Popular Mechanics 1929-04: Vol 51 Iss 4

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POPULAR MECHANICS MAGAZINE WRITTEN SO YOU CAN UNDERSTAND IT PERIODICAL ROOM GENERAL LIBRARY wey. OF MICH.

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We offer you 30,000 of the finest miles you year feel in every mile We announce the New Mobiloil—an oil so startling Under high speeds you will find, as our road test: in its performance that the superlative statements we _ have repeatedly shown, that this New Mobiloil stand: are ready to make about it are actually conservative. up better and consumes more slowly than other oils . . . and it is an established engineering fac that the oil which lasts longest and stands up best at high speed also lubricates best Neny speed. For example, when we say that with regular drain- ing and refilling, plus common-sense care, this New Mobiloil will keep the first-year feel in your new engine for at least 30,000 miles, the facts are that in Try this New Mobiloil. It will help save your a great many engines the New Mobiloilhaskept the good engine from growing old before its time. first-year feel for more than twice this distance. Mobiloil—the World’s Quality Oil—is made by the Repeated road and laboratory tests have proved Oldest and Largest Specialists in Lubrication. that use of this New Mobiloil commonly assures from 10% to 30% more power than other oils VACUUM OIL COMPANY oO generally sold for the same motor. Makers of high quality lubricants for all types of machinery the New iin Mobiloil Publish

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ad test: ] stand: n other ng fact up best od. ve your is time. e by the ANY chinery 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 aie 509-513 Little Collins Se. ISSUED MONTHLY SUBSCRIPTION: SINGLE COPY, 25 CENTS Send See anh bn pease, ee Genet, Cilte, and Matin, gut sen, postpaid - $2.50 To all other countries in the Postal Union - : ° ° e - 3.00 All subscriptions are discontinued at expiration. Sebeenaies ie an Sdeeclieneien adie, Entered as Second Class Matter Sept. 15, 1903, at the Post Office at Chicago, Illinois, ander Act of March 8rd, 1879. Entered as Second Class 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. 51 Contents for April, 1929 No. 4 Special Features i e , ..5 0; Mess 6 P4044 454404 nedeesnceedee’ a 546 The Great Sahara TreasureHunt sss... 554 The World’s Queerest Jobs ................ “ wnanae ia 562 Rocks That Fall from the Sky..................... . 570 The Center of the Universe......................... es 578 Saving All but the Squeaks dicated axes hes es 586 Where Men Defy Death ................................ . 594 The Wonder Metal... fan GEE RO ciated #99 603 14,000 Hours in the Air ..................... wha 610 ee” SS ree Rae es 619 The Bug Boarding House 625 “Signing Off”—Heroes of the sos........... Sele tds 645 Agriculture—forecast invasions of pests to protect Bridges—automobile toll, to link Oregon and Wash- crops 640 ington Airplanes Building Construction—add stilts to old eaens for all streamline flies at great speed 631 extra stories England builds secret plane . 609 Building Materials four thousand engines doomed to be junked 621 kill germs that eat stone 561 hot wire measures winds in tests 575 sea grass serves as insulator against sound and heat 561 plane rescues injured nun in Alaska 618 Busses—fuel oil replaces gasoline in 602 plane solves sea mystery in finding ship 560 Camera—automatic focusing possible for home-movie.. 640 where latest designs are tested 635 Cards (Playing)—holder fits on fingers 576 Archzology—ancient burial pit reveals royal splendor 636 Chemicals—boy discovers new explosive 577 Automobiles—‘“‘joy rider” for, is latest amusement 609 Coal—filters salvage coal dust floating on river 590 Automobiles—Accessories Coins—eagle’s feet on silver dollar right? 545 safety throttle for saves gas es 592 Color—magic effect of keeps steel coo 636 spring clip for valve tappet 636 Compass—sliding-beam promotes accuracy 592 valve spring tester helps save gasoline 599 Cotton—substitute for 619 Automobiles—Driving Crime automatic brake promotes safety . 584 revolver rack on auto dash aids police squad 552 distant switch starts auto 605 thief snared by powder sprinkled on purses 577 Automobiles—Lubrication—automatic oiler reaches all Curtains—tracing cloth for admits rays 569 parts of car 560 Dams, Boulder—America’s greatest reclamation project 622 Aviation Department Store—two million pennies a week used by 599 airport like country club 622 Drain Pipes—air gun to clean out 577 correction of article on “Women of the Air” in Earthquakes January 640 ship feels 553 navy airplane carriers 632 slightest tremors shown on new recorder 646 radio talk with Byrd plane sets wireless record 552 Education—stuttering child as bright as normal pupil 616 Birds—small, put out lights by short circuit 608 Electric Fixture—light cast from any angle by jointed 609 Blood—made with chemicals to help gas victims 615 Electric Plant—portable for light and power — 568 Boats and Boating Filling Station—water kept from gasoline by safety engine in extreme stern of new English speed boat 593 valve 634 inland harbor for yachts 545 Fire Fighting Outboard motor boat for shallow waters 628 freezing gas curbs fires gts secceesccens 590 xing—punching bag worn on head 630 skyscraper fire tests fighters’ skill ............. 602 [Continued on Page 4]

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[Contents—Continued] Fish ae ee fish supplies asin a8 Footrest—paper covered for shoe stores . Games—basketball played on table Volcanoes—predict eruptions by study of averages Wall—hollow, deadens sound more than Washing Machine—speed-shift, does better work aling—modern methods of ; ae Windmill “barn-door,”’ harnesses the desert winds Golf—nine-hole indoor game improves putting Zoo—model mountain for goats .... Grain—model elevator loads cars and boats ... in the form of a slender bar bed and serves as drier . Helium—plant “coldest Hotel—in form of boat House—three story of glass Household Devices Insects—as leprosy carriers .... Insulators—million-volt electric flash tests ——— gaining as inventors prec records Scammed for tower ... ’ Lock—chain, releases gas to foil thieves . Lubrication—fitting closes open oil hole .... Marble—red ink stains on removed with lime . Memorial—lights on churchyard cross Metals—aluminum mixed with gold aids dental work. AMATEUR MECHANICS 4 Automobiles —Lighting-—inatalling by backing ey Raatie, lisereeseaiee motor heat Automobiles—Tires—cover for tire Automobiles—Wheels—removing without a puller Boats and Boating anchor for a small outboard motor pleases youngsters preventing loss of outboard motor combination peng and sleeping bag Cellar—warning geal for low beam in Cleaning—dry, mixture . Door—simple holder for .... ishing—through the ice Flower Stand—made from barrel hoops Furniture—how to refinish your old Gate—hinge makes good latch Memorandum Pad—and holder Mirror—handy for inspectin Photographs—novel effects aluminum bottle caps float prevents skin on while boilin Milk Bottle—wood fiber for replaces g Moon—like volcanic ashes temperatures show Motor Bus—safety wheels for Motorcycle—run by rockets home movie and radio play are linked together polar bear proves good “‘actor” talking movies made in home Nursing Bottle—holder for fits on high chair .. Phonograph—cardboard makes sound box for Pliers—long for many uses 3 Power Plant—electric eyes replace men at .. — by outboard motor in talking movies. enlarging small negatives finder for photographs ... Plants—making transplanting easier . Putty—soldering iron removes Saws and Sawing—screw-slotting hacksaw blades Signs—novel for roadside pop stand Soldering—quickly made acid Stoves, Gasoline—“ethyl Trees—how to grow dwa -_ for Spanish cabinet helpful hints from experts all cannot be used in gg yl record on dictaphone speeds f Water Bag—substitute for .. Radio—Broadcasting—an experimental microphone Radio—Eliminator—new rectifier for pe Radio—Receiver—combination radio and phonograph ‘ Radio—Reception Acido—owab for applying curing noise in set g small sheets of . dudk-suindes farm arts of car that are seldom lubricated Automobiles—Painting—easy method of sandpapering Bookcase—making a modern Cement—strong, durable plaster-of-paris mixture Concrete—old broom used in breaking Drilling—simple tool for close Farming—time and labor saving kinks for the farmer Grain—box for fanning-mill screens and bags Horse—adjustable wooden ; : Joints, Wood—for the amateur Joists—nailing single-handed greater selectivity for the old set grounding of transformer cases eliminates hum checker operates from a.c. line .. ,coeetng unit for a.c. dining car without wheels serves as school ine half a block long - rays control train Stuanbentinn with steam oom ‘freezing Roads—rough roller for hard Robots—that walk and talk Safety Devices and Measures gate stops autos at rail crossings . lower lifeboat on track Searchlight—sends code by radio control . Shovel—mammoth electric snag built to break all preventing marks on work in reducing speed of Machine Parts—expanding and contracting circular Milling Cutters—clearing of Paints and Painting—rigging boatswain’s chair Skis—motor, at Swiss resort Stamp Collection—printer’s error adds value to ‘stamp. large size electric printer prints from wet negatives . Planer Bed—kink for Pushcart—load-balancing Putty—fire softens on sash Saws and Sawing—metal rod at an angle . Springs—compressing heavy T: pe Line—kink for using .. Windows—boxes anchored to cellar wall Wood—making plastic filler for Wrench—improvised ratchet double earpiece for allows two to listen .. loud speaker for leaves hands free roller skates speed service in exchange , Toothbrush—spring-motored for Traffic—two-level streets plann Transportation—all under three feet ride free in busses 593 Tricks—easy with handkerchief Bt aces Vision—new theory offered by Sir Oliver Lodge ieee 624 553 590 601 $91 630 “The “Mor intere “A ur “Like | from Exa THE ( by Cleme that give has learr birth ina of radio, : story—al Philosoph volume tl at our exp Clip an ring you MAN’s | yourself h Read it fr

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Full-Size Airplanes, Instead of Scale Models, May Be Tested at the Giant Wind Tunnel of the National Advisory Committee for Aeronautics, Langley Field, Va.—See Page 635

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ee eee Popular Mechanics Magazine REGISTERED IN U. S. PATENT OFFICE WRITTEN SO YOU CAN UNDERSTAND IT Vol. 51 APRIL, 1929 QUEER-looking device holds the spotlight at the army air corps’ experi- mental laboratories at Wright field, Day- ton, Ohio. For lack of a better name it has been called the “flying bathtub,” since some of the airmen compare it to a winged variety of the household article. The new invention, upon which Lieut. Albert I. Hegenberger, among others, has been working for over a year, was de- signed to take the place of what has, been known as one of the most curious devices man has invented in his efforts to rival the birds of the air—the Ruggles orienta- tor—which, placed upon the ground, is intended to give the student flyer the “feel” of a plane long before he attempts to maneuver a ship aloft. Made from the cockpit of a plane, it is suspended in three concentric rings. With increasing speed, the instructor, from his chair below, manipulates the plane into the desired upside-down or sideways po- sition. Immediately thereafter, it is the student’s job to maneuver the machine back again to normal. The judgment with which he does so determines in large part the rating he receives, or rather has received, since the device is now virtu- ally obsolete. 529

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530 POPULAR The flying bathtub, or “primer plane” as some call it, is similar in size to the Ruggles apparatus, but the new device goes many steps beyond it. The tub contains both a propeller and an engine, and can therefore simulate to an amazing degree every one of the main maneuvers a real plane can execute. It consists of a small fuselage body with rudder, elevator and aileron, or movable flat foil that serves to keep the ship from wobbling from side to side. These sur- faces are fully controlled by the operation of standard airplane apparatus installed in the fuselage body, and the plane itself is sent flying by means of a tractor pro- peller driven by a fifteen-horsepower elec- tric motor, mounted forward in the fuse- lage of the bathtub in the same fashion as is the engine in the actual airplane. The plane itself is mounted in a double- tripod frame, twenty feet high, this height offering a sense of disassociation from the ground besides a’ certain amount of hori- zon perspective. While the student be- comes familiar with the features of flying that at first are apt to be confusing—the blast of air, the noise of the propeller and MECHANICS the rocking, tipping motions of flight—he also is becoming used to the response of actual flying controls. With his feet on the rudder bar and control stick in hand, the student flyer can cause the primer plane to assume any po- sition a plane can take in actual flight and gain the feel of the controls and the dif- ferent movements of the ship with the as- surance of safety while he is learning. An instrument board, equipped with compass, clock, air-speed indicator, inclinometer, bank-and-turn indicator, and the rest of the standard flight instruments, enables him to form the habit of automatic refer- ence to the board in all attitudes of flight. It is pointed out that, from the instruc- tor’s point of view, the device will be ex- tremely helpful. He will be able to ob- serve closely the student’s reactions, and his natural adapta- bility to flying. If he notes some fault in manipulation of con- trols or wishes to demonstrate a cer- tain point, then he may stop the plane at any time and give the student advice. Then again, by —— A Steep Left Spiral, Top, and a Glide, Bottom; in the Center, the Nine Pens of the Poppen Recorder, Which Automatically Charts the Results —- oe fo Ba - om ee eee Ok oe owe ae as 46 or.

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~ SS the hich POPULAR placing a hood over the student’s head, shutting off the horizon, sky and ground, blind flying may be taught by the process of having the student attempt to regain, from various attitudes, normal position by simply referring to his instruments. MOUNTAIN RANGES UNDER SEA FOUND BY ECHOES Echoes have just aided in two important marine discoveries that may help explain an ocean mystery, the origin of the Hum- boldt current. By firing detonating shells from a twenty-foot brass shotgun and de- termining the time the echoes took to re- turn from the floor of the sea, scientists on board the non-magnetic yacht “Car- negie” have found two new ranges of mountains under the ocean. One is more than a mile high above the sea floor and 100 miles off the coast of Ecuador. The other rises to a height of 9,750 feet and runs northwest and southeast, 400 miles to the north of Juan Fernandez is- land. It is believed that this range may be a contributing cause to the Humboldt current and may also be a remnant of the sunken lands whence sprang the myste- rious Easter Island civilization. ROTARY PLOW ON MOTOR TRUCK KEEPS SNOW FROM ROADS Roads around Leadville, Colo., were kept free from snow last winter by means of a rotary plow at the head of a ten-ton, four- wheel-drive motor truck. The blades of the plow were so adjusted that the snow was drawn inward MECHANICS 531 Model Plane with Double Propeller That Is Expected to Increase Power and Give Steadier Flight TWIN PROPELLERS ADD POWER AND STEADY PLANE Increased power for the airplane and steadier flying are said to be achieved with a double propeller which has been dem- onstrated in a small model. The two are placed within a few inches of each other and, in operation, are reported to. produce a gyroscopic effect. Slots in the hubs per- mit changing the pitch of the blades. TON WOULD GO IN A MATCH BOX ON DISTANT STAR So dense is the material on a companion star of Sirius that a match box full of it would weigh a ton. and forced out through an inclined spout at the top. The truck is steered from either end, has a sheltered place for the two operators, with a small coal- burning stove to furnish heat, and when there is no snow, is used for hauling road grad- It is 6,000 times as dense as water. This is one of the inter- esting facts revealed by the new tele- scopes. The 100- inch reflector at Mt. Wilson observatory is to be surpassed in a few years, it has been announced, by one with a 200-inch mirror and a tube probably not less ers and other high- Way units. Motor Truck with Rotary Plow That Has Kept Colo tado Roads Free of Snow than eighty feet in length,

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532 POPULAR Buoy on Swimmer’s Back Contains a Line and Floats, Should Wearer Sink, to Aid in Rescuing Him BUOY WORN BY SWIMMER AIDS IN RESCUES So that life-savers quickly may be able to locate swimmers who have become sub- merged, a small aluminum float, which re- mains on the surface when the body sinks, has been introduced. It is attached by strong fishing line and is so arranged that it is released and the line unwound as the wearer sinks. The buoy is painted a bril- liant color to increase its visibility, and the line can be used to pull the body up. HARVESTER FOR SMALL FARM CUTS REAPING COST Harvesters that cut and thresh grain in one operation, until recently, have been practical only MECHANICS fifty cents an acre. The machine is pulled by a tractor and operated by a gasoline motor. It is compactly and solidly built, the grain being collected in a large bin at the top, from which it can be sacked or dumped in wagons. On larger farms, two or more of these outfits can be used at one time. The average farm tractor is able to pull two of them. EXPERT BELIEVES OLD MASTER WORKED FROM REFLECTION Study of the work of old Dutch painters, including Vermeer, of Delft, who lived between 1632 and 1675, has convinced Mr. R. H. Wilenski, a noted English expert, that they worked, at least in some in- stances, from reflections in mirrors. One of Vermeer’s paintings, “The Love Let- ter,” which hangs in the Rijks Museum, Amsterdam, has been supposed to be a picture of two models as seen through a doorway. Wilenski, however, points out that there is no sign of door and frame, and certain peculiarities of perspective in the chair on the right and the wall on the left indicate it may have been made from a reflected image. A diagram on the op- posite page shows how such a picture could be painted. With such an arrange- ment Vermeer could paint a composite picture of the two models, and of objects which were placed behind him. The ar- rangement of the two reflecting mirrors would permit the artist to compose a pic- ture in one plane before actually starting to paint, by merely moving the objects about until a suitable composition was found. A reducing glass fitted with cross threads also would allow him to auto- matically scale on large farms. Now, an outfit suitable for the small grower has been intro- duced which enables him to cut and thresh an acre of grain in less than twenty-five minutes and at the proportions. Gerard Dore used such a de- vice. Vermeer’s work is noted for the smooth- ness of his tech- nique and the transparent shadows which would result from reflection an average cost of less than Harvester-Thresher for the Smaller Grain Grower; It Cuts and Threshes an Acre in About Half an Hour of interfering light beams.

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POPULAR MECHANICS 533 DID VERMEER PAINT PICTURES BY REFLECTION? Puwnes ie © 8. W. Clatworthy Sketch, Showing How Noted Dutch Artist May Have Produced His Painting ‘The Love Letter,” by Work- ing from an Image Reflected into a Mirror at His Side

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534 Cord Holder as Used When Iron Is in Operation, and Method of Attaching It to the Board HOLDER FOR IRONING CORD PREVENTS ACCIDENTS Easily adjusted to almost any position, a flexible support for the cord that sup- plies the electric iron with current, has been introduced to help lengthen the life of the cord and to prevent accidents such as may arise from pulling the iron off the board or damaging the cord when it be- comes entangled with other objects. The holder keeps the connection out of the way at all times and, when not in use, folds into a small space. SCRUBBING EARS TOO HARD MAY CAUSE INJURY Here is good news for boys who object to the vigorous ear scrubbing their mothers sometimes command. According to New York medical authorities, there is danger in the process, for soapsuds and other foreign substances may be forced into the exterior auditory canal or the skin of the ear may be injured. They point out that the ear is a delicate organ and that nothing should be placed in it POPULAR MECHANICS in the form of a medicine except under the direction of a physician. A slight injury may develop into serious trouble, they say. In washing children’s ears great care should be exercised. A soft cloth should be used for the operation. Another dan- ger lies in blowing the nose too vigorously, because secretions may be carried into the middle ear, resulting in an infection. METAL COATING ON FABRICS TO AID AVIATION Lighter and stronger airplanes are seen as a possibility in the development of a process for coating paper, silk, wood and other materials with metal by an electro- chemical method. Experts point out that, if the system proves successful, planes with the strength of metal could be made from much lighter materials. CHURCH IS RAISED ON STILTS FOR FILLING GULCH So that the gulch in which it was lo- cated could be filled to make a level street, a frame church in- Los Angeles was re- cently raised twenty-four feet on a scaf- folding. The structure was twenty-four by seventy feet and was elevated without mishap. Dirt was piled in around the tim- bers and, in a short time, the church again was resting on solid ground. Where a Church Went Skyward on Stilts; Frame Structure Raised for Filling In, to Make Street Level

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eEeV7"_—"—_T) ame vel POPULAR PLANE RESCUES WOMEN FROM BESIEGED CITY Women and children were taken safely from a besieged le- gation on the Indian frontier re- cently during a rebel uprising, when armed soldiers in a troop- carrying airplane went to their rescue. Infantrymen, in con- stant touch with forts by radio, guarded the refugees as they were taken to safety. The plane was of a special army type with a top speed of more than 100 Courtesy Vickers, Ltd MECHANICS 535 Interior and Exterior Views of the Big Transport Airplane Used in Rescuing Women and Children from the Indian Frontier; Twenty Passengers Can Ride in One Plane miles an hour and a cruising radius of 400 miles. A group of five such ships can carry 100 soldiers and quickly reach dis- tricts where trouble has sprung up. MORE USES FOR WOOD NEEDED TO REDUCE WASTE To effect greater conservation, there should be more uses for wood, according to Dr. Julius Klein, of the department of commerce. He explains that a more effi- cient utilization of the material would make it more profitable for growers to plant and raise trees. At the present time, only the choicest parts of the tree are used and most of the rest is wasted or at least not used to best advantage. Chemical processing of wood, the manu- facture of plywood and end-matching of lumber are among the methods that have been developed along the line of more thorough utilization. Doctor Klein urges consumers to buy more short lumber whenever possible. Large quantities of lumber in this form are burned up each year because the mills cannot sell it. A further saving is realized in end-matched flooring. End-matched joints meet any- where, on or between the joists or other supports so that less cutting is necessary. Development of processes for obtaining valuable by-products from wood, such as synthetic camphor, artificial silk and wood alcohol will also promote conservation and encourage tree raising, Doctor Klein points out.

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Floating in Air, Restrained Only by Celluloid Guides, Magnet Bar Conquers Gravity through Magnetic Repulsion A NEW form of geometry, providing equations which may furnish proof that there is only one substance in the universe, has been developed by Prof. Al- bert Einstein. Fitting in between the Euclidean geometry, familiar to every school boy, and the Riemannian geome- try used by Dr. Einstein in working out his famous theory of relativity, the new mathematical laws which he now proposes go a long step farther in extending the natural results of relativity. For his new equations are based on the assumption that gravitation and electricity are the same thing. That heat and light are related was discovered early in the his- tory of mankind. That heat and energy were related was discovered next—a dis- covery that was for a long time doubted, though now every form of engine is based on it. One by one science proved the in- 536 insteins | atest terrelation of light, heat, energy, matter, space, time, gravitation and elec- tricity, until only one fac- tor was left—the specific relationship of the last two. And, if the new Ein- stein equations stand the test of scientists, it will be proved they are the same thing. The new geometry, while it seeks to reduce all physics to one law, leaves one problem to be solved, and its success probably depends on fur- ther development to bring the theory of atoms within its scope. Doctor Einstein took a step in that direction in 1927 in two papers in which he attempted to define the laws of motion of atomic particles in the gravita- tional field. When the theory of rela- tivity was announced it was stated not more than twelve men in all the world were suff- ciently educated in higher mathematics to fully interpret it. Like its predecessor, the new theory—six brief pages represent- ing ten years’ work—is full of equations that only a few scientists will be able to interpret. But, while the theory itself is almost incomprehensible to the layman, it opens a field for fascinating speculation. Since it is possible now to insulate against elec- tricity, it follows that, if electromagnet- ism and gravitation are the same thing, it may be possible some day to insulate against gravity. If that ever comes to pass, motorless aircraft may ride the skies, people may step out of skyscraper win- dows without falling to the ground, and a trip to the moon becomes theoretically the Cobalt-Steel 1]

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Is This the Airship of the Future? A Motorless Craft Flying through Space because Insulated against Gravity ; Einstein’s New Theory Opens This Field to Speculation possible. Those are some of the avenues of speculation suggested by Dr. H. H. Sledon, head of the department of physics at New York University. Since Newton first proposed the law of gravity—based, according to the story, which probably is not true, on the falling of an apple which struck him while he slept beneath the tree—science has been Seeking some way of upsetting that natural law. The gravitational theory, as it was developed, assigned all movement in the universe to the attraction of masses. he planets were held in their courses by the attraction of the sun, and their orbits were made to deviate from a circular path by the mutual attraction between them. Then Einstein developed the theory, which is now elaborated, that instead of each body, through its mass, causing everywhere in space a certain effect known as gravitation, the latter effect manifests itself only in the immediate surroundings of the body in its gravitational field or area. That, according to Dr. Bruno Bor- chardt, of the Prussian Academy of Science, was the chief development of the theory of relativity. According to this theory, he says, “each body with its grav- itational area acts on space in such man- ner as to shape or reshape it. In other words, space can no longer, as before, be 537

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POPULAR MECHANICS MT. BALDY LOOKOUT CONCAVE af MIRROR 5 ¢ LIGHT REFLASHES BACK TO MT. WILSON -_—- + OBSERVATORY. Einstein’s Work Has Been Closely Connected, Since the Original Theory of Relativity, with the Measure- ment of the Speed of Light by Prof. A. A Michelson, of Chicago University considered as something absolute, such as time used to be regarded by us.” The confirmation of this theory left two general problems unsolved, according to Dr. L. L. Whythe, the British physicist. The first was its extension to include the phenomena of electromagnetism, and the second was the correlation of a continuous “space-time field” with the facts of the atom theory. Doctor Einstein’s latest achieve- ment probably is the best fusion of elec- tromagnetism and gravitation that can be accomplished without considering atomic- ity, he adds. Eventually it may be nec- essary to invent still another system of mathematics to take the atoms into the fold and finally reduce all physics to a single law. Recent theoretical advances in atomic physics may make this possible within a short time. Science has known for a long time that the repulsive force of magnetism when two magnets were placed parallel was theoretically great enough to overcome gravity, provided magnets of sufficient strength could be used. Recently engi- neers of the Bell Telephone laboratories and the Western Electric company—the manufacturing unit of the Bell system— found that a cobalt-steel alloy, invented some years ago by a Japanese metallurgist and now widely used in telephone parts, had magnetic strength to do just this. When one of the bar magnets made from this alloy is placed above a similar bar, and constrained by guides to that position, the repulsive force is so great that one bar will be kept floating in the air, unsupported by any visible force. The repulsive force exerted between the two magnets is practically equal to the gravi- tational force on a single magnet, so that one overcomes gravity. As the repulsive force varies inversely as the square of the distance, it is possible to calculate the mag- net strength needed to support a given weight at any given distance. Announcement of this experiment was confused in the public mind with the use of permalloy, a new magnetic alloy made of nickel and iron, and used as a winding around the copper core of recent trans- atlantic telegraph cables. Neither of the magnets used in the floating-bar experi- ment is of permalloy, and, in fact, the two materials have exactly opposite charac- teristics. The cobalt-steel is used for the magnet bars because it will hold a very high magnetizing charge. The permalloy, on the other hand, gets its name from the fact that, after a specially invented heat treatment, it develops high initial perme- ability, that is, remarkable capability of be- ing magnetized by very weak forces, while for strong magnetizing forces it is not as good as plain iron. Weak magnetizing forces are commonly met in all forms of communication, wire, radio and submarine. The first use of the new permalloy, therefore, was as a wind- ing for submarine-telegraph cable. Sev- eral such cables have been “loaded” by this method with permalloy tape, and, by virtue of the higher inductance they offer _- ae id: cu ce pe cli dr: be to in to as de alc uti for for we rec fly SO- su po

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w F oe »e- aly ire, the nd- ev- by by fer POPULAR MECHANICS 539 aie nin scl 22” SPHERICA:. CONCAVE MIRROR LIGHT ORIGINATES IN SPERRY ARC LAMP HERE APERTURE T HROUGH S eaprncne tiGHT 1S TRANS- oe _ MITTED INTO THE. a _ LABRATORY bei hi RH STF ST 3 The Michelson Experiments Were Checked Again This Winter with This Apparatus, Installed on Mt. Wilson and Mt. Baldy, Two California Peaks Twenty-One Miles Apart to the weak telegraphic currents, thus off- setting the capacity from cable conductor to the sheath or sea water, they permit the transmission of a wider range of sig- nal frequencies, and hence a higher speed of telegraph operation. Such cables have about five times the message capacity of the old-style cable. The permalloy also is being used to a wide extent for parts of new telephones and telephone apparatus, wherever its properties prove useful. Because magnetism, as represented by the deflection of the compass needle, is manifest everywhere on the earth, the idea of harnessing the earth’s magnetic currents is one that has been proposed for centuries. One of the oldest forms of perpetual-motion scheme proposed an in- cline up which a ball weight should be drawn by a magnet placed at the top. Just before the ball reached the magnet it was to fall through a trap, roll down a second incline, and return to the starting point, to repeat the performance. As far back as 1579, Bishop Wilkins described such a device in his book “Mathematical Magick,” along with several others, all designed to utilize the earth’s magnetic force. Science discovered long ago that that force isn’t strong enough to be utilized for anything much harder than turning a well-balanced compass needle, though, as recently as a year ago, two prominent flyers w ere reported to be interested ina so-called “magnetic motor” which was Supposed to turn magnetic forces into power. Another suggestion offered to the war department not long ago was that the nose of an aerial bomb should be mag- netized so that the attraction of the mass of steel in an enemy warship would draw the bomb to the mark regardless of how it might be aimed when dropped. As the most powerful electromagnets made have a lifting radius limited to inches, the idea of using magnetism, so far as it is now understood, is certainly impractical. The Ejinsten theory, however, if it can be developed some day into a workable formula, may revolutionize all present-day accepted notions of what is possible. Ra- dio, to begin with, was merely a scientific theory. The atomic theory itself was only an interesting speculation to begin with, but as a result of its classification of the ninety-two elements which it provides for, several of the unknown ones, such as illi- nium and niobium, have been discovered, and, in fact, only two of the ninety-two, both of them probably somewhat ra- dioactive chemicals, remain to be found. The atomic theory is closely linked with Einstein’s theory of only one substance in all the universe, for it is based on the as- sumption that the only difference between the known elements lies in the number of electrons revolving around the proton which forms the center of each atom of the material. In other words, the atom is a little universe somewhat like our own, with a proton in the center in place of a sun, and electrons revolving around it in place of planets.

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540 POPULAR MECHANICS STRENGTH TESTS ON BRIDGE TO AVOID ACCIDENTS Accurate methods of testing bridges, to discover those that are unsafe, were dem- onstrated recently by engineers of the bu- reau of public roads who used special in- struments in determining the strength and capacity of the Yadkin river bridge in North Carolina. The structure is a quarter of a mile long, has seventeen spans, three of which are 146 feet in length, and had been abandoned because of the building of a dam in the river. Under the arch of one of the longest spans, a scaffolding was “Third Degree” Methods in Testing a Con- crete Bridge; Using Stress-Measuring In- struments, and View of the Tanks on Span for a Weight Test erected for instruments, to record strains and stresses from two tanks filled with water and placed so that their weight could be va- ried and their location changed. First, the engineers cut through the floor to destroy the continuity of the concrete slab for a test of its strength. Next, various instruments were placed so as to record the amount of strain and to give data as to just how much the con- crete span varied under the weight of the tanks. A clinometer was used to measure the change in the position of the arch rib. This instrument is similar to a carpenters’ level. Changes in the length of the rib were measured with an instrument elec- trically connected to a central station we Pars Fa

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POPULAR MECHANICS 541 where the readings were made. By means of storage batteries, the instruments gave automatic rec- ords. Electrical methods were also used to gauge the change in the position of the arch rib. The bridge did not collapse under the heaviest load, but cracks devel- oped which showed that it was unsafe. PARACHUTE HAS METAL RIBS TO AID IN LANDING Several interesting features are combined in a marine parachute which has been devised and tested by a Chicago man. It is attached to the side of the plane, is released by pulling a cord and is con- nected by a strong rigging to a sling harness which the aviator wears instead of the usual para- chute bundle. At the instant of release, the parachute opens quickly somewhat like an um- brella. It has twelve ribs of a strong, light metal and is so ad- justed that it will not capsize and will remain afloat and open even if the jumper should alight on water, thus serving as a raft. The rig can be quickly closed up again for another jump, weighs less than twenty-five pounds and is so arranged that it is released from a plane flying at any angle. Parachute as It Is Carried on Side of Fuselage; It Is Fastened to Pilot by Line and Opens When Released View of the Nave of the Cathedral of St. John the Divine, Now under Construction in New York City HUGE CATHEDRAL IN NEW YORK TO BE THIRD LARGEST On the basis of ground surface covered, the cathedral of St. John the Divine, now under construction in New York city, will be the third largest place of worship in the world. It will occupy more than 109,000 square feet. In exterior length, it will be second among the world’s great churches. One of its most remarkable features is to be the nave which is ninety- six feet wide. The prevailing style of architecture is what is known as thir- teenth-century French and was developed by medieval builders who erected the Notre Dame cathedral, and those of Amiens and Rheims. Sculptors and carvers are closely following the designs of the sculptors of old in the details of the decorations. @Whales to the approximate number of 10,000 constitute the annual catch in ant- arctic waters.

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POPULAR Carbon Inserter Adjusted to the Typewriter; It Saves Handling the Sheets Separately CARBON ADJUSTER FOR TYPIST SAVES OFFICE TIME Sheets of carbon are adjusted between papers in typing by a machine which is said to save considerable time and trou- ble. It is so placed that it does not inter- fere with the operation of the machine. PORTABLE TRAP FOR SHOOTING AIDS OUTDOOR SPORT Pleasures of trapshooting may now be enjoyed almost anywhere with the aid of a portable trap that MECHANICS MINERS HARNESS SURF TO GET GOLD FROM SEA FLOOR In 1897, when gold was discovered in the sands off Nome, Alaska, there began a long series of interesting attempts at sub- marine placer mining, for quantities of gold were known to be farther out from the shore. Today, the beach is strewn with the wreckage of the various machines that were used, broken dredge hulls, steam and gasoline engines, and curious scoops that were meant to harvest the golden grains from the tides. The place would be a junkman’s paradise, were it not for the facts that the freight rate to market is $30 a ton and that a team of horses rents for $40 aday. However, with pans and surf washers, considerable gold is still being taken from the sands. The surf washer is essentially a short sluice box, so arranged that the surf will wash the sands up into it and the particles of gold are collected by mercury. Sixty miles south of Nome, three miners are operat- ing a development where they have found a pay streak below the line of the-surf’s wash. In the winter, they dig down through the ice and into the bedrock, thawing the way with steam. Before spring, they dig out folds up for easy carrying in motor car, boat or pack saddle. It holds forty-three birds which are fed auto- matically from the magazine against a spring that hurls them eighty-five to 100 feet at a pull on the release cord. all the pay dirt they can and dump it above the line of wash, for later treatment with pans and a surf washer to collect the gold. They have operated this mine from un- der the ice for thirty years. The plant lies at the Direction, speed of flight and angle are controlled at will, and the trap is quickly made ready for use simply by unfolding it and an- choring it with a special pin. The trap weighs less than ten pounds and is built to give long service. Trap Gun in Use on Board Boat, and Close View, Showing the Magazine and Cord Trip foot of the Council mountains, a range where many broken bodies of quartz have been found. ' When exposed to the frost, these quartz fields become free-milling ore, and for this reason it is possible for the waves to help ex- tract the gold. wl Sey FF —_ isn oe

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POPULAR MECHANICS 543 TRAINING NEW GERMAN ARMY TO FIGHT ON SKIS - site| Soldiers in the Reichswehr’s Sev- Ss — tas” enth Regiment, Picked for Patrol : . Duty in the Mountains of South- n — ern Germany, Are Trained to Fight on Skis, Following the Practice in Several Other Euro- ean Armies, Including the Ital- ian, Swiss, Norwegian and Swed- ish; in Night Drills, They Carry Ly Torches to Guide Them through the Snow-Covered Woods; the Runners Gliding over the Snow if Permit Much Faster Troop Movements Than Are Possible fT Even on Bare Ground Afoot 1s er EES ed or

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544 POPULAR MECHANICS NEEDLE TESTS OIL PAINTINGS FOR FRAUDS By means of a small hypodermic syringe, an eastern chemist takes samples of paint from old oil paintings for analysis, His research reveals the chemical nature of the samples and thus gives a clue as to the approxi- mate age of the painting and its author, for dif- ferent artists made the same colors in different ways, and the paints of Utilizing the Tides to Build a Bridge; Floating Big Span into Position for Structure across San Francisco Bay “MOON POWER?” IS HARNESSED IN BUILDING BRIDGE Engineers indirectly utilized the force of attraction from the moon in installing a 303-foot span of the highway bridge over the deep-water channel of San Francisco bay. Taking advantage of the high tide, the span, weighing 613 tons, was towed into place and slowly carried into the proper position as the tides receded. The bridge is more than seven miles long. JOINT RAIL AND BUS SERVICE TO SIMPLIFY TRAVEL Joint rail and bus service is planned by the Pennsylvania railroad on the same principle as its combination facilities by trains and airplanes. Passengers will be offered the option of making their jour- neys partly by rail and partly by bus, using sleeping cars at night and busses for all or part of the journey by day. The service is expected to be extended until, in certain areas, busses may take the place of branch- line trains or others where traffic is light and until through tickets, covering joint rail and bus journeys, will be sold over certain routes. The innovation will pro- mote the efficiency of bus lines as feeders to the rail system, officials predict. @Raising rabbits is becoming an impor- tant industry in the southwest. various ages were of dif- ferent chemical combina- tions. The needle of the syringe removes a tiny cylinder of paint without mutilating the subject and en- ables the examiner to determine the qual- ity of the different layers of paint, an im- portant point when a new subject has been superimposed upon a painting. ELECTRIC ARC SOLDERING IRON USES LITTLE CURRENT Economy of current and elimination of the usual wire heating element, are fea- tures of an electric-arc soldering iron which has interchangeable tips for many purposes. Only intermittent use of the current is necessary, as heat is rapidly gen- Typical Uses of the Electric Soldering Iron, and a Close View to Show the Heat Control erated through carbons that form an arc at the end of the tool. A thumb control in the handle permits easy regulation. Za

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ny *Ti- Slose arc trol POPULAR MECHANICS 545 | Yacht Harbor in City’s Residential District Also Serves as Display and Sales Station; Craft in Storage at Los Angeles Yard Where Prospective Customers Can Inspect Boats INLAND HARBOR FOR YACHTS SERVES AS SALESROOM In the midst of the residential section of Los Angeles, is an inland harbor for small yachts and other pleasure craft. 3esides providing safe and convenient storage for the boats, the place also serves as a display and salesroom. EAGLE’S FEET ON COIN RIGHT? WRONG, SCIENTIST SAYS Capt. C. W. R. Knight, British naturalist, who has taken motion pictures of eagles in flight, this is wrong. He declares that the bird allows its feet to trail only when it is taking off for a flight. DOUBLE EARPIECE FOR PHONE ALLOWS TWO TO LISTEN Two persons may listen at the telephone at the same time or one may use both ears with the aid of an earpiece attach- ment which When an eagle flies, does it tuck its feet un- der its breast or does it let them trail behind? The question has been asked before, but has come to the front again in considering the eagle design on our silver quar- ter dollars and twenty-dollar gold pieces. The bird is shown with its feet trailing According to slips over the receiver. It leaves one hand free, can be ad- justed or taken off in a few sec- onds and is said to be a benefit to the hearing. The unit can be carried in the pocket. Of course only one of the lis- teners can use transmitter, but this is usually no drawback. The Attachment in Actual Use and a Close View

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By LELAND S. JAMIESON WO STUDENT pilots of the army air corps advanced flying school walked from the office of the “pursuit stage” toward two airplanes on the flying line. On the way, they compared their watches. “T’ll meet you over Mitchell lake at 5,000 feet,” one of them suggested. “Better make it ten-thirty —my motor’s got a blown valve and I can’t climb very fast.” “How’re you going to whip me in a combat with a . blown valve?” the other scoffed. “Don’t worry. I did it yesterday, and she was blowing then.” “Yeah, you got the drop on me yesterday by starting the fight out of a dive. You come in straight today, at cruising speed, or I'll pull out on you and there won't be any fight.” “Five thousand—at ten-thirty. Let’s go.” Both men swung into their parachute harness and climbed into the cockpits of their planes. They spent a few moments inspecting the curious-looking black objects which nestled against the cowling in front of the planes’ windshields—their camera guns— then waved the blocks away and taxied out into the flying field. Streaking away in front of fan-shaped clouds of dust, they took off and climbed leisurely into the cloud- flecked blue. 546 PQ , _ aT, i ’ I SOS (EE Ae \\) T way Sep; sha ally eacl “spi mile

