Popular Mechanics 1925-03: Vol 43 Iss 3

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& ARCH MUN, j IN; RADIO = 25 CENTS ren CL UBRARY LIZ | POPULAR MECHANICS MAGAZINE WRITTEN SO YOU CAN UNDERSTAND IT t REGO. TRADE MARK GREAT BRITAIN No. 410426

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A. J. Beall, Jr., Morgantown, W. Va., made $85,000.00 last year from his garage and Chevrolet Agency. George Smith, W. Alexandria, Ohio, makes over $800.00 month clear with his garage. Thousands of other students are now making from $50 to $150 a week. Before they came to school, they knew nothing about automobiles—now they are successful eC Pp men. You, too, can have the same success—all you need is the Training—McSWEENY Training. LUE: Vail Lowest Tuition Offer PI Have Ever Made! For a very limited time, I am making a very special tuition offer, the lowest in history. You’ll have to act quickly, though. AUTO GET a ee a F YOU are earning less than $40 a week, read every word. Why offers thousands of BIG-PAY JOBS—jobs where you are the BOSS, in Cincinnati, Chicago, Cleveland, Will Train You! —think of the prestige—the case of getting a big job when you can Bean Coup ‘I \\, McSweeny Trained Men Make GOOD Ordinary garage 8 weeks in any of my ics, and to make more money Home Training rou will be interested in my Home stay in the old job, with no futiuwe—no chance of ever earning muc) more than you are now? The Auto, Tractor and Electrical business Get out of the rut—be independent—be an Auto Expert. McSweeny, Operating Automotive Training Shops I operate Automotiveand Electrical Training Shops in Cincinnati,Chicagoand Cleveland. Think a moment what it means to be trained by McSweeny +d I hl say, “McSweeny trained me!’” That’s the magic phrase that has opened the doors of thousands of big pay jobs to my students. Auto ° mechanics make good money. After schools, you'll be ina posi- tion to boss ordinary mechan- than you ever dreamed of before you read this announcement. Course If you can’t come right away, ‘raining, backed by Automotive Train- ing Shops in three leading cities. My big 64-page, beautifully ' One illustrated catalog tells the 4 whole story send it * of hol I i Big Jobs free if you act at once, A joblikethis in »ny of my schools, J. H. McSWEENY, Pres., Dept. 1419 McSWEENY AUTOMOTIVE AND in Three Leading Cities -y 517-521 South Laflin Street, CH MLS. your special offer. POMS. de ce cescceccvecccsceseosence 1815 East 24th Street, Cleveland, Ohio so —a “‘bossing”’ job ‘4K IE with a future— this is what you can expect after 8 weeks Fe AUTOMOTIVE USE THIS CO & ELECTRICAL SHOPS MY SPECIAL OFFER McSWEENY TRAINING pete a : aa = = - 8 coupon to the school nearest you. Operating Completely Equipped Shops ELECTRICAL TRAINING SHOPS 9 ind Walnut Streets, berg no A ry Oth and Walnut Otrects | Dept.) S17-S21 So. Lettin Ot. | Dear Mac: Let me have the full details Cincinnati, Ohio 1419 Chicago, Ill. Address , I am interested in > Resident Cou Home Study ‘ (Check which you want to know abou

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if muc) siNess OSS, ou! Jand eeny | Can - has nts. »D year Wa D to 1ew sful you ng. ails 0! BS issUED MONTHLY H. H. WINDSOR, Founder London: Hachette & Cie., 16-17 King William Street, Charing Cross, W.C.2 111 Rue Reaumur Popular Mechanics Magazine 200 E. Ontario Street, Chicago, U.S. A. H. H. WINDSOR, Jr., Editor and Publisher & Cie., Melbourne: Gordon & Gotch 509-513 Litele Collins Se. —_——_——_ ———— To all other countries in the Postal Union All subscriptions are discontinued at expiration. utes examine ih date ated on your wrapper. SUBSCRIPTION: In United States and its possessions, also Canada, Cuba, and ne per year, postpaid - SINGLE COPY, 25 CENTS $2.50 3.00 Entered as Second Class Matter Sept. 15, 1903, at the Post Office at Chicago, Illinois, under Act of March 3rd, 1879. Entered as Second Class Matter at the Post Office Department, Canada. Published monthly by POPULAR MECHANICS CO, Copyright, 1925, by Popular Mechanics Co Copysright in Australia. Copyright in France Vol. 43 Contents for Advertising post offices used as billboards........... 400 recruiting Oe er ES in 58 als ko sclera oes 403 telescope tests for outdoor signs........... 362 Airplanes made nearly noiseless .............-+0--055: 381 plane wins tug of war with auto............. 458 Architecture—Domestic—latest ideas in ‘building your home 442 Au :tomobile—daily trips of nation’ 5, 300,000,000 miles 451 Automobile Driving—two steering wheels on 4 Automobile Racing—racer with front wheel drive.... 433 Au tomobiles—Design “raindrop” ies for automobiles 387 touring car and delivery truck has seats that fold on floor 401 A comebiion eeanens ee — enpetins air pump run by fan 464 dash control for atk ee ea 369 enh GE SE hc 06a 54 ccu pone welwanp 441 Automobiles—Lubrication oil gauge lights signal lamp. 449 heater and strainer for oil 468 Automobiles—Muffiers—wrecked by gas blast to test their value ee EE 01 At :tomobiles—Radiators—exhaust gas used to help keep engine cool . é Ned oeceesneeseecees 16 Aviation airplane taxis for inter-city service.............. 440 airplanes as pilots for ships in ‘invisible hands’’ to guide planes by e!ectric ‘cables 460 pioneers to be carried by airplanes to Canadian wilds 433 Bench—Wheelbarrow—for the lawn 381 Bible—Antiquities—shining tower of David discovered 393 Books—art of ancient makers revived 3 Boots and Shoes detachable heels easily fitted . 417 300,000,000 shoes manufactured in U. . S. in 1923. 410 Brake—fitted on hand truck.... 450 Buildin cathedral rises and falls with tide 384 erected in wooden shell to protect workers 425 model galley as realty office 425 Buttone-—Co llar—for tight neckbands 458 Cameras—adjustable lens for hand cameras ; 427 Celluloid—films for use with X-ray studies...... 469 Chair—high chair, cradle and buggy in one....... 384 Check—protector carried in pocket 357 es on outside of church teaches Bible . Fe" 91 om ieee clock imbedded in sidewalk. 426 oa mining under ice fields in Arctic 433 tested with X-ray camera. ......... 385 use of raw coal called a crime oe 416 Copyholder—magnifier for typewriter. Biadteae. 465 Cotton—made to wear like wool... ........ 382 Crane—portable, built like sawhorse........ 402 Crimes—fortunes made in prison cells..... 356 Crutches—on casters built for dog 450 Dictaphone—hooked to radio “cans” programs 386 Disabled armless artist holds brush with teeth exe 357 D blind workers build own radio sets 411 ogs dog teams, “autos” of the north. 392 ea eee 374 March, 1925 “Dragon”—run by men for movies. ........ Drills—diamonds replace tools of steel , .. 468 Earth—eclipses show days are lengthening. ........ 425 Electric Lighting portable plant operates automatically 416 reflector coating on electric bulb 402 Electric Switch—glass plate on electric wall switch 386 Electricity single crystal copper bar carries more current 357 sound of electrons heard by radio 402 Engraving—girl gem engraver . 441 Farming—electricity as modern farm hand 415 Fashion—blown glass trimmings on gowns 463 Files—card index that “thinks” saves work 400 Flags—sewing stars wholesale on flags 415 Flashlights—stick for traffic police 459 Fogs—eye of camera to pierce fog and smoke 361 Foxes—man-made dens for captive 356 Fuel—kitchen range using “‘near-coal” 469 Furnace—electric, for heating knives 363 Furniture—fasteners for loose chair rungs 463 Games—basebali game with dummy batter 441 Garages—built with revolving floors bn Gases—tear gas bath to rout stowaways Golf—courses laid out on lawn jens Gyroscope—how the gyro makes the earth work 395 air—cabinet for removing excess Heart—heartbeat charted by electricity ‘ 362 Heredity—dizzy mice used to test heredity laws 464 Hoist—portable, for garages 459 Horses—scarcity of white horses perils supply of violin bows 468 Horticulture—burlap “bonnets” around trees. 383 Hose—metal mender repairs 458 Household Devices 466 Incubator—revolving, turns eggs and controls moisture 470 Insects practice arts known to man ‘ 392 toilers revealed by movies , 461 Kitchen Utensils—ribs on bottom save gas. Lenses—glasses developed for color blind Light—egg-shaped bath chamber aids light treatment. 411 Linen—at half price of cotton 449 Locks and Keys bicycle converted into key factory......... 394 button lock on inside door knob......... 424 Loud Speakers—horn replaced by cones 495 Louisiana—area of state increased by river cpus 465 Mail Box—safe in apartment house 449 Manicure Sets—worn on neck ribbon 373 lans to send by radio 440 Maps—signal corps Marking ‘edie fth wheel marker on auto truck 38$ Masks—padded ear mask worn by pugilist 355 Measures and Measuring Instruments ranger’s horsepower cyclometer voltage tester used without lamps er Drawing—copies of drawings by dry proc Mental Teste—cab driver mentally qtr than college student 27 Metals—dirt cause of metal “fatigue” herkwod 417 Micrometers—with dial face, pocket size. .......... 382 Mines and Mining—self-rescuer for miners........ . 381 els logging group carved from wood........... 425 ae plaques from sealing wax......... 362 i ns) as Gi ahnee dee Ode ewe ae 463 Monkeys—markets at steamer Me iavaddivéawads 363 pteitiiaaal on Page 4]

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Moving Pictures—Stage Mechanism—when the plot requires a fire A: Moving Pictures—voice recorded in talking movies sauasioe~—opeed of finger and vocal muscles ’ usical Instruments—saxophone played by slotted slide Ocean—deepest well shallow ounnorss to holes in sea Office Supplies—memo clip on telephone saves time. . Oxyacetylene Welding—gas tank regulator Painting—world-famous restored .. = Paper amount of wood in ye gl page newspaper cups made in sanitary cabinet lumbermen put insects to work stripping bark from logs . ePhe: tar coated, used as water pi Pavement—trolley scoop rips up old asphalt Phones connecting phones to amplifier fiber sound disks get better with age Photography—-hunting human game with a camera lugs—twin fuse plug gives double service Police rogues’ gallery of handwriting siren to warn of prisoner escapes heard three miles Poultry automatic pocket poultry killer breed hens that don’t cross road. : Press (Clothes)—electric presser for trousers inting—press prints many colors at once Prisons—sunlit cells in circular prison house Prize Offers and Announcements ; Puzzles—cross-word puzzle centuries old. Radio correct grid leak important metallic grid leak insures permanent resistance noises not caused by static questions and answers radio sets affect watches short waves promise long-distance radio Radio—Aerials not a menace two unusual loop aerials Radio Apparatus—redecorating the radio cabinet adio Construction—things to avoid iff building sets Radio Photography—pictures sent across sea Radio Receivers lamp, receiver and loud speaker combined operates on lighting current Popular Mechanics’ Superheterodyne, Part II Radio Transformers—special unit for tuned radio fre- quency sets ; ; Railroads—U. S. early builders laid ten miles of track a day rail motor cars for passenger use. Registers—mechanical cashier makes change and ad- mits person to trains Rotor Shi illess ship startles shipping men Ruby—real, can be told from false ‘ ety Devices and Measures—signal rings bell, flashes light, counts cars 4 Safety Movement—safety first taught children by honograph ; Sawdust—salvaged, used for walls Saws and Sawing Rigs—portable motor-driven hand- RES eR FPR Screws—with square niche in head. Silos—can be built in twelve hours Skyscrapers—university’s cathedral of learning to be fifty-two stories er Sound—bandstand set with loud speakers for football returns . Statues—monument of Sweden’s champion of liberty Steamships and Steamboats—liners carry water enough to ie | town a week Pater ; Steel—new, for use in shipbuildin Sterilization—steam sterilizer for Street Railroads gas-electric bus saves fuel tractor two blocks long operates on one-cent fare Street Traffic Regulation Pe run sidewalk through building to widen street tile traffic signs in street paving Submarines—electric, like monoplane Swimming—dry land, rack teaches right strokes Tables—sanitary table attached to bed Testing—tester tells if fruit is overripe. Tires es alarm for pneumatic tires . fabric patch for casings mends balloons or cords. man-made bumps test . A ; oys : bells in toy balloons. y kitchen cabinet with roll front sidecar attached to child’s cycle Trucks—electric, that hauls and piles tal tools. [4] [Contents—Continued] 353 . 503 5 496 503 458 391 386 400 372 .. 459 . 451 . 464 Typewriters—run by motor United States : Army—training the eyes and ears of Navy—behind the big guns of the Upholstery—air filled for autos Vegetables—cross between corn and squash. Waste Products barge rids ballast water of oil - : , . 3 two scrapped warships furnish city electric power = 4 bk a garner far south today Whistles—pupils taught to imitate birds Wrenches adjusted by push of thumb worked with single hand Writing—to fox trot record ‘ — Gardens—costly animals less popular than cheaper ones one AMATEUR MECHANICS Ants—getting rid of : - ret 47 Automobiles—Equipment and Supplies—ship-type ven- » ee : Automobiles—Locking, etc.—foiling the auto thief Automobiles—Radiator—thawing coon Automobiles—Repairing—bacon rind auto bearing Bells—method of distinguishing extension Benzine—to deodorize Blowtorch—stand Brush—improvised scratch Built-In Furniture—Part IV—corner china closet Cash Register—double-duty Clocks—easy way to clean Curling Iron—holder for hot Fishing—with umbrella Garages—Equipment and Supplies—washing the car chassis Gate—sliding Kitchen—well-ventilated summer Kitchen Utensils—vegetable slicer Lighters—electric for water heater... . Noise—cornstalk noise maker ; Paints—testing painted woodwork Perambulators—storing the baby carriage Photography—cleaning developing trays Poultry alvanized-iron poultry hopper letting chickens unlock door Rheostat—how to design a water Saw—one-boy Solder and ee oeeaing for home mechanic Stencils—easily made Stovepipes—hoiding, securely Swing—how to make a Venetian swing Toys balloon trick making trapeze artist toy Treadles—for hand grinders Windows—handy raiser SHOP NOTES Acids—acid-proof table top Automobiles—Repairing removing Ford-truck engines turning stiff crankshaft Brass—coloring gray . : Bushings—using spindle-body bushings twice Calipers—transter-caliper attachment Carburetors—dust filter for tractor carburetor Chest—durable machinist’s tool Circuit Breakers—making simple Concrete ; posts protect pedestrians sulphur strengthens Dairy—steam sterilizer for utensils Drawings—making from photographs Granary—handy door Po ee ratchet athes—safety attachment for Markers—marking grain bags Mechanical Drawing—instrument shelf Plaster—paint keeps lime plaster from setting Rubber—inflating vulcanized tubes Signs and Signboard rotecting railroad signs Stumps—making burn themselves : Swi self-feeder for hogs.... Swine—homemade Taps—tapping blind holes Trucks—for moving long bars . Twine—cutter, safety . aa Washers—locating punches for spindle washers Welding—substitute for welding rod Wool—collapsible baler mere 4% 393 408 38 463 392

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oaae eVeeeeesse ___-,-—l—~—‘O™ONN —S,—“‘( il b le , in bottle | 7 ” of the north 392 of eS ~ dog teams, “autos © the 374 Oe Be to train yOUT ..---erserseerrrrr® t steamer docks....-----> 363 [Continued on Page 4] POPULAR MECHANICS ADVERTISING SECTION 95 : . There’s more life in \ EVEREADY HOUR EVERY TUESDAY AT 9 P.M.,E.S. T. Eve rea d y Batter! es For real radio enjoyment, tune in the Eveready Group.” Broadcast through Buy Eveready “B” Batteries and you get WEAF NewYork WEL Philadelphie electricity in its surest, safest and most com- WJAR Providence WCAE Pittsburgh pact form. They reduce your operating ex- vel oo wen Buffalo pense. New developments in the Union Carbide and Carbon Research Laboratories, Inc., have been converted into new manu- facturing processes in the Eveready factories. Good as they always have been, Eveready “B” Batteries are much better today. The Eveready achievement of giving you more hours of “B” Battery service for less money has cut the cost of running receivers in half, and in some cases to a third. There is an Eveready Radio Battery for every radio use. Manufactured and guaranteed by NATIONAL CARBON COMPANY, Ine. Headquarters for Radio Battery Information New York San Francisco Canadian National Carbon Co., Limited, Toronto, Ontario No. 74h Radio Batteries Dey Cm ~they last longer Ks te ' Ww ‘4 ANS Wi WAL q Battery im proves quality, saves “‘B” Batteries Price 60c

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Welding—substitute for welding rod... sty 520 Wool—collapsible baler recente 34 ee Trucks—electric, that hauls and piles 468 This News-Reel Cameraman Is Steadied the Intrepid Photographer—See Page 452 Swinging over Dizzy Heights from the Top of Eiffel Tower in Paris, by a Steeplejack Whose Harness Supports

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ST TF OS Popular Mechanics Magazine REGISTERED IN U. S&S. PATENT OF WRITTEN SO YOU CAN UNDERSTAND IT il. 4. w “MARCH, 1925 No. 3 Radio Picture Transmitter in Foreground, with Operator Placing Film on Rotating Drum Pictures Sent Across the Sea by Radio Wireless Waves Transmit Photograph to London and Back Again so Rapidly That First Part Arrives While Last Is Being Sent be: successful experiments by in- ceeded in sending a picture of a message ventors who achieved the same result in Japanese characters from Washington ilmost simultaneously and demonstrated to Boston, but discontinued his demon- t within four days of stration temporarily each other, have added when it was discovered radio picture transmis- that the old naval sta- sion to the successes of tion at Anacostia, near wireless. In the first Washington, utilized experiment pictures for the transmitting were sent by radio from end, did not have London to New York enough power to force ind one made the round the picture through trip, being dispatched static and code interfer- from New York to the ence. The Japanese British capital, where it characters were re- was automatically re- ceived and recorded broadcast to this coun- plainly, but the same try, the first part of it film bore so much inter- being recorded side .by fering code that the in- side with the sending ventor said all that machine which was still would be necessary to dispatching the rest of read the picture was a the photograph. The code book. The trans second inventor suc- Removing a Picture after Its Ether Journey atlantic demonstration,

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SPECIAL RADIO . PHOTOGRAPHIC RECEIVER > ELECTRO ; MAGNET 4 i ‘ AMPLIFIER RECORDING “CYLINDER Wnew york POPULAR MECHANICS 9 MILE RECEIVING ANTENNA = + -— _ STANDARD VACUUM “TUBE AMPLIFIER IN RECEIVING BUILDING LAND LINES-7OMILES RIVERHEAD TO NEW YORK coming on the heels of the successful tn- troduction of tele- phoned pictures early last summer, has made it possible to take pic- tures of happenings abroad and send them to America the same_ || day, and then redis- tribute the picture by the telephone process to all parts of the country. Besides transmitting pictures, an old Chinese _ pro- verb, “One Picture Is Worth Ten Thousand Words,” also was sent across the ocean. Owing to the fact that the receiving ap- paratus had not yet reached London when the experiment was the shading of the original negative. ‘Th: light beam playing i: the camera gives a sec ond picture, in the form of a photograph ic negative, which ca be developed in th« usual way, and from which as many prints as are needed can be made. The beam of light travels over ev- ery bit of the film, its intensity being co1 trolled by the strengt' of the radio signal and that in turn b the amount of lig! which can pass through the shading, of the original picture hence the film at th receiving end, when l - developed, gives a made, all the transmis- sion was from Eng- land to America. The process, which was in- vented by Captain R. H. Ranger, of the Radio Corporation of America, utilizes a light-sensitive bulb to translate a beam of light, passed through the photographic film, into electrical impulses, which are then amplified and modulated in an ordi- nary radio-transmitting set, in the usual manner. At the receiving end an ordi- nary receiving outfit picks up the electri- cal impulses and passes them back through a light-sensitive cell to be re- flected as a beam of light on a film in an especially constructed camera, and also to actuate a delicate lever holding a foun- tain pen, playing over a piece of paper at- tached to a revolving cylinder. Thus the picture is received in two ways. The paper gives a pen drawing, the lines and their length and heaviness being controlled by Diagram of New York Receiving Apparatus, Nine-Mile Antenna and Recorder, with Prince of Wales’ Smile as Received by Radio accurate reproductio: of the original. Per fect synchronism is maintained betwee: the motors which drive the revolving cy] inders at the sending and receiving end. though these motors are separated by 3,000 miles of land and ocean. They are kept in step by a tuning device which employs the constant pitch of a tuning fork. Some of the received pictures were very good, and others not so clear. Based on present wireless tolls, the average time re- quired to transmit a picture would repre- sent a telegraph cost of about forty dol- lars. Magazines and newspapers fre- quently pay more than that for a picture of great importance, while to picture syn- dicate services supplying many news- papers the cost is not at all prohibitive. The other inventor working on the same lines, C. Francis Jenkins, utilizes princi- ples much the same in his device.

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POPULAR MECHANICS 355 Thirsty Liners Carry Enough Water to Supply Town for Week Enough fresh water to last a small untry town a week or more must be irried in the tanks of the big ocean liners to supply the demands of the greedy boil- ers and the wants of the passengers on a ingle trip. One big ship carries about 5,000 tons for each voyage across the At- lantic. It is estimated that each passenger needs about five gallons of fresh water a lay for all purposes, and as passengers and crew together make up a company of 3,000 or more on the average modern grey- hound, the ship is provided with special tanks along the sides to carry the supply. Steam Sterilizer for Dental Tools Has Automatic Shut-Off Operated with alternating current from a wall socket, a.steam sterilizer for den- tists’ instruments, automatically shuts off at the proper time, and is so arranged that the hot tools can be dumped out upon a napkin without touching them. Water is poured first into a small timing cup to secure the right quantity and then into a porcelain heating chamber below. There it acts as the conducting medium and be- gins to boil almost instantly. In about twelve minutes, it has steamed away. This automatically shuts off the current. In- struments dry quickly, are not subjected to lime deposits and are easily removed without danger of burning the fingers. Emptying Tools, after Sterilizing in Steamer and Filling the Heating Chamber with Water Padded Ear Mask Worn by Pugilist for Protection While Sparring “Cauliflower” ears, sometimes exhibited with more or less pride by veterans of the prize ring, have little appeal to one welter- Pugilist Wearing His Padded Mask to Protect Ears While Boxing with Training Partners weight fighter. While sparring with train- ing partners, he wears a specially con- structed mask that completely covers his ears and reduces the force of blows that land upon them. The protector is fas- tened by a cord that is tied under the chin, and by a band attached to the front and extending to the rear, where it connects with a side strip. Garage Built with Revolving Floors to Save Time and Storage Space Considerable saving in parking space and time required to get the cars in and out, is claimed for a revolving garage Lon- don engineers have devised. Its floor is built in a series of separate concentric rings and each has a number of inclosures to hold an auto. Without disturbing any of the other machines, any car can be moved out simply by whirling the circu- lar floor upon which it rests until its com- partment is opposite the exit. Spaces are left on each of the outer rings to permit access to cars at the center. A garage of this type, with five floors, will hold 100 cars and because of the economy of space, lower storage rates are anticipated. @ About one cent per day per person is spent for electric lighting in the home.

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356 Fortunes Are Made in Prison Cells Despite Handicap of Steel Bars While serving a two years’ sentence at Atlanta, Ga., a prisoner invented a port- able ice-making machine which is now Silver Foxes Grow Large and Sleek un- der Proper Care and Lose heir Wild- ness While Being Raised for Their Pelts Another convict de- being manufactured. vised a tool for making shoes, and when he was released from the Maryland state prison, he accepted a position at $5,000 a year with a shoe firm. A banker was able to build up a lucrative investment busi- ness that netted him $300 a day while in prison. A man convicted of the murder of a New York lawyer and sent to an asy- lum for the criminally insane, nevertheless managed the investment of the $20,000 he possessed in such a way that it grew to nearly $250,000. POPULAR MECHANICS Man-Made Dens for Captive Foxes Duplicate Natural Haunts With the raising, an growing development of silver-fox industry that is said to be because of the small rapidly amount of space required and the profits, increased attention is being given to the construction of the dens, that the animals may live in surroundings as nearly like their na- tive homes as possible. As they are used almost exclusively by the female to hide and rear her young, they are con- sidered highly important to successful breeding. The walls are made thick to keep out light and noise, and an inner chamber and runway leading to the den are constructed to give the animal a sense of security. The sides of the pens are sloping and the floor is covered with woven wire so the animals cannot burrow out.. In winter time, the favorite place for the foxes seems to be on top of the dens and here they curl up together and sleep in the open regardless of low tempera- tures. Fox pelts sell at from $200 to $1,000 each, and pairs of the animals for breed- ing bring higher prices. @ Weighing more than a ton, a Holstein cow owned by the University of Idaho, produced 20,995.7 pounds of milk in one year.

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© POPULAR MECHANICS 357 Airplanes as Pilots for Ships in Fog Guide Way into Harbor Employment of airplanes to guide ships nto harbors in foggy weather has been uggested following the experience of the irrier “Langley” that was piloted safely nto Pensacola bay with the help of avi- tors. The boat arrived at daylight. A ight fog reduced visibility to four miles or ess, and though the low shore could be seen, there were no marks to guide the navigators to the wharf. Several air- planes were carried on the flying-off deck for immediate delivery on land. One of them was launched and after circling about, the entrance was located and by means of signals, the flyer pointed out the proper course. Check Protector Carried in Pocket Stamps Figures in Colors As a means of safeguarding bank checks against raising and forgery, a pocket-size protector, for which patent has _ been asked, stamps embossed figures in two or three colors. The device, which is disk- shaped, resembles a dial and can he carried without injury to the clothing. Pads of different shades of ink are provided, so secret combinations of color may be ar- ranged and registered with banks by the owner, as a key to aid in establishing the genuineness of the signature. Each char- acter can be quickly cut into the paper by pressure of the thumb on the stamp, per- forating the written inscription to make NG MOTOR PRooUCTS Co. gawe Ravers tA } ’ ee ~- * r eens LA x Letivagit 5 & Vest-Pocket Pro- tector Which Stamps Colored Figures on Checks to Foil Criminal Tampering erasure difficult. Specially designed let- ters and figures may also be furnished on the protector as an additional guard. Armless Artist Holding Brushes in Teeth Paints Pictures Holding the brushes in her teeth, a woman artist deprived of both hands and parts of the arms by accident has succeed- Armless Artist, Holding Brush in Her Teeth, Putting Last Touches on a Painting ed in painting many attractive pictures. By developing a delicate control of neck movements the artist applies the colors with a proficiency rivaling painters having all physical powers. Even on difficult por- trait work, the disabled craftswoman eas- ily reproduces likenesses which are highly valued for their workmanship and beauty. The armless worker uses ordinary mate- rials and can manipulate pencils and other drawing accessories with little effort, al- though she employs a horizontal surface instead of the usual upright easel. Single-Crystal Copper Bar Carries Thirteen Per Cent More Current Copper capable of transmitting thirteen per cent more electricity than present conductors has been produced in small bars made up of a single crystal instead of an aggregate of closely packed ones, such as are found in ordinary metal. One of the drawbacks to long-distance power transmission has been the energy loss due to resistance of the wire. Should single- crystal copper conductors become a com- mercial possibility, smaller wire could be used and practically twelve per cent of the copper in transmission lines could then be released for use in other fields. The crystal bars were made by gradually heating and cooling pure copper in an electric furnace. They were about the size of a lead pencil, but if bent, the metal lost its special electrical properties, the large crystal being transformed into a mass of smaller ones.

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308 POPULAR MECHANICS Copyright, R. Horlemann The Rotor Ship “Buckau” Being Driven » | Its by ag een Rotor Towers in the First Test Run on the , ay at Kiel, Germany “Sailless” Ship Startles Shipping Men Revolving Towers Extract Power from Changed Air Pressure and Save Eighty Per Cent of Cost of Operating Vessel A REVOLUTION in freight shipping, where economy in operation and not speed is desired, is forecast by shipping men as the result of the invention of a “rotor ship” by Anton Flettner, a German engineer. The invention, hailed as the first new development in sailing ships since the earliest navigators discovered they could utilize the wind’s power, has been tried out successfully, it is reported, on a 600-ton schooner at Kiel, and two more ships of the same design are now under construction. The motive power of the Flettner rotor vessel is two hollow steel towers, ten feet in diameter and sixty-five feet tall, built up of thin steel plates and mounted on pivots on which they are re- volved by nine-horsepower motors. The power which moves the ship, however, comes not from the revolving towers, but from the air which strikes them. They are, in reality, sails, but the manner in whieh they extract power from the air is based on an obscure natural phenome- 4 non which is so little understood that even scientific men have trouble in explaining it in simple language. The phenomenon is what is known as the Magnus law, or “Magnus effect,” a discovery made in 1853 by Professor Mag- nus, a German, who found that when a current of wind struck a rotating cylinder it exerted a force approximately at right angles to the direction of the wind. The discovery interested scientists, but they found little practical application for it. Artillery officers measured the amount of the effect and made allowance for it when firing in a cross wind. Tennis players also discovered it, and many years ago Lord Rayleigh wrote a treatise on “The Irregu- lar Flight of a Tennis Ball,” but -until Flettner developed his rotor ship about the only persons who had found a way to utilize the Magnus effect were baseball pitchers. Their curve balls depend entire- ly upon this counterforce for their curves. Flettner himself did not know of the

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POPULAR MECHANICS 359 Pe emia a n a eRe wre al A ™, yr ne | ; | | | ' | b é i i t ; ca é i 4 ; : } a | ' d } SUCTION —— PRESSURE en FIXED HOLLOW 4 ne STEEL MAST---+ _ “ f ROTATING CYLINDER as ROTATING CYLINDER a i g- >HP. ELECTRIC MOTOR CRIVING THE ROTATING BRIDGE , a SYLINDER THROUGH at er EARING a5 7 | ht eS he Se Oe ee ey it. ol en so rd u- til ut to ma 4 all ‘e m . OE AE AOE. 0 8 BEE PS. C) The Ulustrated London News; Insert © BR. Horlemann he Diagram of the Rotor Ship Showing Vast Cargo Space Made Available by Eliminating Usual Engines, and, Above, a Close View of One Rotor

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360 long dead professor and his discovery when he started work. He had invented a patent rudder which bears his name and was trying to devise a sailing ship with metal sails, mounted in sections or vanes like the familiar auto-radiator cover, ex- cept that the vanes should extend verti- cally instead of horizontally. His idea was to have fixed sails, with the movable vanes controlled by power, to eliminate the large crew of sailors needed to handle the sails of an ordinary ship. During his experiments he stumbled upon the effect first observed by Magnus and that led him to the professor’s earlier reports. He con- structed two identical ship models, one equipped with ordinary sails and the other with two small revolving towers moved by clockwork, and experimented with them in the glass-inclosed wind tunnel at Goettingen university. The experiments were so successful that a motorship com- pany commissioned him to fit large-scale rotors to one of its vessels, the schooner “Buckau.” The first trials were made in a November gale, and the vessel maneu- vered perfectly. It outran other sailing vessels, and even passed freight steamers. The experiments showed that when the towers were revolved at about four times the velocity of the wind that-struck them, the maximum speed was attained. Turn- ing at 100 revolutions per minute, the towers, or rotors, develop a circumferen- tial speed of about fifty feet a second. The effect of the wind striking the revolving tower is an increase of pressure, with a decrease of wind velocity, on the side where the wind strikes; and a decrease of pressure with a corresponding increase of velocity, on the opposite side. The pecu- liarity of the Magnus effect is that the area of decreased pressure and increased velocity, will, at certain tower speeds, ex- POPULAR MECHANICS tend as much as three-fourths way around the tower, while the increased pressure is confined to the other fourth. With th« tower operating at four times the wind velocity, the pressure developed proved to be about fifteen times as great as th: winds effect on an ordinary sail of the same area. The result is that a rotor ship with only one-fifteenth the “sail” area of any ordinary vessel can obtain the same speed, while at the same time it is more stable, easier to control, and can be op- erated by one man from the bridge in- stead of a large crew. Equally important is that the rotors can be stopped, started or reversed in a sec- ond, as contrasted with the comparatively long time it takes to make sail or take in the sails on a full-rigged vessel. On cer- tain routes—particularly the Asiatic— where the trade winds may be counted on to blow ninety per cent of the time, it is estimated that a rotor ship, equipped with an auxiliary engine for use during calms, could be operated at a saving of eighty per cent over a sailing ship. The steel towers on the “Buckau” are so built that frictional loss of power is reduced to the minimum. A hollow stee! tube runs up the inside of each tower for three-fourths of its length, ending in a pivot, on which the revolving cylinder is hung. The nine-horsepower motors had no trouble in revolving the cylinders dur- ing the tests. No matter what the veloc- ity of the wind and the speed of the ship, it requires no more power to revolve the towers than it does in a perfect calm, since they are perfectly smooth, with no vanes or projections. By altering the speed of one tower it is possible to turn the vessel to one side or the other, and by reversing both towers the ship can be moved backward. =e, vs DIRECTION OF WIN ROTAT Sete - ViMORERS i THE ROTATING | = anes 1 Steere Copyright, The Illustrated Lendon News The “Buckau” Can “Sail” Almost into the Wind, as Middie Diagram Shows, While Greatest Speed Is Attained When Course Is at Right Angles to Wind, on Right

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= 8 ee RE TE oF 2 — i. = | POPULAR MECHANICS 361 rolley Scoop Rips Up Old Asphalt and Loads It on Cars scoop which rips up old asphalt pav- from between street-railway tracks loads it on cars in a fraction of the Art of Ancient Book Makers Revived as Ornament for Modern Works Recalling an artistic practice of old-time book craftsmen, modern binders are re- viving the custom of decorating leaves of volumes with pictures that can be seen onfy when the edges of the pages are spread out by bending them in a mass when the book is closed. This exposes a thin line of colors on the ex- treme guter margin of Traction Scoop Lifting and Loading ld Street Poving Below, Ready for ork e required by the pick- d-shovel method has been igned for attachment to he ends of work cars. As e apparatus is moved ahead trolley power, steel points e forced under the paving, peeling it off in large strips which are ushed up an inclined platform and rolled onto the bed of the car. As each car is oaded, the scoop is detached and coupled to an “empty.” It is said considerable ex- pense is saved by the combination ma- chine which lifts old street surfaces much the same as a banana is peeled. Eye of Camera Is Extended to Pierce Fog and Smoke Screens The power of the camera is being ex- tended by experimental work undertaken government experts so that pictures in be taken through fogs and mists and, ossibly, dense smoke screens. Airplane photographers with the aid of special fil- ters, film and plates of extreme sensitive- ness are now able to take pictures of moky cities on cloudy, misty days with tonishing results. Many of the discov- ries made in connection with the tests re being guarded closely as military ecrets, each page which form a solid design when properly joining. While the ornamental work is being applied the leaves are tightly closed and clamped so the edges remain as an inclined surface. After the paints are dry, the pages are allowed to resume their normal position and the edges are gilded or covered with “marble” effects. completely hiding any of the colors which might show when the book is shut. Some- Courtesy The Christian Science Monitor Skillfully Painted Picture on Edge of Book Revealed When Pages Are Drawn Back times both sides of the margins are treat- ed, different pictures being used to pro duce the double finish.

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362 POPULAR MECHANICS Modeling Plaques from Sealing Wax Proves Popular Fad for Women Ordinary sealing wax is the material a Chicago woman employs for compositions for the displays. The ap- paratus used is a dark box, eight feet lon and three feet wide, made ot wood, co\ ered with heavy green canvas and mount ed on a table. At one end is inserted pair of lenses and at the other, back of a stron electric light, is placed reduced copy of the pro posed sign, painted in the chosen colors. When the modeling observer peeps through the lenses, he sees the . poster just as though it . > were mounted at a dis- tance of 640 feet, and can thus make changes in th: + & Copyright, Underwood & Underwood Class in Wax-Modeling with Samples of Their Work and Alcohol Lamps, About the Only Tool Needed decorative plaques with bird, flower and other designs. Melted over an ordinary alcohol lamp and applied directly from the stick, the wax is easily worked into real- istic figures, adheres tightly to the surface and has a brilliant, glossy surface when dry. Paints are used to develop the color schemes and emphasize details. Instruc- tion in the art is given to a number of women, who have found it a pleasant and easily learned way to make attractive gifts and ornaments for the home. Telescope Tests for Outdoor Signs Reveal Defects before Posting To help artists design the most effective sketches for its outdoor billboards, a large western sign company uses an instrument which shows the poster as it will actually appear at a distance of 640 feet, or from an automobile moving at the rate of thirty miles an hour. These tests are done in the studio with small paint- ings, before the sign is officially ac- cepted and put up- on the boards, and are said to save the company costly er- rors in choosing the wrong colors or \' nde? Ta. Testing Sketch of Sign by Looking at It the “Long Way” through Telescope Lens sketch, if necessary, to improve its effectiveness The motion test is pet formed on the same box There is a disk on top similar to that of a pho nograph, with a rod fo holding the sketch. B giving the platform a spin with a rope and peeping through a hole above the lenses the critic will see the poster as thoug! he were looking at it from a speeding automobile. Heartbeats Charted by Electricity to Aid in Study of Disease Electricity and photography have been enlisted in the treatment of heart disease at Johns Hopkins hospital in such a way that a patient under observation may lie in a ward or room while in another build ing half a mile away, the beatings of hi heart are being recorded in alternately) thin and heavy lines with curves and angles indicating the actual movements of the organ. A specialist wires up his patient as if the latter were a radio set the most important part of the apparatus being a string of glass coated with silver and so small as to be almost invisible Three records are taken, first by co necting the string to the two arms ot the subject, the second by aitach ing the right arm and the left leg and the third, the left arm and right leg. To interpret the photographs,

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en se AY lie a li a} y nd its 1is et, us to le re mn ng or ‘he rm eg the rit ret hs, POPULAR MECHANICS 363 ematics is applied to the curves and of the lines traced by the heart- Some scientists now believe that eart acts as a sort of battery, giving discharge to set itself in motion. aper Cups for Hot or Cold Drinks Made in Sanitary Cabinet dividual paper drinking cups, sealed | a strip of metal and with an edge of ble thickness so as not to cut the lips, fashioned at the turn of a crank in a tary cabinet now on the market. It is ened to eliminate the use of glue and necessity of touching the cups with man hands before they reach the nker. Each container is cone-shaped d at the turn of the handle on the cabi- is cut from a roll of sterile paper long ough to make 1,000 cups. It is delivered the user through a slot at the front of e box. The cabinet may be used as a nding machine by fitting a coin-receiv- mechanism to it, to release the crank. ot drinks also can be held in the strong, ean paper without danger of leaking; the in of the cone is kept open, making the ip easy to fill and drink from, and its ape fits the hand. Many kinds of paper ews of Cabinet and a Cup =_ Strip of Metal That als It ips require glue or other unclean sub- tances in their manufacture, and are uched several times in packing and in llng the vending devices. Making the ips as they are wanted from the roll in e sanitary cabinet is designed to over- ome most of these difficulties. q Our Bureau of Information will answer il questions regarding articles appearing this magazine. Electric Furnace for Heating Knives Prevents Furniture-Shop Fires Furniture makers, before their goods are permitted to be shipped from the fac- tories, carefully inspect all pieces for dents Knife Furnace in Use on Workman’s Bench, and Inset Showing Its Construction or abrasions that may occur in handling the articles. When any such imperfec- tions are found, they are filled in with a special kind of wax that must be melted and worked into the wood with knives. To eliminate the danger of fire from blow- torches or other implements used to heat the wax and the tools, a small electric fur- nace that can be placed upon the work- bench and supplied with current from the light socket, has been invented. It will hold two knives at once, if furnished with an asbestos base, and the metal in the heating chamber is of a kind that will not rust or scale. The heater requires but little electricity and weighs only two pdunds. Monkey Markets at Steamer Docks Around the docks in London and Liver pool, a considerable trade is done in monkeys for organ grinders. Most of the animals arrive on sailing vessels from In- dia and South America as the big liners do not bother with such traffic generally, and the longer voyages give the monkeys time to become accustomed to the climate. They are usually sold at prices ranging from $3 to $25, depending upon their size and state of health, and are then disposed of through agents for the brokers who get commissions for finding customers. While in the hands of the middlemen, the mon keys generally are given good treatment with plenty of warmth and food and ample room in which to play and fight.

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Short Waves Promise Long-Distance Radio Senator Marconi’s New Beam System Leads to Improved World-Wide Wireless Communication By C. A. OLDROYD A RADIO-TRANSMITTING | station - talks to the whole world. Its huge antenna sends out waves to ey ery point ot the compass. When radio was young, this was considered the greatest advantage of the new system of communication, but later experience showed that, in many cases, it also proved its most serious drawback. The radio-sending station may be com- pared to a powerful electric arc lamp burn- ing on a tall tower. Close to the arc, the light is intense and even overpowering, but at a distance from the lamp, the illum- inating power fails off very quickly. So with radio. The energy fed into the trans- mitter is spread in all directions, and only a very small fraction reaches a distant re- ceiving station. Marconi, who gave radio to the world was the first to recognize this great weak ness of present-day systems, and as the result of many years’ research, has devel- oped the “beam” system, which marks as great an advance over the fisual long-wave system as the searchlight proved to be over the exposed are lamp. To prevent the scattering of light, and to illuminate far distant objects clearly, the arc lamp must be turned Furthermore, the messages can be kept secret. Upto the present, the only way to keep a message secret was to send it code, for thousands of stations were able to listev in. This meant delay, and ofte serious mistakes were made during the process of coding and decoding. With a beam-transmitting station, receivers out side the beam cannot read the message just as the searchlight cannot illuminate objects outside the pencil of light it pro jects. Marconi’s experiments with d rectional radio date back nearly thirt years, and in a recent lecture before the Royal Society of Arts, in London, lh traced the gradual evolution of the radi beam system from its very beginning. 1 first beam transmitter was constructed in 1896. With the aid of reflectors, con munication could be kept up over a di tance of one and three-fourths miles, while without reflectors the range was but hali a mile. In the meantime, the long wave of 10,000 meters and more conquered the field for long-distance work. With such immenss wave lengths, beam radio was out of the question, for efficient reflectors would have measured miles in height and lengt! A successful sys ] into a search- light by adding a reflector, which will project a narrow but very penetrating N radio more than in other forms of sci- tem of short wave transmi Marconi’s Message to Readers sion had to be of Popular Mechanics perfected before reflectors could be thought of beam in one di- ence, the amateur experimenter has and in man rection only. assisted the professional worker, and many years of cease After many ex- now famous engineers began their careers less experiment periments, Mar- coni_ has suc- ceeded in apply- ing this principle to radio. While the ordinary type of transmitter radiates energy in all directions, the beam system, like a search- as amateurs est pleasure. radio enthusiasts. [ am proud of the fact that I began my radio experiments as an amateur, and look back upon my early efforts with the great- step. In 191 ing such trans mitters were evolved step by Marconi su [It is up to the amateurs to make radio ceeded in bridg better known and to win more members for the already world-wide fraternity of over twent ing a distance of miles, with transmitter usins light, projects a narrow beam of radio waves toward the receiver. In this way the energy is con- centrated on the receiving station, and efficient transmission becomes possible with very low powers. tA4 waves only thre: meters long. The transmitter only was fitted with a reflecto: These experiments were carried out wit! a new type reflector, as the curved meta sheets used in the earlier experiment would have been too heavy and cumber

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POPULAR MECHANICS 4 2ECTIONAL SHORT WAVE BEAM TRANSMITTE LOW POWER COM PARISON.OF ENERGY REQUIRED AT TRANSMITTER TO PRODUCE EQUAL FIELD AT x x ght. The Sphere Marconi’s Aerial Reflector Throws a “‘Beam” of Radio Waves to Receiving Station and Reduces Power Con- sumption from 10,000 Units to 125

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366 POPULAR MECHANICS focal point. The reflector wire were also tuned to the wa length used. In 1923, an experimental tra mitting station was erected Poldhu, England. The receiv: was fitted on board Marcon yacht, the “Elettra.” His inter tion was to steam farther a: farther from the transmitting st tion and to compare the strengt of the signals. Owing to stru tural difficulties, no receiving re flector could be installed on board the yacht, so a single vertica wire, whose upper end was se. enty feet above sea level, served as antenna. The results obtained were surprising. A wave lengt of ninety-seven meters was e1 ployed, and twelve kilowatts were fed into the eight* transmitte tubes. Even without using a ri flector at the transmitting statio1 clear signals were receive throughout the whole of th twenty-four hours when 780 mile from Poldhu, although the signal ane ane, Saas oa Senator Marconi Seated in the Wireless Room of His Steam Yacht “Elettra’ weakened during the daytime To test the short-wave syste some for practical work. The new reflec- over still greater ranges, the transmitte: tor consisted merely of a number of ver- at Poldhu was redesigned to absorb up t tical wires spaced around a parabolic twenty-one kilowatts. Without reflector curve; the antenna was located at the’ the daylight range was increased to 1,400 . cence eee re te eee eee Copyright, Marconi Instruments Used in the First Transatlantic Wire'ess Test in 1901, on Display with the Marconi Exhibit at the British Empire Exposition

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POPULAR MECHANICS EJECTING sated ATING CLOUDS*OF _% OSTA AMS OF Tay GASES AND - ; \ METALLIC VAPORS . ~( Copyright, The Sphere Radio ‘‘Fading” Explained by Irregularities in Layer of Electrified Dust Particles, Known as the Heaviside Stratum, above the Rarefied Atmosphere of the Earth, Which Reflect Back Wireless Waves

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368 nautical miles. At night, and for some hours at dawn and sunset, strong signals were heard at Long Island, New York, and even at Sydney, Australia. A station situated in Montreal, Canada, found it possible to work with Poldhu for sixteen hours out of the twenty-four Confident of Senator now attempted radio telephony England and Australia. two meters Marconi between A wave ninety- was employed, and twenty-eight kilowatts were fed into the oil-cooled transmitter tubes. For the first time in history, a voice speaking in England was heard, practically at the same moment, in Sydney, Australia, on May 30, 1924. This result was all the more surprising as neither sending nor receiv- ing station used a reflector. Thanks to improvements, it is success, long recent now possible to construct short-wave beam stations of as much as fifty kilo- watts. .Such stations are far cheaper to build than the giant long-wave stations used for long-distance work at the pres- ent time. For broadcasting, too, the beam system has great advantages, for the own- er of a simple and inexpensive crystal set who is situated in the path of the beam, Golf Courses Laid Out on Lawn with Special Tees and Markers Golf links of nine or eighteen holes can be adapted to the lawn or to small parks and fields with the aid of a set of tees and markers devised by an eastern inven- tor. Thus persons, who have little oppor- POPULAR MECHANICS will obtain quite as good reception fro distant stations as the owner of an el orate multi-tube set Recent experiments also have giver clue to the reason for the “fading” of ra signals, as well as the improved recept at night. Above the six-mile belt of eart atmosphere lie fifty-four miles of m« rarefied air, and then a layer of electrifir or ionized, dust particles, called the Hea side stratum, in honor-of the man w! discovered it. This stratum is made up ot the minute dust thrown off by the sun a: the tails of passing comets, and repelle by the pressure of the solar-light radia tion. Its under surface is very irregu and is always in uneasy motion. TI! wireless waves which reach it are reflect: back toward earth, but because of the regularities and constant ions, 1 motion of t] the amount of reflection varies, a: fading is the result. By day the strat sphere, or rarefied upper air, is also io ized, but does not reflect because of patchy conductiveness, so that all unwar waves are lost, and only those pzssi: parallel to the earth, through the excey tionally poor conductor of the lower a are received. tunity to visit a regulation links, will hav more chances to enjoy the thrills of the “ancient and honorable game.” Large figures are placed on the markers to ind cate the number of the holes, and smalle digits with arrow pointers show par. Th: tees are disks of rubber, which prevent i: jury to the grass, and the hole signs hav sharp wicket support which can be inserted easily and leave no trac¢ when they are pulled out A nine-hole course ca: -asily be arranged ona 5 by 150-foot lawn. \ constant practice is con sidered one of the most important requirement for a good game, thi “vest - pocket” course specially suited to th-« player who is tikely t become “rusty” throug! lack of time to go to public or club links. The shots require just a much skill on the law course as they do in the regular game althoug! Golf in Your Own Yard Is Possible with Tees That Protect Grass and Set of Markers for Holes there are no opportuni- ties for long drives.

