keyhole saw outline has and cut out the two portions, as shown in Fig. 4. The next step is to cut each “7” end of the boomerang, *s, hetween the lines, into *. ] ape for a half lap joint, * as pictured in Figs. 5 and 6. A miter saw is the tool ir this task, but at good hacksaw serves quite w¢ Phi joint is then glued press until dry, after which a sit gle row of small nails are drive into place along the cente1 is 11 dicated 1: Fig. 7 N« it] pokeshave ilie } ¢ 1 dk ‘ € cle iti

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POPULAR i) one side only, of your boomerang toa con- shaving, only the sharp edge is taken from the wood at the center in order to leave the joint almost full vex shape, as shown in Fig. 8. In strength, but the remaining part is cut down to a feather line at the thick edge while retaining the full %6-1n a le center ine. Additional nails are then driven into the joint, and aluminum reinforcing strips, cut to shape with tin snips, are nailed to the center and tips of the boomerang on the flat de, as shown in Fig. 9, The final operation, Fig. 10, consists in giving the whole thing a coat of stain o1 \ bright color paint should be used instead of stain if you are varnish, contem plating throwing in deep grass, in order he boomerang more distinguish- falls. to the throwing The average to make t able where it And now person thinks that the throwing of a

some- ] boomerang is hich can onl thing w Vv be acquired through long and continuous practice, but that idea is entirely erroneous. Throwing the curving stick is an accomplishment which you can make your MECHANICS own tar more readily than the pulling a forty-pound longbow. The first that the must always be thrown against the win rule is boomeran It is against the wind only that the mas stick is self-retrieving So, facing the wind, vou hold the boo: ene ; , n your right hand with the erang rounds side inward; that is, the round side shou be the left side of the boomerang, whe held it 1 throwing position by a right-ha thrower. Holding firmly to one end, bt the stick over your head until vou rea the position shown in Fig. 11. The bringing the arm forward in a straig] overhand swing to the position shown Fig 12, release the stick with a short uy ird jerk of the hand, used in omewhat like tl cracking a whip. This i Without this sharp boomerang portant. jerk, ‘tl gets off to a slow spinnin start and will not revolve fast enough t

FIG. 1.

THE PAPER PATTERN

Je—., 7 31 ——>}

|

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POPULAR MECHANICS 673

il it bo “IA vourt ANES <BACK ‘ ‘ ‘ ‘ ‘ . ‘ ‘ ‘ ' o ‘ ' = pe VERTICAL ~*~ POSITION OF HORIZONTAL POSITION OF ...“"# *

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674 POPULAR make the return jour ney; with the snap correctly done, the MECHANICS boomerang will fairly zoom forward, spin- ning so rapidly that it is apparently trans formed into a circular plate of wood of a diameter equal to a straight line joining the two ends. That's all there is to it. ginner learns boomerang throwing some- what like this: ground; The average be- He pitches a few into the he sails anywhere from two to thirty times with no visible signs of a re- turn and then—success, after which the knack is very seldom lost. flight, the missile will swoop straight forward in a journey; In a successful boomerang nearly vertical plane for a distance rang- ing all the way from 100 to 350 ft. As it covers this distance, 1t changes to an al- most horizontal plane, and then, swerving to the left. it soars aloft like a bird and then comes swooping back in a long vol- plane, to land at the thrower’s feet. The parabolic flight of the boomeran: Althoug de cI ibed is a beautiful thing to witness the throw generally a magic stick can be made to perform arcs, A slight small deflectio: of the throwing angle, and the boomerat score of other graceful variation of the snap, a can be made to shoot inward with territ Swiltne a lazy are, « Almo behin: a stump or a pheasant on the wing, 1 fit mark for the flying stick. curve outward in hoot upward in spinning flight. any object, be it a rabbit hiding After some proficiency has been gain in directing the flight of the boomeran: you can erect a target consisting of a but lap sack filled with straw and aim you tick at this. You will soon acquire su ficient skill to score a hit fully half the time at a distance of from 40 to 60 yd And if you do miss, well, back it come like a trained eagle wheeling in the breeze! Removing Cork from Bottle It often happens that corks in bottle and jugs are shrunk or are pushed down that it is difficult to them. At easy and effective into the neck so tar BRASS remove SCREW method of over- coming this trouble is to drive a screw eve or wood screw into the cork as in With this arrangement, the cork can, in most cases, be removed without any trouble. James F dicated. Hobart, Chicago

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POPULAR Preventing Loss of Outboard Motor Propeller e propeller shaft of every outboard is provided with a small brass shear- n, which holds the propeller, from ng on the drive shaft. The pin is de- “1 to break off when the propeller es any submerged object, so that the 1 will not be damaged. However, frequently a broken shear-off pin is cause of losing the propeller, a part cannot always be replaced easily, and costs from $3.50 to $5. With a en shear-off pin the propeller freely on the shaft and backs up against end nut on the shaft, often with suf- nt force to turn the nut and let the peller slide off. After losing several pellers in this way, I decided to prevent rrence of this loss. The end nut could be keyed onto the shaft because the is too hard to be easily drilled, so I nged a metal claw as shown. To in- | this device, it is only necessary to re- e the propeller, place it in a lathe and a ‘4e6-in. groove in the end next to the propeller-

el EE eee shaft housing. oT Pts 7 Ay----- -< The claw is a Bee made of spring on METAL CLAW brass and is + onal fastened tothe

gVEAR OFF PIN ‘ housing with two screws. The lip of the claw rides in the groove cut in the pro- peller and keeps it from sliding off the shaft if the shear-off pin breaks. Inas much as the propeller can not be forced back, it will not loosen the 1 nut on the shaft, but even if the ut came off, the propeller would still be d on the shaft, free to rotate but not » slide off As the claw is made of spring etal, the end can be lifted out of the slot the propeller to remove the latter.— John Edwin Hoag, Los Angeles, Calif. MECHANICS 675

Pots and Pails Suspended over a Camp Fire by Means of an Old Auto-Tire Chain Old Auto Chain Holds Pots over a Camp Fire In the absence of a grate, an old auto tire chain will be found convenient fot holding pots and pails over a camp fire One of the side chains and all but three or four of the cross links in the middle are removed, and the remaining part is then stretched between two. stakes, as shown. The ends of the chain are fas- tened by means of short pegs, pushed through the end links. The pots and pails can be suspended from the cross chains, and the fire built underneath. Another cross chain, with a strong stick pushed through the end link, can be used for re moving and handling the pots when hot as in the upper detail Driving Ants Out of Ice Boxes Ants are often difficult to drive out of ice boxes in the summer home. How- ever, the following method will prove et fective: Mix a solution, consisting of a small amount of tartar emetic, sugar and water, in a saucer, and apply it in the cor- ners and around holes where the ants will come in contact with it in their attempt to get inside They will soon disappear.—L., H. Georger, Buffalo, N. Y.

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POPULAR Preventing Double Clothesline from Slipping on Pulleys Double clotheslines, pul- leys as shown, used on have thetr dis- advantages: When the wind blows, it often causes the line to shift, moving the clothes toward one end, until they may touch the pole or the the house and get soiled. To prevent this, it is a good idea to slip a hook over both lines at each end —Mrs. R. A. Jessen, Keansburg, N. i side of Trough for Testing Tires That Leak Slowly Tires having l ea ks often fail to show any evi- slow dence of such leakage when the tubes, re- moved from the casings, | are only partly inflated. The writer, expe- riencing this trouble, made a testing trough from a section of discarded auto casing of large size. This was nailed to a piece of 4-in. wood, to hold the trough im an upright position, as shown. The wheel with the leaky tire is raised by means of a jack so that the trough can be slipped under the tire —A. C. Brundage. Rochester, Minn. Using Carborundum Stone on Razor It is rather difficult to keep a straight- blade razor honed to barber-shop eff- ciency, but here is a method of dome it which I have used for fifteen years. Get a carborundum stone of the finest grain, MECHANICS strokes dry stone just before stropping. and give vour razor a few on the You w find the edge is improved by this treatme: —A. M. Parker, Edmonton, Can. Getting More Mileage Out of Your Ford I have a model-T Ford and I averaged 36 miles per gallon on ethyl-gasoline. 1 obtain this result, I had &% in. of the meta planed off the face of the cylinder head where it fits on the block. This brought the head closer to the pistons and thus iy creased compression without weakenin: the head, since the force of the explosio) is taken by the bolts with which the head is held to the block. When replacing th: head, %-in. washers should be put unde the bolts to prevent tw isting them off. The valves and piston rings must also be good condition, and the carburetor mu be adjusted lean for the After this impossible to greatest Tue economy. alteration, I foun make the mot knock except when going five or six mil an hour uphill and with the throttle wid open. I run miles since and there is still no fuel knoc} it was have this car about 2.00 It is nov advisable to use ordinary low-te gasoline with this high-compression head but it can be used if care is taken in ad vancing the throttle slowly to knocking. In a Ford motor, a %-in. sh off the head space about prevent reduces the compressio: 14.5 per cent, and compre sion will be correspondingly greater.— H. Howard, Hannibal, Mo. Salt and Pepper Shaker for the Camper To save space in the camping kit, every unnecessary item should be eliminated and, if possible, one article made to serve several purposes. Instead of having sep arate salt and pepper shakers, the two ca: be combined as ' the = AW ~ Get a shown in drawing. test tube of large size, which can be aati ass CUT OFF \ purchased at any Wry Oe: M drug store, and, with a file, cut off the closed end. smoothing off the sharp edge so that

