Popular Mechanics 1929-03: Vol 51 Iss 3

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MAGAZINE WRITTEN SO YOU CAN UNDERSTAND IT

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Popular Mechanics Magazine 200 E. Ontario Street, Chicago, U. S. A.

H. H. WINDSOR, Founder H. H. WINDSOR, Jr., Editor and Publisher London: Hachette & Cie., Paris: Hachette & Cie., Melbourne: Gordon & Gotch 16-17 King William Street, Charing Cross, W.C. 2 111 Rue Reaumur 509-513 Little Collins St. ISSUED MONTHLY SUBSCRIPTION: SINGLE COPY, 25 CENTS ines ene ond ingnataian, dee Saint Site, onl Sesion, ger yam, postpaid - $2.50 To all ether countries in the Postal Union - : - - - + 3.00 All subscrip are d inued at expirati Shik mentns de Gin eden anens eat, 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 CoO. Copyright, 1939, by Popular Mechanics Co. Copyright in Australia. Copyright in France

Vol. 51 Contents for March, 1929 No. 3 Special Features NS. ind 2, Adventures in Wonderland............... reuse antelaiee een .. 434 Where House Heat Goes wees Mncubactecs 1 aiele a VG Ap cf Taming the Father of Waters ; sail 450

, From Sputter-Spatter to Water Speedster 486 ilable. Advertising—window display on wheels 425 Boats and Boating al Agriculture—vacuum cleaner for grain 417 speedboat motor lies flat to lower gravity center. 369 rsoni Air-Mail—first envelopes prized by collectors 377 yacht fitted with gun for shooting ‘ng fish 397 5 free! Airplanes Bridge automatic steering gear for 414 joat span into place 376 , turns carries torpedo weighing one ton 440 grooved track for autos 449 npactt, lands in drag sal 423 Buildings—tall like obelisk to guide aviators 466 Pp model of rocket, controlled by radio 459 Cable—new, sends eight messages at one time 460 ports, refueled in flight for endurance run 401 Cafe—stove and blankets in, draw winter patrons 465 Airship—all-metal to test construction theories 447 Cement—sprayed with metal to make it waterproof 417 t sucl Animals—ship mink in special crates 457 Chimney—felled from inside to protect buildings 425 Archzology—“Norse” ruins laid to Eskimos 465 Clamp—spring, holds work 446 Automobiles—windows reveal inner secrets of engine. 424 Coal—pipe stems made from 459 Automobiles—Accessories Coaster—for snow or ground 432 gauge in radiator cap shows water level 449 lagen of window catch 412 safety brake release 412 Disease—gas mask for asthma victim 465 signal on choke 458 Dogs—suit and boots for pet 471 Starting lever for Fords 432 Door—spring tag for key foils burglar 449 wrench for hub caps 413 Earth—interior now known to science 377 Automobiles—Driving Electric Power—Edison explains cost factors in pro- autoists required to speed across viaduct 433 as 448 glare screen on windshield 466 Electric Switch—with pilot light 471 moving map for driver 460 Electricity—muscular movements produce 458 Aviation Fish and Fishing airplanes of slower speed demand of 376 electric shocks keep fish from irrigation canal 432 } gas tank as airplane guide 471 lookout on tower fishes with telephone 377 landing lights set in ground show wind’s direction 461 Flowers Bees—measure of breath shows insect’s health 449 geraniums kill beetles 432 Blanket—army, resists water 447 keep longer without chemicals 448 [Contents—Continued]

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Fur—taising Karakul sheep new industry Games—buzzer to answer questions . Homes—roof-bungalows on skyscrapers Horses—racing light rays for . Household Devices .... I bins caresses <. 00d ¢ Ink—new fireproof .... Lamp—bridge, adjustable at press of button Lawn Sprinkler—hidden, keeps grass green Leather—made transparent Lettering Guide—for drawing letters Light—how invisible serves to prevent crime Lighthouse—sends radio beam to guide ships in fog .. Mail Bag—wheel carrier for Maps—sticks and leaves guided early sailors Metals hand decoravor for ‘ magic, resists wear and hardens iron Milk—lifter for bottle caps .. Mirror—hand, with anchor Money—new designs on pa Moon—skating on frozen Moving Pictures movie voice follows actor in screen movements talking movies sent by radio Ocean—shotguns fired under, to measure its depth Oil Well—pillar of fire marks first Australian Paints and Painting harmless luminous, to light homes spray gun operated by automobile motor Paper—used for blasting after chemical bath Patterns—electro process for eliminates shrinking Periscope—for onl fans . Photography hunting goats with camera requires disguise photos serve as sculpture for bridge statues Plants breathe only by day, light tests show spread pollen by ectricity Potatoes—gas treatment for cause early sprouting Pressure—artificial, eggs are “‘boiled’’ under Printing—type set by telegraph eotpnatitally Radio cutting down resistance stages .. shopping tips for fans ... ; travel beyond moon echo tests show Radio—Aerials attractive lamp forms . clamp for é Reliontietientinas automatic sea beacon has wide range song sent by photo across Atlantic Radio—Coils—making short-wave Radio—Eliminators compact a.c. converter new combination A-supply Radio—Installation handy kink for set builders hints from the laboratory solder in tape form money cohol peutbio on Radio—Loud Speaker—battery-operated dynamic con- verted to power ..... Radio—Receivers a screen-grid short-wave adapter correct coupling for Radio—Reception improving tone quality regeneration necessary for DX Radio—Repairing push-pull amplifier kink Radio—Television—projecting pictures Radio—Tubes heat in voltage regulator unit protects a.c. tubes Radium—seek curb on deaths caused by Railroads model railway which obeys voice night train signal on track Rats—gas attack routs Rays, Ultraviolet—from sun now on increase Rubber Stamp—jointed grip improves Rug—serves as game board Saws and Sawing—lumber waste is reduced by thinner Seeds—live forty years in deep soil Shaving Accessories—brush holds soap and styptic Smokers’ Accessories combined case and lighter lighter fits in lamp socket Spray Gun—electric run from ath socket Store—self-feeding shelves Submarine—safety inventions Sugar—from peanut shells Surfboard—run by motor gives water thrills . Telegraph—wires connected on Telescope—giant, planned for eis lifornia ‘college Tennis—racket string guards help improve _ Toaster—electric, opens up like a book ..... Traffic operate electric policeman by sound of voice sidewalk lanes for shoppers Travel—town’s history under roof Trees in tropics gives milk like that of cow . transplantation of aided by drugging Tricks—at the billiard table Warehouse—in cave for storing potatoes . Welding—silent on hospital addition Well—artesian, water from heats rail station Windows—that tip inward easily cleaned Wood—rare pink, found in Zululand AMATEUR MECHANICS Automobile ash receiver and hand straps for auxiliary gasoline tank prevents stalling oil distributor shaft Bed—warming the, on sleeping porch Bird House—novel Catamaran—old auto propels Ceiling—applying plaster patch to Chisel—sharpening wood Dynamic Speaker—a stand for the Fishing—collapsible fishline drier Furniture—how to refinish your old Garage—raising with auto jack Golf—handy place for score card Guns—handy pistol shell remover . Ice Box—electric light in the . Lap Board—has many uses : Lathe—boring bar for the home .. Paints and Painting finishing plaster walls with plastic paint made from white lead . Poultry—cleaning ducks quickly Pump—running with farm engine . Scisso’ netizing a pair of Shoulder Pads—made from old auto tires Skates—racing blades fitted to clamp Tricks—clever handkerchief Walls—tepairing leaky cellar .. Wash Boiler—protecting bottom Wood—removing dents in soft SHOP NOTES Automobile Bus—scrapers on eliminates ruts Automobiles one way to save gasoline worn shackles cause backlash in . Bookcase—making a modern Bottle—handy tipper for distilled water Concrete—preparing lintels for trim Door—repair for lock keyholes Fence—circular passage in Grinding—a sphere — Ice Cutter—homemade engine driven .. Joint, Wood—for the amateur Linotype—permanent line gauge . Oilstone—taking care of your Reamer—wedge tool centers Saws and Sawing a ball-bearing scrollsaw weighted saw cuts faster Scriber—multiple, surface gauge Toolbox—field, for the farm Trapdoor—fiush handle for Well—safety hook on digger’s rope Windmill—homemade remote control for

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from Above, Is Caught through a Hatchway in the Vabin om, s Diego; the Gasoline Hose, Dropped hn 4 at tie Recurd-Beeaking Crew Looking After the Gas Lines .”” Refueling in the Lieutenant Inset, The Big Tri-Motor Fokker “‘Question Mark Popular Mechanics Ma REGISTERED IN U. S. PATENT OFFICE gazine WRITTEN SO YOU CAN UNDERSTAND IT Vol. 51 MARCH, 1929 No. 3 7 Sergt. R. W. Hooe, Wearing Both Back and Front-Type Parachutes, Starting Out the Catwalk to Look Over the Starboard Engine of the “‘?”” While Flying above San Diego, California VIVE weary flyers, their faces grimy and smudged with oil, stepped out of a great tri-motored airplane at the Metro- politan Airport, Los Angeles, and jumped into waiting ambulances to be speedily transported to food and baths and rest. Their huge machine had been aloft 150 hours and 40 minutes; which meant that they had broken every aviation endur- ance record in history. A few minutes earlier, a forced landing had averted what might have been a tragic fall to the earth. For a night and a day, all hands had fought fiercely against engine failure in every motor. And at a time when once again the craft had seemed to be in ship-shape condition, it was found that the left motor was missing, a situation calling for but one procedure— immediate descent. Nearly five days previously the giant plane, refueled at stated intervals by means of an especially devised hose at- tached to a plane that flew to within a few feet of the “Question Mark,” had broken the American refueling record of 37 hours and 15 minutes, made at San Diego in 1923 by Lieuts. Lowell Smith and Paul Richter. Having shattered this mark, a few days later the “Question Markers” broke the world’s refueling record of 60 hours and 7 minutes made by two Belgian airmen, in 1928. Later the intrepid American flyers proceeded to break the world’s record of the “Graf Zeppelin,” which soared 3,967 miles in its flight to America last fall while remaining in the air 111 hours and 34 minutes, The “five musketeers,” as they are af- fectionately known in air-corps circles, were Maj. Carl Spatz, flight commander, Capt. I. C. Eaker, Lieut. H. A. Halverson, 353

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POPULAR MECHANICS Lieut. E. from the air was unique in aviation history. In this connection Maj. Gen. James E. Fechet, chief of the air corps, “The manner in which the refueling apparatus was in- stalled and _ per- fected is marvelous, Watching the actual op- eration previous to the flight, I was astonished to find that there was no difficulty at all in attach- ing the hose to the fuel pipe of the endurance plane (going at about seventy miles an hour) and when the gasoline was being delivered the pressure was such that the hose became an in- tegral part of both planes. says: R. Que- |*% caver 2 Affe sada, and Sergt. Roy ooe, se H o 2 Oe The method of transferring fuel of the fuel took place.” As emphasized by the air-corps experts at the outset, the purpose of the flight was not only to put modern airplane engines to the acid test of abso- lute endurance and to determine the strain of flight on the human sys- tem over a _ protracted period, but also—in fact primarily—to investigate the practical value of re- fueling in both military and commercial aviation. Bombing planes, for in- stance, would be given a wider range of action, while commercial planes, owing to de- creased fuel weight, would be able to carry greater pay- loads, if refueling could be demon- strated as a success- ful routine function in aviation. Both the refuel- ing plane@and the endurance ship r were equipped with two gas tanks and No effort on the part of Major Spatz was re- quired when the delivery Interior of the “?” Showing the Berths and the Big, Square Refueling Funnel; Center, a Sheet from Major Spatz’ Log; Bottom, Chalking Messages on Messenger Plane, Which Flew Alongside to Deliver Them

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POPULAR MECHANICS 355 Sse TAS MAP OF THE FIRST FIFTY 2 {x HOURS OF FLIGHT DURING SS S224," WHICH 2000 GALLONS OF FUEL WERE USED ROCKWELL FIELD ok 3 = sMDEcO & ew Sz The Map of the Epoch-Making Six-Day Flight, Which Broke All Records; Because of Fog on the Coast, the Plane Spent One Night Inland Flying over the Desert Waste of the Salton Sea an oil container. The tanks in the former are joined with a pipe to which is attached a fifty-foot hose with a two and a half inch diameter. A similar hose is attached to the oil tank, while ropes were provided also for lowering food, water, messages and other supplies. On top of the gas tank in the “Question Mark” is a berth with two other beds of the folding variety in the rear of the cabin. The gasoline is pumped by hand from the special tank in the refueling ship’s cabin. During refueling periods, the two ships came within about seventeen feet of each other, the endurance plane flying beneath and slightly behind the supply ship. Major Spatz, wearing goggles, rubber face mask, rubber gloves and a raincoat, stood on a small platform built in the entrance com- partment of his ship. Thus he was about shoulder-high in the opening cut in the top of the ship at this point As the hose was lowered from the plane above, he caught it, pulled it through the opening and turned a valve; whereupon the gaso- line poured into a reception funnel just beneath the mouth of the hose, at the rate of seventy-five gallons per minute. A complete log of the ship tells a graphic Story. In its earlier stages, it tells buoy- antly of luxurious repasts of roast chicken, ham and eggs and hot coffee, pleasant lounging about the cabin and perusal of the very latest magazines and news- papers. But there are, too, Major Spatz’ entries about his experiences when the re- fueling hose slipped during its speedy journey and spread gasoline all over the interior of the cabin; for instance: “The refueling last night was the most severe test we could have had. Air was very bumpy. Our batteries were low and gave only a faint light. Moon, Jopkins and Solter (in the refueling plane) stuck to their guns nobly. The bumps were severe enough to cause a difference in the dis- tance between the planes of between twenty and forty feet in a fraction of a second.” Late in the flight, in fact the day be- fore the forced landing, Lieut. Elwood R. Quesada, one of the four pilots in the “Question Mark,” wrote: “One motor sounds all right but doesn’t look so good. It is slowing up. We can’t trust our ears any more. It looks as though the human being would outlast the motors. They are going fast.” One of the unsung heroes of the epochal flight is Sergt. Roy G. Hooe, chief avia- tion mechanic at Bolling field, Washing- ton, whose task on the “Question Mark”

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356 POPULAR MECHANICS However, the tests of 1923 and those conducted by the “Question Mark” differ in certain marked respects. In the first place, the 1923 endurance plane had only one motor while the record breaker has three. The largest quantity of gas trans- ferred at the earlier date was 125 gallons while hundreds more had to be poured into the tanks of the 1929 endurance ship between dawn and dusk every day. Two men sat in open cockpits in 1923, while five men enjoyed a A Refueling Flight That Failed; Blaine Tuxhorn’s “Barling” Taking Gaso- line from a Catapault That Hurled Cans into the Air was to maintain at all times the steady beat of the engines. If any of the three great 225-horsepower motors happened to skip or falter, Hooe had to repair it at once, and to say that his was a man-sized job in the midst of the terrific speed and frequent cold weather, is to express the situation mildly. Many a time he had to climb out on the fuselage and repair an engine. Along with the four tireless pilots he made aviation history. No objective was set concerning the length of time the plane was to remain aloft. The problematical feature of the mission is best indicated by the naming of the ship the “Question Mark.” Air- corps heads early emphasized the point that a minor mishap, which means little in ordinary flying, can put a most effective though temporary brake on any non-stop experiment. However, every precaution was taken to have plane, engines and equipment as flawless as possible. Noth- ing was left to chance. Regarding the earlier refueling test, Major General Fechet says: “Preliminary research along these general lines was made five years ago when Capt. Lowell H. Smith and Lieutenant Richter con- ducted experiments which had their climax in a border-to-border flight along the Pa- cific coast. This flight furnished oppor- tunity for the transfer of the largest quan- tity of gas then on record.” far greater share of com- fort in the “Question Mark,” which includes among its special equipment three berths, two comfortable wicker chairs, books, ra- dio and a small electric stove. The plane in the recent flight was to have two officers on duty in the pilot’s compartment at all times. Major Spatz attended to the transfer of supplies and Captain Eaker was at the wheel during the contact periods, of which there were from three to six each day. That is to say, these two officers took charge by day while Lieutenants Halverson and Quesada took their places by night. Many and enthusiastic were the expres- sions of opinion about the probable ef- fects of the record-breaking flight from men high up in the war department or air corps. Major General Fechet said: “I be- lieve that within a few years we will have commercial planes capable of a cruising speed of 150 miles an hour crossing the continent. from New York to San Fran- cisco and Los Angeles without stopping and picking up their fuel in the air.” F. Trubee Davison, assistant secretary of war in charge of aeronautics, called the feat, “a new and thrilling chapter in man’s conquest of the air.” He added: “Several important problems were solved in prep- aration for the flight, all of which make for materially increased safety and relia- bility. Many other lessons have undoubt- edly been learned which a study of the de- tails of the flight will reveal.” iro the ch the

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iry n’s ral ep- ike jia- bt- de- POPULAR MECHANICS 357 CHEMICAL SKATING RINK SMOOTHED BY HOT IRON Synthetic ice, made from chemicals, places skating in the list of summer sports where an artificial pond is practical. It is varm instead of cold and does not melt, and when it becomes rough after too much use, it is smoothed out with a hot Pouring the Chemical into the Frame of Rink, Smoothing Rough Places with Iron, and Skaters Enjoying the Thrills of a Winter Sport in Tropical Surroundings iron. The formula for the composition of tropical surroundings, in a Hollywood the artificial ice is the invention of a_ studio, for use by the actors during recrea- chemical engineer of Los Angeles, and _ tion hours. For skating, the ice has all the the rink illustrated is installed, amidst properties of the natural product.

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358 POPULAR MECHANICS COAL STOVE FOR AUTO ENGINE PREVENTS FREEZING © P. & A. Placing the Stove under Hood, to Keep the Engine Warm; the Degree of Heat Can Be Regulated To keep the automobile engine and ra- diator warm while the car is parked in cold weather, a portable coal-burning stove has been introduced. It is said to be entirely safe, has an arrangement for regulating the degree of heat desired and ' can be carried under the hood when it is not needed. PRAYER WHEEL RUN BY WIND PUT ON EXHIBIT Devout natives of Tibet have an easy way of saying their pravers. The suppli- cation is written out on a long strip of paper something like stock-ticker tape, then placed in a wheel or cylinder which is spun at a rapid rate, sometimes for days. Each revolution, the worshipers believe, is equivalent to an oral repetition of the prayer; therefore many spinnings make it more effective, it is thought. Some of the cylinders have a tin propeller to produce the revolutions when the wind blows. Dr. Berthold Laufer, noted orientalist of the Field Museum of Natural History, who has collected a number of the prayer wheels for the museum’s exhibits, points out that it is curious that a people so back- ward and slow-moving in other things, should have devised a mechanical means of saying their prayers. The idea, he sug- gests, seems more in keeping with the more mechanically minded people of the west. Near the villages, and in the gal- leries of some of the temples of Tibet, are huge barrels, thirty or forty feet high and fifteen to twenty feet in diameter, turned by windmills or waterpower. In these are placed complete collections of the books of Lamaism, the native religion. CHEMICAL IN GRAPEFRUIT PEEL FORMS GOOD FERTILIZER Grapefruit peelings contain chemicals that make good fertilizer, tests at the Florida experiment station have shown. Nitrogen, potash and phosphoric acid are among the substances they release to the soil. In certain producing centers, where large quantities of the offal are available, the peelings can be used for fertilizer with but little expense, the tests indicate. BILLIARD AND DINING TABLE COMBINED IN ONE Entertainment and utility are combined in a table that has a removable top with space for playing billiards beneath. When the top is on, the table cannot be told from an ordinary living or dining-room article, and the cover is made in sections so that it can be removed easily. Drop aprons conceal the billiard rails and pockets. Table Top Slides Back in Sections, and Is Removed for Playing Billiards on Base Underneath ee a a a a ae

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ved POPULAR PLANTS SNEEZE AND TAKE COLD SCIENTIST FINDS Plants and flowers are afflicted with a form of sneezing and catching cold, ac- cording to H. H. Whetzel, of the New York state agricultural college. Professor Whetzel has photographs of a plant sneezing. A certain kind of destructive fungus has cup-shaped seed holders and at the bottom of each seed-pod bag is a - charge of starch which ferments and ex- plodes. This causes the seeds to blow out in all directions. They float through the air and lodge on the leaves of other plants, taking root there and causing ef- fects similar to those produced by colds. Among the plants, however, the “colds” are not contagious. Each variety has its own kind of cold and these do not attack other plants not even in the same garden. A photograph, taken at the instant of the explosion of a seed bag, shows tiny seeds swirling like a dust cloud from the cup. WINDSHIELD WIPER IS HEATED AND ALSO REDUCES GLARE To prevent the formation of snow and ice on the windshield, an eastern inventor has devised a heating chamber, installed with the wiper. It is wired to afford different degrees of heat and can be swung out of the way when not needed. The heat chamber itself is of tinted glass, which is said to reduce the glare from approaching headlights and also protects the eyes from the glare of the snow in winter driving. SHARKS TO YIELD PROFITS IN OIL AND LEATHER To reclaim valuable products from the tons of sharks that are caught every week during the whaling season, an Australian concern plans to erect a factory at Two- fold Bay, New South Wales. It is esti- mated that nearly $1,500 will be reclaimed each week in oils, leather and other sub- stances produced from the sharks and other inedible fish, MECHANICS 359 Outlets Installed in Office, and Close View of the Single and Double Types ELECTRIC OUTLET ON FLOOR SIMPLIFIES WIRING Adapted especially for stores and of- fices, an electric outlet is set up near a desk or table for lights, telephone, dictat- ing machines or other equipment. It is made in single or double-connection styles, is easily installed and has a brass housing that protects the wires. With a number of these outlets in place, various combinations of service can be worked out with practically no extra wiring, and the floor connections are often more easily made than those from wall sockets. FILTER FOR HOT-AIR REGISTER KEEPS WALLS CLEAN To prevent dust and dirt from soiling the walls and ceilings in homes that are heated by hot-air furnaces through floor registers, a filter pad has been de- } signed to be in- stalled just below the register. It is made of a finely woven, chemically processed steel wool and is thick enough to cleanse the air of soot and smoke without ap- preciably hinder- ing the heat from rising into the room. It is easily removed for cleaning.

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a JAN AYA DING LO) DSRS) NVA b The Bow of the “S-4,” Supported by Two Pontoons under the Lights of the Salvage Tugs, After It Broke the Surface Following Forty-Nine Hours on the Bottom of the Atlantic ESTING the best of more than 5,000 submarine-rescue devices proposed to the navy during the last year, the “S-4,” which was rammed by the coast guard de- stroyer “Paulding,” on Dec. 16, 1927, is now undergoing trials as the world’s first experimental rescue submarine. Raised and repaired, after the removal of the bodies of her forty dead—six of whom lived for seventy-two hours in the torpedo room before their air supply was exhausted—the “S-4” was sent to the bot- tom again on the first anniversary of her fatal accident in the first of the series of experiments which may continue for many months. Her engines had been removed and the apparatus that remained aboard concentrated in two main compartments, leaving three sections which may be flooded at will to simulate conditions on a damaged submarine. The first test was not an unqualified success. It took forty-nine hours to bring the boat to the surface after sinking her in sixty feet of water, and that was with the rescue equipment ready alongside to start 360 rescue operations the moment she reached the bottom. Had it been necessary to gather the pontoons, chains, divers and rescue craft, and tow the heavy pontoons to the scene, it would have been impossi- ble to bring the boat up in the seventy- two hours that six men had survived aboard her. The first device tried was a set of “pad eves”—huge eyebolts built into the hull—to which the chains of the lifting pontoons could be shackled with- out tunneling under the sunken boat, as is necessary when chain slings must be passed around the hull. It took ninety minutes to attach the first of the four chains. After the two forward chains were fastened, water bal- last was blown from one of the side tanks to make the submarine list over at an an- gle of twenty-five degrees, so that one of the after pad eyes was almost buried in the mud and the other elevated on the sloping side of the craft. This was done to test the ability of the divers to reach the eves under adverse conditions. De- spite the change, the two after chains were ati to th: po se} ins of thi

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Clarence Knight and George Boone, Two of the Divers on the “‘Ortolan,” Submarine Rescue Ship of the Pa- cific Fleet; the “Ortolan” Can Put Twenty-Four Divers over the Side at One Time attached in about the same time as those to the forward eves. The submarine rescue ship “Falcon” then began blowing the water out of the pontoons and flooded compartments by sending down air at high pressure, but instead of coming up, as expected, the bow of the submarine broke the surface while the stern remained on the bottom. After a consultation, it was found that two errors in designing the rescue devices were to blame. One was that the single air line was forked in order to supply the three main ballast tanks, and the second was that the escape vents for water in both forward and stern compartments were all placed at the forward end of the sections. With the boat resting on an uneven bottom, the bow being higher than the stern, the air line could only force out a certain amount of water in the stern, and too much remained to restore buoy- ancy. The navy experts decided that indi- vidual air lines, as built in the navy’s new V-class submarines, and the location of forward vents at the forward end of for- ward compartments and after vents at the aft end of stern compartments would solve that difficulty. Following the first experiment, the sub- marine was towed to Key West, where tests will be continued in warmer waters. One of the first things to be tried there is a submarine diving bell, built to fit a special escape hatch on the deck of the submarine. The hatch is provided with a coaming over which the diving bell comes to rest, forming a watertight joint. The divers descending inside the bell can guide it into place and then open the es- cape hatch and take a number of the crew into the bell. It was estimated that three hours would suffice to rescue forty men. Another form of escape, is the concen- tration of all the available air in the sub- marine in one compartment by flooding the others, to provide a reserve supply for the crew while they don the navy’s new rescue helmet, called a “lung,” and escape singly through a special hatch. The lung is a small face mask attached to an air supply in a container that closely 361

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362 POPULAR resembles a rubber hot-water bot- ble. Experiments already made show that even inexperienced men can rise 155 feet without dis- comfort, and without suffering from the dreaded diver’s cramps, or “bends.” Simultaneously with the “S-4” tests, experiments started with the old submarine “Defender,” one of Simon Lake's early boats, which has been rebuilt as an un- der-sea salvage boat As rebuilt, the “Defender” has an air lock on the underside of the bow through which a diver can reach the water. The first experiments were made in raising a sunken pontoon, but it is planned to carry out thor- ough tests with a submarine. The “Defender” will be able, the builders believe, to drop to the bottom alongside a sunken craft and send over divers to couple on air lines or hook on lifting chains much faster than it can be done from the surface. Lying on the bottom, the boat will be independent of weather conditions. MECHANICS Navy experts are generally agreed that most attention should be devoted to sup- plying fresh air, and, possibly, food, to the entrapped men, and effecting their escape to the surface, before tackling the prob- lem of raising the sunken craft. The first test of the pad eyes on the “S-4” demon- strated that, while they would save days or even weeks of effort in bringing the sub to the surface, there is still small chance of collecting the pontoons and rescue gear, reaching the scene of an accident, and get- ting the submarine up before the crew had died from lack of air. A Diver on the Stage, and Henry Lotz with His Model Hook and Pontoon Which Eliminates Divers Entirely rescue crews on the east coast were experimenting with the “S-4

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Sailors Preparing to Sink the Pontoons to the “S-4,” and, Below, Pointing to the Indi- vidual-Compartment Air- Line Valve, to Which the Hose from the Res- cue Ship Was Attached to “Blow” the Submarine POPULAR MECHANICS Sailor, on Right, Holding to One of the Pad Eyes Built into the “‘S-4’s” Hull

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364 POPULAR MECHANICS out on the “S-29’s” hull with a hammer. With the spot well marked, the rescue ship anchored directly over- head, lowered hose lines, and the divers prepared to couple on to the valves in the hull. Eight hours after the submarine had submerged, Lieutenant Karns, looking through the eveport of his con- ning tower, saw a diver clamber along the deck and through the _ face- plate of his helmet rec- ognized Diver Knight, a Sioux Indian. Knight sa- luted and began coupling on the first hose. A mo- ment later the submarine crew heard muffled words as another diver ex- pressed his heated opin- ion of a balky coupling. Within a few minutes the “Ortolan” was ready to send down air, or use the hose lines to furnish ’ Diver in the Recompression Chamber, Preparing to Test an “Artificial Lung,” fresh water or hot soup. Which Has Proved Practical at Depths of 155 Feet The “S-29’ had eleven and “Defender,” a successful attempt at supplying both fresh air and food to a crew on the bottom was carried out by the Pacific fleet off the southern California coast Special valves, developed under the direction of Rear Admiral Ridley McLean, were installed in each compartment of the “S-29,” and the submarine then put to sea. Acting the part of a surface ship which had rammed a submarine, the sub sent out a radio call for help, giving its position, and then dived and came to rest on the bottom in ninety feet of water. Ten miles away, the rescue ship “Orto- lan” received the radio call and steamed at full speed to the position given. As it approached, an air “slick” was sighted. The “Ortolan” put out a pair of motor launches equipped with sweep wires and grapnel, and while they patrolled the sea, the listening device down in the bow ot the rescue ship began to signal the sub- marine Back came a code reply, tapped hose connections. In a report of the bureau of construc- tion and repair, the tremendous difficulties in the way of any form of special appa- ratus is emphasized. Unlike a surface ship, a submarine is a delicately balanced thing in which the available buoyancy, when operating submerged, 1s practically zero. To add equipment means that some- thing else must be taken out. In the building of new submarines, it is possible to assign any desired proportion of weight to the necessary rescue equipment, but when it comes to re-equipping the existing ships, the problem is entirely dif- ferent. Part of the weight of the rescue equipment can be compensated for by re- ducing the weights in the ballast keel, but any such reduction cuts down the reserve stability of the ship, and therefore in- creases the danger to both submarine and crew, making an old refitted sub actually more dangerous than one without the new safety devices. Qa — — a

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id POPULAR MECHANICS 365 Twenty-Passenger Metal Monoplane with Its Wide Cabin, Shaped like the Wing Itself, to Afford More Room for the Occupants and Decrease Air Resistance METAL PLANE WITH WIDE CABIN CARRIES TWENTY PERSONS A cabin, fourteen feet wide and having accommodations for twenty passengers, is one of the chief features of an all-metal monoplane which has been designed for fast service between New York and Chi- cago. The broad, flat shape of the cabin, conforming to the pattern of the wing, is expected to contribute to the ship’s sail- ing qualities. The plane has two motors of 650 horsepower each; its landing wheels fold up into recesses in the bottom of the cabin while in flight, to decrease wind resistance, and a powerful hinged searchlight, which may be adjusted to different angles, has been installed in front to aid in night landings. A speed of 175 miles an hour is expected. The plane has been designed to afford pilots and passen- gers exceptionally unobstructed vision. INDIAN SCARED BY EARTHQUAKE RETURNS STOLEN TREASURE Because an earthquake frightened an Indian excavation worker, helping British scientists uncover Maya ruins in Hon- duras, the British museum is now the owner of a prized death mask that it other- wise might not have received. The mask had been stolen by the Indian while his Overseers were not watching. That night, a severe earthquake occurred. Thinking that the gods were angry with him, the worker confessed the next morning and handed the mask to his superior. The relic was discovered in a grave and repre- sents a high degree of craftsmanship, IODINE INJECTOR FOR TEETH TO ELIMINATE PULLING To cure abscesses and so make it un- necessary to pull teeth afflicted with them, a southern engineer has devised an in- jector which drives iodine far down into the roots of the affected member. It is compactly constructed and has been suc- cessfully tested, according to reports. Injector for Forcing Iodine to the Roots of the Teeth in Order to Cure Abscesses

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366 POPULAR MECHANICS MILE-LONG TRAINS GO BY FERRY TO CUBA Ninety-five freight cars, enough to make a train a mile long, can be carried at one time in a huge ferry recently placed in operation between New Orleans and Ha- vana. The craft is nearly 430 feet long, has a beam of more than sixty-three feet and differs chiefly from other units of its kind in that cars are car- Mowing “Grass” from the Bottom of the Sea; Cutter Which Clears Kelp ried throughout the from the Los Angeles Harbor in Operation “LAWN MOWER” FOR SEA KEEPS OCEAN HARBOR FREE The floor of the Los Angeles harbor is kept free from kelp by means of a marine “lawn mower” with blades on an endless chain. The growth is cut and ground for stock food after being dried. “WHEN IS IT REALLY COLD?” SCIENCE ASKS In Siberia, the mercury commonly goes down to ninety degrees below zero dur- ing the winter; test balloons, sent to high altitudes have recorded temperatures four degrees colder, and sixty degrees below zero is not uncommon at the poles. Much lower temperatures are reached in the laboratory. In the production of liquid air, a mark of 320 degrees below zero is reached and liquid hydrogen has a temper- ature of 422 degrees below. Articles such as pieces of metal, paper, meat or other solids are shattered like china by a slight blow after they have been plunged into a vessel of liquid air, What scientists re- gard as the ultimate degree of coldness is the absolute zero, 459.6 degrees below the familiar zero of the Fahrenheit thermom- eter. Such is the cold of space through which the earth and other planets move. Atmospheres shield many from this ter- rific cold, but the mark is reached on the dark side of the moon, although boiling temperatures are experienced during the day on the side turned to the sun. holds, between decks and on the superstructure, instead of only upon one deck. The loaded cars are handled by an immense crane at each terminal. The ferry will take about fifty- two hours for the transit between the two ports. “MOUNTAIN” BUILT OF SPOONS FOR FAIR DISPLAY One of the most attractive exhibits at the Leipzig trade fair in Germany was a huge mound of 25,000 spoons. The dis- play represented passageways, tunnels, A Mountain of Spoons; Interesting Display Con- structed for the Leipzig Trade Fair foliage and other details, all worked out in spoons.

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POPULAR MECHANICS 367 RADIO ‘LOCATES ORE HUNDREDS OF FEET IN EARTH Transmitter and Direction- Finding Apparatus, Two Essential Parts of the Radio Outfit Used in Prospecting for Ores; It Has Lo- cated Veins 500 Feet Deep Prospecting by radio has been simpli- fied by the introduction of improved ap- paratus, which already has located veins of ore to a depth of 500 feet. Trained en- gineers are required to operate the outfit, but it is not difficult to handle, and its accuracy has been tested repeatedly. It employs the principle of electromagnetic induction. An electromagnetic field is sent out from a transmitter to a depth of several hundred feet. If an ore vein is within the radius of the field, a current is set up in the conductor, which, in turn, sets up a secondary field, and this is de- tected by direction-finding apparatus. By further observations, the extent of the ore vein is determined. The outfit consists of a radio transmitter, a power box and the direction-finding set. A crew of four men is generally employed with it. This method of radio prospecting is not in- tended for hunting lost treasures or small quantities of minerals, but for locating ore veins or bands of minerals and to pick up lost veins due to faulting. It does not de- termine the type of ore or the quantity of it, although it does show its depth and the length of the veins. The method is being used widely in Canada, where weather conditions and the roughness of the coun- r try make ordinary surveys difficult. The radio prospector can work in snow or rain, as his apparatus is not affected by these elements. POCKET ATOMIZER FOR SCENT FITS VANITY BAG A pocket-size atomizer, using a plunger pump instead of the bulb arrangement, has been placed on the market in Ger- many and likewise patented in the United States. The device, about the size of the usual lipstick con- tainer for the vanity bag, is finished in gold, leathers and snake skin, in va- rious styles. The top pushes in, to eject atomized per- fume through a small nozzle in the side. To close the nozzle after use, the pressure on the top is released, caus- ing a spring to push the top out and seal the vent.

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368 POPULAR X-RAYS DETECT ART FAKES BY REVEALING AGE Studying a Painting before Subiecting It to X-Rays, to Test Its Genuineness Spurious paintings are sometimes de- tected by X-rays which show a difference in the structure of new and old materials. For instance, an old painting has been re- touched by a modern artist to make it resemble the work of a recognized master, or some other method has been followed ‘to disguise a subject. If materials of widely varying age have been employed, the difference is likely to be detected by the penetrating rays and the photograph that is taken with their aid. If a recent painting is reputed to be old, the fraud can often be discovered by the X-ray com- parison with a genuine ancient painting. MYSTERIOUS TUNNEL IN CHINA MAY LEAD TO TREASURE Discovery of a mysterious tunnel, seven feet high and a yard wide, in a hill near Nanking, China, has interested explorers, as the passage, they believe, may give a clue to the whereabouts of a great treas- ure, buried 500 years ago with the coffin of the first Ming emperor. The secret of the horde of gold, jade and jewels en- tombed with the ruler has puzzled gen- erations of historians and treasure seekers. When the emperor died, Nanking, his capital, had thirteen gates. Through all of these, coffins were borne simultane- ously, and thirteen tombs were erected MECHANICS at as many different places, it is recorded, so that his enemies and treasure hunters might be baffled in their search for his remains and the hidden gold. The tunnel is lined with blocks of stone and was found by workers constructing a new road. BEAUTY IS TRACED TO LONG USE OF THE JAWS Constant use of the jaws, during a period of millions of years, has been largely re- sponsible for the beauty of the human face, according to Dr. Martin Dewey, an eastern authority. He declares that the use of the jaw muscles has caused part of the development of the underlying struc- tures of the face and that the exercise of those muscles has contributed to the broad- ening of the skull with the consequent increase in the size of the brain chamber. FLUID MASK KEEPS LACQUER FROM CAR WINDOWS To protect glass and other surfaces from being spotted or streaked while applying lacquer, a fluid mask has been introduced. It is applied to the area which is to be shielded, dries and hardens quickly and is then peeled off when the lacquering or painting is done. The mask may be painted or lacquered over without danger to the surface beneath. As shown in the accompanying illustration, a film or mask Car Window Has Been Lacquered Over, But Is Kept Clean by the Mask Which Peels Off is being removed from a car window. The material is also used in striping or other forms of decorative work, the design be- ing cut through it and the lacquer or paint then brushed over the entire surface.

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oo = eae Se POPULAR MECHANICS 369 TRANSPLANTATION OF TREES AIDED BY DRUGGING That trees react to chloroform and other drugs in somewhat the same manner as do ani- mals, is the report of an English naturalist who believes that trees have many powers not com- monly associated with them, such as the ten- dency to be attracted or repulsed by the presence of human beings. He points out that fyll- grown trees with muti- lated roots have been successfully transplanted after they had been put under the influence of certain drugs, whereas other trees, not treated, died. Their response to human beings, he de- clares, can be indicated by various instru- ments that are attached to them to record their reactions. An outstanding example of “nerves” in vegetable growth is the sensitive plant which shuts its small leaves tight at the slightest touch. This action is suspended when the plant is drugged. NIGHT TRAIN SIGNAL ON TRACK PROMOTES RAIL SAFETY So that trains Speedy Motorboat of Improved Design, Showing Arrangement of the Engine to Afford a Low Center of Gravity SPEEDBOAT MOTOR LIES FLAT TO LOWER GRAVITY CENTER Cylinders, and other parts of a specially constructed motor for a speedboat, lie flat so that the center of gravity of the craft is lowered to six inches above the water line. The arrangement of the cylinders is also said to equalize the strain more nearly than is done by other motors. This particular craft, with all the care and thought expended in its construction, proved a failure because of an unfortunate accident. In a test run of seventy miles may be able to sig- nal their approach at a considerable distance down the the track, on sec- tions where ordi- nary block systems are not in use, a special warning de- vice has been intro- duced. It is at- tached to the rails and affords contact with a passing train whereby another signal is shown at a point farther down the line. The sys- tem is intended for an hour, a hole was broken in the bot- tom of the hull when the boat leaped from one wave to another, It sank and divers spent fifty hours be- fore they could lo- cate and raise it. After repairs, oiling troubles developed, and the pilot had the disappointment of seeing the race won by a motor- boat that developed far less speed; in fact, something un- der fifty miles an service at night. Railroad Track-Signal Unit That Gives Notice of Ap- proaching Trains at Night hour.