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mping Ballast Water from Steamer into Compartments ave Settling Barge That Re- the moves the Oil + Barge Rids Ballast Water of Oil lle: to Protect Fish and Birds rhe . ” Oily ballast water, poured from steam- wu ers into rivers and harbors, has been = und so destructive to fishes and birds, ted ides polluting streams and ports, that aes nalties have been imposed by the British saat vernment on vessel owners who allow a liquids to escape into navigable wa- 7. ers. Thestep was followed by considerable A mplaint from shipping companies forced to send their boats to the three-mile limit ~ empty their ballast tanks. To solve a s problem, an English company devised hi il-separating barge which is moored wv yngside the vessel and receives the bal- "? t water as it is pumped out. The barge te livided into a number of compartments et bulkheads and as the oil-mixed water sses through them, the oil is separated Phe d the water finally discharged over- , ard. As ch as 200 ; of oil have ird. AS much as 2 tons of ol have a ; i en recovered from one steamer. the . 7 A ont q To help deer that have fallen into the ni- ime of a western hydroelectric power int, ladders have been built reaching to e top. POPULAR MECHANICS 369 Dash Control for Auto Generator Saves Gasoline and Batteries Operated by a lever from the automo- bile dash, a control for changing the charging rate of the generator to suit driv- ing conditions has been placed on the market. It shifts the third brush in the direc- tion the armature revolves, to give a high rate, and the reverse operation produces a low rate. The entire apparatus is con tained in an end bracket for the generator with a rod connecting it to the lever on the dash. Use of this attachment makes it unnecessary to take the car to a garage for altering the charg ing rate, and quickly adapts the car cor rectly for operation in the city or in open country and for night driving. int

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3710 POPULAR MECHANICS “DRAGON” RUN BY MEN ADDS REALISM TO MOVIE A realistic “dragon,” operated from the inside by seventeen men, has been built for a German motion-picture studio. The exterior has been carefully modeled from reproductions of the dinosaur, and the in- terior is fitted with an elaborate arrange- ment of electric lights to guide the hidden actors, while suction and force pumps, and bellows, have been installed so that the replica may imitate, in true fashion, the movements of a living animal. For in- stance, the pumps and blowers can be op- erated to make it appear that the figure is drinking water from a pool, and breathing is represented by lifelike contraction and expansion of the chest. The “crew,” care- fully drilled to its task, performs its part in such a way that the dragon crawls slowly along a narrow ravine, apparently lifts itself into a tree, rolls its eyes and, true to tradition, shoots fire and steam from its mouth. A struggle with the hero of the play is an incident in the film st and in this, what appears to be b gushes from a wound inflicted by a sw Several months were required to build model and train the men who guid: Specially designed machinery was : stalled inside the monster on rigid b so the writhing movements of the g1 reptile could not interfere with its op: tion by dislodging or buckling the me anism. An arrangement. of “sights” the crew controlling the propelling : chinery was provided by inserting s: peep windows in the thick spines on forward part of the figure. Besides nishing a means of ventilating the inter this aided the operators in guiding dragon and permitted each man to | his action in advance of the signals gi for the manipulation of the various trols responsible for fantastic antics of lizardlike hulk. Bei the weird scenes w« “shot,” care was taker give the ugly head a rocious appearance drenching the grinn jaws and ugly teeth w a fluid which drip from the mouth in i tation of drooling. Left, Preparing the “‘Dragon”’ { the Fight with the Hero, Stag: in the Swamp Shown Below

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POPULAR MECHANICS Artist's Conception of How Mechanical “Dragon’’ Was Made to Play Realistic Part in Weird Motion-Picture Production by Seventeen Men Who Worked Controls

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72 POPULAR MECHANICS Sunlit Cells in Circular Prison House Controlled from Central Tower Circular prison houses with tiers of cells controlled from a central observation tower within the structure have been built on the new state penitentiary grounds at Statesville, Ill, near Joliet. The arrange- ment eliminates the need of a guard at each floor, gives better ventilation and ad- mits light to practically every cell. The doors of each prisoner’s room are built mostly of glass with just enough steel grating to discourage any attempt to break through. This likewise permits better il- lumination and enables the guard to keep constant watch of every inmate. The circular units are grouped about a cylin- drical central building, housing the main dining room and all the structures are in- closed within a wall more than a mile long and thirty-five feet high. Though there are sentry houses at each corner, the cus- tom of having the guards walk the wall has been abolished. Each cell house con- é I Interior of Cell House at Illinois State Penitentiary Showing Guard’s Watch Tower, and Model of Area as It Will Look Wher: Completed tains 248 compartments, is 150 feet diameter and 45 feet high. The new bi ings occupy part of the prison ar¢ 2,193 acres and were formally opened long ago just before convicts were t1 ferred from the old institution at Joli: Safety First Taught by Phonograph to Children in Public Schools As part of a safety-education camj in Chicago, a phonograph record out ing the dangers of the street which « dren should avoid, has been prepared a motor club and distributed in the pu It stresses the folly of r skating, riding on sleds and playing in the thoroughfares, and urges the yo tolks to take pride in being cautious the sake of their families and their co try as well as for their own good. record has been sent to all classes that ' phonographs for instruction purposes der the approval of the superintendent schools. schools.

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¥ ae eee Se OSS SMM EE MF WS YESS AVENE VV IY OVE VERO WV eS POPULAR MECHANICS 37% Zinc-Alloy Coating on Iron and Steel Prevents Rust and Takes Polish ron and steel are said to be made rust- § and other metals are protected from osion by coating them with an alloy inc by a process devised after many rs of experimenting by an English firm. not a plating operation for the alloy iid to become thoroughly incorporated th the basic metal so that there is no ince of peeling or chipping off. The thod is reported to be cheaper than ectroplating and the color and finish it roduces resemble those of silver. A bril- it luster can be obtained by buffing. Ranger’s Horsepower Cyclometer Simplifies Measuring Trails Visitors at Yosemite national park have heen treated to the unusual sight of a talwart forest ranger on horseback, can- tering along the forest trails and holding one hand what appears to be a polo tick mounted on a bicycle wheel rolling n the ground. The apparatus and the er are engaged in serious business, wever, for this is the method that E. Solinsky, chief forester of the park, has levised for measuring the 600 miles of sad and trails that lead through the re- vion. The wheel, in its frame and exten- mm handle, records distances on a cy- lometer mounted in the same way that rest Ranger Measuring Trails on Horseback with Bicycle Wheel and Cyclometer Attached to Stick he instrument is carried on a bicycle. his system is sufficiently accurate for its purpose and is far cheaper than surveying. Manicure Set Worn on Neck Ribbon Holds Tools in Hollow Handle A manicure set so small it can be hung on a ribbon worn around the neck carries Compact Manicure Set Which Holds Instruments in Handle and Can Be Carried like Fountain Pen all the various instruments in a hollow tube which forms the handle for the arti- cles when in use. Any of the tools may be adjusted in place in a few moments and are as easily manipulated as the ordinary kinds. Resembling a fountain pen, the compact set is small enough to be carried in a purse or pocket. The parts are pro- tected against loss or rust and injury by a closely fitting cap. Fabric Patch for Auto-Tire Casings Mends Balloons or Cords Life of auto tires is said to be prolonged for 1,000 to 5,000 miles and breaks in bal loon or cord casings are quickly repaired with a non-stretching, reinforced fabric patch recently placed on the market. It is said to be the only satisfactory means ot mending balloon tires. The patches are applied with cement by the same method used in mending a tube, and the road heat and air pressure vulcanize the material in a short time. The fabric can be built up in several layers thus reconstructing the tire wall with a section of the same pliabil- ity as the casing itself.

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374 POPULAR MECHANICS To Train Your Dog Animals Enjoy Learning and Respond Quickly to Proper Teaching Which Makes Them Valuable Guards and Comrades By ALBERT PAYSON TERHUNE Betest of all, you must know more than your dog. Second, you must not only be able to teach him, but to do it in a way that he will enjoy and remember. Third, you must have patience, a fund of gentle firmness and, above all, common sense. Naturally, these traits also imply self- control. There in a short paragraph, is summed up the whole theme of dog training. There is no magic, no mystery, about it. Anyone can do it—anyone who is suffi- ciently well stocked with the traits I have just set forth. It seems simple enough. Rightly done, it is absurdly simple. Remember, above all, that your dog is not a Daniel Webster. He is an inferior being, who is at your mercy and who must rely on you for everything. Your six- year-old child would not learn fast at school, were his teacher to accompany the lessons with yells of rage and with curses and blows and kicks. The same applies to your dog. If you can't control your own temper, how can you expect to con- trol him? If you can’t keep cool and pa- tient, don’t try to train him. I have dwelt somewhat at length on this; not as a preamble, but as the needful foundation of all dog training. Without this foundation, your work will be useless. Decide, in the beginning, just what you want your dog to learn. Cut the list low as possible. Teach him few thi: but teach those thoroughly. Never te him anything new until he has master every detail of every former lesson such a way as to remember it at wo of command. Best begin with him, if possible, a puppy. The first and indispensable | son is obedience. You can teach | nothing else until he has learned that. soon as he has learned that you are master, that he must look to you fot food, his exercise, his play—to you to no one else—he will begin to obey y Be his constant companion during t time. Let nobody else make friends w him. Obedience and master love will {: low quickly. The first thing to teach him, ordinar is to lie down in some designated p! and to stay there. Press his hips slow and steadily downward, saying all t time, “Lie down! Lie down!” Un the pressure, he will sit down. As does so, shift your hand to his shoulde: always repeating the same words, un! the shoulder pressure has made him down. Then praise him as if he had do some dramatically fine thing. Feed h a bit of liver or other titbit. Go throus the same performance of pressure and 0! at

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PUPPOSE allG Id lal CHCAPLL Lilaih Os vey ens* NS —— ee POPULAR MECHANICS 375 ed command several times. In a day or after the second or third lesson, ll understand that the words “lie are a signal for him to lie down. ithout the pressing hand. Next, o some spot where you want him and repeat the words. Almost at often the first time—he will move designated place and lie there. the mere motion of the finger will him go to the spot and lie down no word of command. Always fol- ach lesson with praise and some of reward. ext—especially if you are in a city or motor-infested road—comes the need _~““a ne t CT« } 10 "4 ] r } Well-Trained Pointers in Sight of a Quarry Cautiously Indicating the Presence of Game y: This can be done by ordering him back t whenever he starts to run forward, ac “ companying the order by the command, {i “Heel!” Better still, take him out on a leash and pull steadily in on it as he moves ir ahead of you, saving “Heel!” over and iF over, OV Very soon he will understand t vou mean, and will drop back at the first nd repetition of the word. Teach him to S walk thus beside or behind you, until you det vive the order “Go ahead!” with a ge unt ture to explain its meaning A dog tha n | has learned to heel, has made himself im- do mune from many tratlic perils. h Another traffic guard may be practiced ous to advantage by pulling on the leash a | oi teach him to “heel”; in other words, a street crossing is reached and by saying ilk close beside or close behind you. “Wait!” Hold him thus fora few secon

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376 POPULAR MECHANICS Canine Guard of Bank Messenger Receiving Lessons in Defense of Parcel : : : Rare Pose b Most Dogs Are Easily Taught Amusine Tricks , y by the Exercise of Patience and Kindness Willing Terrier OU. &U

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a ilk close beside or close behind you. “Wait!” POPULAR MECHANICS ti Police Dog Ready to Fight Danger to Its Helpless Charge Hold him th lus fora few seconds Warning Its Blind aster, This Canine Guardian Holds Him from the Path- way of Harm Prize - Winning Setter in the Act of Scenting Prey Mascot of Fire Patrol Enjoying Stunt It Learned from the Crew then say, “Go ahead!” Before long, reaching a crossing, he will know nough to halt of his own accord and to iit there until you give him the signal go on. [ have known scores of dogs that o this, thereby saving themselves from udden death under the wheels of passing irs. It is a simple and necessary thing 7 » learn. It is still simpler—if more drastic—to ‘ach your dog to avoid poisoning by Te- fusing to take food from a stranger. you have taught him to look to you alone for food, etc., leave the room and let stranger offer him a titbit. As the reaches forward 1 for it, let the st: After Some dog inger snatch it back, slapping the dog lightly across the mouth. A few such lessons will teach the pupil that it is unsafe to ac- cept food offered him by any outsider. It is a cruel thing, in a small way, this slapping of a friendly dog. But it i cruel than to let him die in agony s less from

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378 eating poisoned food. Also, it is better than to have him stolen by someone who may try to tempt him along by gifts. By the time your dog has learned that your home is his, he will probably appoint himself a volunteer guard of it. That is dog nature. Be careful not to scold him severely if, at first, he barks at some friend who enters the house. By making him think he must not sound the alarm, you may keep him from POPULAR MECHANICS require longer time and more patience. Sut all will learn it eventually, if right! taught. Often the fault lies with the heed less owner, not with the dog—especially the latter be an immature puppy. In suc! cases, to beat the poor youngster is sense less cruelty. Be sure that he is let out of the house often enough and that he is not made to sta indoors too long at a time Punish derelic- tion by a sharp scolding, at the time — never sounding it later, when he some time may not un- when a burglar derstand what is climbing in. you mea: Encourage him Then put hi to bark at any out of the outsider’s ap- house in dis proach. Praise grace. He will him for doing learn the it. In course meaning of of time, he will such scolding learn to dis- and will profit tinguish friend by them. Don’ from foe and beat him fo: to save his these transgres barking or sions. A scold growling for ing is enoug] the latter. Never call Here is some- thing else that Highly Educated House is worth while teaching him. Make him lie down; lay your coat or some other ar- ticle between his forepaws and _ say, “Watch it!” Then move away. The chances are that he will try to follow you. Make him lie down again, replace the coat between his paws and repeat the com- mand. Move away again; this time a little farther or even out of his sight. It may take a number of lessons to make him understand he must stay where he is until called by you, and that he must watch over the article left in his care. But, soon or late, he will always grasp the idea. Transfer the coat to the seat of your car, when you take him riding. If you eave the car, make him lie down on the eat, guarding the coat. Quickly he will learn that he is to guard not only the gar- ment but the car as well. A resolute watchdog, on the seat of a car, is better thief protection than a dozen patent locks. few thieves will venture aboard a car where such a dog is growling defiance. As to housebreaking a dog, some dogs learn this imperative duty by instinct. Most of them have to be taught it. Some learn it in a lesson or two. Some Ready for Breakfast; a Puppy Well on Its Way to Become a et and an Interesting Companion dog to you to punish hit That will give him the idea that disobed ence is one way of avoiding retributio: Always go to him to punish him. A dos just learning to obey often becomes di obedient through being called to his mas ter to receive a whipping. I have raised and trained two or three hundred colli puppies, without once striking one « them. Yet my dogs obey me implicit! I insist on one-hundred-per-cent obed ence. If you find it really necessary to us¢ corporal punishment on your dog, slay him over the loins with a loosely folde newspaper. It will scare and humiliate him quite as much as would a whip slas! I have said that a dog is not a Danie Webster. While he is glad to learn whe rightly taught, yet sometimes he does ni understand what you are trying to teac! him. Thus, when you find he is becomin: scared or confused in the course of a le: son, turn the lesson into a romp or other wise break it off and let him get over hi fatigue or bewilderment. Don’t keep o: trying to teach him at such a time. You will only give him a terror of the tas! and you will achieve nothing. Take you: time. You will save time that way in the

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POYULAR MECHANICS 379 Dog Movie “Star” Study- ing a Radio Loud Speaker in Action Firemen’s Pet Which Attends All ; Alarms, Posing at ec é the Wheel of the lie Apparatus Group of High-Grade Pets Trained to Imitate the “Huskies” of Eskimo Land

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380 discouraged become over your dog’s progress, there are two things to remember for your own conso- lation. One is that dogs differ as much as do humans in the speed wherewith they long run. If you Typewriter Run by Motor Power Makes Uniform Key Strokes With a small electric motor attached to the key mechanism, a typewriter of stand- ard make is now being manufac- tured to reduce the stenographer’s labor and to im- prove the quality of the work. The arrangement is somewhat similar to a German ma- chine which has been in use in that coun- try for several years. A light touch on any key engages the motor in such a way that the stroke and spacing are automati- cally completed. The chief advantage POPULAR MECHANICS Ready for the Game of “Fetch the Stick,” Pastime for Both Boy and Dog: Left, Climbing Hunter Scaling a Fence Too High to Leap; Insert, Young Racing Whippets Undergo- ing Training for Exciting Chase after the White Rag Copyright, Underwood & Underw can learn, but that all rightly taught dogs will soon or late master their lessons. The other is that it takes only a comparatively short time to educate any dog, and that thereafter, for the rest of his life, you will have an ideal comrade and guard who will carry into effect all his lessons with no further effort on your part. Surely that is worth a little time and patience. claimed for this apparatus is that the type bars are pressed down with uniform force, assuring a neat-looking page. Greater output and less fatigue for the operator are additional advantages that recom- mend the innovation. New Steel for Use in Shipbuilding to Reduce Weight of Vessels Steel that can be rolled into thin plates weighing considerably less than those usu- ally employed in shipbuilding has been produced by an English chemist, it is re- ported, presenting a way of greatly reduc- ing the weight of vessels without sacri- ficing strength. Heavier cargoes without increase in horsepower are seen as a re- sult of this discovery and the new steel

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_ of time og ; ter ligh ung Tg0- ting Rag e's ‘he ely lat vill vill no lat ‘pe ce, ter ‘or m- ng u- en “e. ic- POPULAR idly is being used in the construction of ships for the eastern trade. It is said ‘fect a saving of eight and one-half cent in weight over the usual mate- Increased elasticity is also claimed the steel which, like many other inven- , was the direct result of an accident. chemist was called to test some plates t had been used in the construction of randed steamer. He came to the con- ion that they did not have sufficient etch” and immediately began experi- ts toward preparing steel with greater tic qualities and corresponding reduc- in weight. Airplane Is Made Nearly Noiseless without Decreasing Power by means of an improved exhaust and propeller that operates on special gears, minating the usual whir, British engi- ers are said to have devised an airplane it is practically noiseless without sacri- e of speed or lifting power. At the same ie, by increased use of internal bracing, ich of the noise caused by the wind hing through the wires and spars has en avoided. Alarm Tells When Tires of Auto Require More Air An under-inflation alarm for pneumatic res has been invented which is claimed to warn motorists when a tube has be- me flat or loses enough air pressure to reach the danger point. The device, which fitted between the wheel rim and the tire, is sounded twice during each revolu- tion of the wheel and is sufficiently loud U nder - Inflation Alarm Attached to Rim of Auto Wheel to attract the attention of the driver even bove the noise of surrounding traffic. he signal can be mounted either on the inside or outside of the rim and remains noperative until ten pounds or more of air has escaped from the tube. MECHANICS 381 Wheelbarrow Bench for the Lawn Is Easily Moved by One Person Benches for the lawn or garden are use- ful and ornamental but cannot be moved easily from place to place as needed. This With Handles at One End and Wheel at the Other, This Deco- rative Bench for Lawn or Garden Is Easily Moved About limitation has been overcome in a seat which an Englishwoman has invented. It combines the features of a bench and a wheelbarrow and may be trundled about as easily as the latter article by means of two long extension handles and a wheel at the other end which forms part of the support. Self-Rescuer to Give Miners Chance to Flee from Poison Gas Danger of mine deaths through smoth- ering by poisonous gases is being reduced in the Illinois coal fields by equipping the workers with “self-rescuers,” tested and approved by the federal bureau of mines. They are designed to give the wearer half an hour or more after the gas surrounds him before he is overcome, and consist of a pinch clamp for the nostrils attached to a small can with a mouthpiece. The de- vice is worn in the pocket or on the belt and is inclosed in a soft brass case that may be ripped open by hand. When the fumes arise, the breathing apparatus is quickly adjusted and by inhaling and ex haling through the mouth into the can, the miner is protected from the poison for at least half an hour and has a chance to seek escape. @On the Iguassu river in South America, 600 miles from Buenos Aires, there is a waterfall which is one-third higher than Niagara Falls.

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382 POPULAR Saxophone Played by Slotted Slide Instead of Holes and Keys Sliding saxophones, operated on some- what the same principle as the trombone, Playing the Sliding Saxophone; Finger Ring for the Right rand Helps the Action have made circles. their appearance in musical Instead of the usual arrangement of holes and padded keys, this instrument has a closed tube at the side that moves up and down a groove to produce the dif- ferent notes. The player is afforded a convenient hold on the slide by a ring through which the forefinger of the right hand is passed. Manufacturers of the ar- ticle assert that it is more easily mastered than the usual saxophone, weighs consid- erably less and that it does not readily get out of order. Cotton Made to Wear like Wool by Dipping in Acid Cotton is said to be increased fifty per cent in strength and the resistance of the surface to scraping improved 200 per cent by immersing it in concentrated nitric acid under a process discovered by a Swiss scientist. The treatment causes the fibers to become rough and curly, resembling wool and having approximately the same wearing qualities. The acid gives the cot- ton a yellowish tinge but this is removed bv bleaching and the effect of the chemical does not extend below the surface. The MECHANICS fabric may be mercerized later, that is, given a silklike sheen by dipping it in strong alkali, a method discovered sey- enty-five years ago by John Mercer, an English chemist. This wool-like cotto: is said to dye more readily and brilliant! than the untreated fabric and when mer cerized, closely resembles linen. Fiber Sound Disks to Improve Phones Get Better with Age Diaphragms for telephones, phono- graphs and loud speakers, are to be made from a composition of fiber, iron filings and bakelite according to a patented proc- ess which is said to result in material near- ly resembling the human vocal cords in structure. The substance is more delicate than the metal now used for the sound disks and is claimed to give better effects as it becomes older. For talking machines and loud speakers, the composition dia phragms will remove much of the harsh metallic noises often heard through such apparatus, and, it is believed, will give a clearer reproduction of voices and some kinds of instrumental music. Pocket Micrometer with Dial Face Is Easily Read and Operated For measuring the thickness of various materials and small parts, a watch-shaped pocket micrometer, with a dial face an inch and a half in diameter that shows readings in half - thousandths of an inch, has been invented. It is held by one fin- ger slipped through a ring on the side, and is operated by turn- ing a knurled screw at the top between the thumb and forefinger to move the jaw below, between- which the object to be measured is inserted. The gauge wil record accurately sizes up to five-six teenths of an inch. is saidto be much easie: to read and manipulate than the usua style of micrometer and is fitted in a bronze case so designed that it cannot spring and thus give false readings on the dial. On the reverse side of the gauge i a table which shows the decimal equiva- lents of common fractions.

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t in SeV- an tton int] mer- no- lade ings roc- ear- S in cate und fects ines dia arsh such ve a ome ace rious aped e an POPULAR MECHANICS 383 Listening to the Foot- ball Returns through Loud Speakers Set in Niches on Bandstand Bandstand Set with Loud Speakers Helps Relay Football Returns Long after the summer concert season had closed, football enthusiasts thronged to the Common in Boston and gathered about the bandstand, where loud speak- ers had been set in niches near the roof, to hear returns of a game. The circular shape of the structure suited the purposes of broadcasting, enabling the crowds on all sides to hear. The horns were painted white and shaped to blend with the archi- tecture of the stand, the half-hidden radio “oracles” adding to the appearance of the pavilion and extending its usefulness be- yond the limits of the summer season. Run Sidewalk through Building in Order to Widen Street Running the sidewalk through the cor- ner of a building solved a difficult street- widening problem in Ottawa, Canada, and added another traffic lane at the in- tersection, besides speeding up traffic by substituting an easy curve for the former right-angle turn. The corner of the build- ing, a stone, steel and concrete structure, was altered by running the sidewalk with- in the building, behind the corner pier, the new wall line connecting the first pier from the corner on-one side with the cor- responding pier on the other. The ten- foot sidewalk was then rounded off around the building, the new curb line passing just outside the corner pier, allowing only enough curb line to protect the pier from being scraped by passing vehicle hubs. The city’s plan commission, which worked How Store Space Was Sacrificed for a Sidewalk to Solve Street-Widening Problem out this arrangement, is contemplating similar treatment for other corners.

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384 POPULAR MECHANICS Portable Motor-Driven Handsaw Cuts Wood, Fiber or Metals Driven by a small motor using 110 or 220-volt circuits, a portable handsaw with interchangeable blades for cutting different Door Trimming and Other Exacting Jobs Are Easily and Accurately Done with Motor Saw kinds of material, has been devised to save time and labor and reduce the cost of various carpentering and other jobs. Air cooling, shafts mounted on ball bearings and a body made of light aluminum alloy, make the saw durable, smooth in opera- tion and easily handled. It can be used on wallboard, fiber or bakelite, and special cutters are provided for steel, brass and other metals. High Chair, Cradle and Buggy in One Save Space in Home Baby's high chair, buggy and a rocker cradle have been combined in one com- pact and easily manipulated article by a western manufacturing company to save the necessity of purchasing separate pieces and having them in the way whe: not in use. The rockers for the cradle serve as legs for the chair and as handles when the buggy is needed. The wheels are rubber-tired and can be swung up out of the way. A movable tray for food and a strap between it and the seat, are add tional attachments on the chair for the comfort and safety of the infant. The ar ticle is sturdily constructed, can bx changed in little time and is especially adapted to indoor use, though it is well suited to the street. Cathedral Rises and Falls with Tide That Compresses Clay at Base Owing to the tremendous weight of tide waters that enter the Thames river, the clay around the foundations beneath St. Paul's cathedral in London is said by e1 gineers to be compressed, causing the building to rise during the flood periods. When the tide recedes the structure re- sumes its normal level. Similar effects of the ebb and flow of the ocean are reported to have been noticed in several piers of the Waterloo bridge, which rise about three-sixteenths of an inch every time the tide comes into the river. Costly Animals as Zoo Attractions Less Popular than Cheaper Ones Fifty-dollar monkeys and their antics, and birds that cost but a fraction of the $15,000 spent for a pair of pygmy hippo- potami, are more popular with the zoo- going public than the expensive animals, accotding to Raymond L. Ditmars, cura 4A Ta Baby Can Eat at Table, Enjoy a Rocking and Take a Ride in This ro Folding Outfit ombination

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ef > — mer o POPULAR 1: of mammals and reptiles of the New irk collection. Rare specimens may be ecious to the scientist but the crowds e them a passing inspection that they iy tarry longer where young orang- tans and monkeys gam- and birds display eir brilliant plumage. ‘ople doubtless would disappointed if the zoo not have the larger costlier creatures, Ditmars believes, but expensive sea lions and en lowly prairie dogs it can be bought for e dollar a pair, provide re amusement for the isitor than exhibits in hich thousands of dol- irs have been invested. lost of the large mam- ials cost from $1,000 up. Giraffes, hippopotami ind rhinoceroses bring round $7,000 each; ele- phants from $2,500 to $5,000; zebras from $1,000 to $1,800 and lions ind tigers a few thou- 0 MECHANICS 385 Burlap ‘‘Bonnets’’ around Trees Aid Symmetrical Growth West winds raise such havoc with shade trees planted in the civic center in San . “ i . +i 1 7 . ‘ . = nail . . inds each. Snakes. in Windshields of Burlap Built around Young Trees in San Francisco's Civic pite of the general aver- sion to them, attract many and, as they ire cheap to maintain, are considered a tar exhibit. Fifth-Wheel Marker on Auto Truck Reduces Cost of Lining Roads lime and labor required to put the center traffic line on highways are greatly reduced with the aid of a_ fifth-wheel inarker attachment that fits any light mo tor truck. It is clamped to the running board on the driv- ers side where it nay be easily seen. Paint for the line is supplied through i hose connection trom a barrel and runs directly upon the felt-covered tire ot the marking wheel, which rests against the cement. In front of the ap- Center to Keep Them from Growing Crooked Francisco that burlap protectors are erected about them while they are young to prevent leaning to one side. Stout frames are constructed and anchored firmly in the ground and the fabric nailed between the crosspieces Coal Is Tested with X-Ray Camera to Show How Much Ash It Holds Another practical use for X-rays has been introduced by an English chemist who 1s reported to have devised a camera, which, with the aid of the rays, takes a stereoscopt photograph ot the inside of a lump of coal, revealing the amount of ash forming material it contains. Vhis process, it is be heved, W il] be ot pliance are cuides, Marking pe Eee oe Bebow ~~. Fifth-W heel value in opening up a longer one for new mines, as it use on straight roads and a shorter one’ will also show how much weight a sample On curves, so that the old mark may be will tose when the outer ash present ts tollowed more easily. removed bv washing

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386 POPULAR Dictaphone Hooked to Radio ‘‘Cans”’ Programs for Further Use When an especially pleasing musical number is announced for broadcasting from some station or a prominent person Dictaphones in Position for Receiving Radio Programs, Showing Attach- ment to Loud Speaker Wire That Fits on Voice Tube is about to deliver an important speech through the ether, a.\San Francisco inven- tor gets out his dictaphone, hooks it to his receiving set and preserves the .pro- grams for further enjoyment. The success of his method, he declares, lies in the way he has harmonized the radio voice vi- brations with those of the dictaphone re- ceiver. A pre-election speech of President Coolidge was recorded on two cylinders ind is to be presented in this form to the chief executive by the inventor. Mechanical Cashier Makes Change and Admits Persons to Trains Patrons of an elevated railway in an eastern city have been testing a fare-col- lecting apparatus at the station gates in- stalled to do the work of a human cashier. It automatically retains ten cents from a deposit of a quarter or a fifty-cent piece, returning the correct change and, at the same time, releasing the catch on the turnstile to permit entrance to the trains. Dimes —the regular fare—also are ac- cepted, but the machine will not handle paper money, pennies or nickels. It is believed that the device will be of aid in rush hours as passengers with the exact fare, or coins which the contrivance will change, can pass through quickly. MECHANICS Pupils Are Taught to Imitate Birds in School for Training Whistlers Whistling has been dignified into art by a western woman who has start« a school where pupils are given instru tion in making the tri and calls of various bir: with tongue and lips, a1 where concert and so whistling is also taug! A special musical scor: hardly recognizable t the layman because of it odd characters and way lines, is used and the bi: notes have already bex given special names su as “hewies,” “whit-chas “heedalas” and “lup lups.” The instructor de clares that the voca cords are not used at in making these sound although she giv breathing exercises sim lar to those employed | students of singing. The founder of the school sa’ that she learned whistle by listening to the birds, and car: ful analysis of the tones has enabled h« to reproduce them with realistic effect. Glass Plate on Electric Wall Switch Saves Defacing Decorations A glass plate for electric-light wall switches has been patented to replac« metal escutcheons that often interfer: with decoratio1 schemes by hidin parts of the wall paper designs Scarcely visible, the glass variety permits any color plan to be carried out without pre- senting unattrac tive spots of metal surfaces. Unaf- fected by air o1 handling they do not require pol- ishing or painting to remove tarnish spots, and only the button and two screw heads are visible when the plates are attached. The panels are also made in colored glass and with mirrored backs to correspond with various plans ot decoration.

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“= FF ¥ *) G8. FP eee POPULAR MECHANICS 387 Three Streamlined Cars, the Sixteen-Horsepower Ley, Thirty-Five-Horsepower Andi and Twenty-Four-Horse- power Dixi, in the Streets of Berlin “Raindrop” Bodies for Automobiles Scientific Streamlining Performs Wonders in Increased Power and Gasoline Saving through Decreased Wind Resistance Ss! REAMLINED automobile bodies, " motors at the rear instead of under a ront hood, and other radical changes are mong the developments promised for the ear future by both native and foreign utomobile designers. ; the “raindrop” body — completely treamlined to reduce air resistance to the »west possible point—is already attract- ng considerable attention abroad and is being manufactured both in England and (rermany. If the new school of design itches the popular fancy—and its pro- ponents believe it will because the fully treamlined body is rational, they say—the otor car of the near future will at last escape from all vestige of the buggy and horse-drawn carriage motif. Starting out with a one or two-cylinder engine built under an ordinary one-seated buggy, automobile builders became so tirmly enmeshed in the tradition that they have never fully freed themselves of it. lhe first automobiles had buggy dash hoards, buggy lamps, carriage wheels and it wasn't much more than twenty years ago that one automobile designer put a car on the market equipped with a whip socket! The evolution of the automobile proceeded rapidly, but always with the impress of carriage builders’ de signs. The dashboard evolved into an in strument board and cowl, and a hood pro jected in front of it, to cover the engine, which in the early days was such an un certain quantity that it must needs be placed at the point of greatest accessibil itv. Straight lines and alleged stream lines which paid little attention to stream line principles replaced the more elaborate curves and angles of family-carriage days but the automobile still kept the same general contour laid down by the first builders who entered the new field. In the meantime a new industry was rising to build airplanes, and for the first time exact studies were made of stream- lines and wind resistances. Scientists were employed and wind tunnels constructed and the mysteries of the invisible air cur-

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385 A Two-Liter Benz Racer Built along the Lines of the Rumpler Stream- lined Body rents charted into an exact science. Now it is proposed to put that ac- cumulated knowledge to work to build automobiles which shall be faster and cost less to operate than anything seen heretofore. “The en- gine, to begin with, is in a fair way of being relegated to what is described as its natural position, over the rear axle. Mod- ern motors do not require such constant attention as to make extreme accessibility necessary; the starter has displaced the crank, and, in short, the principal reasons for having the engine under a front hood are gone. Next, the falling raindrop 1s being reproduced in wood and steel, just as it was in wood and fabric for the air- plane, and the result made into comfort- able automobile bodies. The latest thing in streamlining is designed to eliminate not only the vacuum drag against the rear of a car, but the power-absorbing swirls in the air, which cut down speed and leave clouds of dust floating behind. The new bodies slip through the atmosphere with so little disturbance that the air currents slide back into place and the dust is hardly raised above the road The science of streamlining is founded on natural phenomena — the graceful curves produced in running water as it slips around a stick or other obstruction, for example. Most people have watched a stream as it is divided by a bridge pier or rock or perhaps a fixed snag, only to slip quietly together again. Nature likewise has produced a perfect streamlined body — POPULAR MECHANICS in the fish. The comparatively bro: head of a bass or trout cleaves the wat: while the severed streamlines flow 1 gether again down the long taperi: body and tail with hardly a ripple. An automobile isn’t a boat or a fis but like them it displaces a fluid elemen: —air—and the same laws which app to water navigation apply to an obje: moving through air, for when t! atmosphere meets obstacle it acts in the same way as wate! It is true that air is nearly a thousar times less dense than water, but the sur face presented by a motor car is almost thousand times bigger than that offere: by a fish, and a car moves at a much highe: rate of speed, so that the reaction of th« displaced air on an automobile in motio is proportionately much greater than that of water on a swimming fish. Wind-cut ting shapes, “torpedo” bodies and boat shaped designs for racing cars, have bee used by automobile builders for seve years, but the airplane wind-tunnel test show that almost without exception the are scarcely more than a matter of fashio: and hardly take into account the lines o! least resistance. Bodies which seem to “cut the wind” actually offer practically th« same air resistance as rectangular block: according to Jaray, one of the leadin; European designers, who for ten years ha helped improve Zeppelin designs. His investigations show the wind resist ance of an ordinary car going at twenty two miles an hour eats up sixty per cent more power than a streamlined body o1 the same chassis. At forty miles, the wind resistance increases the power con sumption by ninety per cent, and at fifty the excess energy used because of resist

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r ards, buggy lamps, carriage wheels and the mysteries of the invisible air cur- POPULAR MECHANICS 389 Ley Chassis, with the First Perfectly Streamlined Body Built by a German Aeronautical Engineer Procession of Streamlined Cars Passing the Old Imperial Palace in Berlin, and Right, a “Rain- | drop” Car De- signed by Doctor Rumpler, Cre- ator of the Famous Taube Airplane The Smooth Lines of the Ja- | ray-Type Body, on an Andi Chassis, at Left, Run from Stem to Stern without a Break, While the Overhang ee . Removes the Wind Resist- OS a “ zm IL ance of the Wheels ‘|

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390 ance of the atmos- phere is 110 per cent. He conclud- ed there was only one way to effect- ively streamline a car, and that was to inclose every part, even the wheels, in one streamlined body. Wind-tunnel experiments indi- cated that the greater volume of air displaced by a car should pass over it, while the air near the ground must remain hori- zontal, so as to stir up no dust. Even- tually he worked out a shape which approximated the upper half of a dir- igible, cut on a horizontal plane and placed as near the ground as pos- sible. Actual tests POPULAR MECHANICS AAAALALL Wind- Resistance Diagram ; Top 100, Second Five, Third 100, and Bottom Twenty-Five Per Cent showed wind resistances of one-quarter to one-third that of ordinary bodies. means that when a sixteen-horsepower car is running at an aver: That age speed of twenty- two miles an hour, or when a forty-horse- power car is running at an average of Streamlined Bodies on Ley, Andi and Dixi Chassis Passing through Brandenburg Gate the Famous in Berlin thirty-one miles, saving of close t thirty per cent fuel is effected. A higher speeds tl saving runs much as forty, fift per cent or more The result is tl the driver wl slows down wh« passing throug villages and tow: and then speeds u on open stretch: to keep his averag: rate normal, actu ally saves more fuel than if he ha maintained the a erage speed for thi entire distanc: Cars with the ne bodies which have been operated Berlin and Londo: have attracted cor siderable attentio: because of the p« culiar design, but the builders deny that the machines lo “freakish.” They rest their claims o the assertion that if nature had ever bui a motor car she same design they would have adopted, to g have taken th: the greatest efficiency.

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0 POPULAR MECHANICS Rail Motor Cars for Passenger Use on One Hundred and Fifty Lines Popularity of the gasoline and electric tor as an aid to the steam railroad is wwn by a recent report ued by the National nuk of Commerce, stat- that 157 lines were ge motor coaches in e passenger service at e beginning of 1924, at st of from one-third one-fourth of that of e regular equipment, | that trucks are being dely employed as eeders” to the main nes. The chief service these smaller vehicles believed to lie in sup- jementing the steam trains. The report states that motor trucks are sed mainly on the short iuls, a study in Connect- ut showing that about irtv-seven per cent of he tonnage moved by isoline carriers was iuled less thanten miles, thirty per cent more than ten and less than thirty miles, and only fourteen per cent more than sev- enty miles. As a solu- tion of terminal conges- tion, the motor truck, by hortening the unloading ind handling time of reight, releases many regular cars for long wuls. Surveys show hat an average freight ir occupies nearly fif- teen days to the trip, but { this time, it is actually moving or delaved on the line in haul only i little over a day and a half. Radio Aerials Not a Menace The limited extent of radio aerials is de- clared by the bureau of standards to pre- ent them from becoming any more of a lightning menace than rain spouts, metal clotheslines or tin roofs. If provided with arresters or properly grounded, the report says, they may serve as effectually as light- ning rods in draining the current from the air, but may become fused or torn from their fastenings by a direct stroke. 391 Picture on the Outside of Church Teaches Bible Lesson Reversing the usual custom of decorat ing the interior walls with symbolic paint German Church with Its Exterior Mural Painting Depicting the Four Horse men Mentioned in the Revelation of St. John the rector of a church in Germany has had a large mural placed on the exte rior where it may be plainly seen by mem bers of the congregation and all who pass the doors. ings, Che work was done by a noted artist and depicts a scene from the Book of Revelation. A smooth surface and ab sence of obstructions in the gable of the building made the painter’s task easier. @We want all our readers to write u: freely and often whenever they wish ad ditional information on articles published in this magazine. Address Bureau of In- formation, Popular Mechanics, Chicago.

