Popular Science Monthly 1925-05: Vol 106 Iss 5

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I : RADIO SECTION 4 | How you can builda | simple 1-tube set for nec & distance and quality. Jack Binns on broad- oo MONTHLY hints for eostphane / a M AY Gigantic engines foreshadow new era in transportation 25 CENTS. a { How you mistreat your car—p. 71

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POPULAR SCIENCE MONTHLY SUMNER N. BLOSSOM, Editor May, 1925 Giant Engines Point to New Era in Transportation A story of the remarkable struggle between steam, electricity, and oil—Marvelous inventions may mean cheaper travel by rail and sea EVELOPMENTS in transporta- tion during the last few months all seem to point to the ulti- mate subordination or elimina- tion of steam as a direct source of power for the movement of ships and trains. - Significant of this trend was the recent arrival from Great Britain of the motor- ship Aorangi at the Panama Canal and later. at San Francisco, and the keen in- terest of American engineers in this beau- tiful 23,000-ton passenger liner driven by: internal combustion engines. Like- wise, the activity of the U. S. Shipping Board in installing Diesel engines in ships that formerly were equipped with steam, has created widespread comment. Among other signs that have led engi- neers to-ask seriously whether the day of steam is. passing is the announcement of Samuel M. Vauclain, president of the Baldwin Locomotive Works, that his company is experimenting with a locomo- tive driven by electricity generated by a Diesel engine. The. announcement of the Pennsyl- vania Railroad that contracts have been let to electrify the main line of that road between New York and Washington, and the announcement of the New York, New Haven & Hartford Railroad that more of its branch lines are heing electrified. What is happening in the field of. transportation? What tendencies are apparent just how, and how will they affect steam? Modern transpor- tation came into existence as a result of the discovery of the power of steam, and for 100 years it was the develop- ment of steam engines that made Possible the development of portation. Twenty years ago One of the most extraordinary of the new developments in locomotives is this odd-looking steam-turbine engine of 2000 horsepower, recently built at the Krupp works in Germany. By Hawthorne Dantel steam had just about completed the task of running sailing-ships from the sea; and ashore, except for street railways and a few wheezy automobiles, steam was practically supreme as a source of power for transportation. Recently, however, Lloyd’s—that great marine insurance organization that com- piles most of the world’s nautical data— has announced that more than one- third of the total ship tonnage now being built will be motor-driven. And reports come from railroads all over the world—from India, Spain, Britain, Swit- zerland, America and elsewhere—that electricity and other sources of power are making serious inroads against steam. Let us see first what is happening at sea before we turn our attention to the railroads. The first ocean-going passenger ship propelled by Diesel engines was the East Asiatic Company’s Selandia, built in 1911. She is capable of 12 knots and has a dead-weight cargo capacity of 7400 tons. Today the largest and most power- Will This Monster Stem the Tide away from Steam? ful of these new ships actually in opera- tion is the newcomer in the Pacific—the Union Steamship Company’s passenger liner Aorangi—a ship of 23,000 tons dis- placement and a speed of eighteen knots. Yet so rapid is the development of. ships of this type that within the year the Aorangi will be surpassed by no less than six Diesel-driven ships that now are being built. T° UNDERSTAND thoroughly the motor-ship and its ability to compete so successfully with steamships, you first must eliminate definitely any connection between a motor-ship and a motor-boat. They are no more alike than a great Mogul locomotive and a steam-driven automobile. A motor-boat is propelled by one or more gasoline engines, exactly the same in principle as the motor that drives your ear. The motor that drives the motor- ship, on the other hand, is different in design, principle, size, and power. On the Aorangi, for instance, the four main engines, used to drive four pro- pellers, can develop 17,000 horsepower, and their service speed is only 127 revolutions a min- It is reported to develop greatly increased hauling power with a 20 per cent saving in fuel over the ordinary reciprocating type of locomotive still in use on most of our railways 23 *

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POPULAR SCIENCE MONTHLY Electric Drive Combined with Steam Turbine Is French Invention Millions of tons of coal might be saved to our railroads annually, it is claimed, if the present reciprocating engines were replaced by this type of turbo-electric locomotive recently invented by M. Leon Metais, a French The chief features of this new locomotive are a steam-generating plant and a pair of steam turbines that drive a 2500-horsepower dynamo This current, in turn, drives electric engineer. for generating electric current. ute. Automobile motors are all high- speed machines in comparison with these great engines, and many automobile motors turn over at speeds more than 10 times as great. HE fuel of the motor-ship is heavy oil, which is much less expensive than gasoline. Therein lies a great advantage, for even though gasoline engines could be built of sufficient power to propel so great a weight as 23,000 tons, the cost of the fuel alone would eliminate any possibility of successful competition against steam. With fuel at about two dollars a barrel, however, instead of 10 or more cents a gallon, and with the economical power thus generated, the Diesel-engined ship begins with a very great advantage. But the advantages do not end there. Stowed away in the hull of a steam- driven ship is a vast quantity of machin- ery that takes up much valuable space. By the adoption of Diesel engines about one-third of that space is saved for cargo by the elimination of boilers and coal- bunkers. So great is this saving that a motor-ship of 3500 tons, on a voyage of 8000 or 10,000 miles, can carry nearly as much revenue-producing cargo as a steamer of 5000 tons and the same speed. The following table, prepared by Mr. Bruce Lloyd, of the Emergency Fleet Corporation, shows this advantage: Motor- Steam- Ship ship Dead-weight tonnage .......... 3500 5000 Fuel oil for 45 days at 5 tons a a i a SE ie a re 225 Coal for 45 days at 45 tons a day, Mite SC pas ak aiew hws so Nees 1125 Water for boilers, tons.......... .... 100 Net paying cargo, tons (dead- weight tonnage, minus fuel ERS oo aire bin silt Gein nied 3275 3775 A motor-ship, then, can do the work of a considerably larger steamship. While motor-ships cost more to build a ton, AIR HEATER STEAM PREHEATER ELECTRIC MOTORS GEARED TO WHEELS boiler. The Turbo-Electric Drive Diagram showing the operating principles of the turbo-electric locomotive. The arrows indicate the direction of the steam and water circuit their cargo capacity a ton is greater, and so, consequently, is their earning power. Still other advantages are to be found on the side of the motor-ship. First, her crew is smaller. Stokers are eliminated entirely, or in the case of motor-ships that use steam for auxiliary purposes, the number of stokers is reduced to one or two. Second, the cruising radius, with- out refueling, of a motor-ship is very much greater than that‘of a similar steamship. IX THE case of the Aorangi it is esti- mated at 16,000 miles, which is as great as five trips across the Atlantic from New York to Liverpool. It is true that steamships burning oil are capable of much greater voyages than those burning coal, but even over these, which are the most advanced steamships, the motor- ship has a commanding lead so far as cruising radius is concerned. The use of Diesel engines in ships has brought about many interesting develop- ments. Without boilers for generating steam, motor-ships have had to depend on compressed air and electricity for their whistles. Either compressed air or electricity can create readily the sound that is necessary, but in crowded harbors where many ships are in motion, it is most desirable that there be a visible as motors coupled to the wheel axles. carried to a condenser, converted into water, and used over again in the The turbo-electric engine is said to ultilize as much as 25 per cent of the heat developed from fuel combustion, as compared with only about six per cent for the reciprocating type. running for weeks, the inventor claims, the locomotive could travel far ¢ | STEAM PIPE Exhaust steam from the turbines jg Since the turbines could be kept well as an aural signal. Otiuerwise piloty have difficulty in knowing positively which ship is signaling. To offset this dif. ficulty a ‘‘ visible air whistle” has been de. veloped. This apparatus creates its sound by using compressed air instead of steam and, at the same time, the whistle emits a cloud of white smoke by atomizing a small amount of “‘smoke liquid” froma tank connected with the whistle. Where Diesel engines are used, funnels can be dispensed with, but so accustomet have we grown to the sight of them on ships that many Diesel-driven ships erect them, then utilize them for ventilation; for exhaust pipes, air-compression tanks, and other things that might readily be placed elsewhere. Below decks, however, the space given to funnels on steamships is saved. Occasionally motor-ships are to be seen without funnels, but more than once such ships have been approached with offers of assistance by those who sur- mised that some catastrophe had swept their funnels overboard. Ships, of course, will be driven by the power that will do the work nece sary at the least cost. If the fuel df used by oil-burning steamships were increase greatly in price, it is practically certain that they would revert to @ provided the price of coal did not goup “With coal at its current price” said A. V. Moore, of Moore ait McCormack, a company that is changing six oil-burning steamers into coal burmem, “we can use oil economically under om boilers up to $9.80 a ton.” Oil, then $10 a ton, costs more for fuel when usel under boilers than coal at five dolla whereas oil at $29 a ton will do as work a dollar in Diesel engines as coat five dollars will do under boilers. Aly probable increase in the price of ® therefore, is not likely to make mowr Ir st te

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May, 1925 ships unable to compete with coal-burning ships. It is true that motor-ships cost about 20 per cent more to build than do steam- driven ships, although that is partly offset _by the fact that motor-ships carry up- ward of 10 per cent more freight, have smaller crews, and can make a little better with the same power. According to the United American Lines, operators | of the freighter Seekonk, which has been converted from an oil-burning steamer into a Diesel-driven ship, the pos- sible operating economies amount to $148,902 a year. Of this saving $67,148 is a saving in fuel. The follow- ing table, which has been verified by the United American Lines, shows some of the advantages that the new engine equipment has given the Seekonk. As Steamer As Motor-Ship Sea speed (loaded).. 10.3 knots 10.5 knots Daily fuel consump- tion at sea.. ...... 29 ~+tons 714 tons Daily fuel consump- tionin port ...... 6% tons l% ton Daily fuel cost at sea.. $355.25 $110.25 Daily fuelcostin port 79.62 4.83 Number of engine- room crew........ 16 men 9 men Wages of engine-room crews<yeat) [eee $19,520 $14,588 Yearly tuel cost, figur- ing 240 days at sea and 125 days in a $95,212 $28,064 HE higher first cost of Diesel-driven ships is their greatest present handi- cap. Were it not for this, it would seem that practically no steam-driven ships would be under construction today. And with the great increase in the demand for Diesel engines it is not unlikely that the difference in cost between them and steam-power plants will grow steadily less. Already many steamships are being converted into motor-ships. Twenty- three ships belonging to the U.S. Shipping Board and to several American com- panies already are scheduled for conver- sion, and abroad new motor-ships are being built and steamships are being con- POPULAR SCIENCE MONTHLY + ‘“ 25 The World’s Finest Motor-Ship The 23,000-ton motor-ship Aorangi, largest and speediest motor passenger vessel in the world, passing through the Panama Canal on her recent successful 16,000-mile maiden voyage from Southampton, England, to San Francisco and Vancouver. She will operate on the route verted more rapidly than the work is being done in America. It looks as if steamships have met their masters. But what about locomotives? Coal-burning locomotives long have been recognized as wasteful machines. They burn coal while standing around idle. They waste coal while under way. They pull tons of it in their tenders so that they may have enough to eat (and waste). Not content with that, they haul tons more in great gondola cars in order that they may stock great coal piles from which they may draw their daily rations. And every ton of such coal that is hauled eliminates a ton of revenue-pro- ducing freight that the locomotive other- wise could be hauling. As I have said, the New York, New Haven & Hartford Railroad long has been a user of electricity, and right now

In recent tests on an English railway, this small new type of Diesel locomotive is reported tohave hauled a train at‘a cost of only three Cutting Costs with New Diesel Locomotive cents a mile.

Instead of using coal or steam, the Diesel engine gets its power from explosive combustion of oil under high pressure between Vancouver and Australia. This huge liner is 600 feet long, accommodates 1000 pas- sengers, and carries a crew of 330. Power is supplied by four Diesel engines developing 17,000 horsepower. Her service speed is 18 knots and her cruising radius at full speed, 16,000 miles is electrifying more of its branch lines. In India the railroads in the vicinity of Bombay are planning electrifica- tion. In Switzerland electric locomotives long have been common. Even in Spain electrification is beginning. Whenever an electric locomotive is idle, it is wasting no power and no coal. The power house generates only what is necessary for the work being done, and should there be a period during which less power is needed, it is simple to generate less power. The steam locomotive can- not do that. Hew often have you seen railroad yards seemingly filled with locomotives puffing, smoking, burning coal, and doing nothing? And how often have you seen lo- comotives roar past, showering the whole right of way (and much of the country besides) with their half burned cinders? Where electricity is used, savings arise from diminished fuel consumption, from the elimination of water and coal stations with their attendants, and from greatly reduced repairs on motive power. More and more electric locomotives will take the place of steam. Perhaps our children’s children will look at pictures of our wasteful steam locomotives with much the same curiosity as that with which we ourselves now look at the pictures of the coaches that were conveyances of 100 years ago. The Detroit, Toledo & Ironton Rail- road, which is owned by Henry Ford, has announced that it is building a new type of electric locomotive for its own use. In size it will be enormous. It will weigh 340 tons, will be 117 feet long, 15 feet high, and 10 feet wide. What is more interesting still, it will have sixteen 250- horsepower motors connected with 16 pairs of driving wheels, and will be capable of hauling a train of 150 or more loaded box cars. Its running speed will be 17 miles an (Continued on page 129)

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26 £ Can You Walk a Chalk Line POPULAR SCIENCE MONTHLY OBJECTIVE Le OE ee a ae See a im aE a RY le ame Ye me Oe i Oe AG im oF he ¢,, east ' i ’ ' i ae | ~ = ' g SCY i; Si Li: 11E! ATO laa a START relax even for a second, you probably will find that your guide-posts simply refuse to stay lined up. If you play golf, you probably know this to be true from the frequent mis- adventure of the lost ball. After a whacking drive, you start straight ahead for the spot where the ball landed. As you walk you talk. Naturally, you don’t con- centrate on accuracy of di- rection. And then, all at once you awake to the realization that, although the ball may have fallen where you thought it did, you’re nowhere near the a spot. In the woods you’ll meet ; the same problem. You 4 may pride yourself on your Try This Test on Yourself To find out just how straight you can walk, pick out a tree or some other object two or three hundred yards away, then have somebody blindfold you and start you straight for it. Unless you are a very unusual person, you will find that you walk in circles either to the right or left. In carefully measured tests the author invariably turned to the right, as in Figures A, B and C, while another subject of the experiment always turned to the left of the straightaway course, as in D, E and F By Robert E. Martin AVE you ever tried to walk a chalk line? If you have, you probably found it difficult. The reason is obvious—your supporting base was nar- rowed, and you had to support your body almost on a point. But can you walk in a straight line employing your usual gait, with feet at a normal distance apart? tion you will say “yes.” However, unless yours is an unusual case, you are wrong. You can’t doit. This has been proved definitely by interesting scientific tests recently completed. The reason is that most people are more or less crooked in their habit of walking. They think straight, and they think they walk straight, but they do not. So far as actual walking is concerned, for the aver- age pedestrian the straight and narrow path is merely a figure of speech. The chances are that not even a narrow city sidewalk will keep the average man mov- ing head-on for the spot toward which he charts his course. Try it yourself. Walk across a wide plaza or through an open meadow. Pick out two fixed objects directly in front of you and try to keep them in line as you walk. Unless you make a concentrated effort, not permitting your vigilance to Without hesita- ~ sense of direction, you may know that the fishing pool is straight ahead, and yet, when you leave camp to go there, you will do well to carry a compass! Other- wise, you’re likely to find yourself walking in circles like the man Mark Twain told about. This man, one evening, was caught in a blizzard. He knew that shelter was close at hand, and yet he walked all night without finding it. Morning revealed the place of refuge he had been looking for right at his elbow. He had been walking around it all night, for there was his circular pathway marked by his tracks in the snow! Nor are darkness, woods, or blizzards required to induce this circular habit of locomotion. Walk- ing on level, familiar ground, with your eyes wide open and the sun shining, you'll find this ten- dency totravel in cir- cles asserting itself. At the Johns Hopkins University, BRAIN BALANCERS May, 1935 You may think you can make your steps go straight, but really you wander in circlee—Why whirling makes you dizzy — How to test the intricate balancing machinery of your body balance and your direction. Recently he told me many interesting things about this propensity of mankind to move like the hands of a clock—round and round, More, he demonstrated everything he said in a way that I was bound to fing convincing, for he used me as a “subject” of his tests. THE straightest of all walkers—yir. tually the only straight walker among mankind—this scientist told me, ig 9 blind man. The blind have a definite advantage over men who see, for they have developed, from necessity, a special idea of direction. Experience has taught them that painful bumps and barked shins result from deviation from a straight path; and so, by virtue of long ex- perience, they regulate their bodily movements to produce straight progress. There is a sharp contrast, though, be tween the pathway of a blind pedestrian and one who is merely blindfolded, a fact demonstrated amply by the helplessness of the ‘‘blind man” in a game of blind man’s buff, or the person who tries to pin the tail on the donkey. , Doctor Holsopple uses the blindfold frequently in his story of human balance and direction. When a man is blind folded, he is forced to “‘ walk by ear.” It may surprise you, as it did me, to learn that we walk partly by ear whether our eyes are open or not. In the vestibules of our ears are semicircular canals—two sets, one for each ear—and these govern our ability to maintain our balance and to walk straight. Each canal has three parts, which may be described as being adjusted respect BRAIN — ARE FILLED WITH LIQUID AS IN SPIRIT LEVELS Baltimore, Md., Dr. J. Q. Holsopple, of the department of psychology is inves- tigating equilibrium and orientation, which means your ability to keep your levels. How Your Balancing Mechanism Works When you are blindfolded, you are compelled to ‘‘walk by ear”; that is, you are guided largely by two little balancing devices located im. your ears close to your hearing apparatus. er for each ear, are circular canals filled with liquid, and work like spirit Each has three parts adjusted for vertical, sidewise slanting positions of the head. The diagram above shows how the . balancing and hearing mechanisms send their messages to your brain oe These balancers, One Walls where 1 ASE this straigh’ “Tt is strate t canals « rium al dinaril} We alsc tor, for sarety which | his cra Whe bile, th back t Likewis floor a; you wh “Tov cator. mobile when it that yo eyes in when i seem t falling. fluid it been fl of you you sto forwar to give tion yo move | 0c h: his rev whirlec to the predict fore th motior minute the lef which spun t is, to t the rig stoppi The almost While When be fall to ove = ity had be

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dfold lance ylind- learn r our bules —two overn nd to | may spect. May, 1925 ical, sidewise, and slanting ya bod of ‘the head. When the canals eg bed, dizziness may result, as in red case of a child whirling about and oe ming “drunk” from the motion. It is not, though, the whirling motion + causes the dizziness, Doctor Hol- ple told me; it is the irregular succes- = of sudden starts and stops, that dis- nek the ear canals. In his laboratory is q chair, mounted like a dentist’s or bar- her’s chair, which can be rotated steadily by an electric motor. _ I got into the chair, and the motor ghirled it about with a speed that was al- most terrifying. I expected that the room would be reeling when the chair was brought to a stop. But it wasn’t. Walls and furniture remained exactly where they belonged. ASKED Doctor Holsopple just what I this test had to do with walking ight. a one of the means I use to demon- strate the importance of the semicircular canals of the ears in maintaining equilib- rium and direction,” he explained. “Or- dinarily, we gage our position by sight. We also use the sense of touch. An avia- tor, for example, uses the pressure of his safety belt or the sides of the chair in which he is seated to guide him in piloting his craft. When you ride in a train or an automo- bile, the pressure of the seat against your pack tells you that you are moving. Likewise, the pressure of the elevator floor against the soles of your feet tells you when an elevator is rising. = “Touch, though, is an uncertain indi- cator. Close your eyes when an auto- mobile or train is slowing down, and, when it finally stops, it will seem to you that you are going backward. Close your eyes in a rising elevator, and, when it slows down, it will seem to you that you are falling. This is because the fluid in the ear canals has been flowing in the direction of your motion, and, when you stop, it continues to press forward. The effect of this is to give you the same sensa- tion you experience when you move backward.” OCTOR HOLSOPPLE had me seat myself in his revolving chair again, and whirled me round and round to the right. True to the prediction he had made be- fore the test began, when the motion stopped, for a half- minute or more I felt that I was turning to the lett—the direction opposite to that in which I had been revolving. When he spun the chair with reverse motion—that 1s, to the left—the sensation of turning to the right persisted for a half-minute after stopping. Then he asked me tc lean forward almost until my chin touched my knees while he rotated the chair to the right. When I tried to straighten up, I seemed to be falling to the left. Had I endeavored to overcome this sensation, Doctor Hol- sopple told me, I should have fallen in reality in the direction in which the chair been whirling—namely, to the right. POPULAR SCIENCE MONTHLY Another test illustrated even more vividly the vital effect of the ear canals on the sense of direction. Doctor Holsopple asked me to touch a spot on a large card that he held before me as I sat in the chair. He told me he was going to whirl A Race without a Course Here is shown Svend Mannerheim, Swedish athlete, winning an odd sort of cross-country race held recently near Stockholm. The con- testants were required not only to run fast, but to find their way without compasses, markers, or other help from start to finish. How well do you think you could do in a race of that sort? Try the tests described in this article. You probably will be astonished to discover how crookedly you walk and how difficult it actually is for you to find your way about the chair about again, and that he wanted me to touch the spot on the card when the motion ceased. The chair revolved to the right. and when I at- tempted to touch the spot, I missed it 27 by almost two feet to the left-hand side. Try these tests yourself. A piano stool or a swivel chair can be used instead of the special chair of the psychologist’s laboratory. “Such tests,” Doctor Holsopple told me, “‘throw light on the effect that stimuli from the semicircular canals of the ears have in controlling our movements. From them science will learn how seri- ously a defect in the canals may influence our every-day behavior. “‘A simpler test is that of blindfolding a person and directing him to walk to a tree a few hundred yards away. The ground is level. A surveying instrument is used to measure the accuracy of the walker’s course. Some subjects, while they start out straight for the tree, quickly veer to the right or left. It is a strange thing that any one person, no matter how many times he tries the test, always will turn in the same direction. “TN SWEDEN they have an odd but highly interesting athletic game. It is in effect a cross-country race, but to win it a contestant must not only be the first to cross the finish line, but also must demonstrate a highly developed sense of direction and an ability to orientate him- self, for he must find his way through strange country with no guidance except his own instincts. The average man would make but a poor showing in a contest of that kind. Maybe you would like to see why this is so?” Once more I became a subject for ex- periment. My pathway, on each of several attempts to reach the tree, is in- dicated by the figures A, B, and C in the diagram on page 26. After several fail- ures, I tried to beat the game by leaning to the left. I had an idea that this would counterbalance my tendency to turn to the right, but it made no difference. Another person who tried the same test always moved to the left. ANOTHER phase of this prob- lem of balance and orienta- tion, Doctor Holsopple told me, is presented by antagonistic mus- cles. This means that certain groups move in away that exactly opposes the movements certain other groups are making at the same time, as when the biceps contract and the muscles of the back of the arm relax when the hand is brought to the shoulder. The eye muscles are another ex- ample. When the eyes turn in the head one set of muscles relax and the opposite set becomes tense. “Why does a person walk crooked?” “That’s what we want to know,” this psychologist told me. “The causes are complicated. Doubtless some of them are muscular. In the legs and trunk, for example, one muscle may be pulling harder than its antagonist. “Perhaps a contributory cause may lie in chance, such as the swaying of the body. A deviation of this nature may not be corrected by the semicircular canals, and consequently it influences the walker’s direction. The chance occur- rence may take the form of a sharp gust of wind, or of some trivial influence that swings the person off balance.”

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POPULAR SCIENCE MONTHLY

The Digesting Plant. By Newton Burke announcement that science had produced an effective process by which the waste straw of food crops, such as wheat, barley, oats, corn, and rice, may be utilized as a substitute for the wood pulp from which 90 per cent of | Pee Europe recently came the the world’s paper now is made. The process has been developed by M. De Vains, a French inventor, and depends upon a method of eliminating the hard brittleness which previously had made impossible the use of straw Here the straw fibers are converted into pulp—the first <tage in the new method of manufacturing of paper fibers in the manufacture of printing and Fe% writing paper. The De Vains process

has been installed successfully in a dozen _ the world, the forests eventually will prove paper and pulp mills in European coun- insufficient to supply the demand for tries, and plans are now under way, it is wood pulp for paper manufacturers. Just said, to establish a large experimental how terrific is this demand is shown by plant in Canada, where the great wheat the fact that the United States alone crop will provide an abundance of raw _ requires 7,500,000 tons of paper every material. year. Fifty years ago this country’s Canadian wheat straw, itis announced, annual consumption of paper was only already has been employed effectively in 500,000 tons; in another 50 years, it is the manufacture of paper by means of predicted, it will be 20,000,000. the new process in Europe. The paper Because of this apparently inevitable produced in the milis where the process famine, paper manufacturers have sought has been installed is said to be excellent in quality, a special bleaching method producing a pure white paper when desired. Paper from straw, of course, is nothing new. Straw paper was made in this country a half- century ago; also in Europe. Straw is used also in the manu- facture of strawboard and sev- eral types of cheap wrapping paper. But paper made from straw fibers, matching in quality the paper manufactured from wood pulp, is a distinct novelty, and a successful process that makes it possible is bound to prove of tremendous significance, not only to the paper industry, but from an economic stand- point. Foresters and economists long have maintained that, despite efforts to replant woodlands of

High-Grade Paper Made from Waste Straw Threatened Famine May Be Prevented by a New Process of Salvaging Crop Rubbish The Paper Factory Two interior views of one of the European factories where paper of high quality is being many. factured from straw by the new De Vains pro. cess. At the left is the bleaching plant where the straw pulp is made snowy white. The only chemicals used ‘are com. mon salt and lime. Be- low is a battery. of huge rollers that transforms the pulp into paper sheets

for a new source of paper-making mate rial. Crop straw, most of which is burned as waste, naturally was considered, but the hardness and brittleness of the result- ing pulp made it unsatisfactory.

‘THE luxuriant vegetable growth of the tropics likewise was considered; but, though tropical grasses, bamboo, and sim- ilar vegetable products were found suit- able for paper manufacture, the difficulty of transporting chemicals and fuel to the tropics made this virtually in-

Where Straw Is Burned as Waste exhaustible source of pulp of doubtful value to the paper-using world. Ten years ago De Vains at- tacked the problem of develop- ing a process whereby straw might be used in paper manu- facture. Advices from Europe indicate that he has solved the problem. The only chemicals employed in his process are common salt and lime. Soda and chlorine, which are necessary for the separation of the paper-making fiber, are produced from the salt through his process by electrolysis. Im genious machinery and an ir genious adaptation of well- ¢ typical Canadian harvest scene. It is estimated that chemical reactions peng: , the straw burned as waste after the harvest every year is suffi- i r t eir : soda and chlorine, after cient to produce 50,000,000 tons of paper, or more than th . ’ ‘ne a ag Oe ag pane at work is done, to recombine a requirements of the world, also that straw from a field 10 miles square would keep a paperemanufacturing mill busy for a year salt, which may be used agail.

May, wt

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POPULAR SCIENCE MONTHLY May, 1925 29 Do We Need More Ships like These? Aviation Plays Important Role in New British Naval Designs The “mother ship,” with landing deck for airplanes and mooring-mast for the anchorage of great dirigibles already has demonstrated its practicability as an emergency air base at sea With funnel, mast, and bridge to star- board, providing a wide landing-field on the upper deck, the British aircraft- carrier Hermes can accommo- date 20 planes 2 igre great sham battle staged by the American Navy this spring off the coast of Lower California to test the efficiency of the modern warship in de- fense against attacking aircraft has brought to a head the lively controversy over the question: Is the airplane making the battleship obsolete as a weapon of naval warfare? Great Britain’s most recent answers to that question are found in these new designs of aircraft-carrying war vessels A naval possibility of the future, designed by Sir George Thurs- ton, is the high-speed battleship fitted to carry aircraft and pro- vided with maximum protection against enemy aerial bombs The landing- deck of the British air- craft-carrier Argus isclear of all obstruc- tions, the smoke being emitted aft How the two new British battleships, Nelson and Rodney, may appear when completed under the Washington Armament Treaty. It is reported that their armament will include nine 16-inch guns, making them the most powerful battleships ae ie Samii aes ne ome na at uO nme eS na fan tte # = ve nin hs 6 ES TS SET ey SE SI 1

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' POPULAR SCIENCE MONTHLY May, 1935 Phose Who Carry Our Mail promane > The World’s Highest Beacon This 5,000,000-candlepower lighthouse of the U. S. Air Mail, which is the highest in the world, surmounts Sher- man Hill, itself 8600 feet above sea level, on the top of the 14 Rocky Mountains between Cheyenne and Laramie, Wyo. By Norman C. McLoud IR-MAIL pilots do more than carry A the mails. Each day of their lives opens for them a new chapter of thrill and. adventure. Constantly, day and night, 20 of the 70 fliers who compose this branch of the postal service are on the wing somewhere between New York and San Francisco, and just as constantly danger and excitement lurk in their path. Whence peril will spring they cannot guess. It may come while they sweep along in apparent security over the wide, level plains of the West, or it may appear as they fight their way through im- penetrable fog amid the rugged heights of the Rocky Mountains. The blizzards of winter, the fierce lightning of the summer storms,. the failure of their planes, either in mechanism or structure—any of these, or a thousand other causes, may bring the pilot face to face with death. Indeed, it is a lucky one among these aerial majl carriers who has not suffered the fiercest hardships and gravest dangers many times in the few brief months since the establishment of mail delivery. between oceans in less than a day and a half. San Francisco. unknown perils. The air mail aims to bridge the distance between New York and San Francisco in 34 hours or less. How well this schedule has been maintained by these hardy and venture- some aerial postmen is shown by recently compiled records of the Post Office Department. In two years and nine months the air mail has cov- ered 50,000,000 miles with 157,000,000 letters weighing 4,000,000 pounds. There are stops on the transcontinental route, yet in nine trips out of 10 planes have been exactly on time both at intermedi- ate stations and at termi- nals. The poorest time westbound was 55 hours and 40 minutes, or more than 30 hours better than train schedules. East- bound the slowest trip was 57 hours and 39 min- utes, or more than a day and night better than railway mails. So successful has been the transcontinental air mail, in fact, that the Post Office Department has been stimulated to ex- tend the service. Within a few weeks, it is an- nounced, there will be *— started a double-track service between New Ycrk and Chicago, with a flying time of between eight and nine hours, and overnight delivery of mail between the cities. Here, in his flying togs, is Pilot Paul P. Scott, whose recent adventures in carrying the mail form one of the most thrilling of modern romances. through a series of hardships that began a few weeks ago, when his plane crashed against the side of a mountain A Narrative of the T. hralling Adventures of Postal Pilots A 3000-Mile Path of Adventure The route of Uncle Sam’s Air Mail, bridging the United States from New York to Every night and every day of the year a score of fliers are on the wing somewhere along this pathway, plunging through storm and fog, braving And although there are 14 stops, the mail-planes have been on time in nine trips out of 10, covering 50,000,000 miles in 33 months with 157,000,000 letters The tentative schedule provides for plans to leave New York and Chicago each night at 9.30 and to arrive at the other terminus at 5.30 the following morning. It is not contemplated to handle other than New York and Chi- cago mail, except of course such mail matter as ordinarily is relayed between the two cities. Three stops have been provided—at Bellefonte, Pa., and Cleve- Dauntless Courier of the Sky He has battled his way land ar Clevelat the othe the or drop off Recer Scott st the ends mail ser schedule into a} began official r ment d passed b “a circ Scott with m Dense { The firs crashed. force. waking | on top « incident chronicle LE] he » and mis was vel Pass. / with th to north “T he mountai: small h the clouc regular | saddle is cleared : each side range is “No I visible. hole, wit to what when th banked

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May, 1925 in the Air d Bryan, Ohio. The stop at We ad will be made to change planes, the other two for refueling. Eventually the original plan may be modified. to drop off mail at Cleveland. — Recent experiences of Pilot Paul P. Scott serve as conspicuous examples of the ends to which the heroes of the aerial mail service go in order to maintain their schedules. When this navigator bumped into a mountain a few weeks ago, he began a series of adventures that the official records of the Post Office Depart- ment describe as “hardships not sur- by any experiences of the world fliers who circled the globe in army airplanes.” Scott left Salt Lake City flying-field with mails for Reno and the West. Dense fog hid everything from sight. The first thing the pilot knew he had crashed into a mountain with terrific force. The next thing he knew he was waking up in the snow, with his machine on top of him. His own report on the incident supplies a graphic and thrilling chronicle: “T LEFT Salt Lake at 12.42 p.M.,” he writes, ‘‘and encountered snow and mist from the first. The visibility was very poor as far as Silver Zine Pass. At Shafter the weather cleared with the exception of ground fogbanks to northwest and south. “[ headed south to go around the mountain range, when I noticed a small hole between the fogbank and the clouds, through the saddle-pass on the regular course. The lowest part of the saddle is about 300 feet wide, and can be cleared at an altitude of 7200 feet. On each side of the saddle the altitude of the range is about 8500 feet. “No part of the mountain range was visible. I had proceeded through the hole, with altimeter registering 7800 feet, to what I thought was halfway through, when the hole closed up in front. Then I banked the plane, and was turning to POPULAR SCIENCE MONTHLY Wind Indicator Emergency landing-fields are equipped with this combined beacon and weather vane. It casts a guiding beam that can be seen for miles. The illumi- nated T below the beacon swings around, telling the air-mail pilot, many feet above, the direction of the wind at his landing place come out when the fog closed in behind me, the visibility now being not more than 20 feet. “No sooner had I leveled the plane off and started climbing than I saw I was scraping the tops of cedar trees. “I pulled back the throttle and the stick, together, and crashed on the slope of the saddle at about 8200 feet. “When I came to, my face was buried in the snow and I was groping for the switches with my right hand. My left arm and hand felt numb and useless. I could not locate the switches, so I un- 31 fastened my belt and dug snow enough to pull myself from under, with the aid of a convenient cedar limb. The machine was complete.y ‘washed out.’ ”’ At this point Scott showed himself an observer as well as a pilot. “Then I- began noticing things,” he continues. “I noticed that my left shoulder was out of place, and that my arm was freezing rapidly; that I had cigarettes and matches; that I had left my gun in Salt Lake; that there was a heavy fog, with no sun visible to get A Floating Flare The night-flying plane car- ries a brace of flares for use in case of forced landing. When one of the flares is lighted and dropped, it il- luminates the countryside for half a mile in every direc- tion, enabling the pilot to select a safe landing-place. Notice how the flare floats, suspended from a parachute. It lasts for about 10 minutes Remarkable nighttime view of the U. S. Air-Mail Field at Iowa City, Ia., showing a mail-plane making a landing under the beam of a Powerful beacon. Brilliant illumination of the field virtually turns night into day, assuring the safety of the pilot and his precious cargo

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New Mail-Plane In 100,000 miles of test flying between Chicago and Cheyenne, this new type of mail-plane is said to have demonstrated su- perior speed, ability to make slower landings, and lower operating costs. It is reported to be almost foolproof against diastrous tail spins or nose dives bearings; and that I was extremely lucky to be able to notice anything at all.” Seott’s luck continued to hold. After his miraculous escape, he started down the mountain. The snow was deep and walking was difficult. “In a short time,” he says. ‘‘I slipped on some shale rock, striking my left shoulder, and knocking it back into place. Then I rubbed my left arm and hand with snow until they thawed.” The flyer walked to the nearest railway tracks, flagged a train, wired head- quarters, and returned to Salt Lake. HE marvel of Scott’s escape from death was emphasized by the dis- coveries made by the relief expedition that went in search of him before his tele- gram reached civilization. POPULAR SCIENCE MONTHLY Mechanical Aids for the Air Pilot Powerful “headlights” on the lower wing help to guide the air-mail pilot in making night landings. Note how the lamp at left is streamlined. At the right is a view of the instrument board in the pilot’s cockpit. In addi- tion to the usual controls there is radio equipment with which the pilot re- ceives the weather reports ‘*Our schedules are approximately four hours longer than our experimental flights indicated to be practical,’”’ Colonel Hen- derson said. ‘‘Pilots no longer fear fly- ing at night. It is taken for granted that night flying is here and here to stay. New-Yorkers no longer are astounded when they get letters that left San Francisco early the day before. I am confident that this transcontinental ser- vice is a fixture. San Francisco is per- manently moved up to within 34 hours of New York, from the viewpoint of the Post Office Department.”’ Pilot Wesley L. Smith confirms the statement that the men of themail-planes no longer fear flying at night. Smith is Giant London-Paris Plane the man who took off the first plane when the new service was established on July 1; 1924. He is a vocal student and flying is his means of paying for his education, During the war he was a lieutenant in the Army Air Service. “Night flying is not a bit more hazard- ous than flight in broad daylight,” ‘ac cording to Smith, “‘if the night is clear and the moon is doing its full duty. Of course, it cannot be denied that hazy nights are undesirable, but the thing ] fear most is day flying in a severe storm, ‘‘Even the storms are not as bad.as they might be. In summer the average storm is less than 10 miles in width, and a pilot may fly above it, or he may pass through it in five minutes. Bucking a storm, however, is filled with more thrills than Field - Manager Bernard Main and Mechanic James L. Farrow conducted the search in an_ airplane. With them was Mechanic F. E. Barnard, at the con- trol stick. The relief party itself became stranded in the mountains, through en- gi failure, two miles from a railroad, 10 miles from a telephone, and in a howling blizzard with a 650-mile wind. The searchers had only three sandwiches and three tins of sardines, and hunger and exhaustion crept upon them before they found the wreck, described by them as the worst they ever saw. Despite such thrilling episodes as that in which Seott figured, there is no hysteria in the service, ac- cording to Col. Paul Hen- derson, second assistant postmaster-general, who has charge of the air mails. and Paris. Napier that delivers 1000 horsepower, One of the giant new planes used in carrying passengers and mail between London It is driven by the largest single engine in the world, a 16-cylinder Compare size of the plane with the men normal night flying over the lighted airway ex- tending from Cleveland to Cheyenne. My own worst experience was in daylight, when I was forced down in the Alleghany Mountains and landed in the top of a group of trees. ‘All a pilot has to do, day or night, is to keep his head. In case of mie hap he always can save himself by jumping, his parachute, or pe he can reach sa shutting off -his m and gliding. 1 skilled pilot gliding =m difficult. “One of the w mies of the airplane dense fog, in ¥ pilot cannot tell 1 he is approaching a mountal or other obstacle. Haj an instrument is bell fected that will enabe him to feel his way through a fog, and when (Continued on page 125) © Acrofiims, Ltd.

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e when July 1, lying is cation. t in the t,” ‘ac. ear and y. Of t thing I storm, as they e storm h, and ne may 1inutes. s filled 3 than 1g over ay ex- eveland ly own May, 1925 ff You Were T'rapped in a Burning Building— ~ You, Like Hundreds “of Others, Might Owe “Your Safety to the ‘Science and Daring of the Rescue Squad aS wanes? aetis i ea at + YP, By Ama Barker BOUT four o’clock one morning 10 years ago a policeman, patrolling a congested factory district in lower New York, saw smoke pouring from the cellar of a four-story loft building. The chief of the fire department re- sponded to the subsequent alarm, to- gether with four engine companies. When the basement doors were burst open, thick, black smoke choked the en- trance. The chief went to a call-box and in Morse eode sent: 2—pause—3— pause — 2 — pause — then the box number 1, the fire- department rescue com- pany’s special call. A few minutes later six men in oxygen helmets plunged into the cellar. They groped their way through the stifling smoke and located the seat of the fre. Returning, they got two lines of hose into action. Fifteen minutes later the-fire was out. POPULAR SCIENCE MONTHLY Answering a Call of Peril New York City’s Rescue-Company No. 1 speed- ing to a blaze in one of the most dangerous fire Had the firemen not been protected Cote, Se nae Se comgnay wanes 0 with oxygen helmets, had they not been able to get at the fire while it was still medal for distinguished bravery. The upper picture shows a member of the rescue squad bringing out a comrade overcome by gas fumes small, there is no telling what the loss of ; life and property in that crowded district of the New York Fire Department, be- might have been. cause it marked the beginning in that city The laconic account of the work done of specialized rescue work that has saved dy the rescue squad at that particular fire hundreds of lives and millions of dollars. is a significant item on the official report It was New York’s first application of The pulmotor, an important part of the rescue-squad’s equipment, has saved many a fireman Overcome by smoke or fumes, In Chicago last year 260 persons were saved by this means -fire-quenching chemicals for use where Talking to His Men The commanding officer of the rescue company, equipped with portable telephone appa- ratus, receives messages from his men reporting conditions in a gas-filled cellar. The men all wear telephone helmets Photos © Keystone scientific apparatus for this particular kind of work. But, allowing for dif- ference as to time and place, this memorandum of service might have been taken from fire-department records of any one of a number of cities where, in the last few years, picked squads of firemen have been assigned to man special scien- tific equipment, assisting the regular engine and hook-and-ladder companies. Perhaps the first rescue squad attached to a fire department in this country was organized in Detroit in 1908. This com- pany’s special equipment was limited to a single life net, but it blazed the way for the highly specialized work now being carried on in most large cities and many small ones. Gas masks were used by San Francisco firemen as early as 1909 and Chicago had three auxiliary squads for rescue work in 1909. However, it re- mained for the New York Fire Depart- ment to equip the first rescue company with dependable oxygen masks and to equip a company truck with a variety of special scientific and mechanical appara- tus that was useful not only in fire-rescue work but in almost any emergency where lives might be in peril. AND to-day fire-department officials © all over the country are constantly on the lookout for new inventions and improved apparatus that may be utilized by the men whose lives are devoted to the saving of human beings from death in fire and smoke. Almost every day science offers some new aid in this thrilling and useful work. Oxygen helmets, pulmotors, . special oa a a PT TEES pan ca a es

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34 water would be ineffective or dangerous, acetylene torches for cutting away metal barriers, unusual types of crowbars and other wrecking tools for quick destruction of impeding doors and partitions—such apparatus is now as common almost in the equipment of the rescue firemen as are hose and water in that of the ordinary fire-fighter. To such apparatus and to the skill and bravery of those who man it, thousands owe their lives. How much the appalling toll in lives that fire exacts in this country every year might have been reduced by a wider use of rescue equipment it is impossible to estimate. Fire rescue is highly specialized work, and can be performed properly only by picked men after thorough training. One reason for this is that special skill is re- quired for the operation of the compli- cated rescue apparatus, another that the apparatus requires special care if it is to be kept in condition for immediate use. ND so firemen, as a preliminary to joining rescue companies, go through weeks of stiff training -with gas masks, acetylene torches and many kinds of forcible entrance tools. Besides learning how to use all this equipment, they are taught also how to take care of it, to detect signs of trouble with the apparatus, and to make repairs. The oxygen helmet used by rescue firemen bears slight resemblance to the gas mask of the trenches. The latter owed their efficiency to chemical filters that absorbed the poison gases, which, of course, were usually well diluted with air when they reached the soldiers. Masks of this type had been tried out by various fire departments before the establishment of the first rescue squad, but were found virtually no protection against thick POPULAR SCIENCE MONTHLY smoke, ammonia, or other chemical fumes frequently encountered iin fires in indus- trial establishments. The helmet in use today is of a type similar to that used in mine-rescue work. It is equipped with an oxygen tank de- signed to give the wearer a supply of pure oxygen for an hour. An indicator regis- ters the amount of oxygen consumed, and even when this registers zero, there is still enough oxygen in the tank for 20 minutes’ additional use. BEFORE the adoption of the oxygen helmet, Chicago firemen were called to a blaze in a meat-packing house. An ammonia tank on the third floor, part of the refrigeration system, sprang a leak, an explosion followed, and several em- ployees were overcome. Firemen from the first truck company that reached the fire entered the building wearing the old- style filtration masks and endeavored to reach the third floor. The ammonia fumes, however, drove them back, and before they could reach the street, three of them were overcome. It was with the greatest difficulty that the employees—among them 12 women— were taken on ladders from the third floor, and one woman was dangerously injured when she jumped from a window. A Thrilling Moment—Shooting a life-line up, as a last resort, to a couple trapped on the roof of a burning building. They are seen above with the trope that brings them safety. Many rescues have been made in this way rescue squad. May, 1995 ' All - these persons could be led to saf readily by Chicago rescue present day. a the A vivid instance of the value of equipment in combatting difficult was given to the writer by Lieut. Thom: F. Kilbride, senior officer of New York City’s Rescue Squad, and the only i viving member of the first rescue squad formed in that city. This is q story of fire in a submarine lying at a pier in the Brooklyn Navy Yard, caused by a explosion in the aft battery compartment that injured several men. “When we got there a few of the in- jured had been rescued by Brooklyn fire. men,” said Lieutenant Kilbride. “By the burning insulation on electric wiring and repeated explosions made the fumes; and smoke so dense and the heat 80 terrible that men without masks couldn’t get any farther than the battery platform without being overcome. “THE naval officers said the explosions were caused by chlorine gas coming in contact with electric wires charged with 600 volts. This gas had been formed hy the mixture of sulphuric acid and galt water used in the wet batteries. **Red-hot electric wires, caused by short-circuiting and burning insulation led through the magazines, loaded with smokeless powder, TNT, and a lot of gun- cotton. In addition, the boat was carry- ing eight torpedoes of the largest type with their war heads on, ready for action. The steel jackets were so hot you couldn't touch them with your bare hands! “The only way we could get down to the fire was through an opening in the hull, about 22 inches in diameter. And once inside we had to crawl about and fight the fire with small hand extin- guishers. Salt water could not be used to flood the compartments, because its action on the electric batteries would have caused more explosions. Fresh water was used to dilute the batteries, but the fire had to be fought mainly with hand, (Continued on page 128) Freeing a Victim—The acetylene torch is an invaluable weapon of the In two or three minutes it can cut through heavy iron bars that imprison fire victims, saving precious time in rescue

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1 the ment e in- 6 But iting umes it so Idn’t ‘form sions ming | with ed by 1 salt lation By Arthur A. Stuart world’s largest cities to solve its rapid-transit problems high in the ait. Recent reports from the French capital indicate that actual construction work soon may begin on a remarkable high speed aero-railway, along which pro- peller-driven cars suspended from an over- head monorail will travel 60 miles an hour, carrying thousands of commuters between Paris and the suburb of St. Denis. “Designs for the airway have been com- pleted, examined by expert engineers, and found to be practicable, it is reported. The inventor, Monsieur Francis Laur, a well-known French engineer and former juty of the District of Paris, has laid his entire scheme before the Prefect of Police, and now is waiting only for a con- cession on the line to begin work. During the last year inventors in America and Europe have been at work on the idea of aerial railways to supplant the crowded commuters’ trains, jammed subways, slow moving surface cars, blockaded taxicabs, and buses that have brought the problems of traffic congestion to a critical stage in almost every large city. One of the ingenious systems de- vised—the Felts suspended monorail car proposed for Los Angeles, Calif.—was described in PopULAR SCIENCE MONTHLY in November, 1923. "Phe proposed ‘car of Monsieur Laur ‘differ from the Felts invention in the fact that it would be virtually a ee tiven airship suspended from Proves bids fair to be the first of the POPULAR SCIENCE MONTHLY Riding to Work in Propeller-Driven Sky-Car The design of the proposed Paris-St. Denis commuters’ airway car, showing monorail suspension and airplane propeller that would drive it at 60 miles an hour. Both ends would be tapered like an airship A Mile a Minute by Aero-Railway How Paris Plans to Solve Suburban Transit Problems and running along a rail. Its body, tapering off at both ends like a dirigible, would be built of duralumin, extremely light. While it would be capable of carrying from 60 to 100 passengers, the entire car, including motor equipment, would weigh only five tons. Present plans call for a car 40 feet long, seven feet wide, and seven feet high, driven by a nine-foot propeller. The car would be suspended from overhead carriages, each with two wheels in tandem, run- ning on the monorail. It would be equipped at one end with a regu- lar heavy-duty airplane propeller driven by a gaso- line or electric motor, and at the other end a control cab. The propeller would be of the new metallic re- versible type, turning at 2000 revolutions a minute. Thus, the car could be run in either direction and would not have to be turned around on the tracks. Dur- ing rush hours an extra car or two could be hooked up to the propeller car, forming a train. The track would be in the form of an inverse double parabolic arch suspension bridge holding up the rails, each suspen- sion being about 480 feet long. Suspen- sion cables would be strung on high steel towers guyed longitudinally and at right angles to the track to keep all motion from wind pressure at a minimum. Front View Notice how the car is suspended from wheels running on single rail One of the chief. advantages claimed for the proposed sky railway, aside:from that of providing relief from traffie con- gestion, would be its economy of construc- tion and operation. The initial financial outlay obviously would be small compared with the expense of digging subway lines or erecting steel elevated structures, or even of establishing extensive new lines. of motor-buses. The economy of: transport, ac- cording to the inventor, would reduce the cost of tickets from St. Denis to Paris to about one-third _ of what even the street- railway companies now are charging. The fares to be charged for the single trip of about 10 miles from the northern section of Paris to St. Denis, according to the present plans, would be about three cents. Express cars, not stopping at intermediate points,. would make the complete round trip in a little more than half an hour. It is estimated that the line could handle more than 2,000,000 passengers a year. If the proposed aerial line proves com- mercially successful, it will be followed by other similar lines connecting the heart of the city with its suburbs. Monsieur Laur, who is 84 years old, has spent the past 11 years working on his aero-car. An artist’s first idea of the airline railroad, drawn several years ago. “The track would be built like a suspension bridge

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POPULAR SCIENCE MONTHLY Light Baths Fight Tuberculosis Tuberculosis patients in the Robroyston Hospital at Glasgow, Sco now are treated with baths of ultra-violet light produced by the artificial sunlight apparatus shown here. By building up the bones and improving the quality of the blood, ultra-violet light is Prov- ing an effective weapon against one of the most dreaded of all diseases Magic Cures Found in Sunshine Discoveries of Amazing Germ-Killing and Food-Giving Power of Ultra-Violet Light Promise Better Health for Everybody from the Amazon remarked that he could not figure out why more savages did not die. Careless of infection, they treated their most appalling wounds, he said, simply by lying in the sun. Experiments made at the U. S. Bureau of Standards recently gave an explana- tion. Bacteria found in sewage were exposed to ultra-violet light, a part of sunlight. Literally in a flash, in an ex- posure of less than a second, the bacteria were killed. Sunshine—the mysterious cure used by the savages of the Amazon to sterilize their wounds—was found by these experiments to be the most powerful non-chemical germicide known! Accurate measurement of the tremend- ous germ-killing power of ultra-violet light adds one more proof of its value. More than 120 years ago ultra-violet light was discovered, but only within the last 10 years have its varied powers begun to be appreciated. Today it is being used, not only to fight disease, but to hasten growth of crops, produce more eggs, test paints and fabrics, season lumber, and sterilize water. Its utilization is one of the amazing accomplishments of our age. Ultra-violet light, is not to be confused with the so-called “‘violet rays’’ that we see the salesman at the corner drug-store “demonstrating” with glass tubes of vari- ous shapes. These“violet rays’ are merely the violet light that a high-frequency electric current produces when it is passed through a vacuum. Ultra-violet light is a colorless, in- A EXPLORER returning recently By G. B. Seybold visible part of sunlight. We know that sunlight passing through a prism breaks up into its spectrum—trays of red, orange, yellow, green, blue, indigo, and violet, each color having its own wave length. - But besides these, at each end of the spectrum, sunlight contains waves respec- tively too long and too short to be seen by the humaneye. — Beyond violet, made up of the shortest waves we can see, are much shorter waves. Although these have no effect on the retina, they will darken a photographic plate. These waves are ultra-violst light. By means of special instruments that con- vert the effect. of the waves on photo- graphic plates into electricity, or record their heat, these minute wave lengths have been measured. They are so short that their length cannot be computed in ordinary terms, so the Angstrom unit is used. An Angstrom unit measures ap- proximately 1/250,000,000 of an inch. That is to say, it would take 10,000,000 of them to equal the diameter of a human hair of average thickness. The waves of ultra-violet light vary in length from those just too short to be seen, 3900 Angstrom units long, to the shortest —1000 Angstrom units long. Beyond the ultra-violet region are the extremely short wave lengths known as X-rays. N THE Bureau of Standards test it was found that the shorter ultra-violet waves had the more pronounced action in killing bacteria, but longer ones were effective with longer exposure and when applied with greater intensity. Science, however, has learned to produce arti- ficially ultra-violet wave lengths shorter than any of those in sunshine that reach the earth. Ultra-violet light is emitted whenever an electric current is broken and the spark made to leap across a gap in an are. Arc lamps used in motion-picture studios, for example, give off a large amount of ultra-violet light. The lamp most com- monly used by physicians in ultra-violet treatments has poles of merzury in a quartz tube. UARTZ is used because ultra-violet light will not pass through glass. In winter our closed windows shut out the germ-killing part of sunlight. POPULAR SCIENCE MONTHLY told recently that a way has been found to make clear fused quartz in commercial quantities at a reasonable cost. Does this point to a time when we need no longer deprive our- selves of the help nature offers us daily? With quartz windows in our houses it would be possible to live indoors as healthfully as out-of-doors in the sun- shine. It is the longer ultra-violet waves that cause sunburn. In the concentrated ultra-violet light produced artificially the skin of any one under treatment is burn very rapidly. In two hours under ultra- violet light in a laboratory a person may’ acquire a coat of tan equal to the total result of a full summer’s exposure at the seashore. In ultra-violet light baths the corpus the m: theref« necess provid fightin Dr. ultra-1 perime prever he say’ ; these « Tube unelo ultra thus healis