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The 1,000-Horsepower Sunbeam Car in Which Maj. H. O. D. Segrave Set a Record of Nearly 204 Miles an Hour at Daytona Last March, Only to Have an American Break It M~*: H. O. D. Segrave is coming back to Daytona Beach to try and regain his lost speed laurels, this time with a thousand-horsepower car designed to travel at 240 miles an hour, with a possi- ble maximum speed of 260. Flight Lieut. D. D’Arcy A. Greig, of the British royal air force, on Nov. 4, flew a seaplane with the same kind of engine over a measured course at 319.57 miles an hour, slightly better than a mile an hour faster than the speed record held by Maj. Mario de Bernardi, of Italy. Gar Wood, down in Florida, is prepar- ing to tune up “Miss America VII,” with which he made a world’s record of 92.834 miles an hour last September, and will go out to try and boost the speed record on water above 100 miles an hour, as the boat is expected to make 105 to 107 miles when properly tuned. And a pleasure car has just been shown at the New York auto salon, which, with a touring top and windshield up, does 120 miles an hour in high gear and ninety miles an hour in second speed. What have these four events to do with each other? Three or four years ago, it was gener- 370 ally said that the automobile had about reached the ultimate in development, and any future changes would be in the na- ture of little refinements in equipment and body appointments, rather than major de- velopments. Some manufacturers had be- gun to advertise the fact they no longer made yearly models, and, save for an occa- sional sport roadster, cars generally had come to look very much alike, in the same shades of blue or done in sober black. Just about that time the speed field produced the small, eight-cylinder engine; engineers turned out the four-wheel brake and balloon tires; color experts produced spraying lacquers in bright colors; body designers got some new and original ideas, and in a space almost of months, the automobile had been revolutionized. As usual, the major engineering devel- opment turned up on the speedways long before it was adopted for general use. Eight-cylinder engines of small displace- ment were proven at Indianapolis, At- lantic City, Los Angeles and on other speedways. It is interesting to note that one of the leaders in their development, Fred Dues- enberg, has gone back to the big engine in

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© The Motor Major Segrave’s “Golden Arrow,” Steered by Rifle Sights, Built to Make a New Attempt to Regain the World-Speed Crown for England at Daytona Beach This Year his latest car, a 265-horsepower job that, with touring body, has done 120 miles an hour on the road’ The big engine, with three and three-quarter inch bore and four and three-quarter stroke, has a dis- placement of 420 cubic inches, as com- pared with the little ninety-two and a half cubic inch racers. At 4,200 revolutions per minute, the engine develops 265 horse- power, and when driving the car at ninety miles an hour in second gear, it turns up to 5,200 r.p.m. Two men led in the revolution in car design which associated bright colors with good looks, luxury appointments and more speed. One was Walter Chrysler, and the other E. L. Cord. Mr. Cord was twenty-nine years old when he took over the Auburn plant in 1924. While Mr. Chrysler had come into the automobile business by way of a railroad machine shop, Mr. Cord had grown up with auto- mobiles, being successively proprietor of a wash rack on the coast, part owner of a desert trucking outfit, salesman of used and new cars, manufacturer, at the age of nineteen, of rebuilt and “hotted up” Ford racers, and automobile salesman and distributor in Chicago and Milwaukee. Bright colors and bodies that “look dif- ferent,” he maintains, were a natural de- velopment. “Color was coming into the daily life of everyone, along with modernistic de- sign,” he says. “Furniture of radically new style, decorated in bright lacquers, was finding a vogue. Drapes and other decorations in the new colors were replac- ing the more somber furnishings of the past. Clothes were brighter. You only have to look at the shirts and collars men wear today and recall what they wore four or five years ago to appreciate the change. “We started out to make a car that would look different, on the theory that there are enough people who will pay for something that is a bit different from what the neighbors have, to make their busi- ness worth while. When we created the new mold line in the hoods of our cars, 371

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372 there was a serious question whether the public would like it. Some people didn’t, but a lot did, and even those that didn’t talked about the Auburn, for we had a distinctive appearance that made the car attract the eye. “That little mold pressed into the hood and the distinctive two-tone color com- binations were the outward symbols of the change, but we made a lot of others POPULAR MECHANICS lutionize automobiles is a study of what the customer wants, the things he com- plains about, and the things he asks for. We try to build the kind of cars cus- tomers want, rather than the kind engi- neers think they ought to have. I found in my car-selling days on automobile row that a lot of complaints that were made could have been avoided by little changes that might have cost no more than a few cents per car. Engineers usually are stubborn about making such changes because, in their driv- ing, they do not need them. They know their cars and drive them carefully, and don’t always realize that the average buyer is not an expert.” One of the developments which Fred Duesenberg’s New 265-Horsepower Engine and, Right, the “Shimmyless” Spring Shackle Developed by Packard that didn’t appear at the first glance. The trouble with so many automobiles is that they are built from blueprints, and look it. I am not an engineer, and when engineers come to me with a set of prints and say there is enough leg room under this in- strument board, and that this rear door is wide enough for even an extra-plump woman to get through, they may be right, but I want to know that they are. “So we build up full-sized body models out of wood and clay, complete to the last bit of decoration, and we study them. We fit them out with seats and dummy steer- ing column, and doors that work, and I can climb in and try the leg room myself. We studied what the women wanted, and as a result put the starter button up on the instrument board, where you don’t have to hunt around for it; moved the light switches to the steering column, where they are .easily accessible, and switched to a big rubber-covered acceler- ator pedal that wont scuff or mar the leather on a pair of fancy slippers. “Another thing that has helped revo- the modern trend in design is going to emphasize in the coming year or two is lower and more perfectly streamlined cars. The bureau of standards has discovered that, if cars were as perfectly streamlined as airplanes, their speed would be dou- bled, with no increase in power. Speed of stock cars is determined almost exclu- sively by the resistance offered by the air. A car with a speed of fifty miles af hour would have to have eight times as much power to make 100 miles an hour, with no changé in the body. The trouble with streamlining has been that a perfectly designed body would be so futuristic that few motorists would care to buy it. The new racing car being brought over by Major Segrave, called

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Ig POPULAR MECHANICS 373 © 8. W. Clatworthy The World’s Premier Speed Plane, England’s “‘S-5,” Which Won the Schneider Cup and Has Traveled Faster Than Any Other Ship; the Insert Shows the “S-4,” Its Predecessor

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374 POPULAR MECHANICS Proven on the Speedways in Recent Years, Harry Miller’s Front-Wheel Drive Is to Make Its Appearance on a Stock Car Shortly; It Permits Even Lower Bodies ’ the “Golden Arrow,” is one of the finest streamlined bodies yet made. The car is so fast that it is to be steered by sights, just as a rifle is fired. Two huge bull’s- eyes will be erected above the course, and . the pilot will “aim” his car at the first, and as he passes under it pick up the sec- ond. At 240 miles an hour, his estimated speed, the car travels four miles a minute, or the length of the mile course in fif- teen seconds. The slightest wavering from a straight line might carry the car into the sea before the driver could cor- rect it. It is impossible, according to Major Segrave, to steer by ordinary ob- jects, as the flags marking the course be- come a blurred line and the timing posts are too far away at the start, which must be made four and a half miles away in order to get up full speed. One major development of the speed- ways, which is to appear this year on a production passenger car, is front-wheel drive, following the system proven by Harry Miller’s racing cars in recent years. While the car which is to employ it has not been named or built, it is understood the designs call for an exceptionally low car, with streamlined body closely resem- bling, in some models, the fuselage of a cabin airplane. One model is reported to be but fifty-eight inches high—two inches less than five feet—yet has sufficient head- room for tall people. The front-wheel drive proved excep- tionally safe on the speedways. It gets the power back where the horse used to be, pulling the load, and as a result, the car can take sharp turns at higher speed, climb over obstacles, and is claimed to be The New Duesenberg’s Instrument Board Includes Brake-Pressure Gauge, Tachometer, Altimeter, and, in the Corners, Four Telltale Lights to Warn When Attention Is Needed an Ol CU CU ee Oe a ee

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POPULAR MECHANICS 375 Ed : “s . ie we call Capt. Malcolm Campbell’s “Blue Bird,” Which Uses the Mate to the Twelve-Cylinder Napier Engine That Won the Schneider Trophy in the Plane Shown on Page 373 generally safer. Engineers have often contended that the proper place to apply the power was as close as possible to the point at which it was generated, but with rear-wheel drive this meant moving the engine to the back, with a resulting body design so radically different that it would not be acceptable to the average driver, accustomed to a long hood projecting in front of him. The return of Duesenberg to a big en- gine probably marks the end of experi- ments with superchargers for small high- speed motors, at least for general use. The supercharger proved inefficient at the average operating speed of pleasure cars. The new Duesenberg, with its high power, is designed for quick acceleration in traf- fic, rather than for exceptionally high speed in ordinary use. It has a gasoline consumption of seventeen miles to the gallon at twenty miles an hour; eleven to fourteen miles, at forty miles an hour, and four miles to the gallon at 104 miles. One of the most interesting things about the car is an automatic system of chassis lubrication, which functions every seventy miles. A telltale light on the instrument board indicates whether or not the oiler pump is working, and another light in- dicates when the reserve oil tank is empty. Another pair of lights come on, one every 700 miles, to tell when it is time to change the oil in the crankcase, and the other every 1,400 miles as a signal to fill the bat- tery with distilled water. In addition to the usual instruments, a speedometer cal- ibrated to 150 miles an hour, ammeter, and oil and gasoline gauges, the instru- ment board has a pressure gauge for the hydraulic four-wheel brakes, an aneroid barometer to indicate altitude, a tacho- meter to give engine speed, and a clock. The engine has four valves to each of the eight cylinders. It also is equipped with a vibration dampener consisting of two cartridges, each containing a pound of mercury. Practically every part of the chassis except the frame, parts of the mo- tor and the spokes and rims of the wheels are chromium-plated. @The Popular Mechanics’ Bureau of In- formation offers its free service to all readers of this magazine. Names and ad- dresses of manufacturers and dealers in articles described, and any other details in our possession, will be promptly furnished,

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376 POPULAR MECHANICS FLOAT BRIDGE SPAN INTO PLACE TO SAVE LABOR ott gg s sae” om ny One of the Huge Spans of French Bridge Being Floated into Position; It Is Nearly 600 Feet Long, the Chief Link in the Structure, Which Reaches a Mile across the River Elorn at Brest In constructing a mile-long bridge across the Elorn in France, a huge span was built at a distant point and floated into position. Although the task was a dificult one, it was considered simpler than forming the span in the usual man- ner. Each span is nearly 600 feet long. The bridge will serve the city of Brest. ELECTRIC TRAIN OBEYS VOICE TO START AND STOP AIRPLANES OF SLOWER SPEED DEMAND OF AVIATION Development of airplanes capable of slow speed is necessary for the promo- tion of civil aviation, according to Lord Thomson, former secretary of state for air in Great Britain. He points out that the high speed of military craft is not nec- essary for commercial flying; that slower speed and safe operation at lower alti- tudes would promote the security factor in flying, and that Spoken com- mands govern the movements of a model electric train demonstrated in New York. The word “Stop” brings the engine to a halt; “Back Up” causes it to reverse, and some such phrase as ‘‘Get Along There” will cause it to go for- ward. The action is the result of the vi- brations of the such planes would become increas- ingly popular among businessmen and others who would use them for distances of 150 miles and less. Greater economy in operation would also be possible for slower craft, it was suggested by Lord Thomson, who was the chief of the British delegation to the recent aero- nautic conference voice through a mi- crophone. Testing Model Railway Which Obeys Voice at Washington. thr roc ant ear hu: mil bu tha mai lect var rou wo! velc the tacl

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POPULAR MECHANICS 377 EARTH’S INTERIOR NOW KNOWN TO SCIENCE With the aid of special instruments, scientists have been able to ex- plore the inner earth to a depth of 2,000 miles and more, according to Dr. Bailey Willis, retiring president of the Geologi- cal Society of America. The latest findings indi- cate, he said, that there are two parts of the earth, an envelope 2,000 miles thick which con- sists of elastic rock, and a core that is 2,000 miles in radius and evidently unelastic. This core is exceedingly hot and may be molten, but it is slug- gish and viscous because of the tremendous pres- sure of the outside en- velope upon it. Doctor Willis has advanced the theory that continents are formed by “blisters” which occur as the heat from the core of the earth, unable to pene- trate immediately through the envelope of rock, is sent sideways and forms, beneath the earth’s surface, an immense blister several hundred miles wide and more than twenty miles deep. In time, these blisters have burst through the surface with the result that the land areas have been formed. FIRST AIR-MAIL ENVELOPES PRIZED BY COLLECTORS Envelopes used in the first run of air- mail lines, are in great demand among col- lectors. Good prices are received for some varieties, and whenever a new air-mail Toute opens, collectors throughout the world arrange to obtain some of the en- velopes. They are doubly valuable when they have special air-mail stamps at- tached to them. Watch Tower near Village on Mediterranean Coast, Where Observer Seeks Schools of Fish with Telescope and Relays Word by Telephone LOOKOUT ON TOWER FISHES WITH TELEPHONE Near a small village on the Mediterra- nean coast is an odd-looking steel frame- work, supported by braces and leaning far‘out over the water. At the upper end, in a small cage, stands a man with a tele- phone at his side. He is a watcher, on the alert for schools of fish that can be seen at some distance from his lofty elevation. When a school of fish is sighted, he tele- phones to the village and the men hurry to their nets and boats. @ During calm weather, the average speed of the worker bees’ flight is a little less than fifteen miles an hour,

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eee eee cel Looking through a Wind Tunnel; in the Background Is a Model Plane, Mounted in the Test Chamber Ready for Measurement, and in the Foreground the Propeller That Furnishes the Gale 378

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Oo By A. M. JACOBS 'T WAS flyers’ weather, clear of sky, winter snap in the air, and a sun that penetrated even heavy flying togs. The air above Uncle Sam’s big mid-west test field was full of roaring craft. Two parachute planes were making test drops of the mammoth silk parasols from low altitudes. A target glider spiraled down from 3,000 feet, the big DeHavi- land to which it had been attached following it, a photographer in the rear cockpit grinding out mo- tion pictures of its ma- neuvers. At 8,000 feet, a twirling point of light in the sun, a plane being put through a series of spinning tests. A huge bomber left the earth, none too briskly with its heavy load, but soon was climbing, its great wing sharp against the blue. A supercharged altitude plane, due for a climb to 25,000 feet, had engine trouble at 17,000 feet, and came down, the pilot hedging carefully into the field with a dead stick. Low over the speed course, an observa- tion plane was skimming The Army’s Flying Radio Laborator Tri-M : ‘ y, a Tri-Motor Fokker, Top, and the " Interior of the Experimental Cabin Where New Radio Ideas Are Tested with steady speed. under Actual Flight Conditions All test flights! Either 379

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380 POPULAR MECHANICS the planes themselves new and experi- mental, proving their worth to serve as standard in the U. S. army air corps, or some special equipment in them on trial. Almost everyone carried a story of adven- ture or daring on the part of the flyers who do the testing for Uncle Sam, and whose reports are determining factors in gauging the value of the articles in ques- tion to the service. And these flyers? As the sun dropped low in the winter sky, they landed the planes and drifted into the flight office. They are a physically fit, capabie-looking group of army officers, most of them come into aviation during the war. Big planes little planes, swift, light, sensitive, pur- suit planes, heavy bombers, only a man with skill and daring at flying all types can be admitted to their ranks. Even then it takes about six months to become efficient in the various types of testing. A pilot new to the work may think he is coming along magnificently, but quite fre- quently, unknown to him, one of the others is repeating his tests to be sure of getting correct results and also to learn just how accurate and dependable as a test pilot he shows promise of becoming. Day after day, they take into the air new and experimental types of planes, or old planes equipped with new and untried installations, sure to effect the flying qual- ities to an uncertain degree. Purposely they throw a plane into all the maneuvers into which it might accidentally slip in flight, in order that they may study its be- havior under each condition and may know whether it is going to respond to the controls for the pilot throughout the service. Usually they can place a fault and it is corrected. If the fault cannot be corrected, the plane never reaches the service, and in learning that it is not fit, the pilot must now and then save his life by parachute—or lose it. Such a tragedy occurred at the field about two years ago. One of the test pilots had thrown an observation plane into a spin, which developed a strange Lieut. Leroy M. Wolfe and Capt. P. S. Edwards in the Flying Laboratory at Wilbur Wright Field; Experi- mental Work Is Carried On While in Flight, to Test Radio Beacons, Two-Way Voice Conversations, Long and Short-Wave Code Transmitters and Receivers, and Various Types of Radio-Operated Signals vici whi poss repc in c ing, a sé plan find simi kno mid Poc long sout resp able chie the test upo his and wou tery side test: and cam fore clim mar nos tion Liet unr jum him he I air, that viol whi letti G and out dale one lar | a Pp: has only

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ied the ult not the fit, life eld test ane nge peri- ong POPULAR MECHANICS 381 vicious flatness from which it was almost im- possible to level out. He reported this experience in conference next morn- ing, and, as is customary, a second pilot took the plane up to check the finding. He brought in a similar report. Lieut. E. H. Barksdale, better known as “Hoy,” his middle name, or “High Pockets,” because of his long-legged slimness, a southerner, much loved for his sunny temper and respected for his remark- able flying ability, was chief of the test pilots at the time. None of the test pilots is ever called upon to do anything that his chief would not do, and Lieutenant Barksdale decided that he would be the third to investigate the mys- tery and see if he could fathom its cause. Taking the plane up to 6,000 feet, con- sidered a safely high altitude for such tests, he pulled the nose up into a stall and kicked on right rudder. The plane came to 2,000 feet in a flat right spin be- fore he could level it out. He started climbing again to learn if it was as un- manageable in-a left spin. This time the nose rose flatly out of control, the gyra- tions developing into a maddening speed. Lieutenant Barksdale, struggling with the unresponsive controls, knew he’d have to jump for his life. That held no terror for him, however, for it was not the first time he had to escape a doomed plane in mid- air. But the force of the spin was so great that, in leaving the plane, he was thrown violently out into the wing-brace wires, which sheared the cords of his parachute, letting him fall free to the ground. Grief went broadcast through the field and the great company of flyers through- out the country, for the like of Hoy Barks- dale was not often found. For a time, no one cared what happened to that particu- lar plane and its spins. But there it was— a problem and a mystery—and aviation has achieved its present degree of safety only because problems have been unflinch- Ready for a High-Altitude Test, with Report Books Strapped to Their Knees and Stop Watch Hung about the Neck ingly tackled and mysteries ferreted out. Attempts were made to solve this one in the wind tunnel with small models of the plane. But the wind-tunnel test results did not explain the behavior of the planes tested, since there was not in existence sufficient information on spinning upon which to base sound theories. The thing would have to be fought out in the air. About this time, Lieut. Harry Sutton, who had been much interested in the project from the first, volunteered to at- tempt a solution. The flat spin developed, it was fairly certain, only when the plane was carrying military load. Therefore it seemed reasonable that if the -equivalent of this load could be carried in droppable form, such as bombs, and the plane went into one of those irrecoverable spins, he could drop the load and bring it under conttol once more. There was no surety that this was so, of course. It was a highly experimental proceeding. There was, too, a second purpose to the movable load; he would change its position, move it backward and forward on the fuselage center. They would experiment and find out, if possible, in just which location it most affected the spinning characteristics. So quietly did Lieutenant Sutton go about his preparations, so quietly embark on those first hazardous flights, that the

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382 POPULAR MECHANICS majority of people on the field were un- aware of the courageous task being un- dertaken in their midst. For more than a year, he made flights to 10,000 feet, his plane a mere twirling point of light in the sun as it came down the sky. But the moving-picture camera on the ground, equipped with a special telephoto lens, which photographed the spins in order that the engineers might study them thor- oughly, accurately, and repeatedly, regis- tered sometimes as many as twenty-two successive spins before the plane leveled out. Often the weight had to be dropped before Lieutenant Sutton could regain control. Once the same swift flatness of spin that had thrown Lieutenant Barks- dale into the wing, threw a bomb, upon release, through the wing fabric, tearing a great hole. Those watching expected him to jump then, but he brought the plane in, making a breath-taking landing at ninety miles an hour. After that, for the bombs they substituted tanks, the bottom of which could be opened at will, and they placed in the tanks the equiva- lent of the load in shot, which would fall through the bottom of the tanks when released. The information on spinning garnered by Lieutenant Sutton as “just his job,” has proved invaluable, and the whole project has been regarded proudly by older flyers as a daring piece of special test work performed with .thoroughness and intelligence. Back in the flight office, they are not discussing the spinning tests of today, however, for the solving of a more recent puzzle has taken their place. Earlier in the week, a test pilot new to the ranks brought in a complaint of something wrong with a new bomber he had been flying. When you moved the rudder, he complained, everything else in the ship moved along with it. The older men smiled. Among themselves they were in- clined to believe that the youngster al- though a seasoned flyer was probably not familiar with the severe vibrations set up in flight in that particular experimental ship. They would check the report. One day they went up—three of them; one to pilot, one beside him to watch the forepart structure, and one behind to observe the rear. At 2,000 feet, the pilot started the test by seesawing on the rudder bars, Immediately there was an _ alarming distortion of the whole plane. The youngster was right. This was some- thing more than vibration. He tried it again, the observers searching about dili- gently. After several repetitions, the ob- server in the rear cockpit suddenly, in the language of the small boy, “threw a. fit,” looking scared and point- ing to the left longeron. Undoubtedly he had found something. The pilot started to fishtail once more, to enable him to check observations thoroughly, whereupon the observer almost went wild, pointing again to the longeron, making mo- tions as of snapping 4 stick and gesturing for a landing. It then dawned upon the two in front that the rear observer was telling them that the upper-left longeron, 4 main member of the fuselage skeleton, had broken. In that case only the fabric and cowling The Test Pilot Completes His Report Immediately after Landing, While the Details Are Still Fresh strips would be holding the ship intact there. _ aa oi sid the unc ten it ij no wit unc the tect of had thr. nev er’s tere by | hav test ver) plat scat bee: and bee or r had

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10t ay, ent in aks ing een he hip nen in- al- not up ntal One e to part the the ars. ning The »me- sd it dili- » ob- 1 the . fit,” oint- eron. had The shtail > him tions upon went to the mo- ing a for a wned front server at the on, 4 f the had e only ywling olding re.

POPULAR MECHANICS 383

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oe yee me S. i oY ee wen mt W-- -- — - ee oe ee ee a fee ew om Sin - + eee —/S 8 ere tenn H+ teem m= -- -—<——— ee wee 12000ft. _ _ ms Ls = ait = , bate i » MES MB cc: ss i oe — a ° ‘ 9° Hy OSES MB OB: x a <a ,

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Graphic Chart of a Test Flight, Showing How the Plane’s Climbing Speed Is Repeatedly Measured at Va- rious Altitudes All the Way Up to 19,000 Feet Simultaneously they looked over the side to gauge the altitude and sought their parachute rings. But the plane was under full control, and since it showed no tendency to go out of it, the pilot brought it in, in a clean easy landing. But he lost no time and tried no more “rough stuff” with the rudder. The break, which had undoubtedly occurred during the flight of the younger test pilot, had escaped de- tection by the ground inspector because of its location behind the bombs which had remained mounted in the plane through all tests. That topic is supplanted by news of a new plane ferried in from a manufactur- er’s plant that afternoon. All listen in- terestedly to the comments upon it made by the pilot who has flown it in. All will have to fly it, partake in some phase of its testing, give their opinions upon it. A very few years ago, this ferrying of a new plane to the field for flight testing would scarcely have happened. It would have been shipped in, assembled at the field, and a great deal of speculation would have been rife as to whether it would really fly or not. New planes didn’t always. They had been known to refuse to lift, or now and then they had been nose-heavy and come crashing down, or the controls had been improperly balanced and flight in them therefore dangerous. Because of this uncertainty, there had usually been a certain amount of thrill not only in the first flight, but in the pilot, who was some- times named for the job by the chief test pilot, or might be chosen by the drawing of a names from a hat. So far has avia- tion progressed in the last few years, how- ever, that unless a plane represents a rad- ical departure, it is seldom shipped in for assembly at the test field, but receives its preliminary try-outs at the manufacturer's plant and is flown to the field. The question is no longer, “Will it fly ?” That is presupposed. The interest centers in, “How will it fly?” Will it live up to the specifications set down for its per- formance? How convenient are its equip- ment installations, how comfortable is it as a flying vehicle for pilots and crew? Will the power plant in that particular de- sign cause such heavy vibrational charac- teristics in the structure as to cause the fracture of the main supporting member, as discovered in the bomber? Or, if an observation or pursuit type, will it be fully

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384 POPULAR MECHANICS maneuverable and at the same time easily controllable in all possible maneuvers? These fighting planes would be twisted all over the sky in battle and, if they failed to respond to the pilot’s will, he would be lost. The system of inspection and flight testing in force in the army today is planned to answer such questions. The first flight step in this system for a new plane, after a pilot has given it pre- liminary runs to get thoroughly the “feel” of his ship, is taking it over the “speed course.” This is a two-mile straightaway, permanently laid out on the test field, set off by markers and with a long black line down the middle. These tests require more expert piloting than any others flown, for in order that he may safely see the markers, and fly directly in line with the black line, holding his plane at an even level, where the air is quietest, the speed course is flown low—a mere ten to twenty feet off the ground. A calm day is always chosen. Braced steadily in his seat be- hind the windshield, tense against any slightest movement, with one hand the pilot grasps the control stick, with the other, the engine throttle, while a stop watch in one of the hands is held from slipping by having the cord wrapped be- tween the fingers. No chance of escape by parachute should anything go wrong. The pilot could only land, hurtling at the ground, and probably crash. The main purpose of these tests is to calibrate the air-speed indicator, that is to check the time taken to fly the two miles as shown on the air-speed indicator against the stop-watch time, and to learn the plane’s low and high speeds, and its flying qualities at various other speeds. In the high-speed tests, the pilot opens the throttle wide and strikes his level about a mile before entering the course, As he approaches the first marker, he compresses the stem of the stop watch almost, but not quite, to the clicking point. As the forward edge of the wing reaches the marker, he clicks the stem in, starting the hands around, clicking it in again as the final marker is passed. If he has been flying a pursuit plane with the wind in his favor, the time taken to cover those two miles has perhaps been forty- three seconds. The mere flash of an arrow! The course is then flown in the oppo- site direction, The average speed of three of these round-trip flights is taken as the plane’s high speed. A series of round trips follows, each with the same extreme accuracy and care, and each timed exactly ten miles slower than its predecessor, until the plane is moving over the course as slowly as possible, just flirting with stalling speed. This, the pilots call “taking it over the hump,” and it represents the plane’s low speed. With the plane seeming scarcely to move against the background of the great field, this test is quite as picturesque to watch as the high-speed test, and requires as firm and practiced a hand on stick and throttle and as great a nicety of judg- ment. Although not of long duration, each minute on the speed course is one of extreme strain, and it is with a feeling of relief that the pilot finally climbs to safer flying altitudes, preparatory to bringing his plane in and placing the information The Radio Plane at Wright Field; to Keep the Slipstream of the Nose Propeller from Interfering with the Wing Screws, It Has Three Blades, Thereby Making a Smaller Diameter Possible ti al cli he th a th th to th din ot ve fly ere pil the bri cig offi fea ste cor for tin: Var Wo: OF | pre mu can I hig nov Sl E tow kinc tons $106 fooc tries for

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1S el ch 1g ng in he he er ty- an po- of cen of ime ach its ring just the and Vith 10ve ield, atch S as and udg- tion, ne of ig of safer iging ation aA th the POPULAR he has gathered into the MECHANICS 385 ‘ bs hands of the engineers. There are also the “saw-tooth” test and the “check-climb” test, in which the pilot usually goes high enough to meet subzero tempera- tures and to use artificial oxygen; the “oscilla- tions” test, in which by alternate diving and climbing, sometimes with hands off the controls, the inherent stability of a plane is determined; the “accelerations” test, the purpose of which is to learn the stresses upon the plane surfaces in dives, loops, spins, and other extreme maneu- vers of flight. “If it has wings, we'll fly it,” might be consid- courtesy General Electric Co. ered typical of the test Illuminated Fountain and Colorful Background, Showing the Effect of Care- pilot’s attitude toward the ships that come for test. Difficult, brilliant, at times, dangerous work—and a cigaret and banter at sundown in the flight office. Now and then, for some special feat, such as landing a burning plane in- stead of taking a parachute, a letter of commendation slips into the files. And for a mistake, such as bad landing, get- ting lost on a long flight, or any of the variety of personal slips possible in such work, there is the “Dumb Bell Trophy” or the “Alibi Trophy,” or another, which, presented by his fellows, the recipient must keep displayed on his desk until he can find a new offender to pass it to. In the army air corps, Uncle Sam places high responsibilities. Planes may fail him now and then—but his flyers, never! SUGAR FROM PEANUT SHELLS Experiments are being made aiming toward the commercial production of a kind of sugar from peanut shells and cot- tonseed bran. The product sells for about $100 a pound and is useful not only as a food but for textiles and leather indus- tries. A plant has been built in Alabama for its manufacture. fully Placed Floodlights TINTED LENS ON FLOODLIGHT ADDS TO NIGHT DISPLAY Effects that were impossible a few years ago are now attained in night floodlight- ing by the introduction of improved re- flectors and tinted lenses for the lamps. Doorways, fountains and other units are beautifully illuminated during the hours of darkness and at a considerable saving over what would have been required with older forms of equipment. Projectors with clear glass, stippled and colored lenses are sometimes used in combination for special blends and tones. GROW COTTON READY-COLORED TO SAVE DYEING In Peru is a plant that produces cotton of a reddish tint; a yellow cotton grows in China; India produces a gray shade, and, in Egypt, a brownish-colored va- riety is gathered. The plants breed true to type, the colors are fixed and do not change with variations in soil or climate. By crossing suitable kinds, scientists see a way of growing cotton of various hues, dyed by nature and of fast colors.

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is called the “dew point,” the water vapor forms a cloud. Exactly what is the temperature of the dew point depends on the amount of mois- ture in the air. The more mois- ture, the higher the dew point. But no matter how much mois- ture there is in the air and how low the temperature, there can be no formation of cloud and no pre- cipitation unless there are parti- cles of dust or other nuclei about which the moisture can condense into drops. So, in his experiment, Professor Knipp introduces tobacco smoke into a tiny glass tube contain- ing the saturated air which he has expanded. The microscopic particles of matter which form the smoke are large enough for By VICTOR RUBIN ALTHOUGH aftempts to produce rain artificially have generally been re- garded as wild dreams by scientists, two experiments recently conducted by Prof. Charles T. Knipp, of the department of physics of the University of Illinois, have removed the subject of rain making from the realm of the fantastic. Both experiments, adapted from some- what more elaborate tests by C. T. R. Wil- son, of London, winner of the Nobel prize in physics for 1927, reproduce in miniature the conditions present in nature just be- fore a thunderstorm. In both cases, the air is saturated and suddenly expanded. And then, in the first experiment, minute particles of dust, in the form of tobacco smoke, are introduced. In nature, this expansion takes place when the moisture-laden air is warmed and rises from the earth’s surface. As it ascends, it gradually cools—one degree for every 300 feet. When it reaches what 386 Capt. A. I. Eagle, Bolling Field, Filling the Sand Box before a Flight in an Attempt to Disperse Fog with Electrified Sand the water to form about, and im- mediately drops of water run down the sides of the tube. In his second experiment, instead of introducing bits of dust into the air, Professor Knipp forces the saturated air to pass in front of a bit of radioactive sub- stance. This substance, radium bromide, sends out rays, called alpha rays, which have the peculiar property of splitting up the air into tiny electrically charged par- ticles. And these charged particles, act- ing exactly as though they were bits of dust, give the water vapor the nuclei tipon which it can condense into droplets. Be- cause the rays extend horizontally over the glass tube, the droplets, instead of fall- ing as in normal rain, also extend across the top of the tube, each droplet, accord- ing to Professor Knipp, representing a charged bit of air or ion. What is the possibility of applying these experiments to the production of rain? Like most scientists—though not all— Professor Knipp is inclined to doubt. “The idea of producing rain by shoot- ing a cannon into humid air is not alto- gether poppycock,” he told me, however.

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’ H i i A Composite Photograph, Showing How It Was Proposed That Clouds Be Forced to Give Up Their Moisture by Spraying Them with Electrified Sand Particles, Dropped from Airplanes

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POPULAR MECHANICS These conditions, Professor Knipp pointed out, limit rain making too severely for practical application. As demon- strated in his second experiment, one could theoretically cause a downpour by sending a powerful electric current through water-saturated air during a fall- ing barometer to ionize the air. “In fact that is what happens when a stroke of lightning brings on a shower,” he explained. “The practical objection to this plan is the impossibility of getting enough electrical power. The energy in a stroke of lightning traveling between a cloud and the earth a half mile below is greater than the entire Commonwealth Edison company has available!” While the explanation of why the light- ning flash or the sudden introduction of smoke—especially noticeable after forest fires or volcanic eruptions—produces rain has only recently been discovered, it has been guessed at more or less ingeniously. “There is a certain ele- ment of truth in it. “We know that before we can have rain two conditions are necessary: first, the air must be su- persaturated; second, it must contain enough par- ticles of dust on which the drops can form. “So, theoretically, in a region where the air is practically dustless, the introduction of smoke— say from a passing loco- motive or the shooting of a cannon—would provide the bits of dust on which the drops could form. “That is, of course, pro- vided all the other condi- tions were favorable—the saturation and the sud- den expansion of air (a condition which occurs when the barometer falls) at the very moment the smoke was _intro- duced.” Dr. Chas. T. Knipp with His Simplified Cloud Apparatus, and Diagram of How Nature Produces Its Rainstorms by the Condensation of Moisture on Dust Particles in the Upper Air re ee a ae

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POPULAR MECHANICS 389 m of re on A Natural Lightning Flash near a Power-Transmission Line and, Right, an Oscillograph to Be Used by West- inghouse Engineers in a Study of Lightning in the Tennessee Hills The occurrence of showers after battles, led Edward Powers, in 1871, to begin a campaign to induce congress to appro- priate money for extensive experiments in producing rainfall by firing cannon into the clouds. In his book “War and Weather” Pow- ers showed, among other things, that the battle of Waterloo was followed by rain- storms for two days and that the battle of 3uena Vista, fought in the midst of the dry season, was followed by two showers. In all, he studied fifty battles. Powers’ theories have since been dis- credited. At least one _ scientist has pointed out that no one has yet been able to cause steam from a teakettle to precip- itate by clapping his hands in it, although he would be jostling the drops more vio- lently than would an explosion one-fourth of a mile away. At any rate congress, in 1891, appropri- ated $20,000 to carry out the experiments suggested by Powers, and General Dyren- forth was appointed to superintend them. After preliminary trials, the experiment- ers went to a ranch near Midland, Tex., where balloons filled with a mixture of hydrogen and oxygen, and dynamite car- ried up by kites were exploded in the air. Although the principle on which Powers based his experiments is now generally considered fallacious—namely that the concussion would be sufficient to cause the warm water-bearing air to rise to the colder air above—General Dyrenforth re- ported that the cannonading actually did produce precipitation, drops often com- mencing to fall within twelve seconds of the first explosion. But Dr. W. K. Curtis, who was with General Dyrenforth’s party, declared that the only rainfall which fol- lowed the explosions was that which would have fallen or had actually begun to fall anyway. At the beginning of the World War, fol- lowers of the Powers theory expressed apprehension that a series of devastating storms would sweep Europe. As we now know, the rainfall during the four years of the war was normal for that part of the world. While this clearly disposed of the concussion theory, it by no means dis- posed of the smoke theory. Declaring that Indians started prairie fires to produce rain, James P. Espy, the naturalist who discovered how rising air is cooled by expansion, suggested, in 1845, a novel means of ending drouth. He pro- posed to burn forty acres of timber for every twenty miles, along a line extend- ing 600 to 700 miles from north to south in the western part of the United States. Such fires once a week, throughout the summer, he said, would cause the air to rise, cool by expansion and condense the water vapor into rain. Espy’s theory is apparently confirmed

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390 by the observation that clouds commonly gather above burning forests. But the cure would be far worse than the disease. For, even so tremendous a conflagration as the Chicago fire of 1871 was accom- panied by only a moderate shower, most of the storm clouds which hung over the city—whether caused by the fire or not— having been swept away by strong winds. One of the most spectacular attempts at rain making was made a few years ago when airplanes, circling above Bolling field, Washington, scattered heavy clouds by discharging into them a steady stream of ‘electrically charged sand. Prof. E. L. Chaffee, assistant professor of physics at Harvard University, directed the experi- ment on the invitation of L. Francis War- ren, a business man. Again at McCook field, near Dayton, Ohio, in the presence of army officers and aerial experts, including Wilbur Wright, army planes charged clouds with a stream of sand flowing between two electrodes, and a small shower followed. Although the area affected was too small to prove of practical benefit, the event was hailed in the newspapers as the first artificial rain- fall in history. Most meteorologists, how- ever, refused to accept this verdict. Probably the most successful rain maker of modern times is “Prof.” Charles POPULAR MECHANICS M. Hatfield. Newspaper records show that, since 1905, rain has fallen uniformly following his operations. In 1905, he was paid $1,000 for producing eighteen inches of rain in southern California, in the winter and spring. In 1922, he collected $3,000 from the farmers of Medicine Hat, Alberta. Among his other successes re- ported in the newspapers was a 2.29-inch fall of rain at Hanford, Calif., in March and April, 1924, for which he received $8,000. In April, 1926, a group of farmers, per- haps in a spirit of irony, gave Hatfield a section of land in the arid and unirrigated Tulare Lake region of California as com- pensation for his services. And although the rain did not fall until ten days after the date he predicted, it finally fell in sufficient quantities to save his crop, according to newspaper reports at the time. Physicists and meteorologists have uni- formly condemned Hatfield’s methods as scientifically valueless. They have de- clared that rain would have fallen without his presence and did actually fall else- where in surrounding territory followiug the long periods of drouth he was engaged to break. : Hatfield himself never revealed the mys- terious “chemicals” which he used, al- though he said that his process was the © Kadel & Herbert A Successful Rain Maker, Charles M. Hatfield, Got $3,000 When a Deluge Followed the Erection of His Mysterious Chemical Tower

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POPULAR result of ten years’ study and three years’ practical experimentation. He asserted that he had discovered the power of his chemicals to attract moisture by accident, when he observed that steam from a tea- kettle followed a mixture of them as he moved it about the kitchen of his home. His method of getting the mysterious substance into the air was to erect a square wooden tower mounted on sup- ports fifty feet high and varying in diam- eter from fourteen feet at the bottom to twelve at the top. The tower was sheathed with tar paper and inside were 104 galvanized-iron evaporation pans filled with chemicals and water. The tower, provided with an opening at the bottom to produce a draft, acted as a chimney through which the evaporating chemicals were carried into the air. At night, when there was no sun to heat the tower and evaporate the chemicals, they were burned. The result was eerie clouds bellowing into the sky and illuminated from beneath by the colored fire. Whether or not rain making will ever be placed on a practicable basis, man has apparently wrested its secret from nature. Like all other scientific discoveries that have first been successfully worked only in the laboratory and under ideal condi- tions, the artificial production of rain may eventually be developed to the point where drouth will be a thing of the past and abundant rainfall assured every plot of farm land in the world. But how stupendous the problem is may be gathered from the fact that the average annual rainfall of the United States is ap- proximately 6,055,245,753,000 tons. The energy furnished by the sun to evaporate and transport this enormous quantity of water has been estimated to be not less than 7,000,000,000 horsepower operating continuously. Professor Knipp, with the conservatism of the scientific research worker, admits the possibility of producing artificial rain only under special conditions. But so eminent a physicist as Sir Oliver Lodge recently declared that the problem of elec- trifying the atoms of humid air in clouds and forcing them to fall in drops is no more difficult than the problem of con- trolling contagious disease at one time appeared to be. MECHANICS 391 Receiving Radio-Photo Transmission of Popular Song in London from New York SONG HIT SENT BY RADIO PHOTO ACROSS ATLANTIC OCEAN So that it could be used in time for a ball, a late song hit was sent by wireless photo from New York to London, re- cently, and was received a few minutes after it was delivered to offices in this country. Words and notes were success- fully transcribed for the London singers, who were to render the song at the Three Arts ball. TENNIS-RACKET STRING GUARDS HELP IMPROVE GAME To protect the strings of the tennis racket, small rubber guards, easily at- tached, have been devised. They grip the bottoms and sides of the strings at their crossings in the center play- ing area of the racket, distribut- ing the strain and making the pull of the strings more effective. At the same time, the guards are said to help grip the ball, giv- ing better control to the stroke.

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POPULAR MECHANICS SMOKE BARRAGE FROM PLANES TO FIGHT FOREST FIRES Controlling forest fires by means of a barrage of chemicals from airplanes is one of the plans under consideration by the chemical service and the air corps. Re- _cent experiments in laying smoke screens and gas barrages from planes over the sea have shown that the work can be done at altitudes as low as 200 feet. CABINET FOR DRYING CLOTHES ALSO WARMS PLATES For drying clothes or warming plates, an electric cabinet has been introduced for house and apartment use. It is set into operation simply by turning a switch and has a means for ventilating the contents at the same time. Heated air is pulled from the top of the drier, down through the clothes, but the action is accomplished without fans or other moving parts. PIANO HAS BUILT-IN CABINET TO PROTECT MUSIC Two patented improvements have been added to the piano by a German manu- facturer, One is a built-in cabinet to hold the music where it will not easily become disarranged or dusty, and the other is a built-in lighting unit so arranged that it Lowering a Curtain from the Skies; Smoke Screen from Airplane, Laid Down to Show How Effective It Would Be for Operations against a Battle Fleet illuminates the music and the keyboard without a glare. It is controlled by a push button concealed near the keyboard. Another button raises the top lid of the piano case when greater volume is desired. CELL BOARD FOR RADIO VISION HAS MANY LIGHTS More than 2,000 tiny light-sensitive cells are contained in a board devised by C. Francis Jenkins for an improved radio- vision apparatus intended for broadcast- ing baseball games and other outdoor © Harris & Ewing C. Francis Jenkins with Multi-Cell Board for Radio Vision and Reporting Outdoor Events a ae ea ens 06 oe oh Of

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wing adio POPULAR MECHANICS 393 events. As a_ receiver, the unit will be suited to use in a theater. LEVERS STOPPING TRAIN PREVENT COLLISIONS By means of a lever installation which he has devised for railroad trains, an English in- ventor expects to prevent collisions. Levers are placed at intervals of half a mile and are intercon- nected. The locomotive sets them in operating position as it passes, thereby protecting suc- cessive track sections as it enters them. Should another train run into the guarded area, the projecting lever would automatically apply the locomotive’s brakes and halt the train. According to reports, the installation of the system is comparatively inexpensive, costing only a few dollars per mile. PORTABLE HUMIDIFIER IN HOME _ RUNS FROM LIGHT SOCKET Operated by current from a lighting socket, a portable humidi- fier for the home or office helps keep the air at healthful moist- ness and may also be used as a means to spread disin- fectants or deodorants. It is shaped and decorated in the form of an attractive urn, and the connections are so adjusted that the current is turned off automati- cally, if the container goes dry. @Popular Mechanics Magazine does not publish the name of the maker or seller of any device described in its pages, but this will be furnished free upon application to our Bureau of Information. Preparing Cables for the Big Bridge, and Drawing of Section Before and After Being Compressed with Jacks WIRES SQUEEZED INTO CABLES TO HOLD BIG BRIDGE Six hydraulic jacks, each capable of exerting a pressure of thirty tons, have been used to compress the wires that make up the cables for the Ambassador bridge, linking the United States with Canada at Detroit, into round cables. Each cable is composed of 7,622 wires, which are compacted to form a circular line nineteen inches in diameter. The cables are wrapped to hold them in the round shape and to protect them against weathering. There are thirty-seven ca- bles to support 12,000 tons, the weight of the bridge structure so suspended. FARMER RAISES HORNED TOADS TO DEVOUR INSECTS Near Abilene, Tex., a farmer is conduct- ing a profitable business by raising horned toads for zoos and shows, and for other farmers who keep them to devour insects that damage crops. Since the reported finding of a horned toad that was said to have slept in a cornerstone for thirty years, the specimens have attracted un- usual interest among visitors at zoos.

