Popular Science Monthly 1920-05: Vol 96 Iss 5

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You can learn a lot from car owners about tires OMETIMES you find a car owner who also rides a bicycle. Notice how anxious he is to have the right kind of bicycle tires. As a car owner he knows that he doesn’t have to worry about wear or meney s worth, once he sees the name “U.S.” on any tire—for it tells him that the great United States Rubber Company, oldest in the world, with its high reputation for high value tires, is back of his purchase. You can be sure of your tires, just the same way the car owner is, if you pick your tires as he does. All the resources, men and equipment, of the world-wide organization that builds U. S. Automobile Tires and U. S. Truck Tires are behind U. S. Bicycle Tires. Nine different styles, both clincher and single tube—choose the tread that suits you best: U. S. Cords, U. S. Chain Tread, Giant Stud, G&J Corru- gated, G&J Chain Tread, G&J Her- ringbone, Heavy Service, Overland Thornproof and Nonpareil. Find the dealer who sells good bicycles and U. S. Bicycle Tires—the two go together. Send for the fascinating, well-illustrated book, “Rubber—A Wonder Story.” Address U. S. Rubber Company, Bicycle Tire Division, New York. United States Tires United States °© Rubber Company

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Popular Science Monthly May, 1920; Volume 96, No. 5 25 Cents a Copy; $3 a Year Waldemar Kaempffert, Editor —— Published in New York City at 225 West Thirty-ninth Street Look Out for a Crash When the IVE thousand tons of human flesh and blood! Such is the audience in the Yale Bowl] when it is filled to the limit. Perhaps you have never thought of a crowd in these terms. But the engineer who designs a grand stand, for example, has to consider not only the dead weight of the crowd that will sit on it, but the possibility of other forces that the crowd may develop. Yale students, in their “rush,” form sides and line up in two groups ten men abreast and thirty deep. The men stand > in close formation, with their arms locked before them. These two masses face each other, and at a signal slowly move for- ward. . The force thus developed is amazing. Not infrequently ribs are broken -by the slow pres- sure, and heavy men are lifted bodily above the heads of the crowd. Similar conditions must arise, for example, in a theater in case of an alarm of fire, when people press against one another in their rush for the doors. A simple calculation shows the intensity of the pres- sure that may thus be developed. The push or pull that a man can exert horizontally, when standing on a horizontal floor surface, de- pends on the coefficient of friction of the soles of his feet against the floor. As an approximate and con- servative value of this co- efficient we may take the figure .2, orone fifth. This means that a man can push or pull horizontally, on a Professor Tilden found that the act of standing up from a_ crouching position on.a platform added over 60 per cent to the man’s weight Crowd Gets, Up By Alfred J. Lotka ~ level floor, with a force of about one fifth of his weight, say about 30 pounds. If all the members of a crowd twenty rows deep are pushing to- ward a narrow door and against the walls on each side of it, persons standing against the wall may have to bear a crushing pressure of something like 600 pounds each. In designing struc- tures that are liable to be subjected to stresses from crowds, engineers -commonly figure on a dead load of about. 100 pounds a square foot. But this assumes: the crowd to be sitting or standing still. The situation may be very different if the crowd is Ye age SRE The forces developed in a rush are moving. If the motion is itregular the matter may not be very serious. But watch the fans at a football or baseball game. A brilliant tackle or a spectacular catch, and the whole crowd rise to their feet as one’ man. . The effect of such concerted action may. be serious. A systematic investigation of some of the stresses produced by move- ments of live loads was carried out some time ago by Professor C. J. Tilden of Johns Hopkins University; the results were published-in the Pro- ceedings of the American Society of Civil Engineers. Professor Tilden placed’ a man on the platform of a scale,-and moved the counterpoise until: it registered some 40 or 50 pounds in excess of his weight. ._ The subject. of the experi- ment was asked to crouch down and then suddenly to rise. This was repeated a number of times, with .the eounterpoise each time in a different position, until the highest point was.fotind at which the = . ~~ Fan Pn. Ribs are -broken by the slow-pressure, and heavy men are lifted bodily above the heads of the crowd 21

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pga ema sgn ss Pa raiceTAS Popular Science Monthly stand? counterpoise was just lifted by the effect of the man’s movement. It was found that the act of standing up from a crouching position added 67 per cent to the man’s weight. Getting up from a chair added 79 per cent. A sudden straightening out of the body after standing with slightly bent knees, ° and a simultaneous throwing down of the arms, so as to obtain a maximum effect, added no less than 174 per cent to the dead weight. Professor Tilden also investigated the horizontal thrust, which may be produced, for example, by a man getting up from a chair. He esti- mated that the ratio of the move- ments of the center of gravity in horizontal and in vertical direction corresponds approximately to the ratio of the intensities of the respective forces. His conclusion is that a man, in rising suddenly from his seat, may exert a horizontal force of about one half his weight, say about 70 pounds. His method of determining the center of gravity of a man in different positions is interesting. The man is supported at two points, of which one rests on the platform of one scale, the other on that of a second scale. A When the crowd gets up and stretches before the seventh in- ning, or when it rises to its feet and yells when the touchdown is made at the football game, what is the effect on the grand Professor Tilden, of Johns Hopkins University, who vertical line through the center of gravity (centroidal line) then divides the straight line joining the two points of support, in inverse ratio to the weights indicated by the two scales. By taking two such observations in different positions, the center of gravity is located as the intersection of two centroidal lines. For the erect position one centroidal line can be assumed, without special experiment, to go straight down the vertical axis of the body. Only one more deter- mination is needed in this case, with the man lying across the two scales. Suppose a number of people are watching a boat race from a bridge. They view the shells approaching from one side, and as the crews pass under the bridge the spectators rush across to see the finish on the other side. What effect will this have on the structure? If a man weighing 160 pounds, running across the bridge, gets up his maximum speed of 12 feet a second in a distance of 2 or 3 feet, he exerts upon the bridge a horizontal force of 150 pounds, or in other words practically his own weight. If he is brought to an abrupt halt at the end of his run by striking against the side of the 22 recently conducted a systematic investigation along this line, shows that a man, in rising suddenly from his seat, may exert a horizontal force of about one half his weight. We wonder if grand stand designers take this into consideration bridge, the impact may put a lateral pressure of several hundred pounds upon the wall or railing. Effects of this kind might exceed the allowance ordinarily made for wind pressure. What is the horizontal force exerted by a man walking? An analysis of a series of instantaneous photographs of a pedestrian shows that in walking the velocity ig not uniform, but fluctuates. It is highest just before the forward foot is set down, and lowest just as the foot in the rear is lifted off the ground. As the velocity changes there must be corresponding changes in acceleration, and hence in the force exerted. Professor Tilden has computed that the maximum horizontal force that a man weighing 160 pounds exerts against the ground in walking may rise to about 80 or 90 pounds. One would almost expect that slipping would occur before such a force as this were reached. But it must be borne in mind that the pressure of the foot in contact with the ground will for a moment exceed the man’s weight—just as the man, suddenly rising from a crouching position on the balance scale, will momentarily register more than his actual weight. ——-— Me

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——8-—— May, 1920 Drop a cork in fresh water, and very little of it will sink below the sur- face—to be exact, just twenty-four per cent of it will go under. Cork is very buoyant— much more so than Saturn, for instance But Saturn has the honor of being more buoyant than any of its fellow planets. It is the only one that would float if they were all thrown into a great body of water. Twenty-eight per cent of it would stay above water. Saturn’s lightness as com- pared with its great size has led astronomers to believe that it is not solid but merely a vast envelope of clouds sur- rounding a heated interior. Saturn’s rings, too, are cloud- like, and so thin that they disappear when seen edgewise You may not'think so, but a human being, breathing prop- erly, can walk into fresh water up to his nose and then find himself floating; ~~ He’s not so buoyant as Saturn, but at least eleven ‘per cent of him will bob above water. If you: have not yet -learned how to float on your back, bear this in mind: only eleven per cent of your body will re- main above water. If you try to keep your whole head above water, you. will find it won't work. Just your eyes, nose, mouth, and chin should emerge Saturn—It Will Not Sink HOULD our eight planets sud- denly be dropped into a great body of water, all except Saturn would sink like stones. Saturn, on the contrary, would float gracefully on the surface—rings and all—like a cake of much advertised soap. That is because Saturn possesses only about three quarters of the density of water. The other seven— Mercury, Venus, Earth, Mars, Jupiter, Uranus, and Neptune—are all denser than water. Our earth leads them all, being about five times as dense. Mercury, Venus, and Mars follow close behind. But the larger, distant planets are far less dense than the nearer, smaller ones. Jupiter is only about as dense as the sun, and Uranus and Neptune have but one fifth of our earth’s solidity. Were our earth suddenly to possess the consistency of Saturn, and were we to retain our present densities, we would promptly sink in and disappear beneath the surface—that is, if the earth were in a fluid condition. [If it still remained solid we would not sink beneath the surface, but would feel as if we were walking on something having the density of cherry wood. Saturn is: very beautiful. When seen through the telescope it has a yellowish color and its three strange 23 rings are quite visible. It is seven hundred and sixty times as large as the earth in volume, and it travels very slowly around the sun. The earth’s speed is eighteen and one half miles a second, whereas Saturn makes only six miles a second. That is one reason why it takes Saturn so long to revolve around the sun. Instead of doing it in a year, as we do, Saturn makes a revolution in thirty years. In the course of each revolution Saturn’s rings appear and disappear from time to time. They are very thin, and when they are in the same plane with our line of vision we cannot see them at all. RE IEE

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eet x % HI Hi 2 RT RT An Excavator that Walked Across a Stream \ THEN it became necessary to cross the 800-foot span of the Rio Grande river, a huge 75-ton excavator took the ford and crawled with its caterpillar tractor straight across the swiftly flowing stream. Quicksand lurked in the treach- erous bottom, and at any moment the great machine might have been engulfed, had not the engineers carefully considered this problem. They built an arrangement of timbers, guyed and made fast at the points of crossing the channel, and along this temporary track the caterpillar crawled. The hazardous trip was made from the west side of the Rio Grande at a place called Mesquite. Because of the de- mands for irrigation water it was im- possible to reduce the flow of the river. The heavy caterpillar tractor crawled across the river in six hours and thirty minutes. Popular Science Monthly Fording the Rio Grande with a 75-ton excavator! The feat was accomplished by arrang- ing timbers to form a kind of flexible track securely fastened on each side of the channel A Checkerboard of Artificial Daylight for Workers in Color AN you distinguish tints of green and blue when you see them by artificial light furnished by the ordinary electric bulb? ; These colors may be distinguished from each other, but their various in- tensities fall by the wayside and are lost in artificial illumination, unless special pro- vision is made to save them. The green that you saw in the diffused daylight may have been twice as intense as the green shown by the electric bulb, while the blue in daylight may have been nine times more intense than the blue of the incandescent lamp.. The true color of a diamond can not be judged. by the’ ordinary artificial light, nor can that of-tobacco. Think of the valuable working hours wasted by the waning of.the daylight in industries where true color must de judged! An English artist, Mr. George Shering- ham, has experimented with a method of his own invention calculated to correct this defect. A checkerboard arrangement of squares of blue, purple, and_ green, placed in a concave reflector above the light, sends downward a blended reflection of rays approaching daylight in quality. Of course the colors of the squares must’ What to Do with “Electrocuted” This arrangement reflects the light- waves, selecting those that compose daylight and throwing them down- ward in blended artificial daylight Gas-pipes “electrocuted” by stray currents from electric railways, their life as pipes being ended 1D? ES the gas-pipe or the water- pipe leak? An examination of these pipes may disclose an astonishing condition. From five to ten years after new pipes are installed, one may be annoyed to find them leaking, and the cause at first may. seem a mystery. Small perforations in the metal indicate corrosion, but why shouid pipes apparently nearly new be in this condition? The division of Mineral Tech- nology of the United States Museum has undertaken to col- lect data regarding the damage to gas- and water-pipes by stray electric currents, the chemical action of these currents being known as “electrolysis.” The . presence of street railway systems 24 be such that they reflect the right light sensations, the daylight hidden in the artificial source of illumination. The yellow and red rays that tinted the white light are proportionately absorbed and stopped by the colored squares, and it is claimed that by this simple method of illumination an exact reproduction of the quality of daylight can be attained. The diamond merchant, the color- printers, wall-paper manufacturers, dye- works craftsmen, and those of the textile trade, will be among the chief beneficiaries of this remarkable invention. Artists can paint in color at night, and this is what inspired the artist-inventor to experiment with the method. The painter who is inspired by the symphony concert will not have to wait until morning to dab on canvas the color sensations which the musical mood may have inspired. If he answered the call of the inspirational moment as soon as he reached his studio, home from the con- cert, the daylight view next day of the sketch painted by ordinary artificial light would be quite different from his night-time intentions. With an artificial daylight a valuable color idea could be saved. Gas-Pipes carrying heavy currents in trolleys or third rails is held responsible for the damage, the return current.in the rails partly escap- ing through the moist ground setting up measurable currents in the near-by pipes. Depending upon the character of the soil, the effect of electrolysis is more or less destructive. What is the cure to prevent the pipes from being damaged? It has been found that, with a different method of insulation than that commonly employed in this country, the electrolysis of pipes can be practically stopped. The use of negative “feeders” carefully insulated, compared with uninsulated feeders, shows that the lifetime of pipes in the neighborhood of street railway systems can be prolonged from twenty-five to fifty years, and economy of operation also attends the use of the insulated feeders.

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——— Vv ee May, 1920 ‘BURST DIAPHRAGM This water-heater will chemically bring a bucket of water to the desired degree of temperature, within certain limits Heating Water Without Any Fire ET this water-heater in a bucket of water, turn the clamp at the top, and presto!—there will be hot water in a jiffy, and neither a-coal or gas flame nor elec- tricity furnishes the heat. The principle of the’ chemical water- heater is simple. In the bottom of a cylinder is placed a quantity of unslacked lime, above which is an arrangement for supporting a compartment containing a weak solution of sulphuric acid. The pressure is transmitted downward by a slight turn of the bar-handle, and this operates to open a small hole in the bottom of the acid-chamber, permitting the acid to trickle downward upon the unslacked lime. The chemical reaction liberates heat sufficiently to bring the water to a high degree of temperature. To renew the life of this chemical heater one has but to put fresh acid and lime in the compartments. Such liquids in small quantity as are required to be gradually brought to a certain degree of temperature can be satisfactorily heated by this method. Planting strawberries with a punch and tongs. He punches the hole with the tool in his left hand, and plants with the tongs Improving the Harvesting of Sugar-Beets 6 te on the gasoline, take charge of the steering lever, steer straight along the row of hidden sugar-beets, and see ~ what happens. An automatic hand of metal reaches down into the ground and clutches the beets, while a knife cuts off the tops, lifts them out by the roots, and finally stacks them along neatly where they can be collected. The old method of pulling up the beets by hand and topping them costs more than three times as much to an acre as machine harve:ting does. Real horsepower can also be used instead of horsepower merely translated into the energy. of gasoline engines. and then lifts them out of the ground. A thin knife of steel automatically per- forms the duty. The under-works of the automatic harvester is a busy place, if one watches it as the machine is driven, either by “horse” horsepower or by gas-engine power. First the sharp undulated blades attached to the topping device press into the leaves, holding the crown of the beet against the knife. Pullers are im- mediately behind and in line with the topper, revolving as the machine moves. Penetrating the soil three or more inches, they pull the topped beets out of the ground and deliver them directly The form of harvester that is adapted to into the conveyor, which is so arranged be pulled by a horse algo tops the beets that the beets are cleaned free from loose dirt and are sent prac- tically clean into the hopper in a compact mass. From the hopper they are dumped in piles, to be collected later. Follow the sugar-beet har- vester and see the result of its service. When one thinks about the vast tracts of land that can be profitably planted in sugar- beets, it is interesting to con- sider the part that improved machines can perform in the work of harvesting the crops. The automatic sugar-beet harves- ter driven by real “horsepower.” It tops the beets and lifts them from the ground, depositing them in little piles In this sugar-beet . harvester a gasoline engine furnishes the *“‘horsepower.” A revolving pulling- device, exactly in. line with the top- ping knife, pulls the topped + beets out of the ground Stand: Up to Plant Strawberries \ THEN you are eating a large, juicy strawberry, think of the stringy little plant it grew upon. A new way of set- ting these plants has been devised by a Maryland strawberry grower. He uses a punch for making the hole in the ground, and tongs for dropping the plant in the hole. Then he smooths the ground over with his foot.» .With:.the punch in one hand and the tongs in the other, he works very rapidly. When the plants have five or six leaves they are transplanted to fine, rich soil for bearing. During the process of trans- planting they must be carefully protected against wind and sun. In the South, where many of our strawberries come from, the farm-hands carry the young plants in old fertilizer- sacks. They slit the sacks near the top, and hang them around their necks. Then they make a second slit near the waist-line, through which they put in and take out the young plants. Mildew and leaf-spot are the greatest enemies of the straw- berry plant; but it is also attacked by the larvae of the garden moth and by the grubs of the cockchafer and the rosechafer. When the fruit: is ripe and-ready to be picked, ground- beetles attack it. They hide in the ground all day and are very hard to catch. There is one good way.of getting them, however. Food is placed in jars, and then the jars are turned upside down and-sunk into the ground about an inch deep. When the beetles come up, attracted by the food, they become prisoners. Thus, you see, strawberry growing is not an easy task. When strawberries are trans- planted for bearing, they are carried in sacks to protect them from sun and wind 25