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392 POPULAR Press Prints Many Colors at Once Using Paper Instead of Ink Show cards, signs, tickets and similar matter can be printed quickly and cheaply in several colors at a time on an ingenious press invented in England. It uses strips of colored paper instead of ink, impressing them in- to cardboard after the manner of an embossing machine. ' \ - . ce sat Ls ad Pressure on Lever Stamps Colored-Paper Letters in Place of Ink on Cardboard Sign Loose gun-metal type is used and is forced against the stock by means of a lever ca- pable of developing sufficient pressure with only slight effort from the operator. The outfit eliminates the need for typesetting frames and other equipment, reduces the cost of the job as only one impression is necessary to make as many colors as de- sired, and the finished sign is said to be more distinctive than an ordinary printed card as the letters stand out vividly against the background. Wrench Worked with Single Hand Is Easily Adjusted Telephone linemen, steel workers and others who often can use only one hand at a time, are supplied with a serviceable tool in a quickly adjusted spanner, or wrench, that fits tightly and has a wide range of usefulness. A ring jaw slips ov- er the nut or pipe, closing automati- cally with the aid of a spring, and pressure is applied from the handle through a cam-shaped stub at the end. The tool can be placed in work- ing position with only one hand, enabling the workman to hold on with the other if necessary. The head will fit almost any size nut up to its capacity, and other tools are not needed to supplement the wrench. MECHANICS Dog Teams, ‘‘Autos’’ of the North, Travel Forty Miles a Day What the motor car is to the macadan ized road and the camel to the sands oj the desert, the dog teams are to the froze snows of the northlands, where thes: powerful animals for many years hav been playing an important part in the d¢ velopment of regions whose extreme col and lack of other transportation faciliti: restrict travel. Used largely to assist con mercial enterprise and explorers, the dog also help forward the interests of justic« and order. The Royal Canadian mounted police corps has 128 trained huskies in it service. A trained team can make fort miles a day and maintain this speed for days. Each is hitched to haul a load oi about 125 pounds and, as a rule, teams ar: composed of from five to seven dog Oxyacetylene Gas Tank Regulator Prevents Fires and Explosions Pressure of oxygen and acetylene g: is said to be automatically regulated wit an attachment for welding apparatus that has been de- vised to reduce the likelihood of fires and explo- sions. Both gases are controlled by a single wheel fit- ted with ball bear- ings for easy turn- ing. Pressure readings for both tanks are plainly visible on the gauges of the instrument. In addition to greater safety, the device is said to pro- duce a more efficient flame. Insects Practice Arts Known to Man and Excel Him in Skill everything That insects do almost known to mankind whom they excel in skill, is the belief of a well-known nature student, who spoke before a meeting of the American Institute of Phrenology. While the less developed species live un- der rocks or in the earth and exist by hunting, trapping and fishing for prey, others colonize in large communities and keep herds, raise crops and use leaves for clothing and shelter. Many insects ever build tiny streets and highways, tunneling

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POPULAR MECHANICS d bridging where necessary, to aid them their travel. Various systems of gov- ment resembling those of man have en observed among them, and wars are ried on between tribes in which every of attack and defense ployed by modern itarists practiced. sonous liquids, gases | powders serve as am- nition in addition to all bulletlike projec- that identify several the more warlike ecimens. To _ escape ervation by their mies, the individuals some types resort to vuise and camouflage. rapid travel, some nstruct aerial carriers vhich they sail rough the air while ers build small floats traverse water. Ac- tic bugs have been found which use rt of submarine boat to penetrate be- ith the surface. The speaker also stated it man has learned the art of making fume from the insect world. is Air-Filled Upholstery for Autos Gives Greater Comfort neumatic tubes are being made to fill itomobile cushions in place of springs, ids and other built-up upholstery. The ibes can be quickly blown up by an ordi- iry hand pump or deflated and removed hen not required. Designed so they can e folded to the shape of the cover and present an even surface, the tubes are ’ aimed to eliminate all jars and shocks to assengers caused by the road or engine. ecause they need but very low air pres- ire, they afford soft, comfortable seats d reduce wear on the coverings. to-Seat Cushion Filled with Which Folds into Smooth, Pneumatic Upholstery Springy Padding 393 Writing to Fox-Trot Record Improves Penmanship Pupils in penmanship at a New York school are said to be greatly aided in ac- \o Students at Desks and Blackboard Practicing Penmanship to Rhythm of ance Record Phonograph Is Playing on Teacher's Desk quiring legible and graceiul handwriting by the rhythm of fox-trot and other dance records played on a phonograph in the class room. The beat of the music and its regular cadence help in making smooth and properly formed curves as the hand naturally keeps time to the selection and the writers are encouraged to do more work than they would if left to their own devices. Correct strokes are demonstrated by pupils at the blackboard for the benefit of those at their desks. Shining Tower of David Discovered among Ruins in Palestine Ruins that are believed to have been the walls and buildings of the city of David, have been discovered after extensive ex- cavations in Palestine under the direction of J. Garrow Duncan. The original Jebu site wall of the fort, which was standing when David took it in the year 1000 B.C., has been traced, it is claimed, and the gleaming white-limestone surface of a magnificent tower has been exposed to the light of day and is now visible from all parts of the city. The discovery appar ently settles disputes as to the location of the city, and seems to prove that the has been continuously occupied for over 5,000 years, some of the pottery un earthed at Ophel near by is said to belong to the cave-dwelling period of 3000 B.C and earlier. The Palestine government has set the wall apart as a national monu ment, and the tower is site as being restored

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394 POPULAR MECHANICS Bicycle Converted into Key Factory Nets War Veteran Profits About the only asset a Detroit man had after four years’ service with the ¢ forces World War ‘anadian was a bi- during the Bicycle- “sae Key Factory and Veteran Operator with His Sign and Samples of His Wares cycle. Applying his skill as a tinker, he rigged a series of emery wheels and circu lar files to the sprockets, rented space be- tween two doorways on a busy street and established himself in the key-making and knife-sharpening business. by elevating the rear wheel and sitting in the usual riding position, he was able to pedal the gears and grinders with sufficient speed to make a key from a blank in about a minute and sharpen knives and sors while the customers waited. Shifting the chains and lowering the wheels fits the bicycle for riding home at night, and the trip to work in the morning is taken in the same way. The veteran savs he averages about 200 keys a day and esti mates that he has pedaled the equivalent of a 100,- W0-mile journey in the last five years while oper- ating his unique shop. On busy days, receipts from the factory total $50 and more. SCIs- Rogues’ Gallery of Handwriting Helps Identify Lawbreakers By means of a file of handwriting spe mens of known criminals, the police Berlin are able to identify many lawbrea| ers who might otherwise escape detecti when suspected of evil deeds. Samples their writing are taken from convicted « fenders under suspicion, at those whose signatures have been forged and experts compare these with the record ed examples. Burglary evidence is soug! by a special squad of detectives whose processes of study are similar to those en ployed in gathering data for murder case Fingerprints are taken of all those a: rested for crimes and impressions of th palms of the criminals’ hands are also filed away for future use. persons Man-Made Bumps Test Auto Tires and Foretell Wearing Qualities Automobile tires standards sent to the bureau of for examination, among othe: tests, are given a long, bumpy journey against a rough-rimmed wheel to dete: mine their wearing qualities. Two tires are tested simultaneously. They are i: flated to regular running pressure an bolstered up against the big center whee until the approximate weight they car on the road is obtained. Then the teste: is started, and as it revolves, the tires thud over obstructions placed on the rim to represent street and pavement bumps. I: less than four days of this stationary run ning, the inspectors, by carefully measur ing the wear of the tires, can tell hoy long the rubber will last under service. © U. &l Bumps on the Big Center Wheel Wear the Two Auto Tires as Though They ere in Service

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T Wem FO;GS INtO OOO, OPlimey * auurne eeeweese See oS wT SS = _—elUCU rh Ow Ee S,lClCF OU we a ee POPULAR MECHANICS 395 With the Mechanical Helm Holding the Ship to a Truer Course than Mest Exverienced Pilots Could Do, the ° Coxswain Is Relieved to Keep a Sharper Watch along the Route How the Gyro Makes the Earth Work Spinning Wheels Help Man to Cross Seas, Defy Elements and Conquer Nature THe child who watches a spinning top may not know that his rotating toy evs a fundamental law of the universe h binds the turning earth to the sun d rules the motion of other universes ithin the confines of the star dome. But if the theory of modern scientists is orrect, the movements even of electrons infinitely small particles of matter are roscopiec rotations much like those of e planets in their orbits round the sun. ight, too, is thrown on other terrestrial ldles. The gyroscope is a rotating heel, which, when turning on an axle llowing it to move freely in several di- ections, resists attempts to change the irection of its axis er spin. Its peculiar owers will cause a train to run at high peed on one rail across a gulf bridged by teel-rope rail; stabilize a rolling ship a heavy sea; guide the sailor and avi- or in fog and darkness; help the gunner the turret of a modern battleship to rain his ordnance on an elusive target. ihe true type of the gyroscope is the ic earth which has been rotating on its axis ver since it was thrown off the sun count- ess ages ago. When Columbus sailed for the new world, he carried a magnetic compass which fairly accurately pointed to the magnetic north; but, today, the battleshi or the liner, built of huge masses of stee and iron, cannot rely altogether on its magnetic compass which is liable to devi- ation caused by the influence of the earth’s magnetic field on the iron of the moving ship. The modern navigator therefore calls to his aid the gyro-compass. This wonderful instrument is an application ot the fact that a spinning gyroscope to which a weight is hung, will, under the combined influences of gravity and the rotation of the earth, point to the geo- graphic north-south, and turn in the same direction as the earth. Today, every officer who aspires to pro- motion in the American and British ne vies and mercantile marines has to keep abreast of gyro-compass development and especially of that invented by Elmer A. Sperry, and first installed on the U.S.5 “Delaware.” The nerve center of the Sperry gyro-compass is a master compas placed near the ship’s center line wher rolling is felt the least. Essentially, it 1s ) ] i

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396 a three-frame gyroscope, the peculiarity of whose mechanical system is that it is not interfered with by the movement of the body (in this case, the ship) to which it is attached. A motor generator, worked by the ship’s dynamos, runs the gyroscope in the master compass, which 1s controlled from a switchboard. Mastery of the waves of a heavy sea, and consequently of seasickness, has been es- tablished by a gyroscope placed amidships. Here the waves made to stabilize the rolling and pitching ship. The axis of the Sperry oy ro-stabilizer is in a vertical plane, and when the waves hit the ship, the gyro tilts at right angles to the direction of the wave force, thus neutraliz- ing its effect by passing it out at right angles as an equal but opposing force. A pilot gyro controls the main gyro, and sets it working in opposition immediately the beginning of a roll is felt. An exceedingly interesting part was played by the gyro-compass in the Euro- pean war. At the time of the battle of Coronel on the west coast of South Amer- ica, the British battleship “Invincible” was being overhauled at Portsmouth dockyard in England. She was immediately ordered with one other large British ship to South American waters to reinforce the British fleet, and then to find and de- stroy the German ships which had defeated the British in that battle. She was ready themselves are Elmer A. Sperry and One of His “Gyro” Ship Sta- bilizers, Designed for a Large Passenger Liner POPULAR MECHANICS to leave tiie docks when it was planned | delay sailing until the ship could be swung and the magnetic compasses compensated It was decided, however, that, althou the compasses were badly in need of ; justment, it was necessary to save eve: minute in order to reach South Ameri waters before the German ships could f and destroy the British ships remaini there. The “Invincible” therefore sail without adjusting her magnetic compass: and navigated entirely by the gyro-cor pass from Portsmouth to the Fal! land Islands. Here observations wet taken and the magnetic compasses were found to be out about twenty-two degree The “Invincible” arrived at the Falkla: Islands just in time to coal before t German fleet appeared. Nearly every ship in action at the batt of Jutland was equipped with a gy compass, one of which, on the battleshi; “Lion,” worked in a fire so hot that t lead sheathing on the electric cables fuss and flowed like water. Gyroscopes will also show a ship’s cap tain whether he is moving on a straight line or curved course. A two-frame gyri scope is here used, because such an ir strument moves in unison with the bod to which it is attached. A _ telescope mounted on the axis of a gyro scope, placed on a ship’s deck, wil keep a target in sight howeve much the ship rolls. This i achieved by the “fixator,” whic prevents the gy roscope fro1 wavering so long as the tel scope points to t! horizon. Naval gui

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POPULAR MECHANICS 397 J & AUXILIARY WHEEL ~® FOR) ALTERING URS COURSE. Be oiee). RA Zelaae USED IN THE COURSE OF THE VOYAGE ee ple APTRC | || / ZZ yi ‘ { — MAGNETIC COMPASS | LEVER FOR THRO® Y. = lo Repmeltnaek GEA ue Ee | F REQUIRED BY REQ NET CALM SEA _ } HIP’s @ COURSE | AVERAGE YAW 1} a | | | | e HEAVY SEA | Ships That Steer Themselves with the “Gyro” Pilot Resist Yaw and Are Automatically Returned to the True Course: by Means of a Lever the Handwheel Can Be Thrown into ear When the Helmsman Is Required to Guide the Craft through Shipping in Crowded Harbor Waters Copyright, The Illustrated London News

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398 may be trained by means of gyroscopes and stabilized against rolling. The firing and recoil of such guns interfere very little with the spinning of the gyroscope on its cradle pivots. Even on the roughest sea, the gunner can do his work quietly if his chair is fixed to the cradle of the gyro gun. The navies of the future, according to ex- perts, will no longer consist of gigantic dreadnaughts. Their vast iron bulks will be modified by the gyroscope into small ships weaponed with the heaviest ord- nance, stabilized and trained on the rough- est seas bv these swiftly revolving disks. Next to. stabilizing ships in rough weather and furnishing compass guidance for them over the seas, the most important commercial application of the gyroscope, so far, has been in the automatic steers- man, which can guide a ship through heavy seas on a far straighter course than any helmsman could possibly steer. A ship’s movement in cross seas is exceed- ingly erratic. The buffeting water causes a big vessel to slew off at an angle. The magnetic compass in front of the steers- man records the change, and he then spins his wheel to bring the vessel back. All the operations, however, require time, and there is an appreciable interval during which the ship 1s falling off or returning to its course. There is a lag in the mag- netic compass before it records the change POPULAR MECHANICS of direction, another lag while the stee: man spins his wheel, still another wh the steam steering gear is getting under way and putting the rudder over, and th: another while the ship fights against tl rudder and slowly swings back toward ji course. Usually the vessel will swing too far, and must be jockeyed back again. The gyro steersman is much more se sitive to changes of direction than the o1 dinary helmsman’s eyes and will move t! rudder over before the man with a hand wheel would even be aware that the sl! had changed direction. Once set on a straightaway course, it does not need to be touched again until a change in directior is necessary. A small auxiliary wheel used to change the course set, while a gear is provided to cut out the gyroscope and connect up the handwheel for use steering the ship through harbor traffic Commercial aviation is largely depend ent on the perfection of the gyroscope When white fog comes like a ghost upo: sea or land hiding the aviator’s beacons and landmarks, he has the “gyro-orth« scope” to show him whether he fli straight or swerves. A pointer on a dial standing at zero, shows that the aeroplane is approximately on a straight course Deviations of flight to right or left are i: dicated on a graduated scale, and the lea angular movement of the aeroplane caus« Class of Engineers, in Study of Gyroscope Instruments, Receiving Instruction in Installation and Operation of the Devices as Stabilizers and Truing Implements on Ships and Aircraft

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i. and ope po! "ons tho flies dial, lane irse

ion

POPULAR MECHANICS 399 embled Gyroscope Stabilizer Ready for Test and Installation on a i cer Using a ‘Polerus” dern Vessel; Right, Naval ation and Direction of Travel by Sightin jects Whose Positions Are Accurately rresponding movements of the gyro- ope. The railroads of the future also ay be very different from those we know lay. A citizen of a great city, fifty years ence, may look up into the sky and see a train running at high speed, not on two ils along costly viaducts and permanent ays, but on a single rail, or even a steel rope spanning the gulfs of air between the skyscrapers. In this transformation, mechanism such as that perfected in 1924 by a distinguished tussian engineer, may play a great part. ‘le has invented a monorail car which is single gyroscope mounted on a vertical <le, and rotating vertically. Dynamos nd motors supply the power rotating the roscope. It can also be made to rotate orizontally about a horizontal axis. Pen- ilums, on each side, come into action if he car leans. They cause a ratchet to en- ige with a rotating cogwheel attached the gyroscope’s axle, and to restore the equilibrium of the car by hurrying the pre- ession or return to the vertical position of e gyroscope’s axle, Special devices are ised for easily rounding sharp curves, and or maintaining equilibrium. The mono- ail system halves the length and weight sleepers, and permits a speed of 120 iles an hour. Giant cars have been de-

the Instrument across Ob- hown on Ocean Charts =

to Determine

signed, for main-line and suburban rail- road traffic, capable of carrying 400 people. Gyro-railways would be useful in hilly districts, since heavy embankments would not be required, and the cars, carrying double-flanged wheels can ascend gradi- ents of one in eight as against a maximum of one in twenty on the ordinary railroad. As the car rounds a curve, an orthoscope comes into play, the axle of which is con nected to a valve controlling a com pressed-air system. The compressed air enters pneumatic cylinders and restores the equilibrium of the gyroscope. In 1921 the construction of twenty miles of a gyro-railroad, for the Russian gov- ernment, between I’sarskoe Selo and Petro- grad was begun. Seven miles of this mono-railway track were laid, when diffi culties of finance and rolling stock tem porarily put a stop to the project How many thousands of lives and mi lions of property might be saved, vearly if there were some means of foretelling the course of cyclones and hurricanes! An American meteorologist points out that cyclones, which are rotating masses of air whirling in the same direction as the earth’s surface, possess gyroscopic prop erties. Some day this fact may be applied to the prediction of their paths. 1

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100 POPULAR Post Offices Used as Billboards Yield Government Profits Bavarian postal authorities have devised a source of revenue for the department by setting up post-office kiosks of odd Copyright, Keystone View Co Odd-Shaped Bavarian Post-Office Substation Plastered with Gaily Colored Advertising Signs shape in the public parks and renting the exterior walls as billboards. The sides of the structures are arranged to form forty or more narrow panels, and in each of these is placed a highly colored poster ad- vertising commercial The plan helps to attract the public to the offices and places the signs where they are seen by hundreds of persons daily. Wwar®res. Real Rubies Can Be Told from False by Shape of Bubbles They Hold Rubies, like diamonds, ly imitated, but by a few simple tests, the genuine can be distinguished from the artificial with comparatively little trouble. \ real ruby contains irregularly shaped bubbles, while those in the imitation are perfectly round, according to expert gem testers. Is also have a have been wide The natural jewels silky sheen due to a number of tiny paral lel lines in their structure, a characteristic false specimens do not possess, and they are four times heavier than water so that MECHANICS imitations of to detect Genuine rubies are a c1 talline form of a mineral called corundu; it is not difficult light weight. and the best ones are mined in Bur: Thousands of tons of soil must be dug up washed and minutely examined to coll the precious stones. Strong lights, po erful magnifying glasses and drops of placed on the gem, if it is in a setting sist the examiners in detecting imperf tions and imitations. Artificial rubies clude those made of “paste” or color: glass, cheap red stones of little value t resemble the precious article, and imit tion corundum manufactured by a cher cal process. Flaws and blemishes in t real stones are the clues by which tl genuine gems are distinguished from false, but the fewer imperfections the have, the greater their value. Card Index That ‘“Thinks’’ Saves Work of Many Clerks Saving of time and a reduction in number of files are claimed for an ince system for large or small means of slots in the cards and small ste« rods, information may be obtained fri the records by simply turning the cabinet upside down. The slots allow only tho cards which are wanted to fall out alinement. The rest are held in place rods passed through holes. Those tl are to be studied are then kept in an acce sible position until it is desired to retu them. Various combinations of data ma be arranged and with the slots put in co responding positions, the same file can offices b Even a Child Can Insert the Rods for Releasing Selection of Cards from File made to serve a number of purposes. T! cards are easily perforated on a han punch, and the outside of the drawer cot tains the key to the system of holes ar that the rods may be inserte in the proper places. slots. so

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ing POPULAR MECHANICS 101 Touring Car and y Truck, with Inserts g Partial Conversion for t, and Rear View of Auto 'p for Pleasure Driving Touring Car and Delivery Truck Has Seats That Fold on Floor Combining a pleasure car and a delivery ‘*k, an automobile body has been built rear seats that fold on the floor and a which can be opened out as a tail- e. Change from one type to another be accomplished in a few minutes hout injuring the upholstery. When it part of the vehicle is needed for reight, half the seat may be closed up, iving room for one passenger in the rear partment. For emergency deliveries, e body can be pressed into instant serv- and restored for pleasure driving after e load has been removed. Camping uipment and provisions can be carried overland journeys and the car used for uring trips when stops are made. Mufflers Wrecked by Gas Blast to Test Their Value To determine whether automobile muf- rs will withstand the gas explosions to hich they are subjected, the underwrit- rs’ laboratories have developed an appara- tus by which a muffler can be blown up, » determine just how much pressure it ill resist. The device to be tested is con- nected to an exhaust pipe which projects through the wall into an outside chamber lined with heavy steel screens to stop fly- ing parts of metal. The engine is turnéd over with the starter until the exhaust pipe and muffler have been sucked full of vaporized gasoline. Then, the charge is exploded by means of a spark plug and blasts of varying degrees of intensity are repeated until the muffler is blown to pieces. The interest of the underwriters lies in determining the fire danger, and the results of the tests are used by insurance companies in fixing fire-insurance premi ums on Cars. tive-testing department is equipped wit! a six and a four-cvlinder engine, mounted on test blocks with a sing! board, provided with recor 4 gas, water and oil, and revolution indica The laboratories’ automo e instrument : lis &- gauges Ior tors, while each engine also has a brake horsepower indicator, which can be used not only to register the power developed, but also to put any desired load on the motor. The friction is so great, when the engines are loaded by applying tl yrak ing device, that a water connection i vided to cool the braking flywheel @ Ants identify their enemies and friends by the sense of smell, experiments have shown.

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102 POPULAR MECHANICS Reflector Coating on Electric Bulb Stops Glare and Focuses Light Electric bulbs for a wide variety of uses, carrying their own shades in a reflector Lighted Reflector Bulb Directing Glow upon Work- bench, and Detail Showing Globe Coating coating part way down the glass, have been placed on the market. Glare is pre- vented by them and seventy per cent of the light directed downward through the clear section without a shade attachment. They are, therefore, particularly suited for installation over machines where extra il- lumination is needed, for drop lamps to be used about the shop or garage, and for reading lights, it is claimed. Sound of Electrons Heard by Radio in Vacuum-Tube Amplifier By means of the radio vacuum-tube am- plifier, scientists have been able to hear the noises made by electrons, the infinitely small units of electricity as they are “bom- barded” against the plate in the tube from the hot filament. These electrons, it is held, carry the current and make possible the operation of the tube, which is capable of tremendous amplification. Through this, a new way of measuring the value of the electron charge has been developed, and a method of research opened which may lead to valuable knowl- edge concerning the electron and its | erties. Previously, it has been studie means of tiny drops of oil, observing movements between two. electri charged plates. Droplets are made t: slowly or rapidly or are held statio: between the plates, according to the | ence of charged electrons in them and t voltage applied to the plates. With pr amplification, the roar of the electro: the tube can be magnified to produ: volume like that of Niagara, it is said, this action is to be studied in the hop: that facts not presented in the gra tests will be learned. Portable Crane, Built like Sawhorse, Saves Farmer Time and Labor Pulling stumps or posts, holding hog in the air after they have been slaugh- tered, stretching wire and doing m other farm tasks may be simplified great! with the aid of a portable crane invented by a Texas man. It is constructed some- what like a sawhorse, and, in fact, may be used for sawing wood when necessa A center crosspiece, used as the wind drum, is provided with two cranks, on: each end, and a steel cable with grapplins tongs. With little difficulty, the appa: tus may be adjusted for hoisting ob): such as wagon boxes, pulling horses cattle out of bog holes or for dragg telephone poles. The lifting power of average man is said to be multiplied se ’ ee ee mama Sawhorse Crane with Its Two Handles Is Carric About Easily on the Shoulders times with this outfit although the enti equipment may easily be carried about « the shoulders.

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ak ro DI . . yarric nti! It ¢ p= POPULAR MECHANICS 403 . a Skilled Artists Complete Every Detail of Proposed Outdoor “Ads” in Miniatures Which Serve as Guides and Models for Sign Painters Who Accurately Produce Enlargements of the Designs Recruiting Art for Outdoor Advertising Millions Spent Each Year for Ornamental Trade Messages That Speak with Picture and Story along Nation’s Highways [NS1 EAD of daubing merchants’ ads on tence boards, barn sides, and coarse s that once might have offered a suit- le surface for the lurid colors of the nerant sign painter, the industry of out- oor advertising now devotes almost 100,000,000 a year to artistically designed nels and huge ornamental frames rinted or painted with works of skill nd beauty. \ccomplished artists who specialize in riginating attractive subjects for their create the pictured messages in niature form which are first treated to series of tests for their value in luring e eyes of the millions of travelers they re designed to reach with their stories. rews of sign painters are constantly kept work transferring these originals, en- rged to many times their size, to bulletin ards and illuminated panels erected at ntage points throughout the country. Vhere paper posters are to be used, li- | print gigantic rushes ographers sheets on which the paintings are faithfully repro duced. Each sheet carries a section of the design, and these are finally assembled i1 proper order by the poster who piace them on the outdoor boards So popular method that there is now or city avenue w ded with : brilliantly illuminated by tric lights at night. A corps of judges of locations are at work parts of the nation seek for the permanent boards, studying become in the thirty hardly a *h past pa hic colorful signs, many of has the outdoor di D countr has not been a blaze of cing new po volumes over boulevards, and m« 11 distances between highways and prt nent points that afford suitable settir for outdoor advertising surfaces In the old days, when a paste pot, or paint bucket, and brush were the sole too of the poster’s trade, verbal perm from the owner of a plot of ground o abandoned barn was suthcient to est blis!

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the worker’s right to the desired space. Often a rival, dis- daining priority, might erase the re- sults within a few days and apply other sheets or lettered signs, to be followed by others who in their turn would make similar substi- tutions. But today the great sign-post- ing and painting con- cerns enter into thousands of con- tracts for space and position rights every year, paying a speci- fied rental for the privileges to loca- tions whose value as advertising mediums sometimes brings several thousands of dollars annually to the owners. With the increasing use of electricity, an organization of electricians, skilled in the wiring and mechanical equipment of out- door displays, is necessary for almost every posting company. Elaborate ar- rangements of lighting are designed to automatically switch on and off at proper times of the day and night. Often devices are introduced to control a series of flood- lights which change regularly, adding greatly to the attractiveness of the sign. Until recently, most of the huge boards which carried the advertising were con- POPULAR MECHANICS structed of wood, but now the surfaces made of sheet metal and in many ca are prepared to take either painted desig or pasted paper sheets. Others designed and painted complete in the workshops the posters are constructed of metal s: tions and transported to the scenes of d play for assembling. When an artist has finished the origi: design for an outdoor advertisement, picture or model is photographed. Fri this a plate is made for inserting into projecting machine which throws | image against a large wall marked off in thinly lined squares. This scale aids 1 workers to confor: the completed sign to the dime sions of the boa: it is to cover. Sheets of pounce paper are then placed agai: the wall and t! image is traced wit a perforating devi which outlines ea: figure and letter pe: fectly, to guide t! artists who produ the enlarged patte: All sections of t! marked paper ar numbered to indicat: their positions in th: Tracing and Coloring the Picture and Adding Finish to t € Design A

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POPULAR MECHANICS ¥ Zuo iw % arty 2 es 3 o_o - =? Vx % From a Plate in the Projecting Machine the Enlarged Image of the Picture Is Thrown on a Scaled Wall Where It Is Copied in Perforated Tracing on a Paper Pattern Sheet

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106 finished design when it is finally trans- ferred to the permanent surface. Piece by piece, the subject is accurately outlined on the board, and the artists place the col- ors in an exact but enlarged duplication of the original painting, following in every detail the small model. To change positions as the painting progresses, the artists are provided with a rolling scaffold which can be moved with little effort, making repeated descent from its raised platform unnecessary. As each section of the metal sign is completed, it is removed from the supports and allowed to dry, after which it is coated with a cov- ering of weather-resisting varnish. When the whole layout is finished, the set of metal pieces is transported to the location where they are fitted into the framework of the bulletin board to remain during the period of the advertising program. It was about 1890 that the old “slat” form of advertising-display board was first used. Out of this the permanent wooden surface developed, to gradually change into the method employed at present, con- sisting of all-metal surfaces. With this change, the demand for better and more artistic designing increased, while the steel sheet background affords a superior “can- vas” on which the artists can work. Paper posters for similar display have practically passed through a like change of treatment and preparation. The flam- ing sheets that once glowed luridly, tacked or pasted on whatever offered a support in the neighborhood of streets or road- ways, are rapidly being supplanted by POPULAR MECHANICS more beautiful lithographs set in la frames resembling the “gallery” vari The one-sheet “snipe” with its glaring | tered facing, though still seen in many calities, is decreasing in numbers and its stead the twenty-four sheet poste: fitted on an attractive steel-surfac: board, surrounded by an ornament molding and plenty of white border spa blends with natural backgrounds. Due to improvements in the process printing the sheets, almost any work of can now be faithfully reproduced for the outdoor display boards. Care is taken the poster services to remove and repla any paper displays that may be tatter and worn or stained by the wind a: weather. quality of pastes so as to prevent deta: ment from the board during high wind 3efore a design is passed for use on t outside, its color scheme is subjected several tests to determine the clearness the letters and figures at great distanc: Preferred positions, such as on the curv: of automobile roads where cars must slo down, are treated under a different set details than the equally valuable locatio: along a much traveled railroad right way. For these experiments one concer has made a large boxlike device with arrangement much on the order of a ster¢ opticon. At artist's small original is placed and the o; erator views the sign through eyepiec: This process is said to duplicate the con ditions generally met with in the insta lation of the large signs outdoors. As Each Section of a Metal Sign Is Finished by the Artists, the Piece Is Covered with a Coating of Water- proof Varnish to Preserve the Delicate Shadings from the Weather one end of the device th: Much attention is given to the

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POPULAR MECHANICS 407 Above Is Shown the Cameraman Ready to Photograph the Model Signboard Design; Cen- ter, Developing the Plate from Which the Enlarged Image Is Pro- duced by the Projector the Tracing Room; and Below, Reproducing the Original Drawing ‘ the Scaled Wall Where It Is Propor- tioned to the Dimen- sions of Its Frame; the Squares Aid in Adjust- ing the Size to the Nec- essary Measurements

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408 POPULAR MECHANICS Monument of Giant Figures Recalls Sweden’s Champion of Liberty A group of colossal figures, each more than three times the height of a large man, ™ ” Sa Ey -= ¥ Section of One of the Colossal Figures Which Are to Compose a Huge Monument to the Memory of a Patriot of Sweden ; are being worked into a monument erect- ed in memory of Sten Sture, a patriot of Sweden who lived about five centuries ago. The subjects of the sculptures are taken from among medieval characters. Fully armored knights have been vividly portrayed by the sculptor, Karl Milles, and although all of the figures are in several parts, the pieces must be handled by pow- erful hoists to set them in place. The site is near Upsala and the group is being partly assembled before the various sec- tions are raised to the supports. World-Famous Painting Is Restored with Electric Iron and Heater With the aid of an ordinary ele heater and an electric iron, Leonardo Vinci's “Last Supp: one of the most fan paintings in the w has been restored saved to posterity. N long ago it was fou that the glowing co! were losing their beau and that portions of 1 paint had become tached from the wall the refectory of Sai Maria delle Grazie in } lan, where the g Italian artist painte: five years after Colum) discovered America. examination showed t! moisture was conden: on the paint just as condenses on the wind panes of a room whe: is cold outside. An ope ing was made in the \ between the _ refecto and the room behind, a: an electric heater was stalled in the latter. T! warmed the wall and once stopped the dar ness. The problem saving the loosened pai was more difficult. troleum was injected int the plaster from back, with syringes, later a quantity of liqu rosin. With this foundation, an_ elect: iron was applied and t paint scales gently iron: back into place. 1 area was then varnishe to insure the paint’s se’ tling firmly. The varnish coating was nally sponged off, and the masterpiece now said to be in perfect repair. Té ] Cross-Word Puzzle Centuries Old Seen in Ancient Disk Although the cross-word-puzzle ide as it is now presented for the entertai ment and distraction of millions, is said t have originated in the fertile mind of newspaper reporter, there is a possibilit

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POPULAR MECHANICS 409 ed is form of brain teaser really dates about 2000 B. C. At least such is ication of a copy of an ancient ter- ‘ta disk in the museum of the Johns ns university. The original came ie island of Crete and bears on both 1 continuous spiral line of picture ». No one has been able to decipher nee it is not known whether the leg- gins at the center and runs out- or the reverse, or whether the char- should be connected vertically or intally. The curiosity is known as aestus disk and, although a Ger- cholar several years ago asserted he und the key to the puzzle, others re- | to accept his claim. : Tractor Car Line Two Blocks Long Operates on a One-Cent Fare two blocks long and running on a ent fare, a tractor-trailer system in Specimen of the Yama, a New Vegetable Produced by stern city, in spite of its shortness, rossing Squash with Bantam Corn idered extremely important, for it ntributed largely to tire success of a Cross between Corn and Squash cipal market located on a side street Gives Grower New Vegetable : from the surface lines. Customers , ted to the walk to the cars with their By crossing yellow bantam corn and ; packages so the tractor outfit was hubbard squash, a Wyoming planter has + ed to solve the difficulty. Thetrailer, developed a new vegetable called the after the pattern of the old-style “yama.” About the size of a grapefruit, trolley cars with long cross seats and __ the product is green in color, with stripes nning board on each side, accommo- ofan orange hue. The yama is said to be twenty-four persons at a time, with easily prepared into a number of palatable . -hanging facilities for rush-hour traf- dishes. The first crop of the plants to be D, Curtains are provided for protection gathered consisted of 150 dozen, which tormy weather. The car is run back were purchased by a railroad for free dis a forth as a shuttle without turning tribution in its dining service. The vege 3 nd and the line carries between 1,700 __table’s ability to thrive in ordinary soils 1 ’ 2.000 passengers daily. expected to make it widely cultivated Id lea 11n , 1 ti ee Talat ir ei IO ag f lit For Only a Penny, om ~ Ride on This Tractor-Trailer Line from Surface-Car Terminal to Municipal arket, Saving a Two-Block Walk with Heavy Bundles

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$10 POPULAR MECHANICS

ore ct meen gg ati ct erage a Se

departments except t of medicine and dentist 12,000 students. It cost of $10,000,000. Si, teen high-speed elevat will be installed. tower will form a nuc! us for future unive: buildings, and its de and location so selected that it harmonize with rounding structures. Gas-Electric Bus Saves Fuel tric busses have been o: dered for use in Phi delphia. They wil! electrically driven by celeration and all spee changes are obtain« solely by variation of t engine throttle whic! controlled by the usu accelerator pedal. Ast

the generator volta; rises, and the bus spe is directly controlled the foot pressure of

Architect’s Sketch of Proposed Skyscraper, Which Is to House All But Two of .he Departments of the University of Pittsburgh University’s Cathedral of Learning to Be Fifty-T wo Stories High Skyscraper construction, for many vears considered the most suitable solu- tion of housing offices and stores in con- gested districts, has been chosen for edu- cational purposes in a 52-story structure for the University of Pittsburgh, to be erected this year. Saving of land space and reduction of upkeep costs were im- portant factors in deciding on this type of building, and its impressive height and Gothic lines are to symbolize the dignity and unity of learning andthe achievements of modern progress. The skyscraper schoolhouse, called a “cathedral of learn- ing,” will be 680 feet high, 360 feet long and 260 feet wide. It will house practi- operator, who need remove his hands fr: the steering wheel exc: to apply the emerge: brake. No electrical controller is requir for the motors, nor are any electrical ; justments made by the driver when ru ning the bus. A small switch is provid having an off position and reverse backing. Some of the advantages of 1 electric drive are said to be somew! lower fuel consumption and a higher 1 of acceleration and schedule speeds. W gas-electric transmission it is imipossi! for the driver to race the engine, and it also difficult for him to stall it. The el tric drive is silent in operation and customary jerks and noise of chang! gears at starting are entirely absent. @ More than 300,000,000 pairs of sh were manufactured in the United Stat in 1923. cally all the university's and will accommodate be made of white lime- stone at an estimated } have bee: Two hundred gas-elec- generator and two direct- connected motors. <Ac- e engine speed increases

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IS POPULAR MECHANICS 111 "og-Shaped Bath Chamber Aids Light Treatment of Disease reating patients with different kinds ht is said to be aided at a Berlin hos- by a huge metal chamber shaped an egg, in which the in stands while tak- the “bath.” Entrance uned through a ed curving door on side and there are s at each end of the artment for project- the rays. The inte- s finished in brightly hed aluminum so t the light is repeated- reflected with scarcely loss. The only open- are through a venti- at the top and slits e bottom of the door. chief advantage ed for this arrange- t is that the healing trike all parts of the a benefit in treating a general disorder disease in a particular organ or spot e body. Rickets and tuberculosis are ng the diseases that have been allevi- with light treatments, and the effects e rays as projected within the egg- ped room are said to be akin to those ved at mountain or seaside resorts. ertain maladies, a combination of the ray baths and an inhaling cure has iny cases been found beneficial, ac- ling to physicians. Blind Workers Build Own Radio Sets from Charts with Raised Designs As an added occupation and pastime for blind workers having knowledge of elec- tricity or mechanics, they are being taught Soi How Radio Has Opened Up New Fields for the Blind; Sightless Mechanics onstructing a Set from Braille Chart to construct their own radio sets. Special charts and diagrams similar to blueprints are prepared with lettering and designs in the raised form of the Braille “language” to guide the touch of the fingers. The prints are made for one to five-tube sets, and the sightless mechanics have little dif- ficulty in putting the parts of the appara- tus together with neatness and accuracy. The work is said to be thoroughly enjoved by those blind patients who undertake the task and in a great many cases has resulted in the production of surprising ly well-constructed wire less sets. One-Piece Vessel Built by Electric Welding Electrically welded in to one piece, the first ves sel built by this method has been completed for an oil company for serv- ice as a tank steamer The boat is eighty feet long, has a beam of twen ty-six feet and the hull is twelve feet deep rhe tanks in the hold have a -ross Section of Chamber, Illustrating How Patient Is Exposed to Direct and all Reflected Rays Striking Curving Sides of Cabinet gailons. total capacity of 200,000

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OE — a uO A1ieD Aleyeg s1039yY YMA, U7x2eM}0eq sUTe[y jO SUIEIIND pe esedeg AlPPIMA 70 parsoduiog Aljes9uenH s1y si9heI[q 14 W I >A | ie a ee

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On Carry Safely Actors Which between Curtains of Flame Separated of Widely ym posed ie Players Are Generally C ne NOV When the Plot Requires a Fire Movies Prefer to Burn Down Their Own Houses and Forests Because Real Flames Lack Conviction When Filmed \\ TITH a thousand dollars’ worth of \ fire some place in the United States minute, day and night throughout ear, destroying a dwelling every minutes, a barn every seven; one ital, five schoolhouses, five church- nd fifteen hotels each day, it seems ought to be enough flames to fy every one. ms so, and is so are different, ver, and out where the movie s, critical directors are busy im- ng on nature by staging their own nally conducted fires for the films. t that every film fire is a flimflam— isionally a breaks out is spectacu- -nough to fy even a di- and then be und on the job with his entire outfit. h a one broke out in the Lake Tahoe untry last summer and swept a path six les wide and twelve miles long through the national forest in the Sierra country. \ hastily mobilized force of 700 men, un- der Chief Ranger George W. Sallee, were fighting the flames, when a movie pro- ducer offered to bring thirty-eight of his actors and extras to help, in return for Staging Movie Thrills on the Fringe of Burning Forest Area in California; Insert, Filming Raging Brush Fire in Arizona Foothills “shooting.” The of- fer was accepted and some thrilling fire scenes were filmed two days’ As a general thing, though, even a fire such as this, which destroyed 120,000,000 feet of standing timber, is not as good for movie purposes as a perso! ally staged blaze with a few miniature papier-mache trees and other “props,” plenty of studio flares and lights, and a few cans of gasoline and oil That sort of fire can be “taught” to act just the way the director wants it to, which the real thing does not. Just when a cameraman gets a good set, with a pall of smoke a mile away for background, the wind will shift, flocks of burning brands will drop around the camera, setting fire to the “set,” or the smoke cloud will blow down and obscure the light, sending a coughing, choking bunch of

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$14 POPULAR MECHANICS scrambling for safety. A great forest fire emits alternate clouds of blue and black smoke and gases form in the air, spread- ing a pale green color over all. The dense smoke and gas obscure the sun and ren- der the pictures indistinct. In contrast to this, the studio “forest fire,” arranged in a corner of the lot can be perfectly stage-managed. In one re- cent film a raging fire» was portrayed, which threatened to wipe out about ten towns, a logging railroad, reduce camps to ashes and cause the lumberjacks to flee. Here's the way it was done. Sanitary Table Is Attached to Bed for Sick in Home or Hospital Easily clamped to almost any style of cot or bed, a sanitary table manufactured Table Clamped to Bed Frame and Adjusted to Proper Height for Sitting Posture by a mid-western firm is found a conven- ience in home or hospital. It is wide and long enough to accommodate a good-sized meal tray, can be quickly and thoroughly cleaned and also gives service as a writing or reading desk. It can be adjusted to va- rious heights by thumbscrews. Deepest Wells Dug for Oil or Water Shallow Compared to Holes in Sea Oil wells more than 7,000 feet deep are not uncommon and seekers for water have been known to bore down as far as 4,000 feet. \Vhat is said to be the world’s deep I] near Gobelins in France, where est well is operations were started in 1892 and a pmnrnvorwyT 4D ATO OC rmra tT Tao Along a little spur track some brus] piled, some lights planted, some kerose: and gasoline caretully distributed through the resulting flames a little ging engine puttered back and forth. |; emerged with all parts intact, hardly « smoke-begrimed, but when the “rus! were developed and viewed in the pri tion room that night, the film gave the lusion of a roaring mountain blaze. Most fire scenes in which buildings ar destroyed, are also carefully staged, ficially started affairs, though the flames and the destruction are real enough. depth of over 10,000 feet had been reached by 1914. Compared to the abysses d covered in the ocean, these man-made holes are shallow. Depths of about miles have been discovered in the Pac ocean with the aid of modern apparatu Glasses Developed for Color-Blind to Correct Defect in Vision Color-blind persons may be able to dii ferentiate various shades as accurately others, if special glasses now being vised by opticians prove successful. 1 lenses in the spectacles are to be coloré and will seek to adjust the eyes to recor properly the varying wave lengths of light Inability to perform this function is said to be the chief cause of color-blindness Voltage Tester Used without Lamps Indicates Different Currents Capable of measuring up to 550 volts, tester that indicates whether the current is direct or alternating has been place on the market. It consists of a mag- net coil within a strong rubber housing and oper- ates a_ plunger against the ten- sion of a spiral spring. Readings are shown on a plainly marked scale. To facili- tate reaching the circuit, long lead wires covered with fiber-insulated handles with pointed hooks are provided. No lamps are needed in making tests with this apparatus.

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ps ks in POPULAR MECHANICS 415 SEWING STARS WHOLESALE ON U. S. BATTLE FLAGS : Share —— 0. At the birthplace of Old Glory, in Philadelphia, here Betsy Ross pains- takingly sewed the stripes nd stitched on the thir- een stars of the first \merican flag, the quar- termaster’s department of the army now turns out ill the banners of the army by machinery. A ingle machine embroid- ers hundreds of stars on t fine silk flags in less time than the revolutionary Operator Moving Pantograph over Star Design to Guide Hundreds of Needles heroine required to sew on one of her cut-out emblems. The em- broidering is done by a Swiss machine, with a pantograph arrangement by which the single operator traces an arm over the enlarged master design, guiding hundreds of needles stitching away on five flags at a time. The machine makes the stars in rows of eight, or forty at a time, on the five flags. Besides the national flags, the factory turns out many types of banners. Electricity as Modern Farm Hand Cures Hay and Keeps Bees Busy In the heart of Sussex, England, land of slow-moving countrymen and woods untouched since the days of the Romans, there is a 600-acre farm that is said to be the most highly developed electrically of any on earth. All cultivating and reaping Stitching Five Flags are done by electricity, hay is cured with- out sunshine by forcing drafts of air through the mows with electric fans, milk- ing machines and churns are motor- driven, brooders for baby chicks are heat- ed by electricity and the hens are induced normal during the winter months by hav- ing lights in the laying pens at night. Even the working hours of the bees are prolonged and the colonies swarm earlier in the spring by putting them in electric- lighted and heated houses. It is estimated that the use of electric light and power on this farm saves forty minutes of working time a day for every man employed there, and that one kilowatt-hour of current, at a cost of twenty cents, does work that would cost about $3.41 with hand labor, seventy-three cents with horse power and over forty-eight cents with motor power.