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POPULAR ill not cut. Push one cork to the cen- i the tube and provide two more for ypen ends. You now have two sepa- compartments, one for salt and the for pepper, and as the container is vou can see which is in each. An reakable combination tube can be from a section of bamboo, with a in the center, and the contents ched on the outside, Unusual Rat Trap had considerable trouble with a rat ‘h always succeeded in keeping out of pring trap I set for it. Determined to it, | rigged up the unusual trap shown e drawing. It consists of an old cab- door, about 2 ft. square; a short stick long, a weight and a spring trap. The the cabinet is raised so that one edge rests on ter is screwed to the floor: the door as cated. A suitable weight is laid on clined door stick, which is set under The spring part of the ip connected to the stick with a stout Another cord is tied to the triggel ne end, and to the bait at the other ch is laid on the rt of the door. floor under the center The trap is then set so Z Ze GG V4 reap SCREWED To 0 rloon,, 7 iat ee, «he CHG Novel Rat Trap Consisting of a Large Board Which Falls on the Victim it, when sprung, it jerks the stick from ts position, and the door, being unsup- ported, falls down. When the rat takes id of the bait, and before it has time to get away, the door falls on it. The trap iught the rat that had evaded the former trap and did great execution among the thers —W. L. Hadlock, Chicago. MECHANICS 677 Handy Cabinet for the Garden Tools Can Be Built in the Porch Floor Porch Cabinet for Garden Tools In the absence of a suitable shed or ga- rage, garden tools, such as hoes, rakes, spades and shovels, are usually kept in the basement, and rather siast found a much more suitable place for the tools. this location is often inconvenient. One garden enthu He built a cabinet in the porch shown in the illustration. It is long and wide enough to accommodate all the tools, with some room to spare. .The floor, as lid, when closed, is flush with the porch floor, and sufficiently reinforced to allow walking on it safelv. A sunken ring en- ables the door to be opened whenever nec- essary.—L. H. Georger. Buffalo, N. Y. Saving Time in the Haying Season Ordinarily hay is raked, loaded on the wagon and then hauled to the barn, if it is to be put in the mow. If it is stacked in the field, the hav is drawn to the stacker with sweeps, then stacked and hauled in on racks. a few vards from the alfalfa field One man has his hay shed only Instead of hauling the hay in on a wagon, he lays one of the slings on the ground, sweeps the hay directly onto it from the field and then hoists it under cover, thus saving a good deal of time and labor.—Dale R. Van Horn, Walton, Nebr.

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678 POPULAR Keg Helps to Pull Stumps When pull- ing stumps or large with a tractor, keg can be used to roots a strong advan- tage. The ca ble is attached to the stump near the ground and the keg is then put un- der the cable near the stump as shown. When the tractor pulls there will be an upward as well as a side- —James W. Cot- good tps thai A a ”) aaa wise strain on the stump. trell, Hammonton, N. J. Hinging Porch Windows to Avoid Trouble Glazing a porch is usually a simple job, the sash made to fit the and hinged to permit swinging them up so being openings that they can be fastened to the ceiling. This arrangement works well in many cases, but trouble is often encountered when the sash are other, at right angles to each as at the ends of the porch. The end windows should be arranged to swing up higher than the adjacent ones at the front, which THICKNESS _--” OF SASH entails consid- erable calcula- SS tion and care- —— ful adjust- —1—a = ment. The dif- ficulty can = | readily be | yi ] i avoided, how- i, ever, by hing- \ ____J&__— > —— - ing the windows, nearest to the corner on the front side, to- two =n sil J shown in the gether. as drawing After the end folded over the which is hinged at the top, window is second one, beth can be MECHANICS swung up together. In many cases, a pa of offset hinges are necessary. The im the deta drawing shows how these hing: are bent at right angles, so that the pivot section flush with the when it is comes surface of the end sash other window. folded onto the The bent part should bx sunk also into the top member. How to Prevent Loss of Tools in Overhauling Auto Whenever I am working on my car out doors | take along a flat box, turn it uy side down and lay my tools on it. That i better than putting the tools on the ground where they be lost. If the repair work is very extensive, the car car be run onto a piece of old canvas, so that all nuts, cotter pins, and other small piece will be caught on it without loss.—Arthur Flinner, Wichita, may chance of Kans, Flashlight Carried on Boot flashlight holster sewe When out can be carried to the boot, in the drawing. position it is hunting, a small a leather as shown In this always both hands free and relieves the pockets. The hol ster consists of a piece of leather, 5 in. and 4 in. wide. Place the flashlight against the leg of the boot and the piece of leather across the light as indicated. Sew the two side edges to the hoot so that it clamps the flashlight tightly and close the lower opening with a strip of leather. A tight fit is keep the light safe, no lently the leg may be Harwich, Mass. handy, leaves long wrap necessary to matter how vio- B. Rob- moved.—L. bins, Removing Ink Stains Recently one of the clerks in the store where | am employed dropped a quart bottle of ink on the floor and broke it. The result was a large black stain, about 2% ft. in diameter. | mixed up some car-

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POPULAR te of soda and chloride of lime, in parts, and added water until the had the consistency of cream. This ubbed over the ink stain with a damp and left the floor clean. The method f works on clothing, and is the best | r vy of for removing photographic-de- per stains from the hands.—Warren wbard, Decatur, Il. Heavy Stirring Rod for Chemists wooden stirring rod for the chemist photographer is not practical because bsorbs the chemicals and therefore ; not be used in different solutions. A , ilar stirring rod is rather thin and un- thle for use with large quantities of ut An ideal rod, which costs only 15 cents, depending on the size, is ordinary towel-rack glass rod, which be had at the 5 and 10-cent store. It i knob at each end, which is excellent undissolved chemicals. IONS, crushing Two Handy Tools for the Fisherman » facilitate keeping a string of fish ere you want it, the handy tool shown the insert will be found useful. It is de from a discarded auto or tractor ve, the end being ground to a point sur muddy shoes or boots can be scraped ean quickly by using a similar valve, but referably a smaller one having the end tened and ground down as indicated Missouri Valley, Lowa. W. Bentley, Jr., Fishermen May Find Good Use for Discarded Auto and Tractor Valves MECHANICS 679 Expanding Be't Buckle Made from Spring Wire Expansion Belt Buckle A novel expansion belt buckle can be made by using a 52-in. length of No. 10 gauge brass or steel wire, or any spring wire of similar size. The drawing shows end of the buckle, which, inserted in the belt holes, a flattened portion at one keeps it from slipping. The other end is shaped so that the belt can be attached in the usual way. The spirals are made by wrapping the wire snugly about a piece of about 442 by 1%6 in. in dimen- If the hard t » make, hold the strap iron ina vise and also fasten one strap iron, sions, turns are end of the wire, then wrap it as closely as possible, using a block of hardwood and a hammer to force the wire into shape. The belt will be found comfortable R. Hart, Ashtabula, Ohio Brushing Lint from Heavy Fabrics When lint garment of heavy fabric, it is almost impossible to remove it by friction of the dry and accumulates on a brushing, as the brush ordinary creates static fibers to If the brush is slightly dampened by holding it over a electricity causes the fine cling more firmly than ever steaming teakettle, the lint can be removed without difficulty,

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680 POPULAR © ©) CUPPED FOR ( **— RIVET Tool Bent at Metal Ware with ve Dents from Narrow Necks Both Ends Helps to Rem« Removing Dents from Metal Ware A from the outside made be hammered dents in metal ware usually they out from the inside, which is difficult to do are must in the case of vase or other articles with narrow neck \ form of hammer for this purpose is shown in the drawing. It is made from a steel bar bent in opposite directions at the ends After fastening the tool in a vise as shown, the vase is slipped over it until its other end is in contact with the dent Hitting the bar the inner end of the bar to vibrate and strike rapid blows with a hammer will cause on the dent Repetition of the operation while the vase is , MECHANICS Simple Brace for Cellar Door Cellar doors usuall to sag with a ; piece oI Z enough to rest on one when the doors were c hinged to one door a Gose, Kinderhook, I] Children often get i dle with the switches Starte1 celerator and manipulated so that the blows hit the whole dented area, will soon remove the dent. To pre vent serious marks, tool should be padded. A similar tool can be used for riveting, which the in case the hammer end should be cupped so that it fits the rounded end : ‘ Guard Placed of the rivet. over the by Prevents Sagging v have a tendens lo prevent this I braced the do 4-in. wood, lo: of the middle losed. nd projects beyor STteT The brace it so that the other door also is support by it. When the door is opened, the brac« falls back and is out of the way. This p ticular door opened ona porch floor the brace made it possible to walk on thi doors without causing them to sag.— Guard for the Auto Starter Keeps Children from Meddling nto autos and med gear-shift lever The consequence are usually not serious if the ignition k: is removed, but the continual use of 1 starter soon runs down the battery li the ignition key has been left in the loc! the youngsters can sometimes start thi motor and may even start the car. Fe this reason, I placed a guard over the starter, which prevents the children fre operating it. The guard consists of length of l-in. pipe and a pipe flang: which are slipped over the starter am screwed to the floorboard The pipe ex tends about 3 or 4 in. hevond the starte and only by inserting a short length of wood, such as a piece cut Irom a broot handle, in the pipe can the starter be forced down. When I leave the car. | . take this piece ol wood along and the children have not vet discovered the Starter of an Auto Prevents Children from Operating It trick.—Clifford L Burdick, Milton, Wisconsin. @ White sinks, bath tubs, and washbowls toilet may be cleaned with soft cloth, tened with bow Is a mois turpen- kerosene where there is rust. tine: use

