Popular Mechanics 1929-10: Vol 52 Iss 4

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1 POPULAR CHANICS MAGAZINES$ 1328 WRITTEN SO YOU CAN UNDERSTAND iT q ' . er a, bad a . 4 , Mi, ' ¥. ' ‘ % g i ; fs * a \ 4 3 wt F \ > ¥ (Pn, = \ Alig , Sam j i SEE PAGE 573

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NEWS for the owners of Hupmobile Auburn 8 Graham-Paige . Buick We have proved in thousands of miles of test driving on highways and the Atlantic City Speed- way, and in hundreds of laboratory tests, that the New Mobiloil “BB” gives the greatest summer as protection and power with the lowest oil con- sumption to Buick (1929, 1928, 1927 models), Nash (Advanced and Special Six 1929, 1928, 1927 models), Hupmobile (All 1929 and 1928 models), Graham-Paige (All 1929 and 1928 models), and Auburn 8’s (1929, 1928, 1927 models), If you own one of these cars remember to ask for Mobiloil “BB.” The price is 35¢ a quart, and there is always a Mobiloil dealer nearby. VACUUM OIL COMPANY Makers of high-quality lubricants for all types of machinery th Ne€w in Mobiloil-s»- i@ ~ -— poe @& cot OS ad See: Oe ee ae ee Se

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pst d. er 29 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 In Unieed States and its possesion, aloo Canada, Cubs, and Menico, per yea, anaes - $2.50 To all other countries in the Postal Union - - + 3.00 All subscriptions are discontinued at expiration. Seialeabt ia die sialiled cis nie enalesih: Entered as Second Class Matter Sept. 15, 1903, at the Post Office at Chicago, Illinois, under Act of March 3rd, 1879. Entered as Second Clas= Matter at the Post Office Department, Canada. Published monthly by POPULAR MECHANICS CO, Copyright,1929, by Popular Mechanics Co. Copyright in Australia. Copyright in France

Vol. 52 Contents for October, 1929 No. 4 Special Features Gliding on the Wings of the Wind ................ BEB jap io rien a IS a. cap secacccesesuneun. i TT ee ee nnn anne ee on nqiddihie Souk eawieth Martens ee Flying an Air Liner ........ SAIN METY abit: Ge Abhi wan stad inhi el On the Trail of Poison Mysteries ............... FT Pe ee pF 594 A Thunderbolt Factory................ o>, Soe Ce ee I Co So. enn cukaceessen bn oh bho the Gighudenan’ 605 Wings for the Fishing Fleet ..... A ee a CS ak a: oe. <n The Mystery of Stonehenge ...............................0000. pariTe ... 618 Winged Kings of a Bird Empire ..................0....0........ ti “Blacklight” Spots Planes............. is «in ak alin we eames Tee . 633 Makiaw Crows Jewels for TEOUsee .... 8.8... cee ck ccc cee sceewass 643 Agricultural Implements—hay drier removes moisture Automobiles, Driving—punching bag for autoists .... 604 in forty seconds .......... 635 Automobiles, Fuel—waste from autos filtered for oil Agriculture burner ... pad l bbe ss dese dened ante 642 imported peas improve soil .. 545 Aviation meadow mice destroy crops .......-. ai .. 607 record breakers of the air age .................. 562 pheasants kill crop pests ...... , .. 603 CR SD abc ask «cn stnnds cae ve’s 603 Airplanes wind direction indicated by landing- field lights .. 636 all-metal amphibian to cruise long distances .... 630 Bank—uses vending machine to attract savers ...... 603 detachable cabin for safety and privacy ......... 646 Barbecue—automatic roaster saves meat 576 glider fitted with pontoons .. .. 642 Blindness—mathematics taught blind by touch system 647 maze of controls in cockpit of Australian plane .. $53 Boats and Boating—self-dumping scow ........... 560 model plane has parachute jumpers ae Books—aluminum covers for 545 plane glides up canvas runway onto steamer .... 592 Building Construction—steel house frame gives sky- propeller like huge barrel . ‘ — SE ar tn nie kur es bd e eoteeree 608 siren warns pilot of stalling danger rt es . 614 Buildings—washing faces of, is made eas -. 3 steam turbine for ves ae Camera, Aerial—shows details of ground from aloft .. 583 talks to London while flying over ‘New Jersey ... 623 Candy—helps working girls resist fatigue .... . 599 upkeep of a small, same as that of auto ........ 578 Cattle why tailspin is so often fatal . ‘ 558 brand with squeezer ..................... 560 Airships p-ickly pears as stock feed ................. . 615 gas is stubborn prisoner aboard ....... . 640 Clothesline—without pins . 617 inflating ““R-101” takes six weeks k 576 Concrete—sand tester shows quality of mixture 600 Alaska—vast glacial tract in, remains unexplored .... 552 Cotton—seed “fuzz” valuable 646 Aluminum—hardened will not stain or tarnish .... . 600 Currency—reduced size bank notes cuts printing bill. 636 Animals—luminous cloth lures coons 590 Customs—dyed goose feathers puzzle custom chemists 592 Architecture—crosslines on building give unique effect 635 nes earth may change ..... - 553 Art—students have classes on skyscraper roo! ey Education—college travels on wheels ............. . 604 Automobiles Envelopes—moistener seals and closes flaps ....... 624 roller coaster gives motorists thrills ae . 552 Eyes—are you right or left-eyed? ................. 582 side sway remedied by control ........ Be. . 609 Fires, Forest—plane smokers start wees dvegual 583 single-cylinder has motor in rear .......... 583 Fish and Fishing Automobiles, Accessories anglers see beneath waves with a water scope .. 593 battery indicator checks power and water ....... 607 bait bucket with spring top 591 campers’ bed on top of auto ....... se shoal de gn Floodlighting—dome’s outside Levssveness by “inside hub plates for Fords ............... a BE Cucitcdacdcs eer sake iad oa 640) 43-65000n00R (Continued on Page 4]

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ON OLE RTT oT ost Fruit—electric sunbaths for . Se tt Foa Fruit Fly—war on waged in Florida ae a Te AE Furniture—armchair and bed in one .... i—bag container for car attached on running board Highway—balanced rock is preserved by rerouting .. Horse Racing—betting machine on wheels Horses,Race—heart tested by light-ray machine ._.. — psa enter apace eae hose reel and coal chute House Ice—dry, cause of injuries . Insulation—invisible walls shield home from heat and RS Be Ee hard 6 cinndn Vo 25 «4 049s Kettle—automatic tes gh Ra Lake—deepest fresh-water ......... - e—finds symbol for word “the” . ate Lawn Mower—run by current from light socket ..... Library—plan films of books to conserve space Life Saving—trifie and rocket shoot line to swimmers . Lock—casement, is burglar-proof 34 : Locomotive—model, hauls sixteen persons .......... Markets—drive-in, help solve traffic problem Monument—forgotten story of ancients told by .. Motorcycle—“wall of death” latest thriller _. Moving Pictures—make-up tried out on modeled faces Navy, French—world’s fastest wer ship Navy, U. S.—ship chart shows position Pe naval vessels Noise—city noises tire strangers : Oil Well—movie wind machine snuffs out oil fires . Organ—eleventh finger improves tone effect oe Paints and Painting—black fence post turns white . Pavement prevent skidding by designs in .......... tar shaved from, by tractor rake .... Piling—tide employed to save from marine ‘borers .. Plaster—steel mesh with fiber coat makes base for . Radio—helpful hints from the lab Radio, Aerial—new device eliminates antenna Radio—Apparatus electrolytic rectifier replaces tube ‘ station yo replaces tuning knob . Radio—Application radio aids music students to hear own voice . switch clock is designed for fruit growers Radio—Coils—disk coils for the experimenter Radio—Condensers—locating defective, in power units Radio—Loud Speakers new rectifier for dynamic ............... deeper tones from .. Radio—Receivers a de-luxe. receiver of unit design ............. a tion h for the experimenter ......

cost of operating DIMER Kine dows bs +<c0 dds oth self-contained a.c. three tuner employs four screen-grid tubes Radio—Reception—interference from flashers under control . Radio—Transformer—improving the audio amplifier. Radio—Tubes inexpensive fixed resistors . salvaging charger bulbs .. Railroa box car with removable top .. inter-car telephone system Rammer—for paving blocks . Rugs—three tests for old Saws and Sawing—round saw to cut plaster Sea Elephant—four hundred pounds of fish daily meal. Ships and Shipping old warship turned into floating club rudder shape secret of great liner’s speed shipbuilders vie for Atlantic record 616 Smokers’ Accessories—cigar extinguisher with ash receiver . “wa Statuary—forged, is detected by violet rays . Submarine blown to surface in tests . ‘ escape from, aided by breathing apparatus : Swimming—old theaters remodeled into pools Telephone—wire on ground helps guard forests .. Tennis—ball sealed from air until ready to use Theater—stage on wheels moves on rails combined Thunderstorm—lowest place is the safest in a 615 Tornadoes—in action pictured by as tiated 62 Tracing—frames for stencils Truck self-loading, handles ten tons of steel .. 636 vanishing top changes from closed to open van .. 631 Weather—portable bureau on wheels 6 this model plane flew forty-one minutes . 578 Cart [4] [Contents—Continued] Wires—kept off floor with baseboard clips . Wood Shaper—for the small shop is portable ....... Zoo—penguins live in ice box ..................... AMATEUR MECHANICS Airplanes cornstalk makes model fuselage ... Andirons—made from old anchors .. Aquaplaner—safeguard for the outboard Automobiles keeping free from rust Automobiles, Accessories an electric radiator heater ..................... comfortable auto seat for baby dashboard watch holder ................. 5s Automobiles, Repairing—repair for the timer roller. . Automobiles, Tires—repairing inner tubes : Boats and Boating—make this speedy skimmer .. Bottle—holder for the baby’s —equipped with old auto tires * a Coffee Bottle—old, decorated in modern sty le : Drilling—“strait-jacket” for drills prevents ~ eee . Fish and Fishing aoe preserving fishing-rod grips . wax covers barb on fishing hook Glass—cutting kink .... Grommet—film-spool ends make ‘good t Hallowe’en—stunts for your party 576 Heating—heat cafe with excess heat from Fange Knife—emergency sharpener Lawnmower—repairing ae Lawn Seat—concrete, and tree ‘guard Bete ee eee ere ae ae Paints and Painting—sealing-wax lacquer Photography—drying negatives quickly Rodents—gassing Soldering—tinning bits ....................000000, Stairway—folding, to the attic ..................... eect leds haces dick scpeese hee Vaporizer—inexpensive electric Windmill—old favorites in new forms SHOP NOTES Agricultural Implements covering rows of seed with dirt ................ weight on mower lightens tongue .............. Automobiles, Repairing—hydrometer syringe used to eae eee eee Automobiles, Truck—half of large tank used for body. Automobiles, Wheel—forked tool helps mount disk . Barrel—simple method of slinging a ......... Batteries—tool for removing terminals ..... Belts—how to eliminate static electricity from moving 7 Bench Saw—handle for the Brush—holder for artists’ Cans—metal, testing for leaks Cleaning—removing tar and asphalt spots Doors brace keeps from sagging .. how to set and level a door jamb Electric Light—saving in the stock room Emery Wheel—sliding tool rest for Floor—cement, covering to prevent dust . Furniture—trestoring damaged _. Gutter—repairing leaky Hardening—can for local ............... Lathe—double parting tool ..... Lumber—roller helps load in box cars Machine Screw—templates for drawing angles of heads Measuring—diameter of flanged holes Photography—quick method of making photo solutions Printing feeding paper on job press ........ how to prevent “‘offset’’ in ery Riveting—adjusting the air bucker-up Pee ees Saws and Sawing bands for bandsaw wheels efficient guard for a saw trimmer .. holding the work in the sawbuck .... Screwdriver—two kinks worth knowing Tapping—soft materials “42 Threading—cutting threads without a die Tools—device to pick up articles Tractor—canvas top for the . expansion and contraction ° ae 647 how to apply the ‘ ‘sugi” finish . 698 697 690 . 696 690 . 701

“Wit! time.

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698 689 598 597 689 691 697 700 695 688 702 589 695 598 701 699 596 692 595 591 589 /01 590 590 596 /01 595 02 596 596 701 591 700 102 j02 87 Bulldog Furnace Co., box t35""Gnace in: LT Se POPULAR MECHANICS ADVERTISING SECTION 103 27, Tons Heats 6 Rooms! “With our Bulldog Furnace we use about 21 tons of coal a winter on the average, and it is cozy all the time. We have only a 6-room house so we just use a third of the grate. Three cheers for the ‘Bulldog’!” Frank H. Taylor, Dunning, Nebr. sparging tas ora tomy tind Sipe nye Bg toe fo work of 3 maiats fhe cpeond winter I have weed tho Bulldog ond Spain, Cased, ee ones Os sale ASR RD KEY ° at that. My Bulldog not, only does that, bat also 3 rooms upstairs, “Our a per ans ieee oe - xine at al Eawin O"Diplock. ock> 100 Bim : Arthor Cloepfil, R. FD. No. 1, Rock Port, . No Money Down! Small Monthly Payments—Installed ae as Easily as a Cook Stove! The Bulldog is sent to for free inspection. Then, if satis- kitchen cook stove. Don’t with the Sa ou make ool oma snea al monthly payments at our remark- Oi fact fashioned stove heat or Seumpautwape Sgieeen een ~ OWWcie today! Don’t miss this chance tocut canso easily get th greatest advance ta ecientinc heating at Soon oe fal ballet inated « Bulldog Furnace! ot comnes 68 an astonishin ly low price. orice. The Bulldog burns almost any beat of base nt—and you i tna pet in tes lee than Sealtascleraiha, Welure tedseriamedions ta tok oO By ‘ou it yourse . vos S the Bulldog hanontadidie ship from the nearest point. wre eee wee ee oe Send f for Free Book! tButldog Fusnece Co ss.57,calease Without obligating me, please send me your free catalog Learn how to have all the heat you want—where you want it—and ‘ and special offer ~ 3 the Ba: lidog Furnace. Save money! Remember the Bulldog is different—and better! Have youa basement? YesOQ No Complete combustion of gases save 25% of your fuel bill. Exclu- sive Gable-Top Radiator receives ail the direct rays of the fire. Exclusive oblong fire-pot is not only ideal for coal, but enables you to keep a wood fire over night. Remember—the Bulldog issent for Sree inspection—then small monthly payments at an amazingly low Price !—Send for Free Book TODAY! Street Address _.....--. 5 atinndeidhdiipaaiatitiimniniiimndincndiediada =

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and the steamship Sremen, ortation fropenca DY sweive Motors, ese Three Huge Units Promise a Complete Change in the Picture of International Transp SMe Di AVUVUS SF aESSCUES! JZOTTMUECE wotcapiane, MIG Gt ppeii, sa. Breaker of Ocean Speed Records; Th VS iseass7yT 2 & Very + Seeewe 6S SF SSeS WS SEES SESS SNS BUS» Popular Mechanics Magazine REGISTERED IN U. S. PATENT OFFICE WRITTEN SO YOU CAN UNDERSTAND IT OCTOBER, 1929 No. 4 By K. M. PAINTER VOICE thundering advertisements from the skies suggested the possi- bility of using a loud speaker in fire-patrol planes to direct the ground forces in their war on forest fires. When the great fire swept over the Sierra Madre mountains a few years ago, fire fighting was directed from the city hall, and many hours elapsed before an order could be taken to the men at the front. Now, by using an airplane equipped with a loud speaker, an order can be given directly to the fire fighters. With such an airplane to patrol the fire front, the men can be kept working at greater advantage and out of zones of danger. At the close of the World War, the $29

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530 POPULAR MECHANICS army co-operated with the forestry service and established an aerial patrol system. During the first four years of patrol work, definite routes were followed, varying from 200 to 500 miles in length. Each plane was equipped with a radio sending set. The ground stations were so located that when a plane passed from the reeeiv- ing range of one station, it went within the radius of another. By this means all new fires discovered, and the status of old fires, could be reported immediately. A pilot and observer were in every plane. The pilot attended exclusively to the flying duties, while the observer con- fined his attention to finding and report- ing fires. To adequately cover the terri- tory assigned to a route required four to six hours, depending upon the number of fires discovered. And forced landings, in those early days, were hazardous indeed, but more and more fields are being cleared to reduce the risk involved in “lighting in the trees.” In 1928, the forest service stopped the use of army planes and contracted with commercial companies for its aerial patrol work. These contracts were made with flying companies operating in Oregon, - Washington, northern Idaho, western Montana and California. Bases were maintained at Tacoma and Spokane, Wash.; Portland, Oreg., and Oakland and Los Angeles, Calif. Thus, today, the airplane works in co- operation with the forest ranger or “look- out.” When the lookout sights smoke, he must locate the spot of conflagration on his regional map. Then, by telegraph, he communicates with the fire-suppression headquarters of the district, and men, picturesquely called “smoke chasers” are dispatched to put out the blaze. But after severe “dry” lightning storms, when as many as 300 fires are burning in one dis- trict, it is impossible for the lookout to spot them all. Here the air patrol helps out. When C. W. Meredith, assistant fire warden of the Los Angeles county for- estry department, made his first patrol flight, he was detailed to observe the Ridge Route fire of 1928, and make a survey of its extreme western boundaries, “We climbed aboard, taxied out, headed into the wind and were off at 5:15 p. m.,” relates Mr. Meredith. “While I was ar- ranging my maps and getting ready for a hurried survey of the fire line, we were gaining altitude. We found that the ceil- One of the Forest-Service Patrol Planes Used to Spot Fires over Klamath National Forest in California; Each ne Carries Its Two-Man Crew of Pilot and Observer ing to TO the the ins fez ce we we th gr dit at mi we

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POPULAR MECHANICS 531 ing was very low, and off to the west the fog was rolling in thicker than the well-known peasoup. A pall of smoke lay over the rest of the surround- ing country, and my fears grew to grave con- cern that our mission would spell failure. It was of vital importance that the men on the ground should know the direction of the fire and at what points it was making the most head- way. “It was our duty to get the information to the fire fighters that evening, for on a going fire we have a decided advantage in our favor at night; that is, providing there is not a high wind blowing. At night the humidity rises and the temperature drops, consequently fires are reduced to a lower burning point. “When we were over the portions of the fire that had been brought under con- trol, I slipped out of my safety belt and grabbed my map and pencils. Being in the forward cockpit, I did not have the vision that I would have had were I in the rear. I tried standing up, but my chute inconvenienced me and the air cur- rents over the fire made the going bumpy. My pilot took a hand, and by banking the ship to the right or left at an angle that would give better visibility, made my work much easier. This Two-Story House Was Built Years Ago by a Prospector in the Stump of a California Redwood 3,000 Years Old BUNGALOW ERECTED IN STUMP OF CALIFORNIA REDWOOD In the stump of a California redwood, estimated to be 3,000 years old, a mining prospector years ago built himself a two- story dwelling which is still intact in what is now General Grant National Park. He kept his horse downstairs and lived in a room on the second floor. BURGLAR-PROOF STRONG BOX HANDCUFFED TO CARRIER Intended to thwart thieves when valu- ables are being carried through the streets, “Tt was close to being dark when we turned south for home, and at 6:40 p. m., we were once again at the Saugus field. I telephoned the results of the survey and reports were rushed to the camps on the fire lines. The informa- tion was obtained a woman detective has invented a strong box which is handcuffed to the carrier and also equipped with a burglar alarm. The wrist is thrust in- side the cover and chained to a handle there. Pressure of the messenger’s fin- gers sets the alarm sounding if an at- in one hour and made to fifteen minutes.” To Thwart Thieves, the Messenger’s Hand Is Chained to the Handle of This Strong Box tempt is kidnap him.

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532 POPULAR MECHANICS In Circle, German Glider Which Set Record, and, Above, Transporting It by One-Horse Power GLIDER MAKES WORLD RECORD IN GERMAN CONTEST Robert Kronfeld, German aviator, and his glider “Vienna,” established a world record for motorless planes in the tenth annual international glider contests re- cently held in Germany. The “Vienna” and its pilot flew 150 kilometers (about ninety-three miles) and reached a height of 2,000 meters (4,400 feet). AUTO HIGHWAY TO ALASKA Alaskans are planning an automobile highway connecting that country with the United States by way of Canada, with Seattle as one terminus and Fairbanks as ‘tthe other. Of the 2,000 miles necessary, 1,250 miles of road already is constructed. Aside from opening up the country to © P. & A. tourists and sportsmen and aiding agricul- ture and commerce, Alaskans claim the project would also help the proposed air route to Asia by way of Alaska. WHITE-HOUSE PHONE SYSTEM GREATLY EXPANDED Included in President Hoover’s plans for efficient administration of government business are additional telephone facili- ties, and a switchboard, equipped for eighty telephone lines and forty trunk and tie lines, has been ordered. Telephone service in the White House first was in- stalled during the administration of Pres- ident Hayes, but the first switchboard serving the executive offices was not in operation until 1901. The service was ex- panded during the war. President Hayes and President Cleveland rarely used the telephone and even President McKinley transacted little government business by phone, because the system was not exten- sive enough. President Roosevelt like- wise did not use the telephone much, but President Taft employed it extensively and President Harding transacted daily routine business by phone. President Wilson, however, was not a telephone user, but President Coolidge found it helpful in his daily work.

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ul- ns nt li- or nd n- S- rd in POPULAR EIGHTY-THREE INSTRUMENTS GUIDE AIR LINERS Flying a big tri-motored transport plane requires watching eighty-three different controls and instruments, including the separate devices showing the functioning of each of the engines. Preparatory to landing, it is necessary that pilot and co- pilot check the position of ten controls, and, at night, this number is increaséd to twelve when landing lights must also be adjusted. In one of the Boeing trans- port planes, there are twenty-seven elec- tric lights, eighteen of them with indi- vidual switches. In addition to the rou- tine operations of flying, the pilots, in landing, must adjust the horizontal sta- bilizer, switch on the generator cut-out, put on the reserve tank, switch on both wing tanks, put altitude adjustment to “rich” on left, central and right motors, and adjust the throttle of left, center and right wing landing lights in position. BABY HUMMING BIRD IS NURSED WITH MEDICINE DROPPER When a California man found a baby humming bird, he took it home, but did not know what to feed it. After diligent search of bird literature, he learned that honey and sugar were humming-bird deli- cacies, and fashioned a nursing bottle out of a medicine dropper from which the waif learned to take its meals and soon was hopping about the house. ae | A Medicine Dropper Serves as Nursing Bottle for “Eleanor,” a Baby Humming Bird MECHANICS 533 The Instrument on the Girl’s Arm Measures the Ef- fects of Violet Rays on the Skin TIME NEEDED TO ACQUIRE TAN MEASURED BY MACHINE Effects of ultraviolet rays on the skin are determined by an instrument used by the Chicago health department. In meas- uring the time required for tanning by sunshine, the minimum has been shown to be about thirty minutes. The test con- sists in making a series of exposures of the skin to sunlight through the appa- ratus, which is a metal plate containing a dozen holes with shutters. The appli- ance, with shutters open, is placed on the arm, and one shutter after another is closed at five-minute intervals for an hour. NOISES FOR DRAMA OVER RADIO RECORDED ON PHONOGRAPH “Crowd noises” and background sound accompaniment of dramatic productions broadcast over the radio, including gun- fire, train sounds, opening and closing of gates and doors, and cheering and hissing, are being recorded on phonograph records for permanent use by a British broadcast- ing company. As required, the company sends out its men to make records of noises of trains and elevators or of water lapping along a beach, as the play may specify. The method is costlier than the older one, but more realistic.

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POPULAR MECHANICS WORLD’S FIRST ALL-METAL DIRIGIBLE BUILT Vertical Construction by Sections Was Employed, as Shown Above, in Building the “ZMC-2,” First Metal-Clad Airship; It Is a 200,000-Cubic-Foot Dirigible, Built at Detroit for the U. S. Navy, for Experimental Work

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POPULAR MECHANICS FOR THE NAVY HAS A LONG FLYING RADIUS ag et Above, Unusual Interior View of the Metal- Covered “ZMC-2,” Which, Engineers Say, Is the Forerunner of Super Metal Airships to Be Used in Transoceanic Flight; at Right, Auto- matic Riveting Machine Used to Build the “ZMC-2,” Which “Séews” 5,000 Rivets an Hour and Does the Work of 120 Men; in the Metal Ship There Are 17,596 Feet of Riveted Seams, or About 3,000,000 Rivets; Below, Front View of the All-Metal Control Cabin and Some of the Motors, Developing 440 Horsepower

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eos meres

536 POPULAR MECHANICS

troller governs both mo- tors, geared to two large sheaves which engage .the traction rope. Stop- ping the carrier normally is accomplished auto- matically, in four graded steps, and “spotting” the car at terminals for load- ing or unloading is ac- complished by the use of a push button. Magnetic brakes will stop the car- rier when descending if the power fails. MIRRORS AND LOUD SPEAKERS DIRECT COAL-YARD GANG Executives of a To- ledo, Ohio, coal company issue their orders to yard employes through a pub- lic-address system and see that their instruc- tions are being obeyed. The system involves the use of a reflector com- bining the properties of mirror and field glasses

Courtesy General Electric Co. An Electric Cableway Which in Six Minutes Transports 24,000 Pounds of Lumber a Half Mile over a 1,200-Foot Canyon ELECTRIC TRAM HAULS LUMBER OVER HALF-MILE CANYON Spanning a canyon a half mile wide, the largest electric cableway in the world transports lumber from a loading point on one side to the mill on the other, near Camino, Calif. The tram carrier hauls 24,000 pounds of sawed lumber between the two terminals, 2,700 feet apart, making a round trip over the 1,200-foot canyon at a maximum speed of 1,800 feet a minute. The round trip takes a little over six min- utes, including loading and unloading. Four steel cables, each two inches in diameter, support the carrier, which runs on thirty-two wheels, while the one-inch traction rope is endless. The electric equipment includes two 225-horsepower hoist motors, operating in parallel. <A single manually operated master con- along with the voice-am- plification unit. A man receiving a message through the loud speak- ers raises his arm to indicate that he has heard it, and this movement registers on the operator’s mirror. SUN’S ACTIVITY HELPS RADIO RECEPTION IN DAYTIME Better daylight radio reception in 1929 has been attributed by the bureau of standards to solar activity. A study has revealed that daylight reception this year has been at a maximum and static at a minimum as compared with recent years, and solar activity also has been at or near its maximum in its eleven-year cycle. In 1923 and 1924 reception was weak, and static was high, but since 1927 has been falling off. When solar activity increases, something. resembling ultraviolet radia- tions are given off in larger amounts, af- fecting the earth’s electrical atmosphere.

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Courtesy Dr. Clyde Fisher Hail Fell to a Depth of Three Feet on the Level during This Remarkable Storm in New Mexico; Note the “Natural Bridge’’ Formed by Stream under Hailstones By CALVIN FRAZER HOUGH hail is familiar to everybody, the majority of human beings go through life without witnessing a really destructive hailstorm. Many such storms occur every year, but each is limited to a relatively small portion of the earth’s sur- face. : Although, geographically speaking, the severe hailstorm, like the tornado, is al- ways a small affair, it represents such a concentration of nature’s destructive fury that, in the aggregate, hailstorms levy a heavy toll on property. The average an- nual damage done by them in the United States is three or four times that done by tornadoes. According to a recent esti- mate, the hail losses on ten leading agri- cultural crops of the country amount to $47,500,000 in the average year. The losses on these crops in the year 1915 totaled $69,000,000. Last year there were two hailstorms in the state of Kansas, each of which cost the farmers $3,000,000. The loss sustained by agriculture is only part of the annual hail bill. In the old world some of the heaviest losses occur in vineyards, and on both sides of the ocean, greenhouse glass comes in for an immense share of damage. Ordinary win- dows are sometimes broken on a large scale. A remarkable case of this kind occurred in Vienna, Austria, when an early-morning hailstorm smashed more than a million window panes in the course of a few minutes. Another possibility in the line of hailstorm losses was illustrated at Dallas, Tex., in 1926, when big hail- stones riddled the tops of thousands of automobiles, shattered many windshields and wrought damage totaling about $100,000 to these vehicles. This hailstorm was the most destructive that has ever oc- curred in an American city. Tons of ice fell on streets and buildings during a period of fifteen minutes, and in the busi- ness center of the city the stones attained 537

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538 POPULAR the size of baseballs. Not only were thou- sands of windows and skylights broken, but a great many tile, slate and shingle roofs were wrecked, street lights and elec- tric signs were shattered, and there was the usual damage to greenhouses. The losses in the city and its vicinity were esti- mated at $2,000,000. According to an official publication of the weather bureau, an unusually severe hailstorm swept a path five miles wide across the southern part of Gove county and the northern edge of Lane county, Kansas, on the night of June 4, 1927. The report says: “Fields in the path were left as bare asa highway. Trees were stripped of branches and leaves, and horses, cattle, hogs, sheep, rabbits, chickens and_ wild birds were killed. Hailstones piled into drifts eight to fifteen feet deep, and many of these drifts remained for three days after the storm.” There is a proverb in eastern Europe to the effect that “hail brings not hunger”; referring to the fact that, because of its local character, a hailstorm cannot cause a general famine. There was, however, a case in which a hailstorm caused such widespread distress that it helped bring about a great social upheaval—the French ‘revolution. Beginning in the center of France in the early morning of July 13, 1788, this storm passed northward in two parallel bands about twelve miles apart, MECHANICS crossed Belgium, and finally died out in Holland in the afternoon. One band was ten miles wide and 420 miles long, the other five miles wide and 500 miles long; making the total area over which hail fell vastly greater than in the average hail- storm. No less than 1,309 communes in France suffered from this visitation, and the total losses were estimated at $5,000,- 000—an immense sum at that period. This disaster undoubtedly hastened the coming of the revolution. In comparison with the enormous dam- age done to property of various kinds by icy missiles from the sky, the number of human beings killed or seriously injured by hail is insignificant. Why this should be so isa mystery. Leaving exceptionally large hailstones out of consideration, it is not at all uncommon for hailstones weigh- ing from one to several ounces to fall by the thousands or tens of thousands on in- habited areas. The speed with which they fall, in many cases, is indicated by the fact that they smash skylights of heavy wire glass, pierce window panes with a clean round hole, like a bullet, and bury themselves a foot deep or more in soft earth. Why do not these missiles slay scores or hundreds of people every year? _No satisfactory answer to this question has yet been offered. The most fatal hailstorm of which we have an authentic record was one that All That Was Left of the Glass in a Pennsylvania Greenhouse after a Severe Hailstorm; This Shows Why Hail Insurance Is Popular in Many Localities

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POPULAR MECHANICS 539 After a Hailstorm in Montpellier, France, Plaster Models of Large Stones and Auto Tops Riddled by Hail occurred at Moradabad, India, May 1, 1888, which cost about 250 lives. According to one Eng- lish writer who witnessed the ef- fects of this storm, a majority of the victims were actually pounded to death by hailstones, but ac- cording to other reports most of them were knocked down by hail and wind, buried under the drifts, and died of cold and exposure. There have, however, been sev- eral cases reported from India in recent years in which hailstones killed from one to a dozen or more people by the direct action of the hailstones. Big hail seems to be more prevalent in India than in any other country. Writ- ing of the furious hailstorms of eastern Bengal, Mr. W. R. Haughton says,in a recent article: “Hailstones of over three inches in diameter are not unusual. I have seen two hundred cattle killed by hail in a single storm. These large hailstones may be sometimes seen falling few and far apart, when they look like small birds swooping down.” At the village of Klausenburg, Roumania, on May 1, 1928, six children were killed and ten

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540 POPULAR MECHANICS Cross Section of a Typical Thunderstorm, According to Dr. W. phreys of the Weather Bureau, Showing Ice or Hail “Factory” in Clouds adults were badly injured by hail during ~ the celebration of the May-day festival. On July 4 of the present year two men and one woman were killed and several persons were injured by hail in the sub- urbs of Nuremberg, Bavaria. These events were quite exceptional, however, for in most years there are no deaths from hail in Europe, and apparently not . more than two or three have been re- corded in the whole history of the United States; the only case of recent date was on May 21, 1928, when a fourteen-year- old boy was killed by hail while working in a field near Laredo, Tex. The maximum size attained by hail- stones is a matter of great uncertainty. A new record of size for the United States is said to have been established by the storm that occurred at Potter, Nebr., on July 6, 1928, when among numerous hail- stones “as large as grapefruit” one was found to be seventeen inches in circum- ference and to weigh one and a half pounds. This huge stone, with several others, was measured, weighed and pho- tographed. At Cazorla, Spain, on June 15, 1829, houses were crushed under blocks of ice some of which are said to have weighed four and a half pounds. In the summer of 1902, hailstones weighing ten pounds were reported by an English mis- sionary to have fallen at Yuwu, Shansi province, China. The missionary un- doubtedly found such stones, but did they fall? The fact that hailstones lying THUNDERHEADS packed closely on the ground readily freeze to- gether to form huge masses of ice is at the bottom of all the most re- markable hailstone sto- ries not made out of “whole cloth.” Not all particles of ice that fall from the sky are hail. Little pellets like miniature snowballs, about the size of coarse shot, falling in cold weather, are known to science as “graupel,” while the bits of clear ice, like frozen dewdrops, that also fall during the cold season are called “sleet.” True hail occurs almost exclu- sively in connection with thunderstorms. It is usually of brief duration, though it has been known to fall steadily in one place for more than an hour. A distinguishing feature of true hail is that it consists partly of ice and partly of snow. Large hailstones frequently show several alternate layers of these sub- stances. Most hailstones are approxi- mately spherical or somewhat conical, but other and very striking shapes are some- times found. The peculiar structure of hailstones is explained by the fact that hail is formed in the turbulent region at the front of a thunderstorm, where it makes several journeys up and down be- tween relatively cold and warm regions of the atmosphere before finally falling to earth. At high levels the incipient hailstone is coated with snow and at lower levels with rain, which changes to ice as the stone is again carried aloft. Red hail is a reality, though very rare. As in the case of red rain and some red snow, the color is due to fine dust in the atmosphere. J. Hum- EARTH AS GREATEST DYNAMO YIELDS MUCH ENERGY Generating enough current to supply light, heat and other electrical needs for the ten largest cities in the United States for 1,000,000 years, the earth is a huge dynamo and one of the greatest electrical

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POPULAR MECHANICS 541 wonders of the universe. Dr. Ross Gunn, of the naval research laboratories, esti- mates currents generated inside the earth at more than 200,000,000 amperes, although this energy, like atomic energy, is unavail- able for use by man, being kept in nature’s storehouse for the benefit of generations perhaps a million years hence. He attrib- utes the electrical currents inside the earth to the motions of tiny electrical charges known as electrons, the motions being caused by the high temperatures existing inside the earth. REMOVES POISON FROM DRUGS Drugs such as those contained in mor- phine, coffee or tobacco may be made in- nocuous while preserving full medicinal qualities, a German scientist declares, by adding small quantities of lipoid, a neu- tralizing wax or fat-containing matter which is present in many animal and vege- table bodies. With coffee, for instance, the scientist says, the addition of a few drops of lipoid entirely obliterates the noxious effects, while preserving the nu- tritive and momentarily sustaining effects. ELECTRIC TOASTER FOR BUNS MAKES HOT SANDWICHES Bun sandwiches may be served hot and toasted by using an electric oven intended primarily for buns, but which may be used for bread also. It takes from five to ten buns, or eight slices of bread, at a time and requires less than a minute for toast- ing. The device adjusts itself automati- cally to various sizes of buns. An Electric Toaster for the Quick-Lunch Counter Provides Customers with Hot Bun Sandwiches RAISED BENCH FOR SHOE STORE MAKES FITTING EASIER Fitting Shoes Is Made Easier for Salesman and Cus- tomer by Using This Raised Bench Greater comfort for customer and sales- man alike is provided by a raised bench for the purchaser of shoes which brings him up to a height where the clerk may fit shoes without stooping. Wide steps are provided for the bench, and to the salesman’s right is a cabinet where shoe accessories may be kept. TALKIES FOR THE DEAF Talking pictures are proving a source of amusement for the hard of hearing in Brooklyn, where a section of a theater has been fitted with acoustic equipment for the use of persons whose hearing is impaired. Each seat of the section has a receiver and headpiece and a potentiom- eter, shaped like a fountain pen. A con- trol button on this instrument regulates the volume of sound to the hearers’ needs. According to government statistics, there are 15,000,000 deaf persons in the United States, and many of them viewed the talkies with alarm because they feared they would be unable to follow the pic- ture without the usual titles.

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542 POPULAR MECHANICS ©P. &A. The Prince of Wales Witnessed a Display by the London Fire Brigade, Including Thrilling Rescues from a Burning Building and Daring Feats on Extension Ladders, Such as Pictured Above LONDON’S FIREMEN DO STUNTS FOR PRINCE OF WALES London fire fighters performed stunts for the Prince of Wales at the annual dis- play of the fire brigade recently. Among the feats witnessed by royalty was a res- cue from a burning building and daring tricks executed from the top of lofty ex- tension ladders. AIRPLANE TIRE ACTS AS WHEEL AND SHOCK ABSORBER Requiring no time on all surfaces except concrete. The tire resembles a huge doughnut and is streamlined so its wide cross section offers minimum wind resistance. PARACHUTE OPENED BY WATCH LOWERS MAIL FROM PLANE Delivery of small packages of mail from an airplane while it is in flight is accom- plished by an apparatus attached to the mail bag which opens a parachute after the pouch is dropped. An aluminum shell is equipped with a precision watch and is attached to the top wheel, but fitting di- rectly onto the hub, an airplane tire of great thickness has been successfully tested as landing gear. The cushion- ing effect of the tire under low air pres- sure causes it to act as a shock absorber as well. Brakes can be fitted to the hub, if desired, and ex- periments have of the sack while above the shell is a small parachute folded in a frame. The pilot adjusts the watch accord- ing to his altimeter reading and throws the mail overboard. The watch releases the parachute at a designated height, and the mail floats to earth. A large model is capable of shown that the tire reduces take-off This Airplane Tire Fits Directly onto the Hub, Acting as Wheel and Shock Absorber lowering sixty-six pounds and, in an-

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POPULAR other form, a parachute ® is attached to a skyrocket which lights at the mo- ment contact with the earth is made. TALKING PICTURES SHOWN IN SLOT MACHINE Slot machines now dis- pense talking motion pic- tures. A Massachusetts man has invented an ap- paratus designed to pro- ject talking and singing films when a dime is dropped in a slot. The films may be shown in daylight in a boxlike structure, five minutes being required for one picture. The coin is dis- pensed with in machines intended for the home, the apparatus then being controlled by a switch. When ‘a coin is inserted, red and blue “footlights” flash on, a curtain rises displaying a screen twenty-four inches wide and twenty inches high, after which the lights are dimmed and the pic- ture begins. The inventor calls his ap- pliance an “acrophone.” Emptying This a= of Floor Space, Requires Only Talking Moving Pictures Are Shown by This Machine When a Dime Is Dropped in a Slot MECHANICS 543 e Hexagonal Airplane Hangar, with 54,000 Square Feet irty Seconds HEXAGONAL AIRPLANE HANGAR MAY BE EMPTIED QUICKLY Requiring but one minute to remove all the airplanes from its 54,000 square feet of floor space, a hexagonal hangar, be- lieved to be the largest in the world, has been constructed at Los Angeles for the Western Air Express. Each of the six sides has a self-opening steel door 126 feet wide, and all the doors may be opened in thirty seconds. Emptying the hangar is simplified by sloping floors, enabling one man to handle a big tri-motor plane with ease. OIL-WELL VALVE CUPS CHANGED HALF MILE UNDER GROUND Removing the valve from a deep oil well to change cups and leathers, hereto- fore a tedious and expensive process, is unnecessary with a valve which allows cups and leathers to be changed auto- matically 3,000 feet under ground. The first operation is to drop a cartridge down the rods, which releases the valve case and brings it to the surface. Then, another case, equipped with fresh leathers, is low- ered and the cartridge fastens it to the core. The whole takes about half an hour, while previously several men and a tractor were required for a day or more. ee ae

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544 POPULAR Four Trunks, Such as Shown Above, Contain an Entire Portable Talking- Picture Apparatus for Use in Schools and Salesrooms PORTABLE TALKIES FOR SALES AND SCHOOL WORK For use in education and industry, a portable talking-picture machine has been designed, employing the sound-on-film method of reproduction and operating from the ordinary alternating-current electric-light supply. The entire equip- ment is contained in four trunks and can be set up in a few hours. The apparatus weighs 800 pounds and the amplifier is of sufficient power to supply sound volume for an audience of 800 persons. Screen and horn are supported on the two trunks in which they are placed for shipment, supports to wall or ceiling being unnec- essary, the screen rolling on a curtain roller which fits in the screen trunk. The machine has been used successfully in churches, classrooms, salesrooms, audi- toriums and offices. A SINGLE-WHEELED SEAPLANE Performing perfectly in its first trials on land, a single-wheeled seaplane was demonstrated recently in New York. The wheel is fitted in the middle of the center pontoon with the hole covered by a trap- door, so that a landing may be made in water. The ship is prevented from bump- MECHANICS ing on its wings by skids fastened to the wing floats. When alighting on or taking off from land, the weight is borne by the single wheel, with the skids sup- porting the wings if the amphibian tips to either side. The device, it is hoped, will solve the problem of landing gear for light seaplanes. AIRPLANE STARTED BY SHOTGUN SHELLS Half-length twelve- gauge shotgun shells supply the initial force for a self-starter for air- planes sponsored by Charles A. Levine, trans- atlantic flyer. The starter, weighing four pounds, is screwed into the aperture of a cylinder from which the spark plug has been re- moved. The plug then is placed in the starter in such a manner that it continues to operate after the motor has started. A shell inserted in the starter is held in place by a military-type gunlock equipped with a safety device to prevent premature fir- ing. There is no noise, and smokeless powder is used. maa? Here Is a Self-Starter for an Airplane, Using a Shotgun Shell to Supply the Force

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\e - Fe Fr ww POPULAR MECHANICS 545 ALUMINUM COVERS FOR BOOKS RESIST TROPICAL HEAT Because in some parts of Africa the air is so dry that the covers of books are turned back by the heat and lack of mois- ture, an aluminum binding has been made for volumes subject to such conditions. The aluminum cover is of about the thick- ness of an ordinary tin can, is light in weight, insect-proof, and washable. The metal is chemically treated to take ordi- nary printing ink as well as enamel or paint. The paper as well as the cover is made insect-proof, the paper being treated with a carbonate-of-soda solution. IMPORTED PEAS IMPROVE SOIL Three peas, imported accidentally when a veterinarian ordered two quarts of Swe- dish vetch for his farm, may contribute much to the wealth of American farmers. The three peas, now increased to nine bushels, have a vigorous root system, knotted with nitrogen-bearing nodules, and the vines are prolific, often extending from six to twelve feet in length. Indica- tions are that the peas will yield about thirty bushels of seed to the acre, and a marked improvement in productivity of the soil has been noted wherever they have been planted. TAR SHAVED FROM PAVEMENT BY TRACTOR RAKE Confronted with the problem of remov- ing the slippery and dangerous tar which oozed out of the cracks in the pavement during hot weather, the employes of the Delaware River bridge made a steel- claw rake and at- tached it to the rear of a tractor used to push a sweeper. The weight of a man on a seat over the rake forces it down into the tar, the apparatus dis- lodging lumps of tar, which are then gathered with the sweeper. Scraping Excess Tar from Pavements Is Accomplished with This Tractor and Steel-Claw Rake This 7,000-Pound Sea Elephant, a Circus Attraction, Eats 450 Pounds of Fish Daily FOUR HUNDRED POUNDS OF FISH IS DAILY MEAL Weighing 7,000 pounds and making a daily meal of 450 pounds of fish, “Goliath,” a sea elephant owned by a circus, attracts crowds wherever the show goes. He was captured in the Lost Sea near the south pole, and weighed one ton then, but has gained 1,000 pounds a year ever since and is not yet fully grown. He is known as a sea elephant for want of a better name and is said to be the only specimen of his kind to survive captivity for any time. On the circus lot “Goliath” has a special tank holding 6,500 gallons of water and when he travels he goes on a 100-foot flat car equipped with a 10,000 gallon tank and a sand beach. He eats only fish which he swal- lows whole and has learned to answer his trainer’s call. @ Seventy years ago it took mail twenty- four days to go from coast to coast.