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w 4a we hws 2 ae 21 ee —_ JME. i \ Wiss b heir iich y in yud- Ten minutes later, at 5,000 feet, they waved to each other, circled away and separated by a mile or more, then cut sharply and flew almost head-on. Gradu- ally each man eased his throttle forward; each ship picked up speed until it was “spanking” its way through the air at 140 miles an hour. Each pilot gripped the Student Gunners on the Machine-Gun Range at Brooks Field, Tex., Shooting at Moving-Airplane Targets machine-gun control on his stick and squinted along the top of the fu- selage at his opponent; the two planes passed each other, and instantly each man eased back on his stick and whipped his plane up and around. The “dog fight” was on. One ship was Superior to the other in climbing ability, and gradually its pilot forced it around un- til it was upon the other’s “tail.” Slowly “feeling” his controls to get the maximum perform- ance from his plane, he lined his sights upon his opponent—and pulled the trigger. The camera gun, actuated by a spring mechanism, began to “shoot,” taking pictures at the rate of 100 a min- ute, photographing the area in front of the sights, where bullets, had they been fired, would have gone. The target plane slipped across the sights; it pulled up into the cross hairs; if machine guns rather than a camera had been used, it would have been shot down. During the World War pilots were 547

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POPULAR MECHANICS Camera “Gun” Mounted on a Lewis Machine Gun, and Some of Its Pictures; the Plane, the Target Shows, Was “Led” to Allow for Deflection taught to shoot guns in the air by the use of small, captive balloons as targets. But the disadvantages of that system were manifold. An uninhabited area of con- siderable size was needed, to avoid the risk of wounding people on the ground; nor was it uncommon for the uninitiated embryo pilot to collide with his target balloon, which, in the days before para- chutes were used, was practically always fatal. And having no movement of its own, the balloon presented a target much different from a darting enemy airplane. As early as 1917, efforts were made to develop a camera that could take the place of an actual machine gun in training, and the combined efforts of the Eastman cor- poration and the air service produced what is now known as a camera gun. Mounted on an airplane, it furnishes a complete and accurate record of each pi- lot’s marksmanship. By means of an in- genious mirror in the latest types of cam- era guns, the exact second of the exposure or shot is superimposed upon the finished print, thus forestalling any argument be- tween combating students as to which one fired the first “fatal” shot. Later a method of giving student pilots machine-gun training on the ground was developed. In firing upon a moving ob- ject, a serious error in aim is encountered by the novice. At first, he aims his gun directly at the flying ship and fires, but by the time his bullet has been hurled from the muzzle of his gun to the target, the plane at which he is shooting has moved forward several feet, with the re- sult that the bullet passes well to its rear. A wooden frame, built very much like a |

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POPULAR MECHANICS Students, Seated in the Balcony, Observing a Battle Field Below; the Peculiar Figures in the Lower Right-Hand Cor- ner Are Ground Panels, by Which the Instructor Signals to the Flyers in the Air; a Battery of Four Guns Is Stationed in the Left Center of the Picture, Just to the Left of One of the Diagonal Roads; Below, Bombs in Their Racks beneath a Big Bombing Plane

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the skeleton of an. airplane fuselage, and containing a full set of controls, was made, and on this a gun mount was placed. The gun, being fastened securely to the frame, was moved when the controls were moved, and thus the final devel- opment in machine- gun training on the ground was achieved. The stu- dent, to aim his gun at a given target, pushes on his rudder and control stick until his sights point at the object, then he presses his trigger on the control column and the gun fires. But even this development was not ex- actly what was wanted, because until that time no targets other than the customary “bull and ring” type had been devised, and these, of course, offered no movement by which the student gunner could get train- ing in deflection shooting. A new target was invented: A toy airplane that was at- tached by two eyelets to a movable wire, and this wire was pulled over a series of pulleys in such a manner that the plane traveled across the target butt in front of the gunner. Firing at a point-blank range of fifty feet, a target speed of seven and a half feet a second was the equivalent POPULAR MECHANICS of actually firing, at a range of 200 yards, at an enemy plane traveling at sixty miles an hour. A more recent development in the art of synthetic-warfare training is the min- iature range. Here, under the supervision of a specially trained instructor, students are given all the practical problems which they will encounter in dropping bombs from great altitudes, and in co-operating with artillery units in the adjustment of artillery fire. A model landscape, built to scale from aerial mosaics of the terrain it represents, is used in giving ar- tillery-adjustment training. Each stu- dent is equipped with a pair of ear- phones and a buz- zer, and a radio key which connects di- rectly to the ear- phones of the in- structor. Seated in a high gallery over- looking the land- scape, each man watches for the flashes of light that represent the im- pact of artillery shells, and when these flashes come, corrections are Brooks Students Firing Camera Guns at a Real Plane; One of the Cameras, Center, and, Bottom, Machine-Gun Mounts on a Plane

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ie; un POPULAR MECHANICS 551 Student at Brooks Plotting the Course of a Bomber over the Camera Obscura; the Training of a Fighting Flyer Includes Many Things besides Pilotimg an Airplane made immediately and a report of error is made to the instructor. The instructor calls to the assembled students: “Bracket adjustment”—one type of artillery fire. “Lieutenant Black, make the corrections after the battery is fired.” Immediately, working at a switchboard, the instructor’s assistant snaps four switches down, then presses a button, and in four different spots upon the toy land- scape a flash of light appears. Over 300 tiny electric-light bulbs are placed at points under the canvas of the model terrain, and over 300 different com- binations of “bursts” are possible, bring- ing into play practically every conceivable error in.actual artillery firing. To Capt. S. R. Stribling, of the ordnance department, belongs the credit for solving the problem of training for heavy bomb- ing planes. He built a traveling carpet, representing the earth, stationed his bombers in a loft directly above the carpet, and above each is a bomb sight. The bombardier sits at his sight, determines the rate of air speed by the velocity of the Carpet’s movement, sights upon his tar- get, and at the proper moment pulls his bomb release. Instead of a bomb falling to the target, however, the pulling of the release starts a stop watch, and the instructor, follow- ing the movement of the second hand, knows how long it will take the imaginary bomb to drop to the ground. Thus, if the bombing is being done, imaginarily, from 5,000 feet, the bomb will strike the ground seventeen and one-half seconds after it is released, and at that moment the instructor flashes a light at the point where the bomb would have struck. Another ingenious device for giving bombing practice is the camera obscura. In practicing camera-obscura work, the pilot approaches the target in the same manner as when actually bombing, but at the moment at which the bomb would ordi- narily be dropped, the bombardier flashes out a signal by radio to the instructor in the hut where the camera is located. In reality, this camera is nothing more than a rough lens, through which the image of the plane is cast upon a plotting table. At the signal from the bombardier, the instructor plots the path of the plane’s shadow across the board, being able to grade the team in the plane, first by the time at which the bomb was supposedly dropped, and second by the straightness of the ship’s path above the camera.

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POPULAR MECHANICS meter mark and picked up “WFC,” the “Stars and Stripes’” call. “Go ahead,” he flashed back. An instant after his dot and dash “O. K.” from the Times station had sped across the equator and far to the frozen south, back came Han- son’s dispatch ending with the cheerful words, “sincere regards to your- self and the naval re- search laboratory and en- tire navy department on occasion of longest air- craft communication ever established. We are in flight 3,000 feet over Lit- tle America, Bay of Filming and Recording 2 Home Talking Movie by Synchronizing Camera and Phonograph TALKING MOVIES MADE IN HOME WITH SIMPLE APPARATUS The home motion-picture camera and a small recording phonograph can be syn- chronized for the preparation of “talkies,” a group of eastern enthusiasts have dis- covered. A banjo number was one of the first produced and was a success due to the careful timing of the film to corre- spond to the rotation of the record. RADIO TALK WITH BYRD PLANE SETS WIRELESS RECORD Flying 3,000 feet above the antarctic ice, Malcolm P. Hanson, radio chief of Commander Byrd’s expedition, broke all previous long-distance wireless records from a moving airplane, when he talked with the New York Times radio station, 10,000 miles away. Reginold Iversen, ra- dio engineer at the Times station, had been warned that a test would be staged from the Byrd plane “Stars and Stripes,” by a call from Carl O. Peterson, operator on the steamer “City of New York,” Byrd’s base ship. “Listen in and try to hear the plane,” was the call from Peter- son at a few minutes after three o’clock in the morning. “The plane is now leav- ing the ice,” was the next word. Iversen shifted the dial around to the thirty-four- Whales, Antarctica. Fine sunny night. Hanson.” The transmission ended twelve minutes after the report had been received that the plane was to go up. REVOLVER RACK ON AUTO DASH AIDS POLICE SQUADS Attached to the automobile dash or other convenient place, a revolver holder has been found useful for police duty. It consists of a projecting bar held by a bracket. The revolver barrel is simply slipped over this bar so that the weapon is handy for immediate use. The holder Sketch of Revolver Holder Installed on Dash Where Weapon Can Be Grasped Quickly can be taken down in a few seconds, as the bracket slips out of a socket. Te: bu be wi we We ele pr to te1 est or art tra in ma loy sul int

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POPULAR MECHANICS 553 Testing an Insulator by Subjecting It to a Million-Volt Laboratory Flash MILLION-VOLT ELECTRIC FLASH TESTS INSULATORS To determine the effect of lightning on bushings and insulators, experiments have been conducted in an eastern laboratory with an artificially produced flash of 1,000,000 volts. Wet-weather conditions were simulated by spraying a stream of water upon the unit under test while the electrical charge was on. HOLLOW WALL DEADENS SOUND MORE THAN SAWDUST Soundproofing involves careful study and practice, and scientists are just beginning to discover the proper way to protect in- teriors against noise. Among other inter- esting facts they have learned is that, under ordinary conditions, various materials that are supposed to deaden sound actually transmit it, so great care has to be exercised in constructing walls or other areas to make them soundproof. For example, hol- low walls, in many instances, are better in- sulators against sound than those with an inner space filled with sawdust or other porous material. The filling, oftentimes, instead of keeping the sound out, helps carry it through. Walls can be made soundproof without tearing them down, by covering them with soundproofing ma- terials which may be used as a base for plaster or may need special strips for the lathing and plastering, depending upon the kind of material used. If the room is to be insulated against sounds from with- in, a special soundproof plaster, that deadens echoes, literally swallowing the sound before it can bounce back again to another wall, has been prepared. It is being used with success in broadcasting studios and other interiors. SHIP FEELS EARTHQUAKE Sailing over the center of an earthquake just when it occurred was the experience of a British freighter recently. She was off the coast of Chile, when three heavy bumps were felt as if she were scraping the bottom, though the charts showed the depth of water to be over 400 feet.

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Count de Prorok and Amenokal Akamouk, King of a Vast Tuareg Territory in the Center of the Sahara By JAMES N. MILLER DVENTURES far more thrilling than + * those described in the current novels of burning sands and desert sheiks are de- scribed by Count Byron Kuhn de Prorok, explorer, just returned to America after two years of investigating archeological treasures in the heart of the Sahara des- ert. Within a few weeks he will be back in Africa once again, continuing his life work of revealing to science the secrets now concealed beneath century-old cov- erings of sand mountains. A thousand miles into the remote re- cesses of the world’s most mysterious wasteland, filled by desert desperadoes, the count made his way on his recent trip; 554 here meeting a people of giants close to seven feet tall but ruled over by hosts of masterful women; there almost perishing from sudden onslaughts of fierce and relentless sandstorms; while always he pressed steadily forward in the hope of solving the Sa- hara’s most perplexing puzzle—whether or not the rumor was true that a powerful white queen, now buried amid untold riches, once ruled over a territory about as large as. the United States and known as the home of the Tuaregs, descendants of the an- cient Libyans, a cul- tured people who roamed the desert some 3,000 vears ago. Already renowned for unearthing many of the treasures of ancient Carthage, the youthful explorer, now only thirty-one vears old, tells a graphic story of how he happened to go on his search for the mysterious white goddess—a search that finally met with success. “T had long been convinced,” he ex- plains, “that the legendary queen must be far more than a fable. I had heard about her from virtually every tribe of desert folk and I knew that the belief in her one- time flesh and blood existence was ad- hered to by Prof. Emile Gautier, of Paris, greatest of all scholars of Sahara lore, as well as numerous other authorities. “Back in September of 1926, therefore, I started my search by sailing from Paris, arriving at Algiers some ten days later. With me were twelve men of various scientific abilities, including Prof. Maurice kb. Ww J 22 ee tl

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* ~“~*« ~~ = | SS a eee a ee oaths “ oN a ae Photos Courtesy of Count de Prorok Countess de Prorok and Members of the Expedition Examining a Collection of Beautifully Worked Flint In- struments Gathered by Them near the Egypto-Italian Frontier Reygasse, celebrated French archezclogist, M. Louis Chapuis, well-known explorer, Henry Barth, photographer from the University of Paris, Harold Denny, of Paris, recorder of the expedition, Mo- hammed Belaid, famous Tuareg interpre- ter, and Bradley Tyrill, Pasadena, Calif., game hunter. “Our preparations were unique. I had been studying the Sahara for a good many years and felt that camels, with all their vaunted endurance, were hardly the trans- portation mode for me, since they re- quired great care. Nor was the standard automobile of much avail against the ter- rific onslaught of the wind and the great mountains of sand. So I finally hit upon the idea of having especially built for me three twelve-wheeled motor cars equipped with balloon tires. They worked admira- bly by boldly plunging through the torrid sands and bowlders and blasting many a new trail. “We had to make careful arrangements with the French government so as to gain some assurance of safety from the desert brigands. The French responded gener- ously. As most people know, their re- markable system of military guard con- sists in the maintenance, at strategic wa- tering places, of garrisons, whose purpose it is to lend aid to law-abiding travelers as well as to protect the commercial interests of France. The men in charge are known as the ‘Meharis’ or military police. “Only a few days of traveling through the picturesque Atlas mountains, and we were in the great Sahara. At this point we had no idea of the supposed location of the ‘White Queen’s’ tomb, so we decided that it would be best to live among the natives for about a month, thereby gain- 555

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POPULAR MECHANICS when a child is born it os automatically takes its mother’s, rather than its father’s, name. “Nevertheless all this j woman rule prevails in a land where the men are close to seven feet tall. Beautifully proportioned and of clean-cut features, the pure-bloods are just about a hundred per cent white, though of course the strong sun has given them a coat of tan. ‘It is laughable to think of the men as painting their lips and eyebrows, but that’s not even half the story. They actually wear their hair in what looks like a fantastic kind of perma- nent wave. The men do not prepare their own locks, however. That is Opening the Tombs of a Mediterranean Civilization Whose Riches Rivaled Those of the Entire Nile Region Today the job of the women, and they fulfill it well. ing their confidence and listening atten- “While, to our way of thinking, many tively to rumors of the supposed queen’s of the Tuaregs’ habits are exceedingly whereabouts. queer, yet they have certain delightful “Now, too, we were in the land of the ones that are well worth mentioning. , Tuaregs, which word in our language Take their music. It is like nothing else means ‘the abandoned of God.’ In virtu- I have heard anywhere—a sort of plain- ally every respect they are markedly dif- tive wail with an occasional long note like } ferent from the other desert nomads, be- the ‘zing’ of the Hawaiian ukulele. The ing fair-complexioned underneath their ‘amarad’—the instrument most commonly tan, instead of black, practicing strange used—looks like a cross between a violin ceremonies and giving women an exalted anda mandolin, and it is played only by place in the domestic life. In addition, the women. Up and down, for hours at the Tuaregs have resented interference a time, they wield the crossbow. from outsiders, so we had to plan pains- “Another charming custom is the in- takingly our early contacts with them. variable one of conversing entirely in First of all we had sent ahead bales upon’ verse. Imagine trying to frame your com- bales of sugar and tea, of which they are monest thoughts in such fashion! Cer- fond. Apparently our gifts had beguiled tainly the feat requires the quickest kind completely these desert stalwarts, for the of wit, but the Tuaregs are quite equal j king, Amenokal Akamouk, a jolly fellow — to the occasion and some of their folklore of some fifty vears of age, greeted us with is abundant with genuine classics of open arms. poetry commemorating mighty deeds of “Far from being overdrawn, the strange — valor. stories about the Tuaregs seem to me to “After a month among these fantastic be underestimated. The men wear veils folk, we managed to glean, by means of while the women do not and the ladies careful questioning, what seemed to be possess most of the education. Not only valuable information about the possible do they control the home and family, but whereabouts of a tomb purported to be inheritance is likewise on their side. Even that of the mythical White Queen. Guided

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ed POPULAR MECHANICS Count Byron Kuhn de Prorok and Maurice Reygasse, Administra- tor of the District of Tebessa, Being Es- corted to the Tombs of the Kaids and, Be- low, the Temple of the Oracle of Jupiter Ammon, Thirty Cen- turies Old; It Was Visited by Alexander the Great, Croesus of Lydia, Cato, Lysander and Hannibal, Who Braved the Desert to Consult the Oracle ies See

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POPULAR MECHANICS could early see the out- lines of the tombs of twelve noblemen. Each tomb was about fifteen feet square and eight feet high, we discovered. Be- ing pressed for time, we forced our way right through the heart of the monument, penetrating sand and stone alike. And most of the stones, mind you, were about two feet by three in size and were heavy enough to require two men to transport them from their original position. At a rough estimate, I The Famous Fountain of the Sun, Which Ancient Historians Said Was Warm at Night and Cool by Day by Belaid, our Tuareg interpreter, about three davs after leaving the camp of the Tuareg king, we arrived at the supposed region of the White Queen’s tomb. There was no immediate sign of habitation, so far as the white Tuaregs were concerned. Though only a few miles away, we found a number of mud houses inhabited by native blacks. “A proper excavation procedure re- quires the services of a good many people and we were only five in the first truck. So there was but one thing to do and that was to hire some of the blacks. Having persuaded twenty of them to join our em- ploy, we looked around us more carefully and noted what seemed to be a great cir- cular monument, about 100 feet around, forty feet high and made up of great vol- canic rocks, beautifully sculptured and wrought with ancient Libyan inscriptions. “And now a few explanatory words about the accepted way to excavate a desert tomb. Of course, big spades are used, but every single shovelful of sand must be sifted painstakingly so as to make sure that no possible small treasure will be missed. Thus every member of our party had a hand sieve, and shoulder to shoulder we dug our way down, looking for all the world like a group of gold-seek- ing prospectors. As indeed we were, in a sense. “Down at the base of the monument we would say that we re- moved in such fashion thousands of great stones within our two weeks of excavating. “For five days we kept right along, dig- ging and sieving with remarkable zeal, considering the circumstances. Then, I made my first great discovery, a tiny red object abcut the size of a fingernail. It was a coral bead, almost identical with certain beads I had found some years be- fore while probing the ruins of ancient Carthage. “Shortly thereafter I found quite a few emeralds and garnets (cousins to the ruby) besides a great abundance of semi- precious stones. By this time we had worked our way down through stone and sand clear to the monument’s floor.: A few more deft movements of our spades, and our delighted and astonished eyes were offered the once-in-a-lifetime treat of a veritable Aladdin’s carpet, covering the entire floor, red in color, made of leather and possessed of a _ beautifully wrought fringe about six inches long. It was preserved almost perfectly because the extreme dryness of the Sahara serves to keep most materials more or less intact for centuries. “Among the objects found next, in the order named, were: a rock-crystal vase and a funny-looking nine-inch statuette of a broad-shouldered woman. This last was of the utmost importance because it heralded the greatest find of all. A few moments more of brushing the sand away, a he KH we OU mem wh mM 48lCUmGlUlCO “a * 6 65 Fo - lonit dene l Sf af -*>

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he ise tte ast ew ay, POPULAR MECHANICS 559 and right beside this statuette was found a perfectly preserved skull of a woman close to seventy years old. The condition of the’ sharp-edged teeth told us that. It was the skull of the White Queen herself. “With utmost care we continued to re- move, with our brushes and bellows, the coating of sand in the surrounding region and soon found remnants of the entire corpse, including hundreds of delicately- fashioned beads and all manner of pre- cious jewels. The royal lady had been lying on a magnificent canopy of sculp- tured wood, portions of which were in well-nigh perfect condition. On her head had beén a tiara, or jewel-containing gar- ment, besides three feathers. This last discovery indicated strongly that the White Queen had been a veritable Amazon who had fought during war- fare periods. “After leaving In- party was organ- ized. But fortu- nately the lost members in their two trucks stag- gered into Oargla two days later. “About the date of our find there was much contro- versy, some mem- Excavating Tombs of the Amoriens, a Collection of Silver Coins of Alexander the Great, Found in the Desert, and de Prorok Meeting the Chief Guide of the Expedition salah we were caught in a terrific sand- storm with certain dunes towering 1,400 feet high, and soon the three trucks be- came separated. My truck finally bore several of us safely to Oargla, a French fortress a few hundred miles away. We told the officials where we had last seen our companions and immediately a search bers of our party thinking it harked back to days before Christ, and others, that it dated far later. The argument was not settled until we reached Paris about a month later, and that was a curious situation. It seems that we had found a small wooden bowl, or vase, with silver designs on it. But since we had so many little curios to ex- amine, we hadn’t taken the trouble, while in Africa, to scrutinize this particular one very carefully. But one day in Paris | was entertaining a group of scientists and happened to be idly cleaning the vase, when underneath the sand and dirt I sud- denly beheld three metal objects. They were Roman coins and their presence in the curio left no doubt but that our party had found the White Queen.” GEESE WEED BERRY PATCH Geese have been used as a substitute for laborers in keeping a North Carolina strawberry patch free from grass, and the practice is said to be spreading through- out the south. The birds eat the grass but do not touch the berries or plants.

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560 POPULAR

MECHANICS AUTOMATIC OILER REACHES ALL PARTS OF THE CAR

= 7 = ——— } |_| ———_——— J oo == i ~ - ' [| O| _® | |

Sketches of the Automatic Chassis-Lubricating System; Top Row from Left to Right, Bearing Connection, Cross Section of Resistance Unit, the Pump, Filling Reservoir and, Below, Scheme of Entire System Continuous and automatic lubrication for the automobile chassis is afforded in a system that utilizes the effect of road shocks while the car is in motion to keep all bearings thoroughly oiled. All the motorist needs do is to fill the reservoir. There is nothing to push or pull, for the car literally lubricates itself. This is ac- complished by the action of a pump inside the oil reservoir, a glass container installed under the hood, on the dash or in any other suitable place. The pump is so ad- justed that it is operated by the jarring of the car. This motion causes oil to be forced into the line. To control the flow, resistance units are installed at each bear- ing. They govern the amount of oil that reaches the bearings and are also fitted with a fine screen to keep out foreign sub- stances. A small check valve is incor- porated in each resistance unit to prevent the system from draining, a trouble likely to occur, since some of the bearings are higher than others. By turning a screw in the pump, the amount of oil to be fed into the line can be regulated. This is the only adjustment necessary. PLANE SOLVES SEA MYSTERY IN FINDING SHIP Lost for six days after a storm, and un- able to communicate with ship or land, the Russian motor vessel “Communa,” with twenty-six persons aboard, was found by airplane recently. The boat's engines had been disabled and it was help- lessly drifting when it was seen by ob- servers in the low-flying plane. A tug was sent to the rescue.

far stc six eat dis the bei tur €x] ing the sio Iny sor for rT sor for rid wh cor the the Tri-! for Sno tor

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POPULAR KILL GERMS THAT EAT STONE TO PRESERVE BUILDINGS Scientists are waging a chemical war- fare against harmful germs that devour stone and other building materials. Some sixty different species of organisms that eat stone and other substances have been discovered, and chemicals that will kill them without damaging the material are being sought. The germs weaken struc- tures by opening pores in the surface, thus exposing it more to the. weather and caus- ing it to crumble. It has been found that some of the bacteria will cause ero- sion in the hardest marble in three weeks. Investigators have found that beetles and some other insects that have been blamed for damage to buildings are not at fault. MOTOR SKIS AT SWISS RESORT GIVE WINTER THRILLS St. Moritz, Switzerland, long has been famous for its winter sports, and this sea- son a new one was provided in motor skis for fast travel over snow and ice. The rider, wearing skis, sits on a third one to which a motor has been attached. The controls are within convenient reach, and the operator easily balances himself with the aid of the outer skis. Tri-Ski Speed Outfit for Fun in Winter Snows, with the Mo- tor Unit Mounted on the Center Ski MECHANICS 561 through Special Fitting, and a Close View of Installation FITTING CLOSES OPEN OIL HOLE AND SAVES WASTE High-pressure fittings have been intro- duced for open oil holes on machinery to keep out the dirt, save waste and afford the benefits of pressure lubrication to parts that ordinarily are oiled in a more or less haphazard manner. The units in- volve no threading operation and can be installed in a few minutes. First, a bush- ing is driven into the hole and into the top of this is inserted a nipple with a dirt- proof ball-check valve. An ordinary ham- mer and three special tools form the nec- essary equipment for installing the fittings. So equipped, the parts can be lubricated with a pressure gun. Greasing Bearing SEA GRASS STOPS SOUND AND KEEPS BUILDINGS WARM Builders have discovered that a common variety of sea grass is serviceable as an in- sulator against sound, heat and cold. Like other cellular substances, when dried, it proves an effective shield against noise and is said not to harbor insects while it is practically fireproof. It is being used extensively in some sections for upholstery and mattresses.

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N UNCLE SAM'S big science mill at Washington, where practically everything under the sun is made, perfected, studied or examined so that we may be happier, healthier and live more comfortably, there are hundreds of experts who spend scores of years and sometimes entire life- times on research projects of the queerest kind imaginable. One, for instance, with the tongue-twisting title of “helmin- thologist,” spends hours exam- ining under the microscope the almost countless varieties of strange parasites that prey par- ticularly on humans; another often has to stick his head deep into funny-looking and espe- cially devised contraptions so as to watch the frolicsome ma- neuvers of those fantastic, whip- like organisms of almost un- canny shapes, sizes and descrip- 562 tions that are known as “nematodes”; while, in vir- tually every sizable avia- tion field of the army air corps, there are specialists called “dopesters,” whose main job is to cover sec- tions of recently repaired planes with a _ chemical compound so _ poisonous that some of the appliers actually have to drink as many as five quarts of milk a day in order to counter- act the dope that seeps into their system and makes them “groggy.” Dr. W. W. Coblentz, of the Bureau of Standards, Testing Glass Screens to Protect Movie Stars from Kleig Lights, and Miss Eloise Cram, Bureau of Animal Husbandry, Examining Chicken Pests N cour may to ¢ ever solu van taki: of 1 Yet, son, tak stra

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ilk a ps nd ass ise Not all these- jobs, of course, are dangerous, and may be it’s not quite fair to call them queer, since every one seems to be ab- solutely essential in ad- vancing the almost breath- taking hop, skip and jumps of modern-day science. Yet, to the average per- son, they are bound to take on a singularly strange, or at any rate novel, character. Take the case of William N. Dovenor. He is an artist and, in his official capacity as chief scientific illus- trator to the bureau of entomology, his main task is to devise a rogues’ gallery of insects harmful to man and orchard. Ask him what he has been doing for the past sixteen years and he'll reply “everything under the sun,” while explaining that first of all his purpose is to sketch the com- plete life history of the knaves of “bug- ology” so that the farmer and gardener may learn how best to control them and So protect their crops. To hold a job like that requires the ut- most patience and painstaking study. May be for as long as ten days, or even two weeks, Mr. Dovenor, in the recesses of his studio, will be called upon to spend every available working hour studying the wrig- glings of a single insect larva that isn’t much more than visible to the naked eye. But it is just such seemingly inconsequen- tial creatures that devastate and destroy A Government Chemist Practicing Ultra-Filtration in a Delicate Test, One of Many Made Daily hundreds of thousands of acres of corn, tobacco or cotton. On one single canvas, containing but twenty-six views of twelve different larve, his endeavors occupied several months. Movie stars may not realize the fact, but it is nevertheless true, that much of their indebtedness for relief from the strained- eye ailment, known in its advanced stages as “Kleig eyes,” is due to the efforts of Dr. W. W. Coblentz, of the bureau of standards. When the subject was first brought to his attention, he conducted many tests with various glasses to cap the high-powered Kleig lights. But not so long ago he made the astonishing dis- covery that probably the very best thing for the purpose was ordinary window glass. The reason is that it does not transmit the piercing ultraviolet rays, a situation that, strangely enough, has caused window glass to be condemned rather universally by the health experts. 563

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564 POPULAR The helminthologist is Dr. Maurice Hall, best known, probably, for having done more in devising ways to combat the per- sistent human tapeworm than any man in America. There have been times when Doctor Hall has swallowed the undigest- ible creatures, and now and again the results have placed him pretty close to the martyr list of research workers. Similar to Doctor Hall’s is the every- day work of Miss Eloise B. Cram, zoolo- gist, whose study of internal parasites is confined to chickens and pigs rather than humans. Her efforts alone undoubtedly save American farmers hundreds of thou- sands of dollars each year. Her chief oc- cupation just now is to find out how the serious poultry diseases are spread. She has long held the idea that, may be, the cockroach, the grasshopper, or else the cricket has had a hand in the situation, and lately she has proved that insects in- deed are to some extent guilty of trans- mitting the diseases. In the same general line of work as Doctor Hall and Miss Cram is Dr. N. A. Cobb, who bears the title of “nematolo- gist.” Thus graphically does he describe the vital importance of his studies: “If all the substance of the earth and of the things that flourish on it, with the excep- tion of the threadlike organisms known as nemas or nematodes, could by a stroke of magic be made invisible, then it would MECHANICS still be possible to distinguish the soil- covered parts of the earth, the streams, lakes and oceans, the insects, animals, birds, fishes, plants and humans. So wide- spread and abundant are the nemas, that in this imagined world of transparencies most living things, such as the blanket of soil on mountains, hills, and plains, and the bodies of water would be indicated by clouds of these living threads which vary in length from a small fraction of an inch to several feet, and in diameter from that of the finest of hairs to the thickness of a lead pencil.” An observer, looking through a high- power microscope, views in a lighted field a world as complex and as full of mystery as that we see daily with the unaided eye. There are poorly lighted recesses in this world that hold their secrets tenaciously and seem to require for their exploration something comparable to the spotlight in a darkened room. Just such a spotlight has been recently discovered by Doctor Cobb. Knowing, of course, that when the image of the sun is reflected into the field of vision of the microscope, its brilliance is far too great for the unprotected eye, he investi- gated further. To his surprise he found that on hazy days he could actually form the image of the sun on the tissues inside the object being examined. This bright spot lights up the surrounding tissue, en- Mixing Deadly Potions, to Be Tried Out on Cockroaches and Other Insect Pests, Is the Regular fob of J. W. Sale and J. B. Wilson, of the Food, Drug and Insecticide Bureau \ f a aie ttn

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POPULAR MECHANICS Above Is One of Uncle Sam’s Many Unusual Tasks, Holding a Duff Hygrometer on the Ground to Determine Whether the Moisture Content of the Grass Is So Low as to Cause Fire Danger; at Left, Dr. M. C. Hall, “Helminthologist” Who Studies Parasites An Artist Is Retained by the Department of Agriculture to Paint Garden Bugs; Below, One of the Special. Micro- scopes Used to Study Minute Organisms That Prey on Anima abling the observer to see plainly what did not ap- pear under ordinary illumi- nation. So Doctor Cobb, since then, has been experiment- ing with various means of duplicating the effect of the sun as seen through a

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566 POPULAR MECHANICS hazy atmosphere. He tried out glass- walled boxes containing smoke, then fumes of ammonium chloride, next water containing milk, and so on, down through a lengthy list. He achieved an especially good result by the use of a huge sheet of glass very finely etched with acid. Deeply colored glass, especially green or blue, may be used to advantage, he found, so that, with such a glass sheet between the sun and the microscope condenser, the sun’s image can be used to search out the otherwise obscure spots. Those dopesters of the army air corps, mentioned earlier, use such poisons as cellulose acetate and cellulose nitrate for the reason that they tend to fill the pores in the outer fabric of the plane and cause it to shrink, thereby giving it an airtight and smooth surface. The plane as a whole is not covered in this way because that has been attended to by the commer- cial makers of the ship. It is only the wings that have been temporarily broken and have just been patched up, that need the dope. Speaking of poisons, there is an official of the bureau of chemistry and soils whose major task is to watch for and investigate carefully the reports of all new chemical compounds that give promise of going toward revolution- izing the nation’s commercial trade poisons. Dr. R. C. Roark is the man, and he is known as the poison investigator. Right now, he is devoting consider- able time to a new com- pound known as rote- none, which is made from the derris root, found rather abundantly in the Philippines, Java, Bor- neo, Sumatra and the Malay peninsula. It has been claimed, though not authori- tatively, that the natives of those places have used the root for the purpose of kill- ing fish, by simply putting a tiny quan- tity of the poisonous substance in the water, whereupon, within a few hours, the swimmers die and float to the surface to be caught readily. The claim might be true enough at that, experts say, since tests show that one part in a million can kill minnows with an ex- posure of twenty-seven hours. But if derris root kills minnows, why doesn’t it deal death also to humans? Because it has the peculiar habit of quickly becoming decomposed and inert. Which is why it shows splendid prospects of being valua- ble as a spray, possibly taking the place of the deadly lead arsenate. Rotenone shows further promise in that it is soluble in certain oils without losing its strength. A somewhat different study of poisons is conducted under J. W. Sale and J. B. Wilson, of the food, drug and insecticide administration. To them falls the lot of mixing up concoctions that spell speedy destruction to the cockroach and its in- sect cousins. Almost equally unknown to the public is W. B. Symonds of the bu- reau of chemistry. All day long, he wrestles with all manner of glass which he molds into fantastic shapes H. P. Sheldon, of the U. S. Biological Survey, Spends His Time Figuring Out Where the Wild Birds of the Nation Live at Various Seasons ef the Year

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POPULAR MECHANICS 567 for famous men who must have, at a mo- ment’s notice, the practical results of in- tricate-looking blueprint ideas. Who ever heard of “ultra-filtration”? The word sounds highbrow and is, for it must have the guidance of an expert who understands the highly intricate work of filtering carbohydrates (starches and su- gars) to just about their finest possible point. Such a man is L. E. Dawson, gov- ernment chemist, whose efforts in this connection are invaluable to the sugar and°* candy industries. Like W. B. Symonds, and most of the other government scien- tists who perform miracles for you and me while sitting tight and saying nothing, he is literally a wonder worker. Experts in the various govern- ment departments are constantly being called on to perform the seemingly impossi- ble. One classic ex- ample is the order from Doctor Lang- ley, when he was secretary of the Smithsonian, in- structing an aide to drill a hole length- wise through a nee- dle much finer than those used for hy- podermic injec- tions. The task was completed success- fully. Recently the bu- reau of standards, helping prepare a government exhibit to be shown at the Spanish exposition at Seville, Spain, this summer, solved the problem of get- ting an accurate count of the num- ber of visitors who inspect the Ameri- can exhibit by building a light- beam counter. A small light is to be placed at one side of the gate, focused on a photoelectric cell hidden in the other side. Every person passing through the gate will interrupt the light, momentarily stopping the cur- rent generated in the light-sensitive cell, and this in turn will operate a relay con- trolling the automatic counter. The bureau of standards carries out an immense amount of scientific research . work. One of its sections does nothing ta but study fires. A single report, recently Chemists Found Milk an Antidote for Poiscning from issued on the fire-resisting qualities of Aircraft Wing “Dope”; Studying Nematodes Is Doctor hollow tile when used in load-bearing Cobb’ : i oa eee —— Blows All Special tls, fills a volume of over 330 pages.

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568 POPULAR MECHANICS shed “ee Illustrating Some of the Uses_of the Portable Electric Plant; Generating Light for Railroad Duty and Fur- nishing Power for Drills; Inset Shows Close View of Unit ELECTRIC PLANT IS PORTABLE FOR LIGHT AND POWER For service in‘places where power lines are not available, a portable electric plant, operated by a gasoline or oil-burning motor, has been devised by German engi- neers. It furnishes illumination or drives tools of different kinds and is especially adapted for service along railroads. Cables are provided for operating several ma- chines and lights at the same time. WOMEN GAINING AS INVENTORS PATENT RECORDS SHOW In Kansas lives a woman whose chief occupation is raising chickens but she has found time to invent a doll that can walk, dance, sit down, cross its legs and do other things that humans can do. She obtained patents on the doll just recently, thus in- creasing the growing list of women who are making names for themselves as in- ventors.. Between 1790 and 1910, more than 11,000 patents were granted to wo- men in this country. In England, women were granted 500 patents in one year, and a firm.of patent lawyers there reports that more inventions by women are now being handled than ever before. Their ao 0 =o mf aw» o soe > am wo ia =]

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ahi, Zi ieee ho in- yO- len ind rts ow \eir POPULAR MECHANICS 569 ideas cover not only the household field but extend to aviation, motoring and other activities. Among those winning prize awards from the General Electric com- pany recently, was a woman employe who had developed a means for faster work on the armatures of small washing-ma- chine motors. TRACING CLOTH FOR CURTAINS. ADMITS HEALTHFUL RAYS Tracing cloth used by draftsmen in blue- printing drawings may become popular as a curtain material as a result of an acci- dental discovery that the fabric admits the healthful ultraviolet rays of the sun, usu- ally excluded by paper and other kinds of cloth. It has been suggested that the material be placed in single thickness be- tween wide-meshed wire screens to re- place curtains and blinds in dwellings. ELECTRIC HEATER WARMS BED AND SERVES AS DRIER To warm beds, an electric heater, oper- ating on somewhat the same principle as a hair drier, has heen introduced in Ger- many. It is run from a lighting socket and when used in a bed, is placed upon the pillow. with the nozzle down and the reverse side exposed so that air can be drawn through openings. The air is heated by the electric element and is fanned down inside the covers, circulation being insured with the aid of a coil spring which is laid lengthwise in the bed. Adjusting the Bed Warmer; the Blower, with Inlet Holes Up- ward, Forces Warm Air along Spring Coil Memorial to Mrs. William Astor as It Appears under Floodlights in Old Trinity Churchyard, New York LIGHTS ON CHURCHYARD CROSS REVEAL MEMORIAL’S BEAUTY Persons working late in Wall street often stop at night to gaze at the illumi- nated crucifix, thirty-nine feet high, erected some time ago to the memory of Mrs, William Astor. Four flood- lights focus their beams on the cross, which is of white marble and stands in the old Trinity churchyard. Besides the figures of Christ and the madonna and child, representations of other Biblical characters are included among the decorations. @The Popular Mechanics’ Bu- reau of Information offers its free service to all readers of our maga- zine. Names of manufacturers and dealers in articles described. and any other details in our pos- session, will be promptly fur- nished by addressing the bureau.