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ay, 1995 ight Hille iERSEES * iseases he y Science, ice arti- ; shorter at reach. rhenever and the n an are. studios, 10unt, of st com- ra-violet ry in a ra-violet lass. In out the POPULAR r that a ar fused es at a nt to a rive our- is daily? ouses it loors as the sun- ves that entrated ially the s burned er ultra- son may: the total re at the aths the flay, 1925 must be protected by goggles of any colored glass but quartz. The first spectacular use of the sun as a doctor was in Switzerland, where physi- cured children of tuberculosis by -.¢ them play naked, out-of-doors in the snow. Snow reflects’ ultra-violet light almost completely, thus giving the tents a double dose. of the light— direct and reflected. ; Perhaps the most amazing of all things accomplished by the use of ultra-violet light is the curing of rickets. In this disease the. bones fail to develop properly onaceount of a deficiency of calcium and anhorus in the body. Other diseases que to this same deficiency are hay fever, asthma and scurvy. Ultra-violet light is being used in the treatment of all of these. After the cause of rickets’ was dis- covered, patients were fed calcium and ssphorus, but without favorable re- sults; for the body could utilize only five » cent of the chemicals. Baths in ultra-violet light, however, in some way not yet fully understood, were found to cause the body to absorb 60 per cent of the salts introduced from without. eee OLET light in the treatment of rickets does not get to the bones, put works in its tonic effects through the blood. It helps in the battle against tuberculosis by improving the quality of the blood. Red corpuscles, the food carriers of the blood system, and white corpuscles that fight germs, are made in the marrow of bones. Ultra-violet light, therefore, by enabling bone to take-up necessary building materials, indirectly provides for more troops of working and fighting corpuscles. Dr. Percy Hall, an English specialist in ultra-violet light treatment, has been ex- perimenting with the use of the light in preventing influenza and dyspepsia, which he says is a form of influenza. Attacks of _ these diseases usually come in the winter Treated by Snow and Sun Tuberculosis sufferers in Switzerland tramp Unclothed in the dazzling snow. Snow reflects itra-violet-rays. of sunlight-almost ‘completely, ~ thus giving the patients a double dose of the light—both direct and ‘reflected light POPULAR SCIENCE MONTHLY when our bodies have little defen- sive power. By in- creasing the num- ber of red blood corpuscles in the blood and the per- centage of hemo- globin in these corpuscles by ultra-violet light, we can build up our resistance to disease, declares Doctor Hall. He predicts a_ time when we shall take light baths every fall to prepare our bodies against the attacks of winter. Itis claimed that ultra-violet light will grow hair in all cases except when it has died gradu- ally on account of old age. Sun- burning the scalp with . ultra-violet light causes a rush of blood to the re- gion, bringing with it the food that the starved hair roots require. dry your hair in the sunshine, or go bare- headed out of doors, nature gives you a free beauty treatment. Ultra-violet light penetrates the skin to a depth of only one-tenth of an inch. By pressing a small water-cooled lamp close to the skin, it is possible to make the light penetrate as far as one-fourth inch. This is seldom done, since the powerful light destroys the surface of the skin at the same time as it kills the germs beneath. boils,. and carbuncles. curved quartz tubes it is possible to get at germs in infected parts that are inac- cessible; for example, in treating ton- By means of Bacteria Killed in Less than a Second If you “37 Dr. W. W. Coblentz of the U. S. Bureau of Standards, with the new apparatus for measuring the germ-killing properties of ultra-violet light. Exposed to the light, bacteria found in sewage were killed in less than a second, thus explaining the power of ultra-violet rays to cure disease thing, while substances having no value in treating rickets had no effect on the plate. This explained the mystery of why Eskimo children rarely suffer from rickets. on account of the lack Eskimo children, who live ness lasts for months, were While thousands of children suffer from the disease in foggy climates, particularly during the winter months, supposedly of sunlight, where dark- not: affected. Now it seems that they maintain their health through their diet, most of which contains large quantities of various fish As a germ killer, ultra-violet light is oils. proving effective in treating skin diseases, OCTOR A. F. HESS, of New York, has announced that he ‘has dis- covered a method of making cottonseed oil and linseed oil absorb ultra-violet sillitis, pyorrhea, abscesses, ringworms, light. This is of great importance, for or by introducing a water-cooled lamp into the inside of bones, in treatment of Also it is beginning to be used to replace chemical germicides such as iodine, which sterilizes only the surface and has no penetrating power. That ultra-violet light can be intro- duced internally is a recent and important development. For many years children have been fed cod-liver oil to prevent them from becoming bow-legged, an effect of rickets. Ultra-violet light treat- ment was found to be similarly effective in bone tuberculosis. fighting rickets. Dr. I. Newton Kugelmass and Dr. Irvin McQuarrie of the Yale Medical School recently announced the result of an investigation of the relation between the Cod-liver oil cures rickets, they said, because it actually generates ultra-violet light in the intes- tines. When oxygen was added to the oil (as it would be in the natural process of digestion), the oil. blackened a _ photo- graphic plate, screened with quartz, but had: no effect when the plate was screened with glass.. Egg yolk and sperm oil, also helpful in the cure of rickets, did the same oil and the light. America are experimenting while the supply of cod-liver oil and sperm oil in the world is limited, the supply of vegetable oils is not. Doctor Hess also found that lettuce, which ordinarily has no effect on rickets, and wheat grown in the dark, after an exposure of two minutes to ultra-violet light, became active in preventing weakness in bone. Scientists in other countries as well as to cause food to absorb ultra-violet light. With a method of ‘‘eating sunshine,” they be- lieve, we shall have found one of the greatest preventives of disease the world has ever known. have been found also. L. F. Payne of Manhattan While startling discoveries have been made showing the effect of ultra-violet light on our bodies, commercial uses for it Poultry pro- ducers will undoubtedly benefit from an experiment made by Drs. J.S. Hughes and , Kan. Like bone-making, egg-laying requires-utiliza- tion of lime. Exposing hens once a day for 10 minutes to an électric-lamp source of ultra-violet light caused them‘'to ‘lay four times as many eggs as those that did (Continued on page 130)

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Startling Test to NE of the most startling scientific tests ever conceived soon will be made not far from Fresno, Calif., when the Engineering Foundation, the joint research organization of the Ameri- can Societies of Civil, Mining, Metallurgical, Mechanical and Electri- cal Engineers, will con- struct a full size arch dam for the sole purpose of causing it to burst under pressure of the water it impounds. The object of the test is to determine the weak- est parts of dams of this type of construction and their manner of failure, for the. purpose of ascer- taining how to build dams of maximum satety, yet with minimum thin- ness of construction and consequent economy of material. The experi- ment will cost $100,000. Arches of stone or concrete are familiar sights in bridges. Relatively few per- sons, though, have seen arches stood on end to back up the water of a stream so as to create an artificial lake or reservoir for power development, water supply, irri- gating arid lands, or regulating floods. Dams of this type, however, have been constructed for more than 300 years. The oldest known, the Almanza, was built in Spain before 1586 and is standing today. The Roosevelt Dam in Arizona is an outstanding example of the curved dam built in modern times. Some of these dams are low, but a few exceed 200 feet in height above the stream bed. Some are very thick, others extremely thin. Very few have failed, and they because of faults of the founda- The Roosevelt Dam on Salt River, Ariz., built in 1911, is an outstanding example of the curved dam built in modern times. It was built by the U. S. Government, and is 280 feet high, 1125 feet long, and has storage capacity of 513 billion gallons Engineers Will Burst Will It Hold? This diagram shows the dar- ingly thin proportions of the proposed experimental dam. It is only half as thick as the four-foot Upper Otay Dam POPULAR SCIENCE MONTHLY The Upper Otay Dam near San Diego, Calif,, four feet thick at the top; yet it withstood a severe flood in 1916. It holds 650 million gallons of water $100,000 Dam Measure Safety of Arch Construction By Truman Stevens tion chosen. From this circumstance the question naturally arises: If the thin dams were strong enough, were not large sums of money wasted on the thick ones? This is one of the questions that the impending experiment in California aims to answer. The other question— safety—undoubtedly is the first consideration in dam construction. A great vol- ume of water let loose at high velocity through the failure of a dam may be more quickly destructive than fire. Furthermore, the loss of the water stored by the dam may be disas- trous in itself because it is needed for supplying a com- munity, for irrigating crops, or for generating power. In the past, engineers have been dependent for their knowledge of dams upon the results of experiments with small models in laboratories, and upon the development of various methods of design by mathematics. The California experiment will furnish engineering science with its first oppor- tunity to perform needed tests on an adequate scale. Through the Department of the In- terior and the Southern California Edison Company an ideal site and suitable facili- ties have been obtained for the test dam on Stevenson Creek, a small tributary of the San Joaquin River. The creek gorge is of granite, steep and narrow, so that the reservoir will be small. A recently com- pleted water-supply tunnel of the Southern California Edison Company is near and provides means for furnishing and con- trolling the water needed. HE idea of the committee that has the experiment in charge is to approxi mate the most daringly thin dams that have been built, and perhaps “go ther one butter.” Then, after many tests and measurements, an attempt will be ma to break the dam in order to discover its- weakest part and the manner of failure. For this purpose the dam will be extended vertically to increase the depth of water and its pressure against the dam. Preliminary to the construction of the test dams careful measurements are being made of existing dams and dams under construction. GILEPPE, BELGIUM 1875 pia O SAN MATEO, CAL. 1888 HERNET, CAL. 1895 PROPOSED DAM Contrasted with bulky arch dams constructed in the past, the proposed experimental dam appears as an extremely thin shell. The diagram shows the tendency toward economy of

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83¢ May, 1925 Three Hours after the Start Flames, driven by a high wind, sweeping a portion of the Colorado National Forest. Every year forest fires burn an area equivalent to a 10-mile strip from New York to Denver, mostly due to carelessness With the Eye of a Hawk fi A lookout in the Black Hills National Forest, | 9 §, D., using ingenious fire-finding instrument to establish the location of a blaze. This ig a most effective method of fire protection Photos courtesy Service ORE than half a million acres of national forest lands laid in waste by flames! These startling figures set 1924 down as one of the most critical years in the experience of the United States Forest Service. Growing care- lessness on the part of the campers, combined with long sustained droughts are given as the cause. “Only 20 per cent of these forest fires were due to lightning. Four-fifths were traced to human causes. Smoking, especially of cigarettes, camp- fires and incendiarism were the chief of these, with smoking by far the most serious. Fires burning more than 1000 acres in a single day were not infrequent. During the year flames destroyed or damaged enough timber to build five- toom houses for the entire population of San Fran- asco, Calif., Denver, Colo., or Washington, D. C. Th the last six months of 1924 the government spent $1,600,000 in fighting fires, outside of the cost of forest Officers’ salaries. Lookouts stationed on igh ground, airplane patrols and fire-fighters are on € job night and day; yet in spite of their best efforts, the yearly damage from forest ' fires, due mostly to public carelessness, is more than $16,000,000! POPULAR SCIENCE MONTHLY 39 alf Million Acres Burned in a Year U.S.Forest Uncle Sam’s Fire Scout on the Job This ranger in the New Mexican Forest Reservé is searching for any telltale wisp of smoke caused by some deserted camp-fire or lighted cigarette The Fire Line Woodsmen clearing a line of brush and debris to halt a conflagration in the Wa- satch Nationai Forest, Utah Mia oe De hg 4 Wes > ie xe Pe pt A new portable fire-fighitng outfit, with powerful pump and long hose carried on a motorcycle sidecar, is particularly adapted to use in rough forest lands. The water can be pumped from any available stream. »The. outfit also includes two chemical tanks, shovels, spades, axes, and other fire-fighting implements. Usually two men constitute the operating force, one man riding on a back seat

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40° = POPULAR SCIENCE MONTHLY May. 1925 « xploring a Jungle in Mid-Atlantic Science’s Thrilling Quest into the Sargasso Sea Brings to Light Fish with Fingers, Hair, and Feathers; Ocean Insects Never Seen Before N AN odd, basket-like contrivance of By Raymond J. Brown steel, suspended just above the water from the bow of a wooden steamship as belonging to any known species. in mid-Atlantic, a tall, slim man in the Apparently it is entirely new to science. rough clothing of a common sailor recently Other valuable discoveries are fish with stood brandishing a story as the “graveyard of the Atlantic,” J and the supposed vanishing place mythical continent of Atlantis, — oceanic lake between Bermuda and the Virgin Isles, of approximately 400,000 is a huge square miles in area,

long-handled scoop net. He was peering intent] ae <i ri waed- Enters Neptune’s Graveyard infested depths through ‘Not since the days when young Darwin which the ship was cruised the seas in the Beagle has there creeping, quite as“a been a more picturesque figure in scientific boy standing in the discovery than that of William Beebe, curator bow of a flat-bottomed of ornithology of the New York Zoological Society, who now has ventured into wilder- rowboat might scan nesses of the Atlantic that long have chal- the bottom of a shallow lenged science. inlet in search of crabs. Readers of POPULAR SCIENCE MONTHLY Suddenly the man are well acquainted with Beebe’s previous = bent forward, thrust his romantic adventures to the desolate Gala- cf net down swiftly, swept pagos and into British Guiana. The story of ‘it through a wide arc his present venture is equally fascinating. While his good ship Arcturus may never take its place beside the Beagle in scientific importance, it promises an amazing wealth of and drew it forth again. In the meshes, as he

5 a : gece ‘ . a : : f/ se

William Beebe or almost 10 times as large as New York State. ‘THE sea is inclosed by the twenty-fifth and thirtieth parallels of north latitude, and the thirty-eighth ana sixtieth meridians: of - » west longitude. Ac tually it is a great whirpool, formed by the Gulf Stream and: » the main equatorial current that flows westward across the Atlantic from Africa to South Amer. ica. It circulates but

raised the implement new discovery as it plows among the weeds of Scientist, explorer, aloft, was struggling an the Sargasso Sea. and writer outlandish creature of many hues with a dozen tapering tentacles wriggling from its shapeless body. fins like hands; insects of which science With this catch what is possibly the had not heard previously that walk 314 most spectacular and thrilling scientific miles deep on the ocean bottom; sponges expedition of the present day may be with skeletons like glass. With said to have actually begun. The tall withdrawal of the trawling-nets odd man was the distinguished scientist and creatures like these have been explorer, William Beebe. The ship from from the depths. which he was conducting his queer fishing The Sargasso Sea, famed in fable and was the Arcturus, a 280-foot, 2475-ton vessel, especially equip- ped for the exploration of the most mysterious region on the face of the earth—the Sargasso Sea, a weird ocean jungle that has been an enigma and chal- lenge to science for centuries. The strange fish that had just been drawn from the sea ~7as the first specimen collected by the expedition, which is spon- sored by the New York Zo- ological Society. INCE then a wealth of bi- ological specimens has re- warded the efforts of the little band of scientists aboard the Arcturus. By radio Beebe has reported many amazing finds, wrung from the reluctant grasp of Neptune by the nets and dredges with which his vessel is equipped. Among them is a strange fish covered with scales that are like hair or feathers. slowly; yet into it is. drawn irresistibly the - débris that floats along on these grest ocean rivers—seaweed, driftwood, animal - carcasses, and vegetation from the shores; each the hulks of lost ships, dead sea creatures, refuse from ocean-going vessels. All the taken flotsam of the Atlantic, it may be said without undue exaggeration, eventually.

Neither Beebe nor Dr. William Examining the First Haul K. Gregory, of the American Two members of the Beebe expedition, Mrs. C. J. Fish (right); Museum of Natural History, a government representative, and Miss Lillian Segal, a bio- who is a member ofthe expe- dition, can classify this creature logical chemist, are shown here aboard the Arcturus, exe amining the first haul of strange creatures from the : Sea. Many remarkable specimens already have been caught

reaches the Sargasso Sea, there to swim ©: sluggishly about until it decays « and sinks to the bottom. It is this accumulation of rotting organic matter that has made the Sargasso Sea the garden soil of the ocean, and hence of peculiar interest +e science. In it float enormous grassy islands of the peculiar yellowish seaweed called “Sar- gassum,”’ which derives its nour- ishment from the sunken ocean garbage, quite as the plants of the land thrive in ground that is enriched by decayed animal and vegetable waste. Beneath the waters, feeding on the refuse from sea and land, live the strangest creatures that exist on earth. Columbus, seeking lands to the westward, thought he had discovered them when he ran into this swirling marine forest. MaABINERS crossing the At-. lantic have for centuries avoided the Sargasso Sea. ‘Tra- dition says that many a ship, becalmed there, or unable te cleave its way through - the thick floating grass, has floated round and round in those deadly

May’ 19: waters Jast jou others t peneatl ped 5 The of this howeve cause 0 jn and scientif our wh knowles dweller: Atlanti furnish¢ practice of marl TISt to tl by prev the litt! aboard these tr The d mirably fascina which

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Mays 1925 yntil its skeleton at joined’ the thousands of that found their graves peneath the Sargasso’s tan- gied surface covering. The biological importance of this strange sea meadow, however, is enormous. Be- cause of the discoveries made jn and around it by previous scientific expeditions, we have our whole conceptions and knowledge of the strange dwellers of the waters of the Atlantic. The Sargasso Sea furnishes the food supply of practically the entire range of marine inhabitants. TIS to coordinate and add Fe the knowledge gained by previous expeditions that the little group of scientists aboard the Arcturus sailed to these treacherous waters. The Arcturus has been ad- mirably equipped for the — fascinating adventure on which its passengers em- parked. Besides the movable ~ railed platform from which Beebe accomplished the first catch of the expedition, there jsa runway with a handrail around the outside of the hill, from which fish or other creatures may be harpooned or netted, or observations made. Aseries of searchlights, the beams of which can be turned in any direction horizontally or ver- tically, facilitates observations at night. The masts of the ship have been equipped with crow’s-nests so that hunting-grounds not visible from the deck or the runway may:be searched for. Part of the wooden bottom of the ship was removed and plate glass substituted, so that, with the aid of strong lights, observations can be made of the life beneath the surface, both plant and animal. There are steel platforms, which can be raised and lowered on davits, and which permit divers to descend into the sea to observe and to seek specimens. Numerous small boats, some with glass bottoms, are carried for scouting expeditions over the floating meadows. There are aquariums, tanks, and wells for live specimens, and a darkroom in which POPULAR ‘SCIENCE MONTHLY How a Scientist Goes Fishing Leaning from a basket-like “pulpit” at the bow of the Arcturus, William Beebe is seen here dipping his long-handled net into the Sargasso Sea, to draw from that teeming ocean-jungle creatures that never were seen nor known to science before the strange luminous fishes that inhabit the ocean’s bottom may be studied. The propeller of the vessel is fitted with a guard to prevent entanglement of sea growths. Miles and miles of cable are carried for the dredging operations that already have yielded specimens of enormous scientific interest. Three and a half miles was the deepest to which the dredge had de- scended at the time of this writing, but the Arcturus is equipped to make sound- ings twice as deep. Half-inch cables, made up of 133 sepa- rate wires, are used for the dredge, which is hauled along sledlike on runne-s on the ocean bottom, and for the great trawling- net. Just how big a job it is to dredge the depths of the ocean is shown by Beebe’s wirelessed report that it takes an hour to let the cable down a mile and another hour to haul it in again. One of the announced purposes of the expedition is to endeavor to obtain a specimen of the giant squid, or cuttlefish, most dreadful of all sea creatures. This is the huge, ten-armed monster that has figured so often in tales of the sea. The cruising range of the Arcturus is 30,000 miles, and she will-remain at sea for a half-year at least, touching at shores where specimens are likely to be found. American museums and aquariums are likely to be enriched materially by this expedition, which promises to achieve results of greater importance even than those of Beebe’s previous recent expedi- tions to Galapagos and British Guiana, which have been described in POPULAR SCIENCE MONTHLY. Equipped for Adventure This broken-away view of the woodem steamer Arcturus shows the remark- able way in which the vessel is Nee equipped for the voyage of fascinating . scientific exploration and discovery ba into “the graveyard of the ae Atlantic.” Every provision —— has been made for observing and studying sea life at close quarters and making photos Courtesy Clase atrome for e New York Worl

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ANY novel features are incorpo- rated in a new method of produc- ing moving pictures for non- theatrical use developed by Thomas Armat, of Washington, D. C., who was a pioneer in the development of the moving- picture projecting machine. The new process involves a camera, a projecting machine, a new kind of moving-picture film, and new ways of taking and showing pictures, which per- mit one-eighth of the usual quantity of film to be used. In ordinary moving-pictures 16 images are photographed and projected a second. Mr. Armat has succeeded in cutting the number of pictures made and shown each second to eight. This he has accomplished by making each “‘frame,”’ or separate pic- ture, do double duty, for instead of each frame containing only a single picture, it contains two. In the conventional movie camera the movement of the film is controlled auto- matically so that the film is halted mo- mentarily while each exposure is made. By the Armat process the film is halted for double the usual time, and two pic- POPULAR SCIENCE MONTHLY for the Amateur The projecting machine is simple to operate, frequent changes of film being eliminated tures are made, one on top of the other. When the film made by this process is projected, each frame is held stationary in the projector for double the usual time— an eighth of a second, approximately, in- stead of a sixteenth—and the light in the projector lamp is interrupted. The result is that the same frame is seen twice, and here comes a remarkable feature of the process. Through an optical phenome- $ikReel Movies for Every Home Inventor Claims New Method Simplifies Film-Making ne fd non, in which the imagination possibly plays a part, the eye views the twoi in the same frame separately, and in proper order, the result being that an impression of continuous action is con. veyed, exactly as happens when ordinary film is projected at normal speed. This one feature would per mit the amount of film neces sary to show any action to be eut to half. The Armat film, though, is half the width of standard film, and each image is reduced one-half in length.. Thus the amount of film necessary for a picture is reduced to one-eighth the quantity ordi- narily used. Prints can be made on the Armat film from standard negatives, the conventional feature picture of five or six reels requiring only a single one-thousand-foot reel of Armat film, which once placed in the projector will run for an hour without further attention of the operator. The camera invented by Mr. Armat is a compact, simple, light machine that can be operated by any one without special training or practice. Suction Magnifier for Camera Aids in Focusing having to use a large focusing cloth in |order to obtain a sharp picture, a magnifier has been TT: OVERCOME tthe drawback of appear clear and well defined for sharp focusing. To examine other sections of the screen, the magnifier is simply slid along the screen toa new position. A screw thread at the eyepiece end makes it possible to adjust the distances of the invented that is held to the focusing screen by suction. Ordi- narily, working with a magnifier is: difficult. Holding it in one hand leaves only one hand free to make adjustments and to pull the foéusing cloth around the back of the camera. The new device, a light alu- minum tubeless than three inches long, containing a magnifying lens, is fitted with a rubber suction cup. Besides holding the magnifier in position, this cup protects the section of the ground glass under examination from outside light so that work can be done as well, it is claimed, as if a large focusing cloth were used. The image is said to How the magnifier is attached to the screen by suction lens from the screen to suit the eyesight of the user and meet the requirements of each individual photograph. also, with hand -cameras that often have focusing hoods of insufficient size for accurate work. Used with a reflex cam- era, the long hood can be dis carded and the camera used at 4 higher level, giving a_ better point of view. AN ARTICLE on the progress of television,which was announ for ‘this month, will appear in a subseyueiit issue of POPULAR SCIENCE’ MONTHLY; bet ‘THE magnifier can be used, May, 19% N] | Ul di article and ey wire, | paper hooks, blades safety: melon of solc coins, natior Suc make muset

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ny, 195 ong the y thread of the suit the neet the dividual ye used, cameras g hoods accurate lex cam- be dis- ised at a . better gress ‘a nounced ppear in POPULAR * spoons, hairpins, X-ray showing safety-pin and button lodged in the throat of a 10-day- old baby. These two articles were removed in one minute United States are museums where are displayed an amazing assortment of articles, mostly useless. There are carpet tacks, pins, needles, fragments of combs and eyeglass frames, thumbtacks, bits of wire, shoe laces, pieces of bed springs, paper clips, metal tags, washers, curtain hooks, cartridges, shot, safety-razor blades, teeth both natural and false, phonograph needles, safety-pins, fragments of bone, water- melon and other seeds, coffee beans, pieces of solder, beads strung and unstrung, and coins, the last almost entirely of denomi- nations less than half a dollar. Such articles, you would say, would make only a poor display in a hospital museum case. They do. At least, the exhibition I saw re- cently in the Jefferson Medical College, Philadelphia, Pa., was singularly uninspiring in itself. It happens, however, that vir- tually every one of the thousands of articles displayed there and at the other similar exhibits repre- sents a successful operation. For these odd collections of useless hardware, vegetable mat- ter, and trinkets are made up of the queer things people swallow. People take these singularly indigestible objects into their for a variety of reasons. A small number passes into the stomach, throat or lungs by acci- t. The most careful person is likely to swallow a peach or Prune pit, a small bone, a pebble, o bird-shot with his food and not realize that he has done so. [' HOSPITALS in many parts of the POPULAR SCIENCE MONTHLY go09 0-00%0 007 709 40 40 re 28700 A tH aD } Pry. s oo § % ne ODD Hinde ag eb Eh yeh ars CG; Roar UN renters wound tty are gets Wid ores penis et Se Area eee t.eeeeees aeeoeeeeeet €6000 eeeorGg0ane2eeoe © 2S 28 OF SOF TH C8HGOSSF89S° ORO TFHPOCOHSE SOHO O eee e#e# 8 6 * Gee 2533s @ Ge €0008680 6 GSS0 S$ sSeseesastesee® oree Rene. ee ee ge ee ee & ° ee cena Bi a ee oe a eoeten gee 68 poe 908, i ? es is, > location of a foreign body swallowed by a patient. operation frequently is necessary to save the patient’s life All these objects—nearly a thousand in number—were removed recently from the stomach of a 15- year-old girl in Saginaw, Mich. They include safety-pins, earrings, watch chains, coins, metal street-car tokens, brooches, nails, laces, and ribbons, weighing nearly four pounds altogether |} Strange Things Folks Swallow The amazing variety of dangerous objects found in human stomachs—How they get there and how they are removed— Precautions to safeguard yourself and your children By Ada Patterson Most of these foreign bodies that are swallowed, however, are taken by intent. The professional swallowers—‘human ostriches” they call themselves—who entertain in the side shows at county fairs have contributed many weird additions to the odd surgical museums. Many other persons swallow sharp objects—nails, needles, knives, and razor blades—with suicidal intent. Other habitual ‘‘swallowers” are mentally de- ranged, or suffer from some peculiar phy- siological condition that causes them to enjoy the irritation hard or sharp objects set up in their internal organs. Then a great many of those who have been ope- How Swallowed Objects Are Located Physicians using improved X-ray apparatus to determine the A surgical rated on have been infants whose careless mothers or nurses have left bright and attractive but dangerous objects within their reach. | D his CHEVALIER JACKSON profes- sor of laryngology at Jefferson Medi- cal College, who has performed more than 1200 operations toremove from the throat, stomach, and lungs of people objects that had no business there, discussed with me recently the really amazing things that people swallow. Doctor Jackson’s own museum supplies eloquent if mute testi- mony as to this. “There is rarely a week goes by,” he said, ‘‘that you cannot read of some per- son who hasswallowed an almcst unbeliev- able variety of dangerous objects. Not long ago an operation on a 15-year-old girl in Saginaw, Mich., resulted in the removal of almost a thousand things she had swallowed. These included safety-pins, earrings, watch chains, stove bolts, coins, metal street-car tokens, brooches, ad- hesive tape, shoe laces and bits of ribbon—almost four pounds in all. “A professional ‘swallower’ at Chicago yielded 275 metal ob- jects in an operation, the con- tents of his stomach including upholstery tacks, nuts, bolts, screws, a can-opener, a couple of handfuls of thumbtacks, almost a box of fair-sized nails, cart- ridges, safety-pins, paper clips, _and coins. **A woman in New York, who had been eating pins and needles

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44 for years, desiring a more substantial diet possibly, at last began swallowing safety- razor blades, with fatal results. “A needle—the first he had swallowed —killed a four-year-old boy in Newark, N. J., a few months ago, although he had previously swallowed bone buttons, bits of wood, and similar things without ap- parent discomfort. “DECENTLY a Kansas City sur- geon removed about 50 pieces of mattress spring, two hooks with staples attavhed, and four hairpins from the stomach of a woman patient, who recovered after the operation. “These are typical cases of persons who swallow things inten- tionally. Not long ago I heard of an accidental ease in Toledo, Ohio; which supplies a strik- ing instance of how easily carelessness may lead to disastrous re- sults. A saleswoman in hantiesemivenentihe- a department store was old Johnny -Fitzpat- pinning some merchan- trick of Brooklyn, N. Y., disappeared dise together and had 16 pins in her mouth —a dangerous practice, of course. A fellow clerk offered her a piece of candy, and unthinkingly she began to eat it. She coughed, and of course swal- lowed both candy and pins. “About 90 per cent of the cases of foreign bodies getting into the air and food passages accidentally probably are avoidable. . Bolting of food, a common fault of Americans, is responsible for many of them. Carelessness in preparing food is responsible for many more. It is nothing less than criminal to serve food containing fragments of nut shells, egg shells, oyster shells, crab shells and so on, or to permit chips from food containers, splinters from flour or sugar barrels, or solder from tin cans to get into food. When a fruit jar, jelly glass, or similar container breaks or chips in opening, the contents should be strained or thrown away. mysteriously. = EOF LE are careless, too, in serving to children, invalids or aged persons food that contains bones, watermelon seeds, orange seeds, lemon seeds, cherry, plum, prune or peach pits or the stems of fruits.° Many kinds of ordinarily harm- less candy are a source of grave danger to young children. A child less than two years of age has no grinding teeth, and consequently is no more able to dispose of a piece of peanut candy than it could eat an iron bar. “Tf a child of that age gets a piece of peanut into his mouth, he cannot chew it. There are only three things he can do: spit it out, swallow it whole, or breathe it into thé lungs. If he spits it out, well and good; if he swallows it whole, it will pass into the stomach to make trouble. If he breathes it into the lungs, it will lodge there jana lacerate. ff Swallows Toy A little tin auto be- The upper picture shows how the X-ray found it in the esophagus POPULAR SCIENCE MONTHLY “*False teeth are frequently swallowed, often causing choking or irritation of the stomach or intestines that results fatally. Any wearer of false teeth whose plate be- comes damaged or ill fitting should take it to his dentist for repair immediately. How Did She Do It? A Cincinnati woman recently complained of pains in her sto- mach. Physicians, after an X-ray, re- moved from her sto- mach two pieces of brass curtain rod, one measuring 714 inches long, the other six inches; also a piece of comb three inches long. The woman did not re- member when she swallowed them! by operation, and the woman reepy, ““Women often have a habit of hold. ing coins in their mouths. It is remark able, though, that of 130 of m ‘ operations for the removal of swallowed coins, few of the patients have women. Most have been little childre who suffered the consequences of the } F example shown them by their mothers, " HE rest of our small patie Bin oF kad harmful objects bee their mothers have been careless enough to leave within their reach things smal enough to be placed in their mouths, ‘A child seven years old carried a upholstering tack about in his right lung for two years. Physicians said the was tubercular. The X-ray, however, located the tack.” N Doctor Jackson is the inventor of the bronchoseope, a de vice that. has faejlj- tated greatly the ire: moval of foreign objects from the throat or windpipe. © This instrume consists of along flexible tube, w which is a series of mirrors that - reflect an image of theobjeet that must be Illumination ‘is sup plied by a small elec tric light. -*- -/ 3% The patient is laid t “One patient here was a woman who swallowed a fragment of tooth in a dentist’s chair during a fit of coughing that followed the extraction. Neither she nor the dentist was aware of what had happened. Later, though, she developed an almost incessant cough. At a con- sultation of physicians her trouble was diagnosed as an abscess in one of her lungs. The X-ray, however, disclosed the tooth fragment that had lodged in her lung. The bit of tooth was removed To Avoid Trouble— ON’T eat or drink in the dark. Keep small objects out of the reach of small children. Never put pins, coins, pencils, or smaller objects in your mouth. In preparing food, be careful to keep foreign bodies out of it. If you require glasses to read, wear them also when you eat. When some instrument, such as a physician’s thermometer, is placed in your mouth, be careful not to cough. These precautions against swallowing foreign bodies are urged by Dr. Chevalier Jackson of Jefferson Medical College, who has performed more than 1200 operations to remove ob- jects from throats and stomachs. upon.a table, and his head and. neck: are so placed that mouth, throat, and wind- pipe are in a straight line. The operating surgeon inserts the tube in the patient's throat, slips his forceps down into the tube, guiding his movements by the re flection in the mirrors, and withdraws the object that has been swallowed. This operation can be performed without an anesthetic. An 18-months-old baby in Brooklyn not long ago swallowed a tiny lead’ automo- bile. The child was hurried to a hospital, where an X-ray examination revealed the toy in the upper part of the child’s esopha- gus. The bronchoscope was. worked gently down the throat until ‘it ‘covered thetoy. Then the tube was carefully drawn out, and the automobile came with it. Nature makes strenuous efforts to pro tect foreign bodies from doing harm-whea they find their way into the’ respiratory system or digestive tract. Thus, post mortem examinations of many. habitial ‘‘swallowers” have shown layer upon laye of tissue grown about the objects 2 hiding them. This is a process analoge to that which produces callusés on the hands, or that which causes a woul oyster to produce a protecting pearl. = HIS, however, gives no assurance @ safety to any one who has 8 , something that does not belong im 2 mechanism. Nature frequently fails® its efforts to protect. The object mayne come embedded in an organ and caused malignant growth. It may choke “the swallower. It may cause lameness, blood poisoning. “If an alien substant gets beyond the throat, we should hastel to a hospital or to a physician who ha an X-ray apparatus. May. ig

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1925 POPULAR SCIENCE MONTHLY 45 way, This mountain of Profit from City 2h oe ola coleptege New York City Junk Piles J ys | % ae : : ’ : ee How Your Old Trash m = Is Salvaged ee est Ae + 9 wa se =a, cae arise sR wr =e TR er et te oe a were ma ae ee ee ate gram ths. cn Pm ae oe a, tto5 + Sede aivaeheminenecs ani ae Boer 4 8) ae Oot ee merger tee NS way * Se Oe eee sre to. oe ef ob norneshiocs xg tae ae meer T° =p Pear eee” seared Fe Se ESTs Ft res 7 turned into steel daily. pte Ah ith phen sale mene This pile of 900,000 shoes, at sen a? tie Worcester, Mass., is said «tae? to be the world’s largest SS eialaisemeis 2 RREOE “errs co pscere sr - D2» you ever wonder what happens to all the trash thrown out of the homes, offices, and workshops of our big cities—the empty bottles, the discarded newspapers and magazines, the scrap iron and worn-out automobile tires? The pictures on this page tell the story, a story of how mountains of junk are salvaged and turned back to profitable uses. In New York City alone, the Street Cleaning Department disposes of more than 10,000,000 cubic yards of refuse annually. Every year, city trash heaps yield millions of dollars in reclaimable materials ack: are d wind- atient’s nto the the re aws the l. This hout an klyn not automo- At left: A $20,000 sani of : Crating unbroken, 150,000 old auto tires in empty milk bottles, salvaged Boston. They go into the from New York dumps, for making of rubber boots shipment to milk companies Part of New York’s enormous daily crop of old newspapers, packed in bales on a Hudson River pier. They go to manufacturers to be made into more paper

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Ejectricity POPULAR SCIENCE MONTHLY Recent Survey Shows Surprising Progress in Wired Lighting and Household Appliances—New Contributions to Science HE men you will find in command- ing positions to- day are men who are well-informed—who have at their disposal a practical, working know- ledge of current develop- ments, not only in public affairs, but in the field of scientific discovery. and invention. ‘ It is to help you keep pace with the rapid ad- vance of science that we publish here a résumé of the month’s important additions to the world’s useful knowledge. Electricity in the Home WENTY-FIVE years ago, a home that was wired for elec- tric light was enough of a novelty to be the subject of comment in the neigh- borhood. Now more than half of the 26,000,- 000 homes in the United States use electricity, not only for light- ing, but for a wide variety of household appliances, a recent survey shows. In this the West, particularly the Pacific Coast, leads by a wide margin. Of almost 2,000,000 homes on the Western Coast, 85.7 per cent are wired. Utah leads all other states, with 98.2 per cent of its homes electrified, and California is second with 96.5 per cent. Tennessee, Kentucky, Alabama, and Mississippi, grouped as the East South Central states, appear to use electricity least, 22.2 per cent of about 2,000,000 homes being equipped electrically. About 27 per cent of the 3,200,000 homes in the nine states making up the South Atlantic group use electricity, while 53 per cent of the 54% million homes in New York, New Jersey, and Pennsylvania are wired. In New England 67.4 per cent of all homes use electricity. The Rocky Mountain states have a little less than a million homes, almost half of which are wired. “Many factors, of course, govern the use of electricity in homes. The relative availability of electricity possibly is the chief ‘one; also states where many new homes have been built in recent years are bound to be heavy users since most new homes are wired for electricity as a matter of course. And yet.some of the older states are well in the forefront, as is shown by the individual and collective figures given above. Three times the insulating efficiency of the ordinary vacuum bottle is claimed for a new type of vacuum container recently designed by Dr. C. W. Kanolt, physicist of the U.S. Bureau of Standards at Washington, D.C. He is shown here with his invention. The bottle, said to be virtually heatproof, is used for holding liquid gases at extremely low temperatures in laboratory experiments. Noise-Maker Aids the Deaf ad YOU have ever tried to carry on a conversation on a railroad train, you probably appreciate how difficult it is to make yourself heard above the rumbling of the wheels. Deaf persons, however, find their hearing improved by certain noises similar to the roar of atrain. These sounds seem to set up vibrations in the ears, rendering certain auditory nerves sensitive so that sounds ordinarily in- audible are heard. . Now Dr. Byron E. Eldred, well known engineer and inventor, of New York City, has utilized this principle in a device to aid the deaf. His machine consists of a box, which, An invention that may prove extremely valuable in the improvement of radio loudspeakers, talking machines, telephones, automobile mufflers, and similar appliances, is known as an acoustic filter. It is said to permit only certain sounds to pass © Harris and Ewing Newest Vacuum Bottle Is Virtually Heat-Proof It is proof against the cold as well New Sound Filter May Improve Loudspeakers 4 The inventor is Dr. G. W. Stewattd when an electrie is introduced, Produces sounds not unlike ‘the rumble of a train. "These vibrations are carried to the ears of a deaf person, and carry with them, ac. cording to the inventor the vibrations of other sounds that ordinarily the deaf person cannot hear. Leading ear specialists who have seen the device demonstrated say it does not cure deafness, but that it opens interesting possibilities for aiding the deaf, particularly those who te ca certain affections of the inner ear. Seashore Undertow a Myth? lf YOU are one of those persons who fear to go surf~ bathing because of the undertow, you will find some encouragement for. the coming summer in a recent statement of Dr. W. M. Davis, emeritus professor of geology at Harvard University. 2 Doctor Davis says there is no under- tow. The belief that there is a strong bottom current to carry bathers away from the shore, he says, is a myth that emanated from the excited imaginations of through it. the University of Iowa laboratory, who based the idea on his discovery that sound waves cam be made to interfere with one another in such @ way that only desired tones will be transmi May, 195 Now Lightens Labor in 13,000,000 Homes persons unused to oe

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dertow 2 : of those ear to go cause of you will ‘agement summer {. Davis, Harvard © under- a strong rs away shore, he a myth anated . excited tions of inused to ws, 18 being buffeted by the waves. er wave rolls up to the shore, r Davis says, naturally the water pack again from the sloping beach, times with force sufficient to sweep - n whom it catches unaware off his $ t, Then, if the bather is inexperienced, wit likely to be tumbled around by suc- wae waves and to believe that he has n carried along by a current, when as 4 matter of fact he has scarcely moved. New Marvels of the Movies ERSONS whose memories go back to P the early days of the movie craze will recall that a large proportion of the films shown in America at that time were im- rted, particularly from France. French moving-pictures are seen in this country only rarely now, yet France still continues to make substantial contributions to moving-pictures, particularly on the tech- nical side. Two recent reports from that country are illustrative of the fact. One has to do with the invention by Loudspeaker Used in Tests Amethod of testing the relative sound- qualities of various building ma- terials recently has been perfected by V.L. Christler of the U. S. Bureau of Standards, shown below. The loud- speaker is tightly fastened to the ma- terial under test, and vibrations set. up in the material are recorded on a M. Daponte of a method of projecting pictures in relief by adapting the principle of the stereoscope to the screen. The subject is photographed in cuplicate by means of a special double camera. The resulting two negatives then are printed on a Single positive, the images of one being superimposed on the other by means of a combination of lenses. When this film is run through the special projection machine developed for the process, the pictures appear as having three dimensions, this illusion being pro- duced by a complicated lighting system in * Projector, which causes two beams of vatying intensity to pass through the film tothe screen. There is no distortion in res, it is said, no matter from what angle they are viewed. more amazing than this process is production by a Parisian film company ofa photo-drama in which all the actors ae bees. The life of the bee, of course, shown in the films before, but astounding film has a real dramatic - With a bee hero, heroine and villains 4 whole hive full of “extra” bees for Hamosphere” just like the conventional dlywood production. POPULAR SCIENCE MONTHLY 47 Testing Bodily Effects of Temperature To determine the physical effects of extreme temperatures on workers in factories and mines, scientists of the American Society of Heating and Ventilating Engineers are conducting a remark- ab'e series of experiments in cork-line test chambers at Pitts burgh, Pa. These rooms are equipped with elaborate instru- ments for cooling, heating, washing, drying, and measuring the atmosphere. Effects on the body of exceedingly humid atmos- phere are determined by an analysis of the subject’s breath — How Much Science © Harris & Ewing Do You Know? ‘ ROM hundreds of queries that . is have been received from our Predicts Winged Autos readers during the month, the fol- HERE is a word picture of the motor- lowing dozen questions were se- car of the future as presented by lected. How many of them can Prof. A. M. Low, of England: you answer? A cigar-shaped body, completely in- Write down the answers as best closed. Instead of fenders, wings, so that you can, then turn to page 132 and the car can fly whenever conditions war- see how nearly you were right. rant. An exceedingly powerful motor, capable of driving the car at a hundred 1. oe does a _— nr the head miles an hour or more on the ground and 2. Why. ty eos eee few green at airplane speed in the air. flowers? A hundred miles an hour, according to 3. What is the difference be- Professor Low, will be merely normal tween gasoline and kerosene? touring speed for this vehicle, and all cars 4. Are the Rockies growing will be able to travel at that speed without higher? danger, because the highways will be 5. beta dronsariger oo —— sae? — and a scientifically to 6. What comes & coe eee eliminate cross traffic. 7. Why do some soaps float? a ‘ 8. Why does water in the bottom Is Goiter Infectious? of a double-boiler prevent the r a urning of food in the to A YEAR or so ago medical authorities 9. Is pip head phone different were generally agreed that goiter was from an ordinary telephone? a disease confined to certain sections of 10. Why do worms come out after this country, and caused by a lack of a heavy rain? iodine in the drinking water of the regions 11. Why is the earth round? where it was common. According to 12. Why does fast music make Dr. E. P. Sloan, retiring president of the you feel more active? (Continued on page 131)

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nious method of manufactur- ing floor-coverings from old, worn-out automobile tires, a Seattle, Wash., inventor recently created a thriving new industry.on the Pacific Coast. An idea of the important possi- bilities of his invention may be gained from an estimate of the number of discarded tires that find their way to the nation’s junk piles each year. In the United States at present more than 17,000,000 motor- cars are in operation. Of this num- ber it is estimated that about 15,000,000 are pleasure or com- bined business and pleasure cars. Thus, estimating that each of the pleasure cars uses four tires every two years, ap- proximately 30,000,000 tires are dis- carded annually. By the new method either fabric or cord tires can be turned into durable floor mats B THE perfection of an inge- POPULAR SCIENCE MONTHLY Rubber Carpets Made from Old Auto Tires The ingenious new mechanical processes by which old tires are converted into floor mats are shown in these three pictures. First the tread is cut from the tire wall by the machine at the left. Next, small blocks are cut from the fabric (right) and two small holes are punched in each block. Finally, the blocks are strung like beads on steel rods (below) and the rods are welded into a mat of practically any size desired. They are said to resist oil, water, steam, rust, salt water and acid, and to last in good shape an average lifetime. In their manufacture one machine separates the bead, wall and tread of the tires. A second machine cuts fabric blocks about thre inches long and one inch wide from the tire. The same machine punches two small holes in each block. The small rubber blocks then are slipped over U-shaped steed rods. They are stacked s that the blocks fit over spaces be tween blocks in the preceding row. When the weaving is completed, the ends of the rods are welded to gether with brass clips. The block edges form the wearing surface of the mat. Although manufacture of these mats was begun very recently, thousands of them now are in use. The deep-sea lamp, with pressure- resisting bulb fitted into a heavy bronze cap, is lowered by cable with the diver. How the light jlluminates the depths during salvaging operations is illustrated graphically at the left by our artist New Diver’s Lamp Illuminates Ocean Depths and _ pressure-resisting deep-sea lights, recently invented by Capt. Benjamin Leavitt of Philadelphia, make it possible, it is claimed, for salvaging to be done at depths in which, hitherto, it has been impossible to work for any length of time. Ordinarily, a diver works in the dark ness in from 30 to 60 feet of water. Now Captain Leavitt claims that with his it- vention divers have reached a depth ¢ 361 feet, remaining for several hours 4 depths ranging from 194 to 318 feet. Also that the new deep-sea lamp wil withstand more than 10 times ordinary air pressure, giving almost daylight illumination. The lamp is of the vacuum incandescent type, with a heavy glass bulb fitted intoa bronze cap. The electric wires are I closed in a cable. A group of three lights is provided for each diver, the heavy bronze caps acting as weights. The diving suit is made of mangane bronze and has ball-bearing joints. flexible sections are of interlocked coppt tubing wrapped and lined with rubbet A HIGH-PRESSURE diving suit On the back of the suit is an air ch that supplies the diver with air for hours. He sees through glass window and has a telephone with which to com municate with the ship above. over

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hine cuts It three ne inch The same vO small k. The then are ded steel acked so paces be- ding row. mpleted, elded to- ‘he block ‘the mat. ese mats sands of ing suit deep-sea by Capt. ria, make vaging to therto, it for any the dark- ter. Now th his ir- depth ‘¢ hours at $18 feet. lamp wil _ ordinary daylight andescent ted intos ps are il- he heavy nanganes ints. The ced coppet r chambe ir for fou ; window h to coir Of forms can be used over and over as the ; Rone method of construction the framework is | puilt of timber in sections. To these timbers then are attached an outer wall of metal © TRGENT need of houses that can be rented at prices a workman can afford to pay, has brought about a new type of steel home in Great Britain, principally in Scotland. They can be erected, largely by unskilled labor, almost overnight. ‘ Three motor-trucks are said to be suffi- cient to carry the materials for a complete house from the factory to the site. No excavation is necessary and the parts are easily put together. Some of the build- ings with six rooms are now being erected for about $2200 each, approximately half the cost of a house of similar size made of brick and plaster. The steel, in plate or sheet form, is used in some cases for the exterior of houses; in POPULAR SCIENCE MONTHLY Bassiscos New Steel Homes >- Go Up Like A small steel home nearing completion. framework, is formed of steel sheets embossed to imitate stone blocks other cases for interiors or lining. In one type, a wooden framework is constructed in sections. To this are fixed metal sheets that will form the outer walls of the house. Inside the framework, interior walls of various kinds of composition are placed, leaving an air space between the outer The exterior, on a wooden Where steel framework is used, the exterior is formed of concrete blocks, locked in place and inner walls. Other builders are using steel framework instead of timbers. The parts of this are marked plainly and fit together readily, it is said, enabling four men to erect the framework of a house a day. The outer walls of this type of house are made of slabs of synthetic stone that lock into place, hiding the steel framework completely. In the interior, the steel is covered with a lining of composition sheets, giving the appearance of ordi- nary walls. Houses Made Fireproof by Gypsum Concrete Walls YPSUM, commonly called “plaster of Paris,”” which has been used for centuries for plastering walls, is the essential part of a new fireproof building material. Mixed with cinders, gravel, crushed stone or furnace slag, and poured in forms, it can be used to construct main walls and partitions of one- and two- story buildings. It is said now to be possible to erect an entire house of this incombustible material at a cost that com- pares favorably with that of a wooden building. While it takes ordinary concrete several days to harden, gypsum concrete is said to harden within 30 minutes. This speeds up construction work, lessening time and labor costs. Also, since the material sets sorapidly, a comparatively small number “Pouring” a gypsum-concrete house. From the mixer the concrcie 1s passed up by hand co the wall, where it is poured between the metal forms. Note how window frames are set in the forms. The upper picture shows a completed dwelling of bungalow type walls go up. Another advantage is that gypsum is considerably lighter than concrete. All corners and openings are reinforced by steel rods or welded steel fabric. In one-story construction, outside walls are made at least six inches thick; in two- story buildings eight inches, while parti- tions need be only from three to four inches thick. In a laboratory test made recently by the Department of Civil Engineering at Columbia University, a wall of gypsum concrete was exposed to fire, and kept under a temperature of 1700 degrees for an hour. After the test the exterior surface of the wall showed no signs of the heat. When the side of the wall exposed to the flames was washed with water, it showed a little of the cement washed away, leaving a slightly pitted surface. The fire-and-water test. After an hour’s exposure to flames at a temperature of 1700, following by 2134 minutes of water at 30 pounds pressure, the gypsum- concrete walls shown above were practically undamaged

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50 POPULAR SCIENCE MONTHLY Newest Telephone Is Loudspeaker ae : +7 FUP a The new telephone apparatus without mouthpiece or receiver Water-Tight Bathing Cap Gives Ear Comfort VERY woman swimmer knows how troublesome her ears can be. A cap, when tight enough to keep water out when swimming Indian fashion or diving, often exerts an uncomfortable pressure. To relieve this, a new bathing cap has built-in ear pockets. Its chin band, when adjusted, causes an inward pressure on the ribs of the cap, sealing all open spaces and «eeping the hair dry. Crust of Bread Found to Be i:ess Nourishing 4 AKING: children eat bread crusts may beg a useful practice from an economical ;standpoint, but the time- honored belief that the crusts possess better dietary qualities than the center of the brea! ‘seems to have scant basis in fact. This was revealed in some interest- ing experimerits just completed by Pro- fessor Rosese Hart Shaw of the American Institute of Baking. Professor Shaw took two young albino rats of the same brood, and fed one on crusts and the other on crumbs from the centers of the same loaves. The rat that was fed on crumbs reached normal size at maturity and was strong and sturdy, while the other remained scarcely larger than a mouse and was weak and puny. Repetition of the experiment on other rats brought always the same result. we ~ TELEPHONE without mouth- piece or receiver! Press a button and talk into the air in a natural tone of voice and the message will be repeated at the other end of the wire. This unique telephone was designed espe- cially for use in fac- tories and large of- fices. When an executive in one part of a fac- tory wishes to talk with a person in an- other part, he simply presses one of a num- ber of keys, and speaks his message in a natural voice at some distance away from the box. At the other end his voice is heard clearly and distinctly, as if it came from a radio loudspeaker. ° © K. &H. Window-Washing Eased by New Mounting ASHING both sides of a casement window at the same time is possible if it is fitted with a new carrier quadrant adjuster. The window may be opened to any desired position by regulating a lever on the inside of the house. The device in which the teeth of the quadrant engage a catch on the window- sill, holds the windows firmly in place, preventing them from sagging. When the Baby Cries F A baby cries every minute for 24 hours, it does work equivalent to lifting its own weight to the top of the Washing- ton Monument, Dr. John R. Murlin of Rochester, N. Y., has figured. Hot Water Always on Tap with Electric Heater AN ELECTRIC water heater, fitting at the back of a washbow/l, is said to produce hot water in a few seconds when the handle of its single faucet is turned to the right. By turning it to the left, cold water can be obtained. The temperature and flow of the water can be regulated to any desired degree and volume by turning a thumbscrew on the right-hand side of the heater. The heater is attached in place of the ordinary . faucet and connected with the electric service circuit. AN OBSERVATORY for avalanches, believed to be the first of its kind, has been erected in Tamischbachturm, Austria, by the State Railway. Its object is scientific and practical. It has been fitted with re- cording instruments, and it also will send out warnings when avalanches threaten. Ratchet Lever Adds Power to the Screwdriver [N SETTING or removing slotted head screws, the lever of this screwdriver takes the place of a wrench. It operates with a ratchet, making unnecessary the many quarter turns needed when the wrench method is used. The auxiliary handle of the tool has a cam-shaped bearing against the shank of the screwdriver. It acts as a ratchet, binding the shank when tightening the screw, and can be operated either to left or right. Gum} by FA; suffic Too mu ing the illustrat maticall needed. The le presser, set brus containe Har YLL: mos' while th parently sions he investig: tests wi! cally po caught s while fr on soul sounds score, Elec Turning screwdriver with auxiliary handle

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‘ap iting Lid to when ed to , cold water e and n the The inary . ectric lieved been ia, by antific ith re- | send eaten. wer 1 head driver erates "y the n the has a ank of tchet, ig the to left Gummed Labels Moistened by Automatic Device [F A gummed label is moistened in- sufficiently it will fall off a package. Too much moisture floods the gum, mak- ing the label useless. The new labeler illustrated is said to moisten labels auto- matically with just the amount of water needed. The label is passed under an automatic presser, Which holds it against a rubber- set'brush. This is kept moist by water contained in a small tank. Hardest Sounds to Hear aeeeeLes ending in “ng” are the most difficult for human ears to grasp, while those with ‘‘s,”’ “‘w,”’ and “‘y”’ ap- parently are the easiest. These conclu- sions have been reached through recent investigations by Dr. V. O. Knudsen. In tests with a large audience in an acousti- cally poor auditorium, only 48 per cent caught such sounds as “‘ting’’ and “bong,” while from 90 to 100 per cent were right on sounds like ‘‘wis’” or ‘“‘yox.” The sounds “‘d”’ ‘‘b’’ and ‘‘th’” made a poor score, Electric Night Light for - the Sickroom CREWED into an ordinary lamp ~ socket, this electric night light gives just enough illumination to prevent a child from being nervous, or to dimly light.a sickroom. The light may be used for 35 hours at a cost of one cent, it is eo, Night light inserted into ordinary socket POPULAR SCIENCE MONTHLY Portable NEW sound-ampli- fying instrument invented recently by Marconi to help deaf persons to hear, em- ploys a microphone and two vacuum tubes so arranged as to receive and magnify speech at a considerable distance. Voices near the micro- phone are magnified to such an extent, it is said, that even a man whose hearing is very poor can hear thespeech distinctly, even with the reproducer placed on the top of his hat Amplifier Aids the Deaf instead of against his ear. The instrument is designed on much the same principle as the audio amplifiers used in radio. It is so compact that it can be carried in a small case. New Curtain Rods Adjusted from the Floor ANGING curtains, a dreaded job in most households, is made a simpler task with the new type of curtain rods shown above. There is no need of climb- ing up to the rod on a ladder or chair. Instead, the curtain rod is lowered so that the draperies may be adjusted from the floor. Relieved of the strain of raising her arms above her height, the housewife is able to drape curtains to her complete satisfaction before raising the rods. The bars on which the shade, curtain, and draperies hang can be adjusted at any height by the operator by pushing the bars up against the window-frame and allowing them to drop in slots in brackets screwed to each side of the window frame. By lowering the draperies halfway and open- ing the upper sash of the window, ventila- tion is obtained, with privacy. Hearing with the reproducer placed on top of his hat Rolling Ball Serves as a | Cover for Inkwell HE annoyance of removing the cover of an inkwell every time a pen is to be used has been obviated by an ingenious cover that is closed by a small glass ball rolling on a runway. When a pen is in- serted, the ball is pushed back easily. As the pen is removed, the ball rolls for- ward, closing the well from dust and air. The top and runway for the ball are made of metal. Why a Cat Always Lands on Its Feet ALMost everybody probably has tried the experiment of turning a cat up- side down and dropping it to the ground to see it right itself in falling and land on its feet. Recently Professor R. Magnus, of the University of Utrecht, Holland, set out to learn why it is that a cat possesses the odd ability to change the direction of its body while falling. He discovered that it is entirely a mechanical, or reflex action which the cat performs unconsciously just as we close our eyes when some one aims a blow in our direction. This discovery was made as a result of performing the experiment with a cat from which he had removed the ability to perform conscious actions -by an operation on the brain. After the operation the cat fell feet down when it was dropped, just as it did before.