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“D EADY! Walk!” shouts the pilot, seated on a little board, with his back against an upright post, which forms one member of a rather sketchy airplane fuselage. At his signal a half dozen men, three to the left and three to the right, walk away with the ends of a rubberized cable that leads back, in a “V,” to a hook in the nose of the ship. At the tip of one wing another man trots along to hold the wings level, and behind the craft another pair pull back slightly on a tail rope. Ten steps and the pilot shouts, “Run!” The glider, which has been skidding along the ground on a keel skid, rises a 546 few feet as they pick up speed. A dozen paces, and the pilot calls, “Turn loose!” The man at the wing tip has already lost contact, and the pair in the rear, at the word “loose” drop their rope, which falls free from the ship. As the back pressure relaxes, the glider catapults upward and forward like a stone fired from a sling shot. The pulling rope, caught in its middle in an open hook, point downward, drops free, and the pilot and glider are off to soar among the birds. That’s motorless flight, as it has been introduced into Amer- ica from Germany. The ship described, with its sketchy form of fuselage and the pilot sitting out in the open in front of the wing, is a pri- mary-training glider. For more advanced work, and particularly Miss Maxine Dunlap, Successful Glider Pilot, and, Be- low, Launching a Popular Type of Glider

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Miss Dunlap in the Air during Her First Successful Glider Flight; in This Type of Machine, the Pilot Sits Out in Front of the Landing Skid for real soaring flights, gliders are built with comfortably inclosed cockpits, a windshield to protect the pilot, and many even have an instrument board, featuring an altimeter and a clock, to tell both height and duration of the flight. Since gliding grew up and came of age in Germany—one of the unforeseen re- sults of the peace treaty of Versailles, which put obstacles in the way of motor- ized flying beyond the Rhine—the sport has been classified into two distinct types: First there is gliding, a term which the in- itiate use only to describe short flights down a wind hill, sliding down an air cur- rent just as a sled slides down a snow- hill. And then there is soaring, which is something for the adept to do, and covers any flight in which the glider pilot takes advantage of rising currents of air to ascend to a greater height than that from which he started. Given the proper sort of terrain below, which means the right kind of air currents above, and there is almost no limit to what a good soaring pilot can do. German glider experts have stayed in the air more than fifteen hours, climbed to heights of more than 2,000 feet above the point from which they started, flown as far as 200 miles, and more than forty miles in a point-to-point race. An expert in soar- ing can take off, climb hundreds of feet in the air, circle, cut figure eights, and eventually come back to the starting point as easily as though he had a motor to pull him wherever he wanted to go. The pilots who have done that, describe soaring flight as life’s greatest thrill. They go up and play among the birds as equals; in fact, last summer when Peter Hessel- bach, the German pilot, visited this coun- try and made a ten-hour flight at Cape Cod, a flock of seagulls came in from the ocean, fell into line and flew alongside in formation while they studied this strange, new, noiseless bird plane. It takes from thirty to sixty days in a glider school for a graduate of primary- training gliders to master the secrets of the more responsive soaring ship. It not only is necessary to know how to fly it, but the flyer who hopes to go after dura- tion records in the motorless-flight field must be an accomplished student of me- teorology, for his success depends largely 54, H > | ’

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POPULAR MECHANICS The glider association has issued a very explicit warning about the type of gliders that are safe to fly. They turn thumbs down on the light and cheaply constructed out- fits in which the pilot’s body is suspended from the framework, while he tries to get control by swaying his weight from side to side. It was a ma- chine of this type that killed Lilienthal, the great German experi- menter, whose work, with that of Chanute, contributed to the Wright brothers’ success. Instead of this type of craft, the association rec- ommends that both pri- Dale L. Drake in Glider and Lloyd O’Donnell, Pilot of Plane That Towed Glider in Long Demonstration Flight on his ability to guess, from the terrain below, the kind of air currents that are flowing about him, and so twist and turn ‘as to take advantage of every upward thrust. It is because of his dependence on air currents that hilly country or duneland near a large body of water make the best gliding land, for there are always upward air currents among hills, when the breezes rise from the valleys; and there is usually a rising current at the edge of any large body of water. The National Glider association, which has been organized to popularize the sport in America and attempt to capture the duration and distance records from Ger- many, already has established glider clubs in many cities. The gliding enthusiasts are organized in San Francisco, San Diego, Portland and Seattle, on the west coast; in Denver, Kansas City, Cleveland, Akron, Cincinnati, Indianapolis and De- troit, in the central section, and at New York, on the Atlantic, as well as in many smaller towns and cities. All of the clubs, and many individual members, are build- ing ships, either primary or soaring types, and one or two factories are turning out the former at prices as low as $500 to $600. mary and advanced train- ing ships should be op- erated from the pilot’s seat with controls exactly similar to those used in a motorized airplane. In other words, a pair of pedals work the rudder and a control stick manipulates the aile- rons at the wing tips and the elevators at the tail. Experience has shown that the movements required to operate either a motorized airplane or a glider with these controls are the most natural and there- fore reduce danger to the minimum. To build a glider of the type recom- mended requires a rather thorough knowl- edge of aerodynamics and aircraft con- struction. In fact it may take more skill to build a good glider than it does to build a good airplane. Why this is so can be easily under- stood by examining the construction de- tails of the soaring glider being flown at San Diego by William H. Bowlus, who has been building gliders of various types since 1912. His craft is a high-wing full- cantilever monoplane, with tapered wing. In other words, the wing is above the pilot’s head and has no external bracing, while it is narrower at the tips than in the center. The fuselage is built up with four square longerons, running the full length of the plane. They are only three- quarters of an inch square at their thick-

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POPULAR MECHANICS Drake in Glider Which Was Towed by Plane 200 Miles during Recent Exhi- bition by the Long Beach Glider Club; at Right, Glider, Designed by Hawley Bowlus of San Diego, in the Air; It Has a Wing Spread of Forty-Six Feet and Has Been Built to Enable the Pilot to Take Quick Advantage of Favorable Currents, Which Often Rise Several Times Higher than the Take-Off Hill Charles Ferguson, President of the California Glider Club, Testing Out Controls of Glider before Making a Flight; Prize Of- fers for Long Hops Are Stimulating Interest in Gliding

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550 POPULAR MECHANICS Vance Breese, San Francisco Aviator, at the Controls of a Ferguson Glider Which Is Being Launched by Men with Aid of Tow Rope, Dropped Free as Glider Rises est point, beside the pilot’s seat, and taper to one-quarter inch square in front and three-eighths inch square at the tail. The four form a rectangle, nineteen inches wide and twenty-four inches deep, where the pilot sits. In front, the thin ends are brought together to form a_ horizontal wedge, like a chisel point, and at the tail they form a- rectangle, ten inches high and six inches wide. The struts that brace them also are of spruce, with a square area equal to that of the longerons at the point where they are applied. The whole structure is braced with thin diago- nal strips of spruce, only an inch wide and a sixteenth of an inch thick. They are wetted before being glued in place, and when they dry and shrink, they exert sufficient tension to make a rigid body, capable of carrying a 500-pound load. Two bulkheads of plywood in front and behind the pilot’s seat afford him some protection and likewise transmit his weight to the wing: when in flight, and onto the skid when the craft is on the ground. The wing itself is built in three parts, so it can be taken apart when the glider is towed to or from the field. The center section, measuring six feet, is built in as a part of the fuselage structure, and two tips, each nineteen feet long, are bolted to it to prepare the ship for flight. The ribs of the wing, and the ribs in the tail surfaces are made of “kraft” paper, with spruce strips, only an eighth by a sixteenth of an inch, glued to either side. It is al- most unbelievable that such a paper web would have sufficient strength for the pur- pose, but tests in many flights have shown that it is actually stronger than neces- sary for the load it carries. The whole craft weighs but 160 pounds, and two men can hold it up by the wing tips without any appreciable bending of the structure. The weight includes the landing skid normally used for soaring flights. In addition, Bowlus has built a light-wheeled landing gear which is used both for towing on the highway and in experimental flights, and.adds but twenty pounds to the weight of the craft. Such a machine is only for the adept to fly, but anyone with normal faculties can, under a competent instructor, make safe flights of a few hundred feet in one

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POPULAR MECHANICS 551 of the primary training planes. For instruction pur- poses, the clubs seek a hill- side of fairly gentle slope, clear of obstructions for at least 200 yards, and place the plane not too far up from the bottom. The student is strapped in with a safety belt, the ground crew take positions, and the instructor calls the signals. As the ship leaves the ground, it rises a few feet and glides down the wind until it comes depending not only on the speed of the upward current, but the skill of the student at the controls. At most, he cannot fall more than a few feet, and the worst damage that can be done to the ship, as a rule, is to break a few wing ribs; in fact, a certain amount of rib breakage is counted on as the ship settles down and topples over on a wing tip, since its single central skid affords no lateral stability. A well-built glider of this type is so fool-proof that, if in doubt what to do, “ Climbing: Skilled Glider Pilots Learn to Take Advantage of Favorable to rest, the length of the glide Air Currents and Have Reached Altitudes of 2,000 Feet; Below, William H. Bowlus in Cockpit of His Glider the student has only to return his control stick to neutral, in other words hold it vertically between his knees, and the glider will settle gently to earth of its own accord. @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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552 POPULAR MECHANICS Courtesy Holmberg Air Mapping Co. An Aerial View of an Automobile Roller Coaster Where Motorists May Speed Up and Down over the Half- Mile Track and Enjoy All the Thrills of the Old-Time Amusement AUTOMOBILE ROLLER COASTER GIVES MOTORISTS THRILL Thrills for the motorist are provided ‘by automobile roller coasters along some of the widely traveled highways. Near Chicago a farmer has set aside a field be- side an arterial road for construction of a U-shaped track where, for a dime a pas- senger, an automobile party may shoot the chutes and enjoy all the ups and downs of the old-time roller coaster with- out leaving their car. After reaching the top of the first incline, the car is virtually carried over the track by the momentum gained on the declines, and at times travels at high speed. Cars are dispatched one at a time by a starter, and motorists often wait in line for an opportunity to experience the novel trip. VAST GLACIAL TRACT IN ALASKA REMAINS UNEXPLORED Areas of many thousands of square miles of unexplored territory still remain under the American flag. In Alaska is a great tract of land that has never been visited by white men, and even the na- tives have not penetrated some of it. One of the largest of the unexplored regions lies between the Skwentna river on the north and Lake Clark on the south, and between the west front of the Alaska range and Cook inlet. This area, in the south central portion of the territory above the Alaska Peninsula, is entirely occupied by rugged glacial mountains ex- cept for a narrow strip of low marshy land between Cook inlet and the moun- tains. A portion of this territory was invaded by geologists and topographic engineers of the geological survey under considerable difficulties, and an area of about 1,200 miles was mapped. In this new unknown country, where streams are too swift for ordinary boating and the only trails are those made by the native animals, the map makers used the primi- tive methods of transportation, including the pack horse and the boat dragged by hand through swift currents. In one lo- cality, no human being was seen for more than two months, and even signs of na- tive camps indicated that they were from twenty to thirty years old. The animal life remains virtually undisturbed, black and grizzly bears, caribou, moose and mountain sheep being found in abun- Fish, however, are scarce in most streams: because of the large dance. of the amount of glacial silt in the waters.

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POPULAR MECHANICS 553 PULSATING EARTH MAY CHANGE QUAKES Pulsation of the earth, causing it to expand a little, then to contract slightly, may be responsi- ble for the shift of the centers of earthquakes away from the equator during the twentieth cen- tury in the opinion of Prof. T. Terada and Dr. S. Miyabe, of Tokio Im- perial University. Suc- cessive earthquakes in Japan recently have shown a tendency to ap- pear farther and farther north, and the investiga- tors, in trying to find the cause for the slow change in the latitude of the quakes, searched records to find if there had been similar occurrences. They learned that during the sixteenth century earth- quakes in Japan and Eurasia moved south while those in South America moved north- ward, all approaching the equator. About 1600, however, the tendency was reversed and they moved away from the equator, only to move toward it again about 1700 with a reverse tendency noted about 1800. Approaching 1900, the Eurasian quakes again moved south and the South Amer- ican ones north, but as the century opened, they went in the opposite direc- tion. Earthquakes in North America also moved approximately in the same way as others of the northern hemisphere. Two Dutch astronomers have studied the unexpected shifts of the moon from pre- dicted positions on a theory that this might affect the locality of earthquakes, and the Japanese scientists compared these findings with the curves represent- ing the quakes’ movements. Although there is a rough agreement, they think it more likely that the earth itself pulsates over a long period and that these pulsa- tions govern the quakes. Pilots of the Australian Air Force Face This Maze of Controls When They Fly One of the Combat Planes Recently Purchased MAZE OF CONTROLS IN COCKPIT OF AUSTRALIAN PLANE Pilots of the royal Australian air force face a maze of controls when they enter the cockpits of the planes recently con- structed for use there. Besides all the instruments necéssary to operate the ship, there are many others, including a device for operating a message trailer and a ma- chine gun. Had such machines been available earlier, pilots say, they might have been able to save the two flyers who perished in central Australia while seek- ing the airplane “Southern Cross.” WORLD’S FASTEST WAR SHIP Remarkable achievements in French naval construction were demonstrated recently when the “Valmy,” latest war ship constructed under the post-war plans, attained an average speed of 39.85 knots.

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Pian REE SEE Pn ants. 74 SA a - Wrecked off a Wild Part of the China Seaboard, a Steamer Is Being Looted by Bands of Chinese Pirates; This Drawing Was Made from a Central News Photo By HAROLD T. WILKINS bd old-time pirate, with a slash across his face, picturesque gold earrings, and a brace of Spanish pistols, could be recog- nized easily even without the “Jolly Roger” flying at the masthead. But the. modern pirate of the China seas—his equal in fe- rocity and daring—depends for his suc- cess on the fact that his blue dungaree trousers and coat are exactly the same in appearance as those worn by millions of honest Chinese workers. He comes as an ordinary coolie aboard a steamer plying between the ports on the China seaboard. To the eye of the offi- cer who scans him shuffling up the gang- piank, carrying his food and pots and pans, he seems what he says he is—a poor coolie on the way to seek work in another port. He joins the hundreds of other coolies on the open deck and makes him- self as comfortable as the hard planks al- low. To the shipowner he is a profitable + item of cargo and it is not until some months later, when the relative of a wealthy Chinese passenger, captured on that steamer, receives a severed ear or thumb—a hint to forward a remittance promptly or something worse may hap- pen—that it becomes evident the innocent coolie and his equally innocent-appearing brothers were neither profitable nor harm- less. The British government recently has become seriously alarmed at the growing frequency and daring of the buccaneers of the north and south Chinese seas and rivers. A few months ago, a member of parliament proposed that seaplanes should be used to chase pirates in the Chinese waters and deltas, just as the British ad- miralty’s anti-slavery patrol in the Persian gulf, today carries a flying boat armed with bow chaser guns to war on the Arab slave dhows which at night frequently run cargoes of slaves from the Abyssinian . Mae oe er Wenee' et Ue tere “ ORONO, | a om = «© = oe 6 oA eo

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coast of the Red Sea across to the “bad spots” of Arabia. The Chinese govern- ment of Canton has now joined Uncle Sam and John Bull in the war against river and sea pirates in the notorious Canton delta. Recently, an adventure recalling the Middle Ages at their worst, happened in one of these pirate campaigns. After a fierce night attack on a pirate castle in Fu-kien, south of Shanghai, in which the pirates put up a desperate resistance, Chi- nese marines and a brigade of mixed troops stormed a high wall and entered the castle, which has 130 rooms. They found a ghastly torture chamber of huge dimensions, in which forty captives were hanging in chains or bound on tables. The stone pillars and walls were stained with blood. A terrifying assortment of medieval instruments of torture were found. Many hundreds of victims, cap- tured from looted steamers, had been held for ransom in this den, and been killed or maimed. The stronghold was in the mid- dle of a dense forest on an island in Hinghwa bay, and the pirates had carried on their operations for years past. The steamer “Irene,” flying the Chinese flag, was steaming off the Chinese coast recently, bound for Amoy, her captain, J. H. Jansen, a Norwegian, and his second 555

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556 POPULAR MECHANICS officer and engineer at breakfast in the cabin, when a pirate appeared and shot the Chinese steward. Other pirates over- powered the officers, robbed the passen- gers, and made for the bullion room. They collected their loot, and ordered the ship to steam slowly so as to reach Bias bay about dark. A few pirates kept guard, while the rest gambled and gorged below. The “Irene” was creeping into Bias bay, when the pirates got a shock. Anchored under the lee of the land for the night was the British submarine “L-4,” and her cap- tain, seeing a steamer with no lights, sus- pected something was wrong. He flashed out the signal, “Stop at once!” No answer came. The submarine switched on her searchlight, and fired a blank shot. Still no answer. Then the pirates fired on the submarine, which retaliated by firing two live shells across the bow of the steamer. All this time, the “Irene’s” captain was on the bridge, under the guns of the watch- ing pirates, but he rang for the engines to stop. Down below in the engine room, pirates, at the muzzle of the pistol, forced the engineer to keep the engines running. Then a shell burst in the engine room, putting the engines out of action, and dis- abling a pirate who was about to shoot the chief engineer. The submarine’s cap- tain saw men leap off the deck of the “Trene,” so he took the sub alongside and picked up the strugglers in the water. Among the first rescued were six of the European officers. A heavy swell was on the sea, and the “Irene” was now ablaze from stem to stern. The submarine res- cued all the passengers, many of them leaping into the water wearing lifebelts. A radio message brought up the warship “Delhi,” which picked up twelve sur- vivors and stood by to put out the fire on the blazing steamer, while the subma- rine, packed with 222 survivors, left for Hongkong. Twelve pirates were made prisoners. “SOS. This is the steamer ‘Hsin Chi’ in distress. We are beached on Tae island, Foochow. Hundreds pirates round waiting loot ship. Hurry. Can’t hold them off much longer!” The wireless operator on the British destroyer “Serapis” read off this message recently, and rushed it to the captain. A Chinese gunboat, which had also picked up the message, was first on the scene, but stood helplessly by while a hurricane raged Courtesy C. B. D. Lauchan Cruising South China Waters Where Piracy Is Rife Today, an Armed Motor Launch Keeps Vigil over Vessels That Might Fall Prey to Bands of Marauders

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POPULAR MECHANICS Courtesy C. B. D. Lauchan Special Gunboat Built for Rapid Travel in Shallow Waters, Where Pirates Frequently Are Found; the Vessel Is Equipped with Radio and Powerful Searchlights and the pirates looted the helpless steamer. Finally, they set fire to her and fled. Another radio to Hongkong naval de- pot told of the capture of the British 2.200-ton steamer “Tean,” on the way to that port and boarded off the island of Hainan, in south China waters. She had been taken to the notorious Bias bay, where the disguised pirates landed with seven passengers. The British destroyer “Somme” gave chase, causing the pirates to abandon their loot and prisoners, one pirate being killed. The next and latest affair happened in north China waters where the steamer “Shasi” was bound for Shanghai from Hankow. She had left the latter port when thirty-two young Chinese refused to pay the fares which the ship’s compra- dores were collecting. Some of these Chi- nese rushed the wheelhouse, overpowered the captain—an Englishman—the chief officer, the Chinese pilot, and the Chinese quartermaster. The pirates locked the captain in the cabin with his wife and two children, while the ship was left to drift helplessly. Later, the pirates unlocked the captain’s prison and ordered him to let go his anchor. They then rushed the cabins of four first-class passengers. Off Seven Miles creek, a launch came alongside, and the pirates, loaded with loot, consisting of the plundered cargo, the passengers’ money and _ jewelry, went on board, complaining bitterly that their booty was worth only $10,000 or so. No sooner had the pirates left, than the cap- tain of the plundered steamer returned to Hankow. A fortnight later, the Chinese authorities executed sixteen of the pirates who took part in the looting of the “Shasi.” DEEPEST FRESH-WATER LAKE Lake Tanganyika in central Africa, be- lieved formed in the craters of an extinct volcanic range, claims the distinction of being the deepest fresh-water lake. Depths of 4,190 feet have been located in various parts of the lake, which is 200 miles long and forty miles broad.

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558 POPULAR Diagram of Human Ear and Drawing Illustrating Nature of Tailspin “WE WENT INTO A TAILSPIN—SOS —WE CAME OUT OF IT, BUT WERE SURE SCARED. IT WAS A CLOSE CALL. WE THOUGHT IT WAS ALL OFF, BUT WE CAME OUT OF IT. THE LIGHTS ON THE*INSTRUMENT BOARD WENT OUT, AND IT WAS SO DARK THAT BILL COULDN’T SEE THE...WE ARE IN ANOTHER—SOS—” In the middle of the sentence the wireless transmitter was stilled and two more ocean flyers, Erwin and Eichwaldt of the “Dallas Spirit,” had plunged into the Pacific while bound for Hawaii seeking traces of two lost planes. For the first time the occurrence of a dreaded tailspin had been actually reported at the moment it happened. That was in 1927, and the same year forty per cent of all the fatal accidents to army planes were due to spins. In the last five years forty-five per cent of navy airplane accidents have been due to the same cause, The figures were compiled by Lieut. Carl Brown Harper, U. S. N., who has been making a study of spins, their causes, and means of preventing them. Why a spin is so dangerous is easily told. The inner ear is affected, the waterlike liquid which it contains, is set in motion, nerve im- pulses are transmitted to the brain, and from there down to the eyes, and the eyes begin to oscillate from side to side. The pilot, realizing he is in a spin when the stick tries to force its way back into his chest, shoves it forward and applies oppo- MECHANICS WHY THE DREADED TAILSPIN IS SO OFTEN FATAL site rudder to bring his ship out, but hav- ing done so his eyes continue to oscillate, until they make him believe he is still in the spin, with the result that he keeps on holding the stick forward and the rudder over until the plane goes into a second and opposite spin. But, more dangerous still, the pilot, even when provided with a parachute, cannot leave his ship dur- ing the spin, because centrifugal forces during the gyratory movement have mul- tiplied his weight by four. The only way he could escape from his craft would be through a trapdoor in the floor, and the navy is now studying that problem. An airplane in a tailspin describes an unusual course. Imagine a giant screw, with threads of enormously long pitch and small radius. Hold the airplane with nose down, the propeller against the screw, and the tail sticking upward at an angle oi sixty or seventy degrees. Now revolve it around the screw. It describes small cir- cles, because of the small radius, but de-

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v- te, in yn er id th r- es i1- iv 1e in al POPULAR scends rapidly, because of the great pitch of the threads. That is exactly the. course of an airplane in a spin. Spins usually result from trying to climb too fast, with the result that the engine is unable to pull the weight up the steep aerial hill; the speed falls to the stalling point, and, lacking sufficient forward speed to give control, the craft falls off on one wing. Wing slots, small movable flaps curved to fit the leading edge of the wing, can prevent a spin by flapping open and increasing the lift on the lower wing. The Amer- ican rights to the slots have.been purchased by the government, and experiments are being carried on by the navy to improve their design. One problem has been the necessity of provid- ing some means of lock- ing the slots so the mil- itary pilot can render them ineffective when he wants to deliberately spin his ship in fighting maneuvers. THREE TESTS FOR OLD RUGS Rug collectors hunting old and valuable pieces are given three simple tests by an English expert, to determine rug quality. A wet handkerchief rubbed over the rug will determine if the colors are fast. lf the color rubs off on the handkerchief the design may be spoiled. Examining the inner strands determines if they are of the same color as the outer ones and if the design extends through the thickness of the rug, and a marked sheen or dull polish to the fiber usually indicates that the rug is more than fifty years old and so of good value. Lastly, the rug should be exam- ined for moths, cuts, or worn places. BOX CAR WITH REMOVABLE TOP ENABLES EASY LOADING Top-loading freight cars with remov- able roofs are being used by a railway in Sweden, it having been found that when package-loaded by derricks, they can be filled much more rapidly and easily than the side-loading type. The cars also re- tain the side doors for service when equip- MECHANICS 559 Loading Box Cars in Sweden Is Facilitated by Tops Which May Be Removed as Shown Below ment is not available for lowering freight from above into the car. The roof is di- vided lengthwise in two quadrant-shaped segments which can be let down, one on each side. A shaft along the top of each car side with pinions at the ends works on a gear rack under the segment and is connected through a bevel gear to a ver- tical shaft which has at the bottom a worm gear with a crank that is easily reached from the ground. @Coal can now be rendered dustless by the use of certain chemicals sprayed on it.

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POPULAR MECHANICS Two Views of a Self-Dumping Scow Operated by Flooding Air Chambers, Whereupon the Bottom Becomes the Top for the Next Load SELF-DUMPING SCOW CAPSIZES AND BOTTOM MAKES DECK Scows of 800 tons’ capacity which un- load automatically by overturning, where- upon the bottom of the loaded barge be- comes the deck for the next load, are be- ing used successfully in excavating oper- ations in Seattle. The top and bottom of the self-dumping barges are identical and the sides are built up for holding the dirt, while inner wooden tanks on either side serve the purpose of flooding. The load forces the air-tight chambers be- neath the water line. A one-man tug tows the scow to deep water, the tug oper- ator pulling open the valves on one side with a line. This shifts the center of gravity as the water rushes into the opened cham- ber, and the scow overturns. Dumping of the load raises the air chamber above the water line and the water runs out. With the valves closed, the scow is ready for the next load. Unloading is accom- plished in less than four minutes, the tug continu- ing on its course as the scow is overturned. BLACK FENCE POST TURNS WHITE EVERY NIGHT A man’s puzzlement over a fence post, which he had painted black but which turned white every night, was the starting point of a program of re- search which has culmi- nated in the discovery of a number of chemicals having this remarkable chameleonlike property, scientifically termed pho- totropy. The famous fence post was painted with a “pigment having a zinc basis.” It would turn black soon after sunrise each morning, only to turn white again when darkness came. Many explanations have been given for the phe- nomenon but scientists are not yet agreed as to the cause of it. They have, however, found several other substances besides the zinc sulfide, which was in the paint on the post, that will also change color with the light. Most of the known phototropic liquids are solutions of colorless derivatives of certain dyes. BRAND CATTLE WITH SQUEEZER Operating like the old-fashioned V- shaped lemon squeezer, a cattle squeezer is being used to expedite stock branding in Nevada. Animals to be branded are driven into the open end of the V-shaped contrivance one by one, after which a lever closes the sides until the imprisoned animal is unable to move and scarcely a minute is required for the branding oper- ation. For dehorning, a headpiece is pro- vided also and is adjusted after the animal no longer is able to struggle. Cattlemen say the “squeezer” more than doubles the daily output of a branding gang.

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POPULAR MECHANICS 561 PORTABLE STAGE ON WHEELS MOVES ON RAILS Built on wheels fitted to steel rails, a portable stage and canopy has and the canopy is covered with mate- rial which adds to the acoustic quali- Placed on Wheels Which Move along Steel Rails. This Portable Stage for the Hollywood Bowl, with Its Ten Arches Decreasing in Size, Has the Appearance of a Huge Bonnet been constructed for use in the Hollywood Bowl. The movable stage makes possi- ble a canopy-covered platform for or- chestra work and an open stage with nat- ural sylvan background for drama and dancing. The shell consists of a series of ten arches decreasing in size, giving the proscenium somewhat the appearance of a gigantic bonnet. Dressing rooms are provided on each side so that the width of the movable unit is about 120 feet and the depth sixty feet. The framework is steel, ties, while lights are set in the flanges sep- arating each of the series of arches. The structure is supported by wooden girders to which are attached flanged wheels which in turn are supported by steel rails. By means of a small engine, the prosce- nium unit may be pulled up into a canyon wholly out of view. The only connection between the structure and the ground is the wiring and the plumbing and these may ‘be disconnected with little trouble. A fanlike curtain is used for the canopy. AIRPLANES REPLACING BURROS IN LATIN AMERICA Airplanes are replacing burros and other crude forms of travel as a means of transportation in Mexico. and other parts of Latin America. Here today the airplane is being used where before primitive forms of travel prevailed. Air lines extend from the Texas border to the oil fields of Tampico, Tuxpan and Mexico City, while from Vera Cruz one may go to the Isthmus of Tehuantepec or to Tapachula on the Guatemalan border, or to Yucatan by way of the almost un- known coast of Tabasco and Campeche. A branch line is planned from Merida across Yucatan to Cozumel over territory inhabited entirely by hostile Indians, and the Guatemalan government has a line from Guatemala City to Flores. Mexican air lines from Tapachula, in the south, soon will be extended to Guatemala City and mail will go from Texas to Guate- mala in twelve hours. From there, the Republic of Salvador and the Pac?fic side of Nicaragua are to be linked by air with the Atlantic side. At present one may fly from Florida to Santiago, Chile, and before the year is ended, the journey may be continued across the Andes to Buenos Ayres, Argentina

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Combined Rail-Air Service Now Transports You from Coast to Coast in Less Than Forty-Eight Hours; Twentieth Century Lim- ited Salutes a —* Passenger ne Copyright, Ralph Rugh

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Above, the “Robin” Which Stayed in the Air for Over 420 Hours at St. Louis, and, Below, One of the Refueling Contacts That Made the En- durance Flight Possible; dur- ing Refueling, a Speed of Sev- enty Miles an Hour was Main- tained at 3,000-Foot Altitude

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564 POPULAR Above, the Monoplane “Yellow Bird” on the Beach at Comillas, near the French Border, Where It Was Landed after a Flight across the Ocean from Old Orchard, Maine; at Right, Leo Nomis Testing a High- Pressure Grease Gun Used on His Endurance Flight with Maurice Morrison, Which Ended after Forty- Two Hours When the Ship Crashed MECHANICS Charles W. “Speed” Holman in the Laird Biplane Which He Flew at the Rate of More Than 156 Miles an Hour over the 468-Mile Course between East St. Louis and Indianapolis and Return, to Win the First Gardner Trophy Race for Commercial Air- planes and a Cash Prize of $5,009 7 co vere a Se a” see ee

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POPULAR MECHANICS Gasoline, Food and Water Are Necessities for the Successful Endurance Flight and the Re- fueling Ship and Its Crew Play an Important Part in Keeping the Plane in the Air; Upper Right Shows a Refueling Plane Making Contact over Los An- geles with the Endurance Ship “Angeleno” (Lower Left); in Oval, Capt. Frank Hawks, Who Smashed Records by a Round-Trip Flight from New York to Los Angeles and Re- L turn with One Stop for Fuel 565 Space Is Ever at a Premium in Passenger-Carrying Ships, Partic- ularly When It Comes to Bag- age; the Transcontinental Air ransport Planes, Carrying Pas- sengers on the Air Portions of the Coast-to-Coast Rail-Air Route, Solved the Baggage Problem by Providing Space for It in the Wings; Above, Transport Em- ployes Are Loading Bags into the Wing of the “City of Columbus” before the Initial Rail-Air Trip

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POPULAR MECHANICS Altitude Flyers Must Carry Their Air Supply Along; Right, Lieut. Apollo Soucek with the Apparatus He in His Recent Record Flight Women Are Manifesting an Enthusi- astic Interest in Aviation, as Is Evi- denced by Their Use Daily of Air- Travel Facilities, and the Fact That They Have Gone In for Not Only Transatlantic Flights but for Endur- ance and Altitude Records as Well; Above Is Shown Mrs. Louis Thadden, a California Woman, Who Stayed in the Air over the Oakland Airport for More Than Twenty-Two Hours to Establish an Endurance Record for Her Sex, While at the Left Is Pic- tured Miss Marvel Crosson, Another California Girl Pilot, Who Took a Cabin Monoplane to an Altitude of 24,000 Feet in an Effort to Set a Rec- ord for Height for Other Women Flyers to Emulate

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POPULAR MECHANICS 567 — Above, the “City of Columbus” Ready to Take the Air at Port Columbus, Ohio, Thus Inaugu- rating Coast-to-Coast Rail-Air Pes] Service; with Many Notables 9 | = a Taking Part in the Ceremonies, >5 ca ee - ; , Air Passengers Arrived from ed . : ul New York on the Pennsylvania “Airway Limited” after an Over- - _- night Ride, Walked from the \ Station under a Canopy to the Hangar of the Transcontinental Air Transport, Where a Plane Was Waiting, and after Flying throughout the Day, Resumed Their Journey Westward by Train in the Evening; Below, One of the T. A. T. Planes Fly- ing over Los Angeles ae

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POPULAR MECHANICS OULF of wWERICO All the Luxuries of the Finest Train or Ocean Liner Are Found in the Passen- ger Compartments of the Coast-to-Coast Airplanes; View Looking toward the- Forward End of a T. A. T. Plane Filled with Passengers Octan aveanric The Map Shows the Coast-to-Coast -Rail- Air Route with Shaded Portions Indicating a Travel by Train and Light Parts the Distances Covered by Air during Two Days; Passengers Leave New York in_ the Evening, Take Planes from Columbus, Ohio, the Next Morning, Resume Train Travel the Second Night, and Transfer to Airplanes for the Pacific Coast at Clovis, N. M., the Second Day Coast-to-Coast Rail-Air Passengers Make the Air Portions of Their Journey as Comfortably as in a Pullman; at Left Is a Chair in the Plane’s Passenger Compartment

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POPULAR MECHANICS Above Is the Bellanca Mono- plane “Pathfinder,” in Which Roger Q. Williams and A. Yancey Flew to Rome after Failing with the “Green Flash” ; Right, Mechanic Is Weighing the Lockheed Mono- plane in Which Lieut. Harold Bromley Crashed at the Start of a Non-Stop Flight to Japan, the Weighing Being Done to Insure Accurate p Bane! =—— : _J Flights across the Atlantic and Pacific Oceans Still Challenge the Most Daring Aviators of the World; Above Is the Amiot Plane “Marshal Pilsudski,” in Which the Two Polish Flyers, Ludwik Idzikowski and Casimir Kubala, Made Their Unsuccessful Attempt to Fly from Europe to the United States without a Stop

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POPULAR MECHANICS Above, the French Plane “Yellow Bird,” at Old Orchard, Maine, Taking on Gasoline Before It Hopped Off on the Flight Which Eventually Brought It to Paris with the Three French Airmen and an American Stowaway This Shows a Close-Up of the Monoplane “Yellow Bird,” Being Towed to the Top of the Runway by a Tractor, Preparatory to the Successful Transatlantic Flight of the French Flyers, After the Ship Had Made a Previous Start and Been Forced to Turn Back Above, the Instrument Board of the Single-Motored “Yellow Bird” on Which the French Avi- ators, Jean Assolant, Rene Le- fevre and Armeno Lotti, Jr., Re- lied for Their Successful Trans- atlantic Flight; Left, Mechanics Repairing a Dump Valve Which Was Damaged during the First Attempt of the Frenchmen to Get Away, Necessitating a Re- turn for a Second Start LS = h=3=— rl i tC 2 . 7 — 3 . , | eee tian? a

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POPULAR MECHANICS Right, a Smiling Close-Up of Miss Smith Before She Started on Her Solo Endur- ance Flight, While Above Are Shown Two Other Endurance Flyers, Pete Reinhart and Loren Mendell, Who Flew over Los An- geles in the “Angeleno” to Make One of the Several Endurance Records Established in the Last Few Months, Only to See Their Mark Shattered a Few Weeks Later Above Is Shown the Crowd Welcoming Miss Eleanor Smith, Nineteen-Year-Old Girl Aviator, Seen Leaving Her Plane at Roosevelt Field, Long nd, After Making a Solo Endurance Flight of Twenty-Six Hours and Twenty-One Minutes to Better a Mark Set by a California Woman

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572 POPULAR MECHANICS NINN e Leet aeee Above, Three of the Twelve Motors of the “D. X.” Which Lifted the Plane off the Water in a Trial Flight in Twenty-Eight Seconds, and, Be- low, the Mechanism Which Operates the Motors At the Top, the “D. X.,” the World’s Largest Flying Boat with Three Decks, Twelve Mo- tors, and a Capacity for 100 Passengers, as It Looked on Lake Constance in Germany Prior to Successful Tests

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'ao Se Oo POPULAR MECHANICS Above Is a Model of Germany’s Bid for Air Supremacy, a Three-Deck Dornier Flying Boat, the Largest in the World, Which Was Recently Launched After More Than Two Years Had Been Spent in Building It; Its Twelve En- gines Develop 3,000 Horsepower 573 Below, Model Showing the Proportions of the Dornier Craft; the Gigantic Air Liner Is the First of Several Huge Craft Which Are Being Planned with a View to Estab- lishing Speedy Mail and Passenger Service between Hamburg and the United States Top Photo © P. & A. Close-Up of the Dornier Three-Deck Flying Boat, Showing Some of Its Twelve Engines, Which Propel the 137-Foot Craft with Its Wing Spread of 157 Feet at a Rate of 155 Miles an Hour; the Craft Can Carry 100 Per- sons and Has Salons and Luxurious Sleeping Accom- modations for Sixty

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574 POPULAR MECHANICS The Map Above Indicates the Dis- tance the Los Angeles Endurance Flyers, Mendell and Reinhart, Would Have Traveled around the World in Their Plane, the “Angeleno,” If They Had Flown Straight East In- stead of Hovering over the City; Following the Los Angeles Parallel They Would Have Crossed the United States, the Atlantic Ocean, All of Europe and Part of the Pa- cific Ocean, or Nearly 18,000 Miles; at the Left Are Some of the Empty Gasoline Cans Used by the Ship A Secret of the Long Endurance Flight of the “Angeleno” Was the Invention of the Flyers Themselves for the Auto- matic Lubrication of the Rocker Arms; the Photo-Diagram Above Illustrates How the Engine Received Its Oil o°'\o "_ re lL ee ee

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POPULAR MECHANICS 575 This Picture, Taken at Its Christening, Shows the Mighty Steering Fin of the Giant Dornier Plane Built in Germany, the World’s Largest; Its Size May Be Estimated by Comparing It with the Persons on the Ground; Its Twelve Motors Will Carry a Load of 100 Passengers, and It May Be Used as an Air Liner between Germany and America

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576 POPULAR ’ A Barbecue Roaster Which Turns the Meat Auto- matically, Saving Labor and Meat Shrinkage AUTOMATIC BARBECUE ROASTER SAVES MEAT AND LABOR Operated automatically, a barbecue roaster for the roadside stand cooks and bastes meat, leaving the owner free to wait on customers. The MECHANICS safety curtain suspended before the fire descends if the roasts quit revolving or the mechanism stops functioning, thus preventing burning or spoiling the meat. Twenty chickens or 150 pounds of meat may be prepared at one time. INFLATING BIG BRITISH AIRSHIP REQUIRES SIX WEEKS Inflating the gas bags of Great Britain’s latest airship, the mammoth “R-101,” un- der construction at the Cardington Royal Airship works, lasted more than six weeks. The big bags above the passengers’ quar- ters were first filled and more than two months’ production of the works’ gas plant was required. ELEVENTH FINGER FOR ORGAN GIVES ADDED TONE EFFECT Deciding that the ten fingers of the hands and all the stops on the modern pipe organ did not suffice to produce the blend of sound of which the instru- ment is capable, a New York organist uses an eleventh finger manipulated b, moving his head. This mechanical digit consists of a band fitting snugly about the head, to which is attached a rod curved downward at the end and long enough to reach the ,third or fourth manual, The organist uses the eleventh finger to sustain or play a melody on one of the upper manuals, and his hands for variations and second-touch effects. roaster is contained in an Curved Rod Fastened all-metal house, ‘and the roasts are hung on spits which revolve in a ver- tical plane in front of an open coke fire, an elec- trically operated mech- anism keeping the meat turning at regular in- tervals. The basting re- duces the shrinkage, which, in ordinary meth- ods of roasting, some- times runs as high as fifty per cent. A time clock attached to the electric motor rings when the roast is finished, and a the Organist to Headpiece Provides Eleventh Finger for th th to S” ge bo we to wh ga:

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co * J i oF —_— -_- - POPULAR iva | = poor] $ a Oe tae — ts | Si ee 4 eee | a pall os a epee . 4 MECHANICS 577 a $$ Pi at UA! i € nN om « ence eee, , yer tp od The Lower Part of This Betting Machine on Wheels Is Composed of Booths Where Wagers May Be Placed, While on the Roof Is a Quick-Totaling “Pari-Mutuel’”’ Machine BETTING MACHINE ON WHEELS PLEASES RACE FANS English racing fans are hailing a porta- ble quick-totaling “pari-mutuel” machine carried on the top of a truck, the lower section of which is given over to the wagering. Tickets on horses are issued and from each side of the car the turf en- thusiasts immediately see the totals on the big adding machine, which the inven- tor calls a totalisator. STEAM TURBINE FOR AIRPLANE TO REDUCE COST Steam may enter the air as the source of power for extra-large airplanes, as plans have been prepared for a steam turbine for aviation by Swedish engineers at the request of an American manufacturer. By using a high-pressure boiler fired with crude oil and a high-speed turbine, the Swedish engineers expect to develop from 2,000 to 10,000 horsepower, a single boiler supplying steam for two turbine units geared to as many propellers, or two boilers for four propellers. Already the weight of these turbines has been reduced to less than two pounds per horsepower, which is about the same as the weight of gasoline engines now used on planes, and less than that of the recently developed Diesel engine for aviation. The weight of the fuel required to make steam would be greater than in internal combustion en- gines, but the cost would be less as lower grades of crude oil would be used. The steam would be condensed and returned to the reservoirs. SHAPER FOR THE SMALL SHOP IS EASILY CARRIED Intended for the small cabinet or car- penter shop, and for schools, a portable electric wood shaper has been placed on the market. It is upright, direct motor- driven, beltless and ball bearing, and so designed that lubricants cannot reach the motor. The table |g is mounted on a — screw on which it raises and lowers, and the spindle has a capacity of two and one-half inches between two steel shaper collars, or three and one-quarter inches, using solid cutters. A combination guard and fence is part of the equipment.