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> Helmet with Large Window Used for Shallow-Water Diving; with It the Wearer Can Stay Down Four or Five Hours at a Time By C. MORAN CIENTISTS wearing under-sea_ hel- mets are exploring submarine life in the Gulf of Mexico. Carrying cameras, they proceed leisurely at their work of observing and recording fish and plant ac- tivities. One of these explorers, Prof. W. H. Longley, of the Carnegie Institution of Washington, has spent more than 3,000 hours under water. A stroll on the bottom of the sea is a thrilling experience. A small launch, equipped with air pump and coils of rub- ber hose, is anchored over a spot twenty to thirty feet deep off Loggerhead Key, seventy miles west of Key West. A short 394 ladder is hung over the side. If you reach the last rung, before stepping out into water-filled space, the hose is at- tached to a copper helmet, in the front of which a square of plate glass is securely fitted. Carefully, John Mills, the engineer, lowers the helmet over your head until its weight rests firmly upon your shoul- ders. An assistant takes his stand at the air pump. You are told to let go, to proceed where you please. When your breath clouds the glass, Mills warns, tip your head, letting the water run inside the hel- met and the glass will clear. Follow the hose back to the boat when you wish to, return, Gently as a feather you come to rest on the ocean floor. You may strain your ears but will hear no sound. You look upward but see no sky. You gaze outward, but even under the most favorable con- ditions, fifty feet marks the limit of your horizon. No sharp contrasts of light and shade are to be observed, for the all-per- vading illumination softens every outline and angularity and shrouds every object in a peculiar haze. The water, transparent and constantly moving as seen from above, seems no longer to be water, but a queer encom- passing medium without motion. You are not conscious even that it is wet. You —

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POPULAR MECHANICS 395 a | mez Ze Sitting at the Subma- rine Window Watching the Fishes Flash By in a Coral Forest Life as Seen from the Window of J. E. Wil- liamson’s Undersea Pho- /, tographic Studio, a Huge Steel Ball, Sus- pended from a Flexible Steel Tube, Originally Invented by His Father as an Aid in Salvage Work; These Pictures Were Made by William- son on a Recent Trip in the West Indies The Tube from the Ship Above Incloses a Ladder, Telephones and the Air Duct, and Can Be ; —" “a Lengthened or Shortened fa : -. How a Diver Looks on the Sea Bottom; Williamson Has Photographed Thrilling Fights with Sharks ard Other Big Fish through the Circular Window of His Diving Chamber

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396 POPULAR MECHANICS stretch your hand toward a great coral head tower- ing beside you. It is be- yond the sweep of your arm. You attempt to place your foot on a bit of jutting coral but miss it entirely. Gorgonians, a coraliike form, and other growths, ankle- high when viewed from the boat, strike you at waist or shoulder or overtop you altogether. Declivities which seemed slight before are often seen to run off into huge depressions, and some- times into real gorges. Your movements at sea a dreaded barracuda, the “tiger of the sea,” treats the astonished stranger with good-na- tured consideration, in- spects him casually, and swims slowly away. Professor Longley, who frequently spends four to five hours on the sea bottom, gives the following description of his experiences : “Except when the light is strongest and the water itself most free from sediment, one is denied sight of all but the immediate surround- ings, the world being resolved into a diminu- tive hollow hemisphere, pervaded with silence and on all sides fading bottom are like the slow- motion pictures at the movies. The fishes ap- pear suspended lightly in their investing fluid, a quiver of fin or tail propelling them with equal-ease in any direction, up or down. They exhibit a mild curiosity at the presence of a man, swim lazily about you and idly nose you over. Even The Simple Diving Helmet Used for Shallow-Water Work, and a Close-Up of a School of Pork Fish Swimming, as Airmen Say, in Formation into nothingness. One’s narrow field, however, if wisely chosen, may teem with life. It is more than probable that long- spined sea urchins infest the place, twid- dle their spines if one approaches, or make off at a surprising rate of speed to shady

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Is ie of ie id 1e ut d- a ng re, ce ng yse-Up on field, with long- twid- make shady POPULAR places if disturbed. Yellow, brown or purple gorgonians, heavy with expanded polyps, stand on every side, with an occa- sional coiled basket star close-wrapped about their branches, where its inertness completely belies its power of motion. “Large spiny lobsters, torn between distrust and greed, from under mush- roomed heads of coral protrude their an- tenne and wave them frantically over. proffered food. Hermit crabs with heavy shells sit aloft on purple sea fans. With their spoon-shaped fingers, spider crabs, ensconced in safe retreats, grub off the encrusting growth of plants and fill them- selves to repletion. “The variety in coloration ef fishes is an unfailing source of delight. Whether one looks down upon them through the glassy water or whether they float into one’s field of view through the circumam- bient haze, they provoke recurrent expres- sions of admiration. One is thrilled as by the beauty of Aladdin’s garden. “Particular colors are correlated with specific habits. Red, for example, is al- most wholly restricted to nocturnal fishes which lie hidden by day. The greens, on the other hand, characterize such species as live upon the green reef flats, or swim near the surface in open water. “Equipped with diving hood, one may walk about freely and thus lead carniv- orous forms from point to point by offer- ing them food. It is possible under such circumstances to evoke their various color phases at will by selecting the spot to which the creatures are led. “The movements of herbivorous forms are not subject to quite such definite con- trol, but one may walk up to browsing schools of tangs or parrot fish, follow them about, and procure information with little effort. All the creatures may be photo- graphed amid perfectly natural and typical surroundings with little difficulty.” YACHT IS FITTED WITH GUN TO SHOOT BIG FISH Mounted on the forecastle of a sports- man’s Diesel-engined yacht, is a one- pound gun for shooting fish that may be found on cruises in the south seas, The equipment may also be employed for hurling harpoons at whales. MECHANICS 397 Distributor Box for Telephone and Telegraph Lines in Valparaiso, Chile PHONE AND TELEGRAPH WIRES CONNECTED ON POLE Both telephone and telegraph connec- tions can be made on a boxlike unit at the top of a high pole in Valparaiso, Chile. The distributor section is as large as a good-sized room and is adapted for quick changes in the lines, JOINT GRIP ON RUBBER STAMP IMPROVES PRINTING So that clearer impressions may be made without blurring, a rubber stamp just put on the market has a jointed handle, allowing free play between the grip and the base of the article. This prevents dis- turbing the im- pression when pressure is being applied. The base is of bakelite, and the rubber is firmly attached to it by an especially strong cement.

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398 POPULAR MECHANICS Making Tests with the Collapsible Lifeboats, and, at Upper Right, Inset of PLANES TO CARRY DIAMONDS TO LONDON A ton of gold and many diamonds are to be car- ried each week by all- metal flying boats and airplanes from South Africa to India and Lon- don, it was announced recently. The boats will be used on the area be- tween Cairo and the Cen- tral African great lakes. Beyond this district, tri- motored planes will fly to the Cape of Good Hope. Well-equipped landing fields and han- gars have already been es- tablished between Cairo and Capetown. One ad- vantage of this transport system will be a saving in interest charges which now are about $750 a day on an annual shipment of $70,000,000 in gold. ee fe = i FOOT CLAMP AIDS IN REPAIRING BATTERY the Davits That Roll Down Vessel’s Side BETTER LIFEBOATS TO CURB TOLL OF SEA ACCIDENTS , Loss of life in the “Vestris” disaster and in similar accidents has placed re- newed emphasis on the question of proper lifeboats for vessels. Just recently, inter- esting experiments have been made with improved forms of the craft. One has movable davits that slide down the side of the boat on rails, insuring the safe launch- ing of the boat without tipping over or the breaking of ropes. Another is a raft- shaped boat that may be quickly inflated or collapsed. It cannot capsize and will hold several persons. @ Names and addresses of manufacturers of articles described in this magazine will be promptly furnished, free, by our Bu- reau of Information. Quickly adjusted to storage batteries, a clamp is offered bat- tery-repair and service shops to save time and work. It is slipped on and held by footplates when changing the cells and making other repairs; is practically uni- versal in use as a slight pressure on the footplates makes it adjustable to almost any battery. It also does good service in reinsu- lating a battery as the connecting bars on each cell do not have to be drilled off, but all three cells can be removed at once. The tool is easily portable, and pat- ents have been ap- plied for.

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POPULAR MECHANICS 399 HOW INVISIBLE LIGHT SERVES TO PREVENT CRIME © The Illustrated London News The Development of Cheap and Practical Light Cells for Television and Other Radio Uses Has Opened a New Field in Burglar Alarms; Lights Can Be Turned On by Playing a Beam on a Sensitive Cell, or Alarms Can Be Sounded by the Breaking of an Invisible Light Beam When Some Solid Object Passes across It

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POPULAR MECHANICS after a rain. The material has been used success- fully on roads and, pur- chased in large quanti- ties, is by no means pro- hibitive in cost. COIN-IN-SLOT LOCK FOR CYCLES TO FOIL THIEVES Persons who fide bicy- cles in Berlin are af- forded an efficient means of.securing their vehicles against thieves by a coin- in-the-slot locking ar- rangement, Depositing a Children of Shipbuilders Celebrating the Completion of the Huge Funnel for the Motorship “Vulcania’ FUNNEL ON ITALIAN MOTORSHIP ONE OF WORLD’S LARGEST What is said to be one of the largest funnels in the world was built for the Italian motorship “Vulcania.” Before the vessel started on its maiden voyage to New York and before the funnel was in- stalled, a number of Italian school children celebrated the completion of the giant craft by exercises in the shipyard. In some of the steamets that have been con- verted into oil burners, the funnels are not all used for smoke, some being em- ployed as ventilators or as storage places. SELF-WATERING FLOWERPOT HAS DOUBLE WALLS Plants are automatically irrigated in a self-watering flowerpot recently intro- duced. It has double walls, the inner be- ing of a porous material and the outer one of a waterproof substance. The two are united at the top by means of a flanged rim, and the space between is filled with water. The pot has been carefully tested and has been pronounced a success, SPREAD SALT ON FLYING FIELD TO LAY THE DUST Salt, sprinkled over a Michigan flying field was effective in laying dust and also improved the visibility of the area, as the salt became a glistening white, especially coin releases a chain with a lock and key. The rider fastens his bicycle, pock- ets the key and goes on his way, knowing that his property is protected against theft. The locks are conveniently placed in public places and are reported to be — Lock Box for Bicycle, Which Gives Owner Stout Chain and Key for His Vehicle earning a revenue for the owners as well as affording protection for bicyclists, ‘ nn _—_—>- —|—- = =~ > — eee

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stout vell POPULAR MECHANICS 401 © Henry Miller Releasing Fuel into the Tri-Motored Plane from the Smaller Ship Above, While Flying at High Speed, and a Close View of the Supply Hoze and Nozzle PLANE REFUELED IN FLIGHT FOR ENDURANCE RUN Flying at a speed of ninety miles an hour, a tri-motored plane was refueled from a smaller ship sailing just above it. The test was made to further prove the feasibility of replenishing aircraft while in motion, and was directed particularly toward preparations for a coast-to-coast endurance tour. The most difficult part of the operation, it is said, was the lower- ing and connecting of the fuel hose. The nozzle weighs fifteen pounds. Food has been successfully passed from a service ship to a moving plane with a hose. SKATING ON FROZEN ALCOHOL POSSIBLE ON MOON Taking baths in molten sulphur at noon time and skating on frozen alcohol at night would be possible for persons dwell- ing in the moon if they could survive there. Scientists have been measuring the temperatures of the satellite with improved apparatus and have found fur- ther evidence of the extremes of temper- ature experienced there. When the sun is directly over a point on the moon’s surface, that is, at noon, the temperature reaches about 265 degrees Fahrenheit, higher than the boiling point of water and high enough to melt sulphur. Some indication as to conditions that probably prevail on the unilluminated side of the moon was found from measurements made during a recent eclipse. Before it began, the temperature was 156 degrees Fahrenheit. At the end of the total phase, it had dropped to 196 degrees below zero, the freezing point of alcohol. Half an hour after the eclipse was over, the temperature had returned to 135 degrees, nearly as hot as at the beginning,

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TRAINING el —— —_— «4 S the Miss Helen Hurley Up, with “Carter Spier’; She Has Beaten Some of the Best Men Drivers, and in Forty-Five Starts Was Only Out of the Money Eight Times By EARL CHAPIN MAY MONG the 12,000 light-harness-horse fanciers who saw “Grattan Bars” win the $25,000 New England pacing derby at Windsor, Conn., were some strangers to the trotting tracks who wondered that the big Canadian stallion came under the win- ning wire without a break, It was-a “driving finish” in horsemen’s vernacular, which meant that Vic Flem- ing, from his sulky seat, plied his whip. Reinsmen behind other horses in that race also lashed their light harness horses. But not one of the fast steppers broke into a gallop under punishment. Each stuck to its side-wheeling gait and did the best it could to win the race. Part of this willingness to stick to pac- ing under punishment was properly as- cribed to the hobbles each racer wore. Hobbles are straps which hang over the horse’s back and encircle each horse’s legs. -acers have been prominent in light-har- ness racing since “Hero” and “Pocahon- tas” won mile events and purse money on Long Island tracks in the early fifties. But hobbles did not come into general use until the nineties. Now nearly every fast pacing horse wears them. They hasten the development of vacing horses by 4 402 making an unusual gait more practica- ble. Pacers are frequently termed side wheelers because the pacer’s legs on each side of it move forward and backward in unison. During 1928, when more than 1,500 light-harness racing meets were held in the United States and Canada and about 10,000,000 persons were spectators, more pacers than trotters were entered in the events. “Grattan Bars,” from Canada, won first money in three of these $25,000 races in three weeks, something no other horse has done. But this new world’s record was made possible because of the skillful training given him. So carefully had the year’s sensation been trained that he didn’t break into a gallop under the whip—he flattened out and paced his fastest, which was what he was taught to do through three years of careful tutelage. About 10,000 pacers are being schooled in this manner. About 10,000 trotters are similarly schooled. In light-harness vernacular, all of them are “trotting horses,” to distinguish them from the “gallopers,” or running horses. Breeding, training and racing all horses is a specialty—or two specialties, to be exact. For, with a few exceptions, those Co Ge 2 POCO mf

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oo nrFr,r ca- ide ach in lan eld out ore the ida, 000 her ld’s the tion oa out t he =) of are yout In are hem 2S. rses » be hose who specialize in light har- ness horses have nothing to do with the gallopers, which they refer to as “bang-tails.” Those who follow bang-tail racing speak contemptuously of light harness horses as “turkey feet.” More time, patience, money and intelligence are required to develop a light harness horse, that is, a trotter or pacer, than are required to make a run- ning horse. Also, it re- quires more skill and more mature judgment to win a light-harness race than a running race. That is why you very seldom see a mere boy in a sulky seat. It takes a man’s brains and muscle to get the best out of a light harness horse. Galloping is a natural gait. Most horses run, in pas- ture or on the road or track, naturally. Once in The Trotter “Great Forbes,” with H. H. Hellman in the Saddle of the Racing a blue moon a colt is born to the trotting or pacing gait—“lot trot- ters” or “lot pacers” they are called. But ninety per cent of these natural-gaited ones are failures on the racing tracks until they have been manipulated. Colts bred for track life are halter-broke almost as soon as they are foaled, whether destined for harness or saddle racing. Once the soft halter is on a colt’s head it Stays there until it is replaced by a bridle and a soft rubber bit—a teething ring, in other words. From that point, methods of training diverge. Light harness horses and running horses enter different schools after they are six months old. The school for the light harness horses is much more exacting. It is the result of a century’s experience, for the trotting or pacing horses are strictly American products, while the running thoroughbreds are English in origin, although many great “Bike,” So-Called from Its Bicycle Wheels ones have been developed in this country. The training of the light harness racer is much the more complicated. After the future trotter has become ac- customed to the soft bit by guiding it around its nursery grounds with reins held in the light hands of a pedestrian, a light steel bit is substituted. Constant care is exercised to avoid hurting the ten- der mouth of the baby horse. Well-bred stock is too valuable to take any chances with its flesh or spirit. The days of rough handling passed long ago. When the colt has learned its first les- son and responds to gentle pulls to right or left, it is made whip-wise as well as bridle-wise. A tong lash is snapped in front of it or behind it or at one side of it. But the whip does not touch the gangling colt, so the latter does not shy at it. Then comes the lesson on the breaking cart, 403

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404 POPULAR which is a sulky having a heavy frame. This cart is rattled along the ground; its thills are dropped close to the young- ster’s legs. The wheels are rolled noisily along the stones. But nothing harms the nervous colt. By and by the pupil under- stands that the cart will not injure it. Then it is hitched and gently jogged on the track a quarter mile. It is on its way to being a racing horse. It has passed through the first preliminaries. It has also passed through its first vear. The professional trainer now takes a hand and takes it very gingerly. Each yearling is an infinite possibility. It may be a world’s champion and win a fortune for its owner or it may be a dud, a total loss. It is the trainer’s job to find what is in the animal. He studies. its gait and “personality.” Back of the yearling is the trainer who holds the reins. Back of the trainer- driver is trotting-track history. He knows that from the time the first trotting track The Trotting-Race Winner Is Decorated with a Floral Wreath at the End of Three Victorious Heats MECHANICS was opened—on Long Island in 1828~ down to 1874, when the great reinsman, Bud Doble, drove “Goldsmith Maid” to her record mile, trotting, in 2:14, little at- tention was paid to horses’ shoes. Among Bud Doble’s fellow reinsmen were two blacksmiths, Peter V. Johnston and James D. McMann, who banked the fires of their forges and drove to many a race-track victory. But neither they nor their driving contemporaries paid any at- tention to improving the shoes. “Goldsmith Maid” won more money during the ten years she was racing than any other rac- ing horse until the runner, “Zev,” in this generation, piled up $313,000 of money won. Yet Doble sent “Goldsmith Maid” to the nearest blacksmith shop when he thought she needed reshoeing. She wore a pound of iron on each foot until she wore her shoes down to where she had to have new ones or go barefooted. But Dan Mace and other old-time reins- men began to experiment with shoes of different weight on dif- ferent feet. Mace proved conclusively that a then famous trotter, “Lady Thorne,” went faster when he changed the weight of her iron shoes. From that experiment light-harness horsemen began to study balancing, by which is meant vary- ing the number of ounces in each shoe, usually by making the front pair lighter or heavier than the hind pair, and thus assisting the motion of the horse’s feet. Whole volumes have been written about bal- ancing. Fortunes have been made and lost by it. Six ounces on any trot- ter’s feet is now consid- ered heavy. Four ounces is close to orthodox. A Kansas trainer, named Charles Marvin, drove a pacer known as “Smug- gler” with indifferent suc- cess until, by putting toe weights on the pacer’ .

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POPULAR MECHANICS 405 Seige The Great “‘Miss Morris” Leads the Field Home in the 2:22 Trot; Harness Racing. Because of Its Close Con- nection with Practical Driving, Always Had a Great Hold in America feet and making other changes in shoes and rigging, the “Smuggler” became a champion trotter, a “converted pacer” as the horsemen say. As years went by and the call for speed sent horses past the 2:30 mark and gradu- ally into the “Golden Circle” of trotters or pacers which could go a mile in two minutes or less, horsemen learned that changes in shoeing would prevent knee knocking and that boots would also rem- edy this difficulty. They also learned that in many cases a trotter or pacer went better if his head was held high with an overdraw instead of a side checkrein. Dan Mace discovered that goggles cor- rected the faulty vision of a stallion named “Fearnaught.” Blinkers for shying racers came into vogue. Certain trotters and pacers are inclined to jump and break at shadows such as are cast across the track by quarter poles. Some genius evolved the shadow roll, which looks like a long sponge and is Stretched across the racer’s face a short distance below its eyes. Many a layman wonders what it is for. Another genius learned from experiment that if his trotter or pacer was inclined to side-rein, or not go straight, especially when rounding the turn of a trotting track, a billiard cue or other small pole, fastened to the horse’s bridle and its bellyband, between the reins, would help materially in eliminating that difficulty. ‘Then came the era of light-handed driv- ing. The first of the old masters of the reins was Hiram Woodruff who reigned between the forties and the eighties. He and many of his contemporaries depended for success on main strength and awk- wardness. The modern masters, such as Thomas W. Murphy, Walter Cox and Vic Fleming, put very little pressure on the reins, They depend more on delicacy of touch and feeling and control their step. pers with a minimum of muscular effort With a kind of magic they “lift” their racers to victory, though lifting is a phy- sical impossibility. Up to 1892 the high-wheeled sulky, with wooden spokes and iron-bound wooden rims, was all the vogue. In some of the earlier ones, the driver’s seat was six feet from the ground. In many of the later ones, the driver’s head and body were

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406 above his horse. In such a sulky John and James Goldsmith could really lift their horses’ heads by holding the reins high in air. This was possible with some of the first “bike” or pneumatic-tired sulkies, which, by the way, reduced the average light harness-horse mile by about four seconds and made the two-minute mile less difficult. ' But as science entered into racing, the sulky seat was lowered until now the driver is down behind his horse and hence does not increase wind resistance with his body. Yet, sitting at the low level, a skill- ful driver can still so rein a tired horse that it will brush or spurt under the wire to first money. That is what the reinsmen call lifting it. These are only a few of the things the trainer knows when he starts out with a yearling horse. He begins by jogging the pupil slowly, gradually increasing the speed and distance. During these train- ing miles he learns the nature and capa- bilities of his pupil. If the yearling trots naturally by putting its feet down in one. two, three, four fashion; if it gathers its hind feet quickly from beneath the sulky; if it does not throw the hind feet wide, but gets its front feet up in time to place the hind feet under them, then it is the trainer’s job to shoe his youngster lightly but without any fancy work and to de- velop its manners and stamina. POPULAR MECHANICS But if, as a trotter, the pupil does not go so well, then experiments are made in weight changing. If it interferes or knocks its knees, boots are put on its feet and legs. Its feed is always watched reli- giously. Rigging and feed are the sub- jects most often discussed by light-har- ness men. Mr. Murphy, who drove trot- ting and pacing horses into more than $2,000,000 of stake and purse money and has more speed records to his credit than any other light-harness man, made a big winner out of a discard, named “Hetty G.,” by mixing ground carrots’ with cracked wheat and corn, whereupon she picked up in flesh and speed. But his favorite food for trotting horses is cut-up clover, oats and bran, to which he adds a pinch of senna leaves and a half cup of olive oil. This combination is a prime conditioner. The able and industrious trainer who wants to drive his stable into the money on the Grand Circuit or anywhere, gets up at daylight winter and summer and sits in a sulky for 4 hundred miles before the day’s work is ended. During the rest of the day he studies horses, his own and those of his competitors. At night he dreams of faster horses, That is the life of the light-harness man, “San Peder Girl,” an American-Born and Trained Horse, Was Taken to Sweden and Offered Some Stiff Com- petition to the Swedish Harness Horses on the Stockholm Track mi Vil at ho tri

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_, Be) Se ee ee y’ POPULAR Once he has decided that some partic- ular pupil shall be a trotter with sus- penders on its front legs—suspenders look a little like half hobbles and help the trot- ter get its stride—he enters the horse in its proper class. This is fixed on certain courses, after the horse has won its first race, by the time in which it won the contest, or, on other courses, by the money .it won. If long experiments con- vince the reinsman that his pupil is faster at the pacing gait, either with hobbles or as a free-legger, into a pacing race it goes. Then the man at the reins of the new hopeful has to decide whether he better trail some other driver who breaks the wind resistance and thus take a chance on coming out from behind and going around at the home stretch to make a winning, or whether he should take the lead and head the field along the route. Above all and everything, he must know whether the horse he drives is so trained and constituted that it can be rated at top speed throughout the mile or whether, after it has trailed to the three-quarters pole, it will have enough speed left to brush by those that have led the way. He must also know how much pressure he can put on his horse before the horse will for- sake its artificial gait and go to galloping. The latter is disastrous, for the judges may disqualify a breaking horse. There’s a tremendous lot to the trotting game. That is why men and not boys must follow it, professionally. But among the non-professionals, it has had its mil- lions of followers since the gray mare, “Lady Suffolk,” first trotted a mile in less than 2:30 in 1845. The world’s record for trotting a mile, in the open, that is, with- out a wind shield, was made by “Peter Manning,” with Murphy up, at Lexing- ton in 1922. That mile was covered in 1:5634. The fastest mile ever paced in the open was by “Directum I,” with Mur- phy up, at Syracuse in the same fast time. “Dan Patch,” the pacer, made the fastest mile alone in harness, at Hamline, Minn., in 1906, behind a wind shield. These records indicate what progress has been made in fixing light-harness- horse gaits. But faster trotters and pacers will be developed. Trotting and pacing are American sports and more people watch them than ever before. MECHANICS 407 To Make Haircuts More Pleasant for the Children; Barber’s Chair in Form of Toy Automobile TINY AUTO AS BARBER’S CHAIR HELPS QUIET CHILDREN Children are induced to forget the terror of the barber’s shears and clippers in a chair that is made to resemble an automo- bile. It is comfortable and attractive and, like the ordinary chair, can be regulated as to height. HEAT GUARD ON ELECTRIC PLUG SAVES CURRENT Electrical appliances are heated to vary- ing degrees by means of a disk control on the attachment plug. It provides a range of “me- dium” and “hot” temperatures as well as a shut-off, preventing over- heating and ena- bling the operator to have the flat- iron, toaster or other unit heated to the most effi- cient point. The control eliminates the necessity of pulling out the iron plug.

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408 POPULAR MECHANICS Surfboards Pulled behind Fast Motorboats Are Common, but Here Is One That Is Pushed, and by an Out- board Motor; Leaning to the One Side or the Other Steers the Board SURFBOARD RUN BY MOTOR GIVES WATER THRILLS Riding a surfboard is becoming increas- ingly popular among persons who like water sports, but its possibilities have been somewhat limited as it has been nec- essary to have some sort of boat to tow the board. This need has been eliminated in a unit that has its own power plant, an outboard motor attached to the end. The board is wide, is fitted with ropes for hold- ing onto and attains a speed of thirty miles an hour. No steering mechanism is needed as the board is guided by the rider simply leaning his body in the direction he wishes to go. If the rider falls off, the board will stop at once. SIDEWALK LANES FOR SHOPPERS TO AID PEDESTRIANS Special lanes for window shoppers and for other pedestrians have been tested by the Detroit police department in an effort to expedite sidewalk traffic. Persons who wish to loiter along by the shops have one lane while two others are provided for “through” traffic. The plan helps keep pedestrians to the right and avoids con- fusion. To supplement the traffic lights at some of the downtown intersections, loud speakers were installed to give direc- tions and warning as to the proper time to cross. SHAVING BRUSH HOLDS SOAP AND POWDERED STYPTIC Besides a tube of cream, a fountain shaving brush holds a cup of powdered styptic, and also has replaceable bristles. The assembly takes up but little space in the traveling kit. PUSH SuTTON REPLACABLE BRISTLES © 7» TUBE OF pf CREAM STyprTic cup l. Parts of the Shaving-Brush Kit, Showing the Feeder utton, and Cup for Styptic ., us M te su fr be ol m pl ar us

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in d in POPULAR MECHANICS 409 EGGS ARE “BOILED” UNDER PRESSURE IN ICE WATER Artificial pressure of 600,000 pounds to the square inch, the highest so far produced, has been attained by Prof. Percy W. Bridgman, of Har- vard University, with an é apparatus of his own in- vention. This pressure corresponds to what would be found at the bottom of an ocean 250 miles deep. Under its force, steel tends to spread, paraffin becomes harder than machine steel and rubber turns so hard that it can be used as a die to cut steel. Mercury froze at room temperature under a pres- sure of 200,000 pounds, although it normally freezes at forty degrees below zero or lower. The outfit Professor Bridg- man developed is de- scribed as relatively sim- =e s LMLONG THE WAY | PRESSURE INCREASES) ARE INCH ple. What appears to be an ordinary hand pump is used to create the pres- sure required. Materials to be compressed are held in a small hole bored in a solid piece of steel, five inches thick. This is stopped by a small steel plug which spreads under pressure to keep the con- tents and air from escaping. During one of the experiments the compression cham- OPERATE ELECTRIC POLICEMAN BY SOUND OF VOICE “Mr. Televox,” a mechanical policeman installed near a street intersection in a California city where it operates a wink- ing light and warning arms by the effect of vibrations from automobile horns, has been thrown into confusion by small boys. They discovered that they could success- fully imitate the sound of the horn by their own voices, A yell of the proper Some of the Chief Details of the Pressure Apparatus and an Inset of the In- ventor, Professor Bridgman ber exploded and fragments were im- bedded six inches deep in hard-pine plank- ing back of the apparatus. In another test, eggs taken out of ice water that had been heated by subjecting it to a pressure of 100,000 pounds were found to be hard- boiled. volume and pitch caused “Mr. Televox” to wink an eye and wavé an arm when no signals should have been produced. The inventors are now trying to readjust the “policeman’s” mechanism so that un- timely signals cannot be given. The de- vice is intended especially for the protec- tion of cars being driven from a side street across the main intersection. By tooting their horns, the drivers can cause the me- chanical policeman to halt traffic on the main street until they have passed it.

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POPULAR MECHANICS LIVING IN LUXURY HIGH ABOVE CITY STREETS An Elaborate Roof-Top Bungalow and Garden in New York, Where Such Skyscraper Homes May Cost Anywhere from $2,500 to $300,000; at the Left Is a Vista of a Charming Garden, with Rustic Paling Fence, Which Might Be a Sub- urban Home, but Actually Is High above Man- hattan; Below Is Another of the Lofty Pent- house Homes, with Bushes and Flowers Lining the Stone Coping; Tile Floors and Gay Awnings Make the “Yard” Attractive a Photos by

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POPULAR MECHANICS IN BUNGALOWS BUILT ON SKYSCRAPER ROOFS How a Roof-Top Home Looks from the Opposite Side of the Street; the Usual Penthouses, Cover- ing Elevator Machinery and the Like, Are Con- cealed within the Bungalow’s Walls; Many of the Lofty Homes in New York Have Magnificent Views over the Harbor and Lower Bay, or up the Hudson; at the Right Is a Pigeon Cote in the Garden of a Skyscraper Bungalow, and Be- low, a Corner of the Yard in One Famous for Its Garden and Rustic Picket Fence Ewing Galloway

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412 POPULAR Photo Diagrams to Show Installation of the Automatic Safety-Brake Release AUTO SAFETY-BRAKE RELEASE HELPS PREVENT ACCIDENTS Many motorists have experienced dif- ficulty in shifting gears when the car is stopped on a hill with the emergency brake on. The tendency is to let the auto roll back and possibly collide with a car behind before starting forward. This difficulty is eliminated with an automatic release for the safety brake. It frees the emer- gency at the proper moment, leaves the right foot to operate the accelerator and prevents running, or attempting to run, the car with the emergency on, a big saving for the linings. PLANTS BREATHE ONLY BY DAY LIGHT TESTS SHOW Plants open their breathing pores only under the influence of daylight or its equivalent, Dr. J. D. Sayre, of the Ohio agricultural-experiment station, recently told plant experts. The “invisible light” beyond the red end of the spectrum has no effect on the leaves, he declared. The longest-wave light rays to which they would respond are just inside the limits of the visible red. MECHANICS SEEK CURB ON RADIUM DEATHS TO PROTECT WORKERS Scientists are seeking ways whereby hazards may be reduced for those who work with luminous paints and other ma- terials containing radioactive substances. Seventy-five chemists and industrial offi- cials met in Washington not long ago to consider the matter, the action following the death of several persons who had been engaged in painting luminous dials and figures on clocks and watches. Some ob- servers of the malady have declared that the principal cause of radium poisoning was the “eating” of the substance, that is, the workers’ tendency to place paint brushes dipped in the material, between their lips to moisten the tip. It has been suggested that substitution of a stylus or die for the brush would solve the prob- lem. This theory has been discredited, however, since some persons have died from the poisoning even though they did not use the paint brushes in any way. Ac- cording to Dr. A. B. Moore, dean of science at Purdue University, the real cause of some of the deaths attributed to radium poisoning is still unknown. He said he had experimented extensively with radium without ill effects. ANTI-BURGLAR WINDOW CATCH ALSO PREVENTS RATTLING Intended to make windows burglar-proof, a steel wedge, with sharpened points for holding it in place, also keeps the windows from rattling and may be used as a door- stop. It can be ad- justed without nails or screws, @The Popular Mechanics’ Bureau of In- formation offers its free service to all readers of our magazine. Names and ad- dresses of manufacturers and dealers in articles described, and any other details in our possession, will be promptly furnished by addressing the bureau. -—. a6 oe oh «ms @8 22° eh 22 44 2 at 2s

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n- all d- in in ed POPULAR MECHANICS . 413 BIG WAREHOUSE BUILT IN CAVE FOR POTATO CROP ee —e -— sealed Nae od ~~ } ’ Views inside the Cave Warehouse Where Quantities of Potatoes and Other Crops Are Stored; the Cavern Was Formed during a Volcanic Eruption Many Years Ago In a section of the potato-producing area of Washington, a three-story ware- house has been constructed in a natural cave formed by a volcanic eruption many years ago. Surplus potatoes are stored there, the temperature remaining at about thirty-seven degrees Fahrenheit the year around, The warehouse is equipped with an elevator and there is room for many more buildings, as the cave is about a mile long and forty feet high. Geologists believe that it was formed by a huge air bubble that gathered during a flow of molten lava, t HOT WATER FROM DEEP WELL HEATS RAIL STATION Water from an artesian well, nearly 1,700 feet deep, at Capa, S. Dak., is used to heat the railroad station and also in the locomotives, for it comes spurting out of the ground at a temperature of about 120 degrees Fahrenheit, and at a rate of 100 gallons per minute. Some experimenting was necessary before the water could be employed in the boilers because it con- tained mineral substances that produced foam. By cooling and by the addition of a special compound, this trouble was elim- inated. Later, a chemical! was found which made cooling unnecessary, so that the water could be piped into the engines directly from the well. WRENCH FOR AUTO HUB CAPS FITS ALL MAKES Hub caps on all makes of cars, includ- ing the 1929 models, are easily removed with a universal wrench now on the mar- ket. Hexagon and octagon jaws are ad- justed with a slight twist of the wrist, and the tool is said to be especially adapted for damaged or tightly wedged caps. AUBURN NASHs_\ OCTAGON.» : PACKARD L HEXAGON RICKENBACKER Hub-Cap Wrench, Showing Different Makes of Cars for Which It Is Adjusted

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© Henry Miller View of Automatic Steering Gear as Installed in Cock- pit of Plane for Safer Flying STEERING GEAR FOR AIRPLANES WORKS AUTOMATICALLY Successful tests with an automatic steer- ing gear for airplanes are reported from Germany. The device, it is said, frees the pilot from keeping his hands on the con- trols, yet does not interfere with operating the ship in the usual manner. GAS TREATMENT FOR POTATOES CAUSES EARLY SPROUTING Potatoes are made to sprout in three weeks by dipping them in a chemical sub- stance, and then gassing them in air-tight containers for twenty-four hours. The method, developed at the Nebraska agri- cultural station, is expected to be of great aid to the growers, as it will make seed potatoes suitable for earlier shipping to southern markets, where planting is pos- sible long before farther-north conditions permit, and it also allows experimental work with different grades to begin much earlier than is ordinarily possible. Pota- toes usually lie dormant about four months before beginning to sprout. The treatment is also effective in ridding the potatoes of certain diseases. POPULAR MECHANICS ULTRAVIOLET RAYS FROM SUN NOW ON INCREASE Ultraviolet emanations from the sun are on the increase, according to reports from scientists who have been keeping close watch on the body. Dr. Edison Pettit has been making measurements of the in- tensity of the sun’s ultraviolet light at Mt. Wilson observatory, for four years. Since the first measurements were made in June, 1924, the monthly average inten- sities, have, on two occasions, been half again as great as they were in that month. That was in October, 1925, and February, 1927. The variation closely follows the number of sunspots, Doctor Pettit an- nounced, and now seems to be increasing. STICKS AND LEAVES AS MAPS GUIDED EARLY SAILORS Among the most curious maps in the world are those fashioned by certain tribes of island dwellers, and used as re- cently as sixty years ago. One of these is simply a framework of sticks from the center ribs of palm leaves, tied together with palm fiber. The islands are repre- sented on the map by small shells. The curving lines of the sticks are thought to designate the ocean currents and winds a traveler would be likely to meet in go- ing from one spot to another. The maps were used for many years by the natives. Curious Map, Made By Early Sailors; the Objects at ach Corner Represent Islands ne

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POPULAR MECHANICS 415 Three Kinds of Iron; Gray Cast Iron, with Coarse Graphite Flakes, at Left; Pure Iron and Carbide of Iron, Center, and, at Right, Crystals of Pure Iron Imbedded in Carbide MEEHANITE—A New Metal It Has the Structure of Fine Steel and Promises to Replace Cast Iron in Motor Cars LARGE automobile company recently brought out a new model with an en- gine having thirty-five per cent more power than its predecessor. Offhand, it would be expected that proportional en- largement of transmission and rear-axle parts would be required to withstand the greatly increased turning effort of the engine. But, with minor exceptions, the dimen- sions of these parts are unchanged, yet they are much more than thirty-five per cent stronger than those of the previous model. It sounds like magic, but, like all sleight- of-hand performances, the explanation is simple, for the greater strength was ob- tained by using improved alloy steels. In adopting this course, the manufacturer realized many advantages. The new trans- mission and axle ‘parts could be made on the same machinery used last year, thus avoiding the large expense and trouble involved in putting new designs into pro- duction. Much weight was saved because obviously the new parts weigh no more than the old. The service-parts problem was greatly simplified, for nearly all the new parts will fit the old chassis, thus making it unnecessary for dealers to carry separate sets for the old and the new models. This illustration is merely one of many which could be quoted to show how im- proved steels have greatly assisted in devel- oping the modern automobile. But in spite of the great advances made in metallurgy during the past twenty years, automotive engineers expect even greater improve- ment in the next decade. In the beginning, steel consisted funda- mentally of an alloy of carbon and iron with a tensile strength of about 100,000 pounds per square inch. Then it was dis- covered that, by alloying this material with various metals and by proper heat treat- ment, the strength and other desirable properties could be greatly enhanced, in- cidentally raising the tensile strength up to 280,000 pounds in some cases, Generally speaking, hardness, brittleness and strength go together, as do softness, ductility and low strength. Thus a steel with .15 per cent carbon is soft, ductile and relatively weak, while a steel with 1.25 per cent carbon is hard, brittle and strong. Between these limits, hardness, brittle- ness and strength increase as more carbon is'added. With any given percentage of carbon, these three qualities are brought to a maximum by rapid cooling from the right temperature, while softness and duc- tility with reduced strength are secured by slow cooling. Broadly speaking, the addition of nickel to a carbon steel gives toughness; chro- mium, hardness; chromium and _ nickel, hardness and toughness combined; vana- dium or molybdenum, shock resistance; silicon, resiliency. And the best of it is

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that, by selecting a suitable combina- tion of alloys prop- erly heat-treated, a steel with almost any desired proper- ties may be ob- tained. Now here is a cu- rious fact: Anauto- mobile chassis is largely composed of steel and cast iron. The reader is fully aware of. the - great progress that has been made in the metallurgy of automotive steels. But what of cast iron? Steels have been growing better but it is rather shocking to realize that progress in the development of cast iron has been almost negligible. In twenty years;. the strength of steel has nearly trebled and its other properties have been similarly improved. During the same period, the strength of cast iron has only increased from about 20,000 to 30,000 pounds per square inch, and its other properties roughly in proportion. Fortunately, however, metallurgists all over the world are beginning to give cast iron the attention it deserves, for it is a very important material. In fact, very en- couraging progress has already been made, and this brings us logically to a discussion of a wonderful new material, Meehanite, named after its inventor, G. F. Meehan. POPULAR MECHANICS Chemically, cast iron differs from steel in that it has considerably more carbon, 3.4 to four per cent. Meehanite likewise is composed of iron and two to three per cent carbon, and while it is designed to replace cast iron, it has the structure of fine steel, whereas the structure of cast iron is an uncertain hodgepodge, as will presently be explained. Meehanite has three times the tensile strength of gray cast iron, that is, its strength runs up to 100,000 pounds per square inch. It has twice the stiffness of cast iron. It may be heat-treated like steel. By this means it can be made as soft and ductile as malleable iron or as hard as chilled cast iron. It has un- usual strength at high temperatures and is very resist- ant to corrosion. It machines as readily as gray iron, but with long, curved chips like steel. Meehanite may be used anywhere cast iron is used, Courtesy Prof. Robt. 8S. Williams A Hard Tough Steel, Top; a Fairly Hard and Tough Sample, Produced by Hardening and Tempering. and, Bottom, a Sample of Meehanite, Magnified 100 Times and, in some cases, successfully replaces steel. The material looks particularly promising for cylinder blocks, because of its greater hardness and resistance to ab-

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jams ugh and, nes ces irly . of ab- POPULAR MECHANICS 417 rasion. Tests already made indicate that wear on cylinders and other surfaces is likely to be cut in half. The utility of the material is also indi- cated by the recent manufacture of some air-cooled airplane-engine cylinders. By correct heat treatment, the air-cooling fins were made as soft as malleable iron to re- sist accidental breakage, the cylinder bore was made hard to give exceptional wear quality, while the metal between the cyl- inder bore and the fins was treated to give high tensile strength. Thus these cylinders are not only stronger and lighter, but have superior wearing qualities. SPREAD POLLEN BY ELECTRICITY TO AID PLANT CULTURE In raising tomatoes under glass, a west- ern grower simplifies the task of spreading pollen by using a vibrator operated with current from small batteries. It taps the blossoms lightly but with a frequency many times greater than is possible by hand. The pollen is seen to shower forth, and the entire operation is done in about one-third the time required by ordinary methods. VACUUM CLEANER FOR GRAIN TO IMPROVE CROPS Better grading and testing of seed is said to be possible with an electrically op- erated vacuum unit, developed by the de- partment of agriculture. It can also be used for removing foreign substances from other material than grain. The seed to be treated is placed in a hopper from which the rate of flow is controlled by means of a cone valve. Suction, pro- duced by a vacuum- sweeper fan and governed by an air valve, lifts light par- ticles away from the heavy ones so that the cleaned grain falls into one compartment and dust and the like, into another, Vacuum Grain Cleaner Wheeled Cart for C ing Mail Bag; It Takes a Load from the Postman’s Shoulders WHEEL CARRIER FOR MAIL BAG EASES POSTMAN’S LOAD Letter carriers in Washington, D. C., tested a wheel carrier for the sacks dur- ing the Christmas rush. Instead of carry- ing the bag from the shoulder, the post- man placed it on the wheeled holder and pushed it along. A brace kept the sack upright when left on the sidewalk. CEMENT SPRAYED WITH METAL TO MAKE IT WATERPROOF Reports from Germany state that a scientist there has developed a process for covering ce- ment objects with a spray of molten zinc, tin or lead to make them water- proof. The method has been applied to cement and con- crete slabs, pipe and tanks and is said to be equally success- ful with all forms of artificial stone.