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416 POPULAR Portable Electric-Lighting Plant Operates Automatically Weighing only about 125 pounds, a com- pact electric-lighting plant for the home or farm has been placed on the market. It consists of a single-cylin- der air - cooled gasoline en- gine, geared di ( rectly to the generator and g™ so arranged , Carrying Generator and Motor of Home Electric Plant Illustrates Its Compactness that when the batteries run down to a cer- tain point, the motor automatically starts until it is stopped by a full charge. The smaller model, with storage battery, has a capacity of twenty thirty-two-volt, twenty- watt lamps on the generator alone, or forty lamps on combined generator and battery. A larger size gives current for more lamps and, in addition, will operate the washing machine, electric toaster, iron and other appliances. The entire equip- ment is simply constructed, without valves to grind, carburetor or push rods to ad- just, and consumes but little fuel. A home or tarmhouse, barns and outbuildings can be lighted at less expense with this outfit than is possible at power and light rates In many cities, it is claimed. Its portable feature makes it convenient for use In summer cottages and camps, as well as in motorboats. Use of Raw Coal Is Called a Crime Because of Wasted Energy Use of raw coal for fuel with the at- tendant loss of the valuable by-products it contains has been called nothing short of a crime by English authorities who point out the fast decreasing supplies and the relative superior efficiency of oil. This situation is held particularly applicable to Great Britain, which has no natural pe- 11S POPT TAR MECHANICS troleum resources and only about 1,000,000 horsepower that can be developed f: inland waters. In 1923, that country ported more than $200,000,000 worth oi and mined some 260,000,000 tons of coal] which 155,000,000 tons were burned as 1 fuel. It is estimated that one ton of c will produce three gallons of motor fu eighteen gallons of crude oil, two gallo: of lubricating oil, thirty pounds of su phate of ammonia and a _ consideral quantity of smokeless fuel as residue. On this basis, it is declared, the output of ra coal there, would produce more than twic: the amount of motor fuel now consumed besides large quantities of other valuable materials if it were refined instead of be ing burned in the present wasteful man ner. Central electric generating plant where power can be produced at relati small cost, are also regarded as a possible solution of the fuel problem and the smoke evil in cities. Auto Exhaust Gas Is Used to Help Keep the Engine Cool Waste exhaust gas of automobile engines is being utilized to keep cooling water in circulation by a device that has no movin; parts. It is easily attached to the motor t prevent overheating. Connected to the manifold, a pipe conducts the gas under to the intake water pip: pressure Auto Engine Equipped with Device Which Utilizes Ex- haust to Force Water through Cooling System where it forces the liquid to the engine. After it has once been installed, it re- quires no attention of any kind. VUERCTRUAN Too

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POPULAR MECHANICS 417 Dirt Cause of Metal ‘‘Fatigue”’ Voice Is Recorded in Talking Movies Is Expert’s Claim by Modern ‘‘Aladdin’s Lamp” Ordinary dirt, and not crystallization Motion pictures will deserve some other ises the “fatigue” which results in the _ title than the “silent drama” and the whole eakdown of metals, ac- ding to an expert who just completed stud- wien he claims, ex- e the commonly held oon of change in the rangement of the crys- which compose the etal. The dirt-he i mes is the minute im- ities which survive smelting process and d their way into the ructure of the metal. j \s metals are naturally stalline in structure, s evident that break- e in service is not due crystallization,” says s authority. “The etal is a crystalline ss from the time it is t melted and poured. Vhen it solidifies after elting and pouring, it sumes the crystalline haracter, the same as iter solidifies to snow, rost or ice crystals. Re- earches in metallurgy a Section of a Talking Movie Film with Actors’ Voices Recorded in the Tiny how that when a motor- Scratches Visible at Left car part fails in service, he principal cause is not mysterious at system of film and scenario technique ll It is usually just plain dirt. It 1S im -teb-my bably will hav e to be changed ; a re purity so microscopically fine that without sult of a process which records the huma the most conscientious examination it de- voice, music and other sounds w ith the fies detection.” picture and then re produc es them as the aoe | film is unwound. This almost miraculou ; . achievement has been made possible by a Detachable Heels Are Easily Fitted = odern “Aladdin's Lamp.” a moving-pic and Reduce Repair Bills ture camera which causes the variations it sound to be registered } | il “ Detachable shoe heels that can be tremely small slit upon the film in sucl changed from right to left to correct un- way that thev are “plaved” back whén the even wear have } operator turns the reel. Pictures are been placed on taken in the usual wav. but the camera the market, so by means of a microphone and a radio that the wearer \ tube, picks up the sounds, causing them can have greater \ to affect the light that passes through the comfort in walk- slit less than one six-hundredth of an inch ing and need not wide, and thus obtaining a record of ces visit a repair shop / and music just as a picture of ty scene to make thealtera- J is being taken. The sounds and views are tions. The heels J synchronized when the film is shown are easily fitted a> and are securely « Whenever you find that vou wish to held by pegs one of which, on the side of oO more about anv article 1 the m iga- the upper part of the heel, acts as a lock. zine, write our Bureau of Information.

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118 POPULAR Regardless of Rank, Army Officers Assume the Duties of Pupils When They Attend Uncle Sam’s School Camp Vail, N. J., for Practice in Receiving and Transmitting Code by Radio MECHANICS at Training the Eyes and Ears of the Army Uncle Sam’s Unique School Also Teaches Students How to Make and Repair Airplanes g is the fortunate status of students at Uncle Sam’s big army air-service techni- cal school at Chanute field, Rantoul, IIL, where four and six months’ courses are given in the mechanics of airplane con- struction and repair, radio and photog- raphy. It is the only school of its kind in America. During the war, Chanute field was one of the aviation-instruction camps, but March, 1920, the school has been strictly a technical institution where pu- pils draw regular army pay while attend- ing classes. At the end of the six months’ course, the enlisted man may, if he de- sires, buy himself out of the remainder of his three vears’ enlistment by paying $120 to the government. On a strictly cash basis, he is six dollars ahead even at pri- vate’s pay, for during the period he has been drawing twenty-one dollars a month and has also received board, room, cloth- ing. medical attention and his instruction. The field occupies an entire section of land, or 640 acres. On the “campus” are eighteen large buildings devoted wholly E wede NG a salary for going to school since to school purposes. officers There are about fort civilian instructors on. the teaching force, and approximately 600 me: are graduated each year. The equipment is valued at more than $3,000,000. Whil some advanced courses are given, the school is planned primarily for the ma: who has not had extensive academic train ing. Two years’ high-school work is a maximum requirement. Many classes de mand not more than one year. Practical experience as a machinist, a garage man or work in similar lines is considered as credit for admission. In the mechanical division, a man in six months makes all the wire loops used in airplane construction; he learns how to construct and install all the wvooden parts and metal fittings, how to cover a wing with the fabric, how to handle and use the numerous special tools, aline the ship, prepare it for flving and how to over- haul and test the motor. At the end of the course, according to the instructors, a student can thoroughly repair an air plane and put one together. The photography school embraces three and

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POPULAR MECHANICS 119 ~ 5° | Soldier Students in ; Photography Learn- ing Details of Mixing | Chemicals, Developing | Negatives and Printing, | in Laboratories at Cha- nute Field, While Me- rp chanics Practice As- ( sembling an Airplane ac A | vw 4 JIA 4 id 7 | Ws | Pe ee : vy “A ZF LY Z& yz Loa Putting Fabric on Air- plane Wings Is _ an Important Detail in Repair Courses

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$20 POPULAR MECHANICS Engine-Starting Practice with Wingless Planes; Three Mechan- ics Lock Hands, “Contact,” Yells the Pilot from His Seat, the Starters Give a Mighty Pull, the Blade Leaps and the enles i ous yj / Y | Repairing a_ Fifteen-Watt Radio Transmitter Designed by an Army Officer and That Has Flashed Mes- sages across the Atlantic; Mending Sets Is Part of School Work Sa At Uncle Sam's Army Air Service Schools, Where Airplanes and Radio Sets Are Textbooks and the Hours Are Filled with Action and Practical Instruction POPULAR MECHANICS co

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POPULAR MECHANICS 421 Inside the Hangar at Scott Field the Home of Dirigibles and Bal loons Used for Instruction and Fly- ing Practice during the Ten-Mont! Courses Given at the School; More than 800 Feet Long and 150 Feet Wide, the Floor of This Structure Would Accommodate an Army of 100,000 Men Standing in Close Formation. The Steel Doors, Built Separate from the Hangar and Run- ning on Steel Tracks, Are Opened and Closed with Electric Motors Eight Balloons and Six Blimps Are Kept Here at One Time. At the Left Is a Corner of the Army Radio-Transmitting Station at Camp Vail, New Jersey t—_—" *\) >) 6 » Ce ») 3 es ~~ 3 DADITT AD ALROCTANT CS {»)° ~~

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122 POPULAR main sections. One gives an advanced series of sixteen courses for army photo- graphic officers; while another is intended for reserve officers and men in the national guard and consists of fifteen subjects, and the third is for enlisted men. It is the simplest and includes fundamentals in the taking of ground and aerial pictures, de- veloping and printing, the use and mech- anism of cameras, and in copying and mo- saic work. The radio course embraces instruction in electricity and magnetism, in the fun- damentals of radio and in the construction, repair and maintenance of radio equip- ment. Practice at transmitting and re- ceiving wth the “buzzer” and studies of spark and crystal sets, electromagnetic currents and antennas, vacuum tubes, wireless telephony and telegraphy are given in the course. Supplementing these three main divi- sions are classes for armorers, auto me- chanics, blacksmiths, cabinetmakers, elec- tricians, draftsmen, gas-plant operators, metal workers and parachute riggers. In- ventions are encouraged. The camp al- ready is credited with an improved sus- pension for airplane cameras devised by a photography student. MECHANICS The diversions of a civilian school reflected in a big gymnasium, a swimmi pool, football and baseball teams that ré resent the post in games with organi: tions of near-by towns and schools. Te nis games, boxing and wrestling, baske: ball, bowling are also provided for, a: there are club and recreation rooms officers and men, and a post band. Although flying is not taught, planes a in the air daily during photographic a: mapping tests and while officers put in t! required number of hours in the air permit them to draw their flying pay. Occasionally an aerial demonstration given, such as was staged recently for t! benefit of army-relief work. Flyers fro: distant fields dropped in for an aftern of sport in the air. The deep roar of t bigger planes mingles with the musi whistle of the wind through the taut wir: of sprightly messenger and pursuit craft tumbling and spinning to the continuou crackle of mighty motors. Students to ride in stately bombing planes that so majestically over neighboring farms at villages, spelling in their high and gracefu flights the progress man has made modes of travel since the pioneers p! ded across the plains. Car and Ballast Bags of an Army Blimp inside Huge Hangar at Scott Field; Students Master All Controls before Making a Trip in the Air 124 POPULAR MECHANICS

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POPULAR MECHANICS 123 ~ Pe Big Army Bombing Plane on | Instruction Trip near Flying (= School; Several ‘“‘Rookies’ Can )* Y Ride with the Pilot in These Huge Craft, Getting Actual Ex- perience in the Duties of the Airman Installing and Removing Motors Are Regular Parts of Classroom Work at the Air-Service Technical School; Corner of Radio Shop Showing Phonograph That Plays Dot and Dash Record for Practice Receiving DWaDwagTy «At arTrweretwryreartyr a. = |

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124 POPULAR MECHANICS Safety Signal for Autos Rings Bell, Flashes Light and Counts Cars For the protection of autoists and pe- destrians at curves, side streets and other Tear-Gas Bath to Rout Stowaways Who Hide on Army Transports Stowaways who seek free rides o; United States army transports plying be When Autos Approach This Corner, “Look’’ Sign at Right Flashes and Bell Rings, Warning Pedestrians and Drivers langer points, a warning signal has been nvented that rings an alarm bell, flashes a red light and at the same time regis- ters the car on an automatic counter. Pas- sage of the automobile over a metal plate set in the street, completes an electric circuit which causes the lamp to flash and the bell to ring. Current can ‘be supplied from the lighting system in towns and cit- ies provided with electricity at a small cost. The double warning of the red light and the bell notifies of an approaching car in ample time to give the other driver op- portunity to slow down or stop, as the tread is placed some distance from the signal post. Counting the cars enables engineers to study traffic conditions and frequency of use of the streets, and saves the expense of hiring special checkers for the work. Once installed, the apparatus requires practically no attention. It has been in operation for some time in Ashe- ville, N. C., where it is reported to be the most efficient device of its kind that has vet been found. @iIt takes a block of wood, two inches high, three inches wide and four inches long, to supply the pulp in a twenty-four- page newspaper. A cord of wood, it is estimated, informs 3,600 persons of the day’s news. iO POPITITT aR tween San Francisco and Manila, will prol ably have to carr masks if they expect to succeed in the future, for officials of thy chemical-warfare ser\ ice propose to flood al! possible hiding places i: the ships with stream of tear gas for at least twenty-four hours be fore each sailing. The gas is not fatal but is so irritating that no huma: being can long remai: exposed to it. Police in many cities already have used it to drive criminals from their places of refuge. Prior to the sailing, the trans port’s hatches will be closed and the gas forced into the hold On a recent trip of the transport “Thomas,” twenty-five stowa ways were discovered and put ashore just before the ship left Manila bay. Twenty- three more popped out of their hiding places before the boat reached China, and as they could not legally be put ashore in China or Japan, the transport was com pelled to carry them to the United States. Stowaways usually try to keep hidden for a day or two, and when found, generally are set to some light task. po Button Lock on Inside Door Knob Eliminates Key and Adds Safety Inside door locks, secured by simply pressing a small button and released by turning the knob, have been placed on the market. They eliminate keys, spindle and es- cutcheon plates and are said to be easily put in, since only two ;, holes in the door ower + and four screws — are necessary to hold them in place. The button is built into the knob and requires no separate adjustment. Ab- WIECH ANTCS

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POPULAR MECHANICS $25 e of an outside kevhole minimizes the rtunities for tampering. the appear- of the door is not marred by screws e knob and the simple construction the attachment reduces installation Similar locks are made with an ide opening for a key. uilding Erected in Wooden Shell to Protect Workers from Cold inter weather with sub-zero tempera- . failed to stop building operations on tel being erected near Lake Louise, ada, for the summer-tourist trade. As t as the structure progressed, a windand 1-proof wooden shell was constructed rely around and over the building per, enabling the 350 workmen to go d with their toil and preventing mate- from freezing. To carry the 21,000 of steel used in the hotel, a narrow- ige railroad, three and one-half miles with a four and one-half per cent de, was laid from the main line. Model Galley as Realty Office Aids Sale of Land Real-estate agents in an eastern city e constructed their office on a sub- ision near the sea in imitation of a gal- to help advertise the sale of the land. pirate’s figure of heroic size, close by, Copyright, Keystone View Co. Real-Estate Office “‘Camoufiaged” as Pirate Ship to Arouse Curiosity and Attract Customers ilso symbolizes the days of buried treas- ure and adventure. The roof of the office is Completely concealed by the high ides of the ship and the entrance is partly hidden by the large portholes and panels. lhe masts furnish convenient vantage points for flags bearing the name of the tract. At night, the signs are illuminated. Logging Group Carved from Wood Is True to Life in Detail Remarkable for its beauty and detail, a logging group sculptured trom wood has Curator of Portland Museum Holding Unusual Logging Group That Was Carved from Wood been presented to the Portland, Oreg., mu- seum by the man who made it. The carv- ing, true to life and deftly molded, shows two spirited horses, completely harnessed, drawing a wagon bed on which there are three logs, held by chains. A driver's seat is perched on top of two of the logs in the rear, and reins extend to it. Eclipses Show Days Are Lengthening from Friction of Shallow Seas On the basis of what they have ob- served from eclipses, scientists declare that the days of 1925, are about one-tenth of a second longer than the days of 10,000 years ago, and that by the year 11925 still another tenth of a second will be added to the span which we now measure as ex- actly twenty-four hours. The explana tion, those who have studied the problem helieve, lies in the friction of the tides in shallow bodies of water, which slows up the earth's daily revolution. Since the war, scientists have actually measured this friction in various places and announce that the amount is sufficient to produce the retarding action. @ Nearly half of Brazil is said to be cov ered by forests, little of which is known.

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126 POPULAR Electric Presser for Trousers Displaces Bed Springs A substitute for the old-fashioned method of pressing trousers between the bed springs and mattress is on the market in the form of an electric pressing board which does the So we”

Trousers in Pressing Board with Electric Cord At- tached, an Arrangement That Eliminates Irons work in a few niinutes. The trousers are placed between the boards at night, the clamps closed, and the extension cord from the heating element is plugged in on the nearest lighting socket. After the heat has done its work, the trousers can be left clamped in place until needed in the morning. Bank’s Clock Imbedded in Sidewalk Has Crystal Two Inches Thick Pedestrians hurrying past a_ certain bank in San Francisco have but to glance MECHANICS down at their feet to learn the right time. Imbedded in the sidewalk is a large clock protected by two layers of plate g! each an inch thick, and kept constant} accurate by a master clock inside bank. The outer glass is renewed ever thirty days. The inventor has obtaine patent on the clock, and devised it for cial use in cities that forbid installatio: overhanging timepieces. Electric lig are set in the rim so that the dial can be illuminated at night. Radio Noises Not Caused by Static Traced with Loop Receiver While rightfully blamed many of the noises heard from the ra receiver, power lines, violet-ray machin elevator motors, electric heating pad doorbells, gas-engine plants, telephon bell ringers, street arc lights, trolleys motors frequently are sources of troubk and not the set. Imperfections in the rt ceiver may be detected by connecting antenna and ground terminals with a wire When this is done, no signals or nois intercepted by the antenna can reach t set; so, if howls and whistles are hear they must originate in the apparatus itsel The problem of locating an outside sour of interference is a difficult one, but it c be done, as reports of a government radi: supervisor in a southern city show. Broadcast reception had been rendered almost impossible by roaring that, in some sets, could be heard a distance of two cit blocks. Preliminary investigations wit! static is

=z an ordinary loop receiver

showed that the trouble was due to a 13,000-volt transmission line feeding back into the street light ing circuit, an old ar: system in which tungsten lamps had been substi tuted. But there was particular leakage some where which caused most of the noise. \ special three-circuit re- ceiver, employing a de tector and one audio-frequency amplifi cation, was constructed to hunt for the offending interference: It was lined with tin on all sides of the cabinet and all : telephone and batter - leads were shielded to

stage ryreaéa*'t* Tne ce

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le, ric POPULAR MECHANICS 427 ch the loop mounted on top of the ver. The government inspector andan | of the local power company toured city for two nights carrying the set in utomobile and making tests at different lences. The trans- ers in the particu- transmission line under suspicion, the loop had to be ted toward the lle of the street, re a light was sus- led, to keep the e at its loudest. inspector got out e automobile and ile his companion ened at the set, he ped the light. The terference fell to lv zero and then tO maximum in- Dry-Land Swimming Rack Teaches Right Strokes in Two Lessons With the aid of a machine invented in England, beginners are said to be able to But the trouble Swimming Pupil on Instruction Rack, While Teacher Turns Crank Moving not lie in the light '. It originated in a guy wire to the post lying across the primary of a 00-volt circuit. When it was removed, interference was eliminated. \djustable Lens for Hand Cameras Gives Many Focal Lengths Screwed into the front of the regular hutter, an adjustable lens for hand cam- ras, that gives a great number of focal ngths, has been placed on the market. is used in place of the original lens, “ee Folding Camera Fitted with Adjustable Lens That Gives Wide Variety of Focal Lengths and when the bellows are at normal ex- tension, an image of nearly double the usual size is produced, it is said. On long- bellows cameras, adjustment of a knurled collar on the front of the attachment, gives images of various size in “telephoto effect” up to the limit of the lens. Arms and Legs of Subject in Proper Strokes learn the right swimming strokes in two lessons. The pupil lies prone on a cushion and his hands and feet are strapped to special pads. When the instructor turns a crank, the student’s extremities are auto- matically made to perform the correct swimming motions as the rests to which they are attached are moved in the proper order by a chain-gear arrangement. Cab Driver Quicker in Use of Brains than College Students That chauffeurs of taxicabs think faster than college students in meeting emer- gencies while driving automobiles has been indicated in tests described by Dr. E. A. Moss at a meeting of the National Civil Service reform league. Women scholars in like situations established the next quickest record for rapid mental work. In the experiments two revolvers were fastened under the running boards of the car used to try the skill of the sub- jects. While the machine traveled at high speed, an examiner 3'ding within fired one of the pistols by pulling a wire, and the other was set off automatically as the driver applied the brakes. The time elaps- ing between the two shots indicated the mental agility of the operator. The aver- age time between ‘the two explosions for competing cabmen was .413 of a second, and that for women subjects .459 of a sec ond, while male students set .590 of a sec- ond as their average.

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128 POPULAR MECHANICS Artist’s View of the Service Chambers beneath the Huge Gun Turret of a Modern Battleship from Where Endless-Belt Conveyors Carry Tons of Ammunition to the Loading Platforms

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POPULAR MECHANICS 429

eady with the Shell; Great Steel-Nosed Projectile Passing into Breech of Large Naval Gun Propelled by

Automatic Electric Ram Which Handles the Load with Ease Behind the Big Guns of the Navy How Unseen Crews in Turrets of Combat Ships Aim and Fire Giant Rifles By G. K. SPENCER FuIRE .fire...fire...fire...fire...” So vent the steady drone of a human ce which reached the gunners of num- r three turret, aft battery, U. S. S. “Cal- nia,’ through a brass tube which ened into the solid little firing room of e first of the three guns in the turret. he voice came as though from a great stance. Simultaneously an electric bell unded, confirming the voice signal. A ot did not go forth with each word tire,” but it did signify that, each time the ord was heard and the bell rang, the <uns were “on the target” and that a shell, t let loose at that moment, would go true to the target. Stripped to the waist under the electric ight, the gun crew, with scarce six inches n which to turn their bodies. flung levers. ressed buttons and keenly inspected the uns bore aiter each shell had left the turret. Curiously enough, no shock was felt inside the steel fort as the successive explosions rocked the ship from stem to stern. The decks outside were cleared and not a soul appeared on them. Cow- ering in protected spots, the deck force held their ears and awaited the firing. Within the turret, scarce a ripple oc- curred. We knew a shell had left the muzzle by the undulating motion of the ship as the explosion outside threw the vessel sharply to starboard. The guns were firing to port, assuming the target were an enemy which had engaged on the port beam—-which means directly off the side of the ship, and neither forward nor aft. With the command “commence fir ing.” a seaman pulled a lever and an ele vator from forty feet below shot up and deposited a bag of powder at the side ot the gun breech. A 1,400-pound shell fol

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130 POPU LAR lowed from thirty feet below, in a tubular hoist, and deposited itself in a trough leading to the gun breech. An electric rammer, operated by a seaman with a lever in his hand, rammed in the shell and with- drew; the powder, rolling into the trough behind the shell from its little elevator, was rammed into the breech; the breech also vas closed and at one of the com- manding words to “fire,” the shell was ejected. Speed is the essence of the op- eration, a ship which can get out two shots in three seconds from three guns, being rated higher than a ship which gets out ten shots in twenty seconds, even though all may be hits. The navy’s word is, “It's not the number of hits vou get in an hour that counts, but the number vou land in a minute.” Keach turret of the “California” is com- four decks. On the first three gun breeches are seen. To gain en- trance, the crew crawl up through an air- tight door under the moving top portion, and wriggle in, thereafter shutting the hatch tightly behind them. Once inside, one is impressed by the amount of ma- chinery. This mechanism performs almost automatically. levers, buttons, signals, duplicate signals, precautionary lling implements designed to posed of deck Brass, devices, han Heavy Armor-Steel Turret of the U. S. Warship “‘Mississippi,”” Which Withstood Force of Terrific Powde: : of Many of Gun Crew Serving the Rifles Explosion That Claimed Lives POPULAR MECHANICS MECHANICS operate with a leverage of only a few fee represent the solution of thousan engineering problems. On the first deck, also, is a sighti: paratus. The range-finding device stationed atop the turrets, in the and might be easily shot away. are duplicated, however, in the fig tops, points, and are all connected by tele and speaking tubes to the so that no matter if two, range finders are shot away, the “plott always have enough operating to get ranges. Of ting planes is also utilized. On the second deck, is the mec] by which the turrets are moved arou and the guns elevated and lowered. the third deck, is the she ter of the room is stationary, but sides of the turret, filled solid projectiles on shelves, movearou On the fourth deck, the powder cl jut out from Magazines 01 sides. A crew rying the great powder bags to the « vators. Painted warnings on all s instruct how to flood the magazine case of danger. These men, in the « ; | ie, almost never escape. on the bridge and at various plotting 1 three o1 course, radio trom the I] roomn.. Che ex With shell secured ot men are here seen Ot Catastrop ‘ , ’ ' 1& Underw

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POPULAR MECHANICS 431 To Keep the Piece Trained on Its Target at All Times during Action | Is the Duty of These Alert \ “Trainers” } = — Naval Officers a Inspecting New Rifles under = Preparation for Telltale Firing Tests before Installation Powder Room on Bottom Deck of Tur- ret; Orders Are Received through the Loud peaker from Gunners | A , a“

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132 POPULAR MECHANICS | Stages in Construction of Short-Timbered Silo from Foundation and Scaffold to Erection of the Tall Uprights and Addition of Tongue-and-Grooved Crosspieces That Form the Wall Electric Submarine Like Monoplane Proposed for Use in War Shaped like a monoplane with its wings pointing downward instead of up, a model of a proposed electric submarine for use in bombing and torpedoing has been ex- hibited. While wheels on the bottom are provided to permit cruising about the ocean’s floor, the craft will be lighter than water so that it would rise to the surface in case of mishap to the motor. The op- erator will be furnished oxygen supply tanks and vision is to be through a peri- scope, according to the plans of the de- signer. Submerging will be accomplished by increasing the speed and operating the rudder. Over the cockpit, a dome-shaped protector is to be provided, with hatch Model of Proposed Electric Pilot Protector and Downward-Pointing Wings Submarine Fitted with and side lights. Whilean actual submarine of this type has not been constructed, the model is said to have indicated that such a machine is not impracticable and might be used to good advantage in attacks on fleets. Silo Can Be Built in Twelve Hours from Short Pieces of Timber A farm silo that can be built from short boards that might otherwise go to waste and can be completed in twelve hou after the foundation has been laid, ha been designed by a western man. [ rights used are lengths of “four-by-fours’ grooved on two sides and the side wall are constructed from grooved and tongue flooring strips, two feet long, six inche wide and two inches thick. The object of utilizing the short pieces is to simplily the task of building, and in case a sec tion rots, it can easily be replaced. A num ber of these silos have been constructed and are giving good service in the sout! the designer reports, and one was put uy in less than a day and a half, most of the work being done by boys from a near by. school Tar-Coated Paper Water Pipe Used as Substitute for Metal Water pipe made of paper has been in- vented by a Frenchman and is being man- ufactured in a machine that winds it directly from a tank containing adhesive material with which the paper is coated. The final layers are covered with tar and a finishing coat of bitumen is given before the pipe is laid. Sections are joined by winding a special kind of fabric over the bell-shaped end of one length and that of the next, which fits into it. anem ep 2 oe @ 2a ae

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POPULAR MECHANICS 433 Pioneers to Be Carried by Airplanes to Settle Canadian Wilds th radio communication already suc- ully established between settfements the Peace and Mackenzie river valleys northwestern Canada, it is now pro- ed to establish airplane transporta- into the region for the benefit of new | seekers venturing into the territory. government, it is reported, is to ch the scheme this summer. If the ns are carried out, “schooners of the *’ as modern versions of the covered sons which carried earlier settlers ross the western plains, will soar over ‘deep woods and rough mountains of : province, speeding their passengers to iote destinations in a fraction of the e it would take to go by pack trains. Racer Auto with Front-Wheel Drive Built for Speedway Tests Driven as well as steered by the front eels, a racing automobile has been con- ructed by a western sportsman for speed- iy tests against cars of the usual type. he differential is inclosed in front, just low the radiator, and the driving shafts ehind the large suspension rod between e wheels. The steering rods are below. Front - Wheel Drive Racer with Motor below the Radiator Designers of automobiles are especially in- terested in the speed developed by the racer, how successfully it can be guided and the performance of the brakes. Cabinet for Removing Excess Hair Is Intended to Destroy Roots Among the latest inventions for beauty parlors, shown at a hairdressers’ exhibi- tion in New York city, was a cabinet arrangement for removing superfluous hair me How a Patient Takes Cabinet Treatment for Removal of Superfluous Hair from the Face by treating the roots to destroy the tissues that supply them nourishment. The sub- ject taking the treatment is said to suffer no ill effects, and is not exposed to the danger of infection or disfigurement. The apparatus is controlled with a system of dials and has an extension drum against which the face of the patient is rested dur- ing an application. Coal Mining under Ice Fields of Arctic Goes on Year Round In spite of the long winter night of the Arctic, coal fields lving beneath thick lay- ers of ice, snow and rock in Spitzbergen, are worked throughout the entire year. ‘The first deposits of the fuel found in that country were discovered in 1900 under forty feet of ice and about twenty feet of solid rock. Demands for the mineral during the World War led to exten- sive operations. A vol- ume of coal reaching 90,000 tons was exported in 1919, and the annual production increased so rapidly that more than 335,000 tons were mined in the past year. All of it is shipped to Norway, although companies of many nationalities do the mining

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POPULAR MECHANICS Courte y Whaling Film ¢ With Blazing ‘‘Try Works’ at Which Busy Crews Rendered Oil from a Day’s Harvest of Blubber, Old-Ti: halers Filled Night Seas with Weird and Lurid Glows Whale Hunting Far South Today Floating Factories and Swift Steam-Driven Craft Pursue Blubber- Bearing Quarry Now Retreating to Remote Seas By HAROLD ‘THE romance of the seven seas hangs the old-time hunters, whose daring and endurance made American seamanship famous in every part of the globe. “A dead whale or a stove boat,” says the inscription on the striking whaleman statue in the grounds of the public library of New Bed- ford, Mass. The safety of the crew then often depended on the alertness of the man who stood ready to cut the harpoon line at the critical moment when the mad- dened whale was lashing the water with its terrible flukes. Today, however, whaling as an industry is true to the type found on the Aleutian Islands, Alaska, or at South Georgia and the lone, desolate islands, populated by elephant seals and penguins, which are like a halo over whale 422 DWANWITT a T. WILKINS scattered along the edge of the great A arctic circle of ice floes. The mod whaler is a steel-built, steam-driven vess« about 115 feet long, light in structure capable of high speed and rapid maneuve: ing on a specially rounded keel. Th: boats ride the water like corks and roll pitch in the slightest seaway. No longer is whaling a quest for w! bone, a ton of which, worth at one $10,000, has been found in the mout! the large right whale or bowhead. Bales or whalebone is made into highly artist toilet articles in Japan, but the market it elsewhere is now very small. A powerful harpoon gun is mounted « an iron support in the bow of the ship swiveled so that it can be turned up down and from side to side. Che | ZArTw~wmoere'i yyTatakhkrT Tse

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er- POPULAR MECHANICS ing Deadly Steel Lance at Struggling Mammoth ghting the Cruel Clutch of Deeply Buried Harpoon double shait, six feet long, and 1s with four twelve-inch flukes, de le from the shaft. The flukes spread lely on entering the whale’s body and revent the iron from drawing out. \ le point, called a bomb or bursting irge, filled with powder and ignited by me fuse, is fixed behind the harpoon dd The muzzle of the gun is ch irged h black powder, and the harpoon, well reased, is driven home upon wadding \ igger at the butt end of the gun is pressed ward, and three seconds afterward, the mb bursts killing the whale, perhaps at rst shot. A ring, sliding along the har- poon shafts, is connected with a five-inch ype, which, in turn is fastened to forty or fifty fathoms of a smaller line, called the “forerunner.” This is coiled on a heavy iron pan just under the gun, and

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436 gives slack to the harpoon as it flies through the air. From the pan, the rope passes over a roller in the bow to a double winch in front of the wheelhouse, and thence down into the hold, where at least a thousand fathoms is carried. By means of the winch, the whale is played as one would use a reel on a fishing rod in sal- mon streams. Imagine yourself on the deck of a steam whaler off South Georgia, a bleak and lonely island in the South At- lantic, where the whaling season is from November to the end of April. The day is gray and dull, with heavy clouds bank- ing the horizon, and a strong sou’wester blowing over a sea upon which the steamer rolls and pitches heavily. About 9:00 a.m., a shout comes from the lookout in the crow’s-nest on the foremast, “Whale on the starboard bow!” Far away on the horizon a white column of vapor shoots up into the air. The whale has come up to “blow,” and oxygenate its blood. Pink-stained patches of water de- note the presence of shrimps or “plank- ton,” the whale’s food. The animal turns over On its side, and closing its vast under jaw upon its upper, gulps down the shrimps, rejecting the water in a great shower streaming from the baleen plates of its head. ; The telegraph in the wheelhouse rings for half speed, and the round-bottomed steamer quietly creeps through the water toward the vast bulk of the whale, which the captain, scanning it through binocu- lars, declares to be a finback, sixty feet long. Suddenly, the quarry submerges, and then reappears twenty fathoms away, blowing with a whistling roar. The har- pooner sights his gun. There is a terrific report, a volume of dense smoke, and the lanced bomb belches from the mouth of the gun, trailing a rope, and buries itself in the back of the whale, which hurls its body and flukes out of the water, arches its back, and violently dives, nose down. Hissing from the winch, the hawser, which can stand a strain of twenty-eight tons, runs out over the ship’s bow, the steamer following in its wake. Again the captain rings, this time for half speed astern, and the whale, begin- ning to feel the pull of the ship, dives and reappears near the ship, blowing. An- other harpoon is fired, and the whale, lash- ing the surface, at last lies on the water nearly exhausted and spouting fountains of blood mingled with foam. Forty min- utes later, a small boat, called the “pram,” is launched, and three sailors row to the victim. Lance in hand, a man stands in the bow waiting an opportunity to give WNrrpPwryy ay POPULAR MECHANICS the beast its deathblow by thrusting the lance into its side. The whale sinks but comes up again, floating dead upon the sea. The carcass is hauled to the ship by the steam winch heaving on the harpoon line. To prevent the parting of the rope under the strain, a series of poweriu] springs is fitted in the bottom of the ship's hull. The securing tackle is led to the springs by way of blocks well up the mast, so that any sudden jerk or strain on the rope is taken up by them, preventing dis- location. Once alongside, the whale is made { by a chain passed over the flukes of great tail, and secured to the towing bitts. A hollow air tube is driven, harpoon fa ion, into the carcass, and through t tube it is inflated with air forced in b compressor in the ship’s engine roo: this, of course, to prevent it from sinki: Towing one or more whales, each over half its own length, the steam whaler r turns.to its base which is a shore stati lying in a bay or cove close to the sea. \ typical modern shore station, such as m be found in South Georgia, is a striki: collection of buildings. The flensing s! on which the dead whale is dragged first to have the skin and blubber removed, tracts the eye. Hard by are the carca platforms surrounded by boiling vats, machine for drying the flesh, the engi: house, wharf, offices and manager's hous: An all-pervading odor of steamed files! comes from the drier. All parts of t! carcass, even the blood of the large finn: whale, are used. Besides the shore stations, large stea ers, known as floating factories, ar equipped to deal with the whales broug! in by four or five steam killers, and th« return home with the whale oil at the en of the season. A forest of derricks, ele vators, chutes and machinery crowds thi decks of these factories. Here, the cat cass of the whale undergoes similar treat ment to that at the permanent shore sta tion. Revolving knives cut up the blub ber, which is shot by elevators up and down chutes into steaming vats where th: oil is extracted. This is then cleaned and refined and run into tanks. Thes ships can deal with six to nine blue whales which average eighty feet in length, o1 twenty finner whales in a day. It is stated that, in about four months of the whaling season of five to six months, a floating fac tory can produce 30,000 barrels of oil from 600 whales. The ships are cut off from the outside world for many months, and carry a com- plete engineering shop, and carpenters’ and AaArwmeenoryatTYyYrTreg

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POPULAR MECHANICS ASS : _— — ne —s = SF Cane — SSE ~u wy VY. \4 \e r 7 j , 7 ” Fate of a Seasoned Whaler Driven by a Relentless Gale on to a Rocky Coast Where Heavy Seas Pounded the essel to Pieces Before Aid Could Be Summoned

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-_ POPULAR MECHANICS ue — — S=S=== Steam - Driven Whaler of the Type Rapidly Re- slacing Sailing Craft : Be- ow, Giant Tail Flukes of a Huge Carcass Hanging over the Slip Where the Whale’s Body Is Cut Up; Insert, arpooning a Porpoise from the Bow- sprit of a Boat in North- ern Seas (© U. & U.)

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POPULAR MECHANICS 439 ksmiths’ establishments. Their crews sperm whale will deliberately turn on its =] 150 have to spend some six months in pursuers and sweep the water with devas- \ntarctie regions, and then undergo a__ tating blows of its huge flukes, smashing \ turn vovage across the equator home. the boats or crushing them between its y) ery available place on board ship is filled immensely powerful jaws. h coal, and distillers and evaporators In the narrow and rocky channel of provided to furnish water, the supply Cape Brett, New Zealand, the migrating hich is a very difficult problem at sta- humpback whales are trapned in wire nets, s such as the South Orkneys and Shet- 600 feet long and 200 feet deep, hung on ds. strong cables and buoved on great floats. In these far-southern waters, the When a whale is sighted from the head- tish government has been forced to lands, steam launches set the nets, which strict the issue of licenses to establish are allowed to float loose, hampering the aling stations, and has compelled the whale by their entangling wires and mak- ating factories to use not only the blub- ing it an easy prey to the hunters. - but also the remainder of the carcass, It should be realized that whales are hich was formerly turned adrift. hunted in every sea of the globe. Modern whaling is not without its thrills Therefore the herds are thinning, vear d its pathos, however. Some years ago, by year, and the time is already in sight Norwegian steamship, off Tromso, had when they will become, if not extinct, so tened a rope to a humpback whale = shy and wary that it will not pay to hunt irty-five to fifty feetlong),whenitrushed them in the inaccessible ice floes to which 1 madly against the side of the boat and, they have retreated. Ruthless hunting has ashing through the hull into the engine all but killed the industry off Newfound- y/ room, let in a great flood of water. The land, and from the whaling “grounds” yy, es were extinguished and the ship sank in the neighborhood of Japan, where [ three minutes. The crew had barely whale meat, fresh and canned, is a staple 1e to launch a boat, and were rescued article of food, the humpback whale nother whaler some hours later. The soon have vanished. Un'oading a Treasure of Whale Oil from a “Floating Factory,” a Stout Craft Equipped with Every Need to Reduce the Captured Animais to Articles of Commercial Value

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440 Two Steering Wheels on Auto Help Beginners Learn to Drive Fitted with two steering wheels con- nected by a sprocket chain and with a double clutch arrangement, an instruction emcee Woman Pupil Learning to Drive Auto in Double-Steering-Wheel Instruction Car; Posts Are Connected by Sprocket Chain car used by a southern automobile dealer has been found of great aid in teaching beginners how to drive. Women, espe- cially, become more familiar with the mechanism of the auto and acquire skill in driving much more quickly when they can actually turn the car with the wheel. Danger of accidents is minimized by this method and the pupil has gained confi- dence before assuming control of the auto unaccompanied by a teacher. Airplane Taxis for Inter-City Service at Twenty Cents a Mile Plans for the manufacture of “aircabs” for an inter-city taxi service, to operate at a rate of about twenty cents a mile for each passenger and a schedule of 100 miles an hour, have been announced. The spon- sors expect to operate a demonstration fleet of nine planes in Chicago, in conjunc- tion with units of three in each of four other cities. The craft will be capable of making sixteen miles on a gallon of gaso- line, it is expected, and will be painted a color that has already been adopted by several taxicab lines. A former air-service aviator is at the head of the manufactur- ing company.

POPULAR MECHANICS Signal Corps Plans to Send Maps by Radio “Airplanes, radio and cameras will the next war.” This is the commo: prediction when possibilities further conflicts are ing discussed. Whet right or wrong a whether or not ther another war, the « ciency of the army’s nal corps is being gre increased by the devel ment of these three ventions. Now that p! tography has bee coupled with radio, nal officers are devel ing a system wher diagrams, sketches a1 entire maps can be s through the “commu cation net” of 100 ra stations now under t direction of the arn The army is also maki use of commercial dict phone apparatus in tea ing Morse and radio c work. Hard rubber r ords, practically ind structible, are used for receiving practi the students taking the sounds down the record is “played” through a set of 1 lays. For sending, the students emp! soft-wax cylinders and gain practice in r running and copying them. heard

Memo Clip on Telephone Saves Time and Keeps Notes Safe A metal spring clip which can be quic! ly snapped on or off a telephone withou' the aid of any tool is designed to preven! the loss of me sages and mem: randums. Not: and letters may | inserted in the cd: vice, which hold them in a positi: to easily attra< the notice of pe: sons near the i: strument. Bb keeping paper from becomin: mixed with othe material, the hold er guards them from being blown awa or being mistaken for waste. Sheets «

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POPULAR MECHANICS and letters may be placed in the clamp reading while a telephone user is oc- ed in writing with his free hand. As | to proper distribution of office mail, clip may be employed as a container individual correspondence, insuring diate attention to unopened matter keeping it separate from other papers. Baseball Game with Dummy Batter Tests Player’s Ability \usement-park visitors who like base- ind also enjoy testing their skill, are ave an opportunity of enjoying some e thrills of the real game in a conces- device recently patented. It con- of a realistic figure of a ball player bat in hand, a revolving disk carrying suspended above his head, and a r in easy reach at the operator’s booth ed the usual distance in front. The ct of the game is to pull the lever, h is connected to the bat, at the per instant so that it strikes one of the balls whirling by as the disk turns. If the play is successful, the ball is swung to an upright position and held out of the way. The speed of the revolutions can be Jummy Ball-Game Booth with Batter, Balls on Disk and Lever That Operates Bat ide fast or slow. The disk is generally tted with three balls and score is kept by sunting the number of hits and misses. Girl’s Skill at Art of Gem Engraving Opens New Field for Women Gem engraving, an art dating back to the times of ancient Babylon, has received 1 new impetus in late years, and the de- mand for portraits and designs carved on emiprecious stones has increased with de- 441 velopments in the styles of setting. Much of the success of the gem engraver is said to lie in his deftness of wrist in controlling Skilled Young Woman Apprentice Cutting Portrait on Gem with Special Lathe and Tools the amount of pressure given the stone as it is held against the tiny lathe, and the skill of a young woman apprentice in the art seems to indicate that women are pe- culiarly adapted to the task as they natu- rally possess a keener sense of touch than men. The engravings are made either in base-relief or intaglio, that is, sunk be- neath the surface of the stone. Delicately shaped cutting tools, using diamond dust mixed with oil as an abrasive, are em- ployed to form the designs, which are first marked out in blocks and then cop- ied to scale on the stone to be cut. If the stone is held too hard against the tool, the dust wears off, leaving the surface too smooth to be cut. The correct amount of pressure causes the fine material to lodge in the pores of the steel, making it act somewhat as a file. Pedal on Auto Accelerator Assures Smoothness and Driving Comfort For cars and trucks, an accelerator with pedal attachment to insure more uniform gasoline feed and greater comfort in driv- ing has been de- vised. It is so ar- ranged that the pedal and gas but- ton may be oper- ated in unison with only four = y-- ounces’ pressure, while, because of a sliding brake-shoe arrangement under the footrest, more than thirty-five pounds’ pressure is required to depress the pedal unless the button is touched The two fit closely together for easy operation. first.