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578 POPULAR MECHANICS ee ld Te 44 ; ar ae a to Dot Lh WW AL Wil Lh mee al monoplane in which ex- penses were less than three cents a mile. The flyer covered 17,124 miles and visited fifty cities. During the trip the ship was flown in 330 demonstrations by 108 pilots who covered 9,278 miles, while cross-coun- try flights accounted for the rest of the distance, the ship landing and tak- ing off 410 times and car- rying 656 passengers. Gasoline, oil, storage, service repairs and all in- cidentals totaled $456.61. The flying time was 174 hours and thirty-six min- utes, the cost per hour being $2.61. The average speed was about ninety- eight miles an hour. TEX errr Rl Ghecee ou a al ae . io cad ¥ CASEMENT LOCK IS BURGLAR-PROOF Depending on gravity and an eccentric pin for security, a casement lock has been made that can- Uncle Sam Keeps Daily Tab on the Location of Each of His Fighting Ves- sels by Means of This Ship Chart SHIP CHART SHOWS POSITION OF NAVAL VESSELS Uncle Sam keeps daily tab on the exact location of every ship in the fighting fleet by means of a huge blackboard in the navai-operations office at the navy depart- ment in Washington. The ship chart, or location board, shows the daily battle- fleet maneuvers so that, at any given time, the department knows where each one of its fighting vessels may be found. UPKEEP OF A SMALL AIRPLANE SAME AS THAT OF AUTO Upkeep of a small airplane compares favorably with the operating cost of an automobile, on the basis of distance cov- ered, an official of a flying service has decided after a demonstration trip in a not be opened from the outside while the same principle is applied to make the casement itself water-tight. The window, when closed, is made water- tight by a rabbeted stool and tongue-and- groove machining for the meeting sides. An eccentric pin in the operating handle, placed below the window sill, raises the casement out of the lower groove so that the window may be opened fully inward. A slotted guide in the han- dle allows for both horizontal and vertical mo- tion of the case- nent. When closed, the case- ment drops into the bottom groove as the eccentric pin releases it when the handle is turned.

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\- ie ie 7 he ithe |ceber By EARL CHAPIN MAY NE night in April, 1912, the palatial “Titanic” on its maiden voyage struck an iceberg near the Grand Banks of New- foundland. More than 1,500 human be- ings lost their lives in the greatest mari- time disaster of the century. Since that tragedy no transatlantic liner has collided with an iceberg. Complete avoidance of collision between fast-steam- ing ships and wandering remnants of Greenland’s glaciers is due to the effi- ciency of the International Ice Patrol for which the United States coast guard is responsible. From the first of each April to the last of June, the offsprings of the Greenland ice cap slide into Davis strait and Baffin bay, float southward with the Labrador current and, between Newfoundland and the neighboring Gulf Stream, become men- aces to shipping. To avoid this danger, ships between Europe and America have been run in “traffic lanes.” They began doing it when 300 people lost their lives by the collision of two ships off Cape Race in the early seventies. Since then, east- bound liners are allowed to cruise only in a lane sixty miles wide from north to south; westbound liners keep in their own lane just north of this. Since the “Titanic” disaster, United States coast guard cutters, have often shifted these travel lanes to keep liners away from drifting icebergs. The cutters direct shipmasters by radio. If captains ignore warnings, they are disciplined by ship owners. The ice patrol knows its business because it makes a scientific study of icebergs. Ice patrolling is a risky business. It offers plenty of variety. For example, the number of menacing bergs varies in size and number annually. About 350 of them get south of Newfoundland each spring—on the average. Yet, in the year of the “Titanic” disaster, 1,200 were iden- tified in shipping lanes. Some have been seen as far south as the Azores, but they seldom last more than three days when they get into the warm Gulf Stream. Once spotted, as it rounds the south- east corner of Newfoundland, a berg, no matter how formidable, is shadowed by a coast-guard cutter. This is relatively 579

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580 POPULAR easy in fair weather. When a fog shuts down, human eyes are valueless in iceberg hunting. I’ve known a patrol boat to sight a block of ice 1,700 feet long and, though only sixty-five feet high above the water, weighing some 36,000,000 tons. Just as the cutter approached to make more detailed examinations, a fog has shut down and the 1,700 tons of ship has had to feel its way about. Testing temperature of air and water does not give sufficient warning of a berg’s loca- tion. On one occasion the “Mojave” found the water registering sixty degrees from a distance of two miles to within one hundred feet of a berg. Each year the coast-guard cutters study and plot berg-carrying currents over an area equal to that of Pennsylvania. Cur- rent plotting is done by comparing sub- surface temperatures. When a coast- guard vessel is “dead” in the water, the crew lowers a fine wire into the ocean. At intervals, marking water levels, a bot- tle is attached. There are usually seven bottles between the surface and the great- est depth, 750 meters. After this length of line is payed out a weight, called a “messenger,” is dropped down and suc- _ cessively trips each water bottle, causing it to fill, while a thermometer records the MECHANICS water’s temperature. The wire and bottles are then hauled on board, the bottled wa- ter siphoned into an electric salinometer and the saline contents or solid salts meas- ured accurately. Temperature and salinity are then converted into terms of specific gravity, and the currents are calculated from the latter. Having determined the drift of current and made due allowance for wind drift, the ice-patrol ship com- mander can come pretty close to telling where a berg will be twelve hours hence. He can also tell by observation and ex- perience how much the berg will lose from erosion by waves and from melting. Many attempts have been made to aid nature in disintegrating dangerous ice- bergs. Coast-guard cutters are well armed. Five-inch guns are carried by most of them. These five-inchers have bombarded icebergs without any effect on the mass of ice. Fifty-pound guncotton mines were equally ineffective. Only cur- rents, wave erosion and warm water can put the flcating islands out of business. .The protection given shipping by patrol ships is 100 per cent valuable partly be- cause of radio. Hundreds of weather re- ports are sent and received. If any vessel wants special information, the cutter promptly radios it. Each spring about The U. S. S. “Mojave,” Having Located an Iceberg, Proceeds to Take Measurements as to Its Speed of Drift, Determined by the Ocean Current and, to a Degree, by the Wind 300. mas war Eur as ¢ Fel Ma upo fro: ice was and cut wai tak Wa: gay cas Th anc boz abc

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POPULAR MECHANICS 581 Plunging through a Heavy Sea on an Iceberg Hunt; the “Mojave” Forges Ahead in All Sorts of Weather, to Guard Other Vessels against the Iceberg Menace 300,000 words are thus masters have learned to respect these warnings. In summer time, New York- Europe liners, cruise over what are known as courses A and B. From September to February 1, they cruise on courses C and D. During the normal ice season, from March until June, they may be shifted, upon recommendation of the ice patrol, from track B to track A, if the drift of ice is extra southerly. One night last May, the “Aquitania” was running at a speed of twenty-two and a half knots across the Grand Banks. Her course, as given to the coast-guard cutter, indicated that she was headed to- ward the position which would soon be taken by the southernmost berg. She was also headed into a fog. The cutter gave her a special warning, then broad- cast information about the drifting berg. The liner promptly altered her course— and proceeded safely. The thousands on board the “Aquitania” knew nothing about the cutter’s work. handled. Ship By ceaseless vigilance and daring in fog, wind and cold; by weeks of cruising in dense fog; by long days and nights on the bridge with the fog whistle blowing dou- ble blasts at two-minute intervals so that liners may keep clear of them, the patrol boats keep safe the great - transatlantic lanes of travel. GOLF-BAG CONTAINER FOR CAR HELD ON RUNNING BOARD Stowing golf bags in an auto- mobile is simpli- fied by a holder which is attached to the running board. The outfit has a capacity of four bags, is chro- mium-plated and can be detached easily when it is not wanted.

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=e ase ao cud 582 POPULAR One of the secrets of the 28.5-knot speed attained by the German ship, “Bremen,” the larg- est motor-driven liner afloat, has been disclosed by pictures taken while she was in drydock which show that the vessel has a rudder shaped dies MECHANICS RUDDER SHAPE SECRET OF GREAT LINER’S SPEED Dr. Max Oertz, German hydroplane maker, who was associated with the late Count Zeppelin, airship designer. The airplane wing-type of rudder has been tried previously in single- screw freight steam- ships, where it was found to increase Here Is the German Liner, “Bremen,” Fastest Steamer Afloat, in Drydock Before Her Record-Breaking Trip to America; Note the Propellers, and the Rudder Shaped Like an Airplane Wing like the wing of an airplane, on the streamline principle. The streamline rud- der of the fast 50,000-ton ship, navigators explain, increases effectiveness in steer- ing, and reduces eddies and currents which interfere with the propellers, thus minimizing resistance to the speed of the boat. The rudder was designed by speed from four to eight per cent and to save ten to fifteen per cent in fuel. The “Bremen,” however, is the first passenger ship to be so equipped, and if the airplane rudder continues successful on this vessel, it may be adopted by other ships which deem speed and fuel-saving essential to successful operation. ARE YOU RIGHT OR LEFT-EYED SHOWN BY TESTS Are you right-eyed or left-eyed? This question is settled by a vision test through which an experimenter may determine whether an individual looks with the right or left eye. The ‘test is so simple that it can be tried on children, and groups can be tested at one time. In sixty-five per cent of persons the right eve is dominant, thirty per cent are left-eyed, and five per cent have mixed vision. About fifty per cent of left-handed persons have been found to be left-eyed, and the relation be- tween eyes and hands is considered sig- nificant, but still obscure. Double vision, the inevitable outcome of having two eyes, is overcome by ocular dominance in which the right of way is given to the image of the dominant eye, that of the other eye tending to be suppressed. solu tery wat pre star bur: free com cost AE] Si Day aeri The half the to | The regi oft the is €| low take feet mot dem valt Star cau: are larg

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POPULAR NON-LIQUID STORAGE BATTERY REDUCES MOTOR TROUBLES Filled with a solidified sulphuric-acid solution, instead of liquid, a storage bat- tery now on the market requires distilled water but once every three months. It prevents the formation of injurious sub- stances, eliminating the likelihood of burned plates, and the battery cannot freeze under any conditions. Taxicab companies claim it reduces their battery costs nearly fifty per cent a year. AERIAL CAMERA SHOWS DETAILS OF GROUND FROM ALOFT Successful tests recently were made at Dayton, Ohio, with the world’s largest aerial camera which weighs 130 pounds. The film is 150 feet long and nine and one- half inches wide. An instrument times the interval at which the photographs are to be taken and trips the camera shutter. The film is wound automatically and a registering apparatus notes the altitude of the plane, the time of day, the date and the number of the negative. The camera is electrically heated so it will function in low temperatures. The first photograph taken was from an elevation of 18,300 feet. The possibility of obtaining colored motion pictures from the air also was demonstrated with another camera. The value of the color pictures from a military standpoint thus far has been limited be- cause of their small size, but experiments are being made with a view to producing larger pictures. World’s Largest Aerial Camera Which Gives Ground Details at 20,000 Feet MECHANICS A Light German Car Constructed with a One-Cylinder Engine, and the Motor in the Rear SINGLE-CYLINDER AUTOMOBILE HAS MOTOR IN REAR Built with a one-cylinder engine and the motor in the rear, a light and compact automobile turned out by a German man- ufacturer presents a strange contrast in appearance to the American car. Aside from the reverse position of the engine, the body itself is original in design. A coupe has a removable top, and a single- seated car designed for a cab has the pas- senger’s seat beside the driver with a glass panel separating them. A single light is built into the middle of the hood, and the body itself is contoured so as to form the fenders. PLANE SMOKERS START FIRES Lighted cigar and cigaret stubs thrown from airplanes may start forest fires, for- est rangers have determined after a series of tests. As a result, forestry officials have issued warnings to pilots and air passengers against throwing any sort of burning material from the ships.

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a no one nes a Sapa sere carne ae Ga te ener tonr in 584 POPULAR MECHANICS DRIVE-IN MARKETS HELP SOLVE TRAFFIC PROBLEM pods ot ss Fee Drive-In Markets to Accommodate the Motorist; This One Is Built in Spanish Style to Harmonize with Surrounding Residential Section and Helps to Solve the Parking Problem Showing How Easily Cars Leave the Highway to Reach the Market and, Below, Drive-In Store of Chinese Architecture

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POPULAR MECHANICS 585 FORGED STATUARY IS DETECTED BY VIOLET RAY Ultraviolet rays are being tried out by the Metropolitan museum of art to supplement the connoisseur’s “sixth sense” in detecting fake marble antiques. In the past, X-rays have been tested with some _ suc- cess. Museum officials who are using the ultra- violet ray on marble said it has possibilities which are not limited to this field zlone. The use of the rays is made possible because objects exposed to this light tend in vary- ing degrees to reflect the purple rays. Ex- periments have shown that the color of old marble under the rays was different from that of freshly cut marble, as its luminescence was of a different color. ROUND SAW TO CUT PLASTER Intended particularly for cutting plaster or artificial stone, a round saw blade has barbs cut about its circumference and is used in an ordinary hacksaw handle. It cuts rapidly and may be used for circular or irregular designs where it does not fracture the work. It is useful in making ornamental articles from plaster. TENNIS BALL SEALED FROM AIR UNTIL READY TO USE Tennis balls are kept fresh and pre- served from deadening by a viscose cover that is shrunk onto the ball, contracting it and removing the inflation pressure from the walls. The cover also seals the Race Horses Must Have Sound Hearts, and the Machine Pictured Utilizes Light Rays to Test the Thoroughbreds HEART OF RACE HORSE TESTED BY LIGHT-RAY MACHINE Race horses, like boxers, must undergo a physical examination to determine their fitness for competition, including for year- lings, a heart test for congenital abnor- malities or other disorders. An official of the thoroughbred institute has made a de- vice which utilizes light rays to deter- mine the racer’s soundness of heart. - The machine somewhat resembles a radio set. “DRY ICE” CAUSE OF INJURIES One of the latest hazards in connection with the development of new industrial processes is that arising from the use of “dry ice,” says the department of labor. Dry ice is used by ice-cream plants and dairy companies to pack their products, having an estimated temperature of 110 degrees below zero and being capable of producing a serious injury if carelessly handled. The ice, made from carbon ball, preventing air and moisture from oxidizing it. The seal is removed by running a cutter un- der the seam, and, when bounced, the dioxide, is delivered as cubes which are shaved into, small pieces to suit the users. Handling the ice with bare hands, despite warnings, ball resumes nor- mal shape and size. Viscose Cover Shrunk on Tennis Ball Removes Infla- tion Pressure until It Is to Be Used has resulted in the injuries.

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Ce iting: Repti stay Upecap— Rpe 2 ple ap tee. AR eRe oA ta Ate. Sor a oh RECS cert Pan-American Airport Station and Typical Tri-Motor Ship with Its Three-Bladed Propellers; Note the Cov- ered Passenger Lane and the Roomy Observation Platform By J. EARLE MILLER PART II = HEN it’s rough aloft,” says a recent advertisement, “or the report says dirt above the Alleghenies..:or ice and fog over the Hump...then only master pilots should take to the skyways.” How to become a master pilot is a problem that is engaging the attention of a large part of the youth of America. One of the largest factories has its own system, which consists of taking men with hundreds of hours of solo experience, starting them in the factory bucking rivets, and putting them through every branch of the work of building an air liner, with a finishing course oi flying the ship. Five hundred hours as a pilot is the minimum requirement for entering the school.- How to get that 500 hours, or how to work up the hours required for any of the better-paying pilots’ posts, is the problem. Training pilots has undergone a remark- able change in the last year. Government regulations are getting more stringent all 586 the time, and the men behind the air lines and behind the companies that manufac- ture planes recognize the importance of creating competent flyers. A plane can be built in a few days, even the big tri- motored air liners are turned out daily, but it takes not only months but years to make a finished pilot. The Ford-Stout company has made a rule that it will not sell a plane for use to anyone except a pilot it has approved, or one that has graduated from its school. An accident involving the lives of twelve or fourteen passengers, a pilot and me- chanic, as well as some $70,000 worth of airplane, is too serious a matter not to warrant every possible measure to avoid it, and insistence on the adequate train- ing of pilots is the one way the manufac- turer has of protecting the reputation of his aircraft. There are more planes flying every day, however, that do not. require the skill and training of an air-line pilot, and it is

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through them the young flyer has a chance to work up to the more important jobs. It is like training as fireman and then engineer on a freight train, then engineer on the local as prepa- ration for pulling the throttle on the Century or the Broad- way Limited. The planes which take the place of the railroad freight and local are the private ships owned by business men and manufac- turers, and flown, either to carry important executives about the country or for delivering ex- press and freight, and advertis- ing the company’s product. Most of them are cabin ships, ranging from the pilot and two- passenger craft of the Curtiss “Robin” class, up through the four, five, six, seven and eight- passenger—the Alexander “Bul- lets,” Stinson “Juniors” and “De- troiters,’ Ryan “Broughams,” Fokker “Universals” and “Su- per-Universals,” and like craft. The ships in this class are Fokker Flying Yacht with Dual Hull, Interior of the Craft’s Lux- urious Cabin and, Below, Anthony Fokker Leaving the Ship 587

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Latta Teng ie tbat ie: A a a NR rr he Man IO ee open Tits SacBee, tert re ch el ae na oS Sin at eo Pang ae ra ay ET oe seer ae 588 POPULAR MECHANICS mainly powered with air-cooled radials, ranging from the light engines of the “Velie” type up through the Wrights and the Pratt and Whitney “Wasps” and “Hornets.” Speed and excess power are common in the more expensive jobs, such as the Lockheed “Vega” and “Air Ex- press,” which hold the transcontinental speed records. It is possible to get all the training needed to fly one of these planes, at least to meet the license requirements, without leaving the flying school to get a job. A two-hundred-hour transport license course, including ground school, primary training, solo, and the 200 hours of solo flying, can be had for around $4,000. One school has been experimenting with a 200-hour course in which the student is given a new plane, all for $4,970. In this course the young pilot, after graduation from ground and primary school, gets his first ten hours in a school ship, to qualify for a private owner’s license. As soon as he passes the necessary tests for that the school delivers his own ship, and he can proceed to work up the other 190 hours as fast as he wants to. He pays for gasoline and oil and a nominal hangar fee, and the school supervises the condition of the ship and any overhaul and repairs he makes, and provides instructors for check hops at regular intervals, to determine what he is learning and check any ten- dency to fall into sloppy ways of piloting. Another school, operated by a manufac- turer of light planes, has an even more novel arrangement. Any student who has graduated from the primary school, or has twenty hours in another school, or boasts a private pilot’s license, can rent a ship by the month and work up his flying time as fast as he wants to. The school claims it is possible by this system to get in 200 hours of solo flying for about ten per cent of what it has cost in the past. The charge is $90 for the first month, $80 for the second, $70 for the third, and, if the flyer wishes to use a ship thereafter it costs him only $60 a month. The student furnishes the gasoline and pays the insur- ance premium on the ship, while the school provides the oil. Those prices are basic figures, applying during the month of April. Owing to variations in the amount of good flying weather in the lati- tude where the school is located, the fig- ures are cut as much as forty per cent in January, thirty-five in February and De- cember, twenty per cent in November and March, and raised from twenty to thirty per cent in the summer months. Under the new regulations which the Courtesy Mahoney-Ryan Man Power Is Still Popular in China, although Airplanes Are Appearing in Various Parts of This Ancient Country; Hauling a Plane to Be Used in Transport Service on Coast

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POPULAR MECHANICS department of commerce is expected to issue in the fall it is thought that student instruction and commercial flying from the same field will be prohibited, not only because of the danger to the air liners from the presence of inexperienced stu- dents, but because the air-line operations delay student instruction. In expectation of this order the larger schools are already taking steps to sepa- rate their work from commercial fields. Several of the bigger organizations, with manufacturing, operation and school de- partments, are acquiring double fields. Several of the schools are emphasizing the necessity of every flying student receiving instruction in both open and cabin planes. Heretofore all pilots were trained in the open-cockpit craft, and picked up their closed ship flying ability aiter leaving school. Flying an aerial sedan instead of an open roadster doesn’t require anything radically new in education. The pilot must accustom himself to the more lim- ited range of vision, and, as a great por- tion of the cabin ships are monoplanes, he must learn, if he learned to fly in a bi- plane, that the monoplanes are, as a rule, Sikorsky Amphibian Transport Ship Used by Pan-American Airways between Florida and West Indies; the Same Sort of Plane Flies between Catalina Island and the Coast of California over Western Air Express more sensitive or “tricky” and require a longer glide to land. The smaller air sedans have standar1 stick controls, so there is nothing new to learn in handling them. Every ship feels different in the air, and this may be true of two exactly similar ships of the same make and model. An accomplished pilot can disregard this, for they all take off much alike, and once in the air he can study the response to the controls, the flying and stalling speed and the gliding angle, and then bring the craft in and make a good landing. The “floating” habit of most mono- planes is the most disconcerting thing about them to the student who graduates from the low-powered, big-winged train- ing biplane. Most of the primary train- ing ships land at anywhere from thirty- two to forty miles an hour, more of them at the slower than at the higher figure. Compared to that even the little Curtiss “Robin” has a landing speed of about fifty miles an hour, with a correspondingly longer roll after the wheels touch the ground. Landing and stalling speed are the two most important things in a flyer’s life.

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fr le Rae \ 2 ‘ i 1 b “B4 590 POPULAR MECHANICS Specially Designed for High Altitudes Encountered on the Transcontinental Run between Chicago and San Francisco, a Boeing Transport, Powered with Three “‘Wasp” Engines They are virtually the same, for a ship stalls at the point where speed falls so low it no longer responds to the controls, and a ship lands within a mile or so of this same speed. Increase the landing speed, and the speed which must be main- tained in the air also increases. Many of the training biplanes can be cruised at sixty miles an hour or even less in perfect safety. Raise the landing speed to fifty miles an hour and the safe cruising speed goes up to sixty-five or seventy; raise it to sixty and cruising speed should not be permitted to fall below eighty. Students usually learn to fly with the minimum of instruments, sometimes noth- ing but tachometer, oil gauge and tem- perature indicator. After they have mas- tered the trick of judging flying speed and flying position by the feel of the ship and the whistle of the wind through the flying wires, graduation to a_ better-equipped ship comes as a pleasant relief. Given an air-speed indicator to check flying speed, turn and bank indicators to check flying position, and, possibly, a_ rate-of-climb indicator as a check on climb and gliding angles, there is small chance of a wide- awake pilot getting into an involuntary spin or even stalling the ship. Every plane is rated by the manufac- turer to climb so many hundreds of feet per minute in air of sea-level density. With lighter air at a higher altitude, the climbing rate becomes less, so the climb indicator, which shows the rate not as an angle but in feet per minute, cannot always be relied on. But a check-of-climb indicator against the air-speed dial deter- mines whether the plane is maintaining a safe climbing speed, so one instrument is an aid to the other. Instrument flying is becoming increas- ingly important, as air lines must main- tain schedules in all kinds of weather, and blind flying through fog and storm is only possible for the pilot who is skilled in the use of his instruments. Because a flying education sufficient to fit a man to pilot one of the big air liners costs consider- ably more than a college education, and takes as long or longer to acquire, there probably will be a shortage for some years to come of men for the air-line posts. LUMINOUS CLOTH LURES COONS Raccoons are curious animals, easily at- tracted by bright objects, and an inventor has utilized this fact to aid trappers. Bright objects, such as colored bits of cloth, often are placed near the traps, but these are useless at night. Then a double- faced adhesive tape with a luminous coat- ing may be used, which glows so that it may be observed for some distance.

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POPULAR INTER-CAR TELEPHONE SYSTEM SAVES STEPS ON TRAIN Long trips through a train to find if there is a seat in the diner or if the barber is busy, now are unnecessary for passen- gers on the Cascade limited between San Francisco and Portland. This train has installed an inter-car telephone system, each car being equipped with a telephone instrument with which passengers may communicate with any other car. The telephones may be used to order a meal, call a maid, summon train attendants or obtain any other service. A combination dial and push button, of the one-piece continental type, is used. ELECTRIC SUNBATHS FOR FRUIT Demands that the natural “bloom” be on fruit when it is purchased has resulted in the use of artificial sunbaths to restore the tints of the skins and give them the appearance of having been freshly gath- ered. The fruit first is wiped free of dust and moisture, polished by leathers arranged for rapid handling, then placed under the ravs of the apparatus for from one to five minutes. BAIT BUCKET WITH SPRING TOP HOLDS MINNOWS SECURELY Minnows, frogs and other live bait are kept securely in a bucket that is equipped with coil springs which form the top. A perfor- ated container fits inside the bait bucket, allowing water to circulate freely when it is carried, or the container may hang over the side of the boat in the water. When re- moving bait, the hand is inserted between the coil springs which snap back into position when the hand is removed. MECHANICS taka A Photographer Risked His Life to Snap These Pic- tures of a Kansas Twister in Action TORNADO IN ACTION PICTURED BY DARING PHOTOGRAPHER Pictures of a Kansas twister in action were obtained by a daring photographer who risked his life to snap the tornado in various poses as it approached. The se- ries of pictures the cameraman obtained included views of the tornado at a con- siderable distance, a nearer view with the black clouds throwing dark shadows on the ground and a close-up with the spout of the twister less than a mile away. @ Twenty-nine states now levy a tax of four cents or more on gasoline.

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592 POPULAR MECHANICS PLANE GLIDES UP CANVAS RUNWAY ONTO STEAMER Using a special run- way covered with can- vas or sail padding, a seaplane was successfully landed aboard a ship in recent tests. The run- way was towed behind mas trees from Ger- many and a sample was brought to the labora- tory to have its value fixed. There was a little paper-bound pot and from it rose the tree with lovely green needles and tiny can- dies.. The needles puz- zled the chemists, and Towed behind a Ship, the Canvas Runway, Above, Was Used to Land a ter. Seaplane; Below, the Plane Being Towed up the Runway the North German Lloyd steamer “Luet- zow,” and the plane alighted on it and was pulled on board the vessel. DYED GOOSE FEATHERS PUZZLE CUSTOM CHEMISTS While tariff has always occupied a vital place in politics, the average person’s knowledge of the vast organization re- quired to carry it into effect ends with the custom inspector he meets upon his re- turn from abroad. It does not include the hundreds of workers whose business it is to appraise the value of millions of dollars worth of goods brought into the United States yearly. That is the business of the chemists of the custom appraisers. Their subjects, the materials that come under the microscope or go through retorts and tubes, range from Chinese hair nets to toy Christmas trees and Scotch home- spuns, sugar and manganese ore. For in- stance, a firm imported some toy Christ- one was soaked in wa- It swelled a little and ultimately opened and revealed itself as half a goose feather which had been dyed. Motion-picture films are brought to the laboratories and weighed, examined and appraised. Coal- tar products, liquor and various synthetic fluids are distilled and their parts made known. Another example of the work of the custom chemists was shown at the time of the Philadelphia exposition. Some of the exhibitors brought in fab- rics, scarfs and small carpets, which were said to be so old that exemption was claimed on the grounds that they were antiques. The tariff law lists as antiques articles over 100 vears old which have an artistic value. The fabrics in question were examined. They certainly looked old enough, but the tests showed they contained coal-tar dyes and as those dyes were not discovered until 1857, they could not have been as old as it was claimed. The exhibitors protested, but the goods were taxed. The work of the custom chemists is constantly full of surprises.

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POPULAR MECHANICS For example. one day some hair nets were brought to the laboratory. Human hair carries a duty of forty-five per cent while all other kinds are taxable at ninety per cent. In hair nets, yak hair is sometimes used. were unfamiliar with yak hair and this hair might be merely coarse human. So they sent to the zoo for yak hair and the microscope told them the rest. ANGLERS SEE BENEATH WAVES WITH A WATER SCOPE Peering into twenty-five or fifty feet of water to discern objects clearly is made possible with an instrument known as a water scope which fishermen are using to advantage. The scope is two feet long with a nine-inch lens cemented in place to make it water-tight. The lens is sub- merged in the water and the operator peers through a visor, obtaining vision thirteen feet in diameter in twenty-five feet of water. Besides being used by an- glers, the instrument also is employed in locating articles lost in water, and has even been used to find the body of a drowning person and thus save his life. In the average fresh-water lake, distinct vision is possible at twenty-five feet. Angler Peering beneath the Surface with a Water Scope Which Penetrates Twenty-Five Feet The chemists knew that but they Extension Platform, Like an Extension Ladder, Used to Wash the Surfaces of Tall Buildings WASHING FACES OF BUILDINGS IS MADE EASY Even buildings must have a bath at intervals, and a lofty extension platform, which extends to the fourth story, has been made to allow workmen to clean the polished stones of a tall Chicago structure. Parallel extension ladders form the legs of the elongated platform resting on a base to which rollers are attached, so it may be wheeled easily along the wall. KEEPING FOODS DRY Foods that are likely to absorb mois- ture, such as dry cereals and crackers, may be kept in a palatable condition in a cabinet constructed to prevent moisture. The container holds an odorless material that has a great affinity for moisture and absorbs dampness from the air or food. Besides being used to keep foods crisp and fresh, the cabinet also may be utilized to store metals that rust or articles harmed by moisture. any

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. 2558 sor 698A% ai? a af a_nGeen* By PAUL D. PADDOCK OISONS and mysterious deaths have been linked in the public mind since the dawn of history but modern chemical science has done much to rob such cases of their baffling aspects. Along with the scientific detective, the chemist is winning increased recognition in the war against crime. Police departments are installing laboratories where such apparently trivial things as spots on clothing, weapons or money frequently provide the final evi- dence that may free or convict the ac- cused. / “Mysteries? Yes, there are plenty of them in the chemical realm of police in- vestigations,” says Dr. W. D. McNally, former coroner’s chemist of Cook county, Illinois, and one of the best known ex- perts on poisons in the country. “But the problem of finding the poison and identifying it is a relatively simple process in chemistry. Witnesses may disagree but test tubes, in the hands of efficient men, generally tell the same story. That’s just one reason why the chemical evidence \.in a case is regarded as so important. ’ “Not long ago, a suspect in a murder case was about to be freed when a tiny spot was discovered:on one of his shoe- strings. Analysis showed that the spot was human blood. He had carefully washed all his clothing but had forgotten 594 the shoestrings! A sim- ilar oversight led to the conviction of another man who had forgotten to wash his shoes. In- criminating blood stains were found on the leather. “Chemists kave posi- tive means of identify- ing human blood from that of animals, al- though it is not possi- ble to identify the blood Portable Chemical Laboratory Los Angeles Police Use in Solving Crimes, and Guard with Machine Gun of a specific person. In the same way, human hairs can be distinguished from those of animals, but cannot always be identified as coming from a particular person. “Recognizing that soils have different chemical and physical properties, detec- tives sought for incriminating evidence in a recent murder by closely examining an

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Veyteyn My teries# y Sg t & Coroner Herman N. Bundesen Questioning a Witness during a Gang-Slaying Inquest; the Gun Was Linked to the Murders through Marks on the Bullets in the Victims’ Bodies automobile for traces of swamp mud like that in which the victim was found. “Chemical science has developed inter- esting facts concerning weapons. For in- stance, analysis of the contents of a gun barrel will tell whether the weapon has been fired recently, although it is not pos- sible to determine this factor exactly in terms of hours. There is an interesting field of research here, and possibly chem- ists will be able to fix the time accurately on the basis of chemical investigation of the powder marks. “Important court cases have been de- cided on the basis of the kind of powder found in shells, weapons or upon the body of the victim. It is well known that suicide or murder is often established by the presence or absence of powder marks upon the body. A trained investigator can tell almost to the inch how far a weapon was held from the persor. killed, by careful inspection of these marks. “In a court case, a suspect was alleged to have been in a pool room at the time a crime was committed. He denied be- ing there, but dust found in his pockets, on chemical analysis, proved to be chalk such as is used on billiard cues. Like many other players, he was in the habit of putting his hands in his coat pocket after using the chalk and the dust proved a clue against him. Chemical and micro- scopic examination of the dust found on clothing, on automobile tires or other ob- jects frequently reveals important evi- dence. The physical size of an article is not of great moment to the chemist to whom tiny spots and flecks of dust are sometimes monumental in their signifi- cance. “Tn the field of poisons, the chemist has developed tests that reliably identify the 100 or more kinds commonly used. Poi- son is a hazardous tool for the slayer. Today, with proper investigation, it is practically impessible to ‘cover up’ a death by poison. It leaves an unmistakable trail that frequently can be followed as plainly as though it were written in stone, 595

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596 POPULAR Coroner’s Chemist Ralph W. Webster Examining Blood Stains on Handles of a Wheelbarrow That Figured in a Murder Case although the unfortunate victim may have been buried for months.” During his seventeen years’ experience ‘as. coroner’s chemist, Doctor McNally investigated and helped solve some 15,000 poison and other cases in which chem- istry produced deciding evidence. He planned the present Cook county chem- ical laboratory, one of the most com- pletely equipped in the country. Here, almost daily, important evidence relating to deaths under mysterious circumstances, is discovered by chemical methods. In one corner of a room where special tests are made, is a tragic collection of objects, each one of which might tell a dramatic story. A stained dagger, an old wheel- barrow, a flatiron, clothing with spots, all awaiting the searching eye of science. “T was a university student when I first became interested in poisons,” Doctor McNally said. “There had been a suicide. The late Prof. Albert Prescott was called and, after a brief examination, he named the drug that had been used. Its char- acteristic odor had made identification relatively simple, he explained. I decided that I would like to be able to clear up such cases in as efficient a manner, so I MECHANICS I have encountered many poi- son cases since that time. began to study. In one, a woman had used a drug to kill sev- eral husbands. She and her cousin had disposed of thirteen men in this manner. Their victims were supposed to have died from natural causes. But I happened to be called to attend one of them. I detected a pe- culiar odor on the dying man’s breath. The Pres- cott instance came back to me and the crime was revealed. “A chemist-detective, however, must never jump at the conclusion that the drug he finds has caused the death, and he must apply wide knowledge to the facts in each particular case. It’s one thing to find poison in a body; it’s an entirely different thing to prove that the poison caused the death or that it was administered by a certain person for a specific motive. Take the case of a supposed murder. Now, murder is com- mitted for three chief reasons: first, love; second, financial gain; third, hatred. The chemical evidence discovered must be alined with all the other facts in the case and with such motives as were supposed to have prompted the crime. Frequently it happens that the chemist’s findings are of supreme importance. “Such was the fact in a recent case in which an unfortunate error on the part of a chemist almost led to the conviction of a young man for murder. The trial was one of the most sensational in recent years and developed, among other mysti- fying factors, the presence of three spots on the coat of the young victim. These proved a riddle until it was shown, with little likelihood of error, that they had been placed on the coat after the death. “The testimony was that the young man had access to large quantities of a chemical substance said to be the same as that which caused the young woman’s

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SS ode | we POPULAR death. The stuff had been thrown on a greenhouse refuse heap. Naturally, this point was incriminating, and had it not been destroyed by later evidence, there is little question but that the defendant, who finally was acquitted, would have been convicted. But a chemist had made a mistake in his analysis. The substance on the refuse heap, although like that which had caused the death, was not ex- actly the same, hence could not have been used in the crime. “The three spots were especially inter- esting. Witnesses testified that no such marks had been seen on the young wo- man’s coat when her body was found. But they were clear enough weeks later, about fifteen inches from the coat collar and four inches from the buttonhole. The fact that they were in an absolutely straight line was important. Only a miracle could have arranged them in that order had they been caused by drops falling from a bottle of liquid poison. Obviously, the spots were meant to indicate that the young woman had taken the poison vol- untarily, a supposition that was strength- ened by the fact that when she was found, her right hand was bare and her left hand gloved. “The spots gave off the odor of the fatal drug. But my tests plainly showed that the substance would not retain its odor over so long a period as had elapsed since the young woman died. In the examina- MECHANICS Telltale Marks on Bullets from a Suspect’s Revolver, and Capt. William A. Jones at “Bullet-Fingerprinting”’ Microscope tion of hundreds of blood stains and other spots found on clothing, I had never ob- served a parallel case in which spots were found in a straight line. Other tests showed that the chemical, when dropped upon coarse woolen material, like that of the coat, rolled off like so much mercury. How the spots got there, when they were made and by whom are still unsolved mysteries. “We live in a world of chemistry and are surrounded by poisons in our daily

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598 POPULAR MECHANICS “One of the commonest poison hazards is that of carbon mon- oxide. This gas is formed as a by- product of combustion. Ammo- nia, washing compounds and other household chemicals produce serious consequences and some- times death, particularly among young children who carelessly are allowed access to them and swallow them. Great care should be taken in fumigating. Reputa- ble firms that do this work are licensed and know their business. “The scientific examination of evidence in case of a crime and the application of more certain methods to guard our daily health and welfare are but indi- cations of the added service man is gaining from his knowledge. Only recently, the bureau of standards has recognized the im- portance of more scientific’ crim- inal research and has taken up the problems of identification of documents, typewriters, guns, bullets and other things with a view to establishing more accu- rate standards for this type of " X-Ray Films That Will Not Burn, to Prevent Poison Fumes in Case a Hospital Fire Threatens the Storage Vaults toil, but that need give no cause for alarm. Science has found reliable antidotes for various harmful substances and has de- veloped safeguards where danger lies. Most of the superstitions about various drugs and foods have been abandoned. We know that tomatoes are not poison- ous, for instance, although not many years ago they were considered inedible. Until recently, there has been a lot of use- less worry about poison in foods. Some persons still believe that fatal poisons will rapidly develop if food is left in tin cans. Well, it is not a good practice to leave foods so exposed and juices in time will react upon the solder in the can if that material is there and is in contact with the food, but most containers are much safer than is popularly supposed. Illness is frequently caused by eating spoiled or partly decayed food, but it is a mistake to think that every such case is one of ‘ptomaine poisoning.’ work. The ‘Sherlock Holmes’ of tomorrow will be far more scien- tific than the story books now pic- ture him. He will be a combination of the detective and the true scientist, and will have at his command increasingly re- liable instruments to help him in the war- fare against crime.” AUTOMATIC ELECTRIC KETTLE WILL NOT BOIL DRY Like toasters, cof- fee pots and waffle irons, the tea kettle now is moving to the dining room. An electric kettle may be used with safety on the dining table because it is self- j regulating, cutting ~ ta off the current before it boils dry, auto- matically reducing the heat before boil- ing over, and maintaining any predeter- mined temperature.