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COLLEGE baseball player sits ata table whose surface is a small baseball diamond with diminutive models serving as the pawns of sport. A_ psychologist stands before an electric flasher in an ad- joining room. By moving switches, he - juggles the players and plays on the mid- get diamond so that various unexpected situations are developed. The campus athlete who is undergoing tests to ascertain his baseball knowledge and reactions to emergencies in the game, solves the various sport puzzles as they are presented on the imitation diamond. A careful record is kept of the time re- quired by each candidate in working out the diamond problems. These data aid in culling the misfit from the fit baseball can- didates at the University of Illinois, long famed as a hatchery of champion college nines. When the candidates take the field in early spring, they use a remarkable electri- fied bat in hitting practice. This scientific bludgeon is equipped with electrical con- tacts linked directly by telephonic connec- tions with recording devices in the psy- chological laboratory, which is an im- portant feature in the new university gym- nasium. Similar electrical contacts are imbedded in the batter’s box and at first Exercising a Rat on a Boardwalk “Maze,” Top. as a¢ . $6 bo $ d ani base. A special time recorder registers a oe = es neath oad st 5 A A 418 boc the att the abl

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er- A Test for Mental and Muscular Co-ordination; the Athlete Attempts to Make Regular Contact with the Electrified Hammer as It Is Moved by the Hidden Mechanism the exact second when bat meets ball, while it also keeps tab on the instant the batsman leaves the batter’s box and when he arrives at first base. This electrified detective of baseball- player defects explains definitely the fail- ure of many players to make the “varsity” and to win their coveted college letters. It demonstrates that certain unsuccessful candidates consume as much time in hit- ting the ball and covering the first ten feet to first base as they do in negotiating the remainder of the distance to the initial sack. These men lack the qualifications of satisfactory co-ordination. They fail because they are unable to shift swiftly from the status of baseball batter to track sprinter in the sudden scurry to first. Dr. C. R. Griffith takes regular technical measurements of the rates of development of pitchers, catchers, infielders and out- fielders at the University of Illinois, which recruits its baseball nine from a student body of 13,000. He graphs and diagrams the baseball practices, paying particular attention to the natural hitting range of the different players. These diagrams en- able him to ascertain where any given player will naturally hit a ball. If the nat- ural inclination of the player is to hit consistently to left field and into the hands of the opposing fielder, the coaches, on the recommendation of the psychologist, change the batting stance of that partic- ular athlete so that he will hit naturally into safe territory. A stop watch is used in timing the intervals required by dif- ferent players to field balls and to throw to first base. Tests of athletic candidates bring to light the individual adaptations and pro- pensities of certain students for particular sports. They may identify an unsuccess- ful sprinter as a superior broad jumper. They may prove that a man who tries out for baseball would have a better chance for athletic success on the_wrestling mat or in the squared circle. The series of tests divulge athletic secrets. They aid, so to say, in untangling the scramble into which some modern coaching systems have futilely massed their athletes. The timing factor, as well as form or habit, is of vital importance in many sports such as golf, boxing, discus throwing, shot putting and hammer tossing. Professional 419

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420 POPULAR MECHANICS pugilists who re- main out of the ring for long periods be- come rusty and lose one of their most treasured assets— efficient timing. The undergraduate run- ner wins keenly contested races be- cause of his stam-. ina, speed—and per- fect timing. Doctor Griffith employs an ingenious slotted maze in his experiments to determine the timing at- tributes of different athletes. The candi- date takes hold of an electrified handle and attempts to move it uniformly and correctly from one end of the maze to an- other and through its complicated twists, turns, bends and curlicues. At regular in- tervals throughout the maze, this handle touches electrical contacts and writes the scientific history of the candidate’s timing qualifications. A student gifted with good co-ordination and timing will complete this astonishing timing test five times quicker than the athlete whose sense of timing is vague and undeveloped. A unique reaction-time apparatus is used to measure the muscular quickness of the athletes. This device is so arranged that it records the mental lapse of the baseball or football player, runner or golfer under test. In response to a signal —light, sound or human voice—the athlete presses a response button. The interval between the original signal and his reply is the measure of his reaction time. This testis a keynote to the athlete’s response to future field-of-play emergencies. In another test which aids in the accn- rate determination of a student’s athletic aptitude, the subject sits directly in front of a perpendicular board equipped with an electrified apparatus. This equipment provides ten distinct and separate appli- ances which serve as a scientific proving ground for the eye, ear and hand co-ordi- nation of the would- be athlete. A bell rings and the student under test immediately presses a button in response. Then a pair of weights fall. The subject restores them as rapidly as may be to their original position. A white light flashes. Dexterity Is Tested, at the Top, by Sticking a Contact Pointer in Holes; Center, a Wired Baseball Bat, and, Bottom, an Electric Maze

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ie r fe al ly is e tact and, POPULAR He turns a switch in answer. And thus the automatic examination is continued. A supplementary chart recorder graphs the reaction time of the athlete to this round robin of tests, which demonstrate his rapidity of action, concentration, re- action to orders and similar information. The dexterity of the gymnast, swimmer or basket-ball player is studied by means of an electrical contraption consisting of a peg or pin which fits very loosely in a certain hole in the device. The athlete grasps the pin in his hand, quickly inserts it in the plug hole and then removes it and repeats the process for several min- utes. It is a reliable test of hand-eye co- ordination. Each time the pin strikes the sides of the opening instead of the center of the hole, the subject is faulted corre- ~ MECHANICS 421 A Pair of Unusual Tests; in the One at the Top the Student At- tempts to Stick His Pointer through the Holes in the Disk as They Flash By at Varying Speeds; in the Other, Powerful Magnets, Hidden beneath the Table, Are Switched On and Off, Each One Trying to Drag the Metal Plate in a Different Direc- tion, While a Candidate for the Wrestling Team Tests His Skill in Meeting the Sudden Shift with the Necessary Muscular Energy to Defeat It spondingly, while he is credited with all the clear-cut “bull’s-eyes” he scores. The co-ordination of one’s hands and mind is examined technically in another test, in which the athlete holds an electric pencil in each hand and attempts to guide them simultaneously through two mazes without touching the sides. Another novel test features the use of a specialized appliance to disclose the individual mus- cular tension, if any, which is character- istic of a certain subject. For example, a baseball pitcher unknown to coach and captain may be handicapped in his effec- tiveness by some unusual condition of muscular tension. The apparatus brings to light such condition. Its detection can then be followed by emergency control measures. The test itself is simple, as the

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422 POPULAR pitcher is asked merely to hold an electri- fied hammer so that it makes contact with a swinging arm mounted above a glass plate. . This efficacious detective registers the baseball player’s peculiarities as related to muscular tension. Another apparatus measures a man’s muscular time reactions, It is particularly valuable in making a survey of wrestling and boxing candidates. The athlete is asked to hold a handle in a stationary po- sition at the center of a limited surface. Two powerful magnets are mounted un- der the table below this handle. They are employed to pull the handle in differ- ent directions. The subject does not know at any moment in what direction the pull will be directed. This is a laboratory simu- lation of the ruses and fake movements to which the college wres- MECHANICS has only three small copper-based aper- tures exposed. The arrangement is such that the disk can be revolved at various speeds. The psychologist gives the athlete under test an electrified pointer and asks him to touch the various openings in the rapidly turning dial. Each contact is re- corded automatically. The machine meas- ures the athlete’s rapidity of action in this eye-to-hand test. White rats are being used as athletic actors in an original experiment which Doctor Griffith has inaugurated recently, to determine the effects of exercise on well-being and longevity. The rats are di- vided into groups of uniform age, size, de- velopment and intelligence. A compli- cated maze is used to develop rat intelli- gence as learning is essential to athletic tler is exposed in a com- petitive match. He has to outguess the test ma- chine and outmaneuver it in the same way that he would handle a tricky adversary on the mat, An athlete’s accuracy of movement and alert- ness are gauged by a re- vamped talking machine, geared for extraordinary purposes. The revolving dial of the automatic speaker is covered and On the Test Board at the Top, the Candidate for Athletic Honors Undergoes Ten Different Reaction Tests to Prepare Him for Scenes like This, with a Runner Safe at First ‘ a m p: O01 fi ta 0) p! 01

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ill POPULAR skill. Brawn must be supplemented by brain for success in modern sports. The only definite data now available pertaining to the benefits or evil effects of athletic training consist of statistics compiled at several leading universities. For the most part, these figures cover only the collegiate life of the athletes and do not provide information about their after- college days. Doctor Griffith, by the use of novel rat exercisers, such as revolving cages oper- ated tread-power fashion, is overexercis- ing some rats, while other rodents are given average exercise, and additional groups are underexercised. The research will cover at least one generation, Experts are co-operating with Doctor Griffith in the experiment, which is ex- pected to be productive of data on the re- sults of regular, irregular and excessive exercise—moot points whose conclusive solutions will interest millions of sport lovers, POWER PAINT SPRAY OPERATED BY AUTOMOBILE MOTOR Operated by power from the auto’s motor, an efficient spray gun for applying paints, lacquers and other liquids is now on the market. The outfit includes twenty- five feet of hose and an equalizing filter tank, and is attached simply by removing one spark plug and screwing in the com- pressor unit. The device may also be used to inflate tires, to clean upholstery and to oil the springs. Spraying Auto from Gun Operated by Power from the Car’s Own Motor MECHANICS 423 © U. & U. Photographs Mounted on Replica of Bridge Pylon, to Show How Finished Sculpture Will Appear ‘PHOTOS SERVE AS SCULPTURE FOR BRIDGE STATUES In choosing the equestrian statues for the Arlington memorial bridge pylons at Washington, huge photographs of the proposed designs were mounted in the position that the sculptures will take later, so that the commission could determine the appearance of the finished structure. The photographs are said to be the largest ever made by the signal corps. PLANE LANDS IN DRAG SAIL Successful tests with a huge sail, dragged from a moving vessel and used as a land- ing for hydroplanes, are reported from Germany. The plane repeatedly started and landed on the sail, an advantage of the plan being that the canvas presents a smoother area than the water itself.

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424 POPULAR MECHANICS WINDOWS REVEAL INNER SECRETS OF AUTO ENGINE If there is one thing known to science which is darker than the inside of a cow, it is the interior of a gasoline engine. Uncle Sam has attacked the problem in a novel manner by equipping two engines with peepholes of quartz through which engineers are studying what goes on in the combustion chamber. The layman who visits the laboratory can peep through a device known as a_ stroboscope and watch the engine operation from the in- side out and from the outside in. The stroboscope slows down swift motion so that the eye can see what previously was unseen. It is a sort of simulation of the slow-motion picture idea applied to the study of mechanical activity. When you step on the starter of your motor car, a condition of fog exists in the intake man- ifold. The federal experts have capital- ized this fact by throwing light through one of the openings into the manifold. Exploring the Inner Mysteries of a Gasoline Engine While It Is in Operation; What Goes on Inside Is Revealed through the Quartz Peephoies When this beam strikes the fog, the light is scattered.so thoroughly that an ob- server gazing through a second quartz window can study all that takes place. Soot, tiny droplets and particles in the intake manifold or in the combustion chamber also operate to scatter light simi- larly, when its revealing rays are focused at such points. The arc is thus used to cast its beam into the experimental cyl- inder of one of the test engines. A glass lens, seven inches in diameter, is mounted above the engine head and the series of quartz windows, so that all beams of light from the combustion chamber which pen- etrate these peepholes are brought to a focus at the stroboscope. A mirror is also used to reflect the image to the side of the engine where the stroboscope is at- tached. Each quartz window is one- eighth of an inch in diameter. These openings are distributed so that the rate of flame propagation in the combustion chamber may be computed by watching the illumination spread from one row of the holes to the next. The rate of flame development with different fuels, mix-

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POPULAR tures and varying engine-operating condi- tions are being studied. The phenomena of spark production, ignition of the charge and the resultant explosion are yielding new facts about old engines which have never previously been understood thor- oughly. Potentially, airplanes, speed boats and motor cars will be operated more efficiently and economically as a di- rect result of Uncle Sam’s tests with “win- dowed” gas engines. CHIMNEY FELLED FROM INSIDE TO PROTECT BUILDINGS Wrecking a 155-foot chimney in Lon- don without letting a brick fall on neigh- boring buildings was the task of a skilled steeplejack. He erected a scaffold on top of the shaft and a staging reaching half- way down the inside. Bricks were thrown down to the bottom of the interior into a seven-foot hole that was cleared at inter- vals. The first part of the work was more difficult because of the overhanging top section of the chimney. PERISCOPE FOR GOLF FANS CARRIED LIKE CANE So that golf enthusiasts may be able to see over the heads of others at matches, a leather-incased periscope has been de- vised. It may be swung as a cane by its strap, when not in use, and is quickly inverted to be employed as a periscope. It is said to give a clear view. Using the Golf Periscope Which Permits Spectators to Look over the Heads of Persons Near By MECHANICS 425 WINDOW DISPLAY ON WHEELS HELPS DRAW CUSTOMERS Furniture Display on Moving Platform; the Show Window Is Seen at the Far End Realizing that moving objects attract the eye more readily than fixed ones, the proprietor of a western furniture com- pany devised a novel form of display for his windows. The goods were placed ona moving platform, or series of carriages which rolled in endless-chain fashion the full length of the window, so that the dis- play was completely changed every few minutes. As the articles moved, they were turned about so that all sides of them could be viewed from the street. This method of display is patented. MOVIE VOICE FOLLOWS ACTOR IN SCREEN MOVEMENTS Talking motion pictures have been im- proved, it is asserted, with an apparatus which causes the actors’ voices to follow them as their shadows move across the screen. This does away with the fixed- tone effect under the usual “talkie” ar- rangement and gives a more realistic in- terpretation of the action. It also is said to eliminate distortion. The apparatus is fitted to the camera taking the pictures and recording the voices.

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426 POPULAR MECHANICS LIGHTER FITS IN LAMP SOCKET FOR SMOKER’S EASE Lighter Attached to Lamp, and Close View of the Cord and Sockets, Showing the Push Button Screwed into a lamp socket in the same way as a bulb, a lighter for cigars, cigarets - or pipes has a long cord and also contains alamp switch. It gives a decorative touch to the room and is always in a convenient position for use. CANDLE SIXTH OF WAY TO MOON SEEN BY GIANT TELESCOPE If a lighted candle could be placed 41,000 miles from the earth, about one-sixth the distance to the moon, its flame would still be visible through the 200-inch telescope planned for the California Institute of Technology. Dr. Walter S. Adams, di- rector of the Mt. Wilson observatory, re- cently explained this and other features of the huge instrument, which will reveal many more of the secrets of the heavens. Its mirror, he explained, will collect about 1,000,000 times as much light as the human eve. Stars from five to ten times fainter than can now be registered on the 100- inch telescope on. Mt. Wilson, will be shown. So far, astronomers have been able to determine that there must be a million or more nebulz, mysterious sys- tems of stars lying far out in space. The new glass will probably show that there are many more, and it will doubtless enable scholars to learn more of the nature of the stars that compose them. Some of the in- teresting things about the nebulz are il- lustrated by Andromeda, 870,000 light years from the earth. Its light is about a billion and a half times as great as that of our sun, and its mass probably five hundred million or a billion times as great, astronomers have estimated. LEATHER MADE TRANSPARENT FOR AUTO HOODS By a special tanning and chemical treat- ment, a kind of transparent leather is be- ing produced by an English expert. It is said to be stronger than canvas and espe- cially suited for automobile hoods, to- bacco pouches, raincoats and similar ar- ticles. It is also used as a substitute for gut in sewing leather, and as small belts for lathes, looms and sewing machines. TOWN HISTORY UNDER ROOF GUIDES TRAVELERS Persons passing through the village of Bentley, England, are likely to remember it, for in the center of the main street is a thatched pavilion under which is a large replica of a book bearing the important facts of the town’s history since 41 A. D. English Town’s “Name Plate” Consists of a Big Book under Thatched Canopy Giving Historical Facts The marker has proved a helpful guide to motorists and attracts wide attention. to ic) fre tu mi es: an me mé pre it | me ani un Viv foc Tea tur the pro Sta Was

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rf e it 300k Courtesy Die Woche Imagine a Little Three-Inch Garden Lizard, Enlarged to the Size of a Dinosaur of Old, Chasing You through the Woods, and You Get the Effect of This Composite Photograph \ JHAT would happen to civilization if the little garden lizard ever grew up to be the size of his ancient relative, the ichtyosaurus, and all the other insects and reptiles assumed the size of the monsters from whom they descended ? That is hardly apt to happen, for na- ture, millions of years ago, discovered the monsters were inefficient and in the proc- ess of evolution finally came down to the ant as the highest type of insect develop- ment, and man as the best of the mam- mals. From the beginning of time the process of creating the world as we know it today has been one of unending experi- ment, nature discarding one form after another, of plants, insects and mammals, until she found the types best fitted to sur- vive, and the proper balance to insure a food supply for all. The problem of food supply is the chief reason why there is small chance that fu- ture evolution may ever go back toward the monsters of the past, just as it is the problem that some day will face the con- stantly growing human race. Once there was a dinosaur that grew to be 150 feet long, stood twenty feet high at the shoulder, had a neck reach of thirty feet or more, and weighed, according to the best calculations, somewhere around thirty or forty tons. Even his little brother, the brontosaurus, scaled around sixty feet from the tip of his nose to the tip of his tail, waddled along leaving yard-square footprints in his wake, and would have tipped the scales, had scales been invented then, at 40,000 pounds, which is half the capacity of a good-sized freight car. But the dinosaur and the brontosaurus, the trachodon and the tyrannosaurus, the mammoth and all the rest of the strange beasts and reptiles that once roamed the earth and the air—for there were giant fly- ing reptiles then—discovered one day they had eaten themselves out of house and home, so they laid themselves down and died. In South America there is a valley of the giants where that final tragedy of great size was enacted. There the types peculiar to South America, moving north- ward in search of new feeding grounds, met the tourist monsters which had drifted 427

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428 POPULAR down from Asia on the same mission, and today the valley is studded with the bones of the two groups, Science is just begin- ning to appreciate what an important bearing food supply has on life, whether animal, insect or human. For one thing, stature itself, according to R. Bennett Bean, of the laboratory of anat- omy, University of Vir- ginia, depends on food, water, habit and habitat, and he puts food first. There are pygmies and undersized people in the tropics and in the cold latitudes, while the taller races originate in the more temperate climes where food is most abundant and most diversified. The picture of the tropics as a land where the native need only lie under the right tree to have his dinner drop in his mouth is greatly overdrawn, for, while fruits and some other foods are abundant in the torrid zone, they are not particu- larly good body-building types, nor is the indolence born of heat conducive to the activity that makes for greater growth. MECHANICS In the far north, simi- larly, a seal-blubber diet and the necessity of keep- ing indoors as much as possible to keep warm, have made the Eskimo another of the world’s smaller races, In between the two extremes, the restless races have devel- oped, fed by a well-bal- anced diet, made restless by a comfortably brisk climate, and stimulated by habit and habitat. The rise of man as the highest type of mammal, If Turtles Were Giants, It Would Take Hand Grenades to Stop Them; the Lady Is Entertaining a Ruffled-Neck Bat with the intelligence to grow part of his own food and capture and kill the rest, may have been the natural result of chang- ing conditions in food supplies. Nature took care of the insects and reptiles by scaling them down until their appetites balanced with the food available. The paramount goal, a German scientist points out, was always to keep an exact balance between hunter and prey, eaters and food supply, in order not to put an end to organic life when the last victim

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the 1iS st, ig- ire by tes ist act ars, an im POPULAR MECHANICS 429 should be devoured. For this reason, he adds, and to make possible for man a future development that would include such luxuries as radio and tele- vision, the wild animals were gradually reduced in size and numbers. To- day the elephant is the largest survivor, but even he has been largely do- mesticated and put to work. “But imagine if you can,” he adds, “the lowly Sh garden inhabitant, a hese " Roly .sS LOSS ; grasshopper, the size of an elephant ' What if an ant A Hawk Enlarged to the Proportions of an Ancient Flying Lizard, as large as a tiger, a fero- cious panther on six legs, with monstrous fangs and burning breath, broke out of the jungle? Thanks be to the Providence that spared us the necessity of contending against an insect world of such dimen- sions. No further proof is needed that ants, four or five feet in length, would and a Crab as He Might Have Been Long Ago then have become the masters of the world. Look at nature through the micro- scope. A horned beetle is a rhinoceros in size, a veritable nightmare. What would become of our philosophy of life? It would be bankrupt, fear and horror would be the only emotions awakened in

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430 POPULAR us by a contemplation of nature. Civili- zation was made possible on our earth by the balanced relation of human and other life and their interdependence. But on another planet the insect world may have won out. The mammals, perhaps, expired on Mars, and its world may be ruled by scaly creatures, wise iri their way but armed with claw and fang.” What the future is going to hold for in- sects, animals and man on earth can only be foretold by examining the past, and it is there that the zoologist, the anthro- pologist and the other scientific research leaders come in. The question most often asked the scientist by the layman is, “what good does your work do?” Piecing to- gether the discoveries of this group fur- nishes a fascinating picture of the rise and fall of life through the centuries. The gigantic reptiles‘of a few million years ago didn’t come into being as mon- sters. They started out, undoubtedly, on a small scale. Roaming through a young world, with plenty to eat, they gradually grew in size. Nature helped them along in their fight for survival by gradually adding scales and bony armor to resist their natural enemies. With plenty of food, there was no limit to their growth. - But as they grew in size, and as their pro- MECHANICS tective armor reduced losses from natural causes, they slowly filled up their terri- tory until eventually there was an excess of population over food supply. Exactly the same thing can be seen happening today. Rabbits, for example, will increase rapidly in a period of good years, until lack of food, disease, epidemic, or a cor- responding increase in their meat-eating enemies, brings them down again, and the cycle starts all over. Most of the early monsters were hybrid land and water beasts, and the great size and ponderous movements of all the spe- cies, with the possible exception of the mammoth, rather limited the zone of their feeding activity. Eventually they had to begin spreading out in search of more food. Probably the older and stronger kept crowding the younger and the weaker away. If, as seems probable, the reptilian life originated in what is now the Gobi desert, but was then a rich tropical jun- gle, the animals eventually went far afield, for they crossed the land bridge from Si beria to Alaska before Bering strait was formed in a later ice age, and shoved southward through Canada, leaving myr- iad bones in Alberta, down through the United States, with a trail of carcasses in Montana, Utah, Colorado, Arizona and Just a Little Water Beetle in His Native Element, But a Fearsome Monster When His Picture Is Enlarged to Giant Proportions and Overprinted on This Berlin Street Scene

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POPULAR Texas, through Mexico, Central America and into South America. There they met the northward-moving horde of distinctly South American species and the final bat- tle with starvation was staged. That is the picture of what happened a few million years ago, as science has pieced it together. First, nature, by armoring the giant vegetarians against the meat eater, brought about overpopulation, upsetting the balance that nature usually main- tains, and then exhaustion of the available food supply, particularly after the advance of the next glacial age which cut down the semitropical jungle area of the north- ern latitudes, did the rest. The human race at times suffered just as severe changes, and science has begun to study them. The west coast of South America, down in the windswept, barren, rainless district from which Chile exports a large share of the world’s nitrate supply. was once one of the most prolific garden spots in the world. It is now a treeless desert, a lonely waste in which virtually no rain falls, where the hillsides are bleak and brown, one of the most monotonously lonesome coasts in all the world. But recent excavations in vast graveyards which show the region once supported a vast population, have uncov- ered burial urns containing corn, wheat and other grains, remnants of cotton cloth that show a great cotton-growing indus- try flourished there, and other relics of prosperous, well-fed times, HAND MIRROR WITH ANCHOR LATEST TRAVELER'S AID MECHANICS 431 A Turn of the Wrist Adjusts Shade and Bulb of This Handy Bridge Lamp to Different Angles BRIDGE LAMP IS ADJUSTABLE AT PRESS OF BUTTON Two lamps are combined in one for the convenience of the home in a stand that has a shade and bulb which may be tipped down or set erect by pressing a button. The lamp has two intensities of light, for close use or for general illumination. RAISING KARAKUL SHEEP FUR NEW U. S. INDUSTRY Near Goldfield, Nev., a number of kara- kul sheep are being raised for their fur which is used in making coats and other garments. Until recently, practically all the world’s karakul sheep have been pro- duced in Bokhara, which before the World War had For the railroad or auto tourist, a hand mirror that can be attached to almost any surface by a vacuum cup, has been intro- duced. It is in- stantly adjusted or taken down and has an arm _ that can be turned to different angles. It is held in a strong flocks numbering 1,800,000, but they seem to thrive inthe climate of southern Nevada, and this activity promises to become a profitable industry. The kara- kul is the only sheep that -produces fur instead of wool. The lambs are born with a heavy coat of glossy black or frame of rust-proof metal. Close View of Mirror with Its Cup and Some of Its any Uses pelts are used early. brown and their

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432 POPULAR MECHANICS elements, are opened and closed by means of a small lever on the base of the unit. GERANIUM KILLS BEETLE THAT IS FLOWER PEST Japanese beetles, one of the dreaded _pests of the gardener, are fatally affected by the leaves or flowers of ordinary geraniums, Charles H. Ballou, of the depart- ment of agriculture, has discov- ered. Dissection has shown that the geranium destroys a part of the beetle’s digestive tract within twenty-four hours, and that all the soft contents of the body A Roller Coaster in Summer and a Sled in Winter; the Adjustable Rig with Its Pusher That Gives Good Exercise COASTER FOR SNOW OR GROUND GIVES GOOD EXERCISE Quickly convertible into a roller or a runner coaster for ground or snow, a speedy sled, propelled by pulling and pushing a lever, has been placed on the market. It can be changed from one form to the other in a few minutes, small rub- ’ ber-tired wheels being attached for ground operations. The pusher, which works on a collapsing extension arm like a folding hat tree, has a sharp point for gripping snow or ice and an effective gripper for the ground or sidewalk. The sled itself folds up for easy carrying, weighs but a few pounds and is so strongly built that two large men can ride upon it in safety. AUTOMATIC TOASTER OPENS UP LIKE A BOOK An automatic toaster, which browns both sides of the bread at the same time and has the novel feature of open- ing like a book, = is one of the latest electrical appliances on the market. The sides which contain the two heating cavity are disintegrated within forty-eight hours.. The insects manifest a peculiar fondness for the plant, in spite of its fatal results, and will fly hundreds of yards to find baits which have been scented with geraniol, the basis of the geranium odor. STARTING LEVER FOR FORDS LEAVES FEET FREE Easily installed and handy to reach, a starting lever for Model-A Fords replaces the usual button or rod, It is brack- eted to the steer- ing-column sup- port, is operated by simply lifting the finger and leaves the feet free for brake and clutch. The installa- tion of the lever requires no alterations or drilling of extra holes. ELECTRIC SHOCKS KEEP FISH FROM IRRIGATION CANAL Electrified screens have been erected at the openings to irrigation canals in va- rious parts of the west to keep fish from entering the channels. A low-frequency current is used and does not injure the fish, but gives them a distinct warning to keep away from the headgates. T. Sig

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a- at m cv he POPULAR MECHANICS 433 TALKING MOVIES SENT BY RADIO FROM ORIGINAL NEGATIVE Talking movies, which, it is claimed, can be reproduced on any size screen, are transmitted by radio by a new device in- vented by a Luxemburg scientist. The apparatus is expected to be particularly adaptable to quick transmission of news- reel subjects, as the original negative is used, eliminating the delay while a posi- tive film is made. The transmission and reproduction do not necessarily take place at the same time, as a transmitted picture can be stored for future use. The film is transmitted in the usual way, but at the receiving end is recorded on a series of fine metal ribbons, so it can be “played” later, just as a phonograph record is used. The accompanying sounds of a “talkie” can be registered at the same time. The quality of the reproduced image is said to increase with the size of the screen. AUTOISTS REQUIRED TO SPEED ACROSS MIAMI VIADUCT Speed of less than thirty-five miles an hour is prohibited to motorists while driv- ing across a viaduct at Miami. This rule is to prevent traffic congestion and is said to have had a beneficial effect in this re- spect. Violators of the rule are charged with parking. ; | You MUST GO | 35 MALES Pee HOUR | OVER THIS VIADUCT Sign on the Miami Viaduct, Warning against Driving at Less Than Thirty-Five Miles an Hour Testing the Sap of the “Cow” Tree; the Liquid Tastes like Milk, Explorers Say TREE IN TROPICS GIVES MILK LIKE THAT OF COW Sap from a tree that grows in a certain part of Guatemala, looks and tastes like cow’s milk, Prof. Samuel J. Record, of Yale University, and a member of a re- cent expedition from the Field Museum of Natural History, reports. He says that the natives use it in coffee and for making desserts. It sours easily, like real milk. NEW FIREPROOF INK PROTECTS LEGAL DOCUMENTS For the use of attorneys and others de- siring a material not affected by blazes, a fireproof ink has been prepared by an English expert. He employs a mixture of chemicals with varnish and a specially treated lampblack. If fire attacks a paper on which the liquid has been used, the ink is not obliterated but turned to a brown- ish-black tint. Used on fireproof paper, it becomes transparent after a fire. The paper is mainly of asbestos and fiber.

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Testing Automatic Sprinkler Heads to Determine Whether Corrosion, Suffered during Use in Industrial Plants, Is Sufficient to Prevent Their “Popping” at the Correct Temperature By J. EARLE MILLER HUGE door of steel and firebrick rolls upward, opening the portal to the fiery pit. The roar of gas-fed flames, after rag- ing for hours, has died away, leaving be- hind red-hot bricks, and, in the center of the furnace, a big steel office safe. Work- men tug at a block and tackle, and the safe and its iron platform come rolling out on a track laid in the floor. Shielding faces with upraised arms while their clothing smokes and steams, two men dash in, shove an iron grating be- neath the safe and affix chain slings. There is a rattling of tightening links and the glowing mass disappears up a smoke- grimed shaft rising through the center of the building. The iron cart is wheeled aside and the floor opens up to uncover a vast slab of reinforced concrete. From the moment the furnace opened, a watcher has been counting off the sec- onds. At 120 he calls “time,” a workman pulls a trip line and the red-hot mass of steel plunges thirty feet back to earth, landing on the cement with a thud that shakes the building. A madhouse? No, just the Under- 434 writers’ Laboratories getting under way for the day’s business. Over in the corner a little group sur- rounds a miniature roller coaster, A tor- pedo-shaped steel Juggernaut on wheels, weighing a ton, rolls down the inclined track, picks up speed, and smashes with terrific force into a bright new automo- bile bumper which bends under the blow, then springs back with such force that the flying weight rebounds on its track. In- struments have measured the effects of blow and rebound, and over them bend young men with notebooks and pencils. In the next room, a fine big fire window of steel frame and wired glass is fixed into a strong brick wall. Behind the glass, flames are raging, and, as you watch, the molten glass begins to run and little tongues of fire dance through. At a sig- nal, the flames die away, the wall, window and all, rolls away on an overhead track, a man in overalls turns a fire hose on the still glowing window, and a group of ob- servers watch to see what happens when water at sixty pounds’ pressure strikes the incandescent glass.

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vay sur- tor- els, ned vith mo- Ow, the In- ; of end low into lass, the ittle sig- dow ack, the ob- rhen ; the AN Weyatetsyurcnare One of the Most Unusual Fires on Record; the Top Floors of the Fireproof Building on the Right Were Set Ablaze by Heated Air from the Conflagration across the Street Upstairs, an automatic machine is stick- ing three keys into as many automobile locks, turning them, turning them back again, and then withdrawing them, only to repeat the. performance with monoto- nous regularity. Down in the basement a board, hinged at one end, reclines against the wall, with a big copper fire extinguisher strapped to it. An arm on a traveling belt comes around, pulls the board out from the wall, then lets it fall back with a thud, comes around and repeats the performance, time after time, hour after hour and day after day, while an automatic counter registers the shocks the extinguisher’s glass insides can stand. Scattered around through several acres of floor space, a couple of hundred expert destructionists are busy earning a living breaking up the things other men have built. If you have ever bought an electrical appliance or fitting, examined an automo- bile accessory, purchased some fire hose, had your house wired against lightning, installed a burglar alarm, bought a penny box of safety matches, built a fireproof building, purchased an oil burner or a mechanical refrigerator, or done any one of a hundred and one other things that may affect your fire, burglar or accident insurance rates, you have come in contact with the Underwriters’ Laboratories. Most everything that affects your safety from fire or accident, or your burglar 435

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POPULAR risk, has come un- der the scrutiny of the laboratories. If you want to build a business structure, the architect knows not only what loads the columns and walls will bear un- der normal condi- tions, but what they can stand when assailed by flames. A com- bination press and furnace that cost $35,000 to build tells him that. Your architect wil! know what kind of fire walls, fire doors and fire win- dows to install, and when it comes to bur- glar insurance for your tenants, the labo- ratories have not only examined and ap- proved them, but they pass on and super- vise the equipment of the watchman’s service that answers your alarm. This testing has involved engineering and inventive problems that often sur- pass those of the builders of the original device. When you press a button, turn a switch or pull a chain and the electric light flashes on, you do not give the mat- ter a thought. But just as part of the day’s work a testing engineer built a ma- chine that takes either or all three of those types of electric switches and turns them on and off, day and night for week after MECHANICS week, until they wear out, while an auto- matic counter keeps track of their life span. Because of that one machine, there is built into your electric-light fixtures the maximum of life and safety. When domestic oil burners began to appear, an entirely new problem in fire hazards was presented. A battery of fur- naces was set up at the laboratory and the manufacturers’ samples began to pour in for testing. For weeks, a crew of scientists lived in the heat of a dozen fur- naces and watched the performance of the burners. They were not interested in economy of oil consumption or heat pro- duced, but solely in the possibility of fire or explosion—two things the purchaser might never inquire about. The oil burners that got by the grueling test were awarded “ap- proved” labels. At about the same time, domestic me- chanical refrigera- tors began to chal- lenge the ice man’s supremacy. They involved placing in untrained hands a highly compli- cated plant. Some Testing an Office-Vault Lock; a Giant Air-Cooled Test Coil, Five Feet High, and, Bottom, the Bullet- Proof-Glass Testing Range

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ooled ullet- POPULAR of them used gases that, under certain conditions, are explosive. Others used poisonous gases. The underwriters had to know that neither type would develop a leak and release the contents. And they had to know that the electrical pumping equipment and its automatic control switch were safe against fire. So, another corner of the fire and life- hazard department was cleared out, rules drawn up to describe a safe refrigerator, and the testing started. It still continues, as more and more makes and models ap- pear from time to time, and as samples of makes formerly approved are brought in for a check-up test. All sorts of things come in for test, and many a manufacturer has escaped great loss by finding out the weakness of his device before spending money to put it on the market. They MECHANICS 437 still chuckle in test- ing circles over the hopeful inventor who solved the automobile-theft problem for all time —to his own satis- faction—by devis- ing a combination lock and siren, the latter supposed to set up a terrific clamor if anyone attempted to tam- per with the car, and keep on_ screech- ing for the police until the owner ap- peared to stop it. The inventor equipped his own car, and then drove it around to the laboratory to be tested. He pointed out the car, stand- ing in the street, and stated his wants. The head of Attacking a Burglar-Alarm Guard with a Torch: a Flame Test on Roofing, and, Bottom, One of the Fire- Window Furnaces the burglar depart- ment excused himself for a moment, stepped outside to speak to an assistant, returned and completed the arrangements. Then he announced the test was con- cluded and invited the inventor to look out the window. His car was gone! The assistant had gone out, picked the lock and driven the car around the corner. Another good invention had been re- vealed as the possessor of a flaw. If the laboratory had not discovered the weak- ness, the inventor might have been ruined, and automobile-theft insurance rates all over the country might have taken an up- ward jump. A machine shop is maintained in the laboratory just to turn out testing ma- chines. Each problem presented requires

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a nmenncrtaen 438 POPULAR MECHANICS ratory wonderland reaches the heights of the spectacular. There is one device on which sections of composition roofings can be laid, just as in actual service, and then long tongues of flames sent swirling up the surface to see how well the material withstands fire. There is a vat in which gallons of gasoline can be poured, a match applied, and the efficiency of chemical fire extinguishers measured by timing how long it takes to smother the fire. There are all kinds of gas-fired furnaces for every kind of test. A pair of them will each take a twenty-foot- square slab of floor and subject it to any desired degree of heat for any required length of time. When.a class-A safe, the best, is to be tried by flame, it is first loaded with old books, news- papers and magazines, to see whether it will preserve its con- tents intact; then a hole is drilled through the top and a thermo- couple introduced within, to make sure the internal temperature never exceeds the permitted max- An Experiment to Find Whether the Gas Pump Is Cigarets and Carelessly Tossed Matches its own means of solution. A device that will sell for a few cents may necessitate the investment of hundreds of dollars to perfect just the machine that will subject it to the wear and tear which, within a few days or weeks, represents years of service, Did you ever see the inside of an auto- mobile muffler? Few people have, but when the insurance men began writing automobile insurance they wanted to know all about the fire danger, particu- larly from the hot and sometimes flaming gases that pass through the muffler and exhaust line. In the laboratory, a pair of engines mounted on massive concrete stands form the testing equipment. Not satisfied with ordinary backfires, the testers install spark plugs in the mufflers and ignite charges of explosive gas in them to see whether a powerful blast will tear the muffler to pieces. It is in the flame tests, though, the labo- Safe from imum of 300 degrees, and another hole bored and a pipe line in- stalled to draw off samples of the air for chemical analysis, to make sure the fireproofing compound generates no ex- plosive gases under the heat. The first test is by fire alone, lasting four hours and reaching 2,000 degrees at the end. Then the flames are turned off,and the red-hot mass of steel is allowed to cool for a day or two until a “burglar” squad can force an entrance with steel bars and oxygen torches and examine the contents. Next, piece by piece, the battered safe is torn down until every part can be scru- tinized, particularly the condition of the fireproofing between the double steel walls. If the safe gets by the first ordeal, a du- plicate, fresh from the maker’s factory, is fitted up the same way, save for the gas- pipe line and inside thermocouple, sub- jected to the flames for an hour, taken out, hoisted thirty feet into the air, dropped onto a hard concrete floor, and then allowed to cool, so the stresses and strains of contraction may have a chance

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id ol ad nd ts. u- he Is. ju- ib- POPULAR MECHANICS 439 Pulling a Safe from the Furnace, after an Hour of Intense Heat Preparatory to the Drop Test, When It Will Fall Thirty Feet to Duplicate the Drop into a Basement to rip its joints apart, if they can. When it is cool, it goes back into the furnace, this time upside down, and stands another hour of fire, following which it is opened and the books inspected. The ceaseless fight against burglars is as thrilling as the battle against fire. First science “perfects” an unbeatable safe, then craft finds a way to destroy it. Science studies the method, and comes back with a superior product, proof against the latest attack. Criminal cun- ning starts all over again, and the cycle is repeated. Years ago, the manganese-steel safe was hailed as the last word in burglar-proof- ness, for it was too tough for the hardest drill, and without a drill the “yegg” could not get an opening in which to plant his nitroglycerin. Then came the oxyacety- lene torch, which could burn through even manganese in a matter of minutes. So safes were designed with the idea that, if an enterprising torchman tried to burn his way in, he would destroy the contents before he could effect an entrance, an argument that was expected to keep the most enterprising yegg away. But one morning a Michigan banker came down to work and found his fine new safe had been looted during the night—a supposedly impossible achievement. His complaint, relayed by telegraph, brought a platoon of burglar and safe experts to the scene. They found that a master crook had melted a tiny hole through the top of the safe with a torch, inserted a funnel, filled the safe with water, and then proceeded to burn out a section large enough to lift the loot through, while the water protected the paper money from the destructive heat. In recent years, the manufacturers have concentrated not on building safes that can’t be burglarized—for they agree that is impossible—but on safes that will re- quire more time and tools than the burglar can bring to bear.

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440 POPULAR Photographed While Making a Steep Bank, the Big War Plane Reveals Its Huge Projectile, the 2,000-Pound Torpedo Carried on the Underside of the Fuselage MECHANICS south Pacific. The ves- sel’s oscillator, which sends out sound waves from the keel to the bot- tom of the ocean so that a measure of the water’s depth may be obtained by timing the return of the echo, was out of com- mission, and, for a time, the scientists were at a loss for a substitute. Fi- nally, a shotgun was at- tached to the end of a pipe which was extended twenty feet below the surface of the water. When the gun was fired, the sound waves traveled to the bottom and re- tutned as an echo, just as they did with the regular apparatus. Capt. J. P. Ault, commander of the “Carnegie,” said that the shotgun method checked well with depth measure- ments made by lowering a sounding wire to the bottom. RARE PINK WOOD IS FOUND IN ZULULAND BIG AIRPLANE CARRIES TORPEDO WEIGHING ONE TON A torpedo, weighing 2,000 pounds and capable of sinking a battleship if exploded at the right spot, is the formidable weapon carried by a huge English airplane. The projectile is attached to the bottom of the fuselage and is launched with special ap- paratus. In spite of its heavy load, the plane is a fast one and is easily handled in the air. SHOTGUN FIRED UNDER OCEAN TO MEASURE ITS DEPTH How a shotgun served the cause of science is the story recently reported from the non-magnetic yacht “Carnegie,” which is now making a scientific tour of the A sample of rare wood is now on display at the Field Museum of Natural History. In days past, possession of the material by anyone except a king was an offense punishable by death in Zululand, where the wood was found, by Bruno Lessing after a search of three years. Its rarity is indicated by the fact that the whole country was combed for a bit of it two years ago when the Prince of Wales wanted a piece suitable for a cane, but none was found. The museum sam- ple was presented by Prof. Samuel J. Record, research ‘associate in wood tech- nology. The wood is of a delicate shade of pink and in hardness and appearance is like ivory. Spears of it were symbols of regal authority among the Zulu leaders. @China is one among the best of Ameri- ca’s customers for dyes.