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142 POPULAR MECHANICS Latest Ideas in Building Your Home Space, Time and Labor-Saving Devices Make Small House Luxurious without Boosting Cost to Prohibitive Figure By J. EARLE MILLER a SE vou gol to build a ne home A ( 9 Wool d von hiiaild ] ‘ J 1 l l ouse Ot your n if you could get the kind of home tu want tor the price you can afford to It is possible to do that now. The rchitects of the United States have set themselves the task of making the na- tion’ I ll homes attractive, comfortable, economica durable, and yet keep the n e limits the averagt buildet can afford to pay Chev have done it by i d the O d methods ot hom«e ( began bv analy x the 4 ~ | nye t is 1 neces- and leavin xr it out, and the prepared ures to sho what each fe iture that mav go into vour home will cost, whether and whether, ta , it must be built at the > a ha lded 1 se , Or can be added iater. Homes for generations have had cellars it is a necessity ora luxury, 7 firstasa place to store proy isions and later for the furnace, but with modern heating lants a cellar is not necessary, the archi- ects say, and proceed to point out how vou can save one-fifth of the cost right at begit n Y by lorgett 1) ment. | yu use gas or « ( eating plant can be installed in the ¢ ner of the kitchen, pro ided it is one the new-style furnaces that look like thing else—a talking machi ample. If you use coal, have discovered that it is cheaper to an additional room to hold the fur and coal pile than to dig a cel a cement floor, put in wal ind | : “ar : other things a basement needs. The new idea in home building ork of the Architects’ Small-House sé ice bureau, an organization to whicl architect is eligible if he bu a share stock at a cost of $100, on which he is 1 mitted to earn $8a year. It is not a pi making body. Div ide d into seven regio1 bureaus, the organization me | duce plans for attractive small homes suit able to each section of the country. 1} best plans are then purchased by the bu reau, paying the regular $300 or $400 fe Complete copies of plans, buying list, quantity survey, an mbers pt specincatiorl

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POPULAR MECHANICS 443

= . i } 4 it ' : » 3 ] oa 4 | | g 7% | cae A | ’ ” in Pa , pri 4 y 2 , |) 2 ? — is Cc » e oF , see te a= oF se ’ cdl ns , 73 Ss Soa) —~ ea a \ : -< : Top, Left, an Attractive Small Stucco O) pe - Home with Red-Tile Roof and Three yf “ Tall Windows Opening into Story-and- \ : a~Half Living Room; Right, a “Vacuum- \ On Bottle’’ House with Insulating Material \( pr Made of Sugar-Cane Waste under the -, Weatherboard and Used in Place of 11] 5u Plaster Inside; Below, Left, a Well-De- | lr} signed “Skintled’” Brick Home with Rough-Stone Archway, and Right, First | bu Stucco Coat Laid on Hollow-Tile Wall } , } Tee ons a . <

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444 POPULAR MECHANICS forms of “fool-proof” contract agreements are then supplied to home builders at a nominal fee of about $5 a room, or $25 to $35 for the complete service, which in- cludes professional counsel and advice while you are building the house. The bureau is not aiming to interfere with the private practice of architects, but to bring well-designed homes to people who could not afford to pay the $300 or $400 fee for individual plans. Besides furnishing complete working drawings and other details for the house you want to build, the bureau has printed floor plans and photographs of more than 200 model homes, ranging from three to six rooms, and sells the booklets at cost prospective home builders to want. to permit pick out the style of house they 146 POPT'T apn After the selection is made, complete p! may be obtained on approval. Robert Taylor Jones, of the Amer Institute of Architects, who is techn director of the bureau, has compiled a of forty ways to save money in building The cost of the model homes may ya: $2,000 or $3,000, depending upon what luxuries are added or omitted. One of the most popular plans for the northwester region, a six-room Dutch colonial typ. has cost all the way from $6,500 to $10,000, depending upon whether a porch was add ed or left off, whether the hardwood tri: was the best of the five grades or a cheaper one, and similar details. If you are going to have a cellar, he says, it is not absolutely necessary to put in the partitions when you build, except for the fuel bin. The others can be added later, and you will save $50 to $150 b omitting them at the start. If you ha a fireplace you may expect to pay $300 o $400 extra for it, perhaps even more, « pending upon the material and labor cost The brick foundation course improves wooden house and is almost necessary u! der a stucco home, but the higher it goe the more it will cost. From $50 to $150 may be saved by limiting it to the lowest practicable height. When cutting off t! non-essentials, he suggests the porchast Top, Space-Saving White-Enameled Kitchen Equipm« Includes a Broom and Mop Closet; Below, Right, C: bined Refrigerator-Kitchen-Cabinet Unit. The “Pi man Nook,” Left, Is a Convenient Breakfast Alc: NIRCTTHANTCOS

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POPULAR MECHANICS 445 Plenty of Asbestos Cuts Cost of Feeding the Oil-Burning Furnace “Op, and Kitchen-Style Gas Furnace, at Right. Center, Gas- ed Clothes Drier and, Below, Electrical Equipment of Laundry t sacrifice, since it can always be added a small home, and costs one-fourth les ter. The saving may be anywhere from than a twelve-inch wall. Prices of brict 00 to $600, or more. A glass-inclosed poured concrete, concrete blocks and til rch is expensive, not only requiring vary in different localities, and a bit ot indow sash and glass, but interior trim, careful shopping for the cheapest usua iinting and a better grade of floor. The pays. If you are going to have a base «tra cost of glazing the porch may runto ment it is not necessary, Mr. Jones point 500 or over. Screening the porch is an out, to follow the custom of extending lditional expense; double screens cost tnder the entire house, which involves ex 1. it more than single ones, and metal frames ra excavating and foundation walls. T! —_ re than wood. Screen wire comes in cement floor, he suggests, may be added t, Cc \inted steel, galvanized steel, copper or later, if you can’t afford it at once ain ronze, and he advises buying the one best Tile makes a fine bathroom floor, but aited to the purse. A nine-inch founda- may cost from $25 to $50 more Ke xterio tion wall, he finds, is usually sufficient for stucco walls will cost from $150 to $250 nm arrrTria Ty arwoewesTrTrTrét.~a ATT Orr Aaa

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146 POPULAR more than wood siding. Brick walls may mean an initial expense of from $400 to Ss00 more, but give a better fire-insurance rate, eliminate painting and not only are more durable but lessen depreciation. Wood shingles, patent roofing in rolls, or shingles, tile, or real-clay tile can make a root cost almost any amount. Unpainted shingles are cheapest, those dipped in stain come next, and brush-coated shingles may cost $25 to $50 more. Mr. Jones ad- vises eliminating the porch and similar items and investing the saving in better materials, including roofing. He also ad- vises insulating all exterior wooden walls, particularly in regions of severe winters. The cost may range from $75 to $150. Built-in kitchen fittings may cost from $100 to $300, and, unless exceptionally well designed, are not so serviceable as a well- built ready-made cabinet, he says. Extra bookcases, wardrobes, china closets and open stairways all cost money, but can be installed later. A _ built-in refrigerator with waste pipe and platform may cost from $25 to $50 more than a separate ice box not so well equipped. [f all rooms are not needed immediately he advises omitting plaster, finish floor and wood trim in the spare ones until later. Stock moldings, doors, sash and trim cost less than special millwork. Hardwood floors are more expensive than soft, and each grade of hardwood has a different price. There may be a difference of $50 or more between the first and sec- ond grades of oak flooring. The medium grades are durable, and, if the millwork is well done, and painting, filling and stain- ing of the right sort, the appearance will be fine. The difference between soft and hardwood trim may be $150 or more. For finish, stain and varnish cost less than paint, the difference amounting perhaps to $100 or more. Mirror doors, plate-glass or double-strength glass windows vary in cost, and careful pricing may mean con- siderable saving. A clothes chute is not an absolute necessity, and a good metal one will cost $25 or more. The architects’ bureau advises alway buying the best plumbing fixtures you can afford, whether vitreous china, iron coated with enamel, solid porcelain. A sav- ing can be made by picking a design in keeping with the money you can afford to spend. <A recess bathtub, for example, will cost $35 to $50 more than a simple leg tub. Solid porcelain lavatories cost more than enameled iron, the latter saving $25 to $50. The “pop-up” type of lava- tory waste will cost $3 to $5 more than a simple chain-and-plug device. A kitchen or MECHANICS sink, with drain boards or apron ca costs more than the plain type, and can be used in their place if you want to save. A combination hot-and-cold- faucet may cost $5 or $6 more than rate ones. Laundry tubs, built in be had in a wide range of prices. Hot water heaters vary, too, and Mr. Jones ad vises always buying the best you can af ford, and likewise the best heating | your pocketbook will stand. A heat reg lator saves time and steps and fuel, will cost anywhere from $50 to $160, pending upon the type. It can always | added later. Radiator valves, too, ha wide price range. High-type radiators « less than low type, but only the latte: be fitted under windows. Insulation heating pipes varies in cost, but good sulation saves on the coal bill. Finish hardware and electrical fixture may cost anywhere from two to five cent of the entire house bill. On a $6,500 house the range between cheaper and ¢ pensive grades may be from $130 to $325 For the small home there is a wide range of ideas and devices to save space money. A new door lock, for example, can be installed by boring only two holes instead of painstakingly mortising out section of the door. Even a slow carpe: ter can install four an hour, cutting d the labor costs. On the side of conve: ience there are myriad devices. A patent ed double-hung window may be swung i: side so that the outer surface can washed while standing on the floor inside eliminating all dangerous climbing. A convenient lavatory can be built into a wall no more than four inches thick, thi basin folding up when not in use, while mirror slides down to cover it. Instead o! inconvenient hooks for closets, one fir makes a sliding hanger rail which fol into the closet when not in use, and « be drawn out into the room to give rea access to any article, without taking d¢ everything in front of it. space saver is a small sleeve board and large ironing board which are built i the wall, with a door to cover them wh« not in use, the hinged board folding ward. The whole device—dcor, and all—comes assembled ready to be stalled. Instead of expensive tiles { bathroom walls, a new fireproof wallboard made of gypsum can be used. It is i pressed with a ceramic tile design a1 takes a very high enamel finish. For vet tilating the kitchen and drawing off odo: and foul air, a “ventilating brick” no being made with an outer surface just tl size of an ordinary brick, so it can be buil One convent Casi is

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S6 5x id ¢

C be J] Iboat t i Jith Hinged Windows At- ‘a to the wall up near the ceiling. A three- h pipe runs through the wall into the ve od rT t e ve built a model home from architects’ ist tl 11 mperature - recording POPULAR MECHANICS

Easily Bored Holes Install Below; Windew Latch at it Can Be Locked Open a Trifle for Ventilation tive Screens Are Hung eee to Open into oom

m. For small families the breakfast ‘k, or “Pullman,” is proving quite popu- A folding table, built out from the ll, and two benches like Pullman seats, be fitted into a recess off the kitchen. e popular design occupies a space five four inches by six feet, and accommo- es four people. o show what heat savings could be ide in a properly insulated house, the nufacturers of a wallboard made from waste pulp of sugar-cane factories, eau plans in Chicago, and fitted it with devices. The

447 << ee The “Ventilating Brick,” Below, Can Be Built into Kitchen Wall to Draw Off Odors; Center, a Space-Saving Ciothes Hanger

=== The Patented Window. Be- low, Makes Window Wash- ing an ay | Task, Done n

from Indoors

house, one of the most attractive stucc: bungalows the bureau has designed, ha no basement, the heating plant being | cated in the kitchen. The exterior wal are lined with the company’s product a1 the interior finished with it, a plaster coat ing being added in some rooms, while in others the material is left in its natural state. It can be tinted, stained or ste ciled, and even made to look like stone, with all the beauty of coloring of fine marble, and the warmth of color of lime stone. The model house is practically a vacuum bottle, a principle which is being applied more and more to homes, to keep out heat in summer and cold in winter. Experiments with the material in homes

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> 148 at Beverly Hills, Calif., have demonstrat- ed that proper insulation will keep out the heat and retain an even temperature at night, when the outdoor temperature drops suddenly after sundown. The bungalow, which has a big living room, fireplace, entrance patio, bedroom, bathroom, and kitchen, cost $9,835 at Chi- cago prices for materials and labor. It could be built for considerably less than that in regions where material and labor costs are lower. The labor bill alone was $5,455 and cost of material $4,380. The latter includes such luxuries as ornamen- tal iron-work balconies, red-tile roofing and a decorative brick, tile and stucco- finished fence. Part of the cost of the model house was due to the fact that the rear wall was constructed in three sec- tions, one of brick, one of stucco and the third of weather boarding, all three being over the insulating material. Windows were installed showing the interior con- struction of each section, for the benefit of visitors who inspect the bungalow. Normal construction would save some money there. The tile cost $475, while composition roofing or shingles would be considerably cheaper. Only the highest grade materials were used through- root POPULAR MECHANICS out, whereas cheaper grades of lum! hardware, fittings, plumbing fixtures other materials would cut the cost d without materially cheapening the hou While used in this hor brick is coming back into general favor { well-built small homes. Long looked with disfavor because of its lack of beaut the renaissance of brick has been brous about by a new method of laying, call “skintled” because of its likeness to tl stucco was way bricks are piled in the kiln for baking Skintled brickwork is simply laid with the bricks at odd angles, giving broken surface whose beauty rests in t lights and shadows resulting from Charming effects have been achieved laying the walls of the lower floor skintled brick, whitewashed, and the per story of stucco, with a roof with rou, rounded edges imitating thatch. One of the most attractive skintled-bri houses was built of culls, the defecti bricks discarded after baking. The arc! tect chanced to see the refuse heap at t! brickyard, and when he asked to buy t! culls, was told he could have them for the cost of carting them away. was a particularly effective rough wall, r sembling field stone more than brick. The resu i The Fireplace Adds Considerably to the Cost of a Home, but on Long Winter Evenings Is Worth It. Floor in This Living Room Is of Rubber Tile

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POPULAR MECHANICS 149 Linen at Half the Price of Cotton Seen in Improved Flax ‘*Puller’’ en may be produced at half the price ttton and flax-growing may become a table industry in ev- tate of the union if Mail-Box Safe for Apartment House Stops Theft and Aids Carrier Large enough to accommodate maga- zines and other bulky articles with little ved machinery de- ed under the direc- of a mid-western mobile manufacturer, es successful. The ratus consists main- fa “puller” of simple truction and easy to rate that efficiently rates the fiber from plant, and machinery ereby the thread is converted into cloth in e continuous opera- [In addition to these entions, ways of ferti- ng the soil so that flax can be grown success- y year after year are said to have been discov- ered. The plant can be iltivated in practically every section of s country and in many parts of Canada. advantage in favor of this crop is that as no parasite. Auto Oil Gauge Lights Signal Lamp to Warn When Supply Is Low Attached to the drain plug in the crank- case of the automobile engine and elec- trically connected to the motor and a red ignal light on the dash, an auto- matic oil gauge irmns when the upply gets low and stops the en- ne before dam- ge can be done through burning ut the bearings. \ series of floats so arranged that when more oil is needed, an electric contact is made, lighting the gnal lamp. This burns until the necessary supply is added. If no lubricant put in when the light flashes and the floats sink lower, the motor is automati- cally stopped as an additional precaution. Tenant Taking Mail from His Private Box and Carrier Delivering Letters through Wide Upper Door into Individual Compartments trouble, a mail box has been constructed for apartment-house use that is virtually a small steel safe, set in the wall and pro- tected by a master lock the key of which is carried only by the postman. The top part is covered by a single door which drops down when the master lock is re- leased, exposing the separate compart- ments. The absence of the usual narrow slit makes it easy to put the mail in and there is no opening to allow pilfering with hooks or fingers. Below the main door are separate ones to the boxes. These are opened by individual keys. The safe is made with three, four, five or six units Automatic Pocket Poultry Killer Insures Proper Bleeding For killing fowls of all kinds and sizes for the market, a pocket-size device ope ated somewhat in the same manner as a pair of pincers, is said to insure proper bleeding of the birds and thus increases their market value. It consists of a small sharp blade and a clamp which are squeezed together by pressing the grip with one hand. The blade part is inserted in the chicken’s mouth and the other side fits at the back of the head. When the grip is pressed, the veins in tl severed. This method is regarded as en tirely humane and sanitary. le ne k are

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$50 Safety Brake Fitted on Hand Truck Eliminates Blocking Wheels hauling heavy objects with hand trucks easier and safer, a simple ing attachment has been patented that To make : braking Applying the Foot Brake, and View of the Bar, Springs and Bands can be put on almost any two-wheeled truck in a few moments. It consists of a pair of brake shoes lined with regulation material, bolted to the sides of the frame and connected with a telescoping cross- bar. Two heavy springs hold the shoes awav from the wheels, and friction is ap- plied when wanted by simply placing the foot on the bar. With this attachment, there is little danger of the carrier running back while getting the load on, the aid of a helper can be dispensed with, time is saved not having to block the wheels, and the orkman has both hands and his full eight to apply to the object he is loading. Speed of Finger and Vocal Muscles Shown in Playing and Speech The efficiency of the human body is il- lustrated in hundreds of ways, but the re- markable speed of which the muscles are capable is said to achieve its highest devel- opment in the performances of violinists nd pianists and in the movements re- quired for ordinary speech. It is esti- mated that a skilled violin player will exe- POPULAR MECHANICS cute as many as 600 finger motions minute, while a pianist playing the “ ute Waltz” must touch 740 keys wit! right hand in the same length of ti: some artists are able to do it in thirty or torty seconds. In talking, the muscles are often called upon to perf twenty-five definite motions in one ond. Fast as this rate is, it appears when compared to the rapidity of th tion of a house fly’s wings which are to make 330 beats a second, probab! world’s record for natural flyers. ‘ Crutches on Casters Built for Dog to Help Cure Auto Injury Paralvzed in. the hind limbs as the sult of being struck by an automo “Sport,” a pet dog owned by a Wiscon man, was pronounced incurable and p: arations were made to chloroform But an inventive veterinarian heard the case, designed a roller cage in w! “Sport” could push himself about wit! forelegs and now the dog is said to be on the road to recovery. Strips of sc: iron were bent and bolted to form the su port, which, when completed, resem! the frame for a small kennel. “Sport injured members were held from the {i by means of bandages passed under body and over the top loops of the ca where they were tied with strings. 1 dog was taught to use the contraption placing him in it before he was given food, and he would then push him along to his dish. Now he has learned t bark until he is put into his wheel cl and manages to travel a considerable di ny Se Pere ~ Strapped in His Special Invalid Chair, “‘Sport’’ Push« Himself About with His Forelegs tance each day. The gradual exercise a1 protection to the injured limbs are work ing what is expected to be a complete curt

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POPULAR MECHANICS 451 Copies of Drawings Made to Scale by Dry Photo-Printing Process True-to-scale copies from tracings of engineering and architectural drawings similar work may be Toy Kitchen Cabinet Has Roll Front and Adds to Value of Play Modeled closely after the usual-sized article, with a roll front, metal or porcelain

easily and cheaply made, _ : is claimed, by a dry hoto-printing process hich a London firm has nnounced. The paper furnished in various hicknesses and is ex- sed in the same way . the ferro-cyanide kind | ior about the same me but requires no sub- ‘quent washing or treat- ent with liquid chemi- cals. Printing is done a wooden box fitted ith trays below which placed a dish of liquid mmonia. Fumes rising rom this substance act ipon the paper in such a avy that the image de- ired is printed in prac- tically black lines on a hitish background. As 0 stretching or shrink- ng of the paper, such as occurs in using liquids, is

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caused by this method, exact copies may be ob- tained. They are said to he permanent, and in making corrections on the prints, lines can be removed with little trouble with a solution of hypochlo- rite of soda or a five-per-cent solution of permanganate of potassium. Daily Trips of Nation’s Autos Total Three Hundred Million Miles Estimates prepared by the federal bu- reau of roads show that the automobiles in this country make daily runs totaling more than 300,000,000 miles, traveling in two days a greater distance than that cov ered by all the passenger trains in the United States in a whole year. The fig- ure is based ona report from the depart- ment of the interior that 794,030,852 gal- lons of gasoline were consumed in the month of July last year. It is estimated that at least eighty-five per cent of this amount was used for motor vehicles. On July 1, 15,552,077 autos of all kinds were registered, and it is assumed that fourteen - 4 . » ¢ . ‘ miles to the gallon is a fair estimate of ha - _ . - ~ one side burns “< out, it can be i turned around and the other end - ees eel used, have been _ ee — placed on the market. An insulating wall is placed i: the center.

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- POPULAR MECHANICS Camera Corps That Filmed Colossal Movie Production; with This Battery of Lenses Re cording Every Scene Miles of Pictured Ribbon Were Harvested for the Director's Selection of Fi nal Reels Hunting Human “Game” with a Camera Adventures of Press and Movie News-Reel Photographers Filled with Hair-Raising Experiences as Well as Amusing Episodes I UNTING in Africa has few thrills to to wade eight miles to the city, throug! equal those encountered daily by the water irequently up to. their shouldet meraman seeking human “game” for Once arrived, the films were “shot he newspapers and movie films. Men or within a few minutes, and then one set out vomen who do not want to be photo- onthe return journey. He found a loc craphed bring all their ingenuity into play motive and its engineer, twelve miles fro: to outwit the pursuing picture man, and, Dayton, but no fireman. The photog if that fails, they sometimes turn and as- rapher bra: enly represented himself as ult the photographer. The elements, qualified union fireman, and succeeded 0, are in constant battle with the picture buying the engineer’s sympathies as wel ker, who must not only get tothe scene as the use of the lecetuetten, Once out f a big story and get his pictures, fre- on the road, his first dozen shovelfuls ot lv under extremely adverse condi- coal showed he had never fired a boile: tions, but likewise get them back to the beiore, but the engineer demonstrated office again. how it should be done and they crept For real thrills the man who took the north Sma Toledo, where they first pictures of the Dayton flood in 1913 lived an ordinary lifetime in one dav. The vare met by a mob of newspaper reporters and photographers, all trying to get to Dayton relief expedition was stalled six or eight or get news from it. The photographe: iles from Dayton by a washed-out with the plates took no chances on having ] ridge. The photographer and his assist- his precious bag stolen and, being dead for nt had invested in rubber hip boots, and _ sleep, took the precaution of borrowing a th had a piece of sausage more thantwo pair of handcuffs from the police depart eet long for rations. Tying the sausage ment, locked the bag to his wrist, and hid round their necks and balancing camera the kev in his shoe before starting for upplies on their heads, they started Chicago. Getting a picture of a celebrity

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Snapping Newsy Photos Poised over a City’s Canyons ke * = ot, 2 POPULAR MECHANICS On the Trail of Picture Stories in Mountains of Central Asia Risking Dangerous Foot- ing to “Shoot” Roof Scenes among Skyscrapers

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POPULAR MECHANICS Where Photogra- phers Hazard Life and Limb Providing Thrills for the Sil- ver Screen; Below, Cranking Camera Strapped to Side of Moving Train mim Vr Vv a WY acewsenw~y7TyTéi.eféhkTtT OT Ort Oe

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POPULAR MECHANICS i. =“ a _ ——1 : | Sea -_ * m et / = | Ready ay as Barrage of le / at Spears Comes from Dusky 5 / i at Warriors of South Seas ; ; ¢ | a On High Roof in Alaska Us ing Semaphore | Signals to Di | rect Action of Players filming Mo Every Is Used by Cameramen Who Overlook Nothing to Make N = — Good Fi'ms ; i . : \ Vantage Point

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156 POPULAR — > ae / Lying by a Roadside to | Get Close Shot While Making a Movie of Speed- ing Auto Taking \ a, caréeue ™ Curve Despite Diffi- ’ culty of Tak- ing Pictures of Aerial Scenes Agile Opera- tors Find Queer Ways ' to Accom. plish the Tasks News Photographers Dare Any Risks to Get Scoops on Inter- esting Pictures a © U. &U. me MECHANICS Ser ho doesn’t want to be photographed is equally hazardous. Several vears ago hen a certain banker's affairs were oc- cupyving public attention he emploved sev- eral armed bodyguards to keep photog- raphers away. One of the picture men, however, made a study of his habits and found he left his home at the same hour each’ morning. He then bribed a milk- agon driver, cut a hole in the canvas side of the wagon, big enough to expose the lens of the camera, and the next morn- ing, as the banker left his home sur rounded by his guards, the milk wagon drove slowly past, with the hidden camera- man taking pictures as fast as he could load and shoot. During a divorce hearing some years ago, the defendant, a wealthy man, ob- jected to being photographed on the stand, and his attorneys obtained an order from the court barring photographers. One got past the bailiffs, however, as he did not appear to have a camera with him

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POPULAR 1 idge hi the intruder and m to the bar, where he repeated rder and threatened to send any of- r to jail “for life.” When the aiter- edition appeared, spread across the page was an eight-column layout ng pictures ofthe judge delivering his ng, the defendant sitting beside the e in the witness chair, the defendant’s and attorneys, and then a series show- he bailiffs stationed about the room photographers out. Fortunately e photographer the court enjoyed the but asked to be let into the secret the man got the pictures while ling at the bar being told not to. The ination was a small cameraanda derby ith a tiny hole cut in the top to ex- the lens. As the photographer stood recognized r ep ] l re the bar he held the hat in both against his chest. e movie news-reel men are alwavs eriencing thrills. Some time ago one over Vesuvius in an airplane to film crater, and when the plane disap- red in clouds of smoke the report read that he and the aviator had fallen to the boil- ¢ lava. It not un- some urs later 1t 2° Wee arned the ine had passed fely through smoke and emerged on other side nd flown on back town to land movie man ifely. ££. G. lutt, a news meraman, was ving over Los \ngeles taking ictures of a tunt performer n another lane when he ] ( ( e How Cameramen Engage in Perilous Tasks to Get MECHANICS 457 stuck his hand into the propeller, losing three fingers. Instead of telling his pilot of the accident, he tied up the wound with a handkerchief and kept on turning the crank until the assignment was completed. It was not until the film had been rushed to the laboratory and developed that Hutt fainted from loss of blood and it was learned that he had been injured. C. | Kayo, another news-reel man, was sent i to Mexico to get pictures of Villa in the hevday of that bandit’s glory. He was caught at it, and Pancho stood him up against the nearest wall and ordered out the firing squad. Before giving the order to shoot, he asked if Kayo had anything to say, and the cameraman replied: “Yes. Since you don’t want pictures of you shown in the United States, I like to destroy the film of you before I die.” Villa was so touched he ordered Kayo released, and the photographer gravely destroved a reel of film, but it was an un exposed strip, and he brought back to the United States the first pictures of the ba would dit leader in his home surroundings. The film man must be a diplomat plus, with nerves of iron. Filming animals and children would tax the pa- tience of anyone but an iron man. ry getting a kitten and a baby to lie down in the same crib and both go to sleep. Yet, the movie men have done it, and it looked easy on the screen. Hours are sometimes spent in watchful waiting to catch a lion roaring or a tiger yawning, while with babies it 1s frequently necessary to hide the camera behind a screen in order to catch them plaving . 1 In natural positions. iS | Realistic ouch in Their Pictures

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158 POPULAR MECHANICS Tug of War between an Airplane and a Heavy High-Powered Automobile to Determine the Stronger Machi the Contest Resulted in an Easy Victory for the Flyer Plane Wins Tug of War with Auto during Contest on Ground During a tug-of-war contest between a high-powered automobile and an airplane, held at a San Francisco aviation field, the flying machine dragged the car backward for a considerable distance. The plane, with its running gear equipped with four pneumatic-tired wheels, had little difficulty in pulling the heavy vehicle, the engine of which was kept operating at’ high speed. lo make the task harder for the airplane, the automobile, which was a touring car of rather heavy type, was loaded with seven passengers. Metal Mender Repairs Hose Quickly and Neatly The mending of steam, water and air hose, usually a troublesome job, is greatly simplified by a mender recently put on the market. The device is made of metal throughout and consists of a_ nipple that fits into the adjoining ends of a hose and carries two light spi- ders that may be forced into the surface of the hose. To attach, it is only necessary to slip the nipple into the hose and ham- mer the spiders down. There are no clamps or projecting parts to catch when ground, they do the hose is dragged along the | and as the nipple ends are short, not appreciably affect the flexibility ott tube. The manufacturers claim that mender will not leak or puil out undet highest pressures. Collar Button for Tight Neckbands Eases Strain of Shrinkage With the use of an extended collar b ton, neckbands of shirts and similar gai ments which shrink from laundering be made to fit the wearers without need of cutting buttonholes or re placing the piece. The link is con- structed to allow both-~the collar and. shirt to be adjusted com- fortably and re- places the shrink- age without in- juring the cloth. Neatly designed of strong metal, the d vices are said to increase the girth of t! bands without distorting the front of tl shirt, resulting in the saving of favorit garments which might otherwise be thrown away. Early Railroad Builders Hold Record with Ten Miles of Track in Day Not all the high-speed records can bh claimed by modern enterprise. Researc! into the performances of the men wl! built the first transcontinental railroad the United States shows that on April - 1869, a crew of 8,000 men with five trai loads of material, on the Central Pacit

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POPULAR MECHANICS 459 lroad, laid ten miles of track between n and nightfall, a record which is be- ed not to have been equaled in later even with improved machinery and In all, this pioneer crew laid about 0 rails that day, handling some 1,000 s of metal with their hands. A pair of s every thirty seconds and a mile of ck in three and one-half hours were sidered ordinary performances in those s of romantic trail-breaking across the tern plains. It is true that modern tipment is much heavier, and the track s not so solidly ballasted as is custom- nowadays, but the comparison is not irely unfair when it is considered that workers of fifty-six vears ago did al- t all the labor with their hands. 1 Portable Hoists That Climb Poles Save Labor and Storage Space lectric elevating platforms that climb hed poles by means of motor-driven rs have been designed to lighten labor save time and space in garages and rage houses. The hoists are equipped strong metal rollers so they may be ed about as needed, and can be easily ndled by one man. Either end of a car the entire vehicle can be raised to per- it work to be done on the under parts, liminating the necessity of pits or ele- ited tracks, while cars can be quickly liited for double-deck storage arrange- ent. The platforms which come in con- ct with loads are constructed to prevent ‘ratching painted surfaces or damaging he machinery of automobiles. tomobile Hoisted by Portable Pole-Climbing Ele- vator to Permit Work on the Car’s Under Farts $ ee ~ , aute 7 - | Traffic Policeman Signaling with Illuminated Disk Lighted from Pocket Battery for Night Service Flashlight Stick for Traffic Police Helps in Signaling at Night German traffic policemen on night duty are using sticks with an illuminated disk at the end, lighted with current from a pockét battery, to make the “stop” and “go” hand signals more easily visible to motorists and others. Che little torch catches the eve at a considerable distance, calling attention to the fact that a police man is stationed at the intersection, and thus affording an extra warning to drivers who might be tempted to speed by. The stick is as long as a police club and the light is turned on or off at the grip handle. Tinkling Bells Tied in Toy Balloons Add to Children’s Delight Added enjoyment is afforded children from the toy balloon by a tiny bell at- tached inside to the stick, where it tinkles musically with the movements of the sphere. The little instrument is so small that it lessens the buoyancy of the globe only slightly, and the bells are also said to increase the effectiveness of toy balloons for advertising purposes.

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460 POPULAR Fruit Tester Tells Food Inspectors if Products Are Overripe Pinching apples, pears,and other fruits with the fingers is considered a fair test ‘of their condition, but food inspectors oi the Food Inspector Testing Ripeness of an Apple by Meas- uring Pressure Required to Bruise It department of agriculture have a more neans of determining if products are too ripe to be fit for shipment or sale. They use a plunger device which measures maturity in pounds. It consists of a small rod within an outer casing containing a steel spring against which the bar rests. One end of the rod is placed against the fruit and the end of the barrel held in the hand. By pushing forward, the pressure on the spring is registered on a gradu- ated scale on the casing. The figures are made easily legible by a small electric bulb which lights automatically when the plunger pierces the skin of the fruit. The amount of force required indicates the condition of the specimen. accurate ‘Invisible Hands’’ to Guide Planes by Electric Cables on Ground In the belief that the time is not far distant when the recognized air routes will be so thronged with planes and flying danger of collisions will at method of travel, lready ships by means of craft that the peril the the British royal air ing a way to steer the electric cables laid on the ground directly beneath the paths taken by the air liners. An indicator in the pilot’s cabin or in the cockpit, actuated by the electric current, will instantly show any departure from the right course or there will be an automatic device which will put the ship back in line without the pilot’s attention. Thus, it is proposed, the craft of the skies will be guided al certainly as the steam trains are kept on the track, and all the pilots will have to do will be to keep the success of th force a is seek most as MECHANICS motor and maintain system, it is most ot the dit night or in smoothly even altitude Such a lieved, would also solve culties of flyirig at running ’ 1ogs. Lumbermen Put Insects to Work Stripping Bark from Logs Barking logs cut for paper manufactur is an expensive and important process, i none of the outside material must ret to the pulp or it will spoil the quality the finished product. The cost of tl work has been reduced by a southern co: pany, according to reports, by girdling t! trees in the late summer, thus attracti beetles and other wood-boring insects t] so completely loosen the bark by the ti the tree is to be felled, that it can stripped off with but little difficulty. | Burma, the natives have used ants in t! way to remove the bark from sandal for export. Woo Screw with Square Niche in Head Prevents Driver — Off as screw heads are A, xl Screwdrivers as well ] especially damaged frequently, working with hard woods, as the tool can f Square-End Driver and Screws, with Slots to Fit, f Inserting in Hard Woods the usu has bee not get a satisfactory hold in tvpe- of slot. This difficulty overcome in a screw with a deep, recess in the top. It is driven with special screwdriver shaped to ‘fit tighilv i the niche, the end taper ed sli: ohtly to a sure a firm grip. It is cl y leer th: at screv of this kind can be put in or wi square thdrawn more easily than the usual style, and there is little danger of the driver slipping out thus preventing damage to the head or to the surface of the wood With the square recess, it 1s possible to make the scre eads smaller and put screws more closel together.

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Li aes of The Ill. London News POPULAR MECHANICS 461 gon of the Insect World; a Rove Beetle Devouring a Fly, One of the Many Tragedies That Take Place in an Almost Hidden Life Now Revealed by Movies Insect Toilers Revealed by Movies Trapdoor Spiders, Mud-Daubing Wasps and Queer Diving Beetles Shown as Tiny Workers of Hidden World ry. LAT life i insect s filled with tiny asons, architects and workers which ear to construct their homes with thematical precision has been shown lotion pictures revealing the mysteries n almost hidden world in marvelous red nstrosities more d mas” staged in the haunts of winged crawling little creatures. Cameramen » photograph such scenes are often re- to spen d ks and months tireless effort patient wating et the stories of careers and s of the elusive rs.” Lenses magnify the to several their natural disclose minute rival- in ugliness the giant rds attributed to prehistoric age. 1 many of the re familiar in- ts, once thought 1rects be harmful to are shown in ity to be the Examining a Tadpole “Actor” Which Has Been Stolen from Its Native deadly enemies of pests that often wreak havoc to crops and animal life. To photo- graph the activities of a trapdoor spider, a cameraman spent more than seven weeks filming the busy little worker as it hustled about the opening to a home it was con structing in the soil. Having built a tunnel into the earth, it lined the interior with smooth, hard clay, and closed the outlet ith a per ectli formed trapdoor of mud and silk fibers that fitted the hole as snugly as a stopper in a bottle this door al nvge oO I was attached so the occupant of the nderground den could swing the ( eT b ici i d ( ] 1 ne there e the d ne beetles and the boat man beetles al l others that go about burying small dead nimals and birds in STaves the. | be neath the bodies so they will slow! Haunts for Filming sink into the cavit

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162 POPULAR MECHANICS and disappear from sight. Army ants in all their splen- didly organized ex- istence are magni- fied for the screen only after much preparation on the part of the “direc- tor’ to transfer the colonies and their moundlike homes so the _ intricate mass of tunnels and chambers can be bisected by a glass panel through which the insects may be watched undisturbed while they hurry about the various duties of pro visioning food stores and caring for the young. For night-flying bugs, caterpillars and moths which do their work silently under cover of darkness, special lights are used and arranged so the rays are partially concealed to avoid frightening the little toilers while the camera is registering their every movement. For the more wary vic- tims of the lens, much time is devoted by the operator in making the subjects ac- customed to his presence and the noise of the machine. Honey and similar tempt- ing feeds are placed in the vicinity of webs, holes, crevices and other abodes of the in- sects. Meanwhile the camera is set up to command a view of the surroundings and turned while the subjects can see it. Only when the bug or fly seems to appear con- tent with the presence of the operator and the apparatus are actual pictures at- tempted. it beetles and many other tiny subjects have been filmed for the movies by Miss Lucile Berg in a Chicago studio. A miniature garden with small sunken and flowers has been set up in which the in- sects can live in a natural state while the photographs are being made. Frequently, p¢ y0ls i he, | DOE LEE PEALE. Ys «NOE lh lal Me Me be Powerful Camera Lens Focused on Colony of Wasps . Ready to Register Their Busy Movements a Life stories of butterflies, toads,. na) ; ' ON CE NOELLE PEG EUEVE NE LOE LOE SAGO: Getting a Magnified Close-Up of a Group of Mosquitoes, Where Great Care Must Be Used to Show Accurately the Working of the Insects’ Delicate Weapons to catch one ot captives in so rare situation, operator is required to keep the ca: trained on the ject all night for days at a tir Mud-dauber wa tiny architects oj the insect vw which do th work of buildir night, were ph eee graphed while ~ a gaged in plasteri: clay home | neath the rafters an old barn. The lights used for photographing work were hidden and rays reflected to the spot by a seri mirrors. Trips to out-of-the-way pla have to be made to film interesting inse which could not be transplanted to closures for the purpose, and long ni vigils are kept with camera ready to cat the wary Ones in the midst of interest activities. For the making of a film c taining a motion-picture story of the n quito’s life, tiny glass tanks were fille with water and the larve permitted swim about the narrow space. When camera was set up and lights turned « it was found the heat of the lamps evap rated the water and sometimes caused death of the inmates. A system of r plenishing the reservoir with a drop two of water every few moments vw worked, and the drama _ proceed smoothly. Despite beliefs held by mai concerning the harmful habits of hundr: of insects the movies disclose them to innocent of most of the damage they charged with. Spiders, though found t be armed with hideous weapons, ha been proved to prey only on those inse which are said to be doing great injury 1 vegetation and animal life. age bes, hee ; “yy ¥

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POPULAR MECHANICS bs on Bottom of Cooking Utensils Utilize More Heat and Save Gas red v adding a series of metal ribs or vanes ; ating from the center of the bottom of uh- king utensils to the outer edge, engi- rs are reported to have found a design me ch may be made to save sixty per cent ; he gas used by a plain-bottomed ves- of of the same size. At a test with a rid pper container, this style absorbed near- it two and one-half times as much heat as ordinary pot. While this addition to flame contact area is especially suited en- cas flames, the design is said to effect responding savings with any kind of be el and can be adapted to a wide variety equipment. Wrench Adjusted by Push of Thumb without Bother of Screwing \djusted by merely pushing the lower up or down with the thumb instead of turn a screw arrangement, a wrench now on the market saves time and is said to fit tightly and without slipping. The jaws are placed at an angle of about twenty degrees, a varia- tion from the usual right-angle position, and when pressure is applied to the handle, the lower- “ta jaw band becomes stened in one of the niches on the back ot the wrench. It is claimed that adjust- ents can be made in about one-sixth of e time required with the usual screw rench. ing to Blown-Glass Trimmings on Gowns Produce Colors of Rainbow Covered with tiny bits of glass blown the texture of thistledown, “heart of ght” dresses have made their appearance London society circles where they have ttracted wide attention because of their luster and brilliance. The little pieces ct as small prisms, splitting the light in- to the primary colors and giving the gar- ent a dazzling rainbow effect, it is re- orted. Because of their light weight, they in be used on filmy evening gowns in reference to spangles of glass or metal. ee PE Fs 463 Model of Auto in Bottle Proves Skill of Whittler Complete in every visible detail, an auto- mobile has been shaped from wood and then cut into tiny bits and reconstructed Carver Holding Bottle Containing Automobile That He Shaped from Wood and Placed inside Glass inside a bottle by a Philadelphia carver. The car is an inclosed model and contains two miniature figures. It is sealed into its strange garage by a wooden stopper. Fasteners for Loose Chair Rungs Make Repairing Easy Holders that re- 3 quire neither nails nor glue may be used to fasten chair rungs or parts which pull out of their sock- ets. Once in place, the devices are claimed to hold the pieces permanently. They may also be employed to re- pair the handles of mops, mallets and brushes, which often work loose from their holes. The rung fasteners are made in several sizes to fit most needs, and can be applied in a few minutes without many tools or skilled workmanship.

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164 POPULAR Electric Truck That Hauls and Piles Reduces Warehouse Labor Heavy rolls, ticles quickly boxes and other bulky ar- hauled about and a combination elec- are stacked in piles with Truck Scooping Up Barrels from Floor, and Sketches Illustrating How Ele- vator Tips and Piles Them on End tric truck and elevator an eastern com pany has devised to save time and labor in the warehouse. The load is’picked up from the floor in an apronlike scoop which is revolved and raised to place the object in an upright position for piling. Both the hoisting apparatus and the truck itself are controlled by one operator, power being supplied from storage batteries. This ma- chine eliminates double handling of goods, the use of block and tackle, reduces the likelihood and the full available storage space. accidents enables utilization of of Dizzy Mice in Whirling Cage Used to Test Heredity Laws (wo hundred mice living a dizzy life in a whirling cage at the University of Min- recently completed the first ten years of a twenty-year service in an in- vestigation as to whether acquired char- acteristics are transmitted from parent to The mice the lineal de- of the group which started life in the rotating cage on Dec. 6, 1914. The test is being made to deter- mine whether Weisman, originator of the law that acquired characteristics are not transmitted, is correct. Dr. Karl Lashley, of the university and Prof. Charles P. Sig- erfoos, head of the biology department, Weisman right When the mice were placed in the cage they nesota, offspring are cendants original beliey Se first Was MECHANICS were dizzy for days and could scarce stand. Gradually they grew used to t motion and settled down to enjoy life a raise large families. The young born: inythe revolving cage, were accu tomed to it from the start and experien no inconvenience, b when taken out a placed on a stationa floor, they were wal bly as seasick passenger when they first reach land. Their childre: however, born outside the cage, were norm mice. The inmates o the cage have been kept down to two hundred removing the surplu from time to time, and i every case those remove have shown that the a quired taste for a revol ing home is not trai mitted to the offspri The experiment, ho. ever, will be continue until Dec. 6, 1934. l] Weisman law, if upheld, would prove t! negroes are not black because they ha been sunburned through countless ¢ erations, passing the characteristic o from father to son, but that they are a b race in Africa simply because they ar: adapted to the climate. as re! Air Pump Run by Fan Belt of Auto Makes Inflating Tires Easy Constructed so that it can be attacl to an automobile engine in afew moment an air pump has been patented to save time and labor 1: 1e blowing up tl tires. When it i to be used, it slipped over special bracket which remain fixed to the fram of the car and held against the fan belt. On the twelve - foot hose running to the wheels, in a venient positio: for reading, is at The pump is built o1 durable materials and has simple parts When not in use it may be taken off and placed in the tool box. con air pressure gauge.

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POPULAR MECHANICS Two Warships Scrapped by Treaty Furnish City Electric Power ‘urning swords into plowshares is a iliar figure of speech, but engineers e recently gone beyond this by convert- old battleships into machinery to light ity. The steel hulks of the cruiser rooklyn,” of Santiago fame, and the battleship “Montana” have been cut ' by gas torches and sold to steel mills. i ere they have been converted into cast- : and plates for the turbines and tun- reinforcement a power company uses upply electricity to San Francisco and rounding territory Siren to Warn of Prisoner Escapes Heard Three Miles electric siren, similar to those used iring the war to warn of gas attacks, is been installed on a tower in the yard the Eastern penitentiary at Philade!- 1 to notify prison guards and others in neighborhood of a convict’s escape. e signal, which can be plainly heard r a radius of three miles, is expected prevent successful flights of prisoners. warning the people in the vicinity of e institution at the instant a jail break discovered, watches can be immediate set upon the routes most likely to be | criminals, and ken by the , ursuers kept in- may w// be \ Copyright, Underwood & Underwood When a Prisoner Escapes, Electric Siren with Voice of Three-Mile Range Shrieks from This Tower tormed of the whereabouts of their quarry ind the direction in which he travels. 165 Magnifier Typewriter Copyholder Spares Eyes and Saves Time Eye strain and loss of time in typing are said to be avoided with an attachment for the typewriter that magnifies both the Inventor with Typewriter Fitted with Copyliolder, Magnifier and Front Extension Reading Glass stenographer’s notes and the page being written. It consists of a holder that can be spaced a line at a time and a reading glass on an extension bracket, so arranged that it can be swung to side when not needed. The copy is securely held behind a wide panel so that the characters are easily read and the operator need not glance to one side nor is she likely to lose the place. one Area of State Is Increased by River Depositing Soil at Mouth While other progressing in many lines, Louisiana boasts the distinc tion of being the only one in the union that is actually increasing in area. In the last twenty-five years, it is estimated, more than 1,000 square miles of land have been added to the borders of that wealth by deposits of the Mississippi An aerial survey shows that one sector ot the shore line is twelve miles tarther out to sea than it was in 1900 bays and lakes have been completely filled in and a number of bavous and streams have disappeared. Grass and now growing where a tew water was from five to sixty or more feet deep. The building of drainage systems and the clearing of lands have greatly in creased the amount of the silt deposits in recent vears, engineers say. states are common rivet Sey eral young trees are years ago the

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Time and Money-Saving Tools 0 a en Sones a= nn a + | Cores Are Lifted Out of Grapefruit Neatly and Easily with One “Bite” of Clamp Cutter at Left Holder at Right for Closet Hook, Con- tains Disk of Effective Moth Killer Spring-Catch Re- lease Fits on Win- dow to Hold Sash at Any Height Tight - Fitting Glass ‘“‘Cork’’ for | Milk Bottle, Which Replaces Paper Cap and Can Be Sterilized Fourteen-Piece Electric Cooker Has a Thermometer in Lid Here’s a Sturd Dust Cloth wit Built-In Roomy Glove to Keep the Hands Clean A Lifting Rack in his Capacious Boiler Makes It Easy to Remove Contents and Saves — | Off the ater | Two Articles Can Be Baked at Once in This Double - Compartment Glass Dish That Saves Extra Washing RS a —_— ed 466 Anyone wishing further information on devices described in the editorial pages can Qo

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for Woman’s Workshop in Home ia — = —_—___— —_ ST With Handy Rack, Electric Iron Makes a Small Stove and Can Be Used for Steaming Cloth Jug Pitcher with Gutter in Spout, revents Drips on Table Linen Cooky “Gun” and Some of the Molds for Cut- ting Fancy Shapes by Turn- ing Crank an nd Lock and Bur- A i glar-Alarm_ Bell Combined in Door Prop Cabinet Washes and Rinses Dishes in Large or Small Quantities a An Oven Shovel for Lifting Out Pots and Pans Saves Stooping Over and Burning Fingers Electric Egg Cooker Does Them Just Right with Steam, Can Hold Four Eggs and Requires Little Current Revolving Rack for the Oven Saves Burns and Trouble in Turning Cakes and Pies obtain it by addressing Bureau of Information, Popular Mechanics Magazine, Chicago.

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168 POPULAR MECHANICS Sidecar Attached to Child’s Cycle Enables Two to Ride at Once Two children can ride at once and, at the same time, have the fun of imitating Fun from the Cycle Car Is Doubled with Side Attach- ment That Holds a Playmate their elders in a cycle with a sidecar at- tachment similar to those on motor equip- ment. The toy is a development of the three-wheeled car that has been on the market for some time. It is sturdily con- structed, has rubber tires and wide pedals and, besides the sport of riding it, the child in the “driver's” seat gets the extra exer- cise of furnishing the additional power needed for carrving the passenger. Diamonds in Building Skyscrapers Replace Tools of Steel In planning skyscrapers and big bridges the solidity of the earth foundations is now tested by diamond-tipped drills which “feel” their way into rock and soil strata far beneath the surface, revealing the nature of the ground. Immense saws re- placing many of the hammers and chisels of stone workers are toothed with the gems in the rough, forming a cutting edge that cleaves blocks of hardest rock as easily as wood. The stones used for this purpose are generally of the white vari- etv, too tough for jewelry, and are mostly found as lumps in diamond strata similar to knots in lumber. Those employed for sounding the earth are black and are mined irom beds of rivers and strea When mounted in tools the diamonds ; fitted in‘ settings of steel and copp: rhough they wear down with use, t gems can be removed and turned to « pose other points. It is said the preci stones are now utilized in almost all chinery devoted to making the most c: mon articles of commerce and for direct cutting such materials as rubber, cott rolls, and substances of hard and gritt nature. Growing Scarcity of White Horses Perils Supply of Violin Bows Makers of violin bows are reported | coming anxious over the growing scarcit of white horses, the source of supply the long, smooth hairs used in the mar facture of the bows. The shortage is to be especially marked in Siberia Russia where the best supplies are « tained, and no suitable substitute for t hair has been found. Silk and metal ha been found satisfactory in place of ¢ strings for the instruments but cannot used on the bows. Heater and Strainer for Motor Oi! Utilizes Exhaust Gases To eliminate lubricating troubles in co weather, a western inventor has patent: a combination heating and straining tachment for the motor that utilizes tl exhaust gases to keep the oil fluid a: in working condition. The strainer is i: serted in the auto crankcase, and to tl] is fitted the heating unit, which, in turn connected to the manifeld with a lengt —€ Oil Heater and Strainer as Attached to the Motor Parts in Foreground of flexible piping. The exhaust is ap plied by simply opening a small valve a1 is said to keep the oil working easil\ through the filter screen and the engine in the coldest weather.