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Beit deli = ste == ar LARSON esas dy sungenene sera Toga ee ° sr: Lt ate SOP Rome Mees Popular Science Monthly Is Sir Oliver Lodge Right About Atomic Energy? Sir Oliver Lodge says that if the atomic en- ergy in an ounce of matter could be utilized it would be sufficient to raise the German ships sunk in the Scapa Flow and pile them on top ofthe Scottish mountains. “I think,’ he adds, ‘““we are on the brink of a great discovery” 26

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May, 1920 Dare We Use This Power? Sir Oliver Lodge says atomic energy will supplant coal IR OLIVER LODGE thinks that man is not yet civilized enough to use the energy hidden in ordinary matter. “The time will come when atomic energy will take the place of coal as a source of power.” The man who spoke thus before the Royal Society of Arts in Lon- don was Sir Oliver Lodge —one of the towering figures in modern sci- ence, a man who has de- voted the better part of his life to the study and interpretation of the atom. This new form of energy, which our great-grandchildren may utilize instead of oil and coal, has possibilities so appalling that Sir Oliver almost rejoices that we do not know how to re- lease it. ‘I hope that the human race will not discover how to use this energy,” he says, “‘until it has brains and mo- rality enough to use it properly, because if the discovery is made by the wrong people this planet would be unsafe. A force utterly dispropor- tionate to the present sources of power would be placed at the dis- posal of the world.”’ Sir J. J.. Thomson, England’s great author- ity on the atom, gives a picture of this terrible form energy that wins one over to Sir Oliver Lodge’s view. He tells us that the atomic energy stored in an ounce of chlorine ‘‘is about the amount of work required to keep the Mauretania going at full speed for a week,”’ and that the splitting up of the atoms in any substance would in- volve enormous transformations of energy. “In fact, the explosion of the atoms in a few pounds of material might be sufficient to shatter a continent.” Eoenything Is Made Up of Atoms These eminent men of science have no particular atom in mind when they speak thus of the fearful possibilities of atomic energy. They mean the atoms of any familiar thing—radium, By E. F. Richards iron, copper, wood, or stone. The food we eat is made of atoms, and so are the tables and chairs in out houses. Every one of us, then, locks up within himself immense stores of — a © International Film Service “T hope the human race will not discover how to use this energy until it has brains and morality enough to use it properly,” says Sir Oliver Lodge, in explaining the terrible possibilities that lie not only in radium but in a piece of wood or iron energy. In a little finger there is enough energy to run all the trains in the United States for a few minutes, if we could but release it. The high explosives detonated to hurl millions of shells during a campaign are not so terrific in their possibilities as the atoms of which our bodies are com- posed. The first intimation of the funda- mental facts upon which the modern conception of the atom is based came to us through the study of X-ray tubes. In these Sir J. J. Thomson discovered particles weighing two thou- sand times less than the lightest atom then known, the hydrogen atom. These particles, which we now speak 27 of as beta particles or electrons, were subsequently found to be given off also by radium, as one of the products of the breaking up of its atoms. For, though the atom ordinarily remains undivided; we know today that it is not indivisible. In certain cases the atom breaks up of its own accord, as in the case of radium, shooting off the fragments at speeds which make a rifle bullet appear like a snail in comparison. * Active Radium Particles Thereare, indeed, good grounds for. suspecting that all matter, not only radium, is thus shooting off particles and giving out energy. - But we be- come conscious of the fact only in the case of radium and a few other - radioactive substances. Radium is giving up its atomie energy more rap- idly and more violently than limestone, for ex- ample, which ~explains why it seems more ex- plosive than other ele- ments. A radium atom is like a two-ton . gun firing a hundred-pound shot: Just like the gun, the rest of the atom re- coils after having been fired. This is not merely a speculation, a _pic- turesque guess. The re- coil has actually been observed. After five such projectiles have been fired, radium settles down into another existence—a quieter existence, such as lead or something chemically like it. A uranium atom fires off four such projectiles in order to become radium. Were the Old Alchemists Right? All this is definitely known. The old alchemists were not so far wrong when they dreamed of turning iron into gold. Nature is constantly changing one element into another before our very eyes. When we know how to control the electron in an atom we may be able to make gold out of base metal at will. Two kinds of projectiles are fired of

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eee ar SE Se Se o- by a substance—the heavy shot or alpha particle, which is known to be a helium atom, and the lighter shot or beta particle, which has been found to be the fundamental unit of electricity, an electron. An alpha particle is a sort of emancipated atom. It is fired off at a speed of 10,000 miles a second. Where does the alpha particle get this terrific velocity? From an ex- plosion. Not an ordinary explosion, however. The explosion of such a substance as nitroglycerine, for ex- ample, might be likened to the crash of a house collapsing. But the dis- integration of radium in which alpha particles have their birth is different. It is more like the continuous sputter of a machine-gun; for in this case the “house” gradually crumbles from the explosion, one by one, of the bricks of which it is built up. Heat Given Off by Radium The process is not a hasty one. If someone had started off a pound of radium in the year one of our present reckoning, it would by now, in the year 1920, be just about half gone. And yet,.so small are the individual bricks or atoms that, even with this slow rate of crumbling, from every grain of radium something over two thousand million bricks explode every second! And as the fragments, the alpha particles, fly off with a velocity of about 10,000 miles a second, no wonder that a considerable amount of heat is produced in the process. In point of fact, every grain of radium, in this disintegration, gives off in one hour.enough heat to melt more than one and a half times its own weight of ice. As this goes on for some 2,700 years, on “an average, it will be seen that radium is a most concentrated souree of energy. It’s not the sign of the ‘‘ Black Hand,” but a picture of Joe’s fingerprints Joe, the chimpanzee, is being finger- printed. _ No, he hasn’t murdered any- body; his prints will be used for com- parison with the fingerprints of men It is a plausible supposition that all substances behave in this way, only we do not perceive it because their disintegration is excessively slow even as compared with that of radium, which, as we saw, extends over thou- sands of years. We cannot, from the seemingly inert character of such substances as gold, for example, con- clude that they contain no latent source of energy. Appearances are deceptive. Gunpowder looks harm- less, too. And atoms of the ordinary chair on which you are now sitting, or of the paper of which the POPULAR SCIENCE MONTHLY is composed, may be more fearfully energetic than gun- powder or nitroglycerine. Where does all this energy come from? No one knows. But we can draw a picture of an atom that will give one some idea. An atom is a miniature solar system. There is a central positive nucleus, like the sun, and a revolving system of negative electrons, like planets. No one knows what the nucleus, the central sun, is. The revolving elec- trons are alike in all substances. The hydrogen atom is composed of elec- trons just like the electrons of iron. Electrons always repel each other. An atom is probably about one hun- dred thousand times as large in diameter as an electron. Roughly speaking, the diameter of the electron is about as large, compared with the diameter of the atom, as the diameter of our earth compared with the diameter of the orbit in which it travels around the sun. The hydro- gen atom probably consists of a nucleus and one electron revolving around it. Uranium has at least 92 electrons. All the possible elements lie between hydrogen and uranium. These electrons revolve at terrific speeds in their orbits. Every now Popular Science Monthly and then an electron or alpha particle, or both, are ejected. The speed of ejection is such that, weight for weight, an alpha particle has millions of times more energy than a bullet. A milligram of radium, an infinitesi- mal pinch, projects about thirty-six million projectiles a second. The alpha particle, with its speed of 10,000 miles a second, moves fast and strikes hard. Terrific Speed of Electrons But what shall be said of the speed of the electrons of which the alpha particle is composed? They travel almost as fast as light—186,000 miles a second. How is it that ordinarily we receive no evidence of these electrons moving within the atom? A smoothly running flywheel appears to be at rest. But when it bursts we know that it must have been turning. In the same way, since the motion of the electrons in the atom does not ordinarily become observable to us, when the atom explodes and throws off fragments at unheard-of speeds, we are puzzled until we realize that perhaps the motion existed before, within the atom, but escaped our view. It is easy to see that if atoms are composed of nuclei and electrons re- volving at stupendous speeds they must contain enormous stores of energy. Sir Oliver Lodge has said that if the atomic energy in an ounce of matter could be utilized it would be sufficient to raise the German ships sunk in the Scapa Flow and pile them on top of the Scottish mountains. “T think,” he says, “that we are on the brink of a great discovery. It may take a century. Our descendants, in- stead of burning one thousand tons of coal, will take energy out of an ounce _ or two of matter.”’, Fingerprinting the Chimpanzee O wonder that Joe, the chim- panzee, looks worried. They are taking his fingerprints.. And while they do it Joe thinks of all the deadly deeds in his past, and tries to de- termine which one they’re following © up. ’Tis true, his keeper is petting him while Maurice W. Fitzgerald, a government fingerprint expert, does the work; but Joe puts no faith in that. { He need not have worried, though. } The fingerprinting was done for the ‘ sake of comparison with the finger- ‘prints of men. Does each chim- panzee, as in the case of man, have his own particular brand? This question and others like it will soon be answered. Joe’s home, by the way, is in Central Park, New York city. The ridges that appear on the fingers and toes of men and monkeys are supposed to be there to increase the sensitiveness and firmness of our grasp, a certain amount of friction be- ing caused by these ridges. The chim- panzee’s prints are much like man’s.

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May, 1920 Saving $50,000 by Welding VBE the huge army transport Northern Pacific ran aground in a fog and sustained a fracture in the giant steel stern-post, to avoid delay and an expense exceedinz $50,000 in making a new casting, the officials in charge decided to resort to a thermit weld. Now, what is thermit? The greed of aluminum and certain other materials for oxygen is the basis of thermit. When granulated aluminum powder finely ground is mixed with powdered oxide of iron, and when heat is applied in sufficient quantity to the mix- ture, a reaction is started which rapidly gathers enormous heat and spreads quickly through the whole mass, meltinz the iron in about thirty seconds. A temperature between 2,600 and 3,000 de- grees is raised, second in intensity only to the temperature of an electric arc, and nearly half as hot as the sun itself. A mixture of calcium and silicon and mix- tures of other substances also can be used in thermit, the best kind of material being determined by the char- acter of the work to be done. The frac- ture in the wrecked vessel was 20 feet above the floor of the dry-dock, so a scaffold and platform had to be con- structed. The next step in repairing the vessel was to cut a three-inch gap in the steel with an oxyacetylene torch, the gap to admit the entrance of the molten thermit-steel. A wax pattern was built in the gap, 67 pounds of wax being used A mold-box large enough to hold 46 barrels of molding material was con- structed, 10 feet in length, 51 inches. long on the side parallel with the ship, and 48 inches above the plat- form. Openings for pre- heating the _ fractured parts were arranged, and gates into which the molten steel could flow were provided. The in- tense heat would come from 1,400 pounds of ther- mit, divided between two ‘huge crucibles on each side of the mold-box. As a precaution against fire the chains were wrapped in asbestos, and sheets of this material were placed mE ee! between the crucibles and i.e the hull of the ship, and _—— a the platform below was The spectacular part of the process came sprinkled with sand. Then when all was ready and the thermit was the thermit was poured in ignited. This was preceded by heating the parts to be welded with gasoline torches. The heating required seven hours. Two men, standing on ladders, simultaneously ignited the powder and climbed down to safety. Then the tapping pins of the cru- cibles were knocked out 45 seconds later, and the molten steel flowed into the frac- ture, welding it with a fine grade of steel o a eee oe Ey tS Rigas oa aap tm tone EO Aa aE I NR - - oN : in oe Ss rf f t ESE S

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Fi DT PT See Ee 9 eed UM AMAR IRN e aicin nanan I "acest Siehad arte ete ee At ce hep ed a PG RRR a alee cit aa es ah So 5 it: Popular Science Monthly What Happens When a Great City Suddenly “Looks like a storm coming,” says the weather-wise busi- ness man, whose perch is the top floor of a skyscraper. Other people far down behind the windowed walls notice that it is getting dark, but they can see little of the storm that is approaching, because their view of the sky is lim- ited. Then suddenly all the great city realizes that it has become dark in the middle of the afternoon. “Click! Click!’’ go the buttons turning on the electric lights, and Photographs by courtesy of the burden of instantly supplying about 175,000 additional horsepower is thrown upon Waterside, the generating sta- tion of the New York Edison Company. What would happen if preparation had not been made to meet such a huge demand? Either no lights could be furnished the darkened city or other power would have to be cut off. In other words, the coming of a severe storm would tie up the business of the city until conditions again became normal When two million lights are sud- denly switched on during the time when the greatest amount of power is being demanded by the city, the New York Edison Company is pre- pared. The approach of the dark clouds is announced by an in- genious device, the ‘‘wireless storm- announcer.’”’ A system of relays is connected with a coherer and a bell. When a storm is an hour and a half or two hours away the bell rings every fifteen or twenty minutes, and as the storm draws nearer the ringing becomes more frequent. ; Some storms pass away without ringing up the power station from closer range;. but others advance so rapidly that quick work must be done 30 Notified by the wireless storm annunciator of the swift coming of lowering clouds, and knowing that the city in an hour or less will be plunged into darkness, the system operator at the central station has everything prepared for the increased load. The banked fires must be immediately ready, and the auto- matic stokers are set to work to generate quickly the steam-energy which, by mechan- ical magic, will soon be turned into electrical energy. While the city makes its demand without warning, the storm sends its warning ahead by -the “static” condition of the atmosphere. The watchful operator in the power station becomes more than usually attentive, and soon the fires flare up, the boilers quickly respond, and the whirring generators begin to manufacture electricity

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May, 1920 Turns on Two Million Lights to Meet a Storm the New York Edison Company As the storm swoops down and the sky darkens, there is strict attention in the room where the indicators are arranged. Watchful eyes are turned toward the numbers of dials on the wall. Every district must be looked after and its requirements fully provided for in advance. Nothing is overdone, -but enough electricity must be generated to meet the requirements. Both generators and storage batteries may be called to the rescue when a severe storm prevails, so the close watchfulness by the men before the indicators interprets the story told. by the instruments, and the action of the plant follows When the wheels of activity are whirring to generate the extra load of electricity needed to overcome the darkness of the thunder-storm, what does the effort really mean in the terms of figures? On a day (June 20, 1919) when the record storm of the year occurred, one sees at 5 A. M. about 75,000 horsepower being used by the city. The low ebb of Edison power was at hand. By the timie the factories opened at 8 o’clock, about 165,000 horsepower were being drawn upon, while at 11 A. M. there were slightly more than 250,000 horsepower. The highest point reached in the afternoon would normally have been about 250,000 or 275,000 horsepower; but the extra load brought about by the storm caused the amount to jump suddenly up to about 425,000 horsepower! The huge increase, 175,000 horsepower, had to be prepared with scarcely an hour’s notice Imagine a score or more of men stoking the fires of the huge electric power plant, to beat the approaching storm in the race toward darkness! That is what would have to be done were it not for the fact that the New York Edison Company at its Waterside sta- tion employs only automatic stokers. The whole operation of sending fuel into the fires under the boilers is automatically conducted under the guidance of a few intelligent workmen... The hard conditions and the strain of the storm are borne, not by human beings, but by the steel of machines. From the unloading of the coal from the barges, to the removal of the ashes, the process is car- ried on almost entirely by mechanical means

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fe ge Signor Luigi Fortoni has invented a type- writer that will register notes of music Music on the Typewriter patter numbers, and figures are not the only things that can be registered on the typewriter: it can also register music, as Signor Luigi Fortoni has proved. He has invented a rapid music writer and is shown here using the machine. There are but ten keys on the music keyboard, yet with them it is possible to print with precision all the different char- acters, together with their alphabetical letters, in two sizes. The -notes are given their correct length, and transposi- tion from key to key is made possible. Wetting the Air Your hands feel hot and dry if you sit in a room where there is not sufficient moisture. True, you can place a pan of water on the radiator, but the water does not evaporate rapidly enough. Ralph J. Patterson, of Berlin, N. H., has invented an electric humidifier. It is made of metal shaped like a satchel. It is partly filled with water. A few inches above the surface of the water is a cylindrical electric heater. A wick is looped across the heater, and both ends terminate in the water. The water rises in the wick until it reaches the heater, whereupon it evapo- rates and escapes through air-holes in the lid. As soon as one group of molecules evaporate, another group run up the wick. \ As he makes the connection, an electric heater inside the humidifier becomes hot and evaporates the water in the wick Place the sockets over the tongue of the board, and hammer in the spike Use This Clamp on Those Warped Boards ‘THis is a story of how suppressed irri- tation finally exploded and in so doing produced a floor-layer’s clamp. They were a good bunch of fellows—a volunteer crowd—and they were put- ting in their spare time repairing and re- decorating the little Presbyterian church. Everybody knew everybody else, and they were having lots of fun over the job. There was just one fly in the ointment: the matched boards that they were using were warped. The only reason they didn’t swear was because they were in church. : Ray Aylworth, the blacksmith, had become rather irritated over the job, and vowed he would make something to fix it. At the next session he turned up with a fearsome-looking tool that ap- peared to be a mixture of a pitchfork and an automobile jack. The tool had a fork at one end, and each tine had a socket that fitted over the tongue of a matched board. At the other end was a spike that projected at right angles to the shaft of the tool. In the center was a handle and a toothed wheel, or pinion, working in a rack. ~ Ray asked somebody to place a badly warped board in position on the partly finished partition wall. He slipped the sockets of the fork over the tongue, and with a hammer gently tapped the spike into the two-by-four scantling. Then, by working the handle up and down a few times, he extended the rack like an automobile jack. Three or four strokes clamped the board so tightly that an- other stroke or so would have broken it. He then put a nail in between the tines and held the board firm. The same operation was repeated at the other up- rights, and—presto!—the board was in place. The clamp is adapted to many dif- ferent kinds of work; it is inexpensive; © it enables otherwise useless wood to be employed; and it is compact. 52 © Interna- tional Fitm Service Popular Science Monthly Hauling down the flag is accom- plished by readjusting the pole The Folding Flagpole N the picture above, the Stars and Stripes is flying on a flagpole only two feet high. The pole is one of the col- lapsible flagpoles recently invented by Fred Lindstaedt, of Fairmont, Minn. The flagpole tapers from a broad base to a pointed top. But at the middle there is a short cylindrical section, at which place the pole is divided in two. To lower the flag when evening comes, the upper half of the pole is pulled out of the lower half, turned upside down, and inserted, point first, into the lower half. The two cylindrical sections coincide once more and the pole is half its normal height. A Hose Watering-Pot WHEN the gentle rain from heaven fails to drop,-you get out your watering- can—if you happen to own a garden—and fill it with water. To do this you hold it under a faucet and turn on the water. Your hand moves slightly, the water hits the guard on top of the pot instead of going in, shoots off at an angle, and lands on you. You are drenched and angry. But you are not the only one who has suffered this. Alice E. Wilt, of Philadelphia, had similar experiences and they inspired her to invent a new watering-pot. : This pot is supplied with a pipe which goes through the top of the can, through the handle, and is threaded at the end so that an ordinary garden hose will screw into it. To fill it you need only screw and then turn on the hose. On one side of the can there is a holder for shears, and on the other side one for a trowel. To fill up this watering - pot turn on the hose ,