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POPULAR MECHANICS 599 MODEL PLANE HAS PARACHUTE AND CLOTHESPIN JUMPERS Clothespins serve as the heroes of leaps from a model airplane equipped with para- chutes, in an ingenious toy made by a Los Angeles school boy. The twenty-seven- inch parachutes with their dare-devil wooden-headed passengers are packed on Model Plane Equipped with Parachutes for Clothespin Passengers; at Right, a Parachute Descent each side of the fuselage underneath the wings. They are held in place by a tri- angular flap, one point of which is fas- tened by a pin thrust through eyelets. When the plane reaches an altitude of 100 feet, the pins are pulled out auto- matically and the parachutes, with their clothespins dangling safely at the end, come floating to earth. SWEETS HELP WORKING GIRLS RESIST FATIGUE Feeding candy or other highly concen- trated, energizing food to working girls speeds up their production, particularly during the late afternoon slump, Dr. Thaddeus L. Bolton, head of the depart- ment of psychology of Temple university, has decided after a series of tests on twenty stenographers. Fatigue, diet and working capacity were found to be closely related. One group of girls each after- noon received candy, cake and sweetened orangeade, two other groups received sweets on part of the days and the fourth group went through the afternoon with- out any refreshments. Working capacity was comparatively low at the beginning of the day, increased after a “warming up” until about 2:30 p. m., then fell ex- cept that there was a spurt at the end. The groups taking the nourishment, even only part of the days, showed a higher working rate than the no-food group. TIDE EMPLOYED TO SAVE PILING FROM MARINE BORERS Marine borers, the foes of wood, metal and concrete piling, are being fought by harnessing the tide to combat them on the west coast. Heretofore it had been customary to inject preservatives in the piling material to prolong life. The latest appliance consists of blocks of wood tied to a metallic ring about a pile. The free- floating blocks shift up and down the pil- ing and by their friction knock off incrus- tations, preventing new growths from tak- ing hold. The average life of untreated wooden piling in this region ranges from eight months to two years and those equipped with the blocks last many times that long, marine engineers say.

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600 RADIO AIDS MUSIC STUDENTS TO HEAR OWN VOICES Testing the Acoustic Properties of the Wall Board with the Help of Radio Acoustic properties of wall linings are tested by radio at the Berlin Academy of Music. A tube containing a miniature loud speaker producing a standard-tone effect terminates at one end in a funnel . from which the sound strikes the material to be tested. The reflected sound waves are picked up by a microphone communi- cating with a loud speaker in another room where comparative tests are made with the original tone. Another device, the steel-wire voice recorder, enables a student to study his own voice. It is based on the variable magnetization of a steel wire passing in front of the poles of an electro- magnet activated by microphone current. By reversing this process, causing the magnetized wire to pass in front of a similar electromagnet, currents corre- sponding to the original microphone cur- rents are induced, resulting in a remark- ably faithful reproduction of the singer’s voice in a loud speaker. HARDENED ALUMINUM WILL NOT STAIN OR TARNISH Durability of aluminum is increased by a treating process recently developed which not only hardens the metal but also eliminates the tendency of the sur- POPULAR MECHANICS face to smudge, tarnish or scratch, and enables it to resist the effects of salt water and various acids and corrosive agencies. The process provides a protective finish which will take many delicate color effects. The advantages of the treated metal ex- tend into every field where aluminum products are used. The treatment in ef- fect is comparable to the cyanide process of hardening steel. Every item treated is completely submerged and the inherent advantages of ductility and flexibility in forming are preserved. Laboratory tests showed an increase in hardness of more than 100 per cent. Cooking utensils so treated are left free from tarnish and preserve a bright polish. Airplane manu- facturers and the automobile industry see possibilities in the treated metal for uses where it could not be employed previously because it lacked hardness. SAND TESTER SHOWS QUALITY OF CONCRETE MIXTURE Determining the quality of sand being used in concrete work without sending samples to a laboratory is possible with a sand tester that is simple in operation. The tester grades the sand and gives an indication of its cleanness. It consists of a water-tight frame into which are fitted a graded series of fine-mesh screens and a series of glass vials connecting with each of the screen sections. A small metal measure of sand is poured into an open- ing in one end of the casing, to which water is added, the mixture being gently shaken to cause separation. The instru- ment is turned vial side down, the various screenings falling into the several vials, giving the percentage of each grade of sand either passing or retained. Sand Passes Successively Through a Graded Series of Screens in This Simple Sand Tester

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Sphere Gap Used for Controlling and Measuring Artificial Lightning at the Outdoor Laboratory; the Upright Supports Are Special Insulators and the Dial Records Distance between the Spheres |X THE MIDST of a strange forest of poles and towers of various shapes, a seven-foot balloon, filled with hydrogen gas, sways at the end of an anchor rope. About thirty feet above the sphere is a huge cage aerial, of the type used in radio and supported by long strings of heavy insulators. A small metal ball hangs down a short distance below the cage, just above the balloon. At respectable dis- tances, several men are standing, evidently waiting for something to happen. One gives a signal, and another presses a button that projects from the side of a small box. At once the spectator expe- riences a strange sensation. He knows that something is taking place about him, yet he cannot tell what. He feels that a strange tension is in the air. Then a rustling sound greets his ears, coming from the general direction of the cage- aerial arrangement. Something is happening around the small sphere hanging from the cage. Streamers almost invisible, like heat waves above a railroad track on a summer day, are darting down from it. Then sud- denly a blue-white flame of great bril- liancy darts from the sphere to the bal- loon, zips over the surface to the anchor rope, and is gone. There is a report like the firing of a three-inch gun. The bal- loon seems to shudder as the man-made lightning strikes it, and then continues to wave in the breeze. Such a demonstration which, to the vis- itor, seems like an event that takes place in the setting for a highly imaginative scientific novel, is an almost daily occur- rence at the huge outdoor high-voltage laboratory of the Ohio Insulator com- pany at Barberton. The hydrogen-filled balloon was being subjected to artificial lightning flashes of more than 3,000,000 volts in an attempt to develop a method of protecting racing balloons from natural 601

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602 POPULAR MECHANICS The laboratory field is covered by a network of railroad tracks upon which a strange game of chess is frequently played. The chessmen are steel and wood transmission towers of all types, oscil- lators, sphere gaps, and the like. The process of weeding out a particular tower from the forest of several dozen, and plac- ing it in position for a test is as intricate a task as winning a closely con- tested chess or checker match. Each of the towers, as well as other portable apparatus, is mounted upon a small car to permit easy mov- ing. Engineers using the laboratory often have the job of ‘‘shooting trouble” for a power company in some remote corner of the world in an effort to learn why an apparently perfect trans- mission line failed to do Testing a Hydrogen-Filled Balloon with a 3,000,000-Volt Spark; the Flash its job of carrying power Suggests the High Voltage in Lightning lightning. Incidentally, following the ex- periments described, a satisfactory pro- tective device, consisting of a wire screen about the gas bag and balloon basket, was designed. But the developing of a balloon pro- tector was but one of the many things that are done at this unusual “lightning factory.” Arthur O. Austin, chief engi- neer, is the modern Thor who can manu- facture thunderbolts at will. With his associates, he built the high-tension labo- ratory on what was formerly a model farm. At various places in the maze of appa- ratus that fills the field in front of a chateau-barn, are pairs of huge copper spheres, four in all. By increasing or de- creasing the distance between the spheres of a gap, the operators can control and measure the voltage of the arc during a test. Each of the spheres is of heavy copper, and weighs nearly one-half ton. to some center of popu- lation.. Instead of going to the scene of the trouble, they can bring the problem to their laboratory and reproduce the con- ditions which caused the failure. The lightning manufactured at the ex- perimental station can produce many of the results of that made in nature’s labo- ratory. If a man should get in the way of a 3,000,000-volt spark, he would imme- diately become a task for an undertaker. But it is surprising that a wide-open wire screen can provide complete protection from twenty-seven-foot lightning flashes. At the indoor laboratory, the spectators’ ‘balcony is equipped with such shielding. It is a strange experience to stand behind this screen and watch streamers of fire leap out and strike a foot from your nose. It is by playing with lightning that scientists hope to develop methods of transmitting electrical power at practi- cally no loss, so that you can make toast, a a. onan -«— &

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POPULAR heat your home in winter and cool it in summer, and do a hundred other jobs electrically, at a fraction of the cost today. Who knows but that an accidental dis- covery will be made in such a laboratory which will give the world practical radio power transmission, or some other equally revolutionary development? THE PAY OF AIR PILOTS Pay of the pilot on a regularly scheduled American air-transport line is estimated at $5,556 a year by the aeronautics branch of the department of commerce, which adds that he averages less than two and one-half hours a day in the air. As he flies slightly more than 40,000 miles a year, his daily mean is about 110 miles. The records were compiled from reports on 275 pilots employed by twenty-five air-transport organizations. During the latter half of 1928 the operating revenue of the air companies was slightly under $5,500,000, of which about four-fifths was from air-mail contracts. LIFE-SAVING RIFLE AND ROCKET SHOOT LINE TO SWIMMERS Capable of throwing a float attached to a lifeline 250 yards, an ordinary rifle fitted with a rocket attachment recently was demonstrated in South Africa. The rifle has a container for a roll of cord and is capable of throwing the float 150 vards, but as it is falling a rocket explodes and carries it 100 yards farther. Six swim- Life-Saving Rifle, Fitted with Rocket Which Throws Line and Float for 250 Yards mers were hauled ashore at one time dur- ing tests with the thin line. MECHANICS 603 BANK USES VENDING MACHINE TO ATTRACT SAVERS This Vending Machine Encourages Thrift by Dispens- ing Small Savings Banks for Coins Automatic devices for vending “book banks” have been placed in operation out- side the doors of a New York bank. A quarter dropped into the machine brings forth a metal container shaped like a bank book, one end of which is slotted to receive coins up to a quarter. When the container is filled, the owner brings it to the bank, where his quarter is refunded, the contents of the savings box removed and deposited in a savings account and the container returned to the owner. Boys and girls have been the best customers. PHEASANTS KILL CROP PESTS In response to a complaint by Nebraska farmers that pheasants were destroying planted cornfields, a game warden killed thirty-six of them for tests. Corn was found in only one crop, but in another were found sixty-one cutworms, a third had eight June bugs, still another con- tained forty-two black beetles, and in all the others were found bugs, worms and seed pods from poison ivy and weeds. Some of the corn taken from one crop appeared to be poisoned corn that had been spread about to kill ground squirrels. The poi- son does not affect the pheasants,

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POPULAR MECHANICS seen an sa eB or COLLEGE TRAVELS ON WHEELS In order to study ge- ology, geography, his- tory and other subjects at first hand, a motor college is traveling from Massachusetts to Cali- fornia and back. The students, carried in mo- tor coaches from place to place, make stops to study soil, mines, forests, fauna and flora, deserts and mountains besides visiting historical points and making trips through the Grand Canyon, Yo- semite and Yellowstone. PUNCHING BAG FOR AUTOISTS Striking with a stick at a captive balloon while Photograph of a Typical Filling and Insulating Job and, Drawing to Show How Material Is Pumped between the Walls of a House driving an automobile fifty miles an hour is a stunt that is proving INVISIBLE WALLS SHIELD HOME popular among Berlin motorists. It was FROM HEAT AND COLD started simply as a form of practice for auto polo, but was found to be a good way Effective insulation for residences and to prevent auto accidents on the roads, as other buildings is furnished by a wool- __ it forced drivers to develop steady nerves. like substance prepared from stone and blown over ceilings and into hollow wall spaces by special pneumatic apparatus. The result is that the interior is pro- tected by a blanket of the wool, four inches thick or more, virtu- ally a house within the outer walls, to keep out the cold, pre- vent heat losses and to help keep the home comfortably cool in summer. The insulation also acts as a sound deadener. It is fireproof, does not settle, is dust free and will not harbor vermin. Old homes, as well as new ones, of frame construction, brick ve- neer or stucco, may be treated. The material is blown through a hose from a trailer truck, and the work is done from the attic or the outside of the house. This Girl Driver Is Developing Steady Nerves by Striking at Captive Balloons with a Stick While Speeding ta eo ee

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Scaling Fish at a Large Commercial Plant; the Scales Are Used in the Manufacture of Pearl Essence and Other Lustrous Materials FIFTEEN-million-dollar business in the utilization of waste and the devel- opment of by-products of the fisheries in- dustry has been established in the United States during the last three years, and new sources of revenue are being sought, from methods of utilizing fish scrap as feed for dairy and barnyard animals to the deodorizing of fish oil for use in soaps, cosmetics and cooking substances. Hunting sharks for their fins and hide for use in the manufacture of a large va- riety of articles ranging from women’s handbags to sword hilts and nose grips for eyeglasses is a growing and thriving industry. The skins of many aquatic ani- mals, including those of sturgeon, garfish, wolf fish, cod, cusk, watersnakes and frogs, are being used for leather or nov- elty purposes. Eel skins are tanned for bookbinding, in making whips, suspend- ers and other articles, or dried and oiled for use as a substitute for window glass. Bags made of alligator hides are in much demand. Hides of seal, sea lion and wal- rus are also tanned into leather of especial value to silversmiths, gun manufacturers, and the like, for removing mars and scratches and for polishing fine metal sur- faces. Fish skins, such as cod and had- dock, are used in the manufacture of fish glue, and fish sounds or air bladders are extensively used in the manufacture of isinglass, for clarifying beverages, in ad- hesives and in sizings to impart a luster and stiffness to linens and silks. The “Christiania,” modern floating oil factory, was cruising lazily over the whal- ing grounds. A bull sperm appeared sud- denly to starboard and the gun crew sprang into action. A bomb-laden har- poon shot out over the water and sank with deadly explosion into the whale di- rectly back of its head. Late that after- noon not a trace of whale in its original form was to be found anywhere on the ship. The fat had been made into oil, the whalebone was stored in the hold, and 605

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anche Renacnecasan ees ann 606 POPULAR MECHANICS annually is valued at $5,000,000. The total annual catch of hard crabs in the United States and Alaska is approximately 39,000,000 pounds. Inasmuch as approxi- mately eighty-five per cent of the crab is non-edible, the annual waste is around 33,000,000 pounds. Nearly 20,000,000 pounds of this green waste should produce, upon reduction, about 8,000,000 pounds of dried crab scrap suitable for poultry feeding. In a recent experiment, the bu- reau of fisheries used crab scrap to supplement the poultry diet. A flock of birds was divided into two pens of twenty-five each. From December to March the birds that received crab scrap laid 938 eggs as compared with 479 eggs laid by the birds which were fed a standard ration. The huge beds of oyster shells of ancient civilizations are now proving a bonanza in the manu- facture of poultry grit and lime, and no oyster packer any longer has difficulty disposing of this former waste. The demand for Bureau of Fisheries Experimental Plant for Extraction of Fish Oil Used in Making Soaps and Cosmetics the scrap made into meal. Thus has mod- ern science improved upon former waste- ful methods of capturing whales and of transporting the fat to land stations. The floating factories are provided with equip- ment at bow, stern or sides for hauling the huge mammals aboard for cutting up and reduction. But by very reason of the efficiency with which these mammals are being hunted in order to furnish mi- lady with scented soaps, coldcreams, and other cosmetics, the whaling industry is threatened with extinction, and extensive research is now being made in developing other fish oils. Milady will not be pleased, perhaps, to learn that her vanishing cream, beauty cream, toothpaste and perfumed soap may have been made in part from a fish; but these articles may contain glycerin, and glycerin is a by-product of the soap in- dustry and derived from fats and oils such as fish and whale oil. The more than 10,000,000 gallons of these oils produced oyster shells is larger than the fishery can supply and explora- tion parties are continually searching for beds of other ages. The annual produc- tion of poultry grit and lime from oyster shells is now approximately 300,000 tons, and is valued at $2,600,000. During the war, the European supply of pearl essence or fish-scale essence was cut off and research had to be conducted looking toward the development of new sources of supply in this country. The scales of the sea herring of New England were found to contain the necessary ele- ment, and, at the present time 2,000,000 pounds of fish scales are used: annually in the manufacture of imitation pearls and imitation mother-of-pearl celluloid prod- ucts for use on the backs of hairbrushes, hand mirrors and other toilet articles, um- brella handles, buttons, and other com- modities. The domestic production of pearl essence has become so large as to attract foreign buyers and the manufac- tured products are to be found in every five and ten-cent store in the land,

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7 Oo SS = Ww Discussing the marked growth of ‘the fisheries by-products’ industry in recent vears, and the possibilities for further ex- pansion, Deputy Commissioner Radcliffe, of the bureau of fisheries, declared that “the number of fishery products catering to our needs and vanity today are greater than at any time in the history of the world. Figuratively speaking, the modern woman might dive into the sea and emerge completely clothed and adorned. “She will be wearing a dress of artifi- cial silk made from the shells of crabs, lobsters, or other crustaceans; a fur coat of otter, sealskin or beaver, with mink or muskrat trimmings; shoes of shark skin and mussel-shell buckles adorn her feet; and the buttons on her dress are of pearl derived from fresh-water mussels. “Coral earrings and a_ tortoise-shell comb complete her outfit. In her alliga- tor-leather handbag, she carries a cake of soap made from fish oil; coldcream from whale oil; a sponge; a bottle of perfume with ambergris as the fixative, a hand lo- tion made from seamoss, and gloves of cod skin. On her way home, she views a photogravure which was covered with fish glue before etching, and purchases a beaver hat adorned with an aigrette made from whalebone; a toilet set trimmed with arti- ficial pearl made from fish-scale essence; an amber pipe for her husband; a bottle of cod-liver oil, agar-agar for gelatin, and cuttlefish bone for the canary.” BATTERY INDICATOR FOR AUTO CHECKS POWER AND WATER Affording a con- stant check on the power and amount of water, a battery indica- tor may be at- tached to the dash or steering col- umn of the auto- mobile. The de- gree of power is shown when the starter is de- pressed, while the amount of water is indicated at all times, both being shown by the same needle. POPULAR MECHANICS 6117 ARMCHAIR AND BED IN ONE SAVE ROOM SPACE An Armchair That Is Transformed into a Comfortable Bed at Night by Turning a Lever Simply by raising a small lever at the back, a comfortable armchair, now on the market, is quickly converted into a sin- gle bed. The two arms descend and the back section swings around to make a head support. The bed pad may be at- tached permanently and is completely hidden when the chair is folded up again. The conversion into a bed is accomplished by a single motion as there are no extra parts to insert or adjust. Folding or un- folding the chair takes but a few seconds and its double purpose is not apparent when used as a chair. MEADOW MICE DESTROY CROPS One meadow mouse eats more than an ounce of green food a day or twenty- three pounds a year, government exper- iments to determine ‘the destructiveness of these rodents have shown. One hun- dred mice to an acre, which is not a large number, in a year destroy more than a ton of green grass and even as few as ten to the acre on one hundred acres of meadow consume eleven tons of grass. This number. on the 65,000,000 acres of hay raised, represents a loss of more than 3,000,000 tons a year, or about $30,000,000 in hay alone.

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608 POPULAR MECHANICS STEEL HOUSE FRAME GIVES SKYSCRAPER STRENGTH Steel framework, long used for the sky- scraper and office building, is now utilized for the modern dwelling along the same lines as wood framing. The steel is de- livered ready for assembly without cut- ting or fitting. Ease in assembling is af- forded by perforations of all pieces except floor joists each two inches, the system being so flexible that a house may be planned without the restriction in ar- rangement and style which heretofore has prevented the economic use of steel for small homes. The metal is used for sills, girts, plates, studs, joists and rafters, with light angles for studs and corner posts, and separation plates to join an- Ready-Cut Steel Frame for Dwelling, with Drawing of a Section; Insert Shows One Such Home gles, thus leaving a space in studding for bracing, wiring and piping. Besides be- ing strong, durable, fireproof and non- shrinkable, the steel framing may be used with other standard materials employed in fireproof construction with no more trouble than when such materials are em- ployed with solid masonry walls or wood framing. Standard clips and plates for connecting various parts make the as- sembly of such a structure resemble the piecing together of a child’s erector set. The framing also is being used success- fully in the construction of garages, small apartments, school houses and farm buildings, and for partition work in hotels, apartments and office buildings. While the first cost of steel framing is higher than wood, this, the makers. say, is offset by the saving in labor. Little skill, aside from the ordinary supervision over con- struction work, is required in assembling the ics V the to quit stra bec: the rea A par tor bee sta sto we of wa irc hy in’ of th in fro co Sti gi ve

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POPULAR MECHANICS 609 the framing, and mechan- ics wholly unfamiliar with the system have been able to complete the frame quickly after a demon- stration of the method, because it is so similar to the assembly of the ready-cut wood framing. AUTO SIDE SWAY REMEDIED BY CONTROL Consisting of only two parts, a cylinder and pis- ton, a shock absorber has been made to control starting jerks, sudden stops and side sway as well as the ups and downs of automobiling. The six- way shock control, aside from simplification of the hydraulic principle, also involves angular, instead of vertical, installation, the rear absorbers being inclined forward, and the front axle units inward, connections in each in- stance being with the chassis and the axle, giving direct action. Angular instead of vertical installation results in controlling side sway and starting and braking jerks, while the direct-action installation gives a quicker response. The absorbers also check the tendency of the car to skid or overturn, stopping the twisting torque caused by uneven braking, and extending to keep the wheels fixed to the ground around turns. It has only one mov- ing part cushioned in a fluid imper- vious to tempera- ture changes, con- tains no compli- cated parts, levers, wheels or springs and is intended to last as long as the car without atten- tion. “Shimmying” is eliminated and “bottoming” the springs is prevented. This Roof-Top Studio for Pupils of a Chicago Art School Provides Both Natural Lighting and a Skyline for a Model ART STUDENTS HAVE CLASSES ON SKYSCRAPER ROOF Chicago’s skyline forms an excellent model for pupils of an art school who hold classes on the roof of a tall building. The location, it was found, provided both the natural lighting and the natural scenery for the students’ work. FINDS SYMBOL FOR WORD “THE” After spending thirty years checking up on Hebrew, Anglo-Saxon and other lan- guages, a scholar has formulated a symbol for the word “the,” which is used more often than any other—once in every fifteen words on an average. The symbol he hopes to have adopted generally looks like a merger of the letters “p” and “b” in lower case, while the capital resembles the capital “E” married to the second half of the parenthesis sign. The symbol is an adaptation of the Anglo-Saxon char- acter designating the “th” sound.

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Sa Re RI Aas GL By EDMUND GILLIGAN # Soe: SEAPLANE, the. radio and the homing pigeon are bringing a new era to Gloucester fishermen. For generations the city of Gloucester, Mass., lying in the wide embrace of Cape Ann, has been the home of the harvesters “of the sea. These fishermen have always been willing to gamble with the elements. They have matched their seamanship against the tricks of the northeaster. They have been ready to chance life and ships and strength for their one prize: a holdful of mackerel. 3ut even bravery and stout seaman- ship. could not win the prize if the mack- erel could not be found. Days and nights of searching off Stellwagen banks and in the other shoal waters often ended in dis- appointment. Money for outfitting and for wages was wasted. Often the great fleets came slowly home without a single fish aboard. Now all that is changed through the 610 radio and the airplane. The coast-guard pilot, soaring high in the clear morning sky from Gloucester harbor, roars far above the Atlantic area that stretches be- tween the curling tip of Cape Cod and the brown rocks of Thatcher’s island. Straight into the rays of the dawn, the big ship climbs until the proper altitude is reached and it stands out to sea. To the east and to the south, where the keen eyes of the bareheaded pilot gaze steadfastly, the ocean lies calm and. blue, save where the crests of the waves break in tiny silver falls and splashing fountains. The sea and the land, visible from the cockpit for miles, reveal the world awak- ening. Swift minutes pass as the pilot drives onward into the sun. Suddenly, upon the rim of the ocean, where the sea breaks somewhat whiter on Cashes ledge, he spies a group of schooners. Four in num- ber, they ride together on the waves— painted ships upon a painted ocean, A

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minute later, as the plane roars steadily toward the fleet, another group of schoon- ers, idle also, come into view. Five hulls this time, black-timbered, businesslike, waiting for action. The seines are ready under the beam. Now the plane drops slowly down. The pilot shuts off the motor and the organ- like strumming ceases. There is silence, save for the whine of wind in the struts and against the broad wings. Springing to their feet, the fishermen wave their hats as the airman swoops nearer. He sa- lutes them. But his face is serious. He scans the empty decks. No sign of rich sea harvest there. He sees the wheeling gulls, hungry voyagers that follow the fishermen, flying aimlessly around, cry- ing plaintively. The birds have not had breakfast yet. Nor have the men gone to work. Three days now the ships have beaten up and down the coast from Cashes ledge to Platts bank and thence to Steliwagen bank, patiently on the lookout, hoping for the sign of the great schools of fish. Empty holds wait for the welcome cry of Glimpse of Radio Compartment in Plane, and Receiv- ing Reports at Gloucester Coast-Guard Station discovery. The men listen to the radio pro- gram from the station at Gloucester, which 611

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612 POPULAR sends out the reports of fish prices, tells of the fish splitters waiting for work at the wharves, and gives the small receipts at Boston that mean higher prices. Now the motor of the plane catches hold once more and away it soars, turn- ing high circles, reaching for the fleck of cloud that has been driven down from the blue. The pilot smiles to himself as he gazes first from one side of the cock- pit and then from the other. He leaves the fleet miles behind. He scribbles a note to his observer, who sits below him with the radio operator. “Keep a sharp lookout for mackerel.” “O. K.” comes the answer. The radio operator sits in front of his transmitter. They are in the compart- ment below and to the rear of the pilot’s cockpit. At the right hand of the ob- server is a rack containing binoculars and writing pads. Near it is the speaking tube to the cockpit which is used, of course, only when the motors are silent. At his left hand is a small cage, made of wire and gazes down. MECHANICS wood, where sits a silver-necked homing pigeon, much at its ease. Now the blunt nose strikes against the breeze above Stellwagen bank. ship’s In the east the fleets fade away. The pilot can see far down into the clear water. A school of tumbling porpoises comes riot- ing from the west, bound eastward on some silly business of blindman’s buff More majestically sails a huge blackfis] as big as the plane itself, sliding through the waves, blowing lustily with a dash of spray as his curved back glistens in the sunlight. At this turn, the pilot discovers a new color in the blue water. It is a patch of darker shade and extends from west to east for a quarter of a mile. j the nose of the plane. Swiiftly it circles nearer to the ocean. 4 The wind screams in the struts. The patch of dark color takes on a phosphorescent glow. Its shade becomes bluish-black. Leaning far aver the side of the cockpit, the pilot A broad smile comes upon A Stormy Day for Flyers, but Lieutenant Melka, Right, and Commander Paulsen, Left, Get Ready for a Flight When the Radio Warns of a Ship in Distress

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POPULAR MECHA Beating Up and Down the Coast, Sometimes for Days, the Fishing. Boats, When the Radio Tells the Location of a School of Mackerel, Make Haste to the Spot his tanned face. He.is almost sure. A moment more of swooping descent—and he is sure! He sees a mass of black ob- forward. A foam bubbles and creeps and spreads around it in the : i advance, jects moving Mackerel! Millions of fish are gathered in the wide turmoil then a big mackerel throws itself over the backs of its myriad Now and aT Teliows. And as the plane comes nearer, again with motors sees silent, the pilot that the school is a monster of its kind. Thousands of doll The taken. ars swarm there. waits to be ar off the fishermen lie idle. treasure of the sea P Another note is passed to the radio op- erator: “Report to base the presence of large mackerel school four miles west of While the operator is speaking into his transmitter, the ob- server has written the report on a tiny Stellwagen banks.” square of fine paper which he has thrust into the little tube that the pigeon carries attached to its leg. He then leans out of the opening in the side of the ship and skillfully “tosses” the bird. With wings folded tight, the homer dives straight down to the sea, almost within reach of the spray of the waves. He circles three or four times and then darts toward the pigeoncote on Ten Pound island, at Gloucester. The message into the transmitter con- tinues: “Base No. 7. A-25 calling. A-25 calling. Base No. 7, come in. Base No. 7, come in, please.” Now he stops and listens. No answer- Again he Phen from his earphones a voice “A-25. A-25. Base No. 7 ca Come in.” ing voice comes. renews his signal. Base Come calls clearly: No. 7 calling. in. Come in. They begin to talk: on patrol wishes to report to the base the presence of a large mackerel school four miles west of Stellwagen bank.” No. 7 word or two of other matters are passed Base repeats the message. A

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614 POPULAR MECHANICS og. between the radio man in the plane and the operator on Ten Pound island. The plane soars back to height again. Lieutenant Melka gazes back at the fish- ing fleets, almost hull-down but plainer to the eve of the pilot as he gains alti- tude. The plane’s radio operator listens to the broadcast of the Gloucester sta- tion: “The Master Mariners association of Gloucester has requested this station to broadcast to the fishing fleet a report from air patrol from coast-guard Base No. 7, Gloucester, that a large school of mackerel is moving in the vicinity of four miles west of Stellwagen bank.” The speed of radio is instantaneous. It will be an hour, perhaps, before the pigeon flutters down into the coast-guz Be pigeoncote and waits for the removal its message tube. But already the ae has sprung into life. The auxiliary mo- tors sputter. Far up in the air, the pilot gazes down and sees the blue smoke from the exhausts puff out over the white wakes as the ships glide forward. Cheer- ily the men shout to one another as the schooners get under way. They have the word. Mackerel! Between the two converging fleets of fishermen the patrol plane now comes. Wild cheers greet it from the tipping decks of the schooners. Shouts and queries are sent up from mighty lungs. x yee: “— » ~ Returning to Hangar after a Successful Search for the Mackerel Schools But the coast guardsmen are at work iain. A wave of the hand that signifies, “Glad to help,” and off goes the great plane on the wide sweep of patrol. AIRPLANE SIREN WARNS PILOT OF STALLING DANGER Warning that an airplane’s speed has dropped to a point where there is danger of stalling is given by an automatic en which sounds only when the air spee drops below a certain rate. The screech of the siren can be heard above the noise of the engine and the instrument i l justable to any plane. The apparatus consists of two concentrically | mounted cages, } one moving clocl wise and the other counterclockwise. The inner cage i mounted against a spring and above stalling speed is forced back by the air- ‘A | flow against a Moc cork friction ring, but when the speed is decreased the spring forces the inner cage forward until it is rotated and the noise starts.

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POPULAR LOWEST PLACE IS THE SAFEST IN A THUNDERSTORM Safety from lightning in a thunder- storm will be found in the lowest possi- ble place, says an official of the weather bureau. He advises the person caught in an electrical storm to seek a low place and sit down, or even lie down. Nothing, particularly not an umbrella, should be held above the head. If the person is soaked to the skin, he may find relief in knowing that the wetting is a further protection, because wet clothes are good conductors. CYLINDER LIKE AN AUTO MOTOR ACTS AS HAMMER Tamping down paving stones without lifting, and dropping a heavy weight, is accomplished in Berlin with a ramming machine weighing about 200 pounds, which operates automatically. The heavy rammer has in its middle a single cylin- der, like that of a motor car, and gasoline tank, and the worker carries batteries ina ‘ase on his back, operating the ignition vy pressing a lever with his thumb. The piston throws an iron bolt at the bottom of the rammer against the ground and the whole apparatus jumps upward about eighteen inches from the impact, then tamps the paving blocks as it descends. Machine for Tamping Paving Blocks Contains a Cyl- inder Like an Auto Motor, to Operate It MECHANICS 615 A National Highway Was Rerouted to Preserve This Balanced Rock as a New Mexico Landmark BALANCED ROCK IS PRESERVED BY REROUTING HIGHWAY Monument rock, a natural pillar of shale and sandrock, near San Jon, N. M., has been saved as a landmark even though it was necessary to reroute a United States highway to do it. Engineers found that a logical tangent for a road would ne- cessitate destroying the balanced rock and put two curves into the road to preserve the stone, which to the casual observer appears about to fall at anv minute. Care- ful measurements, compared with measure- ments taken years ago, show that the rock is likely to stand for a long time to come PRICKLY PEARS AS STOCK FEED \fiter South African farmers had spent vears in vain endeavors to clear their lands of a species of cactus, known as the spineless prickly pear, it is now being cultivated for use as both food and water for cattle during prolonged drouths. It contains a large percentage of water and mineral salts, and has been the means of saving the lives of hundreds of cattle dur ing dry periods, which sometimes extend for as long as two years.

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616 POPULAR MECHANICS SHIPBUILDERS VIE sipifetdponn otis paren "| 4 ¥- FOR ATLANTIC RECORD pita, off Ocean liners propelled by steam turbines devel oping up to 160.000 horse power are in prospect a result of the records hung up bv the German ship “Bremen.” When the “Mauretania” built twenty-three vea ago engine ( Ve oped 75.000 horsey f more th 1 dou ri€ power oT in tu r then in € tence was Dp licted that t 3 on would shake pn to piece Ye Bret € ch he Atlantic ( ve d | urbines « ing the “Oceanic, sel of 60.000 ton Lights Illuminating This Tower Are inside the Dome, Which Is of a Shutter- like Framework through Which the Light Passes DOME’S OUTSIDE ILLUMINATED BY INSIDE FLOODLIGHTS Internal floodlighting has been used to illuminate the outside of the dome of a Brooklyn bank building. The dome is not of glass, but its curved surfaces are built up of horizontal louvers, or sloping overlapping sections of metal. Viewed by an observer from any point below the level of the dome, these louvers overlap and their gilded surfaces appear to the eve as a solid gilded dome. The sur- faces of the louvers are lighted by lamps placed on the floor within the dome, and colored lights, through a cycle of auto- matic changes, give a variety of effects. @ Wire automobile wheels are being made from a high nickel, chromium, steel alloy that neither stains nor rusts. = it is reported, will b General Electric ( pelled by the irgest Diesel-electric marine plant ever built, and the Cunard line is planning one or more ships , te be propelled by steam 160.000 horsepower, or even larger “s \ ss ines developing twice as much as the “Mauretani The race among shipbuilders to reduce he time of passage across the 3,000- mile expanse of ocean recalls that the first steamship to cross the At ic , , took twenty-six days. Columbu . sas , he passage in a little more than two months and until scarcely a century ago many sailing vessels consumed almost as much time, although clipper ships often nade better speed than the early steamers, one of them making the trip in thirteen and one-half days. The American-built “Savannah,” only 100 feet long, was the first steamer to cross, but she used sails to assist her paddle wheels in rough weather. The little boat “Sirius” I was the first real liner, and in 1838 reached New York one-h came recor Brist than reduc unde he ( S1X d set Paris atta in

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POPULAR York from Queenstown in eighteen and one-half days, but the “Great Western” came into port a few hours later with a record of thirteen and one-half days from Bristol. In 1864 the time was cut to less than nine days, and in 1872 it was further the White Star line to a trifle reduced DV under eight davs. The “Oregon” made he Oueenstown-New York run in 1884 in nine hours and forty-eight min- six days and five vears later the record was der six days by the set at u “City of Paris.” The rivalry finally resulted in the uilding of the “Mauretania” and “Lusi- tania,” and now liners are planned to llv reduce all records PLANE BEATS HOMING PIGEONS Man scored another victory over na- ture recently when an airplane won in a ice from Chicago to Detroit with four oming pigeot The birds, long consid- ered faster than pl ne vere released by he pilot as he stepped into his cockpit, bu é one did not reach Detroit un- tilan hour and nineteen minutes after the s bird previously flew in four plane rived. Thi 1 €xX.,. tO Detroit davs and eleven ] ours STEEL MESH WITH FIBER COAT MAKES PLASTER BASE Steel mesh coated with bands of pressed fibe s being used by contractors as a plaster base to provide fire resistance, dening and rat-proofing of walls. The rigid teel mesh is supplied in sheets of two square yards, and makers claim the base’ not only af- fords more sub stantial construc- tion, but results in plaster econ- omy in addition to other advan- tages. The subject to weather changes and neither shrinks nor swells, while overlap- Ping at joints eliminates joint cracks. The fiber-coated back of the mesh base pre- mesh is not vents plaster from penetrating or falling. MECHANICS A Camper’s Bed Which Is Stored on Top of the Auto mobile When It Is Not in Use CAMPERS’ BED ON TOP OF AUTO GIVES MORE SPACE IN CAR Prepared for occupancy in a few sec- onds, a comfortable bed for campers is carried on the top of the automobile, leav- ing all space in the car available in the daytime. The bed, equipped with spring and mattress, rides in a ngar placed on wooden slides to which clamps are at- tached to hold it rigid. W) set up, one side ien the bed is rest on supports on the car just above the fenders. \ Vi aterpr« of tent with netting windows also fits over the bed and is attached to the car, this be- ie hangar in the daytime Che is of regular auto-top ma ing carried in t or used as a fly tent. roof that covers the bed 1 terial and is supported by a light wooden frame. A CLOTHESLINE WITHOUT PINS Clothespins are unnecessary with a clothesline made of two strands of wire twisted tog ‘r. Between the wires runs a brass separator consisting of two small wheels on an axle, the clothes being placed wires as the line, between the separator is while the latter closes to hold the wash as the separator is moved. The separator cleans the line as it is moved along the wires. pushed along the also

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“A WAY beyond the dawn of history, a 3,000 or 4,000 years ago, one thinks of the Wiltshire uplands in the twilight of a midsummer day’s morning. The torches pale in the growing light. One has a dim apprehension of a procession through the avenue of stone, of priests, perhaps fantastically dressed with skins 618 oe me | ot painted masks—not the nitaries our artists rep resent the have been—of chiefs skins adorned with neck laces of teeth and bear ing spears and axes, thei gvreat heads of hair held up with pins of bone, 0 women in skins or flaxe: robes, of a great peering crowd of shock headed men and naked children. They have assembled from many _ distant the ground between the avenue and Silbury Hill is dotted with their en- campments. A certain festive cheerful- prevails. And amidst the throng march the appointed human victims, sub- places ; ness and horns and _ horrible. —y robed and bearded dig- Druids to

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se 4 ' i How the Big Stones May Have Been Set Erect by Dragging Them up Earthen Ramps, and Stonehenge as It Is Today; a Modern Druid Meeting in Progress we missive and helpless, distant to die—that the harvests may be good and staring toward the smoking altar at which they are the tribe increase. eressed 3,000 o1 To that had life pro- +000 vears ago from its starting place in the slime of the tidal beaches.” So wrote H. G. Wells, the famous nov- elist and historian, and that is one theory a very probable one—of the mysterious origin of Stonehenge, the strange stone circle in Wiltshire, England. Another theory is that the ise men of the ancient Britons, described by Julius Cesar as and Druids, or living in dens woods and caves, built Stonehenge as an astronomical observatory or temple. As a matter of fact, Inigo Jones, archi- tect of King James I of England, who in- vestigated this strange circle, knocked the Druid theory of the origin of Stonehenge on the showing that it built hundreds of years before the rise of the Druids, who, however, may have used it. Some 12,000 to 20,000 vears ago, a new Stone-Age people, made _ polished stone implements and began to domes- ticate animals, arose either in the now head, was who n Ol in ubmerged Mediterranean ba ] western Asia, or north Africa, and ally spread eastward over Europe, which vas recovering from the last great Ice Ace. Thev began to sow and erain, and by some strange process of rea- that the sacrifice of a , chosen human being soning co ceived wou d conduce to a } 1 successful These people deve oped what Prof. Eliot Smith call C4 harvest. sa “Sun- one” culture, and wherever they mi- grated, set up vast pyramids and mounds, and circles of big stones, perhaps to aid the astronomical observations of their priests or wise men. haired folk with round heads and skulls broader than long. They were a dark curly em in Britain, an earlier race with fair hair, who built a vast circle of Precedit i th of long-skulled men tended flocks, had tones on Salisbury plain, not far from Stonehenge. Today, only about twenty out of the remain at t original 600 enormous stones he original site. Circles of stones also are found in Cornwall Wales. vere believed to possess magical such and ship and or medicinal properties. The fame of the stone circles spread all They were objects of wor- over Britain and reached the ears of the men on Stonehenge Down. The Bronze Age was just beginning, when, it is sur- mised. the folk of Stonehenge—then a center of manutacture of stone tools, axes, and weapons—made a raid on such a cir- 619