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POPULAR SCIENCE MONTHLY Digs Ditches The work of a gang of men with picks and shovels is performed by this mechani- cal trench digger, which scoops out a ditch cleanly in one powerful operation © U.&U. Invents a Flying Bicycle For 25 years Israel Zipperstein, a Chicago vest- oe maker, has devoted the greater part of his evenings i- ape to the invention of a flying bicycle, with cylindrical gt ARS as aan i revolving wings shown in his working models above : - | sa | Odd Auto Shaped like a Shoe This strange roadster, exhibited at a recent German automobile show, is built to resemble a giant shoe Mirrors for Dangerous Crossings Large mirrors set up at “blind” railway crossings are among the latest safety devices to safeguard motorists uM i j inoue ¥ Ld & May, 19 Odd Machines How Men with Unusual Ideq; VME GUM AED OP AOL LORM MEY: Third Wheel for Truck For use where extremely short turns are required in close quar- ters, a third wheel that can be handily substituted for the two front wheels of a motor-truck at need, recently has been invented Ambulance for Horses To aid in transporting sick or injured horses, the Western Pennsylvania Hu- mane Society recently placed in opera- tion the novel motor ambulance shown below. A small crane operated by the truck motor lifts the animal into the car LEM ROD” tren HORSE AMBUL ANCE. | Soq ETY » | { | | 4 f yy t

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May, 1925 and Inventions | Turn Them to Unusual Uses POPULAR SCIENCE MONTHLY Speed Measured by Sight Accurate measurement of the speed of a rapidly revolving shaft is obtained with this remarkable apparatus consisting of a disk pattern revolving on the shaft and observed through an electrical vibrating instrument. A Long-Legged Tractor Recent improvements on the “tractor on stilts,” invented some time ago for lifting and transporting piles of lurnber, have evolved this amazing machine. It can straddle a lumber pile and lift it auto- matically with its mighty inechanical arms The visible form of the revolving pattern determines the speed of the revolutions Nets Safeguard Workers ‘ Structural iron workers, though they are marvelously sure footed, sometimes slip and fall. As a safety precaution, nets made of woven rope, resembling circus nets, recently have been strung across the lower girders ofa building going up in San Francisco Wind-Driven Boat This is a model of a remarkable boat recently designed by a Ber- lin inventor. A windmill above the water drives an under-water propeller by means of chain gear Auto Lamp Instead of driving his old car to the junkman, Forrest Gibbons of Dayton, Ohio, fitted some of the parts to form this floor lamp Mechanical Pacer Aids Runners To help track athletes maintain the correct stride, Coach Thomas E. Jones has invented this pacing machine that rings a bell at definite intervals Builds Model of Brooklyn Bridge A remarkable model of the famous . Brooklyn Bridge (left) is the work of Michael Newman of Boston, Mass. It is 1614 feet long, two feet wide, 414 feet high, and is lighted by electricity

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Speeds Up Map-Making With this remarkable mapping camera designed by an army officer, it is possible to map approxi- mately 2000 square miles with one loading of film, at an altitude of 15,000 feet. This is three times the area possible in a single ex- posure with previous mapping cameras. The camera has three lenses, one in the center and two at an angle, which operate at the same moment, thus photographing three pictures POPULAR SCIENCE MONTHLY What’s New in Aeronautics May, 1925 Planes Repaired at Sea Airplanes now may be repaired and re- fueled in midocean, the navy having es- tablished the repair ship shown above. It is designed to operate with the battle fleet to take care of small planes operated by catapult from various dreadnaughts, but it can handle larger planes in an emergency. The photograph shows how a plane is lifted from the water by the repair ship Gliders Tested Safely A remarkable new apparatus for testing gliders under safe condi- tions is an outdoor wind tunnel built by the California Institute of Technology. It consists of four airplane motors mounted behind a grill-like structure that breaks up the current of air into an even flow. In front of this the glider is suspended on a cable by a pulley, and the effect of actual gliding is produced without danger. At the right is seen a glider mounted in front of the Institute’s wind tunnel Four airplane motors force air through the grill-like device, forming a wind tunnel on the other side, in which gliders are suspended, making it possible to conduct experiments with safety and accuracy practical biplane. spread of only 20 feet. the plane can be dismantled Baby Biplane Is Easily Dismantled This sturdy little machine is claimed to be the world’s smallest It is 16 feet long, six feet high, and has a wing By removing seven bolts, it is said that Air-Cushion Wing An escalloped airplane wing in- vented by Julius Fox of Cleve- land, Ohio, is designed for safer landing. Its peculiar construction, he says, creates cushions of air, lessening the machine’s angle of descent. A new wing rib also is shown less than half an hour

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. 1925 May, 1925 POPULAR SCIENCE MONTHLY 55 Novel Ideas Made Practical @ New Life-Preserver A combination of inflated tire, rubber trousers, slip- pers, and leg paddles makes up this ingenious life-preserver, in which, it is claimed, one can sit comfortably in the water until rescued. With pad- dles operated by the hands, as shown above, the life- preserver acts as a boat Burglar-Proof Vest To prevent robberies from bank messengers a steel vest has been invented to hold bundles of money or se- curities. Locked and con- cealed on the waist of a messenger, it cannot be opened until he reaches his destination. The vest is claimed to be bullet- proof as well as burglar-proof Takes Movie Snapshots Weighing only 414 pounds this automatic motion-picture cam- era can be carried easily on picnic outings, to record the day’s adventures. It has a uni- versal focus lens that eliminates the necessity of adjust- ing the camera for dis- Power from Wind silted ‘ tance. In using the ; . P - > it is lifted to the A new windmill designed re- » psa a cently in England to produce eye and a button pressed. This turns an invisible crank either for motion- pictures or for “stills” greater power is based on ex- periments on aerofoils and air- sctéws. The metal blades of the windmill are curved like a bird’s wing. A hoop encircles the tips of the blades, confining the air and preventing what are known as “end losses,” a com- mon failing with the ordinary windmill Tractor Aids in Thrilling Rescue When the U.S. Submarine S-19 grounded re- cently at Nauset Beach, Cape Cod, the Coast- Guard Station there made effective use of a small tractor in launching the lifeboats in heavy seas. The above photograph shows the grounded submarine receiving a watery broadside. At the left the tractor is seen pulling a lifeboat, prepara- tory to launching it. In the rescuers’ first at- tempt to reach the submarine, their surfboat capsized. A second attempt was successful SPR ee eI OF eh ene

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This highly ornate model of a picturesque Spanish galleon of 1588 was made by Frederick Stern The design of the Monitor of Civil War fame is preserved in a con- temporaneous box model (below) showing the interior arrangement All the elaborate carving, gilt and paint that charac- terized the fighting ships of the seventeenth century have been copied in the most painstaking detail in these two models. Above is the British first-rate warship, Sovereign of the Seas, built by Henry B. Culver and sold for $30,000. At the right is a copy of the Dutch 50-gun ship Hollandia of 1660, made by E. W. Ottie POPULAR SCIENCE MONTHLY May, 1995 World-Famous Ships in Miniature Model-Makers Show Amazing Spil] A fine model of the American r r clipper ship, Fortune of the Indies, period of 1854, built by Capt. E. Armitage McCann A remarkable working model of the U.S.S. Dakota. Controlled by radio, it can be maneuvered from a shore station. It is the work of Charles A. Myers, Jr, May, ! Or : I launcl comm Uncle Firs the V. in any itself bread 21 kn The torpe mach ment to sel Yard Ea name listed phot the g

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Skill Tican ' the It by Cann model of ontrolled neuvered It is the [yers, Jr, Our Newest and Biggest Submarine WICE as large as the biggest undersea vessel ever before built in the United States, the submarine cruiser V-1, launched at the Portsmouth Navy Yard last summer, was commissioned a few weeks ago and now is in service with Uncle Sam’s Navy. First of three submarine cruisers to be built for the navy, the V-1 is designed primarily to accompany the fleet at sea in any weather and to maintain any speed of which the fleet itself is capable. She is 341 feet long, 27 feet maximum breadth, with 2164 tons displacement. Her surface speed is 21 knots, and her submerged speed nine knots. The vessel is propelled by four Diesel engines developing 6500 horsepower. Her armament consists of six 21-inch torpedo tubes, one five-inch, 51-caliber rifle, and two machine-guns. All that Remains of Junked Warships F THE thousands of tons of material in the United States battleships junked recently, under the Arma- ment Treaty, only the triple line of anchors below remains to serve as a reminder. Filed away in the Boston Navy Yard they are attracting much attention from visitors. Each anchor has a number, and its height, weight, and type are kept on file in the office of the Navy Yard. The name of the vessel to which the anchor belonged also is listed carefully. The small anchor in the center of the photograph weighs 1000 pounds. From this the weight of the giant anchors surrounding it can be judged. POPULAR SCIENCE MONTHLY Boe Marked with number, height, and weight, the anchors forma unique filing system The Great Leviathan in Drydock SOME idea of the immense proportions of the steam- ship Leriathan is given by this unusual photograph showing the huge vessel in drydock at South Boston, Mass. This was the only drydock in the United States that could hold her. Compare her size with that of the workmen at the bottom of the picture. When completed in 1914 the vessel was the largest in the world. Since then she has been surpassed in size only by the White Star Liner Majestic. Origi- nally designed to carry about 8400 passengers, Uncle Sam found room aboard her for more than 12,000 of his fighting men.

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58 POPULAR SCIENCE MONTHLY Up-and-Down Razor for Close Shaves A DOUBLE-ACTION safety razor permits a quick and extremely close shave. The beard is shaved off by the customary downward stroke, then the Book-Holder Adds to Pleasure skin is held tight with one hand while the razor is pushed upward against grain of the beard. The latter motion of the razor, shown in the photograph at the left, leaves the skin smooth. A shave with this device is said to last much longer than ordinarily, because of its unusual closeness. It is also’ claimed that, due to the razor’s double-action feature, it is much easier to shave certain spots such as the chin and the jawbone. Invents Talking Postcard POSTCARD device that tells its mes- sage not to the eye but to the ear is the invention of Charles Rammelsberg, of Berlin, Germany. With a phonographic apparatus small enough to be carried in a pocket, the inventor states that any one is able to make faithful voice records on gelatine films the size of postcards. Each record has a capacity of from 600 to 800 syllables. Humidor Box Keeps Cigars in Good Condition IGARS that are either too fresh or toy dry are restored, it is claimed, in , new type of box provided with two hinged front sections between which a moist blotter is inserted. One section is perfo. rated to permit the cigars to absorb mois. ture. If the cigars are too fresh, both sections are opened, exposing them to the air. Children’s Novel Swing Is Rowed like a Boat of Reading OR invalids and others who spend much of their time reading, a book-holder that can be held comfortably in one hand recently was in- vented. The holder is shaped somewhat like a hand mirror and is provided with a ledge upon which the bottom edge of the book rests. Two curved spring clips hold the pages flat against the support and are so arranged that the leaves can be turned readily. The grip, or handle, en- ables the reader to hold the book without discomfort, as shown in the picture below. An Automatic Nursemaid Holds Baby’s Bottle MONG the new ideas submitted to the new bureau established by the French government to foster inventions is a ‘“‘mechanical maternal arm’”—a metal jointed apparatus designed to hold the baby’s bottle at the correct angle, and so save the time of the mother. GAFER than a rowboat and giving the same ex ercise for arm and shoulder muscles, is a rowing swing, a new piece of playground apparatus. The swing moves when the levers are pulled back and pushed forward. Added momentum is gained at the same time by pushing with the feet against a swing- ing platform close to the ground. The rowers may invite two passengers to sit at the ends of the swing, and even more may be accommodated if they are small and do not weigh too many pound,, for, although supported by strong beams, the swing is built for children. Mechanical Teacher Corrects Golf Form O TEACH golf beginners cor- rect driving form, and to correct faults in old play- ers, two Indiana inventors have de- vised this curious apparatus. A player strapped in the pivoted form is prevented from straightening up, and universal joints in the device are said to teach the perfect swing. The apparatus is said to correct two of the worst faults that new players must over- come —that of drawing back from the ball or reach- ing for itin driving. th) / Strapped to the form, the golfer is held in the position that will give him perfect form in swinging and driving Port w' holes, fr in sheet Am size of screw t place. the hol ] D®™ m ing eq ingtor proved thread: were di pened fire de answer from a from d varies In « the Bi cently tools | graph couplit Fire large equips

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Jigars sh or too ed, in a 0 hinged @ moist 18 perfo. rh mois. sh, both them to t “owboat same ex- shoulder swing, a yground ng moves e pulled forward, is gained ; pushing @ Swing to the rvite two the ends yen more dated if | do not nds, for, by strong built for ‘m portable Metal Punch Has Adjustable Dies ITHOUT separate dies, this port- W able punch makes five sizes of holes, from one-eighth tothree-eighths inch, insheet metal up to one-eighth inch thick. A magazine die is revolved until the size of hole wanted registers. A thumb- screw then is tightened, holding the die in place. Inserting the right sized punch, the hole is punched with a hammer. POPULAR SCIENCE MONTHLY 59 New Thawinég ‘Torch Burns Kerosene O MELT ice and snow on construc- tion jobs, a portable thawing torch, which burns kerosene, is claimed to be a time- and labor-saver. Other uses for the torch are thawing out frozen sand or coal, taking frost out of ground prepara- tory to excavating or laying conduits, and drying sand. Danger of setting fire to wooden forms is avoided by directing the flame in such a manner that only hot air comes in contact with the wood. Automatic Door-Closer | 5 patel metal doors and gates can be opened and closed noiselessly and automatically by a newly invented device operated by a small electric motor. It is designed especially for use in banks for opening and closing the gates of safe- deposit vaults, and for large residences where the gates to the grounds are ponderous and heavy. The motor stops the door at the proper point. URING the great Balti- more fire, the fire-fight- ing equipment from «Wash- ington and Philadelphia proved useless, because the threads in the hose couplings were different. This has hap- pened quite often when the fire department of one city answers an emergency call from another, for hose bought from different manufacturers varies in dimensions. In order to remedy this, the Bureau of Standards re- cently has perfected the set of tools shown in the photo- graph to cut threads in couplings on the spot. Fire departments in many large cities now are being equipped with sets of these. Emergency Threader for Fire-Hose Couplings NEW wringer operated by electricity is made specially for photographic purposes to remove the water from wet prints. Its rubber rollers have a density said to be just right to give the correct contact for this work. Very light pres- sure is required—a factor that not only Removing moisture from photo prints with the new electric wringer Electric Wringer Aids in Photo Printing prevents the prints from being spoiled, but minimizes the amount of driving * power required. A single central press screw auto- matically sets a uniform pressure the full length of the rol- lers. It is claimed that the wringer will not buckle prints, that it in- sures uniform dry- ing, preventing the creases often caused by uneven drying, and that it greatly shortens the time required for drying. The machine is driven by a one- eighth- horsepower motor and can be plugged in an ordi- nary lighting cir- cuit. Shak New Stabilizer for Planes HE problem of automatic stability for airplanes without the use of gyro- scopes or other complicated mechanisms is reported to have been solved by a ‘French engineer. His invention is said to consist of an auto- matic adjustment of the plane’s rudders by a weak cur- rent from a small battery, and of compressed air from a small aerodynamic compressor. The appliance already has been adopted on a number of heavy bombers and is re- ported to have proved a great aid in controlling machines. Magnetic Finger Saves Trouble LONG rod with a magnetizing device on the end, controlled by a thumb switch on the handle, is a useful tool for picking nuts, screws or other bits of metal out of parts of machinery where they have accidentally fallen. The rod is attached to an automobile battery terminal and can be bent to any shape. It can pick up two pounds ata time, and works in grease, oil, or water.

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New Marvels in Building Towering Skyscrapers and Imposing Monuments Show the Latest Progress in Architectural Shil] POPULAR SCIENCE MONTHLY May, 1935 The University of Pittsburgh recently completed plans. for one of the world’s largest and most beautiful skyscrapers — a 52-story “cathedral of learning’’ to house the uni- versity activities. This struc- ture will cost about $10,000,- 000, and will accommodate 12,000 students. It will be 680 feet tall, a height ex- ceeded only by the Wool- worth Building and Metro- politan Life Insurance Build- ing tower in New York City Skyscraper School struction in Nashville, Tenn. will be a fine arts building and will cost about $400,000 Modern Parthenon—The world’s only permanent replica of the famous Parthenon of Greece is under con- Twenty-Story Building to Straddle Viaduct» Erection of a 20-story building on the block just north of Grand Centr}. Terminal in New York City hinges on plans by which the structure would be made to straddle a double viaduct roadway in return for closing Park Avenue from 45th to 46th streets. This roadway, running beneath: arches through the center of the new building, would lead into: broad viaducts around both sides of the Grand Central Termingd The structure probably On the banks of the Potomac at Wash- ington, will be erected this impressive _ $500,000 memorial to the American Navy, Merchant Marine, and Coast Guard. The gulls hovering above the central rock without apparent support are an ingenious piece of work by the well known designers, Begni Piatto and Harvey Wiley Corbett Second Highest Monu m ’ The second highest monument m@ world is the Jefferson Davis Memorial, completed recently at Fairview, Ky # rises 351 feet, and is overtopped Oy the Washington Monument, w ; resembles. With the park in whichat stands, it cost its builders $150,000

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1925 POPULAR SCIENCE MONTHLY 61 May, ae 5000 Loaves an Hour chemists constantly are esting the aual; gg ) Why Science Bakes Better Bread ity of the brea / 7 ODERN science has caused us to discard many of our cherished illu- sions. A few years ago, for example, the American housewife would have scorn- ed to serve “‘baker’s bread,” because she believed the homemade kind much more nourishing. Now, though, of about 50,- 000,000 loaves consumed in this country every day, much less than half is home- made. Chemistry, engineering, and other sciences have eliminated the guesswork from the baking industry, and com- mercial bakeries now offer bread of such uniformly high quality that even the old- <—« Trough of Dough — housewife has been converted Oo its use. When mixed, the dough is On this page we take you through a discharged automatically into modern bakery, letting you see for your- a trough for rising. This : process is conducted in a self some of the wonderful things that room where temperature and science has done to make the bread you humidity are controlled eat “‘the staff of life’ in fact.

400 Loaves a Minute The dividing machine automatically cuts the dough into uniform loaves , at the rate of 400 loaves a minute Photos © Ward Baking Co The divided dough is shaped in the molding machine, then placed automatically into an endless series of pans that are ’ placed on a traveling rack that carries it to the steamproofer Preparatory to being baked in the huge traveling ovens

Traveling Oven -—When the dough in the pans has risen, it is discharged into the traveling bake- oven shown above in rows of sixteen. Here more than 5000 loaves can be baked in an hour <—«Ready to Eat—After the bread is baked for 35 minutes, it- goes into the cooling room, whence it passes on a traveling belt through a machine that wraps it up and seals it in waxed paper

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SS ar ae na i TC ONS OES i Ait ssn ge ining eS EN on a a ED TE Electric Horse Made Famous by the President EW affairs of state have caused more discussion than the recent news that President Coolidge owned an electric exercising horse. In the photograph is shown the kind of ‘‘animal”’ on which the President takes his daily ride. A one-horsepower motor drives the mechanism that reproduces the motions of a horse. It is started by turning a switch on the “‘head” of the horse. The action is made up of backward and for- ward, and up and down motions. Two levers control the speed and motion, so that the rider can go either slow or fast, gallop or trot. Thus the muscular exercise obtained in horseback riding is duplicated mech- anically indoors. POPULAR SCIENCE MONTHLY Curious Device Measures Air Circulation ERHAPS the oddest instrument ever devised to measure the condition of the atmosphere indoors is the little “‘ani- mal” pictured below. Placed on a table or desk, it not only registers the tempera- ture and humidity, but it tells the amount of air circulation by the beat of red liquid through the glass tube suspended be- tween the mouth and the tail. The rate at which the liquid moves back and forth in the tube is counted. The only motive power is the evapora- tion of water contained within the device. The more the evaporation, the faster it moves. Reference to a table tells whether the air motion in a room is too great Observing motion of the air-tester or too little for any given temperature. Thus, if the temperature of a room in summer is 76 degrees and the device is making only 15 strokes a minute, instead of a minimum of 24, it signifies that more air circulation should be obtained. Auto Wash-Basin Has Hot and Cold Water Runningboard wash-basin and vacuum tank that supplies it UNNING hot and cold water in a wash-basin attached to the running- board of the car is a luxury made available to the dusty summer tourist by a recent invention. This ingenious water system includes a reserve water tank under the rear seat of the car, and a small vacuum tank that draws from this reserve and feeds the water by gravity into the wash- basin. Two pipes run from the vacuum tank to the basin. One is for the cold-water fau- cet. The other carries water into the engine-cool- ing system, where it is heated before passing to the hot-water faucet. The overflow and vapor from the cooling sys- tem pass to the reserve tank. ; May, 1925 A Handy Washboard i New | Traveler or Student C palo into a suitcase, a small wash. UTI board recently put on the market can comes in handy for a traveler. The hand table wit slips through a canvas strap at the back N. Batte of the board. Its size makes it eon. The t venient in washing small articles in wash. easily In basins. toolcase Many a student saves laundry bills by hinged t the washbowl method, and this little will be device comes, also, to his assistance. pounds. Iceless Refrigerator for Outd the Motor-Car picmnenenes the cooling process of A’... evaporation, a sanitary water-carrier | and iceless refrigerator that can be carried =. on the side of an automobile recently has " The been designed for use by motor-campers. canvas | It consists of a special container in- closed in a linen bag suspended between the top of the car and the runningboard by a strap and tension springs with claws The water-carrier and its uses ; that hook over the edges of the running: board. The cooler will hold five gallons of water, and is fitted with afaucet. (Note the insert above.)

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BY, 1925 New Folding Table Adds to Camping Comforts UTDOOR dining comforts for auto- 0 campers are provided in a folding table with side benches invented by John N. Battenfeld of Kansas City, Mo. The table can be folded and carried easily in the hand, or it can be put in the toolease of an automobile. The parts are hinged together at one end so that none will be lost. Each seat will hold 1200 pounds. Qutdoor Dressing-Room in POPULAR SCIENCE MONTHLY Electric Hedge-Trimmer Saves Time and Labor FoR trimming long stretches of hedge where electric current is not available, this portable hedge-trimming power outfit is especially useful. A two-horsepower, air-cooled gasoline engine is connected directly with an electric generator that supplies current for the clipper. Often it is not convenient on account of terraces or shrubbery to take the generator close to the hedge. For such conditions several hundred feet of extension cord is provided. The gasoline engine and electric gen- erator are mounted on a small four-wheel Automatic Bank Teller Encourages Thrift T° ENCOURAGE thrift among its employees, a New York motion~ for 4 jt picture distributing concern recently in- a Small Bundle Gee} oe a stalled this ingenious automatic bank é ; : Ache te teller in its offices. cess of N oigsingeed — a a a —*. — The employee deposits whatever carrier oe aire pace Ree ral agian a se he ti phe aie - envelope, -earri _ ; ; , cin whine a and places it in the machine, receiving a ey be venience of auto pee ogg ttachi iit aaalitialiaaalaaiiiaaea receipt showing the amount of his deposit. ampers, The room 1s ma a S te ne "hie truck that can be rolled from place to This receipt he takes to the bank, where ner in canvas covering to a steel frame. 'S place where it is needed. _ he is credited with the amount of his yet ween It is claimed that with this power outfit savings in a bank-book. ; gboard from 300 to 500 feet of hedge can be The contents of the machine, of course, trimmed on the top and sides inan hour. are turned into the bank. h claws het How the dressing-room is folded New System Speeds Up Refuse Collection REMARKABLE new system for speedy col- lection and disposal of city refuse uses horse-drawn con- tainer units in which the refuse is collected. These are driven to a central sta- tion, where they are loaded aboard motor lorries by means of motor winches and lifting ramps and car- ried to the disposal plant. collapses into a compact bundle. When set up, a portion of the frame forms a convenient seat in the interior of the little dressing-room. How the refuse container unit is loaded and carried on the motor lorry

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A place for the broom, vacuum cleaner, mops, and other cleaning equipment is found in this convenient kitchen cabinet. There are shelves for soap, oil and powder Threading a needle is made easier if one has a spool holder like the one illustrated. A metal spring clamps around the spool, hold- ing it while it rotates. The loose end of the ‘ thread is pulled through the needle’s eye This new can-opener (at right) cuts a can like a pair of. shears. It sharpens knives and removes. bottle caps Aan ST An ordinary iron- ing-board has the advantages of a built-in one when attached to this fix- ture screwed to the wall of the kitchen POPULAR SCIENCE MONTHLY burning pies. asbestos, which prevents baking too fast With this new pan there is little danger of It is made with a layer of None of the nutmeg that fits in the little box of this grater is wasted. It is grated by pushing box back and forth This simple invention, a screw pressed against the window-frame (at right) keeps the window from rattling in the wind. The base in which the screw rests is fastened to the sill ‘ Re Thy . s May, 195 No burnt toast with this automatic toaster. One sets a dial as on a telephone, When it has revolved back to normal position, the wings of the toaster tip back > A side handle on this egg-beater, which fits the palm of the hand, makes it convenient to hold. A guard over the large gear protects the thumb while the beater is in use. The large size of the gear ensures speed May; Ingenious New Waysty! L Lhese Novel Utensils and Method, Ai Brore9o

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lay, 1995 to hods ith this ed back m, the tip back POPULAR SCIENCE MONTHLY 65 May, 1925 Lighten the Housework Are Designed to Save Time and Labor a> For handling hot plates or lifting hot pans from the oven or stove, a folding holder made of two wire grips is convenient An all-round household servant is this sturdy little electric motor on rollers. One motor for all the household labor- saving devices was the inventor’s object One turn of the crank makes short work of preparing the breakfast grapefruit. Curved knives cut the fruit from the shell and remove the core A flat piece of composition rubber glued to a handle makes a con- venient powderless knife-cleaner. Knives are cleaned by rubbing One handle of this opener holds the can in - place, while the other cuts the top in a circle. A twisted spring, fitting over the In this way there is no danger of injury spout, and hooked around the handle ‘of the teapot prevents the lid from slipping and falling into the teacup A sanitary griddle greaser (above) spreads grease with a piece of material similar to lamp wicking. This can be removed for washing Sugar lumps will not drop un- expectedly when in the firm grip of these improved sugar-tongs When not in use, this baby chair folds flat beneath the table top. The sup- porting steel rod is crooked so that the table-cloth will hang straight down For keeping windows open at any height the metal window lock at the left was devised. Fastened on the upper sash by means of small prongs, it acts as a wedge when the lower window has to be raised

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How the hinged frame holds the typewriter in a perpendicular position "© K.& H POPULAR SCIENCE MONTHLY May, 1925 Handy Frame for Typewriter Fok the small office where space is limited, a fra ment for the desk, that lifts a typewriter up an way when not in use, gives more desk room. Th fixed to a wood base, which fits in a metal frame. This piv on fixtures attached to the desk. A steel rod falling into — in the fixtures holds the machine in an upright position, ] 0 ing the top of the desk clear. ae me attach. d out of the € machine is Photographs Developed in Daylight OPSY-TURVY methods of developing photographic films and plates, by which the process is carried out in da light instead of the darkroom, and the film is placed jn the fixing bath first, then in the developer, are possible as the result of recent experiments made by Dr. Henry Leffman at the Wagner Free Institute of Science, Philadelphia. The daylight method, using a special developer, should be a distinct advantage. Rubber Base Is Cushion for Telephone Instrument A RUBBER basé for a telephone keeps it from skidding on glass-top desks and acts as a cushion to prevent noises Fitting the base and vibration in the phone. The bases are made in several colors to harmonize with office desks or tables. A flexible rubber rim around the top of the base is de- signed so that the base of the telephone can be inserted under it and held firmly, so the device be- comes a perma- nent mounting. ‘Three-in-One Brush Cleans Typewriter Thoroughly [NCLUDING three brushes in one, an improved typewriter brush is designed to reach all parts of the machine that require thorough cleaning. to a general cleaning brush of soft camel’s hair for dusting between the keys and type rods and under the carriage, there is a stiff rotary brush for the type and a pointed brush for reaching out-of-the- way places that accumulate dirt. In addition Useful Slide-Rule Holder TIME-SAVER for the engineer is this handy slide-rule holder. rule is set at an angle at which it can be read easily, and the holder has a rubber base to prevent its slipping on a smooth desk top. Only one hand is needed to operate the rule. Internal coilsprings hold the upper part of the holder firmly against the rule. Ingenious Telephone Pad Uses Paper Rolls OLS of adding-machine paper can be used in this device, making a useful pad for telephone messages. As slips are written they can be filed under the cover, A cutting device aids in tearing the paper, On the under side of the cover is a card for recording important telephone num- bers for convenient reference. The Placing memoranda under the cover — THE high price of olive oil has resulted in the manufacture of numerous vegetable oils as substitutes among which corn oil, one of the newest, ranks with the most important. Tabulating Machine Cuts Labor in Half ACHINE tabulating methods usually have required at least two opera- tions—one of the original entry, the other of transcrip- tion to unit item cards. One of these op- erations now has been eliminated by a transcribing ma- chine attached to the typewriter electrically and operated by the typewriter keys. Thus the labor and cost of tabula- tion are cut in half, it is claimed. The machine can be operated from any light socket. Attached to the typewriter electrically, the - new tabulating machine transcribes the original as the typewriter keys are pressed How the tabulator is operated in connection with the typewritet May, 192 Du} YPE pay fected b; His dev! paper rc the tyPé with du The 0 ment th cash rev Mic NE | the in 1894 from a § line to gage of Steel B FA thi with a P is a wel sticks tc To fo been de screwed The pro FO pa | size of a hand is

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AY, 1925 er attach. ; Of the hine ig ‘Pivots C0 slots l, leay. ht ic films in day- in the e result at the ould be Pad r can be a useful slips are e cover, é paper. 3 a card 1€ num- cover — resulted egetable corn oil, he most If lly, the - yes the pressed May, 1925 Duplicates without Carbon YPEWRITING multiple copies without the use of carbon paper has been made possible by a recent invention per- fected by Max E. Melton, an employee of the U.S. Post Office. His device is attached to a standard typewriter. It consists of r rolls ingeniously arranged so that as the paper is fed to at typewriter platen the sheets are automatically interleaved with duplicating ribbon. The invention, it is reported, is expected to save the govern- ment thousands of dollars a year. The inventor has received a cash reward for his efforts. Midget Railway Is Duke’s. Toy NE of the world’s oddest narrow-gage railways is owned by O the Duke of Devonshire at Eaton, England. It was built in 1894 for the purpose of transporting supplies to Eaton Hall from a station four miles away. Now it is used as a passenger gage of the railroad is only 15 inches. POPULAR SCIENCE MONTHLY ine to transport the Duke’s guests about the estate. The Max E. Melton, postal employee, sitting before a typewriter equipped with the ingenious duplicat- ingattachmentthat he invented. With it, copies can be made without carbon paper Steel Prongs Guard Mail- Boxes from Thieves FAVORITE trick of the letter-box thief is to fish through the slot with a piece of string, on the end of which is a weight smeared with adhesive that sticks to the letters. To foil his efforts there recently has been devised this screen of steel prongs screwed inside the box just above the slot. The prongs make it practically impossible i How steel prongs guard the letters to pull a letter through the slot, although it is easy enough for the postman to inser the letter. ; FOLDING stool that can be |@e packed into asmall case about the {fj size of a cracker box and carried in the hand is adaptable to a wide variety of The folding stool in use (left), and packed in its case Flexible Arm Holds Phone ONE of the ingenious inventions dis- played at a recent business exhibi- tion in London was a new telephone at- tachment that enables a stenographer to have both hands free. A long, flexible arm, rising from a base on which the telephone instrument rests, holds the receiver to the listener’s ear. Portable Stool Folds into a Small Box uses. When un- folded, the legs of the stool are ex- tended to a com- fortable height and held firmly by cross braces. This invention is designed espe- cially for use by artists. It also might be useful for spectators at athletic games, parades, and other events where there is “standing room only.” It would be found useful, too, at picnics, lawn parties, or indoors. It is light to carry and can be packed in a moment. This Boudoir Lamp Holds an Alarm Clock T IS never too dark to see the time if one has a clock in the base of a lamp. This unique combination of two house- hold necessities is the invention of Mrs. Helen Carr of Buffalo, N. Y. The clock is provided with an alarm and is so placed that the light above shines upon it. The lamp is particularly adapted for use in the boudoir as it is made usually in decorative de- signs such as the one at the right. Lamp with clock This Simple Paper Punch Simplifies Binding PUNCHING holes in filing sheets in such a way that the ring fasteners of a binder will fit into them exactly without bulging the paper is a troublesome task that has been simplified by this con- venient punching device. The result has been obtained by three _ small punches sliding along a rule by which the correct distance between them can be measured accurately.

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Tire-Changing Simplified Changing tires on the road is simplified, it is claimed, with a newly invented rim lock con- sisting of a working lever that can be attached to any rim. A pull on the lever reduces the circumference of the rim and releases the tire Light Deflectors for Night Driving Night driving is made safer, it is claimed, with these new de- flectors, which turn headlight beams from the left to the right side of the road. They are controlled from the dashboard, so that when ancther car approaches they can be moved in- stantly, throwing the strong beams of light against the curb ft Anti-Glare Another new form of anti-glare lighting system consists of five lamps with mag- nifying glassesplaced directly under the body of the car. The lampscast directrays on the road beneath the vehicle, throw- ing the car into clear view from all sides. Dim head- lights are used with the magnified lights POPULAR SCIENCE MONTHLY May, 1925 Usetul Inventions New Time-Saving Tool; Windows Replace Side Curtains Clear, unobstructed vision on all sides is pro- vided by a new type of inclosure for open cars in which glass window panels replace the usual celluloid side curtains of the touring-car For Motor-Boats Any Ford engine can be con- verted into a power plant for a motor-boat with the attach- ments shown above, including a propeller in place of the fan ee New Mechanical Tire-Changet This speedy tire-changer for garages consists of three jaws provided with hooks that grip the rim. When the jaws are moved inwardly, # split rim contracts, thus releasing the i

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le The tugging bulldog, the graceful crane in flight, and the winged human figure, typifying speed and power, were novelties in radiator caps recently shown in Paris the May, 1925 for the Car-Owner and Handy Accessories — Trunk, Bumper and Tire-Holder Auto trunk, rack, tire-holder and bumper all are combined in one compact unit in a newly devised attachment for the small motor-car. It is attached by means of steel arms fas- tened to the frame of the car by shackle bolts Odd Caps Heavy-Duty Saw Driven by. Tractor Here is a heavy-duty power saw that can be attached to a Fordson or in five minutes, the makers claim. The ring is supported from front axle and the heavy saw is driven by pulleys from the engine POPULAR SCIENCE MONTHLY Inflator and Gage Combined Air pressure in tires is measured auto- matically by a newly invented inflator that has a small pressure gage that is easily read inserted in the air-delivery tube One-Finger Hood Lock A new hood lock of the eccentric type permits the lock to be operated easily with only one finger, so flexible is it Electric Switch Opens Garage Doors This ingenious garage-door opener consists of pull chains that operate an electric switch. This in turn starts or stops a motor that operates the doors No Rattling The demand for noiseless, non-rat- tling windows for closed cars has brought about the development of a felt-lined channel for frameless glass (at the left). The cushioning material within the metal channel is held in place by small barbs punched in the sides of the channel, as shown in the dia- gram, and thus pre- vents rattling

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70 POPULAR SCIENCE MONTHLY May, 1925 Time-Saving Kinks for Car-Owners How You May Solve ID you ever stop to think what a tiresome job it is to cut the paper wrappings away from a new tire— especially when on the road and time is at a premium? Figure 1 illustrates a quick method the writer observed being used in a garage by an expert tire- changer. He simply held the tire a couple of feet from the ground and then slammed it down as hard as he could. he A valve lifter is employed in regrind- This was repeated several times at dif- ing valves, sometimes the spring jumps ferent points on the tire, and the paper out and one has a “ wrappings broke and fell off.—L. B. R.

picnic” trying to ON MY desk is a warning circular from an insurance company to keep a garage door open when running a motor in the garage. As there are occasions, during chilly weather, when it is not com- fortable to work with the doors open, I have installed a light-weight pipe, of tin or iron, as in Fig. 2. This may project through the door or the side wall. It is set over the end of the exhaust pipe of the auto. The small opening through the door can be pro- tected against heat by a supporting collar, and the opening may be closed when not in use by a pivotel or

sliding cover. 4 wate t > DOOR Fig. 1—By bouncing a wrapped tire forcibly by a ven & on the ground, the paper is broken quickly device of this 4 1 kind, one can * vs ¢ idle his engine a mill

indefinitely without danger. } Furthermore, in C) winter a_ small ‘ : unheated garage A EY can be warmed EXHAUST GAS ° PIPE

SAFETY PT COLLAR

yf

Fig. 2—Outlet pipe ae through run- carries off exhaust oe SSH ning the engine. gases when engine is aoe laagew eae ; c D.D on E idled in the garage to choke rod of the SQ —C. D. DIVINE. truck aids in driving S Wh) through heavy traffic

/

// ~

fi A FRUIT peddler, using a Ford one- ton truck with an inclosed cab, utilized the simple but ingenious scheme shown in Fig. 3 to operate the engine choke without taking his eye off the traffic or his attention from the

Common Auto Problems replace it. Figure 5 shows a simpl device I use, which allows the valve tobe removed without a lifter and without i danger of the spring’s jumping out 4 is merely a piece of brass tubing with a slot cut out of its side. When the tubin is slipped under the spring-retainin washer, it holds the spring compressed when the engine is turned over by hand and the cam dropped. The pin then can be removed from the stem, and the valye taken from the engine block for exami- nation. When the valve is ground, the pin is replaced, and the cam raised. The tubing then can be removed. This simple little device, you will find, will save ag much as half the time required for valye grinding. —W. M. -* ENAMELING black the lower half of each headlight bulb, the headlights on an automobile can he made to give a brilliant light without any dangerous glare (Fig. 6). The principle is that the light radiating from the bulb strikes the upper half of the headlight mirror reflector and then is reflected to the road.—K.B.¢, [N FIG. 7a method is shown for adapt- ing a heavy split cotter key to serve as a valve- grinding tool. The sketches 1 to 5 show the order of oper-

WIRE WITH LOOPED ENDS ations in making the grinder. Fig. 4— Using a piece The cotter is held of heavy wire to com- . : ’ press a piston ring in a vise while the tips are filed. Care must be taken to file the tips square, not bev- eled, as a square corner does not slip out. The tool ‘is held in the chucks of an ordinary bit brace.—E. B.R. OMPRESSION leaks in the motor

wheel. When he drives through heavy traffic with a cold engine, instead of leaning forward to choke the carbu- retor, he merely bears down on the cord with his left elbow. That raises the choke rod.

SECTION SAWED OUT

of a car can be located quickly by the use of an oilcan filled with engine lubricating oil. With the engine run- ning, place a drop of oil on every sus- pected point, such as the porcelain of a spark plug, on the edge of the gaskets around the cylinder-head bolts, and

W HILE overhauling my <a * Fig. 5—Valve grinding Fig. 6—-Lower half of cently, I was confronted with is simplified by the headlight bulb enameled the problem of inserting the pistons use of a spring holder black to eliminate glare into the cylinders. I tried the stunt shown in Fig. 4, with success. A piece of fairly heavy wire was twisted to form a loop at each end. @) LH VG One loop was ‘placed over one of the pei, in” cylinder-head studs. The wire then was OF END END FILED wrapped around the piston ring in the manner indicated. By inserting a screw- pressed and the piston pushed into the | 2 3 4 cylinder. This method did the trick in Fig. 7—tepe in making a vaive-grinding driver into the loop at the free end and prying against a stud, the ring was com- surprisingly short order.—C. M. W. tool ‘from a heavy split cotter key itself when the oil is drawn into the cylinder and burned, because a puff of smoke will show itself. This simple method will prove effec- tive when other expedients fail. GLirs of the rear tires that cause them to wear quickly, may occur in three ways, according to tests by Prof. E. H. Lockwood of Yale University. They may be due to a slow displace ment caused by the elasticity of the rubber, to an abrupt jump when the tire momentarily leaves the road, or to a spill or skid when the tire loses its traction a slippery road. similar locations. The leak will reveal -

which rebori with | the m the la “ Or For new f have | the tr The the m throu; goonel pany- or the belt ¥ course the w lacing and t the ov tually issuin when he for of wa radiat out t] nectic with even tempt toget} he bo Yor lasted aged | of m becau expar cours: Ne Rath thous it we every shop not i ignor is pro world reck]

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1925 ‘S ns imple to be t any Rat ith a ubing Lining ressed hand Nn can valve xami- d, the The simple 1Ve ag valve lower b, the ‘an be ‘ithout . The liating er half or and .. Bw. Feo od is adapt- ry split ey to _valve- ool. etches ow the oper- making nder. r is held » while re filed. ust be ot bev- not slip ucks of .B.R. > motor ckly by . engine ine run- ery SUS elain of gaskets ts, and ll reveal into the , puff of ve effec: I. se them in three f. E. displace- of the the tire Lo @ spin ction on May, 1925 Important Things [ Have Learned about YOUR How to Save Big Repair Bills by a Few Simple Precautions As Told by a Garage Owner out of town paid me a bill of about $125. The bulk of the work for which the charge was made consisted of reboring a scored cylinder and refitting it with piston and rings. To me, though, the most interesting item on the bill was the last, and one of the smallest: “One fan belt and fitting same, $1.25.”’ For neglect to supply that car with a new fan belt—even a new lacing might have been enough—was the cause of all the trouble. The owner of the car had noticed that the metal lacing of the belt was cutting through the leather—a sure sign that sooner or later they would part com- pany—but instead of replacing the belt, or the lacing, he merely tightened up the belt with the adjusting device. This, of course,. just put an additional strain on the weakening leather, and one day the lacing cut clear through the belt, and the fan ceased to revolve. \ FEW days ago a car-owner from HIS happened somewhere on acountry road. Just where, the owner doesn’t know. Eventu- tually, though, he saw steam issuing through his hood, and when he got out to investigate, he found that a couple of gallons of water had boiled off from his radiator, the steam being forced out through the lower hose con- nection. He had no materials with which to make repairs—not even a piece of wire—so he at- tempted to hold the fan belt together with a couple of hairpins that he borrowed from his wife. You can guess how long that “repair” lasted! By various makeshifts he man- aged to get the car to within a few blocks of my garage. Then the car stopped use one piston was “frozen” by expansion to its cylinder. That, of course, was the cylinder we had to rebore. Neither was that an extreme case. Rather, I’d say, after handling many thousands of cars in the last several years, it“was almost typical. For in nearly every case where a car is brought to this shop for extensive repairs, the fault lies not in the automobile itself, but in the ignorance or neglect of the owner. There probably no article of equal value in the world that is treated so carelessly and so recklessly as the average automobile. There; Take the matter of lubrication. POPULAR SCIENCE MONTHLY CAR are some 60 es- sential parts of an automobile that require either oil or grease at in- tervals that. vary roughly between every few days and every few months. Every car-owner has received from the manu- facturer an instruction book that explains by means of a simple pictorial diagram just where and just how often oil or grease must be applied to the car. Oil companies also send out similar charts, and publish booklets and advertisements telling exactly what grades of oil and grease are required by different makes of automobiles to get the best results. Where You Can Save Money Don’t let the dust gather in this corner of your garage. By following the lubrication chart that comes with your car and applying oil and grease where and when the chart specifies, you will save yourself a lot of unnecessary trouble and expense and keep your car in use longer There is, in fact, no reason why every car-owner should not know everything about lubricating his car, which is a simple job, though not the most pleasant in the world. Not more than three cars in 10, though, as far as I can judge from those I see, are properly lubri- cated. Not long ago one of my customers noticed that the oil gage on his dash- 71 board was not working. He was in a hurry to go somewhere, so he paid no attention to what should have been a warning. He got through the day with- out mishap, and continued to drive his car for about a week. Then one day the car began to behave like a _ bucking broncho, and he brought it round to us for an inspection. The reason the oil gage hadn’t worked was that the pump gears were worn, and, of course, oil hadn’t been circulating through the motor. If he had brought the car to us immediately, we could have repaired it for about five dollars. As it was, though, it cost him more than $100 in labor and materials to replace burned-out bearings. NOTHER man heard a little noise in the rear of his car and paid no attention to it, even when it grew louder. In fact, he didn’t run the car into the garage until it showed unmistakable signs of readiness to quit for good and all. We took down the transmission, and found what might be described as a pile of powdered steel sawdust. It’s almost unbelievable, yet this man, who had an instruction book telling him to fill his trans- mission case with a certain grade of grease every 3000 miles, had never inserted an ounce of grease in the two years he had owned that car. Small wonder that the gear teeth began to break off, circulate through the mechan- ism, and ‘‘chew up” everything within reach! His repair bill was about $75— and less than a dollar’s worth of grease would have saved it all! Another man paid me around $30 recently for a new spring and for resetting the spring on the opposite side that went out of shape when its mate broke. An- other case of failure to lubricate! Any mechanic could have spread and oiled that spring in 15 minutes when it first began to squeak. I sometimes think it’s too bad that most cars aren’t equipped with non- adjustable carburetors or with some kind of locking device that would make it

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72 impossible to change the adjustment, once it was made by a competent me- chanic. Haphazard tinkering with car- buretors by people who don’t know what they’re doing causes more trouble than you’d ever imagine. I wish I had a small percentage of the cost of the gasoline that’s consumed unnecessarily every year, due to improper carburetor adjustments! The carburetor is easily accessible and you need no tools to monkey with it. For that reason it’s usually the first part of the car that the average inexperienced dri- ver starts to play with when his car begins to run badly. A man in my town bought a second-hand car a few months ago. It was in good condition, and he drove it without trouble for several weeks. Then one day on the road the motor began to lose power and to miss and cough. The owner didn’t know what to do about it, and was standing ‘by help- lessly when another motorist stopped beside him and asked if he could help. The man who was in trouble explained what had happened, and the other, without making an inspection or a test of any kind, announced immediately that the trouble lay in an improper carburetor adjust- ment and that he could fix it. E DID fix it, too. He gave the gas. adjust- ment a couple of turns, and the car immediately began to hum like aracer. The owner completed his trip, then when he got home, related his experience to a neighbor. This latter had been driving for about a year, so, of course, ‘knew everything about automobiles.” He de- cided that he ought to iook over the work the volunteer repairman on the road had done, and was very gleeful when he dis- covered that the filter in the top of the vacuum tank was clogged with sediment. “See, your trouble wasn’t in the car- buretor at all,” he reported, removing the filter to clean it. IKE many amateur repairmen, how- ever, he forgot something—to re- adjust the carburetor to compensate for the greater amount of gas that was being fed to it through the clean filter. The result—one of them, anyway—was that the owner of the car ran out of gas about a week later 10 miles or so from home. The car had been giving from 15to16 miles to the gallon; now, though, with the new carburetor adjustment, it was giving only seven, and he found himself without gas when all his calculations indicated that his tank should have been half full. Of course, he had to pay for having his car towed in from the road; also for the removal of carbon from the cylinders, for the excessively rich mixture he had been using had caused his motor to carbonize alarmingly. All of that expense and trouble could have been obviated by spending about 75 cents to have that filter cleaned and the carburetor properly adjusted. Batteries supply an enormous annual Test Your Battery It is a simple matter to have your battery tested and sup- plied with water regularly; yet by neglecting this, thou- sands of motorists cut short the life of their batteries POPULAR SCIENCE MONTHLY list of unnecessary casualties. A good storage battery on a car that is run regularly ought to last for years. Few of them do, however. Not a week ago I replaced a $25 battery that was only a year old. Never once had the owner put distilled water in it, nor tested it, as he might have done with a50-cent hydrometer. Any garage or battery service station would have tested it for him and added water for 25 cents, or charged it for him when it was neces- sary for about two dollars. He neglected it, though, with the result that, after a few weeks of idleness, the bat- tery proved incapable of turning the motor

Know Your Car EMOVING tires from rims is a dreaded job that bruises hands and ruins good temper. Special tools have been devised to make it easier, but the average car-owner cannot afford them for individual use. He, therefore, leaves his tire-changing work to service stations. Yet it is possible to do this work yourself easily without special tools if you give proper attention to the rims and lugs. The difficulty of changing tires depends almost entirely upon the condition of these parts, that ordinarily are neglected. To facili- tate tire-changing, observe these pre- cautions: 1—Sandpaper the tire bead surface of the rim and shellac it with a thin coat of shellac. 2—Rub the tire beads with flake graphite, applied with a cotton pad. 3 —Clean the bearing surface of the rim, the wheel rim and the tire lugs, removing rust, and smear a thin coat of graphite grease on these surfaces, including the bolt threads. With the surfaces prepared in this way, and the use of a well-oiled jack, tires will slip readily from rims.

Oil Cheaper By remembering to keep the crankcase well sup- plied with oil, you will save yourself the cost of burned-out

May, 1925 over. When we inspected it we fo its plates so badly sulphated that it useless to attempt to charge it op BA it. Why any one should prefer to fe from $10 to $40 for a new battery ae than from two dollars to five dollars “ed needed battery service, I can’t und < stand; yet they do it. “és Almost any set of 5 tires sold today ought wine between 15,000 and 20,000 miles, How many motorists, though, can boast of getting any such tire mileage? Once again igno- rance and carelessness are to be blamed. To get 15,000 Miles at least, out of a tire, it is neces. sary only to supply yourself with a good gage, to keep the tire pumped up to the pressure specified by the manufacturer and to repair all small cuts as soon as they occur, FR ECENTLY an indignant customer came to me complaining that a cord tire I had sold him had blown out at the end of 4000 miles. I gave him a new tire, but actually he didn’t deserve it. On one of his first trips he had gashed the side of the tire by running over a trolley switch. He made a great point of the fact that the blowout had not occurred at the place that was cut. Nevertheless, the cut was responsible, for moisture, entering the fabric through the break, had traveled along with- in and settled at the place of the blowout, gradually rotting the fabric away until at last a sudden jar caused the rubber casing to give. Those small cuts, to which the average owner pays no attention, frequently result in expensive tires blowing out before the tread shows any appreciable wear. They are caused generally by sharp stones on macadamized roads, steel slivers in car tracks, and the rough edges of curbstones. You should inspect your tires at least once a week, and if any small cuts are disclosed, the break should be cleaned thoroughly with gasoline and repaired with rubber cement. Either that, or have the place vulcanized. bearings ACKING into a curbstone may bruise your tires so badly that a coupled thousand miles are taken from their life. Scraping the curbstone may produce 3 similar result. Misalinement of the front wheels, which causes the tires to wear on the relatively thin sides, likewise soon may make them ready for the scrapheap. A man who keeps his car at my garage recently destroyed an expensive balloon tire because his brake rods were improp- erly adjusted. The right-hand wheel was doing all the braking, with the result that the tire wore out in record time. How many cars are ruined almost irreparably every year because ignorant owners drive them too fast when new,! wouldn’t care to estimate. The mat with his first automobile is more likely “drive it to death” than the man who ha owned cars before. (Continued on page 135)

= & ah the wrol is a stati cept pow trou equi brea resis min that systi two in 1 oper spar assis trou ferir tion engi thes | ‘the ing | meal sils | see t thin; not | For weel stati had the noor some twin tical para time duce thro cuit. presi emit muc the : into bres woul out | days In ti stati agai

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ay, 1925 found it was * Tepair > Spend ’ rather lars for under. tandard last for 10 miles, though, 1Y such IN 1gno- re to be ) miles, IS neces. yourself eep the pressure ‘acturer, all cuts ur. dignant > to me a cord lim had end of e him a ually he On one he had 2 tire by y switch. nt of the had not that was the cut moisture, “ough the ong with- place of y rotting udden jar e average requently wing out ypreciable rally by 1d roads, the rough ld inspect ind if any ak should oline and ;. Either ed. 1ay bruise couple of their life. produce & f the front s to weat wise S00D scrapheap. my garage ve balloon e improp- wheel was the result 1 time. The mat re likely an who has May, 1925 POPULAR SCIENCE MONTHLY 73 Broadcasters Have ‘Troubles, Too! What happens when a station goes dead in the middle of a program—The inside story of transmission HAT happens when a broadcast- W ing station stops short right in the middle of a program? “Must have blown out a tube,” says the average radio fan, but he will be wrong in most instances. A blown tube is a mere detail at any of the larger stations. However, a broadcast station is sus- ceptible to all the ills of a regulation power house, in addition to the many troubles that are peculiar to its own equipment. Reactors or condensers may preak down through overloading, or resistors burn out. A hundred and one minor faults may appear in apparatus that is no part of the actual radiation tem. The ideal broadcaster ordinarily has two complete sets of apparatus so that in the event of trouble the chief operator can switch instantly to the spare transmitter. Then he and his assistants can hunt for and remove the trouble in the main set without inter- fering with the program. The situa- tion was summed up for me by the engineer of one of the big stations in these words: “PFAHE man is not born who can locate and repair a fault during ‘the actual broadcasting. Broadcast- ing is like housekeeping—it is neces- sary to wash the dishes after every meal. We have to go over our uten- sils two or three times every day to see that they are clean and unbroken.” Like earthquakes and_ cyclones, things do sometimes happen that can not be anticipated or guarded against. For instance, just a few weeks ago one of the big stations in New York City had to shut down right in the middle of the after- noon program. Something went wrong somewhere and in -the twinkling of an eye prac- tically every piece of ap- paratus in use at the time, clear down to the fuses in the street, was re- duced to red hot junk through a bad short cir- cuit. Those who were present say that even the microphone in the studio emitted wisps of smoke, much to the surprise of the artist who was singing Into it at the moment. This was a really serious breakdown — one that would put a small station out of business for several days at the very least. In this particular case the * 5 i i i i D i ., with broad- station was on the air Remarkable nighttime view of Station WHO, Des Moines, Ia., with broa ae ¥FX Wi ¥tX By Jack Binns Broadly speaking, there are three main sources of trouble at a transmitting sta- tion. First, in the studio; second, in the transmitter and its associated apparatus; and, third, in the connecting telephone wires that make possible the broadcasting of outside events by remote control. The chief problem experienced in the studio is in securing audio-frequency cur- rents of correct strength. It is necessary to see that the artist doing the broad- casting is close enough to the microphone to get full volume on the weaker fre- quencies, and yet not close enough to ee f orcas met Where Programs Are Sent Out A 500-watt transmitter, showing enormous power tubes. A blown tube is just one small detail in the every-day troubles of a large broadcasting station + St=+ fo toy on Illuminated Broadcasting Towers at Night cause “blasting” on the loud tones. There is the further possibility that some trouble may arise in the voice amplifier or connecting wires to the transmitter, but such occurrences are quite rare. bee THE broadcasting apparatus proper, a number of things can happen, many of which will cause a break in the pro- gram. So far as the tubes are concerned, the possibility of filament “ blow-outs” is not very great. The engineers have sufficient data on the characteristics of power tubes so that they know when they are being overloaded. At some of the stations, the power tubes have thoriated filaments. These, of course, may drop in emission while the program is going out, but the result will mean merely a restriction of the effective area of radiation and not a suspension of operation. One of the peculiar tube troubles that may be ex- perienced is an air leak. When this happens a rush of plate cur- rent follows and the overlead relays will cut out and stop trans- mission. The greatest source of trouble in the transmission apparatus, how- ever, lies in the associated instru- ments used to apply power to the radio circuits. These are common to any electrical power house and may arise in the. transformers, motor generators, condensers, or at other points that are working under high voltage. Well designed broadcast apparatus is arranged to provide an ample margin of safety, so as to limit the possi- bility of disaster. N STORMY weather there is the additional possibility of the antenna being blown down or breaking under excessive wind pressure. Naturally, this would stop every- thing until a new antenna could be erected. If the break occurred at night, the cessation would be complete until the follow- ing day, for it is practi- cally impossible to put up a large transmitting an- tenna in darkness during stormy weather. Since the development of remote control, the life of the station operator has been one of constant worry. At any moment some line trouble may cause an in- terruption in the program. Yet despite handicaps, again in 3 z casting towers illuminated by floodlighting projectors. Breaking of the antenna remote control has be- ain in just 12 minutes. during a severe storm may be the cause of a serious interruption in the program come highly successful.