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May, 1920 At any rate, the box is marked very plainly so that you don’t get a_ shock when you open it © Kadel & Herbert At first he thought it was real. It turned out to be made up of An Alligator in His Mail N° wonder the mail service is what it is! It is no longer confined to modest letters with little red stamps in the corners. You can send almost anything by mail — alligators, for in- stance. Nearly everyone who goes South for the winter sends a dear little baby alligator to some unfortunate relative up North—it’s so useful! The alligators are shipped in small boxes that are very plainly labeled “Live Alligator.” Do you wonder that there is trouble in the post-office? If you were a post- man, how would you like to carry around on your back a bag full of squirming alligators? A Russian ambulance turned into a sled without taking off the wheels From Wheels to Runners N Petrograd, when snow begins to fall, it is often convenient to put wheeled vehicles on runners. By means of an ingenious arrangement an ambulance is rapidly adjusted to the severe conditions of travel brought about by sudden changes in the weather. Instead of taking off the body of the wagon and fitting it to runners, a sled is employed that accommodates wheels and all. Thus the ambulance is moved upon the sled and securely attached so that it will not roll off, and the tired horse is no doubt grateful for the change. When the snow and ice melt it is an easy matter to change back again to the wheels by merely moving the ambulance off the sled. A street-car equipped with a 26-horsepower engine and a powerful airplane propeller Taking the. Air in a Street-Car IMOROUS folk who have vowed that they never will ride in the propeller-driven airplane may retract enough to take a trip in the propeller-driven street-car. In the city of Burbank, Cal.,a steel and aluminum car, built to accommodate fifty-six people, hangs from a single track along which it runs supported by A gasoline engine of twenty-six’ horsepower drives a powerful propeller, the shape of the car being constructed on the plan ‘of a torpedo, cutting through the wind when speeding along at a overhead wheels. lively rate. real kernels on an artificial cob A Yard of Corn T can’t be real!”’ says the man above, as he looks at the monster ear of corn towering up in‘front of him. And he is right. It is not a real: ear, but a very cleverly constructed one. It is made up of the largest kernels brought forth by more than one hundred real ears, fastened to an imita- tion cob. It is more than a yard long, and has eighty-two rows -of kernels with two hundred and twenty-five kernels to each The passengers are thus afforded an opportunity row. This artificial monster was exhibited at the recent Hay and Grain Show at Chicago. to realize how it feels to ride behind a powerful air- plane propeller without being in danger of falling when the propeller stops. It Does Away with the Services of the Caddie NEW golf-club holder invented by Edward Vogel, of San Fran- cisco, is threatening the caddie bus- iness. It is much lighter than the usual golf-club bag, and it can be carried by the player himself. It consists of several tubes—one for each club—fastened together at the top. The central tubes are much longer than the outside ones. The golfer slides his clubs down the tubes and carries them by a handle that fits over the arm. When he reaches the golf course he sets them up tripod fashion. She carried her own clubs to the course, not in a heavy bag but in tubu- lar cases joined together at the top 33 A strange collar-button is this, made of a metal bow-knot and a spear, linked together; the necktie holds it in place The New Collar-Button OU’RE not the only man who growls at collar-buttons. Robert V. Samp- son, of Denver, grew so enraged at one that he took it and the collar it had torn to his work-bench, and sat down and glowered at them. Before he got up he had planned an entirely new collar-button. It is made in two parts linked together at right angles to each other. The upper one is shaped like a bow-knot, and the lower one is long, straight, and pointed. You thrust the point through shirt and collar as far as it will go, and then press it flat against your collar. The link makes this possible. When your necktie is firmly tied it will hold the spear in place.

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cgprtes: a ie A oo nen nw ROMMEL ne voters na 5 wr ain place a sheet of paper where the Fae a pen to a leaf and pen can move upon it freely. Then watch the leaf write in plain’ terms the most minute details of its passing sensations! Substitute a deli- cate magnetic apparatus for the mere crudity of a pen and the fact is accom- plished: the dumb leaf will open its confidences to the eyes of man and indicate exactly how it responds to the influence of outside happenings. He Reads the Thoughts of Plants The man who has discovered the key to the innermost secrets of plant life, and who has exposed the very “life movements” of the trees, is Sir Jagadis Chunder Bose, founder of the Bose Re- search Institute of Calcutta, India. The interested visitor who steps into the Institute at Calcutta will see a large tracing being auto- matically made in two curves. The first curve shows graphically the changes of temperature, the shifting effects of light and atmosphere that are taking place throughout the twenty-four hours of the day. The other curve shows the resulting effect in the response of a tree standing out- side the building. The passing GERANIUM—” Popular Sctence Monthly Watching the Heart-Beats of a Plant Sir Jagadis Chunder Bose, a Hindu scientist, has discovered a secret of nature 5G Leatlewet.3..Wileon cloud, the temperature change, the fall of a raindrop or the shifting wind. —all are reflected in the heart-beats of the leaf! Only the larger movements of plants were recorded by the first instru- ments invented by the Indian scien- tist, but continual improvements _ apparatus that it is a simple matter _ to detect motions of growth far less than’ one four hundred millionth} of an inch, occurring in a shorter time than one hundredth of a second! The principal feature of the “‘mag- netic crescograph,” the instrument that makes visible the pulse-beats of the plant, is a long magnetic lever, the short arm of which is attached by a cocoon-thread to the leaf. The other end of the lever is arranged to move in front of a magnetic needle to which a small mirror is attached. The very slightest motion of the brought about a means of greatly magnifying the small motions, until finally the curious discovery was made that every plant, like every living animal, has a “‘heart- beat,” rhythmic and _ regular, which indicates its state of health. So delicate is the recording MIRROR SS / LEAF The magnetic crescograph, composed of a magnetic lever, a magnetic needle, and a small mirror which reflects a beam of light, forming a spot of light upon the screen. The motion of this spot shows at a glance the pulse-beats of the leaf attached to the arm of the lever by a cocoon-thread The heart-beats of a plant. One sees on _ the screen a graphic line of motion illus- trating the effect of poison on a plant. The line-waves diminish until at death they form a straight line and the spot of light on the screen then ceases to move 34 How ether affects a plant: first is seen the normal response before the ether is admitted, then is seen the stoppage of pulsation due to the. effect of the ether. recovery of the When the ether is blown off, the rapid “‘theart-beats’”” may be noted thread-end of the magnetic lever meets with response from the needle with its attached mirror. When a beam of light is thrown on the mirror at an angle, it is reflected on a screen, and the slightest motion of the mirror shifts the spot of light. When the plant contracts under a shock, the movement is in a re- verse direction; when the growth stops, the spot of light becomes stationary. A magnification of ten million times is possible. If the human heart-beat were magnified to this extent at the rate of seventy-five beats a minute we would see about twelve million “‘palpita- tions” every second. — Explaining the Mysterious Mimosa Ordinarily the records in the study of plant growth are not necessarily magnified so greatly, and instead of being thrown on a screen they are marked with a point delicately adjusted near a plate of smoked glass. Sir Jagadis

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May, 1920 has observed various plants. mosa, well known as a “sensitive plant,” is shown by the investigations to be merely more obviously sensitive than other plants. The “nerve” of the mimosa leaflet, the pulvinule, corresponds in its up- and-down motion to the expansion and contraction of the animal heart. It is a “rhythmic tissue,” the mo- tion of which may be disclosed with light from the marvelous crescograph. At the top of the mimosa The mi- ~ But what are the practical results to be obtained from the wonderful in- vestigations conducted at the Re- search Institute? The more we know about plants the more we know about agriculture. It is no longer necessary to wait months, even years, to discover under what conditions plants thrive best. The crescograph answers our questions in a few minutes. More- over, much light is shed on the life processes of higher animals. Highly arate : — from shock, the effects of various stimulants, can all be seen in the high magnification provided by the mag- netic crescograph. When stimulated, the heart-beats of a plant become enhanced in size. De- pressed with poison, they dwindle in size until the cause is removed, and if not removed the death spasm is seen in the quivering writing of the recording instrument, when the heart- beat stops. This physiological effect of drugs on the simple life- may be found the youngest leaflets, while the mature leaves occupy the middle zone of the tree. At the - bottom are the aged leaves. Investigations were made separately to find just how . the age of leaves determines their response to stimula- tion and their recovery from shock. The effect was found to be very similar to what might be expected in animal life—the young and the very old differing greatly from the mature adults in their response to stimula- tion. Did You Know that Plants Sleep? What is the effect of cold on the heart-beats of plants? Sir Jagadis has found that intense cold paralyzes the action of the rhythmic tissues. In ordi- nary cold weather the trees that are acclimated merely ‘‘hibernate,’’ when the leaves die. But the most astonishing result of his in- movements is regarded by physicians as leading to an important advancement in the science of medicine. It is possible to test the effect of drugs: in a far simpler manner than that employed upon the higher forms of animal! life. Reading the Life of a Leaf How interesting to sit in the darkened auditorium and to watch the screen upon which the crescograph is writing the autobiog- raphy of a leaf! In a ver- tical direction the spot of light oscillates. Gradually the audience becomes aware of a change that is taking place. There is a diminish- ing motion in the wavering image of the light reflected from the small mirror. Is the leaf about to expire? The lecturer explains that the leaf is under the influence of an anesthetic. Ether has reduced its state of sensibility, and its nor- vestigations is the disclos- ure that plants, like ani- mals, actually sleep. During the period of rest there is a decided difference in the heart-beat of the leaflet from that of its waking hours. ° In its rest- ing hours the plant is less capable of excitation, and, curiously enough, the rest- ing time of the mimosa is from evening to morning. Its waking up time is about 8 A. M., and the maximum of activity is reached at from 1 to 3 P. M. The Indian plant Desmodium gyrans has furnished many experiments. Its pulse-beats range from one- to two- minute intervals. A leaflet immersed in water was kept in a dim room for forty-eight hours before its —heart- beats stopped. A cut leaf generally retains its rhythmic life-movements for a similar interval, at the end of whiclhi it can be revived by stimulants. The arrested growth of plants may also be revived by stimulation. Courtesy of Hollinger Sir Jagadis Chunder Bose is imbued with all the mysticism of the East, and yet he is an exact scientist in the fullest sense. His wonderful instrumental study of matter, living and non-living, has made him more of a Hindu than ever. “It was when I came upon the mute witness of these self-made records, and perceived in them one phase of a pervading unity that bears within it all things: the mote that quivers in ripples of light, the teeming life upon our earth, and the radiant sun—it was then I understood for the first time a little of that message proclaimed by my ancestors on the banks of the Ganges thirty centuries ago”’ developed forms of life, such as are reached in the animal world, are so complex that much difficulty attends their isolation. To study the effects of disease and the results of remedies in the simplest life- forms would be of great benefit when adapted to the higher forms. Life is ephemeral in animals, compared with that of plants. and ten is a puny age compared with the 5,000-year-old sequoias! Thus in the recorded pulse-beat of the plant can be observed the primitive prob- lems of life. The effects of various drugs, the depression or the recovery 35 Man’s fourscore years. mal heart-beats have tem- porarily stopped. When the fumes of ether are blown away, the pulsations begin. at first they are very small and weak, but gradually the spot of light begins to swing upward and downward in the rhythmic form similar to that of the normal motion. One of the most interest- ing applications of Sir Jagadis’ dis- covery was recently tried on a tree that was supposedly impossible to transplant. Previous attempts to transplant other trees of its kind had resulted in the death of the plant. Working on the theory that the shock had proved too great for the sensitive plant, the tree was subjected to the effects of ether during the operation. When it recovered from the ether after the replanting had occurred, the tree first shed its leaves, but it lived, Precisely as in the case of animals, an anesthesia proved beneficial in easing the shock of the operation.

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Ra ee core ee oe Popular Science Monthly The traveling players and their play-house are . © Haris carried around the country in a motor-truck Again the Traveling Players N the days of Shakespeare traveling players went from town to town, carry- ing their costumes in a bag, and playing their plays in any old barn they could get. Today we again have traveling players, but they travel in state. The War Camp Community Service of the District of Columbia manages them. A powerful motor-truck draws behind it a large play-house on wheels. Inside there are dressing-rooms, space for the scenery, and the stage itself. The actors ride in the truck. The first performances were given for the benefit of charitable institutions. But the play-house was too frail to withstand the jolts it received, and it is now being rebuilt. Armor for Plants T° protect young plants against cutting insects and other injurious pests, a shield of ‘‘armor” has been invented for the growing plant. A piece of metal or flexible material rolled into a cylindrical form is cut at the top so that strips can be curled outward and offered as an obstruction to the army of insects that advance from the ground. The device is easily applied, and provides an impassable barrier to the insects. It also serves to shield the plant from dangerous winds. The same principle may be employed in a larger device to be applied to fruit trees. The. armor - to be & Ewi The Strawberry Barrel “CC TRAWBERRIES, fifteen cents a quart,”’ shouts the peddler in the street. : : You get out your fifteen cents and buy a box because they are so cheap. But they are not nearly so cheap as they would be if you grew your own—and you don’t even need a garden to grow them in. A barrel will do just as well. Look at the barrel shown below. It has strawberry plants growing out of its sides and its top, and enough strawberries come to life on them to supply a small-sized family for a whole summer. To make this garden, take an old flour- barrel, fill it with rich, loamy soil, and bore a one-inch hole in it every six inches. Into these holes thrust young strawberry plants. They will thrive just as they would under normal conditions, provided they get suf- ficient sunlight and water. This barrel sup- clamped aroundthe ; stem of the plant, to protect.it from damaging insects The armor clamped into position around - a young plant, mak- ing it proof against strong winds and cutting insects plied strawber- ries all summer The baseball team of the House of David—a re- ligious order—is known for its skill and long hair What Lovely Tresses! HEN the wind doesn’t blow too hard, the ball team of the House of David —a religious order at Benton Harbor, Mich.— will hold its own against any team. But on windy days the long tresses of the players blow into their bearded faces and they are greatly handicapped. \ Long hair and beards are among the re- ligious customs of the order. Nevertheless the ball-players are regular chaps, and they have won many games played with semi- professional teams. One of the players— Mooney—is so good that he is to be given a trial by the Chicago'Cubs. The manager, Francis Thorpe, is taking the team on the road this season. A long-haired band travels with the players and furnishes music at the games. Riding the Ostrich AN ostrich may be foolish enough to put its head in the sand when it is being chased and think it is safe; but when a man actually jumps on its back, it runs—and runs , swiftly. At an ostrich farm in Florida you can ride an ostrich around the race- track for the small sum of fifty cents—provided you don’t weigh more than one hundred and fifty pounds. That’s as much weight as an ostrich will carry on its back—though it will pull four hundred pounds in a cart. When you mount the ostrich a sock is pulled over its head—it feels safer in the dark. When the sock is pulled off, it leaps forward. You grab _the feathers and hang on while the ostrich races around the track with you. It can easily beat a horse in’ a long-distance race. - Riding an ostrich around the race-track’is a new sport. It doesn’t weara i harness; you simply hang on to its feathers © Kadel & Herhert