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The Bacubirito Meteorite, Second Largest Known Rock from the Sky, Lying at the Point Where It Fell in the State of Sinaloa, on the West Coast of Mexico ° By CALVIN FRAZER NE REASON why the moon is not fit for human habitation, besides the two well-known facts that it has no atmos- phere and is subject to unendurable ex- tremes of temperature, is that it under- goes the incessant bombardment of in- numerable meteors. The majority of these bodies are no larger than grains of sand but have great penetrating power, as they fly at speeds ranging up to forty miles or more a second. Many, moreover, are as big as baseballs, and some are great bowlders weighing hundreds of pounds or even several tons. A human visitor to the moon would almost certainly be hit sooner or later by one of these deadly missiles. An interesting consequence of this fusil- lade of meteors upon the moon has lately been pointed out by Professor Olivier, a leading American student of meteoric phenomena. Astronomers have long con- jectured that the so-called lunar craters, instead of being extinct volcanoes, may be the scars left by the impact of giant meteors. Whether or not this is true, says Professor Olivier, it is quite certain that the continual fall of meteors of mod- 570 erate size must, in the course of ages, have produced a sort of sand-blast effect upon the lunar surface, quite comparable to the erosion by wind and water that has sculptured the surface of the earth. Only the presence of a surrounding en- velope of air saves our own planet from a similar bombardment. It is estimated that fully 20,000,000 meteors enter the earth’s atmosphere every twenty-four hours. The air protects us from these missiles in two ways. First, even in the thin upper layers of the atmosphere, the meteors are intensely heated by friction, and most of them are completely burned up or reduced to an impalpable powder long before they can reach the earth. Second, the resistance of the air checks the speed of those that reach the ground, so that they do not, as a rule, hit the earth much harder than would bodies of the same weight falling from the height of a few miles. The bigger ones fall with much violence, but small specimens have been known to fall on ice only a few inches thick without breaking it. Meteors that fall to the earth are called meteorites. These vary greatly in size.

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A Bursting Meteorite That Terrified the Natives at Chandpur, Northwest Provinces, India, on April 6, 1885; the Photograph Is Made from a Contemporary Drawing The smallest thus far found were no larger than grape seeds, while the largest of all is the Cape York meteorite, weigh- ing thirty-six and one-half tons, which Lieutenant Peary brought down from Greenland in 1897, and which is now in the American Museum of Natural His- tory. About half of all the meteorites now preserved in museums were actually seen to fall. The rest are known to be meteotites because they possess certain features characteristic of such bodies. The museum specimens represent nearly 900 distinct falls, and the total number of meteorites discovered up to date mounts up into the thousands. Probably hundreds fall for every one that is recovered, but, even so, the fall of 571

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572 a meteorite is an ex- ceediggly rare event in any one locality. The late Prof. C. A. Young made a rough guess to the effect that the total amount of meteoric matter falling to the earth averages 36,500 tons a year. At first sight, this total seems large enough to make the falling of meteorites a rather serious danger to hu- manity. It is, however, so small in proportion to the area of the globe that, if the ma- terial falling at this rate were spread evenly over the earth’s surface, it would make a layer only about an inch thick in the course of a billion years. More- over, the vast majority of meteorites are too small to be capable of causing much damage. Nobody need lose any sleep over the danger of being hit by a meteorite. Neither would anybody be justified in insuring his property against a similar danger. If an in- surance company could POPULAR MECHANICS persuade a large number of gullible people to take out insurance of this sort, the com- pany might operate for centuries without paying out ‘a cent to its policy holders. Nevertheless, in the long run and on the earth as a whole, meteorites do cause a certain amount of damage, and there is a bare possibility that some day a fall of these bodies may be responsible for a more colossal disaster than any volcanic eruption, earthquake or flood that has ever befallen the human race. This possibility was vividly brought to mind a short time ago by the belated news of an event that hap- pened in the wilds of Siberia in the summer of 1908. On June 30, about seven o’clock in the morning, a mag- nificent falling star, of dazzling brilliancy, was observed in the northern sky by thou- sands of people in the southern part of the province of Yenisei. The place of fall long remained a mystery, but in the summer of 1927, an expedition under Prof. L. A. Ku- lik located it in the midst of an almost in- accessible forest lying north of the “Stony” Peary’s Cape York Meteor; and Meteor Crater as Seen from the Air; the Black Specks in the Fore Halley’s Comet, Parent of a Swarm of Them, ground Are Trees

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POPULAR MECHANICS 573 m, DS On the Rim of Meteor Crater, the Vast Hole in Arizona Which H-s Puzzled Science; the Rim Is Lined with These Huge Bowlders, Thrown Up by the Violent Impact Tunguska river, in about latitude 61 de- grees north and longitude 102 degrees east. This region is’ very sparsely inhabited by half-civilized Tunguses, and this fact, together with a complete lack of roads and telegraph lines, explains why details of the meteor fall were so slow in reaching the rest of the world. Kulik has recently returned to civilization with a wonderful story of what he found. Where the me- teorite struck, there is now an area several miles in diameter where the earth is torn and furrowed as though by a gigantic harrow and pitted by large funnel-shaped cavities, like shell holes. Around this cen- tral area, in a circle scores of miles in di- ameter, millions of dead trees lie like a vast forest of fallen ninepins. They are all stripped of their bark and branches, and each tree lies with its top pointing outward from the center of the devastated area. All the vegetation for miles around shows the effects of a uniform scorching, quite different in appearance from that caused by a forest fire. Evidently a meteorite of extraordinary size burst in mid-air and rained down its fragments upon the earth, or else the fall- ing material consisted of a swarm of me- teorites traveling together through space. The sudden compression of the air under these falling masses must have generated great heat and sent out in all directions a hurricanelike blast that felled and shat- tered the trees. The outrush of this hot air was actually observed by several na- tives in the surrounding country. One man, forty miles from the place of the fall, was hurled several feet by the air wave, which felt so hot that he thought his clothes would catch fire. His house was wrecked by the same wave. Another man had stores and a herd of 1,500 reindeer in the forest at the time of the fall. Only a few scorched carcasses of these animals could be found after the event; the rest were completely annihi- lated. The storehouse was burned down, and a number of tools that it contained were melted. At Lalka, 400 miles from the center of disturbance, railroad em- ployes felt the air wave and heard a roar- ing sound. Even at the observatory of Irkutsk, 800 miles away, the air wave was registered by a barograph, and the shock of the falling mass was recorded by a seis- mograph. No specimens of the meteoric material have yet been recovered from this fall. The fragments are probably buried deep in the earth, and it would be a difficult task to transport to the spot

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574 suitable tools for digging them up, but this will doubtless be done eventually. A survey of the region by aeroplane will probably be carried out next summer. As one part of the globe is as likely to be bombarded as another, it was merely a lucky chance in this case that directed the celestial missiles toward a wilderness rather than toward some densely popu- lated region. If London or New York, for example, had been the target, the re- sults would certainly have been appalling. Millions of lives would have been lost, and billions of dollars’ worth of property would have been wiped out. It is com- forting to reflect, however, that such a meteor fall as occurred in Siberia is al- most unprecedented in the world’s history. Almost, but not quite. About thirty-five miles east of Flagstaff, Ariz., near the long ravine known as Canyon Diablo, there is a remarkable craterlike hole in the ground, 4,000 feet in diameter and 600 feet deep. No evidence of volcanic activity exists in the neighborhood, and though at one time there was much controversy in scientific circles about the origin of the hole, it is now generally admitted to have been formed by the fall of a huge meteorite or cluster of meteorites. A great number ‘of iron meteorites have actually been found within a few miles of this spot. The principal mass of material is supposed to be buried hundreds of feet underground, and several unsuccessful attempts have been made to reach it, on account of the probable value of the meteoric iron, to say nothing of the chance that it may con- POPULAR MECHANICS tain diamonds, which have occasionally been found in meteorites. The walls of this curious formation rise well above the surrounding desert, so that, at a distance, it looks an isolated hill of the flat-topped variety common in the southwest, and it was formerly called Coon Butte, but is now known at Meteor Crater. Trees growing on its side are fully seven hundred years old. On the other hand, the crater shows but slight indications of erosion, so that it cannot be very ancient. Navajo Indians living in the neighbor- hood have a tradition that fire once fell from heaven and destroyed members of their tribe. Probably the meteor fall that produced the crater happened well within the span of human history, and at a time when civilized communities and flourish- ing cities already existed in some parts of the world. A few other craterlike formations on the earth, including one recently discov- ered in Esthonia, may possibly have been due to meteoric bombardment, but there is no convincing evidence that they orig- inated in this way. Turning, now, to some of the more definitely recorded effects of falling meteorites, we find that in perhaps a dozen cases—most of them dating back many centuries—people were said to have been killed by meteorites. The evidence in all these cases is too uncertain to be conclusive, but, of course, such an event is entirely possible and has probably hap- pened more than once. There have been some narrow escapes even in modern times. Thus at Braunau, Bohemia, in A View across Meteor Crater from the Southeast Wall; Recent Tunneling Has Convinced the Owners the Huge Mass of the Main Meteor Has Been Located Far Underground ant i pet Dee Ge O.. 2. 2? Oe eee ae, a ee es mm et wee tn ot 42s & 2b (eee Om —s— -—- = © - © 6 owe me meee eee ee UCC CeO

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POPULAR MECHANICS 1847, an iron meteorite weighing nearly forty pounds fell in a room where some children were sleeping and covered them with debris, but did them no serious harm. At Charsonville, France, a meteorite fell on a road between two teamsters, throw- ing up the ground to a height of six feet. Roofs have been penetrated in several cases. A dog was killed by a meteorite at Nakhla, Egypt, in 1911. Stories of buildings being set on fire by these bodies are usually taken with a grain of salt by the authorities. The scorching effect of the great Siberian fall was proba- bly due, wholly or mainly, to the compres- sion of the air and was altogether excep- tional. Ordinary meteorites are heated to an enormous temperature during their passage through the air, but the heating is so brief that it is a mere skin effect and the heat is quickly lost when the object comes to rest. Meteorites found immedi- ately after their fall are generally cold or lukewarm, though some have been de- scribed as “too hot to handle.” No bak- ing of the ground or charring of vegeta- tion has ever been observed at the place of fall, except in the one case mentioned. NINE-HOLE INDOOR GOLF SET IMPROVES PUTTING Competitive features help make an in- door golf game more interesting and give the players valuable practice in putting and other strokes. The set is a miniature nine-hole golf course, the object of the game being to sink the balls in the holes from the tee and thereby score the points indicated for each hole on a small flag that automat- ically turns to des- ignate the score when a ball has been sunk. Each player gets nine balls to the game and may play the holes in any order desired. Balls re- turning down the slope may be played over, those remaining on the field should not be removed wntil after the game and those that bounce off the board cannot be played over. 575 Part of the Apparatus Used to Test the Speed of Winds in Tunnel Experiments with Airplanes HOT WIRE MEASURES WINDS IN AIRPLANE TESTS One of the interesting details of appa- ratus used by the bureau of standards to gauge the velocity of winds in the test tunnels, where experiments on model air- planes are conducted, is a hot wire. It is about one-fifth the diameter of a hu- man hair and is electrically heated. Used in connection with an amplifying set, it gives an accurate measure of the speed of the winds as they pass in waves and ripples around the planes under test. ELECTRIC EYES REPLACE MEN AT POWER PLANTS Power stations that run themselves and are watched by electric eyes which record their impulses miles away, are releasing men, who previously performed important but minor duties, to more active and re- sponsible positions in the electrical world. The innovation suggests the time when television may be harnessed to aid the electrical dispatcher, but at present the method is too costly and is not practical. Essentially the same results are being accomplished by the remote-control sys- tem. Signals are sent to a central point and duplicate, on dials and in records, the readings on the instruments in the man- less power plants.

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576 POPULAR MECHANICS Gate as It Appears When Raised; Auto Striking the Cable and Then Stopped by the Action of the Snubbing Mechanism, Which Is Visible in the Upper Part of the Two Photographs at the Right SAFETY GATE STOPS AUTOS AT RAIL CROSSINGS To prevent accidents at railroad cross- ings, a safety gate that halts automobiles before they reach the track, has been in- troduced. It consists of a road arm, raised and lowered like the ordinary cross- ing gate, but, in addition, it has a cable loop which engages a snubbing device. Should the car be driven against this loop, the cable, anchored to the snubbing post which progresses along a guide way, its movements being opposed by friction or by hydraulic means, gradually brings the automobile to a stop without injury to the driver or damage to the car. Un- der a test, a ten-ton truck, driven at a speed of thirty-five miles an hour, was stopped in this way without mishap. HEATING RIVER WITH STEAM PREVENTS FREEZING In 1776, the East river froze sufficiently to allow an army to cross the ice in safety. Put the stream no longer does that near New York, for every hour some 400,000 tons of heated water and steam are sent back into the river from the big power plants along its hanks. The water is used in condensing steam at the plants. Engi- neers estimate that the return raises the temperature of the entire stream at that point at least-ten degrees in spite of the tidal currents that flow in from Long Is- land sound and New York harbor. CARD HOLDER FITS ON FINGERS TO SIMPLIFY PLAYING Persons who have difficulty in holding their A IN ee cards at bridge or Cell as other games are ; served in a cellu- loid holder that is 4 fastened to the fingers with a silk band. It permits arranging the cards easily. @ Flies have their organs of taste located in the feet.

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a. oS owes te we POPULAR MECHANICS THIEF SNARED BY BLUE POWDER SPRINKLED ON PURSES A kind of powder that turns an indeli- ble blue when it comes in contact with moisture, was successfully used by Scot- land Yard detectives the other day in catching a thief who had been taking pocketbooks from a girls’ school in Lon- don. The powder was carefully sprinkled on purses placed as decoys for the sus- pect, a porter at the school. They disap- peared, and the employe was accused of the theft. He indignantly denied the charge, but his hands were stained a bright blue, a fact that caused him to ad- mit his guilt. The perspiration of his hands had caused the powder, falling from the- purses, to change color. AIR GUN TO CLEAN OUT DRAINS SAVES PLUMBING BILLS When drain pipes become clogged, an effective way to clear away the obstruc- tion is afforded in a compressed-air gun which releases an instant blast at thirty to eighty pounds’ pressure. It is pumped up by a hand plunger, a gauge at the top showing the exact pressure, and the air is released simply by lifting a trigger valve. Attachments are provided for using the gun to the best advantage in different places, such as in sinks, washbowls and other units. A reversible rubber cone makes a leak-proof connection between the gun and the drain to be cleaned. Lengths of hose can be used for insertion into crooked pipes. The device has been found especially adapted to cleaning fill- ing-station and soda-fountain pipes. Gun in Position for Being Pumped Up, and Drawing to Illustrate How It Is Used on Sink Outboard-Motor Pump in Operation and as It Is Car- ried to Save Hauling PUMP RUN BY OUTBOARD MOTOR SERVES CONTRACTORS For draining excavations, manholes and similar work, a portable pump that can be carried on the shoulder, is operated by an outboard motor. It will pump nearly 200 gallons of water per minute, saves time and work in moving and is quickly set up. A special feature is the automatic shut-off. A safety device stops the pump when water ceases passing through it. BOY DISCOVERS NEW EXPLOSIVE AND WINS SCHOLARSHIP His interest in chemistry has proved val- uable to Edwin Mulvaney, a Chattanooga, Tenn., high-school. student. He con- structed a small laboratory at home and experimented with chemicals, particularly those of an explosive nature. One of his mixtures was described to the chemical- warfare laboratories and pronounced a wholly new explosive. The bey chemist was awarded a four years’ scholarship at the laboratories.

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By JOHN T. BRADY Wares inthe heavens should we look for the ac- tual center of the visible universe, or to be more precise, the central nucleus of our galaxy, the dis- covery of which has been offi- cially announced by Dr. Harlow Shapley, director of the Harvard astronomical observatory, after years of painstaking research by himself and his associates ? Can it be seen with the naked eye? How far away is it, and what are its dimensions and its composition? Is there a massive core, or nucleus, a supercenter of gravity around which our whole solar system rotates, much as the earth does about the sun? Is it an ordinary collection of bunched stars comparable with that in the vicinity of the sun, or are we in an enormous pinwheel, or spiral nebula, that is swishing the earth around through space on one of its tails, like a boy hanging on for dear life near the end 578 Composite Photograph from Harvard-Observatory Plates, Show- ing the Point in Sagittarius Fixed as the Actual Center of the Visible Universe, Top, and a Diagram Showing the Universe as a Flattened Disk; the Circle Marks Our Own Solar System of the line in a game of “snap the whip”? For centuries astronomers have specu- lated on the problem of the center of the universe. It has gripped their imagina-

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Ofithe Univense The Eyepiece End of a Big Telescope; This Instrument Has Been Built for an Observatory at Kembang, on the Island of Java, Where Conditions Are Good for Observation 579

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POPULAR MECHANICS tion much like the prospect of making gold from baser metals enthralled the fancy of the alchemists of old. But until quite re- cently, in fact, until Doctor Shapley perfected methods of measuring star distances photometrically and applied these methods to the problem of the distances and structures of the star clusters, the solution re- mained an elusive mystery. Ancient astronomers, whose observation of the stars was lim- ited to what could be seen with the naked eye as they tended their sheep, saw only four or five thousand altogether—hardly two thousand at any one time—and believed the earth was the center of the universe. A natural vanity led most early speculators to this assump- tion, in Doctor Shapley’s opinion, and it is not yet extinct. But with the development of the tele- scope, which enabled the scien- tific star gazer to probe deeper into space, sun worship. began to die out in the ranks of the philo- sophical astronomers. Gradually they began to realize that our sun was but one of many millions of stars, and a very tiny one at that. Then speculation as to the cen- ter of the universe began to run riot, and various celestial objects, such as Sirius and the Orion neb- ula, were suggested as being the central place. Measurements of the motions of stars, suggesting rotation about some central mass or masses, led, within the last cen- tury, to the notion that the Pleia- des or Perseus clus- ters might be the controlling bodies, and more recent ex- tensive star counts induced various in- vestigators to locate the center in the Milky Way. Dr. Harlow Shapley, of Harvard, and, Top, Omega Centauri, a Globular Star Cluster in the Southern Milky Way; Bottom, the Southern Milky Way Itself

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POPULAR MECHANICS Copyright, 8. W. Clatworthy Diagram of the Universe; the Abbreviation “L. Y.”” Means Light Years, the Distance Light, Traveling at 186,000 Miles a Second, Will Go in One Year; This Is the Astronomers’ Measuring Unit

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582 Doctor Shapley carefully explained that he had discovered.the nucleus of only that universe with which astronomical science is familiar and which it.can measure at the present time, or in other words, the cen- ter of one particular comprehensible uni- verse, and not the center of centers of all stellar creation. So he describes his discovery-as the nu- cleus of that group of stars of which our sun is one infinitesimal member, and which doesn’t include the tens of thousands of other universes that lie beyond the limits of our galaxy. “Really what we have found,” he went on, “is the central nucleus of a large, very much flattened cookie-shaped system, somewhat irregularly circular, that is composed of perhaps 30,000 million suns. That’s the best numerical estimate we have, but I think the actual number is very much above that figure. And sprin- kled around among them may be any number of planets which we cannot see. “Our sun then is one of about 30,000 million stars that form a great organiza- tion called the galaxy, and the planets, such as the Earth and the others that we see in our solar system, are a very insig- nificant part of it. “When we begin thinking about find- ing the center of the galaxy, therefore, we are faced with a curious problem, for here we are on a tiny little planet going around a dwarf star, and as we look out into space, we see stars in all directions, the nearest one to us being our sun, 93,000,000 POPULAR MECHANICS miles away, and it is twenty-five trillion miles from our solar system to the nearest star.” Doctor Shapley took up this problem in 1915 while he was attached to the Mt. Wilson observatory, at Pasadena, Calif., prior to coming to Harvard, and the method he developed then of measuring star distances photometrically introduced a revolution into the concepts of the uni- verse and paved the way to the discovery of the center of our galaxy. At that time, the diameter of the Milky Way was esti- mated at 20,000 light years and our sun was thought to be near the center of it Realizing that the globular star clusters, which are especially numerous in the southern Milky Way, would be of much importance in studying organizations of the higher orders, and particularly useful in helping to measure the dimensions of our star system, Doctor Shapley first un- dertook to measure the distances of about seventy of them, all that were then cer- tainly recognized. And in studying the famous star cluster in the constellation Hercules, known as “Messier 13,” for example, he found its distance to be about 35,000 light years from the earth. Small stars among the 50,000 in this group were found to be 100 times as large as our sun, while the more brilliant were a thousand times as big as Old Sol. “All of the globular clusters were found to be immensely remote,” he explained, “and at the same time their distribution is UMMM Y WADA MAAK. Was 8 x SQV Our Galaxy as Seen Edgewise, the Small Circle at Left Marking Our Solar System; the Crosses Represent X Globular Star Clusters Outside Our Galaxy, as Diagrammed by Doctor Shapley

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POPULAR MECHANICS 583 such that we can derive from it the form and ex- tent of our whole star system, since they are certainly part of our gal- axy, and probably out- line the whole system of thousands of millions of individual stars. The most remote of these star clusters is so deep in space that light from it requires 2,000 centuries to reach the earth, not- withstanding its incon- ceivable speed of over 11,000,000 miles a minute. “Analysis of the dis- tances and distribution of the globular star clusters indicated that they form a greatly flattened, irreg- ularly assembled stellar system, and that our sun is not in the center of it or anywhere near the center, but halfway to- ward the outer edge. “T got a distance of 200,000 light years as the diameter from one edge to the other, and all my measurements and the high concentration of the globular clusters in the constellation Sagittarius The New Twenty-Four-Inch Telescope for the Javanese Observatory at Kem- (The Archer) intimated that the center was in that region. In order to check up on this, I started, here at Harvard, several years ago, a sys- tematic investigation of the variable stars in a belt twenty degrees in width. To cover thoroughly the Milky Way, we di- vided it into 240 fields, and ever since, night after night, we have been photo- graphing it with four telescopes. The study of these plates will enable us to measure the distances of the variable stars, and a knowledge of their distribution in space will give us more light on the struc- ture of our own galaxy. “About three-fourths of all the variable Stars ever discovered, by the way, have been found by Harvard observers, and the total was only in the neighborhood of 5,000 up to about a year ago. But within bang Has a Six-Foot Tube, Forty-Six Feet Long the last year we have found about 1,000 new ones. We expect the search to go on for ten or fifteen years before we have found all the variables. “One of the first results of our concen- trated effort to fathom the depths of the Milky Way came when, with the able as- sistance of Miss Henrietta Swope, we found a heavy concentration of stars in the constellation Sagittarius at a distance of 47,000 light years from the earth. “Already a dozen or so clouds or clus- ters of the remote Milky Way have been found on the Harvard plates, one of which shows a special cloud of nebule in the constellations of Coma and Virgo, off 10,000,000 light years from our galaxy. Its center is the center of one of the uni- verses of universes.

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584 POPULAR “But the solution of the mystery of the direction and distance to the center of centers—to that remote point in space which is the center of gravity for all the tens of thousands of galaxies—will have to await the completion of our nebular survey which will take from ten to fifteen years more; and it may never be solved.” There is pretty good evidence to show that our whole solar system is rotating about the nucleus in Sagittarius, accord- ing to Doctor Shapley, and he is supported in this view by conclusions drawn by ob- servers all over the world. Doctor Shap- ley estimates the speed of rotation at about 200 miles a second, and looked at from the north side, the direction of rota- tion is clockwise. Unfortunately the actual central point of our galaxy, as determined by Doctor Shapley, is hopelessly obscured from our vision by impenetrable clouds, he explains, but if you are curious to see how it ap- pears to the naked eye, look for it in the southern Milky Way at a point where Scorpio, Ophiuchus and Sagittarius cor- ner together. In the spring, it will be seen due south in the early evening. “What we seem to have found,” con- tinued Doctor Shapley, “is definite evi- dence that the Milky Way has a massive nucleus composed of billions of stars lo- cated in the direction of Sagittarius, but so large that it flows over into Scorpio and other constellations. This nucleus has a diameter of probably 25,000 light years. “But beyond the limits of our star sys- tem, nebulz are scattered through space. They turn out to be other stellar systems, MECHANICS comparable to our galaxy in form and composition. There are hundreds of thousands of them, mostly too far away to be accurately measured, but apparently smaller than our system.” AUTOMATIC BRAKE FOR AUTO PROMOTES SAFETY Brakes are applied automatically as soon as the foot is removed from the acceler- ator in a safety system a Swiss inventor has developed. The brake is on when the car is in neutral gear, but is released with the shift to first-and operation of the ac- celerator. It is said to hold the car on hills without the use of the handbrake and is intended to be of great service in the event of danger ahead. Few drivers forget to take the foot from the acceler- ator in case of trouble, but not all know how to stop the car promptly after that. ENGINE HALF A BLOCK LONG HAS THIRTY-FOUR WHEELS Designed especially to burn a grade of coal of comparatively low heating value, a huge engine constructed for the North- ern Pacific railway is 125 feet long, weighs more than 1,000,000 pounds and has thirty- four wheels, including the twelve on the tender. An interesting feature is the me- chanical stoker which will crush, deliver, and distribute about the huge fire box, more than twenty-two tons of coal an hour. It is expected that the locomotive will be able to haul, in one train, cars that are now made up into two. Powerful, Huge and Yet Easily Managed, This Locomotive for the Northern Pacific Railway Is Especially Interesting Because It Has Been Designed to Burn a Low Grade of Fuel ee n= = oe OL as = «=: = ta @9 im teat cE ot oe Oo

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POPULAR MECHANICS 585 DINING CAR WITHOUT WHEELS SERVES AS SCHOOL Serving in the Model Dining-Room Compart- ment, a Copy of a Car; Student Waiters Are Taught Politeness, Speed and Accuracy While Learning to Set Tables and Pamper Par- ticular Patrons To train cooks and waiters under con- ditions resembling, as nearly as possible, those encountered on an actual run, the Pennsylvania railroad has built exact du- plicates of dining cars in three commis- sary buildings and now maintains schools at New York, Columbus and Chicago. Every feature, from cooking utensils, range, broiler and pantry, to the dining room and table for patrons, has been re- produced precisely. Even the familiar aisles and corridors have been retained and made to conform exactly with the standard dining-car specifications. In fact, everything is almost exactly the same except that the stationary school does not move. But, officials declare, after waiters have been trained in a schoolroom of the same proportions as the place in which they are later to work, they have less dif- ficulty in balancing trays and passing around corners, even when the car is crowded and the train is speeding around Chefs Teaching Pennsyl- vania Railroad Cooks Some of the Fine Points of Preparing Cuts of Meat; the Schoolroom Is an Exact Duplicate of a Real Dining-Car Kitchen; the Railroad’s Yearly Requirements for Meals Include 2,000,000 Pounds of Meat and Fowl acurve. The average dining-car employe spends about three hours at school each week while assigned to his regular run. At intervals, he is detailed to the school for a week or more of intensive training. Under a staff of specially trained instruc- tors and supervisors, cooks learn how to prepare various cuts of meat, and poultry of all kinds; how to make sauces and dressings, and they become familiar with the special utensils used on a dining car and also become accustomed to working within the restricted space afforded in a dining-car kitchen. The schools have been established largely because of the railroad’s extensive dining-car operations and the difficulty of giving instruction in an ordinary kitchen or schoolroom. The line now has 183 dining cars which serve an average of 12,000 meals daily, or ap- proximately 4,000,000 a year, and are using 2,500 tablecloths and 15,000 napkins every day the year around.

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Corner of a Graveyard for Motor Cars That Have Outlived Their Usefulness in St. Louis; No Car That Enters the Yard Leaves Again under Its Own Power NEW style of establishment for the efficient disposal of aged automobiles which menace public safety has been fos- tered by the organized motor-car mer- chants of St. Louis. These dealers have banded together in a traffic-safety campaign to eliminate veteran cars with defective brakes, steer- ing controls, and similar imperfections, from arterial highways and intersecting streets. Their co-operative undertaking plant is an efficient salvage station where all but the squeaks and rattles from old cars are reclaimed. This salvage station is quite different in operation from the ordinary automotive junk yards. Its rigid rule is that every car purchased must be dismantled. The majority of the cars are delivered at the plant under their own power, but that trip is their touring swan song. Dilapidated automobiles are purchased ‘by the thou- sand both from the dealer members of the association and from the general public. The prices paid range from $2.50 to $40, the average automobile being bought for $20, The salvage is so complete and de- tailed that $40 worth of accessories, repair 586 parts, equipment and raw manufacturing materials will be recovered from each machine and sold. The plan not only accomplishes its pri- mary purpose of ridding the congested streets of dangerous cars, but it brings this to pass at a profit. The salvage yard has fixed $100 as the minimum price for used cars which the reputable dealers will handle. They hope to raise this limit to approximately $200 during the next year. All cars of lower value are catalogued as unsafe, and are delivered to the salvage station as automotive “sacrifices.” The batteries, generators, starters and radiators are removed from the cars, in- spected and tested. If found in good or- der, they are reconditioned and sold di- rectly through the retail shop connected with the salvage plant under a ninety-day guarantee. These parts usually are in fine serviceable condition even though re- moved from worn-out machines, because they are replaced periodically and main- tained better than the millrun of working parts in the old automobile. In wrecking the cars, the windshields as well as the window glass in closed cars th lin ar fe Cz be

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a0) One of the Powerful Electric Shears That Bite Ancient Automobiles into Small Pieces, Ready to Be Melted Down and Used Again; It Is Working on a Pile of Rims are removed, sorted and graded as to size and model of auto which they will fit. The ordinary junk man rips all upholstery from the car and burns it. The St. Louis wrecking establishment reports attractive returns from the salvaging of moss, hair, cotton, burlap and leather from upholster- ing. This project pays the entire ex- penses of its acetylene-torch shop, where the motors are removed and the chassis dismembered. An electrified monorail system removes the motors from the torch shop and de- livers them to the yard unit, where they are scrapped in order to recover the dif- ferent metals they contain. Bronze, high- carbon steel, number-one melting steel, bearing metal, copper, aluminum and cast iron, which are sold for from seven to twenty cents a pound, are reclaimed from the engines. Some bodies are removed and sold in- tact for from $25 to $50 apiece, but the majority of bodies, fenders, steel tire rims, rear axles and other worn-out parts are chewed into smelter material, called “busheling,” in the jaws of mighty elec- trified shears. When working at capacity, one of these shears will reduce fifty ordi- nary automobile bodies, fenders and other discarded equipment into metallic mince- meat in one day. This busheling sells for an average price of $8 a ton. The macerated material is allowed to accumulate in huge piles until some ten carloads of the junk are ready for ship- 587

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POPULAR MECHANICS cars. This magnet lifts 500 pounds of the mate- rial at a time and elimi- nates costly hand labor. The sorting and grading of salvage metals is so thorough that the steel mills pay premium prices for the metal mincemeat which is unloaded, also by magnet, directly from the cars into the fur- naces. The automobiles which owners have sold to the salvage experts subsequently may come home again to roost in the form of new radi- ators, boilers, bathtubs or plumbing fixtures. Building contractors buy old automobile springs by the ton from this St. Louis salvage en- Me, oan, My sat Lente foe SEL Sg Sey: tM terprive, The springs subsequently serve as ment to the smelter. A powerful electro- ideal reinforcement for new concrete con- magnet is used in loading the scrap on flat struction and are in keen demand for that Tires, Batteries and Generators, Along with Other Kinds of Parts, Are Salvaged and Resold for Further Use; Thousands Are Put Back on the Roads Each Year

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POPULAR purpose at $20 a ton. Everything else that is merchantable is also reclaimed and sold. Repair parts for practically all types and models of American and some foreign automobiles are obtainable at low :prices at this hatchery of new automotive trade ideas. Its originators hope to see this St. Louis scheme of co-operation in the sal- vaging of venerable and crippled motor . cars flower into a national organiza- tion. This body, as visualized in motor- world day dreams, would be the coun- try-wide core of chains of salvage stations which would speckle the 2 N Closed Bodies, if in Good Condition, Are Resold at From $25 to $50 Each; Bottom, Portable Torches Cut Up the Scrap American map. If every large city sup- ported such a co-operative plant, it would not take long to exterminate unsafe mo- tor cars‘from the traffic picture. Such a project would also aid in stand- ardizing and stabilizing used-car values and would force out of business the fly- by-night sandlot dealer who barters in “anything and everything that will run.” Of the 25,000,000 automobiles now in use in the United States, at least one-sixth are possible “death cars” that are unsafe to operate in city-speed congested traffic or in open-country running, where many drivers travel at racing speed. MECHANICS 589 The menace of these roving auto- mobiles — breeders of future tragedies —must be faced and then effaced from county, state and national highways. The St. Louis plan at least is a step- ping stone toward this goal until some better plan, if any, is devised. ELECTRIC HEAT “BY THE FOOT” REPLACES STOVE For warming small rooms and restricted spaces, an electric heater in the form of a slender bar, two feet long, has been intro- duced. It is thoroughly insulated, can be installed almost anywhere and operates with direct or alternating current. It is especially adapted for service in watch- men’s houses, garages, vaults and show windows, and may be used singly, in pairs or in groups, as required. Electric Heater, and Illustrations of Uses

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590 POPULAR MECHANICS FILTERS SALVAGE COAL DUST FLOATING ON RIVER Coal dust, floating on the river Ebbw, which flows into the Bris- tol channel in England, is to be reclaimed and used for heating purposes, by installing settling ‘tanks and filters where the stream drains the land around the mines. Besides purifying the water, the plan is expected to make availa- ble considerable quantities of fuel at prices lower than the present scale for grades of correspond- ing quality. SPEED-SHIFT WASHER DOES BETTER WORK One of the most interesting im- provements in washing machines Spraying Man with Gas That Freezes Fires; It Causes age to Fabrics When It Dries FREEZING GAS CURBS FIRES AND REDUCES DAMAGE Improved apparatus has been developed by several fire departments for the use of carbon-dioxide gas in extinguishing blazes. This vapor freezes as soon as it is released from its containers and, by lowering the temperature of the surround- ing area and cutting off the oxygen sup- ply, is effective in putting out fires. When it melts, it entirely disappears without leaving a stain and is therefore especially suitable for use in quenching fires in stores and other places where the goods would be damaged by water. ALUMINUM MIXED WITH GOLD AIDS DENTAL WORK Aluminum is combined with other metals, according to reports of processes developed by a San Francisco inventor, to form valuable alloys. With gold, a hard, light alloy is prepared; a silver mix- ture so hard that it can be sharpened to a razorlike edge is also made, and copper is made suitable for use in tools. The gold alloy does not oxidize, it is said, making it especially useful in dentistry. is an electrically operated outfit that has a speed-shift arrange- ment which requires no clutch or gear mechanism. Its speed is regulated simply by turning a small handle. The machine can thus be used more efficiently for washing different fabrics, some being cleansed better at low rather than high speed and not so likely to be torn. Fur- thermore, the speed shift prolongs the life of the washer and the absence of a clutch and other bothersome mechanisms is a great convenience to the housewife. The washer is the invention of an automobile engineer and is in line with similar im- provements being developed for cars to eliminate gear shifts on them. No Dam- Cross Section, Which Shows Gear-Change Plan, and, in Insert, the Control Handle

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POPULAR MECHANICS 591 “BARN-DOOR” MILL HARNESSES THE DESERT WINDS r eg “4 4 n e [- | it 5 View of the Entire Mill, and One of the Blade Units, Showing Size and Arrangement si Travelers near Fresno, Calif., are some- = times startled to see what appears to be a at number of barn doors flying through ” space. Closer examination shows that ° the rig is a sixteen-bladed windmill which ed a Dutch inventor has devised to run two he pumps and a dynamo at the same time. ly Oddly enough, a barn door was the in- ng spiration for the idea. The inventor once gh watched a ranch hand trying to close a 4 barn door against the wind. The diffi- = culty of the task prompted the plan of ch building a mill with large, flat blades like - those of a paddle wheel. The idea was he developed, the blades being arranged to ile turn a shaft which was geared to the pe pumps and the dynamos. An advantage and, of the scheme at this particular farm is that the mill is placed where no obstruc- tions reduce the force of the wind so that a high tower is unnecessary. At the same time, the inventor has devised a way to decrease the resistance from the back stroke of the blades by erecting a wooden wall which covers the lower part of the mill at the rear. Under favorable condi- tions, the rig is said to be the equivalent of a fifty-horsepower plant. A_ steady stream of water is afforded by the two pumps. RADIO RECORD ON DICTAPHONE SPEEDS NEWS REPORTS Radio and the dictaphone have been linked in Oregon to speed the distribu- tion of stock-market reports. The radio voice is recorded directly on dictaphone cylinders from which a stenographer pre- pares copy for the newspaper presses. The experiment was successfully per- formed under the direction of the state agricultural college to insure the speedier distribution of market reports through- out the rural districts, and adaptations are contemplated to make possible the con- tinuous recording of similar broadcasts.

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592 POPULAR MECHANICS FORTUNES THROWN AWAY IN LITTLE THINGS By stopping leaks in faucets, New York city saved 400,000,000 gallons of water in one year. Gas companies estimate that tiny leaks in jets and mains cause a loss of mil- lions of cubic feet of gas each year, and an Eng- lish expert declares that some 4,000,000 bottles of medicine are wasted an- nually because the aver- Model of Proposed Hotel for Lake Resort; the Boatlike Promenades and a Good View BIG HOTEL IN FORM OF BOAT FEATURES LAKE RESORT Modern ideas predominate in a hotel a German architect has designed for erec- tion in one of the lakes near Dortmund. It is to be built in the form of a boat and has wide promenades like inclosed decks, a coffee terrace, dance pavilions and large dining rooms overlooking the water, be- sides the usual hotel rooms. A special feature is to be the illumination both in- side and out. At night, rays from thou- sands of electric lights will make the hotel visible from great distances. A fine view is enjoyed from most windows. SLIDING-BEAM COMPASSES PROMOTE ACCURACY Designed to eliminate the faults most frequently found in ordinary compasses, a new instrument is made in the form of beam compasses, but small and light enough to be used with one hand. It is claimed that the point of these compasses will not slip and tear the paper, and the adjustments are such that no small errors can occur in setting or in frequent use. The instrument will draw circles up to eight inches in diameter. Pian Permits Wide age teaspoon holds more than the usual dose. An engineer has_ estimated that it takes 2,434,026 tons of coal yearly to generate steam enough to blow the whistles on the railroad engines in the United States and that more than a mil- lion pounds could be saved if the whistles were moved slightly forward and adapted to a single high-pitched note. In Eng- land, 70,000,000 telegram blanks find their way into the wastebaskets every year. SAFETY. THROTTLE FOR AUTOS HELPS SAVE GAS Greater safety in driving, econ- omy in gasoline, and convenience are some of the advantages claimed for an ac- celerator-control throttle attached to the gear-shift lever. It permits shifting from one speed to another without removing the foot from the brake pedal, prevents killing the motor and pro- vides the “extra arm” so often needed while driving in crowded traffic. The de- vice is attached in a few moments, and no alterations in the car are required. It provides an easy way of operating the accelerator by hand instead of by foot control and at the exact time when more gas is needed. ar >.

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no ot pre POPULAR MECHANICS 593 With the Engine Placed behind the Driver and His Mechanician, the New English Speed Boat, Which Is Coming to America to Race, Presents an Unusual Departure in Design ENGINE IN EXTREME STERN OF NEW SPEED BOAT A twenty-six-foot hydroplane, powered with a 900-horsepower 12-cylinder Napier airplane engine, is being brought to America by Maj. H. O. D. Segrave, the famous racing-car driver, to attempt to lift the world’s speed record on the water He is bringing his new racing car, the “Golden Arrow,” to attempt the same feat on land. The unusual feature of the boat is that the engine has been placed in the extreme stern, with the pilot and mechanician in front of it, reversing the usual arrangement. The position of the engine is expected to increase the plan- ing action of the one-step hydroplane hull at high speeds. The engine is similar to that in his racing car, and is the same type that was used to win the Schneider cup from Italian flyers last year at Venice. Reports from England rate the boat at over eighty miles per hour, but this speed will have to be exceeded to better the record set at Detroit last September, when Gar Wood’s “Miss America VII” aver- aged 92.834 miles per hour in six one-mile dashes. ALL UNDER THREE FEET RIDE FREE IN BUSSES Height, not age, is to be the determin- ing fare factor on an eastern motor-bus line. All persons thirty-six inches tall or less, will be carried. free. Those taller will pay the fare regardless of their age. To prevent disputes, a height gauge has been installed on the doors of the vehi- cles. Children whose heads overtop the mark must pay. LOUD SPEAKER FOR TELEPHONE LEAVES HANDS FREE To amplify the voice from the telephone, a loud-speaker attachment has been de- vised so that the listener does not have to hold the receiver. An arrangement is also provided whereby the hookup may Telephone Conversation Being Amplified through the Loud Speaker Attached to Receiver be connected with a radio combination on the telephone instrument.