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POPULAR SCIENCE MONTHLY May, 1925 An Ideal Long-Distance Receiver for the Radio Beginner By Alfred P. Lane HIS one-tube receiver should ap- peal to every radio fan. It is simple to build, easy to tune, and gives remarkably fine results. Distant stations are brought in with a clarity and volume not exceeded by any other type of regenerative receiver, and in this respect it seems to be better than any of the popular hook-ups. The selectivity is also of a very high order. All of these advantages are the result of a new method of obtaining regeneration— a way that absolutely eliminates the dis- tortion so common in ordinary circuits when regeneration is pushed close to the oscillation point. With this circuit, added regeneration simply increases the volume right up to the point where the tube breaks into oscillation. The secret lies in the fact that no audio-frequency currents are passed through the tickler coil, so that all regeneration is obtained at radio frequencies. Distant stations can be brought in with ease when conditions are favorable and the various stations always come in at the same dial settings because regeneration, as obtained in this circuit, has no effect on the wave-length adjustment. NY type of tube may be used. The receiver illustrated was carefully tested with six-volt storage-battery tubes, three-volt dry-cell tubes, and 1%-volt dry-cell tubes. Several different distant stations, including KYW of Chicago, could be tuned in with any one of the three types of tubes. In varying the tubes no change was necessary except a slight readjustment of the wave-length dial (at the left) to compensate for the difference in the internal capacity of the tubes, and a new setting for the regenera- tion control dial (at the right). Of course it was necessary to change the battery voltages to suit the different tubes. The Fig. 1—Rear view of the one-tube set, showing simple layout of parts and wiring. All parts are lettered and numbered to correspond with the wiring diagrams. the parts are arranged so that nothing is in the active field of the tuning unit ABC. You can easily wind this tuning unit yourself by following the instructions in the accompanying article and in an article on coil-winding on page 76 of this issue How to Build the Most Up-to-Date One- lube getty, Notice that i 5 APA. ———. oo ——_—— —_ Fi ve D a = = H > wm aS K vod > AS a 2 62 3 4 $5 bo ANT GRD. “A +A =3 +B Fig. 3—Complete wiring diagram. For be- ginners unfamiliar with the radio symbols, a picture diagram will be found on the next page o Fig. 2—Front view of the panel, showing neat arrangement of the two condenser dials, the rheostat knob, switch, and phone jack tests were made in New York City ina locality not particularly favorable for radio reception. Storage-battery tubes gave slightly louder signals. HE construction of the receiver is exceedingly simple. There are no moving coils and the tuning unit ABC is easy to wind. This point should appeal to the amateur builder particularly, since there are no special parts to be bought. You will notice that there are two wiring diagrams. Figure 2 is for the reader who has mastered the use of radio symbols and Fig. 4 is for the beginner who does not know just how to connect the various instruments in the circuit. Blueprints Are Available for This Set ERE is described the first of a new series of radio receiving sets for the amateur builder—receivers that embody the most up-to-date refinements in radio design, yet are simple and easy to construct. Blueprints for the new Popu- LAR ScIENCE MonrTHLY one- tube set now are available, and will be found listed in the tabu- lation of our Blueprint Service on page 107 of this issue. To supplement this one-tube set, Mr. Lane next month will tell how to build a simple audio amplifier that reproduces with remarkable clarity and _ vol- ume.—THE EpiTor. The receiver is designed to be used with an outdoor antenna from 75 to 100 feet long. If you are located close to several powerful broadcasting stations where in- terference between stations is severe, @ shorter antenna, or even an indoor ai- tenna, may be used during the early evening, although such an antenna cannot be expected to bring in distant stations. You will need the following parts to construct the set: A, B, and C—Tuning unit. D and E—Variable condensers, .00025-ifd. capacity. : F—Grid condenser, .00025 mfd., with clipsfat grid leak. ES G—Vacuum-tube socket. ae H—Rheostat. I—Grid leak, 2 megohms. J—Double-circuit jack. K—Filament switch. L—Panel, 7 by 12 inches. M—Baseboard, 61% by 11 inches. N—Binding-post panel, 34 by 6 inches, cut One piece of hard rubber, composition, OF, board tubing 3 inches in diameter by 4 long. ; 4 pound of No 22 double silk-covered wife. Two 4-inch dials. 6 binding posts, brass brackets, screws, bus wire, etc. In going over this list of parts, you wil

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lay, 1925 id eC ving neat ials, the ne jack City ina rable for ry tubes ceiver is e are no it ABC is ld appeal rly, since bought. are two ; for the e of radio inner who nnect the it. used with 0 100 feet to several where in- severe, 2 ndoor ai- the early na can not t stations. r parts to , .00025-mid with clips fa ‘ii hes, tion, or, cart er by 4 red wire. screws, bus rs, you wil May. 1925 lof them are carried by dealers note a cs. The tuning unit ABC pro be purchased complete, but is . ind. simp i aise must be used on this one- tube set, although under favorable condi- tions it will operate a loudspeaker with sufficient volume to be heard in a small room. és - In the next issue of POPULAR SCIENCE MonTHLY I will tell you how to build a simple and efficient audio-frequency am- plifier to be connected with the receiver shown on these pages. D and E, the variable condensers, can be of any standard make, but the maximum capacity should be as given in order to cover the broadcast band of wave lengths with the tuning unit as specified. Condensers of larger capacity can be used if you have them already, but it will be necessary to reduce the number of turns in coils Band C. Otherwise the proadcasting stations all will come in on the lower half of the dials. If you want to use larger condensers, Mr. Senauke’s article on page 76 of this issue will tell you the correct number of turns for the coils. N PURCHASING the socket @ it I might be well to select one suitable for use with standard vacuum tubes of the storage-battery type, for several of the dry- cell tubes are made to fit this socket and adapters can be obtained for the others. The rheostat H should have a resistance of 15 or 20 ohms for use with six-volt storage-battery tubes, 30 ohms for use with three-volt dry-cell tubes, and six to 10 ohms for use with 114-volt tubes. The jack J is specified as two-circuit purposely, although the two center con- tacts are not used. Next month, when the amplifier is described, these contacts will be brought into use to carry the energy into the amplifier. All the other parts can be of any stan- dard make. It will pay you, however, to buy high grade parts where they actually form part of the electrical circuit, as shown in Fig. 4. If you intend to place the re- ceiver in a cabinet, it is well to purchase the cabinet at the time you buy the parts so that you will be able to fit the panel L to POPULAR SCIENCE MONTHLY '¢-s FF 3 & Fig. 4—This picture diagram of the wiring will aid the beginner in assembling the set Won ann aa a- === =~ — |2"-------------~----> : Ee 7 H j | 3" : | erree Weeks ae A 5 x 2 ? | } 6" ' : ¢ ° a H ! ' © | Seid, ili FO tel ea } l Loonie Bee Cee sears i y A eS DI 1-9 Se Fig. 5—Panel layout with exact measure- ments for drilling holes for the shafts of instru- ments. Use templets for other screw holes the baseboard M and into the cabinet before you start to assemble the instru- ments. If you do not do this, you may find, when you have the set completed, that the standard cabinets will not quite fit your panel. It is much easier to file the panel when there is nothing fastened to It. The first operation is to lay out the These three views of the com- pleted set, from the top, the left, and the right, will aid you in laying out the parts and making the wiring connections correctly. In Fig. 6 note par- ticularly how the grid con- denser is attached directly to the tube socket. In Figs, 7 and 8 notice how the tuning unit is supported by quarter- inch strip-brass brackets 75 positions of the holes in panel L and drill them in the locations shown in Fig. 5. Only the holes for the shafts of the instru- ments are given because many instru- ments now are made single-hole mounting and the ones that require holes almost always are supplied with templets show- ing where to drill the holes for the supporting screws. The easiest way to drill the panel is to cut a piece of heavy paper the exact size of the panel and mark off the holes on the paper. Paste the paper to the panel L with library paste, then center punch and drill the holes through the paper and panel. The paper can be washed off after- ward. This method will save scratching the panel. Now fit the panel L to the baseboard M and to the cabinet as described above. The next operation is to drill 12 smal holes in the hard rubber or composition tubing—two for each wire end. Also drill a hole at each end for the screw that holds the tubing to the brass brackets, as shown in Figs. 7 and 8. The object of drilling two holes for each wire end is that the wire can be passed through to the in- side and then out through the other hole. This will keep the wire tight. See Mr. Senauke’s article on page 76 for sugges- tions as to how to wind coils so that the wire will be smooth and even. OIL A consists of 12 turns of wire and takes up three-eighths inch of space. Coil B has 68 turns in a length of two inches, and coil C has 16 turns and measures one-half inch in length. The space between coils is just over one- sixteenth of an inch, which allows enough room for the holes drilled to fasten the ends of the wire. ‘After you have the holes all drilled, you can proceed to wind the coils according to the specifications in the previous para- graph. All three coils should be wound in the same direction, and each coil should be started at the left end (the nearest end in Fig. 8). After you have the tuning unit wound, mount it and all the other instruments as shown in Figs. 1, 6, 7, and 8. The brass brackets for the tuning unit and the binding-post strip (Continued on page 134)

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POPULAR SCIENCE MONTHLY Let some one.hold the spool of wire with just enough pressure to keep the wire taut as you turn the coil form How to Wind Your Own Radio Coils Useful Hints for a Neat and Efficient Job By Alexander Senauke, M.E. receiver at home finds, occasionally, that he is in trouble with the coils for his new set. Either the wave-length range is not right or he has difficulty in winding the coils so that the finished result is smooth and even like a factory- wound coil. Countless articles have been published that give formulas showing how to calcu- late the wave-length range of ahy given coil, but unfortunately the average fanh’s knowledge of algebra and kindred sub- jects is rusty from lack of use, and so the formulas are not of much use to him. And, besides, the formulas can give only approximate results, since the maximum and minimum capacity of a variable con- denser is not always the same as the figures marked on the outside of the box. Also, no formula can possibly take into account all of the variable y rev radio fan who builds a radio coupled to the secondary, as well as the usual wiring. In this connection, it is interesting to note that highly efficient, low-loss con- struction has another advantage besides increasing the signal strength. For one thing, a low-loss receiver, other conditions being equal, will cover a greater range of wave lengths with the same condenser than a receiver having relatively high losses. This is because the usual low-loss construction includes coils having low internal or self capacity, and wide spac- ing of the instruments and wires, all of which results in cutting down the minimum capacity, consequently mak- ing it possible to tune to lower wave lengths. Now let us consider the various details that affect the possible wave. length of any given coil and condenser. To begin with, the test shows what we knew—that the larger the coil, the fewer the number of turns of wire needed. I also shows that the smaller the coil, the greater the wave-length range attainable with any given size of wire and condenser capacity. ‘3s difference is not very important, however. The size of the wire you use is important. You cannot use the specifications for a coil intended to be wound of No. 24 wire and substitute No. 22 with the expectation of getting the same wave-length range. ‘Tests show that the larger the wire, the greater the number of turns needed, so if you use larger wire than mentioned in the table, be sure to add a few turns. It is always well, by the way, to wind more turns than you factors in ordinary amateur radio construction. After all, the best way to get at. the figures is to determine them by actual experiment. The Number of Turns You Need HE following table will give you the number of turns think will be necessary, for the simple reason that it is no trick at all to remove a few turns if you find the range too high, The table on this page gives some of the results I have ob- tained. In these tests, a standard make of condenser was used, and as you will note from the column headings, the determinations cover the broad- cast wave lengths with the two most popular sizes of condenser and the three most popular sizes of tubing. The tests were made under practical conditions, which means that no attempt was made to obtain an abnormally wide range by reducing the capacity in the circuit. All of the capacity ordinarily present in the average amateur circuit was added before the readings were taken. In other words, there was a socket and a 10- turn primary circuit closely required for the secondary coil,to cover the broadcast wave lengths, when used with the two most popular sizes of condenser and the three most popular sizes of tubing. In each case the primary should consist of 10 turns wound on the same tube and separated half an inch from the secondary. In the tests on which these figures were based, No. 24 double silk-covered wire, wound on one-sixteenth- inch bakelite tubing, was used. WITH STANDARD .00025-MFD. CONDENSER Diameter of tubing 314 inches 3 inches 21% inches Number of turns 48 59 70 Wave- length 245 to 560 240 to 560 235 to 560 range meters meters meters WITH STANDARD .0005-MFD. CONDENSER Diameter of tubing 31% inches 3 inches 214 inches Number of turns 36 43 51 Wave- length 200 to 565 200 to 580 §=—6. 200 :~ to 600 range meters meters meters while if you find that a few more turns are needed, there's only one remedy and that is to rewind the whole coil. Tight and close winding wil have a marked effect on the wave-length range. The closer any given number of turns & wound, the higher will be the range of wave lengths covered by it when used with the standard condensers. A loosely wound coil with kinky wie usually will require from oneto four turns more than standar to make up for the change self capacity caused by th spacing of the kinks. A coil wound in sloppy & shion with kinks in the wire give practically as high eff ciency for radio work as @ (Continued on page 133) E

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yils length of To begin the fewer eded. It coil, the ttainable -ondenser nportant, wire you ; use the ed. to he itute No. tting the sts. show eater the you use she table, the way, than you y, for the s no trick y turns if too high, at a few 1, there is that is to iding will t on the "he closer turns is ill be the s covered with the A loosely nky wire om one to standard change In | by the loppy {2 e wire high eff- rasa 133) Extremes in Tubes What are said to be the world’s largest and smallest radio tubes were displayed at a recent wire- less exhibition in South Ken- sington, England. Both oper- ate on precisely the same principles, but the large one is thousands of times more power- ful than the diminutive model in the exhibitor’s right hand Prevents Radiation This device, designed to pre- vent improperly operated re- generative receivers from send- ing their squeals into the air to annoy the neighbors, is the fecent invention of Roy A. Weagant, a well-known radio engineer, It consists of a choke coil placed in series with the telephones and plate cir- cuit of the audio-frequency amplifier, and a small con- denser that connects the plate circuit of the audio-frequency directly with the grid the regenerative tube POPULAR SCIENCE MONTHLY 77 omething Newin Radio _ What Ingenious fs Hans Are Doimg /{j/ —Useful Devices iif and Odd Ideas in Construction ee Compact French Set Here is the French idea of a low-loss radio receiver as worked out by M. Horace Hurm of Paris. Despite its smallness, the receiver includes a regenera- tive detector and two stages of audio-frequency amplification. It is said to be highly efficient, and its size makes it easily port- Y eee ee able. Note the arrangement of aie the spider -web tuning coils Punching Transformer Cores Because of the electrical losses of solid iron cores, it is necessary to make the cores of transformers used on alternating current out of many layers of thin silicon steel. Powerful punch presses are used in cut- ting the patterns, as is shown above Milk Panels Leo Abrams, of Brooklyn, N. Y., won first prize in a recent radio show with a receiver, the panel and dials of which were made of dried and pressed sour milk. The color combinations can be varied to obtain desired effects Midget Broadcaster At the left is a miniature broad- casting station built by Sandy Smead, a California radio sales. man. It probably is the small- est working model in the world, and can be heard for half a mile

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nan en an eset ws on amination nas pa 78° POPULAR SCIENCE MONTHLY May, 1935" Handy Kinks for the Radio Fa a small screw in a radio set, when instruments and wires are in the way of the fingers, will find a pair or two of homemade tweezers exceedingly useful. They will soon pay for themselves in time and trouble saved. Figure 1 shows two of the most useful kinds of homemade tweezers for work on radio receivers. As these tweezers are designed only to hold small objects such as screws, and not to exert any great amount of pressure, they can be made of light-weight sheet metal. One-sixteenth- inch-thick sheet brass will do very well, and the size of the tweezers can be made to suit your requirements. A_ useful length would.be four inches. The sides can be half an inch wide or less. A Y one who has attempted to start Time-Saving Tools and Useful Ideas for Set Builders board tacked to the cigar-box dip the whole form in melted paraffin hot enough so that the Surplus yw, will run off like water when you take the form out. It is a good idea to drill small hole near the edge of each disk : that the wax that leaks into the inside ¢ the cylinder will run out when you remove it from the pan of melted wax. The idea is to have as little wax as possible remain on the form. The paraffin serves to pre- vent moisture soaking into the cardboard and also makes the cylinder considerably stiffer. If you are careful, a very neat ang workmanlike coil will be the result. Ang it also will be highly efficient because the wire will touch the material of the form for only a small proportion of its

Cut a V-shaped notch in the end of each piece, and after bending each leg of the tweezer into the proper shape, solder or rivet the other ends together. Riveting is the best way, since the heat of a solder- ing-iron may anneal the brass and take away its spring. Right-Angle Screwdriver length. : Silencing Battery Charger patos fans who have alternating eur. rent battery chargers of some of the older models, the vibrators of which make considerable noise, have tried all kinds of ways to cut down the disagreeable chat- tering. Inclosing the rectifier in

8 afrdeery the design of a radio receiver padded box often will muffle the noise, is such that a number of the screws but this method is open to the objection pi be used to hold instruments in place or to Fig. 1—Two forms of homemade tweez- that the lack of air circulation causes the a ‘ hold the parts of them together are oe wed ~~, at pa battery charger to overheat. mis covered up by other pieces of ap- with the fingers while they are driven Figure 4 shows how a charger can the I paratus or the wiring, so that it is be suspension mounted so as practi- t : impossible to use an ordinary screw- WIR CORRUGATED cally to eliminate objectionable hok “ driver to tighten the screws without CARDBOARD noise and yet cause no harm to the Ae ts 3 removing some of the wires or o— rectifier. ae instruments. Sy The mounting is made by fasten- = In many cases of this kind, the y, ing two side pieces to two end sup- use : radio fan attempts to tighten up the ports, as the drawing indicates i m screws with the edge of a knife This forms a rigid frame. Next, cut tien blade and usually the result is two sections from a discarded auto- them } disastrous to the knife. Pliers may : mobile inner tube and nail one on

be used, but they are likely to mar top of the other between the two og the screw head. NY side pieces. This makes an elastic Obvi It will pay the radio fan who does pig. 2-Where anordi- DISK CUT FROM cradle into which the rectifier is new pi any amount of radio construction to nary screwdriver fails ©!GAR BOX placed. old. TI make a right-angle screwdriver as to reach screws in in- : The vibrator still makes a noise, seats i shown in Fig. 2. By making the %<cessible places, this Fig. 3—Efficient low-loss coil but the rubber prevents the vibra- ‘ ei ; simply constructed wound on a corrugated card- . _? . withou angle of one blade square with the _;ight-angle screwdriver ines Soren stvaanthened ty thin tion from being amplified by the If this handle, and the other turned at an will be found useful wooden disk from a cigar box wood of the floor or table on which comes angle of 30 or 40 degrees, you can turn the rectifier is placed. Thus, if the pulls « a screw in places almost impossible to CHARGER 1 door to the next room is closed, the sound edges, get at in any other way. SIDE. | SUPPORTS can be heard only faintly in the next room. wie « ‘ , = . By r A Simple Low-Luss Coil Ze ZZ Label Your Battery Wires nal ma . wae similar AN EFFECTIVE way to wind low- a coe d [UNLEss your batteries are located ald ses loss coils if you do not wish to go to us — directly in rear of the receiving knowle the trouble of making a winding form set so that the wires are only afew reconst for basket-weave coils is illustrated in inches long and it is easy to see ata Ther Fig. 3. glance just which wire comes from uphols The coil is wound on a form made of corrugated cardboard, with the cor- the minus-A-battery binding post differey and so forth, it is a mighty good genera

rugated side out. The neatest way idea to label each wire. Then there applyi 3 << 7 ixing them Saini tor deck end, trorn Ba Shien you have cccesion HME a the top of an old cigar box and then igi connect the receiver. results, tack the layer of corrugated card- —_ Labels of the type illustrated mn In F board to the disks. The cardboard Fig. 5—Durable labels Fig. 5 can be made easily from stiff side of for the battery wires are made by boring two holes in fiber tags and passing the wire cardboard, although a much better appear material is hard fiber with the desig: will n¢ nation of the wire stamped i. Were h used for wrapping most types of vacuum tubes can be used, although there is some danger that it will Fig. 4—Aneffective cushion sup-

collapse at the center. A heavy ti poi —_— 2 a the Sane: It is, of course, desirable to place to the ° is made by esignations for e . grade of corrugated cardboard is ad- stretching a piece of old inner wires are stamped on the labels on the wires a8 near Tor visable. After you have the card- tube across a wooden frame the labels plainly the rear of the radio set as possible.

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rger ng cur- of the h make cinds of e chat- r in a > noise, jection ises the "ger can . practi- ionable a to the ' fasten- nd sup- dicates, ext, cut od auto- | one on the two n elastic tifier is a noise, e vibra- by the yn which us, if the he sound xt room. Wires located receiving nly a few ) see at a nes from ling post hty good hen there ing them . to dix trated in from $ ch better the desig- mped in. to place as neat - possible. POPULAR SCIENCE MONTHLY & dies ae Arthur Wakeling, Editor 79 » Home Workshop HEN applied to the repair of up- holstered furni- ture, the old say- ing, “A stitch in time saves nine,” is never more true. Many a good chair* that is falling slightly into dis- repute because of its sagging seat or frayed covering, can be rejuvenated for a trifling outlay of time and money. Even the wrecks that have been relegated to the attic often can be salvaged and returned in state to their old places in the living-room. Unfortunately the places at which up- holstery first wears out are usually hard to get at without first tearing down the whole and beginning all over again. The sooner started, however, the easier the repair can be done. If the springs of a seat begin to sag, the webbing or metal strap supporting them has given way. The webbing be- comes worn where it is attached to the rails, or the tacks holding it pull out. Obviously the remedy is to put in a new piece of webbing or to retack the old. The construction of most upholstered seats is such that this cannot be done without removing all the old material. If this is done before the outer cover be- comes worn through by the springs or pulls away from the tacks along the edges, it is often quite possible to use this same cover again. By noting carefully just how the origi- nal materials were attached, the sizes, and similar details, while tearing down the old seat, much may be learned and this knowledge applied when you begin the reconstruction. There are a number of ways in which upholstered seats are built up and many different shapes of chairs. However, the general principles are much alike. By applying the information given here to your own particular job, you ought to have little difficulty in securing good results, In Fig. 1 you will see how the under Side of the chair chosen for illustration appeared when the work was begun. You note that in this chair the springs Were held up by two metal straps fastened to the front and back rails. ®make a more comfortable seat than (Continued on page 104) Where to Find This Month’s Mechanical Features The Home Workshop Pages 79 to 82 and 88 to 111 The Shipshape Home Pages 112 and 113 Better Shop Methods Department Pages 84, 86 and 114 to 124 Fig. 2 (above)—Fastening the springs in place. The old springs are nailed se- curely’to the corner blocks; the new ones to the rails Fig. 4 (above)—Putting on the burlap. The rounded wooden strip makes a better edge 5 Fig. 6 (above)—The muslin or ticking cover Fig. 7 (at left)—How to fit a corner around a leg Fig. 8 (at right) —Stretch ing the final covering Fig. 5 (above)—The burlap is covered with stuffing tow and acover of roll sheet wadding /How to Re-Upholster Your Chairs Simplified Methods of Renovating a Worn Spring Seat By William T. Weld, Shopwork Instructor, Central High School, Peoria, II]. Fig. 1 (above)—Be- ginning work on anold ~ chair. Note the metal straps that serve to support the seat sprinzs Fig. 3 (at left)—How the springs are tied. The ends of the twine are held fast by tacking

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POPULAR SCIENCE MONTHLY Inexpensive Fireless Cooker

often thrown away or stored in the attic to gather dust, a reliable, money-saving fireless cooker can be made cheaply and easily. I made one in a few spare hours out of an old tin-covered trunk and two peanut-butter pails. The trunk, a family relic, was about 15 by 15 by 28 in. It was in good condi- tion and so would serve as the container for the cooker without any extra work. At the grocer’s I bought two 12-qt. peanut-butter pails. Next I purchased at a hardware store two pieces of sheet Pete: a few odds and ends that are Made from Pails, Sheet Zinc, Soapstones and an Old Trunk zine, some asbestos, and four soapstones. These things at hand, I obtained a quantity of sawdust from the shop, to- gether with a few thin boards with which to box in the top of the trunk. In assembling the parts, I first cut two holes in one sheet of zinc so that they would come directly over the pails when they had been placed in the cooker as illustrated. Next I covered the pails with two coats of sheet asbestos. The lids likewise were insulated with asbestos and then covered with extra pieces of zinc. The zinc was securely soldered to the lids. This done, the pails were packed in the sawdust and the zinc cover put in place and soldered to the top of the pails. The edges of the zinc were made to fit tightly and turned up about 1 in. at each side. The corners were soldered to make a watertight cover for the sawdust in the body. This completed the bottom part of the cooker. The top was

The cooker open, showing the lids and soapstones May, 1925 filled with sawdust, boarded up tight then covered with the second pieee of 7 To hold the soapstones over the foal while it was cooking, a wire hook soldered to the cover. Small wire hooks were found useful between the solid hook and the soapstones. WE HAVE tried out the cooker for more than a year on many different foods and find it to be quite as efficient ax any commercial cooker. Care and judg. ment must be used to heat the stones to the right degree; this done, we have no trouble in cooking roasts of~ meat and puddings, in baking potatoes or cake, or in having a hot and steaming midday meal ready upon our return from church op Sunday.—H. D. Smitu, Nyack; N. yY.

Register Serves as Ventilator (0°? ventilation for an attic, bam garage, pig or poultry house, may be had by inserting an ordinary registe a such as is used in warm. air heating, under. the eaves or gable ends of the building. For a trifling sum extra, these ventilators can he obtained with a cord or chain -either outside o inside to open or clog them below. They can be painted to match the building or can be bought finished in various styles.—C. W. Husertz.

trips and auto-camping is at hand. It is time to overhaul your equip- ment and, if you have not already done so, provide yourself with an auto kitchen- ette to assure comfort and convenience in the preparation of your outdoor meals. This kitchenette can be made by any high-school boy if he is fortunate enough to be in a school where sheet-metal work is taught. The cost is not exorbitant, however, even if you have the work done by a tinner, although it pays to shop around for estimates. Some commercial outfits no more complete than this are very expensive in comparison. Wood might be substituted for the metal, but would be somewhat heavier. Basswood, reinforced at the corners with tin strips and covered with strips of metal on the outside, if possible, will make a good looking cabinet when Pi tie ana. weather for weekend

enameled black on the outside and light gray or white inside. The cans may be labeled and painted to match. It is not necessary to put in all the partitions or to arrange them exactly as shown. Containers used in this case were 1- and 2-lb. coffee tins, 1-lb. square cans that had contained tea, and small wafer boxes for bread and cake. The only metal containers that were made were one for the stove, which also serves as a dishpan, and another in which are stored a kettle, four pie plates, cups that telescope, pans for other cooking and a frying-pan with a folding handle. The lid of the cabinet opens out for a table that seats two persons on each side and one at the end. The kitchenette is attached to the trunningboard of the car with stove bolts and wingnuts. The author also drilled a hole through the hinge of the door (the hinge is on the back of door) where it did not show and braced the cabinet by run- ning a bolt through. The width of the cabinet is so planned that it will fit back of the door ona

Kitchenette Makes Camp Cooking Easy coupé or larger car. The height bringsit just below the windows. The shelves should be riveted and soldered if of metal, and fastened rigidly if of wood. No allowance is made for thickness of shelves if made of. wood. The partitions, if steel, need only be (Continued on page 106) FOOD COMPARTMENTS \ St a |, 4'+L3h Ys:

ae 7— ys

=)" —|} ]

SILVER| TWO-BURNER STOVE AND ||P WARE |SMALL BOARD FOR LAUNDRY|I3¢ no ‘IN GALVANIZED BOX Q ANY NS PARTITION Front and side views of the cabinet and details of the door, shelves, and partitions

K\\

FRONT EDGE OF CABINET

May, !

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( pringsit sted and od rigidly made. for of . wood. only be a PARTITION abinet ‘and partitions May, 1925 POPULAR SCIENCE MONTHLY 81 A Cheap Cabinet for Printing Your Photos Electrically Equipped Work Table Aids in Making Pictures at Home By Richard C. Tarr Hiv photographers who attempt to do their own work often are at a loss to find a place for developing rinting. ; ” Enact, neat-looking, and efficient work cabinet may be made from an old commode by any one handy with ordinary WORK LAMP FOLDED BACK, AUNT | \ i\ VA until! \ DRAWER FOR ENSITIVE PAPER, ETC. COLORED WTTTTTI TIAL hahha ge TISSUE_ =a TRXOR KIA 42°X8"X8" 5 PRINTING BOX SECTION A-B RUBY WORK LAMP’ Old commode converted into photo cabinet by addition of printing box and ruby lamp tools. If a commode is not available, a second-hand bureau, without any mirror, may be utilized. The following materials also are re- quired: 4 lamp sockets, keyless; two 50- watt lamps; 14 pint flat white paint and brush to apply it; two 15-watt lamps; one snap-switch; 2 pieces lamp cord, about 8 feet long each; one two-socket “cluster plug’; one piece of galvanized iron 1g by 114 by about 28 in.; weather- proof wire, size 14, about 4 ft. long, for printing box; a regular 5 by 7 in. printing frame, ordinarily measuring 7 by 9 in. outside, and a few screws. It is necessary to obtain a wooden box, approximately 714 by 914 by 14 in. inside measurement. The box should not be any smaller, but may be larger, only the cover must be made correspondingly larger, to fit. The cover is built up from dimension stock, and should be of % in. thick pine, whereas the box itself need only be 14 in. thick wood. CREW three sockets into place on one side of the box and wire them as shown. The red light, screwed into the lower socket, will enable the photographer to center negatives properly and mask his paper. One wire should run to one ter- minal of all three sockets; the other wire should run to the other side of the lower, or red-light socket, and thence to one side of the snap-switch. From the other side of the switch run a wire to the remaining terminals of the two upper sockets. The’ red light then will burn all the time, and the white light will go on and A red light in the printing box helps the operator in placing printing paper accurately off as the switch is used. This enables the operator to set his paper by the red light, close the cover of the printing frame, set his time, and turn on the light. When the proper time has elapsed, the white light is turned off, and the paper extracted in the usual manner, for development. After the printing box is made, give it two coats of flat white paint inside, and allow to dry thoroughly before using. A third coat, of white enamel, may be used; it will give a little quicker printing. As the light is all reflected and diffused by the paint on the inside of the box, the printing iseven. The fact that the printing frame is at all times the same distance from the light also assures uniform results. (Continued on page 109) Wallboard Used in Making Neat Waste-Basket wallboard waste-basket is equally useful in office or kitchen. The same design, with the depth, width, and length reduced 2 in. or more, may be used in library, living-room or bedroom. A piece of wallboard 32 in. wide and 4 ft. long is required for the sides and bottom of the basket, wooden strips 34 in. square and 16 in. long for corner posts A and rails B, C, and D, and a strip 34 by 1% in. out of which to cut rails E. But of ample proportions, this By A. Neely Hall Specialist on Handicrafts in the Home The cross section shows the assembly of parts and dimensions for cutting the end pieces. A detail drawing gives dimensions for the wallboard side pieces, and corner posts A and rails B and C to which the edges are tacked. Notice that corner posts A project 34 in. for feet. Plane up the surfaces of the leg and rail strips and smooth them with sand- paper. Cut the wallboard with a jack- knife orasaw. Sawing is the easier way, and rough edges are removed afterward with sandpaper. Fasten the strips to- gether with finishing nails. Coat the sur- faces of the strips with glue, also the edges of the wall- board that are to come in contact with them. Asa re- inforcement to the glue, tack the edges of the wallboard with 34-in. brads. In laying out the end pieces, How — the waste-basket looks finished draw a center line and measure the c y a | Ba= = ve dimensions” either side of it, so that op- posite edges may be symmetrical. The ends of the handle holes may be bored with a l-in. bit or cut with a knife. When the end pieces have been cut, glue and tack them to the side frames. Then cut the bottom rails D and top rails E to fit between the leg strips, and fasten them with glue and brads. Notch the corners of the bottom piece to fit around the corner posts and glue and tack it to bottom rails C and D. With the waste-basket assembled, rub down the edges with sandpaper, then give all surfaces two coats of flat paint and one coat of enamel.

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poo 82 POPULAR SCIENCE MONTHLY Mi; ay, 1995 May, 1 How to Make a Chest for Your Small Tools F in the end pieces. The bottom rail, Big HE amateur mechanic who spe- By William J. Edmonds, Jr. cializes in metalwork and, indeed, 5/16 by 114 by 18} in., and also jg ten, the professional machinist, often 18% by 117 in.; the drawer runners are _ oned into the ends. A and B (left as wish to build a chest to 5/16 by 34 by 117/16 in. They maybe piece at first) are 13/16 in. wide and ey hold their growing collec- tongued to fit the grooves in the side, in. long with tenons at the ends, A tion of tools. A chest of The whole case is assembled with this type that is of neat good grade of hot cabinet or warmed jj ai and workmanlike appear- glue. After this is thoroughly hard i: ance, may be constructed is scribed around the four sides ] V6 in by following the from the top. The cover then is cut of I Hf ‘ be as accompanying i : on this line and the edges of the two drawings. It might H i i Cece

BRASS CORNERS

or At

. an,

parts are fitted carefully together, This be used, of course, method of construction, together with the for other purposes, unusual lightness of the case and the ab. such as for flat ' sence of difficult dovetail joints, are out. silverware, artist’s standing advantages. materials, a collec- The corners of the case are tein. tionof small curios, forced with 12 brass angles and q and the like. brass escutcheon plate to To build the a Wa. match is used to cover the chest successfully RAS keyhole. A ches requires first of all lock and two brass a careful study of - butts also are te. the drawings. Any = quired. good cabinet wood - The drawers are may be used for made as shown the case. Prepare 1 and provided with piece for the top, flush drawer pulls, 5/16 by 121% by 4 The three draw. 18% in.; 2 pieces ers are locked by for the ends, 5/16 means of an iron

4 ba Hi}

Yor gxizia”

STRAP;IRON DRAWER —> LOCK

oo = ag FH @t FF ce FS LQ | > pe: Wn - oe by 12-9/16 by 1214 aN fp ScREWON strip made as de eres 1G Beaver ale antes e back, 9/ ¥ < o the back of t 12-9/16 by 18}, in. Ki bi = ; case with a | Unless wide stock parte : strap in such away

is available, these that it -can slide will have to be glued up from (Oy! two or more widths. ye It will be noted that the ends ; and back are made } in. higher and that the back is made }4 in. longer than the finished dimensions; this is to

-H, * Y 7 S — Wy Ss DRAWERS 2 Maa), ys , (PLAN) | " SSX ‘4 , y" Ly ' }~¥—____2/% ——+| pottom EDG OF BACK BOARD

up and down. A round-head_ wood screw is screwed into the back of each drawer, the head being al allow for fitting the top and for the tongues on the back that fit into corre- sponding grooves in the ends. tage com Grooves are cut in the ends 14 or 3/16 chinist’s tools in. wide and % in. deep to take the - tongues of the back and front. Although as in the chest shown, \Y-in.-wide grooves were used inthechest or simply let into lowed to project sufficiently to en- gage the slots in the iron _ strip. Pushing down this : strip locks the drawers, provided

‘ -t iii 2 if i t - ry I

illustrated, 3/16-in.-wide grooves are 5/16-in.-wide dadoes, they have heen J much easier to make and serve the pur-_ according to which pushed in as far as a poses just as well. Either 14- or 3/16- method is preferred. os they will go. ; in.-wide grooves or 5/16-in.-wide*dadoes These pieces are glued we The interior of 7 are made in the side pieces 1% in. and nailed with small TELUS fj the box may tbe ti deep to take the tongues of the brads in their proper. lined or not, as the bottom and the top tray and the drawer places. The two small front rails, C and builder prefers. J runners, as shown in the end elevation. OD, are 34 by 5/16 by 18% in. and have The exterior may be varnished, as the chest a The bottom of the top tray is 5/16 by tenons cut in their ends to fit the grooves shown, or covered with imitation leather. a P + a)

Strong Sawbuck Lightens Work on of Handling Heavy Logs handling a log HE inverted V between the lower buck, as shown, and marking it off into stove-wood sections, beginning at the 0! larger end. This means less wasted effort if a short piece must be cut to make the

te legs of the sawbuck illustrated makes length come out even. Cut first from the F . it exceptionally strong and rigid. If end that seems a little the heaviest; then r made of hard, heavy wood, it will hold as cut from the other end. : large a log as two men can handle. The In placing a heavy log on the buck, lay ' buck also has the upper part clear for the buck on its side with the top again J 4 the passage of the saw and it can be the log as nearly as possible in the por — § made long enough for a piece equal to tion it will occupy when set up. 1 two sticks of the finished wood to lie take hold of one end of the log and, by } across its horns. This allows the last cut combining a lift and a push, raise the ' of a long stick to be made almost as con- and buck together. By this method it i veniently as the first. becomes unnecessary to lift the log high | § In sawing heavy logs, much time can enough to go over the horns of the buch § ! be saved by balancing the log on the saw- —C. R. Van Drurr, McLouth, Kan. — L

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; POPULAR SCIENCE MONTHLY 83 fay, 195 , 1925 :| Finishing H. Made Furni ols | Finishing Home-Made Furniture ail, E, ig a his Sure Wav & ‘ ae “=| Js Easy —this Sure ay &* | | with a a ed liquid You made a useful piece of furni- rd, a line 1/16 in, ture yourself and you want to give S cut off . P r the two it a beautiful finish. Because you '. This i a pith the know that improper finishing may the ab. : n are Out. ruin it and that any small defects will are rein. be minimized if it is well finished. S and a late ti = covet The Johnson Book on Interior Wood A ch (ae ° ; wwnieas Finishing gives complste instruc- es | tions for finishing all wood—old or ‘aw . ‘ os new. It tells how inexpensive soft ided with F P wer pills, woods, such as pine, cypress, birch, /| ree draw- : | odest by fir, etc., may be finished so they are hs f an iron ‘ ee Z wal de as de. as beautiful and artistic asexpensive = aa} d fastened A Le Sag ack of the hard woods. It is full of valuable, h a metal - “ ° : uch a way authoritative information on the can slide a cs ‘ ‘ down. A fascinating subject of wood finish- ad wood : ;setewed ing. The coupon below tells how back of ‘awer, the to get a FREE Copy. yeing al- 0 project tly to en- e slots in on strip. 9 down this ocks the Bei 7“ Johnson’s Wood Dye is just what you need for the Johnson’s Wood Dye is made in seventeen beauti- in as far as artistic coloring of wood. Itiseasy toapply—dries ful shades, among the most popular of which are: ai of in four hours—will not rub off or smudge—pene- 123—Dark Oak 131—Walnut ‘i bi h trates deeply, bringing out the beauty of the grain. 129—Dark Mahogany 126—Light Oak : pees Johnson’s Wood Dye is a dye in every sense of the 127—Brown Mahogany 124—Golden Oak ae word. Like most first class products it answersone All shades may be easily lightened, darkened or purpose only—it dyes the wood. A finish must be intermixed. Full directions on every label. Select it off iath applied over it—we recommend Johnson’sVarnishes the shade of Johnson’s Wood Dye that you want ig at the or Johnson’s Polishing Wax. and order it from your dealer by name and number. sted effort ke the tfromtx | PU e=="===""FREE—25c BOOK ON WOOD FINISHING----"-=--"=- “a riest; then Ask for a FREE copy of the Johnson 25c Book on Wood Finishing at stores displaying the sign shown at right. : — stores oni rs — a 4 yong and will be glad to show you wood panels—and — be . \ ais aehaan tee & oe tae —- eon aay no store in your locality can supply the Johnson Book —mai n the por f 4 aN \ ELI es LEE IE: EE I up. 1 Bien: G og and, by H a ssesitiaeas ia ARTISTIC aise thelog ': Your Address........ acassinctashastoepttatiaperatagnssiaad L [ele}e) method it J y 7] Sb e log high f City and State NISHE f the buck. : S. C. JOHNSON & SON, Dept. P.S. 5, RACINE, WIS. 1, Kan.” » le “The Wood Finishing Authorities” © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21.

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7 [Better S POPULAR SCIENCE MONTHLY = if ale 10p Methods 43 How Expert Mechanics Save Time and Labor Old Bill Works on Teeth And Shows Dependable Ways to Make Gears Quickly LD BILL was standing beside one O of his lathes watching the chips roll off. It was a pleasing sight, but the machinist seemed to be thoroughly disgusted with himself, the machine, and the big casting he was starting to turn. Old Bill recognized the trouble. “If you will slow down the lathe, and take a cut about half an inch deep, you will get under the scale with one cut,” Old Bill said.. ‘“‘Grind the tool this way.” Old Bill made some motions in the air, but the machinist understood them to mean that the tool ought to be shaped somewhat as is shown in Fig. 2. Old Bill could see some one coming © through the shop door hurriedly from a truck outside. ““T need some helr,”’ the customer said. ‘‘Come out and look at this gear and tell me how long you will be in making another one.”’ Old Bill peered at it over the edge of the truck—a cast-steel pinion about 12 in. in diameter and 8 or 9 in. inface. The teeth were about 2) in. pitch and the bore was something like 6in. The teeth had not broken, but had worn thin and bent over. “Why don’t you send to the fac- tory for another one?” Old Bill asked. “Tt will take at least two weeks to get another, and I can’t wait that long,” replied the other man, who identified himself as the superintend- ent of a building job near the city. “This is on the. most important steam shovel that we have, so you can see how much time means to me!” UT,” Old Bill said, “‘if I make you one, it will cost you about three times as much as one from the factory.” “Can’t help it!”” the superintendent re- plied. ‘‘I must have one now!”’ “All right,’”’ Old Bill returned. ‘‘TI’ll see what I can do, but it is a pretty large order that you are handing me!”’ Old Bill measured the gear with his rule. He remembered that he had a piece of old shaft about 14 in. in diameter. He sent a couple of men to get this into the shop so that a piece could be cut off. Then he counted the teeth in the pinion— 15—and decided that the gear had been 2% in., circular pitch. Having started a machinist to roughing out the blank, he took himself to the office to decide what the size of the gear had been when it was new. He multi- plied the number of teeth by 2 and By James Ellis Machine-Shop Superintendent found the pitch circumference to be 3714 in. Dividing by 3.1416 gave him 11. 93 in. as the pitch diameter. He drew a circle of this diameter on a sheet of drawing paper (Fig. 1). He consulted one of his handbooks to find the proportions of gear teeth of 2% in. circular pitch. He found that the Fig. 1—Quick method of laying out the teeth of a large gear for relatively coarse work addendum, or length of tooth outside the pitch line, was 0.7957 in., so he added twice this to the 11.93 and drew a circle 13 33/64 in. in diameter. He instructed the machinist to turn the blank to this size. He found that the depth of tooth below the pitch line should be 0.9207 in., so he drew another circle inside the pitch circle 10 3/32 in. in diameter. Then he stepped off the 15 teeth on the pitch circle. He made the thickness of the teeth one-half of the pitch or 114 in. Next, he drew a horizontal line from C Fig. 2—A toolbit ground according to Old Bill’s in- structions for get- ting under the scale of a casting END through E, tangent to (that is, jug touching) the pitch circle. Anotiner line, AB, was drawn through £, the point of tangency, to make an angle of 15 deg, with the horizontal. Another line wags drawn from the center of the circle to D, making an angle of 15 deg. with the vertical center line of the circle. These two new lines intersected at F. He drew a circle concentric with the pitch circle through this point F. He called this line his base line. Old Bill set his compasses to the distance from FE to F and drew an arc, using the point F as a center, This was the curve that he was going to use forgbe teeth from the base line to the outside diameter. Below the base line their flanks would be radial, Now, with this radius, he drew in the curves of all the teeth, and made the flanks radial. He rounded the bot- toms of the teeth, where they joined the smallest circle that he had drawn. Old Bill knew that, this scheme he was using was not strictly accurate, for he was making the working part of the gear tooth an arc of a circle, whereas it should be a part of an involute. He also knew that the machining meth- ods that he was going to use would not be capable of much refinement. And, further, he knew that the pinion had had cast teeth when new, so that they could not have been as accurate to shape as he was making his. H's scheme for laying out the teeth was one that he had learned many years ago. It could be applied to-gears of any size with equally good results. The reason for taking-15 deg. for the angle was that most gears were made to work at a_ pressure angle of 14144 deg. His 15 deg. was just an approximation of this. He carefully cut the outline of the teeth with scissors, and laid the templet on his desk. He was going out to the shop when another little problem came up. “Can you make me another like this? asked a man who had just come into the office. Old Bill looked at it and replied, “Sure!” It was another pinion, but smaller. It may seem a far cry from a pinion with (Continued on page 118) |" bad time-saving shop ideas will be found in the continuation of the Better Shop Methods Department, 00 page 86 and pages 114 to 124. Q”

Page 65

, just T line, oint of 5 deg, le Was > to D, th the These - He - pitch 2d this to the ‘eW an center, 3 going ase line ow the radial, in the ide the 1e bot- joined drawn. >me he curate, orking arc of be a e also meth- to use much er, he id had o that een as 1e was ig out hat he ; could e with on for it most ressure as just e teeth _ on his e shop > up. . this?” nto the ‘Sure!” ler. It yn with : will be of the ent, on 1638 In this tool you will find the features which have made Starrett Microm- eters the choice of two generations of crack machinists. The Ratchet Stop, for instance, which eliminates variations in “‘feel’’ by bringing the contact points downon the work with the same even pressure for every measurement. The Lock Nut which instantly sets the ‘‘“Mike”’ for check- ing purposes. The Decimal Equiva- lents on the Frame—a handy time- saver. The Sleeve Adjustment, exact, This Starrett Micrometer has a range of o to1 inch by thousandths. No. 113 is the same tool graduated by ten thousandths. Other Starrett Micrometers are shown in the Starrett Catalog No. 23 “W” which describes the features and uses of over 2200 Fine Precision Tools. We will be glad to send you a copy. THE L. S. STARRETT CO. World’s Greatest. Toolmakers Manufacturers of Hacksaws Unexcelled Steel Tapes—Standard for Accuracy ATHOL, MASS. POPULAR SCIENCE MONTHLY % ta De | P easy and not disturbing thealignment -of Spindle and Anvil, the latter being fixed. The accessibility of all parts for easy cleaning and oiling, the bal- ance of the tool, the fine finish, the way the faces stick together like a pair of Precision Gage Blocks... all these are unmistakable hallmarks of fine workmanship. That’s why “choosy” mechanics own Starrett Micrometers—they want the most in the way of accuracy, convenience and service their money can buy. Responsible Jobs Go to the Men Why do the Who Use A Oo oy > One Inch Micrometer No. 3 Starrett Tools 6 HACK SAW VF IS) This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 22.

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86 POPULAR SCIENCE MONTHLY May, 1925 Shop Shortcuts for Machinists How Expert Mechanics Save Their Time and Effort rate way to bore unusual tapers in a lathe not equipped with a taper at- tachment or where the taper is too long for the compound rest to reach the full length without shifting. The first step is to establish by calcula- tion a ratio of advance of the cross-feed screw with a lead screw. For a taper of V4 in. to 1 ft. and 18 in. long, I found this to be 3/16 in., which is one-half the 14-in. taper for 18 in. Additional figuring showed that the screw would have made three-fourths of a revolution. I fitted one of the change gears to the cross-feed screw in place of the handle and wrapped thin leather around the gear to make up the required circumference of 24in. Ashort piece of steel tape con- nected this gear with the back end of the lathe. One end of the tape was fas- tened to the rim of the gear and wound once around; the other end was held with a small bolt passing through a hole in a piece of old iron pipe, which was clamped across the ways in back of the tailstock. A wing- nut on this bolt provided adjust- ment for taking up the slack in the tape. After setting the tool in the usual manner for boring, this rig bored large tapers without any trouble.— WALLACE REES, Bell Is- land, Newfoundland. [: FIG. 1 is shown a simple and accu-

COUNTERSINK Fig. 2—Combination drill and countersink HE drilling and counter- sinking of many screw holes may be speeded up by making the combination tool illustrated in Fig. 2. The counter- sink is cut off about 14 in. above the head and drilled through to suit the drill. A setscrew is used to hold it at the right depth for the holes—T. C. DANIEL, Washington, D. C. O AVOID packing underneath the tool in doing small jig and die work in a lathe, I devised the adjustable tool- holder shown in Fig. 3. A swinging arm is fastened to the round end of the shank by means of a screw, and the tool itself can be moved back and forth.—GEORGE BENDER, New York. MALL tongs, handy for light work, may be made from cold-rolled steel or round iron (Fig. 4). Both ends of a length of rod are forged before the bend is made. The round loop at the handle end gives sufficient spring to keep the jaws open. The stud driver, also illustrated in Fig. 4, is made from a short piece of hexa- gon steel. It is drilled and tapped to suit the size of the stud and holes are drilled for inserting a bar of steel for a handle. The hexagon allows a wrench to be used for turning, when more leverage is required. i THE average machine-shop time can be saved in many tapping jobs through the use of the tapping set shown in Fig. 5. Hardwood blocks are drilled with five holes 1/32 in. larger than the body drill to hold three taps, a tap drill, and a body-size drill. The crib man can TAPERED BORE

i eS arn 3 MEAT TG ———————— Ma An — 1, Ser w eau A STEEL TAPE Fig. 1—Simple method for boring large taper

Fig. 5—Time-saving holder for tapping set .

Fig. 6—‘‘Knurling’’a rack check out the whole set on one tool check instead of three or five-—H. W. A SUITABLE and inexpensive rack and pinion for small parts such as often are used for fine adjustments in micro- scopes and astronomical instruments, may be made by the knurling process. The parts shown in Fig. 6 are made with a straight fluted cutter 34 in. in diameter with 5/16-in. face, having teeth of 90 degrees included angle. The cutter has a \4-in. hole and is supported on a tool-steel pivot in a soft machinery steel shank 1 by 5 by 7in. The cutter may be either of high-speed or tool steel. A block, open on one side to permit the passage of the knurl, and with a hole to fit the tube to be knurled, is gripped within a milling-machine vise, set so that the work will be parallel with the cutter arbor. A plug is inserted within the tube to take the pressure of knurling. The knurling tool is held between a pair of

“ot HEXAGON STEEL qs

SETSCREW COVER FROM OLD AUTO SPRING Fig. 7—Safety cover for exposed setscrew common cutters on the regular milling arbor and the spindle locked so it will not turn. The work then is fed by hand against the knurl lengthwise the distance required, back and forth, until the proper depth is obtained. The same tool is used for producing the pinion, this being done on an engine lathe. The stock is held in the lathe chuck and the knurl brought against the work as in any knurling process.—O. S. MARSHALL, Springfield, Vt. hel SHOPS where the shafting has eol- lars with projecting setscrews, a good cover can be provided by having the handy man or blacksmith bend pieces of discarded auto spring and spring one over each collar and setscrew, as shown in Fig. 7.—F. C. ENSITIVE bear- ings often are ruined because of overheating. To prevent this they sometimes are painted with a chemical, mercuric iodide, which changes color from scarlet to bright yel- low when raised toa temperature of 250° F. This tempera- ture, while not enough to injure the bearing, is sufficient to warn the operator of its overheating. The substance, as a rule, is obtainable only from the large scientific supply houses, but it can be made from common, drug-store chemicals as follows: Seven drams of bichloride of mercury are dissolved in as little water as pos- sible in a clean glass dish or tumbler. The same is done with 10 drams of potassium iodide, and the solutions are mixed. A scarlet powder forms in the liquid. It is allowed to settle and the excess solution is poured off. When dry, it is mixed in gum solution and applied to the surface around the bearing. The paint is permanent and the color change reverses on cooling. Some care must be used in handling the chemicals, as bichloride of mercury is poisonous.—CHARLES D. TENNEY.

Xo ROUND C.R.S-OR IRON Fig. 4—Shop-made tong and stud driver A GOOD oilstone or hone is worthy a good case. Let the lower box be of oak, cherry, or mahogany. For an oil- stone that is 1 in. deep, 1% in. wide, and about 6 in. long, make a box about 1% in. thick, mortised 14 in. for half of the stone, in order that it will fit tightly into the box and be held at a true level. The cover should be made similarly and be mortised to give a tight, dust- proof fit. e greater efficiency of the oilstone will repay the trouble of making the box. aii

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POPULAR SCIENCE MONTHLY 87 Se KRALUTER C00 SS DX i Why the Lineman — Wants Kraeuter ) Pliers 2

————_

———————— —= =—— == Every pair is drop-forged from special plier steel; hardened and tempered with scientific accuracy; and adjusted with the precision of adentist’s forceps. I

LLL =s They “stand up” long after ordinary pliers are rusting on the junk pile. SM i Doz YOU may not climb poles, but you DO need Kraeuter pliers—nearly everyone does. ee a ——— = ———— eee ah 1 wy Ds 5 i 4 —————— t I3

if

In any case, the best pliers are none Side-Cutting : too good for you. Pliers No. 1781-7 in.

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Kraeuter Slip-Joint Pliers No.356—5¥2in.

| = Oe eee Tee ae —— ———-— @ Kraeuter Slip-Joint Side-Cutting Pliers No. 1973-7 in

——————— ee =X) — ——— ———— = — = Dreadnaught Lineman’s Pliers ewes < —o Seg S ® This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21.