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. ny \ \ HW | 1 Nit THe ( ib hi SANA EMNONAW ALA It aA ail LJERE is an artistic antique A 2 lantern that gives a touch beauty to any room or den, en hanging from an electric ocket in the ceiling or from a acket fixture on the wall. It may be made at very little «pense. With the exception liquid glue and gesso, all the aterials necessary are: an pty salt or oatmeal box, or box of cylindrical shape ig. 1), and an electric-light ocket, plug and cord, which av be bought at any 10-cent hardware for a total t of about 40 cents. store Che first step is to be sure at the top and bottom of the box are ued securely in place. ieval fantern Frasut edi val faw ru frase 0 Then cut a round ole in one end, of about half the diameter the box, and slit the remainder of the dso as to form eight little tabs, as in cr ? > -- ated: Bend alternate tabs place with glue. up these are to hold the lantern top as indi- lo make the top, take an old dry-goods Ox, OF any nd similar piece of cardboard ving the same thickness as the salt box | cut out a circular piece, with a diam- ter equal to one and one-half times the ength of the round box (Fig. a, Draw line from the center to the outer edge. ut this line vith scissors, then oll the disk into a onical shape, so that it will fit cor- ectly over the top f the box, and glue the edges of the ‘one together. Now the roof of your lantern on top on asten of the box by glu- ing the tabs made for this purpose, Fis.t ake WiKi NE } Tae a f " ty! | ae } Hi} | \| iii) ft Wii Ah A, th | PAULL Lek tae ee 0 uty as shown in Fig. 4, on the inside In cutting the windows in the box be careful not to make them too large, as they would then weaken the walls, Cut out the rectangular window opening in the lantern first, then make an overlapping frame of cardboard with as many sections or lights Glue this over the opening you have cut in the as desire. you lantern (Fig. 5). Colored isinglass, celluloid or paper may be glued in the win- dows and this gives the lantern a beautiful appearance, although a tinted bulb will serve just as well. The heads of heavy pins may be cut off, leaving a short shank, and pushed through the lamp as indicated in the headpiece, to simulate rivets Make a door in the bottom of the lan- tern by simply cutting out a square open- ing large enough to admit the electric bulb, and then make a cover of the shape from heavy cardboard. ¢ same ut it larger than the opening in the box so it will not fall out. attached to the door in the lamp photographed, and an- other. the upper A bone ring is heavier, is used at the electric ring Holes are punched in through which the threaded, as indicated in Fig. 6 rhe the finishing : top. ring, cord is is First of liquid glue over the entire let it oughly. next step apply a coating and dry thor- To make the gesso, mix a 1- gill lantern can of liquid 1% of whiting, 3 teaspoon- fuls of glue, cups varnish and of and ap 3 teaspoonfuls linseed oil Fic.2 OF 1

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82 POPULAR MECHANICS cloth, and rub this on the bronzed surtace until the desired color is obtained If you wish to procure avery ancient effect dust powdered rotten stone over the entire su face and rub down very carefully. Silencer for Rebound Clip The small rebound clip on the springs of model rl and A Fords often be come loose and rattle. B using a longer bolt and a coil spring, the clips ca: be kept tight without much attention. For the front springs of model-l cars, a 2% or 3-in. ma chine bolt, % in. in diam eter, with a washer and a radius-rod ball-cap spring are needed. The rea spring requires the same outfit, except that the bolt should be 3h long. The model-A frout spring, having a width ot 134 in., uses a 3-in. bolt The rear spring has a re bound clip, but the spring is nearly covered by the frame cross member, and it is impossible to substi eling it with the aid of a stiff brush or tute a longer bolt.—E., T. knife. Try to model the gesso so that Humboldt, lowa the effect will be that of deeply pitted iron or bronze, but do not make the surface too rough. Allow the gesso to dry 24 hours, ply this mixture ail over the lantern, mod- — for this reason, Gunderson, Jt Novel Window Manikins and you are ready to color. To emphasize a sign in a window dis First, cover the gesso with a coating of | play, some odd manikins were made trom bronze powder pipe cleaners. They are simple to n.ake hey bend easily Set before a dark background, they mixed with banana oil. When this is dry, apply the paint, which mav be burnt as t umber or. green are quite noticea [ ble. A single thum)h tack over the foot of a vertical figure holds it nicely. with a touch of deep red here and there. Squeeze a small quantity of color from the tube Heads can be made Sm2ll Manikins Made from Pipe Cleaners May Be from small corks Used for Changeable Window Display ro SHEE! — onto a piece of

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POPULAR Removing Dust from Inside of Violin s generally a quite difficult and te- task to remove dust from the inside iolin. A good method of doing this to drop into the body a cupful of per- dry rice and shake the whole well. ag should be held over the sound holes prevent the rice from coming out dur- the shaking. You will be surprised ow much dust can be removed in this in a few Ruffalo, N. Y. seconds.—L. H. Georger, Handholds Facilitate Carrying Rowboat Carrying a rowboat is usually an awk- rd task as there is no permanent equipment for lifting the boat. Of course, is turned upside down, it can be car ed by two men, but a large boat may be too much of a load. Besides, it may not ibe desirable to turn the boat upside down, Ry providing the boat with oarlock pads ing handholds as shown in the draw- ¢. the task of carrying the boat will be lightened con- siderably a <5 2 uth 2? Sy

Two holds are cut in oarlock pad so that. is screwed there will be plenty each when it down, of room for the hand to be inserted. The edges are nicely round ed. Four pairs of holds can be provided ona large rowboat to enable as many men to carry it at an even keel.—Newcomb Leonarde, Mystic, Conn.

Holder for the Basement Door lhe illustration shows a cheap and easily made device for holding a cellar door open. lt consists of a length of hoop or band iron, about 1 or 2 in. wide and long enough to be fastened to two joists, besides ex- tending 6 or 8 in. beyond the door when open. Punch or drill holes in the iron strip at points where it passes under the joists and attach it with } NaliS OTF SCTEWS, Is swung two Bend the free end of the 3and4.—J. F MECHANICS 683

Soring-Metal Strip Nailed to Joists Holds Basement Door Open strip to form a catch that will hold the door securely, yet not allow it to strike against the end of the strip as it is opened from the outside, but slide under the as indicated. strip The holder should be lo cated as far from the hinges as possible.— C. D. Paterson, Worcester, Mass Splicing a Broken Shoestring knot in a broken has parted near the center and the ends are still in good con 1 | Instead of tying a shoestring when it dition, try shown in the Anvone can do this, and the appearance of the repaired string will be much neater and less troublesome to lace than if the broken ends were knotted. First cut off the broken ends as in Fig. 1 Cross the two pieces to be joined and insert the tips into the cut ends. Then thread the tips through a | small hole cut | splicing it as drawing.

about % in. each end, as in Fig. | 2. All that is | eee leftto doisto | -_ pull each end — and the splice will look as shown in Figs. . Goodman, Imlay City, Mich. from