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By C. MORAN EN who eat corn mixed with liquid titanium tetrachloride, a chemical used to make military smoke screens ; who subject themselves to the deadly carbon monoxide of automobile exhausts; wh« handle chemicals, a single drop of which eats flesh to the bone, are experimenting at Edgewood arsenal, Md., in the produc- tion of new war gases and chemicals and in the utilization of these elements in in- dustry. Recent research at this laboratory has shown that the useful life of rubber may be prolonged by treating it with certain anti-oxidants; that the minute, natural “one-man tanks” of the seas—the marine borers—which have sent to the bottom more wooden ships than all the guns of war, can be halted by Lewisite, a deadly warfare chemical. A toxic paint has been developed to prevent the formation of barnacles on the hulls of ships, which cause an annual Joss of $75,000,000 in fuel alone. Barnacle is the term commonly used for al! marine organisms which attach themselves to the 594 bottom of ships, but the barnacle itself is but one of a number of such or- ganisms, although the principal one. These growths accumulate rap- idly on the hulls, some- times projecting many inches. Only a fraction of an inch is necessary, however, to impede materially the ship’s progress. Increased SG A ES TE Testing Poison Gas on Plants at Edgewood Arsenal, and Field Truck Used to Measure Gas Content of Air; It Is a Complete and Compact Gas Laboratory and Does Away with the Chance of Errors fuel vess bart time ty-fi dry for the clea on vess latit gro} the troy the pers dev che: on test rela hot cold seer alen ists, are smc pla: Son fell sub farr dan wer was tetr fort chic har: eate and mix tetr

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senal, f Air; y and fuel consumption of a vessel handicapped by barnacle growth some- times amounts to twen- ty-five per cent. Every vessel must be drydocked periodically for barnacle cleaning, the frequency of such cleaning depending up- on the service of the vessel as to seasons and latitudes. The marine growth is active during the entire year in the tropics and only during the summer in the tem- perate zones. The paint devised by the war chemists is being used on destroyers in final tests to determine the relative life and cost of hot plastic paints and cold varnish paints. The erroneous idea seems to be quite prev- alent, say these chem- ists, that all chemical agents of warfare are toxic. In a recent demonstration, a smoke curtain was dropped from an air- plane which was passing over a cornfield. Some of the liquid titanium tetrachloride fell on the leaves and ears of corn which subsequently became discolored. The farmer claimed that his crop had been damaged and demanded reparation. A number of the more discolored ears were sent to the arsenal for test, and it was disclosed that neither liquid titanium tetrachloride itself, nor the products formed when it produces smoke—hydro- chloric acid and titanium oxide—are harmful to eat. The discolored ears were eaten without producing any bad effect and the same was true with grains of corn mixed with a small quantity of titanium tetrachloride. All the discolored corn NN = Ot NET SR I ' Not a Spiderweb but a Hemispherical Vision Chart, Used to Measure Angle of Vision of Various Gas Masks was purchased and fed without injurious results to the live stock at the army post adjoining the cornfield. The pestilence of certain species of birds which are harmful to agriculture or which deface buildings has long been the sub- ject of investigation by the biological sur- vey. Recent experiments have been made in endeavoring to exterminate these spe- cies by the use of chemical gases, but curi- ously enough the birds emerged from the gases unhurt. It was found that birds have rather marked resistance to toxic gases, and furthermore, that it is difficult to build up, out of doors; sufficiently high concentrations of these gases to be ef- fective over extended areas. During the war it was noted that pigeons almost always returned to their cages safely when liberated in a gas cloud. This 595

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POPULAR MECHANICS Fumigating a Bakery Badly Infested with Flour Weevils; Deadly Poisons, in Bags, Are Dropped into Jars Containing Another Poison to Create the Clouds of Lethai Gas was quite a mystery until it was realized that the pigeons escaped by rising quickly above the gas. The tests showed that crows attempt to fly out of the gas cloud in the same way as soon as its irritating effects are felt. Methods of extending the life of rubber many times its normal life have been de- veloped as a result of experimentation to prevent the rapid deterioration of the hose tube, facepiece and exhalation valve of gas masks. Such deterioration made difficult the problem of maintaining a war reserve of gas masks. Initial tests re- vealed that methods of curing rubber had an important effect upon its life. Under- cured stock, lacking sufficient sulphur, be- comes soft and even sticky with age, while overcured and bloom stock, containing an excess of sulphur, becomes brittle and cracks. As a result of the tests, faulty cure has been corrected and facepieces are now molded individually. This has de- veloped an increase of the useful Jife un- der normal storage conditions from a few years to approximately thirty-five years. Another improvement in rubber has been developed with anti-oxidants. These chemicals, when incorporated in rubber compounds, materially reduce or retard rubber deterioration due to oxidation. Tests indicate improvement that may pro- long the useful life of rubber to sixty years. For protection against sunlight, a compound has been developed of rub- ber, pigments, dyes, and softeners dis- solved or dispersed in a suitable solvent. Methods of storing gas masks in inert atmosphere, such as nitrogen, also have been devised. The marine borers have been halted by Lewisite in the hands of the government chemists. Indications are that battles, started long before the sinking of the Spanish Armada, now have been brought to an end by the application of a deriva- tive of Lewisite in the path of the disas- trous marine borers, such as the teredo, bankia, martessa and limnoria. These mollusca and crustacea have been recorded in history as being respon- sible for the sinking of many ships of the Spanish Armada and of boring to weak- ness the timbers of the dykes of Holland, and they have caused mifllions of dollars of damage to the wharves of the world by eating the wooden piling. Creosote long has been applied as @ temporary barrier to these pests, but for many years the war-department chemists wa th tiv vit

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have been experiment- ing upon a more perma- nent defense. Tests have been completed to show that organic compounds of arsenic, mercury and copper have been of the greatest general toxic value against the marine borers. Of the arsenicals tested, those which were either chemical agents of warfare or derivatives of these chemicals were most effective. A deriva- tive of Lewisite—chlor- vinylarsenious oxide— POPULAR MECHANICS Apparatus Used to Test War Gases on Human Beings, and, Above, One of the Side-Line Developments; Treating a Race Horse with Chlorine as a Cold Cure; the Gas Treatment Is One of the Accidental Discoveries of ar Days Which Has Proved Successful in Peace has the highest toxic value. Solutions of the fol- lowing compounds in creosote have stopped the borers from passing into the treated portions of test piling after they had riddled bait strips at- tached to the piling: cop- per orthonitrobenzoate, mercury benzoate, mer- cury resinate, mercury stearstemdiphen ylamine- chlorarsine. Straight creosote impregnations did not stop the borers. Following a recent ex- plosion in an Alabama coal mine, eight men

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POPULAR Testing the Tensile Strength of Rubber Treated with Chemicals That Prolong Its Life to Sixty Years cee a EEE atte Ss MECHANICS were trapped in the fifth right heading, their only means of escape blocked by afterdamp, the gaseous products of the explosion containing the deadly carbon monoxide. Two of the men who tried to make their way through were overcome by the gas and died. The others waited for help and, when equipped with self- rescuers, the chemical filling of which is a product of chemical-warfare research, made their way through unharmed. The self-rescuer is a commercial pocket- size respirator consisting of a canister which is fitted with a mouthpiece, nose clip and exhalation valve. The chemica! filling of the canister, which eliminates carbon monoxide from the air breathed, is a mixture of metallic oxides, known as “hopcalite.” Hopcalite is employed not only in the miners’ self-rescuer, but also in gas masks for firemen and other work- men who may encounter dangerous con- centrations of carbon monoxide. It is also used in carbon-monoxide recorders and alarm devices, such as in the recently the firedamp a oe UAR # at rrvryrie * e In Developing Commercial Uses for New Chemical Mixtures, the Army Gas School Uses This Tank Ap- paratus to Test the Effects of the Gases on the Human Constitution

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POPULAR MECHANICS 599 constructed underwater Holland tunnel between New York and New Jer- sey. Prior to the discovery of hopcalite, there was no type of gas mask which would provide protection against carbon monoxide, other than the oxygen inhalator, a cumbersome type of equipment’ which is a self-contained mask with its own supply of oxygen. It was discovered, ulti- mately, that a specially prepared granular mix- ture of the oxides of cop- per and manganese will change carbon monoxide when mixed with oxygen of the air, to carbon di- oxide, a relatively harm- less gas. This mixture of metallic oxides is called “hopcealite” in honor of the two universities, Johns Hopkins and California, where the basic principles were evolved. AUTO VALVE-SPRING TESTER HELPS SAVE GASOLINE Balanced springs insure better perform- ance of the automobile motor with conse- quent saving in gasoline, faster pick-up and other advantages. To detect weak and faulty springs, a simple tester has been introduced. It is arranged so that the springs can be tried while in the block or when removed, and operates ac- curately. The en- tire test can be made in a few moments. The state of the springs is determined by a gauge. @It takes about two years for a baby whale to grow to an adult. Composite Drawing of Proposed Traffic Plan in Paris, Where Double-Decked Streets and Cross-Overs Are under Consideration TWO-LEVEL STREETS PLANNED TO SPEED PARIS TRAFFIC One of the plans under consideration for relieving the traffic situation in Paris involves the building of two-level streets. An elevated pavement would be provided for pedestrians only, and the stores would have entrances and show windows on this level. Bridges would be constructed at street crossings. The level for vehicles would have space for parking cars and stairways would be provided at convenient locations. A feature of the plan is the concealed tubular lamps which would eliminate need of electric-light standards. TWO MILLION PENNIES A WEEK USED BY BIG STORE Pennies at the rate of seven tons a week were used by a large New York depart- ment store during the holiday season. One reason for the huge demand was the fact that most of the merchandise was priced at odd figures, and as the store’s business is done on a cash basis only, pen- nies were needed for practically every transaction to make the proper change.

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POPULAR Demonstrating the Table Basketball Game; the Ball Is Sent into Baskets by Striking Projecting Sticks BASKETBALL PLAYED ON TABLE LATEST PARLOR GAME Table basketball, a game devised by a student at the Kansas agricultural college, has appeared in the form of a simple out- fit that will amuse the players as well as spectators, and also test the skill. It con- sists of a metal box, the top of which is a cardboard field, depressed in the center to permit the ball to roll into any one of a number of holes along this part of the field. At either end is a small woven basket on an upright. By striking down on the end of small sticks or levers that extend under the field to the holes and project a short distance at the sides, the ball is thrown up out of the hole and, if properly propelled, falls into a_ basket, scoring two points for the player. The sticks on one side MECHANICS INSECTS AS LEPROSY CARRIERS STUDIED BY DOCTORS Studies are being conducted by the army research board at Manila to discover if insects may not be carriers of leprosy. The investigation was started several months ago and, although but one case of transmission of the disease by a mosquito has been definitely recorded, the experi- ments are still under way. The insects are allowed to visit leprosy patients and then to bite volunteer subjects, men who, with the permission of the late governor- general, have been selected from among prisoners serving long terms. After more than sixteen months, none of the volun- teers has been affected, but this is not long enough for final decision in the mat- ter, and it is pointed out that none of the subjects may be susceptible to the disease. The cause of the spread of the malady is still a mystery. Married couples, one of whom has leprosy, have lived together for years without the other one acquiring the disease. Climate and density of popula- tion have been thought to have some con- nection, but they alone cannot be the reason for the spread of leprosy, studies have shown. Insects do not always ac- quire the germs after feeding on leprosy patients and, in the rare instances when they do, they do not always immediately bite a well person, but doctors still be- lieve that mosquitoes, flies, fleas and other insects may be at least partly to blame. CARDBOARD MAKES SOUND BOX FOR PHONOGRAPH As a substitute for the usual sound box on phonographs, a Swedish inventor has de- vised a way to make reach only certain holes and those on the other, reach the rest, so that oppos- ing players can “shoot.” If the ball is struck off the field, a foul is counted and the other player enjoys a “free throw,” a chance to shoot for ordinary cardboard amplify the tones reproduced by the needle. The card- board is simply bent and mounted as indicated in the accompanying . illustration and at- tached to the nee- dle by a special mechanism. The a basket just as in the real game. Bent Cardboard, Which Is Said to Give Results as Good as Those of the Usual Phonograph Tonearm invention has been patented.

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POPULAR MECHANICS 601 WHALING HAS CHANGED SINCE MOBY DICK’S DAY Modern Whaling off California Coast Little Resembles the Work That Made Bedford Famous; Whales Are Hunted by Fast Motor Tugs, Shot with Four- Prong Harpoons That Pass Entirely through the Body, When the Prongs Spread to Hold It Fast, and Then Buoyed and Left Until Several Are Killed and All Are Towed Ashore and Cut Up on Land

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602 . POPULAR MECHANICS cation removed some of the stain until it had been nearly obliterated. A shed was built over the monument during the process to permit warm- ing the chemicals. FUEL OIL REPLACES GASOLINE IN BUSSES Successful use of a heavy fuel oil instead of gasoline to run motor busses is reported by an eastern company. This has been made possible by equipping the engine with a special unit, the invention of a New Zea- lander, consisting of an aluminum pot in which is a nest of thin, curving plates, radiating from a central core. This device is said to help convert the oil into a dry gas be- fore it is passed into the intake manifold. Substi- The Fire at Its Height, Burning in the Upper Stories of Uncompleted Chicago Skyscraper on a Winter Night FIRE HUNDREDS OF FEET IN AIR TESTS FIGHTERS’ SKILL Scaffolding, and other wooden parts in a skyscraper under construction in Chi- cago, caught fire forty stories above the street when the temperature was nine de- grees below zero, giving firemen a busy hour before the flames were extinguished. Hose had to be hauled up by hand, while ice and wind added to the difficulties. RED INK STAINS ON MARBLE REMOVED WITH LIME When vandals disfigured the Ypsilanti monument at Ypsilanti, Mich., with red ink, city officials were perplexed as to how to remove the stains. A paste was pre- pared, chiefly of chlorinated lime, and spread over the statue. After it was dry, it was removed with a trowel and a fresh coating applied. Each succeeding appli- tution of fuel oil for gas- oline is being watched by engineers who point out that it would mean an annual saving of not less than $50,000,000 simply in the operation of motor busses, LONG PLIERS FOR MANY USES AID IN SHOP AND HOME Adapted for picking up almost anything from a thread in weight to ten pounds, specially con- structed pliers have many uses around automo- biles, in the shop or home. The tools weigh but two ounces and are thirteen or seventeen inches long. Putting in valve locks, remov- ing corks from bottles and fastening or re- moving nuts, etc., are a few typical uses. U

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of 1e 1e n- Se en Ve > CO =e eS S ™S Dee AS es . ~P, re : SL ee ee f ci WONDERFUL new metal, one-third lighter than alu- minum and with most of the val- uable properties of steel, will soon be placed on the market. A Long Bar of Beryllium and a Short One of Steel, Both of the Same Weight, and Chart Showing the Position of the Metal in the Elec- tronic Scheme Assuming that its cost is not prohibitive, its use will greatly reduce the weight of airplane engines, and providing its price eventually becomes low enough, it may also be largely employed in auto- mobiles with vast reduction in weight. The name of this new metal is beryllium, a chemical element like iron, copper, alu- minum and lead. While it is too early to state positively just how extensively the material will be utilized, a preliminary investigation suggests that, when it is suitably alloyed with other metals, it may be employed almost any place where iron, steel and aluminum are now used. If this view proves correct, airplane engines of the future may be built almost entirely of beryllium, weighing perhaps half as much as similar engines today which are mainly constructed of steel, cast iron and alumi- num. Strictly speaking, beryllium is not new. That is, it has been known for more than a century, but during all these years scien- tists have been unable to develop a suit- able process for the extraction of the metal from its ores. Recently, however, a Cleve- land scientist and metallurgist, Hugh S. Cooper, and his associates have devel- oped a patented process which permits production of the metal on a commercial scale, and definite steps are now under way for its manufacture. The existence of beryllium was first indicated in 1797 by Vauquelin, a French investigator. Early scientists tried to re- duce the ore to secure the pure metal, but it was not until 1828 that Wohler, the cele- brated German chemist, succeeded in pro- ducing a laboratory sample. Since that date, various experts all over the world have tried to develop a commercial process but, in spite of their efforts, beryllium re- mained a laboratory curiosity until Cooper worked out his method. Many people have the idea that beryl- lium is a rare metal, but this is far from 603

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POPULAR MECHANICS $7.00 a pound and refinements on this method later cut the price to about twen- ty-five cents a pound. The future history of beryllium, it is to be hoped, will show a similar price trend. Pure beryllium is a dark gray metal which takes a high polish like steel. In fact, a polished specimen might be mis. taken for steel until it is picked up, and then it is realized that this stuff that looks like steel is much lighter than aluminum. i It is so hard that it

true. In the United States alone, the ore oc- curs in more than fifteen states and is especially available in Colorado, South Dakota, Connect- icut and New Hampshire. In the last state, there is a whole mountain of beryl, a hard, stony substance

cannot be scratched with a file, and since there is a close rela- tionship between hardness and strength, the pure metal compares with steel rather than aluminum in this respect. Beryl- lium is about. five times as hard as aluminum.

composed of the oxides of beryllium, aluminum and silicon. In short, there is plenty of beryllium ore all over the world, and the rareness of the metal heretofore has been due entirely to the difficulty in separating it from the other elements in the ore. It is still too early to say just what the eventual price of beryllium will be, but experience with the development of other metals suggests that the price will be fairly high at first, gradually being re- duced as the scale of production increases and still further improvements in methods of manufacture are worked out. In so far as cost is concerned, the future his- tory of beryllium is likely to parallel the past history of aluminum. Aluminum ore was discovered in 1700 but separation of the metal from its com- ponents was so difficult that it was not until 1828 that Wohler produced a few particles in his laboratory. Others im- proved the process so that a few years later aluminum could be bought for $115 a pound. In 1854, Deville devised a new method which brought the figure down to

A Small Cast-Iron and Much Larger Beryllium Pis- ton, Both Having the Same Weight; H. S. Cooper, Who Developed the Commercial Extraction Process, and the Three Steps, Beryl, the Rock, Beryllium Oxide, in the Bottle, and the Metal While pure beryllium is very hard, it is also brittle, and for most purposes its brittleness must be reduced by alloying it with various other metals, such as alu- minum, copper and iron. Beryllium and aluminum may be alloyed in all propor- tions, and this is quite fortunate, because one of the chief difficulties in securing pure beryllium lies in the elimination of the aluminum also found in the ore. Hence it is cheaper to make a beryllium- <A fe ef oe Sek ok 6 6 ae (6 ee

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— | Va Ov POPULAR MECHANICS 605 aluminum alloy than it is to produce the pure metal. Beryllium, of course, is so new that most of the possible alloys of this ma- terial with other metals have not yet been made and tested, but what has already been done suggests that in a reasonable time an amazing beryllium alloy will be discovered. DISTANT SWITCH STARTS AUTO SAVING DRIVER TIME For speedier response to fire alarms, an officer of an English fire brigade has de- vised a remote-control starter for the motors of the apparatus. Throwing a switch in the office, or other convenient location, starts the engines of the cars so that they are ready to go the instant the driver reaches his seat. The device can be applied to private uses. Physicians, for instance, could install a switch in their bedrooms and start the auto engine run- ning at the distant garage so that time would be gained in answering a call. HOLDER FOR BABY’S BOTTLE FITS ON HIGH CHAIR Attachable to a high chair or baby car- riage, a holder for the nursing bottle is made of spring wire, covered with white rubber. It prevents the infant from spill- ing the milk or breaking the bottle. Bottle Holder on Baby’s Chair Prevents Breakage and Spilling; It Is Covered with Soft Rubber Model of Proposed Lifeboat-Lowering Rig, a Track down Side of the Vessel Instead of the Usual Davits LOWER LIFEBOAT ON TRACK TO PROMOTE SAFETY A means for the safer and more rapid lowering of lifeboats has been developed by Capt. A. T. Nelson, of Milwaukee, Wis. Instead of the usual system of davits, he has introduced a track which follows the side of the vessel and permits the boat to be lowered to the water on two rails. They hold the small craft from swaying or tipping and are not likely to be obstructed by ice. THREE-STORY HOUSE OF GLASS Plans have been completed for the con- struction of a three-story glass house on top of a New York building. It will be made of glass “bricks,” translucent but not transparent. They will be connected by concrete and steel reinforcing. Inter- esting effects in lighting will be produced at night, when the house is illuminated from within, the architect promises.

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606 POPULAR MECHANICS “ROBOTS” THAT WALK AND TALK, SIT AND STAND, Below Is Capt. A. J. Rob- erts’ Mechanical Man, an English Invention, in the Act of Sitting Down Fol- lowing a Verbal Order ‘A ; ‘ A Stage Demonstration of What a Brainless Brain Child of Professor Popjie Can Do; “Radiana,” the Wireless Barber, Is Shaving a Cus- tomer, While the Human Guardian Stands by to Make Sure the Razor Doesn’t Slip; at the Top Is a Me- chanical Traffic Policeman Used in Berkeley, Calif., to Supplement More Conventional Traffic Signals; the Tiny Policeman Turns to Face the Direction in Which Traffic Is to Be Stopped, While Bells Sound a Warn- ing; the Pedestal Is Also Equipped with a Fire Siren to Stop All Traffic in Case of Emergency; by Combin- ing Wireless, Spesking Apparatus, and the Necessary Motors and Gears, It Is Possible for a Clever Inventor to Reproduce Any Form of Motion ecm a — te uti che eee ene bees of

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POPULAR MECHANICS 607 DO EVERYTHING, IN FACT, BUT THINK FOR SELVES The Weird “Monster” Above Is a Planetarium, Capable of Throwing on a Domed Ceiling the Planets and Stars as They Are, Were or Wil) Be at Any Date Built Originally as a Collection of Electrical and Mechanical Parts to Control Machinery from a Distance, Roy J. Wens- ley’s Robot Has Been Dressed Up in Human Form and Goes to Church, as Guest of the Rev. Christian Reisner; the Mechan- ical Man Can Answer the Tele- phone and Carry Out Any One of a Series of Orders; in Ordi- nary Life, One of His “Rela- tives’? Reports on the Condition of the Water Reservoirs at Washington, Eliminating Hu- man Watchmen; at the Right Is Dr. Benjamin Gaylord Hauser with His Chemical Man, Which Imbibes and Di- gests Food Just Like the Liv- ing System, and Thereby Dem- onstrates in Graphic Form What Happens When We Eat; the Round Bulb at the Top Represents the Mouth, and the One in the Center the Stomach

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POPULAR MECHANICS ~~ SMALL BIRD PUTS . OUT LIGHTS BY SHORT CIRCUIT Electric lights in an English town were sud- denly extinguished the other night. The cause was a short circuit on the line resulting when a small bird evidently at- tempted to fly between the wire and the arms of the insulator. Its feathers established a contact, bringing about the short circuit. Such cases are rare, for small birds alight on power lines, on third rails and other con- ductors without injury to themselves or damage to the system, the reason being that they seldom establish a “ground” whereby the current can be short-circuited. Larger birds often come to grief and sometimes when small birds are flying ; in flocks, the neces- : sary contact for a short circuit will be established Photo by Ewing Galloway between members of the Replacing Electric-Light Bulbs on Top of the Grand Central Building, New flock York City; Note the Outer Shields SHIELDS FOR TOWER LAMPS HELP PREVENT BREAKAGE Electric-light bulbs on top of the thirty- six story Grand Central building in New York city are protected with outer glass shields to guard them against damage by winds and driving snow, rain and hail. Bulbs installed in such places, where they are exposed to the full force of the ele- ments, break more frequently than in more protected spots, and special means are devised to reduce replacements to a minimum. Fitting new bulbs is not al- ways an easy task, although, in the case of the Grand Central building, the workers have little difficulty and run small risk of accidentally falling, because the protrud- ing ornaments on the tower offer abund- ant hand and footholds. Small birds are often killed in pairs in this way if the tail or a projecting wing of one that is sitting on a live wire or rail comes in contact with the body of another bird through which a ground is formed. FLOAT PREVENTS SKIN ON MILK WHILE BOILING To keep skin from forming on the sur- face of milk while being boiled, a hollow metal float with a knob has been intro- duced. It is placed on top of the milk be- fore boiling and re- moved after the liquid has cooled to about 122 de- grees Fahrenheit. The float is made in a range of sizes to fit various pans, and is said to operate effectively. ~ “y sor wit roz ad dri pa: of ED Er to dis Nz Sp tri fo! lat

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POPULAR MECHANICS 609 “JOY RIDER” FOR AUTOS IS THE LATEST AMUSEMENT Wayside Thrills for the Motorist; a “Scenic Railway” Idea Adapted for the Automobile in a Drive over Hil- locks Made from Piles of Earth; an Admission Charge Repays the Owner Motorists are enabled to experience some of the thrills of an amusement park without leaving their cars, on a “joy rider” road built near a Texas highway. For an admission charge of ten cents, autoists drive into a large field where a road that passes ocean-wave fashion over a series of small hills scooped up out of dirt, gives sensations like those of a roller coaster. ENGLAND BUILDS SECRET PLANE TO SEEK DISTANCE RECORD A mystery airplane, secretly built in England, was tested recently preparatory to an attempt to break both duration and distance records.. The machine, a Fairy- Napier monoplane of 100-foot wing spread, adds Great Britain to the coun- tries turning to the monoplane. Hereto- side the pilot’s ear if he deviates from the prescribed course. How the system works is a secret, but it is said to be the result of several vears’ research work. The ship carries 1,000 gallons of gasoline which is kept in wing tanks. The pilot’s seat is fitted with pneumatic cushions to relieve the strain of long hours, and a couch in the cabin is similarly equipped to provide a resting place for the relief pilot. There also is a comfortable chair and a folding table for the navigator. It is planned to try first to break the duration record for unrefueled planes, now standing at 65 hours 25 minutes, and then attempt an 8,000-mile flight from London to Cape- town, with only one stop for fuel. LIGHT CAST FROM ANY ANGLE BY JOINTED FIXTURE fore, practically all British ships, both large and small, , have been biplanes. The 450-horsepower Napier engine is reported to have a special carbura- tion system de- signed to produce maximum _horse- power with a con- siderably lower gas- oline than consumption usual. The ship also is said to be equipped with a type of direction in- Having six joints of special construc- tion, an electric- light fixture now on the market can be adjusted easily to throw the rays where they are most needed. The fixture may be turned in a com- plete circle, swung high or low, tipped or turned in any di- rection, saving time and trouble in re- dicator which sounds a horn be- One of the Many Uses for the Special Light Stand That Has Six Joints adjusting the entire standard,

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that he is one of those rare persons, a natural- born flyer. That is not to be won- dered at, for he comes from the greatest flying family in the United States, and, so far as American and British records show, the world. The flying Stinsons have produced four pilots— Katherine, Marjorie, Ed- die and Jack—a record believed to be unique. How does it feel to have spent 14,000 hours in the air? “T’ve never given it a thought,” Eddie con- fessed the other day. “Tt’s the one thing I want to do, and the only thing I know how to do—build Eddie Stinson and His Wife Snapped at Mills Field, San Francisco, on Last Summer’s National Air Tour By J. EARLE MILLER DDIE Stinson, barnstormer, war pilot and airplane manufacturer, the other day finished his fourteen thousandth hour in the air, a record, it is claimed, no one else anywhere in the world has ever ap- proached. Fourteen thousand ‘hours represent 583% days of twenty-four hours each, or the equivalent of about nineteen and a half months in the air, if they were all strung together in one flight. For a man still in his early thirties to have spent nearly two years in the air is a remarkable thing, but more remarkable still is the fact that after fifteen years of flying, it still holds its lure—the one thing he wants to do. The great majority of flyers, after a few years’ experience, retire into something not quite so hazardous, but Eddie Stinson expects to keep on fly- ing as long as he lives. The answer is 610 planes and fly them. I get in six or eight hours every Sunday, usually flying down to Chicago from the factory at Northville, Mich., to spend the day with the boys at the airport, and, while we have a test pilot, I usually manage to get in a bit of time on every plane we build.” What those bits of time amount to is indicated by the fact that, in the two and a half years since he became an airplane manufacturer at the head of his own fac- tory and began turning out commercial ships and special jobs for transatlantic and round-the-world flyers, he has managed to keep up his average of around a thou- sand hours a year in the air. Last year, with Capt. George Haldeman, he took a Stinson “Detroiter”—a six-passenger mon- oplane fitted with special gas tanks in- stead of passenger seats—down to Jack- sonville, Fla., and set up a new world’s endurance record of 53 hours 36 minutes and 30 seconds, the second time in a few years that he held the endurance mark. 30 sir St Wi fri th all su he sl ol di

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The Stinson “Detroiter,” in Which the Builder and Capt. George Haldeman Last Spring Broke the World’s Endurance Record; a New Ship Is Being Built to Regain the Mark, Now Held Abroad 30th the Italians and the Germans have since bettered that record, but a new Stinson is coming out of the factory shortly to go after it again, and Eddie will be at the controls half the time. His chief recollection of the two and a fraction days of monotonous flying over the Florida coast mst spring is that it allowed him to catch up in his lost sleep. “We carried an eiderdown quilt and a supply of magazines for entertainment,” he explains. “The one off duty would stretch out, read a bit and then go to sleep. I got almost twelve hours sleep out of each twenty-four. About the only discomfort was watching George’s beard grow and wishing we would get it over with so he could shave.” Haldeman was no novice at long flights in a “Detroiter,” for he piloted Ruth Elder almost to the Azores on her ocean flight. The flying Stinsons’ connection with aviation is almost as lengthy as that of the Wright brothers. Along about 1903 and 1904, when the Dayton bicycle men were making their first flights with power, a boy in knee pants, down in Mississippi, with the assistance of two sisters, was building glider-type kites. The trio were Eddie, Katy and Marge, who grew up to be, respectively, an airplane builder and a pair of famous women dare-devils. By the year 1909, when the Wrights were winning their first world-wide recog- nition, the Stinson children were getting 200 and 300-foot flights in gliders big enough to carry them and attaining the respectable altitude of ten to fifteen feet. It must be remembered that the Wrights did most of their power-airplane flying at that time around fifty feet above the ground and publicly announced they saw no reason for going higher. Katherine went to Chicago in 1912 and learned to fly a Wright Model-B, a curious contraption that a spectator described as a rather flimsy front porch with a pilot sitting out on the steps. At the same time Eddie, who had reached the respectable age of seventeen, was building his own machine, with the help of a couple of ga- rage mechanics, in St. Louis. There wasn’t any suitable engine on the market, so they built that, too. The finished product bore a close re- semblance to the Wright, even to the pair of chain-driven pusher propellers in the rear. With it he did a lot of ground fly- ing and learned to handle a plane per- fectly up to the moment it reached flying speed and took to the air. Every time it got off the ground, however, the trip wound up in an accident, and the ma- chine had to go into the shop for repairs. Finally it had been crashed and repaired so many times the builders ran out of places to put fresh patches and Eddie de- cided to go down to Dayton and enter the Wright school, an arrangement which had the advantage that the cost of tuition included all repairs, if the student cracked up the school ship, the singular being correct as, most of the time, the school had only one plane. 611

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612 POPULAR MECHANICS schools during the war and since. Eddie says the fun- niest experience in all his 14,000 hours hap- pened at San Antonio while he was still in his teens. He was flying a Wright model, home- made, and, by permission of the commandant, was using the parade ground at Fort Sam Houston as a flying field. One day the commanding officer served notice he would have to move away, as the army was sending down four ships to estab- lish the nucleus of an air corps at Ft.Sam Houston, and it wouldn't be safe for a kid in a forty-mile-an- Stinson in the Plane, and the Mayor of Jacksonville Wishing Haldeman Good Luck before the Start of the Flight Katherine already had become a famous state and county-fair attraction, and Mar- jorie went through the Wright school that . same summer of 1914 and followed in her sister’s footsteps, while Eddie went barn- storming, too. The family had moved to San Antonio, and put that ancient Texas town on the flying map long before the army made it the greatest flying center in the country by establishing there Brooks and Kelly, the chief primary and finishing flying hour Wright to be fool ing around in the air when four fast “Jennies,” ships capable’ of as much as eighty miles an hour, were in the same vicinity. So the young flyer went out and located his first field, a level track south of town, borrowed a pair of sheets from his mother, staked them down to mark the spot, and returned to the fort to start his first cross- country flight, a journey of seven miles. All went well the first half of the dis- tance, and then, as he shoved the control stick forward to nose down and lose some altitude, nothing happened. He kept on The New Fairchild “21,” a Low-Wing Monoplane Designed as a Training Ship for Student Instruction, Is Typical of the Drift Away from the Biplanes of Recent Years sh

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POPULAR MECHANICS 613 shoving until he had the stick all the way down to the cross- bar on which his feet rested, with the result that finally, per- haps because of the displace- ment of his weight, the home- made plane went into a dive. Back came the stick until it was pressed tight against his | chest, and again nothing hap- pened. He squirmed sidewise out of the seat and kept on pushing until the stick was where he had been sitting, and then the plane nosed up. At the same time he located the source of the trouble. A bolt which acted as a pivot for the elevator controls had sheared off, and instead of going up and down when the controls were moved, the elevators were his new field, until finally his ship was not more than thirty feet from the ground. Afraid to try an- other dive, he shut off the ignition and let the plane settle to the ground, mak- ing a landing in a corner of a ceme- tery without break- ing anything. The sexton ran over to investigate, and Ed- die explained he couldn’t get out of i” the cemetery until he got a three-six- Typical Two-Passenger Coupe of the Air, and, Above, the Retractable Landing Gear of the Fokker Amphibian Pulling Up into the Stub Pontoon Wing simply sliding back and forth. The break- ing of the same bolt made it impossible to warp the wings, a necessary function which took the place of ailerons in the Wright ships. By alternately shoving the stick all the way down and pulling it all the way back, he succeeded in descending in a series of short dives, all the time hoping to reach teenth-inch stove bolt to repair the controls. The sexton thought one might be found, and together they rummaged through all the junk in his storeroom, without success. Finally the sexton in- quired if the boy flyer was superstitious, and volunteered the information that one of the vaults contained an ancient iron- plate coffin, fairly studded with bolts. Together they rolled back the stone

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TS 614 POPULAR MECHANICS cover, inspected the coffin and found a bolt just the right size. Repairs were made, young Stinson took off and landed safely beside his mother’s sheets at the new field. It was on the same field that Marjorie won the title of the “Flying School Ma’rm,” when she opened an aviation school and became the first woman pilot to give flying lessons. She and Eddie to- gether trained a large number of flyers for Canada before the United States went into the war, while their mother helped manage the business. One of the queerest of flying incidents happened during that period. “We had a student,” Eddie says, “who didn’t want to fly, and was afraid to fly. He was of army age, and if he.had to go into the army, he had decided he wanted to be an officer, so joined up to get a fly- ing commission. In private life, he had been a ribbon clerk, and if anyone ever looked and acted as you would expect a ribbon clerk to look and act, he did. “We labored and labored over him, and finally one morning he made three fairly decent landings in succession, so I told him to go ahead and solo. To get his _ticket, he had to take off, go up and do two figure eights, and come down and make a good landing within a certain distance from a mark. “He made a perfect take-off, climbed to the right altitude, did a pair of as nice figure eights as anybody ever saw, circled out downwind, turned and came into the field at just the right altitude, at the cor- rect moment he cut the gun and nosed down in a gentle glide, leveled out just when he should, pulled the nose up as the plane lost speed, and was settling for a perfect three-point landing, with the plane hardly six inches off the ground, when he lost his head and jumped overboard. “The ship landed and rolled along to a stop, while the student was nearly killed from the head-first impact at thirty miles an hour.” With the entrance of America into the war, Stinson was commissioned, and im- mediately assigned as an instructor to Kelly field. There he stayed, for there were plenty of students to send to France, but good instructors were rare. As “final check” pilot at Kelly, no student could graduate until he had a certain number of minutes in the air with Stinson and re- ceived his O. K. At Kelly, Stinson became famous for two things: his stunts with a ship of his own design, and his ability to break light globes with a wing tip, the last of which proved a remunerative occupation, as there was always a certain number of peo- ple willing to bet it couldn’t be done. Every structure around a flying field is marked with a red warning light, one of the most prominent being the light atop the flagpole. Eddie’s usual bet was $100 that he could fly over the flagpole and gauge the distance so accurately that he could crack the glass globe off by brush- ing it with a wing tip, without damaging The Twin-Motored Sikorsky Amphibian, a Luxurious Aerial Yacht; When Its Wheels Are Lowered, It Can Land on Any Fair-Sized Field, or Draw Them Up and Alight on Water his at mi th th dl fa th an pi fle wl ba ab ta th Ov ur sh

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POPULAR MECHANICS 615 Looking Forward in the Cabin of the Sikorsky Amphibian; the Two Pilots Are in a Separate Compartment, and the Kitchenette and Lavatory Are at the Rear of the Ship his ship. As a collision with the flagpole at a flying speed of eighty miles an hour or more would be fatal to both ship and pole, there were frequent takers of the bet, but they invariably lost. His little homemade monoplane han- dled so perfectly that one of Stinson’s favorite stunts was to climb the side of the field water tank, drop across the top and go down the other side until the ship picked up flying speed. To do the trick he flew straight at the water tank, with his wheels just off the ground, pulled the stick back just before a crash seemed unavoid- able, zoomed the ship up the side of the tank until it lost flying speed just above the top, shoved the stick down and flipped over the top, then down the opposite side until he got speed when he would pull the ship up and level out again. What his 14,000 hours of flying repre- sents can be visualized by reducing it to mileage. Forty to forty-five miles was top speed in the early days, but 150 and better is common now, so it is safe to say he has averaged better than 100 miles an hour over the 14,000 hours. At that rate, his 1,400,000 miles represents three round trips to the moon and back, which is a tespectable lot of miles. BLOOD MADE WITH CHEMICALS TO HELP GAS VICTIMS One of the iron substances found in the blood has been prepared synthetically by a German chemist, according to reports. It is expected that the discovery will be useful in cases of gas poisoning, although at present blood transfusion is cheaper.