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POPULAR Kitchen Range Using ‘‘Near-Coal” to Reduce Household Expenses n a process for making a cheap and cticable fuel out of lignite, the woody ir-coal” material that is found in great indance in many parts of the United ites, and in a special kitchen range that burn the product, hope is seen for re ction of coal bills in the home and for substantial addition to the country’s resources. It is estimated that are more than a thousand billion of lignite within our borders. In ere natural state, it is moist and has ractically no value as a cooking fuel vineers of the bureau of mines, have discovered a way to carbot a special oven, producing a char al which 1s have the heating equivalent of anthracite. It can be made up into briquettes for easy handling and readily in furnaces quipped with special grates and teeding i A kitchen range that German in made to consume the so illed brown coal found in that country, is regarded as the best equipment yet devised putting the lignite charcoal to actual It is fitted with special sliding novel shape, an arrangement ir thorough ignition of the fuel, and is iid to have given satisfactory results un tests wwever, e if 1n said to urns stoves or evices entors have ervice rrates oO! ] (ler a @ Celluloid number of films for use in connection ith X-ray studies and so thin that 254,000 f them could be packed into a space an inch thick, have been produced MECHANICS road agreed 16% Breed Hens That Don’t Cross Road to Reduce Loss by Autos While the reason a chicken crosses the is still a mystery, poultrymen are that, with the increase in automo- biles, the trait, no mat- ter what its explanation, Testing Igni- | tion Point oe , Lignit ; Spread ! Special Grates, ar yee View of Exteri of Stove responsible for thousands of dolla 0 to them annually and that protec tive step are necessary One method has been t remove the pens to points distant trom a roads and keep the fowls within the in closures Anotl er solution. howevet! h been offered as a result of tests with d ferent kinds of hens The experiment showed that the road-crossing tenden¢ “oo arked srt-ate hreed +} n more marked in certain breeds than others and that raising only the varieti that “stay put” may greatly reduce the at nual loss by cars. Out of 100 flocks ot certain breed, only half a dozen chicke went across the road, while with othet all but about the same number tried t dash in front of automobiles to the opp site side. Some tarmers are alreat ing to the varieties that to remain on their own side P Way in an effort to cut dowt k llineg e mated-as high as one-fourth ot the flo

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Copyright, Underwood & Underwood Tile Traffic Sign at Intersection Stands Out Sharply against Dark Pavement as Plain Warning to Approaching Motorist Tile Traffic Signs in Street Paving Keep Bright and Attractive Large traffic signs of white-tile letters imbedded in the asphalt paving at a street intersection in Chicago are being used to replace painted signals to save repeated retouching made necessary by wear of weather and steady streams of vehicles. Since the surfaces of the material are smooth at all times, it is believed the mark ers attract the eves of motorists much more readily than the painted ones. A large crew of workers is necessary to replace the painted guides which are easily effaced by a few days of heavy traffic. It is expected the tile blocks will result in a great saving in materials besides affording more con- spicuous signals than older methods. @Byv 1926, 20.000,- 000 motor vehicles will be in service in the United States, according to pre- dictions of Thomas H. MacDonald, chief of the federal bureau of roads. Revolving Incubator in Its Frame with Moisture-Sup- ply Cup at Top of Lid 170 POPULAR MECHANICS Salvaged Sawdust Used for Walls Long considered waste product good fo little else besides use the circus ring or for pre serving ice, sawdust now being elevated to position of considerab) commercial importanc: by modern science Grinding and _ pressit processes have been di covered whereby this n terial is made into sma blocks suitable for floor ing, and mixed with bestos, it has been fou valuable in the manuta ture of wall covering f: both the interior and e terior of buildings. Maz mills use it for fuel alor with scrap boards a1 bark, and recently, e: periments have bee: made in cooking it dow: and extracting alcohol from it. Waste from the lumber milled in 1921 alone, it estimated, would have produced 185,000 000 gallons of alcohol, valued at approxi mately $100,000,000. Revolving Incubator Turns Eggs and Controls Moisture Turning eggs in a large revolving incu bator is accomplished by means of a1 electric motor which rotates the cabinet The trays are so arrange: that the contents cannot be rolled from their origina positions during the opera tion. Ventilation is regu lated by open ings on the sides and lower sectio: of the case, and can be changed when necessary without affecting the inte rior tempereture A device resem bling an engine grease cup, installed on the top, auto matically adjusts the supply of mois ture and is con trolled by the hu- midity of the air

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i. Ul ! ye MECHANIC ‘eUS2wZ How to Make a Venetian Swing By E. F. PRADER

Mj

the Venetian or gondola swing is an SPACER ~ BOLT old enough feature of amusement in | iwNeR ° foun Grn~ ublic parks, but it is seldom used in pri- | °'S* 4ji ™ ite grounds, although it is not by any |PIvoT a \ ieans hard to build. and is ideal for small %) e children, Built properly, it will stand any FZ , —< of | ae f s S A TONGUE - si A . fa OUTER \ ow . SPACER -~ KE _ Si DISK OUTER DISK REMOVED ASSEMBLED VIEW

A Novel Swing of Simple Construction, That Will Keep the Youngsters Amused for Hours at a Stretch; It Is Quite Safe for Small Children, and May Be Made of Any Desired Size. When the Swing Is Operated the Eyes Roll and the Tongues Loll from Side to Side in a Realistic Manne

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PATTERN FOR SIDES a’ IRON SHAFT ------- BEAM ------ SWING ROPES ----------- ROUND-IRON z Lf SUSPENSION RODS a /, arn Upper Left, Pattern of Sides; Upper Right, Detail of Sus rame Construction, and Right, Method of Fastening amount of abuse, and the high sides of the gondola or car make it safe for the little ones. The design shown in the il- lustration has, moreover, an interesting feature that makes it a prime favorite with the children. The sides of the gondola have four disks painted to represent faces, the eves of which roll and the tongues loll from side to side as the car swings. rhe construction is simple. A pattern for the sides of the car, which may be of any size desired, is given in the detail drawing. The ends are perfectly circular, and four disks of the same size as the ends are cut at the same time, from the same material. Four smaller disks, about 3 or 4 in. less in diameter, may alsé be cut. A large disk is fitted to each end, as shown, by means of bolts, with spacers slipped over them so as to leave room for the smaller disks to work between. The outer disks may then be laid aside, the smaller ones centered on the ends of the car sides, and pivoted to them, either with heavy screws or with bolts, after which the posi- tion of the tongues may be marked on them. Two holes for the eves are then bored in each of the larger disks, the lo- 72 POPULAR MECHANICS Pe FLATTENED END ~~ nsion; Center, Assembly Drawing, Showing uspension Rods to Connecting-Rod End cation and length of the tongue slots o:1 mouths marked, and the disks slotted. The tongues are simply strips of flat iron, bent and screwed to the inner disk and painted red. The eves on the disk are merely large black dots. When the swing is operated, the inner disks swing from side to side, the length of the swin: being governed by the length of the mout! slots. The car is suspended by means of fou 3g or Y%-in. iron rods. These are flattened at the bottom, bent to conform to the shape of the car, and screwed in place They are also flattened at the top, bent drilled and bolted to the cut-off ends o! two old auto-engine connecting rods, and these are mounted on a shaft of prope: size, secured by means of eyebolts to the crossbar of the swing frame. Collars should be provided at each end of the shaft, and on either side of the connecting rods, to prevent endwise motion. The frame needs no description, but the method of operating the swing may per haps be new to many. The top board ot the frame cross member is made as wide and as stout as possible, and from it two

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POPULAR MECHANICS are hung, in the center, and reach- own to the car. The ropes are ed, and the occupants of the seats, illing the ropes alternately, set it in and keep it going. Of course, the r apart the ropes are at the top, the it is to start and operate the swing, \dditional length of 2 by 4-in. lumber e bolted at right angles to the upper cross member, as indicated by the lines in the detail, and the ropes ed to the ends of this. Simple Toy-Balloon Trick amusing trick, which can be “put without any elaborate equipment, is ows: Obtain in advance two ordi- toy rubber balloons of contrasting and insert one in the other. When ted the balloons present the appear- of a single balloon. The performer announces that he is going to change olor of the balloon instantaneously. pierces the outer balloon, at a spot re there is a space between the outer the inner one. The outer balloon dis- ears with a loud report, leaving the in- balloon in full sight. The effect is ling and amusing, giving the delusion aving the balloon change color.—J. ph Alpine, South Amboy, N. J. Cornstalk Noise Maker or holiday and other celebrations ere the youngsters like to make lots of and e, a simple inexpensive noise lucer can be de from two ort lengths of ed cornstalk. e lengths should e solid joints oth ends and pulp is re- ved from both. en the blade of harp knife is erted under the iter skin just be- one joint and o slits are made the other end. all wooden edges are then serted under the rip thus formed, as indicated in the de- |. The strip on each piece is rubbed th rosin, as is done on a violin bow. rubbing the strips on both pieces of rnstalk together considerable notse can made.—A. C. Cole, Chicago, Ill. Double-Duty Cash Register In a country hardware store a small radio department was opened and a parti- METAL BRACKET AND PivOT BOLT { 2 r- j 7 VY Pivoted Table Enables One Cash Register to Be Used in Two Sections of Store tion erected to separate this section from the rest of the store. As the owner did not feel justified in purchasing a separate cash register for the new department, he devised the plan illustrated, which made it possible to use one cash register on both sides of the partition. A square section, a little higher and wider than the cash reg- ister, was cut out of the partition and the opening finished with casing. The bottom of the opening was desk-high, and a wooden panel was fitted loosely in this opening. A semicircular shelf was fitted to the panel at the bottom and was sup- ported by two iron-rod braces, as indi cated, and a peephole, about 3 in. in diam- eter, was cut through the panel just above the top of the register. This allowed a clerk on one side to see whether or not a clerk on the other side was using the reg ister. A hole was drilled in the center of the bottom casing to hold a socket for a strong pivot bolt, which was welded to a metal bracket, screwed to the panel and shelf as indicated in the detail. This per- mitted the panel to be swung around freely. It is a good idea to fit a bolt also in the upper casing to give the arrange- ment greater stability and permit it to be turned more easily. —L. B. Robbins, Har- wich, Mass.

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POPULAR Holder for Hot Curling Iron An electric curling iron is rather a nui- sance when used at a dressing table, as it cannot be set down on the table without ruining the varnish, and the same ap- plies to almost all other articles of furniture the in bedroom, yet the dress- ing table is the most con- venient place for making up the hair. By providing a simple holder for the hot iron all dan- ger of marring the surface is eliminatedand curling the The holder consists of a hair facilitated length of heavy wire, twisted and bent as shown in the insert in the illustration, and screwed to the under edge [ side panels, The it one of the as shown in the larger view. on may be dropped into the holder in an instant and is still convenient to the hand when needed. The attachment may also be fastened to the mirror frame Dr. i . S. Hall, McLeansboro, Ill. oO! r l R Getting Rid of Ants There are several ways to get rid of ant ls, and to discourage ants from making nests in the lawn. One method is to pour boiling water on the hill in sufficient quan- tities to penetrate to quite a depth. Re- peat this operation several times. An- other method is to pour enough kerosene into and around the nest to saturate the ground. Still another way is to scoop off the top of the nest and cover the depres- sion thickly with powdered borax. One of the best and simplest methods of dealing with ants is to beat the hill down flat with a heavy maul. One of my neigh- bors rid his lawn entirely of the pests in this way. He made a maul by taking a round piece of wood, about 16 in. long and 8 or 9 in. in diameter. Into the end ot 1 hil MECHANICS this block of wood, he inserted a handle With this maul he could pound the ground down firmly, and pack it so hard that « an ant would be discouraged. He a practice of noting the location o hills on his lawn, and right after shower he was busy with his maul. surprisingly short time there was no dence of ant hills at all. Ina dry se the same result can be obtained maul by pouring two or three pai water on the-hill before tamping. It pears that this method of treatment the ground so closely that the ant smothered. The advantage that is not harmed in the least b treatment.—A. G. Meating, Appleton is grass Ship-Type Ventilators for Auto For ventilating the front compart of his automobile a motorist adopted ship-type ventilator with success, in ing two of them on the cowl as illus- trated. In the wosttion shown, they allow cool air to enter the driver’s com- partment, and by reversing them, the air is exhausted, and the heat from the en- gine passes into the front part. Thus they will serve for both sum- mer and win- ter driving. The construc- tion is simple. The cone cut from piece of sheet brass bent and soldered at the edges. 1S a i m _h A length of brass tubing is soldered to t hole in the cone and a flange is soldere to it, so that the ventilator can be moun! ed in position on the cowl, as shown hole being cut through the latter tor t purpose. On the part of the tube bel the cowl, a coil spring is held by means a washer and pin, and the lower end ot t tube is fitted with a screen to keep out sects that may be caught by the drat

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POPULAR MECHANICS lle Easy Way to Clean a Clock en a clock stops it isa mistake to sup- at it must be taken to the work- for repairs. In most clocks unning simply because of an ulation of dust particles, which e bearings. It is not even nec- to take the clock apart toclean imple method, which has been to work well, is the following: piece of cotton wool in kero- nd place this in a small saucer, ir any similar small receptacle. put this in the case of the ; under the works. Close up the hes and at the end of 24 hours, ™ tton wool will be found to be ed with small black specks: are the dust particles brought hy the fumes of the kerosene. the clock and it will usually igain. Where the works of the are in an inclosed case, a few of kerosene should be poured igh a small hole in the metal ng and the clock turned about le so that the kerosene is well huted. A small quantity is suf- nt; too much will do more harm ~ eood. After a short time the clock 4 usually run again.—Edwin Tarrisse, : hington, D. C cases Vegetable Slicer ‘icing cooked vegetables can be done and quickly by means of the simple ce shown he draw- which | be made / nvone. It ‘ ists of a ooden about n. square, leof % by { in. mate- prefer- i hard- od, and a 1m b eF of gths of = SS YF: ae le piano ie re. These are bent at each end at right sles, for about 3% in., and strips of wood strap iron are screwed tightly to the . e over the ends. Ordinary drawer ls can be fastened to the frame to serve The method of using the ‘er is self-evident—James E. Noble, ronto, Can. : andles. Novel 175 Novel “One-Boy” Seesaw Most playground seesaws require two persons to operate them. Finding this feature objectionable, a schoolboy with an “One-Boy” Seesaw Operated with Aid of Sand-Filled Counterweight inventive turn of mind devised a equipped with a movable counterweight, which enabled him to operate it alone The counterweight consists of a box placed near one end,and two lengths of 1 by 2-in. wood, attached to the box and to a pair of handles, which are pivoted on seesaw } wooden the seesaw within easy reach of the oper- ator. The distance from the box to the center of the seesaw should be about the same as that from the center to the seat on the other end. A quantity of sand, ap proximately equal in weight to that ot the one using the seesaw is put in the box, and then by moving the box back and torth the balance can be readily changed, causing the seesaw to work just as if two persons were operating it. Phe counterweight end of the seesaw is boarded in as shown to confine the movement of the sand box Dangers to Gems As pearls consist of carbonate ot lime vinegar and other acids will eat away the polished surface in a short time Hot water is fatal to an opal, destroving fire and sometimes causing it to crack. Soap is a deadly enemy of the turquotse li a turquoise ring is kept on the hand while washing. in a short time the blue stones will turn to a dingy green Mrs Theo. Bush, Bay City, Mich.

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L76 POPULAR MECHANICS

= a _ - 41" ~ ‘ I WALL CLEAT BRACE... y aD Y eed -- ~) | if on re z © | WN ~fer- COUN TERSHELF H+--SIDE CASING t ! r 183-7 = Ss am t = r 3 ! r¢ 3 3*PLY PANEL z VENEER BACK *™ q T 2 2 ty 42 «© COUNTERSHELF qt’ | “aa See Ss | } i Y ey Yip ] r 4 — ' t t DRAWER > —+ , a SLIDE pas @ © ia * : v) a) | jo 9 2 ia: Tar | aD I K H | ® | ¥ I Y +» Y

SECTIONAL VIEW, CLOSET

Details of Construction of the Corner China Closet; Upper Left, Assembly of Cabinet Upper Right, Detail of Jambs, Casing, Fascia and Door Frames; Lower Left Method of Constructing U | per and Lower Doors, witn } | Dimensions; and Right, Sec | | tional View of Closet, Show- ing Positions of Wall and | Countershelf Cleats, Shelves Drawer, Head-Casing Brace

“ UPPER RIGHT y UPPE G DOOR and General Dimensions Sei J LOWER RIGHT DOOR DETAIL OF CONSTRUCTION OF UPPER AND LOWER DOORS

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FOR THE FZ, yy ie i Part IV—Corner China Closets ( )' dining-room cabinets, the corner — head jamb, or top of the china closet, are hina closet is probably the easiest the same as for the countershelf (shown to a house already built. Certainly in the detail), as is the case with the shelf ilize a spare corner, or, better, two, above the countershelf, except that the ina cases of the design illustrated, front edge is straight, while the other idd to the beauty and convenience of shelves are 1 in. narrower from front to ing room, even though it may con- back corner, as the doors close against buffet of the usual kind. them. is closet is 2 ft. 10 in. wide between The side jambs are of 1 by 4-in. stock, ide jambs, and 6 ft. 8% high to sized to 3% in. in width, and cut 1 in. e underside of the head jamb (the usual longer than the height of the cabinet. Lay ht of an inside door). If the doors them out for the spacing of the shelves, the room are higher or lower, the bearing in mind that the middle shelves of ht of the cabinet should be altered both sections line with the crossbars of irrespond. The top of the counter- the sash doors. Dado them % in. deep and f, in any assemble the e, i 3 . shelves with e the floor. the jambs. Lay e drawings the assembly, side cas- face down, on s 3u% in. blocks on the le, but if floor, or some sible, thev other support ould be of capable of hold stvle and ing it solidly th used in without twist, rest of the and brace the ym trim. shelves so that ‘lue up the they are per elves, cutting pendicular t o em roughly the front edges hape from of the jambs 12-in. pine, and square reinforcing with them. Fit e joints with one of the rugated fas- pieces of panel ings driven veneer, 26 in. to the top by 7 ft., against bottom, the back edge ‘cording to of a jamb and € position of rip it to width e shelf above Nail it solidly below the to the shelves ne of vision. with four ih e dimen- An Attractive and Usetul Addition to the Dining Room That Takes penny and _ ons for the Up Little Space and Is Easy to Build penny finish 44

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178 POPULAR MECHANICS

nails, spacing them 2 in. apart. Remove he detail gives the method of setti: the braces and fit the other back panel in bevel square tor the angle of the joint place, allowing the rear edge to extend tween the curved and straight sectio: past the first piece, and nail the second the fascia. The backing segment through into the first. from 2-in. stock, or two sections of material, and nailed in place unde 4 countershelf, against the upper rail and glue the fascia into place, showi:

margin on the shelf of a scant % in t ¥ fit the straight pieces afterward, whe va the casings are in place. * Two brackets, laid out as shown, ar nailed in place underneath the shelf abo the countershelf, and are set back f: the front edge of shelf and jambs A short length of 34 by 1%-in. neckn eof rounded on the end, is tacked underne forming a bead. Drive the nails from : back through the jambs and into the | from the under edges of the brackets > : 305 "| The cabinet is now ready to set DETAIL OF DRAWER the baseboard with the point of a sa a chisel 2 ft. 2 in. from the corner of Cut two drawer rails of 1 by 2-in. net room, and remove the pieces. Stand pine, 2 it. 10 in. long, and tack into place’ cabinet in the corner, and by mea beneath the countershelf. as indicated in wedges, thrust between the sides and the elevation and the countershelf detail plaster, plumb it both wavs, after The bottom of the upper rail is exactly 3'4 = making it solid by means of 1 by in. below the top of the countershelf, and cleats ab« the top ol the lower rail, 75 in. below. - ; / the head } Bore through the jambs into the ends of .. Fas and nail the rails for two 3¢-in. dowels, and nail = ~~ 2 the wall fast to hold the rails until the glue is dry. z - placed Nail and glue 1 by 2-in. stiles between the a faces of rails, making the width of the drawer i jambs space 2 ft. 6 in. Put in the lower frame a. be but rail with dowels, 2 ft. 6 in. below the top farther f1 of the countershelf hia, Senet To stiffen the countershelf, glue and measured nail 1 by 2-in. cleats to the backs under it, the plan and fit the center cleat, | by 3% in. net, the front gluing it to the shelf and toenailing the SQUARE POR FASCIA JOVNTS the widt front edge into the upper drawer rail. of the cas The curved fascia is built up of two to be used. If the distance is greater thicknesses of 3¢ by 2-in. net pine, glued not hesitate to remove enough plaster ft together and clamped to a torm while wet behind the cabinet to allow it to vO ba

MATERIAL LIST c three h 1 r lra side | € three-ply f 1 n | lraw ‘ l iy Zi fir, S45, sanded l l it l-edge nec l j pine fir, S4S, sanded 1 ‘ l ne 14 | | l l l } pine S4S. sande . 1 1 P f S48 eet DS j s ts D. S. glas l 17 it l l r t S45 ance + parr se ’ itt to mat ces, | I e or f S45 hinges inded l gla l € I ( 10 ) 1 piece l | | it f , fr g catche S4S, nded a yw cat < 1} ¢ tt r S4S 1 lh. six-penny finis | 4 I ur-per finist ils 1-ir P ld in. « ite hy in " ( st t iterials i t l l I ! uild t

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erly. Before casing, nail blocks into triangular space between the jambs ills for backing. Should the plaster egular trim the back edge of the cas- permit the front to be nailed back

POPULAR MECHANICS 479 holes before rabbeting for the glass. Cut the rabbet 3g in. deep, leaving % in. of stock for the glass to bear against. The muntins, of 34¢ by %4-in. net pine, half- lapped at the joints, are secured the stiles and rails by means of brads. The double-strength glass is put in each sas! é to in single sheets, and retained by small moldings or strips of wood. In hanging the doors, line the upper

COUNTERSHELF OF £ 3-PLY h, insuring a tight joint on the under by beveling the back edge. Make a ection beyond each casing of % in., nded off to the profile of the front. The d casing, shaped according to the lay- in the illustration, is nailed against head jamb and a cleat set between the ll cleats, and is well braced by strips of 2-in. pine nailed behind and bearing inst the top. Fit the straight ends of the fascia inst the curved fascia, allowing a pro- tion of the ends bevond the casing edge ual to its projection in front. Reduce thickness of the cove to ™% in. and fit tround under the fascia. Build the doors according to dimensions en in the drawing. Bore the dowel

os AIN INTO | VENEER, WALL AND CENTER AMB % ) CLEATS PX3g°NET } A Se ee _ BACKING SEGMENT \ {— 34 ~ aieecimoniieuneaall a roy = i 7 : = er ™ 35) 7 a t : at * iz : wapl s Sa i Sap = roe 30" +7 << a F Ye o ‘. BOTTOM-DRAWER RAIL,1X2. | TURNED FLAT. SLIDE 1X2 DETAIL OF COUNTERSHELF Fic.4 ight and true. Show a margin on jamb of % in. it the neckmold against the upper

10——|_—s LAYOUT OF HEAD CASING | Fic.3

[| _- LENGTH OF NECKMOLD wt 4 yea LAYOUT OF BRACKET | Fic. 2} ee —-

| ' ' ZA

he top hinges and the lower e1 of the lower hinges with the inner edges of ends of t the rails, allowing them to project about Y% in. Build the drawer as shown in the detail, inclosing the bottom of %-in. panel veneer with the sides, since it could not be slipped in afterward. The ends and top of the have a '%-in. % in. bevond the body, smoothly rounded for neatness. By taking icing the guide between the lower drawer rail and the back corner, and the guide strips on the bottom of the drawer, it will slide easilv. Fit the baseboard and shoe front of the lower rail. sand cabinet thoroughly, and it is for the finish. front flange projecting care in pl two %-in mold to the the read V

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180 Novel Sliding Gate On farms where high fences are used, a sliding gate of the kind shown in the draw- It can be almost ing will prove to be convenient. made from materials available ’ Useful Sliding Gate Suspended by Flat-Iron Hangers on Rail Made of Pipe everywhere. The rail is a length of % or 34-in. pipe, supported at each end by an el bow, a short nipple and a flange, the latter being securely screwed to the post. The gate hangers are made of flat iron, screwed to the gate and bent over to slide easily on the rail. Grease is applied to the rail ev- ery two or three months, to reduce the friction and permit the gate to slide noise lessly. For large gates, it is advisable to provide a stop on the outside, near the bot tom, to prevent them from swinging out ward in a strong wind—Dale R. Van Horn. Walton, Nebr. How to Design a Water Rheostat It is seldom that the average experi- menter gives more than a passing thought to the proper design of a water rheostat. The usual method is to use large plates in a container and add a sufhcient quantity of salt or acid until the proper current flows. The results often unsatistac tory, as the solution heats quickly, and may even boil; this gives a resistance that changes in value with the change of tem- are POPULAR MECHANICS perature and is not conducive to good sults in experimenting. The proble: designing a water rheostat resolves it into a question of the size and kind plates, the density of the solution to he used, and the kind of chemical to be en ployed. The maximum handled by a water rheostat depe: among other things, chiefly upon the amount of electrolyte in the container. It would appear that the energy absorbed wotld be limited by the radiation surface but calculations on this basis do not chec! well with results. To simplify the description we will sume that we wish to construct a rheost for an are light and have on hand a lars: porcelain jar from an Edison-type batte: as a container, and iron plates. The cu- bical contents are a little over 422 cu. ir When used indoors without special cooli: the capacity of the rheostat should be li: ited to 2 watts per cu. in., thus giving rating of 2 times 422, which equals 844 watts for the rheostat. Some voltage dr across the rheostat must be assum: Taking this to be 80 volts, the amper: passed by the rheostat can be calculat: by dividing the wattage by the voltag drop, resulting, in this case, in appro mately 1014 amperes. The allowable may imum current density for the plates is amp. per sq. in. The plates must then at least 10 sq. in. in area, but, since ther is plenty of room, we may use plates 5 i: in diameter, giving an area of about 19.5 sq. in. This reduces the current densit per sq. in. of plate, and consequently r duces polarization and plate resistanc The upper plate is perforated with hol made with a 20-penny nail, and is fastened to an adjusting rod by two bolts, one either side of the plate. The lower pl is left plain, atid a rubber-covered w connected to it. Having determined the mechanical sign of the rheostat, the kind of soluti to be used, and its density, must be det« mined. The chemical is a matter of jud ment. We may make use of sodium su phate, sodium chloride, or copper sulphat with iron plates. Where carbor. or le plates are used we may employ sulphur acid. A simple rule for calculating t! density of the solution in percentage as tollows: Multipiy the maximum di tance between plates by any one of t! following constants: Sulphuric acid .08 sodium chloride .25; sodium sulphate 45 and copper sulphate .90; divide the result by the maximum voltage drop per sulphate does not polarize the plate current that can Since co}

Page 135

POPULAR ected for the rheostat. This solu 1 found to give the is made up an results. lowing the above method a rheo iny other purpose may be con with full assurance that the de do the ‘work in a satisfactory It is only necessary to bear in he relatior ship of the various fac- hich may be listed as follows: The absorbed depends upon the volume the area of the plates mined by the current, which should ceed 1 amp. per sq. in. The vol- op is determined by the maximum e between the plates; where this ts by the | the container the ot the solution is varied to obtain yper results—Thos. W. Benson, phia, Pa electrolyte; size of Washing the Car Chassis under the than anvwhere else ar. A simple and etlicient method ioving this is to use a er of the kind shown in the drav rovided w under ble. It a concrete floor and good drain- nd consists of two lengths of “%-in pipe, perforated with a number ot The pipes are arranged along ides of the garage and connected to The distance between mud and dirt collects “hassis mm tne ¢ Stationat iter pressure 1 can be installed in any garage ] 1 noes supply. Sprayed against Underside of Car Chassis Re- moves Mud and Dirt pipes should be a little greater than tread of the car so that the spray will rike the underside of the chassis. Thus water will reach parts that are nearly iccessible when using a uers, Washington, D. ¢ MECHANICS hose.—G, A. 481 A Well-Ventilated Summer Kitchen In the ordinary farm house the kitchen is the most used room and during the Summer months it sometimes be ome unbearably hot as all the cooking is dor Open-Air Summer Kitchen on the Farm Has Good Appearance and Maximum Ventilation there. lo provide relief, ti sun and dining room of the kind shown, whi bee immer kitc!l is separated from the house, has found very convenient tor cook! y i 1also be u ed as a laundry It is abo 16 ft. square and has as many windo the sides as possible in order to pro maximum ventilation and light Che \ dows are hinged at the top as ] opt outward from the bottom, two-pie folding braces being used to hold thet open; the braces are hinged at the cente on the underside and the end it tl hinges are cut at a slight angle, so tl the weight of the windows causes thet to bow slightly do nward as s] Screens are, of course, provided the inside to make the interior fly-proot outside may be painte hite t é the wood and impr t ea ‘ Thawing Frozen Radiators When putting in the the night, a moto lh frozen near the botto d around t petcock Not wishing to thaw it with | water, or to steam it out in the mornti he bent the overtlow tube so that it directed against the « motor, until steam develope: te was thus ejected on the petcocl nd short time the frozen part was thawe so that the water could be drawn Care should be taken not to bend the tub SO as to choke it o1 teritere t Operation ol! the tat Richard ¢ Mass Glouceste!

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Treadle for Hand Grinder Small bench grinders are often rather inconventent to use because the worker cannot hold the work with both hands, trtipll Simple Treadle Attachment Increases Usefulness of Hand Grinder which is often necessary and always best. The drawing shows a simple attachment that permits one to run the grinder with the foot. It consists of a treadle pivoted at one end to the floor, as shown in the detail, and an iron connecting rod attached to the treadle and to the grinder crank. his attachment is easily made by anyone and well worth the making.—G. A. Washington, D. C Luers, Testing Painted Woodwork lo test the purity of paint on woodwork shave off a splinter with a knife and burn it with a match or hold it over a gas flame until it burns brightly. Then remove and hold it over some 82 POPULAR MECHANICS Fishing with an Umbrella A handvy net for catching killifish can be neatly folded and readily « in a fishing-rod bag, may be made covering an old discarded umbrella with mosquito netting. Although p1 ly intended for catching “killies” b ing a few cracked clams or mussels center and lowering in shallow wat: over ft. deep, it can also be use catching the beautiful silver-banded ing by baiting it with a few piec: shrimp. Tie the pieces to the fram: the center and suspend the net in cd: water near a sod bank. When codfis! flounders are running, the net, baited shrimp, can be used from the end dock. One must be patient, allowin; net to remain down for some time b drawing it up, but when the fish are ent at all, the number taken at one will more than make up for the time in waiting. An old umbrella is also very conver to have along when “bobbing” for e night. String a ) \ dozen or more worn strong thread, winding them up int ball and w rapping the thread well ar: the mass. Let the ball sink to the bott and when a bite is felt draw in the line shake the eel off into the umbrella, has previously been hung over the sid: the dock.—John D. Mayer, New Yorl Substantial Poultry Hopper Unlike most grit and feed hopper: the poultry house, the one shown i: illustration is set high above the floor. p: mitting the fowl to walk under it. To. able them to reach the contents easil broad platform, about 8 in. wide and ; ported by flat-iron braces, is attache it, about 4 in. ab the floor. per is made of dark cloth or pa- per. If pure lead divided into fo paint was used, little silverlike beads, which are metallic lead, will drop off the charred splinter. Totest any paint to be used, dip a Sliver into the paint, and after it is dry, test it the same way.— S. A. Pease, Wau- watosa, Wis. Galvanized-Iron Poultry Hopper Is Sanitary and Can- not Be Used as a Roosting Place compartments above the trou birds from roost on the edge. 71] rod should placed so close the side that birds lose their | ance if they try perch on it. vanized iron. It The hi the top is hing An iron rod ri from end to e1 to prevent restl +

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Making a Trapeze-Artist Toy By H. H. SIEGELE A CLEVER and interesting toy, which will please any 44 child, can be made by anyone in an hour trom a tew pieces ot scrap wood, some nails, wire and a piece ol string. The toy, which is made to represent a trapez performer, can be made to go through a variety of tricks and will afford a lot of enjoyment to the youngsters. It can be made as sturdy as desired, to stand up under rough handling, and it can also be decorated in various ways with very little trouble, so that it will make a very good all-around addition to the playbox. The dimen sions given below apply to the original toy, but, of course, they may be modified to suit the Sm taste of the reader. lhe base is a block of wood, 3% in. thick and 3% in. square. In = = PAI 8 TERE HEH MENT Made from Scrap Wood Nails, Wire and String, This ver Trapeze Toy Will Amuse the « ngsters for Hours at a Time center of this is nailed an upright or of the legs, and at the points where these . &% in. thick by 14% in. wide and units are pivoted to the body lwo larg long Across the top of this ts holes. to take the string to be used, are da crosspiece, 34 in. thick, 1% in drilled at the tops of the arms, in In ind 3 in. long The body is cut from with each other ¢ in. thick It is best to obtain a The arms and legs are then pivoted to of material large enough to make the body by means of the wire, looping the dv. arms and legs. and to mark this latter at each side so that it cannot come 1 in squares so that the pieces can out. A small block of 16-1n. wood d out on it in the same manner as tacked or glued between the arms at the in the detail drawing. A piece 4 top, as shown in the detail lwo in. in size will do li wood as large of wood, 16 in. long ind 1 in vide his cannot be obtained a piece of paper next cut. These should preterably be be marked off in l-in. squares and hardwood, such as hickory, about : : , ; hi nol 17 Iyle parts laid out on it at one time, when thick, but if this ts unobta ible : hic v used in y can be cut out and pasted down to wood, \% in. thick, (this was used smaller pieces of wood to serve as original tov) can be used lwo hole les for cutting. After they are cut, a drilled in the top of each, correspor ling ill hole to take a piece of thin wire ts to the holes in the top of the ari ind led at the bottom of each arm, the top the strips then nailed to the crosspiece

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LEGS, 2 REQUIRED POPULAR MECHANICS 2x7 xi" BLOCK. 1} \/ i 2 3 INCHES BASE -i" SS —_ — E : } } i Put 16" ni =| 5 ——— $$ — — - — |} ee 2 REQUIRED Layout of the Body, Arms and Legs of the Trapeze Toy, with Details of the Supports and Base: Note Espe: How the String Is Run through the Holes in the Top The method of suspending the figure is shown in the detail, and the string must be run through the holes exactly as indi- cated, else the toy will not perform. Now, by grasping the bottom of the upright strips and squeezing them together, then releasing them, the figure will swing over Holding Stovepipes Securely Horizontal sections of stovepipe have a tendency to sag and may even slip apart. This trouble can be prevented by tying them together with a length of wire as shown in the upper part of the illustration. The joints are first pushed together and a hook is driven into the wall just above the stovepipe. The wire is tied to the hook and looped around each joint, being pulled up tight while progressing. This is continued until the elbow is reached, Twist Neat Methods of Holding Horizontal Sections of Stove- pipe Together Securely the “trapeze,” turn somersaults, and form a number of other tricks. The figure can be painted flesh co with black or red trunks, or may even bh: provided with cloth tights, glued on. Thx remainder of the toy can be painted any manner desired. where the wire is securely twisted and « off. Another method of preventing | pipes from getting loose is to punc! small hole, at each joint, through the te: scoped ends of the pipe sections on the side, and insert a flat-head nail in ea hole, as shown in the lower detail. Method of Distinguishing Extension Bells When there are two or more bells use in the same room, some contrivan is needed to indicate which one has be ringing. Often an annunciator is us¢ but this imposes some additional load « the telephone line and must also be res: each time a bell rings. A simpler pla: which has been used successfully, is attach a light coil spring to each bell cla; per. The spring is placed in a horizont position and can easily be fastened by few drops of solder. When any bell the room rings, its spring is set in vibr: tion and continues to vibrate for ten « fifteen seconds after the sound cease: One can then tell at a glance which be! has been ringing.—R. L. Campbell, Bel! ingham, Wash.

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Handy Window Rai window mathroom just behind the tul t nearly impos ithout standin: difficulty w \ providi ion It consi sind show sts POPULAR ser often . which to the ls b sible in as eliminat ng a lift n in the ota lever about 2 it long the side of the win + and provided wit] 1 f e dog at one end, which i notched bar screwed to . 3 otches oT PTOOVEeS MECHANICS a » \ And Hoo dddeeee

Electric Lighter for Water Heate:

t J apart and are cut : . P icksaw. The dog is cut i teel platetothe shape : . : 7 n the insert. It is piv- le ver at the \ notched : ‘ | COIL i na 1 the cente oO ne ant a ; I tl SPRING A. * otch, at the other end, a lt re driven into the ~= ) t the s ing ot the ot e SO ATE = \ b bus] c provided . ICAle ¢ i 315 O ge Hi if r \ ¢ bet y n | ’ = Ss in J —— ~ « > Pp no c ¢ 8B SHING r is 1 Cé 0 ‘ tiie can } Br tore | | eric ( i | { ~ ~. hye onta ed LEVER , , ‘ ounde = see re te nate ssible Window behind Bathtub Opened by Means turner, ¢ ect Simple Lifting Jack ‘ t te ‘ 7 spark lump , i Stroke ( ToT eac! note ‘ ‘ Hari lose the indo the action is re sed, and in tl case it is the lower th of the d that pushes the 7 @ Quicklime add n. lithe sa is not counterweighte: portion of abou device \ ill rt work 1). () W ood deodort n if 1 through cheesec Bel ) Wit] ty +y i ) 1 ce | + 1 » 7 e ) ‘ e i () t ‘ et ¢ ¢ ) Nz pat 1 _ ; in 14 e , the () 1

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486 POPULAR MECHANICS CARRIAGE HANDLE f. SCREW STAIRS Baby Carriage Stored Conveniently on Side of Stairway Storing the Baby Carriage In twg-flat buildings the tenant often finds the hall too small to store a baby carriage. The problem of storing it can easily be overcome, however, if the stair- way is of normal width. The baby carriage is usually just half as wide as the stairway, and it can easily be held to one of the treads by means of a _ hook, securely anchored in the tread with a screweye. The illustration clearly shows how this is done. ‘The carriage is stored a few steps above the first floor and this allows plenty of space for people to pass. Of course, where there are three or four flats above the first floor this practice can hardly be used, but where only the owners of the carriage use the stairs there can be no objection raised.—H. Jackson, Chicago, Ill. A Bacon-Rind Auto Bearing When a tourist burns out two connect- ing-rod bearings, 40 miles from a town where repairs can be made, it is quite a temptation to ride on slowly, risking greater damage to the engine. Being in such a predicament recently, and not hav- ing any repair parts so that I could do the job at. once, the most promising emer- gency repair which occurred to me was to use a piece of ordinary bacon rind as I well remembered how hard and tough this became when cooked. A strip, about 2 in. wide and 12 in. long, was hammered flat to drive out as much grease as possible, re- ducing it to a hard, tough piece. This cut into a number of smaller strips large enough to replace the babbitt burne: from the bearings. They were carei fitted in place and the connecting-rod c drawn up tight. After replacing the pan and the oil, I started the motor a no knock of any kind was noticeable. drove to the nearest town, but not find the condition any worse, decided not to; in “a new bearing there. Since that drove the car over 5,000 miles with thes: bacon-rind bearings without experiencin: any trouble—H. G. Borland, Ashevi North Carolina. Blowtorch Stand Blowtorches are often used to melt le and other metals in ladles, but, as no p: of the torch is adjustable, it is sometin rather difficult to play the flame directly u der the ladle. To eliminate the necessit of using blocks and shims to accompli this, a simple adjustable stand, attach: to the bottom of the blow- torch, h as been found satisfac- tory. It con- sists of two disks with brackets in the center, the latter be- ing formed by cutting the metaland bending the cut parts up ats teas angles, as shown. A bolt, sleeve and wingnut complete the a sembly, holes being drilled through tl brackets for the bolt. The lower dis must be of greater diameter than the uj; per one, so that it will hold the torch any angle it may be set. Small lips left on the edge of the upper disk are ben: over to grip the bottom of the torch. The fixture can readily be made by anyone and the details of construction are given i: the illustration. —C. Homewood, On tario, Calif. @ When the gas line on the truck or ca: springs a leak, it can be repaired tem porarily with a strip of cloth heavily coated with vellow laundry soap, things that ar« obtainable anywhere.

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POPULAR MECHANICS 487 Driving Nails Straight Foiling the Auto Thief amateur doing odd carpenter jobs \ simple and effective method of foil- d the house will sometimes drive in ing auto thieves or joyriders is shown in o that it comes out of the side the drawing. Drill and tap a hole in the ibout halfway in. The usual prac- intake manifold for a 3-in. pipe or tube to pull it out and try to drive it in _ ht. Instead of that, I merely take f punch and, just as the nail point to come out of the side, I put the on the point and give it a blow he hammer, which starts it back e wood. Then I hit the nail alter on the head and on the side until riven in entirely. In this way I, so eak, drive the nail around a corner ut other damage to the woodwork he small impression that is made on ide by the punch and this can very be remedied by filling the hole with Geo. H Mansfield, Cuyahoga Ohio. An Easily Made Stencil —_——a. \ tee Reomeet ~4 WOODEN PLI simple stencil ior lettering barrels, ¥ ca and packages can be made from a Secret Opening Permits Excessive Air in Intake Mani- e ot wire scree This is cut to the fold and Prevents Engine from Starting ‘| size and placed flat upon a smooth ; , . . , ov ; . mnect not ine or ice, and the lettering 1s painted on it fitting, and connect a kk _ Or pipe or melted parattit fhe paraffin hard tubing to extend back to the dash. The quicklv, cementing itself to the wire open end is flared out a trifle to receive a stencil is used in the ordinary way wooden plug made to fit in snugly. When background receives the paint and the plug is in place, the engine will run ettering is left in the original color of © 2OTMally but when the plug is removed, hox or barrel. As the paraffin can be %° much air is admitted to the cylinder ted from the screen for the substitu that no combustion can take place and of other lettering, it is a good idea to therefore, the car cannot very well be run g, ag ich a steel-wire frame and handle, as Of on Its own power, li, however, the e1 gine is started by excessive use of the stREEN choke, the firing will be so erratic that the PARAFFIN thief will be glad to abandon the car in a block or so. Of course. the plugged end of the tube should be located in an un noticeable place behind the instrument board.—Richard P. Cole, Paterson, N. J Improvised Scratch Brush While painting my house I tound it necessary to use a wire scratch brush dl as | could not buy or borrow one 11 1\ neighborhood, I had to make a substitute A piece of ordinary screen wire was rolled up tightly and a piece of pape vound around it to serve as a handle The wire end was found to be just as good as a1 sily Made Stencil for Lettering on Boxes and scratch brush, \n advantage of su ' Barrels brush is that it can be made any conve! ient size. It can be made anywhere, as own, to make the stencil durable and screen is always available, and it « be sy to manipulate—G. E. Hendrickson, fashioned in a few moments.—Otto T. C \rgyle, Wis. Colonius, Kinlogh, Mo.