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POPULAR MECHANICS 441 TYPE SET BY TELEGRAPH WITHOUT AN OPERATOR mr r = ereeenens RECEIVING — RECEIVING EDITING | PRINTER PERFORATOR PERFORATOR

tesa . 0

The Heart of the Automatic Telegraph Typesetter Is a Perforated Code Strip, through the Holes of Which Electrical Contacts Are Established to Operate the Type Machine

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442 POPULAR Safety Belt for Traffic Policemen with Its Red Reflector in the Center RED-SPOT BELTS FOR POLICE GUARD THEM FROM AUTOS Policemen in an eastern city are being equipped with belts that have red reflec- tors on them so that motorists, driving at night, will be less likely to run into the officers. .The plan was devised by a ser- geant of the city’s police department and also recommends that spotlights have red lenses to give the traffic men additional warning of cars. These reflectors are com- monly known as “cat’s eyes.” SEA DIVER HELPS BUILDERS DIG FOUNDATIONS To help sink foundations for the new department of commerce building in Washington, D. C., a deep-sea diver was engaged. He descended several feet be- low the water at the bottom of the exca- vation to dig a well from which water was pumped to reduce the pressure in the sur- rounding area. So far as known, this was the first time a diver had been employed on a building at the nation’s capital. MECHANICS GOLD FOUND IN THE ANTARCTIC TO BE MINED WITH STEAM Rich deposits of gold that may be mined with steam jets are likely to be discovered in the Antarctic, according to Sir T. W. David, an engineer who is familiar with the lands far to the south. He found seams of coal in the cliffs of the great Beardmore glacier, and under the coal are formations of granite and clays where gold often is found. Should the metal be discovered, there would be abundant coal to make steam for mining operations. In ages past, the Antarctic regions enjoyed a mild climate and were covered with dense forests of pines and ferns and with swamps, geologists believe. Gold fields are now being worked at Tierra del Fuego, at the tip of the South Amercan continent. They are a part of a formation that ex- tends far into the Antarctic. AWNING AND SCREEN IN ONE PREVENTS DRAFT Window awnings and two screens have been combined by a western inventor to keep out rain and drafts when the sash is raised. The entire outfit is collapsible and easily taken off or installed. The Awning and Screens Combined Allow Window to Re main Open When It Rains awning may be used at the top or the bot- tom of the window as desired. @ Many kinds of insects injurious to crops are devoured by sparrows. ~~ 7 ao = = | YO

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IC ned red vith und ‘eat -oal ere | be ‘oal In da nse vith elds ez0, ent. have r to sh is sible The to Re - bot- crops | Phcheater Average Householder does not realize complete home-heating efficiency from the winter supply of costly fuel that he burns because his residence is not properly insulated. Downstate in Illinois, where one of the largest universities in the world is located, eminent engi- neering experts have built a remarkable low- temperature testing plant which is being used in part to determine where house heat goes and how to save it. If you doubt that losses of heat occur through walls, floors and ceilings in uninsulated homes, scan the following facts carefully and change your opinion on this sub- ject. A recent tabulation of the heat losses from 200 average uninsulated American homes, located in New York, Michigan and Ohio, explains concisely how Boreas, Jack Frost and King Winter apparently conspired unintentionally with ordinary builders to waste valuable heat with which these home owners hoped to keep their houses warm and comfortable in the cold- est weather. The loss of heat through walls averaged twenty-seven per cent, while the loss through glass windows and doors amounted to 25.8 per cent. An- other 24.6 per cent of the heat units stole away by infiltration—the leakage of heat through air cracks and crevices, The ceil- ing as a wastrel of house heat allowed 16.2 per cent of the warmth to filter out- side instead of keeping the home family comfortable. A final loss of 4.3 per cent of the heat supply through doors ended this disagreeable picture of fuel extrava- gance, House. Heat Gges Low-Temperature Test Plant Where Heat-Loss Puzzles Are Studied In co-operation with the National Boiler and Radiator Manufacturers association and the Illinois Master Plumbers associa- tion, the University of Illinois is now mak- ing tests of steam and hot-water heating systems in a modified constant-tempera- ture chamber built in the form of a house within a house The novel low-temperature testing plant has been erected in a large engineering laboratory. The outside walls of this prov- ing ground of heat distribution are com- posed of six inches of corkboard—efficient insulating material. Two walls of stand- ard construction for the two identical test rooms, respectively, with large air spaces under the floors and above the ceilings, are incased within the insulated structure so that the heat that filters from them under varying conditions may be measured. The insulated walls of the large refrigerated room form the two remaining walls of each of the test rooms. 443

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444 POPULAR MECHANICS The exposed inner walls can be changed on the completion of each experiment. In this way, all types of build- ing material and insu- lation can be tested thoroughly. Accurate knowledge of the effi- ciency of every material will result from the research, which will be continued for several years, or longer, until all the rid- dles of house insulation and the preven- tion of heat losses have been ferreted out. The basement and attic spaces aid in exposing the floors and ceilings of the twin test rooms—each is nine by eleven feet in dimensions and nine feet high—to air of any desired temperature. The base- ment spaces resulted from elevating the floors of the two “scientific cells” two and one-half feet above the floor of the re- frigeration chamber, while the attic space was obtained by building the test-room ceilings three feet below those of the cold- insulated chamber. These overhead and underfloor spaces, as well as the other un- occupied space in the cold chamber, can be heated to any desired temperature. By means of the system of refrigerating coils, the series of electric heaters and an adequacy of ventilating fans, placed at key positions within the cold chamber, the scientists can duplicate any range of conditions which might exist in a house, while they also can simulate practically all outdoor conditions except rainfall. The simple readjustment of control devices can shift the temperature from arctic cold to tropical heat in record time. The weather generated in this testing plant is capable of constant control and regula- tion to the fraction of a degree. The various points in the test rooms where heat escapes during any of the ex- periments are “spotted” forthwith by reliable “patrol- men”—the many elec- trical temperature recorders which are distributed here, there and everywhere throughout the walls, Tracing Air Currents with Fumes; Examining Heat Re- corders, and Adjusting Thermocouples at Different Dis- tances above the Floor

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ure are lere ere alls, eat Re- mt Dis- POPULAR MECHANICS 44 uw floor spaces, ceilings and in other strategic posi- tions where they may de- tect run-away heat The customary practice dur- ing one of the tests is to maintain a standardized temperature of zero in the cold chamber while the thermometer sta- tioned at the normal breathing line within either of the test rooms simultaneously records seventy degrees Fahren- heit. In a word, the ex- perimental radiator or other heating unit under test is made of such size and heat-distributing ca- pacity as to maintain that temperature constantly. A temperature as low as five degrees below zero can be maintained in the cold chamber as long as desired, while the efficient utilization of electric fans facili- tates the accurate imitation of wind action on and in the walls of the research rooms Ordinarily, the tests are conducted under still-air conditions, but in a certain test, if a miniature wind storm is desired, all that is necessary is to switch on the bat- tery of electrical fans and to study their effects on the normal heat losses which occur under such conditions An interesting feature hinges on the “smoke tests,” which are made to observe and register the movements of air cur- rents in the test rooms during the multi- plicity of heat-loss experiments which are being carried on. By use of a metal stand with adjustable shelves for dishes of chem- icals, which can be raised or lowered as desired, white fumes are liberated at va- rious distances above the floor and below the ceiling. The drift of these fumes pro- duces a tangible record of the direction in which the air currents are moving. There are two windows in each test room, located in one of the exposed walls which face the cold chamber and its icy blasts of winter weather. There is also a door leading into each room and a cen- tral passageway between the two rooms. The outer door is insulated and of heavy Tabulating the Records as They Come In by Wire during One of the Heat- Loss Experiments refrigerator construction, as it is the out- let through the cold chamber. The test radiator, shown in the accompanying illus- trations, is located in the usual position di- rectly underneath the windows, The plant is adapted, however, for testing any type of house-heating equipment placed at va- rious locations in the room, or in the ex- posed walls as invisible sources of heat In certain homes which appear well- built and comfortable, as much as one-half of the average winter fuel supply is wasted in vagrant heat which shirks indoor work and flows away through uninsulated floors, ceilings, walls, windows and doors, it has been shown. A thorough insulation of the ceiling may cut down one-half the normal heat loss through that part of the house at once, but it may represent only one-tenth of the total heat loss from the room. Plaster-and-lath construction for walls and ceilings, so builders say, is only about one-half as retentive of heat as similar construction where the dead-air spacing between the studding is filled with satis- factory insulating material. This is true where wall area alone is considered with- out any reference to window openings. Storm windows are more satisfactory in reducing heat losses through windows

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446 POPULAR MECHANICS Installing a New Heating Unit in One of the Test Rooms; the Exact Amount of Heat Produced Is Measured by a Simple Steam-Condensation System than the ordinary metal weatherstrips, be- cause the latter only check the flow of air through cracks while the former reduce the heat transmission through the single pane of glass by providing a dead-air space between the two glass surfaces, It is safe to say that the heat losses in the 200 typical homes in the cold-weather belt, referred to previously in this article, could be reduced from one-third to one- half by practical modern insulation meth- ods, the use of storm windows, calking the window frames and door frames with oakum or similar material, and filling the dead-air spaces in walls and above ceilings with suitable insulation. The important research at the Univer- sity of Illinois will yield facts and figures which will aid potentially in stamping heat losses and costly fuel waste from the cal- endar of winter worries of the average householder. This will in the future save billions of tons of coal. Our homes will be maintained at stable temperatures dur- ing cold weather and, under normal cir- cumstances, a measurable reduction in mysterious drafts will be apparent. Engineering research, by its remarkable heat-loss tests in the house within a house, adds another scalp of worth-while achieve- ment to its many trophies of successful accomplishments. CLAMP TO HELP HOLD WORK LEAVES HANDS FREE To hold strips in place for nailing, and for many similar tasks, a spring clamp is al- most as useful as an extra man, for it leaves the hands free. It snaps in place in a second, has a strong grip and is handy on many occasions. DESIGNS ON NEW PAPER MONEY TO CURB RAISING BILLS Fraudulent alteration of bills will be practically impossible with the _ new, smaller paper money soon to be placed in circulation. The principal reason is that the designs are restricted. For example, George Washington’s portrait, which has been on both one-dollar and twenty-dollar gold certificates, will appear only on one- dollar bills of the new issue. Other de- signs will be confined wholly to certain — nn - a a = a. —

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and s al- il as ‘. for ands s in ond, grip - on ns. JEY 1 be new, -d in that nple, | has ollar one- - de- rtain POPULAR denominations, According to careful esti- mates, the new money will save the gov- ernment at least half a million dollars in its paper bill annually. Four additional notes will be made from a sheet of paper. In the opinion of W. H. Moran, chief of the secret service, the new bills will not stop counterfeiting although they will make the-task no easier, for it is just as dificult to counterfeit a small note as a large one. ARMY BLANKET RESISTS WATER AND IS TWICE AS WARM Said to have twice the warmth of the usual kind and be more resistant to water, an improved blanket has been developed forthe army. Ina test, one was subjected to water for sixty hours, but was not pen- etrated although no waterproofing com- pound was used. The material is light in weight, can be manufactured in any worsted mill and will make excellent lin- ing for trench coats. WINDOWS THAT TIP INWARD MORE EASILY CLEANED Both upper and lower sash of improved windows pull inward from the top and lie flat, locking at a convenient height for washing from the inside. In an up- right position, they move up and down freely. The sash can Window in Va- rious Positions, to Show Ease of Cleaning It from the Inside be installed in old or new frames. MECHANICS 447 ALL-METAL AIRSHIP TO TEST CONSTRUCTION THEORIES 7 'S A ieeg dees. ene Tt. |) Sections of the All-Metal Airship, Being Prepared for Assembly and Trial Flight Flying engineers are awaiting with in- terest the completion of the navy’s all- metal dirigible, scheduled for launching at an early date at a Detroit plant. It is 150 feet long, fifty feet in diameter and is made of duralumin instead of fabric. The “bag” part was made in two huge sec- tions, as shown in the accompanying illus- tration, and then fitted together. ELECTRO PROCESS FOR PATTERN ELIMINATES SHRINKING .Patterns for making metal objects are prepared in copper by a recently devel- oped electric process for which several ad- vantages are claimed. Among them are an elimination of shrinking as now occurs when making a pattern in the ordinary way from a master pattern of wood or metal; economy of time and labor when many patterns are made; elimination of machining, and greater accuracy. It is stated that the error in patterns made by this process is within .003 of an inch.

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448 POPULAR MECHANICS Rare Snapshot of Mother Goat and Young, with Views of Photographers in Disguise HUNTING GOATS WITH CAMERA REQUIRES DISGUISE Photographers with a recent expedition in the Rockies wore white costumes with horns and whiskers while stalking moun- tain goats with their cameras. The dis- guise was. of aid in helping the men to approach the animals, which are exceed- ingly wary and difficult to photograph. FLOWERS KEEP FRESH LONGER WITHOUT CHEMICALS Cool, fresh water, without the addition of chemicals, is the best medium for pre- serving the freshness of cut flowers, tests at the Boyce Thompson institute for plant research have shown. More tlfan forty- three chemicals were used in the experi- ments, but comparison with flowers that were kept in plain water clearly indicated that the substances did not add to the life of the flowers. EDISON EXPLAINS COST FACTORS IN PRODUCING POWER Generating electric power at a hydro- electric plant is but a small part of the total cost, Thomas A. Edison recently ex- plained. Often, from seventy to ninety per cent of the total expense comes in de- livering the electricity to the consumer after it has left the generating station. The real test of economy in electric-power production lies in the final cost of the energy when it is delivered to market, he pointed out. “Approximately eighty per cent of the undeveloped water power of the country lies in the Rocky mountains and in the Pacific coast region,” he said. “The large market for power, unfortu- nately, is east of the Mississipi. Great as have been the advances in transmission of electricity, the art has not yet reached a stage when it is probable, or even possi- ble, that electrical energy can be trans- mitted from the Pacific to the Atlantic.” He showed that about seventy-two pef cent of the country’s water power is in territory embracing only twenty-one per cent of the country’s power requirements.

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life RS lro- the ex- nety | de- mer tion. wer the t, he per -r of tains said, ortu- at as on of ed a yOSsI- rans- ntic.” ) per is in e per nents. POPULAR MEASURE OF BEES’ BREATH SHOWS INSECTS’ HEALTH To spend time investigating the ques- tion of the bee’s breath may seem super- fluous, but scientists have determined that besides giving a clue as to the health of the hive in the winter time and in the summer, the breathing is an index to other interesting facts about the colony. Prof. G. H. Vansell, of the University of ° California, rigged an apparatus by which he could measure the ¢arbon dioxide and the water vapor given off by a colony of bees in both winter and summer. He led the air coming from the hive through a tube filled with absorbent chemicals and by weighing these, after making proper allowances, he was able to get an hourly analysis of the breath of the hive. In win- ter, when the colony was reduced in num- bers and the bees were quiet, the average hourly water loss from the hive was thirty- six millionths of an ounce. In summer, the quantity of water given off was nearly twenty-five times as great because of the increased number of bees and their greater activity. At times, the wintering cluster of bees gave off air that contained less water than the outside atmosphere, indi- cating that either the bees or their stores of food were, at such times, absorbing water from the air. GAUGE IN AUTO RADIATOR CAP SHOWS WATER LEVEL To show the quantity of water in the radiator, a patented cap especially for tractors, has a float valve with a projec- tion visible from the driver’s seat. Suitable pack- ing prevents leaks, © E. H. Mears qour Bureau of Information will answer all questions regarding articles appearing in this magazine, MECHANICS 449 Toll Bridge over the Cannonball River in North Da- kota with Its Grooved Track for Autos GROOVED BRIDGE FOR AUTOS SAVES BUILDING FLOOR Built especially for automobiles, a toll bridge over the Cannonball river in North Dakota has parallel grooves for the wheels instead of a floor. In case horse-drawn vehicles approach, the animals are un- hitched and waded across the stream while the vehicles are pushed over the bridge by hand. SPRING TAG FOR DOOR KEY FOILS BURGLARS To help keep burglars from entering doors with the aid of pass keys, a spring- steel tag that is at- tached to the key prevents forcing it out of the lock ex- cept from within the house, A hook, which is part of the tag, fastens over the door knob after the key has been turned, thus holding it firmly in the key- hole:

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Sinking Bignell Pile from A-Frame Derrick and from Railroad Viaduct; Note Side Jets of Water 45u By PAUL D. PADDOCK A PERPLEXED engineer stood watch- ing a pile driver at a bridge site on the Platte river. With every stroke of the big hammer, the pile would go down sev- eral inches, but, to the engineer’s disgust, it would bounce back again. Quicksand! It held the pile as in a mass of sponge rubber. Caissons were out of the ques- tion. The engineer pondered and then necessity gave birth to an idea. For some time, on jobs such as this, en- gineers had been using a pile with a hole running the full length of the center, through which a column of water was forced at high pressure to clear away sand at the bottom, but this plan worked only moderately well, for, in quicksand espe- cially, the material closed tightly about the body of the pile along the sides. Edward Bignell, the worried engineer, made a great improvement. He was unaware of the fact at the time, but his idea was to prove an important factor in one of the most romantic undertakings of all ages— man’s struggle to control the mighty Mis- sissippi system, that great network of rivers which drains more than forty per cent of the United States all the way from . || SR SSA SS) ee ape Sag ing liqu aro pro upw the like bur: kep hare dati H occt esti such calle Mar orga the othe Wor farm the goug

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st, 1! ge en n- le er, nd ily pe- the ard of to the Lis- of per “om Weaving Timbers to Form Revetment for Strengthening a River Bank; This Mattress Is Spread Well Up on the Shore and Out in Stream, Weighted with Rock and Sunk the Alleghenies to the Rocky mountains. He bored crossholes in the pile at in- tervals of about four feet, forming side apertures leading from the central pas- sage. Water, gushing out of these open- ings, surrounded the pile with a film of liquid, keeping the sand from squeezing around it. He made a still further im- provement. He projected the side jets upward by attaching upturned nozzles to the openings. The result was something like a downward-speeding skyrocket that burrowed its way through the sand and kept on going until it came to rest on a hard stratum to help form a stanch foun- dation for the bridge. He wisely patented the pile, and shortly occurred the second episode in this inter- esting chain of events that were to have such an important effect on America. He called one day at the office of a friend, Mark Woods, president of the largest organization in the country engaged in the protection of property along river and other water fronts. It happened that Mr. Woods had purchased a Missouri bottom farm that was disappearing in chunks at the rate of 100 acres a year as the river gouged out the banks and swept them to the Gulf. In Bignell’s pile he saw a means of permanently anchoring retards to slacken the river’s speed and thus make it dump part of its load and build up the land instead of tearing it away. For years, the retard idea had been employed, but the structures did not last. They had in- sufficient anchorage. A flood or an ice jam—and out they went, carrying with them the land that had been piled up, plus a few acres of the richest soil on earth. Careful measurements have shown that, between its mouth and Sioux City, Iowa, the Missouri river alone is carry- ing away more than 10,000 acres of land every year. Mr. Woods hired men to place retards along his farm and anchor them with Big- nell piles. They held. His land stopped slipping away and began to grow. Bank erosion was effectually counteracted. Be- fore long, his company was installing these retards for other property owners and for railroads whose tracks and bridge cross- ings were constantly in danger of slipping into the stream. The business grew by leaps and bounds, Today, the Woods organization employs between 1,500 and 2,000 men on its river 451

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452 POPULAR projects and uses 120 river craft of various kinds, including a dozen steamers, inter- esting stern-wheelers of the packet days, now busy at the useful task of helping to subdue the streams over which they have struggled for so many years. Just re- cently, the company has completed more than forty projects along the Missouri alone, while work has been done or is under contract on nearly every important river in the United States where similar conditions demand protective measures. The company has a six-passenger airplane for inspection and survey work over sites of operations. In an hour, engineers in the plane can learn more of the require- e Drawing to Show How Re- tards on Concave Side of the River Bend Cause Formation of Land to Prevent Further Destruction, and Aerial Pho- tograph of Missouri River near Lexington, Missouri ments of a project than they could in days of ground surveys, because the river can be seen over several miles of its course at once, MECHANICS and the location of works in relation to each other can be determined accurately and quickly. 4 The Bignell pile, purchased by Mr. Woods primarily to save one of his farms, has thus turned out to be a magic-work- ing aid for the entire country. Along the Mississippi and Missouri rivers, the piles are often sunk to a depth of forty to sixty feet below the stream bed. The river piles are like gigantic needles, fifteen or twenty feet long, sixteen inches square and weighing from 3,600 to 3,800 pounds each, threaded with 1,600 feet of inch or inch and one-half steel cables which, in turn, are securely lashed to the retard itself, a barrier of trees tied to- gether with the butts pointing upstream and the branches down. Fhese barriers, or re- tards, are placed in series at proper intervals, from three or four to twenty- five or thirty being used at the same locality, de- pending upon conditions. The first one, that is, the one farthest up- stream, may extend fifty Photo by U. 8S. Air Service

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POPULAR MECHANICS 453 fb, ~~ j Ds \ E * vm ce ae : Bea * a gp od = % ie Hose Connections for Forcing Water through Pile; Drawing to Show Water Ducts in Pile; in Circle, Edward Bignell, the Inventor, Is Standing on Top of Pile, and, Below, Draw- ing That Explains the Secret of Retard’s Effectiveness; Note How Far the Pile Is Sunk below the Possible Level of the River’s Scour; Retard So Anchored and Tied to Ca- bles Cannot Wash Away WATER SURFACE ; — ee §6feet from the bank, the next 100 feet, the next 150 feet, and so on, the bank ends always being built highest, —— with the rest of the barrier = sloping off as it projects into the stream. The trees that i, rave form the retard are lashed ‘ ot re" y Pe) together in big raftlike units, each from ten to thirty feet high, and are anchored to

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454 POPULAR the pile with steel cables. The pile is set 150 feet or so above the spot where the retard is to rest. The barrier is in no sense a dam. It is essentially a brake on the river’s speed. Fifty per cent of the retard’s upstream face consists of open- ings between the logs. The water flows in, but, detained by the sievelike obstruc- tion, its speed is slackened and then, due to the natural law of gravity, a lot of the river’s burden of silt falls to the bottom. More accumulates. Gradually, just below the retard, a fill develops. The river is ac- tually making land instead of destroying it, and at the same time, the bank that was threatened with complete destruction is being fortified with an earth barrier that will stand for all time. Besides its permanence, the Bignell pile has several other advantages, all of which help to simplify the big problem of river control. Under ordinary conditions, it can be sunk to a depth of fifty feet or more in less than ten minutes. It is not shat- tered as sometimes occurs when driving wooden piles, and the equipment needed is simple—an A-frame derrick to hoist it in position and a pump with suitable con- MECHANICS nections to force water at a pressure of 150 to 250 pounds to the square inch through the hole in the center and out of the side openings. With this effective concrete needle, ragged river banks all over the country are being sewed up permanently and at a great saving over previous methods. This simple unit, born of quicksand and an en- gineer’s inspiration, has cast an entirely new light on the preblem of flood con- trol and the construction of inland water- ways. The situation today, as regards flood regulation and inland waterways, is essentially this: A valuable new tool has been found for the work, a huge organiza- tion is equipped to use this tool, the va- rious agencies that have been working more or less at crosspurposes are united as never before under a big, comprehen- sive plan, outlined by the United States corps of engineers, and finally, congress has passed two generous appropriations to help put the projects well on the road to realization. Briefly, the essential problem to be solved before floods can be controlled or inland waterways become a reality, is to Revetment of Woven Willows Ready for Rock Covering; Protections Such as This Are Spread along Areas Where River Is Weakening Its Own Banks and Those of Levees

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yf of - POPULAR MECHANICS 455 Laying a Timber Mattress from a Barge to Strengthen a Bank and Guard It from the River’s Force; Concrete Mats Have Been Used with Good Effect for This Purpose squeeze the river into a fixed channel and hold it there. A big task—the biggest of its kind ever attempted in human history —but, engineers declare, a relatively sim- ple one after all. Once the streams have been directed into this channel and their speed accelerated, they will automatically keep the silt from piling in the passage and will cease their disastrous wanderings. Floods are bound to happen. But engi- neers hope to keep them under control also. The disaster in 1927 when the levees broke in 253 places, drowning 240 persons and flooding 23,000 square miles of pro- ductive land and cities, was directly due, of course, to the big, swollen tributaries of the Mississippi, all pouring their indi- vidual overflow into the main channel at approximately the same time. But indi- rectly, the terrible state of affairs was the penalty paid for years of compromising with the river instead of taking it in a firm hand and making it stay where it be- longed. Such a course was impossible, because the means were not available to accomplish such an end. Levees, 1,800 miles of them, costing more than $238,- 000,000 have, up to now, been man’s best answer to the flood question. They are still to be of aid, but an attack is now to be made in a big way, at the heart of the trouble, the lack of a fixed river channel. To help in this, congress passed the Jones- Reid bill, carrying an appropriation of $325,000,000 for an extensive program of river-control work. The other important measure, the Deneen-Denison bill, pro- vides $10,000,000 for the further develop- ment of the federal barge lines. The big program of river control as outlined by the United States corps of en- gineers and now going forward at various points, involves six main attacks: First, the construction of floodways from Cairo to New Madrid, from the Arkansas river through the Tensas basin in the Red river and from the Red river, through the Atchafalaya basin, to the Gulf of Mexico to relieve the main channel of waters it cannot carry; second, a controlled spill- way to hold the levels down to a safe stage at and near New Orleans; third, local setting back of the levees in the Mississippi river at “bottle necks”; fourth, greater protection and strengthening of levees; fifth, revetment of caving banks; sixth, improved channels for river traffic, not less than 300 feet wide and from six to nine feet deep, to be obtained by dredging and by contracting the rivers at strategic points so that they will keep their own channels clear.

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456 PILLAR OF FIRE MARKS FIRST AUSTRALIAN OIL WELL Flaming Gas at 550 Pounds’ Pressure from Australian Well over 3,000 Feet Deep The quest for oil, and gas in Australia, which has been prosecuted since 1907, was successful when an American firm of oil drillers, from California, struck both oil and gas at a depth of 3,078 feet. The gas, which became ignited, had a pressure oi 550 pounds at the start, and the oil flow which followed was remarkably clear. Owing to the scarcity of firewood in some parts of Australia, gas and oil for heating and cooking purposes are coming into more general use. GAS ATTACK ROUTS RAT ARMY TO PROTECT CITY When hordes of plague-infested rats threatened to descend upon the city of Johannesburg, South Africa, authorities laid down a gas attack over a wide area on the outskirts in an effort to halt the advance. Arsenic and poison gases of various kinds were pumped into holes on POPULAR MECHANICS farms, and other places where the rodents were numerous, and inspectors were sta- tioned to check the spread of the plague. AUTOMATIC SEA RADIO BEACON HAS WIDE RANGE Sweeping a radius of 200 miles and re- quiring no operator, an automatic radio beacon installed at Orfordness on the coast of the North sea, is regarded as an improvement over other devices of this kind. Listeners on ships or airplanes, need only a stop watch and a radio re- ceiver, and the apparatus is said to be free from night errors and interruptions which interfere with many radio light- houses. A revolving loop rotates me- chanically and sends out signals on a wavelength of 1,040 meters. The receiver registers the maximum effect when the loop points directly at it and a minimum report when the loop is at right angles. Rotation is at a known rate of speed and from a known bearing. By listening to the signal changes and noting the time required, for the signal to reach its max- imum or minimum, the receiving operator can calculate his own bearings. GUIDE FOR DRAWING LETTERS MAKES FIFTY STYLES Aluminum guides for quickly drawing letters, numerals and other characters are made in one piece and each makes more than fifty different styles and sizes. Thev are especially useful to sign painters and decorators, are helpful in teaching chil- dren and require but little skill. Using the Lettering Guide Which Makes Fifty Styles and Sizes and Requires Little Skill

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wn to X- or tyles POPULAR HARMLESS LUMINOUS PAINT TO LIGHT HOMES Within the next few years, the in- teriors of homes may be illuminated at night without the aid of electricity, in the opinion of Prof. J. H. Mathews of the University of Wisconsin. A new kind of luminous paint, non-poisonous and capable of being made in colors, dull in the daytime and brilliant at night, is being devel- oped, although the chem- ical process by which light is stored up in the paint in the day and re- leased at night is not fully understood. Hallways of a home could be a light brown in the daytime and a brilliant green at night; the bathroom, a white by day and violet at night. The paint furnishes suf- ficient light to make pos- sible passage through the rooms without electric light, but, for the present at least, there is not suf- ficient illumination from it for reading. The sub- MECHANICS 457 stance is not injurious, Mink in Special Cage, the Watering Can, and a View of the Three Com- since it does not contain radioactive materials. Its use already has been applied to the stage, where costumes have been treated with it to give novel effects when the lights are turned off. HAND DECORATOR FOR METAL REQUIRES LITTLE SKILL Spotting or decorating metal is done many times faster and more uniformly with the aid of a hand tool which unskilled persons can op- erate with good | results. It is sim- ply pushed across the work, a small wheel serving to keep the tool on the track of the guide which is de- signed to give a rocking action to the blade. This produces crescent-shaped designs on the metal. partments with Punched-Steel Lid SHIP MINK IN SPECIAL CRATES TO AID FUR INDUSTRY Raising wild animals for their fur has become an important industry and re- quired the development of special ship- ping crates to care for the animals on journeys between breeding farms and points where they are tended until the fur is ready for market. A _ three-compart- ment crate has been devised especially for mink, one of the shyest of all animals raised, and one that has suffered the most on railroad journeys. This box is covered with a punched metal screen instead of wire, a special type of water- ing can that prevents spilling has been provided, and a false bottom simplifies cleaning the cage. One of the compart- ments is a “nest box” and is well ventilated so that the animal cannot cut off the air by stuffing the openings with bedding as sometimes occurred with ordinary crates.

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458 POPULAR MECHANICS MUSCULAR MOVEMENTS PRODUCE ELECTRICITY TESTS INDICATE Interesting tests that seem to indicate still further the close re- lationship between life and elec- tricity have been conducted re- cently in Germany. By using am- plifiers and other apparatus, a record was made of the electricity developed on the skin or: imme- diately below its surface. The person used for the tests was placed in a large metallic cage and careful checks were made to determine that the electricity came from the subject’s muscular movements and not from any other source. A striking record was obtained, indicating fluctua- tions in the electric forte during the muscular efforts, according to reports. A rise to a peak was found to occur by degrees in sev- Giving Colt Its Daily Treatment of Ultraviolet Rays to Insure’ Health and Proper Growth LIGHT RAYS FOR RACE HORSES WARD OFF DISEASE Thoroughbreds in a racing stable near Chicago receive ultraviolet-ray treatments every day, as it is believed that they need artificial sunlight when the natural sup- ply is unavailable, as much as do human beings. A short exposure to the special lamp is said to give an effect equivalent to that from a whole day in the sun. The treatment is of.special benefit in winter when the animals are confined indoors. COMBINED CASE AND LIGHTER SAVES POCKET ROOM Cigaret case and lighter are combined in one attractive article, saving the bother of two units with the demand for extra space. The case holds ten cigarets and the lighter is said to be a dependable type, and is not likely to get out of order. eral rapid stages, and, in the event. of a continuous effort, the elec- tric response declined somewhat, before the person was fatigued, but this was be- lieved due to the fact that the skin beeame moist with perspiration. While the test showed a connection between electricity and muscular work, the origin and other factors of the electric currents still re- main more or less of a riddle. SIGNAL ON AUTOMOBILE CHOKE PREVENTS MOTOR ILLS To remind mo- torists to regulate the choke prop- erly, a warning signal has been devised. It con- sists of a small light that glows when the knob is out but is extinguished when the choke is in. This eliminates the likelihood of forgetting to push the choke in, an oversight that often results in fouled spark plugs, damaged bearings and other troubles caused by an excessive use of gas and oil. Back of the lens on the knob light is a semitransparent disk on which a monogram or other leg- end may be printed.

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POPULAR MECHANICS PIPE STEMS MADE FROM COAL BY DISTILLING PROCESS Materials for the manufacture of pipe stems, umbrella handles, cue balls and many other articles will be prepared from coal products derived by a special distill- ing process, according to a recent an- nouncement. Synthetic furniture is pre- dicted as a result of the development in this field. The method is new United States and differs from other proc- esses chiefly in the quantity of by-prod- ucts that are obtained. It produces about two and one-half times as much tars from which synthetic resins are made. From these latter substances, chemists have made a wide variety of articles, including brilliantly colored pens and pencils, bath- room tiling, tops and stoppers for bottles, radio parts and automobile accessories. Gasoline made by the new method of coal distillation is said to produce less “knock” than that obtained by other processes. MODEL OF ROCKET AIRPLANE CONTROLLED BY RADIO Designed to be propelled by rockets, a monoplane in model form has been tested by a western inventor. In demonstrating the craft, he used a radio-control outfit, manipulated by a keyboard. The com- pleted ship is expected to contain eighty- six rocket “barrels” to furnish power. Inventor Demonstrating Radio Control for His Model Airplane to Be Propelled on the Rocket Principle to the. 459 Section of the Self-Filling Shoppers’ Shelves: Cans Re- moved at Bottom Are Replaced from To> SELF-FEEDING STORE SHELVES LATEST AID TO SHOPPER Adapted especially for canned goods, a special shelf arrangement has been intro- duced for the convenience of the shopper. It is filled at the top and, as cans are pulled out at the bottom, others slip into their place. This eliminates difficult reaching and keeps cans from being pulled out on the floor. Another innovation, used in con- ‘nection with the shelves, is a basket with rollers which the customer pushes along on a counter at the base of the shelves, instead of carrying. @ Popular Mechanics Magazine does not publish the name of the maker or seller of any device described in its pages. but this information is kept on file and will be fur- nished free upon application to our Bu- reau of Information.

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POPULAR MECHANICS © Daily Press Radio Lighthouse at Start Point, England; Beams Are Transmitted through Hole in Turret to Guide Ships LIGHTHOUSE SENDS RADIO BEAM TO GUIDE SHIPS IN FOG Wireless beams are transmitted from a hole in a turret of a radio lighthouse at Start Point, Eng., off the steamship route from Plymouth to London. of the apparatus is about 100 nautical miles under normal conditions, and the turret helps to over- come some of the difficulties that otherwise would be encountered in sending from a sta- tion built on rocks. The code is sent automatically, at in- The range tervals or continuously, depending upon the weather. All running machinery is duplicated in case of a breakdown, and if a tube should fail, an alarm is sounded, NEW CABLE SENDS EIGHT MESSAGES AT ONE TIME Eight messages are dis- patched simultaneously over the latest Atlantic cable from Bay Roberts, Newfoundland, to the Azores. Four are sent in each direction at one time. What happens is that the time on the wire is divided equally be- tween four different send- ing machines. For in- stance, there are four messages, the first word of each in order being, cat, rat, boy and dog. The first letter to go on the cable would be “c,” the next “r,” the next “b” and the next “d.” The second letters of each word would follow, and so on, until the messages were completed. At.the re- ceiving end, a device separates the various messages and diverts each to an instru- ment that registers the message properly. MOVING MAP FOR AUTO DRIVER PREVENTS GETTING LOST Moving Map at Right Unrolls as Auto Proceeds, and Pointer Tells Exact Location of the Car Motorists travel- ing over strange roads or driving at night, are guided by a moving chart installed under the dash. It is keyed to synchronize with the speed of the car, unrolling as the ve- hicle progresses. The position at all times is indicated

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POPULAR MECHANICS by a pointer, so that, if landmarks do not agree with the moving map, the driver will quickly know that he is off the way. RADIO TRAVELS BEYOND MOON ECHO TESTS SHOW Radio waves travel far beyond the moon, recent tests have shown, so that commun- ication with the satellite would not be im- possible were someone there to receive’ the signals. Dr. Carl Stormer, a Norwe- gian scholar, experimenting with a thirty- one-meter wavelength, observed echoes from signals back as much as fifteen sec- onds after the original impulse had been transmitted. Since radio waves travel at the rate of about 186,000 miles a second, the echo tests indicated that they had gone more than a million miles out and back again, much farther than the distance of the moon from the earth. Doctor Stormer believes that the echoes are caused by a laver of electrons which come from out- side the earth, LANDING LIGHTS SET IN GROUND SHOW WIND’S DIRECTION Airplane landing-field lights, installed in protected depressions where they can- not be damaged by the ships, have ap- peared at an eastern airport. They are Landing-Field Lights in Small Wells Are Protected against Breakage and Serve as Wind Indicator so set that lines of them may be turned on to indicate the direction of the wind as well as to show the runways. 461 Turning the Dial That Causes Buzzer to Sound When Answer to Question Is Reached BUZZER TO ANSWER QUESTIONS LATEST QUIZ GAME Resembling a small radio cabinet and loud speaker, a buzzer set that answers a wide variety of questions has been intro- duced for the instruction and entertain- ment of. children and others. A card, bearing the questions and answers, is slipped over the two knobs in front of the box. The one at the left is set opposite the question selected. The other is turned until the buzzer, concealed in the loud speaker, sounds. The proper answer will be found opposite the arrow on the “tun- ing dial.” A small electric battery inside the cabinet provides current for the buz- zer. The set of cards furnished gives a large number of interesting and amusing questions with answers, and children en- joy some of the thrills of operating a real radio set while learning facts about science, history and many other topics. HIDDEN SPRINKLERS IN LAWN KEEP GRASS GREEN Ninety acres of lawn in New York's Central park are to be kept fresh and green by a hidden irrigation system re- cently tested. Pipes and disks that give an effective spray, are concealed in the grass, and water may be turned on for the whole area or for just a small part that needs a-special amount. The spray disks have gravity caps that fall back when the water is turned off, to prevent the nozzles from becoming clogged.

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SO NAGASE EA ENGI BE Ea Na Tabs a Se TS EE IO IAG AAT ET ereepewerv ARE ee — Below Is a Bag with Small Outer Side Pocket for Loose Change, to Save Opening and Fumbling through the Main Compartments; It Is Just Large Enough to Hold a Small Number of Coins At Right Is a Washing Machine Operated by a Small Gasoline Engine Instead of an Elec- tric Motor; Its Wood and Steel Construction Reduce Vibration to a Minimum So That It Is Said to Be Nearly as Smooth-Running as the Usual Kind Pie and Cake Pans with Han- dies Are More Easily Placed in Oven and Removed without Burn- ing the Fingers or Dropping; They Are Furnished in Several Different Sizes; at Left, Dust and Moisture-Proof Envelopes for Garments Fold Flat for Conven- ience in Traveling

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This Oil Heater Has a Patented Floor Tray Attached, to Prevent Its Tipping Over and to Protect the Floors Food Flavors Are Retained When Articles Are Wrapped in Vegetable Parchment While Cooking; at Right, a Special Spray Hose for Flushing the Sink Drain Serviceable Hair Drier Is Con- nected to the Vacuum Cleaner, and, Below, a Specially Shaped Frying Fork Which Simplifies Turning Bacon and Other Foods without Dropping J 463

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PERIER oa A ND EBS NE AIF TS IN ae pe LAR RES he ARE eT TN Cathar Rehem en. SS TS 464 POPULAR MECHANICS wickets placed before the disk, the object being to get the ball through the wickets and into the disk in as few strokes as pos- sible. LUMBER WASTE IS REDUCED BY THINNER SAWS By using thinner sews, lumbermen could save some $60,000,000 annually in this country, engineers have estimated. Reduc- ing the thickness of the cut as little as one-six- teenth of an inch would effect this economy, tlie 7 experts declare. They Playing the Quoit Poker Game, and a Close View of the Rug, to Show the Design and Arrangement for Golf RUG SERVES AS GAME BOARD FOR GOLF OR CARDS Double service is afforded from a novel rug now on the market. Besides its nor- mal function as a floor covering, it serves - as a field for two interesting games, a form of poker and indoor golf. The pattern consists of an arrangement of the sym- bols on playing cards. To play poker, a pitching quoit is used, the object being to throw the quoit upon the joker, the cen- tral figure in the design, and so fill out the hand to the best advantage. Five quoits are used in this game, the landing place of each being determined by a hole in its center. If a line between two or more “cards” shows through the hole, the higher card is scored. In the golf game, a putting disk is placed on the joker and a regulation golf ball and putter are used. Here, the main object is to land the ball in the disk or joker and so fill out the hand. THe figures on which the ball stops are also used as in the poker game, to de- termine the hand. Both games require considerable skill, help steady the eyes and nerves, and the putting practice improves the real game on the links. The rug is made of durable material and is hand- somely colored... A pleasing variation of the putting game is played with the aid of point out that with the present saws not . less than $30,000,000 is wasted yearly in preparing the saw logs and about $33,000,000 in converting the logs into boards. This is the annual bill for saw- dust, only a small part of which is sal- vaged for useful purposes. Efficient standardization of blades would result in the saving, a report made to the American Society of Mechanical Engineers stated, and the economy is recommended in view of the none too abundant supplies of timber. LIFTER FOR MILK-BOTTLE CAPS PREVENTS WASTE Paper caps are removed from milk bottles without _ spilling the contents with the aid of a sim- ple lever device recently intro- duced. It fits around the neck of the bottle, the cap is attached to a sharp prong, and is then removed simply by prying down on the lever. The device is quickly adjusted and does not mutilate the cap, which can be used repeatedly. “N lo tai po ica de of Fi on rac rel pre re it ser Gr we ere m an ST pat we pet Sta Side Con ter 1

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TS aus eS * POPULAR MECHANICS 465 “NORSE” RUINS LAID TO ESKIMOS MUSEUM EXPLORER SAYS Norsemen may have landed in America long before Columbus did, but, so far, no tangible evidence has been found to sup- port this belief, Dr. William Duncan Strong, assistant curator of North Amer- ican ethnology and archzology, recently declared after research into the question of alleged Norse ruins by the Rawson- MacMillan subarctic expedition of the Field Museum of Natural History. Ruins on Sculpin island, near Nain on the Lab- rador coast, which had been regarded as relics of an ancient Norse settlement, proved, upon examination, to be only the remnants of an old Eskimo whaling camp, it was found, The stonework did not re- semble the authenticated Norse ruins in Greenland, and no Norse implements were found, whereas the material discov- ered closely resembled that which is com- monly found in Eskimo burial grounds and camp sites in other regions. STOVES AND BLANKETS IN CAFE DRAW WINTER PATRONS Coke stoves and blankets are provided patrons of a German cafe when the weather is cold. The innovation has al- ready proved popular in France, whére permanent heating facilities are not in- stalled and outdoor dining is common. Sidewalk Dining Is Now Comfortable Even in Wir- ter with the Aid of Stoves and Blankets Gas Mask for Asthma Victims Affords Treatments While the Wearer Is at Work GAS MASK FOR ASTHMA VICTIM WORN WHILE AT WORK German engineers have devised a light- weight gas mask that is said to be effective in the treatment of asthma. It can be worn about the house or other place while at work, has wide glasses to permit unob- structed vision and is quickly adjusted or taken off. SEEDS LIVE FORTY YEARS IN DEEP SOIL That the seeds of weeds and other plants will grow even though they have been buried forty years, was shown recently by Prof. O. A. Stevens, of i the North Dakota agri- = cultural college. Nearly seventy per cent of the seeds of pigweed germi- nated after this long burial, and about the same results were ob- tained with the evening primrose Seeds of some varieties of grass did not grow after five years, The tests showed that there is comparatively little to fear from seeds of weeds buried deeply. @Of the world’s volca- noes sixty-five are active.