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684 POPULAR Handy Campfire Grate of Large Size Can Be Suspended Horizontally over the Fire, and When Folded, Takes Little Space among the Camping Equipment iinieeiaaainnmieee ‘ f GREEN SAPLINGS ound - -™ —_* io y is: cae Se em ——— ey # 4 a som Ee oo Lio ff a‘ he A [eo ) =| = |S ae : ¥ }¢ el = ; 2 y- f 4 ' ' ' ' ' ' ‘ \ —— ae -— + A= \ MECHANICS A Large Folding Campfire Grate Many campers use a stove for cooking, but there are also “kick” To these, many who get more from doing it over an open fire. the large folding grate shown in the drawing will be a convenience. It is made from three 24-in. lengths of iron or cold-rolled steel bar, 344 by % in. in di- mensions, to which are riveted, at equal intervals, nine 16-in. strips of 4 by %-in. stock. The rivets should be free enough to allow the grate to be folded. The end holes of the middle strip should be fitted with Y%-in. bolts and wingnuts, which are tightened to make the grate rigid when in use. Four lengths of chain, provided with hooks at the ends, serve to suspend it over the fire, the chains being hooked to a suit- able improvised framework made of wood, The chains are attached to the grate by slipping the end links over the ends of the bars and holding them in place with taper pins.. No matter which way the grate is swung, it always remains horizontal and this prevents easily. utensils from slipping off When folded up as shown in-the a: } littie can readily be carried along with the other upper detail, it takes very space and camping equipment Clean-Out Plug for Sink Drain Is Simple and Efficient The occupant of a cottage was greatl\ troubled by frequent clogging of the sinl waste pipe, which had been run level fo distance, and hence some required re peated visits of a plumber. To eliminate this trouble and expense, the owner drilled a hole in the vertical pipe and stopped the opening When ever necessary, a wire can be passed into with a plug as shown. the horizontal pipe to loosen the ob struction so that it VENT PIPE LEAD JOINTS - washed with is easily CAST IRON TEE : | away water The wooden plug LEVEL LEAD PIPE SINK WASTE* was afterward re WOODEN plus ss placed with a regu plug, the tapped lar pipe hole being to suit. PIPE TO CESSPOOL

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POPULAR How to Detect Short Circuits in Toy Railroads Sometimes the locomotive of miniature ectric trains refuses to run. In such a should go about locating the ouble in a systematic way. Be sure that e battery or transformer switch is closed se one d determine whether the house-lighting rcuit is in good condition by trying the ehts. Test a storage battery with a hy- drometer and dry cells with an ammeter. the current flows as far as the tracks here may be a short circuit in a section of the latter. Test for this by touching wire to an outside rail and one wire middle rail. If a spark there is a short circuit; if not, the Rail shorts are usu- ally found in the clamps holding the third iil down to the may have ut through the insulation and caused a ort with an outside rail. If so, bend p the clip, remove the old insulation and eplace it with new, then bend down the ip again. © one o the inside or ccurs, ection is all right. ties. These The locomotive can be tested or short circuits by holding one wire on e shell of the machine and the other re on one of the motor brushes. A Sure-Catch Roach Trap | 8) make a cood roach small trap, get a glass sirup molasses pitcher, with the spout nearly level the drawing. It should be large enough to oT as shown in admit the big roaches. The cover of the pitcher has a lip which fits tightly down over the spout opening and must be turned aside when ised as a trap, leaving the spout open- ing uncovered. Put some jelly, gravy or bits of fish in the bottom of the pitcher, and the will find their through the open spout. They cannot get out, however, because they, are unable to hold their bodies up while they attempt to get on the horizontal part of the spout from the inside. roaches way i MECHANICS Barbed Wire Is Hard to Unroll Single-Handed bu Easy with This Rig Unrolling Wire Single-Handed \ll that is necessary to unroll a reel of wire single-handed is a good wheelbarrow, a broomstick or length of pipe and four 20-penny nails. These are driven into the sides of the wheelbarrow as shown in the drawing. The roll of wire is placed on the broomstick or pipe, which is then set the the the nails. After the loose end of the wire on the roll is tacked or tied wheelbarrow is pulled away from the post, which unrolls the wire without any across sides of barrow. between to a post, the trou ble—Joseph Enos, Brownsville, Oreg. Cleaning Large Set Rings It is often rather difficult to find some convenient and effective method of clean set rings An pipe cleaner can be used as ing large ordinary indi- cated in the photo, and it will do the work without causing dam age to set or mounting. @ Chewing gum can be removed from dif ferent materials by soaking in turpentine.

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686 POPULAR Substitute for Broken Stove-Door Spring When the spring of an oven door is broken, the door may drop over unex- p ectedly 1 breaking the hinges. A substitute for the spring can | Caslly be pro ided. Drill a through the edge of the door about 2 in. from the hinge at the bottom, and dr il] } ] oie another through the edge the ndic ited. ot stove, is ring of suitable Homemade Soft Soap and Its Use \ good soft soap for laundering can be made as follows: Dissolve » lb. of sal soda in about 5 val. of hot water and then at 20 bars of ordinary laundry oap his will torm a jellylike mass and, when it is cool, stir in 1 cuptul of strong ammonia water, cupful of turpentine, cupiu of kerosene, “% cupful of carbon tetra chloride, 4% cupful of water glass, and 1 cupful of denatured alcohol. This mixture mav be made in a boiler and kept stored in closed jars or crocks. Soak the clothes overnight in water to which the above mixture has been added in the propor tion of 1 qt. to half a tubful of water Hot water 1s best. Che soap dissolves at once even in cold water, but its great value lie in saving the time needed to prepare the soaking solution for the clothes with ordi- nary About SOap. qt. of the mixture should be put into a croc} and collars, handkerchiefs, shirt slee ves and cuffs, and other very soiled pieces, are immersed in it Set the crock in a tub, into which water 1s poured up to the edge of the crock The next morning the contents of the crock should be emptied into the MECHANICS washing machine, or tub, if washing is t be done by hand, and hot water adde Five minutes’ washing will be sufficien Che water with the soap mixture in it feel soft to the hands and will not injure the skin. Only extremely dirty piece have to be rubbed, but after soaking the strong soap mixture all night, only a little rubbing is necessary. The sligh odor of turpentine will disappear if the clothes are rinsed in two waters, and th: out whiter than would think possible with so little labo: clothes will come one In order to whiten clothes, such as work men’s shirts, that will not readily wa clean in this way, make up a mix ture of equal parts of clear lime wate: turpentine and kerosene and shake unt Use a boilerful of for half creamy a cupful of this mixture to water and boil the clothe an hour Anti-Rattlers for Auto-Hood Clips Many makes of automobiles have no rubber anti-rattling devices on the hat dles that hold down the hood ind tl} spring clips used for the purpose ofte ittling The trouble a | sonort cause unpleasant 1 can be eliminated by piec of heavy rubber tubing or hose to tl hood just under the spring handles that the rubber will bear vith a slig pressure against the clip Che draw shows how it was done in one make ot Ca The LTIl¢ ip plies to practi cally anv othe make also. Four l-in. lengths oft heavy-walled rub ber tubing, about 34 in. in outside diameter, were used. They were to ft hood by means ot 6-32 ma fastened 1e @lf a little turpentine is added to st it the coods. will prevent the iron sticki Irom )

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ade All Shop Notes published in 1927, in book form—Fifty Cents—from our Book Department Attractive Wooden Trim for Cabinetwork By CLAUDE WEST hinges, handles and es wy eres N cutcheons, worked out along artistic es, are very ornamental rts for cabinetwork, and afford an un mited field for design. Such parts especially attractive on pieces that other Jesides, they pro pleasing as are se are rather plain. de an excellent means of expressing in- dividuality, and a touch of distinction may e given to a piece of furniture, which in vav would be like innumerable every other \ qt eT With proper designing and finish- ¢ pieces may be made to have an an- tiquue least suggestive enough of it to render them suitable to be used with period furniture. On the other hand, thev mav be designed and finished to appearance, or at suggest the most modern creation of the cabinetmaker’s skill. Phe cabinet shown in the photo merely a semi-Priscilla design, is Ornamental Wooden Hinges of Many Designs Can Be Made by Cutting used as an example, and no dimensions or tor its construction are given ex details cept for parts to be mentioned later, which 1 to 9. should be made of sound, straight-grained Figs. The hinges are shown in F4G.3 the Pieces Out with a Coping Saw and Gluing Them Together

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688 POPULAR MECHANICS Figs. 1 to 9 Show the Patterns for the Various Parts of the Fittings on the Box Shown in the Photos hardwood and the handles and escutch- eons should match. In cases where it is possible to do the work on a bandsaw, the parts may be cut from solid stock of a thickness equal to the width of a hinge, and no gluing is necessary. However, as the work will be done by hand in most cases, the method illustrated shows how to cut out the pieces with a coping saw, and, as thinner stock must be used, the pieces will have to be glued together after- ward. The drawings show a double hinge having one middle section and two end sections, each section being made of three pieces glued together. Pieces of the same thickness may be used so that their com- bined thickness equals the width of the hinge, but in this cabinet the middle piece is as thick as the outside pieces together Fig. 1 gives a side view of these pieces of the middle section, two of them being re- quired. The lines indicate the pattern la‘d out on the wood ready to be cut out. Fig 2 shows the single center piece of the mid- dle section, and Fig. 3 shows the cente! piece for the end section, two of these pieces being needed, one for each of the two sections. The material used for the latter should be of the same width as the material used for the piece shown in Fig 2. Fig. 4 shows the outside pieces for the end sections, four pieces being required two for each section. The material should be of the same tliickness as that used for the piece shown in Fig. 1. When the patterns have been laid out on the stock, as indicated by the lines, the cutting can be done with a coping saw The stock should be long enough to be held down firmly on top of a bench o1 table, while the pattern being cut out pro jects over the edge to permit sawing. The saw should be held as nearly as possible at a right angle to the that the cutting will be done squarely, and the sawing must be done slowly and carefully, the pattern being followed just outside the lines. stock, so Any irregularities can