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: May, 1920 oe eta Set eae Ta ae Baggage, not bombs, go in this airplane’s capacious maw The Baggage-Room of an Airplane "THE baggage-room of a railway train is a dark and gloomy place. Many a passenger has wept at the thought of put- ting her pet dog in it. But the baggage- coach of an airplane is not by any means a cold, gloomy place. In fact, it is apt to be very warm, since it is often located near the engine. The picture above shows a regular porter stowing away baggage in the front end of a French passenger airplane. The owner of the bags may be seen climbing in the rear. Compare the present-day airplane, with its space for pilot, observer, passengers, and even baggage, with the airplane of ten years ago. She’s a Truck-Driver E careful what you say about truck- drivers in general, hereafter. They are not all huge persons with large swear- ing vocabularies. -Here is one, for instance, who is both charming and soft-speaking. Her name is Luella Bates and she lives in Clintonville, Wis. Not only does she drive her own truck, but she does all of the repairing herself She and her truck are shown below. c A portable searchlight that will throwa beam of dazzling light a distance of ninety miles. It can be wheeled into any position and the angle of the light accordingly regulated Throwing Light from New York to Philadelphia [NX trying out a new portable searchlight it was found that a dazzling beam of light can be thrown from New York to Phila- delphia, a distance of ninety miles. The source of light is a carbon are drawing a current of 150 amperes at a pressure of 75 volts. A concave parabolic reflector forms the rays into a brilliant beam and projects it with great power along the length of its course through the night air. The portable feature of the searchlight is interesting because of. the ease with which it can be operated. The entire mechanism can be rotated on a horizon- tal axis; besides this, the car upon which the powerful light is carried can be turned as easily as the light itself in any direction. In this smoke-house, smoke perco- lates through a vent in the floor A Smoke-House that Will Not Burn SMOKE-HOUSE built of slabs of con- crete instead of logs, and having an underground channel through which the smoke can be drawn from a fire built out- side, is an innovation in smoke-houses, con- structed by Mr. Fred Traub, of Doon, Ia. The heat from the fire is partly lost in the passage of the smoke through the underneath vent, an advantage in smoking meat, because otherwise the temperature might be high enough for the fats to drip. The fire-pot is placed outside at the back of the concrete house, where the fire can be easily replenished and controlled. The concrete smoke-house is not only burglar-proof to a greater extent than are wooden structures, but it is fire-proof. . The Senators’ Subway Dp you know that the senators at Washington have their own electric subway to take them from the Senate Office Building to the Capitol? The subway train looks very much like the scenic railway trains you see at amuse- ment parks. But of course the senators don’t need to he strapped in. The front end of the train is shown, and in the front seat are Senators Poindexter and Dial. Woman can do anything a man can, it has been said. Here is exhibit A for feminine efficiency—Miss Bates and her truck 37 © International Film Service Co. We often hear of ‘‘senatorial courtesy”; perhaps it thrives because senators have a subway where strap-hanging is not necessary

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Popular Science Monthly © Publishers’ Photo Service A hothouse made out of an old drum upon which motion-picture films were dried. Old negatives were between the strips An Improvised Hothouse ROM a drying-drum upon which miles of motion-picture films have been dried, te become the framework of a hot- house is a big jump of adventure. Per- haps hundreds of feet of film, picturing scenes in which heroes, heroines, and flowers figured, once were spun around the wooden drying-frame. ; Now the drying-drum has become a fixture of the outdoor sunshine and serves as a support for a photographer’s old negatives from which the gelatine has been washed. Through the glass the sunshine pours upon the young plants, and under its warm rays they thrive just as well as in the usual hothouse. The Lever Potato-Fork AYS the farmer to his helper: ‘‘Fork up those potatoes,” and the helper picks up his fork. On the handle, down near the prongs, is a clamp that holds in place a swinging metal rod. When the man starts to dig up the potatoes, he thrusts the rod into the ground, and it acts as a fulcrum for the fork, making his work much easier. The fork becomes a lever and pres- sure on one end forces the other end up. Instead of lifting the fork at each stroke, it is necessary for the farmer simply to press down on it. A metal rod attached to the handle of a potato-fork acts as a fulcrum and turns the fork into a lever A stake with an adjustable wire hoop on it will support a weak-kneed plant. As it grows slide the hoop up or down Provide Crutches for Weak Tomato Plants - "TOMATO plants cannot stand on their own roots, and this is also true of many other plants. They have to be artificially supported throughout their lives. Such plants are usually tied to up- right stakes. Yet as they grow taller they must continually be retied. A plant-supporter has recently been invented, consisting-of a -wire hoop that slides up and down on a stake. The hoops come in all sizes. Echoes from the Bottom of the Sea OUND travels through still air of a certain density at the rate of about 1,100 feet a second. Making use of this principle, a device has been tried that promises success in finding the depth of the sea-bottom in any locality. A small amount of explosive material is discharged at the side of a vessel, and the reflected sound from the sea-bottom is caught in a microphone suitably attached to the vessel. A chronograph registers the difference in time between the discharge of the explosive and the reception of the echo in the micro- phone. An accuracy within 1-1,500 of a second or about 40 inches in measurement is attainable. 38 The sun, so noisily welcomed by the cockerels, soon becomes a warm visitor, and they crowd under the family umbrella Umbrellas for Chickens *“LTOW outrageous is the glare of sunlight here in the poultry yard!” is probably what all the chickens are talking about in their peculiar manner when the midday sun beats fiercely down. Mr. L. S. Fisher has solved their problem to the complete satisfaction of his valuable chickens. The family umbrella, firmly secured so that a sudden gust cannot whisk it away, was promptly appreciated by the crowd of White Leghorns that flocked under it for shelter. The glorious sun which they had so noisily heralded in the early morning was now screened from sight. Weeding Made Easy \WHEN the weeds grow up overnight there is a way to eliminate them promptly in the morning. Mr. Lewis Inman has invented a simple arrangement for bringing genuine disaster to the bolshevik weeds that spring up in the garden’s orderly plot. He merely shoves a handle somewhat like that on a lawn- mower, and a wheel guides some knives ‘over the ground, digging under the weeds with blades that are rounded so they can be worked close to the roots of plants not to be dislodged. The hand-weeder can be piloted around rocks without injury to the knives. The rounded points of these blades can pass near the roots of plants without any danger of cutting them

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May, 1920 The flag-pole, held in the metal bracket, is ad- justed at the de- sired angle; then the clamp is tightened to hold it in place Taking the Strain Off the Flag-Pole Aas out the flag and drawing itin again puts a certain strain upon the staunch flag-pole and the support that holds it in a fixed position. The sudden jerk caused by a gust of wind throws addi- tional weight upon the bracket that holds the pole, and unless it is strong there is an added danger of its breaking. To overcome these inconvenient possi- bilities, a new flag-pole bracket has been invented. Mr. Edward S. Mowry is the inventor who had the foresight to design a support for the flag-pole, enabling it to be rigidly clamped in the desired position. The strength of the metal will hold against the tug-of-war set up by the wind. Lit- erally with clenched teeth, it will bravely support the flag. The method of fastening the cleat to the metal of the bracket gives great security to the strength of the cleat in resisting the pressure of the wind. Heavy flags can be managed easily when they are pulled in or raised on the flagstaff. Chop Cabbage in Circles IF you sharpen the edge of your biscuit- cutter you can use it-as a chopping- knife. According to the rules of geometry, its circular edge will cut more than three times as much as would a straight blade having the length of its diameter. Behold the busy housewife below, chop- ping cabbage.. See how much she. clips at a single stroke. She finds the circular cutter very easy to handle. Hence- forward her family will be fed coleslaw often and in large quantities. A circular chopping-knife will cut three times as much cabbage as a straight one Johnny doesn’t mind having his hair cut when he sits on a merry-go-round hobby-horse The Barber’s Hobby-Horse “TOHNNY got a hair-cut!” All the hoodlums in the neighborhood yell this after Johnny every time he comes from the barber’s. No wonder he weeps when his mother drags him there. But in one of New York’s large depart- ment-stores the barbers have no trouble. All the little Johnnies are eager to be shorn. Why? Because the usual stiff- backed ‘ barber’s chair has disappeared, and in its place there is a regular merry- go-round hobby-horse. While the barber chips, Johnny pulls the reins and is thoroughly happy. Where the High Cost of Baby- Carriages Doesn’t Trouble HEN an American mother goes marketing she puts her baby in a rubber-tired carriage, wraps him up in blue ribbons and lace, and starts out, proudly wheeling him before her. But when a Moro mother goes marketing with her children she’s not so fussy. She sits her children on her shoulders and lets them hang on to her‘hair. Thus her hands are free to carry bundles, if necessary. Such a mother is shown below—though she isn’t carrying anything except her children on this trip. She took her hus- band along to carry the bundles. The Moro mother carries her children on her shoulders and they clutch her hair 39 The head of the “safety” oyster- hammer fitsthrough a circular disk, pro- tecting the eyes of the oyster -shucker Protect Your Eyes When Shucking Oysters “LOOK out for the splinters!” a stranger would exclaim if he gave expression to his thoughts when he sees an “‘oyster-shucker”’ professional in the act of hammering open oyster-shells. The bits of flying shell sometimes dart in the direction of the worker’s eyes, and there is danger of losing one’s sight if a well directed blow sends back a sharp bit. Mr. Norbert Buras, of Louisiana, has greatly lessened this possibility in the invention of a “safety”? oyster-hammer. Attached in a slot back of the hammer’s head, and covering the area from which the splinters fly, is a circular disk of trans- parent material. Celluloid or mica are able to withstand the shock and yet permit the one who hammers the shells to see how to direct his blows. When the workman is very proficient he can strike exactly the right spot without looking at what he is doing, so that even an opaque disk may be used for protection if one desires, Make Stirring Easy “@TIR constantly,” says the recipe. And there has recently been invented a stirrer. It consists of a long metal handle with a flat swinging disk at the end. Suppose you are frying potatoes. A spoon or fork will not scrape them from the bottom of the pan, but the new stirrer will do it thoroughly. In cooking scrambled eggs, it isn’t necessary to scramble them before putting them in the pan. Simply use the stirrer for the job. A stirrer takes the place of the fork and spoon formerly used for mixing things

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ae Ri whe BE ET SM Ba: at en a @s chew” aha - RR EAPO? 4 camila ica 28 Iie Ss RRND ii Nit Ea nia ae : penal t OTA: CAS: CN Ba ey rs the lightning craekled-sharply across the horn-gap ~arresters. ) But down on the floor of the power-house, in front of No. 3 unit’s panel in the main switchboard, little Bob Fitz- gerald, the chief engineer, continued to frown up at his new attendant. “No, no,” he protested impatiently. “Think! What's the field circuit for, anyhow?” Johnny Gibson pondered a moment. “Why, it’s to excite the alternator,” he replied. Outside, thunder, in the wake of the first lightning flash, rumbled away in the distance, and overhead a second flash crackled more sharply across the horn-gaps. But little Bob continued to frown up at his green assistant. “Then what do you suppose hap- pens when you open and close this?” he demanded, jabbing a thumb toward a piece of equipment on the slate panel before him. It was the field switch, and Johnny eyed its heavy polished blades and considered. “Why, I reckon if you’d open it that’d kill the alternator,” he de- cided at length. ‘‘’Cause then there wouldn’t be any field.” The thunder boomed closer as little Bob nodded jerkily. “Of course,” he retorted. ‘When any alternator’s running, it’s live as long as this switch’s closed and dead as long as it’s open. Remember that now, and don’t go—” Then the Big Crash Came A crash drowned out his words. Overhead, in the row of horn-gaps, a huge ball of fire leaped out, blazed for a moment in blinding brilliance, and then broke into a score of crackling streamers. Little Bob turned quickly toward the switchboard. But scarcely had he done so when, from behind the bulk of unit No. 3, appeared the tall figure of Mike Collins, the oiler, his long arms waving excitedly. “Fire! Fire!” he yelled. ‘“Num- ber three’s a-fire!”’ And No. 3 was. (0) Werninee an arriving flash: of Little Bob ge er, ~ Johnny Gibson, rounded the disconnected ~-=. smoothly swaying Corliss en- No."3, “andy ‘S$ egine and came upon the big iii “. generator, a dense cloud of As little Bob, followed by . heavy black smoke was pour- ‘ing out of the pit beneath it, ‘and through this could be.seen the fligker of fame. . “Get. some extbiguihers!*. ‘little Bob commanded.» -. + Mike - obeyed. . The chief panded and raced back .around the engine; and Johnny, thinking he.too was in search of extinguishers, ‘followed.. But little Bob simply jerked? open the big oil switch, disconnected No.'3 from the bus-bars, and dashed back once more. “Want me to shut her -down?” Johnny called. Little Bob shook his head. “No! Her breeze’ll drive the blaze away from her coils. Come on!’ Chemical Extinguishers to the Rescue Mike had hurriedly assembled a half dozen ‘chemical extinguishers, ready for use. But the fire likewise had been taking steps in the way of preparedness, and even more rapidly. In the pit under the generator was a large quantity of oil, accumulated there because of disabled overflow equipment. This had rotted the in- sulation on the three main leads where they emerged from the stator frame, and the lightning had of course flashed . across this weakened spot. Now, as the three men turned the streams of liquid into the smoke cloud, it lifted, disclosing a flare of are sputtering from one cable to another and igniting both oil and insulation. “Hurry! Hurry!’ little Bob yelled excitedly. “Stop it before it spreads! . Mike and Johnny obeyed. : ‘In’ spite of the choking gas that. rosey-:the instant the liquid “came in “contact with the heat,,they sent their streams hissing into the*blaze. The Dlazixg : ‘oil -was extinguished. The smoking insulation was extin- guished. The spitting tongue of arc was snuffed out—but only as long as the streams were held directly upon it. “What’s the matter with these extinguishers?” little Bob demanded. “Here, give me one!” But nothing was wrong with the extinguishers. The gas that rose when the liquid struck the heat had the familiar suffocating odor. Yet, as soon as the streams were deflected, the 40 Popular Science Monthly Fighting a Fire with Brains The cub electrician remembers a lesson and saves the power plant By Charles Magee Adams blazing arc flashed up, driving the line of fire nearer and nearer the stator windings. The supply of reserve extinguishers at hand was exhausted. .“‘Get some more! Hurry!’ little Bob. ordered. Mike handed his‘still charged ‘tank to the chief, and dashed away. For another minute the two ren ‘who-remained-fought on side by side “Sn. the ‘cloud_of gas and smoke. But still the line of fire, fed by the crack- ling arc, crept relentlessly nearer the vitals of the big alternator. Then, while his extinguisher still threw a steady stream, Johnny Gibson dropped it, turned, and darted out of sight behind the still throbbing unit. Little Bob was frantic. “Come back! Come back here!’ he shouted. But Johnny had gone. Left alone, the chief engineer turned against the fire with feverish des- peration. The pulsing flicker danced between the cables, closer and closer to the stator windings. And then, suddenly, like a match flame caught in a puff of wind, it disappeared. What Johnny Had Done Little Bob deflected his extinguisher stream; but it did not reappear. He shot the liquid at the insulation, and its glow died to charred blackness. He sprayed the flickering oil, and it subsided. A moment later Johnny Gibson slid breathlessly into sight around the big generator. Little Bob swung on him vehem- ently. “Quitter! You quitter!” he snapped. ‘Do you think you can run off and leave me to put out this fire by myself?” Johnny stared at him, nonplussed. “Why, I—I just ran around and killed the generator,” he explained. Little Bob shook a blackened fore- finger at him. “I disconnected her myself, the first thing,’’ he retorted. Johnny nodded. “Yes,” he answered. “But you didn’t open the field switch, and that left her live. Don’t you remember what you told me a while ago? That’s why she kept on arcing. I opened the field switch just now.” For a moment little Bob blinked stu- pidly. Then asmile of comprehension overspread his smoke-streaked face. “By gum, Johnny, you win! If you keep on learning like that, I’ll be darned if I won’t have to hunt a new job!”

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May, 1920

i a cae dike Just ‘in ‘Time; He Remembered the Field Switch Warned by the mutter of the approaching thunder-storm, the men in the power-house were ready; but when the lightning flashed across the weakened insulation on the main leads of the generator, it kindled a blaze that they could not control. Nearer and-nearer the ‘flames crept toward the

stator windings; and trouble loomed big, when Johnny Gib- son} the cub electrician, thought of his latest lesson from the:,chief.. He dropped his extinguisher and ran, but not in retreat; for a moment later the flames winked out— Johnny had thrown open the field switch and “killed” the generator

} fi j « LE a RE ig EE IE ae eR pen tn a me one s * <A OET PT A UOT AO Te 7 i EET EL TS ae ene aor Reo i ae ag ee

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q | Popular Science Monthly Feeding Films to the Magic Lantern A reel of them is much smaller and lighter than glass 1G@\ w Photographs © Underwood & Underwood Coney Island, Ellis Island, and _ the Statue of Liberty RAS —--@ are the first three pictures on the film. By simply giving the handle of the machine a twist, each succes-. sive picture will flash on the screen This roll of non-in- flammable films weighs half. a pound; the same number.of glass slides “w6tld weigh about twenty pounds Each suitcase contains one hundred = giass a \ slides. A single roll of 7 the new films contains ai. as many pictures as th ¥ one of these suitcases “My lecture tonight is on New York city,” says he; whereupon he opens his top drawer and takes out—not a large case full of glass lantern ’slides, but a small roll of films that he can easily slip in his pocket PRGA arene! IRAN NS de a at Oe * “~ i The new “‘still” film, invented by Mr. F. H. White of New York, at- Pe t tached ‘to an ordinary magic lantern: the film is wound on rolls - 42 4

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May, 1920- Food from Above Lunch is served on a string where apartments are high Photographs © Press Illustrating Service Willie’s lunch, a banana and a slice of bread with jelly on it, coming down on a string This baby likes apples— and he gets them: though one of these is for big sister “Don’t bother me! Go out and play.” In this fashion the apartment-house mother gets rid of her children until her work is done. When Johnny is hungry he calls up for his lunch Willie has the bread safely in one hand and the ba- nana safely in the other, and is eat- ing both at once ee ge —— ee a ss This woman has three children. How do we know? Because she is lowering Se - three pieces of : Baby soon gets used to looking food—a pear ' ; ‘ up at the window for his bottle. and two cakes 3 ‘ He knows that if he cries par- : 9 he . ticularly loud and long, it will appear on the window-sill and then start down. He freachesup and the bottle is in his hand i This is what Mrs. Murphy saw when she looked out of her window. Mrs. O’Brien, on the floor below, was lowering an apple to the street