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ee a ae a nn a ee ae 466 POPULAR TALL BUILDING LIKE OBELISK TO GUIDE AVIATORS The Foshay Tower in Minneapolis; Unique Office Structure Modeled after the Washington Monument The Washington monument is said to have been the inspiration for an obelisk- shaped business building now nearing com- pletion in- Minneapolis. There are thirty- two stories reaching 450 feet in height, with five stories underground. Two of these will be used as a garage with a storage capacity of 250 cars. At the tip of the building is a wide observation balcony. A radio broadcasting station and an aerial beacon will be installed there. MAGIC METAL RESISTS WEAR AND HARDENS IRON Aelium, a strange mineral discovered about three years ago, possesses many re- markable qualities that fit it for special service, an expert reports. It fuses lead and copper with any other metal, he de- clares. It reduces the flowing temperature of molten metals, making possible die- casting and the molding of metals of high melting point into intricate patterns. It increases the tensile strength of iron, steel and other metals, and also increases the capacity of copper and aluminum to carry electric current. One of its most peculiar properties is that, under certain MECHANICS conditions, it provides a natural film of oil so that other lubrication is not neces- sary. In fact, Thomas J. Clark, a Utah stockman who discovered it, thought at first that it was an oil shale and was ex- perimenting with it in the belief that ir would yield oil. Harry Miller, auto racer, made a shop test with an aelium bearing, running it for four hours at 5,000 revolu- tions per minute without oil. It was then clamped down and run for twenty-eight hours without heating or shaft injury, according to reports. A bearing in an automobile clutch was run for twenty- four hours under a pressure of 1,500 pounds to the square inch without lubri- cation and showed no signs of wear. Ac- cording to engineers, an automobile with bearings of this material would probably need but ten per cent of the oil required on the usual car and burned-out bearings would be practically eliminated. GLARE SCREEN ON WINDSHIELD PROMOTES SAFE DRIVING To protect the eyes from.the glare of approaching headlights, an adjustabie shade of transparent material is attached to the windshield. It is also effective against the rays of the sun and is said to promote visibility in fogs. It may be used effectively for shades on the headlights of the same car, to lessen the glare in the eyes of other drivers, Glare Screen in Place on Windshield, Showing How It Protects the Eyes from Approaching Headlights

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y It All Three Balls Can Be Pocketed at One Shot by Using a Pair of Cues to Transmit the Blow to the Pair Placed in Front of the End Pockets, the Cue Ball Going to the Side ERHAPS you can neither shoot a_ glove, as shown. It is really very funny. good game of “Kelly,” nor run up an One of the old stand-bys in magic is the imposing string at three-cushion billiards, sudden disappearance of some object; at but it is well within the ability of any the billiard table, the magician does it with person to present a few diverting tricks a billiard ball. Like this: He takes a ball on the green table. Such as this: The performer places a ball in the mouths of the two end pockets, and sets his cue ball at the opposite end of the table. The trick is to pocket all three balls in one shot. A tall order? Not at all! The performer merely places two cues in the position shown and then shoots his cue ball so that it strikes the butt end of the nearest cue. That’s all! A trial will show you that the seemingly im- possible is quite easy. Did you ever go rabbit hunting? And laugh a little, cruel as it may seem, at the funny way a shot rabbit flops over when hit? You can demonstrate the.same quaint toppling-over effect on the billiard table by shooting a ball into the open end of a heavy, fur-lined The Imitation of a Shot Rabbit, Done by Shooting the Cue Ball into a Fur-Lined Glove 467

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ar SAR RR sm Uh A DR IE Le ARIE KA i hil POPULAR MECHANICS Rolling Two Balls across the Table, One on Top of the Other, Looks Like a Difficult Feat; the Trick Is Accomplished by Using Two Cues to Keep the Top Ball in Position; the Start Is Shown at the Right, and, Above, the Balls Have Al- most Reached Their Desti- nation, Propelled by the Force Exerted by Pressing Down on the Pair of Cues The Vanishing Billiard Ball; It Looks Hard, but the Right Hand Deceives the Eye While the Left Catches the Ball be- hind the Back and Pockets It \ pic er: po lea the ful T

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Me POPULAR MECHANICS 469 in his right hand, and swings his hand up three times, as illustrated, On the third time, the ball oblig- ingly melts away into thin air. Of course, the ball didn’t really melt. It was merely caught be- hind the back on the third swing, and the left hand slyly slipped it into the side pocket. Try it! And don’t worry about anyone gluing their eyes on your left hand; the misdirection is too powerful. There is a trick, and a good one, too, in which one billard ball is balanced on top of another. But, here’s a better one: The balls are not only balanced but they run the length of the table in their two-high majesty. You do it with two cues. The picture shows the start of the op- eration, the balls being held in place until the cues are properly adjusted. Notice that the cues point upward. Now, if you re- lease the balls and press down on the butt ends of the cues, you will demonstrate what appears to be quite In the next effect, the performer takes a difficult trick—the balls running the a tumbler, and wagers anyone he can full length of the cues in this position, pocket it in the side pocket on the very first trial, the tumbler to be rolled from the side of the table, as shown. You’re on! But, doggone it, he did it— on the first trial, too, the glass describing an arc and ending in the side pocket. Of Two Tumbler Tricks; Above, Rolling the Glass into the Pocket, and Below, Pocketing the Dime in the Tumbler by Jarring the Inverted Glass Forward over the Coin

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RII ANGLO BR ACR INN Ny RT AL ANE OB db tn han 470 POPULAR MECHANICS course, no one is sup- posed to be wise to the preparation, which con- sists in placing the tum- bler in the pocket, and then rolling it up the ta- ble and marking the ex- act spot from which the glass must be started in order to reach the pocket in its curve. Another excellent trick with the tumbler also is illustrated. The tumbler is placed on the ledge of the table, as shown, and a dime is placed on the cushion in front of it. The trick is to pocket the dime in the tumbler. This can be easily done by shooting a ball from the oppo- site side of the table. The shot must not be too hard, and the ball must strike in a direct line with the dime and tumbler. Place two cues together, and set a ball on them at the tip end, as shown. The problem is to make the ball run off the butt end of the cues. It’s quite a stunt, even when you’re in on the “how.” The how consists in separating the cues slightly, until the ball gains mo- mentum, and then closing them sharply so that the ball jumps suddenly forward and rolls off the Making a Ball Run Uphill Looks More Difficult Than It Is; the Ball Is Started by Separating the Butts of the Cues and Squeezing the Tips Together behind the Ivory; When It Gets under Way, the Ends in the Hands Are Suddenly Squeezed Together and the Ball Jumps from Be- tween Them ard Rolls up and off the Ends; If the Trick Is Performed Lengthwise of the Table, It: Will Be Found Much Easier to Do C ere hig ser mal tan! ma phe ing sun cub and poi

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POPULAR butt ends. By performing the feat length- wise of the table, and thereby eliminat- ing the extra height caused by the cushion, the problem is greatly simplified A trick known to our grandfathers, and one which appears to be entirely forgot- ten by the younger generation, is “The Pressed Ball.” The problem is to press a finger down on a ball and make it go the full length of the table. The unini- tiated person doing this will send the ball away with too much backspin, and it will only go half the distance, but if you moisten your finger slightly before at- tempting the feat, it rolls merrily along to the other cushion. SPRAY RUN FROM LIGHT SOCKET DEVELOPS EVEN PRESSURE For applying lacquers, paints, disinfect- ants and other liquids, an electric spray gun is operated with current from the house-lighting circuit. The com- pressor unit is said to develop an even pressure at all times, an essential on many jobs, and it may be carried over the shoulder with a strap or placed on the floor or bench. Only the paint container and the gun itself are held in the hand, so that vibration is reduced and there is less weight to support. The nozzle controls the spray’s density. GAS TANK AS AIRPLANE GUIDE HAS FIFTY-THREE LAMPS On top of a 418-foot gas tank, recently erected in Chicago, is a tower seventy feet high with several high-powered lights that serve as an airplane beacon, Other lamps, making a total of fifty-three for the entire tank, are provided, They are lighted auto- matically by an astronomical clock, and a photo-electric device turns them on dur- ing the day if fogs or smoke obscure the sun, The tank has a capacity of 20,000,000 cubic feet. It contains 5,500 tons of steel and nearly 2,000,000 rivets. A sign on top points to the landing field. MECHANICS 471 What the Well-Dressed Dog Is Wearing; Kid Boots for All Four Feet and a Handsome Coat SUIT AND BOOTS FOR PET DOGS HELP GUARD HEALTH Pig-skin boots for all four feet and a slip-on sweater of special pattern have been devised for pet dogs. They keep the animal warm and comfortable. SILENT WELDING ON HOSPITAL PROTECTS PATIENTS Inmates of a West Virginia hospital were undisturbed although a steel addition to the structure was built recently. Elec- tric-arc welding instead of riveting was the process used, so that practically all noise was eliminated. At one time, the welding was in progress only fifteen feet from an operating table, but the surgeons went on without annoyance, SWITCH WITH PILOT LIGHT ALSO HAS OUTLET Switch tap, pilot light and electric out- let are combined in a unit adapted to the operation of va- rious appliances, radio, and re- mote-control lights. The cur- rent is controlled by the finger, and the jewel is lighted when it is on.

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OR A Re ee — —— ee ey ae ee 1? Shopping lips for see Above, New Device, for Regulating Line Voltage for A. C. Sets or A and B-Eliminators, Automatically Reduces the Line Voltage If Too High and In- creases It If Too Low Below, a New and Decidedly Different Type of Console Radio Cabinet Equipped with Glasses, De- canters and Silver Service; the Cellarette Com- partment Is Lined with White Lacquer and the Drop Leaf Is White Enamel on Metal Left, Dry Rectifier Unit of Plug-In Type, Said to Have Extra-Long Life, Replaces Full-Wave Rectifier Tubes in B-Eliminators; Below, Handy Unit Combines Light-Socket An- tenna and Supply Outlets for Dy- namic Speaker, Eliminators or A. C. Receiving Sets Below, New Push-Pull Amplifier of Excellent Design Can Be Used Equally Well with Radio Receiver or Phonograph Pick-Up; Small Switch Provides Quick Change-Over

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Left, Unit of Compact Design Provides Effi- cient Antenna and Ground Connections as Well as a Means of Controlling Line Volt- age; Two Outlets Are Also Furnished for Set and Dynamic Speaker; the Unit Is Well Fused to Prevent Burn-Outs in the Receiver; Right, a Compact Short-Wave Adapter, Now Available for Use with Any Re- ceiver, Covers All Short- Wave Bands without Changing Set Wiring Below, Clock Installed in New A. C. Receiver Operates from_ Light-Socket Current and Automatically Winds Itself Once a Minute; It Keeps Accurate Time Right, Complete Television Re- ceiver Now Available Is Equipped with Sliding Visor and Combina- tion Scanning Disk for Either 24 36 or 48-Line Pictures Above, New A-Power Unit of Popular Make Has Improved Filter Sys- tem Employing Three 1,500 Mfd. Condensers and Improved Choke Coils; It Is Claimed to Be without the Slightest Trace of Hum 473

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474 POPULAR MECHANICS to the set. The lamp is useful in checking a.c.-operated radio de- vices, where it is necessary to turn them off with separate switches, and may be connected in the line as a warning or pilot lamp for this purpose. Handy Kink for Set Builders The use of ordinary quilt-frame clamps, for holding paper tem- plates, small wires to be carefully soldered, and other emergencies, where the operator could well use three hands, has solved many dif- Insert Photo Shows Clamp Fastened to Building Near Window for Lead-In Clamp for Aerial and Lead-In The clamp shown in the illustration re- places unsightly sticks and poles, requires no nailing or bracing and is easily attached and removed. The only tool necessary for its installation is a screwdriver, and the various applications shown in the sketches illustrate its adaptability to all sorts of situations. The threaded shaft is of cadmium-plated rust-proof steel, and the clamp itself is of heavy channel iron similarly plated. Separate lead-in insu- lators are also available at small cost. These are mounted’ on short rods which screw into threaded holes provided for them in the clamp. Anyone who has erected antennas will appreciate the handy methods illustrated for running the aerial and lead-in wire around corners, etc. Attractive Lamp Forms Antenna A pleasing combination of an efficient antenna and a lamp is shown in the illus- tration. The an- tenna is of the light-socket type, and the outfit is provided with a length of lamp- cord, for connect- ing to the house- lighting supply, as well as a binding post, for the an- tenna connection ficult situations for the writer. These clamps are cheap and should be of the 2-in. variety. Corrugate the jaws by making a few shal- low cuts with a hacksaw, to prevent shift- ing of paper templates. Clamps of this type do not mar expensive panels: and may be wedged with small blocks of wood. —E. R. McCourbrey, Pawhuska, Okla. Compact A. C. Converter The compact unit shown in the illustra- tion converts 110-volt 50 to 60-cycle alter- nating current to 6-volt d.c., and when used with a B-eliminator, combines the convenience of electrical operation with the desirable characteris- tics of stand- ard d.c. tubes. No changes in tubes or set , wiring are required, and the device takes up less room than a 6-volt storage battery. Heat in Voltage Regulator The ordinary regulator used to protect a.c. tubes from excessive line voltage, when plugged into the electric outlet, will often become warm. This is not an indica- tion that the unit is defective; it is a con- dition to be expected because such devices will dissipate heat, and simply indicates that the unit is doing its work normally. tw St

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kes Try. A SCREEN-GRID SW ADAPTER —~for Na \ } HE LAST few months have witnessed a renewal of interest in short waves, due to the overcrowded long-wave chan- nels, coupled with the fact that televi- sion is a field which brings out the advan- tages of short-wave transmission and re- ception. A good television transmitter requires a band from 40 to 80 kilocy- cles wide, which represents from four to eight long-wave broadcasting channels. These cannot be afforded in the broadcast band, so the newer transmitters are work- ing between 30 and 80 meters. The short waves are valuable, because “side-band cutting,” with consequent loss of picture definition, is less severe. The width of the side bands is determined by the num- ber of “dots” sent for each picture and the number of complete pictures per second. The definition of the picture will depend on the number of dots to each picture and the continuity or smoothness of motion on the number of complete pictures sent every second. High-quality transmitters have side bands 40 or more kilocycles wide, and future circuits espe- cially designed for television reception must eventually tune uniformly to this wide frequency band. The best method of doing this will be in the use of r.f. circuits of the band-se- lector type, with regeneration used spar- ingly or not at all. However, the widest interest in short Waves at the present time is confined to the excellent programs transmitted by twenty or more stations in the United States and a much larger group employ- YOUR ing code. The simple adapter described in this article is suitable for all three types of reception, but is not especially designed for television, as a compromise must be made in this case. Byrd’s expedition to the south pole; the flight of the “Southern Cross” to Aus- tralia, and similar instances, where short waves have enabled a transmission link with civilization, show the value of these short wavelengths. Great progress has been made with short-wave apparatus. Further advance- ment in the ultra-short wave bands, below 5 meters, is limited, since the lower end of the ultra-short band merges with the upper end of the heat-wave band, although electrical oscillations have been produced which are near the border line. Short- wave transmitters costing only some thou- sand dollars have in many instances re- placed long-wave transmitters costing hundreds of thousands of dollars, They are not only less expensive and much more compact, but they provide reliable communication over enormous distances and during daylight hours when consist- ent operation on long waves is ordinarily difficult. The trend of short-wave receiver de- sign follows closely that of broadcast re- ceivers, and the development of satisfac- tory short-wave receivers and adapters has been greatly advanced by the new screen-grid tubes, which were used ex- perimentally in short-wave transatlantic reception for over a year before they ap- peared on the market. 475

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476 POPULAR MECHANICS ing but the audio ampli- fier in the broadcast set is in use. A schematic diagram for a two-stage audio-frequency ampli- fier is given for those who The two-tube adapter described and illustrated in this article em- ploys the screen-grid tube, and greatly increases r.f. amplifica- tion without complicating the op- eration in any way. In fact, the operation is actually improved over that of the standard broad- cast receiver, because the regen- erative detector is not directly coupled to the antenna, and the ‘antenna coupling does not have to be varied to prevent “dead spots.” An adapter of this type does not re-radiate, as the screen-grid tube acts as a “blocking tube” and prevents direct ra- diation into the antenna. Some years ago, when oscillating receivers became numer- ous, there was a crusade against them. The necessity for a similar crusade can be eliminated by the use of circuits employ- ing the screen-grid tube. The model illustrated in this article was built and tested in Popular Mechanics ra- dio laboratory and brought in eastern short-wave television and voice broad- casts with loud-speaker volume during the daylight hours. Reception at night in- cluded short-wave stations in all parts of the United States at good loud-speaker volume. These tests were made with the adapter plugged into a standard broad- cast receiver. The detector tube in the re- ceiver is transferred to the adapter, and the adapter plug is then plugged into the detector socket in the set. All tuning is done with the adapter-unit dial, as noth- wish to include the amplifier with the tuner instead of using it in combination with the standard receiver. The terminal marked “plate lead” is connected to the binding post which goes to the r.f. choke, and the B-positive terminal is connected to the 45-volt tap of the B-battery. Any high quality a.f. transformers may be used. The first jack is for the use of headphones, and the output jack for the loud speaker. The construction of the adapter unit is very simple, as shown in the simplified wiring diagram. ‘The front panel is 7 by 14 in. and the wood baseboard % by 8% by 13in. Solder every connection carefully, as perfect electrical and mechanical con- nections are absolutely necessary in short- wave adapters and receivers. See that the small setscrew on the 100-mmfd. condenser is tightened so as to give a good wiping contact for the rotor. The wiring in short-wave receivers deserves more atten- tion than is accorded it in broadcast re- ceivers. All leads should be as short and dir sho ren sho ble. be pac cul be I the tho ing ing or | 45- try the nal set. C rec alt tha nec cei’ No 301 are am twe typ abl to thr firs the cas tec! rec is t tior dyt -—

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is in n- e- id

POPULAR direct as possible, that is, bee-line wiring should be used. Wires carrying r.f. cur- rent should cross at right angles and should clear each other as much as possi- ble. A slight increase in lead length may be permitted to make this possible. Ca- pacities between the grid and plate cir- cuits are especially important and should be reduced to an absolute minimum. Batteries are recommended because of the high sensitivity of the adapter, al- though it may also be used with sets hav- ing an A and B-eliminator by disconnect- ing the detector-supply lead (positive 45 or 67) from the set and connecting a small 45-volt B-battery in its place. The B-bat- try 45-volt positive terminal should go to the receiving set and the negative termi- nal to the B-negative binding post on the set. Complete a.c.. operation of short-wave receivers and adapters has not been found altogether satisfactory, owing to the fact that the B-eliminator introduces extra- neous noises on short waves. If the re- ceiver employs a.c. tubes, four separate No. 6 dry cells, connected in series, with a 301-A or 112-A detector, MECHANICS 477 into the first-detector socket and the oscil- lator tube in the superheterodyne must be removed; the converter is then made to oscillate and is operated in this condi- tion. Where the intermediate frequency is high, above 150 kilocycles, the adapter will work better when plugged into the second detector and operated in the usual manner. The A-battery leads should be perma- nently connected to the adapter unit; if the a.f. amplifier is combined with the adapter, making a complete receiver, the A-positive leads should be connected di- rect to the A-battery positive terminal and the set side of the battery switch so that this switch turns off all tubes. Ordi- narily 112-A detector and screen-grid r.f. tubes are recommended for short-wave receivers. The 112-A is more sensitive and is a stable oscillator. The 301-A is almost as satisfactory as a detector and may be used when the effective input ca- pacity must be low; for example, when working at the minimum wavelength of the circuit. The 200-A detector tube is very sensitive but noisy. A 199 tube may

are recommended for fil-

ament supply. Where a COND. two-stage power-pack ar Saat type of amplifier is avail- J a 2meGs able, it is a simple matier f z to arrange a switch to Ew - }+ & “ro, F throw the input of the = Cont tH cOnts = t+ first transformer from we ‘ oO the detector of the broad- 3 aie cast receiver to the de- aa tector of the short-wave TAPPED receiver. If the adapter — is to be used in connec-

tion with a superhetero- dyne, it should be plugged

foe Bt 45vV. Bri35v.

VOLUME DIAL CONTROL KNOB FILAMENT SWITCH SENSITIVITY

UX-112-A — JALK 45V peer an 1-A 1-A

-¢ 4 4 4ieV. “Ar +A +B <¢ +B +c 90 V. 9V. 135 V. TWO-STAGE AUDIO AMPLIFIER FOR COMPLETE RECEIVER

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478 POPULAR MECHANICS ay ® SETSCREW DIAL KNOB VOLUM E Aidit Mm pooegd 1] Een oa TONATROL 100 MMF. —" — exes - TYPE P Pra DIAL if @ i} 20-OHM Ui we bis cap g OR 7 = = / 4-0HM —LIE« > - : 5 % RESISTOR f P : 801-A OR 112° © SCREEN on bd : 70-MMFD. PREVENTS CUITING E ‘TTERY colt | | ye 00.0 O @M' Ee“ moUNT / F P -A +A a. &.. ANT. GND! ‘SCREEN-GRID SW ADAPTER ‘ ee SS NRE * : Marcr 929 ; be used when filaments have to be dry- cell operated, but the regeneration may be poor, especially at very short wave- lengths. ' Anyone who has tuned a set of the type employing a stage of r.f. amplification and a regenerative detector will have little dif- ficulty in tuning this short-wave unit, as the principle is exactly the same, although the settings are more critical. Distant stations may be heard by gradually in- creasing the capacity of the regeneration or “sensitivity” condenser, until a hissing noise is heard and the detector just begins to oscillate. This control should be kept as near as possible to the oscillating point throughout the tuning range. When properly adjusted, touching the stator plates of the detector condenser will re- sult in a sharp click. If there is no click, readjust the sensitivity control. When the station is located, decrease the sensi- tivity slightly and readjust the tuning con- denser until the whistle is very low in pitch. Both adjustments should be made simultaneously, so that the pitch is very low at the point where the receiver stops oscillating. A slight readjustment of the tuning condenser is necessary, because the sensitivity control affects the tuning adjustment slightly. The proper setting for the 70-mmfd. grid condenser will be at nearly maximum capacity; the best gridleak value will be found by test and will be between 2 and 5 megohms. The setting of the variable grid condenser, the resistance of the gridleak and the detec- tor-plate voltage determine the sudden- ness with which the receiver goes into oscillation. It is not a good plan to let this happen abruptly, as it makes the in- strument difficult to operate at the point of maximum sensitivity. The short-wave plug-in coils come in sets of three, cover- ing the 20, 40 and 80-meter bands, and a mounting base is included in the coil set. A large blueprint of the simplified and schematic diagrams may be obtained from Popular Mechanics radio department, 200 E. Ontario St., Chicago, for 25 cents to cover cost and packing. Specify blue- print No. 142. A copy of the material list will be mailed free to any address upon request,

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the use ing ing be pest and The the tec- len- into » let » in- oint vave ver- nd a set. and from , 200 ts to blue- 1 list upon Making Short-Wave Coils By L. B. ROBBINS HE INTERESTING programs now available on the short waves have cre- ated a demand for short-wave sets and adapters, which are not expensive and are quickly assembled. Suitable short-wave coils can be purchased for from $5 to $10 . a set, but many experimenters would like to make their own if the data for their construction were available. The purpose of this article is to show the reader how to make a good set of short-wave coils of the plug-in type to be used with standard- tube sockets, suitable for covering’ the 150, 80, 40 and 20-meter bands at a mini- mum cost. The materials required consist of the following items: some stiff cardboard mailing tubes, 3 in. in diameter; a few strips of bakelite, 8 in. wide; four UX- tube bases from burned-out or discarded tubes; a small bottle of orange shellac, a \%4-kb. spool of No. 18 The tube for the 150-meter coil should be 4 in. long; for the 80-meter coil, 3% in. long, and for the 20 and 40-meter coils, 2% in. The mechanical construction is so clearly shown in the diagrams that little further comment is necessary. The coils (secondary at the left and tickler at the right) must both be wound in the same direction, the turns being spaced % in. apart, and the space between the coils should be about % in. Punch a pair of holes in the tubing at the start and finish of each coil and thread the wire through them to hold the winding. The ends of the coils are then brought down through small holes drilled in the bakelite strip, as shown. To prepare the four prong bases cut the tube base off with a hacksaw, severing the wire leads at the same time. The leads may then be removed from the prongs by enameled-copper wire, and an assortment of machine screws and nuts. As these coils are de- signed with a fixed sec- ondary and tickler, each pe ||! pair is to be wound on a single piece of tubing and their terminals connected to the four prongs of a single tube base, as shown in the sketch. wee A COMPLETED $o-eentan COIL SAW BASE __ OFF HERE ABouT ) RELEASE TUBE LEADS BY MELTING SOLDER ON TIPS OF PRONGS THROUGH PRONGS : ~ LEADS COME DOWN i. “BOLT | | ' HOLE DRILLED IN CENTER / OF BASE FOR BOLT heating the tips of the latter with a sol- dering iron. Drill out the prongs and also drill and countersink a %-in. hole in the center of each base. Each pair’ of coils will cover a range 479

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Completed 20-Meter Coil well above and below the band for which they are designed. If an adjustable pri- mary coil is to be used in the circuit em- ployed, one size only is required, and this may consist of 10 turns of No. 26 double- silk-covered wire wound on a tube 2% in. in diameter. A variable high resistance may be used across the antenna and ground posts, eliminating the primary coil. Using .00025-mfd. variable condensers in . the circuit, the following number of turns will be found about right for the various short-wave bands: for 20 meters, second- ary 3 turns, tickler 6 turns; for 40 meters, secondary 7 to 8 turns, tickler 9 to 10 turns; for 80 meters, secondary 15 turns, tickler 10 turns; and for 150 meters, secondary 25 turns and tickler 20 turns. For smaller condensers, use one or two more turns in the secondary depending upon the total number used. No change is required in the tickler coils or the primary coil. When using the coils, the idea is to get a number of turns in the secondary that will place the middle of the band some- where near the middle of the condenser setting for best results. Correct Coupling for Receiver The degree of coupling between the pri- mary and secondary coils in a receiver should be carefully adjusted in order to obtain both sensitivity and selectivity. Be- cause of varying local conditions, the dis- tance between these two inductances will not be the same in every receiver. For POPULAR MECHANICS this reason, a little experimenting is neces- sary. Ifthe coupling is too tight, the local stations will cover a large part of the tuning dial, or even be heard faintly over the entire dial, being present as a disa- greeable background while distant broad- casters are tuned in. If the coupling is too loose, distant stations will be elimi- nated. Because of the extreme weakness of the signals, they cannot be transferred to the secondary coil. In the case of the local station, the oscillations are so strong they easily induce a current into the sec- ondary, even when the two circuits are not in resonance. There is a critical de- gree of coupling between the two ex- tremes which will not eliminate the weak stations but will sharpen the tuning of the locals, so that the former stations may be received. To find this critical value, tune in a distant station, one that is found near 50 on the dial, and slowly move the primary away from the secondary. At the point where the station begins to fade out, securely fasten the primary in place. It may be necessary to retune the set during this operation. Unit Protects A. C. Tubes A simple voltage-control device for pro- tecting a.c. tubes from high line voltage is now available. The need for such a device in some localities where the supply volt- age is often as high as 130 volts is very real, as the life of a.c. tubes is very short in such cases, regardless of the type of filament transformer employed in the re- ceiver. No tools are re- quired to in- stall the unit, which is sim- ply plugged into any con- venient outlet. The local power com- pany will ad- vise the user as to the max- imum line voltage in the locality. The a.c, set is then plugged into

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ae aa Sa ee oc POPULAR the outlet marked to correspond with that voltage and thereafter requires no further attention. A.c, tubes such as the 226 and 227- types must not be operated above their rated filament specifications and may be further protected by means of suitable filament ballasts in the line to each tube. Push-Pull Amplifier Kink If you are one of the many who would like to try ottt push-pull amplification, the idea illustrated in the circuit diagram is an eco- nomical method of changing the old a.f. transformer so that it will serve the purpose. This form of amplification has many advan- tages, especially in the output stage, and will be found in many of the latest sets. Bridge the sec- ondary of the first af. trans- former with two 100,000-ohm resistances as shown at Ri and Re; these provide a means of finding the center tap, or zero point, of the a.c. voltage in the secondary winding of the transformer Ti. This point is necessary for the application of the neg- ative bias to each tube. Resistances Rg and R4 are each of the 50,000-ohm heavy- duty type, ordinary grid resistors being unsuitable because they will not pass the necessary current for the correct opera- tion of the tubes. The B-battery is led to the center ee Saat ey Fil. CHOKE point formed Ly 3G & by these two resistances a} fF through an ru. Jt 2 impedance Li, B+! which may ‘ c A B+ Pwr. } LOUD SPEAKER? PUSH-PULL AMPLIFIER consist of the primary of an old trans- former or a standard 30-henry choke. This choke and the 2-mfd. condenser Ci act as a coupling impedance or output filter which keeps the B-supply out of the speaker winding. Two of the 171-type tubes are advised, the results being faith- ful reproduction and better volume. @Popular Mechanics’ radio department offers its information service free to all readers of our magazine. MECHANICS 481 Above, Complete Installation in Smail Space; Lower Left, Dry Trickle-Charger Unit; Insert, Right, 1,500-Ohm Condenser Battery-Operated Dynamic Speaker Converted to Power Alternating-current operation for the dynamic speaker of the 6-volt battery-op- erated type is a simple matter for those who wish to eliminate the storage battery. The illustration shows a dynamic speaker arranged for operation directly from the a.c. 110-volt, 60-cycle line. As the drain of a speaker of this type is only .6 amp., a dry trickle charger is used to supply the necessary d.c. current. This unit is shown at the lower left, and the reader will note that the polarity is carefully marked. It is very important that the red cord from the speaker unit be connected to the posi- tive terminal of the trickle charger. The condenser, shown in the insert, is one of the new low-voltage high-capacity types rated at 1,500 mfd. It is connected directly across the positive and negative posts of the charger unit and effectually reduces the a.c. hum to a minimum. These units take up little space and will work satis- factorily with any of the dynamic speakers designed for 6-volt d.c. operation. With some makes of speakers, it has been found that filament-control units in series shunted across the output terminals of the trickle charger, can be used instead of the condenser. This is, in fact, an experi- ment, but is worth trying.

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Fromm, tne i tee * Dink mimi i id ota he "ee alan’ o Sakon - VM dddlddldddddddddddddddddddddddddddddddddddded cdl Yj yj Y y f Vj y y j > TAPE OR! j i 2 i. i j VAR. RESIST. SUBPANEL OF j 4 0-500,000 aw ae 4 OHMS —s a+@ ) j ‘ Z VA i ‘ y y \ B-A- y y So. | RECEIVER : : A Small Variable Resistor : GND B+ DET. j } Provides a Simple Means for 2 y j Controlling Speaker Volume = B+ AMP. j ) and Sensitivity When Con- y y nected Either in — y~ B+PwR.¢ Y 4 the Antenna or across the An- #2 Z j tenna and Ground, as Shown BAKELITE TUBE B+PWR. 4 y in the Sketch at Right SSS Machine Screws Make Inexpensive Binding Posts; Left, Low-Loss y Primary Coil for R. F. Transformer Is Wound on Bottle of Size to Fit y) Inside Secondary at Filament End, 15 to Rey No. * S. C. ire Being sed; SeCguOARY Right, Front Vi Eclodion bere “Be ight, Fron iew ollodion before Be- WINDINGS of Dynamic Speaker i CORE. STAMPINGS , 482 Secondary Winding of Audio Transformer May Be Used as R. F. Choke; Remove Core Lamina- tions, Cap with Bakelite and Mount with Long Machine Screw as Shown Baffle, Rear View of Which Is Shown on Opposite Page VM hit iio ing Removed " ddcbadd SSS SSS SSS ss SSS REV SV VA VV WA W{| VIA gas aAd-A_AAAAAI_ AN WE

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; SEG Laboratory Gf sled cllldldldddddddldadadcascdidddddddcdddddidldddidddddidldd "MEL y U GUIDING EDGE ) OF TOP BOARD , j HACKSAW -——. CLAMPS.—~ TA VV VAUVEWVWwwsws> SRAM AAaw7» BAKELITE Above, Simple Guide for Cutting Panels; Below, Wood Blocks Pro- tect Panel When Clamped in Vise for Drilling or Filing SSS FIRST AUDIO In Testing for Noisy B-Bat- DETECTOR tery, Connect One Phone Tip, Y r TRANSFORMER Hold the Other and Touch Opposite Battery Terminal BAKELITE BUSHING SSSA SESS ~ “E 50,000 OHM +6 -F VaR. RESIST. SSS Y Right, Two Simple Methods of Controlling Receiver Volume HOLE IN CHASSIS — RAW NV VWH—-.C-—_ DB WAWWWWWv0° ww Nw) Left, Rear View of Dynamic- Speaker Arrangement Suitable for Small Theaters ; the Baffle Is About 4 Ft. Square and May Be Made of Celotex; Smaller Single Speakers - Give Excellent Results in Home AOQUNTING BOLTS SSS SSS oo Above, Two Simple Kinks of Insulating Leads Passing through Metal Chassis of Receiver SSS SSN WIRE TURNS PER INCH SSS Above, a Quick Method of Determining the Number of Turns of Wire per Inch for Any Coil; Wind the Wire Selected on a Pencil and Check the Distance with a Ruler, Then Count RMAVMWVDNiVBWW WwW Ww Doe V the Turns se / ttteaacadtdddddddtddddddddtsdhcaaaccceccdddacaccccldddddeeeeteeettt Udddcccaddde lll dldadd 483

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484 POPULAR MECHANICS f ~eine TEAR OFF WRAP THE STRIP A SMALL STRIP AROUND THE SPLICE The Successive Steps in Using the New Tape Solder Illustrate Its Handiness and Freedom from Waste Handy Solder in Tape Form A solder in tape form has recently made its appearance on the market, and is avail- able in 60-in. rolls and also in packages containing five 5-in. strips. No iron or torch is necessary, as the heat from a match or cigar lighter will make a good soldered connection. There is no waste in solder of this type, as just enough is torn off for each job. It is claimed to be non-corrosive and is, therefore, ideal for radio purposes, Regeneration Necessary for DX Real DX-results are only possible when some form of regeneration is employed. Care must be taken, however, in order not to interfere with the pleasure of others in the vicinity. The real DX-fan ordinarily listens in after everyone has gone to bed and knows how much regeneration he can use without creating a miniature broad- casting station. Regeneration may be obtained in various ways, and as the mod- ern r.f. circuit is invariably equipped with some means for stabilizing to prevent re- generation, this device can be easily lo- cated and temporarily altered for DX-re- ception. This will permit regeneration to approach maximum sensitivity and is easily kept under control. Cutting Down Resistance Stages The usual practice of using three stages of resistance-coupled amplification was necessary to obtain the same result as with two stages of the transformer-coupled type. The third stage may be omitted if high-mu tubes, known as the CX-340 type, are employed. The higher amplification factor of this tube makes up for the lack of step-up in resistance coupling and pro- vides just as much volume as two stages of transformer-coupled amplification. New Combination A-Supply A new A-supply unit supplies up to 24 amp. of current, which is sufficient to op- erate ten %4-amp. tubes. Power tubes, such as the 171 or 112-type, drawing % amp. each, must be counted as two of the Y-amp. tubes. The unit eliminates the 6-volt storage battery for the operation of practically any set employing standard d.c. tubes, making possible light-socket operation of the entire set if a B-elimina- tor is used. A receptacle is provided for plugging in the B-eliminator, and the en- tire power supply to the set is then con- trolled by the small pendant switch shown. A tap switch is provided in order to meet the requirements of the set and the voltage conditions in various localities. This switch is set at the lowest point at which normal reception is obtained. Only two units of this A-supply device can possi- bly be affected by prolonged heavy duty, the rectifier and condensers, which are easily replaced even by a novice. The unit is complete and ready to plug in. ya (SPECIAL PENDANT CONTROL SWITCH A-Eliminator Housed in Well-Ventilated Container, Showing the Various Controls \ POWER PPLY (8B ELIMINATOR as RECEPTACLE [olen il om]

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eS POPULAR MECHANICS 485 Laboratory Installation Showing the Projector and Disk at the Left and the Screen at the Right; Right, Doctor Alexanderson with the Filament and Tube Used in the Television Apparatus Projecting Television Pictures Television pictures projected on a screen by Dr. Ernest F. W. Alexanderson, of the General Electric company, in recent public demonstrations show a rapid advance in the new art. The screen employed is sim- ilar to that used for home movies and the pictures are remarkably clear, with good half-tone definition. The projector in- cludes a disk with 48 lenses, and the pic- ture or image is thrown through a ground- glass screen. One of the projectors was demonstrated at the last radio show in NewYork City, where sound and pictures were synchronized with satisfactory re- sults considering the experimental nature of the apparatus. The results are far in advance of similar television demonstra- tions where the picture is only about 1% in. square, and the rapid progress made within the past year promises an early solution of many of the problems involved. Improving Tone Quality The common practice of supplying all the tubes in a receiver from the same B- battery or eliminator is not by any means the ideal arrangement from the standpoint of tone production. A separate B-supply for the audio tubes will prevent much dis- tortion and also reduce the trouble experi- enced as motorboating. This is not a new idea, but the cost of an extra B-supply has discouraged its adoption in the past. In the present day of combined audio ampli- fiers and high-voltage B-eliminators, the objection against a separate B-supply for r.f. and detector tubes has not so much point, and a simple eliminator for this purpose can be built at low cost, or B- battery units can be employed. @QWhen making alterations in a receiver, it is always best to remove the tubes first.