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he smoothed be done with care, so as to be he heads cut off will serve. apering, using fine sandpaper. Z¢ vith the piece to ‘t illusts POPULAR When the have been cut out, they should be out later. together as shown in Figs. 5 and 6, rmer showing the middle section and tter the end sections. The gluing sure ach piece is exactly in its proper po After the glue has set thoroughly, off any surplus and work out all regularities with a wood rasp or with Then drill for which the hole small Put the together and finish smoothing and he ot sandpaper. hj = iii S nge pins, nails which appear to be the heads nge pins, are simply glued in place, 1s being cut slightly shorter than dth of the hinge, to prevent inter- e. The knobs used for the hinges ; +} the photo were clothespin heads, indicated by the dotted line in rhe handles Fig. s hree pieces, cut out according to the in are made hown in Fig. 3. After being p. they are cut out as shown in Phe escutcheons are shown in They should be made of stock in. thick. MECHANICS ONY For the trim can be scrollsay rather plain elaborate work, ved, manner desired. more carved or dec orated in any Inexpensive Farm Tractor for Light Work The principal parts of the tractor shown in the photos area Ford chassis and a light The sIon W three-speed transmission. front end of as milled fit the rear end of the Ford universal the extra transmi to 121\ joint, 1 ne om the front end of t aft, and a piece Was cut fT Ford drive s! the remainder w as milled to fit the rear end of the trans- mission. The rear spring was removed and the frame was bolted to the rear-axle housing. An extra rim was bolted to each wheel and the rear wheels were fitted with wooden lugs. A farm-implement seat was added and a few minor changes and the cost $17 tions were made, which made the completed tractor about besides the chassis, which the farmer had on hand. The two transmissions, working together, vive this tractor a very wide range of powe and eed, and it will pull i piow, irrow, pulverizer, roller or any other farm implement of about the same size. e examples are in- is guides to the of making up the of ‘| he de- ould har- d are capable ion. the trim is to be ap- the ated, they are therefore, in Two Views of a Light Farm Tractor, Consisting of a Ford Auto Chassis Equipped with an Extra Transmission of the Three-Speed Type; This Arrangement Gives a Wide Range of Power By raising the rear end of the tractor, the large rear wheels mav serve as pul- levs in running belt ma- chinerv.—Leland A. Dve, Boston, N. Y.

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690 POPULAR

~ thermom Thermometer Read in Incubator Swinging with This : ; Holder end of the horizontal arm, is suspended at the proper distance

screw, similar to those used on a the eggs. lurning the loop at above

depth gauge, com plete it. For dupli cating a diameter. the gauge is placed on the old piece and the pressed down until it touches the sur face: slide rod is then the nut is tightened to hold

the top of the ma chine the thermometer against the glass of the door and after it has been read, it is swung back to its former swings position. G. E. Hendrickson Argyle, Wis.

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Your Boy Will Like This Liner By HI SIBLEY if. toy-boat builder, having worked ut ingenious designs in craft powered rubber bands and electric steamer a fraction ickwork, will find a fasci- novelty. of the tless ships that sail the seven seas are ered with anything besides steam, and for it real Only a steamer affords a great thrill, e action and full-size There are no difficulties in making sound of a 1 } but if the young shipbuilder has a upright steam engine among his half the job is done. e white pine for the hull, pieces—bottom, main- which is three Lay out your out- which is 30 in. block and deck. 1 1 q sntral block, 614 in, wide and 3 deep, and, er boring four holes at the corners of old, saw out the inside piece with a the boiler. These can be bought at a very reasonable price; in fact, the engine used of this eighty-five cents and is in the original model cost only an exceptionally capable performer. Set the engine amidships with quite a tilt aft so that the crankshaft will be nearly with Locate the engine, but do not Now bore a hole through the stern just in line the propeller-shaft position fasten it. large enough to receive a brass tube of vg-in. inside diameter. This should line up with the center of the flywheel. Cut a length of stiff brass wire for the propeller shaft and straighten it. The propeller can be cut from a tin-can lid or, better, a sheet of brass: solder it to the Make ot plugs, for the ends of the propeller-shait tube babbitt, brass two lead bearings wire. by pouring molten lead or the latter being preter- OVERHANG __-~ AT BOW KEEL Fic. we park | ‘ e aon 1 eC ‘evhole saw, and then cut away for the nd stern, as indicated by the dotted bottom Fig. 1. Nail firmly to the the 5@-in block, your power plant. main and you re ready to install lhe steam engine best adapted to this model is a small upright type, in which the crankshaft runs through the center of able, into a hole bored in a block ot wood hav 1 ° 1 } ing a nail, of the same diameter as the shaft, in he center. When cold, the nail is easily pulled out, leaving a

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692 POPULAR peller shaft. File the plugs to a taper, so that can be driven the brass tube they into the ends of The plug at the propeller end can be driven in that at the permanently, but end should be enough to be taken out when assembling the other loose various thrust nut, for between parts. Some sort of washer, which mav be a example, should be battery used pro- peller and bearing It is almost impossible to line up an en- gine with a long propeller shaft accurately enough so that it will not bind using a universal joint. The lattet simply made and permits the shaft to turn very freely at all times without how ever, 1s Two brass or tin strips are cut, perforated and bent as shown, the flywheel and the other for the inner end of the propeller shaft one for They are connected by means of a brass-wire “spider,” shown in Fig Most cheap steam engines have lead ( 3 2° BRASS TUBE ~ —yp UNIVERSAL ASSEMBLY, a t eee | eg “SOLDERED ~~ || UNIVERSAL SPIDER LEAD BEARING ~~. is ¥ 5.0/4, BRASS WIRE —-——- SHAFT ASSEMBLY \ FRONT OF c CABIN ‘ ‘ “~ J an of the shaft and insert the spider. LINED WITH — ASBESTOS AND TIN MECHANICS flywheel and hub. and the drilled a short depth to receive the sma latter can be brass screw that holds the universal ar; \ drop of solder will lasten it curely more t Having assembled your propelk haft, bearings etc., in the \ boat. Vou Cat solder the universal arm to the inner end When ngine securely all turns freely, fasten the e to the bottom of the boat with screws. At this point, vou can test the boat out it the water, first having given the hull coat ot paint on the outside to Also it shield around prevent water soaking in vould be well to set a tin the engine high as the universal and open in front so that the wood will not scorch Tin, lined with asbestos, such as is used in pipes for hot-air furnaces, is this shield. Fasten per end of the propeller shaft tube to notched crossbar so that it will not vibrate Assuming that liner meets the excellent material for the up vour newly launched “engineer's” specification and expected performance, finish up wit] the deck The and cabins. directly over the engine, main cabin made of Ye O1 } in. stuff, and lined with tin and asbesto The roof is also of tin asbestos-lined with a large funnel soldered over the oper ing for the top of the engine. This funne ] TIN SHIELD AROUND ENGINE wae METHOD OF MOLDING BEARINGS Lis) | © TH? « Q| o LEAD BALLAST—

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POPULAR MECHANICS 693 m. _ yf generous proportions, so it can carry off the heat with inger of setting the boat on The entire cabin is hinged at back so that it m L\ be tilted up ! fueling or filling up the boiler. end can be A solid serve for the *-h at the front ide of tin or sheet brass. wood will heelhouse and lock of also for the after cabin or itch, which has no function except for ppearance. Che rudder is of galvanized sheet iron or iss, with a large clock gear at the top post for turning it. Masts, pstans, crow’s-nest, etc., are made as in- f the rudder licated in Fig 3. An important item ts e lead ballast, two triangular strips of id, on the sides of the keel. Paint the hull a bright red below the vater line. black above, and deckhouses cream, with doors, windows and portholes Varnish the decks, ive the funnel a red band at the top utlined in green, and Rubber Gasket for High Pressures Even the best grades of vacking for use with high-pressure steam sheet -rubber sures of 150 or 200 Ib., while the cheaper eracde ¢ eldom itistactor tO re ures over 100 Ib But the latter can be used for high-pressure work if it is pre pared in the following way: Cut out the gasket or washer in the usual way and give one ide an application of fairly thicl readv some cuttings made DV using’ a coarse Tasp ON a p ece ot bab gs will do in most cases, Sprinkle the surface and after the joint is heated up bitt Lead raspin but the babbitt is better. raspings freely over the sticky Install the gasket in the usual way tighten well steam. So prepared, a gasket will with eldom leak. nor will it blow out any made of the more ex Noble. lo- quicker than those 7 | pensive materia —lJames | ronto, Can.