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Seer a9 ee TY oe RRP Ieee 616 POPULAR MECHANICS Tennis Gun That Hurls Balls across Net for Benefit of Player. Practicing Strokes TENNIS GUN HELPS PLAYERS PRACTICE HARD STROKES Tennis players can practice without an opponent by means of a gun that hurls balls at them from across the net. This unit gives them an opportunity to de- velop a number of strokes and enables the instructor to check their work, as he can watch each play. HOME MOVIE AND RADIO PLAY ARE LINKED TOGETHER A synchronizing device for attachment to the radio receiver, so that a home movie projector can be operated in conjunction with plays broadcast over the ether, is being tried out in England. The British broad- casting corporation, which-operates “2Lo” and other government-controlled stations, recently filmed a movie to try out the de- vice, invented by Mr. G. V. Dowding. The synchronizer is claimed to be so ac- curate that it will not get more than one second out of step in twelve months. It is planned to lease the movie reels at a nominal sum. When a movie-radio play is to be announced, the broadcasting sta- tion gives the reel number, allows time to insert it in the projector, and the an- nouncer then directs the audience to press the button that starts synchronizer and movie projector. The first movie-radio play filmed involved a chase of an escap- ing convict. STUTTERING CHILD AS BRIGHT AS NORMAL PUPIL Stuttering may be a handicap, but it does not necessarily indicate lack of men- tal ability, tests performed on 7,138 school children by Dr. Elizabeth D. McDowell, at Columbia University, disclose. It was found that the stuttering pupil has as high intellectual capacities as the normal child, that his vocabulary is as good and that, usually, he is physically superior. Other tests proved that the stutterer could speak as many words in a three-minute period as any other pupil. BIG SEARCHLIGHT SENDS CODE BY RADIO CONTROL Beams of light flash messages in code from a 3,500,000,000-candlepower search- light recently constructed for the French government. This is done by remote ra- dio control, a wireless apparatus, miles away from the lamp, operating a shutter so that the code is “winked” out in flashes of light. The lamp is moved by electricity, through a portable controller, being ad- justed so that it can be elevated to an an- gle of ninety degrees for operations against aircraft. By both quick and slow movements, the beam can locate a fast- moving object and, once having spotted it, can be guided to follow it. Mammoth Searchlight Controlled by Radio; It Flashes a Code Visible for Many Miles “H( Indi Thes Serv I gio: in wit of stil pic duc ling ma is t gar Ala ag hea the tov riv pic sur me wit ing gle be me

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POPULAR MECHANICS 617 “HOOLIGAN” FISH = ~~ / Indians at “Hooligan’’ Fishing Time; These Fat Little Fish Yield Oil That Serves as Lard or as Substitute for Ice Cream In the Pacific coast re- nature was generous in supplying the aborigines with food resources. Many of the primitive industries still exist. They are quaint, picturesque, and are con- ducted along the simplest lines. One of the most ro- mantic and colorful of these is the harvest of the eulachon, or “Hooli- gan” fish, by the natives of southeastern Alaska. Picture a river of purest azure, a glacial stream winding through a valley heavily timbered with spruce and fir, above the tops of which snow-capped mountains tower majestically. On the bank of the river, Indians, clad in nondescript but picturesque garb, toil or play in the hot sunshine of the short Alaska summer, the men sweeping the waters of the stream with crude dipnets and the women scurry- ing up the bank with baskets filled with gleaming fish. The eulachon is said to be the fattest of all fishes, and both the meat and the oil rendered from it have a gion, SUPPLIES BOTH FOOD AND LIGHT (a peculiarly delicate, agreeable flavor. In the early days of Alaska gold discovery the eulachon was used for purposes of illumination by the miners, who called it the candlefish. It may be dried, thrust in the neck of a bottle, and burned like a candle. The Alaska Indian likes the oil of the eulachon better than other fish oils, and the flesh is sometimes eaten dried and smoked. The Canadian government purchases much of the oil for its Eskimo wards in the far Arctic. It is considered an excellent substitute for lard. One of the favorite dishes among the coast In- dians is prepared from eulachon oil and is a native substitute for ice cream.

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POPULAR MECHANICS The Man Standing in the Dipper Gives Some Idea of the Enormous Size of This Shovel ¥ MAMMOTH SHOVEL BEING BUILT TO BREAK ALL RECORDS Spurred by the success of several twelve-cubic-yard-capacity electric exca- vating shovels put in operation last year, a fifteen-yard unit is nearing completion, to be the largest in the world. Some idea of what a fifteen-cubic-yard shovel means may be gathered from the fact that the dipper will bite out eight large motor- truck loads of material at a single gulp, or enough earth to fill a trench six feet wide, sixty-eight feet long and a foot deep. The machine will have a boom 120 feet long and a dipper stick of eighty feet. A sin- Fe gle man, with one set of hand levers and one set of pedals, will control every oper- ation of the giant, according to the Gen- eral Electric company, which is building the motor equipment. Power will come to the shovel through a trailing cable nearly three inches in diameter and about a thousand feet long, which will be wound on a reel at the rear. PLANE RESCUES INJURED NUN IN ALASKA Winging his way north- ward over Alaska, an aviator went to the res- cue of an injured nun at the St. Peter Claver mis- sion in Nulato recently. She was carried 400 miles in the plane to Fairbanks, where surgeons set her broken leg. The Rev. Father Joseph F. McEl- meel, priest at the station, heard the faint whir of the airplane. He hurried to the post office, secured the aid of the signaling agent there, and in a few moments, the plane had landed and arrangements were made for taking the suffering nun to Fair- banks the next morning. SPRING-MOTORED TOOTHBRUSH FOR POCKET Giving the toothbrush a rotary instead of a sideways movement is recommended by dentists, and this is the natural action of a revolving brush now on the market. It has a small motor which causes the brush to spin rapidly when a tiny handle is pushed. The entire outfit can be carried in the pocket, is Operating the Rotary Toothbrush; a Spring Motor Spins the Shaft and Buffer at Rapid Rate easily kept clean and is said to be benefi- cial to the teeth and to the gums.

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© Tropical Press Agency Dr. C. J. Hedley-Thornton Examining Some Samples of “Artificial” Cotton in Various Stages of Treatment; a Bird’s Nest Led to the Accidental Discovery of the Plant SUBSTITUTE for cotton, discovered by accident in a Central American bird’s nest, has quietly been put in produc- tion in England, and, with its recent an- nouncement, it was stated that a sufficiency could be grown within another two years to fill fifteen per cent of the world’s de- mand for cotton cloth and cotton products. The new fiber comes from a weed, found growing wild in British Guiana. Dr. C, J. Hedley-Thornton, of London, an expert in the study of cotton pests, particularly the boll weevil, was in Guiana with a party of scientists when they discovered a bird’s nest, apparently made from cotton. As no known cotton supplies were within reach of the bird, they watched, and even- tually traced the nest builder to a weed from which it obtained the building mate- rial. They found nine different varieties of this weed, all very similar, but only one variety yielded the cottonlike fiber selected by the bird. Samples of the plant were taken to England and cultivation attempted. De- 4 spite the change of climate, the weed thrived, and, by careful crossing and re- crossing of selected specimens, in a few years’ time began yielding plants five to seven feet high, with a far superior out- put of fiber. The plants grew well in even poor soil, and, so far, no insect pest has been found to attack them. Considerable areas in Sussex and Essex have been un- der cultivation for some time, with an average yield of 800 pounds to the acre, the acre yield being valued at $100. Cloth made from the fiber has been dis- tributed, without even experts detecting the fact that it did not come from a gen- uine cotton plant. Before going to the mills, the fiber is chemically treated, but from then on the process of converting it into usual cotton-product forms does not vary from existing methods. It is readily mixed with silk, artificial silk or wool to produce blended fabrics, and is bleached, printed and dyed in the usual manner. The cloth, it is claimed, has a higher sheen than ordinary cotton, so 619

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a eg ae eo ee cepa a ae POPULAR MECHANICS only because the crop may be grown with profit on poor waste land, but because its cheapness promises to revive the cotton- spinning industry, which has suffered con- siderably in recent years. Neither Amer- ican nor Egyptian cotton, it is claimed, can be laid down at the Lancashire mills at prices which will enable them to compete with the new product. Chemical and structural tests of the cloth woven from the weed fiber indicate it is stronger than cotton, and also more elastic. So far, it has only been woven in the coarser grades. Doctor Hedley-Thornton anticipates no difficulty in weav- much so that a blend of ten per cent artificial silk and ninety per cent of the new cotton ae makes a satisfac- tory silk substitute. The makers claim it takes color much more easily than or- dinary cotton, and requires only about one-third as much coloring matter for dyeing. Instead of pick- ing fine cloths com- parable with the best cotton fabrics, and the Lancashire mills are experi- menting with the fiber preparatory to attempting to in- vade the entire cot- ton field. With the production in the hands of one com- Sa pany a price of : 12% cents a pound has been put on the fiber. ing the fiber in the field, the plants are reaped by machinery and sent to the mills for separation. It is impossible to grow new plants from seed, as they will revert to the wild character- istics. Instead, the roots are dug, the old root having decayed and left three fresh offshoots. As a result, after each acre’s crop has been dug, there are sufficient new roots to plant three acres the follow- ing year. After the fiber is removed from the plants, the leaves can be salvaged and made into serviceable paper and the stalks into building board. Excess roots also can be utilized through the extraction of a new drug. The progress of the development is be- ing watched with interest in England, not The Bird’s Nest That Led to the Discovery of the Plant, Top; Fiber after Treatment and Ready for the Mills, Center, and Coarse-Count Fabric Woven from the Fiber ne de of al

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POPULAR MECHANICS 21 Drawing of the Automobile Toll Bridge That Will Connect Oregon and Washington; It Is to Cost Nearly $6,000,000 and Will Be More Than a Mile and a Half Long LONG TOLL BRIDGE FOR AUTOS TO LINK TWO STATES Another impressive bridge construction is under way on the Pacific coast, where a steel link is being thrown across the Columbia river to connect Longview, Wash., with Rainier, Oreg. The bridge will have a clear height of 195 feet, amply sufficient to allow tall-masted vessels to pass beneath; will be more than a mile and a half long, and will cost approxi- mately $5,800,000. More than 13,000 tons of steel will be required. It will be oper- ated on a toll basis. More than 600,000 vehicles will use it during the first year it is completed, engineers estimate. Work is to be finished about Feb. 1, 1930. FOUR THOUSAND AIR ENGINES DOOMED TO BE JUNKED Four thousand Liberty engines, brand- new and still in the original crates, are doomed as junk, as a result of the action of the house of representatives in placing an official ban on their use in new air- planes ordered by the army.. Ten years ago the Liberty engine was the finest air- craft motor in the world, but engine build- ing has progressed so far in the years since the war that the, big twelve-cylinder Liberty is now branded a menace to aviators, be- sides being uneconomical to use. Con- gressman LaGuardia, of New York, a war- time flyer, was responsible for the decision to replace the surplus engines with more modern motors. He cited figures from General Fechet, chief of the army air service, to show that Liberty engines were three times as dangerous as the modern Wright “Whirlwinds” and “Cyclones,” Curtiss “D-12’s” and Pratt and Whitney “Wasps” and “Hornets.” LaGuardia rec- ommended that none of the engines be sold for use in civilian planes, and that they be converted into scrap. Some re- conditioned Liberties have been sold for use in fast motorboats. ROUGH ROLLER FOR HARD ROADS TO STOP SKIDDING On some of the hard roads about Ber- lin, a specially constructed roller is ap- plied to roughen the surface and thus re- duce the likelihood of automobiles skid- ding. The plan in effect gives a tread to the road without damaging the material or causing discomfort in riding. Rough Roller That Puts a Non-Skid Surface on Hard Road for Safer Auto Driving

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622 POPULAR MECHANICS terms. Under the bill, the government is to advance $165,000,000 to start the project, with the idea that the money eventually will be repaid out of power profits. If the states ac- cept the terms and the dam is built, it will be the highest on the continent, taller than the Washing- ton monument; will im- pound a mass of water sufficient to cover five New England states to a depth of one foot, and will stop the river from carrying down to the sea each year enough silt to fill the whole channel of the Panama canal. While the primary purpose be- hind the scheme is flood reliei—to prevent the river .from overflowing the immensely rich Im- perial valley, a truck gar- den that once was the bottom of the sea and is now below the river level —the power developed is Model of Airport Department of Commerce Prepared for Exposition in Se- ville; It Embodies the Latest Improvements AIRPORT LIKE COUNTRY CLUB HAS MANY LUXURIES For exhibition at the international fair in Seville, Spain, the department of com- merce has prepared a model of an airport. It shows luxuries and conveniences com- monly associated with country clubs, and similar places, and also has small replicas of most of the latest safety devices devel- oped for aviation fields. BOULDER DAM UP TO STATES BORDERING ON RIVER With the passage of the Boulder dam bill by congress and its signing by Presi- dent Coolidge, the greatest flood-control, irrigation and powWwer-development scheme in American history is now up to the states bordering on the lower Colorado river, waiting for their acceptance of the expected to pay for the work. As a side line, a hotel and resort may be developed on the west bank above the dam, from where boats can travel up to the Grand canyon. The site is not far from Las Vegas, a desert stop on the Los Angeles-Salt Lake air-mail and passenger line. ALUMINUM MILK-BOTTLE CAP HELPS GUARD HEALTH To keep dust and germs out of milk bottles, an aluminum cap with a hinged cover opening for pouring, snaps on the top of the bot- tle. It is easily ad- justed and tightly seals the con- tainer. Sata: ae | | » ~ "2 oo . ew

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POPULAR MECHANICS 623 AMERICA’S GREATEST RECLAMATION PROJECT Bird’s-Eye View of the Boulder Dam Site; the Grand Canyon Is Several Miles to the Right of the Storage Lake; Insets, the Dam Compared with the Washington Monument, and Visualization of What It Will Mean to the West

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a eR ww Ee FOE sah Model of Lock, the Chain of Which Contains Pene-. trating Gas Intended to Rout Burglars CHAIN LOCK RELEASES GAS TO FOIL THIEVES Fumes of penetrating gas are contained within the chain of a lock that an eastern inventor has introduced to discourage thieves. Should the chain be cut, broken or otherwise tampered with, the gas is re- leased and is intended to overcome any- one who is attempting to force an en- trance without a key. PREDICT VOLCANO ERUPTIONS BY STUDY OF AVERAGES When Dr. Thomas A. Jaggar, director of the Hawaiian volcano observatory, predicted, the other day, that there will be an eruption of either Kilauea or Mauna Loa this year, scientists paid attention, for his prophecies with regard to the action of volcanoes have been fulfilled with re- markable consistency in the past. “A vol- cano is not a clock,” he explained. “The interval theory is based on averages and the averages are based on certain laws of nature such as those that determine the space intervals of ripple marks in the sands of the sea or the time intervals when they break rhythmically on the beach. The lava under a volcano has been pressing upward for ages through a crack POPULAR MECHANICS of certain size. It has blocked or im- peded that crack with its own heap of lava and so has forced itself to adopt a rhythm or interval like the puffs from a steam engine. If it has several vents, these divide responsibility for the interval, and if one vent is low and close to the water table, while the other is high and far above the ground water on the island, the probability of explosion is greater for the lower vent. This is because a sudden drop in the lower vent may place the lava column below the water table and so develop a steam chamber. This is the situation of Kilauea as compared with Mauna Loa.” Doctor Jaggar predicted in 1912 that Mauna Loa would become active before 1915. It broke out in 1914. In 1920 both Kilauea and Mauna Loa erupted, according to predictions he made in 1917. WOOD FIBER FOR MILK BOTTLES REPLACES GLASS Lightweight bottles of paraffin-treated spruce fiber have been introduced as milk containers in place of the ordinary ones of glass. They eliminate the clatter, are easily opened and are tightly sealed when filled, to keep out dirt and to prevent tam- pering. Two of the cone-shaped holders, I Mii Filling the Paper Bottles, and Comparison of the Weight of Two with One Glass Bottle, All Filled filled with milk, weighed but seven ounces more than a full glass quart bottle. T ‘ eacl actu nig! abo law: aut dist sho se pro ast¢ shu too scul T thai whe in t “Bu Fac lish out por den stru lane has yea or thre ern sma nea sou upo dru sup thir the

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he es HE FANTASTIC sight of two chickens, each one clad in what actually looked like a nightshirt, careening about on a farmhouse lawn, was afforded two automobilists in the rural district of Vienna, Va., a short time ago. “What does that prove?” exclaimed the astonished driver as he shut off his motor and took a closer view of the scurrying hens. The answer, given by W. S. Abbott, was that they were now on the premises of what is probably a unique research farm in the country. Known variously as the “Bug Boarding House,” “The Crawler Factory” and “The Insect Zoo,” the estab- lishment is used for the purpose of testing out all manner of chemical mixtures pur- ported to rid the nation’s households, gar- dens and farms of bothersome and de- structive insect pests. “Doctor” Abbott, as he is known, is the landlord of the boarding house, and he has been on the same job for about twelve years, his official title being entomologist, or insect specialist. Assisting him are three other entomologists, and the gov- ernment has established a somewhat smaller bug farm at Lake Alfred, Fla., near Orlando, the idea being to study the southern insects, notably those that prey upon citrus fruits. In addition, the food, drug and insecticide administration, which Supervises all the work, maintains some thirty collectors whose duty it is to tour the country in search of samples of insec- An “Apartment House” for Cockroaches in the Government Experimental Laboratory, Where All Kinds of Insects Are Studied ticides to be turned in for investigation. Far-fetched as the bug farm’s nick- names may sound, they are not so much so when you come to examine the reasons for their origin. Certainly the place is an insect-boarding house, for there are apartment houses and a regular bill of fare for cockroaches; a two-story palace de- voted exclusively to the fussy wants of clothes moths and carpet beetles, and, besides, two entire greenhouses filled with choice plants that offer the richest kind of desserts for the most discriminating outdoor moguls of bugdom. As for being a “Crawler Factory,” that term, too, is not so far from the truth. There’s hardly an insect that a person could name off-hand that isn’t to be found, and if it so happens that the supply of roaches, moths, fleas, lice, and so on, runs low, the experts practice the simple expe- dient of supplying such appetizing fare that in an amazingly short time, may be only a few days, the situation becomes normal. Then again, the name “Insect Zoo” 625

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MECHANICS

certain kind of chemical mixture, be wrapped around the hens. It killed the lice, sure enough, and killed a lot of chickens, too. Almost equally tragic results, though of a somewhat different sort, have come about occasionally dur- ing experiments concern- ing the lowly bedbug. There was a time when the wee crawlers were bred in the bug-boarding house off a rather large scale. Not so today, however, and possibly such happenings as the following may serve to explain why. It seems that bed cooties can live on many kinds of ani- mals, notably white rats, or so the experts believed

Testing Out Insect Eradicators in One of the Greenhouses of the Laboratory Where Pest Extermination Is Studied comes pretty close to the real facts in the case. Whereas, in an animal zoological park, the monkey frolics about a tree while the duck cavorts in a pond, a sim- ilar situation prevails among the bug-farm inhabitants. Within its exclusive man- sion, the cockroach may play hide and seek among the cracker boxes and refuse of various kinds that simulate almost ex- actly the conditions in its natural habitat; the hungry clothes moth, surrounded by a goodly supply of raw wool and woolen cloths, has far better qtiarters than he would have normally, and the rest of the bug family are treated with like consid- eration. For instance, the itinerant animal parasites, such as those fleas and lice that gnaw on dogs, cats and chickens, are bred in substantial numbers by the simple process of letting them roam around at will on the haunches of animals raised especially for the purpose. Those two staggering hens with the “nightshirts” on were taking part in a curious test. The experts had followed out literally the directions of a lice cure, which recommended that cheesecloths, that previously had been dipped with a in the early days. There- fore, in order to encour- age their development, the seemingly clever idea was hit upon *to build up a sizable partnership between the bugs and rats. All went well for a while. But soon the scientists were taxing their brains to solve the strangest mystery of many a day. The bedbugs were disappearing fast and no legitimate reason presented itself until one alert expert noticed to his as- tonishment that, instead of the crawlers thriving on the white mice, the latter beasties were chewing away steadily on their erstwhile biters. This sort of thing couldn’t go on. So the practice of trying to breed the bedbugs stopped, and the fact was made known officially that Uncle Sam hereafter would buy them at the modest price of a penny apiece. Yet there weren't any too many bug hunters willing to sacrifice time and energy for that sum. Whereupon the price jumped up to a copper and a half. Even then the situation was hardly as it should be, although there actually were a few people of extra-fine eyesight who not only claimed they could supply 2,000 bugs upon twenty-four hours’ notice, but were able to make good on the boast.

T expt mer that for j apie assis his < stor wro Unc Pap the men larg gan all | cou nec out lette pirir the | not inse glad alre: vide sent N tyrs thei: dail: all i for ;

Tryin, ter, <

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POPULAR MECHANICS 627 | This bedbug story, however, had an un- | expected ending. Doctor Abbott one day t mentioned, in a Washington barber shop, ' that the government was in the market t for a supply of the bugs at a cent and a half t apiece. A stranger standing by offered to assist in getting the collection started, but t his assistance took the form of passing the . story on to a newspaper reporter, who : wrote a highly interesting account of Uncle Sam’s offer to pay for the pests. : Papers. throughout the country reprinted ‘ the yarn, sometimes adding embellish- e ments of their own, with the result that » large shipments be- > gan to arrive from 7 all quarters of the y country. It was e necessary to get 0 out a special form tigator on the bug 5 letter assuring as- farm to be called e piring dealers that upon, of a sum- "i the government did mer’s evening, to ge $, not need any more out in the swampy d insects and would woods where mos- > gladly return those quitoes are thickest re already sent, pro- and “park” there t. vided the shipper 5 for hours, mean- om sent return postage. 7 time letting the n Not all the mar- stinging insects try tyrs to science get their luck both on - their names in the an arm that has to daily press. It is been treated with a a all in the day’s work so-called mosquito- st for an insect inves- proof lotion and on lf one that has no s- such protective sub- rs stance on it. Un- er happily, this pro- on cedure has to be carried out because it is ng one of the best ways to test the efficacy ng of many much advertised commercial rem- ict edies. The idea is to compare the number “le of bites received on each arm. he Gas masks are common enough in et mines. But who ever heard of using such TS protective coverings for “shooting” cats ‘or and dogs with flea and lice remedies? ed Nevertheless there are frequent occasions en when the bug experts must put on a be, funny-looking mask, known as an “aspi- ple rator,” that fits over the nose and mouth. nly Without it, they would be more than likely on to get their nose and throat so filled with * ble Trying Out Flea Cures on a Cat and Dog, and, Cen- ‘trong chemicals that very soon they ter, a Plant Ravished by Aphids About to Be Sprayed would manifest all the symptoms of the

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Chickens Wear “Nightshirts” in a Test in Which the Garment Is Saturated with an Advertised “‘Remedy” true possessor of hay fever. It seems rather a shame that no such contraption has been devised for the use of the animals that must undergo the tests, but thus far there has been none that has entered the situation seriously. The dog shown with “Doc” Abbott in the picture, is only a mongrel. But its service to science during its five-year stay with Uncle Sam has been important. Sad- eyed and quiet, it has figured in all sorts of tests. In one of the very latest, it was adorned liberally with fleas, wrapped care- fully within a piece of sacking and then put into a box sprayed with a new kind of flea cure. Only the faithful dog’s head was left sticking out and it presented an exceedingly sorry picture. However, it bore the ordeal with bravery and earned further high rank as a star boarder in the bug house. In this regard the cat family is far more “persnickety” than are the dogs. Five kitties are kept at the farm to be covered now and again with sundry fleas and lice closely related to the dog varieties. But, as every one knows, cats bitterly resent having any kind of liquid poured on them; which explains why only POPULAR MECHANICS the powders are used ordinarily. Even these are not welcomed. Lice aren’t by any means confined to animals. Plants have them, too, and in great abundance, variety and in most colors of the rainbow. Known as aphids, the size of these strange insects also varies widely, some being so tiny as to be barely distinguishable to the naked eye, and others up to about an eighth of an inch long. Though most aphids are green, the color seems to depend mainly on that of the particular plant on which they live. One of the most novel of the recent ex- periments at the bug-boarding house was designed to test the effect of a substance, to be taken internally, which would not only rid chickens of lice, but, in case the said poultry were gobbled up by hawks or owls, would likewise kill these animals. The experts gathered a few of these last and fed a couple of chickens to them after the latter had imbibed of the magical powder. But something revolutionary must have happened to the “remedy,” for the hawks and owls seemed to thrive on their unusual fare even when the powder dose was increased up to eight times the amount called for. BOAT FOR SHALLOW WATERS HAS “STEPS” ON KEEL Weighing slightly more than 180 pounds, an outboard-motor boat introduced in England, will run on water but three inches deep when it is empty. The keel is arranged with overlapping members and the sides are built in the same manner to decrease resistance from the water when the craft is going forward. It will hold several persons. View of Keel of the Outboard-Motor Boat, Showing the Overlapping Members on Bottom and Sides MC T eac wo! cag ami wei The loa shij bus bin sig] sca! Sted atio the Stez it p is a lar Boz

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Ten" eS eel nd en old 2.) z the POPULAR Model of a Working Grain Elevator on the Chicago River, and, Inset, the Car-Load- ing and Unloading Side, with Railroad Sidings MODEL ELEVATOR LOADS CARS AND LAKE STEAMSHIPS The millions of bushels of grain which each year pass through the control of the world’s greatest grain market, the Chi- cago Board of Trade, require a vast amount of handling machinery to permit weighing, checking and speedy shipment. The huge grain elevators can load or un- load either railroad cars or lake steam- ships at the same time, and weigh every bushel of grain that goes in or out of the bins, all in one operation. One of the sights of the weighmaster’s office is a scale model of an elevator, rail car and steamship, cut away to show actual oper- ation. Grain can be run into and out of the bins, and to and from the car or steamer holds, and accurately weighed as it passes. The unloading of railroad cars is accomplished on a dumping track, simi- lar to those used to empty coal cars. The Board of Trade differs from stock ex- MECHANICS 629 changes in one important particular, for, while stock brokers may never see the actual shares they buy and sell, a sample of every car of grain enter- ing the Chicago market goes to the trading floor for examination. Both Board of Trade and state inspectors pass on the grading and insure the genuineness of the sample as representative of the lot. MOTORCYCLE RUN BY ROCKETS SHOWN AT EXHIBITION One of the interesting displays at a re- cent motor exhibition in Germany was a rocket motorcycle. For the first time, the general public had an opportunity to ex- amine this unit closely. The cycle has passed several successful tests. Rocket Motorcycle Shown at German Exhibition; Note Chambers and Powder Containers at Rear

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630 ZOO GOATS’ MODEL MOUNTAIN KEEPS ANIMALS IN TRIM

Goats in the San Diego Zoo on Top of Their Artificial- Mountain Playground Erected in Pen To give mountain goats the exercise they need, an artificial cliff has been erected in the animals’ pen at the Balboa park zoo in San Diego, Calif. <A spiral runway leads to the top of the crag, and there are projections to which the animals may jump. The goats enjoy the climbing and their nimbleness attracts visitors. SOLVE RADIO MYSTERY While stirring beans on her electrical stove, a California woman was mystified at hearing the strains of three musical selections coming from under the pan. The phenomenon remained a mystery un- til investigation led to the following ex- planation: The music was picked up by induction from a telephone wire by the current circuit that supplied the range. It was then fed to the metal resistances in the stove where the audio vibrations were loaded upon the heat vibrations

POPULAR MECHANICS which carried them to the thin metal disk of the pan. The stirring caused the musi- cal vibrations to come up from under the beans. It would have been possible, in the opinion of engineers, for the hot air alone to have reproduced the music. LIGHT RAYS CONTROL TRAIN TO PREVENT WRECKS German engineers are testing a light- ray safety-control system for railroads. A selenium cell is an important unit in the apparatus and along the right of way are mirrors, of special construction and said to be reliable under all weather condi- tions. Rays emanating from the locomo- tive cab strike the mirrors as the train proceeds. If there is danger ahead or the next block is closed, the rays affect the selenium cell in such a way that an electric circuit is closed and the train’s brakes are automatically applied.. The train is brought to a stop gradually by varying the distance between the mirrors. The system has been recommended for installation at curves and other places where slower speeds are in keeping with greater safety. PUNCHING BAG WORN ON HEAD AIDS SHADOW BOXER As a substitute for the regulation punching bag, a rubber sphere, attached to a headband by rubber cords, and worn in front where it can be struck by the fists, has appeared on the market. It is said to afford healthful exercise, gives practice in shadow boxing and is noiseless. Should the user miss the ball, he would suffer no injury as the sphere is of light weight.

Shadow-Boxing Practice with Lightweight Rubber Ball Attached to Head with Rubber Band

Int line and Gi us! str th wi of ha ho to! he in lez in ho ar a \ “¢ mi he in co be in su lig he

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all POPULAR MECHANICS 631 ALL-STREAMLINE PLANE FLIES AT GREAT SPEED Interesting Views of the Stream- line Plane Built for Fast Speed and Greater Comfort; Note the Guards about Landing Wheels Absence of struts, un- usual development of streamline design and the low position of the wing are special features of a monoplane built by a western engineer. It has flown at 200 miles an hour with its single mo- tor and has climbed to a height of 1,000 feet with- in the first minute after leaving the ground, ac- cording to reports. Land- ings at forty miles an hour are made. The fuselage and wing are covered with plywood. The plane has a wing spread of thirty-five feet. “COLDEST SPOT IN THE WORLD” FOUND AT HELIUM PLANT Near Amarillo, Tex., the bureau of mines is constructing a plant for obtaining helium from natural gas and when it is in operation, it will be one of the world’s coldest places. Three hundred degrees below zero will be the normal “weather” in this laboratory, for at that point other substances than helium in the gas are liquefied and can be drawn off, leaving the helium, which is carefully saved and bot- tled for use in inflating airships. Under such cold, air is also liquefied, carbon di- oxide becomes solid, lead and copper take on the properties of steel, and rubber be- comes as brittle as glass. An icicle, thrust inito the gas at such a temperature, would produce about the same effect as when a hot poker is immersed in water. Im- proved manufacturing processes are re- ducing the cost of helium to but a frac- tion of what it was when the gas was first employed for aeronautical purposes. @ Names and addresses of manufacturers of articles described in this magazine will be promptly furnished, free, by our Bu- reau of Information.

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a PROM AAR ae ater pe To 632 POPULAR MECHANICS SEAGOING FLYING FIELDS AND SALT-WATER —. 5 ii gee — 7 2% 7%. iy me dy to Take Off from the Flying Deck of the “Lex- poe 2 One of Uncle Sam’s Newest Aircraft Carriers Landing a Seaplane Along- side Ready to Be Hauled Aboard Again, and the Plane Being Hoisted to the Deck; Seaplanes Are Shot from the Carriers, as Well as from Battleships and Cruis- ers, by Catapults, and When They Return Alight Along- side in the Water; Land Ships, However, Can Fly Directly from the Broad Flying Deck and Return to It, Hooks beneath the Land- ing Gear Engaging Arrest- ing Apparatus to Bring em to a Stop Copyright

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—E——————— FS POPULAR MECHANICS AIRMEN WITH THE FIRST LINE OF DEFENSE hn * - FF Gassing a Ship aboard the “Saratoga,” Top, and Tak- ing Off from the Flying Deck; Each of the Big Air- craft Carriers Has Seventy- Five Fighting Planes and Carries 140,000 Gallons of Gasoline for Them; the Lower Photo Shows the Life Nets Lowered around the Edges of the Deck, to Provide a Refuge for Sailors When Ships Are Landing; When Not in Use, the Life Nets Are Raised and Swung Inboard B. U. Thompson

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ikaie Meal © aes amp ins Aad wo Ber o § Drawing to Show How Stilts Were Installed in Build- ing and Addition Erected on Top of Them ADD STILTS TO OLD BUILDING FOR EXTRA STORIES Although it was not constructed for adding more floors, an office building in New York city was raised six Stories re- cently by a skillful engineering plan. This involved erecting eight columns, 175 feet tall, inside of the old building, to support the addition. The work was accomplished without disturbing tenants and was fin- ished within six months. NEW VISUAL THEORY OFFERED BY SIR OLIVER LODGE How do we see? The phenomenon of vision is given a different explanation by Sir Oliver Lodge who witnessed a series of tests showing the effect of electric shocks on the nervous system. He sug- gested that radiation alone is not the POPULAR MECHANICS whole cause of vision but that the retina of the eye possibly contains something which ejects electrons and these act as projectors to stimulate the nerves. This stimulation from the electrons, rather than the impact of the light waves, Sir Oliver holds, may cause vision. His expla- nation was inspired by the fact that some high-frequency electric currents could not be felt when applied to the body of the subject in the test, but did produce an effect on the nervous system. PRINTER’S ERROR ADDS VALUE TO POSTAGE STAMP Mistakes usually are costly but they may mean small fortunes to stamp col- lectors. An illustration is furnished from France. Recently, a government printer carelessly tore a roll of blank paper on which the stamps were to be printed. He mended it with a strip of red paper. When the stamps, which were printed in green, were finished, ten of them appeared on a red background. They are already highly valued by collectors and doubtless will in- crease in price. WATER KEPT FROM GASOLINE BY.SAFETY VALVE To prevent pumping water into the automobile gasoline tanks from filling sta- tions, a special valve has been devised to fit on the end of the suction line inside the station tank. Its essential feature is a float which sinks in gasoline but rests on water and locks the pump before water at the bottom of the tank can be drawn into the cus- tomer’s auto. The station attendant can quickly pump out the water in the tank, thus al- lowing the float in the suction-line valve to fall back and unlock the gasoline pump. a Rust, dirt and aTeRIe ms scale in the bot- tom of the tank are also excluded by the valve, which is made of bronze. “Ss _ eal

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POPULAR MECHANICS 635 WHERE LATEST DESIGNS IN PLANES ARE TESTED Views in the Plane-Testing Laboratory at Langley Field; the Huge ind Tunnel, One of the Planes Tested and the Large Fan Unusual experiments that will have a far-reaching effect on airplane design are being» conducted at Langley field, Va. The air resistance of the increasingly pop- ular radial air-cooled aviation motor, which now is one of the most serious drawbacks of this type of airplane power plant, is reduced by more than thirty per cent by a radical change in streamlining the cowling, which diverts the propeller slip stream around the motor and yet does not interfere with the cooling. The in- r crease in efficiency resulting from this change is said to be the most valuable aviation improvement since the World War. Wind-tunnel investigations have revealed that twenty-five horsepower is lost in overcoming the wind resistance offered by the motor, without streamlin- ing. Therefore, the new cowling in- creases the effective horsepower of the plane by approximately eight horsepower. The saving, in the case of a 200-horse- power motor, for example, amounts to

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636 three gallons of gasoline to the hour of flight. The new cowling device, which re- sembles a large bowl with the bottom knocked out to make room for the pro- peller shaft, is placed over the engine. It is the first result of a cowling and cooling investigation undertaken in the new $150,000 propeller-research tunnel. ROLLER SKATES SPEED PHONES IN EARLY HOURS Telephone Girls in Los Angeles Exchange Wearing Roller Skates to Save Time in Answering Calls Young women on duty in the early morning hours at a Los Angeles telephone exchange, wear roller skates fo speed them in moving to different positions at the boards. The plan is reported to have been successful, as it saves time when only a few attendants are at work, ANCIENT BURIAL PIT REVEALS ROYAL SPLENDOR Splendors of a royal court that flour- ished 5,000 years ago have been unearthed in the cemetery of Ur of the Chaldees, where the hodies of forty-five sacrificial victims, thirty-nine of them women, have been found by excavators. The discovery revealed an amazing display. There were gold hair ribbons, wreaths of gold leaves POPULAR MECHANICS and flowers, inlaid pendants, large ear rings, combs with flowers of colored inlay, pins and necklaces of gold. Among other objects were three harps, one adorned with the golden head of a bull, and the statues of a pair of rams, their heads and legs of gold, the horns and hair of lapis lazuli and the fleece of white shell. The statues have sockets which indicate that they once were the support of some article of furniture or ornament that long since has disappeared. After the bodies of the sacrificial victims had been placed.in the pit, earth had been heaped on them and tamped down, while other possessions, servants and live stock were buried to complete the ceremony. MAGIC EFFECT OF COLOR KEEPS STEEL COOL That color may be employed indirectly to increase the strength of some struc- tures is the interesting conclusion sug- gested by a series of experiments by an English authority. He has found that a certain shade of blue diminishes the effect of the sun’s rays on steel and preserves a more even temperature. Since extreme heating and cooling may tend to weaken a structure, under certain conditions, the proper color might insure longer life and greater strength. Physicians long have recognized the importance of the right color in hospitals and sick rooms and in the home, the use of color in decorations being studied more carefully. SPRING CLIP FOR VALVE TAPPET ELIMINATES NOISE To stop tappet noises in cars which have devel- oped that trouble, a spring-steel unit is inserted be- tween the valve stem and the tap- pet head. Once in place, it holds the tappet in constant engagement with the camshaft and can be installed in a few minutes.

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POPULAR MECHANICS ° 637 Polar Bear Performs for the ““Talkies”; the Recording Apparatus Was Placed at the Open Door of the Bear’s Cage While the ““Mike’’ Was Held near the Screen POLAR BEAR IN TALKING MOVIES PROVES GOOD “ACTOR” To obtain “talking” moving pictures of a polar bear at the zoo in Oakland, Calif., photographers placed their machines close to the animal’s cage and then opened the door so they could film close-ups of the inmate. The bear seemed to enjoy its brief experience as an “actor,” jumping in and out of its pool and giving a few roars and grunts which were recorded for the talkies. MOON LIKE VOLCANIC ASHES TEMPERATURES SHOW No one knows for sure of what the moon is made, but temperature tests dur- ing the last eclipse indicate that it is composed of a porous substance possibly not unlike the volcanic ashes common in various parts of our earth. Scientists are quite certain that the moon is not like solid rock in structure. Drs. Edison Pet- tit and S. B. Nicholson, of the Mt. Wilson observatory, made careful measurements of the cooling of the moon as it went into the earth’s shadow. Similar measure- ments were made in a laboratory as to the cooling of substances such as granite, ba- salt and quartz. The material that cooled in a manner most like that of the moon was pumice, a porous stone of volcanic origin. The tests further substantiate the theory that the craters on the moon were caused by volcanoes. PAPER-COVERED FOOTRESTS AID SHOE-STORE CUSTOMERS One of the latest conveniences for the shoe store is a footrest with a reel of paper that isunwound as needed to provide a fresh, clean sur- face for the pa- tron’s stockinged feet. The reel car- ries sufficient pa- per for many days, and the stool is of such shape and size as to be handy and comfortable. @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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Pot Covers of Different Sizes Are Conveniently Held in This Wall Rack of Enamel; It Also Has Hangers for Spoons Small Electric Range and Broiler Combined Takes Anything Up to an Eight-Pound Roast, Reduces Cur- rent Consumption and Saves Time; the Top Part Has a Three-Compart- ment Steamer for Vegetables This Portable Gasoline Heater Can Be Swung at Different Angles for Better Direction of Its Warmth; It Is Safe and Simple Extra Service Is Rendered by This Double Strainer with Two Sieves; They Come Apart without Diffi- culty for Washing To Prevent Burning of Toast and to Save Cur- rent; Automatic Electric Toaster Has a Setting Device for Giving Different Degrees of Brownness, and Turns Itself Off 638

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Small Electric Washer Can Be In- stalled beside the Washbowl in Bath- room, or Other Convenient Place; Cleanses All Sorts of Garments and Will Take Bulky Articles Like Sheets and Pillow Cases Mop Wrung by Crank Instead of in the Usual Way Has a Mechanical Hand That Holds the Cloth Flat against Floor Surface When in Use Washing Dishes without a Pan: This Handy Mop Has Space for Soap in the Base of Its Grip and Uses Odd Pieces to Reduce Waste

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POPULAR Inner Solid Wheel Resting on Block, Shows How Bus Is Supported if Outer Tire Is Punctured SAFETY WHEELS FOR MOTOR BUS AID IN BLOW-OUTS Small emergency wheels with solid tires are attached inside the regular wheels on motor busses of a western line. Should the tires blow out, the smaller wheels would support the load until the bus could be halted and repairs made, thus reducing the likelihood of overturning on curves or while running at high speed. The wheels can be attached in a few moments. A CORRECTION In an article on “Women of the Air” in the January issue reference was made to Glenn Curtiss as the inventor of the aile- ron, thereby doing an unintentional in- justice to Dr. William W. Christmas, of New York, who was the first man, after the Wright brothers, to fly a plane, and who invented the form of aileron now universally used, as a movable section of the main wing. The error was due to a mistaken understanding that the Curtiss plane, with interplane flaps, which he flew on June 26, 1909, was the first practical ship to get away from the Wright system of wing warping. A search of the records since discloses that Doctor Christmas used ailerons on a plane which he flew March 8, 1908, and that these ailerons closely re- sembled the modern article, the patent on which he sold to the United States government. MECHANICS FORECAST INVASIONS OF PESTS TO PROTECT CROPS Predictions of insect-pest invasions may be broadcast like the weather forecasts, if plans being developed by Roy Melvin, at the Iowa State college, materialize. By careful observation of the temperatures during the winter, measurements of the amount of oxygen consumed by the eggs and larve of insects in the cold season and comparing these factors, he has worked out a method of calculating the percentage of insects likely to survive the winter. Last year his forecasts on the abundance of corn borers were verified later in the season. AUTOMATIC FOCUSING POSSIBLE FOR HOME-MOVIE CAMERAS A device which makes it as easy to keep a movie camera, or any type of ordinary film or plate camera, in accurate focus on a moving object as it is to do it with a focal-plane shutter camera, is now avail- able for amateur photographers. It con- sists of a fast lens and shutter, fixed in a micrometer mount and focusing on a prism, on which the picture can be seen through a magnifying eyepiece which en- larges it about ten times. A train ot gears can be added to automatically keep the camera lens in the same focus or, for slower work, the device can be focused, the exact distance to the object read from a scale, and the camera lens focused to the same point. A mi- crometer adjust- ment permits movement of the prism toward or away from the lens, so that it is possible to match the exact distance between the cam- era lens and the film plane, and then use it to check other lenses to the camera, as the lens of the device is easily removed to set other lenses, such as a telephoto, in its place for accurate focusing. @ Reindeer were imported to America as early as 1892.