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620 POPULAR MECHANICS cf aK ( Abin thi Hi | pti Wiltshire country, took photographs which re- vealed hidden lines indi- cating the old trackway over which the stones were dragged on rollers by Stonehenge men pull- ing on ropes of hide. Ex- cavators have confirmed this fact. Today, Stonehenge is bounded by an earth- work, 300 feet wide and approached from the northeast by a_ banked avenue of great width. At first sight, a chaos of fallen and upright stones meets the eye. The ap- proaching visitor sees a unworked stone called the “Hele stone” or “Friar’s heel.” Hele is an Anglo-Saxon word large, suggestive of the Greek word Helios, or sun. The Hele stone, over which the sun appears to rise at midsummer-day dawn, is some yards outside the earthwork. Passing inside the earthwork, the visitor sees on his left a block, called the “Slaughter stone” and thought to have been used asa place of execu- at tion. This stone is one Stonehenge as It Probably Was Some 4,000 gg Ago, and Plan of Original of the myst eries of Structure with a Stonehenge. Excavations cle of blue stones in the Prescelly moun- under the Slaughter stone have sliown tains of Pembrokeshire, South Wales, 170 miles overland from the Wiltshire plain. A fierce battle was fought between the fair-haired long-heads and the dark men of the round-headed invading race, and 115 of these blue stones were taken by sea from the coast of Wales around the shores of the English Channel to the mouth of the river Avon, in Hampshire. Up this little river, ang foreign blue stones were sent on raft » West Amesbury in Wiltshire. Recently, a British government air- plane, surveying and mapping the North that the ancient builders intended to bury it in a hole roughly dug in the chalk, and just deep enous ¢h for the soil to cover the stone at ground level. But the builders made the hole too short, and so the stone rests on the sloping chalk at either end. On the outside of the circle, and within the 300-feet-wide circular earthwork, are two rough, unworked stones, one of which appears to mark the rising of the sun on the winter solstice, and the other its setting on the summer comes a ring of unhewn stones, twenty-one feet high, r solstice. Then about standing upright, Cou Sk

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POPULAR iortised to their tops. The with lintels 1 1 i he circle is 108 feet. diameter of t Next comes a ring of hewn stones brought by sea from Wales, of which seven are still standing, and nine prostrate, out of ) the thirty or forty original stones. Behind these, in the next circle, once stood five ereat trilithons in horseshoe formation, opening to the northeast. Inside the site e trilithons, of which only one still tands, is a ring of smaller upright stones, so in horseshoe tormation, Then the eve falls on a singular, flat block, called the “Altar stone,” almost wuried beneath the remains of a fallen l possible that this stone been a roster or platform here is no proof that it ever was uprig! voking northeast from this slab, through S F day e ve mii Sut ¢ ce—t 0 I et s mono one looks trom cent yn the Altar stone. All round Courtesy Frank Stevens MECHANICS Sketch of the Huge Blocks as They Appear Today, and Another Solution of the Construction Problem, Tip- ping the Stones into a Pit with the Aid of Tackle

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622 on the plain are great numbers of prehis- toric burial mounds, or barrows, which may house the long-dead builders of Stonehenge, or may be the graves of the famous and forgotten chieftains of the new Stone Age. The engineering of Stonehenge is re- markable. How were the great trilithons raised when men had none of the derricks, slings and electric hoists of our modern days? The only tools used were crude hammer stones or mauls of flint. E. H. Stone, an English engineer, suggests that a man of extraordinary ability designed and supervised the erection of the stone circles. Foremen or overseers measured the for the foundation pits of the great monoliths and trilithons, while other men dressed the great stones, shaped and repaired the stone and flint tools, dug the foundations, sites and lugged the stones into place. No articles of metal have been found near the site of Stonehenge, show- ing that no Bronze-Age men using metal tools were emploved. The stones probably were split in a way similar to that still practiced in parts of modern India. Men stood in a line across the stone. Each one held a his head, gripping the maul with stone above tool POPULAR MECHANICS both hands, and at a signal from the over. seer each man simultaneously dashed his maul on the slab, and so split it across, Quartz mauls have been found at Stone- henge, showing signs of this terrific bat- tering. Then, the stones, resting on tim- ber rollers, were tugged across countr by men pulling on ropes of hide. The difficulty of the job can be judged from the fact that each of the trilitho: uprights weighs forty tons, and each block and lintel weighs twenty-six tons. Sey- enty-five blocks were needed, so that the total weight of these alone was 1,950 tons The master engineer probably laid the design of Stonehenge by marking circles out the with a rope staked to a center on the ground of the site. The great circle was divided into thirty equal parts and the space for the stones marked out on the ground. His first problem was how erect the forty-ton uprights. differes but it was arranged that the tops of the stones forming the seatings for the lintels should, These were of heights, great stones after erection, be as nearly as possible at a uniform level. To do this had to be dug at vary- ing depths, according to the lengths of the stone uprights. The bottom of th the foundation pits e pits aa —— 7. ; Frank Stevens The Mysterious Blocks of Stonehenge as They Are Today over the Structure Wiltshire Downs; Possibly This Strange toa i May Have Served as a Place of Sacrifice of Human Victims on Each Midsummer Day When the Sun Rose over the Plains; the Upright Megaliths Are Over Twenty-Two Feet High and Several of the Lintels Are Still in Place

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POPULAR was carefully excavated to correspond with the shape of the bottom of the stone, to secure a firm foundation. Round SO as nits. the ground was rammed hard as tform for the stone. Then, the great stones, on rollers and with the flat-dressed ce uppermost, were rolled over the floor. eac me end on, and so balanced as to » itse to the pit Mr. Stone suggests { rough derrick, made of a pair of timbet eer legs, was used to raise the 7 me ¢ ¢ ere is no direct evidence to show ( é one-Age men got the lintels ( op ot the uprights, twenty-two a1 da t high. Mr. stone believes a bank t i t own up around each pait tone The top of the earth 1 1: t. med flat to make a working stage, a e which the tops of the big uprights - a lao ont ed a te inche ihe bank so 1 the prigh as to exert equal ressure on all sides, and hence not sh Then the he sloping side of the foundation. nd set on top of the upright. | or sees, just inside the ear ork circle of Stonehenge, a puzzling series of twenty-three holes in the chall li of these contain cremated human em s, and in three the signs are that the cremation w done on the spot. he mauls used in dressing the great tones weighed from thirty-six to sixty were wielded by two to ] ur pounds and ree men. Picks of deer horn may have l to cut t s of the uprights, he holes for the founda- een user since splinters of rn have been found in these pits. Even today, after years of patient re- MECHANICS 623 RADIO WIRES KEPT OFF FLOOR WITH BASEBOARD CLIPS joey i me) ! — ed — Baseboards Keep Radio and Wires off the Floor Metal Clips Ir Tel Clip th mav be inserted in base oards, door frames and moldings serve to keep lamp, radio and telephone wire off the floor. lhe metal fasteners are 1 . pped into the space between the trim nd the wall, the top bei reg bent to receive TALKS TO LONDON FROM PLANE FLYING OVER NEW JERSEY falking with persons in London while oaring in an airplane 2,000 ladlev field. N. |] leet ovel was accomplished re a hookup of radio and loneg-di tance telephone wires. lan in the plane was sent to the ‘e] b scientists do not really know the search, exact purpose for which Stonehenge was built, nearly $000 years ago. Vas it intended for a court of justice, a hall for ceremonial chiefs meetings of and kings, a sun temple for sacrifice of human victims, or a hall for the ell laborat ries ground station at Whippany, N. J., by radio and there picked up and re layed over transat lantic wires. The call was completed in a few seconds, but the first versation was ham con pered by considera ble interference, al though the voice rites of the dead? No one is sure, Airplzne Passengers Talking with London by Tele- phone and Radio While Flying over New Jersey from London was distinct.

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Memorial of Some Long-Forgotten Event, This Sixty- Foot Monument Stands in the Holy Land FORGOTTEN STORY OF ANCIENTS TOLD BY MONUMENT Built to commemorate a _ forgotten ancient monument the ruined citv of Baalbeck, is Sixt) stands near Syria. It and on its sides sculptured hunting and hunting regalia, but of its origin, age or its build- ers, hit event, an feet high are scenes nothing is known. MOISTENER SEALS ENVELOPES AND CLOSES FLAPS Sealing envelopes in the busy office is accomplished quickly with an automatic moistener which not moistens the flap but closes it securely so that a slight only pressure on a pile of finished letters is all that is required, thus keeping the enve- lopes clean as well as eliminating sealing rhe by mout sealer consists of a container in which a supply of water is kept, the moistener respond- metal ing to a pressure of the thumb when more water is wanted on the felt pad used for seal- ing. The moistener is mounted above a frame shaped like a lip through w’srich the flap passes to be sealed. POPULAR MECHANICS SUBMARINE BLOWN TO SURFACE WITH CREW IN TESTS largest undersea fightin was rescued from America’s craft, “V-4, by being blown to the surface with her ting 4 the deep } crew of eighty-seven officers and men ji tests off San Diego, Calif., hailed by naval authorities as marking another make these craft safer. Fresh air was sup- step to plied to the submarine’s compartments the old air was exhausted, and finally the sub and its crew were brought to the sur- face by compressed air lines from the res- cue which the of the boat eighty-six feet Thirty-nine minutes after the settled to the bottom a diver from the rescue boat was on its deck and had connected an air hose to its Fresh air vessel blew ballast beneath the surface. submarine salvage was sent into one then air was pumped from one compart- \ aly es. com- partment and another, and _ finall tne ment into another and completely throu the vessel. Air pressure then was applied to the main ballast tank, and twenty-three minutes later there was a rush of foam and boat i any action on the part of its crew. the submerged was afloat without WAR ON DREADED FRUIT FLY WAGED IN FLORIDA Described as the “oaudiest lady and most the damag- ing pest of Bug- ville,” the Medi- [ terranean fruit fly \ is being attacked in F] army of ——— orida by an 5.000 and scientists orkers equipped with chemicals, spravers and other impediments of war. The dreaded fly succeeded in almost ruining the citrus crop before the counteroffensiv started, and placed a fund of more than $5,000,000 at was state nation having the disposal of the attacking army. It is the female that does the damage, laying eggs in seventy-two kinds of fruit, includ- ing the orange, lemon, grapefruit, pear, plum and Strict one of the measures taken, with the state militia seeing that it was maintained. apple. quarantine was c 72

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ACE iting deep her aval

POPULAR MECHANICS 625 OLD WARSHIP IS TURNED INTO FLOATING CLUB

—<—<————$—

The U. S. Monito-, Which Guarded New York Harbor during the World War, Has Been Transformed into a Floating Country Club and Serves as a Summer Resort for Long Island Society Transformed into a floating country club, the former U. S. monitor, which guarded New York harbor from subma- rines during the World War, is now uti- lized as a summer resort for the social elite of Long Island. PLAN FILMS OF LIBRARY BOOKS TO CONSERVE SPACE Confronted with the prospect of “drowning in books,” librarians of the Berlin state library have advanced a plan for photographing the books and storing the celluloid film to save space. Books photographed page by page on a celluloid film, it was found, could be stored in less than one-fortieth of the space needed for the printed vol- umes. Old and precious examples of the bookmakers’ art, when photo- graphed, would need no longer be exposed to the wear and tear of usage, and new books, having no particular intrinsic

Tracing Drawings.and Art Work on Wax Stencils Is Made Easy with This Tracing Frame value, could be destroyed after being filmed. The photographic system would first be used for books seldom called for and a special film-reading room would be established for the celluloid library. A small projection machine beneath each table would throw the pages on individual screens so students would be able to read while seated comfortably in armchairs, the book film operating like a movie film. FRAME FOR TRACING STENCILS MAKES DUPLICATING EASY Tracing drawings, art work and maps on stencils is simplified with a tracing frame, adjustable in six positions, in which the stencil is locked by two clamps. It may be used for any type of rotary duplicating ma- chine, the equip- ment including a glass with a ground surface to insure sharper lines, a transparent cellu- loid tracing sheet and celluloid trian- ele for ruling.

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other “bird islands,” oc- cupied only by sea flyers, here the shore, land and ocean birds live side by side, an interesting and unique example of the manner in which wild Young California Brown Pelican, and a Rugged Bit of the Coast along the Bird Retreat By H. H. DUNN Photography by Lee Passmore and the Author | eoranaad by several pairs of bald eagles, whose ministers of war are ospreys, five small islets, ten miles off the western coast of Mexico and twice as far south of San Diego, form the most complete bird empire in the world. Into this harshly dominated kingdom, mammals, even man, have not entered, with the exception of one small variety of field mouse, and sev- eral herds of sea lions. Protected by the government of Mexico, and watched over by that of the United States because of their inviting possibil- ities as centers of smuggling operations, these five Coronado islands are so sur- rounded by red tape that few, save scien- tific expeditions, ever visit them. Unlike 626 life rules itself when completely tree trot man’s influence. Rising straight from the sea, composed of granite—the “backbone of the Earth” —covered with a scant layer of soil, in which low brush, the offer few landing places, there being only grows Coronados aaa

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in dos ynly ee Pelicans and Gulls, the Nesting One ‘“‘Talking” to the Photographer; Pelicans Attain Nearly Full Size Before They Discard the Down of Babyhood or Are Able to Fly one on North Island, the largest of the group, and one on South Island, next in size. At the former, an expedition from the San Diego Museum of Natural His- A few of the re- sults, some of them the first photographs of their kind ever made, are shown here- with. An estimate, made by trained observers, places the winged residents of the Coro- nados at 100,000. One of the mysteries of the islands is the presence of several flocks of California valley quail. - If they arrived there in recent they must least ten miles from the main- land; if they were there when the islands were separated from the continent, as the floor of the sea sank, they are indeed old- timers, for this parting occurred, accord- ing to the geologists, not less than 10,000 years ago. tory landed recently. years, have flown at On this same island, too, are the smallest birds in the world—humming- birds. They are not so mysterious, for they fly annually hundreds of miles in their migrations, but the quail are not migrants. This avian empire is divided into dis- tinct states, territories, zones, or what- ever one wishes to call them, each inhab- ited by one variety of bird—with the ex- ception of the gulls, which, preying on all their neighbors, nest where they rob whom they please, and generally lead the lives of winged “racketeers.” First and closest to the shore come the Brandt cormorants, flyers, underwater swimmers, divers and the best fishers of all birds. please, In vears past, these cormorants nested by thousands on the flat shelves of the Coronados; today there are only a few hundred, due to the depredations of the great black-and-white wv ‘stern gulls. Here, at the very boundary of the Bird Empire, we began to see the workings of its gov- ernment. As we stood photographing and counting the cormorant nests, one of the birds appeared, loaded with a fish, driving at top speed from the sea toward her home. Before she reached the land, 627

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628 POPULAR MECHANICS him, always screaming, always striking, until he also dropped the thrice- looted dinner. Then the eagle, again folded into the spearhead, fell, seized the fish before it struck the water, and zoomed in a thousand-foot rising slant, to scream in tri- umph as he sloped down again to his mate and nestlings on the lofty ledge. So life goes in the Bird Empire: rob or be robbed; kill or be killed; survive by wit or wings, or both, or perish as unfit. Rather sharply cone- shaped, the eggs of the gulls offer an interesting phase of nature’s protec- tion for bird life. Being of this contour, if one or Playful Sea-Lion Pups Parked in a Stone-Walled Refuge of the Bird Empire While Their Mothers Go Fishing a gull fell upon her, and as the cormorant released the fish, the gull dropped to the water, seized the booty and rose in the air. There was a scream from above, and an osprey, watching from the cliff four hundred feet higher, struck at the gull. In and out and round about they went, cutting circles, loops and spirals in the air until the gull, turned from her own nesting place, put out to sea. The osprey followed, flying beneath the gull and driving her ever upward, until at last the first robber dropped the fish, while the pursuer, folding his wings, fell faster than the falling mackerel, took it in midair, and rose on a long slant toward the cliff. But he was not to enjoy his loot. From far aloft there came, in total silence, but with the speed of a ten-inch shell, the body of a bald eagle, folded compactly into a living spearhead, with a snow-white point. Passing within what seemed to be inches of the osprey, the eagle found wing, turned upward, and struck at the fish in the hawk’s beak. The osprey dived, swerved, lifted, at a speed which would have taken the swift- est duck, but the eagle was always with all start rolling, they wing in circles, on the smaller end as a center, coming back to their original position. Thus, on bare ledges, or in scanty nests, or when disturbed by the sudden rising of the parent bird, the eggs do not roll away. More than this, their tendency being to roll together, they remain in the center of the warm area of the mother’s body, thus aiding incubation. Sea-lion puppies, one-third grown, snapped at us when we undertook to play with them, some fifteen being parked in a small stone gully, while the mothers went fishing out at sea. A huge brown pelican waddled along beside us, as if familiar with man. Suddenly there was a whimpering in the air, and from the earth- covered slopes above, little murrelets and Cassin auklets by thousands began to pour from their burrows for their flights. Night had come to the Empire of the Birds. @ 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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Anna Hummingbirds, Fast Out- growing Their Nest; These Dimin- utive Birds Evidently Cross the Channels Separating the Islands from the California Mainland and the Mexican Shore California Valley Quail Play Tamely around the Photographer on South Coronado Island; Here Is One of the Cocks of the Flock Which Does Not Migrate, Although the Mini- mum Flight from the Mainland Would Be About Ten Miles; Be- low, at Left, a Murrelet, Pulled from Its Nest in a Hole in the Rocks Four Hours of Patient Stalking, Most of the Time Prone on the Ground, Were Required to Obtain This Photo- graph of the Western Gull with Her Nest and Eggs e

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630 POPULAR ALL-METAL AMPHIBIAN TO CRUISE LONG DISTANCES MECHANICS TT HTL TT HH aaa of 4,000 miles. The ship has a wing spread of seventy-two feet, it is forty-three and one-half feet long and loaded, weighs 14,000 pounds. It carries Views of the Amphibian under Construction and, Below, Erwin Greer, at Left, and J. H. Wendt, Designer of the Craft, Holding a Small Model Flights over the oceans will be most successful with amphibian planes, in the opinion of many aeronautical engineers, and to further demonstrate the efficiency of these craft, a novel amphibian has been built in the shops of Greer college at Chi- cago. Outstanding features are its all- metal construction, the elimination of pontoons and the use of two smaller aux- iliary motors besides the three 300-horse- power engines in the main power plant. These smaller motors, according to J. H. Wendt, the designer of the ship, will be employed to keep the craft flying once it has attained speed and altitude, so that all the big engines will not have to be run continuously. By this arrangement, a saving in fuel will be effected, giving the amphibian an estimated cruising range twelve passengers and two pilots and is equipped with cabin conveniences of the most luxurious air liners, including radio-receiving and transmitting apparatus. CITY NOISES TIRE STRANGERS Visitors in a large city burn up body energy one-fifth more rapidly than aver- age residents because of the effects of city noises upon the nervous system, accord- ing to experiments conducted by a neu- rologist in New York. The city dweller, he found, became immune somewhat to city noises through adaptation, but the stranger responds to the unusual clamor with a reaction’ which increases or de- creases the respiration rate, tends to create abnormgl muscle tension and some- times causes heart changes. ~—m 7H A. ~-~_ — ~—

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POPULAR MECHANICS 631 PHONE WIRE ON GROUND HELPS GUARD FORESTS A forest-fire patrol observation post in the far west is connected with the outside world by a single iron wire lying on the rock and snow of the mountain. Members of the hiking parties that often climb this mountain, observing this wire, are usually unable to understand how a _ single-wire grounded circuit can operate un- der such circumstances. The ex- planation is that very low-resist- ance iron wire is used and that snow and rock have little con- ductive ability, hence do not ground the wire. As it is not possible to secure good ground on the top of the mountain, a wire leads from the observation cabin to Crater Rock, 800 feet below, where excel- lent contact is made in the place where the steam issues from the ground. VANISHING TOP CHANGES TRUCK FROM CLOSED TO OPEN VAN Converting a closed truck into an open van is made possible by a disappearing top and collapsible sides, all of which are shoved away out of sight. The roof over the driver’s cab is divided into two parts, and it is between these that the truck top disappears. The upper part of the casing over the cab is hinged and may be lifted up. The rubber van top slides on metal crosspieces which are bent around metal rods along the top of each side of the van. Over the topping and crossbars are metal plates, to force the top to fold as it slides back and to prevent the fas- tenings from working loose. The top also may be entirely removed. The sides are formed of hard- This Machine, Resembling a Steam Roller, Marks Crisscross De- signs in Asphalt to Keep Vehicles from Skidding PREVENT SKIDDING IN STREET BY DESIGNS IN PAVEMENT Streets in Berlin, Germany, are being made skid-proof by a huge machine which stamps into the asphalt pavement a deep crisscross design, the lines of which pre- vent slipping. The engraving is some- what similar to the designs on the treads of some automobile tires which are in- tended for the same purpose. The ma- chine that does the stamping resembles a gigantic steam roller. QUAIL CHECK POTATO BEETLE Reluctant small boys who spend many back-aching hours over beetle-infested rows of potatoes soon may relinquish this unpleasant task to the quail or bobwhite. Experiments have shown this attractive game bird has a decided taste for the po- tato beetles, and if given a chance, will clean them out completely. Where bob- wood panels and slide in grooves ‘in the standards to open or close any section. The panels are held in place by setscrews and rub- ber plates, making whites are pro- tected by a closed season and increase greatly in numbers, potato beetles have been found to di- minish to such a de- gree that it is no longer necessary to each panel section adjustable. Vanishing Truck Top Which Slides into Roof of Cab to Convert It into an Open Van spray vines with poison,

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632 POPULAR MECHANICS toration of oxygen. At the same time tests were made of a diving apparatus which is said to permit divers to descend 300 feet. The previous record was 204 feet. This appliance reduces to one-third the time of decompression and freedom from the effects of nitrogen. As soon as the diver is ready to come up to the point where decompres- sion must begin, a cylinder with an attendant inside is lowered and this man helps the diver into the cylinder for the de- compression period. Its advantage is that it does away with much armor. LAWN MOWER RUN BY CURRENT FROM LIGHT SOCKET eee SS Lawn mowing is made easier and quicker with Contrasting in Appearance with the Ordinary Plane Is This Ship with a an electric mower that is Flanged Cylinder for a Propeller PROPELLER LIKE HUGE BARREL TESTED FOR AIRPLANE Resembling a huge barrel with the ends knocked out, a cylindrical propeller has been tested for an airplane whose con- struction is in odd contrast to the ordi- nary plane. Projections inside and out- side the cylinder give it the appearance of a turbine flange, and when the cylinder is whirling the flanges operate in a man- ner similar to a screw propeller. While differing radically from usual methods of construction, the craft underwent suc- cessful ground tests recently. ESCAPE FROM SUBMARINE AIDED BY BREATHING APPARATUS Successful tests of a breathing appa- ratus enabling trapped submarine crews to escape from deep water have been made by the British admiralty. Sunk to a depth of 126 feet, those making the tests reached the surface safely in a min- ute and a quarter. The apparatus, weigh- ing less than five pounds, is attached to the chest and has a flexible breathing tube through which exhaled air is regenerated by absorption of carbon dioxide and res- designed like the small hand machine, except that it has a mo- tor that is attached. The mower cuts around shrubbery and hedges better than the hand mower because the blades re- volve whether the wheels turn or not. It is light in weight and equipped with rub- ber tires to avoid noise. A Hand Lawn Mower with Electric Motor Eliminates Some of the Work of Cutting the Grass

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Za Ss, Bla cklighrt p OMBINATION of television with “noctovision”—seeing things at night by invisible light—is to be used by the British government to guard England against aerial attack. Searchlights which cast no visible rays will sweep the skies above the Channel coast at night in war- time, pick up invading aircraft with their unseen light beams, and furnish the illu- mination to transmit the picture of the invader to the anti-aircraft batteries on the ground, to the airdromes of defend- ing pursuit squadrons, and to the war of- fice in London. Two devices invented by John L. Baird, the English television expert, are to be combined. Secret tests have already been made before Lord Allenby, the conqueror of the Turks in Palestine; Lord Arnold, Admiral Sir Mark Kerr, Sir Thomas In- skip, Sir Herbert Samuel and others, rep- resenting the army, navy and air force. Experiments in long-distance transmis- sion of night scenes are about to be inau- gurated between London and New York. The Baird noctovisor utilizes the in- visible infra-red rays—the band of vibra- tions below the visible red of the spec- trum, rays of a wavelength so long the eye cannot see them. They have sixteen times the fog-penetrating power of visible light, which makes them particularly useful in a climate such as England has. In operation, the searchlight, fitted with carbons which produce large quantities of red light and little of the shorter wave- lengths, is covered with a black screen, usually Corning glass, which prevents the escape of any of the visible light. As it sweeps the sky, nothing can be seen, and from above it cannot be detected, save for a tingling sensation in the eyes, if one looks directly into the beam. The sensation is somewhat like the feel of looking into an intense light, though the eye sees nothing. A photo-electric cell on the ground, however, picks up the image of the plane overhead as easily as though it was bathed in visible light. From that stage on, ordi- nary television processes complete the transmission of the picture. The Baird apparatus is still in the ex- perimental stage, but the army, navy and 633

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634 POPULAR MECHANICS Sir Oliver Lodge and J. L. Baird Examining Experimental Apparatus by Which Images of Aircraft or Other Objects Are Transmitted on Beams of Invisible Light at Night and Seen on Small Screen air-force officials who viewed the tests were all enthusiastic about its possibili- ties in the defense of London from enemy air raids. The air-raid problem has been given intensive consideration since ma- neuvers last autumn showed that squad- rons of planes could penetrate all exist- ing aerial defenses and reach the heart of the metropolitan district with ease. Navy officers were particularly inter- ested in the possibility of applying the noctovisor to warships. They pointed out that in a battle between two fleets, fought at night, the one equipped with invisible light as eyes would have all the advantage. The ability of the infra-red rays to penetrate fog and smoke screens also would be of great importance. The use of invisible light rays at sea is not a new thing, for it was first developed during the war by the American navy as a means of keeping convoy ships in line without showing navigation lights. In- stead of infra-red, ultraviolet lights were used. On the stern of each ship in line, an are lamp producing high ultraviolet values was placed, covered with a Corning glass screen, a sheet of black glass which no visible light can penetrate. The watch officers on the bridge of the next ship were equipped with a fluoroscope, such as is used in X-ray work, and with this they could see the signal light plainly, while it remained invisible to the enemy. Neither noctovision nor television can see farther than the human eye, but the ability of the former to penetrate atmos- pheric conditions which balk the eye, gives it its value. In experiments in Cal- ifornia, photographs have been taken, through fog and clouds, of sequoia forests more than 200 miles away, and infra-red pictures of Pasadena, taken through the fog from the observatory on a near-by mountain top, are regularly used to check similar infra-red pictures taken of Mars. OLD THEATERS TRANSFORMED INTO SWIMMING POOLS Old theaters, usually difficult to dispose of, are being remodeled into swimming pools in New York. The sloping floors make conversion into pools easy, and the balconies provide space for spectators. Four vacant theaters will be so used. a= = _—_— yr one o ela

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POPULAR HAY DRIER REMOVES MOISTURE IN FORTY SECONDS Acting somewhat on the principle of a corn popper, a giant hay drier shreds and removes the moisture from hay in forty seconds, during which the grass travels through 1,500 feet of pipe and is delivered in bags ready to be hauled to storage. Green hay is fed into the machine, cut into inch lengths and then blown through. a series of insulated pipes where it is sub- jected to a temperature of 700 degrees. The exhaust from two gasoline engines used as power first strikes the hay as it passes through the pipes, after which the curing is completed by steam and various gases of combustion. The hay does not burn or bake because it passes through rapidly, and at the time the highest tem- perature is reached, there is no oxygen in the chamber to support combustion. In the early stages, the principle of the corn popper is used, for, as the heat in- creases, a small volume of steam is created in each tiny stem, causing a mild explo- sion which blows the piece open. Hay comes from the drier somewhat shredded and pulverized, but retains a green color and typical odor. An automatic stoker assures a fairly smokeless exhaust, keep- ing the hay from becoming sooty. MECHANICS 635 Hay Drier Works Like a Corn Popper to Remove Moisture from Grass in Forty Seconds Diagonal Lines and Headlike Designs Give a Facade Effect to This German Business Block CROSSLINES ON BUILDING GIVE UNIQUE EFFECT Diagonal lines which form a crisscross design have been used to produce a re- markable appearance by the architects of a mercantile building in Hamburg, Ger- many. Combined with these lines are pro- jecting headlike designs which give a facade effect rarely carried out in a tall business block. INDELIBLE COLORED PENCILS LIKE WATER COLORS Colored indelible pencils now are be- ing produced with a thin lead that will take a sharp point like an ordinary pencil for fine work. The leads, in twelve colors, are stronger and more durable than those in the ordinary colored pencil, and the makers say they will last about three times as long. By going over the fine markings with a moistened brush, wash effects are obtained, the shades blending like water colors. The pencils are used for sketch- ing diagrams, maps and charts. They may also be used to supplement colored inks.

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636 POPULAR MECHANICS WIND DIRECTION IS INDICATED BY LANDING FIELD LIGHTS Model of a System of Sunken Ground Lights for Air- ports Which Also Shows Wind Direction Ground lights on airplane-landing fields may serve the double purpose of indicat- ing the exact center of the field and show- ing the prevailing wind direction. The arrangement includes a series of eight glass-covered trenches shaped like the spokes of a wheel in the center of the field, which light automatically to show wind direction. They are faced with heavy plate glass capable of sustaining the weight of a plane and are wired sepa- rately to a rotary switch driven by a wind vane, the vane switching light to the trench which lies toward the wind. A white and red glass combination on the trench makes it easily seen from the air. REDUCED SIZE OF BANK NOTES CUTS PRINTING BILL Uncle Sam expects to save about $1,- 600,000 a year by using the smaller-size currency which was placed in circulation recently. The new bills will result in a saving of 550 tons of paper, worth $500,000, and 500 tons of ink, valued at $100,000, while reduced labor will save $1,000,000. Plates used for long-run en- graving now are made by the electrolytic process, which multiplies the number of plates that can be made from the original engraving, thus lengthening the life of an original plate. The change in size of the money meant only slight changes in the mechanical equipment of the bureau of engraving and printing. Machines for trimming sheets to size were rebuilt, and those used for the final operation of num- bering, sealing and separating were re- placed with typographic presses which take sheets of twelve subjects each, print two serial numbers and a seal on each note, cut the sheet in half, separate each half into six notes, collate the notes in numerical sequence, and deliver them in units of 150 each. Twelve notes now are cut from one sheet of paper where only eight were obtained before. A new-type press produces 336,000 notes a day. SELF-LOADING TRUCK HANDLES TEN TONS OF STEEL Ten tons of sheet steel are handled at a time by a self-loading truck with tilting platform on which the bundle of sheets is pulled by a looped cable attached to a motor-driven drum at the front of the truck which is operated by storage bat- teries. At the lower end, the platform tapers down to the thickness of steel plate, this end resting on the floor when the platform is tilted down for loading. When the bundle is in position, it rests on the center of gravity so the platform can be tilted up by hand, being held in position by a locking mechanism. Rollers on the upper part of the platform facilitate un- loading. The truck has ten wheels and is driven by two large wheels through spur gears. It has a short turning radius to per- mit operation into and out of box cars. Self-Loading Truck with Tilting Platform Which Han- dies Ten Tons of Steel at a Time AS

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POPULAR MECHANICS 637 “WALL OF DEATH” LATEST MOTORCYCLE THRILLER "7 Motorcycle Riders Assume Almost Horizontal Positions as They Speed around the Vertical Sides of This London Bowl, Which Has Come to Be Known as the “Wall of Death” Daring motorcycle riders who use the almost vertical sides of a large bowl as a racing track are affording thrills to Lon- don’s seekers after diversion. The riders are in almost horizontal position as they speed around the perpendicular track, which has come to be known as the “wall of death,” because of the danger involved. ZOO PENGUINS LIVE IN ICE BOX When eight penguins, accustomed to the antarctic regions, arrived recently at the Philadelphia zoo, officials faced the problem of keeping them cool, because the expensive birds were unable to with- stand the temperate climate. The zoolog- ical society met the issue by building an ice box for them. The floor of the shelter is a shallow concrete basin on which was erected a house made of heavy planks with a roof of heat-resisting tar paper. A door in the front and a win- dow at the rear for the ice completed the abode. Each day 500 pounds of ice, cut in layers, is spread on the floor and the birds sleep standing up on the ice-cov- ered concrete. Native shrubs and greens surround the house and outside is a lake where the birds disport themselves. CIGAR EXTINGUISHER COMBINED WITH ASH RECEIVER For the careful smoker, who avoids fire hazards, a combined cigar extinguisher and ash receiver is on the market. The extinguisher unit is operated by pressure of the finger which brings water into a recess at the top, the heat from cigar, cigaret or pipe drawing the water to the glowing ash. After extinguishing the fire, the water flows back into the container, which will not leak even if held upside down. The ash receiver is carried on a tray as a sepa- rate unit. The appliance ts made for at- tachment to automobiles and can also be fastened to the clothing of hikers.

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ye. Serves as Extra Fingers; Does Scores of Tasks Such as Reocking inside Bottles, Taking Things from Fire and Dusting Difficult Places With These Rubber Protectors, the Wearer Can Place Arms in Water Almost Up to El- bows without Wetting the Sleeves; They Are Decorated to Match Apron and Have Tight-Fitting Wristbands = a oe %. ‘a * Polishing Pad, Used like a Mitten, Has a Washable Cover Easily ‘Removed or Readjusted ; Hand Is Afforded Strong Grip Above Is an Easily Attached Window Lock That Firmly Secures Both Sashes and May Be Employed to Hold Doors = Open or to Lock Them; at Left, a Built-In Dust Bin That Takes the Sweepings for Later Removal or Deposits Them through a Chute into the Base- ment; It Is Furnished in Nickel or Colors to Match the Woodwork

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Double-Sponge Scrub Brush Saves Handling Dirty Water; the One on Base Does the Dry- ing and the Bulky One Absorbs the Water; It Is Cleaned by Holding It under Faucet Chemically Treated Rubber Sponge Keeps the Hat Clean and Is Also Useful in Remov- ing Spots from Lamp Shades and Fabrics; It Is Washed with Soap and Water = Here Is an Improved Casement Window with a Screen That Fits Flat against the Frame and Is Easily and Quickly Removed from the Inside; Window Is Readily Opened by Handle That Extends through the Screen Sanitary and Well-Ventilated Cooling Cabinet for Food Fits on Window Ledge to Save Space; Shutter Vents Close When Door Is Opened. to Keep Cold Out of Room

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640 POPULAR Modeling Tiny Heads in Colored Clay to Demonstrate Character Make-Up in Movie Studios MOVIE MAKE-UP IS TRIED OUT ON MODELED FACES Tiny heads modeled in colored clay are ‘used in the moving-picture studios to work out and demonstrate character make-up. Three or four-inch heads are made of Indian chiefs, prize fighters or Arabian sheiks and submitted to the di- rector who suggests any changes desired, after which every detail of make-up is worked out on the models. The actor then is made up to resemble the clay image and a screen test is made. The method gives a view of the head from all angles, enabling visualization of the actor in make-up, thus saving time and money. - GAS IS STUBBORN PRISONER ABOARD AIRSHIPS Roast beef is a close relative of the largest airships in use today, the “Los Angeles,” “Graf Zeppelin” and the new 3ritish air liners. Hydrogen or helium gas that provides lifting power for the air giants is contained, not in a single compartment within the rigid hull, but in a series of gas cells, These drum-shaped MECHANICS containers have nothing to do but retain the precious lifting gas. The job of ward- ing off rain, hail, sunlight and wind is left to the outer covering of aluminum-coated balloon cloth. Lives of airship builders have been made less tranquil by the fact that hydrogen and helium gases are more difficult to keep in captivity than the most ferocious circus animals. No matter what kind of material is used for the gas cells, there always is a constant oozing of the contents into the outer air. One of the most satisfactory materials for keeping the gas captive is goldbeater’s skin. This extremely tough substance forms the outer covering of a portion of a steer’s intestinal system. Hence the close rela- tion of roast beef and airships. Gold- beater’s skin, as the name implies, is used in beating gold—hammering it into sheets so thin that light will pass through. With its toughness is combined the ability to retain gas better than almost any other material. As it comes from the packing company, a barrel of salted skins contains 2,500 pieces. Gas cells are manufactured from the skins cemented to a cloth base. One method makes use of glue to hold the pieces in place. An improved system con- sists of laying the skins on rubberized bal- loon cloth coated with rubber cement, the pieces overlapping about one and a half inches. An idea of the number of steers represented in a dirigible is given by an order for the ill-fated “Sher.andoah,” to- taling 1,500,000 skins. HUB PLATES FOR AUTOMOBILE ADD TO ITS BEAUTY Hub plates for Ford cars now are on the market as an accessory to add to the car’s appearance. The plates are chro- mium-plated, fit- ting around the original hub cap which does not need to be re- moved to install them: Once in place, they do not jar loose or interfere with removal of the wheel. Ab ut qu

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POPULAR MECHANICS 641 MOVIE WIND MACHINE SNUFFS OUT OIL FIRES “— Pl WITT Above, Wind Machine Extinguishing Oil-Well Fire, and, at Right, Aerial View of the Blaze Hollywood’s movie industry contrib- uted the latest development for the con- quering of burning producing wells, when a wind machine, such as used in moving pictures to create windstorm effects, ex- tinguished a burning gasser in the Santa Fe Springs field. Two wells broke out as uncontrollable producers and a day later developed into that terror of town-lot fields—burning gushers. With blazing oil spouting 200 feet into the air, neighboring wells, tanks, sump holes, warehouses and offices soon fell a prey to the flames, and before the spreading fire was even partly controlled, a damage of approximately $4,000,000 had been caused. The original two wells burned as flaming torches for more than a week. The usual methods employed to “kill” the flames failed and, as a last desperate method, a committee of

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642 POPULAR operators decided to borrow a wind ma- chine from one of the motion-picture com- panies, in an effort to enable their men to approach closer to the well to make necessary observations. When the ma- chine arrived at the field, a test revealed its wind-producing strength to be so pow- erful that it was decided to attempt to blow out the well with it as a man blows out a candle with his breath. A crew..of eighty workers was selected to make the experiment. They were garbed in as- bestos coats and trousers, and carried shields before them as protection against the heat. Then the wind machine was turned on, full blast, toward the burning geyser. To the joy of the oil operators, the machine blew the column of fire to one side sufficiently to enable the crew to “hook” a flow line to one pipe of the well. With the flow of the well dimin- ished by half, the machine was next di- rected at the twelve-inch casing from which the fire and oil roared forth. At the third attempt, when the machine was turned on full force, the blaze suddenly died out. The wind machine is a truck- like affair, carried on rubber-tired wheels. A housing contains a powerful electric motor which operates a series of four air- plane propellers which produce the wind. MECHANICS WASTE FROM AUTOS FILTERED FOR OIL BURNER Oil burners have been designed to use waste oil from the drainage of cars. The equipment includes a filter to strain dirt and water from the waste, and the burners are used in both heating and cooking stoves. The heater is intended particu- larly for economical use in garages and workshops where such fuel is plentiful, but heavy oils, such as those remaining after the extraction of gasoline or kero- sene, also may be used in homes. A settle filter is operated on the principle that the oil rises to the top while water and sediment sink, the oil being drawn off through gauze. A small air pump is used to clean the gauze at intervals. GLIDER FITTED WITH PONTOONS TO LAND ON WATER German gliders long have flown suc- cessfully over land, but have been at a dis- advantage when air currents forced them over open water and then made a land- ing necessary. Now, one of the wind craft has been fitted with pontoons resem- bling those attached to amphibian planes, making a water landing easy. Here Is a German Glider Fitted with Pontoons, Like an Amphibian Plane, So It Can Make a Successful Water Landing When Air Currents Carry the Craft to Sea

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Sl ed Making Crown Jewels jporthe OVI CS i THE last five years the motion pictures have used more than half a billion dollars’ worth of crown jewels, famous gem sets and historic or- naments worn by their stars, stolen by their crooks, and missed in their mystery plays. This year approximately $200,000,000 worth will appear on the screen. That is to say, they would be worth that if they were real. Yet they are such per fect imitations that, un- der the glowing lights of the studios, worn by a daughter of Pharaoh, a queen of Babylon, a Czarina, an empress of India, or a modern social leader, all show, in the film, exactly the design, size, color and appear- ance of the jewels of the women they represent at the period presented in the play. Up to five years ago, the motion pictures used whatever jewelry the costumer could supply. Then the public and the critics arose, demanding accuracy in gems as well as in costumes and customs. They never hoped to see the Kohinoor, the Or- loff diamonds, Persia’s royal sapphires, Hyderabad’s pigeon-blood rubies, Naisha- pur’s emeralds, or the priceless pearls of the crown of Holland, but they did want to see them reproduced accurately when- ever called for in the film scenes. Simultaneously with this demand, there appeared in Hollywood a slender Dane, who had walked through all the capitals Petersen- Fagerstam with Completed Replicas of Crown Jewels of the Rus- sian Czars; He ing the Czarina’s and, at the Extreme Right, Is a Bracelet of Sapphires from Persian Crown Is Hold- Tiara, ewels oly Lov ow hacet f *» of-Europe, studying the designing of jew- elry, viewing the world’s famous gems, and learning to make what we now know as “period jewelry.” His name is Willy Petersen-Fagerstam, and he is descended from generations of jewelers in the Dan- ish capital. From white and colored glass he fashions gems of all kinds; from cop- per, pewter, German silver and brass, he works the platinum, gold and _ silver mountings, and from glass, blown thin as a sheet of goldleaf, he forms pearls, cov- ered with fishscale composition of all the shades of the sea treasures of Ceylon and 643

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644 POPULAR MECHANICS the South Seas. In the last year these replicas of famous stones and their set- tings cost the motion-picture companies more than $20,000. This year, the total invested «will be nearly twice as much. What time Petersen is not making gems and jewel settings, he is studying de- signs’ and imitations preserved in_ li- braries and museums. In this work, he cannot originate; he must imitate. From the’ necklace of sabertooth-tiger teeth for the Stone-Age ‘medicine man down to the Hope diamond or other famous. stones and their settings of today, Petersen makes them all exact replicas of the individual productions of ancient and modern jewelers, and gold and silversmiths. He uses glass, and glass only, to pro- duce replicas of the famous, and com- mon, jewels of the world. Virtually all of it;-cast and ground with the proper “faceting,’ comes from Czechoslovakia, Prague being the largest source. These countries produce a cast glass, uniform in coloring, with a very high factor of. re- flection, such as can be had nowfiere else in the world. This cast glass is used for diamonds, except when wanted in composition stone is ever used. These “casts” are made in duplication of the originals, from exact measurements and color photographs. They mimic not only the size, shape and color of the fa- mous gems of the world, but reproduce every flaw possessed by the originals— and no great gem exists without faults of some kind. Once cast, the imitation gems are ground by hand. There is no wholesale production of these stones. Al- most as much attention is given to each as the cutters of Amsterdam give to the genuine stones. Pearls for the motion pictures—from the great pear-shaped pink pendants in the crown jewels of Holland, England and some of the Indian states, to the smaller but more uniform treasures of modern necklaces—are blown in the thinnest of glass by the workers of central Europe. Every famous and valuable pearl in the world has been so imitated as to size, shape and color, in blown glass. When the “pearl” has cooled, it is covered with several coats of a varnish made from fishscales, and colored to the exact tint of the original. Laid side by side, except for weight, it would be extremely difficult Replica of Pearl and Diamond Necklace of Italian Court Jewels large quantities, as for the covering of slip- pers, sandals or gowns, Copy of Valuable Indian Neck- lace of Sapphires and Dia- monds to distinguish the orig- inal from the imitation. At first Petersen at- when rhinestones are called in; for emeralds, rubies, sapphires, -topazes, amethysts, lapis-lazuli, zircons, Alexandrites, indeed ‘solid” stone. No paste or other ‘ for every Replica Tiara from Austrian Jewels Above and Pearl Necklace from Holland tempted to use syn- thetic and culture pearls, but these did not photograph so well, cost more, and, once broken, could not be replaced immediately. Moreover, th Siz In pi th be th on ur Pe tic th ga ni to wl ne tai ar Re pa th th er rex

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POPULAR MECHANICS 645 Photos Courtesy Paramount Pictures Making a Jeweled Slipper for Period Costume of the Time of Louis XIV; on the Bench Are Exact Imitations of Royal Russian and Austrian Headdresses they could not be obtained in the shapes, sizes and colors to duplicate the originals. In these pearls, liquid glass of a shade of pink, gray; cream, ivory or black, exactly the same as that of the particular gem to be imitated, is used in the blowing. Then the fishscale composition is tinted to the same degree and applied. The result, to one who is not an expert on these treas- ures of the sea, is the same as the original. In plain, unlocked wooden drawers Petersen keeps thousands of these imita- tion jewels. There one sees the Orloff diamonds, the Kohinoor of Shah Jehan, the great sapphires of Persia’s royal re- galia, the empress of India “set” of dia- monds, replicas of the world’s most no- torious necklace, that of -the diamonds which involved Louis XVI, Marie Antoi- nette, Cardinal Rohan and other digni- taries of France in a historic fraud. There are reproductions of the Great Mogul, the Regent, the Nizam of Hyderabad, the particular yellow Orloff, said to have been the looted eye of an East Indian idol; the Great Table of Persia, once the prop- erty of Genghis Kahn, one of the few rectangular diamonds, the Duke of West- minster’s Nassak; the famous bearer of bad luck, the blue-tinted forty-five-carat Hope diamond, probably part of a mys- teriously missing 112-carat colored stone, brought to Europe by Tavernier and later stolen from the French crown jewels. The large stones, like the Cullinan, Tif- fany, De Beers and others, though never worn, must be on hand for museum scenes, jewel-robbery stories, and royal scenes in which such huge gems might be on display. Similarly, Petersen keeps in his workshop a collection of artificially made matrix containing excellent imita- tions of the various precious stones, for use in pictures whose scenes are laid in the remote parts of Africa, India, or other gem-producing countries. Petersen’s tools are of the simplest, and any maker of real crown jewels would laugh at his littke workbench and _ its equipment. Several pliers, with round, square and flat noses, and four or five hammers of varying weights and faces, will make any kind of jewelry of any period, when they are helped out by a small vise with corduroy pads on the jaws and some colorless cement.