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fon Sputter-Spaitter EARLY 4,000 outboard motorboat races were held last year in North America, and more than half a million skippers piloted some kind of outboard craft on our inland and coastal waters. Young and old have “outboarditis”—a dis- ease which rages by reason of the many recent developments in hull and marine- engine building. In the slang of our most active naviga- tors, an “outboard” is any boat from seven to seventeen or even twenty feet in length to the stern of which is clamped a light gasoline engine, propeller shaft and pro- peller—the pushing power. This power plant is one unit which can be easily at- tached, detached and lifted by one indi- vidual. Hence it is a “portable.” Because this small boat and power plant form the most convenient and economical combination for aquatic sport, outboards speed over the surface of almost every bay, sound, lake, pond, canal, river and creek in this country and astonish the heathen occasionally. Thousands of out- 486 boards travel across this and other coun- tries on or trailing behind motor cars so argonauts of the automobile may pause and navigate on casual water. Motorists thus tour by land and water alternately and find the water not quite so crowded as the road. But dyed-in-the-wool out- boarders are the maddest of racing fans. On a windy, sleety, snowy April day, young Earl Widegren of Locust Valley, Long Island, steered an outboard shaped like a large watermelon along the wave- tossed Hudson river from Albany to New York City, to win the Hudson Outboard Marathon of 133 miles at an average speed of thirty miles‘an hour. Young Widegren’s craft, named “Baby Olds,” was twelve and a half feet from stem to stern and fifty-four inches across the waist. It had a high-arching deck of tarpaulin, streamlines and longitudinal body steps and a nose like an airplane’s fuselage. It was in the air about half the time and was designed and built in an air-

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ut- ay, ley, ped ve- lew ard eed aby rom ross < of inal ne’s the air-

»Water-Speedster plane factory. It crossed the finish line all wet but winning because it had the de- sign and a dauntless navigator, plus a power plant weighing less than 150 pounds that worked faster than most airplane en- gines. “Baby Olds” was one of the latest things in outboard boats during the spring of 1928. It is a far cry from the 1913-model, single-cylindered outboard motor that pushed a flat-bottomed or clinker-built rowboat through still water at eight miles an hour, to the scientifically constructed power plant which rushes a transverse- stepped hydroplane over the waves at thirty miles an hour. Since the days of the “one-lungers,” sealed coils and con- denser casings have eliminated short-cir- cuiting. Separate feed pipes and cooling tubes now keep fresh and salt water out of lubricants. Two, three and four cyl- inders insure steadiness. Larger piston displacement gives more power. Costly and more serviceable alloys have displaced cast iron and common steel in the combustion and propulsion depart- ments. Outboard metal is often of higher grade than that used for similar parts in Fleet of Outboard Hydroplanes in a Fast Race through the Atlantic Waves in a Regatta on the Florida Winter-

Pleasure Coast motor cars. Vibration has been reduced and noise and temperament are disappear- ing. Mufflers are actually coming into fashion. Hence, since 1925, outboards have dominated larger racing craft in many events on protected waters, This change has been gradual. Judge Aaron B. Cohn, of Toledo, caused a sen- sation during the Detroit regatta of 1924 when he won the American Power Boat association’s outboard championship by speeding nearly twelve miles an hour! That performance broke down official re- sistance so effectively that “kickers,” “put- ters” and “sputter-spatters” were admitted to the exclusive Gold Cup regatta on Man- hasset bay. Then the outboards regis- tered a sensation by covering nearly twenty miles in one hour during the 1926 regatta of the Mississippi Valley Power Boat association, at Louisville. Now out- boards are welcomed at the Newport-Nar- ragansett competitions for large and small power boats. The once despised “water bugs” are speeding forward steadily. Outboard plants, once merely “kickers’ for fishing trips, are still depended on for long cruises, but, whereas the spark plugs on Lindbergh’s “Spirit of St. Louis” fired from 800 to 900 times a minute, the aver- 487

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3 POPULAR MECHANICS meet. Within two years, she was hailed as our leading lady outboard navigator. Yet she had hard luck in the Hudson River Marathon. The first time she tried to buck the winds and waves and currents be- tween Albany and the great metropolis, her mo- tor was killed by sleet and rain, she drifted help- lessly to the eastern shore and reached her destina- tion, soaked, in the ca- boose of a local freight train. Under the rules, she tried again. When the motor’s vibration started the seams in her cockleshell, she bailed and purred southward pluckily. Time and again rain or spray wetted the Making a Motorboat of Any Canoe or Rowboat, the Outboard Has Been Adopted by Thousands on Lakes and Rivers age outboard spark plugs fire from 3,500 to 5,000 times in sixty seconds. This is one reason why seven outboards, none of them more than seventeen feet long, bucked Lake Michigan and flood condi- tions in the Illinois and Mississippi rivers from Chicago to New Orleans and finished the 1,750-mile voyage at an average speed of twenty-two miles an hour. This improvement in mechanism, plus a gift for tricky navigating, permitted fif- teen-year-old Mary Alcott Richardson of Glen Ellyn, Ill., to win a handsome silver trophy by driving her tiny, thin-shelled craft along ninety-six miles of rough Lake Michigan to win the Milwaukee-Chicago Outboard Marathon. A few months later thirty-five outboard devotees started from Boston for New York City, via Cape Cod canal and Long Island sound. C. P. Stevens, Jr., of Al- bany, won $1,000 by negotiating the 260 miles five minutes and six seconds ahead of the runner up, Al Buffington, of Fall River, Mass. Helen Hentschel, of Flushing, N. Y., graduated from a swimming class to com- mand of an outboard in the 1925 Gold Cup spark plugs of her en- gine, but she sucked salt from the wire ends and started her motor hopefully. Forced to lean across the steering wheel to pump air into her auxiliary fuel tank, the boat’s pounding so agitated her stomach that she was nearly as dead as the motor, when kind rivermen towed her into Garrison. But though Helen did not win that marathon, she did win against famous European outboarders on Lake Trem- plin, Germany, by doing 28.7 miles an hour. Then she hurried back to try for outboard honors in California and Rhode Island. The boys and girls who pilot outboards, against mature men in many cases, run many risks in their erratic speedsters. The “Driftwood Derby” of July 4, 5 and 6, at St. Louis, is an example. Officially it was the twenty-first annual regatta of the Mis- sissippi Valley Power Boat association, witnessed by 30,000 people, but, between snags and river steamers, it resembled a log-rolling contest. Two boats of the 151-class sank to the river bottom permanently. That didn’t discourage the dozens of outboard speed- sters. H. M. Frazier of Auburndale, Fla., got his water bug into a backwash , wane a Oe ee CU

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id tO POPULAR MECHANICS 489 Saskatchewan, Canada which jammed his head against a stone bridge pier. But, like entrants from De- troit, Cleveland, Birmingham, Kansas City, Houston and Wilmington, N. C., and other cities, Frazier stayed with it, to ap- plaud an outboard record of 33.33 miles an hour made over a course referred to as “a practice for the River Styx.” Naturally outboard racing creates ex- citement and develops the industry just as motor-car racing developed motor cars. sut thousands of miles are traveled annu- ally by amateurs who “putt” for pleasure in their water flivvers. Afternineteen years in his local courts, four terms in his state legislature, nine trips to Labrador and various experiences as a state’s attorney and a world-war aviator, Judge William J. Malone, of Bristol, Conn., loaded his family and friends on his twenty-foot out- board cruiser and expiored the Ohio and lower Mississippi from Pittsburgh to New A Houseboat Pushed by a Six-Horsepower Engine, Top; Duck Hunter, and a Fisherman at Fish Lake, Orleans. The same spirit of aquatic ad- venture sent Mr. and Mrs. Rockwell Stevens clear across France, in an out- board boat, much to the astonishment of the natives. But the water flivver is solv- ing engineering problems as well as giving pleasure to the traveler. Not long ago the mine manager, A. B. Norris, had to get some six-ton boilers from Quebec to the Melartic gold mines, 433 miles in the Canadian wilderness. The mines were forty miles from the nearest

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490 railroad. Pack horses were out of the question and the roads were impossible. So he made his boilers air-tight, tied them to large canoes, equipped the canoes with outboard motors and floated the boilers up forty miles of winding stream. This feat could not have been accom- plished but for a recent improvement in outboard equipment through which a pro- peller shaft is not bent or broken when the propeller strikes a stone or other un- yielding obstruction, but is tipped upward and backward unharmed. The only part damaged is a small brass sheer pin. A new pin is put in place and the voyage proceeds. During the Norris adventure, the propellers often hit river bottom but no material damage followed. Nothing suffered but the sheer pins. Outboards also go in for dramatics. Through the blackness of a winter’s night, between cakes of ice and over white-capped waves, Ralph Anderson steered an open boat, pushed by an outboard, from Isle Royal, in Lake Superior, to the Michigan mainland and a doctor. Anderson’s com- panion was a fellow trapper who had been seized with acute appendicitis. Anderson had the option of operating with a fish POPULAR MECHANICS knife or getting his companion to a doctor, During a sudden flood which submerged a large part of North Sacramento, Calif., the Wilbur family rescued 300 marooned fellow citizens in the Wilburs’ water fliv- vers, That was an all-night job, also. Inexpensiveness as well as versatility increases the outboards’ popularity. Fol- lowing the custom with auto motors, the outboard engines are classed according to piston displacement. Class A, in out- boards, has less than fourteen inches of displacement; Class B, from fourteen to twenty inches; Class C, from twenty to thirty inches; Class D, from thirty to forty inches ; Class E, from forty to fifty inches; Class F, from fifty to sixty inches; Class G, from sixty to eighty inches and Class H from eighty to a hundred or more inches. Of course, most outboarders have to buy their motors, though one can. rent and sometimes borrow a motor. Capt. Elmer E. Dunn, of St. Petersburg Fila., rented one for fifty cents, rented a boat for $10, tuned up a bit to get experience, for he was the rawest kind of outboarder, and cleaned up at the Miami Beach Re- gatta of the Florida Outboard Racing as- The Flivver of the Lakes; Speeds of Fifteen to Twenty-Five Miles an Hour Are Not Unusual for Outboard Boats Capable of Carrying Four to Six Passengers in Comfort

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a) nt POPULAR MECHANICS 491 A Pair of Secondhand Wheels and Ties, an Old Axle and a Few Odds and Ends Provide a Trailer and Eliminate the Necessity of Storing the Boat or Owning a Boat House sociation last winter. It does not take years of training to make a successful out- board racer. The manufacturer helps the amateur. The modern outboard motor is the only marine engine using ball bear- ings and roller bearings for internal work- ing parts. If an outboard fan does not feel like investing in a fancy hull with transverse bottom steps (which make it a hydro- plane) with streamlines and brass finish- ing, he can build his own for a few dollars. Ovide Siouxi, great chief of the Huron Indian tribe, built one from working plans that weighed 140 pounds and cost $75, and made a speed of thirty miles an hour. But. lots of boys build cheaper ones, called “punkin seeds,” “tubs,” “crates” and “strawberry boxes.” In one of these crude small ships, about as pretty as a slab of wood, eleven-year-old David Leonard beat some of the season’s most skillful skippers to the Class-B champion- ship at Winter Haven, Fla. Having won so many peace-time vic- tories, the captains of our “water bug navy” are getting ready for war-time work. At the rate the outboards’ speed increases they will be “cracking” fifty miles an hour in a year or so. And if we engage in another war, the mosquito fleet of water flivvers will do their bits in many a naval engagement. Each fleet outboard will be canvas-cov- ered like a kayak and will head straight for the enemy ship or transport. Each outboard will bear a torpedo. As each captain of a tiny craft gets within striking distance of the enemy, he will go over- board in his life belt, leaving his ship to keep its course on the surface or beneath the surface of the water. The deadly tor- pedo will do its work. There will be plenty of skippers for these infant outboard destroyers. Probably Malcolm Pope will be one of them. Malcolm lives at Winter Haven, Fla. He starts the outboard on one of his home town’s hundred lakes, attains a speed of thirty or more miles an hour, shoots his boat up a wooden incline, soars forty feet straight through the air, splashes safely on the water again, and then, for good measure, gets up to high speed once more and skids his light vessel up the sand beach to dry land. Malcolm proposed the mosquito fleet of outboard destroyers. You'll have to keep an eye on these young skippers. No tell- ing what the outboarders will accomplish now that they try almost anything, PAPER IS USED FOR BLASTING AFTER CHEMICAL BATH Intended especially for the use of farm- ers and quarrymen, a kind of paper, sim- ilar in appearance to ordinary blotting material, has been prepared for blasting. It is coated with a hot mixture of chem- icals and water, dried and then cut into strips, which are rolled into cartridges.

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a FE a ag YA SAS ate 492 Applying Plaster Patch to Ceiling When redec- orating an old ceiling, I found a sec- tion of it was badly cracked, Most of the cracks con- verged to one point where the plaster had broken away entirely. I removed all the loose plas- ter around this + spot and then drove large-headed roofing nails into the lath, letting them project about 4% in., to serve as anchors for the plaster of paris with which I mended the place. Then I took a smooth board, about 1 ft. square, and held it against the soft plaster by means of a length of 2 by 4-in. wood, set on the floor, a wedge being used between the floor and the pole to force the board firmly against the repaired section. When the plaster had set and the support was removed, the patch not only was smooth but held the surrounding plaster securely. —Dan Courtney, Chicago. Racing Blades Fitted to Clamp Skates Racing blades can easily be fitted into the runners of ordinary clamp skates by sawing or filing a groove in the runner, setting the racing blade in place and then soldering it in the groove, using muriatic acid cut with zinc as a flux to make the solder adhere to the metal. Of course, care should be exercised to cut the groove accurately. It may be necessary to shorten the racing blades one or two . inches so that they will not project too far beyond the end of the runner, for, if they do, they may easily be bent. I have found skates POPULAR MECHANICS altered in this way highly satisfactory; they can be more easily handled than or- dinary skates and the clamping feature is quite an advantage—Sam Weidman, Lowell, Wash, Cleaning Ducks Quickly Picking wild ducks is a task that most sportsmen gladly leave to their wives. The large feathers are not so hard to remove but the down is very annoying. An easy method is to pour melted paraffin over the bird before picking the down and al- low it to congeal. It is then easy to rub the down off with a rotary motion of the palm, leaving the skin clean. Another method is to dip the hand in partly melted paraffin and then massage the feathers off. Either method practically eliminates the need of singeing. Certain kinds of ducks, such as bluebills, butterballs, golden eyes and coots are better skinned than picked, as the objectionable fishy or oily taste disappears with the skin and the fat ad- hering to it. Protecting Wash-Boiler Bottom Leaks in wash boilers usually occur near the edge and are caused by sliding them on and off the stove. A length of lightweight angle iron, fitted around the edge of the boiler as shown in the drawing, greatly in- creases the life of the boiler by elim- inating wear on the bot- | tom. The an- gleiron should be a few inches longer than the distance around the boiler as measured with a tape, is bent to fit snugly and securely clamped at one end as indicated. It is necessary to make saw cuts in‘one side of the angle iron where it is to pass the rounded ends of the boiler, as shown in the upper detail. The angle iron also reinforces the boiler so that it is dented less easily—Wendell Mitchell; Rogers, Nebr.

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ir 1g of 1¢€ POPULAR MECHANICS 493 Old Auto Having a Propeller Attached to the Driveshaft Runs Log Catamaran on California Lake Old Auto Propels Catamaran At Lake Almanor, in California, an old auto has been used successfully for pro- pelling a catamaran made of logs. The auto is securely mounted on the cross members, and a propeller is attached to the end of the driveshaft, which is ar- ranged so that the screw is submerged. Running the motor slowly furnishes am- ple power and surprising speed, enabling the catamaran to travel all over the lake.. —Grace E. Grohman, Stockton, Calif. Novel Bird House Bird-house contests held in New York rural schools brought out many new ideas. Many peculiar houses were entered in the contest, and one that won first prize was made from the large fungi found growing on certain trees. Cut-off pieces of this growth were found to become very hard when dry. The house shown on the left in the photo is a home for a song sparrow, the measurements, according to the contest rules, be- ing approximately 6 by 6 by 6 in., with all sides open. The top and bot- tom consisted of pieces of fungus, and were held together by means of lengths of hickory twigs about as thick as one’s thumb. Three- penny nails were used to fasten the top and bottom to these posts, the nails being driven into the ends of the posts for a distance about equal to half of their length. The heads were then cut off, and the ends sharpened so that they could be pushed into the fungus. A daub of glue was also put on the end of each post, or on the fungus at the points where the posts were to stand. Stout cord was wrapped around the house after it had been assembled, and it was laid away to dry. After several days, the fungus was hard and the posts were firmly in place. Instead of trimming these posts, a few branching twigs had been left on to pro- vide a place for the birds to alight. The feeding station was also made from fun- gus, two pieces being rigidly attached to a short board to hold them.—Cora Hamil- ton, Binghamton, N. Y. Novel Bird Houses Made from Tree Fungi Win First Prize at School Contest

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494 Simple Trick with Handkerchief Which Can Be Easily Performed by an Amateur Clever Handkerchief Trick For parlor magic, the clever handker- chief trick described in this article will be found amusing. The performer takes an ordinary drinking glass, of the thin va- riety and with straight side, in his hand, and while standing before his audience, turns it to show that it is empty. Then he places a small red handkerchief in it, and covers the glass with a black cloth. He ‘ tells the audience that he will make the red handkerchief turn white without re- moving the black cloth, and upon remov- ing the black cloth this appears to have happened. The handkerchief can he passed around among the audience for in- spection, after which it is again placed in the glass, covered with the black cloth, and it is turned red again. Prepare for the trick in the following way: Be sure to use a glass of the description given, as the trick will not work with any other shape. Take two pieces of mirror, the exact width and height of the inside of the glass. Ce- ment them together back to back, place them in the glass, thus dividing the latter into two compartments. The mirrors cannot be noticed by the spectators as the glass is held so that they look into one mirror, which gives the impression of a plain glass and makes the tumbler look empty. The red handkerchief is placed on one side of the mirrors and a similar white handkerchief on the other side. When, in performing the trick, the black cloth is placed over the glass, the performer turns the glass around unnoticed. Thus, if the POPULAR MECHANICS red handkerchief is placed in the compartment facing the audience, the white handkerchief will come into view when the black cloth is removed, and so on.—E. A. Hoppman, Dumont, N. J. Repairing Leaky Cellar Walls At times cellar walls will leak and the condition seems to get worse if neglected. A simple method of repairing a leaky wall is to drive one or more pipes through it at the points where the leakage is worst. The pipes should be calked with fibrous ma- terial or lead, so that there wili be no leakage between the wall and the pipe. After all the water has drained and the wall has dried out thor- oughly, the inside surface is given a coat of waterproofing compound. When this has dried, the pipes are removed and the holes plugged tightly—L. H. Georger, Buffalo, N. Y. Handy Pistol-Shell Remover Trappers will appreciate the handy pis- tol-shell remover shown in the illustra- tion. It is made by grinding off the end of a key, as indicated by the dotted line. Plunging the shank of the key into the force it It should be kept on the key ring empty pistol shell will quickly out. CUT OFFON _ DOTTED LINE Door Key with the End Cut Off Makes Handy Pistol- Shell Remover in order to be always available for use.— Harold Eckebrecht, Chicago, IIl.

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O THE man who has not a console, or other cabinet, large enough to contain a baffleboard, the mounting of the dy- namic speaker presents something of a problem. It is easy, of course, to build up a small frame with a shelf across the back; fit a wallboard panel on the front, and, if this assembly can be hidden from sight in some way, nothing more elaborate is necessary. Where the speaker mount- ing is visible, however, something more decorative is essential, and the stand de- scribed in this article is ideal for the pur- pose, as it is not only simple to construct, but forms a very pretty piece of furniture when properly finished. As may be noted in the head illustration, when the stand is in use set in front of a fireplace or near the wall of the room, nothing of the speaker itself is visible, and the stand resembles only a decorative screen. The materials necessary for the con- struction of the stand proper are two pieces of five-ply veneer, %4 in. thick, 24 in. wide and 32 in. long. One side of the veneers should be of nicely figured walnut or mahogany. The maker can choose any of the four designs shown in Figs. 1 and 2, and none of them presents any difficulty in laying out; the only thing to be borne in mind is that the circular hole in the front of the screen, for the speaker cone, must not be placed cen- trally, but should be a little higher than the center of the front. In the stand shown in the illustrations, the center of the hole is 12 in. from the top of the screen. In Figs. 1 and 2, the left half of the- drawings repre- sents the shape of half the front, and the right half, the supporting brackets, and it will be noted that the brackets are cut so that their length is slightly less than that of the front, at the edges. The pieces may be cut to shape either on the jigsaw or with a hand coping saw, and the only precaution to observe is to use sharp blades in the saw, so that there will be no tendency to flake off the edges of the walnut or mahogany veneer. The brackets, of course, should be laid out so that the face veneer will be on the outside on the finished stand; this seems an un- necessary warning, but it is very easy to make a mistake and lay them out so that, when cut to shape, one finds that there are two right-hand or two left-hand brackets, instead of a right and a left. After cutting to shape, finish the edges by filing and sanding dead smooth, then mold the edges of the screen front. Note that the molding on the edges is not car- ried down to the feet, but is stopped about 3 in. from the bottom. The molding may be a simple bevel or a hollow on the edge, and, in this case, it may be done with the chisel or gouge, on the shaped parts, and with the molding plane on the sides, but if any of the more elaborate moldings is desired, the maker will find it advisable to take the piece to the nearest cabinet shop and have them run the moldings on the shaper, since, although it is easy to run the moldings on the straight edges with the molding plane, it is difficult to mold 495

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496 POPULAR MECHANICS the shaped edges. Also, the edge of the circular hole should be molded the same as the outer edges, and this can be done in a few minutes on the shaper. If the reader cannot have the molding done as a oF me b J ry Fic.! described, it is advised that he simply bevel or round the edges of the front, and make the grill for the hole as described later, so as to avoid the necessity of mold- ing the edges of the hole. The edges of the brackets may be left square, or just rounded a trifle by means of sandpaper. Since the screen is, to be fitted with a grill, and since the grifl would be too tar back if it were simply fas¢ened to the back of the screen, which is 3% in. thick, it is necessary to sink a recess™in the back of the screen so as to bring thee grill for- ward, Before describing this, however, we will tackle the grill. \ The maker, of course, can use \4 wood grill if he chooses, but the one iMusgtrated in the photos was made of sheet lead, This may seem to be too weak and soft, buy 45 a matter of fact, it makes a very satige!ac- tory grill, and one that is decidedly novel and effective. As shown in Fig, 4, tit lead is cut to represent a landscape, ands when backed with gold cloth, the effect 1\5 quite striking. The lead used is “4g-ir® sheet, which can be obtained from th? nearest plumber’s shop. The size of the? opening in the screen, of course, depend ‘S on the size of the speaker cone, and conse ~ quently the size of the grill depends on this also, but a 14 by 14-in. piece is amply large enough even for a 10-in, cone. Lay out a circle of the size of the opening on a sheet of paper, rule it off into 1-in. squares, as in Fig. 4, then sketch in the landscape by referring to the squares in the illustration. Flatten out the lead ss Left, Gluing a Bracket to the Front; Above, Alternative Designs for Stand; Below, Detail of Joint between Bracket and Front oe ee ee ee ee - - wn

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POPULAR MECHANICS i Y Above, Fitting the Shelf; Note the Recess on Back of Screen; Below, Design for Sheet-Lead Grill; White Parts Are Cut Out it ly ay yn in. he in ad sheet, pin the paper centrally over it, then trace over the design with a fairly sharp, but round-pointed seriber, so as to impress the design on the soft lead. Remove the pa- ‘ per, and cut out the design with a knife, taking ‘care to make the cuts clean and sharp. Now take a small screwdriver, and “texture” the trunks of the trees by striking the screwdriver lightly with a hammer, varying the impression and direc- tion of the screwdriver point so as to simulate as closely as possible ) the. batk-of the tree. The same tool will do for making the leaves beast of the pines. If the reader has an assort- ment of small punches, he will find that it is an easy matter to grain and texture the surface of the landscape to produce a very creditable effect, but a small screw- driver, a couple of nail sets and a small round-nose chisel will enable him to do a very good job of landscape “painting.” If the edge of the hole has been molded, this is all there is to do to the grill. If, however, the reader has not been able to iehe mold it, then a sort of ornamental border, joint about 3¢ in, wide, should be punched all around the circular rim of the design, and the edge of the sheet lead should be cut to form a shield, as shown in the illustra- tions. An ornamental border can then be punched around the edge of the shield, and the whole grill may be fastened with gimp tacks over the opening in the screen, thus hiding the edge of the hole. Setting the grill in from the back, with the open- ing molded, however, makes a much bet- ter-looking job. For the recess, centering on the open- ing, at the back, lay out a 12-in. square,

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then cut out the wood _ within this square until the bottom of the re- cess just meets the edge of the molding around the screen opening. The maker had better have this done at the same time as he has the mold- ings shaped, as a job that will take the cabi- netmaker only a short time to do on his router will be found rather tough with hand tools, although it can be done. If done by hand, see that the bottom is smooth and flat, also that the “sight edge” around the molded opening is even all the way. The height of the shelf that supports the speaker at the back depends on the di- mensions of the speaker used, so no meas- urements can be given for this, or for the width of the center of the shelf. Any piece of wood, about % in. thick, will do for the shelf. It slides into dados or grooves cut in the brackets, and the maker will find it advisable to fit the shelf a little lower than is actually needed, and to shim the speaker up afterward. In this way, it is easier to center the cone of the speaker over the opening in the front. If no means of cutting the dados for the shelf is at hand, simply screw two strips of wood at the proper height on the inside of the brackets, and screw the shelf to POPULAR MECHANICS these. Be sure to make allow- ance for the 3%-in. cloth-covered plywood insert described later, so that the shelf will be cut wide enough to support the speaker. Turn two feet from walnut or mahogany, 1% in. long, as shown in Fig. 1. The diameter of the upper collar on the feet is the Left, Cutting Out the Design on the Grill; Right, Punching or Texturing the Design ‘ same as the thickness of the wood front, ¥% in., and the diameter of the foot is 1% in. Drill the feet and the bottom of the stand front for 4 or %-in. dowels, and dowel and glue the feet in place. The brackets are set back from the edges of the front 1 in. Mark a line down the back of the screen 1% in. from each edge, and, along each line, lightly drive in four small brads; cut off the heads of the brads, and sharpen the projecting points. Now set the brackets in place, with their lower ends even with the bottom of the feet on the screen, and with their thickness cen- tering on the line, and press them down on the sharpened brads; this marks the position of the dowel holes. Withdraw the brads, and drill for the dowels, taking care that the holes go only three-fourths of the way through the screen. (See Fig. 3.) Dowel and glue the brackets in place and clamp; leave until the glue is hard. ee wm

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w- ed er, de er. or vn he he iring ont, 1%4 the and The S of yack and, mall and CR ywer t on cen- own the lraw king irths Fig. ylace rd. POPULAR The screen should lean back from 1 to 1% in. at the top, so, when the glue is hard, mark and cut off the feet of the brackets to secure this effect. Now sand the faces- of the screen and brackets very carefully. Stain the work walnut or mahogany to suit the veneer used, then, after the stain has set, give a coat of walnut or mahogany paste filler, wipe off across the grain, and screen. MECHANICS 499 leave todry. When dry, sand down again, working the sandpaper in the direction of the grain, dust off, and apply a coat of thin shellac. When this has set, sand down with “Wetordry” garnet paper, used wet on a felt pad, dry off and give another coat. Sand this down as before, then give one or two coats of cabinet-finishing var- nish, rubbing down between coats with . pumicestone and oil, on a felt pad. The last coat may be simply dulled with the pumice and oil, rubbing lightly length- wise, or, after rubbing, it may be repol- ished by using rottenstone and oil. Now cut a piece of %-in. plywood to fit the recess in the back of the screen, and cut a hole in the center the same size as the one in the screen. Cover the ply- wood with gold cloth, carrying the latter over the edges of the wood and gluing it to the back. Tack the grill in the recess, then place the cloth-covered plywood over it and fasten it with brass screws. Set the speaker on the shelf, shim with card- board until it is centered over the opening, then screw or clamp the edge of the cone ring to the wood. Three brass clamps will fasten the speaker very nicely to the Above, Finishing Stand, Showing Cloth-Covered Insert behind Grill; Below, Grill in Shield Form for Use on Face of Stand

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500 POPULAR

i ROPE 7 ———

Seid hf Por een SO

—-TWINE — LEATHER BRASS SCREWEYE DETAIL OF WRAP STRAP ance. After one MECHANICS %-in. rope with narrow eR ee TAPESTRY OR TERS , > time. Ls

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WV - he he ap n- en nic flat lan ood 1 in e of iece th a t as nda iten isel, his hing yne, two con- +§ ch sy to hisel oper the POPULAR Warming the Bed on the Sleeping Porch When going to bed on the sleeping porch during the winter time, more com- fort is assured, if the bed is warmed just before retiring. Here are a few simple methods which have been found success- ful: In one case where the porch was located directly over the living room, the owner cut a hole through the floor, di-. rectly under the bed, and installed a floor register, so that the warm air from the living room would come up under the bed. To prevent the heat from being lost in the cold room, a piece of canvas was placed over the mattress and extended down to the floor on all sides, thus com- pletely inclosing the space under the bed. Another method consists in putting an electric heater under the bed shortly be- fore retiring, and placing blankets over the bed so that they touch the floor on all sides, thus keeping the heat under the bed. Of course, it is necessary to be care- ful when using an electric heater to avoid fire. A third method consisted in pro- viding a hot-water coil underneath the bed, the coil being connected to the hot- water tank in the kitchen, which was lo- cated next to the sleeping porch. When such a system is installed, the possibility of freezing should be considered in case the fire in the range is not kept up; it is advisable, therefore, to install a drain valve in the pipe to empty it—Harold E. Benson, Boulder, Colo. Handy Place for the Golf Score Card When hur- rying around a golf course, I have often wasted time fumbling through my pockets for the score card and a pencil. To avoid this, I took a small paper clip and attached it to my golf bag and tied a pencil on with a length of heavy string. Both card and pencil are then handy.—R. J. Plaisted, Cleveland, Ohio. MECHANICS 501 Ant | (a A Ws Pk 74am td eX ce = | Lap Boards Are Easy to Make and Can Be Used for Many Purposes about the House Lap Board Has Many Uses One of the most useful and convenient articles about the house, and one which is easy to make, is a lap board. I have made a number of these for my friends, who find new uses for them every day. The exact dimensions may be varied to suit the maker, but a satisfactory size for gen- eral use is one 20 by 30 in. in dimensions and % in. thick, with a semicircular por- tion, about 4% in. deep, cut out at the front edge, as shown. Cleats should be screwed or nailed across the back, but a neater job can be done by tonguing and grooving the end strips against the body of the board in the same way as drawing boards. I made some of the boards in the finest Honduras mahogany, embellished with a fancy border inlay, and the owner's monogram executed in marquetry of rare woods. The surface was given an appli- cation of paste wood filler, varnished and rubbed down. Lacquer can be applied if cheaper wood is used and beauty is not considered.—R. L. Simons, St. Paul, Minn.

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502 POPULAR MECHANICS a _ ae G Efficient Pump Jack Can Be Made from an Old Auto Crankcase Running the Pump with Farm Engine A good, inexpensive pump jack can be improvised from an old auto crankcase in which the shaft has been left intact. The crankcase is inverted, as shown in the illustration, and is placed so that one end of the shaft lines up with the handle of the pump. An-old connecting rod is securely fastened to this end of the shaft, while a pulley is keyed to the other end. The pulley should be large enough to keep the pump speed at about forty strokes perminute. A length of flat iron is pivoted to both pump handle and connecting rod as indicated, Although the drawing shows the pan removed from the crankcase, it is better to leave it in place, espe- cially if there are children who are Auxiliary Gas Tank Is Automatically Kept Filled for Emergency When Gas Is Needed likely to come near the pump while the engine is being operated. Auxiliary Gasoline Tank Prevents Stalling With the auxiliary tank shown in the drawing it is impossible to knowingly run out of gasoline while driving a car. When the main tank is exhausted, it is only nec- essary to lift the hook, open the shut-off valve, and the contents of the auxiliary tank will take you to the nearest filling station, provided it is of sufficient capacity. It is automatically kept full at all times, and requires no attention after it is once installed. The construction is simple and the cost should not exceed $2. It can be installed on any car having a vacuum or electric-suction system from the main gas- oline tank. The parts required are: one small galvanized-iron tank which can be made to the desired shape and size at almost any tin shop; two short lengths of copper tubing of the same diameter as that used in the gasoline system of the automobile; two brass compression-fitting elbows; one brass compression-fitting shut-off cock, and one brass compression- fitting tee. These items can be obtained at any auto-supply house. The tank should have straps soldered securely to the front and sides, the ends of the straps being bent, as shown, to permit attachment to the dash. The size and shape of the tank depend on the space where it is to be mounted. The two elbows are soldered to the top of the tank and the shut-off cock to the front, near the bot- tom, care being taken that all con- nections are leak- proof. Fasten the tank securely to the dash near the vac- uum tank. Discon- nect the main feed pipe from the vac- uum tank and con- nect it to one of the elbows, as shown. Connect the other elbow to the inlet on the vacuum tank

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ne be as he ng ing at uld ynt nt, sh. nd ere ed. are top the the ot- ng on- ak- the the ac- on- eed ac- on- the wn. her niet ank POPULAR MECHANICS 503 (where the feed pipe was for- merly). Cut the tube leading from the vacuum tank to the car- buretor and insert the tee, which is then connected to the cock on the bottom of the auxiliary tank. The cock is kept closed all the time, except when the gasoline in the auxiliary tank is needed. The vacuum tank draws gasoline from the main tank through the auxil- iary tank, keeping the latter full all the time. When the main tank runs dry, the vacuum tank will not draw the gasoline out of the auxiliary tank, but the supply in this tank can be released by open- ing the cock that controls the flow into the carburetor.—Albert D. Sayer, San Pedro, Calif. Collapsible Fishline Drier Many fishermen, who have good lines ahd know the advisability of drying them thoroughly before putting them away, will appreci- ate the collapsible fishline drier shown in the drawing, which can be folded up and put away with the rest of the fishing tackle when not in use. It consists of four strips of wood, of which two are a trifle less than half the length of the others. The longer strips have holes drilled in each end and the shorter ones have a hole drilled in one end only. The assembly is clearly indicated, two screws fitted with wingnuts being wi used to hold the pieces to- gether. The shorter strips are pushed be- tween the 9" longer ones - when the de- vice is folded, and when it is opened, the t strips are set at { right angles to Lui each other, and ; the wingnuts tightened to hold them securely in this position.—W. A. Murphy, Marshall, Tex. ‘ae SECTION OF ~ ls OLD AUTO eet ' ny wait itt Ba Heavy Rubber Pad Made from Old Auto Casing Protects the Shoulders When Carrying Heavy Loads Shoulder Pads Made from Old Auto Tire A comfortable shoulder pad can be made from a section of an old tire as shown in the drawing. By stripping off a greater or less number of layers of the fabric, its thickness may be varied. Work- ers who carry heavy loads will find it use- ful, and to sportsmen it will be serviceable for carrying canoes or equipment, or wherrit is necessary to haul a boat through fast water by means of a drag line. Finishing Plastered Walls with Paint Many amateur craftsmen, who have un- dertaken the painting of newly plastered walls, have been of the opinion that the wall must be sized with glue or some other similar substance before it can be given the finishing coats of flat tints. A better method of preparing the wall is to apply a priming coat of paint on the plaster in- stead of the size. sang jae ee ins wn toms enh seit wer 2 VRE SGU A IETS tire ct srpring neers eran ine arena BOO ON ae “BIS

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¥ “ — —— an A OO ‘a 4 » sf . } ey y He _ Ve oi ‘¢ 4m, . ie - hae Op Foe eP2 # a a aud: a sae HE STAINED finish is the accepted high-grade finish of today, correct in taste, reflecting dignity and used in the expensive suites. Walnut and brown ma- hogany, the popular finishes of the past few years, grace the interior of the more modernly furnished residence, but there are still countless homes with the golden- oak furniture of a decade ago, and com- paratively few which are not “blessed” with at least some pieces in this once pop- ular finish. These can easily be changed to the modish walnut and browrm ma- hogany. The work is interesting, it is a profitable use of spare time, and there is a great deal of satisfaction in the attain- ment of fine results to the man who en- joys producing things with his own hands. There are two ways to do this finishing. One is to color the wood with stain, and then apply coats of varnish. Practically all new furniture is treated at the factory in this way. For the finest refinishing, the old finish is removed and a new one built up from the wood with stain and varnish coats. The other method is to 504 x at 4 m, 2 , Refinish 1) The Use of Varnish Stain Sos n> oaks ta ray = = t% Wy ~~ i ee 5 rs 3 ** > a] Sy; ‘A RY? it +) i oe de S: & x 8 aoe y.& i — ae $ he — use varnish stain (stain and varnish com- bined) over the old coating. In this issue we will describe the quick method of varnish-stain finishing without the removal of the old finish. Much real- istic and beautiful work has been done in this way, and a really nice finish may be produced, suited for any except very fine pieces. We will take, for instance, a dresser in golden oak finished with gloss varnish, and follow the operation of changing it to a walnut finish. (The pro- cedure will be the same for any of the dark-stain finishes; and light-stain effects, such as silver-gray, cannot be satisfac- torily produced over a darker finish.) The first step is, of course, to clean the surface by washing with soap and water, followed by a rinse-off with clear water. Wipe the surface with a cloth wet with gasoline, naphtha or benzine, to cut and remove any greasy substances that may be present from handling, or from the use of greasy or oily polishing preparations or of wax. The next step varies somewhat accord-

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ain Wee Aa. 2. RS ym- ick out eal- > in be fine loss of rO- the cts, [ac- the ter, ter. vith and y be 2 of or »rd- ", Ke Ce Wy atts ee 4.5 ing to the condition of the old finish. If good, a light sandpapering to cut the gloss is all that is necessary. If it has been chipped off so there are depressions in the surface, the edges around the depres- sion should be feathered or tapered with sandpaper. In case the old varnish finish is badly checked or “alligatored,” there is nothing that will prevent the checks show- ing through the refinishing coats. These will actually magnify and emphasize the checks and cracks. In such cases, the only way to do a really first-class job is to re- move the old finish. If this is not desired, the checked finish should be sanded down thoroughly, especially on all conspicuous surfaces, such as the dresser top, fronts of drawers, etc. This, although it will not remove all trace of the checks, will sand them out to some extent. After the sandpapering has been com- pleted, the surface should be dusted clean from all particles of sand and sawdust, immediately before starting to apply the finishing coats. When using varnish products, it is important that every bit of dust be removed from the surface, as every speck shows through the transparent var- nish. Watch out for dirt in corners, erton'Elli@ty #eedy > GP oo crevices and carvings, which will be picked up by the brush and distributed over the surface. Our dresser is now ready for the actual application of the refinishing materials. Drawers should be removed. (If desired, the mirror and the uprights supporting it may be removed and left off entirely, or the mirror hung on the wall from the pic- ture molding just above the dresser.) The first application is an evenly brushed-on coat of walnut varnish stain. As the shade of any stain material varies according to the surface over which it is applied, it will be a good idea to try out the finish on some inconspicuous part of the dresser, to see if the effect is satisfac- tory. This can perhaps be done on the back of one of the legs, or on an edge next ‘to the wall. If the effect is too dark, it can be lightened by adding a little turpen- tine. If too light, an additional coat may give the desired effect. Each succeeding coat of a varnish stain darkens the sur- face perceptibly, and three or four coats may give you just the effect you want. After the try-out, the required number of coats of the stain should be applied over the entire surface. In doing the top or other large panels, do a strip 3 or 4 in. wide the full length of the panel; then 505

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POPULAR Some Crude Oil, Pumice- stone and a Piece of Thick Felt Are the Only Things Necessary for Producing a Rubbed Finish MECHANICS grain without refilling the brush, and finally brushing with the grain again, with long, sweeping strokes. Dirty work is one of the principal causes of defects to be guarded against in varnishing. Nothing spoils a beau- take another strip of the same width, and so on over the entire surface, working quickly to prevent the edge from setting before you get back over the next lap, which would cause streaking at the over- lap. If the material drags a little under the brush and goes on with a blotchy ap- pearance, add a little turpentine. The more conspicuous larger surfaces should be left until the last, so you will be sure the material is working right when you do them. If more than one coat is ap- plied, each coat should be allowed to dry at least forty-eight hours and then sand- papered lightly before applying the next coat. When the varnish-stain treatment is completed, a finishing coating of varnish should be applied. This may be of gloss varnish, either left in full gloss effect or rubbed to a semi-dull finish, or it may be of flat-drying varnish. Varnish is applied in about the same way as enamel, with the cross brushing method described fully in the December, 1928, issue of this magazine, flowing it on with the grain, then brushing across the tiful varnish finish more than dust or grit in the surface, and failure to get a clean finish is, in the great majority of cases, due to the brush, the varnish cup, or the surface not being absolutely clean. Varnish brushes must be kept thoroughly clean clear up to the root ends. Dried skins, and particles of the finishing ma- terial left in the heel of the brush, work their way down, and it is almost impossi- ble to get a brush that has been allowed to get “lousy,” to use the painter’s term, clean enough again to use for varnishing. Varnish (and varnish stain) should al- ways be applied in a room which is just as free from dust as possible, and care should be taken that no dust is raised in the room during and for several hours after appli- cation, until the material has set dustfree. People walking will stir up enough dust to ruin a job. It is also important that varnish be applied in a warm room, that the surface on which it is applied be warm, and that the varnish itself be warm; other-

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d h f yf d or an. hly ied na- ork ssi- ved rm, ng. al- t as uld om pli- ree. lust chat that rm, her- POPULAR wise it will not flow properly and level itself to a smooth, even surface. If var- nish has been kept in a cold room for any length of time, it should be warmed by setting the can in hot water, or by placing it near (but not on) a hot radiator. If possible, varnishing should always be done on a dry day, as it dries very slowly in damp weather, sometimes causing trou- ble and affording a greater opportunity: for dust to settle on the work before it has dried, and also a greater chance for someone to get against the work and spoil it. Windows should be kept closed while applying varnish and until it has set dust- free; then opened, if practicable, except in extreme cold weather, to provide venti- lation and good drying conditions. If varnish from a previously opened can is used, even though it has been kept tightly corked, it will be found that a skin has formed over the top. This should be punctured carefully and the varnish strained through cheesecloth to filter out any small pieces of dried skin. If the var- nish has become too thick to spread easily, it should be thinned with a little pure tur- pentine. In the application of varnish, there are certain defects of workmanship which should be continually guarded against. Skipped places is one of these, and the finisher should keep looking across toward the light, down close to the surface, which will readily show up any missed places. He should also be on the watch out for sags or beads of varnish running down over the work, especially at the corners, and immediately on seeing one pick it up is nots $ shee |! cL with a corner of the brush. Another thing to be constantly watched for is loose hairs shed into the work. These are es- pecially common when new brushes are used, for, no matter how high-grade the brush, there are always a few loose hairs. MECHANICS 507 These should be worked out as much as possible with the fingers, and by dipping the brush in turpentine or in the varnish itself and brushing it out on a clean board or piece of paper. When a hair is shed into the work, it should be poked out with the end of the brush, and the surface then smoothed out. Varnish brushes ought to be kept for use only with varnish, and should be cleaned only with turpentine or benzine (never gasoline). While on the subject of brushes, a word about the kind to use for varnishing is in order. A good-quality 1%-in. chiseled varnish brush will be found very satisfac- tory for the average furniture-finishing requirements. Expert finishers generally prefer what is termed a “flowing” brush, but these are rather high-priced, and good work can be done with a regular varnish brush. It is important, however, that a high-grade brush be used, as one should not expect to do good work with a cheap brush. Get a good brush and keep it in good condition. It is also desirable to have a small 1- in. brush for small surfaces, Decalcomania Trans- fers, Tastefully Se- lected and Applied, Add Much to the Appearance of the Finished Work

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508 POPULAR chair rounds, etc. This may be a regular varnish-brush type, but for fitting rounded surfaces a camel’s-hair brush is preferred by many. For the finest finish, a coating of gloss varnish should be applied, and rubbed, about three or four days after application, with pumicestone and oil. Full directions for producing a rubbed effect, by dipping a pad of rubbing felt or soft cloth first in rubbing oil or sewing-machine oil, then in powdered pumicestone, and rubbing over the surface, were also given in the December issue, MECHANICS turn out satisfactorily, and the surface seem to be blurred or streaked, it can gen- erally be corrected by applying a thin coat of prepared wax (floor wax), and polish- ing briskly with a soft cloth. Many peo- ple, also, are especially fond of a waxed finish, and prefer to wax over a varnished finish to obtain the typical wax sheen, but it should be remembered that a wax finish requires more attention, and must be pol- ished frequently to keep looking well. The other method of finishing—and the easiest one—is to apply one finishing coat of flat-drying var- For the finest rubbed job, two coats, or preferably three coats, of gloss varnish should be applied, rubbing the first coats lightly with No. 00 sandpaper (or for the best possible job, with pumice- stone and water) and the finishing coat with pumice- stone and oil to the desired effect. How- ever, one coat of clear varnish over a coat of varnish stain may be rubbed to a reasonably good job, if care is taken not to rub too much, so as to cut through, especially at the sharp edges. Wipe and examine the surface often to note progress. Another method sometimes employed by home finishers, which will be found very satisfactory for any except the very finest work, is to apply a coat of gloss varnish over the varnish stain, and rub it lightly, after drying three or four days, with fine steel wool (No. 00) wet with linseed oil. This will be found a simpler operation than pumice rubbing, and there will be less chance of the novice rubbing through the finish. Here it might be mentioned that in case rubbing with any material should not nish over the var- nish-stain coat. This closely ap- proximates a rubbed effect, although it has not the depth and richness of the real hand-rubbed finish. When ap- plying flat varnish, it is.important to shake the container immediately before using, as, unlike gloss varnishes, pa‘t of the content of flat varnish ordi- narily settles to the bottom and should be reincorporated with the liquid be- fore using. If desired, a fin- ishing touch may now be added with applied decoration. Transfer patterns (decalcomanias) may be obtained simulating wood inlays, designed espe- cially for use on stain-finished furniture. These are easily applied and impart a note of richness to the piece that is worth while. Stenciling is sometimes used as a last finishing touch, but care must be taken to use designs and colorings that are appropriate to stain-finished wood. @Any old canvas water bag, slit open at the top, makes an ideal creel for carrying fish and will keep them moist and fresh all day. mr

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ut sh to yre ke art of di- the uld ted be- fin- jay ith ion. rns as) ied spe- ure. 1ote orth as a be that d. n at ying resh POPULAR Removing Dents in Soft Wood When working with soft wood or me- dium hardwood, the hammer may occa- sionally slip, making dents on the surface, which, of course, spoil the appearance of the job. To take out such dents pour on a few drops of alcohol and light it. The heat will swell the wood and raise it to the original surface, the alcohol burning out. so quickly that no charring will result— L. B. Robbins, Harwich, Mass. Boring Bar for the Home Lathe The drawing shows a simple boring bar which I made for use on a small lathe in my home workshop. The cutting tool is held securely in a sleeve keyed to a shaft, which is driven by the chuck or the face- plate of the lathe, a dog being used in the latter case. With this arrangement it is necessary for the sleeve to slide length- wise on the shaft so that it can be moved back and forth while revolving. This movement is made possible by the provision of a ball-and-socket joint at the other end of the sleeve, indicated in the upper right- hand detail of the illustration. The joint permits attachment to the tailstock, which is used to feed the tool. The work is acemuate. (7 KEY, & X3X3" wae _ sniaes ean ce SETSCREWS 7§ SCREW a ! ! Ai a Simple Boring-Bar Attachment on a Small Lathe in the Home Workshop mounted on the lathe bed as shown.—Ed. M. Wyland, Rapid City, S. Dak. MECHANICS 509 Raising a Garage Single-Handed with an Auto Jack before Laying Concrete Foundation Raising Garage with Auto Jack When it is desired to raise a garage that is set on posts, in order to put a con- crete foundation under it, an auto jack will be found useful. A number of lengths of 4 by 4-in. stock are obtained, for use as lifting bars, and they are pushed under the sill at right angles to it. A block and plank are set under one end of these and the auto jack under the other. After the jack has raised the bar, a block is pushed under it to hold the load, and then the jack can be used to raise the next bar, a few feet away. Repeat the operation until the whole garage is raised to the de- sired height. The foundation is then laid, and after it has set for several days, the garage can be let down on it by reversing the method. Magnetizing a Pair of Scissors To make it easy to pick up a needle when it falls on the floor, in water, or places that are hard to get at, I have magnetized a pair of scissors. Anyone can do this by merely stroking the scissors in one direction over a pole of an electro- magnet or ordinary steel magnet of suffi- cient strength—Andrew Veng, Philadel- phia, Pa.