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POPULAR Device Helps to Reline Brake Bands W he nN relining shown in the drawing will be found of auto brake bands, the jig > great assist- ance, It is made of 4 by 2-in. flat-iron bent double as shown. A small the holes in stock, pin to fit rivet the welded on. as bands is indicated, and a hole the size of the diameter of the pin, and ex- line vith it,is drilled in the opposite actly in side of the jig. In use,the brake band and lining are held in the the vise. The vorker in drill- ing holes through the lining, the pin fit- ting in the hole of the band directly un- derneath.—A. C. Cole, Chicago, Il.

yig, which is clamped in hole in the jig guides the Laying Out Angles Accurately Dividing a circle into equal parts repre sented by degrees, and the further subdi- vision of these degrees into minutes, is a task that curately. few mechanics accomplish ac However, here is a simple method of laying out angles by making use of the 18-hole and 27-hole index plates that are provided with a universal milling machine dividing head. This method is based on the fact that 40 turns of the mdex crank are necessary to cause the work to make a lence it is complete revolution that vances the work an angle of 360 divided by 40, or 9 lo subdivide this angle, use an index plate having a number of holes heing an even multiple of nine. With an 1&-hole plate a turn from one hole to the next represents 14°, or 30 min., and to the obvious each turn ad second 1°. By using the 27-hole plate, the movement from one hole to the next equals 43°, or 20 min As an example, suppose you want to scratch two lines that MECHANICS make an angle with each other of 20 2 min. Proceed as follows: Set the worl up in the dividing head and, with the 27 hole plate set on the index crankshait scribe a center line with the surface gaug: Two complete turns of the crank give 18 and a turn equal to 7 times the distance from hole to hole (or rs holes ) is 7% , Oo ) 2° 20 min. By following this method. an angle can be ratelv. If. laid out quickly and accu ou have to lay out an odd nun ber of minutes, the following will be of help. It gives the number of minute that a one-hole movement in the different standard index plates makes 15-hole plate, 36 min.; 16-hole plate, 33.75 min 17 hple plate, 31.76 min.: 19-hole plate 28.42 min.; 20-hole plate, 27.00 min.; 21 hole plate, 25.71 min.; 23-hole plate, 23.47 min 29-hole plate, 18.62 min 3l-hol plate, 17.41 min.; 33-hole plate, 16.36 mit 37-hole plate, 14.59 min.: 39-hole plat 13.84 min.: 41-hole plate, 13.17 min.: 47 hole plate. 11.48 11.02 minutes, min., and 49-hole plate Holder Prevents Soiling of Blueprints A Wisconsin W orkmen builder, noticing that soiled and eventually many valuable blueprints, devised a sin ple holder t ES protect then i consist two wood frames, hingee together and covered with celluloid sheets,ob tained at a near-by auto

ae <ce@gs oF Fy store, The blueprints were inserted CELLULOID SHEET 7 \ TACKED ON EAGH in the frame SIDE OF FRAME so that two floor plans or two elevations were exposed A iatch was pro vided to hold the frames together and fa- to view at either side. cilitate the removal or replacement of the prints.- (;. E. Hendrickson, Argvle, Wis. @Stain putty to match the finish before applying it on high-grade work.

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POPULAR Prevention of Scale When Hardening Stee! One of the things to watch out for when ning oxide that This is a matter for consid- steel is the scale or on it. n when the piece must be true to titer hardening, because scraping off it das follows: usually makes yoid this, procee scale undersize. Instead placing the piece to be hardened in an en fire, as is usually done, put it in a tainer made from a length of pipe, eaded at each end for a cap or plug ut out the air, and place the con- er in the fire. No scale can form be- se no air reaches the piece to be hard- | As a matter of fact, any sealed container can be used, depending It is brought to the the usual and water or brine—James Mec- Hartford, Conn. vhat is at hand. heat in way Counterboring Washers Some washers, about % in, thick, had e thinned down to Moo in. he only to do this was by counterboring, which involved the problem of COUNTERBORE 1 holding the washers se- curelyv. I ob tained duplicate la ) A al PILOT : counterbores 7 ‘ 1 ‘ wasHeR and removed ig the pilot trom . yi PILOT . is hale HOLE one, | itis | 1 in a chuck bolted to the COUNTERBORE Ne machine table The one with pilot still in place was held in the press spindle. With this set-up I laid her on top ot the pilotless counter e ind brought the other one down ut pilot passed through the washet nd ‘nto the pilot hole of the stationary nterbore. A glance at the set-up will rv that one of the counterbores will cut. if the washer turns around with the oving counterbore, the stationary one vill cut, and if the washer bites into the tationary counterbore, the moving one will cut—Harry Moore, Hamilton, Can. 695 MECHANICS AG ™ AUTO-SPRING LEAF “-=-DOUBLE HOOK A Strong and Convenient Strap Holder Is a Timesaver for the Harness Repair Man Clamp for the Harness Repair Man Belt ther 1 makers, harn and with repair men tradesmen who ] ive to work leather, rubber or fabric ips ona bench, will find the illustrated spring clamp very useful The leaf of a discarded auto spring is bolted to the underside of the workbench at the end most convenient, and, thro oh the eve of the ) is fas- tened a ide irom a length ot rol ( iTp r ed, Vl pitt gg or ti m1 i belt or strap s lac 1 flus] the end of the ben sho 1 tl hooks being ised and the rele ed to hold the rip ecure|\ the ta h | while the ther is kept immovable by the left hand Handy Pocket Saw Near] every mechanical de ce wu ed round the home eems to be assembled with screws When tight- ening or loos ening them me i apt to poil the slot in the head, but the slot be deepened by can readily means otf a short piece of hacksaw blade ill be fe It wv to keep such a piece on one’s ke eee

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696 POPULAR ee, ~ Wire Mesh, Replacing One Wall of Storage Shed for Seed Corn, Permits Proper Ventilation Storage Shed for Seed Corn Seed corn should have plenty of ventila- tion and also be adequately protected trom chickens, mice and rats. A good storage shed which meets these requirements has been constructed by an Indiana farmer, and is shown in the accompanving photo- graph. The corn is held on a number of wooden racks near one end, the wall at this end of the shed being replaced with wire mesh, This permits plenty of air and sunlight. The foundation and floor are well fitted to prevent the entrance of ro- dents.—]J. C. Allen, Lafavette, Ind Stop for Reaming with Drill Press In the manufacture of certain inter- changeable machine parts using a taper pin, difficulty was experienced in getting all the machine-reamed holes exactly the same depth. Various stops were tried-on the drill-press spindle, but they always slipped and it took too long to set them up. Finally the operator hit upon the idea of drilling a hole of the correct depth in a parallel on which the piece was taper- reamed. The reamer cuts through the piece and the end comes against the bot- tom of the drilled hole in the parallel, which gives a positive stop. This method eliminates all worry about the reamer slid- MECHANICS ing up into the chuck or the collar on the spindle slipping, and, of course, the time required for setting up is reduced to a minimum.—Arthur F. Parker, Philipsburg Pennsylvania. Tinning Cast Iron To solder cast iron or fill a hole or crack in it is difficult, because the surface can- not be tinned readily. Grinding, filing or polishing does very little good, and a really satisfactory job of soldering is seldom obtained. However, a railroad shopman accidentally discovered that the surface could be effectively prepared for tinning by sandblasting. This method is especially adapted to the tinning of bearings that are to be babbitted. The sandblasting cuts away the carbon in the cast iron, but has little effect on the metal itself, except that it leaves it bright and clean. The solder clings to this clean surface almost as readily at is does to steel or tin plate. Sandblasting greatly assists in obtaining a good welding job with a gas _ torch. When tinning the sandblasted surface, regular soldering flux is used.—Avery E. Granville, LaGrange, Il. Milk-Can Rack for Auto Truck One farmer who delivered milk to a neighboring town with a truck, was unable to load it with feed and other products on his return trip, because the empty cans, although light in weight, required all the space. To overcome this difficulty, the farmer built special racks on the sides of the truck to hold the empty cans, as shown in the photo. This left plenty of space for whatever extra load he wished to carry back home. Racks Built on Sides of Auto Truck Hold Empty Milk Cans

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Designing Radiator Furniture By THOS. W. BENSON bree USUAL steam or hot-water radi- ators are seldom things of beauty and hen making furniture to improve their it well to remember that e inclosure will influence the effective- s of the heating system. Practically | the heat from the radiator is dissipated convection, that is, by having the heat off the air flowing over and rough the radiator. pearance, is irried by Radiator inclosures ometimes increase, but too often decrease, e flow of air and thus lower the heating effect of the radiator In the illustration eneral types of inclosures are shown dia accompanying SIX ammiatically. The following paragraphs f — Le A ~ / ; . \ will enable one to select fur- \ | | niture that is in keeping with \ | ) conditions met with in his e pe TX TIIIITIIY + ‘A ~ rate of flow and improves t heating. A change in proportions will usually result in reduced efficiency and the arrangement shown is possibly the best fr the heat ing standpoint. Such an inclosure, on the other hand, does not prevent smudging of the wall and is not very decorative If screens are added, as in Fig. 2, with the opening B as in the previous case and A equal to R. the screens reduce the air flow and the arrangement is but 5 per cent better than the plain radiator In order to prevent smudging of the wall by dust ‘carried up b the rising tream of warm air, it is necessary to use a solid top and discharge the irm ait —— om | EC HY 2) £B HY ie front of the radiator. from ti J To retain full effectiveness, | ~~ pas censsensees \ particular heating plant. In Fig. 1, when dimension B is equal to ] Rk. the radiator will be 10 per cent more effective than before. This is due to the solid screen forming a well-defined path for the air circulation, which increases the the inclosure must have open- mes proportioned is shown in Fig. 3, where D is equal to R and C ts twice B. The structure is rather high but the discharge opening will reduce the flow any lessening of ot warm air and the radiator becomes that much effective. iCss 697