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ieee Bas sation x ca a ee oA wernt thicbicit a EIA oh OL Sree Pe Tae NEC ee OS a. wk a 5 ae Iie nae She smears her face with white paste that she kneads on a stone What a Pasty Face! ACE powder isn’t effective enough to give the Macua woman that white- washed look she admires so much in her pale-faced sisters. Her natural hue being a rich, dark brown, powder simply turns it yellow. The Macua tribe lives in South Africa. But the brown can’t possibly show through a coating of white paste such as clowns use. And thus we find her kneeling before a stone as she kneads her daily paste. She smears it over her face and ears, but does not touch her mouth. Where Directories Hang on Corner Posts D”® you ever go from house to house, trying to find out where John Smith lived? And when he lives in a small town he is more careless than ever about giving you the name of his street and his number. But in a Western city the improvement club has hung directories on many of the guide-posts throughout the town. When you want Smith, you look him up under “S” in the directory. There you find Smith’s street and number. You need only find out where the street is and then you can find your way to his house. Whether you be friend, foe, mailman, or bill collector, you will find the corner di- rectory a great help. Suburbs throughout the country will undoubtedly follow suit. ——— ee {In a Western suburb directories are hung at many of the corners These witnesses of a traffic accident are demonstrating just how it happened How Did It Happen? RASH! The limousine ran into the truck—or did the truck run into the limousine? Accidents happen so unex- pectedly that it is often hard to tell who is to blame. In the traffic court at Washington, witnesses of traffic accidents do not have to tell what they saw—they demonstrate it on a small cardboard street corner. There are models of all sorts of vehicles, and each witness plays a sort of chess with them—putting them in their proper places. Jewels First! OLD and precious stones—billions of dollars’ worth—have gone down with wrecked ships for centuries. The bottom of the sea is inestimably wealthy. But its income, is destined to drop off now, for there has been invented a floating safe. You put your valuables in it when you board the ship. The safe, of course, is kept on deck. When a ship goes down, the safe breaks loose and floats. Automatically a red light flares from the top of the safe and a siren horn blows. The life-boats cluster around it, and, if all is well, a passing ship will see the flare and come to the rescue. Valuables are safe, even in ship- wreck, in this floating receptacle 44 The office pet wouldn’t stop nib- bling, so they bought him a muzzle Bunny Wears a Muzzle ETER RABBIT loved to nibble— that’s what got him in trouble—and so do all of Peter’s brothers and sisters. One little brother is shown above effectively muzzled. He is the pet of a large London office, and he walks all over everyone. But, unfortunately, he nibbles. He nibbled the ruffles off a woman clérk’s waist, and he chewed the book- keeper’s trousers. And so the chief bought him a muzzle, and he wears it in business hours. This Peter Rabbit seems to like office life. They’re Keeping Cool on a Warm Job HEN fire and sunshine enter into a combination, even the upper region where telephone cables are suspended may become a warm place. At least, that is what several repairmen thought who hurried out to the scene of damage to fix some cables burned by a near-by fire. The sun from above and the warm air from the scene of the fire below together made the work difficult. The protection afforded by umbrellas seemed attractive to some of the men, and as there was not enough of a breeze to make it impossible to keep the umbrellas in position, sev- eral of them kept cool by thus screening off the sun. — These wiremen fastened umbrellas to the wires to screen off the sun =~ 4 ot MD os Ss hob TH wt 03 = |

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May, 1920 His master lost both legs in the war, so Paulo pulls him around town This French Hero’s Dog Is His Motor PAvLo, the dog, and M. Andrivet, his master, both were wounded in the Argonne. Paulo recovered completely, but his master lost both legs. They have both returned to Paris, and may be seen any day going through the streets together. M. Andrivet sits in a tricycle, while Paulo runs alongside and acts as its motor. He uses a chain drive. The tricycle is equipped with a steering wheel that enables the crippled man to guide. Here you see the two on a main street riding beside a trolley car. Paulo is an excellent motor, and he never stalls. Your Special Hook URSES, cooks, maids, and house- keepers are often known to mix things up—towels, for instance. How can you be sure that your towel hasn’t changed places with somebody else’s? By using an individual towel clip like those below. When you wish to take your towel out or put it in, you simply press a button and the jaws of the clip will open. Thereisa tooth-brush holder connected with each clip. The clips may be labeled. The “safety first’? window-apron for pro- tecting children and window-washers For Betty When She Washes the Windows T° prevent youngsters and others from * tumbling out of upper-story windows, a safety-apron supported from rods mounted in brackets at the side of the window has been invented by F. R. Blankennagel, of Passaic, N. J. The window-apron is supported at an outwardly inclined angle that obstructs little of the light and air. Washing the windows can be done more safely with the device in place to prevent the industrious window-washer from falling out backward. The rods can be easily released from the sockets to which they are secured, and the device removed when not needed. This gorilla, “John,” is acting as maid, lacing up a pair of shoes This Gorilla Has Solved the Servant Problem Yisit the home of Madame Alyse, in London, and you will see.a clever gorilla whose name is “John.” He is reputed to be the only domesticated gorilla in England, and is a past master in the art of acting as valet or maid. Since the animal is so adept in training, perhaps gorillas will be taught to be serviceable as substitutes for ‘‘hired”’ help. No Mistakes Here AN automatic score-board, so arranged that. only the right score for each player can be registered, and no mistakes can be made, is an invention of Mr. Frank A. Garbutt, vice-president of the Los Angeles Athletic Club. The size of the score-board is four by five feet.. The names of the two players appear on a sliding blackboard, which can be removed and replaced in a moment. On the lower blackboard is, the score under their games. At the top is the indicator that shows who is “‘in.”” Now, here is the special feature of the device which. will appeal to all ball- players: when the cord is pulled that shows the player’s score on the indicator at the top above the blackboard, a mistake cannot be made giving the score to the wrong player, because the indicator ‘in’? when moved to one side auto- matically locks the other. Individual towel clips with tooth-brush holders attached will help keep your family well 45 An ingenious score-board which prevents a score-keeper from pull- ing the wrong cord and registering the score to the wrong player : x i!

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j : TTT Sere nsvwbie ea eee 7a napselepree ok Gul 2 ieash Sy see Popular Science Monthly Scrape the food off your pots and pans with this many-sided scraper Scraping the Pan ATER won’t always wash off the food that clings to pots and pans. They must be scraped. And now there is a scraper of many sides that will do the scraping. The sides are of different lengths, and there is a dent in the center of the scraper that enables you to grasp it firmly. Near the shortest side there is a hole by means of which you hang it on the wall. Sermons by Telephone FALLING rock in a mine in Wales hit Sam Pritchard, a miner, and injured him so severely that he thought it would be a long time before he could hear the sermons preached in his local Baptist church. But three friends determined that he should hear the Sunday service, though he was unable to go to the church. They set. about rigging up a telephone for his benefit. Now he can lie in bed with the receivers at his ears and hear every word of the sermon. The chapel is some distance away, but the words of the preacher come as clearly by telephone as they would be heard in the building. An edible gourd called a bean. It is not as nutritive as an ordinary bean, but its bulk makes up for other deficiencies When a Bean Is Not a Bean It’s a Gourd NE so-called New Guinea butter-bean will provide a meal for a whole family. If the diner does not object to the slightly bitter taste, he may be satis- fied with his dish; it is indeed a cheap one, for the seeds of this curious vegetable sell six for fifty cents. But the remarkable fact must be announced that the so-called bean is not a bean at all—it is a gourd! Advertised extensively as a giant mem- ber of the beany tribe, this gourd springs up as by magic when the seeds are planted after the danger of frost has passed. Like the ordinary pole-bean, it will grow whether cared for or not. In food value it compares with the summer squash, and by no means has the nutritive value of true beans. Drop a few seeds of this remarkable bean, and almost overnight, like Jack’s ‘‘bean-stalk,” the great gourd will spring up. Itis an interesting addition to the gar- den, and well worth the sum spent for it. An ordinary lamp - wick, soaked in grease, will keep the pan in condition Greasing the Griddle “PUCKWHEAT cakes—put ’em on the griddle,” sings the negro comedian. But first you must grease the griddle. How? Take a piece of lamp-wick, soak it in grease, and clamp it in a wire frame. It will distribute the grease evenly and may be used for a long time before the wick need be changed. If you would have plenty of griddle cakes, make one of these greasers for your cook. To Correct Typewriting TENOGRAPHERS know what a tough job it is to make erasures on a type- writer when carbon copies are being made. A card slipped between the carbon and the under sheet of paper may work some- times, but often it causes a smear. Here is an arrangement for eliminating the smear. A padded flat bar is attached across the typewriter just at the place to permit the sheet requiring erasures to rest over the pad. It is adjustable and can be removed easily when not needed. The carbon sheet passes under the bar-pad while the sheet upon which the erasure is made passes across the upper face of the pad. om m * ee Not many people can lie abed Sunday morn- ing and hear the sermon at the same time! The paper rests upon a pad; the carbon paper passes below the bar and does not smear the copy a a ee al ee ee ee ee a

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‘May, 1920 bits of twig fly upward. _Mud-Guards in the hie NE would scarcely imagine that air- planes need fenders to keep misty clouds’ from splashing into the tonneau, and they don’t. guards to keep the mud of flying-fields from spattering all over their perfectly good propellers that are whirling at a couple of thousand revolutions a minute. These little gobs of mud, bits of twigs, and pebbles hit the whirling piece of valuable timber a terrific blow—at the rate of five hundred miles an hour, in fact, for this is the peripheral speed of a modern air-screw. Every propeller is carefully balanced. A bit of wood will set up a tremendous strain on the crank-shaft of the engine, and the bearings. Hence air- plane wheels now have mud-guards. An Electric Hair-Cut D Nenies vce electric motor operating an are rangement of suitable cutting blades, the electric hair-cutter is the invention of a Berlin barber. Instead of laboriously working a pair of scissors all day in the art of cutting hair, the electric machine needs only to be guided in the proper manner to do its work effectively and quickly. Rheostats regulate the current to the requirements of the motor and enable the barber to work the cutter at the de- sired speed. Electric hair-cutting, clipping, mas- sage, shampoo, and singe lighten the barber’s work. c As the airplane speeds across the ground, pebbles, mud, and ‘ The mud- guards’ — the propeller But they do have mud-.. Sr ope “How the Natives ‘Carry Water in Old: ‘Siam 7ATER-BOTTLES made of animal a ¥%. skins?»-.Why?’’ one might ask. ~ Within twenty degrees of the equator, onthe Indo-Chinese peninsula, the little country Muang Thai, as its inhabitants know it—Siam, as the rest of the world recognizes it—basks in the tropical sun. Its lofty mountain-peaks rise above the mists, clear-cut against the sky. Forests of teak, fields of rice, and endless dense jungles of blowing palms confront the visitor in this strangely beautiful country. Here, in the various steps of climate encountered from the tropical coast-line to the temperate region of upper altitudes, one finds the people doing their work in the most primitive ways. Where water must be carried, instead of conveying it in pipes by a system of pumps, the natives simply carry it by hand. In order to carry the water exactly as their forefathers did centuries ago, the Siamese have made water-tight bags out of animal skins. The bags are light when empty and easily carried when filled. This boy is having his hair cut by anew electric machine © Keystone View Co, The Siamese carry water in bags made of animal skins, just as their ancestors did ° 47 After lifting and moving a load to its destination, this truck elevates. the: orm to the shelf upon which it is to be stored Store It by~-Truck. } . paeduhapodicleg 3g run by storage bat- teries saves a lot of time and labor in its useful service in storage-houses, ware- houses, laundries, and freight depots. It picks up boxes and kegs and conveys them to the place that has been designated for them. , But that is not all: it elevates the load until it reaches the height of the shelf or the freight-car level where it is to be placed. The driving power is separate from the lifting mechanism, this being controlled by a small motor on top of the truck, which will lift a 4,000-pound load to a height of seventy-six inches: It is said that by its use store-room capacity can be increased from 200 to 500 per cent. Electrify Your Brush ARROWING tales will make your hair stand on end, and so will the new electric brush shown below. In fact, it will even make your hair curl. The brush has metal bristles, and: on its back it carries a small box inside of which is a magneto. To operateit you simply work a convenient handle. The brush was intended originally for invigorating the scalp. But new uses are being found for it daily. For in- stance, it may also be used for massaging the face—not directly, but by means of a massage attachment that can be ap- plied to it. © Press Illust rating Service What makes his hair curl? The electric brush he is using

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~ ween piconet nwestin is Dt ERGY A RAE PCIE a Pi ARMM be MT OE e s “THE gas-holder is to the city that uses artificial gas what the reservoir is to a city’s water supply. The water used by a city is not forced directly into the city’s distributing mains, but is pumped from its source of supply into reservoirs and stored until it is used. Water reservoirs are always located on hills, so that the water may flow downward, seeking its level in the mains. It is thereby distributed to the consumer under a normal pressure. , ae The gas-holder fulfills these requirements .in supplying gas. Instead of being. lo- cated on‘a hill, it is placed whenever possible at the lowest point in the distribu- tion system, so that the gas flowing out of it, owing to its being lighter than air, will rise of its own accord to the points at which it is con- sumed. The weight of the holder containing the gas supplies it with the necessary pres- ——— a sure to overcome the friction caused by the gas flowing through the mains, and thus it reaches the consumer with pressure sufficient to meet the demand. Were it not that the holder supplies this energy as well as the gas itself, the gas could not flow continuously through the mains to the consumer. It may surprise some people to learn that the total floating weight of the holder—that weight which the gas is compelled to lift—is more than twelve hundred tons. This weight presses down on the gas contained in the holder to the extent of a little less than half a pound to the square inch. The gas-holder comprises a tank, which rests on a concrete foundation and contains sixteen million gallons of water; a guide-framing, which guides the holder up and down; and the holder itself The gas is not allowed to enter the distributing mains under this pres- sure, however. It is reduced or throttled back by governors at the works, giving the consumer about one tenth of a pound to the square inch. Three elements make up the holder: first, the tank, resting on its concrete foundation and containing sixteen million gallons of water; then the guide framing, secured to the outside of the tank to guide the holder in its movements up and down as gas is let Deadening Noise with Cotton NSTEAD of putting cotton plugs in the ears to stop the noise of the metal gear in machinery where rasping noise is not wanted, the cotton has been put to use in making the gear itself noiseless. After trying many kinds of materials, metallic and non- metallic, the choice was narrowed down to the use of steel or com- pressed cotton. The steel gear was found to make such-a nerve-racking noise that it was impossible, so the cotton gear was tried. Thus the fabroil gear was developed. It was at first designed to work noiselessly in the average gear-train. Specially selected cotton is wound around a drum, capped and bottomed with steel shrouds of the required size. Then the whole is put into a hydraulic press and brought to the proper dimensions. The resulting gear wears as well as cast-iron, and produces no noise when used in connection with metalic parts. Its elasticity gives it a closer surface contact, and is not affected by steam, hot water, or any condi- tion that would injure iron gears. Cotton gears may be used*in automobile en- gines, printing- Gear wheels made of compressed cotton to deaden the noise in the “gear-train,”’ the series of interlocking wheels attached to d oth automobileengines, pressesandother printing - presses machines. _and other machines 48 ° Popular Science Monthly The Gas-Holder—a City Reservoir in or out; then the holder itself, which is made up of five sections, folding up in the holder tank like a tele- scope. When the holder contains no gas, all five sections tele- scope in the tank and are flush with the top of the tank, which is filled with water. As gas is let into the holder through the inlet pipe which passes up through the water in the tank, the first or inner section, which carries the roof or crown, is in- flated; and when it reaches the top of the tank it picks up the second section by means of what is known as the cup. This cup runs round the whole outside cir- cumference of the holder, forming the bottom edge of each section, just as if the edges were turned over and bent upward to hold water. As each section rises it picks up the grip or in- verted cup of the next section, and as each cup is filled with water, there is formed what is known as the water lute, or seal, to prevent the gas from escaping. When the holder is fully inflated all the sections are lifted with their respective cups filled with water and the lowest edge of the lowest section is about thirteen inches below the surface of the water in the tank. This prevents. the gas from escaping at the bottom. A gas-holder is the most expensive single piece of equipment that a gas company is called upon to provide; yet, in spite of this, from the stand- point of economical operation it is the cheapest. -~_ ket ee ei m em ew ee A oO ee |