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asy Handkerchief “~ > KNOW, Amos; most people think that handkerchiefs have no other business than noses, but listen. The performer collects all the handker- chiefs present.. We'll say there are four. He drops them into his hat. He shakes them up. Then comes the trick. With- out even as much as a single glance, the alricks > Sam Brown * performer removes each person’s “hanky” as he calls for it. Isn’t that a lot more mysterious than noses? And it’s dead easy. The first handkerchief is gripped through the felt; the second one is pushed up under the lining; the third is the performer’s own, rolled into a compact little ball so as to be The Stretched Handkerchief Makes Big Ones Out of Little Ones, and, Top, Any Owner Can Get His Prop- erty Returned from the Hat without the Performer Even Looking at It 641

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642 distinguishable from the others; the fourth is simply dropped in. Well, with a layout like that, all the performer need do is re- member which hanky is which and distribute them accordingly. “Rudy” Kipling tells us how the elephant got his trunk, but he gives no recipe for making big handkerchiefs out of little ones. Allow me. The performer bor- rows a handkerchief. Re- marking that it seems a bit small, he twists it tightly—rope fashion— between’ his hands. In full view, the little hanky stretches out and be- comes a full-sized hand- kerchief for the benefit of an amused audience. It’s done like this: The handkerchief is first taken by the extreme ends between finger and thumb of either hand. It is held slack. The per- former then twists it up POPULAR MECHANICS Two Stages of the Stretched-Handkerchief Trick, at the Top, and, Bottom, Trying to Burn a Bit of Fireproofed Linen into a rope, and under cover of the rapid move- ment, the hands are for a moment turned backs downward, so that the handkerchief lies across the hands. The little fin- gers at once curl inward, as shown, and the hands are again turned backs upward. And what have you? The handkerchief now lies with a doubled- up portion of the ends concealed in either hand, although its appearance is much the same as it was before. To stretch the hand- kerchief, the twisting is carried on, and during

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POPULAR MECHANICS 643 magician. He previously soaks his handkerchief in a concen- trated solution of borax and water. Such a hanky appears much the same as every other with the exception that it is quite some little salamander, and The Reef Knot, an Interesting Illusion Which Can Be Performed with a Borrowed Muffler; the Drawings Show Various Stages in the Tying of the Apparently Intricate Knot, Which Then Dissolves at a Tug the twisting the spare part of the hanky is allowed to escape little by little, first from one hand and then from the other, until the man-sized product is exposed to view. Try this: Light a match and hold it under a handkerchief for half a minute. What happens? Well, most people have to buy a new handkerchief, but not the pan

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POPULAR MECHANICS not! For the performer simply passes the silk square behind his back and the knots oblig- ingly melt away! A knot, called a reef knot, is at the bottom of the whole busi- ness. Like this: The first knot doesn’t seem to mind expo- sure to a match flame the least little bit. The performer takes some- one’s beautiful silk muffler, and ties the ends tightly into knots. Gr-r-rr! Does the owner of the muffler get mad? He does The Penetrating Coin, Which Apparently Passes Right through a Twisted Handkerchief; the Sketches Show the Working of the Trick, and the Circle Inset, the Right Thumb Making the Double Fold is made by passing the end of the handkerchief in your right hand be- hind the opposite end held in the left hand, as shown. In making the second knot, the end in the right hand is passed in front of the oppo- site end in the left hand, as illus- tra col sel twi wil pic Thi tra Rig Abs Bel

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eT ses the and the he the the xht po- us- trated. Such a knot looks dis- couragingly wrapped up in it- self, but if you will take the two ends AA and pull, you will get the reef-knot effect as pictured., In this form, POPULAR MECHANICS 645 the kerchief. The coin is then twisted The Final Step in the Pene- trating-Coin Trick, Top, Right; the Juggling Trick, Above, and, at the Right and Below, the One-Hand Knot, Tied by Flipping the Hand tightly within the hanky, but, no, the magician pulls it right out again! Do it this way: Hold the coin in your right hand at the tips of the thumb and first knot can be slipped off instantly and with one hand, while you are holding the silk behind your back. Here’s a good one! The per- former takes a coin in his right hand and covers it with a hand-

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646 finger. Cover it with the handkerchief. Then, to show that the coin is still there, you stretch the hanky tightly over it, using the thumb and first finger of the left hand, as shown in the back view. And therein lies the whole trick. Notice that the thumb of the right hand passes over the left-hand thumb, and then grips the coin through the fold. Not satisfied yet, the performer lifts up the corner of the handkerchief next to the audience and shows the coin stilk under- neath the cloth. And now, with a quick flourish, the performer shakes out the handkerchief, still retaining his grip on the coin. This brings the coin to the out- side of the now diagonally folded hand- kerchief, as shown. It is wrapped up in this condition and then removed by sim- ply untwisting the handkerchief and slid- ing the coin out into view. Try it! Balancing a handkerchief upright on POPULAR MECHANICS your hand is a smart juggle which is quite puzzling. Of course, your audience is un- aware that you have twisted’ a stiff piece of fine wire inside the handkerchief to give it the necessary rigidity to sustain its own weight. Most people find it hard enough to tie a knot with two hands. So, try to imagine that awed look of amazement when the magician, with a sudden outward flip of his hand, ties a knot in the center of a large silk handkerchief. This little interlude is quite easy. Hold the handkerchief as shown. A quick for- ward movement of the hand will bring the end A around so that it can be gripped between the first and second fingers at the point marked B. Holding the end A at the point B, the performer gives the hand- kerchief a quick outward toss, the knot magically forms in the center, and there you are! SLIGHTEST TREMORS OF EARTH SHOWN ON NEW RECORDER Earth vibrations as slight as one ten- thousandth of an inch are registered on a new recorder which is being tested in a government laboratory, thirty-five feet be- low the surface of the ground. Records are made photographically, the displace- airplane or automobile, and some of the first waves will pass a quarter of the way around the world in ten minutes. The new instrument detects earthquake waves which may be flowing from one side of the sphere to the other, and is expected to prove of still further aid in predicting the occurrence of quakes that might be disastrous. Scientists keep track of the ments or vibrations being shown 1,000 times greater on the record than they are during the actual movements incident to a quake. Study of the tremors with this and other in- struments has- shown that the shocks travel at tre- mendous speed, at normal variations in earth move- ments and are sometimes able to issue warning when unusual tremors are about to take place. @ Names and ad- dresses of manufac- turers of articles described will be promptly furnished, least four times as fast as the swiftest Quake Register in Government Laboratory below the Ground, and Sample of the Record It Makes free, by our Bureau of Information. pl o ZI 2 > th al

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POPULAR MECHANICS 647 Greater Selectivity for the Old Set Sets that may have been amply selective a year or so ago now fail to separate the crowded broadcast channels. Selectivity is, of course, a matter of circuit design, the present-day set being selective becauge it has low-resistance circuits, well-shielded tuning units and the tuning condensers now used have the proper capacity varia- - tion. There are several ways of sharpen- ing the tuning of the old set, however, without making any radical changes. A variable high resistance, shunted across the antenna and ground posts, reduces the signal pick-up from powerful locals when the operator is trying to cut through for distant stations. Another method is to make the detector less sensitive, which may be done bysubstituting a variable grid- leak for the fixed type or by placing a vari- able high resistance across the grid and grid-return terminals of the detector socket. Shielding will add materially to the efficiency of the old set. This may be done by lining the cabinet with tinfoil, shel- lacked to the inside for general shielding, and by providing metal partitions between the tuning units, New Rectifier for A-Eliminator A new dry- plate rectifier for A-elimina- tors of the type shown in the illustra- tion has re- cently ap- peared on the market. It re- places the dry unit originally supplied with the A-power device and is said to give longer life and quieter operation. 3eing inclosed in a perforated metal case, it may be fastened to the eliminator in the manner shown. Two connections are all that are necessary to install it. An Experimental Microphone The microphone for the beginner, shown in detail in the illustration, is a homemade device that requires but one dry cell for its operation. When connected to the bat- tery and headphones or a radio amplifier, ~——_ 5} -7 CARBON _FROM t ; OLD BATTERY =. 1%, PIECE OF 3 PENCIL 6 —4--/ Y Uy TRANSMITTER Construction Details of Homemade Experimental Micro- phone; Below, (ompleted Unit Showing Connections it will transmit speech with good audi- bility. The person speaking should stand about 1 ft. away from the “mike.” The con- struction requires little comment. The pencil, sharpened at both ends, is placed loosely in the holes in the upper and lower carbons so that it will move freely. Do not use too much battery; 1% volts is sufficient for good results. The author has found this device very sensitive, and many interesting experiments can be worked out with it. The carbon may be obtained from discarded batteries—A. C. Alderton, Wanganui, New Zealand. Homemade Aerial-Coupling Condenser In trying out several short-wave hook- ups, I noticed that the commercial an- tenna-coupling condensers are not easily adjusted for maximum effect. The sketch shows a simple homemade type that works satisfactorily, as it provides a means of very fine adjustment. The sketch is self-explanatory. Small variable condensers of this type are useful for neu- tralizing or BRASS ‘SOLDERED balancing, and the ex- perimenter will find it convenient to have several on hand.—A. B. Robbins, Muscatine, Ia, (THREADED ‘

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who was lost on the tragic voyage to South America, that the “op- erator of the ‘Vestris’ handled his end of the distress traffic in a com- Arthur Jensen, Radio Operator of the S. S. “American Shipper,” Telling the World the “Vestris” Survivors Had Been Rescued \ HILE science is constantly devising means of securing safety on land and sea and in the air, in the final analysis it remains for mankind to furnish the he- roes. Radio, or wireless, as it was called in the days when the world first thrilled at its efficacy and felt more secure because of its existence, provides a way, but it still takes men to do the deeds. Michael J. O’Loughlin, the newest name on the permanent roll decorating the foun- tain of honor in front of the barge-office tower, down at the Battery in New York, received the same kind of commendation that was given comrades in the service who have thought of others before they have thought of themselves. A federal radio official said of this man, 648 mendable manner from the time this observer first heard his signals to the last transmission on failing power a few minutes before the last signals on his emergency set were sent, notifying all stations the ship was being abandoned.” There are twenty-three additional stories, each with its own scenery and characters and all with the same plot, which tell of the cruelty of the sea and the self-sacrifice of men whose minds responded so bril- liantly in emergency, and whose gener- osity was so great that their lives were ‘their gifts. No matter whether the ship foundered on a reef, collided disastrously in fog or was a victim of fire or storm, each of the wireless operators who died at their posts, did the same thing—gave his life for others. Then there are those who have shown forgetfulness of self in relinquish- 1 AVL IF ae | oy ) FEE > {

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or ve h- 4 - s Q ing places in lifeboats or giving up means of remaining afloat. One youth rushed from his bed, pajama- clad, and in the three minutes. before the ship sank, adjusted the auxiliary wireless set and succeeded in getting a call through. When both dynamo and storage batteries had been submerged by the sea, another operator and his chief succeeded in mak- ing the set function temporarily. After performing fast work with the key, the wireless man of an Atlantic vessel gave up his life belt to a passenger. Out on the Pacific coast, another relinquished his hold on driftwood in order that it might support a woman. The memorial which bears the stories of sea dramas was dedicated in 1912, after Jack Philips, the wireless operator of the “Titanic,” had inspired the world to create a memorial to marine messengers. Under the inscription, “In memory of wireless operators lost at sea at the post of duty,” appears first the name of George Eccles. He was instrumental in saving 200 per- sons when his ship, the “Ohio,” went on an Alaskan reef nearly twenty years ago. In the thirty minutes left to the “Ohio,” he raised an Alaskan station which sig- naled two near-by vessels. In 1910, Stephen Szepanek flashed the call for help cu | W nN 7 pital y POL) aye A oe" i Ni : Cage-Type Aerials Swing in Festoons from the Basket Masts of Battleships; This Is a View from the Mast- head of the “New Mexico” 649

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Sake: hehe. adeieall . when the railroad-car ferry which plied the Great Lakes sank as it approached Milwaukee. Whether a submerged rock or shifting loaded cars caused the plunge of the ferryboat is not cer- tain. When help arrived, there was no trace of the vessel, On the Pacific ocean, in 1913, young Lawrence A. Prudhunt refused a place in the lifeboats to stay at his task of sum- moning aid to the “Rose- crans.” Due to his ef- forts, three men were saved of the crew of thir- ty-six. There were no passengers on board. It was Donald Camp- bell Perkins who worked POPULAR MECHANICS being awakened when the “State of Cali- fornia” struck a reef in Gambier bay, Alaska. As so frequently happens, the dynamos failed and his main wireless set was rendered useless. However, in those three minutes he brought the auxiliary set, which runs on storage batteries, into use and succeeded in getting aid. He was made a prisoner when a lifeboat broke loose and jammed the door of the cabin, and sank with the ship. When the “Monroe” was in a collision off the coast of Virginia, in January of 1914, Ferdinand J. Kuehn stayed in the wireless room flashing out calls for help until he was sure that assistance was com- ing. As he went on deck to assist in load- ing the small boats, he met a woman cry- ing for help. Since she had no life pre- Lieut. Pedro C. Andres, of the Cuban Navy, with an Automatic SOS Sender so desperately fast after of His Own Invention, Top, and the Directional Loop of the “Leviathan” se he hi: ne di: so in st pa ot “ th ju

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me me a der POPULAR MECHANICS 651 A Lone Sentinel Standing Guard over the “Celtic,” After the Big Liner Ran Aground on the Rocks, While Entering Queenstown Harbor, Ireland, without a Pilot in a Dense Fog server, he gave her his own and helped her into a lifeboat. There, by the davits, his foot slipped and he fell into the water, never to be seen again. In April of that year, Walter E. Reker displayed his resourcefulness and bravery in a collision when the “Admiral Samp- son” and the “Princess Victoria” crashed in Puget Sound. The “Princess Victoria” stood by so close to the sinking vessel that passengers could climb frém one to the other until damaged oil tanks caused the “Admiral Sampson” to catch fire. Al- though the operator of the slightly in- jured vessel wirelessed that he would send for help, Chief Operator Reker stayed at his post until his calls were through. Afterward he assisted passengers to the lifeboats. When the last load had left, he reported to the captain on the bridge and went down with the ship. A man of only seventeen years offered his life for others and gave it for one woman when the “Francis H. Leggett” foundered on the Duxberry reef off the west coast, in September, 1914. Clifton J. Fleming went down with the ship after Staying at his post. Coming up in the pounding sea, he grasped a piece of wreck- age for support. When he discovered a woman struggling in the water, he as- sisted her to the drifting wood and re- linquished his hold upon it, since it would not support both. His assistant, .Harry Fred Otto, had stayed with him in the wireless cabin sending out calls, until the Pacific closed over the little room. He was not seen again. It was Adolph J. Svenson who, with his chief Loren A. Lovejoy, rigged up an auxiliary set as soon as the water ran off the storage batteries at another lurch of the sinking “Hanalei.” When the wire- less cabin was swept overboard, he assisted the chief in sending signals to the near- by Pacific shore with a flashlight. In spite of the fact that men on land could see the signals, it was almost impossible, due to the storm and terrain, for them to effect a rescue. When only wreckage remained of the “Hanalei,” Loren Lovejoy was picked up from the piece of driftwood to which he was clinging by a passing ship. Adolph Svenson was added to that band who died on duty. There follows a period of years when war added hazards to the seas. Mines, submarines and the danger of collision

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POPULAR MECHANICS “City of Athens,” a steamer in the coastwise trade. Francis Joseph Doherty, the wireless operator, went down with the ship. Emile H. Hulsemann’s last message was heard on Feb. 29, 1920. It is believed that the wireless of the “Cubadist” was torn away in the gales that characterized that season off Cape Hatteras and which took toll of this ship among the coastal traffic. When the “Macona” struck a rock off the Nid- igen light on the Swed- ish coast, Lawrence B. Robinson, wireless op- erator, lost his life. Only one of the crew of fifty was saved. Evidences of fire on the drifting wreckage, marked with the name of Navy Radio Operator Broadcasting Weather Maps to Ships at Sea; This another ship to join the U. & U. : > mysteriously sunk, the System Is One of the Most Important Advances in Navigation “Swiftstar,” gave evi- from running with few lights were new perils to augment wind, fog, fire and un- charted reef. George Arundel Gear gave his life dur- ing those troublesome days. His ship was the “Manga Reva.” His message, “Come as quickly as possible; am drifting before the wind with no boats,” was sent off the coast of France. Neither he nor his captain had the comfort of knowing that other ships were racing to the rescue, ‘ for his last call reported, “No responses to calls for assistance. Going fast.” During the war, when armed naval guards were aboard merchant steamers, the tanker “Motano” was torpedoed by a submarine. Sinking within a minute’s time, Russell A. Williams, the wireless operator, was among those to lose their lives. Another disastér in which the ship sank so rapidly that very little rescue work could be done, was that off the Atlantic coast, on May 1, 1918, when, during a dense fog, a French warship rammed the dence that Ernest E. Dorsey was given no second to flash SOS. Mariners believe that this tanker was struck by lightning. Two days after Christmas, 1923, within an hour after he had signaled that the number-one hold of the “Conejos” was filling with water, Fred Salim sent a last SOS reporting that the ship was sinking fast and giving its position in the Black Sea. Although its sister ship, the “Clon- tarf,” and other vessels rushed to the aid of the distressed boat, no traces of it were found. When the “Haleakala” was twenty-five days overdue, it was decided that it had been lost in the hurricanes which were sweeping the Atlantic coast. Peter L. Bacuinka was the radio officer who went down with this ship. About 200 miles west of the Philippines the freighter “Elkton” went down after the wireless operator, Charles F. Ruble, had flashed that it was disabled. A smear of oil spreading for five miles was the only trace found of the “David al de lin m: tu th tel ra Ste Sig de ho sir mi Wi in: ics me ice rea gla wit ani ans

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ve ad re Le nt les ter ess ied les vid POPULAR MECHANICS 653 C. Reid” when rescue ships ar- rived. They had plowed through a storm area off the Azores after they received messages calling for help in October of last year. Mau- rice Black first radioed, “We are in a bad way. Come over.” “We are going fast,” was the cry seven minutes Jater. There are three other men who were licensed to handle ships’ wireless and who were lost at sea at their post of duty. Boris Michael Dutko was on the “Brin- dilla,” which was lost in Decem- ber of 1919. James J. Curran’s Left, Combination Radio and Pho- . “ ” . nograph Unit, with Three Turn- ship, the “Moreno,” went down “‘ibies: Right, Dynamic Speaker in June, 1917, off the Azores. Lawrence M. Waring, Jr., lost his life on the “Cotopaxi,” which foundered off the Florida coast in December, 1926. At the dedication of the memorial, Com- missioner H. Cabot Ward linked science and men and deeds in saying: “It is a wonderful quality of the human soul that new conditions always bring new manifes- tations of heroism.” Device Stops Man-Made Static The filter shown in the sketch is a new development in the radio field along the line of devices designed to eliminate man- made static at the source. The manufac- turer maintains a special service to help those who are confronted with such in- terference, which is a real problem for radio listeners. It is claimed to take out static caused by motors, blowers, fans, sign flashers, ice machines or any electrical device using 110 or 220 volts regardless of horsepower. The connections are simple, and the unit is housed in a metal container with holes for easier installation, MOTOR, GENE BLOWER OR oT Radio and Phonograph Amplifier A simplified arrangement of phonograph pick-up unit and power amplifier com- bined with a radio set is illustrated here- with. This device is now available for small motion-picture theaters or other public places where loud volume and con- tinuous programs are required. Three phonograph turntables are arranged to per- mit interchange of records without inter- ruption. The dynamic speaker supplied with the combination unit is mounted on a large baffleboard which is supported in easel fashion. A. C. Tube-Operating Hint A.c. tubes, such as the CX-326 and C- 327, and particularly the latter, operate at comparatively low voltages and high cur- rent; the CX-326 at 1.5 volts and 1.05 amp., and the C-327 at 2.5 volts and 1.75 amp. Unless a socket whose spring ter- minals make very good contact with the tube prongs is used, the contact @ Popular Mechan- ics radio depart- ment offers its serv- ices free to all readers. We will be glad to help you with your problems and will promptly answer all inquiries. Left, Filter Device Inclosed in Metal Container; Right, Diagram of Connections resistance between the tube prong and the socket terminal may be sufficient to reduce current sup- ply to the C-327 to a value that is too low for satisfactory operation.

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HE BENCH described here is designed to harmonize with the Spanish radio cabinet illustrated in the October and No- vember, 1928, issues of Popular Mechan- ics, but it is a handsome piece of furniture, and well worth building for its own sake. The construction is simple and the up- holstering is easily the legs of the bench should be made to correspond, and Fig. 8 details this con- struction. Cut four pieces of 1 by 6-in. rough walnut for the legs, smoothing two sides of each. Blanks for the two rails are made from stock 3 in. wide by 10 in. long. Glue the rounds to the stretcher, then add the legs and slip the seat on. Rein- force the upper ends of the legs by nail- ing through the done. Either hard or soft wood may be used for the frame of the seat, and the construction is so well shown in the illustrations that no details are neces- sary. The four legs are turned from 2 by 2-in. rough wal- nut, which, if accu- rately centered on the lathe, will easily give the largest re- quired diameter of seat. If the work has been well done, the assembly should be square, and the stool should stand with very little ten- dency to rock. Be- fore adding the up- holstery, fill the stretcher and legs, then varnish or wax the walnut to corre- spond to the finish given the radio cab- inet. Unroll cotton batting on the seat, 1% in See Fig. 4. A little time in turning is saved if two legs are turned from the same stick. Use rough walnut stock, 1 by 2-in, for the stretcher, which is detailed in Fig. 6. If the legs of the radio cabinet were made ot flat stock, 654 lapping it back and forth until the pile, when compressed, is 1% in. thick, step- ping back the ends of the upper plies to give the curve to the edges. Allow the cotton to project a little beyond the sides and ends, so that the rail edges will not Bm §€=6 om ly a ” 163 -

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POPULAR MECHANICS 655 AY DETAIL OF CORNER CONSTRUCTION CLEAT, 2 REQUIRED Fic.3 RAIL DETAILS LEG DETAIL ROUND DETAIL 4 REQUIRED 2 REQUIRED

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656 POPULAR MECHANICS with a narrow chisel made by hammering and filing a round-nosed flat point on a spike. Use a hardwood block when out- lining. Then lay the ornaments, upside down, on a soft-wood block and hammer up the centers and petals, using the round end of a glass-cutter handle, the ball of a hinge pin or any other available tool. “Antique” by heating in a flame, punch the centers for round-head brass escutch- eon nails, and nail them to the stool rails, as indicated, spac- jut out when the covering is drawn tight. Cover the stuffing with a piece of stgut cloth, tacked in the cen- ters of the sides ing them evenly with dividers. and ends. Finish tacking by working toward the corners, and apply the tapestry. Cut a strip of plush, 4 in. wide and 6 ft. long, for a band. Prepare a strip of nar- row strap iron by punching holes every inch. Nail this around the top edge of the seat frame to hold the upper edge of the plush, pile inward. Sew the corner of the band and pull the plush down over the iron until it is tight. Tack the lower edge under the rails. Sew the metal fringe to the band. The seat illustrated was covered with brown brocade having gilt flower designs and stripes in light blue and old rose edged with black and yellow. This same material was also used for the radio grill. For the band, a dark vermilion bordering on maroon was chosen, and this was used as backing for the radio-cabinet plaques. The ornamental nail heads, shown in Fig. 7, are laid out on 134-in. circles. Make a full-sized tracing with which to trans- fer the design to 2l-gauge sheet brass. With tin snips cut the designs into indi- vidual squares, and cut the outlines with a jewelers’ saw. Prick-punch the centers, scribe the center circles, and outline them The corner clasps are four in number, being designed as an overlapping pair of nail heads. The photos ac- companying the drawings show the following opera- tions: page 655, nailing the seat frame to- gether and boring the holes in the cleats for the ends of the legs; page 656, the lay- ing of the batting for the seat covering, and the paring off of a round to take the shoulder of the stretcher; page 657, bor- ing a leg for a round, marking for the stretcher flat on a round, hammering out a nail head and two of the finished heads. If you cannot get good walnut to make this stool, write to the Radio department, and we will tell you where to obtain it. Do not “spoil the ship for a ha’p’orth o’ tar” by using soft wood. a) ~ SS 7 vv Ili

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we . POPULAR MECHANICS 657 eee BRASS NAIL HEAD,22 REQ. Fis.7 ¢ CORNER CLIP |; 4REQ. |

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To Prolong Their Life, Connect Tubes of Like Characteristics in Groups on Variable Strip-Type Resistors, as Shown Be- low (Left) at A, B and C: Adjustment for De- creasing Voltage Is Then Made with Master Rheo- stat E; with Most of Re- sistance of E in Circuit, Vary A, B and C Until Voltmeter Placed across Filaments Shows Correct Voltage, Then Solder Clips in Position; Perma- nently Connect Voltmeter ; Now Varies Voltage Applied to All Tubes in Correct Proportion | R.F. TUBES DET. AUDIO AMP. TUBES ! 2 3 4a 5 ) ~ / WIRES / ‘ ; VOLTMETER/ SOLDERED / —_ RUBBER TUBING { A Bs c ' TOGETHER SLID OVER JOINT E VARIABLE. RHEOSTAT of OF SUITABLE VALUE ; FILAMENT Above, a Short Piece of Rubber Tubing Insulates AND CURRENT- rh TERMINALS Soldered Joint; the Wire Should Be Twisted to In- J CARRYING CAPACITY Z OF RADIO SET sure a Good Mechanical Connection DOUBLE SOCKET = —— r ' s. a 4 e— — . ‘ & ee t % & AY ) ¥ A ‘ - 4 un = re “4 nila ZZ ee “ “4 eg ip» if | ¢ a “A v' an ‘a Bending Aluminum Sheet for Homemade Shield Boxes Is I Not Difficult, if Done as Shown Above; Right, Lead-In and De Power Supply from Double-Outlet Wall Plate; Antenna and By Ground Connections Are Made to One Plug and the 110- } g Volt Supply Connection to Another i, Gr“ Cigale” = AS

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— ae ee la SMALL 110- - VOLT LIGHT ‘ ] UNPUT TERMINALS OF THE DYNAMIC A.C: UNIT SWITCH Mounting an Indicating Lamp for A.C.-Operated Dynamic Speaker as a Reminder to Turn Off Current; a Hole Is Bored in Front of Speaker Cabinet and Light Mounted behind a Jeweled Port and Supply Line a SHORT — NIPPLE. “4s FLANGE NUT Connected in s Shown Brass /“$ ff "GROUND WIRE WASHER COUPLING ABOUT 6 FT. LONG OLD BRASS WELL POINT | SOLDERED TO WASHER An Excellent Ground Con- nection Made from 5 Ft. of Brass Pipe, Threaded for an Old Brass Well Point and Ground-Wire Connection; When Ground Wire Is Con- nected Cover Top Connection with Waterproof Paint; Be- low, Code-Practice Set Op- erated from 110-Volt House- Lighting Supply Gives a Steady Signal Which Does Not Change Pitch; Lower Right, Soldering Tip on Broken Tinsel Phone Cord Is Not Difficult, if the End of the Lead to Be Soldered Is First Wound with Bare Wire ¢ 30-HENRY CHOKE \ ry | 8, ae] B+i60 s BELL- RINGING TIP SOLDERED IN PLACE AND END OF CORD WOUND WITH THREAD “ TRANSFORMERS Experimental B-Eliminator ‘ Employing 112-Type Tubes . as Rectifier; R-1, 5,000-Ohm 5 Variables; R-2, 2,000-Ohm % Mica} Condenser in Ground Lead Fixed; Use 1-Mfd. of Receiver Pe °

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POPULAR MECHANICS METAL SHIELDS GROUNDED TO : Geeta CHASSIS OF THE SET fo ‘etm | eee a >ppete _ 3 ' it } : | : | Ww ! i i 1; | -——++ Ba0v. ee ' i 1 /\ at ‘\ | sp ¥ = '= 1 = 100,000-OHMS ne ; ex > tic |Z FILAMENT ae } SwiTcH ; IMF] : tu = Seo. frag ag a oo e-- BIA mi an roun ‘osts with Pointed ires =~ as Shown, Protects Set during Electrical = *¥CHASSIS GROUND fe Storms Oscillation Control for Tuned R.F. Sets, Obtained we with 3-Tap Variable Resistor; Note Filament i . Switch, When ee Cuts Resistance Out of an | -Circuit be ltearp ircui PLATE-L] ~30-HENRY CHOKE : th B+ TO SPEAKER + se * PLATE *30- F a 3O-HENRY CHOKE owen | 1 } ae if \\ > — W Double Filter Arrangement, Used in Push-Pull be- BRACKET hu tween Power Tubes and Speaker, Claimed to Give tic Good Response at All Frequencies Instead of Cut- ting Off at Certain Frequencies as in the Case of co Many Output Transformers . 4 _) Subpanel Brackets Made from Ya-In. Brass Rod, Bent to Shape j and Threaded at the Ends; Hex- agon Nuts Hold Panel in Place tr Left, Handy Bat- ad tery-Cord Arrange- is ment for Test Table ter Makes Quick Con- nections Easy; the the Counterweights Keep f the Leads Out of ol the Way When Not po Required tri eli; : Z ne Ae A ~ Cas | An —Y), ‘ tri rt | i } o ' eit fi : N lea GFA tiv ce pac the of to | sid Th H Shielding the Control-Grid Lead of the Screen- the ( ‘WEIGHT Grid Tube by Means of Strips of Tinfoil; the Foil - x ORD Is Wound Tightly around the Insulation on the S FLEXIGLE COR Lead, and Is Then Grounded to the Stage Shield alre to;

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POPULAR MECHANICS 661 Curing Noise in Set The writer has a set that has been per- forming satisfactorily until recently, when, if anyone walked across the floor. heavy static noises issued from the speaker. Supposing it to be a loose con- nection, I cleaned the battery terminals, examined the tube and socket connec- tions and renewed the speaker cord, but without improvement. I put in new tubes and batteries; still no improve- ment. After several weeks of this inter- ference, I found the ground clamp on the water pipe in the basement badly corroded and very loose. This pipe being directly beneath the floor of the room in which the set was located was jarred by anyone walking above. A new ground clamp remedied the trouble. The moral is: When things go wrong with the set, start hunting for trouble at the largest connec- tions, for without good aerial and ground contacts, it is useless to tinker with the set. —Ralph LeCompte, Herbertsville, N. J. Grounding of Transformer Cases Eliminates Hum

Left, New Tube Checker Showing Plug for A.C. Line; Right, Checker in Operation with Tube Inserted Tube Checker Operates from A.C. Line The new tube checker shown in the illustration operates directly from the reg- ular a.c, 60-cycle lighting circuit and is so designed that the circuit may have any voltage from 90 to 130 volts. It will check all tubes, a.c. or d.c., using filament current of 1.5, 2.5, 3.3, 5 or 7.5 volts, in- cluding rectifier tubes. The checker is equipped with sockets for UX, UY and UV-tubes; a line-

One of the most troublesome sources of hum is that due to ex- ternal fields around the power trans- formers used in the power pack. This trouble eliminated by con- Chicago, III. No. 117, Simple FOR THE RADIO BUILDER The simplified blueprints listed below include the best of Popular Mechanics tested circuits. When ordering, simply quote the numbers of the blueprints desired and inclose the proper amount in an envelope addressed to Popular Mechanics Magazine, Radio Dept., Back magazines containing full descriptions of the circuits can also be obtained. Inclose an additional 25 cents for each magazine desired, giving date of publication. may be No. 111, Homemade Tube Tester July 1926. 25c No. 115, 15 to 550-Meter Three- : Tube Receiver necting the metal No. 116, Three-Tube Loop Set. Dec. 1926 25c Electrolytic B- voltage adjusting dial; a five-point filament-voltage dial, push buttons and suitable meters. An instruction card is supplied. 200 E. Ontario St., @ Dry cells may be 25¢ tested with an am- meter having ascale Nov. 1926 cases or cores of the Eliminator Feb. 1927. 25c of 25 or 30 amp.; transfor s No. 123, Economy-Nine Superhet- h instrument yrmers to erodyne Nov. 1927. .50c ae either the ground No. 126, Homemzde B-Battery should be held on lead or the B-nega- tive lead of the re- and Charger No. 130, One-Tube Short-Wave Adapter No. 131, Five-Tube All-Electric Jan. 1928. .25¢ the cell just long Mar. 1928. 25c enough to get a ceiver or power Receiver Apr. 1928. 25¢ reading, and cells pack, so as to bring No. 134, Edison Type B-Battery July 1928 .25c showing less than | ; > 1 A No. 135, Screen-Grid Browning- 10 < | ld t the cases and cores Drake Receiver Sept. 1928. 25c ) amp. should be of all transformers No. 138, Screen-Grid Perfect-Tone discarded. A volt- ; Six Receiver Nov.1928. .25c to the low-potential No. 139, Simple Television Re- meter may also be side of the circuit. This also applies to the a.f. transform- ers, if they are not already grounded to a metal subpanel. ceiver No. 142, Two-Tube

ceiver No. 140, Power Amplifier and B- Supply for Television Jan. 1929. 25c No. 141, Hammarlund-Roberts Hi- Q 29 Junior A.C. Re- Screen-Grid Short-Wave Adapter Mar. 1929 25c Dec. 1928. 25c used; a good dry cell should register 1.4 volts and should Feb. 1929. 25c be discarded when the reading falls to 1.1 volts.

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662 POPULAR Complete Kit for Service Men Ae complete testing and repair kit for the busy radio-service man is shown in New Radio Kit Showing the Complete Equipment Required for Testing and Service the illustration, nothing having beer over- looked that is necessary to meet any emergency. Safety devices protect all meters and circuits so that an error in testing will not damage the instrument or the set itself. It can be lifted out of the carrying case for store or laboratory use. Various fixed condensers, from .001 to Z mfd., a 30-ohm rheostat, a 500,000- ohm variable resistance, and an audio transformer are available for instant use and in various combinations. The kit is equipped with standard meters and makes accurate tests of voltage and current of all radio receivers, including those using the newest tubes. Removing Hum from Dynamic Speakers First determine whether or not the hum is caused by the dynamic speaker, as it may be in the set instead. When located in the speaker, there are several simple methods of reducing and often eliminat- ing the hum. One simple method of test- ing the speaker for hum is to remove the output tube of the set, when, if the hum continues, it is evidently in the speaker. Dynamic speakers are of three varieties, one in which the field is energized by di- rect current from a storage battery; an- other in which the field is energized by means of rectified 110-volt current, or 110- MECHANICS volt direct current, and a third in which the field is energized by means of current from the B-eliminator. The battery-oper- ated type cannot cause a hum. The sec- ond type is the one in widest use and most likely to cause the trouble. The third type seldom gives trouble and when it does, the remedy is usually beyond the average set owner. As regards the second type, simply shunting high-capacity con- densers across the field coils will fre- quently eliminate the hum. These con- densers should be of the heavy-duty type from 4 to 8 mfd., the capacity varying with the type of speaker used. In some cases, A-type condensers of large capacity are required across both field coils. In ex- treme cases, a high current-carrving choke of the type used in A-eliminators, placed in series with the rectifier and field coils in addition to the A-type condensers, will be required. World Time for DX-Radio The radio clock shown in the illustra- tion is now available for DX-listeners who wish to follow the programs not only from their local stations, but of all the stations their receiving set will reach. As seen from the illustration, there is'a secondary dial listing the principal time-zone locali- ties, namely, Eastern, Central, Mountain, Pacific, Alas- ka, Hawaii, Berlin, Loa- don, Canary Islands, Azores, Rio de Janeiro and Atlantic, thus complet- ing the time circle. The secondary dial may be turned so as to be set for use anywhere. With this arrangement one can determine local time in any part of the world. @When testing B-eliminators for maxi- mum output with a low-reading milliam- meter, the meter should be protected against burn-out by a fixed resistance of 1,000 ohms or more placed in series with the meter.