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510 POPULAR PLUG DETAIL OF 110-VOLT SWITCH are ones FOR DOOR OPERATION = Electric Lamps in Refrigerator Are Automatically Lighted When Doors Are Opened Electric Light in the Ice Box Our refrigerator is located on the rear porch and the light is so far away that it provides very little illumination for the refrigerator. Two small door switches, which close a circuit when a door to which they are attached is opened, were installed on the refrigerator doors. A lamp was provided in each compartment, and a length of lampcord was used to connect the circuit with a near-by wall plug.—Miss Jane Rider, Washington, IIL. Oiling Auto-Distributor Shaft Distributor shafts on some auto motors receive insufficient oiling, due to the fact that the grease or oil cup located at the top of the distrib- utor shaft is for- gotten. To insure proper lubrication for this part, with- out special atten- tion, the method shown in the illus- tration will be found satisfactory. It eonsists in get- ting the oil supply from the pipe run- ning to the oil Insuring Proper Lubrication on the Distributor Shaft of an Auto Motor MECHANICS gauge on the instrument board. Cut this pipe and install a tee and a needle-valve sight-feed lubricator as indicated, and run a length of copper tubing from the needle valve to the distributor shaft. Adjust- ment of the needle valve controls the amount of oil fed to the shaft, and as long as there is any oil in the crankcase, the distributor shaft will not run dry. The oil should be allowed to pass only in drops. Plastic Paint Made from White Lead Textured walls are now quite popular and there are several high-grade plastic paints on the market for treating plastered walls. It is not generally known, how- ever, that a white-lead plastic paint can be readily made at little cost, which will give entirely satisfactory results. Plastic paint must be thick enough to allow de- signs and figures to be worked in it, should dry hard and quickly enough so that it may be glazed over if desired, and have some oil content to give permanency. It consists of the following ingredients: white lead, 19 lb.; dry whiting, 4 Ib.; flat- ting oil, 1 qt., and drier, 4% gill. The best method of compounding it is to use one- half of the oil to break up the white lead, and mix the other half with the whiting. Then mix the two together and add the drier, which will result in a thick paint, about twice as heavy as the average white- lead paint, which can be applied with a brush. It should be applied heavily. The above quantity will cover about 30 sq. yd. Color can be added to the mixture or it can be applied dry with the brush, giving the desired rough and streaky appearance. As soon as the paint is on the wall, it is ready for the working in of the designs, which may be of va- rious kinds. Ex- pensive tools are not required; a graining comb is handy for some de- signs, and a kitchen spoon is useful for making circular fig- ures. Crumpled pa- per is sometimes used as well as wadded rough cloth for texture designs.

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ar od V- an ill tic —} wi A ry 4 y bp QY All Shop Notes published in 1928, in book form—Fifty Cents—from our Book Department A Ball-Bearing Scrollsaw By W. CLYDE LAMMEY hl TIMES past the writer has made sev- eral attempts to construct a scrollsaw that would be suitable for a wide range of work, and all have been more or less of a CUTTING OUT TABLE failure, owing to the difficulty of making a smooth, easy-running assembly. In every instance, the driving mechanism was faulty and soon went to pieces under the strain of driving even small fine- toothed blades. However, it happened one day, while cleaning the basement, that a discarded pair of roller skates was found, and, after some cogitation, these rusty skates became the nucleus of an idea which in essential is the project described, namely, a ball- bearing scrollsaw. Though lacking in re- finements perhaps, it has been found to equal any of like capacity in practical features. The ball-bearing assemblies in the skate wheels are used in the saw arms and in the pitman and driving wheel, making an easy-running mechanism that may be op- erated at high speed. The skate wheel is used intact in the saw arms and driving wheel, but only the assembly in the pit- man rod, If no discarded skate is available, get four wheels with the regular threaded bolts. These may be obtained at any hardware store where repair parts are carried, Make sure that the wheels are of the \“— CRANK BEARING PITMAN DRIVE WHEEL + —C_.. | —e— -e Cc - HOLDER 7 SAW ARM (ZSROOVE = i. MOUNTING BLADE HOLDER Fis. 511

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POPULAR MECHANICS double ball- race type, as these are more cer- tain to run true and are best suited the purpose. Rip the stock for the arms and the to ing saw as shown in Fig. 1. Chisel a groove of suitable size and depth in the end of the saw arm (in the upper edge of the top arm, the reverse in the lower), bore several slanting holes and chisel out to take the curved portion. Rivet the holder in place, using washers; then fill the groove with plastic wood, and, when dry, sand smooth. A turnbuckle with two fairly heavy screweyes is used to provide a quick means of adjusting the blade tension. The screw- eyes are turned into the wood and a “%g¢- in. rivet put through close to the end, to prevent splitting. Centering 19 in. from this end and 1% in. from the lower. edge in thie upper arm, and the reverse in the upright arm sup- ports from 1-in. oak to the dimensions and form shown in the drawings, and true the edges with the jointing plane. Cut two pieces, 28 — +—— in. long, from 2 by ASSEMBLY, ARM AND PITMAN WHE EL 4-in. stock for the base. Half-lap the ends over the uprights (Fig. 5), taking care to have the shoulders of the halves square. Usea 1 by 4-in. piece, about 9 in. long, to space between the up- rights and for rigidity. Use two hand clamps to hold this assembly square while boring the three %-in. holes for the bolts. Give a liberal application of glue to the joining surfaces and tighten the bolts on washers. If desired, the upright arm sup- ports may extend to the floor to make a floor mounting. After the stock, for the arms has been prepared, the turnbuckle, bearings and blade holders are placed in position. The holders for a pin-end blade are adapted by cutting the frame of a small hand cop- lower, bore a hole for the bearing with an expansion bit, first testing the setting on a piece of waste stock until the skate wheel is a tight driving fit. In driving the wheel to position, use a large nail set on the rim, rather than strik- ing it directly, as this is likely to damage the bearing. 3efore laying the arms aside, obtain a piece of common strap iron (or any other that happens to be adaptable) % by 1 in. and cut from it two pieces, 3 in. long; 7%

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ther in., ; fe POPULAR in. from one end bend at right angles and % in. farther bend again, making an off- set of % in. in each piece. Bore a \%-in. hole through the offset ends and two %e- in. holes in each opposite end. Rivet the pieces to the lower saw arm, one on each _ side and 2 in. from the end taking the blade. These form the upper connection for the pitman. The saw table is best built up from 1-. in. yellow pine in the manner shown above Fig. 1. Cut a piece, 33 in. long, from 1 by 10-in. yellow pine, and rip another, 2% in. wide and 3 ft. 8 in. long, from the same stock. Cut this last in four pieces, two 1 ft. long and two 10 in. long. Square all edges carefully with the plane, and dowel and glue the pieces, two on each side, in such a position as to geta_ |} circle of 8%-in. ra- || dius about the end. Scribe a _ circle about the end, | rounding off where | it meets the center- piece; saw to the outline, and plane and sand smooth. Han- dling the stock will be greatly facilitated if the table is given two coats of thin shel- lac and rubbed smooth. This makes a hard surface that is well worth the extra labor, The pitman drive-wheel assembly con- sists of three parts, A, B and C, Fig. 1. The drive wheel A carries the bearing and is made to run in a recess in the plate B, MECHANICS . +513 | DETAIL OF TABLE Fia.4 UPRIGHTS ~, ||;CONSTRUCTION OF BASE Fic.5 which in turn is secured to the sup- port C. This method of construction has been found to over- come the tendency to run out of true owing to the short bearing surface of the skate wheel. For the driver, saw two pieces of hardwood to 6-in. diameter, each 4% in. thick, and glue together with the grain running at right angles. Use screws to save the wait for the glue to harden. Turn out on the faceplate to 5%4-in. diam- eter and true the outer face carefully. Cut a groove fora %-in. round belt, having the center of the groove about % in. from the inner face of the wheel, so that the belt will run directly over the bearing. Sink a recess centered on the face of the wheel, to take in the skate bearing flush with the surface. Use the greatest care in this operation to have the bearing fit tightly. Sand the wheel smooth. In the standard skate wheel with iron tread, there is a series of small holes through the inner face just below the tread. Before driving the bearing in place, bore several of these holes through both sides of the rim and countersink for screws. Center a %-in. hole in the recess for the bolt head, and bore through the wood. Take care to have it true. Drive

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514. POPULAR the bearing in place and tighten with screws. As close to the tread as possible (in the metal), bore a 4%-in. hole for the bolt holding the pitman bearing. This will give a stroke of approximately 1% in. The position and relation of the com- ponent parts will be readily seen from the drawings and photos. Turn the plate B from a single disk of hardwood to exactly 6-in. diameter, and, beginning a trifle less than 4% in. from the edge, recess the surface %¢ in.; % in. from the center, sink a deeper ring to accom- modate the head of the pitman bolt. Drive four ordinary thumbtacks into the inner surface of the plate as shown. Mark the outline of this disk on a piece of hard- wood, 1 by 6 by 9% in. Saw a three- quarter circle to the line and bring the edges around in a curve as shown in the assembly, Fig. 2. Tighten a skate wheel in the vise and, with a hacksaw, cut through the tread down to the cones that form the inner half of the ball races, and pry the rim apart. This will release the bearing. Us- ing one of the threaded bolts, with a thin washer next to the wood, tighten the pit- man bearing in place. Centering % in. over this bearing and in approximately the same arc as the wheel rim, bore six ¥%-in. holes and chisel out the waste as in a mortise. On the average, this will re- move sufficient weight to counterbalance the wheel. The pitman is made from a piece of ma- ple, planed to % in. in thickness, 13% in. in width, and 4% in. in length, into one end of which is let a 3-in. length of %-in. iron. Make two saw kerfs as closely to- gether as possible MECHANICS a clamp and bore a hole for a small stove bolt, to clamp the loose piece. Assemble the arms in the frame first, using %-in. bolts. Punch washers from tin, and shim the bearings until the saw arms move freely when the bolts are tight- ened. Bolt the pitman-wheel assembly together, using thin washers between the plate and the wheel, until it turns easily without binding against the heads of the thumbtacks. Bolt in place as shown in Fig. 2, and connect the upper end of the pitman to the arm, using a small bolt. If the parts have been carefully made, this assembly will be found to run with re- markable ease and smoothness, the ball bearing adding immeasurably to the elimi- nation of friction. Center a %-in. hole in the circular end of the table for the blade. Raise the arms to the highest point in the stroke, measure, and allow about % in. for clearance. Mark this measurement on the arm supports, and at this height fasten a small piece with screws to support the rear of the table. Measuring an equal height, cut two pieces from 2 by 2-in. stock and secure to the ends of the base with lag screws. Be sure that the pieces are even at the top. Lay the table in place, insert a blade in the holders and test with the square. If the table is square with the blade, lock it down with screws. Mount a % or 4%-hp. motor just back of the pitman drive wheel and use a pulley of l-in. diameter on the motor. The saw will make about 900 strokes per minute with a 1,750 r.p.m. motor and with a coarse-toothed blade will do clean and speedy sawing. The blade continually recedes from the in one end of the wood to a depth of 14 in. and rivet the iron in place in this slot. Bore a %4-in. hole through the outer end of the iron. Center a %- in. hole 134 in. from the end in the wood, and saw down tan- SNe RK DOWN ee bo ~ frame MATERIAL LIST pieces, 2 by 4 by 28 in., piece, 1 by 10 by 33 in., yellow pine. piece, 1 by 2% by 44 in., yellow pine. pieces, 1 by 3 by 36 in., oak. pieces, 1 by 4 by 24 in., oak. pieces, 1 by 6 in. square, birch or maple. piece, 1 by 6% in. square, yellow pine. piece, 1 by 6 by 9% in., oak. pieces, 2 by 2 by 16 in., yellow pine. standard roller-skate wheels with iron treads and threaded bolts and nuts. hand scrolisaw with 6-in. blade and 5-in. work on the up- stroke, the advan- tage of which will at once be apparent in use, as this ac- tion precludes the annoying tendency to jerk the work upward. In ma- chines with a blade moving straight up yellow pine. gent to the circle, removing the piece as shown (Fig. 1). Slip the open end over the pitman bearing and insert the short piece. Hold in place with and down, it is nec- essary to fit some kind of “foot” that will hold the work down when the blade is on the upstroke. ~~ — a be h: th m gin hin in j 2 by Wit! gas

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all ni- nd ms ire, irk ind ‘ith ble. ces the ure Lay the the c it k of y of saw nute ha and sally the up- van- will rent ; ac- the lency work ma- blade it up nec- t will is on POPULAR One Way to Save Gasoline A substantial saving of gasoline can be made by anyone having a car equipped with a vacuum windshield wiper which has adash control. Before starting on a drive of any distance, disconnect the small hose connection on the wiper. After the car is started, turn on the dash control, which ordinarily would cause the wiper to -op- erate. This procedure supplies the gas mixture with more air, thus thinning it and effecting a saving of gas. In some actual tests with a Chevrolet coach of the 1928 model, I averaged better than 30 miles per gallon. This idea cannot be used when the wiper control is built into the wiper, as, in this case, the amount of air entering the inlet manifold cannot be regulated.—H. L. Braly, Shamrock, Tex. Flush Handle for Trapdoor In a manufacturing plant having a num- ber of steel trapdoors, cheap, flush door handles were made and found as good as the commercial articles. Each handle is made from a piece of round stock, bent to a U-shape and threaded at both ends for nuts. The holes in the door for the ends should be a trifle larger than the diameter of the handle, and the portion of the door between the holes is grooved so that the handle will drop flush with the surface when the door is closed. It can readily be pulled out to open the door.—G.A. Luers, Washington, D.C. -- RECESS Homemade Engine-Driven Ice Cutter Any farmer who wishes to have an en- gine-driven ice cutter can easily make it himself as there is no difficulty involved in its construction. The sled is made of 2 by 6-in. stock, firmly braced and equipped with a handle for pushing. A stationary gas engine is mounted on the sled and a MECHANICS 515 Harvesting Ice with a Simply Constructed Engine- Driven Cutter That Can Be Made at Home suitable 2 by 6-in. frame, to hold a circular ice-cutting saw, is pivoted to the front end of the sled as shown, a lever being pro- vided to permit raising or lowering the saw. The saw shait is fitted with a pulley in line with the pulley of the engine, to which it is belted—Clay L. Gorrell, Be- lair, Md. Multiple-Scriber Surface Gauge When castings are to be laid out in lots, as they generally are in any large plant, the multiple-scriber surface gauge will be found a valuable aid. Once the scribers are set to the correct meas- urements, the entire lot of castings can be laid out without dis- turbing the setting of the gauge. This simple device will help in- crease pro- duction and will eliminate many errors in laying out the work.—C. Kugler, Philadelphia, Pa.

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Wood Joints for the Amateur PART II HEN the amateur, after watching the skillful craftsman make and fit a joint, starts in to do the job himself, he finds, to his surprise, that the thing is not quite so simple as it looked. In spite of the most careful work with the tools, the joint is not exactly right when it is fin- ished. The fact is that there are many little things done by the craftsman while he is making a joint which go unobserved by the amateur, yet are essential to the success of the work. In addition to this, the professional, by long practice, has ac- quired a degree of skill in handling his tools that the amateur cannot hope to du- plicate for some time, and consequently he must modify his methods to make up for his lack of facility in tool handling. Let us take the making of a cross-lap joint for example. The first step is to square up a face side and edge on each piece, and mark them (see Fig. 1). After measuring and marking the position and width of the joint on one, lay the pieces side by side, as shown, and square the marks, with the knife, across both faces. Turn them edgewise, keep- 516 ing them together, and square the marks across the face edges. Now square across the other edge, singly, keeping the stock of the square against the face side. Set a marking gauge to half the thickness of the stock, and gauge the depth of the re- cesses, gauging always from the face sides. Now comes a little trick that the ama- teur will find of use. Take a chisel, and, slanting it toward the waste, as shown in Fig. 1, cut a little groove right up to the line on either side. If the knife marks have been made fairly deep, severing the fibers of the wood, the chips will come away clearly, and the groove will make it possible to start the saw square across the work, and just inside the line. Another tip is to start the saw as shown in the lower drawing in Fig. 1, holding it slant- ing, and sawing down on one side until the saw teeth just touch the line marking LINES SQUARED ON . FACE SIDES AND EDGES STARTING SAW

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rks Oss ck Set of les. na- nd, 1 in the irks the yme e it cher the ant- intil cing POPULAR MECHANiCS 517 the depth of the recess. The saw can then either be brought up gradually until it is horizontal and the cut continued, or else the work may be reversed, and a similar slanting cut made from the other edge; if this is done, the two saw kerfs will keep the saw straight, and it will become easy to cut down horizontally and keep the cut square, The next thing is the paring out of the waste. Some workmen like to do this sort of paring horizontally, as shown in the photo accompanying Fig. 1; others, again, prefer to pare vertically, as shown below Fig. 2. The amateur will probably find the first method the easier. With either method, the procedure is the same. Sharpen the chisel; good work cannot be done with a dull tool. Pare away the wood on a slant at one saw kerf, as at A, Fig. 2, then take a similar cut at the other kerf, and next cut off the top of the “hill”; these cuts are numbered 1, 2 and 3 at A, Fig. 2. If the chisel is thrust all the way across the work, from one side only, the SK IS S wood on the opposite side of the cut is apt to be torn off, as shown at B, and, to avoid this, the wood should be cut away partly from each side. Many workmen prefer to pare away the wood as shown at C, slanting the chisel upward, and paring halfway from each side, so that the cuts end in the center; there is then no danger of wood being broken off at either edge. When sawing an end half-lap, or any similar, joint, mark off as described be- fore, then fasten the piece endwise in the vise, and, starting the saw as in Fig. 3, saw down along the depth line until the saw teeth touch the line marking the length of the lap. Turn the work around in the vise, and saw similarly on the other side. Finally hold the saw horizontally and cut down the center. It will be found a great deal easier to keep the saw to the depth line by using this method than by sawing straight with the saw down hori- zontal while trying to keep the saw square in two directions. Of course, with either method, one must watch the line on the end of the work as well as that on the side, but it is decidedly easier by the first method than by the second. With normal care, using this method, it will be found unnecessary to employ a chisel to make the parts of the joint fit properly.

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518 POPULAR Circular Passage in Fence Consists of an Iron Wagon Rim Wired in Place Securely Circular Passage in Fence When it is necessary to cut an opening in a fence as a passage for hogs, sheep or calves, you will find the idea indicated in the illustration of exceptional merit, as it makes a neat job and does not cause the fence to sag, as often happens when the fence is cut vertically and two posts are set up a few feet apart. Get the rim of a wagon wheel and cut a circular hole in the fence so much smaller than the wheel that the wire can be turned around the rim, and the ends twisted securely to hold it in place and to prevent scratching the animals.—Luther Strosnider, Onaga, Kan. Cover Attached to Clip Aids Mechanic While working on an auto, or other piece of machinery, I have frequently dropped small parts on the floor and spent quite a bit of time in recovering them. I now use a small tin-can cover, attached se- } curelytoa TIN-CAN COVER/ strong spring clip as shown in the drawing. The con- tainer thus made can be clipped to any convenient part of the machine where it _ Weal a ay MECHANICS is handy for the worker to reach, and will hold small parts without risk of losing them.—Ross J. Plaisted, Cleveland, Ohio. Safety Hook on Well Digger’s Rope When digging wells, the bucket used for hauling up the earth sometimes slips off the hook on the end of the rope and may cause serious injury to the worker in the pit. To avoid this danger, a Ne- braska well digger provided a safety hook as shown in the illustration. It is really a large snap hook from which the bucket, full or empty, cannot be dislodged when there is a slack in the rope, and the snap can only be opened intentionally. Hence the man in the pit can work in safety without worrying about the bucket over his head. Ifa snap hook of this kind cannot be obtained, fasten a strip of spring steel to the hook, which is done by drilling and tapping the hook and spring for screws to hold the latter securely in place on the shank of the hook. It may be necessary to re- move the temper from the end of the spring where the screw holes are to be drilled, then re- tempering it. The spring must be ar- ranged so that it closes the hook when pressure on it is released.—Frank S. Reynolds, Fort Morgan, Colo. Taking Care of Your Oilstone A good oilstone, whether it is natural or of the artificial variety, commands a good price and is therefore worth proper care. The surface of the stone must be kept uniformly flat and even, and a glazed condition must be prevented. To let an oilstone become dry will harden it. It should be clean and moist, and, if kept in a dry place, a few drops of fresh, clean oil should be left on the surface, to pre- vent glazing. The fluid floats off the par- ticles of steel removed from the tool. Ii no oil or water is used, these will become

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“pt ay / ral > a per be zed an It ept ean re- yar- li yme

POPULAR lodged in the pores of the stone, greatly impairing its efficiency. All coarse- grained natural stones should be used with plenty of water, while medium and fine- grained natural stones, and all artificial stones, should be used with oil. In order to prevent further glazing of a stone, that is already more or less dirty, wipe the sur- face clean after using it. If this is not done, the oil soaks into the stone and car- ries with it the particles of steel. A glazed stone can usually be restored by a thorough cleaning with gasoline or am- monia. If this does not entirely remedy the condition, the stone can be scoured with loose emery or a sandpaper block. A new oilstone should be soaked in oil for several days before it is used. Field Toolbox for the Farm To eliminate the trouble of taking farm tools home after each day’s work, because they cannot be left outdoors in wet weather or during the winter months, it is a great convenience to have a portable box of sufficient size to accommodate a large saw besides other tools. When working for several days on one spot, the toolbox is brought there and left until the work is finished. The box is built to stand on end, as shown in the photo, in- stead of being laid on the ground where it would soon be snowed under. The hinged door is fitted with a hasp and pad- lock, to minimize the risk of having the tools stolen. The outside is covered with roofing paper.—J. R. Koontz, Bremen, Ind,

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Portable Field Toolbox for the Farmer Keeps Tools on the Job and Protects Them against Weather MECHANICS 519

Window-Raising Mechanism Taken from Auto Door Makes Good Bottle Tipper Handy Tipper for Distilled-Water Bottles The window-raising apparatus from an old auto door, built up on a wooden box as shown in the photo, has been used to make a convenient device for holding and tipping 10-gal. distilled-water bottles for filling storage batteries. Turning the crank tilts the bottle to any degree neces- sary for filling a small container, without the risk of spilling any water. The crank mechanism is arranged on a. strap-iron frame, which is screwed to the box and supports the bottle. Repair for Door-Lock Keyhole Frequently a good door lock is discarded because the keyhole is worn to an oval shape, which allows the key to drop out of its correct working position. An easy way to remedy this trouble is to obtain two thin washers, with holes the same size as the shank of the key, file a slot in each washer from the edge to the hole, the slot being of sufficient width to take the web of the key. Clean and tin one surface of each washer and sweat them to the plates of the lock.—John Bell, Alton, Eng. @A guard for a circular saw can be made from a discarded auto-brake drum.

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in —- coon i 7] j 4 =m ‘ } iy * Ee 6 Beet tot Bay 2-8 tos he: ot 1 bs ‘ 7" a t . yiay= g i 2 H Kt Be) ‘ Ba ¥ baie - ‘ i fen Ih | = derside edges, 4 by % in., on sides Siw w and front, to receive a 34 by 13s- «© in. strip glued and nailed in for a { nosing. This, however, extends ¥ around the left side and front only. ending % in. from the right side. Miter the corner joint. Make the back 2 ft. 8 in. by 2 ft. 5% in. Notch the left upper corner 2% by 14 in., and cuta % by l-in. rabbet in the bottom of the -! notch. The right upper corner is rabbeted 34 by 1% in., % in. deep. (See Fig. 4.) The inner face is then dadoed 3% in. wide and % in. deep, to take the back edges of the left partition, and the left rear and bottom shelves. The parti- tion groove is 1 ft. 2% in. from the | left edge of the back, and the bot- : e ' 4 bd oy ik a Elevations of the base are shown ms me in Figs. 1 and 2, and details in Fig. u 3. The top is a rectangle, 2 ft. 654 + in. by 1 ft. 674 in. Rabbet the un- PART I § ARGE capacity and economical use of space are features of the modern- istic bookcase described in this article. It is 5 ft. 11 in. high, 2 ft. 8 in. wide and 1 ft. 9 in. deep. Not only is it an interesting piece complete, but the base, if desired, can be used alone as a stand. Since solid stock, through shrinkage and warping, would rack the case apart in a few months, five-ply 34-in. material should be used. There are many joints dependent for their appearance on the squareness of the ends of the various parts, so the use of a template in the form of a square block held against the saw blade is advised. 520 tom dado is 7 in. above the lower edge. The upper shelf dado is 10% in. above the lower. The laying out and cutting of the dadoes are somewhat tedious and exacting, but there are a few tricks that simplify the labor. First, square the piece accurately, and mark an edge and side from which to measure and square. Next, lay out a stick with the necessary dimensions, mark- ing the points with a knife (not a pencil). Make the end marks % in. or more from the ends of the stick. By using this as a pattern, all pieces belonging to the same assembly can be laid out. Mark the long dadoes with a straight- edge, scoring the lines with a knife point. Clamp a straight strip of wood to the work, the edge centering on the line, and

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wn ‘ig. 5% 1n- des - ra nds nly, ide. y 2 per i the r is eep. 2 is 4 Ss of rear urti- the bot- wer . in. does but the tely, h to ut a vark- cil). from is as same ight- oint. , the and , MODERN BOOKCASE | E.M.Love guide the saw against it, hold- ing the blade with the thumb, or a piece of wood. If the dado is across the grain, start with a crosscut saw. When the surface is cut through, the use of a rip- saw will expedite matters, In- stead of a single strip of wood clamped to the work, a guide consisting of two strips bolted at the ends can be used. This is slipped in place with one strip above and the other below and cinched tight with bolts. Chisel the waste wood out to as uniform a depth as possible. This can easily be done with a router, but if one is not available, the depth can be fairly accurately regulated by means of a nail driven squarely through a block, the point projecting 4% in. With this tool scratch the high spots, leaving only shreds of wood for the chisel to pare. The left upper shelf is 11% in. by 1 ft. 2%4 in. The bottom shelf of the lower section assembly is in one piece, 2 ft. 8 in. by 1 ft. 8 in. Near the center, the front edge projects 4 in. for a width of 8 in., i ft. 21%4 in. from the left edge, bringing that part flush with the front of the cabinet when it is put to- gether. Cut the left side partition 1 ft. 2% in. by 1 ft. 9% in. To allow for the top nosing, notch the left upper corner 2% by 1% in. Dado the front face full width, 7% in. above the lower edge, and the back face 10%4 in. above the lower edge. The left front shelf is 814 in. by 1 ft. 2% in. The left center partition is 1 ft. 8% in. by 1 ft. 9 in. A vertical dado, % by % in., is made on the left side, 814 in. from the front edge, and one on the right face, 11% in. from the front. The lower dado on the left is 7% in. above the lower edge, and the other is 10% in., while the dado on the right is 1134 in. from the lower edge. The right center partition is 11% in. by 1 ft. 9 in., with a dado full width of the left face, 11% in. from the lower edge. The right side partition is 1 ft. 6 in. by 1 ft. 914 in., and extends back to the left center partition. It has a vertical dado on the front face, 10% in. from the front edge, into which the back edge of the right center partition fits. $21

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§22 POPULAR Make the front center shelf 8% by 11% in. The left front side is 1 ft. 3 in. by 2 ft. 234 in. Rabbet the upper left corner ¥% by 1 in. by 2% in. on the inner face, and notch the right upper corner %4 by 3% in. Rabbet the right edge inside, 4 by % in., and cut a dado across the inside, 12% in. below the upper edge, and another 7% in. below this. The rabbet must be notched 4 by % in., to fit the center shelves. The right front side is 10% in. by 2 ft. 234 in., with the left edge rabbeted Y% by % in. The lower dado on the inner face matches that on the other front piece, and the upper groove is 934 in, from the top. Before attempting to assemble the sec- tion, try all joints separately. They should MECHANICS go together snugly, yet without need of undue pressure, since it is possible to use clamps very little. If a shelf is too thick to go into the dado, take a shaving or two off the lower side. If the joint will not close tightly, a shaving or chip in the groove may be to blame, or the dado corners may be so rounded that they in- terfere. Much final cleaning up can be avoided if the parts are sponged with warm water to raise the grain before as- sembling. When dry, sand smooth. In putting together, smear glue on both meeting members. The following is a good order to follow: Lay the back on the floor; enter first the bottom shelf, and then the small upper shelf and the leit center partition. Bring these joints up Peng —l— eit \\\ V7 fie] ff = iH) f | ~ H\ | \\ \A\\ } ‘| | i\\ if } ify BE tity \ \/ } > 3” i , | Br iii fj t } Lijit » at +s —4 ell | ———— ---2 \ 5 om 1 i rah ee ~s— - - | Lh t= dali i | | ‘ PETER ETE 8 oh hat ah 4-4-+4-—-4) o ’ dees Fae ‘ ) a |) - ba 16z i wo \ REReAatees mit I Ly jh i [noe ee j PY i o ,& 4. 4 \ / ; % a WT 1 | tee eee \g Mt i-f-—-4 Seeheees ITIMOOTT 1 i ae ee Piddha dl 3 © Ni 1 PY cag ser oe es | is = ee at | \} my “ Wels UM TI rae el | - Toh a a SEER TIC SBAT ab oe ee { f = \ 1} 1 bid sbidd ee Ma ¢ bt s 9) 4 a a1, 14 '§ ' pe ae ti | A ale a ae haat we a we - ite a ——1 =a : 2i- PJ it “oO ea . 4 ps ar |: i ‘ 1 \ A ¢ ° =a | “ 2 q 3" \ ” i Oz — 8 ——>}, if | wis --- / 3 — ‘ at i ——- ait tie vg 7) = ————— | eee 4 Fic.2

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"4 4 cU POPULAR MECHANICS 523

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524 POPULAR tight, hailing through back and partition into the shelf edges with six-penny finish nails. Next add the left partition and the right side partition, following with the small center shelf, nailing all solidly to each other. The partitions merely butt against the lower shelf, so their distance from the back and sides must be carefully checked. Put in the right side shelf, and nail and glue on the fronts. The left top is joined with a rail, 1 by 2% in. by 1 ft. 8 in., and the right with a % by 1%-in. rail placed vertically in the rabbets provided. Fit the top next. The assembly should be rigid and square by this time. If it is seriously out of square, see if the joints have sprung open. Notch the right upper rail end, mak- ing it flush with the top nosing. Puta l ‘by 1 by 7-in. rail at the top of the front opening, clean off all glue squeezed out of the joints, and fill the nail holes with plastic wood. The base is put on in two members. The upper is a 3% by 2%-in. strip mitered MECHANICS the left side, cutting the piece a little longer than necessary and mitering the front end. Nailin place. Fit the mitered end of the front strip to that already on, and tack it up, so that the length can be accurately marked. Then cut the other end and glue and nail this front strip to the cabinet. The piece on the right side is fitted in the same way. The ends pro- jecting beyond the back are sawed off. In the same way add the heavier lower member, a piece 54 by 5% in. The lower edge should be backed with blocks tacked to the front pieces and the back edges. Worn Shackles Cause Backlash in Auto When searching for the cause of backlash and knocking in the Ford rear axle, do not neglect to examine the rear- spring shackles, since around the case, the upper edge being flush with the lower side of the bottom shelf. To give it backing, glue and nail a wooden cleat under the shelf. Begin at these, when worn, allow the whole axle to move forward and back- ward as the speed changes. The ball joint on the front end of the drive-shaft tube also wears and adds to the knocking.

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the ‘he be ces se for and ord lect ear- ince low ack- oint ‘ube POPULAR Preparing Concrete Lintels for Trim There is often more or less trouble in the building of brick or hollow-tile walls where solid concrete lintels are used to attach inside trim. The drilling of holes in the concrete and setting in of plugs to hold the nails takes much time and is not entirely satisfactory. The use of solid blocks, placed at intervals on the inside. of the form, has been tried, to the regret of the builder, for the wood expands or contracts, and in some cases cracks the concrete. The problem was solved by cutting laths into 4-in. pieces, then fitting a strip of composition roofing between two pieces of lath and tacking them to- gether with small nails. The roofing ma- terial, being pliable, allows for the con- traction and expansion of the wood and keeps the concrete from cracking. These pieces are tacked on the inside of the form, about 18 in. apart, so that, when the forms are removed, the pieces will be left imbedded in the concrete lintel. Be- fore the plastering is done, the frames should be marked to show the position of the blocks, This method has been used successfully in lintels from 4 to 9 ft. long, and not only were time and money saved, but the lath and felt blocks seem to grip the nails that hold the trim much better and tighter than plugs or wood blocks. Wedge Tool Centers Reamer When it is necessary to hand-ream two bushings in line, the illustrated jig for cen- tering the tool will be found useful. It consists of six steel wedges of the shape shown, drilled and slipped on a key ring. They are spaced evenly on the latter, and copper wire is wrapped around the ring between the wedges to keep them in position. When reaming the spindle bushings of automobiles, the lower one is reamed out first, using the centering tool as indicated. —Dick Cole, Los Angeles, California, WRAPPING OF COPPER WIRE TO SPACE WEDGES * 2 THICK Centering Tool Which Insures Perfect Alinement of Holes Reamed in Spindle Bushings MECHANICS 525 . Weighting End of Saw Blade with Lead Disks Makes It Cut Faster Weighted Saw Cuts Faster In cutting logs, which I do with a 3%4- ft. saw, I found that lead disks, weighing about ¥% lb. and fastened to the end of the blade, as shown, made the saw cut faster. The disks are held on the blade by means of a bolt and nut. Weighted in this way, the saw cuts about one-third faster than it did before, and without any more effort. —Sam Weidman, Lowell, Wash. Permanent Linotype Line Gauge Having had quite a bit of trouble in keeping a line gauge available for imme- diate use on the linotype machine, I duplicated the gauge graduations on the fulcrum bar. The gradua- tions were laid out carefully by means of a pair of dividers, and the lines were made with a knife- edge file. Numbers were stamped with a steel punch.—Jas. H. Rodgers, To- ronto, Can.

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526 POPULAR MECHANICS

This Remote Control for Shutting Off Windmill on a Nebraska Farm Has Proved Successful Simple Homemade Arrangement for Remote Control of Windmill On a Nebraska farm, the windmill was erected quite a distance from the farm buildings in order to avoid a stratum of hard rock. This location was, of course, rather inconvenient, but the trouble was partly overcome by providing a control by which the windmill could be shut off from a position near the house. A length of heavy galvanized-iron wire was run from the lower end of the shut-off handle at the mill, over one pulley mounted on the ma- chinery-shed roof, and another at the top of a 10-ft. post, to a 2 by 4-in. lever pivoted near the bottom of the post as shown. This arrangement has given satisfactory service for two years, and in that time has required no repair—Dale R. Van Horn, Lincoln, Nebr. Scrapers on Busses Eliminate Ruts Several times during last winter, com- plaints were made to the Canadian gov- ernment that the interurban busses cut deep ruts in the ice and snow on the coun- try roads. After trying out several ideas, a mechanic suggested attaching a heavy piece of angle steel by means of two lengths of chain to the rear of each bus. The chains were attached to the chassis by clevises and were sufficiently long

to prevent the angle steel from getting caught under the rear wheels when the bus was backed up. Hooks were attached to the rear bumper to sling the bar up out of the way when not needed. After a whole season’s use, it has been found that the bars removed nearly every rut in the roads. In fact, the appliance was found so successful that it has been made part of the winter equipment of several bus lines.

Grinding a Sphere A novel method of grinding a sphere on the end of a shaft, de- vised in our shop, is illustrated in the drawing. A tool grinder was used for the purpose, the work being rotated on its surface by means of an improvised jig as shown. The jig consisted of a lathe chuck driven by a small motor, both being mounted on a wooden base, which was pivoted at a point directly beneath the center of the ball to be ground. The shaft on the end of which the ball was to be ground, was first turned down in the lathe to the proper size, and was then set in the chuck of the jig. By rotating the base with a handle provided for the purpose, the end was ground to a perfect spkere—C. Kugler, Philadelphia, Pa.

Tie a. Novel Method of Grinding a Sphere on the End of a Driving Shaft

AA< & ey

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‘as by of a = ~ 2 SSS ‘Scientifically de- SSS ce = Exo Desin for Newlyweds NEWLYWEDS planning a stepping stone to home ownership, and others trying to make a small amount of money buy a large amount of comfort, service and convenience in a small house, will be interested in this tabloid plan. Two thousand dollars should build this miniature English cottage under average conditions, according to estimates by the designer. That’s a cost so low you may wonder if the house can possibly contain more than “standing room only.” Studying the plan will show how cost has been cut. Compressed into © Popular Mechanics Plan 4-G-30 being that you have it in a detached home of your own on ground level and at the surprisingly low rent of around $25 per month under normal conditions. In a city skyscraper apartment, you might have to pay the landlord anywhere from $75 to $175 for the same service up fifteen or twenty floors in the air. If this appears too grand and glorious a picture for renters or raises high hopes in the hearts of cliff dwellers, then take the time to inspect the plan and see how ingeniously the designer has clipped cor- ners, saved space and used every device space hardly larger than a two-car ga- rage, there is all the efficiency, time and labor-saving equip- ment equivalent to the latest type of signed city apart- ment, the difference A NEW SERVICE To help our readers get started on one of life’s most glorious experiences—building and owning a home—Popular Mechanics Magazine will sup- ply readers a one-sheet blueprint of the house here illustrated for $2. This blueprint does away with the necessity of first purchasing a com- plete set of plans to find out whether you can afford to build. It contains floor plans, eleva- tions, a section, detail, size of joists, studs, etc., and also a brief specification. tradesmen and dealers for building estimates. possible to “split pennies” and pull the cost down to considerably less than the average cost of the average house in more than sixty principal cities, which, ac- cording to statistics, is $3,750. Submit it to $27

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POPULAR MECHANICS LIVING ROOM 11-0" x 19°-0” FIRST FLOOR PLAN STORAGE CHAMBER 12-0"x 10°09” SECOND FLOOR PLAN Here is how costs have been lowered. There is no base- ment. This means a saving of $300 to $500. A breakfast alcove replaces the customary dining room, Here’s an- There is a cash in-} vestment of $3,000." This sum of money / put into six-per- cent income-pro-} ducing securities would yield you $180 per year. This amount is properly ¥ other $500 to $700 charged to yourself saved. A concealed, or closet-type, bed in the living room not only provides complete bungalow service on the lower as rent, In addition, there are taxes, up- keep, insurance, de- preciation, etc. Aj fair average in most communities would floor, but clips off $500 to $1,000 which wall-bed makers say is the cost for an extra bedroom. Wallboard with plastic-paint finish, or, in fact, any of the rigid forms of board insulation nailed directly onto the studs, gives you satisfactory interior finish and three operations at little more than one price. You not only get a substitute for lath and plaster, but insulation at the same time, and also a decided saving in labor. Stock kitchen fixtures, linoleum floors and fiber tile for bathroom walls, replac- ing more costly ceramic tiles, save still more money. Simple but attractive bath- room fixtures and inexpensive stained-fir trim complete the interior equipment. Savings like these may net you a total of trom $1,800 to $2,000, possibly more. Getting back to how rent money may buy this home, suppose your lot cost $500. To be conservative, let us say the house, under average conditions, will cost $2,500. be $130 per year t@ cover these items. You have therefore @ total yearly expense of $310, or a month rental charge of $25 in round numbers. | No doubt you can finance a little housé like this through local building-and-loam associations. A werd or two about building costs} they vary with localities, choice of m terials, labor, etc. Recent figures show that a $5,500 house in Chicago costs le than $3,000 in St. Louis. In some com munities costs may be lower than the figures; in others, somewhat higher. EDITOR’S NOTE: Popular Mechanics Maga- zine has prepared a new plan book, “Twenty Popular Low Cost Homes and Ten Command- © me..ts for Home Builders.” Thes> are select homes and show labor, space and time-saving ideas. They are $5,000 homes and less. Send 10 cents in stamps to cover postage. Address Building Editor. ‘

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in- ,000. yney er- rT O- ties you his erly rself tion, up- de- A nost ould ir tom re ae ithily rs. ousé loatl Sts; ma shows less con hesé