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May, 1920 What Makes a Baseball Curve? It is simply a matter of atmospheric pressure blow vigorously between the two separated ends. The leaves of paper move toward each other and cling together. Obviously, the mov- ing stream of air exerts a suction effect upon adjacent bodies. In more pre- cise language, the atmospheric pres- sure between the paper leaves is lowered by the air velocity action, and the unaltered pressure of the air on the outside crushes the paper leaves together. Blow through a distended envelope that has been sealed and that has had its ends slit open. The side walls collapse and the envelope flattens, crushed by the greater pressure of the still air outside the envelope. Suspend a cork from a silk thread, and with a“‘straw,”’ such as those used at soda-fountains, blow a stream of air past the cork at a distance therefrom of at least three fourths of an inch. The air pressure on the breeze side of the cork is reduced, and the normal atmospheric pressure on the quiet side of the cork pushes the cork over and into the stream of air. Hi: up a sheet of paper and Not a New Discovery Similar experiments may be per- formed with water as the fluid medium instead of air, using a submerged hose to furnish a high-velocity water cur- rent. Let the nozzle of a_ hose delivering a quarter-inch stream of water at high pressure be thrust under the surface of a body of water, and let the stream pass between’ the sub- merged hands, held with the palms an inch apart. Marked suc- tion will be felt and sen- sibleeffort will berequired to keep the palms apart. Examples might be multiplied demonstrat- ing that, where a portion of a fluid is moving faster than an adjacent part, the pressure in the higher-velocity region is less than in the lower- velocity region. This is not a new discovery in science: it has been known for nearly two hundred years. Never- theless, it is of interest to all of us, since by this By Lindley Pyle allow the string to untwist, thus putting the ball into a high rate of rotation. The air close to the ball is soda “straws” in your mouth and blowa stream of air past each side of the ball. In the diagram Fig. 1 the short arrows indicate the swirl of air rotating with the ball, while the long arrows represent the air ks “7 i Fig. 1. Short arrows indi- cate the air rotating with the ball; long arrows, the air from two straws If you slit the ends of a closed envelope and blow through it the result will be the same as in the case of the paper % @%% ad Fig. 2. The curve of a baseball, fol- lowing the prin- principle we may explain the curve of a baseball. Tie one end of a six- foot length of string to a tennis-ball, and fasten the other end to the ceiling of a room free from air currents. Spin the ball for several minutes in one direction so as to twist the string, then Blow through a straw at a suspended cork; the pressure of outside air forces the cork into the stream of air ciple of air cur- rents indicated in Fig. 1 above dragged into motion along with the surface of the ball, as may be seen by bringing the smoke of a cigarette into close proximity. Now, while the ball is spinning (not swinging), place two 49 that streams past the ball from the straws. It is plain that the net effect of the mingling of these air currents is to cut down the velocity effect at L (where the two currents are in opposite direc- tions) arid to main- tain it at H (where the two currents are in the same direc- tion). The preced- ing experiments have demonstrated that the air pressure is consequently greater at L than at H, and one is not surprised As soon as he stops blowing the sheets of paper will come together and cling. Why? Because the at- mospheric pres- to see the ball pushed sure between them. has been °C toward H. Discard the straws, and produce a breeze past the spinning ball by swinging it to and fro like a pendulum. The effect upon the spinning ball as it moves bodily through the air is the same as when the breeze past it is produced by blowing. In the diagram Fig. 2, when the spinning ball is pulled aside (by its string) to a and then swung toward b, it corresponds precisely to the case just described, except that the breeze past the ball is due to the bodily motion of the ball through the air. Instead of reaching b the side thrust on the ball carries it toc. On the return trip it goes to d, and on the next swing to e. If the direction of spin be reversed the plane of the pendular vibration rotates in the opposite direction. The Ball ‘Follows Its Nose’ . The front of the moving ball is often termed its “nose.” It will be noted that the path of the moving ball deviates in such a direction as to lead one to say that the ball “follows its nose.” The experiments have led directly to the case of the curving baseball. The delivery of the pitcher is such that the ball leaves his hand with a rapid spin, and the ball follows its nose, whether it be in-shoot, drop, or what not—for a reason amply illustrated by the foregoing simple experiments. lowered by the blowing and it is overcome by the steady pressure from without

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Peng hte gan lin 8 hk i wo sinh: grr abe Rae ean le se rata SO a ra 7 A ATR sa a adh alii ago. soe nae eran ve i AN AP AR ln tists Sena eS ee wn Sein fis canary pica ipeteiniennd tas atin tons atte oobi a INBI Rcpanete tay Tsim aes. tt a re em areas ae an tS Teeth Ait camming dioica hentia The slanting end-wall of the tank permits the fowl to escape from its sudden bath An Unexpected Plunge for the Poultry UCH time and labor can be con- sumed when it is necessary to dip poultry conforming to the rules of the poultry-yard hygiene. Imagine the task of separately immersing two or three hundred fowls! Mr. Alva F. Randolph comes forward with an ingenious patent by which the members of the feathered community can be given a highly effective plunge-bath in whatever liquid may be required. From a compartment the chickens walk across a tilting bridge, and, one at a time, are gently let down into the liquid. The apparatus works automatically. As the fowl steps past the central pivot of the bridge the plat- Popular Science Monthly Laying Concrete Under Difficulties AYING a concrete pavement in a narrow alley lined with irregular rows of fences and telegraph-poles is the feat performed by the city of St. Louis. The fifteen-foot alley was so narrow that teams couldn’t turn around in it, so all of the materials had to be delivered and spread upon the sub-grade before the actual concreting began. Because of the irregular line of sheds, fences, and poles, a difficulty had to be met in the placing of suitable forms along the sides of the alleys. Iron-bar guides were used to overcome this difficulty, the long, and were set in sufficient numbers to avoid the interference of the projections along the sides, which in some cases varied as much as six inches. The irons were driven to grade along a line set between the stakes, the center of the alley to be four inches lower than the sides. Then came the difficult job of laying the concrete in so cramped a space. The lower course was deposited within the reach of the ordinary boom-and-bucket mixer, a space of about fifteen feet. To grade it properly it was tamped lightly and then covered with the top mixture, which Wrtep eet h eebe baa wdy This alley was a difficult problem because the teams distributing the concrete material could not turn around in it; they had to deposit the material as the work progressed bars being made of 34 by 11% inch strap- iron on edge, having the two ends turned over for about a foot and sharpened for driving. The bars were six or eight feet form tilts down- ward, and the sur- prised chicken finds itself be- ing immersed. A slanting gangway formed by the end of the tank per- mits the dipped fowl to walk out and dry itself. As the bridge tilts down, a_ plank slides across the opening at the other end to pre- vent the other chickens from coming on the bridge too soon. ‘Here we see a templet being moved across the wet concrete, sliding upon iron guide-bars at the side. The bars are six feet long Building Trees for Birds OULD you have wrens, flickers, owls, or bluebirds, or would you like a few of each in your garden? There is a certain way to get the very birds you want, and that is to make a tree for them. Dr. B. Harry Warren, of West Chester, Pa., makes imitation trees to attract birds. He makes them of cement, cork-bark, and other suitable material, and just at the place where a wren, an owl, a flicker, or a woodpecker would look for the desirable location of a nest, a cavity is made ready for the home- building birds. In the tip of each stump-like limb of the concrete tree there is a hole leading to a nest cavity of exactly the right size to accommodate the bird desired. The hole for the wren is one inch in diameter, and the nest cavity is in a piece of drain-tile. Four nests are arranged for in this tree— three in the limbs and one in the trunk; and.it is expected that, besides the house wren, a bluebird, a flicker, and perhaps one of the smaller woodpeckers (such as the downy woodpecker) will find free lodging in the tree. 50 was struck off with a templet sliding upon the iron side-guides. The bars were then drawn out and the space filled with wet mortar. Planks laid on top of the concrete on both sides of the alley served as a plat- form for the roller-man and the finishers. For a narrow alley where there is not enough room for a team to turn around, the problem of laying a concrete pave- ment calls for such ingenuity as has been displayed in this case. The number of protruding sheds and irregular fences, punc- tuated by the intruding line of telegraph- poles, would have hindered a less resource- ful effort at spreading the cement floor. Making a concrete tree. In the limBs and in the trunk are openings leading to nest cavities for several birds

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May, 1920 Making Gas Connections Fool-Proof | deen a child may safely be intrusted with switching the current of an electric light on or off. If you havea contact socket in the wall of your room, you only need a long enough insulated double wire with a contact plug to utilize the electric current for your reading- or piano-lamp, your toaster, your curling-tongs, or your electric iron. Even permanent gas fixtures are by many persons considered less desirable, because there is always the possibility of accident through gas escaping from a stop-cock carelessly or accidentally opened. With temporary connections, by means of gas tubes, the danger is even greater. Many of the objectionable features of temporary gas connections, however, are eliminated by a new contact plug. The socket is attached to the end of a service pipe, and is set in the wall flush with the surface. Connection with a reading-lamp, gas-heater, or any other appliance is made by means of a gas- tight and flexible metal tube, the con-

necting plug of which is inserted in the wall socket and fastened by a quarter turn of the plug. Turning the plug in the socket not only securely fastens the flexible tube, but at the same time turns on the gas. If the plug is accident- ally removed from the socket, the gas is automatically shut off. In the daytime, when the gas connection is not» needed, the plug of the connecting tube is removed from the socket, which, being set in a brass plate and flush with the wall, is neither conspicuous nor unsightly. The same socket may be used at dif- ferent times for connections with various fixtures, such as piano- or reading-lamps,. heaters, toasters, per- colators, or chafing-dishes. The same metal tube may be used for all

of these fixtures, or, still better, each may be supplied with its own tube of appropriate length, which is left attached to the fixture. Push the plug in the socket, give it a quarter turn, and the gas from the service pipe will flow to your lamp or heater * An Airplane that Really “ — Off” —_ i order to enable an airplane to hop off without the’ necessity of running along the ground, Earl. Atkinson has invented a novel launching The engine pumps compressed air into a tank carried within the fuselage, and a connection device. with this tank extends to two cylinders fixed be- neath the wings of the machine. The airplane °F” @) rests upon these metal legs until it is ready to start. When compressed air is admitted into the cylinders, the legs are thrust out in such a manner that the machine literally bounds upward and is wafted away under * Here is an invention that the inventor claims will enable an airplane to “hop like a giant bird wie COMPRESSED AIR TANK How to feieeai a Watch REMEMBER the last time you were near an electric motor and afterward You took it to the watchmaker and he said it was mag- your watch wouldn’t go? netized and it would have to be demag- netized—one dollar, please! The accompanying illustration shows what a simple operation it is to demagnet- izea watch. It is tied to a piece

——————

He is demagnetizing his watch by passing it through an electric coil while he spins it rapidly

of string or ribbon, twisted so that it spins around when re- leased, and then, while it is spinning rapidly, it is passed through a coil of wire carrying an alternating current. The opera- tion takes about half a minute. The coil shown in the illustra- tion is wound with 196 turns of insulated copper magnet wire wound in fourteen layers of four- teen turns to the layer. It is supplied with lamp-cord leads, tapped, and shellacked. For operation it is connected directly to the alternating-current supply of 110 volts by removing a lamp and inserting an attachment plug. Great care must be taken to ascertain that the lighting supply is alternating and not direct current, since if the coil is connected to a _ direct-current supply, the watch will be mag- netized more strongly than before. fl

<A Py An PROJECTORS

the power of its own propellers. The airplane can be given a free standing start by the im- pulsive compressed air charge. Means that normally shut off communication between the air-reservoir and the hollow “‘leg’” are adapted to open automatically just when the airplane, under the increasing thrust of its propeller, is lifted to clear its landing- gear from the ground. We should like to see the commit ourselves on the subject of practicability. The Name in the Ceiling ENSECSTEE!” garbles the subway guard. The car is crowded; you can’t see the station signs; you can’t understand the guard. You don’t know where you are. Can this situation be remedied? The London Metropolitan Railroad is trying to remedy it by installing in all the cars electrical station signals. Just after the train leaves one station the name of the next station flashes upon the ceiling. The ceiling is divided into panels, and there is a station name in each one, placed consecutively. The signal system works automatically. There is a small striker on the track, a short distance beyond each station, that operates a set of switches in the ceiling of the car. The motorman adjusts the switches before he starts out, and the striker does the rest. As one sta- tion name disappears the next one shines forth. Everyone can see the ceiling, and thus there need be no confusion every time the train stops. If station flashing proves successful, perhaps a map will be added to each panel. It is planned to have the map cover the district surrounding each station, and to include the names of the leading stores and theaters. propellers work before we .

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ie endlibathes apc cesperesanenione ee en LL I tag go / Phim el eit oa sonoma EAT AT ae RO po Nog Se Ma Turn on the Cold and Let’s Have Winter Popular Science Monthly pleted its growth in EFORE we turn on the steam to make artificial spring and sum- mer for the greenhouse, we must turn on the re- frigerating system to produce artificial winter —if we would produce certain plants out of season. Experiments by Dr. Frederick Coville, botanist of the Depart- ment of Agriculture, seem to demonstrate that some plant life, such as the blueberry; can thrive only when it has passed through the cycle of climatic changes due to the seasons. From his experiments spring and sumrrsr, and later in the season has gorged its twigs, stems, and roots with starch and other storage foods for early spring use, it becomes dormant and, shedding its leaves, re- fuses to grow again at the temperatures which in spring and summer would be most favorable to its growth. But after the plant has been exposed to prolonged chilling it is ready to grow. During the period of chilling there occurs the transformation of stored starch into sugar, which the fact was definitely established that when a blueberry plant has com- if happened in the Maine woods. A lineman was sent out to locate an open wire. He came upon the break, but found that about five hundred feet of the wire had entirely disappeared. He went off to get enough wire to fill the gap, and when he returned he found a large bull moose there. The moose had returned to the scene of his crime with the wire wrapped around him and a long end trailing behind. He _ stood there grandly sizing up his enemy, and the enemy in the meanwhile ’ gtealthily picked up the end of the moose’s wire and tied it to a tree. Then he mended the. break with the new wire. When his work was done he turned his attention to the moose, which was still standing around. Armed with a long sapling, he chased the moose around two trees until the wire was so short that the moose tripped over it and fell. In order to chill certain plants to turn their stored starch into sugar for their food, the greenhouse is equipped with a refrigerating system. Get Off the Wire, Moose! ‘Who stole my wire?” asked the lineman. ‘“‘I did,’’ said the moose (speaking with his eyes). This incident actually happened in the Maine woods is essential before the plant can use it for food. The lineman came as close as he dared, cut the wire, and then ran for the nearest tree. When he was sitting safely on a branch he looked down at the moose, and saw that the animal was still on the ground, panting for breath. The wire was wound tightly around his neck. But in a few minutes he had re- covered his wind. He jumped up and trotted off with just a few feet of wire to call his own. According to the lineman, the moose had a good spread of antlers, but the man didn’t think that the short piece of wire wound around them would get the moose into trouble. Yet, a short time before this telephone catastrophe, a moose near Lake Sourdnahunk ran around with a piece of wire in his antlers, got caught in the branch of a tree, and died there. A moose’s antlers are powerful and are very useful when he fights, unless they get caught. The New Tie-Nipper Spikes Rails in Less Time with Fewer Men SIMPLE iron tool that is stronger and more rapid than the working power of two men is the new implement employed by a Western street rail- way. It consists of a lever, a handle, and a head and foot. Ordinarily the laying of rails requires the use of two men at the rail-end, where each man with a steel bar guides the heavy metal, while other work- men spike it to the ties. The new arrangement re- quires only one man. He adjusts the foot of the } lever. The tie is then firmly held to the rail while the spiking is done by the laborers. A test demonstrated that using the new tie-nipper the work of one man could be dispensed with, and that the work could be done in one third the time required by the old method. The new tool weighs twenty-six pounds when equipped to handle a seven- inch T-rail. The foot of the device is made in various lengths to fit dif- ferent heights of rails, and is ten inches high from the nipper under the tie, places the head over the ball of the rail, and grasps the nipper.” Courtesy Electric Katiway Journal Spiking a rail that is held firmly to the ties by a single man using a “ tie- The old method required a man on each side to hold the tie 52 - horizontal base to the pivot in the top bar. The lever is about six feet long.

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May, 1920 ‘How to Close All the Windows at Once In the picture at the left the inventor, Mr. L. M. Phelps, is - placing a single drop of water from an eye-dropper upon a strip of blotting-paper. As if by magic the drop of water causes the mechanism instantly to start closing the window. The moisture detectors can be made so sensitive that they will close at the first drop of rain Presto! The drop of moisture soaked into the blotting-paper strip and the rain-trap is sprung. The spring fastened to the win- dow-sash is released, so that it draws down the sash as noise- lessly as if it were drawn down by hand. An inside connection with the other windows also brings them down, and the whole house is made window rain-proof UT an automatic window-operator on The person who goes away leaving the of paper outside causes the mechanism to one of the windows, connect all of the window of his room open need rot break operate a spring, and the spring draws windows suitably on the inside with the an important engagement to rush back at down the sash. An inside connection of ‘inside sash control,’ and connect the the first drop of rain. The automatic all the sashes on the same side of a house system with an alarm-clock. At a desig- window-operator will close the windowsfor can be made, so that only one automatic nated time every one of the windows will him. Little strips of blotting-paper serve. operator outside is necessary, the working be closed. Mr. L. M. Phelps, the in- as moisture detectors, and can be madeso of this “master sash” serving to close all ventor, claims that all the windows in the sensitive that they will operate to close the the windows. world, if properly connected with his windows when the dew falls, or can be If it.is desired to have the windows closed automatic operator and sash control, fixed to work only when it rains. at a certain hour of the day or night, the could be closed simultaneously with the The automatic window-operator is at- system can be connected with an alarm- fall of a single drop of moisture upon the tached to a sash equipped with balance clock, and at the fixed time click! click! will sensitive strip operating the “‘master sash.” weights. A drop of moisture on the strip be the only sound as all the windows close. An Eskimo Duel Is The Camera Takes Its Fought by Tongue Own Pictures When the Eski- I “% 7OU’RE a mean, Remon pee oneal F a tender young plant doesn’t die of ugly brute, and land fight, they ~ fright when it sees eight large electric- i your face reminds me do it with their light bulbs staring it in the face, then its it of a chunk of ice,” tongues; they ° growth will be automatically photographed q said one Eskimo to take turns at with the aid of those same eight bulbs. another, and the sur- singing, danc- They are part of a new automatic motion- A . ing, and hurling : * 4 rounding villagers ue eneruetie picture camera recently invented. There roared with laughter. k are two timing clocks, one for switching o r t ch s ’ g n Tinnt'a Donen: than tiaiels aie yane gna the lights every so often, and the other for mos in Greenland’s surrounding vil- shutting off all power when the necessary icy mountains fight lagers decide number of exposures have been made. their duels—with which one wins Two relays start and stop each exposure. You set the clock to the interval desired. Usually, in the case of growing plants, this interval is one half hour. The only attention the automatic camera needs is a daily wind- i ing. Heretofore, when i long-period pictures were made, _ three H camera-men were needed. They worked in eight-hour shifts. But the new camera will work by itself, and may be used for photograph- ing any kind of slow growth, such as the development of an animal or insect, as well as the growth of plants. their tongues. They pick a suitable time and place for meeting and then notify the villagers. They take turns at singing, dancing, beating drums, and hurling sarcastic re- marks at each other. While one opponent performs, the other. one must grin and bear it. Then he gets his chance at tongue-lashing. They are sec ee eae both given several opportunities to tell the baleful glare everything they know and think about of eight electric- _each other. They even draginthesins of light bulbs; its their ancestors, if they can do it in a growth is being particularly insulting fashion. photographed by Which one wins? The one who can get 22 automatic the greatest number of laughs out of the ™0V!"8~ Picture 3 = : camera. This audience. And as for getting satisfaction Comera is very —is it not much more gratifying to tell a useful in photo- man just what you think of him than to graphing - plants stab him in the ribs?—CHRISTIAN LEDEN. of slow growth