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*, i e “YSolderin te" for th e Slome PLleehanic ~ by~ James Sate i Beevers is nothing difficult or mysteri- soldering, hard and soft, but, as the « ous about the art of soldering. Onthe sions in which hard soldering (br: other hand, the mere possession of a sol- and silver soldering) is required ar dering iron, a generous supply of solder, the home are few and far betwee and a large tin of flux does not by any simple soft soldering will be consid means guarantee a good job. All that is in this article. necessary to insure good work, however, Soft solders are composed of tit is the observance of a few simple rules, lead, alloyed in various proportions, « together with a little common sense. nary tinner’s solder being half-and There is no knack to be acquired, and a_ that is, composed of equal parts of ti: few practice jobs, bearing in mind always _ lead \s the melting point of these the rules, will soon make anyone a sol- ders runs from about 330 to 440° F., t dering expert. There are two kinds of may be easily worked by means of a made of copper- the so-called solde1 iron—heated to a degree somewhat ab the meltjng point of the solder. ~ Upper Left, Filing the Point of the Iron Bright; Upper Right, Tinning the Iron; Below, Sweating a Patch over a Hole 4358

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POPULAR MECHANICS 489 J — Soldering irons are made in various Also, when these fluxes are used, the apes and sizes; also plain, gas, alcohol work should be thoroughly washed after- | electric-heated. Good work may be ward, or rust is likely to develop. Finally, e around the never use an acid me with a plain SOLDERING FLUXES flux on electrical wir- lering iron, heat- METAL FLUX ing, as corrosion is on the gas stove sure to follow: use a gasoli IRON CHLORIDE OF ZINC in. rosin-core sol- vith a gasoline | Si SAL AMMONIAG ne Pee ate 2 rch, but by far the nasties iaieiae der, or a paste flux . t tool for all- cease} SAL AMMONIAG specially prepared for und home use is | pine cop) CHLORIDE OF ZING this purpose. e electric solder- | ZINC (Nem HYDROCHLORIC ACID Now for the actual iron. Phis can tt... ROSIN soldering. 4d he first plugged into a CHLORIDE OF ZINC thing to do is to “tin ket anywhere in the iron. Light the e house or garage, thus avoiding the _ stove, if using a plain iron, or plug it into cessity of frequent trips to the kitchen the socket, if an electric one, and, while reheat the iron. The alcohol-heated the iron is heating, hunt up a small piece on is also a very useful tool, where elec- of tin, brass or copper. The inside of the city is not available. flux-can lid will do if nothing else is avail- lhe prime requirement, in every sol- able. Clean a spot on the surface, about ering job, from the simplest to the most 2 in. square, with emery cloth, and drop a implicated, is cleanliness. The parts to little flux on it. If using a plain iron, don't soldered or joined must be chemically let it get red-hot; it should be just hot ean. To do this, it is first necessary to enough to melt the solder well. When it emove all rust, scale, oxide or dirt from has reached this point. remove it from the e surfaces to be soldered by means of a__ stove, hold it as shown in photo No. 1, and e, scraper or emery cloth, using this un- brighten the point, on all four sides, with the surfaces are perfectly bright. The a file. Ifthe latter is not at hand, rub the ean surfaces are protected from oxidiz- point on a sheet of emery cloth until it is and the flowing of the solder over clean, then rub it back and forth on the em aided by the use of a flux. clean surface of the tin on which the flux or all-around use in the home, the was spread, photo No. 2, applying some iste fluxes sold in small tin containers solder to the point while doing this. Don't e about all that is required, or a supply forget the flux. The point of the iron will acid-core and rosin-core solder. The become evenly coated with the solder, and tter is a hollow rib- —_.. it is then ready for on of solder filled work. When re- ith an acid flux ora ux made of melted - rosin, dispensing ith the necessity | | too hot, or the point ior a separate flux. | will “burn” and must il For the man who = | be retinned. When | J heating the iron afterward, take care that iw doesn't get ikes to tinker heated to the proper INCORRECT , iround the home ° Cares degree—a little expe hop, the paste flux rience soon enables nay be supplemented by a few others, the user to determine this—the point may vhich have been found better for particu- become black or discolored, but the tin ar uses. These fluxes, and the metals for ning is unharmed, and a dip in the flux vhich they are particularly suited, are list- quickly removes the discoloration. Most ed in the accompanying table. The chlo- good electric irons need no attention in re ride of zine, often called “killed spirits,” is prepared by dropping zinc (not galvanized- iron) clippings into hydrochloric acid until the acid is “killed,” that is, until bubbles cease to arise from the. zinc. The acid may then be strained and kept in a glass- stoppered bottle. One caution is neces- sary in using this flux, and with straight hydrochloric acid also. Don't allow any of it to remain in an open container near tools, or they will become badly corroded. gard to the heat. and only require a dip in the flux now and then to keep the point bright. Ordinary soldering is simplicity itself To solder a leak in the seam of a pail, for example, the dirt must be cleared from around the leak with a scraper of some kind until the surface is as clean as it can be made. Too much emphasis cannot be laid on the cleaning in a job of this kind, as a small spot of grease or dirt will not

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190 POPULAR MECHANICS Upper Left, Polishing the Work; Upper Right, Applying Flux to Bracket before Tinning; Lower Left, Tin- ning the Bracket; Lower Right, Sweating the Bracket in Place

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POPULAR MECHANICS 491 the solder to flow into the seam, and cause a lot of trouble. Apply some to the surface, heat the tinned iron, flow the solder into the seam, apply- the end of the stick or ribbon of sol- to the point of the iron. Don't at- pt to stop the leak by dropping some lder froma ght of a few hes onto the t where the leak be. The metal ind the solder st be warm, ly as hot as the er, in order to seittorun. In- d, it is a good to heat the rk before apply- the solder, if can be done— not too hot, or e surface will dize, and must recleaned. The oper way is eep the iron ssed against the 1, so that it ; the metal, and the solder to point so that it s into the seam. dering a hole in pail or other utensil is difficult if the e is so large that the solder will not dge it alone. In that case it is neces- to patch the hole. Cut a patch of e same metal large enough to cover the le with plenty of overlap. Clean and lish one side of the patch, and also the ot it is to cover, and coat the cleaned irfaces with flux. Tin both cleaned sur- es with solder by rubbing the hot iron er them, feeding solder to the point: en apply some more flux, lay the patch er the hole and hold it down with some ol as in photo No. 3. Now, by running e hot iron slowly around the edge of the tch as shown in-the photo, or holding on top of the patch, the solder on the nned portions will melt and unite. This called “sweating.” It sometimes helps feed a little solder to the iron while unning it around the edge of the patch, the hot solder causes that on the tinned urfaces to melt quicker. A similar procedure is followed in sol- ‘ring one piece to another, as in the il- ustrations showing a small bracket being oldered to a pan. Both surfaces to be oied are polished with emery cloth, photo No. 4, and spread with flux as in No. 5. Each is then tinned, No. 6, and the bracket placed in position and sweated to the pan as shown in photo No. 7. Small pieces may often be joined by tin- ning the parts, spreading some flux on them, placing them in the proper position and clamping them with a pair of pli- ers or tongs, then holding them over the flame of the stove Or over a Bunsen burner un- til the solder melts. They are then quickly removed, and allowed to cool, while still keeping them clamped. Many amateurs, when making joints in wiring, in their endeavor to make a neat job, coil one wire closely around the other as shown at the left in the de tail drawing. This makes a neat con- nection, from the standpoint of looks, but a poor one elec- trically, as the close coils do not permit the solder to flow around the joint prop- erly. It is better to make connections like those shown at the right. Here the coils are open, and the solder can make a good electrical connection between them. Re- member also, an acid flux must not be used for soldering electrical connections. When soldering some parts that are hard to hold together, it is usually a simple matter, once they are tinned, to wire them together while the iron or the gas-stove flame is applied to sweat the joint. A word of caution 1s necessary when using the flame to sweat joints. Don't apply the flame right at the joint, as it is apt to “burn” the solder, or oxi dize the parts. Apply it some distance away, and let the heat run up through the metal to the joint. This also makes the heat easier to control. A few nails driven into the bench or worktable around the parts to be joined will also aid, in many cases, to hold them while applying the sol- der. It is hardly possible to give specific directions for holding work of this char- acter, as every case is different, but the reader wili experience little trouble in de- vising ways to hold the job.

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192 POPULAR MECHANICS Letting Chickens Unlock Door Poultry seems to do best, generally speaking, when they can choose not only the hour for roosting but also the time to sally forth in the morning. With the doors of the chicken house open during the day, they fro in when they please, but, if the house is closed overnight, they must wait in the morning ledge the previous night, just before t ilarmer goes to bed, and in the mornin; when a hungry hen steps on the trigg to reach the corn the additional weig pulls out the nail and the weight ope the door. Fig. 2 shows an adaptation this device designed for houses where t floor is Cc oO} siderably abo the level of t ground outsid In this case t door is hinge at the botto: and, whe until someone lets them out. It is an easy matter, how- ever, to pro- vide an auto- matic device that will per- mit the fowl to open the door themselves. The door is fitted to slide upward, and a screweve dropped, fort a cleated i1 cline to facil tate entrance and. exit. \ stiff piece clock spring fastened to the sill inside an bears agait the door that, whe closed, it will be under pre is driven into sure. A scre its top,to which eve is. driv is attached a into the door length of stout a p on the insid cord. The latter ie — —— 2 {~t - PULLEY at the top, an runs up over a ia srr sae —~ COND | directly abov pullev mounted qi “ - NAIL | this two mor above the door, | eal SCREWEYES are screwed and a_ heavy RP ageecone GRAIN, | into the wall o . ~GRAIN f counterweight t! 4 . = .f | -the hotise is attached to A} | a nail is dropp: the other end of i} ; — DOOR ~ through — thes: rf OPENED ‘ the cord. About \ Ph a e - eves to lock t! , Nig! oN ae) ‘ ; a foot away z\ ye door, and tl 7 1 —— oe ~ . od . . . trom the door, ie, =» WEA AZ, 4 nail is tied t and directly in ! WRG the end of front of it, the nae ‘“triogoer”’ j Two Simple Devices That Enable the Fowl to Oven the Door of izgeger 1s : . the Poultry House in the Morrtings mounted. This consists of two pieces of wood nailed at right angles to each other, as shown in Fig. 1, and pivoted between two stakes driven into the floor. The trigger is set, with the part nearest the door in a ver tical position, and near the top is nailed a small ledge upon which some kernels of corn may be scattered. From the top of this piece a wire runs to a nail pushed through the screweye in the top of the door and into a hole drilled directly be hind the screweye in the side of the house. When the trigger is set, the weight, dragging on the nail, keeps the door shut The corn is, of course, scattered on the fre. 2. = length of cord running over pulley an down to the trigger. The latter in tl case consists of a single board, and th corn is placed in a small trough joinin the tops of the stakes to which the trigge: 1s pivoted Cleaning Developing Trays For a tray cleaner use a solution cor sisting of water, 32 0z.; potassium bi chromate, 234 oz., and sulphuric acid, 3 oz. Pour it into the tray to be cleaned an swab with a tuft of cotton. The solutior may be poured off into a bottle and used several times > a a

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By C. M. 1) EADY-MADE cabinets are generally i\ finished in dark-brown colors to har- nize with the usual type of living-room niture. For variety’s sake an orna- ntal design in attractive antique, in nese lacquer, or in “tiffany,” will be nd to give a pleasing effect. Recently | was given the job of refinish a cheap-looking mahogany-stained net, which the wished to.im e. I suggested an antique finish in and proceeded to do the work in the ving way: The entire surface was sanded down with No. 0 sandpaper then dusted off well. thin of white she were applied to nt the mahogany stain from “bleed- i hrough the finish paint). shellac will not ent this trouble, so it 1s advisable to owner lwo ] : ici showing t etimes two Coats ot Left, Applying Flat White Paint; Above, Stippling On Design through a Stencil; Below, Pouncing with a Cloth Ball to Give Mottled Effect pply an extra coat or two, especially over e edges and corners, where bleeding is ost apt to occur; each coat must be oroughly dry before the next is applied. Vhen the last coat of shellac is dry, it is nded down with No. 0 sandpaper. It ould be kept in mind that the smoother the surface, the better the final finish will Redecorating the Radio Cabinet OWENS be; the shellac should fill every crevice and scratch, and all dirt particles that stic] to the surface must be removed by sand ing. Two coats of flat white paint, colored a little with raw sienna, are then applied. This paint must be thin enough to per mit it to be applied evenly, but not so thin that it runs. If, after the first coat of flat white, the mahogany stain bleed through, apply another coat of shellac to the through prevent stain from bleeding subsequent coats. After the dried, the stencil white ha Stencil flat done. second coat of work is of all kinds can be purchased at large paint usually a catalog containing the will be sent stores; various designs free to any- 4 ?

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14 POPULAR MECHANICS 1 be requesting one. Colors ground 1 must be taken to give a good even coat ire used tor stenciling, a tew drops ot do not attempt to take too much vart lapan drier being added to assure quick on the brush, smearing it on one pla | Irving. The stenciling job in this cass with the idea to brush it out evenly. 17 consisted in putting a simple black border can be done with paint, but varnish ts ver 1 the top and side 5 Oo! the box al ra acen tacky, which makes if hard to sprea ter design to match \ light pencil mark Only a little varnish should be taken « is drawn along the edge to help in laying — the brush and this applied with quick, hl the stencil on st ight he stencil is strokes. If anv hairs come out ofthebru held securely with two fingers while the onto the surface, they should be picl lor is stippled into the perforations with out at once with a pin or sharp knife bl i brus] in old shaving brush will serve or they will dishgure the whole job. Ait the purpose well) he stencil paint must the first coat of varnish is thoroughly d be heavy so that it ill not flow under rub it down with powdered pumice st the stenci causing blotches and runs and rubbing oil This can be done wit Onlv a little of the paint 1 used on the piece of telt cut from an old hat ( brusl just enough to cover the white must be taken not to rub too hard o ; paint distinctly Care must be taken to the corners and edges or the rnis| . old the ste ( | it | SO that it will not be cut. Che dust is the n cleaned ott wit! ; slip smearing the work If this h ippens rag saturated with turpentine india é remove the smear with a clean rag, satu ond coat of varnish applied, proceeding rated ith turpentine, and then wipe dry. the same way as betore \iter this is d (he mottled or antique effect is pro the surface is « eaned off and polished duced by pouncing the surface with a cloth good furniture polis] ball or dry brush after a darker color has If the cabinet is entirely unfinished been applied vhich in this case may be the start, paste wood filler is applied burnt umber or raw sienna, thinned with _ fill up the pits This is always necessa turpentine. This is applied evenly all over in case of mahogany, walnut and o the surface, and while still wet, the cloth Che filler can be obtained in different c ball is pounced over it to give the desired ors. Of course, a light color should effect lhe color should be left heaviest used if the finished color of the cabinet | around the corners al d center to be light, and a dark filler if the fit Varnish is next applied, after the sur is dark. The filler is thinned with tu face has dried thoroughly. \ sood erade pentine to forma paste al dis brushed of clear varnish should be used—not a thickly, left on the surface for a few n damar varnish. The work should be done utes and then wiped off. After 24 hou in a clean room where there is little or no chance of dust and dirt getting on the var . nish while it dries Usually amateurs experience trouble in not be | ing able to keep the sur- I ce clean. Varnish rut l dt es | € "6 Left, Rubbing Down First Coat of Varnish with Pow if dered Rumice Stone and Rubbing Oil: Right, Radi it Cabinet Finished in Antique After It Was Completed when the temperature 1s ibout SO to 85 the first coat of .shell ic is applied ry . \ good 2-in. brush is a handy size for ap stain must alw ivs be used before appl plying varnish on a radio cabinet. Ca ing the fillet

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POPULAR MECHANICS 495 Correct Grid Leak Is Important The apex of one is cut away to permit at- taching it to a bracket, which serves not only as a stand for the projector, but also as a mounting for the sound-reproducing One of the smallest parts that enters » the construction of a radio receiver is grid leak, and in connection with it the d condenser. As usual with small de- ls they are given little attention. It surprise many to know that the vol- e and clarity of reception depend on correct value of the grid leak and the 1 condenser. The grid current is de- mined by the number of negative elec- ns that are attracted to the grid from filament. The negative charge on the d sometimes piles up to a point where practically stops the flow of plate cur- nt; the grid leak relieves this situation d frees the imprisoned electrons, pre- nting the tube from choking. This re- lires a grid leak of correct value for the be used. The grid leaks now on the market vary efficiency ; some are correct in value ac- rding to their rating, others nearly so, d many are found to be inefficient. hen selecting the materials for building ur set, always demand the best; this ap- es especially to grid leaks and grid con- nsers. Substituting different grid leaks various resistances in your receiver will ten be the means of improving volume d clarity of reception. Each type of ibe requires a different type of grid -leak 1 grid condenser. The values of these rts are usually supplied by the manu- cturer of the tube, and will be found in e literature accompanying the _ tube hen purchased. A good variable grid ik is recommended by some authorities; nother plan is to have several fixed grid eaks varying in value from one to five egohms and you will be able to select he best one on trial. The variable grid leak is a valuable in- trument—if the average user would be ontent to let it alone once it 1s adjusted to the best value for the particular tube eis using. Once the leak is properly ad- usted it should not be touched unless the tube is changed. Horn Is Replaced by Cones in Loud Speaker Of unusual design, pleasing to the eye is well as the ear, a new type of cone- shaped loud speaker has,.as its outstand- ng features, intensity of volume with little lirectional effect. Instead of a horn, the nstrument has a projector within which the actuating mechanism is contained. The projector consists of two hollow cones with their bases cemented together. A New Loud Speaker That Enables the Audi- ence to Hear Equally Well from Any Direc- tion mechanism, which is of the balanced ar mature type. The armature of the mag net unit is connected with the apex of the outer cone, causing the projector to vi brate with the current impulses. Connecting Phones to Amplifier There is a right and a wrong way to connect phones to an amplifier. If the are incorrectly connected they become de magnetized and soon lose their sensitivity The simplest way to find which is the best connection, is to plug the phones in at the last step of amplification and tune the receiver to the loudest possible sig nal; then remove the phone caps and lift one edge of the diaphragm with the finger until it clears the edge of the shell. When the phones are connected in one direction, you will observe a stronger pull than when the connections are reversed. When the connections are so placed as to obtain the greatest pull on the diaphragm, ‘put a mark on the phone terminal that was con- nected to the plate of the tube. There- after always connect the marked terminal to the plate.

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| | How to Build the ‘Popular Mechanics’

ee - —*, ° i “Oigh. eve 7 Superhere odie Whi ¢ clear the lower Cs i eTs ive i Ta _ : i . re , 4 1 a‘ parfrt oT t fi ¢ i hh. oF |. Bas i i rheostats . } are so plac

that the oT and plate te mounted on the tront panel \ small cut - out will also be n minals are close as po sible to the re spective 1 and plate ter minals of tl tube socke which allo short and dire ecessarv at the eft front end oft the sub panel to clear

he back of the push-pul switch: the si

oO this ca leads. Thi ead be «ks precautt ermine: upoO should be taker issemblv. \s with all tl mble the transfort O inst ers in regard t lent ( the plate a1 ibpane | grid leads. T! ea scriber to tuned - stag ocate t transforn 101 ng hole er is pla ce All ( the next to the ft th ‘ C2 audio -fre ve drilled wit! quency trans 1 No. 27 dril former. O Be careful to this transforn locate the vari er will be foun three litt] mountin brackets place under the tet minals; the 00025 - m fd fixed condenser is connected ous instru ments on the subpanel exact- 1 as shown in the lavout. Vote that two three - gyang sackets are used. The first socket unit at a ar > the left is for across the grid and tilamen . Osts on two ol “ie rm View of the Finished Receiver; the A and B-Batteries May Be I 4 the second de Housed in a Cabinet, Making a Very Attractive Installation these brackets 496

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POPULAR MECHANICS hird bracket is also placed under the terminal and provides a mounting for ide of the .0005-mfd. grid condenser he 2-meg. grid leak, which is mounted ps attached to rid condenser. assembly is v shown in \ p . { iring diagram. | soldering

497 the lead from the negative-A line to the positive of the C-battery can be taken di- rect, eliminating the binding post if so desired. This completes the instrument assembly of this section on the sub panel. A brass shield is then placed between this sec tion and the next,

under every inal on trans- ers and sock- indalso put on all fixed nsers not fur | with them. e lugs can be ed to the con r by means POINTER rt brass ma- veel ies PAPER rew Never DIAL --._ ler directly to fE BAKELITE ¥ condenser of DISK --~~ type, as the ‘rom the iron lestroy the ef- CABINET of the con- TOP a LOOP JACK-” e .5-mfd. by- condenser is ed flat under second detector- socket, with e terminals to- rdthe front panel, king connection to the lever of e potentiometer | the negative-A line. Directly back e audio-frequency transformers, at le back edge of the subpanel, mount the brackets for supporting the terminal strip. ese are made of 46 by % by 4%-in. brass ps, turned up lin. at each end and drilled hown in the detail Part I. Fasten them he subpanel with brass machine screws. e terminal strip consists of a piece of hy 1 by 7-in. bakelite. Drill this strip r the binding posts and engrave the vari b-battery voltages as indicated:on the p. Place soldering lugs under these ts and mount the strip on top of the FLEXIBLE LEADS -<-— Details of the Mountin Cabinet, Showing the kets with short brass machine screws l-mfd. by-pass condenser is connected the B-battery from the A negative 6 90-volt posts. At the right of the minal strip is a binding post on the bpanel; this post is for the positive lead the 4'4-volt C-battery. A lead from the rative A-battery line is also run to the se of this post under the subpanel. This nding post is for convenience in wiring;

LOOP BINDING POSTS . MOUNTED ON SUBPANEL™ of the Loop on the Top of the onnections to the Binding Posts as shown in the photos. The shield is made of 26-gauge sheet brass, 6% by 6% in. in size. The long side is bent at i\* |] “CENTER TAP j ON LOOP

right angles 4% in RD-TIP - Ghme mua rom the end, to tTorm a mounttit base for the shield two holes are drilled through the flange and the shield is se cured to the sub panel with machine screws. A soldering lug placed under of the machin« screws on the ut derside of the sub panel for the put pose of grounding the shield. This ap plies to both shields and the tinfoil shield on the back of the front panel is grounded by means of lugs under the brass supporting brack- ets that go under the subpanel. The lugs are all connected together with one wire which runs to the negative binding post of the A-battery. This is done after all circuit wiring has been completed. We will now consider the middle sec tion; this embraces the three intermediate frequency transformers and their respec tive tube sockets, also the 4'4-volt C-bat tery, the 1'4-volt C battery for the poten tiometer and the negative lead to the fil ment posts of the intermediate-frequenc) transformers ' short one The filament posts of the transformers are ith one all connected toget and this lead is taken to the negative post of the 1'4-volt batter The binding post s] (“-batteries in bus bar, iown between the t ) this section is for the nega tive lead from the 4!'4-volt C-batter which goes to the filament posts of tl two audio-frequency amplitving trat formers. The 1%-volt of a cell from a flashlight battery, and (C-bhatterv consist

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500 POPULAR 1% bv 34 by 3%-in. strip « drilled at each end ot double binding screws secure mounted ona bakelite. Holes are the strip tor mounting posts, of which the lower leads from the circuit, and the upper ones hold two short lengths of bus bar o1 support the dry cell and also make the positive ar egative connections ; small nut s soldered to the zinc shell at the base ot the W ¢ No. 6-32 machine screws to brass MECHANICS soldering lugs on this unit are nun as shown in the diagram. Care shor taken when soldering the wire to mall terminals; do not hold the ing iron to them anv longer than sufi to make a good connection. At of the coupling unit is a “6 by % by 2 trip of bakelite, on which is m three binding posts. This strip is by 6-in. bracket form a 1 j in. bast in. at the top. Th ing-post assembly is forthe purpose necting leads tre loop jack and cord Lip jac k mounted top of the net to their re as shown in the loop connection dr Green silk-covered lampcord is vet for these leads; they should be ju enough to allow the lid of the cabi: be opened, and can be bunched tl a small cabinet. The midget variable condenser is « table - mou ed ona x by p- shown so as to also bent tor the three flexible 1 i cabi spective screweve near the hinge o the cell, holding the cell in place bv means of the bus bar. The positive contact is made at the other end of the cell by countersink- ing a very small hole in the brass positive terminal, just deep enough to allow the bus bar or screw to support this end of the cell and make a good contact. A hole is drilled through the cen- ter of the bakelite strip for a 1l-in. brass machine screw, ; to support the entire unit above the sub- panel. The unit is then mounted in the position indicated Che intermediate-ire- quency transformers are mounted on the panel in the position shown, to allow the grid and plate leads to be made as short as possible. Next comes the second shield; this is exactly like the preceding one, and is mounted in the manner, except that it is placed far enough back to clear wave-length condenser. This com- pletes the assembly of the middle or inter- mediate-frequency section rhe third, and last, section to the right contains the coupling unit mounted on the subpanel, and it will be noted that the Same the type and is | on the subpan: a point direct tween the osci condenser and wave - length densers on the { panel. Whet dering the lea this condenser stitute lugs for copper tabs and der the wire t lugs. At the of the coupling Above, View of Left-Hand Section of Subpanel; Cent Middle Section, and Below, Right-Hand End of 5 panel, Showing Location of Shields

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POPULAR MECHANICS 501 ther of the 1'%4-volt batteries: this the cord-tip jack When the loop jack ted in the same manner as the 1 mounted, no metal should come in contact battery previously described. There vith the lid lt the reader desires to log 5-mid. tixed condenser across this the loop there are extra papel dial chart this condenser is mounted onthe = furnished with the oscillator and wave unit \ th bus bar looped undet let eth condensers, and one ot these dial ble binding posts ca be tastened under the bakelite d e rear of the subpanel in this sec that forms the mounting for the loop jacl the sockets for the first detector \ disk of celluloid covers the dial and pre the oscillator tube; these are of vents soiling, and at the same time tend ele type and are mounted on the to hold the papel dial flat on the cabinet with brass machine screws, 1% the loop ierial can then be rotated 199 rhe oscillator socket is mounted and logged. When making the station lo reme right of the subpanel ind enter the call letters of the station, the letect ocket at the left of the the ive lengt then the read r O thre letector tube is of the oscillator condense ext the readis t ‘) it type: all the other the ve-length « ce ( ind ist the e instrument are of the position of the loop The loop is dire \ or C-301A type. This completes tional and helps materially in cutting out b of the oscillator and first interference lo mount the loop on t secTl \OD-1 cl pli go cut oft ] 1 OT T tilye te all the wiring possible on the hell of the plu nd make oO ylu é é ta ¢ the front pane 1), diameter and ng « to dl the ypanel to thie come flush with the top oft t Op lready mounted on the tront when driven into the latter; then d1 ind complete the wiring Use hole through it from end to end to take a ypper bus bar for the entire ci %46-in. brass dowel pin, 234 in. long ich nd cover with a good grade of black is fitted snugly into the wooden plug at tti’” tubing The leads from the the latter is then pushed into the loop points on the voltmeters can be plug This will then allow about 2 vith sn aller flexible rubber-co. of the brass pin to stick up above the top re if desired. of the loop plug ind as the e1 d of the loop -eep the negative and positive A-bat is already drilled to take a pin of this size leads underneath the subpanel and all that is necessary is to place the loop e together, so as not to form any in-- on the pin and push the wooden plug in on loops in the circuit. This also ap- to the loop jack. For those who would to all other leads Avoid forming rather not mount their loop on the lid of keep all grid and plate leads as short the cabinet, but prefer to have the rect a po ~ ble, and do not parallel separate a mounting base comes with t] e id plate leads. All wiring under the loop and this is provided with three double panel is run direct from point to point. binding posts to take the three loop lead that the machine screws that go If this is used, the three leads from t ugh the subpanel do not touch the binding posts mounted on the subpanel | bottom of the cabinet. The brass must be brought out through holes drilled kets elevate the subpanel % in. above” in the rear of the cabinet This cor cabinet base, and this allows plenty ot pletes the loop installation. If desired for all screws and wiring to cleat pointer taken from an old rheostat can b ibinet base The instrument is no soldered to the bottom of the looy leted and ready to place in the cab plug to wv ork over the paper dial cab net to}! ry 1] { lo 4 repare the lid of the cabinet for mount the loop the loop jack by drilling a 34-in. hole Remove the loop, and drillholesthrou muuch the lid at a point just back of the the rear of the cabinet in ter, then cut a disk of “4s-in. bakelite, 3 binding post r the A and B-hatteri diameter, for mounting the loop Small hard-rubber bu drill this for the oval-head nickel used in the bases of electric table ¢ wood screws, as shown in the dia are shellacked into the hole he m, and also drill a hole at the back of not essential, but add much t center in this disk to mount a phone pearance of the cabinet Use fle le rt ach tor the center tap on the loop ber-« ered { ture ire for ¢ necti Ware t be drilled so that the cord the A and B-hat , im thes | ack cle thre loop jack lange Drill post he \ ratte ) t ( ) he -» | e throu the lid to cle SO-am t ¢ ] t¢ t ;

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502 POPULAR MECHANICS battery of either four 22)4-volt heavy-duty ment out tothe loop. This will permit B-battery units, or two 45-volt units. cabinet lid to be raised so that the midg: These are connected in series and tapped variable condenser and the rotor oj off at the first 18-volt positive tap for the coupling unit can be adjusted for best plate of the first detector tube and the sults under operating conditions. \\ plate of the oscillator tube: this will be these have once been set for maxi seen by referring to the checking diagram clarity and volume there will only be The 45-volt positive B-battery tap is for variable adjustments to make in tur the plate of the second detector tube and these are made with the oscillato1 the plates of the three intermediate-fre denser and the wave-length condense1 quency amplifying tubes. The 90-volt of course, the position of the loop in positive tap is tor the plates of the two gard to the ldcation of the station audio-frequency amplifying tubes. The received. The rotor of the coupling instrument is then ready for the tubes. and the midget variable condenser lake one tube and place it successively only require the first adjustment and in each socket, each time pushing in the not be touched again push-pull filament switch and turning up lo pick up a broadcasting station, t the rheostats: this will show if there is up the rheostats to a point where any error in the filament wiring and elim- can hear the tubes in operation, the: inates the possibility of burning out all the wave-length condenser at, say, the eight tubes. If the tube lights correctly, point on the dial. Rotate the dial ot all the tubes can now be placed in their’ oscillator condenser 10 to 15° on « sockets, being careful to put the C-300 or — side of its 30° mark; if no station is h UV-200 detector tube in the first-detector on this wave length, reset the wave-le: socket. Set the rotor of the coupling unit dial 5 or 10° ahead and follow the at the loosest coupling; see the photo for procedure with the oscillator conde: the approximate position. We are now as above until a station is located; rep: ready to adjust the instrument under op- ing this process over the entire dial re erating conditions. ing. If, after this tuning process, on Take the plug off the end of the loop _ still unable to locate a station, the { and place the loop on the extra base that may lie in the fact that the oscillator 1 comes with it; take three flexible leads is not oscillating. Turn up the rheo from the loop binding posts in the instru- marked oscillator and intermediate ir “A Marvelous Set! And It Seems Almost Too Simple. Why, I Believe I Could Build One Myself.’ This Was the Verdict of Mary McCormic, Famous Opera Star, on Viewing the Popular Mechanics’ Superheterodyne Eight, the Sensation of the Chicago Radio Show

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POPULAR MECHANICS 503 this is the third rheostat from the Instrument Combines Lamp, Receiver nd side of the cabinet when facing and Loud Speaker trument; turning up this rheostat ually remedy the trouble. Also turn \ novel combination of radio receive first rheostat at the extreme right and table lamp has recently made its ap the cabinet; this rheostat is marked pearance and lends itself nicely to the it also decorative tes as a scheme of the rheostat AA if Y 4 home. Che n it de- Wj \% lamp and re is the gf t 4) a | ceiver are made of fila- tu in one unit 7 t current the loud speal ed to the er is concealed tor and under the ed 1_e@- } ide Whet uency the shade Another tipped ba ra of de- t} r receive ining expo ed oF not I t, t Shade Tiy ed . o" oscillator Back and the Receive ult omp oscillat C ead Right , “ i detector o touch a Lamp two-step amp! d_ ter- fier. and , of the oscillator-tube socket wit] wave-length range from 250 to 700 mete ger; if the tube is oscillating, a dis The lamps are mounted at each side ick will be heard when the tet the instrument cabinet touched and again when the fin removed ' Special Unit Aids in Building Tuned Radio-Frequency Sets e instrument has been built ac to the construction details out in this article one will not have long luned-transformer radio-frequency am it for a station. Rotate the loop plification has until recently been obje¢ time to time, as this will often enable tionable. on account of additional adjust ns to be picked up that otherwise ments and the be unheard, as the loop is directional necessity of r the instrument has been checked using some properly adjusted for maximum re means of sta- take off the temporary loop leads bilizing or replace the loop plug on the loop prevention of e the cabinet and push the plug into” oscillation, loop jack, and plug the center loop most of which linto the phone-tip jack. Seethat the are not ap- plug makes proper connection in the plicable over if it does not, the wave-length con the whole ser will have no tuning value and it broadcast be noticed at once. If the loop plug range, and es too far down in the jack, use wash which accomplish the results with consid between plug and jack. sothat the plug erable loss in energy Now, however be of the proper length to make the tuned radio-frequency transit rect contact in the jack been made which 1s mounted on the hatt of the condenser, thus eliminating li¢ . ] ] ] } + Metallic Grid Leak Insures ce acca tin. aber ripe taag te Permanent Resistance + na ger beige ssatacet 4 \ metallic film of high resistance, which tained by means of another variable ctually annealed to a olass rod or tube denser, the requ red movement ot e feature of a grid leak recently plac ed is only a few degree the market. It is claimed that the re capacity of a volume control tance thus produced is unusually stable former is wound so that the re nee » the fact that the film cannot wear verv low, giving equal amplification over or become detached in any other way. the entire broadcasting rang

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504 POPULAR MECHANICS Radio Sets Affect Watches its shape. Line the inside of the ho coil, after removing the form, with an jd Thousands of London watches have piece of plush or velvet, to protect been attacked: by a new disease, which watchcase, and cover the outside wit jewelers have named “broadcastitis.” strip of thin genuine or imitation leat They report that about 40 per cent of To make a neat-finished job, bevel their repair cases are due to magnetism, edges of the base. drill holes for the « as compared with five percent beforeradio nection from coil and lamp socket, gr: became popular. the underside of the board for the « \merican jewelers say there has been necting wires, and, after wiring, cover th no appreciable increase in magnetic bottom of the base with felt. troubles in this country, the average re- In operation the plug is screwed into th maining around five per cent. They sug- lamp socket and the current turned gest, however, that the English jewelers’ The sixty-cycle alternating current set diagnosis is probably wrong, and that not a magnetic field in the coil. Pass broadcasting, but listening, causes the watch through it and the watch beco: trouble, the watch becoming magnetized the core of the magnet. Take it out, ; while the owner is tinkering with his re- the magnetism is removed. ceiving set. If you have alternating current in your home, a simple demagnetizer can be Two Unusual Loop Aerials ilt with < vad base, r te. us ae ; ; . Pat - German manufacture and contains s ' cai _ features not found in other loops. It . \ said that, owing to the auxiliary fol arms at the base, it is possible to tune the receiving instrument with this loop, a can be folded into several shapes, offeri various degrees of selectivity. It is wou with litz wire, and the arms keep the wir taut while folding. | The loop shown in the lower phot: | radically different in design. Built int shape of a balloon, or large ball, it claimed to be very efficient and differs f1 the standard type of loop in that it is n directional. It folds up in the same m ner as an umbrella.

of extension cord and plug, and a coil of ordinary magnet wire, the light being connected in series with the coil to furnish the necessary resistance to protect the line fuses. Prepare an oval form, 3 in. across the face, 2% in. high and 3 in. long, and about this wind a half dozen layers of the magnet wire. shellacking the wire to give Above, New German Loop Folds into Various Shapes, Enablin; : wo :. ee the User to Tune the Set with It; Right, Novel Loop That I! it the necessary rigidity to hold Non-Directional

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Things to Avoid By J. D. Pettevae is nothing very hard about the building of a radio set, even an eight be superheterodyne. There are a few re instruments to mount on the panel nd baseboard or subpanel, a few more ires to bend and joints to solder, than hen building a simple 1-tube set, but, th a good diagram, that is all the differ ce. However, when building any set, m the simplest to the one that appears e most difficult, there are a t must be taken finished job 1s few things into consideration, if be satisfactory th from the tandpoint of ap arance and per rmance. One ould not merely diagram oft instrument and llow it slavishlyv. ourse, there re sets in the dis which e instructions ust 1 { eliv. ke a ic g of be followed if the oper ng results are to e satistactorv, but such case the usually this. But in sets the ;ome- irections pecity verage T iTts Call in Building Sets ATKIN times be rearranged to improve the looks. Care should taken, when thi that the leads are not made longer, as a set that looks well will not in the end prove satisfactory if it does not perform well The thing of first importance is to keep be doing the leads short, especially: the grid and plate connections, and, when attempting to redesign a set, many different arrange ments of the instruments must be tried until the happy result of good appearance and short leads is attained. Perhaps the best method of show Ing VI it should not be done in building a radi et 1s tO give a col rete € ¢ ( Reinart eceive hown he ful page tion about Live best ¢ 1! ) o do come t Ion tf ( é t h | n " e 4 | e sé anv re ¢ r built b teurs 1 ¢ cou T é ist le ( | thi ¢ present +] :

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506 POPULAR MECHANICS 1 Connection at Condenser; Fig. 3, No Contact 5. Sockets Not Screwed Down; Fig. 6, Lead Viev of Rea f Set to Fig. 1, Rheostat Shorted; Fig. 2, B Tran forn ’ " } “ + ; i € 4 1S i Soldere Fi

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POPULAR MECHANICS 507 d arrangement of the first attempt have been clamped under that switch-lever iring was atrocious; leads run- bushing locknut was merely slipped over every way but the right one, poor the bushing, and held in place by the shaft cts everywhere—in fact, it is a trib collar, thus making only an edge contact the excellence of the circuit that anda very poor one. In addition to this, e1vel orked at all. We will take while the switch lever arms had at one of the most important errors as time made good contact with the switch re illustrated in the enlargements points, as was evident from the marks o circies e first place, the owner could not nd why his batteries ran down so He was using WD-11 tubes, and ents of these tubes do not light so that he did not notice that the tube was burning all the time, the set was in use or not. Upon gation, | found that the rheostat is tube had been connected so that tch lever, when it was supposed to ; e “off” point, really made contact the other lead, forming a direct path e current instead of shutting it off. is shown 1n Second- the latter, now they did not; as shown in Fig. 3, light jar sufficient to use the re- er to lose ume, and en to lose the tion entirely. of course, inted to a se contact mewhere. As atter o! tact, one otf the arms was about Me in. from the points. No wonder sig nals had ceased to come in! Although sol dering lugs had been provided on the terminals of the transformer, these had not been used, but instead the bus bar had been looped around the terminals. This would not have been quite so bad had the terminal nuts been tight. but, in con mon with every other ter minal in the set,they were loose Qe Fic j J 5 0 the co | tion of the tube socket In addition t the tact that soldering lugs had not been used on the ter minals, the socket vere ove, Front of Old Panel and Cabinet; Center, Front of Cabinet in Rebuilt not even screwed di eiver ; elow, View of Rear of Rebuilt Instrument, Showing Neat and ‘ the hase In explar Compact Arrangement ) THe Vas Pidlia tion of tl the builder ere Vas nota tight contact anvwhere said that he ad ot an cre tne the set, all were loose, but the most proper length, and he thought, t didnt nspicuous example ot a poor contact matter, anyway. It is true that the ab as the one shown in Fig 2. This is the sence of the screws would not cause the onnection from the switch lever of the’ set to stop functioning, but it is an evi econdarv to one side of the tuning con- dence of carelessness, and good radio set denser. The copper washer that should cannot be built if care is not taken to do

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5OS POPULAR good a job on every part of the set as within the builder's power In Fig. 6 is shown a typical lead, the one running from the tube socket to one side of the This takes a bend upward, then one toward the panel, another toward the left, toward the panel again and then down and into the con- denser terminal. This lead could just as well have been taken straight across the base from the socket to the condenser. As it was, the course it took made the lead about twice as long as necessary. Figure 7 shows the panel layout. panel was cut but the tuning condenser ‘| he tor the cabinet, builder made it do anyhow, there too narrow by making the iob look sloppy even at first sight. When drilling the peepholes in the panel he had not supported the latter soft wood, and that the drill broke through nd knocked a large chunk from the edge on a block of the conse quence was of the hole even if he had not supported the panel properly he could have drilled these holes from the front, and then, if the edge of the hole had chipped, the front would not have been marred. With rea and the [ block of soft wood under the panel at the point where it is to be drilled, there is no excuse for the holes chipping at sonable care, use ola the edges or breaking out. In Figs. 8 and 9 is shown the instrument as rebuilt. It will be noticed that the panel arrangement is symmetrical, and looks very neat. All the binding have taken from the front and mounted on a neat terminal strip at the rear of the base board, and the phone posts have been re placed by a pair of phone-tip jacks. The set of six posts at the left side of the orig- posts been inal panel were for three pairs of phones, and, besides making the poor appearance of the panel worse, this method connected Phones should be best results, and is is a simple thing to do by means of the phones in parallel connected in series for ome double binding posts. There is there- no need to spoil the appearance of the panel vith extra phone posts The condensers first used were of the hook tvpe, and \\ hile these vere vefry good tuning, the position of the dials could not be logged for vat 1 1 since three turns of the dial were re- or tine 1oOus stations, quired to run the condenser from mini mum to maximum capacity Two good standard 23-plate condensers were there fore substituted for them, and, as these had a 100-to-1 vernier ratio, fine tuning was not. sacrificed Instead of drilling 2? holes in the Pp inel for the switch points and stops inductance switches w ere used, MECHANICS which necessitated drilling only three holes. The old coil, which was. bad wound and mounted on a thin fiber for: was thrown away, and a new coil, wou on a substantial wooden form, fixed in upright position behind the inducta: switches. The leads from the coil to t switches were thus made as short as p sible. The rheostats were mounted on panel at the top, with a filament swit between them. No peepholes were drill as, with the tubes employed, it 1s alm impossible to see when the filaments lit through holes in the panel. The new arrangement of the tube so: ets and transformer is such that the pl and grid leads are very short and dire A little thought applied to the job b starting the c ] will often save time in the wiring of the strument, as well as add greatly, in m cases, to its ethctency his set, | would formerly ! fore Onstruction of the hardly do more than br in local stations on the phones, has plenty of volume to ope! ite a loud spea on the same stations. Even if the oper tion of the set had not been very mu improved, there is no question of the provement in appearance, and this alo could easily have been achieved at first the builder studied the circuit beforehar Receive- Operates on Lighting Current A new receiver has recently made its ay pearance that can be operated from a w socket on supply volts, alternating « direct curre: The claim made that t! power is controll: that it is quiet in operatio and unvat ing in -volut and ton-s [2 So and C-battet ies are ¢ nated Cor bined svith t! power featu are two stag ed eit! ( 4 : of condenset tuned radio-frequency amplification, and amplifier a cde a two-stage audio-frequen Che tuning is simplified by svt chronizing the three dials. tector! One rheosta is used to control the five tubes as a u

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All Shop Notes published in 1924, in book form—Fifty Cents—from our Book Department Steam Sterilizer for Dairy Utensils ) \IRY utensils that are not kept scru- average farmer who delivers two or three pulouslv clean become a hotbed tor 10-gal. cans of milk daily, and uses a cream 4, which not only cause the milk to separator of the usual type, consists of quickly, but also may contribute to four parts. spread of disease. Even though a A baking pan of standard size, 14 by 20 can may seem perfectly clean after by 3in., is one of them, and a close-fitting been thoroughly washed, sterilizing insulating cover should be made for it, as means of the simple apparatus de- follows: The edges of a sheet of medium ibed in this article will greatly increase weight galvanized iron, 4 in. longer and e time that milk can be kept in it with- wider than the top of the pan, are bent t spoiling. This handy sterilizer, which up % in. at right angles to form a shal especially adapted to the needs of the lowtray. This is filled with a number oi This Simple Steam Sterilizer Costs Little and Will Soon Pay for Its Cost Many Times by Keeping the Milk Sweet Much Longer han Usual, Due to the Elimination of Germs; Milk Cans Are Set over the Spout for a Five-Minute Steam Bath 509

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510 POPULAR MECHANICS asbestos sheets and considerable steam y be ejected through the spout, over wh a second sheet of gal- as the water boils, vanized iron is soldered over the top. A 1¢ lange, made by doubling strips of the the utensils must be held to scald the: FOR DIAGONAL STRIP Ox : Parts of the Sterilizer; Lower Left, Standar SS Size Baking Pan to Ho!d the Water; Upp | Left, Asbestos-Insulated Cover, with Spout j ‘= = Permit Escape of Steam; Right, Bottomle +4 Box with Lid, to Fit over Insulated Cover: © SECTION OF COVER a? UW, \ - / — 4 ~ 0 \ 5 ie | as A, UNARMED, 2 ci” 4 ~ log > WIRE FOR STRAINER CLOTH Ls " ’ hi\ “© \ | N = aN +\ 4 ~*~ — j A } 0. } os 15 >} | | | | ] } ~ 142° _ BOX TO FIT COVER BAKING PAN, 14x 20°X 3 same metal and bending them over at right The steam must be allowed to reach a ter ingles, is sweated on the underside along perature of at least 205°, and preferab the edge to fit snugly into the baking pan. 210° or 211 An accurate thermomete: \ 1%-in. hole is cut through the center reading to 212°, is necessary to determi: of the completed cover, and a length the temperature. This is placed in tl! of galvanized-iron pipe, about 4% in. top of the steam spout, and sterilizatior long, is fitted and soldered in the hole, of the utensils should not begin until the is indicated. strips, 8 in. in steam has reached the temperature spex length, are sweated on across the top of fied. A five-minute steam bath will tho: Diagonal the cover and also strips forming a 15-in. shown in the detail. The re- maining parts are a box without a bottom, which should fit snugly inside the square mn the pan cover and a flanged lid for the 1OX Diinensions are given in the detail lrawing. A heavy length of wire to hold d soldet ed near square, as is riveted an me side of the box, about “4 in. trom the top \ll these parts are easily made, but if tools are not available, any tinsmith vill do the work for a small sum Che cost of the material is about $7 lhe heating plant for generating the | steam is an Ordamnary two burner ket ) ene or gasoline stove, which can be found on nearly every farm. Water is poured into the baking pan to a depth of about 1 in., and the insulated cover fitted over it Chis quantity of water will furnish steam at 211° F. for about 50 minutes. As soon oughly sterilize the utensils. Milk cans may be put over the spout and left standing there until they a1 sterilized. When handling them, it is, o course, necessary to wear gloves or u cloth over the handles to prevent burnin the hands After sterilizing a can, should be set, mouth up, so that the stear can readily escape. It will be dry in tw or three minutes. The pails and separate tank are sterilized in the same way. Smal er articles are scalded in the box, whic! is pia ‘ed on’ the cover and the lid put o1 The strainer cloths are hung over the support provided for this purpose It unnecessary to rinse out the cans befo filling them w J ith milk; in fact, this proce isable, as it partlv defeats t! purpose of the sterilizer. ure 1s inad\y \s it is desirable to keep the cans and ails hot long enough to permit them t