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’ pol enerarye org a wontyintet c | Dept. F5, 11 Mercer Street, New York City | 66 HAT is your opinion of Radion Panels?” was the question asked a number of win- ners in recent set-building con- tests. The answer of one enthusiast was typical, ‘The best!’’ And he added, “‘I used it because of its low leakage at high fre- quencies.” Made to order especially for radio purposes, Radion Panels are noted for their low surface leakage and low dielectric ab- sorption. And low losses in your set mean clearer recep- tion, more volume and more distance. Easy to cut, saw or drill RADION Panels are easy to cut, drill or saw. They are strong, moisture- proof and resist warping. Eighteen stock sizes and two kinds, black and mahoganite. Radio dealers have the exact size you want. The use of Radion Panels by the manufacturer of a ready-built set is almost invariably a sign of general good quality in that set. Send for booklet, “Building Your Own Set’”’ OUR new booklet, “Building Your Own Set,” gives wiring diagrams, front and rear views, shows new set with slanting panel, lists of parts and directions for building the most popu- lar circuits. Mailed for 10 cents. Send the coupon now. AMERICAN HARD RUBBER CO. Dept. F5, 11 Mercer St., New York City Chicago Office: Conway Building Pacific Coast Agent: Goodyear Rubber Company, San Francisco, Portland RADION @ ‘The Supreme Insulation PANELS Dials, Sockets, Binding Post Panels, etc. a ea eel eel AMERICAN HARD RUBBER CO. Please send me your new booklet,“Building Your Own (stamps or coin). | Low leakage at high frequencies .” for which I enclose 10 cents POPULAR SCIENCE MONTHLY 4 | The Home Workshop| How toGlue Boards Together The Simplest Method of Preparing Table Tops and Other Wide Pieces By Emanuel E. Ericson, Noted Manual-Training Authority Fig. 1 (left)—Arrange the pieces with reference to color and grain. Put the wider pieces toward the edges, if possible, Mark two lines across in VY shape and number the boards Fig. 2 (right) —The inside edge of the first board at either side is planed straight and free of ‘‘wind.”’ No squaring is needed as the fac- ing edge isto be planed to the corre- sponding angle. Have plane sharp Note how the jointer plane is held parallel to the edge and how the fingers of the left hand help to keep it steady Fig. 3 (above)—When the edge of the next board has been planed, the joint is sighted. At the ends the joint must be absolutely tight and true; the middle may be slightly open ; an / yj ait A Pi — ‘ y ., a ities ge . Fig. 4 (above)—When each joint *" 4| has been planed, the whole piece is set up and tested for straightness Fig. 5 (above)—Two pieces are laid across the bench to support the work. Clamps are adjusted for length before glue is applied. If the shop is cold, the joints should be warmed, but not made hot. Use freshly made glue of the best quality. If flake cabi- net glue is used, it should be soaked beforehand in cold water. A good grade of liquid glue will serve, but warm the tin in water. Do not clamp too tightly. Level the joints on the face side with a mallet, or a block and a hammer Fig. 6—The glued-up boards are kept straight by the use of wooden cross pieces and hand screws. These are put on each end of the work. The work is left for about 24 hours so that they will dry thoroughly IS] This seal on a ractio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21. May, 1925 —— a

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POPULAR SCIENCE MONTHLY wma? Ae ie me i 2. ns 7 = Y; bath 2 ™ rs ¥ y pete ert Temper Savers! Home repairs are easy—and comfortable—with a set of Blackhawk “Q. D’s.’”’ There’s a sturdy socket to hug each bolt and nut closely. And a handle that’s really handy. A small set of Blackhawk ‘“‘Q. D’s” is equivalent to a peck of fixed-socket or open-end wrenches. Blackhawk engineers have designed a selected .‘‘Q. D.” set for your particular car. It will quickly pay for itself in the time it saves. Every Blackhawk socket is broached to exactly 1/64’ oversize. The handles are just right for leverage, balance and strength. They all have firm, comfortable grips. Durable, all-black, baked-on finish. Have your dealer show you how a small, inexpensive set of Blackhawk ‘‘Q. D’s” is both temper-saver and money- saver. Write us direct if he can’t supply you. Made and Guaranteed by AMERICAN GRINDER MFG. CO. Dept. L Milwaukee, Wis. Also manufacturers of Blackhawk Water Pump for Fords. When You See a “Hex” Think of Blackhawk! Welded@wrenches IS] This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21.

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In Steel Handle—Eight sizes from 6 in. to 48 in. In Wood Handle—6, 8, 10, 14 in. sizes. . Examine this feature-illus- tration of the TRIMO Pipe Wrench carefully—think what each of these features means to you in time, money and labor saving—inspect and handle the TRIMO at your nearest dealer’s —then you will clearly under- stand’ why the majority of America’sskilled mechanics pre- fer this wonderful tool even though they can buy other wrenches at a few cents less. You can buy the TRIMO at most hardware, plumbing and mill-supply stores. TRIMONT MFG. CO. ROXBURY, MASS. © America’s Leading Wrench Makers for Nearly 40 Years POPULAR SCIENCE MQNTHLY WHILE the fun they get from working with tools is what leads most men to | become home workshop enthusiasts, there | is no disguising the fact that a vast amount of money is saved and earned each year | in the home workshops of the United States. workshop has a monetary value. You | either repair some article and thereby pro- | long its life, or you make it unnecessary to | purchase an equivalent commercial prod- uct, or you build something that is sold ata | | Every job undertaken in your home | | | profit. | | Poputar Science Monrtuiy wishes to bring together some of the most profitable | undertakings of amateur mechanics. | For the best letter from a reader | on the topic, ‘‘ My Most Profitable | Home Workshop Job,’’ a first prize of $25 will be given. For the second best letter there will be a prize of $10, and for the third, a prize of $5. | For the ten next best letters prizes of $1 each will be given. Contributions that do not win prizes, What Was the Most Profitable Home Workshop Job You Ever Undertook? New contest offers $50 in prizes for the best money-making | and money-saving experiences of readers but are of sufficient general interest to war- tant publication, will be purchased at regular rates. No letter should be more than 400 words long. The money-saving or money ~earning element must be stressed. In addition to telling what the job was, explain just why you consider it the most valuable of your home workshop undertakings. Give the exact value in dollars and cents if you can; otherwise estimate it as accurately as pos- sible. It will add interest to your letter if you include a photograph or drawing show- ing the article or repair described, but this is not essential. The contest will close May 25, 1925. All letters must bé received on or before that date. The Board of Editors of Popu- LAR ScteNcE Montuty will act as judges and their decision will be final. Unavail- able letters and photographs will be sent back only when accompanied by postage for their return. The winners will be an- nounced as soon as possible after the judges complete their task. Address your letter to the Profitable Job Contest Editor, Poputar SciENcE Monruty, 250 Fourth Ave., New York. Novel Method of Loading a Truck HEN heavy objects must be lifted on a_ truck without the aid of winch or tackle, it often is possible to use the method il- lustrated in the ac- companying photo- graphs. These show how a heavy stump was loaded by three backed toward the log and two 2-in. planks were leaned against the bed end (Fig. 1), with their lower ends under the stump. A chain was passed under an upper root snag and the ends made fast to the truck. Upon being driven forward, the truck rolled the stump on the planks, where % was blocked by means of a pry (Fig. 2 Fig. 1 (at left, above)—The first step. Fig. 2 ° men. (at right, above) Halfway up. Fig. 3 (cen- planks, the chain The truck was ter)—Ready to back the truck under stump was tightened, and The chain was tightened and the stump rolled up the incline once more, when it was possible to pry up the lower ends of the planks until they were nearly level with the truck bed. Rollers were slipped under the front ends of the a third plank was braced against the stump as in Fig. 3. A cleat nailed to the stump above the brace prevented it from slipping. The truck was easily backed under the stump / and its skids. To unload the stump it was necessary only to pry against the skids, as the rollers were under the weight.— EDWIN M. LOVE. © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21.

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was the » the nore, sible ower anks were with rere the the chain and was ig. 3. » the The tump } ssary ollers 4 OVE. RAISING CHICKENS BY THE CARLOAD ©*% THE GREAT FARMS where chickens are raised by the hun- dreds of thousands to ship to market, taking chances with the temperature of the incubators means the possible loss of thousands of eggs. Only by keeping the incubators at 103 degree F. can the raisers of chickens on a wholesale basis be sure of hatching their eggs. The Zycos Incubator Thermometers register incubator tempera- tures accurately—always. The same care is taken in —— Jyeos Incubator Thermome- ters as in making all the other Indicating, Recording and Con- trolling Instruments in the Jyceos Line—the Sixth Sense of Industry. Whether you raise chickens for market or family use, you need Zycos Thermometers in your incubator. If you use heat processes in your manufacturing —whether hatch- ing eggs or making steel, paints, furniture, rubber goods, metal ware, food products, or any other product that goes through heat- treating processes—you need in your plant the Sixth Sense of Industry—Zyeos Instruments for Indicating, Recording and Con- trolling Temperature. MANUFACTURERS feos Engineers have effected substantial economy for manufacturers in every line of industry by applying the Jyeos “sixth sense.” Whatever your problem in the indicating, recording or controlling of heat, there is a Zycos Instrument to serve you. Write us for literature on any instrument, or type of instrument, and it will be sent promptly. Or, if you prefer, our engineers will consult with you on the application of the Jyees Sixth Sense in your plant. Taylor /nstrument Companies Main Office and Factory ROCHESTER, N. Y. U.S.A. Canadian Plant: Jcos BUILDING, TORONTO POPULAR SCIENCE MONTHLY Zyeos Wall Thermometers To help you maintain a temperature in your house conductive to good health. Zycos Office Thermometers An aid in promoting human efficiency. Zcos Bath Thermometers To enable you to get the most good from your bath. Toler Home Set Bake Oven Thermom- eter, Candy Thermom- eter, Sugar Meter. The secret of accurate res- ults in cooking. tenn [fome Tycos Fever Thermometers A necessity in every home. Tpler Quality Compasses To show you the right way in unfamiliar country. Tyeos Stormoguide Forecasts the weather twenty-four hours ahead with depend- able accuracy. Fcos Hygrometer To enable you to keep the humidity of the atmosphere in your home correct at all times. Your dealer will show them to you. Ask us, on a postal, for booklets on any of the above. Tyeos ~ “fy Profession, Joe Sphygmomanometer, Pocket and Office types. Zeos Urinalysis Glassware. Zeos Fever Thermometers. Bulletins on request. INDICATING + cos Temperature Instruments (\ RECORDING + CONTROLLING © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21.

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A Necessary “Tool” For Your Workshop OR the man or boy who has a home workshop, Lee Union-Alls are a handy “tool” to have about. All that is necessary when you want to get busy is to slip into them and start your work. They cover the body from head to foot and can be worn over other clothing. They save clothes, also. And they save time where the hours for such work are limited. Wear Lee Union-Alls, the original one- piece work suit, worn by thousands of mechanics,shopmen, garage workers and industrial workers. Lee Union-Alls are quality-built—close-woven cotton fab- ric, riveted rustproof buttons, reinforced strain points—fully guaranteed to give satisfaction. They give solid. comfort, long wear, and are neat in appearance. Accept no substitute—look for Lee onthe buttons.. Thousands of live dealers sell Lee Union-Alls. Ask your dealer today! LeeUnion-Alls THE H. D. LEE MERCANTILE CoO. Kansas City, Mo. Trenton, N. J. South Bend, Ind. Minneapolis, Minn. San Francisco, Cal D) oh (Gu Lee Overalls and Work Shirts are other items in the famous Lee line. They are quality-builc, also. a a a a a ee tad POPULAR SCIENGE MONTHLY eS ” HAT makes of my Ford Autiene of the car in the garage creep on “Automotive Trade Training”’ at night, or else me when I try to where. They claim crank it?” is a question frequently asked. With the larger use of electric starters, less attention is paid to this trouble than formerly, yet the results are no less seri- ous. The tendency of a Ford car to creep forward when cranked by hand wears out the operator; the same tendency in an electrically equipped car puts the elec- trical equipment to a severe test and wears out the battery. The matter of a creeping car is not so simple as might at first appear. There “What MakesMy Ford Cree The causes for a familiar trouble and how to remedy it By Ray F. Kuns CHECK UP ON BAND ADJUSTMENTS ADJUST FOR WEAR AND TENSION > : \a frm 4 4 CLUTCH FINGER a A ial CLUTCH PLATES yh | | SPRING in 4} \ | Ml H may be a number of contributing causes. In cold weather the trouble may seem to grow worse, until some morning either the operator or battery is completely ex- hausted in an attempt to start the engine. The engine turns as though there were some tremendous power holding it back and the car may show a tendency to creep forward. The trouble very likely is due to the condition of the oil within the en- gine and especially the oil in the clutch and under the transmission bands. Not only must the oil be light in body, but it must remain that way at any low temperature that may be reached and it must retain its lubricating qualities, no matter how hot the engine may become. It is a fact, too, that Ford engines are “boiled’’ about as often in the winter as in the summer. Another trick used by experienced drivers is to allow the clutch to be en- pe gaged when stopping that this squeezes all the oil out ofthe clutch plates while it is warm. In the morning when the clutch-and-brake lever is set on neutral, the clutch plates sepa- rate, and, as the oil has been squeezed from between the plates, the clutch wil] not drag. * Every driver, of course, is familiar with the fact that if the bands are drawn too tight, the engine is hard to crank. He also knows that the engaging of slow speed in the Ford car is merely a result of gripping or holding the slow-speed drum. Consequently when the oil under. the slow-speed drum is thick and gummy, it has the same effect as gripping or hold ing the slow-speed drum and thus tending to propel the car forward. For this rea. son it is well to check up carefully on the adjustment and not allow the bands to be set too closely. Ancther cause of creeping in a Ford car, and one not so eas ily remedied, is the wear that occurs in the transmission parts, particularly in the clutch. The Ford clutch plates are steel. . One group of these is mounted on the clutch disk drum and the other group is mounted in the brake drum. When the clutch lever is in neutral, the plates are sepa rated; and when Tracing trans- ptt ogee lh the lever is in for- ward position, the disks are together and held so by the tension of the clutchspring. The tension on the clutch fingers may be adjusted and thus offset some of the tendency of) the clutch plates to drag. On the other hand, if they are allowed to be too loose, the clutch will not hold and there will be a loss of power in high gear. [N A new car there is no difficulty in adjusting the clutch fingers properly. In an older car they will have to be set up until the clutch holds. In this instance there may not be much of a throw-out and instead of the clutch plates’ releasi as they ought, they may hold bea little grooves or notches have been w in the brake drum or in the clutch-disk drum by the hard lugs on the clutch plates. As long as these plates or part of them remain with their lugs in these notches (Continued on page 94) © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE CF STANDARDS. See page 21.

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POPULAR SCIENCE MONTHLY EVEREADY HOUR c Recommend EVERY TUESDAY AT 9 P.M. fe 7 For real fo te the ‘Ever- = O O d b a C C eC Tl eC S eady Group.”’ Broadcast through stations— WEAF New York WFI Philadelphia Wiak Frome TGR” Bullalo” : IN AN effort to reduce the first cost of a oar bank weco { Minneapolis radio set, a newcomer in radio often buys thsi : inferior batteries. You know such “‘sav- ing” is really wasteful. Tell your friends who are about to buy receivers that the best batteries obtainable will prove to be the most economical. Tell them to buy Eveready Radio Batteries—they last longer and, because they are greatly supe- rior, they give complete satisfaction. There is an Eveready Radio Battery for every radio use. Manufactured and guaranteed by NATIONAL CARBON COMPANY, Inc. New York San Francisco Canadian National Carbon Co., Limited, Toronto, Ontario EVEREADY Radio Batteries ~they last longer AND ALL GENERAL puRPOSse® iponese® RELIABLE cyt: Anse gc Eveready Columbia Ignitor — — : No. 77 Batter 45-volt for ait a Extra Dry Cell ‘ — hey oe Tubes iS ; = pen cal a: a oa rice 1% volts ‘oe : of cee $4.75 For use on multi- tube sets No. 767 45-volt Large Horizontal Price $3.75 With variable taps © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21.

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Here’s the indispensable tool for the mechanic in shop or garage and for the handy-man- around-the-home. The tool needed almost daily for the odd jobs that crop up. There are a hundred things about thé home or shop to get out of order at a moment’s notice, which can be adjusted just as quickly if there’s a Wrench at hand. Pexto Adjustable Angle Wrench takes the place of several sclid end wrenches. They are backed by a century of tool making experience and are a combination of skillful workman- ship and materials of quality. They can be furnished in sizes 4 inch to 12 inch, in full polish or semi-polish finish. They are drop forged steel, properly hardened and in every re- spect worthwhile tools. Other tools in the Pexto line are Braces, Bits, Hammers, Chisels, Squares, Hatchets, Pliers, Snips, Screw Drivers and many other small tools. Ask your dealer to show you Pexto tools. © The Peck, Stow & Wilcox Co. Southington, Conn., U.S. A. POPULAR: SCIENCE MONTHLY SA Backyard Aerial 3/32 X1" STRAP IRON + How the aerial trolley coaster is made and used MALL children can have great fun . in riding on the aerial trolley coaster illustrated above. It not only is thrilling sport for the youngsters, but also develops their hand and arm muscles. The coaster is made from two pulley wheels, such as are used for clotheslines, about 5 in. in diameter. These are mounted with strap iron or in any suit- able way to a wooden carriage cut from a % by 3 by 14 in. board. A length of 1-in. dowel or a portion of a broomstick is oS Coaster Provides Thrilling Sport for Children / run through a hole in the center of the carriage to form the hand grips. The trolley is mounted on a wire or rope clothesline stretched across the yard at: an easy angle. The children climb on a _ stepladder, porch, or stand of some kind and, grasp- ing the handle-bars, slide down the in- cline until their feet touch the ground at the other end of the line. The carriage is pulled back with a rope or pushed with a stick.—DONALD W. CLARK. Woodworker’s Mallet Turned from Piece of Hard Wood . YOU have access to a wood-turning lathe, it is a simple matter to make yourself a neat and useful mallet. Instead of making the head and handle separately, as is usually the practice, you will find it easier to turn the tool from a single piece of close-grained, hard wood, preferably hickory or maple. The mallet is 834 in. long in its en- tire length, the head being 234 in. in’ diameter and 314 in. long, and the handle 1% in. in diameter at its thickest part and 514 in. long. ‘‘What Makes My Ford Creep ?”’ (Continued from page 92) they will not release fully, but will present quite a resistance or drag. This again has a tendency to cause the car to creep for- ward when the engine is cranked. This is a job for the repairman. The engine must be removed from the car and dismantled, at least to a point where the transmission may be torn down and re= built. This work may be done by releasing’ all the engine crankcase bolts and remov- ing the transmission cover, after which the cylinder block and transmission may be lifted from the car, leaving the crank-" case pan in the car. The better plan, however, is to remove the engine or power plant as aunit and thus make all parts more readily accessible and insure a better grade of work. Extreme care must be used by the beginner in disassembling and assembling the transmission. a aS) This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21.

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Yy 1995, ; f the r rope rd at: \dder, ' rasp- 1e in- nd at age is vith a May, 1925 SO The Home Workshop Trellis for Climbing Roses - Costs $4 for Materials Y CLIMB- {@& ING roses jga were not doing very well against the house, and I decided to build a trellis for them. By modifying and combining designs published in POPULAR SCI- gNcE MONTHLY, I constructed the trellis illustrated at a total cost of only $4. It is made of cedar, using 2 by 2 in. pieces for the uprights and 2 by 4 in. pieces for the cross bars on top. The lattice strips are 14 by 2in. The wood is stained brown.—H. C. Felt Disks Serve as Cushions for Vacuum-Tube Sockets H°” tube sockets may be mounted so as to eliminate noises caused by vibration, which are especially noticeable in the “hard” tubes now almost uni- versally used, is illustrated below. Each socket is mounted on a cushion made of pieces of felt sewed together and cemented to the socket. As many sockets as are needed may be mounted by this method on a composition Ghd Ss PILE OF FELT DISKS SS Y2" TO 3/4"HIGH How the pads are made and method of mount- ing several jarproof tubes on a single base or hard rubber strip about 31% in. wide and \ or 3/16 in. thick. The strip is fastened to the base of the set with wood screws, which pass through spacers to hold the heads of the binding-post screws off the baseboard. Round nuts from old dry cells may be used for this pur- pose.—DoNALD H. PALMETER. Special Holder for Sharpening Blade of Spokeshave — O OVERCOME the difficulty of holding a_ spoke- shave blade when ting it on an oil- stone, I made the holder illustrated. hard wood or metal. I found one made of cast iron to work better because it is is about 4 in. long. It may be either | grinding it or whet- | heavier. The handle | © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21. POPULAR SCIENCE MONTHLY 95 - 4 9 . Wait—Don’t Buy Find out first that our claims are true. Make this 10-shave test. DEAR SIR: You’re a fair minded man—and as such will give other men a chance to prove any sincere claims they advance. Now the ones we make for Palmolive Shaving Cream are pretty broad. You may question them. So we say, “Don’t buy yet”—Let us send you a 10-day tube to try. And thus, grant us the opportunity of proving how true those claims are. Men by the millions have shifted to this unique cream. Today it occupies pinnacle place in its field; its success is a trade sensation. 80% of its users were wedded to rival makes. Only outstanding merit, you’ll agree, could shift so hard a market. Find Out, Please So we ask you, now, in fairness to us both, please mail the coupon. We'll rest our case on what you find. After 10 days of new shaving delight, few men go back to old ways. 1 Multiplies itself in lather 250 times. : 5 Delig ht '§ 2 Softens the beard in one minute. : 3 Maintains its creamy fullness 10 minutes on the Five remarkable face. results: 4 Strong bubbles hold the hairs erect for cutting. 5 Fine after-effects, due to palm and olive oil content. To add the final touch to shaving luxury, we have created Palmolive After Shaving Talc—especially for men. Doesn’t show. Leaves the skin smooth and fresh, and gives that well-groomed look. Try the sample we are sending free with the tube of Shaving Cream. There are new delights here for every man who shaves. Please let us prove them to you. Clip coupon now. THE PALMOLIVE COMPANY (Del. Corp.), Chicago, IIl. PALMOLIVE SHAVING CREAM _ and a can of Palmolive After Shaving Talc Simply insert your name and address and mail to Dept. B-984. Address for residents of Wisconsin, The Palmolive Company (Wis. Corp.), Milwaukee, Wis. Address for_ residents other than Wisconsin, The Palmolive Company (Del. Corp.), 3702 Iron St., Chicago, Ill. 1 I a an ee ere cin + weed Lar etie st PARSER yee he ae oes SS

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He’sdrillingoutabroken rivet onaSteeringcolumn witha“Yankee”’ Ratchet Hand Drill. Thanks to the“Yankee” DOUBLE Rachet he can work in the easiest position, as only a slight to and fro movement of crank is needed to make the drill cut continuously, = 7 In places where ordi- nary drills won’t work, the “Yankee” Hand Drill No. 1530 quickly drills clean, accurate holes. No need to tear down construction. When set at DOUBLE Ratchet, the slightest movementofcrank makes drill cut continuously. “YANKEE” Rachet Sp HandDrill = No. 1530 ‘ Though a midget insize,it N has every ratchet adjustment { of the big “Yankee” Breast DrillsandHand Drills. Fivein all—Plain Drill, Left-hand Ratchet, Right-hand Rachet, DOUBLE Ratchet and Gears Locked. Weighs on- ly 1% Ibs. Measures only 10% in. long. Some other “Yankee” Tools Ratchet Breast Drills Ratchet Tap Wrenches Ratchet Screw-drivers Spiral Screw-drivers Automatic Push Drills Dealers Everywhere sell “Yankee” Tools May we send you this FREE Tool Book? a You’ll be in- terested, we know, in see- ing all the “Yankee” time and labor-saving % tools. Write tart for it today! Z 7 ~~ _- NortH Bros. Mrc. Co., Philadelphia, U.S. A. "YANKEE" TOOLS Make Bet Mechanica, POPULAR SCIENCE MONTHLY ie _|l Wa | i! TOT yo Lita magazine case illustrated may be placed alongside commercial furni- ture of good quality. Its use is not con- fined necessarily to books; it will serve for other purposes. The case is constructed from 3-in. stock dressed to 5% in. thick throughout, with the exception of the back and middle shelves. Preferably mahogany, curly whitewood or some good cabinet wood should be used. Each of the sides A is cut to the di- mensions indi- cated, with mor- tises 144 in. wide and \% in. deep, and 2 rows of holes ¥ in. in diameter and % in. deep. The holes are for short lengths of nails, which are I CAREFULLY constructed, the Attractive Case H Ys XJa° MORTISE B a ae BACK: nM Ae 20M KSSH A IIH if Hts } | | | / \ ore PL SS Hy i yy \eunlbaaow Sie re WY ///)\\ Sacer UTX | ii} ANN tp LED Pp olds | used to support . the shelves. This method allows the height between the shelves to be changed. How the finished case looks in use VLL LX Ye DIA. HOLES eg Ni ‘ TOP BACK RAIL | Ss | KNX S eX Pam 4suetves // \ 36°X10%4 X19 : LL. 4% —-| BOTTOM D 4 THICK BACK RAIL WY Ee 19%" > Working details of the hardwood case. The distances between the shelves are adjustable The top and bottom shelves, E and F, are tenoned and fit in mortises in A. The pieces B, C, and D also are tenoned into side pieces. The back is a sheet of wall- board fastened in a groove running the entire length of the side pieces. The parts may be assembled with a good grade of liquid glue and with screws wherever needed. After the glue is hard, the case should be cleaned up with fine sandpaper. Care should be taken that the edges are not rounded, but kept square. Finish the case as preferred. Cheaply Made Frames N MANY occasions the writer, even when he had at hand a fillister and rabbet plane, or a machine saw, has found it more convenient to use yoga | FRAMES MADE FROM HARDWOOD. FLOORING VISE FOR GLUING AFTER FRAME 1S TOGETHER 1S} This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21. An efficient clamp for holding picture- frames together while the joints are glued odd pieces of tongue-and-grooved stock | to make frames for pictures, mirrors, small panels, and other purposes. The tongue may be taken off with a slight effort with chisel and plane; the inner (Continued on page 97) th

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ustable and F, i. The ed into of wall- ing the with a 1 SCreWS is hard, rith fine en that ut kept rred.

cture- glued ed stock | mirrors, ses. The 1 a slight

the inner

Extra Jaw ee C- Sinaia for Holding Tapered Pieces W HEN it is necessary, as often happens, to hold a tapering or irregular piece in a C-clamp, the attachment il- lustrated is con- venient. It is a small jaw made of any soft steel. The surface is roughened to prevent slipping when used. on steep tapers. At the back is a tongue, semi- circular i in section, which fits into a V slot filed in the fixed jaw of the clamp. The supplementary jaw is free to adjust itself automatically to the work.

Cheaply Made Frames (Continued from page 96) slip or lip of the groove likewise may be removed. The material. then is ready to be mitered. This method is particularly applicable at the present time when severely plain hardwood frames are the vogue. At pic- ture exhibitions in New York recently there have been a surprising number of these frames, finished in natural color as thinly and unobtrusively as possible. Plain or quartered oak, maple or other flooring may be used, as it is always very well machined and perfectly smooth. Nearly every carpenter has odd, left-over pieces of both flooring and tongue-and- groove wainscoting, some of fine cabinet hard woods. ‘These are suitable for this purpose and may be obtained cheaply. The drawings on page 96 show plainly how the material is prepared. It may be left quite plain with only the tongue re- moved, or given a bevel on the inside edge, or a rounded outer edge or, if pre- ferred, an ornamental bead. If one has molding tools, other designs may be formed from the same material. Many excellent suggestions have ap- peared in POPULAR SCIENCE MONTHLY in regard to joining the frames—methods making use of a special small wooden vise, a machinist’s vise, a piece of string tied around with small blocks used to tighten it, and others. These are all good. I ‘add one other, which I find has the ad- vantage that the work can be tested readily to see that the joints come to- gether before gluing. That is important, especially in frames from 2 to 4 in. wide. Nail on the two cleats at right angles to each other and quite square inside as shown. The other two cleats are cut to suit the wedges. Allow room for nailing at the two most convenient corners. Place a small piece of tough paper under each corner when gluing, also touch with glue about 1% in. of the under side at the joints so that the paper will stick. When the glue is hard, drill holes for the brads and see that the wedges are tight and the frame firm before using the ham- mer. Having nailed two corners, reverse the frame for the others.

with short tenons.—A. E. ELLING.

POPULAR SCIENCE MONTHLY SAVE HALF-INSTALL YOUR OWN PLUMBING 48> HEATING BY OUR NWew £asy Method ANY HANDY MAN can install his own Plumbing and Heating by our New/Easy Method and Save Half. In the past 50 years, we have saved our customers hun- a of thousands of dollars in the cost of: Plumbing 8, Pipeless and Warm Air Furnaces, Steam _ Boilers, Heewaren Boilers, Water Supply Systems, Water Heaters, Bathroom Outfits, Pipes, Radiators, Valves, Supplies, etc. BIG ‘ux BOOK Tells the whole story. tg the Hardin-Lavin New Easy Method. Send coupon with 25c (regular price 50c, refunded on first order) for yourcopy today. This Big, Instructive, Well-Bound “Handy Man” gos Catalog shows 10,000 items in latest a, highest quality a and Heating Fixtures and supplies at Whole- sale Prices, Hundreds of Trade Secrets Also shows many valuable diagrams, plans and elevations of simple installing systems, trade secrets and money, time and labor saving kinks. Complete Bathroom Outfit, built along practical and attractive lines. Highest grade possible to make. Shows that First pod Hardin-Lavin products can be had at low cost. WHITE ENAMELED BATH heavy white porcelain, enameled inside and aia the 3% inch turned-over rolled rim; outside painted. Newest Design. Fitted complete with heavy brass, nickel-plated compression bath faucet, withchinain- 30% in. aoe 4% or 5ft., weight 300 lbs, Chicago A-50— Bathtub complete as % 1 10 shown with iron-pipe connections. Special 3 e

TUB Cast Iron,

White Closet Outfit Improved, snow-white composition Chino Closet tank | (beautiful rapa ine destructible); fitted with solid brass elevated noise- ed waives and | improved china Yt flushing handl ledicine lighest Marade Cabinet, Special....... *895 it Grade White steele nlt Ss joints cleetrcaly rie 7) ed with white vitreous j fore ename! four coats of Highly pamehed. baked enamel, inside and out. Has reinforced b: plate glass bevelled aaeeees two plate mahogany ook, glass shelves, heavy glass ass knob and with heav enameled non-sag hinges. Cabinet is b raas,nickele guaranteed to be entirely satisfactory lated bar and carefully crated to reach you in inges, flushing first class condition. Hang on any

ell, supply pipe, || wall with two ecrews, Height 21 in., closet bolts, e etc., width 38 ia depth 5 in., wt. 35 lbs. weight 125 Ibs. No: 137—White enameled Cabinet c -S2 reduced te........ $8.95 —White cos os so tho co! as show! n with eh iron-pipe com $19.95 Lavatory Late design, white porcelain enameled, cast-iron drop apron Bvatesy. sup. ported on concealed wall hangers; new low design, china indexed come ee faucets, meavy brass, nickel

Most. valuable book of its kind pub- lished. SEND 25c FOR YOUR COPY TODAY. Bonded Guaranty We guarantee that every article we sell from the smallest fitting to a com- plete installation is perfect and exactly as shown and Read Our of the HIGHEST GRADE that is possible to manufac- Guarantee ture, We further guarantee that if you are dissatisfied for any reason, you can re- turn any goods bought from us and we will immediately our 50 years’ record refund your money plus of square dealing and } freight sharges you have about our new million paid. (Signed) SRDIN-LAVIN co. Geatdliin ing Be Valco? " Write this mnensine or your bank about

Super Improved Automatic Electric Water Supply System Spgeisetnas (hes —_ fool-proof and simple. Can be deper n to give lasting service with eee a. attention. No better outfit made for SHALLOW. WELLS OR_ CISTERNS Complete WHERE eee a NOT OVER a2. FEET BELOW SURFA' Noiseless Pome Runs in Oi! $ggs°o Noiseless, double acting, brass fitted throughout and fully enclosed and lubricated by the * ‘New Splash System.” All moving parts run in oil bath which insures long life. Latest type oversize 1-6 Horse Power electric motor, operates pee ooally and is thoroughly relisbler surplus power to drive pump under all conditions. Outfits Complete— No Extras System ronsists of pump with auto- matic air valve, oversize 1-6 Horse Power repulsion induction motor, automatic ewitch set at 40 Ibs., relief valve, shut-off valves, necessary pipe and fittings as shown; one galvanized heavy pneumatic tank with pressure gauge, one % in. galvanized foot valve and strainer. Pump has % in. suction’ and discharge. Outfit equipped with 60 cycle, 110-220 volt, single - phase alternating current motor. If you have other current, state voltage, etc. No. A.—-500. Water Supply System with 42 Gallon Tank. Shipping Weight 300 Ibs. Price, com- Diete, Special $98.50 No. A.—501. Water Su ply System with 80 Gallon Tank. Shipping

In another detail I show a square joint | . bine wthags 0 Ibs. Price, — ete, Special’ $110.50 No. A—502. Water Sup- ly System with 100 alion Tank. Shipping Weight 380 Ibs. Price complete, Special $122.50

"7 This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. supply pipes and trap to floor <= nthe size 17x1936 in., Rees! 20 tbs. Chi icago A-51—Lavatory. Com- plete ss. as shown with Iron-Pipe con- Speclah........, $11.75 Cc looae A-53—Bathroom outfit, complete as shown and de- scribed. 7 Peete $59.95 All shipped from Chicago plant sone day as order is received, der today. You cannot lose. Heating Plants Cut-To-Fit Hot Water—Steam— Hot Air—Pipeless Hordip-Lavin Cut - To - Fit Hot Water Heating Plants give highest heat efficiency at fowest cost. Boiler embodies best engineering; easy dump- ing grates; long indirect fire travel that insures complete combus- QW tion and greatest heat. Our modern equipment and 50 years’ any my an a! Bolle that will burn any Mond of fu

anly, WE HELP YOU PLAN, Every Hardin-Lavia Heating System is figured to eliminate long. runs of piping, to save valuable time, and expensive labor, With our complete instructions and simple installing features, you can Se the work yourself and saye. We loa the tools if necessa: WRITE TO- DAY FOR LOW WHOLESALE PRICES. Free Estimate Send us rough sketch, plan or blue print of your home and we will figure the wholesale cost of a simplified cut-to-fit Heating or Plumbing System that ex- actly meets your needs. We will show you — wrinkles where you can make money savings that will surprise you. Our Bonded Guarantee ,protecta you, Behind this, stands our million dollar nts — reoned of 50 years. COUPON TODAY HARDIN-LA ,LAVIN co. pa a le HARDIN-LAVIN CO., 106-16 W. Pershing Rd., Chicago, ill. Gentlemen: Enclosed please, find 25e (% regular price) for which eend me your Big Complete “Handy Man” Book « Catalog. | with special olesale discount sheets and FREE Bulletin Se am interested in ) Water Sply. System ( ) Plumb. Fixtures Steam Heat. Plant ( ) Bathroom Outfits ) H. W. Heat. Plant ( ) Pipeless Furnace Note:**Handy Man” Book is FREE if order accompanies coupons

NAME we sessecseserseeeeverenceeserseeensesesecseeeasnens ° ADDREGSB ...cccsccvccccccccccccccedcedsececccscosceess evce | ORI casa oae-desccdsdensasacunsame STATE....csccccccece ee

See page 21.

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| You can tell by the “Hang’”’ It’s a Maydole Next time you’re in the hard- ware store pick up a Maydole Hammer. Balance it in your hand. Swing it. It makes you itch to come down on a nail and drive it home. No other hammer has just the Maydole ‘hang’. It’s the result of 82 years of accumulated skill and experience in making fine hammers. The head is press-forged of selected steel, specially tem- pered. The handle is of clear, second-growth hickory, perfectly seasoned. Together they make a beautifully balanced hammer that’s in a class by itself for service and wear. Whatever style of hammer you want,—carpenters’, machinists’, or any other type —ask your hardware dealer to show you a Maydole. Once you’ve handled it you'll never be con- tent with an ordi- nary hammer. Write for our free pocket handbook 23 “B”’. It’s interesting © and useful. THE DAVID MAYDOLE HAMMER CO. NORWICH NEW YORK 7642 POPULAR SCIENCE MONTHLY —--- LMOST any little girl or boy from eight to 10 years of age would like to have this desk and chair. They are of simple construction and may be made of any wood, but preferably of well-seasoned oak. Each part can be laid out and cut to the dimensions indicated, or the sizes may be altered to suit the age of the child, if older than 10 years. The desk stands SEAT BOARD wxowxie © LEATHER 30" 7 a xeKu @® 4 $REO. ex We sie — eS OAK 1%" Z REQ. _. MORTISES e O LEGS We'xie"x30" A RED. Xive X30 (1m PAIRS) SEO: & EN @ 2" Pa oe CORNER BRACE (2) = OAK Ay 4 REQ. 2 REO. ® PINE " ES aF Se * @) Taran Lt jo" Jo," > OAK by 36'x14'xa% IPAIR REO. OAK 3 REQ. How the chair is constructed is shown by the numbered details in column directly above The Home Wor A Desk to Make Any Child Happy Kkshop 24 in. from the floor; the chair seat, 1514 in. Wood screws rather than nails should be used for the joints. The outside edge of the cover and back piece are rounded slightly, and the top is covered with desk cloth, stretched and glued. A piece of auto-top covering, if in fairly good condition, makes an excellent cover. If preferred, the top may be left plain. The cover is joined to the back piece with two 1)4-in. narrow brass butt hinges. Serape or sandpaper the wood as smoothly as possible. If a natural finish is desired, fill the wood with a paste filler and apply two or three coats of white (Continued on page 99) IS 2074" LONG 15%” WIDE ( xia Xiao" OAK 4 REQ. | I R135" QqQe—_h a> 143, 2 REO. oa @,**Rt 19% is (8) 2g ; Tx 1%a"X21%8 OAK7 cee In this column are the parts of the desk sim- ilarly numbered to show where they are used © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21. $$$ nt

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y 5% uld ack p is a +3%° POPULAR SCIENCE MONTHLY Fishing-Rod Shipping-Case Made from Rain-Pipe F YOU are in the habit ot carrying your fishing-rods without any protection save thin canvas cases, sooner or later they will come to grief in transit. A tube for two fishing-rods can be made readily out of a length of round gal- | yanized iron rain-spout tubing about 3 in. | longer than the rods when they are unjointed. Fit and nail a round piece of wood into | the lower end. Prepare another round | piece to fit tightly into the top and pro- vide. a strap handle. Cut a piece of canvas to fit over the tube, sew it along the side, turn it with the seam in. and slip the tube into it. The top of the canvas can be hemmed for a drawstring. Sew a neat round patch on the bottom of the | canvas casing.—ROBERT PAGE LINCOLN. A Desk to Make Any Child Happy (Continued from page 98) shellac. Rub smooth and finish with several coats of furniture wax. All the joints of the chair are tenoned and glued. Both top and bottom back ribs are alike and a templet can be made as a guide in working out the curves. The seat board, which holds the pad- | ding in place, is fitted in after the frame is put together, but it need not be a tight | fit. It rests on four angle pieces nailed _into the corners on the under side. In upholstering the seat, tack a piece | of stout cotton cloth along one edge and | about halfway on each side. The filling is | pushed under with the hand or with a flat stick. Be sure to get the filling well into | the corners. Pack it high and level in the | center and slope it away on each side to- | ward the edges. When the filling is all in, _ pull the remaining edges of the cloth tight _ and tack down all around. The outer cover may be leather or imi- | tation leather, cut to size and tacked at | four corners with carpet tacks to hold it in | Place. A piece of upholsterer’s tape or | gimp is fastened around the edges with evenly spaced upholstery tacks. Finish the chair to match the desk. | , Both the legs of the chair and the feet of the | desk are fitted with polished steel glides. | —H. L. WHEELER. | —$—$$ URTE TIME AND LABOR SAVING ORTER’S BOLT CLIPPERS and Wire Cutters are hand tools, develop- ing tremendous cut- ting power through a combination of leverages. Fifty pounds’ pressure on the handles delivers approximately three thousands pounds’ pressure at the cut- ting point. The three types of cutters shown in this advertisement rep- resent the particu- lar models most generally used. A good, all-round size of tool is represented in Size 3 with a ca- pacity of 54" an- nealed bolts in the thread. Other sizes have capacities ranging from “/16" to 34" annealed bolts in the thread. Spe- cial nut-splitting tools are obtainable in both side and end-cutting models. H.K. PORTER,INC. EVERETT, MASS. © Sold by-retail hardware stores and.carried in stock by leading hardware jobbers Angular Cutter: Side Cutter: A tool of all round service. Cutting jaws are parallel with the han- dles. End Cutter: Cutting edge on this tool is at right angles to the handles. Every. POR- TER Cutter is built on ex- actly the same principles. Differences be- tween the va- rious models lie in the types of cutting jaws. Jaws are set at 30° angle to handles. Gets into difficult places. Saves stooping. RS, IS) This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. a ge a ma pe yom eee epee aia = — ae; aot Sez woe

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ty a 80:7 ; “There is a difference in Hack Saw Blades —long life —fast cutting —uniformity That’s where the difference in hack saw blades shows up. Blades made by Millers Falls Co. at their West Haven ' plant will answer your most exacting requirements. Best quality tungsten steel— for long life. Milled teeth with special patented set—for fast cutting. Individually hardened— for uniformity. Same high quality as other Millers Falls Tools. All hard and flexible, in standard gauges. When you place your next order, insist on hack saw blades made by Millers Falls Company. MILLERS FALLS COMPANY Millers Falls, Mass. 28 Warren St. 9 So. Clinton St. ew Yor hicago Manufacturers of Mechanics’ Tools, Hack Saws and Automobile Tools MILLERS FALLS TOOLS © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21. ‘- POPUEAR SCIENCE MONTHLY evenly on the rails. as a piece of plate glass or marble. Ye'SCREW HOLES FOR UPPER TRANSOM = roa SSS Sg Vg SCREW HOLES FOR ns OWER a, ee PIECE OF MARBLE O8—~ OTHER FLAT SURFACE bE ecco ; ————* aa | a Fig. 1—Typical model railway truck made as described last month. Fig. 2—-Transoms and Fig. 6—Spring mounting. Fig.7—Pick-up shoe swing bolster. Figs. 3, 4, and 5—Details. weight rests evenly on all four flanges. If it ‘‘teeters” slightly, ease up a little on each of the eight corner screws until the truck comestrue. Bring the second truck to the same degree of advancement, if you have not already done so. Beginning with the upper transom (Fig. 2), place all the markings on its under side. With a fine saw (a hacksaw will do), cut a piece from your stock of the required cross section and of a length equal to the distance between the outer edges of the side frames. Test the ends | with a small square; then mark a cross line 1% in. from each end. Each of the cross lines should coincide with the median line of the side frame if your work has been carefully done. The center line of the transom now must be drawn carefully from end to end (Fig. 3). Then lay the transom in its proper position across the frames, hold it firmly, and with a soft pencil, mark the position of the screw holes on its under Model-Makings Third article in a series on miniature railroads By Edward E. de Lancey HEN the trucks of your model electric locomotive or coach have progressed to the stage shown in Fig. 1, it is well to ascertain if all four wheels of each truck bear To do this, place the truck on a true and perfectly flat surface, such, for instance, See if the ——— Ye HOLES > 22 HOLES (TAPPED) TAPPED Vee orkshop TOP SIDE-FRAME UPPER TRANSOM SWING. BOLSTER {CENTER PIN — te eee PICK-UP SHOE BOTTOM SIDE FRAME SSS UPPER TRANSOM VAX3% o {Ss LOWER TRANSOM Vax\%4X3% ss SWING BOLSTER Ye X94 X48 BRASS side. These will come on the cross lines, =i each will be 14 in. from the center ine. Now drill the preparatory holes (from the under side) for the flat-headed wood screws, using a drill somewhat smaller than the screws. We now have four holes that should register with the correspond- ing holes of the upper frame. After securing the upper transom, care- fully measure half the width and half the length of the- truck frame, taken as @ whole, to give you the location of the center pin. Mark this point, but before boring the preparatory hole for the round-headed screw that is to form the pin, test its position with a pair of sharp divicers. If center pins are not accurately placed, your locomotive will assume a skew position. Now insert the flat-headed screws and tighten up with a small-shanked, sharp screwdriver, for access is not direct. (Continued on page 101) Two model railroad coaches, one having a motor-truck like that described in this article — a ,

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s lines, center ; (from 1 wood smaller r holes spond- a, care- valf the n as a of the ing the headed test its ers. If .d, your osition. ws and , sharp ct. POPULAR SCIENCE MONTHLY ak (Continued from page 100) ing An alternative method of fastening the upper transom is to use the 1g by 1 in. machine screws. In this case, bore the holes in the upper frame with the drill that comes with the screws and use the tap that belongs to them. Do not countersink the holes. The holes in the transom must be fully 14 in. in diameter. Put the screws in from the top, and after they are tightened up, snip off their excess length with small-jaw wire cutters. Small brass washers under the heads of the screws are desirable. File the ends of the screws smooth and flush with the under side of the upper frame. This is important because a smooth, sliding contact with the swing bolster will be required at this point. smaller cross section, locate the holes in a similar fashion (Fig. 4), but remember that small round-headed screws, put up through the bottom frame, are used in this case. If they show through the top of the transom, file them flush. come within less than an inch of the upper transom, and, therefore, will interfere with the application of the screwdriver to the center pin. To forestall this incon- venience, make a 3%-in. hole in the center of the lower transom; later on, you can make a corresponding hole in the pick-up | shoe. You now are ready to attach the | lower transom. | ITH both the end beams and both transoms in place, the truck should | be tested on the flat slab. If any ‘‘teeter- ing” now manifests itself, ease up on all the transom screws, but leave the end | beam screws as they were. The truck now cannot get “out of square,” although it may impress you as being too loose jointed. Do not be disturbed on that account because a slight slackness will compensate for the absence of equalizers. We omitted equalizers from our design | because they would have complicated matters unnecessarily. It now remains to make the swing _boisters and spring plates. For the | former, cut a piece of 1/16 by 34 in. sheet brass, making it 1 in. longer than the width over the truck frames (Fig. 5). _ Square the ends carefully, and while you _ aré about it, make a second bolster for the | trailer truck. See that they match exactly in the matter of length, for if they do not, the spring plates later will be forced out of line, imparting a slovenly appearance to the whole locomotive. Then cut four pieces from your angle brass stock for spring plates, making them a trifle in excess of 114 in. long, so as to allow for filing off the burr at the ends. These are for the spring plates, one of _ them belonging to each end of each swing | bolster. Scratch a line across each bol- | Ster 14 in. from each end, using your Square for this purpose. Then, with the drill belonging to your 3/32-in. machine | Screws, bore two holes exactly on the | Scratch and \y in. from the side. Tap | these holes. | (Continued on page 110) For the lower transom, which is of a | The upper side of this transom will | Here’s The Correct Solution to That Tool Problem -Buy BROWN & SHARPE TOOLS ROWN & SHARPE Tools are a good investment. You'll find their long-lived accuracy helps you do better work. The very fact that you use Brown & Sharpe Tools brings you the respect of the men you work with. You'll find that these tools really give your skill every opportunity to show at its best. That’s why Brown & Sharpe Tools are the first choice for every tool requirement. Write for Small Tool Catalog No. 29. It lists over 2000 Brown & Sharpe Tools Brown & Sharpe Mfg. Co. Providence, R.I., U.S.A. © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21. SPCR TER Bab EE A apr ite ee OEE SOS ’ co RMgnre eee eremog ro . es fr rie ie ee Re

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AUGHAN Vanadium Hammers are aris- & BUSHNELL octrats among hammers. Made from special formula vanadium steel —handled with the best grade hand- shaved second growth white hickory —designed with a special non-slip claw that grips either a brad or a spikew— and equipped with a Vaughan’s Expansion Wedge that firmly locks the handle tight—they are made for you craftsmen that buy quality tools. V & B Unbreakable Planes bear the same reputation as V & B Vanadium Hammers. They are drop forged— not cast—from a solid bar of V & B Supersteel, and stand the falls and accidents that would break an ordi- nary plane. They are furnished with all vanadium steel blades and walnut handles in the sizes you'll want. Your hardware dealer will heartily recommend these two tools. Ask to see them when next you are in! © VAUGHAN & BUSHNELL MANUFACTURING COMPANY ms of Fime Toots 24 Carroll Ave.~ wt WL U.S.A. | © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21. | The Home Workshop POPULAR SCIENCE MONTHLY “Duck Foot’? Is Useful Tool for Patching Woodwork ENTS or small holes in woodwork, especially in cabinetwork or furni- ture that is given a natural finish, are repaired with stick shellac, which is made in colors to match all kinds of finishes. Finding it difficult to apply the stick shellac evenly, I devised the tool il- lustrated, which is simply a short length When heated, this tool applies stick shellac very evenly to holes and blemishes in woodwork of copper rod, 6 in. long, flattened at one end, bent over at an angle of 120 deg., and fitted with a handle. In use it is heated in an alcohol flame and then applied to the stick until enough shellac is melted to fill the depression. It is then used much like a soldering iron. The flat part is rubbed over the patch when completed to obtain a smooth finish. Plate for Preparing Dowels HE dowel maker illustrated is an old piece of steel 14 by 1 by 3 in. with 3 | holes 14, 3g, and 14 in. in diameter. The three countersunk spots of corresponding sizes were added to the tool for use in pointing the dowels after I read in the last November issue of POPULAR SCIENCE Wooden dowels can be made and pointed with this plate MONTHLY the article “Universal Dowel | Sharpener Made from Steel Block.” To make the dowels the wood is planed to about 1/16 in. larger than necessary and one end is tapered slightly to enter the hole. The wood then is hammered through.—H. CALDWELL. Awl Made from Old Spark Plug SMALL awl or prick punch may be made by removing the firing- pin and_ porcelain from an old spark plug and filing the end of the pin toa sharp point. Heat this until cherry red and plunge into cold water. It then can be given a needle point on an oilstone.— L. B. Rospsins, Harwich, Mass. m SPARICPLUG PORCELAIN May, 1935. - COURSE IN TWO YEARS YOU ARE BADLY if you tack HANDICAPPED HighSchool training. You cannot attain business or social prominence. You are barred from a successfu] business career, from the leading professions, from well- paid civil service jobs, from teaching and college entrance. In fact, em- ployers of practically all worth-while positions demand High School train- ing. You can’t hope to succeed in the face of this handicap. But you can remove it. Let the American School help you. FIT YOURSELF FOR A BIG FUTURE This course, which has been prepared by some of America’s leading professors, will broaden your mind, and make you @ keen, alert and capable. It is com- plete, simplified and up-to-date. It covers all subjects given in a resident school and meets all requirements of a High School training. From the first lesson to the last you are care- fully examined and coached, USE SPARE TIMEONLY Most people sdle away fifty hours a week, Probably you do. Use only one-fifth of your wasted hours for study and you can remove your present handicap within two years, You will enjoy the lessons and the knowledge you will gain will well repay the time spent in study. Check and mail the coupon NOW for full particulars and Free Bulletin, American $chool Desf. H-575. Drexel Ave. and $8th $?., Chicage RL! TS ETE, TRG TORTS NNN, RE WON TS OK ES oY omy, American School Dept. H-575 Drexel Ave. & 58th St., Chicago Send me full information on the subject checked and how you will help me win success, Law | | lear | if th | eati | leat the Spr | hon | not | con lize | of | | sta ant nat car gal spr spr

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mS ie 2ieh Be Baer era abe POPULAR SCIENCE MONTHLY Chemistry Simple Formulas that Will Save Time and Money oO garden spray will not kill all kinds leaves, a poison spray must be employed; if they suck the sap of the plants without eating the leaves, oil or dust sprays are the only practical means of control. Sprays of both kinds can be made at home more cheaply than bought. For insects that eat plants, arsenate of Jead is one of the best poisons. It will 'not injure the most delicate plant. It | | eonsists of 8 parts by weight of crystal- | | lized arsenate of soda mixed with 7 parts | of acetate of lead in water. These sub- | stances, when pulverized, readily unite and form a white precipitate of lead arse- nate. Anywhere from 1 to 5 oz. of this can be mixed with 5 gal. of water to make an excellent spray. Arsenite of lime is another effective spray. Boil 1 oz. of Mixing arsen- ate of soda with acetate of lead in water (above) and making a kerosene emul- sion (at left) white arsenic with 4 oz. of sodium bicar- bonate in 44 pt. water for 20 minutes, or until dissolved. One ounce of this stock solution, which will keep indefi- nitely, is mixed with 8!. gal. of water containing 3 oz. of freshly slaked lime. Astandard contact insecticide for sap- sucking pests is kerosene emulsion. Dis- solve 2 oz. soap in 1 pt. water by heating to just below boiling. Take off the fire and quickly add 1 qt. kerosene and churn or shake vigorously. For the control of seale insects 1 oz. of this solution is mixed with 9 oz. water; for ordinary sap-sucking insects, with 15 oz. water, and for soft bodied plant lice, with 20 oz. Disease-checking chemicals are pri- marily copper and sulphur compounds. A fungicide can be made by slaking 14 lb. of burned lime (calcium oxide) with 1 qt. water; add the water slowly and stir constantly. Then add !4 lb. flower of sulphur or finely ground sulphur, and boil the mixture for an hour. Strain out the lumps and label. Each ounce is diluted with 9 oz. water if it is used before or after the leaves have made their ap- pearance. When the plants are in full foliage, each ounce is diluted with 40 oz. Handle all poisonous sprays with great care and keep them from children. of insects. If the insects eat the | Home Workshop | | pil UE Trees gy 1S © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21. Here are the eight different size drill points furnished free with Mr. Punch, the Goodell-Pratt Automatic Drill. Bores holes without a split — that’s what Mr. Punch, the Goodell-Pratt Automatic Drill, does _ cabinets and other delicate, exacting work make this automatic drill more necessary today than ever before. Through hard wood without splitting it, through soft wood without crushing it, through plaster with- out cracking it—quick, clean holes when Mr. Punch is on the job. You push — he twists. Eight different size drill points ranging from 1-16 to 11-64 of an inch are furnished free with this drill— each kept in a separate compartment of the hollow handle. To get the drill point you want, merely turn the top cap of the handle and the point is released through the little top hole. All exposed parts of this automatic drill are nickel- plated and highly polished. Drill is 10 inches long and weighs 8 ounces. A handy size. Sold by good hardware stores everywhere. If your dealer hasn't it, write us. Send for the book of 1500 Good Tools Catalog No. 15 illustrates and describes each of the famous 1500 Good Tools made by Goodell-Pratt. In- teresting and valuable for tool lovers. Write for a copy. Nocharge for it. © GOODELL-PRATT COMPANY GREENFIELD, MASS., U.S. A. “ eg PNT ne ie ee pes Sap er el fh > RS => = expan we —