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Tiss =e 646 POPULAR Above, om Hose Reel Which Fits in Coal- Chute Door; Salon, the Door When Closed DISAPPEARING HOSE REEL FITS ON COAL-CHUTE DOOR Caring for the garden hose has been:sim- plified by combining a hose reel and coal- chute door, the reel being mounted on the door, which opens at the top, allowing it to rest on the ground. The reel is made of heavy steel and operates on ball bearings, while the frame is formed by the flange of the coal chute. When the winding reel is removed the chute is unobstructed. The end of the hose connecting with the faucet is fastened to a projecting pin so it may be hooked up without unwinding the length of hose, or a connection from in- side the basement may be made. The hose also may be used in the basement for washing the floor or for wetting down the coal pile. COTTON SEED “FUZZ” VALUABLE Cotton manufacturers are finding a val- uable by-product in the heretofore useless “fuzz” that remains on the cotton seed after the fiber has been removed. Chem- ists have found that this fuzz can be made into a fabric resembling silk and now the seed is shaved very close to ob- MECHANICS tain the product, which is used for mak- ing automobile tops, as a leather substi- tute, and for combs, brushes, mirrors, films, sausage casings, paper and collodion. DETACHABLE AIRPLANE CABIN FOR SAFETY AND PRIVACY Models of a detachable cabin for air- planes have beefi made by an inventor to add to the safety, privacy and comfort of future air travel. The detachable com- partment has a parachute on top so that in case of danger, the pilot may release the compartment containing his pas- sengers, the cabin dropping through the fuselage and floating to earth beneath the parachute. The cabins have wheels like auto trailers, and a person traveling much by air might own such a cabin, keeping it in his garage. When going on a trip the cabin would be hauled to the airport as a trailer, there attached to the airplane, and, if necessary, detached and fastened to another airplane at a transfer point, then hauled to the passenger’s hotel door at his destination. The cabins also might be used in handling mail and freight with- out packing and unpacking. Detachable Airplane Cabin Which Floats to Earth by a Parachute When Loosed from Plane

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POPULAR MECHANICS 647 MODEL LOCOMOTIVE HAULS SIXTEEN PERSONS A Model Locomotive, Built on a Scale of Three-Fourths of an Inch to a Foot, Pulls Sixteen Persons on a Real Railroad Track, and Has Made a Continuous Run of Nine Hours Built on a scale of three-fourths of an inch to one foot, a one-sixteenth-size model of an Atlantic-type locomotive has been made by a mechanic as a toy for his children. The locomotive, complete in every detail and operating on a real rail- road track, has pulled sixteen persons in addition to the engineer and has made a continuous run of nine hours. It won a medal, a cup and a diploma of merit at a British model-engineering exhibition. Leisure time of two years was spent by the maker in its construction. WEATHER BUREAU ON WHEELS BATTLES FOREST FIRES California forest fires are being fought by a portable weather bureau mounted on an automobile truck. The weather bureau on wheels is equipped with a radio-receiv- ing set, apparatus for establishing three emergency weather stations, and complete charting equipment, a radio operator and weather observer composing the crew. The outfit is rushed to the scene of a forest fire, where the radio picks up weather conditions and forecasts, adding to this local observations including wind conditions. Charting this information, the observer makes a forecast for the fire area which is rushed to the fire fighters, who are thus enabled to concentrate their efforts at strategic points of the fire zone. BLIND TAUGHT MATHEMATICS BY TOUCH SYSTEM In a further effort to help overcome the handicap suffered by the blind, the Ameri- can Braille Press has evolved a sys- tem of teaching sightless persons simple mathemat- ics by the touch system. Hereto- fore efforts had been centered mainly on im- proved methods of dot printing, read with the finger tips. The mathematics system substitutes raised figures and symbols for the dots.

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ee ane A AEN Ts completely shielded a.c. screen- grid receiver employs a_ band-pass filter in a highly efficient three-tube cir- cuit. Designed and built in Popular Me- chanics radio laboratory and thoroughly tested in a locality where selectivity is an absolute necessity, this receiver easily separated strong locals. The volume and tone are remarkably good; in fact, the vol- ume is equal to that of a six-tube receiver employing standard type 201-A_ tubes. This is, of course, due to the greater amplification and careful handling of the a.c. screen-grid tube.

Selectivity is possible only through the use of the band-pass filter and careful shielding, and is practically that obtained by the use of three r.f. stages employing the usual tuned r.f. circuit. The all-metal cabinet for the set and power supply is the one described in de- tail in the September issue of Popular Me- chanics, and the only alteration necessary is to provide a slightly deeper compart- ment to the right of the dial for the band- pass filter. The layout diagram shows the shielding and location of all the instru- ments with the exception of the three

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7 biasing resistors and two by-pass condensers, lo- cated for convenience be- low the metal subpanel. These instruments are shown in dotted lines in the wiring diagram on page 650. The resistors and by-pass condensers could just as well be placed above the subpanel, which would avoid the neces- sity of raising the %-in. subpanel to % in. to accommodate them. Therefore, the front-panel template is laid out for a %- in. subpanel; a bakelite panel, %e by 7 by 21 in., will fit nicely in a standard 21-in. wood cabinet, which must be 12 in. deep, to house the entire receiver. If a %-in. subpanel is used, either cut % in. off the partitions at the top or use a bakelite front panel, 7% in. wide instead of 7 in., and leave the partitions as they are. It will, of course, be necessary also to raise the holes in the panel % in. higher than shown on the template. Mount the instruments as shown in the layout diagram, and use soldering lugs for all possible connections. Keep the coils at least % in. from the metal partitions. The holes for the antenna and ground posts are drilled large enough to drop the two Eby binding posts through the sub- panel, where they are mounted on the bakelite strip and held to the underside of the subpanel with short machine screws. The large fixed-resistance unit is mounted upright on a small piece of bakelite at the rear, by means of a rod threaded at each end for 6-32 nuts. The rotors of the variable condensers are all grounded to the metal subpanel through the condenser frames. The holes in the center partitions for the shaft should be drilled no larger than neces- sary to clear. The balancing condensers, E-C-35, are mounted before the condensers are in position and should be accessible for adjustment. The original metal-cabinet front panel is drilled by using the bakelite panel as a template. An opening is cut in the metal panel for the rear of the escutcheon plate and lamp bracket, and for the antenna switch, a.c. line switch and potentiometer. The indicator-drum bracket is mounted directly on the metal panel and held in po- sition with through both panels. Bolt the front panels together tempo- rarily and mount the instruments. two screws Line 649

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) . \ 650 POPULAR MECHANICS screws on the subpanel in order to line up the condensers correctly, When in position, loosen all setscrews and remove the condenser shafts and front panels. It is best to wire as much of the set as pos- sible with the end partitions and front panels off. Use nothing but well-insulated standard hookup wire designed for a.c. receivers; the leads from the power compact should have %e-in. rubber insulation, especially where they run through the metal tubing from the compact to the filter-condenser block and to the resistance unit at the rear. The same kind of wire is used for the lead to the switch on the front panel, and a smaller a.c. twisted-type for the 2% — = = CONNECTED To » 8 ds ate METAL BASE OR SHIELD © Oo + FIXED RESISTANCE | 2*M21L 135 Vv. : a CENTER TAPPED TWPE CIOS 2. 4MPFD. TYPE R-280 BLOCK ® 1200035 _) ha — “oo ANTENNA 110-V. LINE __ ~ SWITCH SWITCH 100,000- OHM POTENTIOMETER ee ee ee a . ev.) SV. \ ee ee Ee ae Se $e - a = SS OOOO OOOO OOO Scanieastlidamaeallinemeietemeamanes Upper Left, Underside View of the Completed Receiver Showing the Location of the Biasing Resistors and By-Pass Condensers; Below, Simplified Wiring Diagram Showing the Various Instruments in Approximately the Same Positions They Occupy in the Assembled Set up the variable condensers, shafts and and 5-volt filament leads. The metal base dial through the indicator drum. To in- and shielded compartments form a com- sert the shafts, remove the two end parti- mon ground, eliminating long leads. Note tions. Mount the flexible coupling as that the control-grid lead and plate lead shown and tighten the setscrews in the from the screen-grid tube are shielded by coupling, condensers and indicator drum. means of insulated wire covered with a The knob on the indicator drum should woven-metal sheath. These shields are now turn all the condénsers freely. It grounded where they come in contact may be necessary to loosen and slightly with the metal cabinet. Care should be shift some of the condenser-mounting taken that the metal sheath does not touch

Page 129

POPULAR MECHANICS 651 the terminals at either end. The filament metal. The 2-mfd. by-pass condenser transformer hasa24-volt secondary wind- across this resistor is mounted on the ing for the screen-grid tube and detector. partition above the af. transformer. The The variable center- tapped resistor .0l-mfd. fixed condenser and 750-ohm re- across the 2%4-volt secondary is mounted _ sistor, indicated with dotted lines under with stiff busbar wire, above the trans- the subpanel and marked optional, is former, in an easily accessible position for really necessary for the correct operation adjustment to prevent hum. The center ofthe set. The leads 3, 4 and 5, from the lug is connected to a short lead and antenna coil, run through holes drilled in

= #27 6 #25 #2o #2 6 -2* CENTER LINE OF INDICATOR SCALE AND A= NO.30 DRILL ‘ple ASF ESCUTCHEON PLATE B= NO.%6 " A CENTER LINE OF CONDENSER c.g ” aw 7” SHAFT AND INDICATOR DRUM 7 tied . "7 ft. -- « - ~41 4 6 et PT Lae ee: ee mE . ee o#2t #27 _ rere — 2 —_———————$—$—$— $$

grounded on the metal partition. The other center-tapped resistor across the 5- volt filament line, near the audio tube, is mounted on a small bakelite panel which also carries the speaker posts. The center post of this resistor is taken to the 1,500- ohm resistor under the subpanel, and the other end of the 1,500-ohm resistor is screwed directly to the metal subpanel. The opposite end must not touch the

.00035-MFD. 7 GANGED CONDENSERS .. N77 ANT. _ SHIELD, / SHIELD _ Baiat ——— / c 0002s ! 2-A ' ! rt L.S. F | 60 OHMS ! capt res OPTIONAL 1 150 OHMS 2 —— METAL BASE ~-]- 4 ] j ) w a— | ] D.L. + ae ~ 2 €e omey ip R-280 iCOMPACT fF INSIDE ‘DOTTED ® | +1959 $3000 ome] [46FO. amen —e rea. | os. B | [rea eal => a - | ae = 2 To7 a) +¢ z Janse § oven >” IMFO. - » a. 'F ' S-VOLT LINE ¥ REAR TAPS JZ word : TWISTED y \ ir ;- Sw. B= CONDENSERS SECONDARY 3) IN BLOCK wor use ‘: g "so PRI. 60- 2.5-VOLT LINE, TWISTED <” Ta RST ‘UNE . r

2.5-VOLT ~~ T-308) SECONDARY FIL. TRANS. Upper Left, Panel Template for One-Half-Inch Subpanel; Right, Placing Shield over Screen-Grid Tube; Below, Schematic Diagram of Three-Tube A.C. Screen-Grid Receiver and Power Supply

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A AR RA Pa a TR TA 652 POPULAR MECHANICS the end partition and go to the taps on the antenna switch. With the end partitions removed and the front panels in position, insert the Above, the Completed A.C. Screen-Grid Receiver Ready for Testing shafts in the variable condensers, and re- place the coupling. See that the rotors of the three condensers are “all in,’ and then tighten the two setscrews on the shaft in each rotor unit. The rotors are now all in one unit on the shaft and turn- ing freely through the indicator drum. Lift the rotors to the “all-out” position, turn the knob on the indicator drum to the left as far as it will go and then tighten the setscrews which hold it to the shaft. Now turn the dial on the shaft until zero shows at front and tighten the setscrew which holds it to the shaft. The knob of the indicator drum will now con- trol all three condensers and drum dial. Complete the wiring to the front panel, replace the end partitions, and the set is ready for testing Go over the wiring carefully and check each connection. See that every lead that goes through a hole in the metal subpanel or partition, with the exception of the shielded leads previously men- tioned, is carefully insulated. The holes should be large enough to pass all insu- lated leads without touching, if possible. Insert the tubes, connect the antenna, ground and speaker, and plug the supply lead to the transformers into a con- venient 110-volt, 60-cycle lighting socket. A single wire, 100 ft. long, will provide a very efficient antenna. Turn on the a.c. switch on the front panel and check the various B-voltages on the upright resist- ance unit with a B-eliminator voltmeter. If the voltages are approximately as specified and there is no evidence of a short circuit, slowly turn the knob of the indicator drum until a station is tuned in about the middle of the dial. Now set the antenna switch at the point of loudest reception. Adjust the balancing con- denser across the antenna-tuning con- denser for the loudest and clearest signal with the volume control at the right full on. This is done with a wooden stick shaped like a screwdriver. Never use a metal tool in the set while the current is on. After adjusting the first balancing condenser, move to the next and balance it also for best possible signal, then serve the last one in the same manner. Once balanced, there is no further need to touch these condensers. A slight adjustment of the potentiometer volume control and the antenna switch may be needed in tun- ing in some stations to best advantage. The compact, self-contained construc- tion of this a.c. receiver makes it avail- able for use in a variety of console in- stallations as well as the two suggested methods shown in the photos at the head of this article. However, when the metal chassis is placed in a wooden cabinet, ven- tilating holes should be drilled in the rear of the cabinet. Do not close the back of the rear metal compartments. The cost of the parts, including the tubes and metal cabinet, at net list prices will be approximately $65.00. If there are any points that do not seem clear or if addi- tional information is desired, address your letters to Popular Mechanics radio de- partment, 200 E. Ontario St., Chicago. Blueprint No. 144, describing in greater detail the construction of this unusual three-tube a.c. receiver, is now available. It may be obtained for 25 cents, together with a complete list of the parts used. The list of parts will be mailed free to readers who do not desire the blueprint. ins ie el di a ae

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Improving the Audio Amplifier Many experimenters have failed to find any improvement when substituting the new large-type a.f. transformers for the small types in common use. This, how- ever, is not the fault of the new trans- formers, as they require the use of by-pass condensers and resistors in the circuit to take full advantage of their high-imped- ance winding and large core. One of the most common difficulties is feedback from the power tube into the grid circuit of the first audio stage. This may be pre- vented by connecting a resistor varying from 8,000 to 60,000 ohms between the F terminal of the transformer and the C-negative line. For the first audio stage 60,000 ohms is best, and in the power stage employing either the 112-A or 171-A tubes, 25,000 ohms are used. For the type- 210 tube, use 15,000 ohms and for the type- 245 tube, 10,000 ohms. The type-250 tube works very satisfactorily with 7,500 ohms. A by-pass condenser of 1-mfd. capacity should then be connected from F on the transformer to one side of the filament in all cases —D. A. Brown, Marion, Ohio. Station Selector Replaces Tuning Knob A station finder that takes the guess- work out of tuning does not require any changes in the tuning of the radio set nor does it interfere in any way with its reg- ular operation. It is fastened to the front of the set by means of a setscrew on the shaft of the drum dial, or regular tuning Supporting arms fit on the rheostat dial. Tuning Selector Installed on a Standard Panel Assem- bly; and Close-Up Showing Call Letters or other control shafts behind the knobs. A celluloid chart for writing in the call letters of from 16 to 20 stations is located directly above the control knob. POPULAR MECHANICS Rectifying Unit Being Placed in the Double Mount; and Complete Rectifier Ready for Installation New Rectifier for Dynamic Speakers Operating direct from the a.c. line, a new rectifier for dynamic speakers elimi- nates the usual power transformer, reduc- ing the cost of assembly. Two units are required for each installation and are supplied either separately or mounted ready to install. The units may be re- placed when necessary as easily as a tube is changed in a socket. Salvaging Charger Bulbs The writer has found that quite a few charger bulbs are discarded because they are thought to be burned out when such is not the case. Frequently, the base of the tube makes an imperfect contact in the socket and this causes arcking, with the result that in a short while the bulb ceases to function and goes out. The remedy is to scrape the inside of the socket and base of the bulb and sand the prongs bright to insure a good contact, and the bulb will be restored to useful service.— Glenn F. Stillwell, Collinsville, Il. Cost of Operating A.C. Sets The average a.c. receiver operates at a current cost of but one cent for every three hours of actual use. This is much less than the cost of operating many of the electrical household appliances in cagmmon use. The manufacturers of some electric irons estimate the cost of the cur- rent consumed to be 3% cents per hour.

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| \ | Disk Coils for the Experimenter By EDWARD A. McMURTRY PART II | B iecws coils of the neutralized-field type, equivalent to the binocular or dough- START SEC.WINDING nut varieties, are very efficient. The con- struction, as shasn in Figs. 5, 6 and 7, is quite clear, and the method of winding is very simple. Fig. 5 of the first part of this article, which appeared in the Sep- tember issue, gives the disk layout for coils of this type. Three disks, 2 in. in diameter, and a fourth piece of cardboard stock, cut on the dotted lines to form the main or center card, are required. The disks are then bolted to the main card with \%e¢-in. spacer washers, to pro- vide the winding spaces as in Fig.6. Note that there are two winding spaces on one side of the main card and one on the other. The two lower spaces are to be occupied by the divided secondary wind- ing, and the separate primary coil is wound 654 in the upper space with the large washer. The primary coil contains 10 ft. of wire, with the start and finish ends brought out above. From 20 to 25 ft. of wire is wound on each secondary coil, the two coils be- ing connected in series. The coil at the left, Fig. 7, is wound clockwise and the one at the right counterclockwise. These coils are easily mounted on a strip of bake- lite and a small metal bracket may be employed to hold them upright on the baseboard in any position required for circuit and space demands. The wire used should not be of the enameled variety, silk or cotton- covered wire being best for disk coils. If No. 26 wire is used, the coil disks will be somewhat larger than would be re- quired for No. 28 or No. 30 wire. If wire as small as No. 30 is used, cut the wire the proper length and solder special flexi- ble stranded lead wires to each end before wind- ing. Start the winding with the soldered joint just inside the coil form, so that the lead wire only shows on the outside and finish in the same manner. By employing this method the fine wire is protected, as the flexible leads take up the strain and wear. Coils of the D-type may be closely fol- lowed in the modified disk form as shown in Figs. 8, 9 and 10, and very interesting adaptations for variometer and_ loose- coupler devices are available with the coils rotating in a flat plane. The winding form is shown in Fig. 8 and consists of a disk, 3 in. in diameter, cut in two to provide the sides for the winding form. A smaller piece of cardboard is cut for the winding-core piece, as indicated by the dotted lines. It should be just large enough to provide a %-in. winding space all around. Glue the core piece in posi-

Page 133

tion and bolt all three pieces together at the center. This is one-half of the com- plete unit which is composed of two such coils wound in opposite directions and connected in series. The single-coil units are then mounted flat on a slightly larger cardboard disk. When two such complete units are put together, the result is a loose coupler or variometer, depending on the manner in which they are connected. Fig. 10 shows the connections for a loose coupler; if a variometer is desired, the coils should be connected in series, and there will be but two leads instead of four. One set of coils is stationary and the other set forms the rotor. Mount the units facing each other on bakelite strips, one unit stationary and the other so that it may be rotated. The correct length of wire to be used on a disk-coil unit, the secondary of which is to be tuned with a variable con- denser of a given number of plates, such as the unit shown in Fig. 4, in September issue, is best found in the following man- ner: Wind about 50 ft. of No. 30 wire on the secondary and about 8 ft. on the primary; place the coil in the set and tune in a station operating on the longest available broadcast wave. The station should come in well on the high end of the dial; if this is not the case and the station comes in about the center of the dial, take turns off the secondary and make tests until the station comes in at the high-wavelength end of the dial. Electrolytic Rectifier Replaces Tube This simple rectifier differs from the or- dinary electrolytic cell in that it employs two aluminum electrodes instead of one. It will replace any rectifying tube or other rectifying element used in conjunction with a mid-tapped transformer secondary. The glass container may be a %-pt. fruit or salad jar and should be examined care- fully to make sure that it is free from cracks. A hole, about 134 in. in diameter, is cut in the metal cap, leaving a narrow retainer rim as shown. A hard-rubber or bakelite disk is then cut to fit snugly in- side the metal cap, where it is held by the retaining rim. Four holes are drilled in the disk, three for the electrode binding POPULAR MECHANICS 655 posts and one for a vent. Ordinary wire solder may be used for the lead electrode; the aluminum electrodes are %4 in. wide and 3% in. long, holes for the binding posts being drilled in one end and these ends bent over % in., to form electrodes 3% in. long; the lead electrode is the same length. The electrolyte may be the familiar borax solution made by dissolv- ing as much borax as % pt. of distilled . water will take up, or a solution of 1 oz. monobasic’ammonium phosphate in ™% pt. distilled water. The aluminum electrodes must be carefully sanded and absolutely free from grease or dirt before they are placed in the solution. The connections Cacuminum ASSEMBLED RECTIFIER TO A.C. 110 VOLTS ALUMINUM 7 LEAD DIAGRAM OF CONNECTIONS Construction Details, and Diagram Show- ing Connections to Transformer are plainly shown and must be closely followed. The advantage this type of rectifier has over the tube or cartridge is its low cost; the lead electrode will last indefinitely and the aluminum electrodes are easily replaced when exhausted.—W. G. Fisher, New Haven, Conn. @A small wire brush is useful for the purpose of cleaning the tip of a soldering iron before it is tinned.

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656 POPULAR MECHANICS A De-Luxe Receiver of Unit Design Probably one of the most elaborate as- semblies for home use in the way of a radio receiver is shown in the photo. Seven aluminum cabinet units contain the various components of the set proper. These units, together with a power pack, power amplifier, dynamic speaker and an electric-phonograph turntable, have re- cently been installed in this specially de- signed console. The circuit employs four (— ‘ Top, Phonograph Turntable Located in Lower Com- partment; Center, Complete Installation; Left, Power Pack and Amplifier stages of tuned screen-grid amplification, detector, two stages of resistance-coupled audio amplification and type-250 power tubes in push-pull. The four screen-grid tubes, the 200-A detector and the two type-240 resistance-coupled tubes are op- erated on rectified a.c. current, supplied by a 3-amp. 6-volt power plant. The B and C-supply is obtained by means of two type-281 tubes arranged for full-wave rec- tification. Plug-in coils for the tuning units cover a wavelength range from 200 to 3,000 meters, including the higher [ for Sta ze ren ma res Fig tub the lea’ stri to? as bia do1 neg dey res pas em — _—_ us

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—a— en Oe waves employed by European stations as well as those of American and Canadian broadcasting stations. The receiver is not difficult to tune, although each tuning unit is provided with its drum control, and the various units may be coupled together so as to be operated as a single group, thus simplifying tuning. The inclusion of the phonograph feature makes it possible to reproduce records taking full advantage of the audio system. Simple Grid and Filament Control by Fixed Resistors Inexpensive fixed resistors may be used for grid and filament controls with the standard vacuum tubes in common use. If a fairly steady source of filament cur- rent is available, the filament of the tube may be protected by a resistor of suitable resistance for the tube, used as shown in Fig. 1. As a means of stabilizing an r.f. tube with the least trouble and expense, the grid suppressor method in Fig. 2 leaves little to be desired. An inexpensive strip resistor, having a value of from 300 to 800 ohms, may be used for this purpose, as the exact value is not critical. Grid- biasing the heater-type a.c. tube is easily done by inserting a strip resistor in the negative-B lead as in Fig. 3. This method depends on the voltage drop across the resistor for the biasing effect and a by- pass condenser of either .5 or 1 mfd. is employed as shown POPULAR MECHANICS USED AS FILAMENT RESISTOR USED AS'CBIAS RESISTOR WITH A-C.WEATER TUBE C) 8- GRO. USED AS GRID SUPPRESSOR New Device Eliminates Antenna The device shown in the photo is said to give results equal or superior to those obtainable from a good outdoor antenna Antenna Eliminator, Showing Shielded Ground Lead and Clamp; Left, Sketch Showing Installation through the employment of a new pick-up principle. It consists of an insulated cy- lindrical shell, 3 in. in diameter and 5 in. high, containing an inductance and capacity unit. This unit consists of a sin- gle-element shielded vacuum tube, ar- ranged in electromagnetic relation to a solenoid coil, the inductance of which is variable in order to adapt it to any re- ceiver, for better selectivity and reduced local interference. It is claimed that the r.f, signal delivered to the receiver from the vacuum tube is both filtered and am- plified by its action. The device is self- contained and may be installed in the back.of the radio cabinet or console. Antenna and ground binding posts are provided and these are connected to the corresponding binding posts on the re- ceiver. A shielded ground lead is pro- vided with a clamp which is connected to a radiator, water-pipe or other ground. When installation is made, a station is tuned in at the set and the knob on the unit is turned until maximum volume is obtained, after which no further adjust- ment or attention is required. @Popular Mechanics’ radio department offers its information service free to all readers of our magazine. We will be glad to help you with your radio problems and will promptly answer all inquiries.

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aasemyeiae chia eS RSE ES Sg SR GR Se FRR eS sere we res a tN ee Right, a Simple Trouble Shooter for Multitube Re- ceivers; Start at Antenna- Stage Socket in Set and Transfer Tube to Tester, In- sert Plug and Tune Set for Signals; If Signals Are Heard in the Phones, Move Tester to Succeeding Stages Until Dead Stage Is Located; When Plugged into Audio Stage, Shunt Out Grid Con- denser; Jumper Is Removed for Ammeter to Read Fila- ment Current of Tube PANEL BRACKET TRIANGULAR TUBE BASE FILLED WITH SEALING WAX { Easily Made Angles and Brackets for the Homemade Receiver; Brass Strip 1-16 by %4 In., Is Suitable for the Triangular Brackets, and % by %-In. Strip Is Best for Shelf- Supporting Brackets, Which Must Carry More or Less Weight; Right, Bending the Brass Strip around Large Nails Clamped in a Vise Insures Angles of the Same Height PHONE -TIP , JACKS U FULL SCALE a DEFLECTION \p00 OF METER OHMS 1.MA. 1. Vv 10 V. 100 V. 1.5 1.5 15 15 2. 2. 20 200 a 3. 30 300 5. 5. 50 500 8. 8. 80 0. 10. 100 Above, Diagram and Chart for Using a Milliammeter as a Voltmeter by Means of Suitable Resistors in Series; a Milliammeter with Full-Scale Deflection Is Best for Testing B-Power Voltages, as the Resistance Is 1,000 Ohms per Volt; Others May Be Used for General Voltage Testing; Left, Above, Meter and Re- sistance Units Arranged on a Small Wooden Base Tw UVUHOS HT SP wHO® 20H

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eo Seen" waFerw * & = 32-VOLT FARM-LIGHTING CIRCUIT OR 10- 5 D.P.D.T. AMPERE oe Ww SwitTcH FUSES ==” 9- Ps caper | EE TO FILAMENT YT OF RADIO SET TWO 40-WATT 32-VOLT BULBS IN PARALLEL CARBON FIL. a &-VOLT ; DET. STAGE COIL OF PREFERRED + RADIO BAT. \. THE TUNED -RF. w = “ \ RECEIVER Above, hen Drilling Radio Panels, Place a Piece of Soft Wood of the Same Width under the Panel, and Always Drill Panels from Front to Back to Insure a Clean-Cut Hole at the Front Above, a Simple Method of Charging Radio Bat- tery from Farm-Lighting Circuit; the Fuses Protect the Main-Line Fuses; for a Light Charge Remove One 40-Watt Lamp; Right, Additional R.F. Amplification for a Su- perheterodyne from a Tuned R.F. Receiver Con- nected to Antenna and Ground; a 60-Turn Coil, Connected to the Loop Posts, Is Inductively Cou- pled to the Detector-Stage Coil R.F. RECEIVER aaa - PORTION OF socker/ METAL coun Upper Left, a Single-Th-ow Relay Switch Made by Changing the Terminals and Length- ening the Blades of an Ordinary Double-Pole Double-Throw Knife Switch: Above, Tube a Mounted in a Portable Instrument So That It May Be Removed Easily from Above; the Metal Cover Was Obtained from the Junk Box; the Tube Socket Is Supported by Two 1-16 by %%-In. Brass Strips; Left, Soldering a Tap on an Inductance Coil Is an Easy Mat- ter, If the Wire on the Coil Is Raised with a Toothpick

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eee eee eoeettrr patie ciremmanste ttt teante ate RRO

Combination Hookup for the Experimenter By D. A. BROWN RADIO programs, phonograph music or two-way conversation is possible with

receiver, and at the extension end there is a relay panel consisting of a push button and a small 4%-volt battery mounted as shown below. The switchboard should be located in some convenient position near the re- ceiver. Mount the switches just as shown in the insert photo and wiring diagram below, so as to avoid confusion when fol- lowing the directions to be given. The audio section of the set should fol-

———— ‘ G 6 7 we ! | FE *T-.0005 MFD. i” | | os — DET.) TAR 6} 7 - Fl- 4 ; =| + Ye Z =, Z { é € <— 15 OHM \ ce, € MN waka “ j TUNER DESIGN IS 30-OHM \ f L OPTIONAL

S.P.D.T. SWITCHES —

\ the hookup shown in the diagram. The radio receiver will perform all the ordi- nary functions of a set, tuning in the va- rious stations on the speaker in the con- trol room as well as operating a second speaker installed in another part of the building. The circuit can also be used for the amplification of phonograph rec- ords which may be heard in either or both rooms as desired. The switches are arranged so that a per- son in the control room may speak to an- other in the room where the remote speaker is located and vice versa, to carry on a conversation both ways. Ordinary loud speakers are used for all three oper- ations. The equipment for this domestic telephone exchange costs very little. An electric bell is installed near the radio

669

— BELL BUTTON

RELAY PANEL IN REMOTE ROOM piss

low the diagram closely, but the tuner may be of any type desired and is not shown in the circuit diagram. When the set is completed and the extension wires laid to the other room, the batteries and speakers are connected. Now, to tune in a station on the receiver and operate the set speaker only, place switch No. 1 up, switch No. 2 up, switch No. 3 up and throw switch No. 4 to the right. Switch

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1er 10t che res ind in the up, ind No. 5 is left out for broadcast signals. Switch No. 3 is merely a line switch in negative-A and is left closed in the up position for all operations. To operate the extension only, on broadcast signals, place switch No. 1 up, No. 2 down and throw No. 4 to the right. Now, if the operator wishes to have the broadcast signals on both speakers, place switch No. 1 up, No. 2 up and throw No. 4 to the left. This places the loud speak-° ers in parallel. To use the audio amplifier for phono- graph records, a standard pick-up device is connected to the terminals marked “pick-up” above switch No. 5. Place switch No. 1 down and throw No. 5 to the left. Switches No. 2 and No. 4 will now throw the speakers in and out as desired. For two-way telephone communication, with the set speaker acting as the micro- phone, turn switch No. 1 down, No. 2 down, No. 4 left and No. 5 right. The operator may now speak softly into the speaker, and the person at the other speake. will hear his voice at loud-speaker volume. To listen to the reply from the other room, the operator throws switch No. 2 to the up-position. When the per- son at the remote speaker wishes to call the operator, he simply presses the push button to ring the bell and the operator throws the switch to listen. FOR THE RADIO BUILDER The blueprints below include the best of Pop- ular Mechanics tested circuits. When ordering, simply quote numbers of blueprints desired and inclose proper amount addressed to Popular Mechanics Magazine, Radio Dept., 200 E. On- tario St., Chicago, Ill. Magazines containing full descriptions of the circuits can be obtained. Send 25 cents for each magazine desired, giving date of publication. No. 111, Homemade Tube Tester July 1926. .25c No. 115,15 to 550-Meter Three- Tube Receiver Nov. 1926. .25c No. 116, Three-Tube Loop Set. Dec. 1926 25c No. 123, Economy-Nine Super- heterodyne Nov. 1927. .50c No. 130, One-Tube Short-Wave Adapter Mar. 1928. .25c No. 134, Edison Type B-Battery July 1928. .25c No. 138, Screen-Grid Perfect- Tone Six Receiver Nov. 1928. .25c No. 139, Simple Television Re- ceiver Dec. 1928. .25c No. 140, Power Amplifier and B- supply for Television . Jan. 1929. 25c No. 142, Two-Tube Screen-Grid Short-Wave Adapter Mar. 1929. 25c No. 143, Four-Tube Screen-Grid Receiver May 1929. 25c No. 144, Three-Tube Self-Con- tained A.C. Receiver . Oct. 1929. 25c¢ POPULAR MECHANICS 661 Tuner Employs Four Screen-Grid Tubes Five tubes, four of which are of the screen-grid type, make this new tuner especially interesting to the DX fan. The Completely Assembled Tuner Unit Showing the Screen- Grid Tubes in Position parts are available in kit form for home assembly, and the completed unit is suit- able for mounting in a console. The a.c. screen-grid tubes are used with a new type of completely shielded rf. trans- former, and a type-227 tube is used for the detector. A feature of the tuner is the new color dial, whereby, as the knob is turned, the scale is projected in various colors on a ground-glass screen. Any good power supply and audio amplifier may be used with the tuner, but a spe- cially designed power unit, consisting of a type-280 tube for a rectifier, one stage of transformer audio with a type-227 tube and a stage of push-pull amplification with two of the new type-245 power tubes is sold completely wired by the manufac- turer of the above kit. Locating Defective Condensers in Power Units In most cases trouble in power units is located in defective condensers. A sim- ple and effective method of locating con- denser trouble is to connect the elimi- nator to the light line in series with a 100- watt lamp. With the rectifying tube in the eliminator, the 100-watt lamp _ will glow if the condensers are shorted. It is then an easy matter to unsolder the con- nections on the condenser bank until the lamp goes out, and then check up on the condenser unit that caused the lamp to go out. If there are no shorted con- densers and no load on the eliminator, the lamp should be out.

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. . Sonenneeniemeatanaiehanediaennbeibtiimatenkiaeeenaateteeaimedemeannand Celyvene tae GA 662 POPULAR MECHANICS transformer. If this does not produce results, group them in series and parallel across the sec- ondary, until the desired low tone is obtained. When these condensers are connected in parallel, the capacities are added; if connected in series the effective capacity is less than that of the smallest unit in the series. Radio Switch Clock Is Designed for Fruit Growers A radio switch clock that automatically turns the radio set on or off at Upper Left, Bridge Approach Showing Location of Flasher Signal; Below, any desired time has Diagram of Filter Installation; Right, Signal at Through Street Interference from Flashers under Control In many suburban districts, through streets are protected by flashing signals. The interference from such an installation is usually in the form of a periodic click- ing which may be picked up by radio re- . ceivers located anywhere within a one- mile radius of the flasher. Similar flash- ing signals are used at rural crossings and bridge approaches. The installation shown in the upper photo is located near Walpole, Mass., and consists of two 25- watt lamps on opposite sides of the road, about 25 ft. apart. It caused set owners in the vicinity to look about for a remedy. A special filter designed for this form of interference completely eliminated the trouble. The local service man investigat- ing receiving conditions in the vicinity of such flashing signals can co-operate with the local highway department in eliminat- ing interference from this source, as these filters are now available. Deeper Tones from the Speaker If the depth of tone is not satisfactory, the following method will often secure the desired result: Provide three fixed con- densers of .00025, .0005 and .002-mfd. ca- pacity, and connect them, one at a time, across the secondary of the first audio been especially de- signed for the citrus growers of southern California. The temperature readings for each district are announced by radio at frequent intervals throughout the night, and if frost is likely to appear, the grower must be wide awake and on the job. With the automatic switch, he notes the time announced for the next report, sets the dial for that time and returns to bed, knowing that he will be awakened by the radio announcer when his set is turned on at the expected time. The switch is mounted in a neat metal base upon which the clock is supported by two standards. There are two dials, one for setting the turning-on time, and the other for set- ting the turn- ing-off time. The switch is connected be- tween the battery or light socket and the set, in series with the filament. It is designed for operation with sets em- ploying either 6-volt batteries, eliminators, trickle chargers or with a.c. sets.