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POPULAR MECHANICS out without wiping, they should be ered with a sterilized blanket if the 1 is cold. If they do not dry entirely is way, they must be wiped, or germs begin to develop at once. After ster tion, the utensils should be kept in a m free from dust and should not be ched, especially on the inside. When erosene or gasoline stove is used, the should not be stored in the same or it will absorb the odor of the oil. Dust Filter for Tractor Carburetor Vhile shelling and threshing, we dis- ered that much of the dust and chaff yn around found its way into tke car- retor and from there into the cylinders the tractor, which increased the carbon posit on the pistons and in the cylinder ids considerably. To overcome the ticulty, we made a filter of the kind own in the illustration. It consisted of in. wire mesh bent to form a cylinder d soldered into two baking-powder can vers. The seam was also soldered. A le was cut in one of the covers and this t over the intake of the carburetor. everal sacks were made from light-weight nton flannel, just large enough to fit er the screen cylinder snugly. These cks were cut and sewed the wrong side ut and then turned so that the nap would e on the outside. One of these was pulled er the screen and left there until pretty ell covered with dust, of which very little ot through. Then another was used un- t , 4N COVERS 4 [ Simple Filter Attached to Carburetor Intake Prevents Entrance of Dust and Increases Life of Motor til it too was covered, and soon. The sacks can easily be washed and are good for a ong time.—Dale R. Van Horn, Walton, Nebraska. 511 Truck for Moving Long Bars When a long, heavy metal bar is brought from the shop storeroom, it is usually dragged along with one end on the floor Sma!! Roller Truck Facilitates Moving Long Metal Bars and this, of course, mars the floor and is dangerous to the other workmen. Both of these objections can be overcome by using a small roller truck of the kind shown in the illustration and photo. It consists of a short length of pipe or tubing, drilled near one end for a shaft, which carries the wheels, a washer and pin at each end being used to hold them in place. In use, a lipped into the pipe and it can then readily be pushed along 1 Dar 1s S Sulphur Strengthens Concrete concrete soaked ten as been found that in melted sulphur is five to strong as ordinary concrete and is also waterprool. Concrete is so porous that it will absorb a quantity of hot melted sul phur equal to about seventeen per cent of its weight, and pores filled with sulphur the concrete is resistant to compression. The tensile strength is increased by this treatment. Although sul phur has a tensile strength of only 200 Ib. per sq. in. and ordinary concrete often less than this, test soaked in sul phur have been found to have a tensile strength of 2,000 pounds.—Chas. F. Gold- thwait, Stratford, Conn. It h times as alter the are alse a ) pieces

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912 POPULAR Draftsman’s Instrument Shelf One of the disadvantages oi a tilting drawing board is the lack ot adequate ta- cilities for keeping the ink bottle and the instruments from sliding down when the DRAWING , BOARD -—/ J || SETSCREW WEIGHT ” — —— Shelf Pivoted to Top of Drawing Board Always Main- tains a Horizontal Position table is in an inclined position. The ac companying illustration shows a conven- ient shelf that will always remain hori- zontal irrespective of the angle of the table. The shelf may be of any desired length and is pivoted to the top edge of the drawing board by means of two hinges as indicated in the detail. On either end of the shelf a piece of flat iron is fastened to the edge, with an iron-rod extension made to carry a weight, which is tightened on the rod with a setscrew. The low center of gravity of this arrangement assures a level shelf for the ink bottle and the in- struments no matter at what angle the board may be tilted —J. H. Rodgers, To- ronto, Can. Paint Keeps Lime Plaster from Setting hat oil paint applied to the surface of fresh lime plaster tends to hinder the set- ting of such plaster, is one of the conclu- sions drawn trom a series of made by the bureau of standards ‘he setting of the plaster is caused by the absorption of carbon dioxide from the air and the re- sulting change of the hydroxide, or slaked lime, into limestone. This absorption of carbon dioxide is very greatly hampered by the paint film, tests MECHANICS the bureau finds. It is retarded, but not seriously, by a finish coat, and takes plac more rapidly in lean mortars than in ric] the combination of a finish coat with a film of oil paint on top of it was subse quently tried, and was found to preven the absorption of carbon dioxide almost entirely, cubes of plaster treated in thi way showing no appreciable penetratio: of carbon dioxide after six months. Rustless Water Pipe Iron water pipe can be made rustless b coating it with melted asphalt. The pips is held up by two forked sticks, 3 ft. ar 5 ft. in length respectively, the lower end being pointed and driven into the grow about 12 ft. apart. The pipe is laid in the crotches and melted asphalt is poured into the upper opening. The asphalt is heate in a can until it boils and it is then slow! poured into the pipe, which should be turned while pouring. A pail should lx placed at the lower end of the pipe to cate the asphalt that runs through. The pip: should, of course, be thoroughly cleane before this treatment; if it is full of rust and dirt a wire brush should be draw: through first—C. F. Goodnow, Jr., Sout! Sudbury, Mass. Removing Ford-Truck Engines Considerable difficulty usually attends the removal of the engine from a Ford truck due to the interference of the das! and of the ex- haust - pipe connection. In an eastern shop main- taining a number of these trucks, the trouble was overcome by sawing a slot in the dash from the inside to the steering post, as shown, so that the dash can be taken off without loosening the steering post. The exhaust and muffler pipe are pulled out as a unit by disconnecting the clamps that hold the manifold to the cylinder block. It is ther an easy matter to remove and replace the engine.—G. A. Luers, Washington, D. C. EXHAUST - . ( MANIFOLD, (7 P a

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Making a Simple Circuit Breaker By FRANCIS G. LeMERLE RY electrical experimenter an ie é ill-shop man has, at some time ot a CCasiol to use an overload cit s =m 44

ma \ ( z | I} | goer i} YOKE -- } if BINDING | POSTS il | 7 a, ae : Y y —_— aed aii, ‘WwW WZ WT 3 t STOP Le > RH 4 - 4 ACK a SCREW ; 3 oe = ~ 2% - « 4 > ~ 5 — > SIDE VIEW Overload Circuit Breaker, Made from Readily O able Parts. for the E'ectrical Exverimente: thick, bent as indicated in the deta hie feet of the yoke are drilled screws, with which it is securel\ tastened down to the base. and the magnet i e to the top of the yoke by means of an ire machine screw driven into the core of tl

magnet, a hole being ot course drill and tapped for this purpose. Before fa te ¢ the magnet to the oke, 25 tut ‘ AN 14 dcx \\ ¢ ire ind ovet he t end of the magnet, t wind he us marked C in the drawing Phe is lature L is made of a short pie 0 sive discharges and prevents the ron according to the dimension cks and trains from being burned due in the detail. It is drilled for a r hort circuits, which occur frequent], which, after being slipped through the hol en the trains are derailed has a washer soldered « th end lhe breaker described in this article can then driven into the base o that the { used on any voltage up to 110 and 1 iest end of the armature comes direct 1 ry sensitive in opening a circuit carry derneath the magnet core A small stop from 2to 10 amp. It consists of a base screw is driven directly underneath to nd side of wood on which the metal parts support the heavy end when it is not re tastened: an old 500-ohm telephone attracted by the magnet Che other end ringer magnet, and some miscellaneous of the armature is normally raised and parts that can readily be found almost any holds the breaker arm so that there is co here and modified to suit their particu stant contact between the copper strips o ir purpose in the device the upper end of the arm and a plate Che telephone magnet Jisheld vertically which is screwed to the top of the side and vy a brass yoke, 12 in. wide and %¢ in. is in electrical contact with terminal |

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514 POPULAR MECHANICS The construction and dimensions of the breaker arm are given in one of the details. It is pivoted on a screwhook D, which is COPPER v7 STRIPS ‘4 SQ. BRASS ‘ -

armature to touch it when attracted } the magnet. The gaps between it and tlie armature and between the armature ani the iron screw below should 2 about %42 inch. Three bindins posts are provided to permit the device to be easily connected any circuit; the binding post E located on the sidepiece and, ; mentioned previously, is ele trically connected with the plate that makes contact with the co; NL LATCH per strips on the breaker ar; A, |. a The binding posts B and I are f <. ei 1 are ta | —— tened on the base: one end of t}i KC BRASS &@ BREAKER 25-turn coil C is connected ,o~ YORE io, ARM binding post B and one end oi th. , +S == i fine-wire coil J oi the telephon — TU magnet is connected to bindi: ew x post I. I he other end of the ma; SCAEWHOOK K net winding is soldered to th: sien brass voke and the other end 0: : coil C is soldered to screw D ani

a | ee 3"SQUARE to screwhook K. Screwhook \ ™ a 6 must not touch the plate unde ae. binding post E, or the circui sey hs (WA.__SOLDERED To YOKE breaker will not function. Ru)

J DETAIL OF ARMATURE G Constructional Details and Dimensions of the Two Armatures, the ber-head tacks are provided der the base. and the circuit breaker is then ready for opera Breaker Arm, Brass Yoke and Special-Shaped Screwhook tion. The circuit diagram show driven into the side. The copper strips, cut irom No. 30 sheet copper, are curved and bolted to the top end of the breaker arm, and the ends filed down evenly to make a good electrical contact with the plate. A small coil spring is used to pull the breaker arm to the position indicated hy the dotted lines in the side view when released from the latch armature. A stop screw is also provided here to arrest the arm. The armature G is then made. This is a short piece of “46-in. soft iron, drilled at both ends and in the center, as shown, a machine screw being screwed into one end and a short length of heavy galva- nized-iron wire soldered into the other end. Another short length of the same kind of wire is used as a pivot for the armature, and this is securely soldered to the top of the yoke. A small collar is soldered on this wire on each side of the armature to hold it in place, although only one collar is shown in the detail, for the sake of clearness. A knurled thumbnut is then fitted on the screw; this nut changes the balance of the armature and varies the sensitiveness of the circuit breaker, as will be explained later. The screwhook K is bent to the shape shown and is driven into the side. It comes directly over the arma- ture G, permitting the outer end of the how the breaker is hooked up to the load and to the supply line. The bind ing posts E and I are connected to oppo site sides of the line. The post B is cor nected to one terminal of the load and

H -:HO-V. LINE JF A

x Tres

LOAD

Method of Connecting the Circuit Breaker to the Su; ply Line, and Paths of Primary and Secondary Circuits the other terminal of the load is connecte‘| to the same side of the line as binding post I, or it may be connected to this bind ing post if more convenient. The prin ciple of operation of the circuit breaker is as follows: When the switch to the load

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POPULAR MECHANICS 515 urned on, the normal current flows Homemade Self-Feeder for Hogs point A on the supply line, throug! ad, threugh binding post B and coil Manv ftarmer will find a homemade pivot screw D; from here, it flow elf-feeder of the kind shown in the draw igh the breaker arm, the copper strips ing just as useful_as a purchased one. It contact consists of an to b i 1 dl old reaper bull st E, and wheel and an e to t ¢ oil drum. Both er side of supply line F. ITfithe rent be es too great short cir ends of the lat ter are removed and the shell is wired to the wheel spok c as shown \ the wheel] weighs over 100 lb., there is lit tle danger of the drum up ocreurs, ] C will mag e the tele- ne - magnet e suthcient- to draw setting If all the ar the spokes are ture G left in, the feeder will b suitable for small hogs and pigs but if it is desired to use it for large hogs, one row nst the iron w. As soon this hap s, another uit is closed ch permits rent to flow m point H, rough the yrnet wind over the ke, armature and screw of spokes must be removy ed, vhich can @Cas ily be done with the aid of , a hammer and : " . Simple Self-Feeder for Hogs M i Reaper Bull Wheel ig Ok K., to piv and O cold chisel. Of screw D, and course, this m there over the breaker arm, binding feeder should be set on a flat surface of st E and to point F on the opposite concrete or wood, preferably the former le of the supply line. rhis secondary better still, the bottom may be filled with rcuit strongly magnetizes the core of the an inch or two of concrete; in no case elephone magnet so that the latch arma hould it be set directly upon the ground re L is pulled up, and this releases the as this would very unsanitary cor reaker arm, which consequently breaks dition Inc the rough lugs o1 e circuit. As soon as the breaker arm is the rim of the offer splendid oppo released, the primary circuit to the load is tunity for itching hogs to get temporary roken and also the secondary circuit comfort. hrough the magnet J. Of course, this all ippens in a fraction of a second so that Coloring Brass Gray e circuit is broken almost immediately hen the overload or short circuit occurs lo color brass grav, first clean the su changing the balance of the armature face off with alcohol, polish it to an even (; with the thumbnut, the device can be finish, making sure that all grease and ljusted to open at different currents; the finger marks are removed, then immerse loser the nut is screwed to the center the the work in a solution of arsenic chloride ess magnetic force is necessary to pull it (poison), 1 oz., and water, 1 pt., until the lown and the less current is passed with desired shade is obtained. Wash in cleat ut operating thearmature,andthe farther warm water, dry in boxwood sawdust, and t is out the more current required. As warm and lacquer with a thin pale solu coil C has only 25 turns it cannot mag tion of bleached shellac in methy! alcohol netize the core sufficiently to attract the using a broad camel’s-hair brush.—Franl atch armature. N. Coakley, Buffalo, N. Y.

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516 POPULAR MECHANICS

=4 BRASS “

\. PANEL ; COMPARTMENT

METHOD OF DRAWER CONSTRUCTION s| ihe + el aD

B a ft “ 105 _ 4 g f_$ 26’ _—______________+ a hn SE

PANEL ~ SIDE ELEVATION 1° 7. @ Upper Left, Cross Sec- | tion, Showing Arrange- ment of Locking Pins, | Drawers and Front | | |

Panel; Upper Right, Assembled Tool Chest When Completed; Low- er Details, Front and PANEL - Side Elevations |

FRONT VIEW

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Durable Machinist’s Tool Chest By H. R. HARRIS \ STURDY oak tool chest, which will strongly appeal to any machinist, can lily be made by carefully following the tructional details and dimensions in the accompanying illustrations. e chest is 26% in. long, 14 in. high and in. wide, has a roomy till, 2 in. deep, drawers of various sizes and depths, 1 removable front panel, which can lid under the lowest drawer when the st is opened for use. Besides being ted in the neatest and most durable hion, the corners are well protected by attractive chest a strong, neatly ns ot brass corner;rs. ur brass cover clasps, signed lock, and drawer pulls greatly appearance. When to the finished hed, the sod may be ined any de- ired color, referably dark this will not Ow spots as uickly asa eht color, and led with a paste. The urface should then be rubbed lown with oil It is not ad visable to use paint, enamel or varnish, as iny mark made by sharp ools are im- mediately noticeable. \ practical fea- ture of the chest are the locking pins provided in the front edge These auto- matically lock the front pane! when the cover is brought down and it is then impossible for anyone to get at the drawers. The construction of these pins is shown in the cross-sectional view of the chest at the upper leit in the full-page il- lustration. Brass bushings are, of course, provided in the holes that are drilled in the top edge of the front panel to receive the pins. Durable Machinist's Tool Chest Made of Oak, with Attractive Fit- tings and Designed to Accommodate All Kinds of The bottom and back of the frame are first cut out and fitted together, next the endpieces and then the horizontal and vertical partitions between the drawers Finally the bottom of the till is cut, doweled and fitted in place. These parts are temporarily assembled and then taken apart, after which glue is applied and the parts securely screwed in place. The ver tical partition the drawers i screwed to the ends, back and till bottom, and horizontal drawer support with flat head screws, the holes being countersunk and plugged. The lid is cut and assembled in the same way. Care should be take to make the drawet parts to correct di mensions, and all the joints perfectly square so that | they will fit nicely in the frame when put together T o assemble them glue and nail one side to the between front, insert the bottom, which is cut from No. 22 rauge sheet steel, into the groove; glue and nail the other side ir Pp lace in the same way, and then clue and nail the back to the sides The same construc tion is used on all drawers. Felt is gy lued drawer and to all sides of the till.anda length of “es by %4-i1 rubber strip is glued to the frame of the box behind each drawer, to take up the shock when the drawers are closed. Four 3-in. steel plates are screwed to the bottom. as shown, to take iron dewels provided on the bottom edge of the front panel. Al- though these plates are flush with the sur face of the bottom, it is advisable in ordet to prevent marring the panel, to drive to the bottoms. Tools 17 wn

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2" . 6 TOP OF LID >a 8 S445 = een c edit i See - - 265 FRONT AND BACK OF LID DETAILS OF LID CONSTRUCTION

mre

’ ae Sil Te 3 ——ss —______— mye T ——— “yaD i | “ae far) | j rm B mio — 4 rd » ‘ |

——4

Ss - eat; t. 2 ae mer a: — —— y o= ari et |} DOWEL PIN TOP ENDS OF FRAME

be a _ _ 96 DRAWER SLIDES Constructional Details of the Parts of the Chest, Including Bottom, Back, Ends, Front, Lid, Drawer Supports and Slides; the Parts Are First Cut and Fitted Together, Then Assembled with Glue and Dowels round-head brass upholstery nails in the front of the panel at points where contact is made with the plates. For the sake of appearance, the front panel has a beveled center piece, which is fitted and glued in grooves cut in the sides and ends. After the chest is finished, it is advisable to ap- ply some melted soap or grease on the drawer slides to reduce friction and pre- vent wear. As here described the box was built mainly of oak. The following parts in the material list, however, were made of maple: The first five items in the list; the top, front and back of the lid; the bot- tom, front and back of the frame; the drawer slides; the top, bottom and center pieces of the panel and the front of the drawers. When made of oak and map however, the outfit is very heavy, in fact it may be too heavy for many machinist unless they desire a particularly heavy bo» in order to stand rough treatment. While this is desirable where a machinist is on the road, and his tools must be slipped many times in the course of a year, in the majority of cases lighter woods than these can be used with no great loss in wearing quality. Beech is much lighter than eithe: oak or maple, and takes a very fine ma hogany finish. Poplar, elm and chestnut are also very good woods to use, and com paratively light. Even the soft woods such as pine or cypress, can be used if a very light box is desired, but this is not

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POPULAR MECHANICS cr oO

) 1 ‘ttom half. f ‘ 1 é l 11 i right d t ¢ 10 , top halt e € 1 € | l 11 t | 17% ] m., ends lid zi -t t u n il 1 ece 1 )- 11 ] I rt lrawe t t ce, 7-1 $11 I7-16 1 ertical d ] ece y ] l 1 ’ iw ront ece, by 95@ by 25% in., till bottor 1 piece by 2 } l l iece, Se by 9 by 25 in., lid top lrawer, front 4 pieces, '4 bv 27-16 in.. dowels pieces, ; by 1 ] ece, ¢ by 10 by 26'4 in., frame bottor e1 ece, 4@ by : by 26 in., frame front piece 1} ] ece, e by 1154 by 26% im., frame back r ds by 17 by 26% in., lid back and front pieces } j ) eces, 4 by ¢ by 97-16 in., drawer slides ends 1 piece ge by 5 7-16 by 15 3-16 in., panel cente ; nie by 1 641 > . > pieces, 54 by 2 by 2415-16 in., panel t og ; ee eee wen ends ;' : ” cer yee pieces ] ) ] l ‘ 1% by 1 er-left drav , ends ‘ ece ] lower-'left rawe pawn, Fe : 4 ’ we ‘ ‘ l 11 1 ype t ty . : : t iwe l l 1! Idle-rig pieces, 834 by 1 d ape r 1 31 il lower-right d c ece \ | ece, 1 ? 4 ; a ie \ witl | ve }« I c ; 4 L l cl t t! iwe | 1 piano Ss 1 t . ect l 13 ! uppe 10 polis! pull flu ; front 8 polishe c niece 1 : lowe ‘ 1 1 hal 1.1 recommended unless the box will not be well as the hardwoods.

ubject to much knocking about or wear With the use of a good dye the softer be taken with

More care must the filling, staining, varnish , ing and rubbing. but the result is well voods can be finished to look nearly as worth the trouble A Transfer-Caliper Attachment collars and stop are drilled for two sma slide rods; these are a tight fit in one Converting an ordinary spring caliper collar and riveted over \ light coi nto a transfer caliper, which is a tool — spring is fitted between the collars. Afte ‘iten needed, can be slipping the attacl imply done by he ment in place, the eans of the attach- J eo: Sii(iing collar the ment shown in the i outer one—is pushed illustration. It is k> to one side when it i made ~ { Oo] | Owss: Sop yh) 3 over t! e ball al lt é lwo collars are made <4 = spring hold the 0 slip over the ball ‘spring ' “stop ter snugly in t | mn the end of the ad- bret countersunk hole * justing screw. One FixeOCouaR While the calipe1 ie collar has one hole - ae 2adljusted. the set ; lrilled in the center screw 1s loose and to clear the ball, while OFFSET HOLE

t he stop slides on the s the other has this ~. rods. When the adjustment rc hole offset and break- is made, the setscrew is tight S ing into a small hole ened, and when the calipers in the center, the y are opened to clear the work, , latter fitting the SUuDING ‘. COUNTERSUNK it is only necessary to close it screw. This hole is CUlAR ~-" Hove : them again until the stop ’ : = | _ Simple Attachment Converts Spring Cali- shes the ball ie countersunk on one per to a Transfer Caliper touches the ball to o tain the " side. A _ short piece correct measurement. rhe . of round rod, tapped on one end for a stop must just touch the ball lightly.—

knurled setscrew, is used for a stop. Both Harry Moore, Montreal, Can.

Page 174

| % ¥ ae a © O4LSNO1™ NN UNV VLINVS . t Row of Sharp-Pointed — jKeep Birds off Railroad igns' Protecting Railroad Signs Hawks, buzzards, owls, parrots, and other large birds, which are very nu- merous in a certain section of Mexico, found railroad signs quite convenient roosting places, with the result that the reading matter on the signs was soon obliterated. The trouble was quickly eliminated by driving a row of large, sharp spikes into the upper edge of each sign. These kept the birds off Turning a Stiff Crankshaft \iter bearings have been taken up, it is sometimes impossible to turn a crankshaft by hand or with the starter. If the car cannot be towed, the following method will be found satisfactory: Take an old tear radius rod, put “%6-in. body bolts through the holes in the forked end and screw the nuts up tightly. The projecting ends of the bolts are spaced just nght to enter the holes in the crankshaft flange and the rod is long enough to give ample leverage so that it can easily be used to turn the crankshaft over. POPULAR MECHANICS Substitute for Welding Rod While busy with a large welding job, which had taken several hours to preheat, we ran out of welding rod. The following day was a holiday and it seemed as if the work had to stop, which meant that the preheating would have to be done ove: again. Rather than lose so much time, we tried as a substitute soft-iron wire cut off from cotton bales that were on hand, and the results obtained were highly satisfac tory. It is, therefore, a good idea to pre serve old baling wire that otherwise would go to the scrap heap, as it may be found useful on similar occasions.—H. M. Toombs, Chicago, I}. Making Drawings from Photographs Biologists classify snakes and other ani- mals that have scaly skins by the arrange- ment of the scales on the head. At one time artists were employed to copy this arrangement, taking measurements with a rule and calipers. The present method of making such drawings is to photograph the object, trace over the picture with India ink and then bleach it. Any kind of paper may be used which has a semi- rough surface, the kind commercially des- ignated as “semi-mat.” The bleaching solution is as follows: Iodine (10 per cent in solution of potassium iodide), 30 drops; potassium cyanide (10 per cent in water), 5 drops; water, 1 oz. The solution is poisonous and should, therefore, be kept safe from persons other than the user him- self or his assistants. This method of out- Accurate Drawings Made b Then Bleaching Them Tracing Photographs and lining photos may, of course, be used in other commercial and professional work. —C. W. Mitman, Washington, D. C.

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POPULAR MECHANICS Se => =>, Method of Letting Stumos Burn Themselves Which Has Been Found Successful in Pacific Northwest and Has Received Endorsement of State Extension Service Making Stumps Burn Themselves moving large stumps from 2 to 8 ft. meter, standing as many as thirty to cre, is a difficult task in the Pacific vest. Every method of removing has been tried, with varying success, o far, not one of these methods has ed as well as a new burning method ted by an Oregon farmer. The burn- pparatus consists of two cast-iron rs or furnaces, a long draft pipe, hort draft pipes and several lengths linary 6-in. stovepipe. The outfit can lv be installed in a short time with d of a shovel, ax, furnace hook, iron hing rod and a wooden cleaning rod e furnaces are open at the bottom ear, and a small door is provided at ront. One of them is placed on the nd with the rear end against the p as shown in the photo. The long pipe is placed in the door, and pitch and bark chips are ‘laid over the of the pipe inside of the furnace. A t of stovepipe is next put in place and furnace is banked in with earth to a th of 12 to 18 in. After the kindling begun to burn the furnace is filled | pieces of bark dropped in through the chimney and forced down with a poker. When the furnace is well filled, the long draft pipe is shoved further in, and cause a blast of flame against the base of the stump. As the fire begins to work its way into the stump the long draft pipe, which makes the flame blast, is pushed in to the stump, causing the fire to burn deeper and deeper. It requires from 20 to 30 hours to burn through a 3-it. stump The second furnace is then placed on the opposite side of the stump with a smoke pipe attached, the first furnace is taken awav from the other side and a small draft pipe is substituted. The stump has now become a furnace, ready to burn itself, with a draft on one side and a chimney on the other. The next step in burning is to bank the stump with dirt to keep the fire inside, which will eventually consume the entire stump. Inflating Vulcanized Tubes After vulcanizing an inner tube, one should not inflate it immediately, for if this is done while the tube is still hot, the rubber stretches at the repaired portion Even if the patch is not loosened thereby the tube will at least be weakened.

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2 POPULAR MECHANICS Method of Using the Wool Baler; Figs. 1 and 2 Show How the Sides and Ends Are Raised and Crossbars Slipped Over; Fig. 3, Tying of a Bundle, and Figs. 4 and 5, the Bundle After the Sides and nds Are Dropped -

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Collapsible Wool Baler By C. MORAN \\ TOOL growers have long felt the while pressing the wool down with one eed for a simple baling device to re- hand or with one foot, whichever is most ‘onventional hand-tying methods. convenient for the operator. Aiter the baler, which has been designed by bundle has been tied, as shown in Fig. 3, ment research scientists, is shown the baler is loosened. This is done by re accompanying photos and illustra moving the crossbars which permits the 1 Vith it a large quantity of wool can _ sides to fall down and consequently di: into a neat and compact bundle engages the endpieces from the spring it ditheulty. stops. \ finished bundle of wool is baler is made of l-in. wood, cut to shown tn Fig. 5. ensions given in the detail draw- A baler of this kind will be found of con he side and end pieces are hinged siderable usef. ness, as it makes the tas! 2 by 12-in. bottom piece, as shown. of tying bundles much easier. and make are cut in the sides, near the ends, them all of uniform»~size. Anvone can ve l-in. square crossbars which easily build It; the only material neces so cut out to fit into the notches sary is some 1-in. wood, preferably hard tance between the inside of the wood because of its superior strength, a on the crossbars should be ex-_ strip of spring steel or brass and eight 12 in. Spring-steel stops, bent to hinges. Of course, the press can be used ipe indi - for othe pur ed, .ar-e SPRING a poses besides ed to the 2°” STOPS » ~ be 36" baling wool, the size and minor construc tional details being varied to suit the work if necessary. A press o f this type should not be made with the intention of using it for bal ing waste pa per, as the time spent in the operation vould be wort! the ends e stops fit- n slots for this pose, 'SO ley can pushed a: Lee hold the Ipieces in vhen the s and ends n vertical tion, as nat the m in the drawing. ree narrow more than the Sum received for the sma bundles. Al +7 hes are cut e edges of endpiece and also in the side edges, though a press larger in size than the one e center, to hold baling wire. described might possibly be used for pa se, the device is laid on the floor and per, it w ould be clumsy and inconvenient engths of baling wire are run at right to handle; balers for paper must have es to each other, through the narrow some means of compressing the paper es, as indicated. In this way the mechanically and keeping it compressed in be held in place securely while while the bundle is tied ool is being compressed. The wool rown on the surface until it covers _ hole baler and is about 1 it. thick. Repairing a Ratchet Jack first operation, shown in Figs. 1 and When repairing a ratchet jack trouble to bring up the two sides and slip the — is usually experienced in finding out which ssbars over them. The endpieces are pawl is not catching. If holes are drilled t brought up and pushed past the 1n the sides of the casing so that the ¢ stops. It is then an easy matterto pawls can be seen engaging the rack, the » the ends of the baling wire under the trouble can readily be located and rem posite doubled ends and twist the wire edied—John A. Blaker, West Auburn er securely to hold it. This is done Massachusetts.

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h2 POPULAR Sectional Granary Door Consisting of Several Loose Boards, Can Be Easily Opened Handy Granary Door A sectional granary door made of a number of 1l-in. boards fitting in two grooved side rails is frequently seen on the farm. The side rails are usually ver- tical and the cross boards all of equal length. The trouble experienced with this arrangement is that all the boards must be raised up to the top in order to remove them, and if they fit rather snugly, this is quite difficult to do. A better arrange- ment is shown in the drawing. The side rails are at an angle and the cross boards have the ends cut off at a corresponding angle. Then the boards can be removed without any difficulty by raising them only a foot or two, and when they are in posi- tion they always fit snugly. Keeping Tools Free from Rust A good way to keep polished steel tools, such as screwdrivers, chisels, drill bits, ete., free from rust without using oil or other greasy applications, is to insert them, point down, in a wide-mouth crock filled with rice. Even in an ordinary house cellar, bright steel tools will remain per- fectly free from rust for many months if this method is used, and the tools are al- ways clean and ready for use. Now and then, of course, the rice should be changed. —James E. Noble, Toronto, Can. MECHANICS Acid-Proof Table Top For chemical laboratories, battery-s; ry ice stations, and other places where a are handled, an acid-proof coating on table tops is almost a necessity. The lowing two solutions are used for purpose: The first consists of iron phate, 4 parts; copper sulphate, 4 part potassium permanganate, 8 parts, water, 100 parts. The second solutio; consists of anilin, 12 parts; hvydrochlori acid, 18 parts; water, 100 parts. Two coats of the first solution ar applied hot with a brush and allow,, dry; any dried coating that has not soaked in is then rubbed off. The surface is the: given two coats of the second solution a1 later a thin coat of raw linseed oil rubbed on with a cloth. If the table t is painted or varnished, it should scraped down so that the solutions penetrate the wood. In cases where t! method was used on some old laborato: tables the result was highly satisfactor The surface turns ebony-black a few hou after the coating has been applied. Tapping Blind Holes The drawing shows a good method arranging a tap and holder when blind . blank holes are to be tapped on such wor! as caps, covers and the like. Work this character may vary considerably depth, and since, as a rule, they are not machined for anything but the thread the ordinary machine stops will not be of : use. With the _ oN Np gp Ry SLOT IN shown the \ TAP END tap will ad- a i END VIEW OF TAP vance into the work until it reaches the face, no matter what the depth may be, provided of cours: it is not deeper than the threaded lengt of the tap. The tap is made as usual wit the exception that a hole is drilled throug its center and a slot cut across the face 0! the shank. The holder is turned on t! shank to fit the machine it is to be used ! and the front end is bored out to a ru: ning fit for the tap shank. A hole, th same size as the one through the center o the tap, is drilled through the center am another hole is drilled through it at righ! ~ KNURLED STOP PIN angles; a knurled-head stop pin fits into

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POPULAR MECHANICS 525 tter hole, and a length of drill rod is Marking Grain Bags ted into the tap. Two pins that are into the bottom of holes bored in Marking grain bags is an easy task if older complete the job. After the done with a stencil. One can readily be has been drilled or bored to the tap- made from a piece of scrap tin or other ize the tap is advanced in- __ pee hole and the lead will draw = A : the work until the end -of eo A stop pin reaches the work. x) \ er advance of the holder is 7 rrested, but the tap con- to advance until the slot in | | ~— nk is free of the drive pins, the tap revolves with the i The machine is then re the knurled stop pin pulled | the holder pushed for- bX intil the pins again engage slot, when the tap can be out. Safety Twine Cutter ere heavy twine is used for packages, a safety cutter of nd shown in the illustration » found convenient. It con- of a piece of wood slotted ally about one-half of its the slot being about % ide. A safety-razor blade is ed to the side of the wood, the slot so that it will he twine when pulled down through = sheet metal cut to the proper size. The ~ — ~~ - Marking Grain Bags Facilitated by Sheet-Metal Stencil slot. It is preferable to attach lettering is punched out as shown in the razor blade diagonally rather than at upper left-hand detail and a brush and 1 angles to the slot as the twine will be — some black paint are used to apply the let e easily cut by sliding it overthe sharp tering tothe bag. This is a much quicker e of the blade than by being pulled and neater method than lettering free- against it. The cutter may be at- hand.—J. R. Koontz, Bremen, Ind ed to the edge of a bench or counter re it is used most. The twine may be Using Spindle-Body Bushings Twice ided through the center hole of the so that the end is always handy when A discarded bronze spindle-body bush ing from a Ford car can be used to replace a steel spindle-arm bushing. Both end are cut off with a hacksaw, allowing it to be slightly longer than the steel bushing Aiter it is driven in place both ends are peened to expand the bushing and tighten it in place. A reamer is then run through to enlarge the opening to the desired size. If the spindle arm and steering-rod yoke are worn and allow vertical play, the flange on the bushing can be ground or filed down to the proper thickness so that no washer is needed.—E. T. Gunderson, Jr, Humboldt, Iowa sfety-Razor Twine Cutter Fastened Conveniently to Counter ? ; @ Keep the contact point of the toolpost eded. Obviously, it is almost impos- setscrew oiled, to avoid wear on tool and le to cut one’s fingers on the blade ar- screw and prevent the point of the screw ged in this way. from bushing out.

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a0 POPULAR Safety Attachment for the Lathe 1 | \ factory employe ted in facing nuts in whose work con nuts stationary by means of a wrench, as shown in the upper photograph, while they were backed off from the threaded arbor, well until his arm facing tool and badly worked against the The idea drawn Locating Punches for Spindle Washers Washers of different kinds are used to take up the end play in Ford-spindle arm or body joints. These washers are difficult ‘nter so that the spindle bolts can be replaced. \ good method is to round-ended punch which use a er over the hole in the spindle when Such as t driven down punches can be made of discarded spindle bolts by cutting ff the threaded part with a hacksaw and erinding the end round | . Gunder- Humboldt, Iowa SOn, Concrete Posts Protect Pedestrians Along one of the principal streets of Portland, Oreg., at the foot of a long, steep hill, reinforced-concrete posts have been provided to protect pedestrians from run away autos. In a recent accident an auto smashed through a store tront and en a lathe, held the Was vill center the’ MECHANICS cut. Then the safety device shown in iower picture was attached to the | the machine wrench, attached to iat Chis consists of an alli a lever so that it be pulled torward ag the nut. Using thi vice, the machine ; versed with one while the lever hand pulled forward wit}! other. The arbor us¢ this operation dit from the usual type threads on it to the low-limit | diameter for a le: corresponding to tl fourths of the lengt!] being the nut, and from point tapered, .020 in Above, Usual inch, for four or Method of Hold- threads. The nut to ing Nuts Station- ary While Backing faced can De crewed Them off a the arbor while the Threaded Arbor | ee a. notior after Facing in a ears 1S en Moulos Lathe; Left, Safe- locks itself on the taper ty Nut Remover thread, enabling a | facing cut to be tal This eliminates trouble encountered if t face of the nut is not at right angle the axis, a fault that is frequently f in nuts faced on a straight-threaded and screwed against a shoulder. faced on the improved arbor were fo ‘ to be true within .002 in. when teste means fF an indicator.—Chet. Sh lint, oO! Mich. dangered the lives of several persons near the ‘ll as the ot the car the erectio: \\ ere pants store, as we since Concrete Posts on Edge of Sidewalk at Foot of St Hill Protect Pedestrians from Runaway Autos motorists take here is consequently | the posts, ereater care ie@ss dl anger;r.

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Prize Offers and Announcements

50—Best New Uses for Stop Watch awards of $100 and $50; also ten additional f one stop watch each. These offers are made best lists of uses for the Pastor stop watch, an accurate instrument consisting o!f a time | a stop watch in one. Particular value is this concern on uses promising great savings t Leading engineers claim that in the in- lions of dollars are wasted owing to lack of to the time element in operations. The Ster-

Company, Inc., wishes to learn all the uses the Pastor stop watch may be put. The larger e cash offers will be paid for the best list, the for the econd best and a Pastor stoy ued at $ ), will be given for each of the est series uses received. T.: instrument x old machines as stated in Problem HA-2 HE SUM OF $50 IS OFFERED BY THE Manufacturing Company for the best plan eceive for uses of ground slate O THE PERSON SUBMITTING TO THEM ticle which they can make in their machine and cal shop, the Guyan Machine Shops will pay over and above its royalties or sales price. RANITE STATE MOWING MACHINE COM offers $500 in cash and royalties for satisfactory king drawings for gasoline-motor lawn mower they ept tor mantniacture and marketing but if the company approves and enters into such agreement in any imstance, and reward is paid up t aggregate of $1,000, payments shall then cease and the Bridgeport Brass Company shall become proprietor of all rights, privileges and returns from the promotior anutacture or sale of any such patent, plan or sug gestion the Bridgeport Brass Company adopts unde this offer May 1, 1925, is closing date for this offe Address Bridgeport Brass Company, Bridgeport, Com $1,000—Adjustable Miter Box

rhe sum of $1,000 in cash and a satisfactory roy will be paid by Roche and Moore for a suitable ter = Sef Cevmentete, to Ge-cineteved seit Gis-medienrs ndsaw The des gn must be st h that it can be ea quickly adjusted t t t of half rele It 1k ec one mexpet e to manufacture. s} 1 be n weight and preferably lanned 1 he tec f erthe d tee N le ested designs ld be sul tt t te th araw gs r sKxetcne h e bec serit ft the lor r meern reserves the right to be the sole ridge of the nerits of all ideas submitted and their availability doption by yur rganization Addres Roche Moore Cochranton, P This offer expires May 1, 19 $25—New Uses for Cel-o-Glass The sum of $25 will be paid by Cello Products I: porated for each suggested ne ise for its product Cel-o-Glass, provided said use is of such character as t open up an entirely new and definitely accessible ma ket for the sale of this adaptable material. Entries will be judged by the company alone In case of duplic: tion of suggestions, preference will be given to the one first received List of present uses and other inforn tion can be had from the donor Address all replies t Cello Products Incorporated, Box 28, 89 Fulton Street New York, IN PREVIOUS ISSUES Expire May 1, 1925 NATIONAL BRASS COMPANY WILL PAY } $300 for design of key guide that can be made of s metal and which will properly fit escutcheon plate of similar material eet TO ANYONE WHO WILL PRODUCE FOR them a saxophone reed to satisfactorily replace the present reed the Bu 1es Bar d It trument Comt if will pay the sum of $1,000 THE PHENIX RADIO CORPORATION WILI } neu fort pay the sum of $1,000 for the design of FOR A SATISFACTORY HAMMER - BLOW arrangement for portable hammer lrill, the W Electric Tool Corps t ll pay $ $2,000 WILL BE PAID IN SEVERAL AWARD for processe nd machines for sa ig waste lu € National Lumber Manufacturers’ Associatior FOR SKYROCKET STICK HARMLESS I> descent, $1, on shel with 1] umn ated flag $ . chemical combinations t produce smokeless firework colors, 250 Thearle-Duffield Fireworks Cor I MOTOR-OPERATED HANDSAW FOR MANI facture and sales; award, $10,000 in rovaltie R. I Barker and Company ELECTRIC HEATING ELEMENT WHICH will operate and inter hange with base and cover Imperial self-heatir gasoline iron, $500 Impe Brass Company DISCOVERY OF NEW USES FOR CARBON dioxide gas or improvements to present use Aw $1,000 ull Details Regarding the Previous Offers Listed Above, May Be Obtained by Ad- dressing the Bureau of Information, Popular Mechanics Magazine

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O28 POPULAR MECHANICS Radio Questions and Answers

Q. Can you tell me why I am unab'e t et low wave south or east and west? \ lengths on my three-tube set? I we all the way frou ipport for tl vertal I 340 to 560 meters. A Either y nductance is tm 100 ft. lor ind place the 1 uN I ¢ t Te i not u J i tuning con ac mmmodate thi leng t et 1 t er | ’ ut l le i rr putting a ele ite the erial the better 1 ] er ert vit tl vund that the lead-in end 1] ts which you expect to recei Q. Does it make any difference where the lead-in wire stati N 14 copper wire is connected to the antenna? Will there be any differ- will give good result Care if two antennas are within 5 ft. of each cther? ind use good insulator It etter to mnect the lead-in wire at the end f the antenna nearest the set If the two antennas are Q. I would like to make a simple crystal receive: t run parallel to each other, the distance should be do not wish to invest much as it is for a small ll right, otherwise it should be increased to 8 or 10 Can you eetae me to some article on the subject? ft However, parallel antennas do not give ; ood the January, ati issue we described a very esults as when the e at n angle én enh athe t crystal receiver f this type lf you do not 1} back number you can obtain it from our subs Q I have been troubled by what I thought was department t the usual price All construct static, but the noise continues even after the ground tails are given in the article, and the instrument and aerial are disconnected. What is the trouble? be built for about 75 cents. \ There is probably a taulty connection in your set lifticulty might be eliminated by resoldering all Q. My neighbor is uneasy because I have an aeria loubtful connections until the right one is found Che the roof. We live in an apartment building and he ile may also be caused by dust between the plates afraid that lightning will strike the aerial. Of cours the condenser, or the sliding contact in the reat this is foolish, but f have taken it down to please hi y have become corroded; possibly also the B-hbat- Can you suggest some other means for me to build a: ‘es are defective aerial that I can use with the receiver I now have I do not feel like building a more expensive set at th Q I cannot understand why low-ratio audio-fre- time. I have | a five-tube neutrodyne receiver. A. \ ; quency transformers are used in most circuits. Why neighbor is unduly alarmed. A well-built aerial, not use _ transformers of erly insulated and pr nigher ratios and get loud- with an approved hg! er signals? A. Both higl i ; . , arrester, is a prote ind low ratios will woe, Lhe Radio Department is will : building rather tl but the reason for using the . . . lazare owevet ae eealee ta te women ing and anxious to serve you. It . - 4: . ‘ am anxious to know a the proper plate and fil Radio Editor, Popular Mechanics .0005-mfd. variable ment voltages. Change the Magazine, 200 E, Ontario St., denser is specified it rid leak first, then look t : circuit I wish to e ur A and B-batteries and ( hicago. A. The statement tl ee that they are in good condenser is W5-1 condition, and that the pacity cannot be made ight voltage is applied less you have the aut! Ve may ] r t » litth too mel voltage for ft ti man wcturer for it, or have tested it you er operatiot : former years, it was the practice of the manutacturers. and writers to state that the 11 Q. I have just built a spark sending station. Is there variable condenser was of approximately any way that I can listen in on it for the _ broadcasting capacity, the 23-plate condenser .0005-1 stations? \ N transmitter will do nothing +3-plate condenser equivalent to .001 mfd ‘ but send The receiving instrument is a separate de condensers are no longer made in a standard pa ice. It is always best to obtain some simple bool on materials differ, plates are larger and in some « radio betore attempting t build transmitters and re smaller, spacing and design differ, so the safest met ceivers, so that you may thorough! nderstand the is im all cases to be guided by the rating given principles ved before going to a1 expense It is manutacturer ilso ne to ebtain a license from the radio in spector district before you can operate a trans Q. I have a radio receiver consisting of a single-circ mitting <trument No license is required for using tuner, with grid and plate coil. It is not selective. H a radio receiver can I make it more selective? A. Wind : separ aerial coil on a form the same diameter as your grid « Q. Being a reader of your magazine, I am taking the putting 10 or 12 turns of No. 22 ecotton-covered v liberty to ask you a few questions. I wish to put up on this coil, and mount it about in. from the se an aerial in the best possible way. Should I use iron ary or grid coil that you now have, putting the pipes for the masts, or would it be better to use wood? in inductive relation to each other. Connect the ac How far should the masts be apart, and how high and ground to the ends of this coil instead of to shail I make them? Is it best to run it north and grid coil as you now have them. [* accordance with the editorial policy of this magazine never to accept compensation in any form for what appears in our reading pages, and also to avoid all appearance of doing so, we are obliged to omit the name of the maker or the seller of any article described. This information, however, is kept on file and will be furnished free, by addressing Bureau of Information, Popular Mechanics Maga- zine, Chicago. [ Editor.]