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504 POPUEAR ‘SCIENCE MONTHLY Be. May, 9g Americans will not wait Accustomed to instant communication by telephone and telegraph, our military authorities realized in the late war that the American Expeditionary Forces could not depend on the communication services of Europe. The necessary plans, materials and engineers were sent over in ship loads. A world record was made by the Signal Corps in establishing lines of communication indispensable to every branch of the army. In a surprisingly short time, every American general in France had at his disposal the communication facilities to which, in America, he had been accustomed. Europe was sometimes startled by the amazing methods of the telephone workers from overseas. The American- trained Signal Corps units invariably sought the shortest way, overcoming all natural obstacles to extend the needed means of communication. The Americans were not content to wait. They expected and demanded the same ever-ready telephone connections which they had at home. The Bell System has set a world standard for prompt attention and continuous service. AMERICAN TELEPHONE AND TELEGRAPH COMPANY AND ASSOCIATED COMPANIES BELL SYSTEM wi One Polic , One System, Universal Service %e Ras $25.00 in PRIZES sunt eat Let Boice Help You Build It! No matter what you want to build. Boice can help you. B u 4 He’ll send you the Now Boice-Crane Junior Saw or any other Boice-Crane machine on monthly payments. He gives you unsurpassed prices and values witha itive ney-back guar- antee. Machine shown will saw, Pay a few » grin r, rabbet, tenon, ete. Seardy accurate, cents a day e ical. Saws 1:4’ stock. . Sold with of without motor. the Boice way! Write today, for Descriptive Catalog of Bench Saws, Drills, Jointers and Band Saws and the Boice E-Z-Pay Plan. W.B.&J.E. BOICE Poe. P.S. 5-A, Toledo, Ohio « ’ a ~ ‘orld’s Lepegt pfebers of Small The Home Workshop How to Re-Upholster Chairs (Continued from page 79) the original one was, two sets of new springs were purchased. The old springs were moved to the position shown anq fastened with nails to the corner block, (Fig. 2). This illustration also shows the new springs being nailed to the side rails of the chair. After the springs are in place, whether sewed to webbing or held in the manner explained, the next step is to tie the tops in a position to give the seat its shape, . Figure 3 shows the springs tied and the worker driving the last tack. In this particular operation you should keep in mind how the original job was tied and]. do the new work accordingly. r Tie a simple knot in one end of a piece of spring twine and drive a 10-oz. tack |: through it into the rail at a point in line with the center of a row of springs, Stretch your twine over the top of the]: springs to the opposite rail and, allowing |: about a foot of twine extra, cut the piece from the ball. aT} Bet of the knots to use for tying springs is the clove hitch. It is made as follows: Working from the front rail toward the back, hold the twine and the spring nearest the fastened end with the thumb and forefinger of the left hand. Hold the spring in the desired position and with the right hand pass the free end of the twine down inside the coil, then up and under the first loop of the coil and to the left of the fastened end. Draw this loose end over the tight cord and down inside the coil again, then up on the right side of the fastened end and run it through the loop thus formed. Slide the knot until the spring is exactly where you want it and tighten. Proceed to the opposite side of the coil and tie the same kind of a knot, but in this case the twine first is passed down on the outside of the coil. Before tying the second spring, be sure to space it at a top distance equal to the distance between the coils at the bottom. Continue across the row of springs, mak- ing a knot at every intersection of spring and cord until the opposite rail is reached. Fasten the second end of the twine by driving a tack partway into the rail. Wrap the end once and a quarter around it in such a way that the slack end lies uppermost when the tack is driven ins After making sure that the whole row is tight and in the proper position, drive the tack securely. Drive a second tack through the loose end close to the first- one. When fastened as described, long use of the chair will not cause the twine to be cut off through coming in contact with the head of the first tack. How the springs look when all are in position and how the diagonal strands are tied are shown in Fig. 3. Take part- ticular care in tying subsequent rows of springs, after you have done the first one, to keep an equal tension at all times. In Fig. 4 you will notice that wooden strips, having their inside edges rounded off in order to prevent catting the twine, are nailed to the rails. This is not always (Continued on page 105) © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21. ee Mas yo wee a. ¥ So ee, ee eee oe

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airs f new prings n and blocks WS the rails hether lanner ie tops ape. . d and [n this | eep in| d and |. A Diece . tack |: in line prings, of the |: lowing | e piece tying $ made nt rail nd the ith the hand. osition ne free 1e coil, of the 2d. end. nt cord hen up nd and ‘ormed. exactly of the ot, but d down be sure l to the bottom. Ss, mak- f spring eached. wine by he rail: around end lies iven ine > TOW is 1, drive nd tack the first- od, long le twine contact | are in strands ake par- rows of irst one, 1 times. wooden rounded e twine, t always May, 1925 The Home Workshop How to Re-Upholster Chairs (Continued from page 104) done, but in this construction it furnishes a much smoother and longer wearing edge. The illustration also shows how a piece of 12-0z. burlap is tacked over the springs. Notice how the corner is cut out to pro- vide a smooth fit around the leg. When tacking on burlap, it is well to turn the edges under as you go along. This gives greater strength. Tack the burlap over the springs only moderately tight, for the spring reaction should all come on the twine and not on the burlap. Stuffing tow and roll-sheet wadding are shown in Fig. 5. Other materials such as kapok and moss also are used. The stuffing is placed on the burlap and scratched about and piled up until the ap- proximate shape of the seat is obtained. The wadding then is spread over the top and the corners are drawn down like the burlap. A few tacks are driven along the edges to hold it in position. Sometimes afew stitches are taken through the seat. Muslin or ticking next is stretched over the whole (Fig. 6). The tacks are driven in only a short distance. This is called slip tacking and is necessary because in putting on the muslin you will have to draw out any wrinkles. ONSIDERABLE patience is required in all upholstering work and at this particular point you may have to tack and retack a number of times before you get a smooth, unwrinkled surface. This is a good place to practice cutting out and fitting corners as shown in Fig. 7, and to gain practice in fitting a smooth edge against the legs so that when you put on the final cover you will make no errors. Figure 7 also indicates how the final cover is slip-tacked along the front rail. When cutting out the corner to fit around the legs, be sure to take out only a small square at first; that is, do not try to get a final fit the first time, but gradu- ally cut and fit until when you fold the edge under for the last time it will fit snugly against the leg on both sides. Figure 8 shows a good position to assume when stretching on the final cover. The left hand draws the wrinkles out of the cover from the front toward the back while the right hand takes up the slack. Remember that you must be patient in doing this. You may have to remove the tacks from a whole side in order to remove some little wrinkle; so do not drive any tacks home until the surface is smooth. The completed job is shown as the initial piece on page 79. You will notice the gimp or edging is in place, thus cover- ing up the rough edges of the cover. A good rule to follow in spacing any orna- mental tacks is to drive in the two end tacks first, then the center one. Drive two additional tacks at the centers of the spaces thus formed and divide all new Spaces in a like manner. : In a future article the method of attach- ing webbing to.a chair frame, how to sew Springs to it, and also one method of building up a so-called “hard-edge spring seat,” will be explained. ‘POPULAR SCIENCE MONTHLY rf e SARGENT particularly good planes. The two Sargent Planes illustrated here should be on every home and school work-bench. First, because they have proved their ability in the hands of exacting carpenters in shops and out on building jobs the country over. Secondly, because they are most moderate in cost and are built to withstand the wear and tear of hard usage. SARGENT & COMPANY, Mrrs. PLANES Planes that suit the carpenter are the ones for you to use YOU are eager to get the profes- sional touch into your work. To do this it is necessary first of all to use good tools and Sargent Steel Block Plane No. 5206 Sargent Auto-Set Bench Plane No. 714 The Sargent Auto-Set Bench Plane has a feature that saves much delay. The chromium steel cutter may be removed for whetting and replaced without changing original adjustment. Yet, in place, the cutter is as rigid as can be. For end work and the smaller jobs, you can’t beat the Sargent Steel Block Plane. These two planes fill practically every need you may have for a finishing tool. They will help you get professional- looking results. At hardware Stores. Write us for booklet. 50 Water St., New Haven, Conn. | NEW VEST POCKET ADDING MACHINE —nothing to get out of order. Everyone who uses figures should own one. Counts Up to 999,999,999 ¥g— Total visible at all times. A pull of the finger clears it. Don’t carry a pocket full of pencil stubs and scra ) Paper todo your figuring. Carry a Ve-Po-Ad. \ : Send no money, \ 10 Days Trial Just name and ad- | dress and we will send machine tpaid. | Pay postman on delivery $2.95. Use it for - i 10 days to prove it does all we claim. \ mi, not perfectly satisfied we will refund your 7 4 money. Limited supply. Send order today. Reliable Adding Mach.Corp.,Dpt, 185, 170 W. Washington St., Chicago, Ill. Adds as rapidly and accurately as a $ po machine, yet fits the vest pocket. 95 : echanically perfect. Easy to operate pcs o CED AD Here’s a money maker. Everybody E N ij Ss wants one. Splendid profit, "Write for special offer. | © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21. GENTS spark Pivc : Y Visible Flash Just Out— Amazing Invention— “= Beacon Lite Spark Plugs. You —- see the flash of each explosion in “SEE, the cylinders. Tells which are firing ri; Ss Greatest improvement in spark lugs | => since gas engines were invent on- derful gas savers. Agents coining money. EK Easy to make with new sure-fire plans. Sells on = sight to every autoowner. Phillips, Ont., writes “Sold 2 dozen today, 3 dozen yes- = terday. Rush 10 dozen.” Write for s cial Free Demonstrator Offer and FR: deal to introduce these wonder spark plugs in your territory. Write quick—today. CENTRAL PETROLEUM COMPANY 612 Century Bullding Cleveland, Ohie Pe Cees ee Ye tae eens edt Fb AB A

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O000D An Easy Way to Learn PHARMACY AT HOME Graduate pharmacists are al- - ways in demand. The work is in- teresting and pleasant and salaries are good. Many young men open drug stores of their own and be- come independent. There’s an easy way to learn pharmacy right in your own home in spare time, without losing a 7 day or a dollar from your present ’ work. The International Correspon- dence Schools course in Phar- macy supplies the knowledge which it will be necessary for you to have in order that you may pass your State Board Examination. Just mark and mail the coupon printed below to the International Correspondence Schools, Box 7651-D, Scranton, Pa., and full particulars about the Pharmacy Course or any other work of your choice will be sent to you by re- turn mail. INTERNATIONAL CORRESPONDENCE SCHOOLS : Box 7651-D, Scranton, Penna. Without cost of obligation on my part, please tell me how I can qualify for the position or in the subject befor which I have marked an X _] PHARMACY BUSINESS TRAINING COURSES Business Management 0 Salesmanship Industrial Management Advertising Personnel Organization Better Letters Traffic Management Show Card Lettering Business Law Stenography and Typing Banking and Banking Law Business English Asceuntaney (incleding C. P.A.) ( Civil Service Nicholson Cost Accounting (J Railway Mail Clerk kkeeping ( Common School Subjects Private Secretary 0 High School Subjects Spanish 0 French Cj Illustrating TECHNICAL AND INDUSTRIAL COURSES Electrical Engineering O Architect Electric Lighting Architects’ Blue-prints Mechanical Engineer Contractor and Builder Mechanical Draftsman Architectural Draftsman Machine Shop Practiee Concrete Builder Railroad Positions Gas Engine Operating Civil Engineer Surveying and Mapping Metallurgy 0 Mining Steam Engineering 0 Radio Structural Engineer Chemistry Automobile Work Airplane Engines Agriculture and Poultry Mathematics icc ds sala cate butioks dbavaveinvunl deateobeeulses itm vooreseesersvoes Persons residing in Canada should send this coupon to the International Correspondence Schools Canadian, Limited, &fontreal Canada © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. POPULAR SCIENCE MONTHLY Kitchenette for cians Cooking (Continued from page 80) soldered. A board across the bottom of cabinet stays the metal sufficiently to support the lid, which is wood covered with metal. It makes a strong table. The supplies were decided upon after three months’ camping in a tent. Many apparent necessities at home are luxuries or a nuisance on such a trip. It was found to be more convenient to use a refrigerator basket than to build a refrigerator in the bottom compartment. However, a refrigerator can be made, if desired, by insulating the bottom, sides, and removable upper lid. Since the stove is used at every meal, this would rest with its container on top of the refrigera- tor, so that when it was removed the refrigerator lid could be raised. One such refrigerator has a drainage hole in the bottom with a small tin funnel passing through a hole on the runningboard. When height is added in this way to the case, a stay at the top will be necessary. LL containers are designed to hold amounts that can be purchased cheap- ly, that is 1 lb. of commercial shortening, which does not melt or get rancid like lard; a paper carton of salt, flour, sugar, cornmeal (especially necessary for frying fish and for hoe cakes), all placed in 2-lb. coffee cans; cocoa, mustard (for salad dressings), tea, and the like in 14-lb. tea cans; rice, prunes, tapioca, and similar supplies in 1-lb. tea cans. The square tins waste no space as do round tins. In the reserve space should be carried tins of peas, corn, Lima and baked beans, macaroni, beets, condensed milk, soup and spinach, and the like. : Too many campers on a long trip eat cold meals, or expend a great deal of money for restaurant meals, thinking that one ean cook little en route. With a sys- tematic arrangement like this kitchenette, one may have at a moderate cost good food with less effort than is usually exerted when preparing such a meal at home. Automatic Feeder for Poultry Operated by Alarm Clock 1” YOU do not wish to attend to your poultry more than once a day, you will find an automatic feeder advan- tageous. Fasten a large box with an open top and a hinged bottom to the roof of the chicken house. Run a cord to an alarm clock as shown and place a wire hook at the end of the string over the alarm winding key in such a way that when the alarm goes off at noon, the key allows the hook to slip off, thus scattering the contents of the box.—R. C. TARR. YOU 100 CAN PLAY THE «. HAWAIIAN GUITAR 2 %e JUST AS THE HAWAIIANS Doy- ileal, ue LATEST HITS Ss 4 MOTIONS f used in playing the fascinating Hawaiian Gui- ha tar. Our native ; Hawaiian instrue- ‘ ; ors teach you to m quickly. Pictures shen fhem Everything explained clearly’ PLAY IN HALF HOUR After you get the 4 easy mo- tions, you can play harmonious chords with very little practi 40,000 students have learned play i in this easy, pleasant w EASY LESSON; The 52 printed: lessons with q ical knowledge necessary, Y, learn to play any kind of bs pay as you play. pists FREE Gu 1 As a special offer to it A sens we give this Aat size, e Ve every. ‘ain. post card will a Ask tora ~ ae cial offer and easy te First Hawaiian Cons of ay inc. 233 Prondaray (Wi orth Bidg,, Dept, 46, New ¥ York, N.Y.; Special courses on Vio- lin, Tenor-Banjo, Ban- p20-Uk kulele and Ukulele } Tests Show Ford Can Run 60 Miles On Gallon of Gas The amazing fact that a Ford can run 60 miles on a gallon of gasoline was recently brought to light through tests con- ducted by America’s fore- most engineers. Great strides have already been made in this di- rection by the recent invention of a simple attachment which can be installed in a few minutes without any alterations to motor. A. C. Winter- burn made 41.4 miles on 1 gallon of gasoline after this device was attached. B. O. Weeks, famous aviator and in- ventor, wants agents and will send sample for trial. Write him today at 426-800 Eleventh Street, Milwaukee, Wisconsin. Motorcycle Bargains SAVE 25% to 65% on Slightly Used and_ Rebuilt Motorcycles, Ace, Indian, Excelsior, Harley-Davidson, Cleveland, Side Cars, Johnson Motor Wheels, Evans Power Cycles, Bicycles. Send for Free Bargain Bulletin § and Money Saving Message, listing hundreds of ee bg used, rebuilt and new machiees supplies, eccemaeet, RICAN’ ‘MOTOR CYCLE CO. Dept. 528 2047 W. Chicago Ave. CHICAGO Contains interesting Radio infor- mation. Complete list of U.S Broadcasting stations wit space to log station. All hookups. How to operate sets. Construction of aerial. Write today. STANDS FORD RUNS 57 MILES ; ON GALLON OF GASOLINE A new automatic and self-regulating device has been invented by John A. Stransky, 204 Fourth St. Pukwana, South Dakota, with which automobiles have made from 35 to 57 miles on a gallon gasoline. It removes carbon and reduces spat plug trouble and overheating. It can be install by any one in five minutes. Mr. Stransky wants distributors and is willing to send a sample at his own risk. Write him today.—Adv. See page 21. ee BS ee = -

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n 60 miles rought to

Radio infor- ist of U.S Lom 8 with netructoa of 0 CORP, N ST. Grow? =S ON LINE device has Fourth St., utomobiles _ gallon uces spa! ye install isky wants nple at his

Act Now if You Wish a Smoking- Cabinet Blueprint

N la it Al ! My

O MANY times has the tracing for our No. 2 blueprint gone through the blueprinting machine that it soon will have to be withdrawn. If you expect to make a smoking cabinet, it will pay you to send for this blueprint.

Complete List of Blueprints ged one of the blueprints listed below can be obtained from POPULAR SCIENCE MONTHLY for 25 cents. The Editor will be glad to answer any specific questions rela- tive to tools, material, or equipment. Blueprint Service Dept. Popular Science Monthly 250 Fourth Avenue, New York Send me the blueprint, or blue- prints, I have underlined below, for which I inclose.............. cents: No. Title Price ES re 25c Bomonene Caniinet...... oc. cece 25c 3. Book Trough End Table......... 25c ES eS OT re 25¢ Srmmnving Ceuimet. .........5..005 25c 9. Arbor with Gate and Seats....... 25c OE Ore 25c 11. Bench and Tilt-Top Table....... 25c 12. Electric Washing Machine....... 25c SS ESS re 25c 14. Toy Train, Horse, and House..... 25c 15. Home Workshop Bench......... 25c 16. Inlaid Radio Cabinet............ 25c 17. Cedar and Mahogany Chest...... 25c 18. Telephone Table and Stool....... 25c 19, Grandfather’s Clock............. 25c Me REE BOD PICS... oo csc ves ees 25c 21. Colonial Writing-Desk........... 25c 22. Girl’s Cabinet and Desk......... 25¢ me, Pergola Garage. ... 2.2.0. cece 25c ere eee 25c 25. Sailing Outfit for Canoe......... 25c 26. Baby’s Crib and Play Pen........ 25c 27. Kitchen Cabinet Work-Table.....25c 28. Pullman Play Table............. 25c 29. Toy Tea Cart, Garage, etc....... 25c 30. Tool Cabinet, Bench Hook, etc. ..25c 31. Priscilla Sewing Cabinets........ 25c 32. Chinese Game Table............ 25c¢ 33. Pullman Dining Alcove.......... 25c 34. Trellises for House and Garden. . .25c 35. Simplified Radio Cabinet........ 25c 36. Rush-Bottom Arm-Chair........ 25c 37. Simplified Bookcase............. 25c 38. Sheraton Table................. 25c 39. Salem Chest of Drawers......... 25c 40. Writing-Desk in Sheraton Style. .25c 41. Up-to-Date One-Tube Set ...... 25c a GRR Ra See co ee ar (Please print) ME ase raise cieys ocak ic siciaiia araneve'e: be ia-einine RN BUS PEE os 6.0yshe.cle disse isi sieribses whetalaiviaes

|

| you wish.

POPULAR SCIENCE MONTHLY |ONE Easy Payment

13" x 5' Quick Change Gear Screw Cutting Lathe PRICE $354

107

Puts This 13" x §' Quick Change GEAR In Your Shop We ship any size Lathe you need upon receipt of first pay- | | ment—then you pay balance in convenient monthly install- | ments which the Lathe itself will save and earn for you. 32 Major Improvements made in South Bend Lathes in the last two years, establish new standards of accuracy and efficiency. eign Countries. More than 32,000 in use in U.S. and in 64 For- For example, South Bend Lathes are used in 2 largest Steel Plants, 8 largest Auto Factories, 5 largest Railroad Shops, by largest Oil Company, by U. S. Government, etc. Get Our FREE Catalog Shows 96 styles, all sizes. Lathe you want. prices. Select just the Note our money-saving Pay on convenient easy terms, if Send Coupon for Free Catalog. SOUTH BEND LATHE WORKS 317 E. Madison St., South Bend, Ind.

seilalaceniiglepcclaigagiaagrnens ght ail SOUTH BEND LATHE WORKS, a # 317 E. Madison St., South Bend, Ind, | Gentlemen: I would like your factory prices § @ and terms.on a oi. oo ics adeceeweses Lathe, i | Please Send Free Catalog. . ' | INNIS: < ocisu<reacied arog oaareeinale oe ae 5 I AGGPCSS iii ic cccccaveeeccceceseseceseceseen . |

$25.00 in PRIZE See top page 8 in front of book for details

‘Old Town Canoes’ a A aa ’

Double the charm of your outing WHEN you plan your vacation this year, be sure to include an ‘Old Town Canoe” in those plans. “Old Towns” are light—they respond quickly and easily to every stroke of the blade. In design, “Old Town Canoes” are beautiful. They are patterned after real Indian models. The price of “Old Towns’’ is remarkably reasonable. $64 up. From dealer or factory. * & k * The 1925 catalog shows all models in full colors. It is free. Write for your copy today. Otv Town Canoe Co., 1595 Main Street, Old Town, Maine, U.S. A.

IS} This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21.

Devendall (60 Million Satisfied Customers) Good Looking (Lmproved Model. a handsome watch) Big Value (You get the benefit of the saving . from immense quantity production)

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@ pair today. Re / @ \ ‘ Established 1857 Klein Pliers. get my hands on them again. man feels that way about good tools. Yes sir, most men do feel that way. That’s one reason why Klein Pliers have been the favorites for 68 years. You'll notice that most hardware stores feature them. Electrical companies specify them! Treat yourself to Mathias Pil Fix It! NOTHING could be simpler with these Fact is, I’m glad to- ‘ POPULAR SCIENCE MONTBLY * ] guess every KLEINe:us Rgreme a rosperous / Bicycle M4 Dealer/ im HERE is a big oppor- tunity for live, ener- getic, ambitious young men to establish themselves in their own profitable bicycle business. With more bicycle sales than ever before, the chance to cash in, on a very mod- est investment, never was brighter. You can be your own boss —make a good profit—be absolutely independent—put money in the bank. Don’t work for somebody else all your life—go in for yourself, NOW, in a clean, pleasant, well-paying business. Ann Shop Special Write TODAY for full par- ticulars to Dept. 251. CYCLE TRADES OF AMERICA Incorporated 35 Warren Street New York No.7 $2502 Illustrated with motor THE MOST POPULAR MACHINE PARKS EVER BUILT! A winner from the start. convenient size for the small shop. Does everything in woodworking. Has circular rip and cut-off saw, 6- inch jointer, 16-inch bandsaw. Lathe and shaper attached if desired at small cost. Operates from any light socket. Just plug in and go to work! Write for interesting circular The Parks Ball Bearing Machine Co. 1547 Knowlton St., Cincinnati, Ohio Canadian Factory: 200 Notre Dame East, Montreal, Canada bern Merl erat bere tert DWORK ab abinet A real machine, yet © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21. Toy Horses and Cars By Charles M. Miller Assistant Supervisor of Manual Train. ing, Los Angeles City Schools M?2st popular with the youngsters these days is a toy car with a frame work that resembles a horse. In making one of these horses, a realistic effect is obtained simply by placing the axle of the rear wheel off center about \% in. The axle is a 14-in. rod, about 12 jn, long, threaded at each end for 1% jn, Three washers and two nuts are used, ag shown, in holding each wheel in place, The eccentric wheels must be adjusted go that their motion will be alike, otherwise the car will wabble. Some kind of special hinge is nece to allow the fore part of the horse or other _ REAR VIEW OFA PLAIN TYPE >| SADDLE Why, STEERING HANDLE HINGED FRONT 5 STRAP IRON! ex |" HINGES SET IN SAW KERF = “ASHER HOOK AND SCREWEYES How to mount the rear wheels off center to get a galloping effect; various steering joints animal to be turned for steering. A variety of construction may be used, a few types of which are shown. If screweyes are used, they should be heavy, but the eyes comparatively small. Two butt hinges inserted in saw kerfs form a splendid joint. A long piano hinge, which can be bought by the foot at almost any hardware store, can be cut up to make an even better hinge. Two hooks and two screweyes also may be used, in which case the joint is assembled by tem- porarily twisting one pair sideways. What- ever kind of hinge is used, the joint must be pivoted on the center line of the body. Dressing a Grinding Wheel WORN WHEEL £ HEN an em- ery wheel or 4 restored by dressing it with a tool made as shown from 4 * number of washers _ of equal size and 4 as “ rod or long bolt. The washers should turn freely. The bolt is rested upon the frame of the grinder so that the washers will come in contact with the rapidly revolving face of the wheel. Only enough pressure is re quired to keep the truing tool steady. ——

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Is igsters frame. ealistic ng the out 4 ; 12 in, 5% in, sed, as place. sted so 1erwise cessary r other ater to , joints ing. A used, a ould be y small. w kerfs y piano 2 foot at e cut up vo hooks used, in by tem- 3. What- int must he body. heel an el- wheel or has be |, lumpy, it'‘can be dressing ol made from 3 washers ze and 4 ng bolt. ne of the come in g face of re is re eady. ———— ee | | spray can be obtained. | better way of holding the pipe at a correct The Home Workshop Easily Made Spray Waters Narrow Strips of Lawn By Dale R. Van Horn ‘a of the best ways to water narrow strips of lawn is to purchase a 10-ft. length of 14-in. water or gas-pipe and after drilling 1/32-in. holes at 6-in. inter- vals, attach this to the hose. The far end of the pipe is capped. Once attached to the hose, the pipe can be dragged where desired and, by kinking | the hose slightly, any desired angle of | If preferred, a quarter-turn elbow may be attached between pipe and hose; this provides a angle. Cabinet for Printing Photos (Continued from page 81) The illustrations (page 81) show the con- struction of the cover of the printing box. Its main features are the two wallboard shields, which are nailed inside the print- ing-frame opening. These prevent any direct light from striking the frame. A strip of 14-in. beading runs around the under side of the cover to keep it in place | when in use. This may be the tongues | ripped from some matched boards or any small strips of soft wood. | The ruby lamp is constructed from a wooden box, having a sliding cover. In | my case, it was picked up at a friendly grocer’s. The cover is discarded. Cut two pieces of clear glass, one fitting the groove for the cover, and the other slightly smaller, to fill the space just out- side the groove. Screw a socket in place on the bottom of the box, the wire being led out of a small hole cut in one side, after being heavily taped to prevent leak- | age of white light. ~ The writer found that the use of two sheets of colored tissue paper, one orange, the other deep red, made a lamp that was safe to use with ordinary plates and film. By screwing the box to its supporting bar in an offset position, with the red side of the box down, a red light will be thrown directly on the work table, where it is most needed, and the lamp itself is out of the way. The arrangement of screws on the back of the cabinet, as shown in dotted lines, makes it possible to fold the lamp and bar to one side and down, out of the way, when not in use. All the corners and edges of the work- | lamp box should be bound with heavy | paper, to prevent leakage of white light. | POPULAR SCIENCE MONTHLY 109 More Power per Tube— Greater Economy— C/R:KIT 1lto 5 tubes for loop or antenna ER L A and Pride with Only CIR-KIT brings you the fundamental ad- vantages which make Supereflex more powerful tube for tube. With one tube doing the duty of three; with three tubes rivaling five in conven- tional arrangements, Erla Supereflex circuits excel in power, with less tubes to buy and operate. Originally made possible by the special design of Erla Scientific Precision Apparatus, Supereflex cir- cuits are most perfectly constructed with Erla Supereflex CIR-KIT. With this complete assort- ment of genuine Erla parts; with screwdriver, pliers, and an evening’s time, you can follow the simple CIR-KIT instructions to a finer radio re- ceiver. Its construction, range, volume, selectivity and typical Erla tone clarity will give you cause for endless pride. And you will be money ahead. Electrical Research Laboratories Department S, 2500 Cottage Grove Avenue, Chicago MONTHLY $150 #8300 PRorirs Own your own big money- making battery charging busi- ness, $35 cash brings complete H-B One Day Battery Charg- } ing Outfit. Long, easy payments. No experience needed. Big profits easily made, 30 days trial on money- back guarantee. Write for tree bulletin. HOBART BROS. CO., Box P-S Troy, Ohio. ONE DAY GhAncixc TOOL CHESTS FOR PARTICULAR MEN Toolmakers and Ma- chinists will find the right Case in our FREE CATALOG Send for it TO-DAY, H. GERSTNER & SONS 517 Columbia St., Dayton, 0. © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21. EARN $2,000 TO $10,000 A YEAR STUDY AT HOME OPPORTUNITY is at your door. Learn Airplane Engineering now. Write for Free Catalog Dept. P-5 Monadnock Block WESTERN AIRPLANE CORPORATION CHICAGO oh nos Tee lk SAN Vile of! a at oer int ARO A

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Where to Look for | Speedy Improvement IS there any machine that can't be improved—or bet- ter operated? It’s not so recorded on a Veeder counter. When a counter goes on, pro- duction goes UP; the inventor gets busy or the operator gets busier on the job. Production only goes back- ward when nobody’s looking. You're always looking for speedier records — and get- ting what you look for—on COUNTERS Thissmall Rotary Ratchet Counter (No. 6) counts reciprocating movements of the lever, as required for recording the output of innumerable small machines. When the lever is moved through an angle of 40 to 60 degrees, the counter regis- ters one. The further the lever is moved, the higher the number registered. A complete revolution of the lever registers ten. This counter can be adapted to no end of counting purposes, by regu- lating the throw of the lever. Price $2.00. (Cut nearly full size.) Small Revolution Counter, also $2.00. The Hand Tally illustrated below is used for counting anything from number of people in a public place, to number of packages in an inventory. In the fac- tory or store it counts stock; in the “open” it may count anything from cattle on a ranch, to poles on a telephone line! Registers one for each pressure of the thumb lever; counts up to 10,000, then repeats. Can be set back to zero from any figure by turning knob once round. Size, exclusive of finger ring, 2 inches greatest diameter. Price, $5.00 Write us about that counting problem of yours—or see how it’s solved in the Veeder book- let; copy free. The Veeder Mfg. Co. 44 Sargeant St. Hartford, Conn. | and projects equally at each end. Next | a way that one of the tapped holes in the | swing bolster is clear of the vise jaws, and, _ using the hole in the swing bolster as a | Insert a 3/32-in. screw through the spring | it smooth. Treat the remaining hole | similarly. POPULAR SCIENCE MONTHLY Simplified 1 Model Making (Continued from page 101) Place an angle brass across the end of a swing bolster, so that the latter abuts firmly against the inierior angle of the former. See that it fits snugly, is square clamp the combination in the vise in such templet, drill through the spring plate. plate until its head comes firmly against the latter. Then remove from vise, snip off the excess length of the screw, and file ‘THERE are four such jobs as this, all requiring care and patience, but their May, 1925 How Springy the Bristles Feel! The best painters are —' WHITING-ADAMS BRUSHES. Geta good brush — one that will last and give years of satisfactory service. WHITING- ADAMS BRUSHES give the kind of service you want. WHITING -ADAMS BRUSHES RYO ea Illustrated Literature SOHN L. WHITING-J. J. ADAMS CU. BOSTON, U. 5. A. Brush Manufacturers foi Over! 16 reward will be an easy riding and pleasing locomotive. swing bolster for the center pin. Remem- ber the stress that we have laid upon the accurate placing of center pins. Be equally painstaking in boring this hole. Last of all, don’t forget to file the bevel on the inner edges of spring plates, as in Fig. 6. | outfit through the frames and between the wheels. Be sure to place the -in. tightening it; then slack up just enough | to leave an easy sliding contact be- tween the swing bolster and the upper frames. return current shoes. The former is a piece of spring brass stock, not less than 314 in. long. It is attached to the middle of ihe under side of the lower bolster. In this position it will be seen that it covers the hole we have left for the screwdriver; a corresponding hole in the shoe, or by clear the Te ty Rao the shoe approximately as in Fig. 7, but see that there is always a bend, never a sharp angle. The attaching screws may be placed so as to form a letter V, with one of the three screws at | the point of the V preferably nearest the | spring end of the shoe. Give the shoe | just sufficient pressure on the third rail to | keep it always in contact, but never let it bear hard enough to act as a brake. The return current shoe is simply a | piece of 1/16 by 4 in. brass, long enough to reach from the outer edge of the end | beam to about 4 in. beyond the nearest | a axle. It can be bent sufficiently by eye before attaching, but must have no sharp | angles. Fasten it with a broad-headed brass wood screw to the end beam farthest | from the gearing. Put a small brass | | washer under the head of this screw. | Next month we shall | method of mounting the motor on its | truck and, perhaps, say something about | | the body and. wiring. 3) This seal. on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. Before attaching the pivot-spring rig- | ging, it may be necessary to remove one of | the spring plates, in order to pass the | washer around the center pin before | We now are ready for the pick-up and | but this can be overcome either by making | cutting a 3-in. slot far enough back to | explain the | Ycarsand the Largest in the World It remains to locate the hole in the eo. Evei "yone Inferested ; in RADIO. Should. Write for "4.4 thisFREE RadioBo . ie Greatest Bargain Catalogue published. Chuck full of thou- sands of Radio Bargains at the lowest. prices to be found anywhere in the United States. Parts, Supplies, Sets, Parts for Sets, Latest Circuits. Send for this catalogue TO-DAY. We have friends in every City, Town and Hamlet. Our reputation is our bond. No red tape. Honest merchandise, goods shipped on ap- proval. No _risk—satisfaction or money refunded, no arguments, no money in advance. Ask this maga- zine about us! WHOLESALE RADIO SERVICE 9Church St. Dept.A NewYork City WE will pay you $4 to $6 a day for making 2 to 3 doz. pairs standard Steber socks daily; on High-Speed Family Knitter for five years. Written contract. Yarn FREE. W All or spare time. Be independent. earn guaranteed pay under this plan. Old reliable man- ufacturer. Sen for particulars without obligation. Steber Machine Co., Utica, N. Y., 602 Steber Bldg. Ranger*5 Finest bicycle built—44 styles, it y. ork at home. Thousands, colors and sizes. Factory to Rider prices. f FREE ree Tria express prepaid on 30 join 1 Days Free Trial. Cash or easy payments. if i lamps, wheels and equipment i) Ay: res at half usual prices. Send no Nu money. Write today for big. grisiog, w& A sp-ciel Factory Bicycle Prices from f.cee ‘rial plan and See page 21. =) mm ©. Wow ee et Oe OD lee ~~ et « - 41 Th Fm hUMtlCUCUTOCUTD a es ee” ol lle ee ieee we ee

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'Y, 1925 I May, 1925 Home Worksho Miniature Log Cabin Improves Appearance of Mailbox ‘MEALIZING that their common sheet- metal mailbox detracted from the appearance of the beautiful country road, the women on a farm in northeastern Iowa built a little cabin of twigs around the mailbox and fenced the supporting post w ith sticks of larger diameter nail- ed together in rustic fash- ion. To in- sure the solidity of the miniature cabin, two steel braces were run from the post to the floor of the metal box.—F. L. CLARK. How to Adapt a Small Motor for Finishing Floors A SMALL portable electric motor or a fan motor can be adapted easily for removing varnish from floors, sandpaper- ing the wood, and waxing and polishing the finished surface. _A wooden frame is made as shown. If a fan motor is used, the ends of the wooden frame are drawn together with light bolts so as to grip the body of the motor. If the motor has center trun- nions, these can be inserted in correspond- ing holes bored in the framework. A motor with a base is fastened to one arm of the frame and long bolts are used to stiffen the other arm. The shaft should “4 SANDPAPER Ml jit 6" BRISTLE BRUSH LEATHER EN FF (PADDED) 4x3 CASTER — la i PIVOTED ELECTRIC MOTOR Small motor mounted for use in finishing floors and three of the several attachments 4 : be placed so that it will be perpendicular to the floor or nearly so. Three interchangeable floor tools are used. One is a sandpaper disk, the second is a heavy bristle brush, and the third is a polisher of wood faced with | padded leather. The brush is mainly for removing paint or varnish and in con- Junction with loose, fine sand scattered | Over the floor. The method of connecting these disks with the motor shaft will vary. Only small disks should be used so as not to overload the motor, but a little practice will give excellent results from this im- Provised floor finisher.—A. L. i © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21. POPULAR SCIENCE MONTHLY 111 KEEP reception clear / Keep it clear. Keep it loud—with all the vol- ume your set should have. Keep the battery at top notch—fully charged—peppy. The Tungar charges your storage battery over- night while you sleep—and at a cost of hardly more than five cents. It’s easy! Just two clips —and a plug for the house current. Or you can make a permanent connection, and just throw aswitch. Keep your set at its best all the time —with a Tungar. The Tungar is a G-E product, developed in the great Research Laboratories of Gen- eral Electric. The New Model Tun- gar charges Radio A and B storage bat- teries, and auto bat- teries. Two ampere size (East of the Rockies) $18.00 A Tungar is also available in five am- Tungar—a registered trademark —is found only pere size, design un- 1S} on the genuine. Look for it on the name plate. changed (East of the Rockies) . $28.00 Merchandise Division 60 cycles—110 volts General Electric Company, Bridgeport, Conn. GENERAL ELECTRIC $25.00 in PRIZES ‘etn iin." ™ Make $100 Weekly-sell RADIO | ure ; Terr ; Demonstrate Once — tne — Sure Sale Ze DD IN M A CH I N E Coast to coast, lowest prices,attrac- fa t Ba ot 6) . K ET Ss I Z E tive four-tube instrument $39.50. ® Big commission to ycu. Exclusive territory to proven salesmen. Ter- ritory going fast, write today for large illustrated book No. 100. on’t fail to name your county. } NEW Does Work of $100 Machine. ie Total Visible at all Times. FREE TRIAL—Send No Money Anyonz Can Operate It. Guaranteed for Life Just write ‘‘Send me a Baby Calculator’’ and give your name and address. e will gig it immedi- e! Inc. Chicago, tll, 0 ately, all charges prepaid. n delivery pay FP Ns) fret tor fait rerund if the Baby Calculator ial for full refun e y Calculator x is not the greatest time and labor saver ycu ever used. This is thelowest priced pract Soa calculating machine made. Order today. man jo lglg BABY CALCULATOR SALES CO. COMMISSION. P.O. Box 1118, Chicago, Illinois, Dept. 2

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SRM IR pI LE LIN IS PGS POPULAR SCIENCE MONTHLY Look For This Display In Hard- ware Windows It’s your assurance that such dealers handle the genuine Sand’s Levels—the kind master craftsmen prefer. A Complete Assort- ment Of The Most Popular Sand’s Levels Step in and look them over. With such an assortment of levels side by side you can quickly choose the style best suited to your needs. Factory Built-In Permanent Accuracy “Sand’s Levels Tell the Truth.”” You can depend on their accuracy on your most particular work. Accurate workers must have accurate levels. If you are an amateur doing odd jobs about the home or shop, there is no level like the genuine Sand’s to help you make amateur work more like that of the professional. If you like good tools, you'll appreciate the advantage of a Sand’s wood or aluminum level. At Good Hardware Stores Everywhere Get One Today SANDS LEVEL , & TOOL CO. 5849 Fischer Ave., Detroit, Mich. - May, 1925 ae I HN | 1 ’ | la | eC AMATEUR carpen- ters usually find the hanging of screen doors rather diffi- cult. By following the correct methods, however, good results are certain. The outside of a screen door is that side to which the netting and screen mold are applied. Lay the door down on a pair of saw horses and cut off the stile projec- tions (“‘horns” or “‘lugs,’”’ as a carpenter would call them). Stand the screen against the opening and note the width. If there is considerable stock to be cut off, joint the lock stile straight and slip it into the dépening, with the hinge stile bearing against its jamb. Have some one trace the outline of the jamb on its stile and rip to the line, afterward smoothing it carefully. Slip it into the opening, or if it is still too wide to go against the stops, scribe the stile again and plane off the excess stock. Allow 1/16 in. clearance at both edges of the door. With the door in place against the stops, wedge up the bottom and oné side, and scribe the top rail to the head jamb, using scribers or a com- pass. Saw and plane to the line Hanging Screen Doors and down from the top 7 in., and put on the spring hinges. To mark for screw holes, hold the hinges firmly in place, which requires considerable _ pressure against the spring tension, and trace the holes with a lead-pencil. Drill small holes to start the screws in, or if the casing is of soft wood, punch them with a nail set. Screw on the hinges, and re. move the wedges. The door should show proper clearance. If working clearance is given the rear stile while the hinges are being put on, in nine cases out of ten the hinges will spread sufficiently to make the lock stile strike on shutting, necessitating their removal, plugging of the holes, and re setting. It is never a fault to have very little clearance at the hinge stile, as the hinges nearly always loosen up with use. Insufficient seasoning of the material out of which the door is built, espe- cially if the after- noon sun shines on the door, often re- sults in the stiles’ springing until the centers strike the stops, so that the door will not close. An effectual rem- edy is to put on an ordinary butt hinge at the center, “which will keep the stile straight. The stiles can be and test in posi- tion. Then fit the bottom of the door, allowing as little clearance above the floor or linoleum as possible, as otherwise flies will crawl under. Many back doors close against the ends of the porch flooring as a bottom stop, thus effectually barring flies. A front-door screen, however, usually closes with the bottom rail against the slope of the sill, and must be beveled on the bottom to fit. In case the door is too long to go into the opening for scribing the stile, try the jambs for straightness with a straight- edge, and test the head jamb for square- ness with the sides. Cut the door to a tight length, making allowances for varia- tions in squareness in the jamb, and cutting off excess stock from the bottom rail. Then proceed as above. Having secured a good fit, with the edges of the door beveled sufficiently to clear in opening and shutting, wedge the door tightly against the hinge jamb by means of shingle points or other broad wedges, leaving proper clearance at top and bottom. Now measure up from the bottom 11 in. Attaching the lower spring hinge. Note the extra butt hinge at the center of the stile; it aids in keeping the screen door from warping moistened with water and allowed to dry while wedged to a curve in the opposite direction; but this is an expedient rarely used. Put the handle about 3 ft. from the floor, and the hook eye opposite. The hook never should be attached to the door, for inevitably it flips around when the door swings shut, preventing it from closing properly and marring the casing and jamb. To REPAIR the worn tire of a carpet sweeper, remove the old tires completely and replace them with new rubber tires made from a 5%-in. wide section cut from the union or section oF 30°% 32" thickest part of a INNER-TUBE TIRE Ford inner tube a 30 by 344 in. Ap- ply a thin coat of glue or shellac to the wheels to in- sure the rubber’s sticking fast.—J. A. CAPELL. Repairing a Carpet Sweeper © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21. ae ae eae aa a

Page 93

Y, 1925

ut on Screw place, assure e the small if the vith a id re- Show e rear on, in S will K stile their nd re- e very as the h use. aterial *h the » espe- after- ines on ten re- stiles’ til the ke the at the t close. 1 rem- E on an butt center, keep Taight. can be 1 with lowed rhile 1 curve s is an ym the . The to the d when it from - casing ne worn carpet ove the ipletely er tires on cut 3%" = a“

' May, 1925

Window Ventilator

top, no matter how draperies. A quickly ad- justed ventilator | __

casings I ran a pair rods costing 10 cents clamps over the window frame. The result is that my ventilator is pretty as

well as practical. the bottom or top desired.— W. F. Z.

To Avo a draft in my bedroom where one of the windows is kept open at the cold and windy the weather is, 1 made a ventilator as shown from %4 yd. cretonne left from window I stitched a hem 14 in. deep at the top and bottom of the piece. Through these

=

of spiral spring sash each and hooked the It can be adjusted at of the window, as

Washers for Faucets

the

To REPAIR any com- pression faucet so that the washers will last longer than usual, replace the old rubber or leather washer with a washer cut from %- in. gasket rubber and faced with thin leather. The facing may be cut from the upper of an old shoe. The rubber furnishes the necessary resiliency and leather resists long wear.—ToM J. PARADY.

Repairing Door Panel A CRACKED door panel, especially one in an outside door, is difficult to repair. Putty and even calk- ing often will fall out. If the crack is covered with a nar- row strip. of adhe- sive tape, however, the repair will be

satisfactory. The surface first should be cleaned thoroughly and the adhesive strip well heated. After it is covered with a heavy coat of shellac, the strip may be painted —WILLIAM C. SERRELL.

POPULAR SCIENCE MONTHLY 113 Radio at its Now Within Your Reach

R ax. \ * _ Tf z iN | ate! ti ee | = 7) Oj ha 2 ; . oe | i 2 ‘ D ; re 4 i 7 assay? fe 6 GaN LS Semi-Finished — Factory-Mounted is OU buy this set with the ALL-AMERICAN parts 4 properly mounted on the paneland baseboard. 4 Without knowledgeof blueprints, circuitsornames > of radio parts, you can wire up an ALL-AMAX 4 Senior in one delightful evening and know that it is right. This completely mounted highly efficient three-tube set costs you no more than you would pay for a kit of parts. Price, *42. Ten cents will bring you the new Radio Key Book, and upon request we will include, free, a complete wiring blueprint of either ALL-AMAX SENIOR or ALL-AMAX JUNIOR, ALL-AMERICAN RADIO CORP. E. N. Rauland, President 2668 Coyne Street, Chicago

Na Ad AA wn te eA Bn, w* a WADA PAS PASS WIN AN ALL-AMAX RECEIVER at your favorite radio store. Ask them about the great ALL-AMERICAN Slo- gan Contest. Youcan win a set by sub- mitting a SLOGAN. Everybody can enter. It costs nothing.

ALL-AMAX JUNIOR © Aone-tube set that brings f in the local stations on the & loud speaker, or tunes them out and gets real distance. g All parts are mounted on panel and baseboard, and clear photographic wir- ”, @ ing directions arein- ;, Cluded. Price. . 832 p LN LA i »~ ws op a i a ALL-AMERIC. ee . “a

© This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21.

tna tp tnt nt ee ct eee Ro

ee nn a nn een a

Page 94

The handiest tool on the YET Saves ~mone ~muscle -minutes fe a SIMONDS FARM AND HOME SAW Repairs to be made—odd jobs to be done—that is the call of Spring. So Spring calls for Simonds Home and Farm Saw with teeth that bite their way smoothly and easily through the toughest board. In the Home and Farm Saw, Simonds has produced a cutting tool worthy of the name. Confin- ing manufacture to one size— 24 inches long—Simonds is able to offer the Home and Farm Saw at $2.00—a price that is actually less than you thought you would haveto pay for anor- dinary saw. Ask your hardware dealer about this saw today. SIMONDS SAW & STEEL COMPANY Fitchburg, Mass. “The Saw Makers” Established 1832 Branch Stores and Service Shops in Principal Cities SIMONDS Pronounced Si-MONDS } SAWS FILES KNIVES STEEL POPULAR SCIENCE MONTHLY (Continued from page 86) for Grinding Thread Tools By Charles Kugler Fixture ASILY as it may be made, this fixture makes pos- sible the speedy grinding of U.S.S. or 60-deg. thread tools and Acme or 29-deg. tools. Either type of tool can be ground at one setting. For example, to grind a_ 60-deg. tool, the sides A and B are placed on the magnetic chuck of a _ tool- grinder and the two sides of the tool: ground to 60 deg. Then the fixture is placed with the side C on the chuck and the 15-deg. front angle is ground. After that the side D is placed down and the top of tool is ground. Side a \\ xT ek) NY \ \ \ ‘ ] With this fixture and a magnecic chuck, both standard and Acme thread tools may be ground CNT Ua aN / ij } ti : W))))) PLate ; \ ti Way \TOOL ne Cis used only when a U.S.S. tool is de sired to make a flat on the thread. For a V_ thread this is not neces. sary. For an Acme 2 9-deg, thread the sides D, E, F are used, The central screw makes the tool fast in the slot by exerting pressure on a in. rod. With this fix. ture a precision thread tool may be ground in a few minutes, yet the work involved in making it is not great; a machinist can make one in four hours. The writer made | the one illustrated of machine steel and | pack-hardened it. i} Ja SQUARE Wristpin Bushing Tool for Rapid Work Useful both for insertion and removal By Harvey Mead "THIS tool for inserting and removing wristpin bushings has given very good service and is easy to make. The dimensions can be made to suit the work. The inside diameter of the collar must be just a little larger than the outside diameter of the bushing. The knurled nut has an outside diameter slightly smaller than the outside diameter of the bushing. To insert a bushing, place it over the screw, locate the toothed or slotted nut between the bosses in the piston with the milled slots against the boss, and with a bar as a lever, turn up the screw until the bushing is in place. INSERTING REMOVING How the wristpin bushing tool is made and_ used. The photograph at the left shows the insertion of a bushing; that above, its removal 1S] This seal on a radio or tool advertisement signifies the approval of the iNSTITUTE OF STANDARDS. See page 21. To remove a bushing, place the — open end last, over the screw. Pass the | screw through the bushing and start it | into the knurled nut. Let the open end | of the collar bear against the piston and | tighten the screw. | | Lathe Chuck Supplements Vise for Bench Operations Two unusual uses for lathe chucks at the workbench OR hand work at the bench, a lathe chuck may be used to hold such an irregular casting as that shown in the larger of the two chucks above. The chuck is bolted to the bench and jaws adapted to grip the part to be held are provided from soft blanks. The smaller chuck, which is held in an ordinary bench vise, is gripping a finished automatic-die for disassembling and re assembling. In this manner the product is held securely without marring the fin ished surfaces, as would be done by at- tempting to hold the cylindrical member : between parallel jaws.— O. S. MARSHALL. ss 4 aA Th © as mm — pm «&

Page 95

ols ly when ol is de- hake a thread, thread neces- ‘or an -deg, > sides e used, ntral es the in the Xerting 1a lk 1is fix. recision may be a few ret the Ived in list can ar made beel and

e collar, ass the | start it | pen end ton and | | s Vise Ss

a lathe such an . in the re. The nd jaws held are 21d in an finished and re- product - the fin- e by at- member 4 RSHALL. |

—_—_$<$—$__ nt { . | |

POPULAR SCIENCE MONTHLY

Better Shop Methods Old Bill Talks to the New Machine-Shop Apprentice OMMY JONES, who had been in the shop only a week, was like a colt fresh from pasture. Old Bill had been keeping a watchful eyeonhim. As Tommy was going out on Saturday, Old Bill told him to wait a while. After every one had gone they went into the office, Tommy a bit sus- picious. Old Bill soon put him at ease. “Tommy,” he said, ‘‘it has* been my custom for years to take boys into the shop on trial. I have noticed that you have done unusually much playing. The shop is no place to fool. It is dangerous and you easily may be injured for life. “Get yourself overalls tonight and don’t come Monday morning without them. Never wear any loose fitting

clothes or long sleeves around a machine- shop unless they are buttoned up tightly about the wrists; roll up your sleeves above the elbows or, better, have them cut off short. “Never place your hand near a revolv- ing cutter to brush away chips, but use a soft wood stick or a brush, or stop the machine. Always make use of any safety devices provided for the machines, especially grindstones and emery wheels. Never remove the guards. “The tools, machines and - materials that you will use are expensive, many of them very expensive. If there is any- thing you do not understand about your work or the machines, you must always ask some one who does. If you had to buy these machines and tools yourself, you would have a great deal of regard for them. Oil your machine each morning before starting up. Never place files, heavy wrenches, and tools or rough cast- ings on the ways of alathe. Never usea monkey-wrench in place of a toolpost wrench or machine-vise handle; this practice ruins the screw in a short time. “Tf you have to shift gears on a ma- chine or change the stroke of a planer, al- ways stop the machine. Get the proper speed and feed for every operation. Ma- chines do not get tired, and if you work with your head you can make the ma- chines do the physical work. “Learn the value of little things. Never slight a job, no matter how unim- portant it may seem to you. Do every- thing as well as you know how. Pay no attention to what the other fellow is

doing, but concentrate on your own job.” amit Better be sure it’s “Good old ‘B.V.D.” { “B.V. dD” Union Suit (Patented Features) Men’s $1.50 the suit Youths’ 85c “B.V. D. Shirtsand Drawers 85c the garment Men's “B.V. D.” Underwear in Fancy Materials at Various Prices The B.V. D. Company, Inc. New York Sole Makers of ““B.V. D.” Underwear

EMEMBER that no underwear with- out the red woven “B.V.D.” label is “B.V. D.” Assure yourself of that Famous Fit, Long Wear, and Cool Comfort which have kept “B.V.D” the world’s most popular men’s underdress, Get the underwear you ask for! Insist upon this red woven label: 853, ** Next to Myself I Like ‘B.V. D.’ Best”? ? MADE FOR THE

rode Mark hog USPes fond Foreign Gamtriad) ©1928 The B.V.D, Co. Ine

A new or hub cap for. less than 1¢ Stop that leak in a jiffy with SMOOTH-ON No. 1 Makes no difference whether it’s water leaking from the hose connections or radi- ator, oil or gasoline from the supply lines, or gas from a loose exhaust pipe, Smooth-On p No. 1 will produce perfect tightness in a few minutes. Use it also for keeping grease cups, lock nuts and hub caps from dropping off, and for perfect sealing of cracks in bursted water jackets, Get Smooth-On No. 1 in 7 oz. or 1 or 5-lb. can from any supply house. c<_ By SMOOTH-ON MFC. CO. SuooTtO4 Nesey Cats: N.J. Do it with SMOOTHON

Write for

The Caille Liberty Twin The Motor No Other Dares To Follow The Motor forWeeds —goes through them like an eel. Shallows can’t interfere—drives your boat where’er "twill float. Hidden rocks can’t damage it—just glides over them. Equally efficient in deep water. The IBERTY gE Oe WIN is built on the direct drive principle, has twin cylinders —no vibration, light weight. Bosch Magneto, Zenith Carburetor and motorcycle control. Easy to start. Thousands in use. Send for our free book on rowboat motors. b THE CAILLE PERFECTION MOTOR COMPANY 6340 2nd Boulevard Ap, Detroit, Mich. The Motor with Direct Drive Pi

Page 96

116 Bargains in CHEMISTRY Ss | } LL of the Chemistry, Pharmacy and other books listed below were written and prepared by well-known authorities in this field and are used by leading colleges and technical schools throughout the coun- try. They contain much material that is not available in any other form—anywhere. They are complete, authoritative, profusely illustrated, yet surprisingly low in price. Studied faithfully, there is no doubt that they will help you to gain a greater mastery of your work and secure a better position and a larger salary. SEND NO MONEY Just check the names of the books you want on the coupon below and we will send them to you on approval by return mail. _FREE EXAMINATION COUPON. | International Correspondence Schools Box 7653-D, Scranton, Penna. Please send me the books I have checked below. I shall either return them in five days or send you the money. Pharmacy and Materia Medica, 326 iy pages ---------+------ 3.00 0 Qualitative and Quantitative Analysis pages ---------+------ .00 (1 Organic Chemistry, 387 pages --- - 3.00 Ci Inorganic Chemistry, 605 pages -- - 4.50 [] Chemist’s Handbook, 348 pages --- 1.00 [] Chemistry of Iron and Steel, 347 pages --------------- 3.00 (J Chemistry of the Packing House In- dustries, 313 pages -------- W5 © Industrial Chemistry Manufacture of Paper and Sugar, 375 pages - - -- 3.50 O Chemistry of the Manufacture of Cot- tonseed Oil, Petroleum, etc., 415 pages 3.50 Good English for Everyone, 442 pages 3. OTHER BOOKS AT $1.00 Oo || © Pharmacist’s Handbook. 324 pages - - $1.00 | (1 Machine Shop Handbook, 335 pages - 1.00 (J Mechanic’s Handbook, 330 pages - - - 1.00 I] © Electricity Handbook, 414 pages --- 1.00 0 Building Trades Handbook, 409 pages 1.00 | Cj Advertising Handbook, 445 pages - - 1.00 j (0 Radio Handbook, 514 pages ----- 1.00 Oe ee er oe MRIS So. Diu codoanbseguehceennetese nar ys SE NEW CAMERA Takes and Finishes Pictures Inside The Camera in One Minute The marvelous new Crown Minute Camera takes and finishes pictures inside the camera in one minute. No films—no plates—no dark rooms. Load cards in day- light. Pictures 24x34 inches. Size of camera 534x534x7 inches. Universal lens takes pictures at all distances. Simple instructions sent with each camera; no experience necessary. Send no money. We will send the camera on 10 days’ free trial. If satisfied you simply send 50 cents weekly until our special introductory price of $10 is paid. Crown Minute Camera Co., Dept. 507, Norwalk, Conn. POPULAR SCIENCE MONTHLY. | Better Shop Methods Toolmaker’s Long Button Is Useful for Close Work O LONG accustomed have machinists been to the standard design of tool- maker’s buttons that they will be quick to note the outstanding feature of the new set illustrated below, which was developed recently by a manufacturer of precision New set of buttons for toolmakers tools. of the buttons in the set is made a little longer than the others. The advantage of the long button lies in The difference is simply that one locating holes that are close together. It is possible to use an indicator to center the long button even when a short button is placed close to it. Adjustable Fixture Holds Rod Ends for Rapid Drilling T IS often a laborious task to center- punch the ends of rods that are to be drilled. Another difficulty is to place the rod ends in a vise so that they may be gee | straight. The same trouble arises in milling the end of a rod. To overcome these difficulties and hold any rod in a vertical position, the device illustrated was made. A hardened die with holes of the sizes most in use, can be The fixture opened to show the V-shaped movable jaw, and howit is used to hold a 34-in. square iron rod for drilling in the end set so that the desired guide hole is exactly over the center of the rod. A stud bolt with wingnut allows the faceplate. Within their capacity the jaws will hold any shape iron, square, round, hexagon, oval or flat. For milling the ends of rods, all that is necessary is to take off the guide die on top.—O. W. MIELENz. fixture to be fastened to almost any drill prepaid parcel suffer. Deaf Can Hear Says Science New Invention Aids Thousand, Here’s good news for all who from deafness. Corporation announces the perfection of remarkable device which has enabled thoy. sands of deaf persons to hear’ as well a ever, The makers of this wonderful devigg say it is too much to expect you to belieye this so they are going to give you a chang to try is at home, They offer to send it by They do not send it C. O. D.—they require no deposit—there is no obligation. _ They send it entirely at their own expense and risk, _They are making this extraordinary Offer well knowing that the magic of this little instrumient will so amaze and delight the user that the of its being returned are very slight. have already accepted this offer and report most gratifying results. that you should endure the mental and physica strain which comes from a constant effort Now you can mingle with your friends without that feeling of sensitiveness from which all deaf Persons Now you can take your place in the and business world to which your talents entitle you and from which your affliction has, in a mea. sure, excluded you. address to The Dictograph Products Dept. 1303-D, 220 West 42nd Street, New York, for descriptive literature and request blank, The Dictograph Products post on a ten-day free trial, Thousands There’s no longer any neaj to hear, Just send your name and Corporation, Arnold Johnson Director, Arnold Johnson and His Orchestra. Hear his complete set of all Buescher strumentson your phono- ph in inswick cords. Everything in Socially and has many earn money. Six Days’ payments arranged, FREE Saxophone Book models and gives first lesson chart; also pictures of famous tes aeapere and orchestras. Just send your name fora ention any other instrument in which you tay beintareall BUESCHER BAND INSTRUMENT CO. 702 BUESCHER BL Easy to Play Easy to Pay True-Tone Saxophone ‘7 Easiest of all instruments to play and one of the most beat tiful. Three first lessons sent free give you a quick, easy start—in a few weeks you can be playing popular tunes, No teacher necessary. You can tainments, church, ie A saxophone player is (108) Showsall Buesclier Bamd and Orchestra Instruments OcK e HART, INDIANA aoc; Dept. New cade Old Turn your OLD Gillette into the NEW model with a NUWAY BLADE SADDLE. Save money and get the smoothest shave you ever had. Silver plated 25c. Gold plated “The NUWAY is the SMOOTH way’ For old style Gillettes only. Money back if not delighted. B, 1616 Woolworth Bldg., New York Only amonth forafew months —easy toownthefamous standard WITTE En- _ 3 ne. Uses Kerosene, asoline, Distillate or Gas. Equipped with cel WICO Magneto. Simplest and cheapest to erate. New device makes starting eas: pons . Si 2to26 FREE BIG NEW Bole cirect trom factory to roy o8 ENGINE BOOK engine book—sent absolutely Free. WITTE ENGINE WORKS 2228 Witte Building, - = « 2228 Empire Building, 2228 Witte Building, - SAN FRANCISCO, CALIF. IS) This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 22. $569 SSS — brated Troubleprest NINETY DAYS’ FREE Write today for my new illu No obligation toyos KANSAS CITY, MO - © PITTSBURGH, PA.