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i- Old Favorites in New Forms 4.VERY boy at some time or other ~ makes a windmill, and for years these devices have been merrily whirling on the barn, garage or backyard fence. Of late, however, it has become quite a fad to make animated windmills of all sorts, two types of which are described in this article. The first drawing shows a danc- ing darky, and is the work of I. M. Mon- teney, of Castle Kock, Wash., while the galloping horse on the following page was designed and made by Owen Stevens, of Chico, Calif. Four-bladed propellers are best to use for this purpose as they catch more air and consequently transmit more energy to the mechanism. To make a suitable propeller to operate the dancing darky, take two 12-in. lengths of 1 by 2-in. stock, such as poplar, which is easy to cut to shape. The detail at the upper right- hand corner shows how the block is cut diagonally to form a blade at each end. Remember that opposite blades must be inclined in opposite directions when view- ing them from end to end, this being clearly indicated by the diagonal lines in the detail. The two pieces are mortised and nailed together in the exact center, after which the blades may be trimmed down separately to balance the whole pro- peller. A 6-in. shaft, cut from ™%-in. Animated Windmills Are Now the Fad; This Dancing Darky Is Always Full of Pep When the Wind Blows 663

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664 POPULAR dowel stock, is set firmly in the propeller hub and two hardwood blocks, drilled to receive the shaft, form the bearings. A collar on the shaft next to the hub, keeps the hub from rubbing against the bearing and thus elimi- nates excessive friction. The l-in. crank arm, which is at- tached to the end of the shaft, is shown just above the detail of the shaft, together with a 2-in. connecting rod. A length of wire, to which "x2" 3 FT. LONG -- MECHANICS Although the Horse Keeps on Galloping without Fatigue, the Huge Fish Wiggles Its Tail and Al- ways Keeps the Same Distance behind Him the figure of the darky is attached, is bent at the lower end to pivot on the end of the connecting rod and is supported in two bearings so that it stands vertically. The first of these bearings is formed by a hole drilled through a wooden platform, representing the floor on which the darky does his dance, while the second bearing is made by forming an eye in a length of wire, which is attached to the platform as indicated. The figure must be care- fully made, the arms and legs being loosely pivoted so that they will move freely when the figure reciprocates up and down. The remaining parts of the device, including the framework, the weather vane and the base, which is fitted with a pin at the point of balance, are all clearly shown, and no difficulty will be experi- enced in making and assembling the de- vice. Bright colors add considerably to the attractiveness of the windmill, and paint also preserves the wood. Take care, however, not to get any thick pa-nt be- tween the bearing surfaces, or on the joints of the figure. Oil applied to these points will reduce friction and also keep moisture from penétrating the wood. Besides its obvious usefulness as a weather vane, the galloping horse, which is much larger than the dancing darky, makes a suitable adornment for the barn. The propeller is 3 ft. across and the blades are made of 1 by 2-in. wood. The drive pin, consisting of a length of light metal rod or heavy galvanized-iron wire, is securely an- chored to the hub of the propeller and the other end is bent to form a crank. The crank moves a connecting rod attached to the horse’s head, which is pivoted to allow a vertical movement. The legs are also pivoted and a positive movement is im- parted to them by wire connecting rods, one of which is attached to the head. Thus the head and both pairs of legs move in unison, as indicated by the dotted lines. The horse can be made of either wood or sheet metal, and the vane, attached to the

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w 8 F vw POPULAR MECHANICS 665 rear part of the frame, is cut from sheet metal to resemble a huge fish. The im- pression one gets is that the horse is try- ing to outdistance the fish, which wiggles its tail—if this is made of thin shim brass —and swims after the horse. An Electric Radiator Heater In an unheated garage it is rather dif- ficult to keep the engine reasonably warm, to permit easy starting. If desired, how- ever, a simple electric heater can be made to fit against the radiator. Get a shallow pan large enough to fit the front of the radiator and obtain a heating coil about 6 or 8 in. long, which is designed for use on 110-volt current, and draws from 400 to 600 watts. If such a coil is not readily available an ordinary radiant electric- heater element, which can be obtained at any hardware store, will do. In the case of the coil first mentioned, it is mounted on the inside of the pan with suitable brack- ets, care being taken to keep it weil insu- lated, and two lengths of asbestos-covered cord are connected to it as shown. Ifa heater coil is used, merely screw a cleat receptacle to the inside of the pan on a right-angle bracket so that when the ele- ment is screwed into the receptacle it will be parallel to the bottom of the pan. A bail is provided so that the pan can be hung over the radiator filling spout. Electric Radiator Heater for the Auto Is Easy to Make and Costs Little Holder for the Baby’s Bottle There is no necessity for holding the baby’s bottle by hand, as a simple bottle Wire Holder for the Baby’s Bottle That Will Save Mother Much Time holder, of the kind shown in the draw- ing, can readily be made. It consists of a length of wire bent to clamp on the bottle. Rubber tubing is slipped over this end to insure a good grip. The wire fits into a length of tubing which is drilled and tapped for a thumbscrew to permit adjustment for height. The tubing is split at the lower end and bent out so that it can be attached to a square frame by means of screws, the bent ends of the tubing being drilled to accommodate them. The frame fits under the pad of the cot, and is held firm by the baby’s weight. If desired, the tubing can be attached di- rectly to the side of the cradle instead of the square base, but this arrangement limits its use to the cradle only.—Mrs. Ruth E. Shaw, Kansas City, Mo. Peeling Onions When peeling onions just hold the onion in the left hand with the root end upper- most, and peel downward toward the stem end. By doing this you will find that “there is not a tear in a peck.”—Mrs. J. E. Bourne, East Providence, R. I.

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POPULAR v WASTE ~ Simple Device for Gassing Rodents in Their Burrows Has Been Found Effective Gassing Rodents In cases where it is not advisable to lay poison to destroy rats and other rodents, try gassing them by the method shown in the drawing. Take an old paint drum about 12 in. long and 8 in. in diameter, and fasten the lid to the side by means of a link hinge. Punch a hole in the lid to admit the point of a pair of bellows. In the base of the drum punch a 2-in. hole, and solder a short length of sheet- metal tubing around the hole as shown. Rivet or solder a strip of sheet metal about 2% in. wide to the inside of the drum to prevent cotton waste and sulphur, which is later put into the drum, from clogging the pipe. In use, the drum is opened and some old, oily cotton waste is placed in- side and ignited. If necessary, the lid may be closed and the cotton waste fanned with the bellows to get a good glow. Usu- ally, however, the waste will burn readily if the lid is Fig. 1, the Ratchet Mechanism, Showing Wear; Figs. 2 to 4, How the Parts Are Repaired MECHANICS removed. While smoking well, place the pipe in the mouth of the burrow, prefer- ably to the windward side of the other holes. All holes from which smoke issues should be plugged up tightly. Then the drum is opened and some sulphur is sprin- kled on the cotton waste, after which the cover is replaced and the bellows operated to force the fumes into the burrow. Sul- phur dioxide is generated and this will kill the rats if they cannot get out.— George H. Holden, Chesterfield, Eng. Glass-Cutting Kink Glass cutting without special tools is usually unsatisfactory and sometimes wasteful. The ruler or yardstick com- monly used, often slips when the cutter is pressed against it, and the whole piece of glass may be ruined. To avoid this trouble, cut a strip of rubber from an inner tube, about the width and length of the ruler or stick. Lay the strip un- der the ruler, and no slipping will occur. —F. W. Bentley, Jr., Missouri Valley, Ia. Repairing Lawnmower Many lawnmowers are constructed with a pawl and a ratchet wheel, as shown in Fig. 1 of the accompanying illustration. They are quickly worn so that the ratchet does not hold at all times, particularly when the cutter stops with the pawl in a horizontal position. However, the ma- chine can be made as good as new by filing or grinding the pawl as shown in Fig. 2, grinding a twist drill to a sharper angle than usual and cutting out the ratchets as shown in Fig. 4. By using the adjacent ratchet as a_ ful- crum for the drill. it can be worked across the face of the ratchet, and a perfectly square face readily cut on it in a tew turns. Fic.2

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POPULAR MECHANICS 667 Repair for the Timer Roller of Old-Model Ford While making a long drive, the owner of an old-model Ford had the misfortune to break a timer-roller spring and was unable to proceed. As there was no serv- ice station or telephone handy, he was at a loss what to do until he thought of tak- ing a rubber band, which he had in his pocket, and wrapping it around the roller arm to take the place of the spring. The result was entirely satisfactory and he was able to drive to the next service sta- tion without any trouble—Glen F. Still- well, Collinsville, Tl. Inexpensive Electric Vaporizer When you wish to warm or vaporize a small quantity of liquid, or melt a solid, such as paraffin or wax, which does not require an intense heat, try the method shown in the drawing, which makes use of a 16-cp. lamp of the carbon type as a heating unit. Screw a cleat receptacle to a small piece of wood, which is used as a base. Connect a length of lamp- cord to the receptacle for plugging into a convenient outlet. Take a clean tin can and remove the ends so that the resulting cylinder will be about 2 in. longer than the combined height of the lamp and socket. In cutting one end leave two small lugs. These are bent over to form feet which are tacked to the base. A small notch is also cut in the bottom to receive the lampcord. For best results, it is advisable to line the inside of the can with asbestos paper. Cut another can down to form a shallow dish of a diameter a trifle smaller than that of the first. Also leave four lugs which, when bent over, form hooks for supporting it on the The heat generated top of the tall can. by the carbon lamp is sufficient to melt or vaporize the contents of the shallow dish in a few moments.—L. B. Robbins, Harwich, Mass Pair of Andirons for the Fireplace Made from Iron hip Anchors Andirons Made from Old Anchors For the cottage or lodge fireplace, a novel pair of andirons can be made from old anchors, preferably those of the “kedge” type with a fixed crossbar. The length of the shank should not be over 20 in. to fit in the average fireplace. Plain black iron makes the most rustic appear- ance. Saw off one fluke about halfway between the tip and the shank and saw off each end of the crossbar near the ball and the crook as shown. Heat the ends of the bar and bend them down at right angles to form legs parallel to the re- maining fluke. The height of the legs should be the same as that of the portion from which the fluke was removed. Place the andirons thus made side by side in the fireplace as shown, and you will find them quite nautical in appearance and able to support a heavy load of logs. @To make your shoe soles last longer, warm them and then apply two or three coats of hot copal varnish; this treatment makes the soles waterproof.

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CTOBER 31—Hallowe’en—that’s the night the “ghost walks,” and, believe it or not, if you can cause delicious shivers to run up and down the respective spines of your various party guests, you'll get three cheers and a tiger from everyone concerned. Did you ever “walk the plank?” Off into the briny deep, I mean, with salt water and everything! You will need a plank, of course, and one end of this should be supported on a low box. Also, you should have on hand an ordinary sprayer filled with salt water. Your vic- tim is blindfolded, and a guide on either side take his hands and lead him up the plank, as shown in Fig. 1. As he pro- gresses, the guides should stoop lower and lower in order to give the plank-walker the impression that he is going up a con- siderable height. At the end of the plank, the victim is told to halt. The guides step away. You can give-a short farewell ad- dress: “The howling sea that is upon us tonight!” At this part of the speech, someone takes the sprayer and sprays 668 salt water in the victim’s face, while an- other member of the “plank-walking bri- gade” runs a wooden paddle around in a pail of water. A sheet of tin can be shaken to get the windstorm effect. The victim is then prodded gently from be- hind and commanded to “yump.” From all past observations, he should expe- rience a considerable thrill in jumping down through space those few short inches. Here’s something else. No Hallowe’en party is complete without the traditional “shost story.” An excellent manner in which to put this across is to seat your guests in a circle on the floor, see Fig. 2. In the center of the circle place three or four lighted candles. As the telling of the story proceeds, the candles mag- ically go out, one by one, until at the climax, the “Now I’ve got you!” stuff, the last candle goes out, leaving the room in total darkness. The “nigger in the woodpile”~ isn’t much. It is merely a matter of cutting the candles, taking out a small piece of

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At the wick, as shown in Fig. 3, and then putting the candles together again by slightly heating both of the cut ends. Of course, when the candle burns down to the break in the wick it will go out. Give the idea a little experimenting be- forehand, so that the various candles will be properly timed. Try this stunt: You are seated at a table. Around the table are other spec- tators, all holding hands, making a com- plete chain. The room is dark. Now, slowly and with a soft glowing intensity, a small light appears in the center of the group. It grows in intensity and form until you are horrified—or should be—tc see a death head floating above the center of the table, bathed in a halo of saffron fire. The illusion lasts for a full breath- taking ten seconds, and then the head slowly fades from view. Lights! Every- body’s hands clasped! Nothing on the table! The manner of effecting this spooky illusion is quite simple. Get a hollow tube of tin or cardboard, about % in. in Paint the out- diameter and 5 in. long. side of this tube black. Now, glue a large dark balloon to one end of this tube, as shown in Fig. 4. After the glue has set, inflate the balloon to its full di- mensions, and on it, with luminous paint, paint the figure of a grinning skull, as shown in Fig. 5. Mark the tube at the free end in some manner so that you can tell, with your lips alone, whether the skull head is upside down or not. Stuff the balloon up into the tube. And now for the stunt. You are seated at the table. Your hands are held. The prepared tube, looking for all the world like a fountain pen, is in your upper coat 669

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670 pocket, or if you happen to be a “leddy,” under the top of your dress. The lights are out. Now, do you see how the trick is ac- complished ? A sim- ple matter to duck your head, as shown in Fig. 6, get the end of the tube, and, oh, well, the rest is just a lot of “hot air!” How’s this? The host (that’s you) brings forward to the center of the room a sheeted, ghost- like figure, which, up until then, had oc- cupied an unobtrusive place in one cor- ner. This ghostlike figure is introduced as the Talking Fool, Ghostland’s only in- terpreter. This figure, as explained fur- ther, not only talks, but will answer any questions which may be asked of it. And it does—a deep sonorous voice that an- swers all and sundry interrogations with varying degrees of truthiulness. No, there’s no small boy concealed be- neath the sheet. In fact, there is nothing at all under the sheet except a wooden pole to hold the figure upright. Well, then, iow is it done? Like this: POPULAR MECHANICS Get a small wooden barrel hoop. Get two lengths of 1%-in. half-round lumber about 4 ft. long, and two short lengths of wood, 4 in. wide by % in. thick. Get a speaker unit of the type used in the average radio set and some wire. With these various things in readiness, you can very easily duplicate the figure shown in Fig. 7. The barrel hoop is nailed to the top of the two pieces of half-round mold- ing. The speaker unit is fitted into a hole _drilled through the hoop, as shown in Fig. 8, and the wires from this unit are inclosed between the two pieces of half- round. The two pieces of 4-in. wide-wood stock are used to fashion a base for the upright pole, and the wires from the speaker are fas- tened in place at either end of one of these crosspieces to two nails, the ends of which pro- t ject about &% in. below the under surface of the wooden support, as vin shown in the dia- gram, Fig. 11. The idea of these nails is to allow an elec- trical connection between the speaker unit and two pieces of tin which should

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POPULAR MECHANICS

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“672 POPULAR MECHANICS be placed on the floor, as may be seen in Fig. 7. Are things getting any clearer? Well, two wires are bolted or soldered to the tin sections, and these wires, fastened to the floor by means of thumbtacks, lead ~— ~~ LOUD-SPEAKER OUTLET RADIO ‘* PHONOGRAPHIC PICK-UP JACK a----- WIRES --—> TIN SHEETS i , THIS AREA WITHIN HEARING BUT OUT OF SIGHT wires From |i LOUD SPEAKER |} UNIT i MICROPHONE ees === a - BATTERIES WIRES ARE ® NAIL FASTENED ‘NAIL TO NAILS onto tin plates, a line to the radio and out to a microphone—that’s the whole outfit. And now for the performance. You bring the outfit to the center of the floor. An old sheet has been fastened in place over the bare framework, with features painted on, as shown in Fig. 9. You take care that the figure is placed just so, in order that the nails in the crosspiece will make contact through the rug with the tin sheets. And there you are! The man at the end of the microphone should be close enough to the party group to hear the various questions. His answer is whispered softly into the microphone, it goes through an amplifying stage by radio, and comes out like the proverbial “ton of bricks” from the ghost’s mouth. The assistant’s voice, however close, can- not be detected because it is perfectly synchronized with the “ghostly chatter.” Try it! You will find that with a little care in the concealment of the wires, everybody will be very much mystified. Of course, there are hundreds of other spooky stunts which you can ef- fect at Hallowe’en. You can use flasher buttons in order to make a ghost or a black cat with orange or red blinking eyes. How about paint- ing skull heads on bal- loons with luminous paint so that they will glow weirdly in the dark ? Painting a white skeleton on a black bag, touching into the loud-speaker outlet of your radio set. Now, from the phonographic pick- up jack of your set, run two wires, over the floor again, to a convenient closet or down to the basement via the hot-air shaft—anywhere that is within hearing yet out of sight. Two batteries are hooked onto this line, and a microphone ends the whole thing. Maybe it sounds rather complicated, but the diagram shown in Fig. 11 should make the whole thing clear: A speaker unit at one end, a connection made by nail ends projecting through the rug it up with luminous paint, and having it shoot along a long wire from the top of the house to the garage? A wet glove, with thin sticks glued inside each finger to imitate the real bony handclasp of some departed spirit, gives a real thrill in the dark. How about writing fortunes with a solution of baking soda and water, and then reveal- ing the fortunes by holding a lighted can- dle under them, causing the writing to turn brown? But try this one: On a white sheet of cardboard, paste a large orange pumpkin cut-out, with eyes, nose and mouth of blue pay rod era spi! cor foll Wa: soa bru Wi] late pip job bet scr: as eli tre the scr thi: she cut she fit the Sct Car

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POPULAR MECHANICS 673 paper pasted on, as shown in Fig. 12. Hang this pumpkin face on the wall and below it arrange a second sheet of plain white card- board, as shown in Fig. 13. If you will look the jack-o’-lantern square in the mouth as you count twenty without blinking, and then stare at the plain sheet of card- board, you will soon see the filmy, ghostly spirit of Mr. Jack-o’-lan- tern—a blue face with orange features—mysteriously appear on the blank cardboard and then as mysteriously pass through the solid wall. No, Amos, there’s no trick about it. It’s merely a mat- ter of retention of vision—what- ever that is—and you need but try it to be convinced. Preserving Fishing-Rod Grips Often the cork grip of a fishing rod chips or peels off after sev- eral seasons’ use. This is caused by per- spiration absorbed from the palm by the cork. The trouble can be prevented as follows: Before storing the rod away wash the cork with lukewarm water and soap, scrubbing it lightly with a soft brush. It should then be rinsed and wiped, and hung in a shady well-venti- lated place until thoroughly dry. Stove-Pipe Cleaner Everyone who has taken down stove- pipes for cleaning knows how messy the job is. The writer has found it much better to disconnect the pipes and scrape the soot out as shown, which eliminates the trouble of taking them down. The scraper used for this purpose has a sheet-metal blade cut to the shape Sheet-Metal Hood for the Motor That Protects the Outboard Aquaplaner from Injury Safeguard for the Outboard Aquaplaner Although outboard aquaplaning is a comparatively safe sport, there is always some danger that the operator may over- balance and fall back against the motor with painful if not serious consequences. To avoid this trouble make a sheet-metal hood, preferably of heavy aluminum, and hinge it to the deck just ahead of the motor as shown in the illustration. When starting the motor, the hood can be pushed forward so that it will not be in the way, and when running, it completely covers all the projecting parts of the mo- tor. Sharp edges and corners must, of course, be avoided or the hood would defeat its own pur- pose.—D. Rockwell, Hollywood, Calif. @An emergency corkscrew, which will prove efficient, shown and having a curved edge to can be made in a few moments by fit the contour of the pipe—A. C. Schofield, Craven, straightening a safety pin to its full length and coiling Canada. With This Scraper It Is Not Necessary to Take Stove- pipes Down for Cleaning it around a nail.

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674 POPULAR Cornstalk Fuselage for Model Airplane Is Strong and urable Cornstalk Makes Airplane Fuselage A piece of cornstalk makes an ideal model-airplane fuselage, according to My- ron Alber of Beatrice, Nebr. A section of stalk, about 20 in. long, is carefully hol- lowed out. This can be done by means of a length of wire, one end of which is flat- tened and bent over at right angles to forma scraper. The shell of the cornstalk is very strong, stands considerable twist- ing, and completely incloses the rubber band used as motor. A balsa-wood plug is fitted into the front end of the stalk. The rear part is reduced in size by cutting out triangular sections, about 5 in. long and % in. wide at the base. After these sections have been removed, the end of the stalk can be brought together and glued, leaving a hole about % in. in diameter at the end. This hole is also plugged with balsa wood in which a hook is fastened for the attachment of the rubber bands.— Dale R. Van Horn, Lincoln, Nebr. Tinning Soldering Bits A soldering bit may be tinned without any trouble by using the following method: Get a coarse brick, a fire brick being preferable, although an ordinary red brick will do. Cut some grooves in the upper surface to receive the bits, the grooves being made a little deeper at one MECHANICS end than at the other. The brick is warmed enough to melt some rosin which is put in the grooves. The bit is filed bright, heated and placed in one of the grooves. A stick of solder is held against it and the bit rubbed back and forth in the groove. It may be necessary to add a little more rosin. The bit should be dipped in zine chloride both before and after it is heated. A short rubbing in the puddle of solder will tin the bit quickly. If a file for brightening the bit is not available, rub the bit against the brick, which will serve the same purpose. Watch Holder for the Auto All that is necessary to make the dash- board watch holder shown in the photo, are a few inches of heavy copper wire, rubber tubing of the same length as the wire and of sufficient diameter to permit it to be slipped over the wire, and a 4-in. piece of soft iron, about Me in. thick and 4 in. wide. After the tubing is slipped over the wire, the latter is bent to the shape shown, to grip the watch securely, and mounted on the iron strip by means of a short screw, the wire being bent to form an eye for the screw, and the iron strip drilled and tapped to receive it. A second hole is drilled through one end of the strip so that it can be fastened to the instrument board as indicated. The pur- pose of the rubber tubing is to hold the watch securely without marring its sur- face, and to avoid rattling—Walter E. Burton, Akron, Ohio. Dashboard Watch Holder Made from a Length of Heavy Wire and a Strip of Sheet Metal

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Or OO — = a d yt ns to on POPULAR MECHANICS ca HINGED C STEPS Convenient Folding Stairway to the Attic In many a small home or summer cot- tage, the attic can be reached only through a trapdoor in the ceiling, which is trou- blesome, especially when it is necessary to lift boxes for storage. In one of the suburban homes of Boston, there is a hid- den stairway which solves the problem x ee Folding Stairway to the Attic Which Is ~ Convenient to Use and Entirely Hidden = When Folded by providing an easy and convenient ac- cess to the attic yet economizes space. Each step is hinged to the stringers so that the stairs can be folded against the wall. The trapdoor is sawed out at one side to make room for the upper end of the folded stairway and hold it securely when the door is closed. A rod near the bottom supports the folded stairs, the ends of the rod fitting in slots cut in a specially built door casing. Four doors, which completely hide the stairway when it is not in use, are hung from the casing. The drawings show the construction of the in- stallation with sufficient clearness to en- able anyone to duplicate it, if desired — Mrs. Lillian S. Loveland, Wellesley, Mass. Sealing-Wax Lacquer Sealing wax, which consists mostly of rosin and shellac, is soluble in denatured alcohol and dries with a high gloss, mak- ing the solution desirable as a lacquer for decorative purposes. The sticks of wax should be broken into very small pieces and enough alcohol added’ to dissolve them. Unglazed pottery can be decorated with this lacquer as follows: Cut the de- sign from a piece of printed crepe paper and glue it to the surface of the work. 30th the paper and the exposed surface of the pottery are given an application of the lacquer. After this has hardened, the paper is removed and the background can be treated in another color.

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Takie Tabata with His Prize-Winning Model Plane; Note the Position of the Wing AKIE Tabata, a 14-year-old boy scout of Pasadena, spent three painstaking days constructing this trim monoplane. ‘It looked pretty good to Takie, but this modest little craftsman was in no way prepared for the sensation his ship made by remaining in the air 41 consecutive STRAIGHT-GRAINED PIECE OF 5 WIDE HARD BALSA §X1}X16" USED IN MAKING PROPELLER ~\ minutes at the Star-News—Pitzer and Warwick model-airplane meet at Ross field, Arcadia, Calif., on June Ist. The judges were amazed at the swift climb of this 2-oz. tractor, and when it passed out of sight beyond a tall euca- lyptus tree, the timer assumed it had come to earth and stopped his watch at 10 m‘n. 46:5 sec. Even that seemed a long fight to the timer, but the adventurous little monoplane had only begun to warm up; for 30 more minutes it soared above the 676 fields before coming to earth again. Had it not been for the timer’s error this would have set a world’s record. Of course Takie had made other model planes; many of them, and he “knew his stuff.” The features which enabled the record-breaker to ride on the breeze and cover over 2 mi. are, in his opinion, the exceptionally wide wing span of 48 in. and the reverse camber of the stabilizer which tends to hold the tail down when losing speed, and preventing a nose dive. By no means did the propeller pull continuously for 41 min.; on the contrary, tests dem- onstrated that when wound to the safe limit of 200 turns with a 4-to-1 mechani- cal winder, the prop revolves only 2% min. But in that comparatively brief space enough altitude is gained to per- mit duration and distance before yield- ing to gravity. It is estimated that this plane attained from 800 to 1,000 ft. alti- tude on its record flight. Young Tabata says there are no tricks in building a duplicate of his prize winner, SHAFT HOLE MADE WITH / PIN DRILL ' ! WY S A WS SS te and he wants all Popular Me- chanics model-airplane builders to have an opportunity to share his design. With the exception of bam- a.

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y quired, the plane has an all-balsa frame- work throughout. boo “wishbone” ribs in the fuselage and frames of the sizes shown, such music wire and washers as are re- square so-called “hard” balsa, which is

all of \%-in.

3egin with the two top longerons, — T Fsang J Fig. 2, tying them together with cross- o—F asaxiz” "G L'MUSIC WIRE LANDING GEAR, FRAME. STRADDLES NOSE : ' NS wu ~~ Act / SHAPED FROM Lk SS a SRD BALSA) WISHBONE BAMBOO —\ a : BENT OVER CANDLE BOUND [---.-- < ING ig Xz, “4 ‘.- ane “WITH THREAD AND CEMENTED \ G STEEL WASHER, CEMENTED ON ~~~ — 2-PLY BALSA, GRAIN AT RIGHT ANGLES, §” —— WIDE, 15” DIAM.

CG) Fol heavier thz he soft grade. me ned e than the soft grade

ix % SOFT BALSA considerably stronger, harder and slightly Thread will RETAINING WASHER hold the pointed ends of the boat-shaped 677

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678 POPULAR MECHANICS a cee moe -_ | = ~ ecanenscss = t ‘ -| | "9 a 4° - i y or - UPWARD ; " i} : vee | 2 I F Gir J x \---- LEADING EDGE SANDED FROM %SQ. BALSA \ Tal

poe iin hoe

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POPULAR MECHANICS frame together until the ambroid hardens at the joints of the cross- pieces. Next bend four bamboo wishbones at a sharp angle over a candle flame. The bamboo pieces should be about %e-in. square section, and bending should be done slowly and gen- tly, with the glossy side of the bamboo about an inch above the flame. The ends of the bamboo are pointed and pressed a little way into the top longerons, just enough to keep them from springing out while the ambroid is hardening. When all are set, install the bottom longeron, bind- ing it to the apexes of the wish- bones with thread and ambroid. The nosing, which serves also as a prop-shaft bearing, is of steel, %e in. wide and about %2 in. thick, or less. Neither aluminum nor brass will carry the load prop- erly. The rear ends are tied to- gether with a piece of %2-in. music wire having a “U” bent in the center to carry the S-hook. For such a long and thifi pro- peller as this 16-in. job, a select piece of straight-grained hard “of Lenina tae Yee ere balsa should be used. The diagrams (Fig. 1) illus- a trate the method of shap- ing the blades, substan- : tially the same as on the prop of the Hixon- Wheaton tractor described in the September issue. The thinness of the blades is limited only by the builder’s skill, but should not be over %e in. at the tips. The hole in the hub for the shaft should be absolutely square with the blades and can be drilled with a tool made by flattening the end of a short section of music wire, grinding the edge sharp and chucking in a hand drill. This tool also is handy for drilling the hole in the nosing, although a fine twist drill is even better. A small steel washer is ambroided to the back of the hub, and a loose brass nut runs on the shaft behind it. All steel washers can be cut from the same size sheet steel as the nosing. Make the wheels of 2-ply balsa by am- broiding two pieces of Me-in. stuff to- Des oo ee APPROX 10° TREAD, 135° Fic.4 a Tabata Launching His Plane for Its Astonishing Flight at the Arcadia Meet, Where It Created a Sensation gether with the grain at right angles. A short piece of brass tubing serves as the hub. Washers ambroided to the axles keep the wheel in place.

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POPULAR MECHANICS

When the glue hold- ing the paper fabric is thoroughly dry, apply wing dope with a soft brush. Best results are secured with a half-and- half mixture of the dope and lacquer thinner. But do not use any dope on stabilizer or fin, as it will warp the delicate frames. The three sides of the fuselage are covered one at a time with separate pieces of rice paper. As

i ae ’ x

% RUBBER BAND 10 FASTEN WING \p 8 STRANDS jg RURSER BANDS, if ------- COVERED | UNCOVERED © SECTION Fic.5 | The wing, Fig. 3, | is an all-balsa job, with hard balsa for

STABILIZER HAS REVERSED __ CAMBER ON & RADIUS

*S._RuBBER _!

in the case of the wing, do not apply glue to the ribs. When the glue is dry on the wing halves, tie them together at the dihedral angle (see Fig. 4) by means of short pieces of bamboo bent over a candle. The cen- tral spar is tied with a short and stout piece of balsa. All joints are ambroided and bound with thread. In making the stabilizer frame, Fig. 3, take care that all ribs are bent on the same curve, that is, with an 8-in. radius. This can be done by steaming and bend- ing over a lighted electric bulb, or over a wooden form. They should be thor- oughly dry, however, before ambroiding to the framework. Paper is used only on the bottom of the stabilizer, and on one side of the fin, or rudder. The frame of the latter is simplicity itself, being merely a rectangle of %s-in. by %e-in. hard-balsa strips mitered at the corners. It is braced by threads to the corners of the stabilizer. A small block of balsa is ambroided to the rear center of the stabilizer to make

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POPULAR MECHANICS 681 it level with the direction of flight, or parallel with the strands of the motor. Balsa blocks aré also ambroided to the underside of the wing at the center in order to tilt the front edge upward at ap- proximately 4°. The most efficient angle will be determined by experiment. Now adjust eight strands of e-in. flat- rubber band so there is a little slack when unwound. By all means provide yourself. with a mechanical winder, or make one from an egg beater. It is indispensable for this type of ship, since the rubbers can be wound four times as much by stretching them out. At first do not go over about 75 turns with a 4-to-1 winder. Tabata says that 200 turns with the winder is a safe limit; he has gone as high as 250, but does not recommend it. You will get best results at first by launching in the air by hand. Give it a gentle thrust—and always into the breeze, not with it. The breeze will help it gain altitude, though in the meantime it will swing about and follow the direction of the wind. It is of utmost importance to have all surfaces in their proper alinement. A slight variation one way or another will ruin its performance. And note from the photo how far back Tabata sets his wing —well back of the center of the fuselage. But this is precisely the position in which it made the record flight for him. Make this wonderful little monoplane according to these plans and you will have a ship you’ve always hoped to own—one that flies and flies—and how! Wax Covers Barb on Fishing Hook To prevent the barb of fishing hooks from catching on the inside of the fishing-tackle kit, cover the barb with a wad of paraffin or wax as shown. When the hock is to be used it is an easy matter to break off the wax. The writer found that hooks with barbs protected in this way could be carried in the pocket when it was not desired to carry along any unnecessary equipment.—George Woodwin, Ramea Is- land, Newfoundland. SEALING WAX — Concrete Lawn Seat and Tree Guard Besides serving as a lawn seat, a circu- lar slab of concrete with a suitable open- Neat Lawn Seat and Tree Guard Made of Concrete Slab and Blocks ing in the center, as shown in the photo, makes a good guard for a small tree. It is set on three concrete blocks, although tile can be used if desired. The slab was cast on a smooth surface with two strips of tin or galvanized sheet iron on edge serv- ing as a form. The ends of the strips were soldered together previous to pour- ing the concrete, the outer one measur- ing 48 in. and the inner one 20 in. in diameter. The inside form was laid down first and filled with sand to prevent crumpling. Then the larger form was laid about it so that both were concen- tric, giving a uniform spacing of 14 in. be- tween the two all the way around. Con- crete made in the proportions of 1 part of cement to 3 parts of sand, with just enough water to make a quaky mixture, was used. The supporting blocks were made by pouring concrete into small nail kegs. After the concrete was thoroughly dry (it was allowed to stand for five days) the seat was assembled and given a coat- ing of white cement wash.—Dale R. Van Horn, Lincoln, Nebr.

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682 POPULAR Hotbed Which Is Accessible from the Basement Keeps the Flowers Blooming during Winter Basement Hotbed A hotbed accessible from the basement, as shown in the illustration, has been in use for several years by a Nebraska resi- dent. A suitable opening in the basement wall was made and finished off by fitting a 2 by 6-in. frame snugly in it. A num- ‘ber of studs were set at 2'4-ft. intervals to accommodate sash, which could be closed when desired in order to keep out furnace fumes, although these fumes were not found detrimental to plant life in the hotbed. The earth was, of course, excavated on the outside before the open- ing in the wall was made. The wall was made 5 in. thick and was built all around the edge as indicated. The level of the hotbed should be about 3 ft. below the lawn and the wall should project about 6 in. above it. A frame of 2 by 4-in. ma- terial was built over the hotbed, sloping from the house, and fitted with sash. One- fourth-inch wire mesh was tacked over the outside of the sash to prevent the glass from being broken by negligence or acci- dent. Although a southern exposure of the bed is preferable, this one was built on the east side of the house and was found entirely satisfactory. As the auto drive ran right past the hotbed, the owner thought it advisable to provide concrete tracks as shown in the drawing. These were made in 6-ft. lengths, 10 in. high and MECHANICS 12 in. wide, with a groove of sufficient width to accommodate the auto wheel. It is almost impossible to get out of these tracks, and this eliminates the possibility of skidding over against the bed, which is likely to occur during the winter.—Dale R. Van Horn, Lincoln, Nebr. Drying Negatives Quickly When it is necessary to dry negatives quickly, make a saturated solution of carbonate of potash, which has the prop- erty of absorbing water from gelatine. An immersion of five minutes in this so- lution will be sufficient, after which the surplus water must be soaked up with a blotter and the negative rubbed dry with a soft cloth. If there is not enough time to wash the negatives thoroughly after fixing, this can be postponed until after they have been used for printing. A _pe- culiarity of this process is that the film may be stripped from its backing by cut- ting all around the margin, after which it may be transferred to another and used in reverse—George Parke, Chicago. Film-Spool Ends Make Good Grommets Small chains used in a drilling outfit passed through some canvas covering in several places, and it was found necessary to provide grommets, but these could not be pro- cured at once, so they were improvised from a num- ber of old film - spool ends as shown in the photo. The raised portion of one ferrule was cut off and enlarged a trifle to go over the other ferrule when the latter was _ pushed through the hole in the canvas. The peen of a hammer was held over it and the hammer struck with a block of wood, beading the ferrule over and compressing the disks firmly on the canvas. a -_ Se ele a ae a Fs fs =— + sO Fa

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| a — POPULAR MECHANICS FEED LINE |” PIPE, GZ AR VENT 3 PIPE TO HOT-WATER TANK -Small Cafe, Formerly Using Stove Heat, Made More Modern by the Installation of Hot-Water System Using the Excess Heat from the Kitchen Range Heat Cafe with Excess Heat from Range When the proprietor of a small cafe found that his range heated the water in the range tank to the boiling point much faster than he could use it, he asked a steam fitter if this waste heat could not be used to heat the dining room, where stoves were more or less unsatisfactory. The steam fitter made the installation shown in the drawing, and it has given good service for over two years. The hot water rises out of the tank into the top pipe, which runs down at a slight an- gle to the farthest radiator. Two other radiators are also connected as_ indi- cated. After the water has passed through them, it is cooled considerably and flows back to the heating coil in the range through a return pipe installed so that it slants toward the stove. An air vent is placed at the high point of the feed line. Keeping Auto Free from Rust The owner of a new car usually takes pride in the appearance of the nickeled parts of his car. If the car is purchased during the winter months, some of these parts may become partly rusted before warm weather arrives. When I buy a new car I give them several coats of light oil applied with a rag. This protects the finish by covering the nickel, and the oil can easily be removed when the weather moderates... Certain parts of the chassis and engine of a new car may show signs of rusting, but this can be prevented by giving them a coat of old crankcase oil with a brush. Keep a small fruit jar of such oil on hand in the garage for this purpose. Surplus oil may be removed with a rag. Many mechanics clean greasy parts of the motor with gasoline. This is effective, but highly inflammable. It is much better to use carbon tetrachloride and gasoline mixed in equal parts.—Ross J. Plaisted, Cleveland, Ohio, Emergency Knife Sharpener A knife sharpener that takes very little room, costs practically nothing and has been found highly efficient, can be made from any old metal twist drill, % in. in diameter or less. The bit is merely fas- tened to a ta- ble top, shelf or a piece of wood by means of two staples. Pull- ing the knife blade across the drill, as indicated, will produce a clean, sharp edge, equal to one made by using an ex- pensive sharpening device.

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POPULAR MECHANICS few extra turns so that the chuck jaws will seat firmly against the top of the strip. This gives valu- able support where it is most needed because the wood, espe- cially hardwood, will bind on the drill and will hold tightly against the chuck jaws.—W. J. Lennox, Wiarton, Ontario, Can. Make This Speedy Skimmer Although the little paper craft shown on the opposite page may seem too frail to last long, it is Cart Equipped — = Auto Wheels and Casings Provides omfort for the Driver Cart Equipped with Old Auto Tires Old auto casings give many miles of comfort to the driver of the two-wheeled cart shown in the photo. In a small Kansas town two carts thus equipped are in use, and the owners claim that the ex- tra comfort is worth the cost of the wheels and tires. An additional advantage is that they are practically noiseless on paved streets —Frank Sargent, Holten, Kans. “Strait-Jacket” for Drills Prevents Breakage in Sheet Metal When drilling holes in sheet metal with an ordinary hand drill, one is likely to bend and_ break the drill. A wood- en jacket,as shown in the drawing, will elim- inate this trouble. Such a jacket can be made in a mo- ment. Rip out a strip approxi- mately % in. square, a piece of tonguing from an old board being about the right size. Cut it a little shorter than the drill and then run the drill through - it lengthwise, as indicated. Give the drill just a waterproof and, with care in han- dling, will have surprisingly long life. It draws scarcely % in. of water and the slightest puff of wind will send it skimming across the pond like the proverbial “scared cat.” Cut some strips for the lengthwise parts of the frame from three-ply bristol board. The crossmem- bers are made from the lightest cigar-box lids you can obtain. Get one of cedar if possible. This wood is strong enough for the purpose, very light and easy to whittle. Cut the triangular stem from white pine. To assemble the frame, tack the crossmembers upside down in their relative position on a board. Let the nails project on the underside so that they can be withdrawn easily. Thin, short brads are best for the purpose. Now lay a keel of very thin wood, gluing it in place with shellac. Gunwales are next and then the long strips. The latter are first fastened to the two central crossmembers_ with waterproof glue or shellac and, when dry, are similarly glued to the bow and stern pieces. The “planking” thus provided should be bound to the crossmembers se- curely with strips of light paper, also glued or shellacked on. Ordinary wrap- ping paper is now cut to cover the hull, coated with spar varnish, and applied be- fore the varnish dries. For a rudder, at- tach a piece of tin, cut and bent to the shape shown, and tack it to the stern. The mast and spars are made of light bamboo splints and the sail of waxed sandwich paper. If you find that your particular model requires ballast to prevent it from capsizing, simply put a nut or washer on the floor just back of the middle cross- member. This boat has been found to outrun any model boat with sails.