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ee et) i inj Sl, iE ine A PR Reo, Popular Science Monthly A catcher always runs the ‘oo ‘risk of being hurt by ball or bat. He wears a _ heavy mask, a chest - protector, and knee-guards; but they don’t prevent him from having frequent sprained or broken fingers Earl Smith, catcher for the New York his signaling with Giants, lets us in on his right hand. He some of his secrets. stands behind the He posed especially batter, and, after siz- for the POPULAR ing him up, signals to SCIENCE MONTH- the pitcher for the LY. He is here call- kind of ball he thinks ing for acurved ball the batter.can’t hit a een « = ~ > a - ae Cg ot SN - . : em =, pac rye onan ¢ pias NNN ACN hci ala ncaa etna seth ibianti in wei So nt — In the days of Nero ij this used to mean tie “thumbs down”’— + Be! he must die. Now it means “‘send over a curved ball.” How times and 4 amusements have wa changed together! A knuckle ball is a hard ball to throw se and a hard ball to ie signal for. The i Bid catcher knuckles Bee down his first two te 5 af fingers and lets his thumb and the Sie other two stand up cell straight. Try it! RS The waste ball sig- nal above is not very different from the fast ball signal. His fingers are still stiff and straight, but they are parted —with the thumb and the first finger clinching together 54 The Catcher Gives the High Sign When he tucks his thumb under his closed fist he’s not getting ready to punch someone: he’s simply signal- ing fora spit ball, hoping for the ver- dict, ‘‘He’s out!” When he holds his fingers close - to- gether and keeps them very straight, he’s calling: for a fast ball. To the uninitiated all balls look alike, but the skilful moundsman uses change of pace

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May, 1920 What to Do with an Old Barroom Under prohibition books supplant beers and toys the toper © Press Illustrating Dolls and toys now hold forth on this corner formerly occupied by a barroom When saloons sold alcoholics no sailor dared enter and buy. Now the Y. M. C. A. in Hoboken uses an ex- saloon as a lounging room for sailors © att toe } oe ian ‘i 2 ik Wi lh Prohibition is a very good thing for this *“One Lone Ranger,” said she, with her foot on the bar-rail. It was young rascal. He has learned the bar- neither a hard nor a soft drink—it was a book. This little barroom rail step already—the first step downward in the Hotel Majestic, New York, has been turned into a book store Imagine the feelings of the man who stands for a fitting No longer is free lunch served here. “You have to buy it, and on the very spot where he formerly drank his beer the only thing you can add to the lunch is a package of cigarettes 55

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Aska WL i AN PRPS NTR Ti ee Nant nN 9 taba Fe i cine = areaty’ Sel omilicgtes,, sag 8 ete TES & era ea Nee Sane NG! IM PELE TIOGA ALOIS © aa bili 7 ea Pome de Popular Science Monthly A Mechanical Genius of the Back Woods Without schooling or training of any kind, he has made himself a cunning artificer in wood and stone By A. F. Harlow “4 SHOMAS COKE RICE is a Ten- nessee moun- taineer who lives in one of the wildest and most inaccessible portions of the nar- row, high, deeply seamed plateau known as Walden’s Ridge. An almost unbroken forest extends for sev- eral miles in all direc- tions from his home, and a lone cabin three miles away shelters his nearest neighbor. In this lonely spot he has lived for twenty of the twenty-five years of his life. He has tain stock, accounts for the indomitable courage with which she and her children endured their trials. As Coke grew up, he showed a disposi- tion to tinker with the few tools at his dis- posal, and began to do repair jobs-.with re- markable ‘skill. One _of his first real crea- tions was a jumping- jack, a crude wooden toy manipulated by a string, the original of which he had ‘seen in the possession of a child at the settle- never spent an hour of his existence in a school-room, and until idea. the draft caught him in 1918 he had never been more than twenty miles from Yet he is a cunning artificer in Had he had the opportunity for mechanical training, he might have been a _ wonderful an in- home. wood and iron. craftsman, a manufacturer, ventor—who knows? I first saw “Coke” seven years ago. At that time his mother “believed” he was about eighteen years old. The mother is a fine example of the Spartan heroism and stolid endurance common to the Southern mountain women. Her husband left her when Coke and his sister had not yet entered their teens. He rode away on the only horse pos- sessed by the family. The agony of the bitter struggle with poverty during the years that followed can never be told in words. The mother, assisted by the two children, succeeded in raising each year a tiny patch of vegetables near the house. She would walk through all kinds of weather to a settlement six miles away, where she did any sort of work she could get to do. As the children grew older, the three were able to put half or more of their three-acre clearing into cultivation. Their only implement was an old bull-tongue plow, and, having no horse, they took turns pulling the plow. Then there “Coke,” as he is called, made every part of this forge and blower, excepting the sprocket wheels and chain. And the construction was all his own If he had gone to school, he might have been a great inventor. Perhaps it is not too late yet for the young mountaineer to have his chance was wood to be cut and brought in from the forest, and in this work the children each ‘“‘made a hand.” The mother has a strong strain of the old Cherokee Indian blood in her, and this, combined with the hardy moun- Thomas Coke Rice, a Tennessee mountaineer, and his mother and sister have lived in the wilds all their lives. He never went to school, yet he is an expert work- man in wood, stone, and, what he likes best of all, iron 56 ment. When I first ran across him seven years ago, he had al- ready made consider- able progress. He had built a little forge out of stones and earth in the yard, and was doing blacksmithing. frow, an edged tool used in the country for splitting palings-and old-fashioned shingles, he had split out two slabs of oak for the sides of his bellows, and had With a shaped their edges with his jack-knife. A piece of an old buggy-top ‘served for the lea- ther portion .of the bellows. He hacked and whittled out a handle and frame, and soon the forge was in operation. Among his first products were table-knives and_ butcher- knives, most of which he made out of old wagon-tires. He ap- plied wooden handles, making the tiny rivets with which they were fastened, and sharpened the blades on a grindstone which he had slowly and laboriously fashioned from a chunk of mountain sand- stone. He occasionally found sale for these tediously made tools at the settlement at small prices. It so happened that I did not see Coke again until the summer of 1919. I found that he had greatly enlarged his list of products. Instead of a bellows he now has a rotary blower, of which he made every part except two sprocket wheels and a chain, which he salvaged from the wreck of two old bicycles, and some scrap tin with which the fan is

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May, 1920 encased. He got the idea of the machine from seeing a small portable forge in operation at a coal-mine several miles from his home. He has equipped his blower with a treadle as well as a crank, so that he can run it with both hands free to tend his fire and turn his iron. And that blower creates some wind, too! Coke apologized for the unevenness of the blades on the fan. “I didn’t have no square to true ’em up with,” said he. He apologizes thus for many of his products. ‘“‘That ain’t made just as it ought to be,” he will say; or, “T could do better next time.”’ Heseems to have no occasions, Coke some time ago found in a deserted cabin the burrs or grinding portion of a coffee-mill. He took this home, cleaned and removed the rust from it, built a box for it, forged a crank and attached it, and then, being in a hurry, stuck a piecc of corncob on the crank for a handle! The cob does just as well as a polished handle; the calloused palms of the family don’t mind its roughness. In this mill the family not only grind their coffee, but grind their corn into meal. This makeshift handle is an indica- tion of the fact that Coke doesn’t care can make them of all sizes, from the big five-inch-bladed jack-knife suitable for skinning animals or for cutting one’s way through a rhododendron thicket, down to the tiny knife shown in the accompanying picture, whose handle is only a trifle over two inches long. The blades shut up easily and accurately into the case, just like a factory-made knife. The handles he makes from cow’s horn or from bone. He admits that he has sold two or three of these small knives for as little as twenty-five cents apiece! Coke still suffers from a lack of ade- quate equipment. For an anvil he has only a heavy illusions as to the quality of his handiwork. He makes practically all the tools that he uses in his farm-work—hoes, mattocks, axes, hammers, hatchets, frows, and so on. It is true that they will not hold an edge as well as steel tools, but he gets much good ser- vice out of them. He makes hinges for the gates and doors on the place, as well as latches and bolts for the latter. A razor-back pig comes squealing up to the fence with a small bell clank- ing at its throat, and you learn that Coke made the bell. He is constantly on the lookout for old iron that he can remelt and use in his work. Parts of old wagons, plows, and other agricultural machinery, discarded tools— steel axle, fastened across two blocks of wood. The thimble serves as the horn of the anvil. When we first visited him last summer, he expressed a hope that he could some day have an emery wheel on which to sharpen his tools, the ordi- nary “grindin’ rock,” as he and all mountaineers call it, being too soft. He has since been supplied with this article. He digs the coal that he uses in his forge from a all’s grist that comes to his vein that outcrops under a cliff two and a half miles from his home, and brings it in, a boxful at a time, on his shoulder. Coke was taken into the army in the spring of 1918. The mountain soldier did not get any farther than Camp Pike, Ark. No one in the mill. Of course he must al- ways carry such junk several miles, either on his shoulder or on the back of the old mule that he now possesses, and of which he is as proud and as careful as if she were a race-horse. Coke works very skilfully in wood, though he does it, as a rule, only when necessary. army seems to have compre- hended his gifts. He was much interested in the auto- mobiles and trucks he saw, and begged to be allowed to work at something in the motor department, either as driver or repair-man. But he was esteemed too ignor- ant to be allowed ‘to touch machinery. He has made some gunstocks that can’t be beaten by any- body. He built a kitchen cupboard for his mother, and had no dressed lumber out of which to make it, either — just a few pieces of rough stuff, and the rest he sawed out himself. He made a plane with which to dress it, even making the blade of the plane in his forge. Ordi- nary kitchen chairs are easy for him, but his best job in the line of furniture is his mother’s large, comfortable rocking-chair, which has knobs and curves not easy for a man to achieve when he is absolutely ignorant of geometry or of design, save in a purely intuitive way. As an example of the expedients to which he has resorted on many instruments Rice has made. pocket-knives, from the big five-inch-bladed jack-knife suitable for skinning animals to very small ones. those shown in the middle picture. shows two millstones and four tools. In the top picture are a few of the many crude tools and much for woodworking, anyhow. He says so. Iron is his true love. He will even work in stone at times. It is twelve miles from his home to the nearest grist-mill. He decided recently that he wanted a little mill of his own. So he has been slowly working out a pair of small millstones, using a variety of mountain sand- stone, which is welded together with so much iron that it might almost be called a low grade of iron ore. But probably his cleverest work is dirnlayed in his pocket-knives. He 57 He can make all kinds of Compare The lowermost picture Rice made them all There may yet be time to save this latent genius from sinking into the sodden apathy and ineptitude of the ordinary unambitious moun- taineer. A few more years in his present surroundings, and his gifts will be lost. He says he would not stay in his present forlorn location an hour if it were not for his mother. She clings to the spot with the unexplainable, feral instinct of the old mountaineer, who sickens and shrivels when away from the big hills. Coke hasn’t developed his gifts along tht lines that would mean most to himself and others, be- cause he doesn’t know how to do so. He doesn’t know how to get his wares to the proper market. He doesn’t know how to capitalize his talent. Who will give him the chance? ET TE

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SS RE Fee ene ae ene - —— iain ie ape ene ET Dee a saa ge Rene a OO AS AER a i ig MELA a a Sh ty nasi = SERRE fe ape) teemtanaemcen nae tigen ma Ly Mnafstneta ae. ni Ph ‘ = = ncaa reared — Rinchiai see R A RTI EE meine Nettie tape an + —J- Underwood & © Underwooi The Unbarbered Ainu MAGINE 20,000 men in need of a hair-cut anda shave, and who have been (Right) The pneumatic Popular Science Monthly tent carried by the ‘** aerochir,” or airplane ambulance. The tent is inflated with air pumped in by the airplane engine (Left) The aborigines of Japan, the Ainu. If ever hair-cutting and shaving become a fad, here will be a good place for a barber to get rich in An Airplane Tent Hospital ERE is an airplane ambulance that car- ries a tent for a tempo- rary hospital. The tent is composed of material suitably made into com- partments which can be inflated to form a support for the tent. The air- plane engine operates a fan which blows air into the bags. The ambulance, or aero- : chir, has a speed of ninety ais miles an hour. in need of these things all their adult existence! In the northernmost islands of Japan live the Ainu, or hairy men. Science hints that these curious folk may be of remote Caucasian descent, though they undoubtedly emigrated origi- nally from the Kuriles. When they came to Japan they killed the race of pit- dwellers, the dwarfs who knew the art of pottery and could make flint arrow-heads. Then later came the Japanese, who drove the Ainu tothe northernmost island of Yezo. These backward people take on nothing new. They eat with chop-sticks and use mustache-raisers—indeed a necessity. Sprinkling the Envelopes OOD-BY, old sponge and dirty bowl! You have mussed up the office desk long enough. An Illinois manufacturer is making an efficient aluminum envelope- moistener. An aluminum cap fits tightly over an aluminum can which is about two inches in height. Water is poured into the can, and when it is turned upside down, the water comes out through tiny holes in the cap. No sponge is required in using this moistener. The small holes permit only a little water to flow out of the can. ' q | understand that they cannot The new envelope-moistener is really a small watering-can ; the lid is perforated On a small island in the Great Salt Lake thousands of pelicans live, even though they have to fly many miles for their -food Put Up Your Umbrella When Among Pelicans BOUT twenty miles from Saltair, Utah, on the Great Salt Lake, is Bird Island, recognized as the sanctuary of pelicans. Bird Island derives its name from the fact that only birds—and, in fact, only pelicans—live on the island in the great inland body of salt water. There are countless thousands of peli- cans on the islands, and many tourists leave Salt Lake City every summer to spend a few hours there. The birds are so thick, and fly so low, that most persons tour the small island with either umbrella or parasol open to prevent the pelicans from alighting on their heads. There are no fish in Great Salt Lake, and many have asked how the pelicans live. Inquiry shows that the older pelicans fly every morning to Utah lake, about thirty miles distant, and consume a meal of fresh-water fish, and then return with their pouches full to feed the younger pelicans. Bird Island is nothing more than a rocky structure. There is no human habitation there. Neither is there any vegeta- tion. The reason for the peli- cans remaining at- Bird Island and making the daily flight to another lake for food has never been fully explained, although fish and game offi- cials say that the pelicans be molested at the island, and that therefore the sanctuary in Great Salt Lake will always con- tinue as their permanent abode. 58 Where Time Counts Not _ HAT’S all this for?” one would surely ask if he visited the bank of one of the sluggish yellow rivers in the vast domain of China, and saw a bull slowly walking around in a circle under a bamboo canopy. “Is it some queer religious ceremony?” “Not at all!” the guide would reply. “Here in China many people follow the beaten paths of their fathers. This man is urging the bull to trudge around the treadmill of a ‘pump’ which draws up the water from the river and empties it into a narrow irrigation-ditch. “‘Of course a gasoline engine and pump would do the work better, but it may be a long time before they want to use modern things out here.” © Keystone View Co. On the bank ofa river in China, this bull operates a tread- mill, thereby conveying buckets of water for irrigation

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May, 1920 weeks Courtesy of the American Museum of Natural History When Kansas Was a Sea At the time the gigantic flying reptile shown above soared in the sky, millions of years ago, western Kansas was in the heart of a great inland sea. The toothless Pteranodon measured twenty-one feet straight from tip to tip across the wings. A large condor might extend as much as thirteen feet stretched out, but in proportion the ancient flying reptile weighed less. It was all wings and head, the wings being covered with a thin leathery membrane like the wings of a bat. Little claws at the side of the ‘“‘wing- finger’”’ enabled the creature to hang like a bat while resting. Mr. Handel T. Martin, curator of the Geological Museum of Kansas University, discovered the Pteranodon in the chaik deposits of western Kansas. The mounted skeleton may now be seen in the Museum of Natural History, New York. Veils for Horses \ HEN a horse wears a veil across its face just below its eyes it is not trying to look as if it came from a harem, but is attempting to keep the flies and gnats from landing on its nose and lunching there. The end of a horse’s nose is‘a favorite meeting-place for bugs. In fact, some of them try to raise their families there. And the horse is helpless. Its tail won’t reach around that far, and its bit restrains its tongue. A veil is its only protection. A great flying reptile so constructed that it must have been amarvel unsurpassed in soaring flight engage These horses are not trying to be beautiful; their veils that try to live on a horse’s nose ward off the A Curious Clock wp Rat is a curious clock in your shop window; will you tell me about it?” the stranger asked. rc “Well,” said the inventor, Mr. S. C. Swindler, “having an idle clock in the house, the thought struck me that I could make that clock operate a large sign which I thought I could myself manufacture. I went to work, and in three days had it crudely operating my sign. I spent my spare time for three years improving the device, and now you see how it works.” The works of the clock operate circuits of electric current which cause the letters of a sign to flash. A very small per cent of current is used, since the clock takes the place of a motor. The works inthis clock operate a mam- moth electric sign ee ————— © Kadel & Herbert The parrot that called ‘‘Ma, come get 7em!’’ and caused the arrest of a burglar The Parrot Burglar-Alarm “Mi come get ’em! Ma, come get ’em!’’ was the cry that rang shrilly through the stillness of the house. Cecilia Sherman, the ten-year-old daugh- ter of Samuel Sherman, knew at once what the parrot meant, for the family pet had been trained to pronounce this phrase at the sight of strangers. The girl ran upstairs, and brushed against a strange man coming down the stairs. She ran after him as he darted from the house, and was joined in the chase by her cousins Julia and Sadie. The girls were better runners than the man, and when they caught up with him the three held him until a policeman came and arrested him. Targets of the Big Guns OOM! The great guns are firing. As the smoke rises and the rumbling echo rolls away, the sailors watch eagerly. Did they hit the target? From the deck of the battleship the targets look like tiny black patches with white spots in the middle. But a close-up view is quite different, as you see in the picture below. On target No. 175 three hits are plainly seen. The numberless target next to it boasts of three patches that cover up holes made in an earlier test. These are some of the targets at which the United States battleships fire when they try out their guns