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xi- ed of ith “Outboard Motor” Pleases Youngsters By HI SIBLEY OWING a boat has always seemed a clumsy and laborious means of get- ting over the water. Maneuvering in close quarters and on small ponds is awkward with oars. It’s tough on unaccustomed backs in a pull against the wind, and your boat loses momentum between each stroke. Turning a crank is much easier, as with this manual outboard motor. Perhaps one cannot go quite as fast with this device as with oars, but the push ahead is con- tinuous, and a youngster with imagina- tion will get a real thrill from seeing the water churning up behind; besides, he CSS 4s FRONT END OF PROPELLER SHAFT FILED FLAT ON 3 SIDES, THESE FLATS THEN NOTCHED FOR CHUCK 663

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664 can reverse it instantly as in a motorboat. If you own a hand drill, the job is half done. The drill constitutes your motor, and this outboard is so designed that the drill can quickly be taken out and used for its original purpose at any time. The only alteration—and even this is not ab- solutely necessary—is extending the crank handle to give greater leverage. In the one illustrated we simply built up an ex- tension from three sections of perforated bar borrowed from a toy-construction set. A flat iron bar will serve even better in case you can drill the holes for the bolts and handle. The framework should be made from a piece of wood, 39 in. long, 1 in. thick and 3 or 3% in. wide. Select some tough wood not likely to break or split. Yellow pine will do. Saw out as shown in the diagram, and bore the two holes for the propeller-shaft bearings. These bearings, which are sec- tions of brass tube, should be driven in to a snug fit. After being in the water a short time, the wood will swell and hold them securely in place. They do not need to be as long as the holes in the wood. For the propeller shaft, we used a brass CRANK EXTENSION TO GIVE GREATER LEVERAGE -— ROUND CORNERS AND FINISH WITH SANDPAPER POPULAR MECHANICS curtain rod, % in. in diameter, since it hap- pened to be the only thing on hand at the time. However, a cold-rolled steel rod, %46 or % in. in diameter, is recommended, depending upon the size of your drill chuck. The cheapest hand drill, by the way, will suffice for a light-duty motor, its only disadvantages being the noisy gears and unreliability of the chuck, as well as its inability to stand a heavy load. A big sturdy drill will be much better if you care to make the investment. Cut the propeller shaft to 25% in., then flatten the forward end on three sides with a fle for a length of about 1 in. In the center of each flat place, file a groove, about %6 in. deep, running lengthwise. These grooves are to give the three chuck jaws a better grip. The propeller is much more easily made than might be expected. Use a piece of. close-grained wood, 2 by 2 in. in section by 7 in. long. Saw out as.indicated by the dotted lines and bore the hole for the pro- peller shaft. Have this a snug fit, but not too tight, or, in forcing the shaft in, you may split the wood. With a gouge or curved chisel, make one side of each fin concave and the other, STERN NOTCHED PERMITS PROPELLER TO SIT LOWER IN THE WATER WASHER--. BRASS TUBING —-— ASSSSSSS] L. x ad fn } b ion EL WK SHAFT BEARING ) PROPELLER KZ FINS CARVED CONCAVE ON BACK SIDE

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POPULAR MECHANICS 665 or forward side, convex. When finished, the fins or blades should be about % in. thick. Whittle the edges all around to about % in. thickness, then round them with sandpaper. With a sharp jackknife, round the hub so there will be no sharp corners or edges, and thus make it smooth and streamlined. Insert the pro- peller shaft so that the end is flush with the backside of hub. Now carefully drill about a %2-in. hole through hub and shaft and insert a nail or steel pin. Take pains with your painting. If convenient, apply a coat of filler to the propeller and sandpaper smoothly when drv. Two coats of bright red give a lively touch, and they should be followed with two coats of spar varnish. Let each coat dry and sandpaper well after all but the final coat. Now you are ready to fit the hand drill to the frame. It will be simple if you have the type of drill used by the writer. In this a stud opposite the center of the main gear is set in a hole in the wood frame, and the handle is clamped to a grooved section by means of a brass strap. If you have selected a nicely grained wood for the frame, leave it in the natural finish, covering with two or more coats of spar varnish. Cut the rudder, as shown, from a piece of galvanized sheet, as heavy gauge as your snips will handle. Paint the rudder well with bright red, same as the propeller, or a bright green. Give it two coats of spar varnish also, and, when dry, attach to the frame with screws. The final assembly consists simply in inserting the propeller shaft in the bear- ings and tightening the chuck jaws over it. If your propeller blades are tilted in the right direction, as shown, the rota- tion tends to keep the chuck tight, so that after a few revolutions you can reverse under load without fear of loosening the chuck jaws. We found that by notching the stern board of the boy’s little boat, the propeller would sit lower in the water and at the Same time be in a more convenient posi- tion for the operator. This, however, will not be practicable if the boat at your disposal is a rented or borrowed one. You will find the making of this little outboard an absorbing pastime during the spring evenings, and you will then be ready for a cruise as soon as navigation opens. It can be conveniently carried anywhere, and the efficiency of this sturdy little power plant is limited only by the muscles of your arm. Cover for Auto-Tire Padlock Mud, which gets inside of the padlock used by many car owners on their spare tire, causes considerable difficulty in open- ing the lock when the tire is needed. To prevent this, a cover should be provided for the lock. It can be made from a piece of thin leather, cut and folded and then sewed up the sides as shown. A coil spring is slipped over the open end, which is then turned back over the spring and the edge sewed down, imbedding the spring in a hem. The bag is made to fit snugly over the padlock and, when fin- ished, it is turned inside out so that all seams will be hidden. The spring holds the bag on the lock securely and prevents mud and water from getting into it—F. J. Wilhelm, Cincinnati, Ohio.

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666 POPULAR MECHANICS iF i= ae ee ‘Y ~f : - Nk OD / Cardboard Device Used by Photographer for Finding Best Viewpoint Finder for Photographs I have found the illustrated device use- ful in selecting a viewpoint for any par- ticular landscape or object to be photo- graphed. A card is cut to the same size as the plate or film used in the camera, and a rectangular hole, about two-thirds the size of the card, is cut out with a sharp knife or razor blade. At the inside edge of the opening thus formed a small cord is attached as indicated, and a number of knots are tied at intervals on this cord, the distance from the edge of the hole to the knots being equal to two-thirds of the focal lengths of the various lenses used on the camera. The landscape or object to be photographed is viewed through the opening of the card and the distance of the eye from the frame is varied by hold- ing different knots against the upper part of your cheek, just under the eye, until the frame includes the desired picture. A lens of corresponding focal length is ad- justed to the camera. On my camera, I use lenses of 4% to 16%4-in. focus. The outside dimensions of the card enable one to carry it with the plate holders—W. H. Wilcox, Tacoma, Wash. Dry-Cleaning Mixture An emulsion of gasoline and water is much used by dry cleaners for removing grease, tar and paint spots from clothing. It is in the form of a thick, white sirup, which evaporates entirely and is not in- jurious to any fabric or color. This emul- sion can be prepared as follows: Dissolve, in 1 qt. of boiling water, % oz. of pure castile soap and % oz. of gum arabic. Al- low this to cool, and then add 1 oz. glyc- erin, 1 oz. strong ammonia water, 1% oz. chloroform, and 2 oz. sulphuric ether. Shake well, and pour enough of the mix- ture into a quart bottle to fill it for % in. On top of this pour gasoline to raise the level %4 in., and shake until creamy. Re- peat the addition of gasoline, shaking each time, until the bottle is full. The cleaning mixture will then be ready for use, and may be applied with a rag or with a small brush. If, on adding the first lot of gaso- line and shaking, the mixture does not be- come emulsified, too much gasoline has been added. In this case, allow the mix- ture to stand for a few minutes and pour off the excess gasoline, which comes to the top. Shake well, and add a smaller quantity of gasoline. When the bottle is half full, larger quantities of gasoline may be added at atime. It is interesting to note that the more gasoline is added, the thicker the emulsion becomes, and if the addition of gasoline and the shaking is prolonged, a semisolid jelly is formed, which will not run from the bottle. Keep the emulsion away from open flames. Conserving Motor Heat in Zero Weather Fittinga shutter in front of the radiator of your car is auto highly recom- mended to keep the heat of the motor at an efficient F operating > £+---- temperature, and the pro- vision of cardboard or asbestos strips in- side the lower part of the hood to close the ventilating slots, is also advisable. Be- sides this you will find that asbestos “fluff,” which is used for steam-pipe packing and TIMING- GEAR CASE , is obtainable at almost any mill-supply house, provides considerable insulation when stuffed between the dust and oil pans of your car, as shown in the drawing. —R. P. Cole, Paterson, N. J.

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yn vil POPULAR MECHANICS 667 Toy Speed Wagon ‘ Provided with a stout rubber band, this speed wagon will travel at a fast clip for more than 100 ft. One model has covered 250 ft. on a single winding. To make it, get four can covers for the wheels; cut 2 strips from the side of one can, bend the ends over at right angles and punch _ holes through them to serve as bear- ings for 2 lengths of wire which serve as axles. Push the wires through holes punched in the ex- act center of the wheels, and then Toy Wagon of Simple Construction Driven at High Speed by a Stout Rubber Band solder the wheels to the axles. Cut a narrow board, about 2 ft. long, and fasten one set of wheels and axle to each end. Drive a nail in the underside of the board just behind the front axle, in the center, as shown in the detail. Geta stout rubber band and tie one end to this nail. Then wrap the other end of the band around the rear axle and turn the wheels to wind the band on it. If you stretch the rubber while winding, you can wind it much tighter. Set the wagon down on the floor and let it go. In one case the band was wound so tightly that the wheels would spin, unless a brick was placed on the wagon. To make the wagon run in a curved path, turn the front axle slightly, Flower Stands Made from Barrel Hoops Wooden barrel hoops can be used for making artistic flower "stands like those shown in the drawing. They can be made Flower Stands of Various Kinds Can Be Made from Wooden Barrel Hoops A: —— v which can readily be done if it is attached by means of a screw driven through the center of the tin strip. You can also add other details, such as a hood, seat, steer- ing wheel, radiator, etc. File all edges down so that they are as smooth as pos- sible, and when you wind the rubber, take care not to let the wheel spin in your hand, for even a smoothed tin edge may make a bad cut.—Dale R. Van Horn, Lin- coln, Nebr. of various shapes and sizes and, when finished, are given an application of paint to add to their appearance. Care of Automobile Doors When you are oiling your auto, do not neglect the door hinges and latches. Many rattles and squeaks can be traced to door hinges and old anti-rattling devices. Slam- ming doors too violently is apt to break the door-window glass, or it may spring the door, and it is then almost impossible to prevent it from rattling. For the same reason, it is a good plan to examine the door checks occasionally. @To level rough ground quickly and ef- fectively, drag an iron rail over it, tying each end to a suitable length of chain or rope and attaching it to a tractor.

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Be Sure That All Sanding Dust Is Well Rubbed Off Before Starting to Varnish [% THIS issue we are going to take up the extra-fine stain finishing of furni- ture by removing the old finish and build- ing up the desired new finish by coloring the wood with stain, and then applying finishing coats of varnish. This is the method skilled finishers use in refinishing operations of the highest class. We will take for an example an end ta- ble in the red-mahogany finish which used to be fashionable but now is no longer seen in the best-furnished homes, and change it to the modish brown mahogany of today. In this connection, it is to be assumed that there are only two reasons why the householder will ordinarily want to remove the old finish and build up a new one from the wood. One is to change the effect, and the other that the old finish is in such bad condition it cannot be re- 668 ‘Ow 7oRefinish Finishing with Stain and Varnish stored to its original state by patching, polishing or the application of an addi- tional finishing coat. It should, of course, also be remembered that the stain finish- ing of fine furniture calls for the exercise of considerable good judgment, and that those without previous experience in the use of finishing materials should first do some smaller, medium-grade pieces to be sure the results obtained are satisfactory before attempting expensive furniture. Ordinarily a previously stained piece can be refinished in a darker stain effect with satisfactory results, but wood pre- viously stained dark can seldom be satis- factorily refinished in lighter effects. Red- mahogany stain in particular is very pow- erful, and it is practically impossible to use any except the very dark stains, such as walnut or brown mahogany, for refin- ishing surfaces previously finished in red mahogany, as the stain deep down in the wood, which cannot be entirely removed, will “bleed” through and “muddy up” the new finish, so it will not present a very pleasing appearance. In starting the refinishing of the table, the first step naturally will be the removal of the old finish. This is not a difficult operation, although it is rather a disagree- able one to those who are not accustomed to it. The work is best done with the pre- pared paint and varnish removers made especially for the purpose. Alcohol is sometimes used, as is also benzol and other solvents, but they do not act so quickly and efficiently as the prepared re- movers. Lye is also employed, but its use is not advisable, as it is likely to burn the wood and injure it for refinishing. Some people also sandpaper down the old finish instead of using paint and var- nish remover, but this is not such a satis- factory method, for it is impossible to sand out checks entirely as long as any of the old finish remains, and to sand it .

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\e he r- to ny down clear to the wood is a hard job, and a much longer one than the re- moval of coatings with a solvent remover. The method of using paint and varnish re- mover is as follows: 3rush a liberal coating onto the surface, being sure to shake the con- tainer thoroughly to agi- tate the contents, imme- diately before using, and also being careful not to get any of the remover onto any near-by painted or varnished surfaces. Allow the application of remover to re- oughly washed with a cloth saturated in main on the surface until the old coating gasoline (preferably high-test) or benzine, is softened, which usually takes about five or, better still, scrubbed out with a vege- minutes, then scrape off the softened coat- table brush dipped in the gasoline or ben- ing with a putty knife. Carvings, moldings zine, to remove any remaining deposits and other hard-to-get-at places may be of the paint remover. This is extremely reached with a small vegetable brush or a piece of steel wool (which should be fine) dipped in the remover. In some cases where the old finish is exception- ally heavy or ad- heres tenaciously to the surface, a second or third ap- plication of the re- mover may be nec- essary, but not as a general rule. After the removal of the old finish has been important, as paint removers are ordinarily made with a wax content, which, if left on the surface, will inter- fere with the dry- ing of the new fin- ishing coats or cause other trouble. As soon as the surface is thor- oughly dry, you are ready to build up the new finish. The first step, as in all finishing, is to sand- paper the surface. completed, the sur- Applying Rubbi ' ae Berens When Pellcht While it may seem face should be thor- re eee boa en rome to be quite smooth, 669

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670 POPULAR MECHANICS it is always wise to sand lightly before any finishing is started, to take off any nibs or dirt and insure the last de- gree of smooth- ness. For fine fin- ishing, only very fine sandpaper should be used (not coarser than 0000). Care should be taken to sand evenly all over the surface, so that the refinish- ing coats of stain will produce a uniformly even effect. When through, loose parti- cles of sand and sawdust should, of course, be dusted off carefully. The next operation is the application of the stain. .For the home finisher, a stain of the penetrating type is best. Oil stains, although suited for use by the amateur, are only adapted to new wood, as when a wood has once been filled, stained and varnished, its porous qualities are partly destroyed, so that oil stains will not pene- trate sufficiently. There are other types of stains which require more skill in ap- plication and therefore should be used only by the skilled craftsman. Before starting to apply the stain, a try-out should be made on some obscure part of the table, as it should be remembered that a stain gives somewhat different color ef- fects when used on different kinds of woods, and also varies somewhat accord- ing to the previous finish and the quan- tity of stain that may be left in the wood when the old finish is removed. If the effect is found to be too dark, the stain can be lightened somewhat by adding a little turpentine. The application of the stain itself is a comparatively simple operation. One coat only should be applied, as evenly and uni- formly as possible, without covering any part of the surface twice. If any places are skipped, touch them up with a small brush. After staining, the surface ordi- narily should not be sandpapered, as it may cut through the color in places. The next step is the application of filler, if the piece is of one of the open- grain woods, such as oak, walnut, ma- hogany, chestnut, etc. This should be done after the stain is thoroughly Top, Sopping On the Remover; Center, Staining the Piece; Below, Rubbing Off Filler across Grain

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he POPULAR dry, usually the following day. While the wood, if of the open-grain type, was un- doubtedly filled when the piece was orig- inally finished, the application of the paint and varnish remover usually removes some of the filler as well as the finish. The function of the filler is to fill the pores of the wood, so that the following varnish coats do not sink in, and to level the surface for the finishing coats. Ordi-- narily paste filler is used for open-grain woods, this material coming in thick paste form, to be reduced with benzine or tur- pentine to about the consistency of thick cream immediately before use, and being made in different shades, such as natural, oak, walnut, mahogany, etc. The color of the filler should correspond with the effect desired. Filler is applied with a brush, and, with- in a few minutes after application—as soon as it commences to set, which is in- dicated by its turning flat—is wiped off across the grain with a cloth, rubbing vigorously until every bit of surplus is re- moved, the last stroke or two being with the grain. The filler should not be ap- plied on too much surface at a time, for if it sets hard before you get it wiped off, it will be hard to remove, and this must be done or the finish will be disfigured with grayish streaks. In case it should get too hard, it will have to be washed off with turpentine or benzine, or perhaps taken off with sandpaper dipped in tur- pentine or gasoline. When the filler has dried for 24 hours, the surface should be sandpapered very lightly, and dusted clean. The next operation is the application of a thin coat of shellac, to seal in the stain, which would otherwise bleed through the finishing coats of varnish. Shellac, being made with alcohol and containing no lin- seed oil, is impervious to the attack of the strong dyes used in penetrating stains, which attack linseed oil. For use over brown mahogany, walnut and the darker shades, orange shellac is recommended, as its yellowish cast helps to bring out the true beauty of the effect. (For light-stain effects, white shellac should be used.) After the shellac is dry—it dries very quickly and becomes thoroughly hardened in about two hours—it should be sand- ‘papered lightly to a smooth surface, but not too much, so as to sand it off entirely. MECHANICS 671 Rubbing Down between Coats with Fine Sandpaper on Felt Pad After dusting clean, you are ready for the finishing coats of varnish. For the highest-class work, three coats of high-grade interior-finishing varnish (gloss) should be applied, allowing three, or preferably four, days for drying be- tween coats, and rybbing the first and second coats with No. 0000 sandpaper (or, for the best possible job, with pumicestone and water) and the final coat with pumice- stone and oil, to the desired effect. Full directions for pumice rubbing were given in the December, 1928, issue of this maga- zine, and detailed information regarding the technique of applying varnish in the March, 1929, issue. A high polish of piano finish is some- times given fine furniture by rubbing with rottenstone (which can be obtained at paint or drug stores) and oil, after the pumice rubbing is completed. Simply rinse off the pumice with clear water, and begin rubbing with rottenstone and oil, using a very soft cloth or soft rubbing felt, and proceeding over the entire sur- face until a beautiful high polish is pro- duced. Then rinse off with clear water and dry with a chamois or soft cloth. In case any places are found to be dull after the clean-up, they should. be rubbed to

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672 POPULAR MECHANICS ished furniture, and you will have a piece that compares with the mahogany or wal- nut-finish furniture shown in the stores. When using the decalcomania transfers, it is, of course, necessary to choose a pattern that will imitate a wood inlay, that is, one that resembles the background as closely as possible. Bright, highly col- ored transfers, while quite suitable for painted, lacquered or enameled furniture, are entirely out of place on stained and varnished pieces. There are many trans fers, however, that resemble inlay and marquetry work, in comparatively dull colors, and any good paint house can offer a. selection that will enable the ama- teur finisher to suit his walnut or mahogany pieces. Take care to place the transfer accurately. If it is off center or not straight, it will mar the effect of the most careful finishing. ( match the rest of the sur- | face; then the entire surface ] is given a few strokes to 5 produce a uniformly even t effect, and cleaned off thor- oughly when through. " From the foregoing, it h will be seen that the refin- b ishing of an old piece of fur- c niture in a fine stain finish is q really quite a simple opera- p tion for anyone who likes pe handcraft. There are just t | these five operations: tak- ec ing off the old finish; ap- c plying the stain; applying $1 the filler; applying the var- wi nish coats, and rubbing pie (and polishing if desired). pa Then, if desired, a last fin- us ishing touch can be added ie by the application of trans- D fer decoration in one of the ag medallion patterns or wood- bot inlay effects designed espe- Scraping Off Softened Varnish with Putty Knife after Sopping with roll cially for use on stain-fin- Remover

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with

Removing Auto Wheel without a Puller If you have to remove a rear wheel of an auto and there is no wheel puller at hand, jack up the opposite wheel, setting the jack at a slight outward angle so that the weight of the car pulls on the axle of the wheel to be removed. Take off the hub cap and the hub nut, reverse the nut and screw it on the shaft until it comes flush with the axle, and tap the axle with a hammer until the wheel comes loose. The nut is reversed so that no damage will be done to the castellations. I have found this method successful with the tightest wheels —K. E. Corliss, Lang- ley, Wash. Memorandum Pad and Holder One of the most useful types of memo- randum pads is one that incorporates a roll of paper, which can be torn off at any length desired. It is easy to make one from a piece of tin, brass or galva- nized sheet iron, the dimensions and shape of which are given in the upper detail. The dotted lines show where the metal is bent. Two 3-in. metal straps are sol- dered onto the sides at the top and bottom of the pad holder as shown, a slight space being left between them and the holder. In use, a roll of paper is laid in the box section and the end pulled between the top and the straps. If de- sired, the holder may be given a coat of lac- quer to im- prove its ap- pearance. All the sharp edges, are, of co ut2

You Can Prevent Loss of Your Motor by Tying It to the Boat with a Six-Foot Rope Preventing Loss of Outboard Motor Some time ago, when attaching an out- board motor to a boat in rather rough water, I overbalanced with the result that the motor and myself had an untimely bath. It was quite difficult to recover the motor in 15 ft. of water, and I decided to prevent a similar accident by fastening a 6-ft. length of rope to the motor before lifting it out of the boat. A harness snap, fastened to the shank of the wingbolt of the motor clamp, provided a quick means of attaching and detaching the rope. Of course, the other end of the rope was se- curely tied to the boat. Another simple method of preventing the loss of the mo- tor, due to vibrations loosening the screws clamping the motor to the boat, was found successful on a Wisconsin lake. A piece of %e-in. sheet copper was bent to fit over the transom of the boat, and screwed to the wood. The motor fits over the copper in the usual way, but the clamp screws get a good grip on the soft metal, and do not seem to become loose. A combination of both methods described should prevent any possibility of loss or trouble.—Dick Cole, Los Angeles, Calif. "as engl la ma he ll acelin: none ate nw — en yy

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F COURSE you have a camera. Every summer you go on a grand spree of picture taking—snaps of the fish you catch, artistic and unartistic photo- graphs of your friends and relations, a beautiful bit of scenery; in fact, every- thing from a mud turtle to a midsummer sunset is fit material for your black box. And then, at the end of an arduous sum- mer, you take the vast collection, look them over for the last time, and then plank the whole bunch in a shoe box with the rather vague intention that some day you will take them out again and put them in a pretty album where they can yellow away to a decent old age with in making this checkerboard, the first step is to procure a sheet of heavy white cardboard or bristol board, 16 in. square. Now, measure in 2 in. from each edge of this square and rule another square to form a border, 12 in. along each side. Di- vide this inner square, with ruler and T- square, into 64 small squares, as shown in Fig 2, each of these smaller squares meas- uring exactly 1/4 in. to a side. That finished, take a small piece of card- board, and in the center of it cut out an opening 1% in. square. This is the “finder.” By placing it in various posi- tions over a snapshot, you are enabled to select the most picturesque or inter- esting bit of the picture, and after finding it, you should outline it by running a pencil around the inner edge of the card- board square, as shown in Fig. 3. Your snaps, of course, should be of the 2% by 3%-in. size, at least, so that there will be plenty of detail in the pictures, although 14% by 2%-in. “vest-pocket” snaps will do in a pinch. Outline 32 of your best snaps in this manner, and then cut out each of the squares with a paper cutter or a pair of sharp scissors, as shown in Fig. 4. After cutting the snapshots, take a pen, and, filling it with black ink, run a some pretense at luxuriousness. That’s the average amateur photographer. Like a lot of others, you take a picture and that ends it, and vou never give a thought to the wonderful deco- rative effects that can be obtained from the camera and your old snapshots, But here’s what you can do: Go over your accumulation of snapshots. Among them you will, of course, find two or three dozen or more pictures which you espe- cially like, and from these a photographic checker or chessboard, as shown in Fig. 1, can be made. 674 black border around the outside of each square, as shown in Fig. 5. The next step is to mount the photo- Ci tu ot pi in tic bo ab be tos me abl mit fit Shap be pi No

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each 10to- cardboard. In doing this, 16 of the pic- tures should face one way and 16 the other, so that each ‘player will have 16 pictures facing in his direction, as shown in Fig. 6. The final step in the construc- tion of the checkerboard proper is the border. If you have the necessary artistic ability, a simple pen-and-ink border can be drawn around the framework of pho- tographic squares; if not, the simplest method is to paste a narrow strip of suit- able wallpaper border around the edge, mitering the corners so that the edges will fit nicely together. A small, diamond- graphic squares on the ruled sheet of the same size as the cardboard and paste or glue the checkerboard to one side of this. Cut a piece of heavy glass to exactly the same size as the board and place this over the top of the layout of photographic squares. Bind the edges of the three as- sembled pieces with a 2-in. strip of col- ored felt, cutting the felt at an angle every 16 in., as shown in Fig. 8, so that it will make a neat joint at the corners, as shown in Figs. 8 and 9. Almost finished! It remains yet to glue a square of felt to the bottom of the board so that it will not mar the surface of the playing table, and then—your move! A neat top for a card table, as shown in Fig. 10, can be made in a similar manner, and here the scope for artistic grouping of large and small pictures is consid- erably enlarged. The various steps in the construction of the Shaped or circular photograph can then be pasted in each corner, as in Fig. 7. Now cut, from %-in. lumber, a piece of photographic card table are much the same as those used in mak- ing the checkerboard. If desired, the pho- tographs can be pasted directly to the sur- face of the table (this should be light in 675 '

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676 POPULAR MECHANICS mS puzzle is finally assembled, as shown in Fig. 12. This particular puzzle was made from an enlarged snapshot of the Harding Memorial, at Marion, Ohio, but any other type of picture—landscape, personal, ma- rine, etc.—can be used to equal and often to greater advantage. A small boy would surely appreciate puzzling out his own pic- ture over assembling a photograph of a locomotive, of a beauty spot in the Grand color in order to contrast) instead of to a sheet of cardboard, although the latter is the better method. The binding for the card table can either be felt, as for the checkerboard, or narrow brass strips (such as are used for the edges of oilcloth- covered tables), bent at right angles, can be used to hold the glass in place. Something entirely different is the pho- tographic cut-out puzzle. Take one of your best snaps and have it enlarged to about 7 by 10 in. Mount this enlarged picture on one side of a thin slab of wood, preferably three-ply veneer, so that it will stay flat, using a good grade of glue to hold the photograph firmly in place. After the glue has set and dried, take a coping saw or a fretsaw and cut’ the mounted photograph into small sections, as shown in Fig. 11. This can be done haphazard or from a penciled pattern, as: your fancy dictates. In cutting the photograph, downward pressure should be used only on the out- ward stroke of the saw, as a heavy, down- ward pressure on the backstroke tends to give a slightly ragged edge to the picture which will mar its appearance when the canyon or striking scenic view elsewhere. Still another phase of decorative pho- tography from your old snapshots is the making of transparencies. A _transpar- ency is a positive film; that is, the snap- shot film appears like a snapshot photo- graph made transparent. The varied uses for these transparencies are legion, but, perhaps, in the making of lampshade deco- rations they are most popular. The how of making them goes like this: Take about six of your favorite negatives and retire to a room which is entirely darkened with the exception of a dim light furnished by a red electric bulb or allo initi

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the yar- ap- yto- 1ses but, eco- tives irely dim b or POPULAR MECHANICS 677 by an ordinary white bulb masked with red paper. The red paper that films are wrapped with in the original package makes a good safe light. In this dark room, take a roll of film of the size that fits your camera and unwind it. After procuring the length of film, cut it with scissors into six small pieces of a size to fit your negatives, as shown in Fig. 13. Now, take one of the pieces of the new film and place it on a piece of black vel- vet, felt, or dead- black paper. Put the negative film over this, and, on top of the two, a clean piece of glass. That done, take an ordinary match, Light it. Hold it about 2% ft. away from the glass, as shown in Fig®14, and match. - The match should be waved slightly to and fro as the exposure is being made, and this exposure should be of no longer duration than the match- head flame men- tioned, as further exposure will “burn up” the film. What happens is quite obvious. The light penetrates through the light allow it to burn for the duration of the and dark portions of the film negative and initial flame caused by the head of the makes a positive impression on the lower

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NM oO — Zz a en) QO ica — — POPULAR

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POPULAR MECHANICS film. This positive imprint, when made in this fashion, is technically known as a transparency. After making the usual six exposures, place the prospective trans- parencies into a black box and take them to your photographer. He will develop them in the usual manner, producing posi- tive films like the one shown in Fig. 15. The practical value of these films lies in the fact that their transparency makes them quite suitable for mounting on lamp- shades and side-bracket lights. The first step in mounting them is to cut out the necessary area from a plain undecorated lampshade, or perhaps you can find a parchment lampshade with a design which readily permits the cutting out of some portion to allow the inser- tion of the picture. After cutting out the framework, trim the transparency to the required size and paste it in place on the inner side of the shade. A piece of trans- parent paper should be used as backing, in order to give the picture more bril- liancy. Some idea of the effect can be gained by the illustrations in Figs. 16 and 17, although the full delicacy of the trans- parency is something far-too illusive to be reproduced on the printed page. effect can be varied by using thin colored paper to back up the transparencies, or thin colored celluloid, the color being chosen to suit the subject. Novel Sign for Roadside Pop Stand The proprietor of a small roadside pop stand, just outside of a small Nebraska town, has a novel advertisement which is especially attractive at night. It consists of a 5- gal. keg bored to admit the ends of empty pop bot- tles as shown. A 150-watt electric lamp is provided inside of the keg, and the open end of the keg is closed. At night, when the light is turned on, the bottles let the light through, making the odd sign visible from the road. The . 679 Back-Up Light Which Works Automatically When Car Is Reversed Installing a Backing Light on the Car Any motorist can provide a back-up light that works. automatically when the gear-shift lever is thrown into reverse. Get an ordinary stop-light switch and mount it on a bracket, which is in turn attached to the transmission cover as shown. The switch is so located that the gear-shift lever bears against it and closes the circuit. A 4-in. spotlight is mounted at the rear in a convenient position. The small diagram shows the method of con- necting the lamp and switch in the circuit. —G. A. Luers, Washington, D, C. Soldering Iron Removes Putty Putty can readily be removed from old window sash in which the pane has to be renewed, by means of a red-hot poker or hot soldering iron. An electric iron with ‘a wedge-shaped point is the best for the purpose as it remains hot. After getting the point down to the wood it can be pushed along, peeling the old putty clean without damaging the wood on, the sash. —Mason Barnard, Worcester, Mass. @ Half of an old flour barrel, cut length- wise and laid on the ground with stakes driven in at the open end, makes an ex- cellent coop for a brood of young chicks.

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680 POPULAR MECHANICS Small Mirror At- tached to Swivel Joint on Handle Helps Inspection of Hidden Places Handy Mirror for Inspecting Corners Machinists and shop workers often find it necessary to inspect a corner which is out of the line of vision and can only be seen by the use of a mirror. In such cases a small mirror taken from a cosmetic com- pact and attached to a handle so that it can be adjusted, will be found “just the thing.” Remove the mirror from. the lid and solder a ball-and-socket joint to the _ outside edge of the lid. Joints of this kind can be found on gas-throttle rods and dis- tributor rods of autos, and can be picked up for a few cents at any auto junk yard. Tighten the socket on the ball until it moves rather stiffly. Screw a piece of the rod into the joint and attach a wooden handle, about 7 in. long, so that the com- plete handle will be 10 in. long. When entirely finished, replace the mirror. Such a tool will be found useful for inspecting corners inside of tanks and boilers with a flashlight for illumination; for checking timing gears without removing the radi- ator, and for inspecting and timing a mag- neto without removing it—C. Neiper Bruce, New Castle, Pa. Quickly Made Soldering Acid Preparation of soldering acid by drop- ping pieces of zinc into muriatic acid until all bubbling has ceased, which indicates that the acid has been properly cut, takes a long time and is more or less messy. An equally effective flux can be made from a few cents’ worth of zinc chloride mixed in water to make a saturated solution. The flux thus made is ready for use as soon as it is mixed. As the salt is extremely deliquescent it should be kept in an air- tight bottle —J. S. Hagans, Chicago, Ill. Warning Signal for Low Beam in Cellar There are quite a number of cellars in which the center beam is lower than the joists, and no matter how careful you are, you occasionally will bump your head against it painfully. After this had hap- pened to me a number of times, I decided to prevent repetitions by providing a warning signal that I would see when approaching the beam. I had noticed that most people walking down into a cellar have their eyes fixed on the floor and therefore I got a paintbrush and some black paint and marked a line on the floor directly under the beam. When I catch sight of the line, I always remember to stoop.—J. A. Dowie, Alexandria, Va. Fishing through the Ice When fishing through a hole in the ice the hole is likely to freeze over during the night unless it is covered. Sometimes a piece of paper or cardboard is laid over the hole and this is covered with straw or hay, but the disadvantage of this method is that, unless it is securely weighted down, the straw may be blown away. A better method, which I have found successful, consists in setting a piece of corrugated cardboard, roughly shaped to form a tube, into the hole and then filling the top of the tube with straw or hay. A little water applied to the edge of the ice and to the outside of the tube will soon freeze and hold it securely in position—Dale R. Van Horn, Lincoln, Nebraska.

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i ee ee Ue ewe. Coat POPULAR How to Grow Dwarf Trees and Shrubs Dwarf trees and shrubs of the Orient are famous the world over. If you enjoy gardening or ex- perimenting with such trees and shrubs, here is a simple method of growing them in your own home. Carefully remove the pulp from a half grapefruit or large orange. Let the peel dry to some extent and then apply a single coat of shellac or varnish on the outside. When dry, fill with the finest and richest leaf mold you can get. Rich fertilized earth will do in a pinch. In the center of the shell, plant a tiny seedling of the tree or shrub you wish to dwarf. Set in a sunny place and water occasionally. As the seed- ling grows, the roots will eventu- ally pierce the sides or bottom of the fruit-skin pot. With a sharp knife, or scissors, trim each pro- jecting root flush and apply varnish or shellac on the wound. Repeat this opera- tion for a few months and then transplant the tree to a pot or jardiniere of suitable size. Pine trees, orange, lemon and quince trees are the easiest to work with, although there are countless varieties suitable for experimentation—M. W. Meier, Lang- ley, Wash. Simple Door Holder Two shade-roller brackets, one attached to the baseboard and the other to the door so that they will engage as shown in the drawing, will be found efficient as a door holder. The concavity of the brackets and their smooth edges, cause them to en- gage easily when the door is pushed open,and sim- ilarly to slip apart readily when it is closed—R. Wailes, Be- thesda, Md. MECHANICS 681 GROMMET—” Wind and Waterproof Sleeping Bag Can Be Made from a Piece of Canvas and Two Blankets Combination Shelter and Sleeping Bag When one does not feel justified in pur- chasing a sleeping bag, a good substitute can be made cheaply and without much work. The materials needed are one piece of duck about 6 by 16% ft., the weight be- ing determined by the user according to his needs for shelter, and 2 doz. brass grommets with %-in. holes. Also get a few yards of good stout tape, thread and needles. Space the grommets about 15 in. apart on the long edges of the can- vas. Then sew 1-ft. lengths of tape to the edges of your camp blankets, spacing them to match the grommets in the can- vas. It is a good idea to have the lengths of tape sewed on by machine. In use, the canvas is laid down flat as shown in the drawing. The blankets are laid on it, and the lengths of tape are tied to the grommets. Fold one blanket over the other and there will then be exactly 2% ft. of canvas projecting at the head end of the bed thus formed. Tie up one edge of the bed all the way, using heavy fish- line, rove through the grommets back and forth from end to end. This will make the edge practically windproof. The other side is similarly tied, halfway up or en- tirely—Dick Stafford, Boulder, Colo.

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682 POPULAR MECHANICS Pocket First-Aid Kit Handy and compact, fea- tures which are appreci- ated by hunt- ers and camp- ers, are the requirements of a pocket first-aid kit. I have found no better con- tainer for such a kit than a small tobacco can of the kind shown in the drawing, which can be obtained al- most anywhere. Give the box two coats of white paint and, if desired, paint a neat red cross on one side. Have the druggist put up the following items in slender 2- drachm tubes: aromatic spirits of am- monia; soda-mint tablets; iodine or mer- curochrome; a saturated solution of per- manganate of potash, which is used for - insect bites and stings; 10 drops of oil of cloves in sulphuric ether, this being used as a toothache remedy; a small roll of adhesive tape, removing the tape from the container and filling the latter with zinc oxide which is used as a burn oint- ment; a roll of 2-in. gauze; a small pack- age of absorbent cotton and a square of surgeons’ lint, which is sold in waxed en- velopes about 6 in. square. To assemble the kit, take about half of the absorbent cotton and place it, tightly rolled, in the bottom of the can. On this stand four of the tubes vertically.. Place a small pair of scissors between the tubes and the side of the can. Add some rubber bands and toothpicks and the surgeons’ lint. A small card or paper, containing straight pins and some small safety pins, besides a needle and thread, is then inserted. A pair of tweezers can also be accom- modated. On top of the tubes lay the tube of soda mints on its side, and above this place the tin containing zine oxide, and about half of the roll of gauze. A small piece of soap and the tape can then be fitted in a corner. Be sure that the corks on the tubes are all tight. This kit is the result of fourteen years’ experience. —Harold J. Boyd, Orlando, Fla. Enlarging Small Negatives Amateur photographers who enlarge small negatives. and find that the grain of the gelatin emulsion is objectionably mag- nified in the process, may counteract this trouble by simply immersing the negative in a liquid which has nearly the same re- fractive index as the negative and the base. Such a solution may be carbon te- trachloride, benzine, turpentine or glyc- erin. In a horizontal enlarger these solu- tions should be used in a tank, made by clamping a strip of soft rubber between * two sheets of glass, or in a vertical en- larger a clear glass tray can be used. A simple method is to sandwich the negative between two glasses after covering both sides with a thin coating of glycerin. If the enlarger radiates much heat, it is best to treat the film with a hardening solu- tion, such as formalin, before immersing. Hinge Makes Good Gate Latch Any large strap hinge can be converted into a good gate latch. With a hacksaw or cold chisel cut off one end as indicated by the dotted lines, and recess the re- maining portion so that it is wide enough to fit over the gate frame. Screw the hinge to the fence post as shown, and nail ona block to keep the latch end hor- izontal, Bend the ends of the latch sec- tion upward a trifle so that it will slip into its locking position more easily after it has been lifted to release the gate. If the gate is required to swing in one direction only, a stop block may be nailed onto the post, and an unslotted hinge can be used in practically the same way with just suf- ficient clearance between it and the stop block to accommodate the gate frame. SJ paths A ty >

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eS w Fr oe POPULAR Using Gasoline Stoves and Lanterns Gasoline treated with lead tetraethyl, so- called “ethyl gas,” cannot be used instead of “straight” gasoline in stoves and lan- terns. Exhaustive tests seem to indicate that ethyl gas relieves the knock in a motor by retarding the explosion, and many users think that it is a gas of ex- ceptionally high-test quality. Gasoline, however, merely holds the lead tetraethyl in solution in the same way as salt is held in water. When the gas is vaporized in the generator of a gasoline stove or lan- tern, a solid residue is left, which quickly plugs up the orifice in the generator tip. Then the stove ceases to burn. Campers who siphon fuel from their auto’ tanks should be aware of this. Bell Anchor for a Small Boat An old differential-housing cover plate, fitted with an eyebolt as shown in the sketch, makes an excellent bell or mush- room type of anchor for a small fishing boat. This anchor does not depend on its gross weight to hold a boat. It digs into the sand, gravel or mud at the bottom and is therefore more effective than a heavier plain-weight anchor. When drawn to the surface, its accumulated contents can be rinsed out before lifting it into the boat—Dick Cole, Los Angeles, Calif. Differential-Housing Cover Plate MECHANICS 683 th L STRAIGHT My Oey A JOGGED STRIP Convenient Transplanting Box Consisting of Jogged Strips of Sheet Metal Making Transplanting Easier A sheet-iron box, with removable par- titions forming a number of compart- ments, will facilitate transplanting. For ordinary plants, make the box 3 in. deep and from 20 to 27 in. square, depending on the size needed. For the partitions, get strips of sheet metal and bend them at 3-in. intervals as shown, first to the right and then to the left. These bends should be true right angles so that the strips can be slipped out when necessary. On each side of the jogged strips straight - strips are provided. Fill the compart- ments thus formed with rich earth and plant the seeds. When the plants have reached the desired size, transplant them. Remove a whole row, which can be con- veniently done because of the jogged strips, and it is then an easy matter to separate the individual plants. @When lighting matches in the wind, spread an envelope by pressing on the edges and use it to shield the flame.