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POPULAR SCIENCE MONTHLY . ousands ; | Who suffer ; 1 Prodvets ; ection of a so ADE MARKS-COPYRIGHT ae TR HTs Thul devigg “bal PROTECT YOUR INVENTION send it by ANY NEW article, machine, design or improvement thereof, or any com- ’ free tral, bination of parts or improvements in any known article which increases its 6 require efficiency or usefulness, may be patented, if it involves invention. ae If You Have Any N Id ick f You Have Any New Ideas 4 € chances which you feel are useful, practical and novel, take prompt action to protect your T any neal rights. If you have invented any new machine or new combination of parts or pe! — improvement, or any new design or process, SEND DRAWING, MODEL OR without tht DESCRIPTION of it for information as to procedure to secure protection. in the social ents entitle is, in a meq r name ani Corporation, , New York, lank, DRAFTING and SPECIFICATION ROOM of CLARENCE A. O’BRIEN, Registered Patent Lawyer, Washington, D. C. All communications are held in strict confidence. My personal, careful and thorough attention is given to each case. I offer you efficient, reliable and prompt service—based upon practical experience. Highest references. NO CHARGE FOR ABOVE INFORMATION Write today for free books, ‘‘How to Obtain a Patent’’ and ‘‘Inven- / ™ ¥ oe tion and Industry” and blank form ‘‘Record of Invention.”’ Se T, INDIANA These books will give you valuable information, and they may save you much time and effort. Send for them now. My practice is devoted exclusively to r Old United States and Foreign Patents and Trade Marks. Write me freely, frankly 7pege Books Free and with full confidence; it is very probable that I can help you. Use the Coupon attached, and immediately upon its receipt I shall send you the form Record of Invention to be returned to me with drawing, description or model of your idea; promptly upon re- vou ceiving your idea I shall write you as to procedure and costs. ia CLARENCE A. O’BRIEN old plated t delighted. a ig., New York REGISTERED PATENT LAWYER Member of Bar of Court of Appeals, District of Columbia, United States Court of Claims; Supreme Court of United States, Supreme Court District of Columbia. ---------------- FREE COUPON ---------------- CLARENCE A. O’BRIEN, REGISTERED PATENT LAWYER 8892 Security Savings and Commercial Bank Building Directly across Street from U. S. Patent Office, Washington, D. C. Please send me your free books, ‘‘How to Obtain a Patent” and ‘“‘Invention and Industry” and blank form, ‘*Record of Invention,’’ without any obligation on my part. the NEW Y BLADE IMPORTANT—WRITE OR PRINT NAME CLEARLY. ISCO, CALIF. 2. © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21.

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POPULAR SCIENCE MONTHLY PATENTS | TRADE-MARKS FOREIGN PATENTS MUNN @ CO. PATENT ATTORNEYS Associated since 1846 with the Scientific American 683 WOOLWORTH BUILDING 522 SCIENTIFIC AMERICAN BLDG. New York City ; Washington, D. C. 411 TOWER BUILDING 364 HOBART BUILDING Chicago, Ill. San Francisco, Cal, 219 VAN NUYS BUILDING Los Angeles, Cal. ete Books and Information on Patents and Trade Marks By Request. Associates in All Foreign Countries, DESIGNS Apex Super This highly oa er 4 radio frequent” ain tunce. he most advan isan ceiver qructiOne oy crite ets eV the seasone: At the Amazingly Low Price of $ THE Bossert RADIO os i 5 Bungalow costs only $615, delivered to YOU complete. Has living room, 12x12 ft.; two bedrooms, 9x9 ft.; kitchen, 6x9 ft., and bath. Rooms per- fectly arranged, light and airy. Here is the most remarkable vdlue ever offered in portable bungalows. The small cost is paid back to you the first summer in health and pleasure. You are guaran- teed satisfaction by the largest lumber company in the East. Simply choose your vacation spot, near the beach, up in the mountains or in some country paradise of your own discovery, then put up the RADIO Bungalow! No carpenters or skilled mechanics required. Two men can erect it within a day and a half. It is sturdily constructed and will last for years. The RADIO Bungalow is fully portable. It can be taken down readily, transported and put up again without trouble, so that it can always be your summer home no matter where your fancy takes you. Don’t delay! Write NOW for order form and folder completely describing the RADIO Bun- galow. LOUIS BOSSERT & SONS, Inc. Largest Lumber Plant in the East 1310 Grand Street, (House Dept.) BROOKLYN, N. Y. | lathe,” Old Bill resumed, “hold this jeter Shop Methoc. Old Bill Works on Teeth (Continued from page 84) teeth of 214-in. pitch and weighing about 350 Ibs. in the rough to another with in pitch, which could be held in one hand yet that was the variety of work that Old Bill had, and the variety of work that con- fronts many a general machinist. “How soon can you make it for me?” the customer asked. : “T can get it out right away,” Old Bill said, and looked at his watch. “You can have it late this afternoon if you want it.” The pinion was of cast iron and had several of its teeth broken out. Old Bil] decided that he would make his new one of steel, for he knew that it could be done in about the same time as the cast one and would be much stronger. The remaining teeth were so badly worn that it was not possible to tell how large the outside had been in the beginning, go methods somewhat similar to those used for the big pinion had to be used for the smaller one. This was a little bit simpler than the larger one, for the smaller one was made with teeth proportioned by the diametral pitch. sy HERE is a difference,” Old Bill explained to the machinist who was to make the gear. ‘‘Somebody decided that it was too much trouble to figure cir- cumferences and divide, and then look at tables, so they made a system of gearing that hardly takes any figuring. “Tf you know the number of teeth, and the diametral pitch, divide the nun. ber of teeth by the pitch and you will have the pitch diameter. For the outside diame- ter, add two to the number of teeth and divide as before, which will give you the outside diameter. This pinion has 20 teeth, and it is 8 pitch. Twenty-two divided by 8 gives 234-in., which is the size that you are to turn the blank. ‘Pick the eight-pitch gear-cutter in the |: milling machine cabinet marked ‘17 to 20 teeth.’ This is numbered 6. The depth to cut is marked on the side of the cutter and is .270. Be sure that you have the cutter in the center of the blank before you start cutting, then just barely touch the blank with the cutter. Move the table away and raise it just .270 in. and start to work.” OLD BILL passed through the shop, looking around to see if any one was in difficulty. He observed that the large pinion blank was getting along well. He was going to have a man stay to work on it that night, so he returned to his office to get the paper templet. “T have made this paper gear,” said Old Bill; adding with a smile, “It will not be as easy for you to make a steel one as it was for me to make the paper one, but the teeth should be the same shape!” The machinist looked at the templet, and measured the diameter with his rule. “When you get the blank out of the templet tight on one end and scribe the outline of the teeth on the steel. Better take a prick punch and mark the teeth (Continued on page 120) —_——e © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21.

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y about h in. lat con- r me?” id Bill rou can ant it,” nd had Jd Bill LeW One be done St one, ly worn w large ning, so se used for the simpler ller one 1 by the ld Bill who was decided zure cir- look at gearing eth, and in. der of lave the » diame- eth and you the has 20 nty-two h is the nk. er in the |: 17 to 20 1e depth ie cutter 1ave the k before ly touch ove the in. and he shop, one was the large ell. He work on his office ir,” said > will not el one as one, but ? ribe the Better he teeth —_—$—$———t May, 1925 —————————————— ail a eeeiieaiiiaaiall > fae oo ee ne mee New York Office Suite 1007 Woolworth Bldg. Philadelphia, Pa., Office Suite 714-715 Liberty Bldg. | Washington, D. C., Office Victor Bldg. tS) This seal on a radio or tool advertisement signifi POPULAR SCIENCE MONTHLY TRADE-MARKS COPYRIGHTS OUR OFFER: Your first step ? Before disclosing an invention the inventor should write for our blank form “RECORD OF INVENTION.” This should be signed, witnessed and returned to us together with model or sketch and description of the inven- tion for INSPECTION and INSTRUCTIONS. NO CHARGE FOR THE ABOVE INFORMATION Our Four Books Mailed Free to Inventors Our Illustrated Guide Book HOW TO OBTAIN A PATENT Chicago, Ill., Office Suite 1114 Tacoma Bldg. Full instructions regarding U. S. Patents. Our Methods, Terms, and 100 Mechanical Movements illustrated and described. OUR TRADE MARK BOOK Protection. Information regarding Trade Marks and unfair competition in trade. OUR FOREIGN BOOK We have Direct Agencies in Foreign Countries, and. secure Foreign Patents in shortest time and at lowest cost. Progress of Invention Description of World’s Most Pressing Problems by Leading Scientists and Inventors ALL COMMUNICATIONS AND DATA STRICTLY CONFIDENTIAL Shows value and necessity of Trade Mark ? INTERFERENCE AND INFRINGEMENT SUITS PROSECUTED Pittsburgh, Pa., Office Suite 514, Empire Bldg. Private Office, Victor J. Evans, with View of Patent Office Through Window Ip rata orieschelgeient estes erent anne a ighest References © Prompt Attention Reasonable Terms VICTOR J. EVANS & CO., Patent Attorneys | San Francisco, Cal., Office Suite 1010 Hobart Bldg. | Main Offices: 760-9th Street, N. W., Washington, D, C, i Gentlemen: Please send me FREE OF CHARGE your FREE books as described above. / 1 | COUPON |Name............0:-:00cccceetsereeseeeeeneseeceeeteene | PiGdeeee eines ie oS CH era wie een «) nieteeete es the approval of the INSTITUTE OF STANDARDS. See page 21. SS nn

Page 100

120 POPULAR SCIENCE MONTHLY : without _, tra Cost Ole Evinrude’s LATEST TWIN OUTBOARD MOTOR. _Ex cs

Here is the year’s un- matched value in rowboat _— motors. The new 3 H. P. Elto gives you a full extra horsepower without extra - , cost. Think of the extra speed, the rs — i a greater power, the surer safety in ° . : rough waters, and the constant satisfaction these things afford. STARS WITH A TOUCH ~ Just step into your boat and go. No coaxing and priming. Nospinning. Norope to pull. Give the starting button a quarter > swing, and as easily as you step on the starter of your auto, Elto jumpsinto action. The Atwater- Kent Uni-Sparker Ignition with Columbia Waterproof Hot Shot Batteries throws a spark of such intensity and fire, your Elto simply must “Start witha Touch,” even oncold days. ONLY MOTOR WITH THE PROPELLO-PUMP For Elto owners, all pump troubles are forever ended. There is nota single moving pump part—no valves to stick—no parts to wear. daa The Propello-Pump is operated by siphon, suction and the driving force of the propeller blades. Screened openings in the rudder constantly feed an abundance of cool water to the Motor. It never overheats. As long as the engine is run- ning, the Propello-Pump is working. WRITE FOR FREE CATALOG Before you select any Motor take time to compare and see for yourself the extra value Ole Evinrude offers you in Elto—the Fastest Light Twin. ELTO OUTBOARD MOTOR COMPANY OLE EVINRUDE, President Dept. W. Manufacturers’ Home Bldg. MILWAUKEE, WISCONSIN arts with a Touch’ Designed & Built by Ole Evinrude i

“DON'T SHOUT” “T hear you. I can hear now as wellas anybody. ‘HOW?’ With THE MORLEY PHONE. I've a pair in my ears now, but they are invisible. I would not know I hadthem in, myself, only that I hear all right.’ The Morley Phone for the DEAF 8 to the ears what glasses are to the eyes. Invisible, comfortable. weight- less and harmless. Anyone can adjust it. Over one hundred thou- sand sold. Write for booklet and testimonials. THE MORLEY CO., Dept. 797, 10S. 18th Street, Philadelphia FFL ris © DIAMONDS WATCHES

You Save 50% World 6-Volt Storage Batteries are famous for their guaranteed | Approvedand quality and service. “Backed by | _ Listed as DIAMONDS WATCHES cesstu. a 2 and Thousands of Satisfied Users. — by ts CASH°RCREDIT cirts You save 60% and get a Pro we \ 2 ‘Wear, Guaventes Bond including Radio m ting News Labor- World Battery owners ‘‘tell } atories, Popular their friends.” That’s our best | Science Insti- proof of performance. Send your | tute of Stand- order in today. ards, Popular RADIO BATTERIES Radio Labor- 6-Volt, 100-Amperes . . . . $12.25 atories, Radio

6-Volt, 120-Amperes . . . 6-Volt, 140-Amperes | °°: ig.o9 | Broadcast Lab- AUTO BATTERIES <= = The Diamonds in NS t ax. Ine. A e Diamon » €-Vott, as cece $12.25 a gf these Rings are brilliant, Blue White,high-\ wor Pree sss de Quality Gems. The mountings are ° ce ee ’ Solid Rubber Solid 18-k ite Gold. Cased in handsome Ring box. SEND NO MONEY Container ToBe Successful, Look Successtul . 5. ‘Wear Send for Catalog Over 2000 illustrations of Diamond-set'Jewelry, Pearls, Watches, Wrist Watches, Mesh Bags, Silverware, etc. Sent prepaid for your Free Examination. Catalog explains Just state battery wanted and we will ship day order is received, Now Standard by Express C. O. D., subject to | $gu! menton all your examination on arrival. orld Storage Extra Offer: 5% discount for | Batteries. bd

cash in full with order. Buy now | More leakage or Soiichocti, e invite comparison of quality and prices. d get breakage of jars atisfaction Guaran- 50% cnt | nega battery at | or rotting of box. teed or Money WHITE GOLD WORLD BATTERY COMPANY yen, nt crders 1219S. Wabash Ave., Dept. 7 Chicago, ill, delivered on first

price; balance in é 2 2 equal amounts, No, 49— 18k $100 weekly, semi- Solid White Gold, 17 Jewels, $35 ~~ 8 monthtfy or monthly, i , Stecnctanvanionne. Delivered on payment of $3.50, then a week LOFTIS BROS. & CO. National Jewelers

New Traveling Carriage Designeg for Automatic Arc Welding

Welding a straight seam automatically

T° SPEED up the production of straight welded seams, the traveling carriage illustrated was developed re cently. The unit consists of an auto matic welding head and the necessary controlling mechanism, a motor, and a wire reel support mounted on a frame- work that rolls along a track.

Old Bill Works on Teeth (Continued from page 118) well. Then get the gear in the big shaper and plane the teeth to shape. I will have a tool made for you to use in finishing the sides of the teeth. But first use a square- nose tool about 3 in. wide to get out most of the metal.” “T ought to rough out all of the teeth before I try to finish any of them,” the machinist commented. “Yes, that’s the idea,” Old Bill agreed. **Set up the blank with one of the spaces vertical and go down with the square tool. You might work out almost to the line with a round-nosed tool after you have got to the bottom with the square one. When this is done on all of the teeth, you proper shape.” Old Bill went by the milling machine to see how the little pinion was progressing. It was almost done. Both jobs, big and little, would be ready on time and, he knew, a credit to the dependability of his shop.

Spring Cover for Spindle End ‘THe spindle ends of emery wheels in tool- rooms and shops very seldom are guarded. An in- expensive guard can be made as eae’ illustrated from a piece of tubing tapped on the inside of one end and plugged. Three or four flat springs are riveted inside, as shown, to hold the tube in place on the spindle.

WHILE it is common practice to put a board on the flanges in the bed of a lathe to hold tools, it is better to use a piece of heavy wire netting cut to fit in snugly.

Dept. N-871 108 North State Street, Chicago, Illinois Stores in Leadi ng Cities

This lets much of the dust and chips fall

can use the formed tool to give them the |

| through.

r{S] This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21.

ate we ow a ft mm ow os ct -—_— ff wet eee PO Ea ee ar ae

Page 101

May, 1995

‘ion of aveling ed re- | auto- cessary and a frame- th shaper Il have ing the ;quare- et out > teeth 1,” the agreed. spaces re tool. he line 1 have ‘e one. h, you 2m the hine to essing. ig and nd, he of his

of one ir flat wn, to dle. put a 1 lathe 1 piece nugly. ps fall

——————

May, 1925

== Better Shop Methods Precision Boring-Tool Will Assure Accurate Work ° By H. L. Wheeler Machine-Shop Foreman = boring-head detailed below is for poring holes in drill jigs and dies and similar work where extreme accuracy is required. There are three main parts, the base, the slide (2), and the shank (1). The base and slide are dovetailed and provided with a gib (7) 1 in. thick, which is adjusted with three headless setscrews (4) on the side of the base. The shank is fastened to the base with four fillister-head screws from the under side. The heads of these screws are sunk in counterbored holes flush with the back. A %-in. hole is provided for the boring- tool, but this dimension may be changed MORSE BRASS, NUT@®) TAPER ’ -. o

He

Details of a boring-head that will bore holes from 54 to 6 in. with extreme accuracy to suit the user. One or two setscrews hold the tool in place. The feed screw (3) is made in one piece and has a graduated dial to read in thou- sandths of an inch. The screw has 20 threads to an inch, so that one revolution of the screw moves the tool .050 in. The brass nut (8) is fastened to the slide with a fillister-head screw. The nut fits snugly into the groove in the under side of the slide and cannot work out of place. The thrust plate (9)-is fastened with flat-head machine screws. The material used is machine steel. A boring-head of the size shown will bore holesfrom about 5¢ in. to 6 in. in diameter. Various styles and sizes of straight-shank boring-tools may be made up.

Surface Plate of Glass A PIECE of glass from a broken wind- shield or mirror makes a useful sur- face plate for the small shop or the home workshop. As precision surface plates of guaranteed accuracy are quite expensive, there are many mechanics who do not wish to purchase one. While the glass is not absolutely perfect, it will be found

quite accurate enough for ordinary jobs.

POPULAR SCIENCE MONTHLY Now One of Paid Professions! *90 to 150 Every Week! , — BE A “WHITE-COLLAR” MAN— Earn $90 to $150 a Week—CLEAN Money! What’s the use of doing dirty, greasy, hard work, when you can NOW make TWICE as much money in a manly pro- fession that is CLEAN, profitable and full of opportunities? MOLER Graduates Are Always Busy! MOLER trained Men are — given the preference, for they alone possess the valuable, thorough MOLER training in the application scientific includ- ing the Electric hair cutter, the mechanical massage, and the latest vogues in ladies’ hair bobbing. MOLER also ou soon step out as your gives special trainin: in Easy to Learn— Quick to Earn! That’s BARBERING for YOU! And the best part of it all is this—scientific of all the Jatest barbering, as taught the Barbering methods, modern MOLER way, makes YOU a Master Barber in a short course of intensive training, at small expense! own Boss, if you wish, in your own Shop, which we will gladly help you equip. BARBERING ladies’ marcelling and an Bobbing easy practical course in the treatment of skin diseases. MOLER SYSTEM OF COLLEGES 30 Branches in United States and Canada the Highest

_ i aN) Juuliter Earn While Learning! *‘Where there’s a Will there’s a Way” to earn BIG pay! Write to the nearest MOLER Calvan there is one: near you, and learn how you can earn while you learn the barber trade. Ask for the new FREE MOLER Barbering Booklet C. Find out HOW MOLER helps you help ourself AFTER you graduate, as well as BEFORE! Find out why MOLER Men are making DOUBLE the money others made last year, before Ladies’ Shingle ame so popular. You re NEXT in line for bi Brie MOLER way. Send Coupon en MOLER SYSTEM CF COLLEGES <« Address Nearest Branch (Street Address NOT Needed) Please send me without obligation on New York, N. Y. Cleveland, Ohio Atlanta, Ga. my part your Booklet C Chicago, Ill. Detroit, Mich. Memphis, Tenn. N Se. Louis, Mo. Denver, Colo. Dallas, Tex. |) Perrrrrrr rs rire eee Kansas City, Mo. Omaha, Nebr. Houston, Tex. Cincinnati, Ohio. Milwaukee, Wis. New Orleans, La. San Antonio, Tex.

SIGNS, BANNERS, CARDS Easily Painted fic htcu. Simply trace around a letter pattern and fill in. Leen in a large variety of reasonable

‘or free comelen. John Rahn, D2433 Glenn Views \v.,Chicago

ONN

INSTRUMENTS Drs Play for pleasureandpn and profit -—Conn gives you both in the short- est time. Easy playing is the out- standing feature of Conns, as the world’s greatest artists will tell you. Beautiful tone, perfect scale, reliable mechanism. With all their exclusive ‘features Conns cost no more. E TRIAL, EASY PAYMENTS on any band or orchestra instrument. Write for details, mentioning in- strument, R.O. Sweeten is one of the hundreds of famous stars who use and en- dorseConn instruments, Cc. G. CONN, Ltd. 532 Conn Bidg., Elkhart, Ind CULTIVATE YOUR MUSICAL BUMP

The Midget ‘Five-in-One’”’ Slide Rule ue a eS rer) tract Sia Tule, itv will etantly 280, btract, multiply and divide any Bination of whole numbers, . mixed numbers ‘and decimals. Gives cons and ry ee ah also Logs, Sines

Be an Expert While You Learn Wottheener’ fork Write immediately for nal_ profi! student. In personal instruction an Expert $55 to $90 a Week You never See a TRAINED watch a job. Got my my train- ing and say . b: o fos to email pay. vill he ay nn spare | time raise trai aloe, an Expert’s + yp and pay when 7 you i graduate. THOMAS SWEAZEY, Principal Bhicago gg of Sele oo Chicago, Itt.

our terms, methods, etc. your invention for our Instruc- tions. No Charge for the Above

NVENTORS your ipeas Send for our Guide Book, HOW TO GET A PATENT, and Evidence of Invention Blank, sent Free on request. Tells Send model or sketch and description of Information. of EEE Se Ere tee Ne SNR. van caus dom padwaodede aca ae RANDOLPH & CO. |: Dept. 130, Washington, D.C. See? 0) weir eon cloe Re ee a ——— Be Oe ee eee ee Se eee

© This seal on a radic or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21. ° —

a

Page 102

122 Your Choice 75c a Week sence a g We eal cut § the price i one-half

No matter what your occupation, one of the home study sets listed below will quickly fit you for a better job and bigger pay. Any set you select will be sent for seven days’ examination, and if you decide to buy you may pay the rock bottom price at the rate of only 75c a week. But you must act now! The rising cost of paper and binding materials won't permit us to continue the present low prices much longer, These books are the work of recognized author- ities. They are written in plain, easily understood language, by recognized authorities, and contain hundreds of photographs, diagrams, tables, etc., that make difficult points as simple as Hand- somely and durably bound in half or full morocco leather (except as noted), and stamped in gold. Pay-Raising Books At Greatly Reduced Prices Business Management, 8 vol., 2500 pages, 1000 pictures. Was $52.50. .......Now Carpentry and Contracting, 5 volumes, 2138 pages, 1000 pictures. Was$37.50, Now Civil Engineering, 9 volumes, 3900 pages, 3000 pictures. Was $67.50........ Now Electrical Engineering, 8 volumes, 3800 $29.80 19.80 34.80 pages, 2600 pictures. Was $60.00...Now 29.80 Automobile Engineering, 5 volumes, 2600 pages, 2000 pictures. Was $45.00....Now 19.80 achine Shop Practice, 6 volumes, 2300 pages, 2500 pictures. Was $45.00...Now 21.80 Steam and Gas Engineering, 7 volumes, 3300 pages, 2500 pictures. Was$52.50,Now 24.80 Law and Practice (with reading course), 13 volumes, 6000 pages, illustrated. Was SSS Se eae Now 49.80 Fire Prevention and Insurance, 4 vols., 1500 pages, 600 pictures. Was $30.00, Now 14.80 Telephony and Telegraphy, 4 volumes, 1728 pages, 2000 pictures. Was $30.00 ents kt, ee SS (eine wie Susie 3S 14.80 Sanitation, Heating and Ventilating, 4 volumes, 1454 pages, 1400 pictures. Was ELGtOLGcGsaascdcbs tess toes cee 1230 Drawing, 4 volumes, 1578 pages, 1000 pic- tures, blue prints, etc. Was $30.00..Now 14.80 Send No Money Shipped for 7 Days’ Trial Yes, we'll gladly ship any set right to your home or office upon your simple request. Pay only ship- ping charges when the books arrive. Don’t send a penny until after you have used them seven days, then remit only $2.80 or return them at our expense. Pay balanceat the rate of $3.00a month—75ca week. Act now—while these splendid bcoks are being offered at 20% to 50% less than regular prices. This offer is open to every person within the boundaries of the U.S. and Canada. Grasp your opportunity— fill in and mai! the coupon now. American Technical Society, Dept. X-520, Chicago American Technical Society, Dept. X-520, Chicago, U. S. A.

| | eo ee | I | for 7 days’ examination, shipping charges collect. | I will examine the books thoroughly and, if satisfied, will send $2.80 within 7 days and $3.00 each month, | until I have paid the special price of __.....------- ; If I decide not to keep the books, I will notify you at

once and hold them subject to your order. Title not | to pass to me until the set is fully paid for. l SS a ee on ae ae Pe | | i IN intra allot enintan lia taiingibinaies mew 6mte oie i er tae ‘(S} This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS, See page 21. POPULAR SCIENCE MONTHLY

Aethods Cleaning and Buffing Tumbler Made from Strong Barrel ‘A FTER several years of satisfactory experience with a tumbler made from a wooden beer barrel, I have found it to be quite as durable as the more elab- orate outfits costing two or three times as much. A large barrel can be used, al- though I prefer the half-barrel size. If more capacity is required, another barrel can be coupled to the same shaft. A hole 12 in. square is made in the side of the barrel by drilling four holes and cutting out the wood with a keyhole saw. The section cut out is used for a cover. Before the cutting is done, however, the hoops should be reinforced with wood screws or lagscrews through holes previ- ously drilled for this purpose. For the door clamps a piece of 14 by 2 in. iron is used. A 13/16-in. hole is

COUPLING FOR OTHER TUMBLER SHAFTS

LLL ——<—YQ CARRIAGE BOLTS WITH WINGNUTS

After being fitted with a door, the barrel is mounted between two inverted shaft hangers drilled in the center of each clamp to take a carriage bolt, which passes through the barrel about 3 in. from the edge of the opening. Each bolt is provided with a wingnut for clamping the door in place. Each end of the barrel is fitted with a flanged coupling provided with journal ends. These should be centered care- fully and lined up in relation to each other. Two plain shaft hangers inverted on the floor serve as bearings. A 24-in. pulley on the tumbler shaft and about an 8-in. pulley on the line,shaft give a suit- able speed. Aluminu:n or brass castings, as a rule, will tumble to a nice finish without using any polishing agent. For sheet-metal stampings the small slugs and scrap punchings may be placed in the barrel to speed up the work and produce a better finish. For a superior finish use dry saw- dust or leather scraps.—F. J. WILHELM.

Lathe Pan for Brass Chips Mest lathes have two pans for chips, one for iron and one for brass. If your turning is mainly iron, the trouble of changing the large pans can be saved by making a small pan that just fits in the opening in the bed under the chuck. The majority of lathes have a flange at the bottom of the bed that will hold the pan. It is best to provide handles with which to lift it out:—G. F. S.

Inventor's Universal Educator

'GENDFOR Si {| | =THIS FoR | DON’T LOSE YOUR RIGHTS TO PATENT PROTECTION Before disclosing your invention to anyone send for blank form ‘‘EVIDENCE OF COn. CEPTION”’ to be signed and witnessed, 4 4 sample form together with printed instructions & will show youjust how to work up youreyi- dence and establish thesame before filing ap. @ plication for patent. As registered patent at- torneys we represent hundreds of inventorgall over the United States and_Canada in thead. vancement of inventions. Ourschedule offeeg willbe found reasonable. The form “Evidence im of Conception,” sample, instructions relating to obtaining of patents and schedule of fees nc sag request. Ask for them,—a post card if will do. 274 Ouray Bldg. WASHINGTON, D. C. Originators of forms “Evidence of Conception.”

To the Man With an Idea I offer a most compreliensive, ex- perienced, efficient service for his prompt, legal protection and the development of his proposition. Send sketch, or model and description, for advice as to cost, search through prior United States patents, etc. Pre- liminary advice gladly furnished with- out charge. My experience and familiarity with various arts, frequently enable me to accurately advise clients as to prob- able patentability before they go to any expense. Booklet of valuable information and form for properly disclosing your idea, free on request. Write today. RICHARD B. OWEN Patent Lawyer 6 Owen Building, Washington,D.C. 41-D, Park Row New York City

contains 900 mechanical movements; 40 per- petual motions. Tells how to obtain and sell patents. Suggests new ideas. Explains how to select your attorney and avoid patent sharks. Special price (for a limited time) $1.00 postpaid. Albert E. Dieterich, 681-A Ouray Building, Washington, D.C. Eg “) mmercialized OWN A CASH OR ROYALTY BASIS ade PATENTED or UNPATENTED dn Business 25 Years ‘Complete Facilities-References. érie ADAM FISHER Mrs. Co.

FISHER MFG. CO. 183-D Enright Ave St. Louss,Mo.

en 2266 & ee & eee &* ent

Page 103

ntors all i thead. relating 1 . of fons ost card AKS ———____—_—_—— icator 40 per- and sell ins how t sharks. ost paid. 3uilding, T BACK Saet fe. Works tke. = typewr op ing New Iny Invention —_ A PRACTICAL EDUCATION IN ELECTRICITY Learn by the thorough, role us 40 scientific ier va ay bebe our cremny, fare, win eee rr e us Per,” ie Bit ie id rma . ics, m ar OF ENGINEERING oF MILWAUKEE psMm-525 415 Marshall Stre Milwaukee, Wis. Twolncomes Poncien eal students, says ‘‘Am earring’ ala oaths @ month, besides I made over qatet twomonths.’* What otherstudents rosgne you can do. ae rsonal instruction at home by mail will enable y: become a draftsman. in i teceaiig short time. Write for free book today. Chief Draftsman Dobe, Dept, 13-65 1951 Lawrence Avenue, Chicago, Mlinolg “] EARN $12 A DAY MAKING SIMPLEX SIGNS AT HOME” This is but one of the many letters we receive from those who are making Simplex Chipped Glass Signs, Medallions, etc., with our system. No ic talent is required. Big demand for th this work by local and out of town people everywhere. Every home and _ business place is a prospective customer. 4We help establish you and furnish all materials and plans for securing orders. For further particulars write: Simplex Utilities Co., 1133 Broadway, Dept. 127, New York City POPULAR SCIENCE MONTHLY ARITHMETIC oF ELECTRICITY A practical treatise on electrical calculations of all kinds reduced to a series of rules, all of the simplest forms, and involving only ordinary arithmetic. 200 pp. Price, $1.50. POPULAR SCIENCE MONTHLY 250 Fourth Avenue :: NEW YORK Just Out. 13th Edition A NEW AND GREATER Dyke’s Automobile Encyclopedia Entirely Rewritten, Rearranged and Illustrated. Greatly Enlarged; 1238 Pages, 4143 Illustrations. A Practical Book for Everybody The Repairman will find this book a ready reference and guide. The Auto Owner will know how to diagnose troubles and know when repairs are done right. The Student learns the funda- mental principles, the key to a suc- cessful repairman. This Book Will Teach You to Become An Expert Auto- mobile Repair- man, not only on testing, adjust- ing and repairing engines, carbure- tors, clutches, rear axles, differentials, tires, etc., but an Electrical Expert on ignition, gener- memeng starting mo- tors, storage bat- teries, etc. Diagnosing any trouble will be easy. Don’t -wait—Order Now! Cloth $6.00—-Limp American Morocco $7.50 Postpaid Popular Science Monthly 250 Fourth Ave., New York City Better Shop Method Special Diamond Holder for Redressing Emery Wheels YW HEN truing a surface grinder wheel with many diamond holders I have seen, it is necessary to raise the wheel high enough to allow the diamond to pass under it. After the wheel is true, it has to be reset to its former position. To avoid this resetting, the holder shown may be used. It is simply a cast- DIAMOND HOLDER Through the use of this diamond holder a wheel can be redressed without being raised iron block with one side planed to a 45- deg. angle. A hole is drilled at right angles to the angular face to receive the diamond tool, which is locked with a set- screw.—H. W. Fountain-Pen Filler Improves Soldering Acid Bottle [N 25 years’ ex- perience I have HOLE THE SIZE found nothing better OF A PIN than acid for general soldering, but I have GLASS adopted a_ better DROPPER method of handling it than is used ordi- narily. I took the glass from an old fountain-pen filler and slowly revolved the point in a gas flame until it was nearly closed. Then I burned a hole through the cork of a wide-mouthed 2- oz. bottle and pushed the filler through. A new cork is needed about every six months. With ‘the hole in the filler the right size, the acid does not run out if the bottle is tipped over, but as soon as the point is touched on the work, the acid comes out instantly.—ALLEN BRUNCK, Town Line, N. Y. TM la le i MM) 7 th .- SOLDER- ING ACID S A Hammer of Unusual es ae 4 P IPOLISH he TOOLMAKER friend of mine re- cently made a hammer that so im- pressed me because of its design and “‘feel”’ that I copied it for the readers of POPULAR SCIENCE MONTHLY who like fine tools and take pride in artistic merit as well as general utility.—O. B. © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21. EARLE E, LIEDERMAN The Muscle Builder What Is a Bohunk? A BOHUNK is a man who knows the right thing to do and then deliberately does the opposite. Some- times we call these fellows fools. Sqmetimes we use stronger words to describe them. We laugh at them. We pretend they are funny. But we never Tespect them. And _still—how many fellows are just plain BO- HUNKS and never realize it? They are given a good, clean body to start with. They know that this Body is one of the most delicately constructed organisms ever put together. Their common-sense teaches them that they must not abuse it—and then: they eat every blame thing they can lay their hands on just to satisfy their appetites. They go on committing sins against their flesh that even a dog would not do. They know that their bodies need exercise just as much as need food. And still they permit themselves to grow soft and flabby, accumulating poisons, disease and every kind of germ imaginable. THE WISE MAN Come out of it, fellows. Don’t be a plain dumb Dora. Don’t you realize you can’t keep this up? You're really not living at all. You only think you are. Cut out this foolishness and get busy. Drive those decaying tissues out of your body. Throw out your chest and give your lungs a treat with some good, pure oxygen. Harden up those soft, flabby arms of yours. Take those rolls of jelly off your body. Get some honest-to-goodness muscle. Find out what real health and strength mean. You'll realize then how foolish you’ve been to go without it. It’s been yours right along for the asking. A NEW MAN IN 90 DAYS Come to me and let me help you. You can’t do it alone. You may think you can, but you'll find you are wrong again. This is my job. I’ve been doing this very thing for 15 years and I know just how it can.be done. I’m going to pack one full ——_ of healthy muscle onto those arms in just 30 days. m going to add two inches to your chest in the same ey. of time. Yes, but that’s nothing. I haven't done a thing yet. Now come t real works. Just watch ’em grow. I’m going to broaden your shou'ders and deepen your chest. I’m going to stretch out those lungs of yours that are now sticking together like pieces of fly paper. Every time you take a breath you will feel the old oxygen shooting through your blood and making your whole body tingle with new life. I’m going to put some real pep into that old backbone. I’m going to build up those muscles in and around your vital organs. You will feel the thrill of vitality throughout your entire system. And all I ask is 90 days. Sounds good —doesn’t it? You're durn tootin’ it's good. It’s wonder- ful. And the best of it is—I guarantee all this. Do you doubt ‘me? Come on, then, and make me prove it. 4 s the stuff. That's what I like. Are you with me? t’s go. Send for my new 64-page book “MUSCULAR DEVELOPMENT” It is FREE It contains forty-five full page lager 4 of myself and some of the many prize-winning pupils I have trained. Many of these are leaders in their business professions today. I have not only given them a body to be proud of, but made them tter doctors, lawyers, merchants, etc. Some of them came to me as pitiful weaklings, im- ploring me to help them. Look them over now and you will marvel at their present physiques. This book will prove an impetus and a real eapisotiom to you. It will thrill you through and through. All I ask is ten cents to cover the cost of wrapping and mailing and it is yours to keep. This will not obligate you at all, but for the sake of your future health and happiness, do not put it off. Send today—right now, before you turn this page. EARLE E. LIEDERMAN Dept. 1305 305 Broadway New York City oS A | eR EARLE E. LIEDERMAN Dept. 1305, 305 Broadway, New York City Dear Sir:—I enclose herewith 10 cents for which are to send me, without any yo nag ke my part ever, a copy of your latest boo uscular Deseo: ment.’’ (Please write or print plainly.) Name. ...... cnn ccnccccccccccceccccecccceecccecce Sicccwccccence oso ChPoascowsecsswn State...ccce

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124 Learn at home to read BUILDERS’ BLUEPRINTS HE quickest way to secure advancement in the building trades is to master’ the art of reading blueprints. You must have this knowledge if you want to be a fore- man, or to have a building or contracting business of your own. One of the best books ever published on this subject was written by William S. Lowndes, Ph.B., and is called “Builders’ Blueprints—How to Read Them.” This book contains 184 pages and 97 illustrations. Ten full-sized blueprints are included—the same size and scale of blue- prints or working drawings used in the erecting of buildings. The cost of this book, including the 10 full-sized blueprints, is only $3 and it is a wonderful bargain at that price, for it will help you tremendously in your daily work. SEND NO MONEY ust check the name of this ‘Builders’ Blueprints” ook or the names of any other books you want on the Free Examination Coupon printed below and we will send them to you on approval by return mail. Don’t miss this opportunity to get these won- derful books. For just a few dollars you can get valuable information that will help you every day in your work—information that is Sound to help you get a better job and a larger salary.

International Correspondence Schools Box 7652-D, Scranton, Penna. Please send me the books I have checked below. I shall either return them in five days or send you the money. CJ Builders’ Blueprints—How to Read Them (Ten full-size blueprints included free) - - = - = = - - - = $3,00 (J Carpentry and Joinery and the Steel I I { | I | Square. 514 pages. 358 illustrations 4.50 | C) Building Trades Handbook - - - - 1.00 [] Plain and Fancy Brickwork - - - 1.50 | |] The Slide Rule, How to Use It - - 1.00 (] Concrete Engineer’s Handbook - - 1.00 | (] Plumber’s and Fitter’s Handbook - 1.00 (J Plastering and Stucco Work - - - 1.50 || struction ce St eS oe 1.50 | 0 Hollow Tile Construction and Stucco | Finish - - - - - - - - == 1.50 C1 Estimating Building Costs, Specifica- | tion and Contract Writing - - - 3.00 (1 Good English for Everyone - - - 3.00 | (] Civil Engineer’s Handbook - - - 1.00 ] Machine Shop Handbook - - - - 1.00 || [] Structural Drafting - - - - - - 4.00 [] Mechanical Drafting - - - - - 3.00 | (] Building and Materials - - - - - 3.50 [] Elements of Surveying - - - - - 3.50 | (] Radio Handbook - - - - - - 1.00 | Name.....

i 1 I l | | | l | | | Cj Plain and Reinforced Concrete Con- l I | | | | | l !

> Qa Q tony B wa

Get back your “WR= winning muscles Getinto form for outdoor pleasure with Absorbine, Jr.—a rubdown that keeps out stiffness and puts back the old strength $1.25 @ bottle at your druggsst’s W. F. Young, Inc Springfield, Mass.

POPULAR SCIENCE MONTHLY

| ing a sealed joint.

Better Shop Methods How to Make an Eye Magnet for Use in the Shop [* SHOPS where many steel and iron castings are ground, hardly a day passes without some of the workmen get- ting particles of the metal in their eyes, no matter how stringent are the regulations in regard to wearing goggles. In our shop I have used the magnet described below successfully for several years in removing the offending particles. A small hard rubber syringe of the type illustrated is bought at a five-and-ten-

CUT OFF | HERE

E The magnet is made by winding fine wire around a nail and inserting it in a casing cent store. The piston is removed and the pipe cut off at the base as shown. Fit a large nail into the hole thus made, allowing it to protrude an inch or more from the rubber casing. Make two core ends of \%-in. fiber to suit the nail. Wind the bobbin thus formed with several layers of No. 22 single silk-covered mag- net wire. Solder the leads to a length of flexible lamp cord. File the free end of the nail to a rounded point and polish. Hook it up to several dry cells and it is complete.—P. A. JUDD.

Air Pressure Used for Testing Water-Pipe Connections F°k testing a piping job after the work is done and before turning on the water the plug illustrated is useful. It is intended especially for checking the work in such jobs as installing range boilers and hot-water systems. An ordinary pipe plug is drilled 13/32 in. through the center. A valve stem from a discarded auto : tube is inserted, the locknut mak- The rubber sur- rounding the stem

on the tube should be cut around the WATERFRONT Fae srcrp flange, So aS tO RUBBER GASKET PIPE PLUG leave enough to make a gasket. Use a T connec- tion at the joint marked C for attaching the test plug. Shut off the system at point A and B by inserting in each union a blind gasket to be removed after the test. The plug then is screwed into any side outlet in the system and pressure is applied with a hand pump to which a gage is attached. From 50 to 60 pounds is sufficient to indicate any leaky joints. The plug is replaced after the test with a regular pipe plug. The plug and diagram of the connections

|

IS) This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. May, 1995 6eR99 Storage “B” Battery 2. $2¢els Lasts Indefinitely—Pays for Itself Economy and performance unheard of before. at a negligible cost. Approved and listed as S$ leading Radio Authorities, including Pop. Radio Laboratories, Pop, Sci. Inst. Standards, Radio News .» Lefax, Inc. and other im portint institutions. E uipped with Solid Rubber Case, an ance against acid and leakage. Extra heavy glass jars, 3 rugged plates. Order yours today! ieieniiia 7 SEND NO MONEY 22iiettte a weenie Ba order is received. Extra Offer: 4 batteries in series (96 voits: Pay expressman after examining batteries. 5 per cent discount for cash with order. Mail your order now! 4 } enna bd wee . Wabash Ave. ept. 80 ii pa Maker ofthe famous World aio "A Suorage Batic as . $12.50; 120 Amp. $14.50; < Prices: 6-volt, 10? Cuipped with Solid Rubber Bese. "* #164 World STORAGE BATTERIES IKDKA = WEAF'= WGN = WJS = KH IS] FOR RADIO KGO = KFAE= WIYe dany: Saw Books FREE - ‘Saws in the Shop,” “Saw Sense,’’ ‘“‘Saws on ~ ad Farm.” Just send us your name and address and say which of these helpful books you want and we will send it FREE. Write NOW E. C. ATKINS & CO., Inc. Dept. D-20 Indianapolis, Ind, BEAUTIFY YOUR CAR/ ’

Promanco Auto Frames all the rage! Adjustable. Add to a . Order toe Propucts M. TH ST., ary Re I i Saves Galions of Gas Any reader can prove on his own car, Ford or any make, how easy it is to increase gasoline mile age 50% and get rid of carbon, by writing Ed. Naylor, 481 Produce Ex. Bldg., Kansas City, Mo, He has perfected an amazing invention which any one can put on car in three minutes without boring or trouble. Doubles power on hills. He wants agents and is willing to mail sample at his own risk. Send him your name today. yfishermen, Fishing facts and ‘hints. Tells how to compete in [fis our annual $2,000 Fish- book Photo contest. A postal me f «gets it FREE! SOUTH BEND BAIT COMPANY e 14581 High Street South Bend, Ind. a

Acne Eruptions on the face or body, bers Itch, Eczema, Enlarged Pores and Oily or Shiny Skin. Write today for my FREE BOO FREE “A CLEAR-TONE SKIN,”— telling how cured myself after being afflicted 15 years. E.S.GIVENS, 153 Chemical Bidg., Kansas City,Me.

No Joke To Be Deaf I make myself hear after telng deat for 25 years with my Artificial Ear Drums. § wear them day and night. They are pet fectly comfortable. No one sees They stop head noises. Write me and I will tell you a true story, how I became deaf how i ific a bear. eg Oe Ai icial © Drum Co., 86 Hoffman Bidg., 2539 Woodward Ave., Sarroit, Mich

A SERVICE FOR YOU In Buying Radio & Tool Equipment For list of tested and approved products write Hg) the Popular Science Tastitute of Standards. See page 21.

See page 21.

d c I i ! I I I 1 é \ 1 1 ;

Page 105

r Gas ar, Ford or isoline mile writing Ed. s City, Mo. 1 which any hout boring He wants at his own on 2 Hohner is Fun! Music plays an important part in the edu- cation Pe the boy or girl; and today the harmonica is playing an important part in musical education. Anybody can quickly learn to play a Hohner Harmonica with the aid of the Free Instruction Book. There are no long hours of study and practice—just a few minutes a day, when you feel the desire, and you will soon be playing popular, classical and jazz selections. Homework on a Hohner is fun. It teaches accu- rhythm and expression, the basis of a musical po Ne Get a Hohner today and ask for the Free Book. If your dealer is out of copies, write M. Hohner, Dept. 182 New York City. Leading dealers everywhere sell Hohner Harmonicas—50¢ up. Positively identified by the Ace trade mark stamped on the frame. A few strokes through the discs will sharpen the dullest knife. Try your hardware dealer first or send $1.00 t to ACE HARDWARE MFG. CORP. \ Philadelphia Chicago San Francisco J POPULAR SCIENCE MONTHLY and Crystal Sets FRESHMAN Double Adjustable Crystal Detector No more searching for the sensitive spot. —Merely turn the knob as you would a dial. For base or panel mount- ing, complete with Fresh- $ 1 .50 man Super-Crystal Atyour dealer’s, otherwise send purchase price and you will be supplied postpaid. CHAS. FRESHMAN CO., Inc. 240 West 40th St., New York Those Who Carry Our Mail in the Air (Continued from page 32) this is in use the dense clouds will be robbed of their terror.” Many of the air pilots agree that the danger stretch of the transcon- tinental route is not in the Rocky Mountains, but along the airway between Mineola, L. I., and Cleveland, Ohio. For much of the time the Alleghanies are covered with fog blankets, and there is one span where scarcely a landing- field is available for 200 miles. Dense snow and sleet storms are as serious as fogs. The pilots agree that ex- treme cold does not slow down the service, because the men are clothed for protection from low temperatures, and each plane is equipped with cockpit heaters. They tell me, however, that it is far from plea- sant to spend eight hours battling a bliz- zard, through blinding snow, with a bitter wind screaming around them, and with no ground lights visible for their guidance. One of the recent developments in the service is snowshoe equipment for the mail-planes, for use in forced landings. Rain also brings disadvantages, for the high speed of the plane causes each drop that strikes the pilot’s cheek to bite fiercely and painfully. ET Pilot H. G. Boonstra tell of his experience with a head wind. In piloting postal plane No. 357 from Chey- enne to Federal, in Wyoming, Boonstra received liberal education as to what the wind can do to a flyer. ‘“‘The distance is 18 miles,’’ Boonstra says. ‘On the night before Christmas, 1924, I spent 73 minutes in covering this stretch. Try as I might, I could go no faster. Believe me, it was some wind! The thing figured out that I was driving the plane at a speed of 100 miles an hour, that the wind was driving me back 86 miles an hour, and that my actual prog- ress was at the rate of only 14 miles an hour.” Boonstra is a hero to the people of Pinedale, Wyo. Pinedale is an isolated community, 105 miles north of Rock Springs, cut off from the outside world for the greater part of each winter. Some time ago a rancher was dying in this re- mote settlement and no medical aid was available. In this emergency Boonstra ferried Dr. E. S. Lauzer, a Rock Springs surgeon, to the bedside and was instru- mental in saving the rancher’s life. Some time after the Pinedale incident, Boonstra was lost on his regular run and grave fears were entertained for his safety. Recalling his trip to Pinedale, every man in the entire countryside dropped his work and _ searched for Boonstra until he was found. They tell me that any man in the air-mail service of the Rockies can have anything he wants at the hands of the citizens. In any narrative of the transconti- nental airway, Pilot Paul Scott enters at frequent intervals. Before his experience in the Utah Mountains, already told, Scott was flying eastward toward Salt Lake when his radiator exploded. The plane took fire, but Scott succeeded in (Continued on page 126) This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21. Applying the new tread—the inventor, Emil Nestler, rub- ber expert and engineer, de- monstrates one of the seven simple steps in this amazing proc- ess, > 2 x - t Ha sta) Be President of your Own Company HE discovery of the first known method of joining new rubber to old by actual fusing or welding is your opportunity to own a highly profit- able business in your own name. Millions of pneumatic tires—car, truck, balloons—now junked merely because part of the rubber has worn off the treads, can now be kept in service. Car owners can cut tire costs in half. NESTLER Rubber Fusing Process The Modern Method of Tire Servicing Think of what this service would mean right in your community! Not an experiment. Process has been carefully perfected during past seven years, and has been endorsed by the leading authorities. Thousands of tires al- ready Nestlerized (retreaded by Nestler Process) have demonstrated soundness of method in actual road service. Make Guaranteed Tire Repairs. Your Nestler Equipment will enable you to offer a Guaranteed Tire Repair Service, too. The Nestler Method is faster, less costly and more profitable than old-fashioned methods and in addition produces a positive fusion of new and old rubber that you can guarantee. The Nestler Process is a revolutionary advance in the art of tire servicing. No experience necessary to become an expert in this line. Process is amazingly simple. We teach you free when you buy your equipment. Profit possibilities are un- limited. Small capital required. Right Now we can make you a Special Proposition that assures Earnings From The First Week —just like entering a going business. ; 1 ghaas tas Mnaes temie Get the facts. No Fusing Process and de- obligation. Fullest scribes he methods ze ror ae Pa Dp : : ust write for the Pour own community. Ddooklet. Ask for the Send for it today. Special Proposition. Limited and exclusive territories now being assigned. ~ To get the territory of your choice, write Now! This is an oppor- tunity of a lifetime and you should not miss it. Nestler Rubber Fusing Co., Inc, Dept. P. S. 245 West'Séth St., NEW YORK CITY

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126 The transfer of another clubman is here recorded Some smokers appear to have be- gun their pipe-smoking with Edge- worth and have stuck to it ever since. Others, of more adventurous or more inquiring nature, have evident- ly started out to ‘‘try ’em all” before signing up with any one brand. Mr. Schroeder’s enthusiasm for his final favorite is evidently based on a pretty broad knowledge of the field. Read his letter: Messrs. Larus & Bro. Co., 21st & Main Sts., Richmond, Virginia. Gentlemen: I have been reading witlra great deal of interest the advertising you have been running in the Saturday Evening Post, particularly the issue in which the letter from Mr. K. F. Chapman stated that he was a member of the ‘“Tried-’em-All Club.” It may be of interest to you toknow that I was a member of this same club up to about four years ago, when I resigned and joined the “Edgeworth Club.” I don’t mind telling you that I was employed in one of the largest tobacco companies in the country for about twelve years, and my loyalty to this company compelled me to smoke the brands of pipe tobacco which they manufactured; but try as I would, I could not become a steady pipe smoker. After I left this company several years ago, I tried Edgeworth Ready-Rubbed Tobacco, and I have been smoking it ever since. Now, I have a life membership in the “Edgeworth Club” and take it from me it is ‘“‘some club.” Respectfully yours. E. A. Schroeder. Let us send you free samples of Edgeworth so that you may put it to the pipe test. If you like the samples, you'll like Edgeworth wherever and when- ever you buy it, for it _ never changes in qual- ity. Write your name and ad- dress to Larus & Brother Com- pany,10E South 21st Street, Richmond, Va. Edgeworth is sold in various sizes to suit the all purchasers. means of Both Edgeworth Plug Slice and Edge- worth Ready-Rubbed are packed in needs and small, pocket-size packages, in hand- some humidors holding a pound, and also in several handy in-between sizes. We'll be grateful for the name and ad- dress of your tobacco dealer, too, if you care to add them. To Retail Tobacco Merchants: If your jobber cannot supply you with Edge- worth, Larus & Brother Company will gladly send you prepaid by parcel post a one- or two-dozen carton of any size of Edgeworth Plug Slice or Edgeworth Ready-Rubbed for the same price you would pay the jobber. POPULAR SCIENCE MONTHLY Those Who Carry Our Mail in the Air (Continued from page 125) landing. Ship and mail were completely consumed—and there is something im- pressive in the fact that this is the only case in which air mail has been destroyed. When night flying was attempted many people shook their heads and predicted a heavy death list for the daring pilots. These forecasts have proved without foundation. The first fatality occurred after six months of operation, when Clar- ence Gilbert was killed near DeKalb, IIl. Evidence indicated that his motor had died when there was no landing-field within range. It appeared that the pilot jumped and that his parachute was caught by the fierce wind and torn from its ropes, causing Gilbert to be dashed to his death. Gilbert’s death was notable for more reasons than one. Not only was it the first fatality in 1,200,000 miles of night flying, but it afforded a fine example of the sense of duty actuating the men of the postal service. In his perilous position Gilbert took time before jumping to “pull” the electric switches on his plane. This presence of mind prevented the ex- plosion of 90 gallons of gasoline carried in his tanks, and saved the plane and its cargo of mail from destruction by flames. The great factor of safety for the mail pilot is his parachute, always strapped to his body, and ready for instant use in case of emergency. Another safety device carried by night- flying planes is a brace of flares stowed in a recess in the bottom of the fuselage. These are for use in forced landings away from the emergency fields. By lighting and dropping one or both flares, the pilot may produce brilliant illumination for half a mile in every direction, enabling him to select the smoothest spot for his landing. The flares float on parachutes, and remain lighted for 10 minutes. RANK YAGER used these flares to good advantage on a westbound trip from Omaha to North Platte. About mid- night he ran into a severe storm. By the light of his floating flares he was enabled to land with but slight injuries, although his plane was demolished. A by-product of the air-mail service is a machine known as the’ puddle jumper, which patrols the lighting system of the night-flying airway. These planes have 33-foot wings, seven feet four inches in width. They are able to land at low speed, which makes it possible for the pilot to drop to earth in small fields. The machines have big flat wheels, known as “‘puppy feet,’’ for which the soft mud of a rain-soaked field has no terrors. The puddle jumpers go where other planes would fail. Their all-metal pro- pellers serve as weed cutters, making it safe to land and take off in dense growth that would chew up the wooden parts of the mail-plane propellers. On this type of plane is an electrician whose sole job is to see that the lighting system of the night airway is kept in perfect condition. He is responsible for the proper working of the five beacons of 500,000,000 candle- (Continued on page 127) © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21. May, 1925 Agsat Users Wantea GEE hew caay it fs with th ag ois ad Suan EMT, which Y send Froo, toma ui a day in your i st biG te — pe ng a made, ov non-skid Cordis guara: for mil balf way arcund the tran teedby Sead The Mellinger Plan starts you i n business, all or parg time; no eapital or experience, needed, Tires paid « cn approval. Lowest wholesale Prices i if you. boost MELLINGER TIRES, Tinks, I Ihave Py aR Beares ME LLINGER TIRE Philadelphia, Pa. Dept. Bg aos pa # ZIP-ZIP j HOUSANDS of boys are Y made happy with this won- derful Zip-Zip shooter, something every boy wants and never gets tingd of. Kip-Sip, cheoter jp scientifically and practically’ made; boys, ou like hunt- ing and outdoor sports eta gee Zip shooter with plenty of pep and. ‘orce and learn that your dealer happens os to have em, Agents 20005 Make --« INSTANT WELD. Welds Rubber Instantly. Better, quicker, and easier than vulcanizing. ONCE ON—ALWAYS ON. No Heat or Cement required. Re- pairs blow outs, punctures, rubber boots, shoes, etc. Guaranteed to outwear article repaired. Agents, Salesmen and Distributors Waited, TOURIST PRIDE MANUFACTURING CO. | sin Desk 45E MINNEAPOLIS, MINN, ete Tool Cases for ohiaets Car. enters and Tool akers; none better; . thirty styles. Quarter- ed oak and metal cov- ered. Ask for booklet. “Built for Sevview™: ign tools and meta slectricity like ada on metal with en or pencil omplete outfit B3.50: pr. wosie ony mare, pitereet- scri circulars free day. ents wanted. _ to- Arkograf Pen Co., 1171-A East Stark St.,Portiand, Oregon SEND FOR THE dad A ae ge oe CATALOG Gur net price list. Full line of auto bodies and accesnco- ties for Fords at Wholesale Prices. Save 27.85 ine Profit “git W. Ohio st. Dept. 8, Chicago, Il. FOR FORD- Prices from International Body " Works, Our marvellous, te) nan MOVIE M HINES sell as low as $3. a8 ponent and use same size film.as big theatres. We also have wonderful films at lowest prices—with a new film ex- change service. DON’T Miss THIS! rite NOW for free catalogue PARAMOUNT MFG. CO. Dept. PS 7 Boston, Mass.