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This Ten-Inch Paper Boat Is So Light That It Draws Only One-Eighth Inch of Water and Develops a Sur- risin _—— 685

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a Ae TE 686 POPULAR MECHANICS Saving Time When Repairing Inner Tubes After finding the leak in an inner tube, which has been pre- viously inflated, insert a pointed cotter pin in the hole. This spreads the rubber and lets the air out quickly, in fact much faster than it takes to remove the valve core for the same purpose. The cotter pin is ground to a point and then spread apart so that every time it is used it must first be squeezed together. The spout of an old oilcan will serve the same purpose. Old Coffee Bottles Decorated in Modern Style You can revamp your old coffee bottles in keeping with the latest style and will then find them es- pecially popular for use on bridge tables. Get some silk cord, or any other colored cord to your taste, and wrap it around the neck Small Adjustable Baby Seat Hooks over the Front Seat of Any of the bottles tightly. Shellac Make of Car Comfortable Auto Seat for Baby The seat shown in the drawing is home- made and can be hooked onto the front seat of any make of car. It can be made from new material or the top part of any small child’s chair may be altered to suit, if one is available. A couple of slides are fastened to the back to accommodate a board by which adjustment for height is made possible. In the center of the board a slot is cut as indicated, and a hole is drilled through the back of the seat in line with the slot to receive a bolt and wingnut with which the board can be securely tightened in any desired posi- tion. A U-shaped bracket of flat iron is attached to the top part of the board and hooks over the seat. It will be found that a tray made to be-clamped over the chair arms provides additional convenience. When the tray is not used a strap across the arms keeps the baby from falling for- ward. Besides being handy in the auto, such a seat can be hooked over the back of an ordinary chair to make a high chair. —Wayne M. Judy, Clear Lake, Iowa. the cord after it is wrapped. Pro- cure some carved wooden figures of suit- able size to be fastened to the corks of the bottles. Use waterproof glue to do this and be sure to scrape all traces of paint and varnish from the two surfaces that are to be glued. Wooden beads can be attached to the neck with thread slipped and tied between the cord wrapping. In case you have no coffee bottles, get some similar bottles used for chemical tests. They are made of specially annealed glass, which, although very thin, will with- stand consid- erable heat, and hot coffee can be poured into them without breaking them. The cost of these bottles is about 50 cents and the deco- rative mate- rial should not exceed the same amount. —Frank H. Williams, Santa Ana, Calif.

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wwe wa ow =a OO . k >e > SHOP NOTES All Shop Notes published in 1928, in book form—Fifty Cents—from our Book Department How to Apply the “Sugi” Finish By HAROLD JACKSON OME of the finer arts come to us from the orient. The Japanese, especially, are very artistic people and we have learned many things from them, among which is the beautiful treatment of wood known as the “sugi’” finish. Many gen- erations ago the Japanese gathered drift- wood and fashioned beautiful articles from it without artificial treatment of any kind. After continued pounding of the waves and the chemical action of the salty sea water the softer parts of the wood be- came destroyed and the harder parts were left protruding from the surface. This, caused a beautiful embossed finish which rendered every delicate curve and irregu- larity of the grain in a particularly strik- ing manner. On account of the irregular shape and the limited amount of driftwood, the use of this naturally embossed wood was very restricted. But the Japanese craftsman was not content to sit down at the beach and wait for inferior pieces of driftwood to blow in. Besides, the chemical action of the sea is very slow. The Japanese then turned to another ele- ment of nature that is more rapid in its action. They used fire. They made artificial drift- wood that is far su- perior to that made by nature in the sea. Craftsmen found [ that, by scorching the surface of the wood and | brushing out the 4 charred parts, a perfect driftwood finish re- Burning the Cypress with the Blowtorch to Produce the Sugi Finish

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688 POPULAR MECHANICS Scrubbing Out ea Portions with a Wire Brush sulted, and they gave the world some- thing entirely new and different in the way of wood treatment. Sugi is a wood the Japanese have found to be especially adapted to this finish. Sugi and cypress are very much alike in their characteristics and the latter takes ‘the finish just as well as sugi itself. Of the American woods, cypress is the only one that takes the sugi finish perfectly. Fir does fairly well, but a wood that has considerable difference between the hard and the soft parts, that has an elaborate and showy grain, and that is free from resin, is essential. The process of applying the sugi finish is more simple than the reading of the instructions. Anyone can do it. A gaso- line blowtorch and a wire brush are the required tools. Nothing else is needed. The entire surface of the wood is charred with the torch until it is totally black all over. Burn the surface as evenly as pos- sible. When burnt, set the wood away for 48 hours before doing anything more to it. At the end of that time the finish is completed by brushing the charred sur- face with a rather stiff wire brush. Brush with the grain. This completely removes all of the charred portions and leaves the wood a rich brown color which is very pleasing to the most critical eye. No varnish should ever be used on this finish. To do so will spoil the whole job. If a little gloss is de- sired wax only should be used. Rags or waste should be used to polish the surface whether wax is used or not. The parts must be finished be- fore they are installed. During the burning the board will warp on account of the moisture being forced to the back of the board by the application of the intense heat of the torch. This should cause no alarm, and the difficulty can be remedied by allowing time for the moisture to again adjust itself within the board. It takes about 48 hours to do this. This adjustment can be hastened by placing the board in the sun, burnt-side down. In applying the sugi finish there are only four rules that, re- quire special attention. They are, use dry cypress, do not overburn, do not rub for 48 hours after burning, and use care in rubbing so as to get an even tone. The more you rub, the lighter the color be- comes. The shade depends upon the rub- bing, not the burning. a Artists’ Brush Holder Two rubber bands attached to a tum- bler, as shown in the drawing, make an excellent brush holder for artists. Three knots are tied in one of the bands at equal in- tervals. This band is stretched over the top of the glass and another band is snapped around the glass to hold the first one. The brushes are slipped be- tween the knots so that the bris- tles dip in the wa- ter without touch- aul ing the sides or bottom of the glass, which allows them to retain their shape. T

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— TS §& | ee Oe | ce ee eo POPULAR Removing Tar and Asphalt Spots Do not use soap on tar or asphalt spots on cloth, as this will set it in a way to make the cleaning almost impossible. Rub the spots with soft grease, and set aside until the grease penetrates the tar. Re- move the tar and grease with gasoline, or by washing in hot suds. Asphalt should be wetted with kerosene and left to stand, then washed in turpentine or alcohol. Double Parting Tool The time required to part off work in a lathe can often be reduced by one-half if the arrangement shown in the drawing is used. In the case illustrated a piece of tubing is being parted to make collars. Ordinarily a parting tool will cut freely until it gets into the cut a short distance and then it is likely to clog because the cuttings do not clear themselves. By us- ing two parting tools as shown, neither tool cuts into the work enough to permit clogging. Both tools are offset and are mounted one over the other in the tool- holder. However, as it takes more time to set two tools than a single one, this arrangement is not suggested as a time- saver for cutting a single collar. DETAIL OF DOUBLE PARTING TOOL Two Offset Parting Tools Cut Collars from Both Sides of the Tubing MECHANICS Forked Tool Made from Pipe and Fittings Helps Re- move and Replace Heavy Disk Wheels Forked Tool Helps Mount Disk Wheels Heavy disk wheels of the demountable type can be put on the hub with little exertion if the illustrated tool is used. It consists of pipe and fittings and has a forked end which is slipped under the wheel while the other end serves as a handle. The method of using it is clearly shown. Anyone who has changed disk wheels will appreciate this helpful tool._— G. A. Luers, Washington, D. C. Weight on Mower Lightens Tongue The weight of a mower tongue together with the vibration of the machine, will usu- ally cause sore necks on a team of horses after a day or so of steady work. One farmer suspends a cement block from the seat by means of a strong strap, which counterbalances the tongue and also ab- sorbs some of the vibration.—J. R. Gentry, Lincoln, Nebr. @iIn the absence of a brace to hold your wood auger, get an ordinary faucet han- dle and slip it over the square tapered end of the auger so that it can be turned by hand.

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690 POPULAR MECHANICS Developing Sodas Can Be Dissolved Quickly by Dust- * ing Them in the Water and Rocking the Tray Quick Method of Making Photo Solutions Ordinarily, when making developers, the sodas, stirred into a tray of water, set in chunks as hard as rock before they can be scattered sufficiently, and many minutes are lost before they are all dis- solved. The drawing shows a method which greatly reduces the time needed to dissolve them. First, be sure that the sodas are thoroughly powdered. Put the water for the solution in a large tray so that it will not be too deep. Lift one end of the tray and rock it steadily with- out allowing it to slop over the ends. Sprinkle the soda powder evenly in the water, in the middle of the tray where the washing action is strongest. With a little practice, this can be done so that no lumps will be formed, the swishing of the water keeping each tiny grain in sus- pension and almost instantly dissolving it. In a timed test, 1 oz. of carbonate of soda was dissolved in 10 oz. of water, by stirring and crushing the lumps after they were formed, in 1214 minutes at 65°, for perfect solution. When the same quantity was dissolved by sprinkling it in as the tray was rocked, complete solu- tion was accomplished in 3 minutes. In dissolving larger quantities, the use of a salt shaker makes it impossible to drop too much soda into the water accidentally. This method holds good only with pow- dered sodas, but as they are the kinds al- most universally used, the busy photog- rapher can save many valuable minutes. When the sodas are mixed separately, the sulphite will give little trouble, but most ready-mixed developers for amateurs will have them combined, and the carbonate will control both—C. K. Van Druff, Mc- Louth, Kans. How to Prevent “Offset” in Printing On a rush job where printing was nec- essary on both sides of the paper, and there was not enough time to permit the first run to dry properly before backing up, the makeshift method of preventing offset described below was used with suc- cess. Sufficient packing was removed from under the draw sheet of the job- press platen to allow for a sheet of ordi- nary print paper. This sheet was pasted along the top of the platen and extended to the guide pins to which the work was fed. After 50 to 100 impressions had been made, the sheet was replaced with a clean one. This method saves time and gives permissible results where speed is essential on an ordinary run.—Edgar Sherman, Tucumcari, N. M Measuring Diameter of Flanged Holes By equipping a pair of inside firm-joint calipers with toolmakers’ buttons as shown, one can take ac- curate meas- urements in flanged holes. When a cali- pering job is to be done, ‘‘mike’”’ the buttons with the caliper points set in- side of the flange. Re- move the calipers and reset them to the same distance between the buttons, and you will have the exact diameter of the hole inside the flange at the caliper points

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Fe — wr fF «e n- he nd he ts Can for Local Hardening It is often necessary to harden both ends of a piece of work and leave the middle section soft. When the piece is short, as in the case of link pins, it is a rather diffi- cult job to do this. If one end is hardened at a time the heat is likely to travel along the pin and soften the end previously hardened. As it is out of the question to heat the ends at the same time and leave . the center cold, the next best thing is to heat the whole surface of the pin and keep the central portion away from the water when the ends are quenched. The photo shows a simple method of doing this. Obtain a tin can and drill a hole through the sides, about 1 in. below the top, making the holes a trifle larger than the pins, so that these can be inserted and removed easily. For convenience a stiff handle may be affixed to the can. In use, a pin is heated to the right temperature, pushed through the holes in the can and the whole dipped into the water until the pin is submerged, but not the top of the can. Of course, some water leaks through the holes but the ends of the pin are thoroughly cold before much water gets into the can, and the center section is too cold to be affected by the water, so that conse- quently it re- mains soft.— Harry Moore, Hamilton, Canada. Cutting Threads without a Die After bolts had been set in the concrete foundation for an engine, it was found that the threads were not cut far enough down to allow the nuts to be tightened on the engine bed. Not having a thread- ing die, the makeshift method shown in the drawing was used with good results. A nut fitting the thread was attached to a POPULAR MECHANICS TT ome = Eick my ~~BIT L) ~-WORK \ HANDLE Improvised Method of Threading Bolts Set in Con- crete Foundation steei bar near one edge by means of a U-bolt. A threading tool was put through the bar near the other edge and was held in place by a long setscrew. By rotating the nut with the bar and feeding the tool lightly with a hammer for each cut, the threading was accomplished in a short time, and the job was found entirely satis- factory —August Jeffers, Bedford, Ind. Simple Method of Slinging a Barrel A simple method of slinging a barrel, which is open at the top, is to put the barrel on the sling so that the latter comes in the middle of the bottom. Then take one side of the sling and put a half hitch around the barrel near the top, but not too close to the edge. Take the other side of the sling and put an- other half hitch around the barrel just above the first. The barrel can now be safely hoisted.—C. New- kirk, Chicago.

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BY FAR the greater part of the furniture in use today is stain-finished walnut, mahogany or oak. As some pieces of fur- niture receive harder wear than others, and as frequently one piece of a suite meets with an accident, some practical in- formation on the restoration of such pieces should be of general interest in every home. Of course, the processes de- scribed are only those that can be at- temped by the amateur, as the skill- ful professional worker uses many methods that cannot be followed by the unskilled layman. Before attempting any work of this kind get a bottle of good fur- niture polish, a small bottle of sewing-machine oil and 10 cents’ worth of pow- dered rottenstone. One of the high- grade furniture pol- 692 By BERTON ELLIOT ishes, sold by paint-supply stores to fur- niture repair men, is best, if procurable. Light damages to the finish of a piece of furniture, which have not dug down into or through the stain in the wood can be inspected by wetting the finger and rub- bing over the bruise. If the bruise is not through the color it will be practically un- noticeable when wet and will show the same effect as you will get when varnish is applied. Practically all varnish-finished surfaces in which there are light damages can be greatly improved in appearance with furniture polish, rottenstone and sewing-machine oil, and plenty of “elbow grease”; in fact, most of them can be restored nearly to their original state. You may be surprised to find that a table top that you thought was practically ruined beyond repair can be made a thing of beauty again in about 20 minutes. Marks caused by hot dishes are treated as follows: First try to polish out the marks with furniture polish, rubbing them vigorously with a soft cloth and using just as much pressure as possible. As there is no abrasive in liquid furniture polish the surface will stand a good deal of rubbing without injury. Give the surface a final rubbing off with a dry, clean cloth to re- move all the surplus polish. If there are any marks or spots that show dull, polish them up with the rottenstone as follows: Place some of the rottenstone in a saucer and pour out some of the sewing-machine oil into another shallow receptacle. Dip a pad of soft cloth into the oil first and then into the rottenstone, and rub briskly, but with not too much pressure, over the dull spots on the finish. This will not put a polish where there is no finish, Light Damages to Furniture Sur- faces Can Often Be Removed by a Brisk Rubbing with Rotten- stone and Oil = @ «2b @& « aon & _ -—

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oe Ww ph Aubsitnbaniys as a foundation is a necessity, but if there is any finish at all it will be im- proved. Give the entire surface a rubbing off with a clean cloth to re- move the sludgy mix- ture and polish again with furniture polish. 3y working on a table, buffet or dresser top with the furni- ture polish and rottenstone al- ternately for 20 to 30 minutes, it can be brought up to a fine finish, with all light blemishes rendered practically, if not en- tirely, unnoticeable. A dresser on which perfume has been spilled, the luster spoiled and the finish rough- ened, can be restored so that the blemish is hardly noticeable. The remedy depends on how bad the blemish is. If the perfume was wiped up immedi- ately after spilling, a vigorous rubbing with furniture polish or rottenstone and oil may bring up the finish so that it will be quite satisfactory. If the pieces are too badly roughened to be finished in this way, the best thing to do is to give the top a finishing coat of varnish, unless the piece is an expensive one and requires the services of an expert craftsman for refinishing. The ordinary piece of fur- niture, however, especially golden oak and other furniture in gloss-varnish finish, can be satisfactorily refinished by the home worker in the following way: Sand- paper the place where the perfume was spilled until perfectly smooth, and also sand the rest of the top lightly, using sandpaper not coarser than No. 00, No. WOOO being preferable. Dust the surface carefully and then apply a coat of high- grade interior finishing varnish over the The Top Which Looked Beyond Repair Is Polished to Look Like New with Little Effort entire surface. If the finish was in extremely bad condition from the perfume, it may be necessary to apply two coats of varnish, in which case the first coat should be sandpapered lightly or rubbed over with fine steel wool, after drying for at least 48 hours. The final varnish coat may be left in full gloss or rubbed to a semi-dull finish after drying 48 hours, by using steel wool of a very fine grade, dipped in linseed oil, or by using pumice stone and oil. Some prefer to give a piece a finishing coat of flat-dry- ing varnish, following the gloss-varnish coat, instead of rubbing, which produces a very beautiful semi-dull finish, although not having quite the richness of a hand- rubbed job. If some of the varnish finish has been chipped off, but the color still remains in the wood, clean the disfigured part thor- oughly with soap and water. Rinse off with clear water and allow to stand until 693

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4 694 POPULAR absolutely dry. Sandpaper the entire sur- face lightly, feathering the edges around the chipped place so that they taper down gradually instead of forming a sharp in- dentation. When this has been done, ap- ply a coat of varnish over the entire sur- face. In case this does not produce a per- fectly smooth finish, without showing any trace of the chipped place, sandpaper lightly again, and flow on another coat of varnish, after the first coat has been allowed to dry for 48 hours. This can, of course, be rubbed or given a finishing coat of flat-drying varnish, as previously mentioned. Deep bruises that go down into or through the stain in the wood will show up distinctly even when rubbed with a mois- tened finger. Such damages are more diffi- cult to repair than light ones, especially for the amateur who has not the equipment and cannot well attempt the more intricate processes open to the professional fin- isher. With injuries of this kind the color is more or less gone and must be supplied in some way. The method usually employed by skilled furniture patchers is to fill the dig or abrasion with a material known as “stick shellac” or “furni- ture finishers’ stick cement,” which is melted into the abrasion and smoothed with a hot knife. This ma- terial comes in col- ors to match the Surface, Then Var- popular hardwood hpished and Rubbed finishes, and is of a Down transparent nature so that the grain of the wood shows through. After the stick shellac has been melted in or “burned in,” the entire sur- face is polished off, which the professional finisher usually does by a process known as French polishing. This is the only method that will permit good matching of deep damages. However, unless one is skilled in the work, he is likely to make a Deep Bruises Are Stained to Match the MECHANICS mess of it, so that the finish will look worse than before. For less conspicuous surfaces and arti- cles where a flawless repair is not neces- sary, the following method may be used satisfactorily. Work a little stain into the bruise so that it colors the exposed wood to about the same shade as the finish. A “penetrating” stain is best for this pur- pose and may be obtained in all of the popular hardwood effects. It should be worked into the abrasion with a small camel’s-hair penciling brush, and the sur- plus stain wiped off quickly with a cloth, to prevent coloring the wood too dark. If the effect is found to be too light, work in a little more stain and wipe off again, repeating the process several times if nec- essary, until the color matches the rest of the surface. When the stain is thoroughly dry carefully flow the scratch full of var- nish with a small camel’s-hair brush. When the varnish has dried thoroughly for at least 48 hours, go over it a few times with a dry cloth and then rub the entire sur- face with furniture polish. It may also be necessary to use rottenstone and oil as previously de- scribed. If trouble is experienced in dulling down the gloss of the varnish patch to match the rest of the surface, rub over the glossy place lightly and carefully with a small piece of fine steel wool, then polish up the sur- face again. This should produce a uniform effect. In case it is found that the stain applied to the abrasion did not darken the bruise sufficiently to match the rest of the surface, a touch of stain may be applied over the filled abrasion with a small brush. Water marks in furniture greatly de- tract from its appearance. Some kinds of varnish will not stand water without be-

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| A el ‘ —_— vil be- POPULAR coming white. If, for example, a wet bathing suit or towel is left on a chair for any length of time, it may be found that the surface has turned to a very pro- nounced grayish color wherever the wet article has touched it. While this dis- figures the piece seemingly beyond repair, all that is necessary is to sandpaper the surface with very fine sandpaper and apply a coat of varnish. The cloudy effect entirely disappears with this revarnishing.- The new finish may be left in full gloss or the glare may be softened to a semi- dull luster by rubbing down as described. Clear lacquer has recently come into extensive use for the finishing coats on stain-finished furniture, instead of var- nish. For the finest possible patching of lacquer-finished pieces somewhat different methods than those described are em- ployed in the professional shop. How- ever, for the home worker, the methods described in this article may be used, the slight differences in luster between the varnish patch and the lacquer being taken care of by polishing or rubbing the patch after the retouching has been finished. Brace Keeps Door from Sagging When a heavy door begins to sag it is often quite a task to remove it to plane off the edge. Sometimes a door will keep on sagging and if constantly planed it will be out of square to a noticeable extent. In places where appearance is not of ut- most importance the diagonal brace shown in the photo will keep the door from sagging. It is simply a rod or length of pipe that is threaded at both ends and slipped through two brackets fas- tened to the door. Tight- ening a nut on each end pulls the door back in proper alinement.— A. Mathieu, Chicago, IIl. MECHANICS Handle for the Bench Screw Bench Screw, Turned by Means X J of a Crank Handle, Reduces the \ P Time Spent in Adjusting Vise v While using a bench screw, a home- workshop owner devised a simple crank handle which enabled him to turn the screw in and out much faster than was possible with a handle of the usual type. It was made of pipe and fittings, as indi- cated in the drawing. The tee which ac- commodates the handle is drilled and tapped to receive an L-bolt, which, when tightened, holds the handle securely. Bands for Bandsaw Wheels We were in need of bands for our band- saw wheels and did not have time to wait for new ones. It was therefore necessary to improvise some bands, which we did in the following way: We purchased a quantity of adhesive tape of the same width as the width of the bandsaw wheels. This was wrapped on the wheels and found entirely satisfactory.—F. L. Jester, Bainbridge, Ga. @An easy method of repairing a leaky bucket or a tin gutter so that it will last a year or more is as follows: Paint the metal inside and out, then paint one side of a strip of cloth and apply it to the in- side painted surface of the metal.

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696 POPULAR MECHANICS Footboard or Treadle with Pivoted Hook Holds Work Firmly in Sawbuck Holding the Work in the Sawbuck When sawing wood on a buck, it will be found best to hold the work firmly, which can be done by means of the foot clamp .shown in the drawing. It consists of a 3 or 4-ft. piece of 2-in. stock, to one end of which a %-in. iron rod is pivoted, the rod being shaped to form a hook at one end and an eyelet at the other, where it pivots in the footboard or treadle. The hook is ground to a point so that it will grip the work securely. Pressure of one foot on the treadle suffices to keep the log from turning while being sawed.—Leslie H. Phinney, Orange, Mass. Template for Drawing Angles of Machine-Screw Heads ‘ In our plant flat-head ma- chine screws are made, ranging from ¥% to &% in. in diameter, and the included angle of the heads is 70°. The time re- quired to lay out the angles on the draft- ing board has been greatly reduced by the use of the illustrated template, made of celluloid. It is placed against the T- square with its center line coinciding with that of the screw. The horizontal lines on the template give the exact position for the top of screws. of various sizes. The angle of the head is first drawn, leav- ing the lines for the top and the slot to be filled in later with the use of the T-square and triangle. Cuts on the underside of the template, near the top, provide ready means for lifting it up from the drawing. —August Jeffers, Bedford, Ind. Feeding Paper on Job Press On many job-printing presses, especially where a solid foundation is lacking, the feeder is continually annoyed and fre- quently some valuable paper stock is ruined, because the vibration makes it work off the feed board. The trouble can be remedied by cutting two wide bands from an old inner tube and slipping them over the feed board crosswise of the way the stock is fed‘ into the press—Edgar Sherman, Tucumcari, N. Mex. Two Screwdriver Kinks Worth Knowing A small metal pipe cap fitted on the end ofascrew- driver will protect the handle against damage when used for tapping. Also the handle Baie can be given a blow with a hammer with- out the risk of splintering the wood. Drill a hole in the handle under the cap and fill the hole with a mixture of white lead and tallow, which when applied to the threads of screws, will make it easy to drive them into hardwood, or in the case of machine screws, will facilitate driving them down if the tapped hole is rusted. Cement-Floor Covering to Prevent Dust If it is desired to make a concrete floor in a factory or mill that will not sand off or make dust, a coating for the purpose can be prepared when making the floor. This coating consists of one part of ce- ment to two parts of crushed rock or hard

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gravel, which will pass through a 4-in. sieve, and from which the fine dust has been removed. This is thoroughly mixed in a mixing box, or by a machine mixer, with a sufficient amount of water to pro- duce a plastic but not sloppy consistency, and spread on the under concrete before either the finish or the under concrete has had time to set. It is floated with a wood float to a true level, and then slightly trow- _ eled with a steel trowel, to bring it to a proper level and to smooth the top slightly. This will give a finish which is pebbly, and not dead smooth or slick like a sand finish. After the finish has been troweled, and has set sufficiently so that the covering will not mar the surface, it should be covered with sawdust, sand, cloths, or any other material which will hold water continuously. The finish should be kept soaking wet for at least a week, or, better, for ten days. Half of Large Tank Used for Truck Body For hauling odd-shaped pieces of iron, such as castings or steel forgings, which cannot be neatly piled on an ordinary truck, a body made from half of a large, discarded tank, has been found highly satisfactory. The cutting of the tank was done with an acetylene torch. Simple blocking keeps the body securely on the chassis and prevents it from rolling. POPULAR MECHANICS Wi ata) i ih i Tool Made of Steel-Bar Stock Tool for Removing Terminals from Storage Batteries For removing terminals from storage batteries quickly and without injury to the battery, the illustrated tool was de- vised by an attendant in a service station, and was found entirely practical and time- saving. It consists of two hooks and a t. My ~ ~~ thrust end for the bat- tery post, the latter being formed on the end of one of the handles, which are made from steel-bar stock, found around the shop. The hooks are piv- oted to the handles as in- dicated in the upper de- tail which shows all the parts of the tool. In use, the hooks engage on op- posite sides of a ter- minal, while the thrust end bears against the top. Manipulation of the han- dles forces the hooks up against the terminal, first on one side and then on the other, prying it off slowly—Geo. A. Luers, Washington, D. C. | ee ie uta NS Useful Truck Body for Odd-Shaped Iron Pieces Can Be Made from Half of Discarded Tank

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POPULAR Two Harrow Disks on a Wooden Handle Make a Good Tool for Covering Freshly Seeded Rows Covering Rows of Seed with Dirt Rows of seeds can be quickly covered with the illustrated tool which was made and used by a Nebraska truck farmer. It consists of a handle cut from a 1 by 6-in. board, 4 ft. long, the corners on the wide end being cut off at an angle, as in- dicated, and two harrow disks attached by means of suitable screws. Holes should be drilled in the handle to receive the screws, to prevent splitting the wood. Washers are provided on each side of the disks to reduce friction and prevent ex- cessive wear on the wood by the rotating disks. In use, the tool is pulled along over the row so that the disks push the dirt up between them, which leaves a small ridge completely covering the seed. —Dale R. Van Horn, Lincoln, Nebr. How to Set and Level a Door Jamb For a 2-ft. 8 in. by 6-ft. 8-in door, make a mark at a point 6 ft. 936 in. above the rough floor and then with a level transfer this point to the other side of the open- ing. In the same.way locate this point on both sides of each door opening to be cased up, using a hand level, straightedge or some other leveling instrument. Then MECHANICS cut the side jambs 6 ft. 834 in. long and case up the sides of the opening, using straight casings. When the side casings are on, set the frame into the opening, holding the top of the casing to the 6-ft. 93g-in. mark. This distance will allow 4% in. for margin, 6 ft. 8 in. for the door, % in. for clearance, and % in. for finish floor. Nail the casings at the top first, being careful to keep them to the mark. Then, using the casing for a straight- edge, plumb the side jambs and finish nailing the casings. The other side casings can now be put on and the work on the opening completed. Before leav- ing the opening, nail the jamb to the rough work with 10-penny finishing nails, driving them at an angle of about 60°. This slant prevents the jamb from being pulled out of place—H. H. Siegele, Em- poria, Kans. A Hydrometer Syringe Used to Test Auto Oil Line To locate trouble in the oil-circulating system of an auto often is a puzzling job. Air leaks on the suction side of the oil pump will stop the supply of oil. To avoid the trouble of taking down the oil pan, use a hydrometer syringe as shown in the illustration. If the rubber nozzle is too small to fit tightly, it may be wound with tape to make it air-tight. If the line leaks inside of the crankcase, the rubber bulb will expand freely, and if the line is clogged, the bulb will not expand at all. In case every- thing is in good condi- tion, the bulb will expand slowly and oil will gradually come up in- side the glass. The same method may be used to test gas lines, but the capacity of the syringe must be equal to the volume of the parts being tested—R. Hadley, Fairfield, Conn. es

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OR best results, chisels, plane irons and similar tools must be ground to a

Sliding Toolrest for Emery Wheel By W. CLYDE LAMMEY

| _ +o

ae = —= —<——_ = _

certain bevel, and the edge must be perfectly square with the tool. The average home mechanic and small-shop owner, who grind these tools on an ordinary hand-oper- ated emery wheel, know how difficult it is to get the edge ground accurately, and will therefore appreciate the sliding tool- rest shown in the drawing. With its use the work can be ground to any bevel de- sired without depending on the accuracy of the eye and the steadiness of the hand. The illustration shows two applications of the tool, one, a lathe-bed attachment and the other an attachment for a hand- operated grinder fastened to a workbench. Essentially the device consists of a wooden toolrest and a small guide sliding in a groove cut across the top of the rest. The adjustable feature of the tool makes it especially valuable, the rest being pivoted

to the base, which permits grinding the edge of the tool to any desired angle. To make a rest of this kind for a hand- operated, 7-in. emery wheel, first remove the iron rest with which the wheel is al- ready equipped. Rip from %-in. hard- maple stock a piece 3 in. wide and 8 in. long. For wheels of other sizes the di- mensions may, of course, be changed. Plow or dado a % by %-in. groove in the rest as indicated, and plane one edge off at a 30° angle. Drill the iron rest for screws to fasten the wood rest to it se- curely, with the beveled edge next to the Easily Made Toolrest for Grinding Plane Irons and Chisels Accurately and at Any Desired Bevel

“i hin » wheel. A guide made of a % by Y%-in. strip with a %-in. block nailed or screwed to the end is then made. The edge of the block must be perfectly straight and must be set at right angles to the guide strip or tongue, which must be a close fit in the groove. Use a small square to check for accuracy. Rub par- affin or soap in the groove and over the guide strip in order to prevent binding. In the case of a toolrest designed to fit a lathe bed, the rest is screwed to a flat-iron support, which is bent at right angles as indicated, and is drilled to receive screws, two of which hold it to the rest secure- ly, another one serving as a pivot. Two blocks fitting on and under the lathe bed serve as the base to which the rest is at- 699

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700 POPULAR MECHANICS tached, as is clearly shown in the upper detail. A bolt and wingnut are used to clamp these pieces to the lathe bed. In use the rest is first set to the correct angle for grinding the work, which is held firmly on the rest with the thumb and first finger of the left hand, while the other fingers go over the guide. Both the guide and work are slid back and forth as a small cut is taken off along the edge of the tool. The emery wheel is turned with the right hand at a fairly good speed. Device to Pick Up Articles Saves Back Stooping over constantly to pick things off the ground is rather hard on the back Hinged Sticks Make Handy Device for Picking Ob- jects off the Ground and therefore the device shown in the photo will be appreciated. It consists of two sticks hinged together near one end, and a spring near the hinge to hold the sticks together. Squeezing the handle opens the sticks so that they can be set over the object to be picked up. Releas- ing the handle allaws the sticks to grip the object securely. It was found advis- able to provide the ends of the sticks with sheet-metal tips. How to Eliminate Static Electricity from Moving Belts Static can best be eliminated from a moving belt by applying to its surface some material which is a good conductor of electricity. Although the theory is not new, it is a question what kind of material to use for this purpose. Rapidly moving metal parts, such as metal disks, never are subject to static troubles because the disks themselves are excellent conductors. For the same reason, metal bandsaws, which run at velocities of thousands of feet per minute, never give static trou- bles. Therefore, if a belt is made con- ductive it will not collect static, but the substance applied must not decrease the coefficient of friction between the belt and the pulleys, must not injure the belt in any way, and must wear well. Experi- ments with a number of materials for use on rubber belts showed that a good grade of spar varnish was a very satisfactory vehicle. Powdered aluminum, bronze, copper, graphite and lampblack have also been tried, various proportions of each being mixed with the varnish. The most satisfactory results for rubber belts were obtained by using a mixture of lampblack, 18 parts, and spar varnish, 82 parts. For a good non-inflammable thinner, equal parts of carbon tetrachloride and painters’ naphtha are recommended. This dressing was carefully tested on belts in actual in- stallations on an air compressor and on a rubber conveyor belt. It was also tried on rubber belts in flourmills and on thresh- ing machines. When it was applied to the entire surface and allowed to dry, static did not develop. The belt should, of course, not be used until the dressing is entirely dry. For leather belts the follow- ing formula has been found satisfactory: liquid fish glue, 100 cu. centimeters; gly- cerin, 88 cu. cm.; sulphonated castor oil, 100 cu. cm.; water, 170 cu. cm.; lamp- black, 82 grams, and 2-per-cent ammo- nium hydroxide, 20 cu. cm. In some in- stances, it is well to increase the amount of glycerin and fish glue. The material for leather belting may be applied while the belt is moving, but the dressing for the rubber belting must be allowed to dry before the belt can be used —W. F. Schap- horst, Newark, N. J ; ca su lik mi an

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Tapping Soft Materials Experimental model work frequently calls for tapped holes in soft materials, such as hard rubber, fiber, wood, and the like. In connection with such work, one may make use of what may be called a “lead” plate. By its use, remarkably clean and accurate threads can be cut with an ordinary tap, even in such material as pine wood. The lead plate is nothing more than a small piece of metal, such as brass or steel, in which a hole of the de- sired size has been tapped. It should be of sufficient thickness to accommodate about three or four threads. In opera- tion, the lead plate is laid over the hole to be tapped and is held in place with the fingers while the tap is revolved through it into the soft material below. Inasmuch as the feed is thus automati- cally assured, the threads will come out clean and true. When one has occasion to thread very small holes, the tap can be dispensed with and the screw itself can be made to cut its own thread by screwing it through the lead plate in the same manner as is done with the tap.— August Jeffers, Bedford, Ind. Roller Helps Load Lumber in Box Cars Loading box cars with lumber can be done easily and quickly by using the pivoted roller shown in the photo. A piece of heavy flat steel is bent at right angles to form a wide “U,” and the ends are drilled to serve as bearings for the roller shaft. A hole is also drilled through the center part of the roller support, which is pivoted by means of a bolt toa4 by 4-in. beam as indicated, a jack screw POPULAR MECHANICS Air Bucker Used in Riveting Can Be Suitably Adjusted under Heavy Tank with Wood Blocks Adjusting the Air Bucker-Up When riveting heavy material, where bucking-up must be done from below, an air bucker, with a piston range of 7 or 8 in., will be found a great help. By using several lengths of metal pipe to slip over the bar of the bucker, setting the lower end of the pipe on a wood block, its ele- vation may be regulated to suit the height of any rivet, on oval surfaces like that of a boiler.—Jos. C. Coyle, Denver, Colo. Saving Electric Light in the Stock Room A toggle switch, arranged so that the opening and closing of a stock-cabinet door would turn the light on and off, re- sulted in a considerable saving of current. The arrangement was found successful in on the end of the beam permitting it to be wedged se- curely in the door- way.—C. Groat, Portland, Oreg. @To stop a drip- ping faucet until a plumber can be called, get a rubber band, at least 1 in. wide, and stretch a printing shop, where the stock cutter, with both hands full of paper, rarely, if ever, stopped to turn the snap switch, but always pushed the cabinet door closed with his foot, switching off the light that formerly burned unnecessa- it over the spout and handle. This Pivoted Roller Lightens the Task of Loading umber into Box Cars rily—E. Sherman, Tucumcari, N. M.

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Testing Metal Cans for Leaks In a Denver establishment, where metal cans are manufactured, tests for leakage Tapered Rubber Nozzle Admits Air to Cans When esting Them for Leaks are made by filling the cans with com- pressed air and then submerging them under water. The air is admitted to the can by means of a cone-shaped rubber nozzle, 3 in. long, 2 in. in diameter at one end and % in. at the other. A %-in. nip- ple is passed through the center of the nozzle to allow easy attachment of the air hose. Owing to its taper, the nozzle can be quickly fitted into any circular opening from % to 2 in. in diam- eter —J. C. Coyle, Denver, Colo. Expansion and Contraction of Wood One of the most serious draw- backs to the use of wood for ac- curate work is its susceptibility to moisture. The sap cells absorb moisture in damp weather and the wood swells, while in dry weather the moisture is drawn out and the wood contracts. This expansion and contraction is practically all POPULAR MECHANICS in the direction running crosswise to the grain. Woods ordinarily swell ten times as much crosswise as lengthwise. Know- ing this, the user should arrange his struc- ture so that changes come in the least important sections. Pacific coast red- wood is an exception to the above rule. It expands just about as much length- wise as the other way and for that reason it is undesirable for most uses.—Donald A. Hampson, Middletown, N. Y. Efficient Guard for a Saw Trimmer An ordinary shower-bath curtain was made into a satisfactory inclosure for the saw trimmer, to prevent metal chips from flying about the shop, in a western print- ing plant. A large ring of heavy iron rod was hung from the ceiling, high enough to allow plenty of room for the worker using the saw to stand under it. From this ring the curtain was suspended by means of the ordinary brass rings, so that it ex- tended about 18 in. below the level of the saw mandrel. A quick jerk on the cur- tain closes it around both the saw and the worker. ‘When not in use, the curtain is pushed to the rear or one side of the saw.—Edgar Sherman, Tucumcari, N. M. Canvas Top for the Tractor Driving a tractor in the rain is not a pleasant task, but the situation can be improved by providing a canvas top like the one shown in the photo. The frame is made of pipe and fittings or iron rod, and the canvas is cut and sewed together to fit over it snugly. Celluloid windows sewed into the canvas give sufficient vi- sion.—Carlton Groat, Portland, Oreg. Canvas Top with Cel- luloid Windows Pro- tects Tractor Driver during Rain

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el- er G “Os “ { COPYRIGHT POPULAR MECHANICS Shey Said It Couldnt Be Done VYJHEN Chicago architects, several years ago, asked Chicago brick lay- ers to build walls of common brick skin- tled-fashion, many refused because they said it was not brickwork. It was at vari- ance with habits of years of bricklaying. But the architects were insistent. And today both Chicago architects and brick- layers can claim a large measure of credit for developing a new idea—skintled brick- work—out of an old material. At the same time they have made an aristocrat out of a product which for many years had been used for the more PLAN NO. 5-B-13 newness of style quite different from any- thing we have had before. Furthermore, such walls are relatively inexpensive. So much so that this new treatment is be- coming very popular in small houses, There are no def- common everyday structural pur- poses, such as rear and sidewalls. Common brick now face the street in fine residence jobs. The endless skintle variations produce a charm of wall texture and estimates. HOW TO GET A BLUEPRINT 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 any house appearing in the magazine for $1. print does away with the necessity of first pur- chasing a oye of plans to find out whether you can afford to build. mr : “ floor plans, elevations, a section detail, size of laid in the wall, joists, studs, etc., and also a brief specification. Submit it to tradesmen and dealers for building inite rules for lay- ing skintled brick- work. The idea is to produce an ir- regular surface or facing in which the brick, unevenly This blue- It contains sometimes project at one end as much as an inch. No 703

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POPULAR MECHANICS ‘Porc - I3-G* j2*6" LIVING Room IS*OnRZEE SSS sss SSAA SSS SSSA GARAGE Enter - 5-B-13 e TiNST FLOOR PLAN = SEN Bep Room IT-o"* |S- Croser Croan CLoseT RN F7TF.Tcwti WWE MA AAMAAAN Croser SS Ben Room 18-o% 11-0" * SECOND FLOOR PLAN- Wt definite pattern is followed, save perhaps some particular bond such as Flemish, English or Dutch. The only idea is to obtain a sense of extreme irregularity or texture, which in itself becomes tremen- dously appealing.. The projections of the ‘brick cast shadows on the wall surface. These shadows give what architects call a play of light and shade or decorative effect. Aside from common brick, laid skintle- fashion, you find salvage brick used in the same manner. What is meant by sal- vage brick? Brick selected from old buildings, being torn down. Many are weatherworn but still in excellent condi- tion, and when wsed in a skintled wall, produce original and colorful effects. What about the cost of a brick house? Manufacturers say that costs have been brought down until today, with certain types of wall construction, the brick house will not cost over six per cent more than a frame house. They also add that the moderately increased first cost for brick is soon offset through savings made in annual upkeep, such as painting, in- surance, etc. A word of advice-about selecting brick for your house. Don’t try to judge a finished wall by a few loose bricks. Re- member that the mortar joints are almost as important as the brick itself. So, if possible, select your brick from a group of wall panels. These are on display in most dealers’ offices. Try to picture your completed house. done in brick and ap- propriate mortar joints before you place your order. The house illustrated this month is a common-brick skintled job done uncom: monly well. The owner says the final cost was not more than $400-over and above frame construction. In this house a built-in garage opens onto a rear hall. The hall is a_ pivot around which radiate the service and living quarters of the house. A large living room is a feature. The adjoining sunporch adds more room to the living area. On the second floor there are two good-sized bedrooms and an abundance of closet space. You have here a small house of reasonable cost that departs suf- ficiently from standards to make it indi- vidual and of excellent resale value. PLAN BOOK FOR READERS A NEW BUNGALOW BOOK: Sixteen se- lected low-cost bungalows in popular styles, at prices ranging from $5,000 down to $2,000. Each house fully described and illustrated. Send ten cents in stamps to cover mailing.

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