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POPULAR Good Substitute for Water Bag Made from Pail and Towels Substitute for Water Bag Nearly everyone knows the value of a ‘water bag for supplying a cooling drink when ice is not available. If none is at hand, a good substitute can be had by wrapping wet towels around a pail of water suspended in a breeze. The edges of the towels should overlap the rim of the pail and dip in the water. The cloth acts as a wick and draws up sufficient water to keep the towels moistened. The evaporation of the water in the towels cools the contents of the pail. It is well to cover the pail with a piece of card- board, and if no breeze is blowing, to swing the pail on a rope tied to the limb of a tree—Dick Cole, Los Angeles, Calif. Screw-Slotting Hacksaw Blades Every mechanic’s tool kit should con- tain a set of four screw-slotting hacksaw blades. These are similar to the ordi- nary blade, but are wider, and each of a set of four is of different width, the widest being % in. It is obvious that the set will save the metal worker considerable time in cutting slots and grooves. Slots wider than % in. can be made by making MECHANICS the second cut parallel to the first. Little or no dressing up is necessary when the job is finished.—J. S. Hagans, Chicago, Ill. Homemade Gas Vaporizer for the Auto Here is a gas vaporizer that will help to start your car quickly on a cold day. It consists of an army-rifle cartridge shell threaded at the small end to fit a tapped hole in the gas-intake manifold. The cap hole is enlarged so that a screw slipped through two mica washers, one on the in- side and the other on the outside of the cap, will not touch the shell. A hole is drilled through the side of the shell at the small end for another screw, but this one, unlike the first, must make actual contact with the shell. A piece of asbestos paper is cut so that, when rolled to form a cyl- inder, it will fit snugly inside the large part of the shell. Get a length of resist- ance wire, as part of the element from a discarded electric-heating unit, wrap it around a nail to form a small coil and con- nect it to the two screws on the shell, as indicated in the illustration. Screw the shell into the hole you drilled in the in- take manifold. Connect the screw on the cap of the shell to one side of a switch, which may be mounted on the dash or in- strument board, and connect the other side of the switch to the ungrounded side of your stor- —-CAP HOLE ENLARGED THREADED TO z ‘FIT ' age battery. Fit HOLE IN ae MANIFOLD By closing the HOLE FO! 7 : —e switch so that EXPLODED ARMY CARTRIDGE current will aa wane flow through Borto.) =o the: resistance i REsstnce,«CWire in the cS RESISTANCE Shell, consid- a WIRE erable heat will be pro- duced almost instantane- Y , ously, and this i CARBURETOR -* eas) will enter the a CARTRIDGE intake mani- enc sea ama fold, vaporiz- ing the gas before it reaches the cylinders. —Clyde E. Volkers, Terre Haute, Ind. @A mixture of four parts sodium fluoride and one part of pulverized sugar is effec- tive in destroying ants. PO CARA SA

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¥. All Shop Notes published in 1928, in book form—Fifty Cents—from our Book Department Sanding on the Lathe By W. CLYDE LAMMEY Most home craftsmen will agree that the sanding of their work, prepara- tory to finishing, is the most tedious part of the whole business, and, for that reason, it is often slighted, to the detriment of the finished job. Sanding rough stock espe- cially demands the use of no little energy, and where there is much of this work to be done, it will pay the worker to spend a little time in the construction of a con- trivance to do the sanding mechanically. This is easy if he has.a small lathe in his home shop. Obtain a piece of 3 by 3-in. stock, 10 in. long, and cut a groove, %4 in. wide and 1 in. deep, down the center of ofie face, that is, 1% in. from the edge. Center the piece in the lathe and turn it to form a drum, 2% in. in diameter. Be careful to Here Is a Simple Sander That Will Take the Hard Labor Out of Finishing Lumber, Insuring a Good Sur- face with a Minimum of Work 685

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686 POPULAR MECHANICS have the drum of exactly the same diam- eter throughout its length. Any kind of stock will do for the drum, although good well-seasoned hardwood is preferable. Next get a piece of 2 by 8-in. stock and cut from it a piece, 16 in. long. Draw a line square across the stock, in the center of its length, and on this line bore two holes for 4%-in. bolts. Cut another piece of stock of the same width, but 1 in. thick and about 2 in. longer than the width across the lathe ways. Cut two grooves across the face of this piece, so that they will fit over the underside of the lathe ways, as shown in the drawings, and, using the first piece as a template, drill two holes for 4-in. bolts. The height of the table shown in the illustrations is 57% in., from the top of the lathe bed to the top of the table. This is for a lathe of 8-in. swing, but of course this dimension must be determined by the lathe the sander is to fit. The tables are made of 1-in. stock, well dried, and should be at least 8 in. wide, and better 10 in., to afford a good bearing for the work. They must be planed to a true surface and mounted rigidly on the 2-in. base. Use screws and glue (not nails) in assembling, and be sure that the height of the drum carrying the sandpaper will not be more than 4¢ in. above the surface of the tables. Also be sure that the surfaces of the ta- bles are not thrown out of true in assem- bling. Bevel the ends of the tables that go next to the drum. The method of mounting the assembly on the lathe is apparent from the drawings. A sheet of garnet paper is attached to the drum by cutting to size and folding the edges into the groove, afterward driv- ing short wedges into the groove on the ends and cutting them off flush with the surface of the drum, so that they do not strike the work. It will be found that this sander is a great improvement over the hand method, the high speed of the lathe leaving the work smooth and without objectionable scratches. It also leaves a true surface, if the work of constructing the sander has been done with reasonable care. Swab for Applying Acids An easily made swab for applying acids and other substances, which must not come in contact with the fingers, is shown in the photo. Simply remove the con- tents from an old flashlight dry cell, fold a piece of burlap or heavy cloth into a flat strip and pinch the opening of the cell tightly over it. The zinc is worked easily with the fin- gers, and it holds the cloth ofr swab firmly. The remainder of the cell pro- vides a conve- nient grip for the swab.— F. W. Bent- ley, Jr.. Mis- souri Valley, Iowa. Parts of Car That Are Seldom Lubricated Many automobile owners are under the impression that every part of the car has been oiled or greased sufficiently at some time or other. However, this is far from true, and there are usually a number of places that are seldom, lubricated even though they need it b#dly. Insufficient lubrication often is the cause of expensive repairs. The grease cups that are hard to get at are neglected even by many garage attendants, so the owner ought to know where they are. Thev are usually found in inconspicuous locations as, for exam- R

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POPULAR MECHANICS 687 ple, the two cups that oil the outer rear- axle shaft and the roller bearings. These are located on the rear-axle housing, near each end and close to the brakes. It is more important that they be given atten- tion than the spring hangers, but in spite of this, only a few auto owners know of their existence. These cups should be filled once a month. The efficiency of the brakes depends to some extent on how well the brake mechanism is lubricated. One brake pin may “freeze” for lack of oil, and this will throw the entire mech- anism out of proper adjustment. Once a month it should be oiled, from the pedal to the brake shoes, with penetrating oil. Another often neglected part is the uni- versal joint. Of course, nearly everyone knows it’s there but it is nevertheless fre- quently overlooked. A few drops of oil on the generator is necessary now and then and clutch bearings should not be forgotten. Resurfacing Farm Anvil An old farm anvil can be resurfaced with very little work by using the rig shown in the illustration, which consists of a grindstone or emery wheel driven back and forth over the anvil surface by means of a pump jack run by a small en- gine. A 12-ft. length of 2 by 4-in. stock is used as a connecting rod between the pump jack and the emery wheel, and a suitable weight is tied or otherwise fas- tened to the top of the connecting rod, near the emery wheel, as indicated. In some cases, it may be found necessary to provide guides for the connecting rod so that the emery wheel will not slip off. OLD EMERY { WHEEL ! Resarfocing, an Old Farm a op ws Anvil by Means of a Pump c—- Jack and Emery Wheel Load-Balancing Pushcart f -EYEBOLTS END VIEW WHEN L ASSEMBLED Heavily Loaded Cart Can Be Better Balanced by Shifting the Axle Loaded pushcarts are often improperly balanced so that, when the greatest weight is on the front end, the cart will have a tendency to tip over in this direction, and when the most weight is on the back, the person pushing the cart must practically lift the load besides pushing it, which is very tiresome. To overcome this trouble, I arranged the axle so that it could be moved either forward or backward to bal- ance the load. The axle was bent to a U-shape and was securely attached to the underside of the cart by means of eve- bolts. A Y-shaped brace, made from flat iron, was fitted on the ends of the axle, holes being drilled in the ends of the brace for this purpose. A slot with two notches was cut in the single end of the brace to accommodate a bolt, with which it was held to a flat-iron bracket attached to the underside of the cart near the handle. The bolt is fastened securely to the bracket by means of two nuts, and the slot in the Y-brace slips on the shank of the bolt, but cannot come off as it is held between the head of the bolt and one of the nuts. The end of the Y-brace is bent down at right angles to form a handle, permitting the worker to shift the brace and wheels back and forth as desired. The body of the cart is held quite firmly in either position—S. E. Schofield, Indian- apolis, Ind.

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688 POPULAR MECHANICS Simple Hitch Permits Worker to Lower Himself at ill on Boatswain's Chair Rigging Boatswain’s Chair To rig a chair for lowering or raising yourself, hook a single block on the roof, ‘ wall or structure on which you are going to work, and with a gantline rove through it, make the chair fast as shown in the upper left-hand detail. Get in the chair and have someone pull you up to the top. Then take a small length of rope or strong marline and lash the two parts together, being careful to have the lashing secure so that it will not slip. The man below can then let go of the end so that you can pull up some slack. Then take hold of the bight of the rope and pull it toward you through the bridle of the chair as in the upper right-hand detail. Slip the bight over your head, around your body and the chair, and draw it up as shown in the center drawing. You can now let go of the lashing and you are all set to lower yourself at will. This is done by taking hold of the rope and pushing it through the loop. It cannot ‘slip or get away from you.—C. Newkirk, Chicago, II. @A length of garden hose, split and slipped over the teeth of a saw that is being filed, is a handy arm protection. Reducing Speed of Lathe Here is a novel method of reducing the speed of a small metal-cutting lathe: Get an old-type auto-starting motor equipped with a sprocket, of the kind used on many models prior to 1919. These motors have a reduction gear, which in case of a Wag- ner motor is 1 to 10. Remove the core and commutator from the shaft so that the case serves merely as a housing for the shaft and the gears. A small grooved pulley, suitable for a 4%-in. round belt, is securely fastened to the shaft. A length of belting is run from this pulley to a similar grooved pulley on the motor that drives the lathe. A bicycle sprocket is attached to the driving pulley on the lathe and in line with the sprocket on the start- ing motor, the two being connected with a bicycle driving chain. I have reduced the speed from 1,750 to 50 r.p.m. in this way.—Sidney Cornell, New York City. Compressing Heavy Springs When assembling rather stout or heavy springs, as, for example, the spring re- tainers for truck radiators, the method illustrated will prove advan- tageous. A wire nail is placed through the cot- ter-pin hole in the end of the stud and the spring is screwed down on this, thus gradu- ally compressing the spring. When the spring has been screwed down far enough, the washer and nut are slipped on a few threads, and the nail withdrawn. This method will save 10 to 15 minutes of fum- bling and prying down on the spring, while trying to engage the thread of the nut. Annealing Small Sheets of Aluminum After a small sheet of aluminum has become hardened by hammering or swag- ing, it can be softened again by smearing a thin coating of ordinary vaseline on both sid sh Th blz tin m¢ ani de: col pe: ret lef no’ mo Ad ho: in | De suy ria! chi ma Th adj 6-i1 the wit hol thr top to | wh thr hol Hors

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POPULAR MECHANICS 689 sides and holding the sheet over a Bunsen- burner or gas-plate flame. The surface becomes black at first. By con- tinuing the heating while moving the sheet back and forth, it will sud- denly turn to its natural color. When this hap- pens, the sheet must be removed immediately and left to cool in the air. Do not cool it under water. —L. L. Llewellyn, Pied- mont, Calif. Adjustable Horses Found Convenient A number of adjustable horses of the kind shown in the photo are used ina Denver machine shop for supporting broad mate- rial at the different ma- chines. The horses are made mostly of wood. They are 4 ft. long and 30 in. high at the lowest adjustment. The 6 by 6-in. main part of the horse is braced to the legs with strap iron and reinforced with a 4-in. steel plate on top and bottom. A 2-in. square bar of steel, with 34-in. holes % in. apart, passes perpendicularly through the body, near each end. The top ends of the bars are split and forged to fit grooves turned in a 2-in. steel roller, which supports the material. A rod, passed through the holes in the vertical bars, holds the roller at any desired height. Horse with Roller of Adjustable Height Found Useful in Machine Shop Two Views of a Large-Size Photograph Printer Which Is Equipped with Exhaust Fan, Vacuum Pump and a Number of Switches Large-Size Electric Printer for the Photographer Ordinary photographic printers will only take negatives up to 11 by 14 in. in size. To make prints 20 by 24 in., and larger, one firm found it necessary to build a special printer. The photo clearly shows the construction and the arrange- ment of the lamps and snap switches, one switch being used for every three lamps, to enable accurate control of illumination. Altogether there are sixty-three 60-watt lamps and two red lamps for placing the paper in position. This printer will take négatives up to 30 by 40 in. in size. After the negative is placed in position and the printing paper laid on it, the rubber blanket is clamped in place and, by start- ing the vacuum pump, with which this printer is equipped, all the air between the pressure glass, negative and paper is removed, insuring absolute contact over the entire surface of the print. Another feature is an exhaust fan on the left side to remove the hot air from the inside.

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Wood Joints for the Amateur PART III } rn BRIDLE joint (Fig. 4) is a very handy joint for the amateur, since it is a little less difficult to make than the mortise-and-tenon joint. Its, usefulness is not as wide as that of the latter and lies more in carpentry and joinery than in cabinetmaking. However, for light frames for small doors, window and draft screens, etc., it is quite satisfactory, and also for the center legs of small semi- circular tables, as indicated. The end bridle joint of Fig. 5 is common for frames, and is known also as an open- slot mortise and tenon. The mitered bridle (Fig. 6) looks a little more difficult, but is really simple to make. The parts must be carefully laid out with square, BRIDLE JOINT Fic.4 STOPPED BRIDLE bevel gauge and knife. Then the vertical cuts forming the tongue are made, hold- ing the work at an angle in the vise and cutting down to the line defining the length of the tongue. The shoulders are then cut in the miter box. The cutting of the mouth will be described later, in connection with the end bridle. The joints in Fig. 7 are used mostly in heavier work, although the oblique bridle finds occasional employ in cabinetmaking. When making up a frame for a light paneled door, as in Fig. 8, note that the bottom of the groove for the panel on the inside edges of the rails is even with the inner edge of the tenon A, thus making the groove easy to plow. The grooves MITERED BRIDLE Fic. 6 OBLIQUE_ Ys FORM OF BRIDLE JOINT => WR I -~ f on slo in ne thi an 9, ou Fi; tw th is | lay be cu a | ho the tak sql the the

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POPULAR MECHANICS 691 FRAMING OF LIGHT 7 PANELL AAAS on the inside of the stiles run into the slots at the ends, so there is no difficulty in plowing them. When making a bridle joint, the thick- ness of the stock is usually laid out into thirds. Set a mortise gauge to the size, and gauge the edges and ends as in Fig. 9, which shows how both pieces are laid out for an end bridle, or how the leg in Fig. 4 is marked out. Fig. 10 shows the two pieces laid out, and it will be seen that the length of the slot in the leg, W, is the same as the width of the rail. After laying out, mark the waste, or stock to be cut away. The waste on the rail is cut away exactly as described for making a half-lap joint (Fig, 2, March issue). To cut out the waste in the slot, drill a hole, about %e in. less in diameter than the width of the slot, as shown in Fig. 11, taking care to keep the hole vertical and square with the face edge; saw along the lines to release the waste, and pare the bottom of the slot square. An alternative method is to make the kerfs first, sawing just inside the line, and down to the line for the bottom of the slot. Then, using a chisel the exact width the slot is to be and setting it, with the bevel toward the bottom of the slot, about %4¢ in. away from the line (see left-hand sketch, Fig. 12), drive the chisel in about 4 in.; withdraw and move it back about Y% in., with the bevel facing outward and drive it in as at B, so as to take out a tri- angular chip. Set the-edge of the chisel exactly on the line for the bottom of the slot, with the bevel toward the outer end, and drive it straight down, as at C. Move the chisel outward again, and take another chip as at D. This will bring the cut down to about the center of the stock. Now turn the stock over and repeat the process on the other side, so that the stock will appear as in the section at E, and the waste will drop out as at F. If the cut- ting has been carefully done, no further work is necessary.

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Box with Shelves and Partitions, Locked Door and Air Holes, Protects Grain Bags Box for Fanning-Mill Screens and Grain Bags Fanning-mill screens and grain bags can be kept out of the reach of rats and mice by storing them in a wooden box, as shown in the illustration. Shelves and partitions are provided in the box so that the stored material can be arranged in an orderly manner, and large holes are cut in the ends to provide adequate ventila- tion, the holes being covered with wire mesh tacked down securely on the inside to prevent the entrance of rodents. Care should be taken to have the door or cover fit snugly and a hasp and padlock may be provided. Periodical examination of the box is recommended so that, if rodents have gnawed a hole in it, prompt repair can be made.—J. R. Koontz, Bremen, Ind. Prints from Wet Negatives Nearly every photographer realizes that certain pictures, especially those for news- paper publication, must be finished quickly in order not to lose their news value. To make contact prints from wet nega- tives, a saturated solution of potassium carbonate is prepared. After the neg- atives have been. washed they should be wiped off carefully with a soft cloth or a piece of chamois skin, and placed in the potassium-carbonate bath for a few mo- POPULAR MECHANICS ments, after which they are again wiped dry. The potassium carbonate provides a dry surface from which contact prints can be made. The negative should be thor- oughly washed and dried in the usual way after the prints have been made. When enlargements from wet negatives are re- quired, the negative should be rinsed free from hypo and placed in a five-per-cent solution of formaldehyde for one or two minutes. The negative will then with- stand the heat of the enlarger and any number of copies can be made. If the negative is to be preserved, it must be washed and dried in the regular way after being removed from the enlarger.—Jesse A. Leason, St. Paul, Minn. Kink for Using Tape Line Often, when using a tape line, one has no helper around to hold the eye end, which is particularly inconvenient when measuring from one point to another without any surface to press the line against. This trouble can be eliminated in many cases by opening the middle sec- tion of a 2-ft. rule, catching the eye of the line on the small wire pin, and then closing the halves of the rule so that the eye will be held firmly between them When making ; vertical meas- urements the rule can be laid down and one foot put on it while drawing the tape taut. If the measuring is to be done on the ground, the rule can be pushed down into the soil. Preventing Marks on Work in Lathe When running a piece of finished work in a lathe steady rest, it is common prac- tice to place a piece of soft metal over the end of the jaws in order to prevent them from scratching the work. A better and more up-to-date method is to make an SS oO @ OO tha 2 oh oe Oe Oo ee oe ee

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1em and an POPULAR MECHANICS 693 extra set of jaws out of bakelite or similar material. They are very strong and will not scratch the work. Clearance of Milling Cutters In grinding the clearance on the cut- ting edge of milling cutters, sufficient at- tention is usually not paid to the angle or exact amount of clearance the cutter will have on the work. If too great, the cutter will have a tendency to chatter and make a rough finish, to say nothing of the disagreeable noise, and the loosening up of the bolts and clamps on the machine will cause the heel of the land to drag, making an uneven surface, and is. liable to break the teeth. The angle depends, to a great extent, on the diameter of the cutter and also on the material it is to cut, although, in general, milling cutters are used on almost anything that can be cut, from a piece of hard wood to high- carbon tool-steel, making regular shapes, such as plain, slabbing, slanting, or an- gular, while in those that are made up for a special job and used for that purpose only, more attention must be given to the kind of material to be cut. Generally soft materials will machine better with more clearance than tool steels, and the like, although conditions may cause the reverse to happen. Usually, for cutters up to 4 in. in diameter, from 6 to 7 deg. will be found ample on the outside diameter. Over and above this diameter, the angle may decrease, say, % deg. for each 1 in.in diameter, un- til 4 deg. is reached, which is about the minimum amount for any cutter. The clearance on the teeth of end mills should be from 2 to 3 deg., when the cutters are used for roughing and fin- ishing. If used for roughing alone, a little more clear- ance will be better. When Breaking Concrete Using an Old Broom to Hold the Chisel When Break- ing Concrete An old broom will come in handy when breaking up concrete. Use it as shown in the drawing to hold the bull point or chisel, and to prevent bits of concrete from flying up. When using a com- pressed-air hammer, or power concrete breaker, slip a piece of screen, about 1 ft. square, over the point of the drill. This will enable the operator to see the work through the screen without danger from flying bits of concrete. Sawing Metal Rod at an Angle To saw lengths of tubing or metal rod at an angle on the power saw, I use a couple of pieces of wood as auxiliary vise jaws. By allowing these to extend a little beyond the cut as indicated, I have found the work can be sawed at any an- gle just as easily as straight. The saw, of course, cuts through the wood jaws before striking the work, so that, by the time it reaches the cut, it is well guided. Scrap pieces of wood are usually to be found around any machine shop. —A. Dane, Potts- town, Pa, Using Wood Jaws for Sawing Metal Rod and Tubing at an Angle —Harry Moore, Montreal, Can.

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HEAD OF a? DRILL Tool Driven by a Ratchet Wrench, Handy for Drill- ing in Confined Places Simple Tool for Close Drilling For drilling in close places, a small ratchet drill is often found too large. A more compact tool is necessary where the flanges of the castings or the webs of channels are spaced 3 or 4in. apart. One of the handiest devices for use on such jobs consists of a suitable length of hexa- gon bar stock, a setscrew and a ratchet wrench. A hole is drilled in one end of the bar to accommodate the drill, and the other end is drilled and tapped for a set- screw, the head of which is ground to a point. The drill is ground down, half of the head being removed as shown in the upper-right detail. This allows it to be securely locked so POPULAR MECHANICS Strong, Durable Plaster-of-Paris Mixtures Fifteen years ago, I set %4-in. bolts, at- tached to a sundial triangle, into 5-in. holes, 3 in. deep, in a stone base on the grounds of the Ontario hospital, at West Toronto, Can. The cement I used was made of 4 oz. of plaster of paris, 4 oz. of portland cement, and ¥% oz. of dark brown sugar. The ingredients were well mixed, and just enough water was added to make the whole fairly stiff. This cement has been exposed to the weather at all times, and the bolts are as firmly set in it as they were 15 years ago. The same mixture is often used by heating engineers to cement together the joints on 4-in. cast-iron pipe, sometimes used in greenhouse heating. It sets very hard and is waterproof and easy to work. The addition of a small quantity of fine sand will make a stronger and perhaps harder cement. To keep plaster of paris soft for slow working, mix wheat flour in it, in the proportion of 4% oz. of flour to every 5 oz. of plaster. Us- ing a greater amount of flour will retard the drying of the cement still more. If asbestos powder is used in plaster of paris to make it tough, it should be very care- fully sifted through an extra-fine sifter before using it. Coarse asbestos powder will prevent the cement from setting so strongly as when finer powder is used. All combinations of plaster of paris and other powders should be thoroughly mixed before adding any liquid—James E. No- ble, Toronto, Can. Nailing Joists Single-Handed One man can handle a joist single- handed and nail it in placé at both ends by the method shown in the illustration. Drive a nail partly in at one end near the top of the joist and that it will not turn. The ratchet wrench is then slipped over the body of the tool, and by manip- ulating this, the hexagon part will be turned and the screw will be fed down into the work.—G. A. Luers, Washington, D. C. i Vis A/i aa Joists Can Be Nailed in Place Single-Handed by Fol- lowing This Method hook the nail over the sill to hold the joist in place tem- porarily until the other end has been nailed securely. Then remove the first nail and pro- ceed to nail this end also.—H. H. Siegele, Emporia, Kansas, ra

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id POPULAR MECHANICS 695 Kink for the Planer Bed While watching a worker setting up a job on the planer bed one day, I noticed that he had his clamps resting on several sloping surfaces. Wondering how he was able to keep the clamps from slipping off, I investigated and found that he had placed short pieces of old files between the end of the clamp and the metal incline, making the surface non-slipping.—Frank | N. Coakley, Buffalo, N. Y. Expanding and Contracting Circular Machine Parts Circular machine parts are sometimes machined slightly over or undersize. In the latter case, the part is sometimes plated to restore it to the desired diameter, but, in many small shops not having plating equipment, simpler expedients must be used. A method of expanding and con- tracting circular parts, which, while not highly accurate, will serve in many cases, consists in driving a taper pin into reamed holes drilled near the edge of the work as shown in the drawing. The examples illustrate the method of decreasing the size of the bore and enlarging an under- size bushing, plug or disk. The material to be altered must be moderately soft, so that it will yield to the pressure applied ENLARGING AN UNDERSIZE BUSHING SECTION THROUGH BORE Drill and Taper-Pin Reamer Are Used to Expand or Contract Machine Parts with a comparatively hard taper pin. The only tools necessary for this work are the usual drill and taper-pin reamer. Iron Hooks Used to Anchor Concrete Window Box Securely to Basement Wa Window Boxes Anchored to Cellar Wall Many houses built nowadays have the first floor only a short distance above the ground level, which makes it necessary to box in the basement windows. The boxes are usually made of concrete and, in many cases, they gradually pull away from the wall and allow leakage. To pre- vent this, one contractor anchored them securely to the wall by means of two iron hooks, as indicated in the drawing, the hooks being imbedded in the concrete when this is poured. If the basement wall is built of stone or concrete blocks, the anchors are slipped between the stones or blocks when the latter are laid, and then imbedded in the window box. It has been found practically impossible for the boxes to pull away from the wall when anchored in this way. Easy Method of Sandpapering Auto When I started the job of repainting my auto, I knew that a lot of sandpaper and muscle was necessary. I drove the car down to the beach, and by using plenty of sand and water with a piece of heavy felt, I removed most of the paint. By using a fine grade of sandpaper in going over it a second time for finishing touches, the job came out very smooth, at a con- siderable saving in effort and sandpaper.— Charles Latour, Jr., Plattsburg, N. Y.

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PART II IGURES 5 and 6 detail the upper sec- tion. While complicated in the assem- bly, the individual parts are comparatively simple. The back is 2 ft. 234 in. by 3 ft. 43% in. From the right upper corner a piece, 7% by 11% in., is cut, and for a dis- tance of 5 in. above the horizontal part a strip 4% in. wide is cut. Mark for this cut and saw obliquely toward it, springing the blade out, and cutting in with the line as quickly as possible. Then saw in the op- posite direction to finish the cut. This notch receives the rabbeted end of a side- piece. The upper left corner is cut out 8 in. by 1 ft. 10 in., the vertical cut then be- 696 aking a ing notched % by 6% ~ in. at the bottom and ; Y% by 71% in. at the top Rabbet the lower end % by % in. for 8% in from the left, and & in. from the right. The long right side (center piece marked A in Fig. 6) is 16% in. by 34 in. Rip % in. off the back, ex- tending from the lower end to within 43 in. of the top. Cut a 7% by 8-in. piece from the lower back corner, and rabbet it 4 by % in. Then, from the front upper corner, take a piece 7% by 9 in. A 4% by %-in. dado is cut full width of the inner face, 12% in. from the lower end, and a second one, 2% in. above it. A third is made 7 in. farther up, that is, with the upper side flush with the bottom of the big notch. This is deepened to ¥% in. on the horizontal part of the notch, and this % by %-in. rabbet is carried up the notch and across the top. The left rabbet cor- ner is notched % by % in. A vertical dado, running from the lower end to the first dado, is 7% in. from the front edge. Rabbet the projecting lower end % by ¥% in. On the outer face two dadoes, 4 by ¥% by 83% in., are cut, one 7 in. above the lower end, the other 83% in. above the first. A third, full width of the narrow upper end, is 10% in. above the second. The long left side (left-hand piece A, Fig. 6) is 1 ft. 434 in. by 3 ft. 5 in. The inner-face dadoes correspond to those of the other side, as does the lower rabbet >_ ata of 4 or —-- 2p eh pee 6 — —e =e a fee ' ef. Ok Cnet Oe Oe tA

Page 175

= 2 eer SE ww —-— w+ oOo fe NT oo WM}. = E.M.Love and notch. A fourth horizontal dado corresponds to the. upper rabbet of the other side. The upper end is rabbeted % by % in. Between the two upper dadoes cut out a rectangle, 834 in. wide, and rabbet all around this % by % in. Cut a %-in. strip off the back edge from the bottom to a point 1 ft. 6% in. above, and rab- bet the rest 4% by % ine AG by 34-in. dado extends from the upper horizontal dado to the top rabbet, as in Fig. 6. Two dadoes, yy by % by 7% in., on the outside at the back, one 7% in. above the lower end, the other 9% in. above it, carry the small side shelves. Make the top (A in Fig. 5) 1034 by 1634 in. Rabbet the back edge on the underside % by % in., and saw a strip off the right side, 4% in. wide, for a distance of 8 in. from the front. The shelf below (K) is 10% in. by 1 ft. 334 in., with a 4%-in. strip off the left side, 734 in. long. The next shelf down is the same, except that a %-in. strip, 8 in. long, is removed from the right edge, starting from the back. The follow- ing two shelves are 10% in. by 1 ft. 4 in. The bottom shelf is L-shaped, 18% in. wide at the back, 1 ft. 4 in. from the front to the back, and 10 in. wide in front. It fits both the middle and the right com- partments. The three partitions are next made. The upper one, between the top and the first shelf down, is 6% in. high and 10% in. wide. The middle one, just below it, is 8% in. high and 103% in. wide. The one below this is 8% in. high and 10% in. wide, while the lowest is 12% by 10% in. At this stage it is well to assemble the parts so far as they are made, not only because it makes clearer the arrangement of the other pieces, but also because any small errors may be compensated for in making the rest. Assemble the sides with the shelves and partitions, nailing the butted upper and lower edges of the par- titions, and add the back. The top of the right wing, 8 by 9% in., is rabbeted % by % in. on the underside 697

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698° at the back. The front section fitting with it is 734 by 12 in., rabbeted at the upper and lower edges. It makes a butt joint with the long side, while the top piece fits into a dado. The shelf below is 7% by 8% in., and the sidepiece fitting against it is 9% by 8% in., rabbeted % by % in. at the top and bottom. In addition, the front edge is notched back % in. to fit into the rabbets of the front pieces. The next shelf is also 73%4 by 8% in., and the lower front part is 7% by 8% in., rabbeted Y4 by &% in. at the top and 4% by %& in. at the bottom. The top of the left wing, detailed in Fig. 6, is 8% by 8 in., and rabbeted %4 by ¥% in, at the back. The middle shelf is

POPULAR MECHANICS 8 by 7% in., and the lower is 8% by 7% in. The side is 8 by 19 in., with the upper end and back rabbeted % by % in., and the lower end 4% by % in. A % by %-in. dado across the inner face, 10 in. from the lower end, supports the middle shelf. When assembled, plane off all project- ing ends and scrape uneven inside places. A \-in. strip of wood is glued into the open joint inside the right lower com- partment. It is difficult to hide the plies of the edges with paint, even though they are well sandpapered. The writer has found gesso to be the most satisfactory prepa- ration for filling the plies. Smear on thickly, working well into the pores, and

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Page 177

POPULAR MECHANICS 699

C=DADO ; DEEP < \ Fia.6 then rub off reasonably smooth with a putty knife. Allow it to dry for a day or so. Then carefully trim off lumps with a sharp chisel, smooth with No. % sand- paper, used on a flat block, and finish with fine grit. Any open joints can also be filled with gesso; in fact, a pretty sorry-looking job of cabinetmaking can be made into a reasonably good surface for painting, and if the reader has bad luck with the book- case, either in the way of open joints or splintered veneer, he will do well to try filling the defects in this way before aban- doning the project. Sand off all corners to a radius of about

Ye in. Give three or four coats of flat paint, all well sanded, before applying enamel. The case in the photograph was painted sage-green, and striped on the sides of the top nosing and the top of the heavy base member with orange. The tops of the steps of the nosing, and of the narrow member of the base, were made lavender. Secure the top to the lower section with small iron strips on the back and a screw through the lower-section top into the bottom shelf of the upper section. @A piece of rosin stirred into melted bab- bitt will make it run better.

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POPULAR MECHANICS Time and Labor-Saving Kinks Upper Left, Two Stout Oak Posts Set Up in the Position of an Inverted “V,” Hold Wire Fence Taut in Hollow; Upper Right, Block and Tackle, Passing through the Shed Roof and Attached to a High Support above the Shed, Facilitates Butchering of Large Animals, Which Are Hoisted with a Team of Horses ——_ NG Wagon Step Made from Pieces of 1- In. Wood, Bolted or Screwed Se- curely to Two Lengths of Flat Iron, Which Are Bent to the Shape Shown, Is Hooked onto the End Gate of a Wagon; It Has Been Found Especially Convenient for Huckstering and for Delivery Pur- poses; Being Removable, It Can Be Put Away When Not in Use The Dairy Thermometer Can Be Protected against Breakage When Stored Away by Slipping It through Screweyes Located in a Groove Cut in a Piece of Log, the End of the Groove Forming a Support for the Instrument Device for Holding a Cordeau Spool While Loading Well Drill Holes; a Wooden Brake Is Provided to Stop the Revolving Spool, a Pointed Stick Being Used to Hold the Brake Down and Also to Punch Holes in Dynamite Cartridges

Page 179

POPULAR

Found Useful by Keen Farmers MECHANICS

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Wedges for Splitting Tim- ber Are Always Handy in This Carrier

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Above, Adjustable Roofs for Haystacks Used by Some Mary- land Farmers; Left, Hay Protected by Layer of Corn Stalks; Right, Light Shed Built over Haystack

Handy Hitch Permits Quick Detachment, the Rope Bein Slipped through an 8-Shaped Iron Rod Welded Together

To Help Prevent Water in the Stock Tank from Freezing, Provide a Hinged Cover of 1-In. Wood; the Cover Should Be Sectional, Which Makes It Much Easier to Handle Than if It Is Built as a Single Large Piece

Wagon End Gate, Called a *“*Shoveling Board,” Saves Labor When Un- loading Corn with a Shovel, as the Work of Hoisting the Corn over the Gate Is Entirely Eliminated

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702 POPULAR aS {JI i ali anit Burning Gasoline on Putty Softens It, Thus Facilitat- ing Its Removal Fire Softens Putty on Sash Here is a simple idea that greatly facil- itates the job of removing old putty from window sash of which the pane is to be renewed. Get a small oilcan, of the kind in which a light grade of oil is sold, and fill it with gasoline. The hole in the spout of such a can is so small that the stream of gas can readily be controlled. First remove the old glass, then place the sash on a flat bench or table and squirt gasoline on the putty, being careful not to let it run over the wood part of the frame. See that all the windows and doors of the room in which this is done are closed so that there will be no draft. Ignite the gas on the putty with a match. The air com- ing from all four sides will cause the flame to rise toward the center of the sash, and hence will not scorch the frame. The heat causes the putty to become brown, and if enough gas is used, one burning is usually sufficient to soften the putty so that it can be removed. Do not let the putty cool off, as cooling hardens it—B. R. Glatts, Weiser, Idaho. Making Plastic Filler for Wood The home mechanic can make a good plastic wood for filling holes, cracks, etc., by mixing sawdust, sifted to the de- sired fineness, or wood flour if obtainable, with any transparent brushing lacquer. After mixing, the filler should be kept in an air-tight container to prevent it from MECHANICS hardening. However, if it should harden from exposure to air, it can be restored to working condition by adding more lacquer or lacquer thinner.—J. S. Hagans, Chicago, II. Improvised Ratchet Wrench With the aid of this improvised ratchet wrench, work can be assembled in a frac- tion of the time usually required. The wrench can be made by any machinist in an hour or so, and the details of construc- tion are clearly shown in the drawing. The body is made of a piece of flat iron, drilled and equipped with pins at the points indicated. A handle, made of stock of the same thickness, is pivoted to the body by means of a screw. The nut holder is made from an ordinary hexagon nut, filed out square, and part of it is turned down on the outside to fit the hole drilled in the body loosely so that it can be turned easily. After the turned-down end of the nut is slipped through the hole in the body, a washer is placed on this end, which is then riveted over to hold both the nut and the washer in place. In the shop where this idea originated, each ma- chinist has from two to five of these —| Any Machinist Can Make This Simple Ratchet Wrench Which Saves Considerable Time wrenches, varying in size to meet the needs of different jobs.

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wT = = nch ‘he AT LAST A HOUSE IN IRISH STYLE Copyright, Popular Mechanics ie ti par, H ae e i iti hn ee een * 4 VAS, n Plan No. 4-S-40 Here Is Something New—a Tabloid Plan: Studio Living Room, Attached Garage; House Can Grow as Your Purse Permits HY NOT a house in Irish style? Sounds interesting, doesn’t it? Log- ical, too. We've borrowed style features from the Spanish, Dutch, English, Italians, Swiss and adapted them to American houses. Why should we longer neglect the fine traditions of the Emerald Isle? Those sturdy thatched-roof houses of old Erin are in many ways as picturesque as the rambling half-timber cottages of Merrie England or the adobe houses of sunny Spain, topped with colorful tile and built around a patio. In the little house above, the designers have merged a bit of old-world tang with a.dash of American daring and pro- duced a touch of originality—perhaps just those features of style and service at low cost you’ve been house offers you all the efficiency, com- forts and conveniences of a roomy, yet reasonably small kitchenette apartment. In addition, the house may grow as your purse permits. In fact, you can make ad- ditions to the plan now if you wish. The architects have given you a thatched roof with slight roll at the eaves, Jaid with variegated edge grain cedar shingles in brown and green; stucco exterior on metal lath with half-timber effect, reminiscent of old-world solid walls and plaster finish, and a rugged chimney of either fieldstone or brick, to add the external touch of solidity found in many an old Erin house. All of these features have been incorpo- rated in a tabloid plan, and done so skill- fully that you marvel at the roominess and spacious effects looking for and haven’t found as yet. Certainly there’s romance and atmosphere here a plenty. But that’s not all. Aside from something new, stylistically speaking, the little HOW TO GET THE PLANS To help our readers get started on one of life’s most glorious experiences—building and owning a home—Popular Mechanics Magazine will sup- ply readers a one-sheet blueprint of the house here illustrated for $2. This blueprint does away with the necessity of first purchasing a complete set of plans to find out whether you can afford to build. It contains floor plans, eleva- tions, a section, detail, size of joists, studs, etc., and also a brief specification. Submit it to tradesmen and dealers for building estimates. in so small a house. Garage and house are all under one roof and can be placed on a lot as narrow as_ thirty- five feet. Let’s look over the plan and equip- ment. There’s a 703

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POPULAR MECHANICS -Firyt-FLloon-Piran« studio-type living room with high ceiling and rafters exposed. A “Romeo and Juliet” balcony opens from the second- floor sleeping room and overlooks the living room below. An open stairway to the second floor is a feature. Next to the fireplace is a bed closet. This may be used for emergency purposes or, if the family is small, it may serve as permanent sleep- ing equipment. A toilet on the first floor, always a convenient feature, makes the first floor really quite a complete bunga- low as far as equipment is concerned. Notice that the dining-room floor level is raised one step above the living-room level. That’s a touch of individuality. A porch may be built to the rear of the din- ing room, China cabinets flank a spacious window overlooking either garden or ter- race. No doubt the full-mullioned win- dow will prove a joy to housewives who appreciate the decorative possibilities of such a feature along with the flood of sun- shine it provides. The second-floor bedroom is planned for picturesque effects. A vanity alcove between the two closets will please the ladies. Opening from the upper hall, there is a door leading to the deck or roof of the garage. By stretching an awning over the deck, this space may be used for living or sleeping purposes in summer. In fact, a second permanent bedroom may be added to this deck now if you wish one. 10''* 12" ~SECOND-FLOOR-DLAN- This is a basementless house because it saves fifteen per cent on the cost. A basement may be had if you want one. Notice how the first-floor heater, placed in the rear hall, is served with fuel through a wall opening beneath the stairs. Fuel is stored off the garage under the stairs. The house is of frame construction and fully insulated. Interior finish may be of large surfaced insulation boards or wallboards treated with plastic paint or decorated to suit your taste. This means a saving over lath and plaster. Summed up, you have in this little house every modern, practical space-sav- ing feature along with a high degree of comfort and a large measure of style. You have it all at very reasonable cost. Re- cent Chicago estimates say $5,300 will build the house complete. Chicago prices range from ten to twenty-five per cent higher than prices in many other localities. EDITOR’S NOTE: Popular Mechanics Maga- rine has prepared a home plan book, ““Twenty Popular Low Cost Homes and Ten Command- ments for Home Builders.” These are selected homes and show labor, space and timesavine ideas. They are $5,000 homes and less. Send 10 cents in stamps to cover postage. Address Building Editor.

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