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May, 1925 nth ne better; . . Quarter. netal cov- r booklet. Service” inton, Ohi we May, 1925 —— Those Who Carry Our Mail in the Air (Continued from page 126) power each, the 33 beacons of 5,000,000 candlepower, and the 360 flashing lights of 5000 candlepower, lining the route from Cleveland to Rock Springs, Wyo. One puddle jumper works between Cleveland and Chicago, one between Chi- cago and Des Moines, one between Des Moines and Grand Island, Neb., and one between Grand Island and Rock Springs. The electrician carries a type- writer, and when he spots trouble he a memorandum instructing the caretaker to look after it. Where there is no caretaker, the electrician lands and fixes the lights himself. Radio stations along the transconti- nental airway serve as dispatching sta- tions and furnish quick communication in cases of forced landing. These stations also give advance weather reports and convey orders to the various depots. Weather information and threats of pos- sible storms ahead are signaled to pilots by caretakers at frequent intervals. In the air-mail service much of the fly- ing is done by seasoned veterans. In a recent compilation, William C. Hopson, of Omaha, held the record of performance, with more than 2236 hours of flying to his credit, and a distance of 221,876 miles. James H. Knight, of Omaha-Cheyenne, had flown 2311 hours, ‘covering a mileage of 211,095. E. Hamilton Lee’s record stood at 2387 hours and 201,205 miles. IN THE wilds of Alaska the Post Office Department has demonstrated the val- ue of air-mail service for inaccessible areas. A series of flights between Fairbanks and McGrath proved beyond doubt that the airplane is the mail messenger of the future for rugged and isolated regions. Dog sleds require 35 days for the round trip of 742 miles. Pilot Carl B. Eielson made repeated round trips in slightly more than six hours of actual flying time. In one of these journeys the pilot became lost and was overtaken by pitch darkness, in the heart of the mountains, with not even astar for guidance. In this plight he could not land. The only thing to do was to wander around in midair. After more than an hour of perilous flying he picked up the Fairbanks beacon light and made a safe landing. The mail-planes carry a wide variety of cargo, from fresh California dahlias for the New York dahlia show to_ the latest New York styles in dresses for a Los Angeles fashion show. Bankers use the mail service freely, because of the saving in interest. By airplane the time con- sumed in transmitting funds is reduced three days, with an estimated annual interest saving of thousands of dollars. International mails are speeded by the air-mail service. As much as two weeks may be saved in the transmission of Euro- pean mails for Australia and the Orient, formerly sent through the Suez Canal. The air mail is still in its infancy. Its service to the public is being constantly extended. That it is proving such a dis- tinct success is due largely to devoted, courageous fliers who speed over vast stretches of the country every hour. POPULAR SCIENCE MONTHLY IN ONE y As Earne MONTH A New Business—Big Business A Business to Enthuse Over — The “Ideal” Lawn Mower Sharpener A wonderful invention that eharnene lawn mowers scilentifi- cally—quickly—perfectly; does the work as nothing else can. FRED C. MILKERT OF ROSELLE, ILL., WRITES: “The Ideal Lawn Mower Sharpener put me in business, starting in the basement of my home and forcing me now for the third time to move into bigger quarters. Today the dream of my life— a shop of my own — is realized. With amachine like yoursanda little hustle any man can havea business of his own and beindependent.” D. H. NOAKES, MILFORD, OHIO, WRITES:*‘‘Several years agoI started sharpening mowers in a 10 x 10 shed. Today I own a store of my own on Main Ave., No. 212, valued at $8,000.00. The ‘Ideal’ Grinder didit all.” FRED MILKERT, W-F-KENDT, SUFFALO,writes: ZENO BRANDON, MIDDLE- Roselle.iil.writes: Isharpened 994 lawnmowers last sea- TOWN, OHIO, writes: “I made r ial “gon, and the receipts were nearly $820.70 in 55 days with my ‘Ideal.’ Last June I sharp- $2100.00 which is not bad Have made as high as $38.70 in one ened 256 lawnmowers day.” po which gt ond for a side line.” ay. iia avons _— You Start Now Lawn mowers are dull—owners don’t know where to get them sharp- ened. Mowing the lawn dreaded because of dull ‘g# or improperly sharpened mower. Lawn mowing % healthful, invigorating and pleasant when Mower is ‘‘Ideally’’ sharpened. You do the work scienti- fically—you are in big demand. Lawn Mowers Sharpened to Razor Edge— People glad—owners delight in mowing lawn with mower sharpened on an‘‘Ideal.’’ Mower runs light—click-click-click and the grass is cut. Build permanent business for yourself. Start now! WRITE TODAY , seem me Pee = 4 2 ee IT TODAY catalog and booklet High and Bell $ ; a estore Say gy cataingandbotietetGeoreeSasit™ . e Piscine «os thdesenveneo vy eaaendeal The Fate-Root-Heath Co. SPE fics cxit ies ine batie+s% High and Bell Sts., Plymouth, 0. = @ EF is MAKE MONEY AT HOME You can earn good money at home in your spare time making show cards for us. No canvassing or soliciting. We show you how by our new simple instructograph method. We supply both men and women with work at ome, no matter where you I:ve, and pay you cash for all work completed each week. Full particu- fective; modelled on latest type of Revolver; appearance alone is enough to scarea burglar. When loaded it may be as effective as a real revol- ver without danger to life Cal. Biank Price 50c. a Blank Cartridges, by express, 50c per Johnson Smit lars and booklet free. Write today. . ae J : > . AMERICAN SHOW CARD SYSTEM LIMITED in 1 2 ee ? 206 Adams Building, Toronto, Canada j ht —_— 4 % it BLANK CARTRIDGE Pisrox Wp) It From the : agg PRICES Marvelous new Indian Prince—the Personal Motor—goes 90 to 100 miles on a gallon. 00 Operates at less than 1-3c per mile. Light— Safe—Clean. You learn to ride it in 5 minutes. Costs less than any other high-grade machine. Write today for illustrated booklet telling all about this new Indian Prince—the Personal Motor—and how easily you can buy it. Gndian Motocyele Co. Dept. H-5, Well made and ef- - _ It takes standard .22 - Cartridges obtainable everywhere. Ff - Superior quality $1.00 Postpaid, Mapaeyee h & Co., Dept. 346. Racine, Wis. Springfield, Mass. © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See Page 21. ' Become a big-pay man in the greatest industry of alltime. Quickly, easily and right at home, you can fit yourself for highest salary positions, or you can cash in on your spare time. The call is urgent for mechanics, operators, designers, inspectors. Unlimited, fascinating opportunities on land or sea i Tram YOU «* HOME c2 ARADIO EXPERT Under my practical, easy to understand, instruction—you qualify in an amaz- 9 ingly short time. No previous experience is necessary. Every branch of radio becomes an open book to you. You learn how to design, construct, § operate, repair, maintain and sell all forms of Radio appsratus. My methods - are the latest and most modern in existence. . FREE fsntieitenraratestset Write Today ra? FREE A. G. Mohaupt, Radio Enginser, RADIO ASSOCIATION OF AMERICA, Dept. 45, 4513 Ravenswood -Ave., CHICAGO

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128 250,000 MECHANICS USE SNAP-ONS Look for the name “Snap-On” on each handle and sockct— without it no wrench is a genuine Snap-On ' They'll tell you there’s a Snap-Ou Wrench Combination for fast work on every nut—whether out in the open, around a corner or in the deepest and hardest-to-reach place. They'll testify to the quality of Snap- Ons, as well as to the liberality with which the Snap-On guarantee is main- tained. Snap-On Wrenches are the perfected maintenance tools of this day and age. Get acquainted with them now. Selected Sets for Car Owners There's a small set especially selected by Snap-On engineers for your particular car. All the wrenches you need—none you don’t need—and. at a price you'll say is trifling compared to what they'll do. Ask to see it. Snap-on Socket Wrenches SNAP-ON WRENCH CO., MFRS. Milwaukee, Wisconsin Motor Tool Specialty Co. Distributors 14 E, Jackson Blvd., Chicago Send me particulars. My address is— © POPULAR SCIENCE MONTHLY If You Were Trapped in a Burning, Building (Continued from page 34) extinguishers charged with tetrachloride. ““We worked there for three hours and a half before we could be sure the fire was out and all the time the submarine was three-fourths submerged—likely to sink at any moment.”’ Ship fires on city water-fronts fre- quently defy the efforts of fireboats and firemen until the arrival of a squad in smoke helmets makes it possible to pene- trate the dense smoke and carry hose lines down to the blaze. The Baltimore rescue company recently succeeded in extinguishing a fire in the bilge of the steamship Florida after suffo- cating smoke had driven the fire com- panies back. 1% THE disastrous Equitable Building fire in New York some years ago a bank employee trapped in a steel-lined chamber on the lower floor of the building was rescued by firemen who sawed through the steel window bars. An hour and 15 minutes was consumed in the task, which today could be done in a minute or two with an acetylene torch. Nor is it only at fires that the scientific | equipment of-the rescue squad is found useful. In cave-ins on construction jobs, building collapses, and similar accidents the apparatus of the rescue firemen has saved many lives. Only a few weeks ago several people pinned under the wreck of an elevator in an office building’ in New York were released when the rescue squad cut the counterweights into half-ton chunks with the acetylene torch so that they could be removed. When the torch is used, by the way, a fire-extinguisher i is always kept at hand. Pulmotors of rescue companies fre- quently are employed in administering artificial respiration in cases of drowning and asphyxiation, as well as in resuscitat- ing persons overcome by smoke or fumes. A Detroit rescue company by the use of a pulmotor on an infant, apparently still- born, was able to start respiration. Some of the most effective devices em- ployed by rescue squads are the inven- tions of firemen. There is, for example, a heavy claw tool of soft steel, which finds its use in opening burglar-proof locks that have a bar across the inside of the door. This device was developed by a New York fireman. Its handle curves toward the edge of the claw instead of toward the side, so that when a lock gives way the handle will not strike the fireman who is prying the door open. N A fire in an Eastern city some time ago a door shut on a hose line, shut- ting off the flow of water. A fireman who had witnessed the incident suggested that a wedge would have been useful in holding the door open, and, since that time, every man in the department has carried a wooden wedge in his pocket, and no hose line is carried over a threshold without first wedging the door open. A fireman in another city made a hose roller to be used in hoisting a hose line to the roof of a building. This speeds up the work considerably. © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21. May, 1935 The LARGEST RADIO STORES in AMERICA ff the latest and best Hits’ in our new JUST OUT! oz 2¢~ ty-six page Radice Catalos including all the best and lat- est Kits, Parts and Accessories. Also our new 32 page bargain section—Write for your FREE copy today! SAVE MONEY! manupeccorers dealer surplus and et LS male ee only brand new fully guaranteed nation- ally advertised apparatus. Our enormous uying power pets us to pay spot cash and get rock-bottom prices—even way be- low manufacturer’s costs. catalog is crammed ees derful Radio Bargains at’s wh; ousands 0: our won- 509 SOUTH STATE STREET, CHICAGO, ILL., Dept. P.$.¢ Stop Using a Truss STUART’S PLAPAO- PADS are different from the truss, being mechanico- chemico applicators made self-adhesive purposely to hold the distended muscles securely in place. No straps, buckles or spring attached—cannot slip, so camnot chafe or press against the pubic bone. Thousands have _ success- Reduced fully treated themselves at Reduced Fac-Simile home without hindrance Fac-Simile Gold Medal from work—most obstinate Grand Prix cases conquered. Soft as velvet—easy .to apply—inexpensive. Awarded Gold Medal and Grand Prix. Process of recovery is pate 80 afterwards no further use for trusses. We _ prove it by sending Trial of Plapao abeciutely FR Write name on Coupon and send TO Plapao Co., 790 Stuart Bldg., Se. Eoaat Mo, for Finger Print Experts = and Students Something new! Premiere Finger Print Powder. Brings out invisible prints on many_ surfaces. Discovered by famous western criminologist and endorsed by police and detective departments, ~ instructions included—learn in one All for $1.50 Send no money. Order today and pay when it comes, SCIENTIFIC DETECTIVE LABORATORIES Dept. 4 Arctic Building, Seattle, Wash, DEAFNESS IS MISERY I_ know because I was Deaf and had Head Noises for over 30 years. My invisible Anti- septic Ear Drums restored my hearing and stopped Head Noises, and will do it for you. They are Tiny Megaphones. Complete evening. by Catarrh or by Perforated, Partially or Wholly Destroyed Natural Drums. to take out. Are ‘‘Unseen Comforts.” Inex- pensive. Write for Booklet and my sworn statement of how I recovered my hearing. A. 0. LEONARD. Suite 301, 70 5th Ave.. New York SELL BY MAIL Mail Order Men, send for our. Dollar Ciecular Service. Circulars with your imprint fur- ished at fourth original cost. Make 92 cts. profit en each dollar order. Add our service to your regular line and watch profits grow. PARTICULARS FREE! D. 1. ELFCO, 525 $. Dearborn, Chicage PRINTING offers Big PROFITS wages are now s0 high you cal. make big money in spare time with one of our printing outfits, No experience necessary. Out “2 instruction book makes every- thing easy. Presses $12 up. Pay for themselvés in.a short Write today for catalog pre: type, ink, paper, cards etc, 'T PRESS CO X33 Meriden, Conn. Cannot be seen | when worn. Effective when Deafness is caused . Easy to put in,easy h 4 si +p

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or Wholly — ut in, easy 3." Inex- 1y sworn -aring. New York Re ~ The best stories are Never written ttle Agen pitt ag wonderful short story”? But you didn’t write it, and the inspira- tion was soon forgotten. “Many a story banged off hot oa my Corona ina front-line dugout would never have been written if I had waited to reach a spot of greater convenience.’’ — Louis R. Freeman, War Correspondent, Explorer, Traveler. e * + * * The advantage of owning a Portable Corona is that you can write your best thoughts as they come to you, any- where, any time—and that’s the secret of successful writing! The newest Corona (Model Four) has the standard keyboard used in offices everywhere. Corona Four costs only $60. Easy terms if desired. Look for Corona in your phone book or write Corona Typewriter Co., Inc., 112 Main St., Groton, N. Y. fits Grid Leak any Mounting FRESHMAN PLUNGER TYPE VARIABLE GRID LEAK was designed especially for the non-tech- nical set owner who can replace in an in- stant the fixed grid leak with this new, efficient cartridge type Variable Grid Leak: without requiring the change of a single wire. © At your dealer or by mail post- paid. Write for free catalogue. EO lh Buying Radio & Tool Equipment Take the Advice of Engineers Write to the Popular Science ‘Institute of Standards for list of tested and approved Products. See page 21. _ POPULAR SCIENCE MONTHLY Giant Engines Point to New Era in Transportation (Continued from page 25) hour, and its maximum speed 35 miles an hour. One of the unique features of this great electric motive unit is that it carries its own converter station. This eliminates establishment of sub-stations along the route, a practice at present general in railroad electrification. Through a regen- erative braking system the Ford locomo- tive will have the ability to develop elec- tric energy at any speed from the maxi- mum to practically a standstill. The voltage adopted for the Detroit, Toledo & Ironton electrification is 22,000 volts, 25 cycles, alternating current, which is a trolley voltage twice as high as any previously used in this country. There are other recent developments, however, in other than the electric field. I have already mentioned the announce- ment by Samuel M. Vauclain, of the Baldwin Locomotive Works. The Diesel- electric locomotive to which he referred is, he admits, an experiment, but it may develop into a satisfactory type for long hauls through stretches of country with- out water, or through sections where oil is the only easily available fuel. The motor is of the inverted V-type. with the crankcase above and _ the cylinders projecting down and to each side. HIS Diesel locomotive, however, is not the only new development in this field. Reports from England tell us of a trial carried out with a Diesel locomotive on the London & Northeastern Railway. In Germany Diesel locomotives are being produced at Augsburg, and in Russia some 1200-horsepower engines are being supplied to the Russian State Railways. Perhaps the most extraordinary of the new developments, in appearance at least, is the turbo-locomotive, which was de- scribed recently before the American Society of Mechanical Engineers. This, of course, is neither electric- nor Diesel- powered, but is driven by steam. Where other steam locomotives are of the recip- rocating type, this new one is driven by turbines. The advantages claimed for the new turbine locomotive are economy in fuel, low water consumption (the exhaust steam is condensed so that the water is used over and over), and smooth running due to the absence of reciprocating parts. This locomotive is of 1000-horsepower, but a 2000-horsepower machine recently was completed by the Krupp works in Germany and studies and designs have already been made of locomotives of 5000 horsepower. The Krupp’s locomotive, aa odd-looking monster pictured on the cover of this issue, is reported to develop greatly increased hauling power with a saving of 20 per cent in coal over the ordinary reciprocating type. It is possible that the turbo-locomotive may stem the tide that is flowing against steam locomotives, yet railroad men the world over recognize that the steam loco- motive must be improved greatly or it must give way before the advance of other types. r{S] This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21. Quickest and easiest way to fix punctures - So simple a boy can do it Just clamp on a Patch-&-Heat Unit and light the fuel it contains. It’s all ready to use anywhere, simple as a cartridge for a gun. No gasoline—no cement—even the raw rubber is cut to size. Will not loosen or come off. The re- pair is permanent because it’s heat-vulcanized. Nearly three million motorists always carry a 5-Minute Vulcan- izer because there are a great many times while on the road that you are compelled to repair a tube, even though you carry a spare. It’s the easiest, quickest, surest method. Get a Shaler to- day. You may need it tomorrow. Complete outfit — $1.50 — in- cludes Vulcanizer and 12 Patch- &-Heat Units (6 round for punctures and 6 oblong for cuts). Extra Units cost only 75c a dozen. Slightly higher in Canada and far west. All auto accessory dealers sell it. C. A. SHALER CO. Waupun, Wis. 2101 Fourth Street

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1-C:8. MACHINE SHOP HANDBOOK MACHINE SHOP HANDBOOK 335 Pages —282 Illustrations HIS I. C. S. Macuine Suop Price only

HANDBOOK is a_ wonderful bargain at $1. Contains more common sense, practical informa- tion than any other book of its kind ever published. Will help you to get a better job and a bigger salary. Contents: Useful tables, mensuration, trigonometry, properties of. materials, drilling, reaming, tapping and threading, lathe work, threads and thread cutting, measuring and testing, milling-machine work, indexing, helixes and spirals, _— work, gearing, planer work, shaper work, slotter ph broaching, grinding and polishing and lapping, jigs an fixtures, punch and press work, die casting, gauges, microm- eters and vernier instruments, lubricants, temperature indicators, metals, heat treat- ment, chilled iron, welding and brazing and soldering, coating, protecting, filing, stock estimating, etc. Just write your name and address on the coupon printed below—enclose the necessary amount of money—and we'll send this 335-page Machine Shop Handbook or any other books you want by return mail. Money back if not satisfied. aietecienieeienbatenionteneatenteetenten International Correspondence Schools Box 7649-D, Scranton, Penna. I am enclosing ..-.---, for which please send me the books I have checked below— O Machine Shop Handbook—335 pages, $1.00 0) Patternmaking—420 pages - 3. O Foundry Work—568 pages - - - - 4.00 0) Lathe Work—312 pages - J 0 Gauges, Jigs, Dies, Tempering, Heat Treat- ment—347 pages - 0 a Boring, Bench Work, Erecting— pages - C Automobile Handbook—345 pages - O Electricity Handbook—414 pages - O Chemistry Handbook—348 pages - 0 Pharmacy Handbook—324 pages - Oj Traffic Handbook—386 pages - - 0 Radio Handbook—514 pages - - - 0 Mechanic’s Handbook—330 pages - O Building Trades Handbook—409 pages O Advertising Handbook—445 pages’ - O Salesman’s Handbook—352 pages - O Civil Engineer’s Handbook—411 pages Oj Steam Engineer’s Handbook—298 pages oe IE ncigieiGieines dennis eeintes airmen ears

Easyto inate Cartoons When Shown in the RIGHT WAY Some of the cleverest cartoonists and comic artists learned how to draw in their spare time by followin Cartoonist Evans’ Simple 4) Easy. to Learn Meth tow and are now MAKING GOO EY. Send one of your drawings, and let Mow, eens as Ni you have ability and receive the Portfolio of Cartoons and full details about the course. It is not expensive. THE W. L. EVANS SCHOOL OF CARTOONING 825 Leader Building Cleveland, Ohio POPULAR SCIENCE MONTHLY

in Sunshine (Continued from page 37) not have the treatment, and twice as many of the eggs hatched. Doctor H. D. Goodale of Williamstown, Mass., has built the first sun porch equipped with mercury vapor lamps to provide his pedigreed chickens with ultra-violet light on cloudy days as well as bright ones. Young chickens given baths of the light in an experiment by Dr. William T. Bovie of Harvard University and President C. C. Little of the University of Maine, weighed five times as much as others of the same age raised under natural sun- light filtered through window glass. Manufacturers of automobiles have seized upon ultra-violet light to test body fabrics and finishes. A few hours of exposure of upholstery fabrics, top ma- terials, and paints under ultra-violet rays were found equal to many months of natural weathering. Pigments, the coloring matter in paint, are faded and discolored by the ultra- violet part. of sunlight. One pigment, lithopone, much used in white paints, sometimes turns black after exposure to sunlight. Tests under ultra-violet light enable paint manufacturers, it is said, to tell in a few hours just how long their color schemes will remain attractive. The light has been used, also, to age painting materials and to dry varnish on auto- mobiles. Ultra-violet light penetrates water, so that it can be used to test materials, paint, and varnish, immersed in a bath. The effect of the light under varying weather conditions can thus be studied. Ultra-violet light streaming on a var- nished surface in water, shows the effect of sunlight on a car left out of doors all night and covered with dew or rain. ye experiments have shown that exposure to ultra-violet light stimu- lates plant growth. Several varieties of flowers and vegetables were found to grow twice as fast when artificial light was ap- plied nine hoursa day as undernormalcon- ditions. In Hawaii ultra-violet radiation was tried on sugar-cane, pineapples, and bananas. The fruits ripened more quickly when exposed to the rays, and it was esti- mated that sugar-cane could be harvested at the end of 12 months, were ultra-violet light used, instead of the 20 months nor- mally required to reach maturity. Indications point to a sunlight age, our crop production speeded up by floods of ultra-violet light on fields at night and in cloudy weather; vegetable markets and ice-boxes drenched with the light, making our foods more healthful; quartz windows in our homes and office buildings to take full advantage of ultra-violet light sup- plied us freely by the sun; and ultra- violet lamps indoors to use‘on dark days. Winter will be as healthful as summer. We may even direct the light upon our bodies while we are sleeping. We may eat sunshine, drink it, and live in it con- tinuously. Then we may look back with incredulous wonder at people who through centuries ignorantly failed to utilize fully this magical part of sunlight. Magic Cures Found Bi

© This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS.

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‘Wh Buy Safety Razor Blades? New Madden Safety Razor ends all shaving expense. Fast, easy, velvetshaves—new bla unnecessary. Wonder shaving edges thatim- prove with use. Remarkable double-action razor i = - —_ le syn ote, Delighted users y “SAVIN: hayer’ s outfit sent sent en “air “Tai. Don't Te cada oan ree t, write Des n Razor poration, 1819 Broadway, New York, N. id Can.

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. May, 1925 — .. ~ 7 The Newest Contributions to Science (Continued from page 47) ‘american Association for the Study of Goiter, however, this opinion is erroneous. There is just as much goiter, he says, quoting other authorities, along the Atlantic Coast as there is in the Great Lakes region which was regarded as the ‘goiter belt.”” Summarizing recent in- vestigations, he adds that goiter now is be- lieved to be an infectious disease. Only one type, endemic goiter, is due to defi- ciency of iodine. The use of iodine in the treatment of goiter has been found actually harmful in certain cases. Says Fishes Can Smell 1 HAS been believed generally that fishes have no sense of smell, the reason being that smelling is supposed to consist of detecting gaseous substances in the air, a condition impossible to produce in the water. Now, though, Prof. Karl von Frisch, physiologist, of Breslau, Germany, offers the suggestion that fish actually do smell, backing his statement on a series of experiments he performed. When Professor von Frisch placed food in the tank, the fishes found their way to it without delay. When the nose centers of the fish were rendered useless by an operation, however, they could no longer detect food from a distance, though they devoured it with normal appetite when they discovered it. He also ascertained that amphibians use the same organs for detecting food on land as in the water, thus seeming to indicate that their organs of smell worked just as well in water. _What Stammering Costs TAMMERING costs this country $250,000,000 a year, according to Samuel Robbins, director of the Boston Stammerers’ Institute, who bases his esti- mate on the fact that a half million stam- merers earn an average of $10 a week less than those who have no impediment in their speech. This is the more deplor- able, says Mr. Robbins, because usually stammering can be cured. Stammerers, particularly children, says Mr. Robbins, should not associate with those who make fun of their defect, and those who are in daily contact with them should speak carefully and distinctly so that the sufferers may be inspired to emu- late them. Mr. Robbins also makes the astonishing assertion that stammering is contagious, and that one stammering child, unless cured, can pass his habit along to his friends. Million Animals Auto Victims EVERY day of the automobile tourist season, now about to begin, more than 1,000,000 animals are killed by motorists on the 3,000,000 miles of motor highways of the United States, ac- cording to a compilation made by Dr. Dayton Stoner, of the University of Iowa. In a single run of about 200 miles in lowa, Doctor Dayton asserts he found 105 dead animals of 29 different species. In another trip of 632 miles he found 225 animals crushed to death. POPULAR SCIENCE MONTHLY 131 Pep up your set with good tubes “TDIDN’T think that tubes made such a difference—until I changed to MAGNATRONS.”’ That’s what one enthusiastic MAGNATRON user wrote us. You, too, will be pleasantly sur- prised by the way that MAGNA- TRONS “pep” up a set and give it a new lease on life. MAGNATRON DC-199, DC-201A; and DC-199 with large base sell for only $3 each at your dealer's. CONNEWEY ELECTRIC LABS.. 309 Fifth Ave., New York Factories, Hoboken, N. J. ud , : ac : GUARANTEED “Have received more stations with my Miraco than I ever re- ceived with any other set cost- ing $50 or $60 more,” reports fF. J. Brink, Grove,Okla. ‘More than pleased with my Miraco— have 125 stations on my log to wa date.’?—C. Gilland, Franklin, Texas. “‘Best set | ever used. Have heard London and Cali- fornia.’’—C. A. Henry, bank Village, N. Y. “‘When you can’t get a program with the Miraco you need not try any other set. Am getting all over U. S.with mine.’’—J. C.Brown,Albertville, Ala. COAST TO COAST RECEPTION veritied by Miraco osers NORTH DAKOTA HEARS OE O1S HEARS 1. Y. iraco has been working ‘**Believe Miraco best on Mi fine. Have heard fromcoast market. Hear stations all coast. many sta- tions in Canada and —T, G. Anderson, over U.S. AlsoCuba. Hea uba.’’ N.Y. and Cal. most every Turtle night.’’—Mrs. F. K.Proph- e, N. D. et, Pawnee, Ill. eports like these from users in every state prove jiraco Tuned Radio Frequency sets—at rock-bot- ty —have efficiency of sets costing 3 times Made by set ‘actory- built, completely assembied, fac- sorgtest , and guaranteed. Eas lor beginners to operate. Order "MAIL COUPON BEL —_ ELOwW.. ri: offer, latest bulletins, pen A. pap and proof that Radio offers ee ee A Be | MIDWEST 408-F, E. 8th Street, Cincinnati, { ] USER { |] AGENT d free literature, SPECIAL OFFER, and full lars Send free literature. fipeaen a Vern- 4) RADIO CORPORATION Ohio ] .t’s a mighty handy little tool for holding radio panels, boards, or metal pieces while drilling them. It is a portable vise that can be carried around the house or shop, for gluing, sawing and many other jobs. The Jorgensen ‘‘Steel Spindle’’ Hand Screw must not be confused with the ordinary wood spindle hand screw. ~~ adjustable for angle clamping. Send for one, lot of The Jorgensen is rugged, jay, if your dealer cannot supply you, and save yourselfa time and trouble on the next job. Read the coupon Money Refunded if Unsatisfactory ADJUSTABLE CLAMP CO., 212 N. Jefferson St., Chicago a Please send items checked below: 7 Ship by mail, postage prepaid, ONE No. 5-0 i Jorgensen Hand Screw (Length 4 in., Jaw opening 2 in.) for which I enclose $1.00 Ship by mail, postage prepaid, ONE No. O Jor- gensen Hand Screw (Length 8 in., Jaw opening | 44% in.) for which I enclose $1.50. Send latest descriptive bulletins. 3 Money will be refunded if tools are unsatisfactory and are returned within 30 days. Oo a) © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21.

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POPULAR SCIENCE MONTHLY Alice Higgie, a 13-year old Chicago girl, made $75.00 a week in vaudeville last summer. Her mu- sicalact isconstantly in demand for clubs, lodges, hotels, radio studios and private (02 age For a 15 minute act she receives $15.00—a dollar aminute! Read what she says—‘Piayin “ts mu- sical instrument is lots of fun. 1 wish everybody knew how — it is and how quickly you can learn, especi- = wit Aloe Hiei. instruments—they are so easy to play. New Offer Learning to Play Made Easy pw onew furnish free with every Wur- ree " instrument a Special Scholar- ship = a ,netenely famous school of school has taught thou- sands to play by a a enel ie heme study method. Many of its graduates are a professional musicians. you want to play for ees or for ay choose your favorite instrument and send for this New re ean nm below. Warlt ae ree in your own home on an: urlitzer instru- me Easy payments if desired. J Illustrates and describes every known musical instrument—more than ou Free — » Easy Pay- ment i. and | epenel holarship Of- oy No obligation. @) Send this ‘Coupon (f@ | The Rudolph Warlitzer Co., Dept. 1785 Send me your Free be Book on oe instruments. Also our Free Trial, Easy Payment —_ and special Free olarship Offer. No obligation ip Name State. “Copyright 1925, The Rudolph Wurlitser Co. Here Are Correct Answers to Questions on Page 47 1. It jars the optic nerve and this stimu- lates it. The brain is in the habit of receiving from the optic nerve stimuli which it recognizes as light. Accordingly the stimulus caused by a jar of the nerve also impresses the brain as being a light stimulus, and we think we see a flashing light or a lot of them like moving stars. 2. The purpose of the flower is to attract insects. Most plants are green, so the flower is usually of another color in order that it may be more noticeable to the insect in the midst of green leaves. 3. Mainly a difference in the tempera- ture at which they boil. Both of them are made by heating crude mineral oil in a still. The gasoline boils off first and is caught. until the temperature has been raised a good deal more. 4. Probably they are, though we cannot be sure. The growth of mountains is very slow. They are not pushed up sud- denly in some grand cataclysm. They rise little by little, a few inches in a thou- sand years. We know that the Rocky Mountains are fairly new and that they have been rising quite recently, because they are so steep. 5. Because the pigment in the curtain of the eye may fade, in much the same way that dyes fade when they get old or have been exposed for a long time to the light. 6. Most electric wiring consists of at least two wires—one for the electrons to enter on, the other for them to return. If the insulation fails so that the two metallic wires touch, the electrons jump instantly from one to the other, some- times so violently as to burn the wire. 7. The ones that float have had a very fine froth of air beaten into them just as you beat air into cream to make whipped cream. The soap really contains a lot of small air bubbles, far too small, of course, to be visible individually. 8. Because of the fact that water boils always at a certain temperature. The water in the bottom part of the double boiler cannot get any hotter than about 212 degrees. Accordingly the food can- not burn so long as any of the water is left. 9. Notin principle. In both of them an electric vibration is converted into sound by its effect on a small magnet in the tele- phone. But the detailed design of a radio head phone is not tht same as that of an ordinary telephone receiver. The instru- ments are not interchangeable. 10. Worms like to lie on the damp ground. They do not do this at other times when the ground is dry because they do not like to become dry them- selves. 11. Because any mass of matter takes this shape from its own attraction of gravity. If the earth were square and had corners that stuck out, the attraction of gravity of the rest of the earth would pull these corners down to the general level of the surface of a sphere, or close to it. 12. The heart tends to keep time with any strong rhythm. Ordinarily one’s heart beats about 70 times a minute. The rhythm of a fast march is faster than this. So it makes your heart beat a little iaster, the faster heartbeat improves the circulation of your blood, and that makes The kerosene does not boil off ° May, 195 Get Health-Height-Youh A Home GYMNASIUM . Very many human ills are of Spinal ori This great University Invention, The © Therapeutic Couch, Rejuvenates the «cn Stretches and exercises the Spine, Skeleton, Can tilages, Nerves, Arteries, Muscles and Ligan 5 Helps correct Curvatures, Deformities, re: causes of arrested growth, give Height and a Bod: Beautiful. Ask for free book ‘*The Human Body, International Health Devices Corpo ra 246 W. 59th St. Dept. 3 New York one Have You AN INVENTION If so the WORLD PROGRESS will show you how to Protect and Profit From Your Ideas Sample copy free. One year’s subscription Send for free book, " *. “WHAT TO INVENT” containing Suggestions to Inventors ag ig Inventions Needed, We invite manufacturers to address us regarding inventions they want, WORLD PROGRESS Pus. o~ INC, shington, D.¢ Room 202 Victor Bidg. ADDING MACHINES ton, Wales ‘and all ctendond makes often at less than one-third \ regular priest ales .— and styles oh >? A-1 condition.” built by enpieia SOLD ON IN You can bu ay a SAL Pay He bad low as down. poe ean «, wal customers. ite ‘REE models and bar in ain pres i let : SeLIABLE ADDING iQ MACHINE © CORP.” ots ae ~ F E wit 3 ft. Telescope FRE E° Pe acts mil ine ey were close; see Moon never before. ¥ iE: pow on fretet care mile awa: SondNo finer pielgt 1 Strap pay Postman only $1.85 plus pennies FERRY & CO., 3224 ed St.. Dept. 1785, AGENTS 500% PROFIT GENUINE GOLD LEAF LETTERS | Guaranteed to never tarnish. Anyone can put them on stores and office windows, Enormous demand, large profits, yee says: smallest day $28.70. R.L. Reel made $920 intwo months. Write today for free sample and liberal offer to general agents, METALLIC LETTER CO., 433A N. Clark Street, Chicago Buy Sport Bodies for Fords At ee Prices! This Model in Grey Prime $3,9:5° Write for circular B-2,0f other models. AURORA, ILL. POTENTIOMETERS FOR DEPENDABILITY am pn 4 te offers big opportunities for men thod prepares quic' 4 a [a piel tep fre vfrom amateur to M Te A work, ide while Ie pA ny FREE Ero: sey ra and free. Won a for f fon informa Find about the man ies in the differ- ent branches of bane ee adbew yeue you feel more active. INTERNATIONAL STUDIOS, Inc. 3€01 MichigenAve.,Oept. 1365 Chicago,U.S.A> © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21. An Uncrowded Field § | and how youcan qualify.

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pinal OFigin — The rises the body— celeton, Con. 1 Liga ties, ren and Body man 3 ; Orporation York City ——<—— NTION? S will ur Ideas ription 406, NT” ‘ tors as to nufacturers they want,

ts, Paul Clark L. Reel oday for free 1eral agents, rk Street, Chicago

May, 1925

How to Wind Your Own Radio Coils (Continued from page 76) that is perfectly smooth and even, unless, py accident, a kink causes a_short- circuited turn. If that happens, the coil js absolutely worthless for radio work. It will tune as broad as a barn docr and the signal strength will be very poor. This brings us to the matter of how to wind coils so that they will look so smooth and even that the casual observer will take them for factory-wound coils. Like everything else, it is really simple when you know how. Of course, you must have good wire to start with, and it js much better to buy it on spools that are wound smoothly than on spools wound at random. ’ The next problem is how to wind the coil form without kinks. The simplest and best way, short of a winding machine, is the method shown in the illustration. RILL two small holes about one- fourth inch apart at the point where you want the winding to start, and pass the end of the wire through and back as shown in the tubing illustrated. Next, persuade some member of the family to hold the spool of wire with just sufficient pressure so that you can turn the spool and wind the wire on the coil form by turning the latter slowly and carefully. Naturally it is a slow process, but it turns out good-looking coils. With a little practice you will find that you can wind a coil of 50 turns or so in a very few minutes. Of late, many radio writers are recom- mending double silk-covered wire instead of double cotton-covered wire. There is a good reason for this. Silk does not absorb moisture nearly as much as does cotton, and moisture in a coil will have nearly as bad an effect as a short-circuited turn of wire. Cotton insulation is practi- cally as good as silk if it is absolutely dry, but, unfortunately, when there is much moisture in the air, the cotton-insulated coil promptly falls off in efficiency. HE kind of insulation used has an influence on the number of turns of wire needed. Double silk insulation is thinner than the usual double cotton covering and, consequently, you will find it necessary to increase the number of turns of wire if you use cotton-covered when silk is specified. Similarly, you must decrease the number of turns if you wind coils with silk-covered wire when the receiver has been designed for cotton- covered. Another important matter is that of using shellac, collodion, or other insulating varnish. The object of.such treatment is to keep out the moisture and to prevent the wire from coming loose on the form. So far as the radio fan is concerned, there is just one good rule and that is to stick to double silk-covered wire properly wound on the form, and avoid all forms of varnish or other “‘dope”’ for coils.

based on laboratory tests and con- taining hints that will aid you in effi- hext month’s issue.

POPULAR SCIENCE MONTHLY

eee MER article by Mr. Senauke cient radio construction, will appear in

Only greatly impaired. You will find that nearly all sets made—in fact over 90% of them—are equipped with Dubilier Micadons. This is the name by which all Dubilier fixed con- densers are known. Be sure your set—whether you buy it or build it—is equipped with Micadons. They are made by specialists. Dubilier specialists can make good fixed condensers Sips small fixed condensers in your radio set are there to help you get clear reception. If these little condensers are not made most accurately the quality of reception you get—even though your set may be excellent in all other respects — will be 133

CONDENSER AND RADIO CORPORATION

250 4th Avenue, New York City

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: FRANKLIN INSTITUTE, Dept. B280, ROCHESTER, N.Y. $1900 to $2700 Year . Sir: I want to travel. Send me without charge (1) Speci- 2 men Railway Postal Clerk Examination questions. (2) List e of other U.S. Government jobs now open to men and women. e Address r1S] This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21. # (3) Send free sample coaching lessons.

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ele | s- 6) si Gs | eis © ami s/c aums ie! 6: POPULAR SCIENCE MONTHLY \\ J 0c. ame 2] = y S NX Do You Hear Each Instrument Distinctly ? With the unique design of Rauland-Lyric comes a peculiar excellence. There is brought an abil- OI 9 rae a a ity to bring before you, asanotedcritic remarked, “the very personality of each artist’, as he ex- plores the resources of his instrument. Such a qual- ity, indeed, as to render insignificant, in any radio set, the added cost of Rauland-Lyric Amplifica- tion. Rauland-Lyric is a laboratory- grade audio transformer de- signed especially for music lovers. The price is nine dollars. Descriptive circular with am- plification curve will be mailed on request. All-American Radio Corporation, 2668 Coyne St., Chicago. : TRANSFORMER The Choice of Noted Music Critics a ae ae a ae | terminal of the socket G. The Most Up-to-Date One-Tube Set (Continued from page 75) were bent up out of strip brass one- sixteenth inch thick and one-fourth inch wide. Do not make the brackets out of thick, wide brass or other metal, as it is desirable to have as little metal as possible near the coils. If you prefer woodwork to metalwork, make wooden brackets instead of the brass ones shown. They will be equally efficient. Be sure to mount the socket G so that the filament terminals will be nearest the front panel L. You now are ready to begin wiring and you can follow either the diagram shown in Fig. 2 or that shown in Fig. 4. Which- ever one you use, be sure to mark over the line of each wire with a heavy pencil as soon as you connect the wire that it represents in the receiver. This method may save you much time in looking for trouble due to making wrong connections or leaving out a wire or two. ie ALWAYS is well to get the filament wiring done first and in this receiver it is extremely simple. First run a wire from binding post No. 3 over to one terminal of switch K. From the other terminal of switch K run a wire to the nearest binding post of rheostat H and then connect the remaining terminal of rheostat H with the filament binding post of socket G, which is nearest con- denser E. Do not worry over the fact that this terminal on the socket probably will be marked “+FIL.” Plus and minus markings on filament terminals mean nothing anyway. Next run a wire from binding post No. 2 over to the remaining filament terminal of socket G, and from this wire run a branch to the two ends of coils A and B, which are nearest to each other. Also connect binding posts Nos. 4 and 5 with binding post No. 2, and then run a branch from the wire connected with this post underneath the coils to the far end of coil C and another one to the rotary plate connection of condenser D. This completes the filament wiring and the grounded sides of all three circuits. Now connect a wire from the remaining terminal of coil A with binding post No. 1, which completes the antenna circuit. ON side of the grid condenser F should be connected with the grid In the receiver shown in the illustrations, a soldering lug was soldered to the grid condenser and the hole in the lug slipped over the binding-post screw of the socket, which makes as short a connection as it is pos- sible to obtain. Complete the grid side of the secondary circuit by running a wire from the stationary plates of con- denser D over to the terminal of the coil B nearest to coil C, and solder the wire also to the other terminal of grid con- denser F. Next connect a wire from binding post No. 6 to the lower lug of jack J and run a wire from the stationary plates of con- denser E across to top lug of jack J to the plate terminal of socket G. Solder at both points. These last two wires are shown clearly in Fig. 7.. Now connect the rotary plates of condenser E with the terminal of coil C that is nearest to eojj B. This completes the wiring. You now are ready to put the receiver into operation, assuming, of course, that you already have constructed the ap. tenna. FIRST connect the wire from the ap. tenna to binding post No. 1. Runa wire from binding post No. 2 to the nearest water-pipe. Be sure to scrape the pipe bright with a knife or sandpaper and make the connection with the pipe with a ground clamp or, lacking this, wind 12 or 15 turns of bare wire as tightly as possible around the polished portion of the pipe. Connect the A battery, either storage or dry cell, depending on the type of tube you are using, with binding posts Nos. 3 and 4, being sure to connect the minus terminal of the battery to binding .post No. 3 and the positive terminal with binding post No. 4. Next connect the B battery—which should be of 45 volts for any of the standard tubes— with binding posts Nos. 5and6. Besure that the positive terminal of the battery! is connected with binding post No. 6. Now snap the grid leak J into place in: the clip on grid condenser F.. Make sure that the rheostat H is turned all the way to the left, place the tube in the socket carefully, and plug the phones into jack J. 7 You now are all ready to tune in the broadcasting stations provided they are transmitting. First turn the dial on the shaft of condenser D around to 100 and. do the same for the other dial. The dials, by the way, should be fastened to the shafts of the condensers with the 100 division at the top when the condenser plates are fully engaged with each other. Snap on the filament switch K and turn the rheostat H slowly to the right’ until a click, accompanied by a slight hissing, is heard in the head phones. This’ click probably will be heard before the rheostat is turned more than halfway. There is a slight click when the rheostat first starts to turn and makes contact with the resistance wire, but the click indicating that the tube is oscillating is the one you should listen for. en the click is heard, you are ready to tune in. Turn dial £ back toward O until the oscillations stop, then turn dial D slowly until you heara signal. Readjust the rheostat H until the signal is coming in as loud as possible, but do not turn the rheostat farther than necessary to attain maximum signal strength, as such a procedure will. cut down the life of the tube and use up the batteries needlessly. the may whe and osci opel osci you: and dec wou reve you reve out Cn vice nect lute (Continued on page 135) © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS, See page 21.

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ick J to Solder at vires are connect with the it to coil receiver rse, that the an. _ the an. - Runa 2 to the O scrape andpaper the pipe ing this, is tightly ortion of r storage the type binding > connect ittery to positive 4. Next should be d tubes— Besure e battery! No. 6.0 > place in: ". Make ed all the ye in the e phones ne in the they are ial on the | » » 100 and. ‘ial. The stened to h the 100 condenser ach other. h K and. the right - a slight nes. This vefore the halfway. e rheostat s contact the click illating is , you are n dial E ions stop, ‘ou hear @ > H until S possible, rther than msi » will. cut ise up the May, 1925 — —t—‘i=tsOs The Most Up-to-Date One-Tube Set (Continued from page 134) After the rheostat is set properly, turn the right-hand dial until the signal attains maximum loudness. You will find that when dial FE is turned too far, the signal will be broken up suddenly by a clicking and rushing sound. This indicates tube gscillation and you should be sure to operate your receiver at a point below gscillation so as not to radiate and spoil our neighbor’s reception. If the receiver seems dead and lifeless and the weak signals you hear are decreased in strength when you turn dial E, the chances are that you have wound coil C in the wrong direction or reversed the connections to this coil. If you find that the coil is wound in the wrong direction, you can rewind it or reverse the connections. There is just one other point to watch out for. Do not mistake the end of coil C nearest coil B for the end of coil B, and vice versa. Such a change in the con- nections will render the receiver abso- lutely inoperative. Things I Have Learned About Your Car (Continued from page 72) Manufacturers advise not to drive a new car faster than from 20 to 25 miles an hour for the first 1000 miles. I’d say don’t do it for the firs 2000 miles. You’ll have plenty of chance to try your car out after that, and if you curb your and more efficient vehicle. A man who bought a new model of a popular make of car the first of this year has been running between my garage and the service station of the manufacturer ever since, because he drove it too hard when he first had it. The bearings, of course; were excessively tight, and when he drove at high speed, naturally the bearings became “‘starved”’ for oil. Even- tually they gave way, the ‘“‘stiffness” disappeared from the car and the owner went on his way happily. But his happiness was short-lived, for he has had nothing but trouble ever since. The bearings are pitted, and almost daily some new “defect” discloses itself. These are only a few instances from thousands that have come under my attention of the harm done to cars and the unnecessary expense caused by the ignorance and carelessness of owners. Automobile engineering has advanced wonderfully since the days when a motor- trip, no matter how short, was a hazard- ous adventure, but engineers are not yet able to produce a car that is proof against flagrant misuse. They can and do pro- duce cars, however, that ought to last a great deal longer and cost considerably less for upkeep. Gas, oil, and grease, water for the cooling system, frequent inspection of the battery, the ignition system, and the tires and an occasional check up of the carburetor adjustment—if intelligent care is taken in these particulars, necessity for repairs is not likely to arise at all. a impatience you’ll find you have a faster | POPULAR SCIENCE MONTHLY Balkite Battery Charger. Charges 6 volt “‘A” storage batteries. Price $19.50 West of Rockies $20 In Canada $27.50 unfailing power supply Hereat last is an unfailing power sup- ply for your radio set. Balkite Radio Power Units furnish constant uni- form voltage to both “A” and “B” cir- cuits and give your set greater clarity, power and distance. The Balkite Bat- tery Charger keeps your “A” storage FANSTEEL Balkite “‘B”—re- places ““B” batter- ies and dry cells. Operates from light socket. Price $55 In Canada $75 for both circuits battery charged. Balkite “B” replaces “B” batteries entirely and furnishes plate current from the light socket. Both are based on the same principle, are entirely noiseless, and are guaran- teed to give satisfaction. Sold by lead- ing radio dealers everywhere. Radio - Balkite Pover Units BALKITE BATTERY CHARGER — BALKITE “B” PLATE CURRENT SUPPLY Manufactured by FANSTEEL PRODUCTS CO., Inc., North Chicago, Iilinois Uniformity Guaranteed! One ‘reason that leading builders of fine sets use more a Thordarsons than all competitive transformers combined is HARTMAN AUDIOLA GLOBE EAGLE anp MANY OTHERS USE THORDARSONS ! Shey SaY~ THEY SAY OF THE AUDIOLA “SUPER”: “Absolute elimination of distortiédn and foreign noises is attained . . . One stage of straight audio coupled with a stage of push-pull audio gives the volume of three audio stages with the clearness and distinctness of headset reproduction.” Audiola amplifies with Thordarsons! Thordarson Interstage Power Amplifying Transformer, $8. © for latest Hook-up bulletins—free! ecause Thordarsons run absolutely alike, absolutely uniform; always ‘‘match up’’ perfectly; always amplify evenly over the entire musical scale. The following statement was made recently by a prom- inent set maker (name on request): ‘Any radio manu- facturer who is sincerely desirous of producing an in- strument of the volume necessary and of a tone superior to anything else on the market, must be absolutely forced to use Thordarson transformers sooner or later.’’ the lead of the leaders—build or replace with Thordarsons. eR, : They are unconditionally guaranteed. supply you. THORDARSON ELECTRIC MANUFACTURING CO. ‘WORLDS OLDEST AND LARGEST EXCLUSIVE TRANSFORMER MAKERS Follow E Any store can, If dealer is sold out, order from us. Chicago, U.S.A. Australian Representatives: Walnart Electric Mfg, Co., Ltd., Sydney. Unconditionally Guaranteed HORDARSON AMPLIFYING TRANSFORMERS Standard on the majority of quality sets TYPES AND PRICES: Thordarson Transformers are now to be had in three ratios: 2:1, $5; 34-1, $4; 6-1, $4.50. Thordarson Power Amplifying Transformers are $13 the pair. ‘‘Super’’ Audio Frequency Write THEY SAY OF THE OZARKA: “Ordinarily a three step amplifier is noisy but we can guarantee the OZARKA to give the greatest volume possible with a tone reproduction that is satisfactory to everyone.”’ Ozarka amplifies with Thordarsons! THEY SAY OF THE MASTER: “The parts used are the best. Shielded, dis- tortionless transformers insure perfect repro- duction, unusual volume and tone.”’ Master amplifies with Thordarsons! THEY SAY OF THE HARTMAN: “The range, selectivity, volume, clarity and freedom from noises is remarkable.” Hartman amplifies with Thordarsons! r1S] This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21.

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POPULAR SCIENCE MONTHLY ae for the Checkered Box Brass Mises _ Soldered Joints—Grounded Rotor Are Standard Features of the Bradleydenser The Bradleydenser is a low-loss condenser with many dis- tinctive features that insure long life and high efficiency. For instance, the brass stator and rotor plates are soldered at all joints. The plates cannot become loose, corrode at the joints or work out of alignment. The rotor is mounted on a long sleeve bearing that supports the rotor plates without the use of an outer end-plate. Therefore, the di-electric material is reduced to two small buttons. This means low loss and sharp tuning. The stator plates are protected with a dust cap that can be detached without tools. The minimum capacity is extremely low, and body capacity effects are greatly reduced. The entire design makes for the highest efficiency in radio receivers. © Use the a Bradleydenser Build for Efficiency Electric. a. Apparatus 293 Greenfield Ave. Milwaukee, Wis. Send for the latest in- This filter tuner with resistance -coupled audio amplifier is equipped with Bradley- densers. The tuning is sharp and selective. formation on the Brad- leydenser. It will pay you to know about this remarkable low-loss condenser before plan- ning your next radioset. © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 21. ART COLOR PRINTING CO., NEW YORK

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