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698 The practice of mounting a shelf over a radiator for flowers or books, as in Fig. 4, is a very poor one, and affects heat radia- tion to a greater extent than would seem When the width of the shelf E is but half of dimension A in Fig. 1, there is a drop of 10 per cent in heat radia- tion. When E equals A, the reduction is 20 per cent and, in extreme cases, where E is one and a half times A, the loss is 35 per cent. Putting a sc-een in front, as in with the solid top E equal to A, results in a 30-per-cent loss, but an all- screen inclosure, as in Fig. 6, reduces the effectiveness only 5 per cent. Summing up, it is apparent that any at- tempt to use a solid-top radiator inclosure, possible. Fig. 5, Fitting Linoleum Snugly against Raised Concrete Border Cutting linoleum to fit snugly against a raised concrete border is a task that re- 4 WOODEN HANDLE 7 ‘ SHARPENED NAIU. LINOLEUM =O % PDT he, ‘ iS hg Sim, j CONCRETE ‘RAISED BORDER Device for Marking the Edges of Linoleum So That It Will Fit Snugly and the usual method of scribing is impractical in this The work 1s facilitated use of the simple tool shown in quires considerable care, particular case. by the the illustration. It consists of a 4-in. strap hinge, screwed to a 12-ft. length of 1 by 2-in. board, The free portion of the hinge is bent over as indicated, and a sharpened one of the other part, the point of the nail or screw is driven into holes in the nail being directly over the bent edge and consequently directly in line with the edge border. In the leaf is fitted over the edge of the linoleum as shown, and the handle is depressed to make a punch mark, which indicates the exact point where the linoleum is to be cut to make a snug fit against the con- crete border. The hinge is then slid along of the raised use, loose POPULAR MECHANICS except when it is arranged as in Fig. 3, will reduce the heat thrown off by the radiator It is possible to disguise the radiator wit! open or screen-top inclosures, while still retaining heating efficiency, but the dis advantage of smudging the walls is still present. Loss of effectiveness of the ra- diators can be offset by carrying higher temperatures in hot-water systems and higher pressures in steam-heating systems, but the forcing of the heater leads to coal Other alternatives are the use of larger radiators, or fans to circulate the air. faster. It is for the individual to de- cide whether his heating plant will permit the use of radiator furniture, and these facts will aid in an intelligent decision. losses. the edge and the operation repeated at 1- ft. intervals, leaving a row of punch marks that serve as a guide in scribing the cut ting line. This device eliminates the fre quent shifting of the linoleum necessary —Mary when scribing in the usual way Gleeson, San Francisco, Calif. Turning a Large Pulley in a Small Lathe We had a number of 16-in. pulleys to turn down on a 14-in, lathe, a job which seemed impossible at first thought. How- -ver, the illustrated set-up shows how the work done. A mandrel, on the pulley made a running fit so was which that it could be rotated. was mounted 1'4 in. ott center, as indicated. A lathe dog was at- tached to the mandrel near the tailstock, the dog being large enough to project be yond the ways of the lathé bed in order to prevent the mandrel from turning. A bolt was fastened to the faceplate to serve as a dog for driving the pulley.—C, Kug- ler, Philadeiphia, Pa. BOLT ~ be —PULLEY z=: —...3 Q a te == \J COLLARS —— = r LATHE DOG nt nl Sn Tie Set-Up Showing How a 16-In. Pulley Was Turned in a 14-In. Lathe

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POPULAR MECHANICS 699 Sawdust Cakes for Kindling Where a great deal of vdust accumulates, as the farm, good kin- ng cakes forthe kitchen ove can be made as fol- ws: Get a length of 3- tile and stand it on the uted end on a smooth oard. Make a plunger om a section of a small and fit a handle to it noneend. Mix up saw- enough flour iste to make a crumbly ust with but not too sticky mass. hrow some of this into e tile and tamp it down Then lift the tile off the cake and proceed to make another. When dry and hard, the cakes should be piled carefully in a dry place. One or two cakes will suffice to start the fire either by sprinkling with kerosene or placing them over lighted newspapers.—L. B. Robbins, Harwich, Mass, ith the plunger. How to Cut Duplicate Pieces on a Bandsaw It is often necessary to cut out a num- ber of duplicate pieces on a bandsaw. Saw- ing three or four at once means, of course, quite a timesaving, but the pieces must be held dur- securely together ing the opera- tion. An easy means to this end is to cut two or more tapered slots, about 1 in. deep, in two adjacent edges of the material as indicated WEDGE? SAW SLOT’ and then drive a small wedge into each slot. The wedges will hold the pieces to- gether firmly and prevent their slipping apart while the sawing is done.—Neil Nel- son, Kansas Citv, Mo. @ Aluminum castings may be ground on a disk grinder without filling the abrasive material, if a coat of paraffin is applied to the wheel. Rack Constructed from Lengths of Pipe Facilitates the Draining and Airing of Milk Cans Rack for Draining Milk Cans An Alabama simple rack for draining and constructed a milk cans. It consists of two lengths of iron pipe, One of them is held securely in farmer has airing arranged along a fence as shown. place by crosspieces, which are nailed to the posts them for is held in a similar way in holes drilled through and have holes drilled throug! the pipe. The other length of pipe milk cans are set on the and lean against the posts. The lower pipe, upside down, the upper pipe. dle is grasped and the cans To remove them the han- are dislodged from the lower pipe.—J. C. Aller ette, Ind. Lafay- Accurate Measuring of Keyways and Grooves When cutting kevwavs and grooves in machine parts, a very simple method of them accurately is to measuring use a pair of steel wedges, or an ad- justable parallel with which every man is ta- Place the the and _ slide them together until they are groove, letting the ends project. Then, by using the micrometer on the outside of the wedges, a true size can be obtained. shop miliar. wedges in groove tight in the

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How to Handle Brass Pipe By HORACE G. WOODWARD ] AM “right handy with tools” deal of When and do a threads on the pipe; six or seven perfect threads are sulticient, and more will sim ply weaken the pipe beyond the joint. Fit- great repair work about our make a new place. preparing to service connection with the city water main, I decided to have all pipes carry ing water for the house of brass. Be- starting the however, I fore iob, made some inquirtes about brass pipe “kinks” of knowledge about and to get such iobs. | am passing on some of the which main points may be use- ful to others doing similar jobs. It is necessary to remember that brass, being an metal to does not re easier work, quire the force that would be applied to iron pipe, either in the vise or the wrench, Working in stand- ard iron-pipe-size brass pipe, it is desirable, or the stock and dies. 1° 1 to split an 1ron-pipe coupling ] for the vise, for such-size pipe with a hacksaw, heet of lead over each half and insert these on opposite sides otf the brass pipe 1 in the vise. I was surprised to learn that threading may be done without any lubricant at all but a characteristic squeak is then p1 duced, hich may be avoided bv us 4 soapy water or oil. The dies are the same as for iron pipe, but should have perfect teeth, and these in the best dies are shaped to advance in the work like a cultivator plow, lifting out the shaving. Experts say that the stock should not be jerked when cutting threads on brass pipe. but pulled with a steady movement in order to insure perfect threads, and I find this method gives fine results. Another important thing in either brass or iron pipe is not to put too many deep 700 tings should have a good reinforcing _ bead, and a fitting that will extend upon the pipe be yond the perfect threads, great strength to the joint. The fit- should be of there is available viving tings good quality brass not iron. Friction wrenche should be used on the pipe turn elbows or tee and to I use a monkey wrench, the jaw extending beside the part that pro leways ‘ jects Sit pipe wrench may be used on brass pipe but has the same ° ‘ ‘ a ‘ . : objection as on @g ilvanized iron pipe, cu ting the pipe excessivel if not carefully handled. Pipe used at all on wrenches should not be Powdered rosi of the vise clamps o 1e friction faces of the wrench, will ove fittings. applied to the taces come the tendency to slip on the pipe. The amateur worker, and many plumb ers, may not realize the importance of reamin 1 and brass ¢ both ir pipe to re move the burr at the ends. I have used a 1 is purpose with satisfac have observed in %4-in tory results. | pipe a burr formed bv a wheel cuttet the capacity of the line When and fit tings are accurately threaded no filling or hich reduced fully one quarter. pipe dope is needed in the joints, but a paste of linseed oil and red lead is used by many plumbers to insure tight joints. laying in the ground ” brass, but suited to sustain Brass pipe for should not be ordinary “vellow annealed or otherwise settling strains.

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POPULAR MECHANICS 70) Cementing Tool Tangs in Handles 4 quick-setting cement for anchoring e tangs of small tools in wood or fiber indles can be made from pure shellac. uy the dry shellac and dissolve it in just nough alcohol to make a paste, which then put in a tin dish or can and ignited. mmediately after the flame has died own, and before the shellac has a chance cool and harden, fill the handles with he cement thus made, and drive in the ings, which should be heated. When ool, the cement will be found to be very trong and practically waterproof. Holding Small Steel Articles for Photographing When small steel or iron articles are to he photographed without showing any upport, a magnet can be used to hold them shown in the drawings. Fig. 1 shows the general arrangement. The back- ground is a sheet Of cardboard which is held to the base by triangular pieces of vood at sehind the back- ground and close to it, a strong permanent magnet is supported by a wooden rod, to which it is fastened with a few turns of copper wire. If the object is set against the cardboard, the magnet will hold it securely. When one item has been photo- graphed it is simply lifted off and the next one placed in position.: In this manner a vreat deal of time can be saved and re touching is reduced to a minimum be- cause no support shows on the photo. A discarded magneto magnet is suitable for each side. ay ¢ é 4 OBJECT V TO BE ’ \ PHOTOGRAPHED t \ 4 j CARDBOARD BACKGROUND —>— ce Permanent Magnet, Securely Supported on Rod, Holds Small Iron and Steel Objects for Photographing this purpose and, for very heavy ebjects, several magnets may be placed side by side, or a small electromagnet may be used instead. The current is taken from SUPPORT FOR VERTICAL CAMERA CARDBOARD —~ OBJECT TO BE BACKGROUND ~ PHOTOGRAPHED [ + FRAME SUPPORTING BACKGROUND Spherical and Other Irregularly Shaped Pieces Can Be Held Securely on Flat Surfaces current is only for short periods of time, the bat- will last very with a vertical camera, a magnet support is some- times valuable, especially if the object is irregular in shape or spherical, so that it roll over during the process of photographing, particularly if some machinery is working close by, as in factories. a few dry cells, and as the used Even teries long. may about or tip The arrangement in this case is shown in Fig. 2. The magnet can be held by a block of wood, a strip of brass and a wood Screw it to the block. Do not use a steel strip for this purpose as it will the magnet. being used to fasten short-circuit This method is not contined to steel or iron objects. Many other articles can be held as suggested if a short iron pin can be inserted in them. For instance, if a smoker’s pipe is to be photographed, an iron pin may be placed in the bore. The magnet will attract this and the object will cling to the background exactly like a solid steel body.—C. A. Oldrovyd, row-in-Furness, England. sar- Lanes.. @ When the drawers in a chest, cabinet, or other storage place for tools, stick or are hard to pull, apply a little grease along the sides and other bearing surfaces,

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02 POPULAR Kinks on Accurate Drilling I have been a few kinks in laving using work for the drill with great out sig press SURFACE PLATE” Fig.2 Fic.3 Sharp Tools and the Application of a Few Handy Kinks Will Help in Drilling Accurate Holes success \ large magnifying glass, held by a clamp so that the worker’s hands are free, is better than a small one. One method of holding the glass is shown in Fig. 1. It can be set to anv angle. If no precision center punch is available, the surface gauge or a V-block can be used asin Fig. 2. This keeps the punch at right angles to the work A flat kind shown in Fig. 4 scl iber of the sometimes Cc round one work. The punch should be accurate ground to a sharp point, which will facil tate marking the work at the intersectio: of two lines. Use a center combinat drill of a diameter smaller than that of t center-punch mark, and make the ang! sharper. For instance, if the center pur has an angle of 60°, that of the drill should be about 70 Then follow this up witl a drill like the one shown in Fig. 3.) Thi the drill follo If dividers are used, keep them W heneve1 scale graduated in fiftieths or inch, because the lines on has a tendency to make the hole. sharp at all times. possible, use a hun dredths ot an these scales are finer than those on more coarsely graduated rules. uations Such fine grad enable you to set vour dividers more accurately. If you are not sure of MECHANICS the accuracy of that 1S, the drill measure i. layout, drill small hole ler th rod ot » 17 over ail an the finished size, it the with smal sert correct size and a micrometer. Ii there is any error, use a round file to e large the holes so that the next-size dri corrects the error. I have found that it pays to blue the’work, even though it costs more than rubbing bluestone on it, as thi see the lines more clearl\ followed and the tools are kept in good condition enables you to lf the above rules are strictly no trouble will be experienced in drilling holes within limits from .003 to .005-in center-to-center distance. —Charles Kug ler, Philadelphia Pa Spotting Wall Studs The drawing shows how a carpenters’ hammer may be used to space off for hook them to After ing or othe cating points in baseboards, strip chair rails, etc., at which to nail the wall studs through the plaster. ’ 7 stud, by sound finding methods, one place the driving tace ot the hammer at this point and roll it forward over the claws, until the end of the handle strikes the surface of the board. The end has previously been scored, as shown ) that the mark comes exactly in line wit! he next stud, 16 in, from the first Ch Marked Handle Enables Quick Measurement Hammer for Stud Nails in Baseboards and the Like an accurate and quicker method than sounding for each nail or using a rule @ Crude petroleum oil, diluted with gaso- line, makes a good brown wood stain, re- sembling dark-oak finish,

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$e reree J © PoPULAR MECHANICS MAGAZINE PLAN 61-L.F 1 Flouse Complete for $2500" that home and If you are undecided New vou can build - buy that ca which to spend your savings on, the fol lowing idea may suggest how to have both and without pinching your pocketbogk for years to come. Why not build a little house? Yes, a very little house. Equip it as efficiently as a modern city flat. Build only enough house comfortable shelter, But don’t doll it up to look like a miniature mansion. Doll to give vou stvle and convenience. ing up costs money. Keep it simple. Re- member that above everything else it must be a timesaver. You will need that time to drive your new car. You would be willing to build such a house if it did not place a voke of indebt big city Che owner liked it so well, he decided to live in the house all vear round. And in a climate where the winters are cold. Motoring to and from the city was a matter of onl miles when vou can save on taxes vy ten miles. What is ten build- ing costs, upkeep and at the same time en- joy the health, happiness blessings of the countrvside? Here is how he did vated the cellar. hot-air furnace which keeps the comfy in all kinds of weather. Fullv insulated the sidewalls and ceiling to make the floors, house warmer in winter and cooler in summer. Used wallboard as an interior finish. house is of In every other respect the edness around your standard construc- neck for vears to tion: Frame with come. All right. A NEW SERVICE hingle roof, eithe Then study this To help our readers get started on one of life's wood or composi . most glorious experiences—building and owning - . plan and read the a home—Popular Mechanics Magazine will su; tion; siding exte storv of how the ply readers a one-sheet blueprint of the house rior. The house . : here illustrated for $2. This blueprint does away , mwwner built this with the necessity of first purchasing a com would look well house complete for $2,500. It started out as a lake cottage on the outskirts of a afford to build. plete set of plans to find out whether you can It contains floor plans, eleva 7 ; tions, a section, detail, size of joists, studs, etc walls. Or it might and also a brief specification tradesmen and dealers for with shingled side Submit it t he stuccoed building estimates ecoed. Now } study the plan and see how

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POPULAR

MECHANICS

to save time, space, labor and efficiently it works out

money. There's a large, in living with stone or brick fireplace \ viting room dining porch opens off the kitchen and This, too, can be used for lin ing room, living purposes or even sleeping quarters in an emergency. A compact i kitchen, fully equipped with cup board porch, a well-fitted bathroom and bedroom complete space, a rear one the equipment While there is only one main bed- | room a closet or concealed bed opens into the living room closet be-

from the side the fireplace. This adds sleeping extra accommo Saves dations and the cost of another

es

] Titers To GRACE

\ , wer

CSTONE HEARTH & PRE PLace “LIVING -ROOM- 13'O" 230"x =",

-Bep-Roonm- 90"

ae

board plaster. and did bed Partial cellar exca lath bed second replaced A closet with a

away room, vation saved a tidy sum This house may have started out as a summer cottage. It finished, how ever, as a mighty comfort able all-vear dwelling. Sav- ings were made _ without sacrificing any oft the comforts of the - family, and there was enough cash ' - - left for the pul chase of a more up to-date automobile The cost of build ° ing this house ob oe viously will depend " | | upon now thor a| oughly you equip it, and $1,000. A broad Same time-—it screened porch worth while to in- EDITOR'S NOTE: Popular Mechanics Maga- Be : : ae ee : stigate lis ide% stretches across the zine has prepared a new plan book, “Twenty vs tig ate thi lea entire front of the Popular Low Cost Homes and Ten Command of making space . ments for Home Builders.’’ These are selected ol 1 | ble dut house. You may homes and show labor, space and time-saving also do double duty, want to glaze this ideas. They are $5,000 homes and less. Send It is one of the s : S 10 cents in stamps to cover postage. Address - In tor, permanent Building Editor. easiest and surest living quarters. ways of accom- Further savings were made by making plishing that desirable purpose by keep- space and materials do double duty. Wall- ing down costs.