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Se eae eee i sa snp degen nt ntl aoa dante Toca des a—~ighvpaedaaia _by one, to the letters Popular Science Monthly Do Spirits Talk through the Ouija Board? Perhaps it is that subconscious ego whose memory is better than yours You place the ouija board upon your knees or on a table, and let your hand rest lightly on the planchette, the little three-legged car- riage that rides over the ouija board. See that you are comfortably seated, and your arms not cramped, but free to move. Stop your thinking ma- Ais you hovers the unseen. By A. J. Lorraine Anyone who says this has either not read the communications of Patience Worth, through the hand of Mrs. Cur- ran of St. Louis, or else is wholly de- void of literary sense. Read the book and judge for yourself. Selected ex- cerpts from the records have been col-

chine; try to make

your mind, as far as possible, a blank. If you want a success- ful séance, see that the circle of friends about you consists of persons who take a serious interest in the proceedings. Scoffers are not help- ful: a quiet, serious atmosphere is most favorable to good results. A time passes in silence. The right conditions must -be allowed to establish themselves. Look — now the planchette stirs. A hidden power seems to move it. At first a few straggling, random movements. This may continue for a while. Pres- ently, pointing, one

of an alphabet printed on the face of the board, the planchette begins to spell out a mes- sage : ee Aree ete ey. ttt Ott hte: ie Dedind: Padua Ce og IL***]*** v*t**B***p, A*** G*** A***I*** NIC***0Q*** M***E. P*** A*** Pee eee BE * * * N*** Gre * E W * * * oO*** Bore eee tet Nt ** A eee M*** EK. . With these words one of the most remarkable personalities that ever spoke through the ouija board an- nounced herself to the world. It is sometimes said, in criticism of those who inquire into

Skeptics are disappointed in the character of the messages received with the aid of the oujia board. They forget that even the greatest of us are but human beings. Sir Isaac Newton did not always discuss mathematics at the breakfast- table, nor Napoleon the best ways to win a battle. point if the spirit of Newton refers to a special dish of which he was particu- larly fond in his lifetime, and if on investigation we find his statement to be true, than if he were to dwell long and learnedly on gravitation lected into a volume by Casper S. Yost (Henry Holt and Co., publishers). There you will find romantic tales of times long since past, and a series of poems of singular charm, written in a quaint old English dialect. And the remarkable thing is that Mrs. Curran, through whom the communications came, is herself not a writer, and the very language in which they are couched is strange to her. Patience Worth claims to be the discarnate spirit of a person that once walked this earth, even as you and I. What does psychic science have to say It is much more to the about it? To understand the situa- tion, you must begin by understand- ing yourself. Ordinarily your hand obeys your will; its motion fulfills some con- scious purpose of your mind. When, therefore, you find the planchette un- der your hand performing movements and spelling out words that were not in your mind, and which you had in no wise purposed, you prised. One explanation that presents itself for this strange course of events is that some unknown outside influence,

guides your hand, irrespective of any knowledge or pur- pose on your part. Are You Absent- Minded? And this is a pos- sible explanation. But, before we final- ly adopt it, let us pause for a moment. Think: in the ordi- nary course of life, do you not some- times perform ac- tions that are not controlled by any conscious act of the will — actions, per- haps, that are even contrary to what you intended? Areyou never absent- minded? Have you never handed the conductor on a street-car a transfer and held out your hand for the change? Have you never dipped your pen in the mucilage bottle? Or, if not that, then some equally absurd lapse you surely have committed sometime, as sure as you are human, though you may not have gone so far as the young man who started to take a girl to an ice-cream parlor and found himself escorting her to the undertaker’s.

Such lapses remind

occult phenomena, that nothing but trifles and dribble ever comes to us from the agencies, whatever they may be, that speak to us through medi- usual channels.

and not to prejudge. HE war has done so much to revive interest in the ouija board that the POPULAR SCIENCE MONTHLY has decided to approach matic. You exercise the whole subject of spiritualism with an open mind. It will not do to accuse those who manipulate the ouija board of being frauds: there are too many of them. Besides, it is the business of science to investigate In this article the author sets forth the results of investigations that have been conducted by psychic researchers for ums and other un- years. It will be followed by articles on other phases of spiritualism us that many of our actions are auto- your will to decide the main issues, and then leave the ‘exe- cution of the details to—to what? Well, psychologists call it your subconscious

60

are naturally sur-. perhaps a_§ spirit, -

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May, 1920 self. This other self is a very remarkable person, even though once in a while he plays curious pranks with us by doing the right thing at the wrong time. I am not going to say that your other self is in all things your superior; in some of life’s affairs your dom- inant conscious ego has to hold the helm. But in some things the sub- conscious or subliminal self is indeed your su- perior. His memory is phenomenal. It seems almost as if he never forgot anything. Ordi- narily he takes a modest place in the background, so that, though you have been living with him all ‘these years, you may hardly have noticed him at all. But there are ways of drawing him out into the light, where you can observe him. He notes many things that you pass by unobserved. The clock has just struck the hour. You did not count the strokes. But it is not too late. Though you were paying no attention, he was on the job; he kept a memory record of the sound. And in your mind you can go back and count the strokes. Subconscious Memory There is not a second in your waking hours when you are not constantly re- | ceiving impressions through your senses. Your eyes are open and are seeing some- thing or other as long as you are awake. How much do you remember of what you see? Far more than you ordinarily suppose—at least, if “‘you”’ means both of you, your ordinary self and your subconscious self. Perhaps you say, how do I know that the subcon- scious self remembers so much? As long as I am not conscious of what he re- members, how can I test his memory? There are several ways of digging down into the mem- ory of the subconscious self—that is to say, into your subconscious memory. The first method is very simple. Select any little incident in your life—some- thing quite trivial, say. To start with something easy, you may pick out A revived form of an old pastime: A wedding ring suspended from a thread tied to the fingers performs various automatic motions. The more usual method is to put your elbows on the table, hold your hands against your temples, with one end of the silk thread at each temple, the ring hanging in the loop of the thread under your chin and swinging to and fro in a wine-glass. It counts out answers to your questions by striking the sides of the glass, so it is believed some fairly recent occurrence. Per- haps you went to see a friend off at the railway station, or you met an ac- quaintance in the street and stopped Mrs. John H. Curran, of St. Louis, through whom “Patience Worth’? has communicated a number of romantic prose stories and poems 61 to exchange a few words. Whatever it may be that you select for the experiment, fix your thought on that event in a dreamy sort of way, and let your thoughts drift freely around the various associations that come to your mind in connection with the in- cident. Do not make any effort to recall things; just let your thoughts come floating in as they will. You will be surprised at the amount of detail—trivial detail—that you will thus find streaming back to your mind. The fac- ulty of thus resuscitat- ing memories can be improved by practice, and isnot without its use. It may help you sometimes to recover articles mislaid or lost. But what, you may ask, has this to do with the ouija board? One of the several methods of tapping the subconscious is with the aid of the ouija board, or, more generally, of auto- matic writing. For the planchette is not neces- sary: it is merely an adjunct to facilitate the process. Certain persons possess the natural faculty of automatic writing. Ifa pencil is placed in the hand of such a person and is allowed to rest on a piece of paper, and if this person takes his attention off the action of his hand,—for instance, by reading a book or by engaging in conversa- tion,—presently the pencil between his fingers starts to write, tracing words and sentences having no rela- tion whatever to the book or the conversation. It is just as if some other person were writing. The opera- tor himself (or herself) does not know what has been written, any more than do the other persons present, until the writing is in- spected. The Case of Miss C— Then, it is often fourfd to contain references to ex- periences that had been ‘ long forgotten by the sub- ject, and that frequently cannot be recalled even after the writing is de- ciphered, though other evidence may establish

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a ae aN ENE ENE EST ER Tie TERS their truth. So, for example, Doctor Morton Prince, Professor of Nervous Diseases at Tufts College Medical School, quotes the case of a certain Miss C—-—, who, in a _ hypnotic trance, narrated a strange tale, as- cribing it tojthe intermediation of the spirit of a person purporting to have lived in the reign of Richard IJ. She gave many personal and historical details which, on examination, were found to be correct, although many of them could not have been ascertained without extended research. Miss C—, on coming out of the trance, was unable to say how the intimate historical knowledge displayed in her hypnotic utterances could have origi- nated. She could not recall reading any book that would have furnished her with the information. But a script produced by her in automatic writing disclosed the fact that a book called ‘“‘The Countess Maud” had been read to her by her aunt fourteen years earlier, when she was eleven years old. Both ladies had so com- pletely forgotten the con- tents of the book that they could not recall even tue period with which it dealt. Nowa Or be, Yeo ax) hon, fe Ma Yolen te WnUilade | We see, then, that we must be cautious in: as- cribing the motion of the ouija board, and the mes- sages spelled out by it, to the action of extraneous influences, or perhaps of discarnate spirits. For, from what has been said above, it is clear that much of what. appears to the subject as the creation of another mind may be merely the resuscitation of impressions wholly for- gotten by the ordinary self, but indelibly fixed in ; the phenomenal memory Ele yn of the subconscious self. 9s ster, “ar Wate ies Les. 2) wil ut 4 at | ~ Helene Smith from Mars But how about the re- markable literary quality of the productions of Patience Worth? Mrs. Curran, through her ordi- nary consciousness, has shown no signs of any re- markable genius in that direction. And how about the quaint old Eng- 65) lish, dialect consistently ee followed throughout her planchette writings ac- credited to the discarnate L a) Patience Worth? s Well, in the matter of ee i literary quality it is ad- mitted that Patience Worth’s productions are unsurpassed by any auto- Pr ae vice ob Ke Tom matic writing on record. But as to the dialect, the performances of a certain Swiss medium known under the pseudonym of Mademoiselle Hélene Smith totally eclipse her feat. Helene Smith has com- pletely kicked over the traces, so to speak. She writes not merely in an archaic tongue, not in a mere outlandish dialect. Her speech is not of this earth at all. It is written in characters hitherto un- known, in words found in no earthly dictionary—and for a good reason: Helene Smith claims to be the spirit of a departed in- habitant of the planet Mars. But there is something very suspicious about Heélene’s Martian language. Its syntax, its grammar, the order of the words in the cet Ns Uwe wr,

ees ee atthe awe Ke tes Wer Koes 4 Ya th acs <— = Psychographic signature of Archdeacon Colley, alleged to have been received after his demise by the Rev. G. Henslow. Above is shown the natural signature of Archdeacon Colley, for comparison with his alleged spirit signature KrSZtac G62? defghijhtli un iV¥ws de Me re buvwxeyet . ch V- oS initia Ve <sdoublesss 5 signe daplriel Characters used by Hélene Smith, and purport- ing to be the letters of the Martian alphabet 62

Popular Scvence Monthly A dream drawing. It makes us sus- pect that some modern paintings may be produced by automatic methods sentence, are precisely the same as in French, Hélene’s native tongue. More than that, the individual words are found, on inspection, to show a strange agreement in the number of syllables ‘with the corresponding French words. Subconsciously Evolved Dialect? It would be difficult to find an example that would illustrate more tellingly the extraordinary faculties of the subconscious self than this per- formance of Mademoiselle Helene Smith, who must have evolved, un- known to herself, a complete language and a cipher code, and have then proceeded to use them consistently, without stumbling, without hitch, in writing lengthy descriptions of alleged doings upon the planet Mars. As compared with this, it would have been a relatively easy task for Mrs. Curran to evolve, subconsciously, an “archaic dialect,’’ which, by the way, has never been shown to have been actually spoken at any time or place. As for the undeniably inspired character of Patience Worth’s poetry and prose, this will not greatly sur- prise anyone conversant with the psychology of creative mental ac- tivity. Numerous men great in litera- ture and other fields have told us that it seemed to them that not they, but some other person or persons for them, created their works—they merely wrote down what was revealed to them. Dickens, in his letters, speaks of the characters in his books much as he would of real personalities,

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May, 1920 and he tells us that the famous Mrs. Gamp, perhaps his greatest creation, often spoke to him ‘with an in- ward monitory voice.’ Robert Louis Stevenson ascribes his in- spirations to Brownies, who “tell him a story piece by piece, like a serial, and keep him all the while in ignorance of where they aim.”’ Instances of this kind might be multiplied. Briefly, we may say that genius seems to consist in an unusually close contact of the conscious self with the subsconcious, an unusually developed power to summon up before the view of the fully awake mind the dim phantasms with which the sub- conscious realm is peopled. Psychology Explains Much Are the revelation of the ouija board and other modes of automatic writing, then, to be wholly explained in the matter-of-fact terms of psy- chology? Is it all just a freak by the automatic motion of the artist’s hands. ings, it is remarked, have a certain value for the artist which they do not possess for the ordinary individual Not only handwriting, but also drawings, have teen produced Such Another instance cited by Myers has an amusing side. The pencil in the hand of a certain lady gifted with automatic writing persisted, on one occasion, in writing time after time the word “Goat.” She was then in- formed that the gentleman standing beside her was named Nanney. In instances such as these, which are well authenticated, the ouija board and automatic writing generally seem to give marked evidence of telepathy or thought-reading. But there are cases in which the hypothesis of tel- epathy must be strained almost to the breaking- point to account for messages re- ceived. Dr. Hys- lop, in his book ‘*Contact with Other Worlds,” cites a number of such examples. On January 28, 1902, Dr. Hodg- son suggested to the alleged spirit controlling the famous medium Mrs. Piper that he should impress the daughter of Mrs. Verrall, in England, with the view of a person holding a spear in his hand. The medium replied: ‘“‘Why asphere?”’ Dr. Hodgson corrected her: “‘A spear.” The control agreed to try. Both Mrs. Verrall and her daughter are noted mediums. On February 4 of the same year Mrs. Piper’s control reported to Dr. Hodgson (this being the first séance since the giving of the message) that he had succeeded in transmitting the message about the “sphear’ (so Mrs. Piper spelled it). Meanwhile Mrs. Verrall had, on January 31, re- ceived through her automatic script a message partly in Greek and partly in Latin, which translated read as draw- of the intricate workings of the human mind and body? This does not follow. Psy- chology sheds light on the situa- tion, and perhaps explains much. But there is seemingly also much that remains unexplained. So, for example, in a seance reported upon by F. W. Myers in his work on “Human Personality and Its Survival After Bodily Death,” the operators of the ouija board were placed out of sight of the com- pany, who in silence selected a photograph from an album and fixed their attention on it. Pres- ently the ouija board began to spell out either the name or the initials of the person whose photo- graph had been selected, or else it wrote out some characteristi« fea- ture descriptive of the picture. Out of five cases three were cor- rectly identified. In another case a series of ques- tions were put to the board: ‘How many shillings has Miss X in her purse?” ‘Four” (correct). “How many coins in my purse?” “Five” (correct, though the in- terrogator thought he had many more). A card was picked at random out of a pack, looked at by one of the party, and then laid face down on the table. ‘What is the color of the card?’’ ouija was asked. ‘Red’ (correct). “‘What number?” “Seven” (cor- rect). ‘What suit?” “Hearts” (correct). How to Make a Ouija Board ie \ | COMPLETED \ | TABLE ‘FELT PAD yoPQRSTUVWxy> 1234567890 i GOOD-BY /f 20" ol A homemade ouija board that ‘“‘answers’’ ques- tions fluently can be made from a clear perfectly straight board about 20 inches long, 14 inches wide, and 3% inches thick. Round off the corners and sandpaper it until smooth. Trace on it the letters of the alphabet with a pencil, and black them with a brush; also trace the words “‘yes’”’ and “no,” and the numbers, and at the bottom the word “‘Good-by.’’ Coat the board with two coats of varnish, and rub smooth. While the board is drying the table can be made. Cut from a board of 34-inch material a heart-shaped piece 41% inches wide at the widest point and 6 inches long. Next make the three wooden legs 2 inches long and glue them into holes in the under side of the table. Cut three disks of felt from an old hat and glue one to each foot of the little table follows: “A universal seeing of the sphere fosters the mystic joint reception. Why did you not see it? The flying iron [Latin idiom for spear] will hit.” Mrs. Verrall is a classical scholar, so the receipt of a message in Greek and Latin is not in itself very surprising. Still more re- markable, therefore, is the case of a message given by Mrs. Verrall to her control in Greek, and re- peated together with the transla- tion and the reply by Mrs. Piper in America, though this lady is ignorant of the ancient languages. Another Automatic Script Case In other cases automatic script has been found to bear a marked resemblance to the handwriting of a deceased person purporting to be the author of the communica- tion. Material of this kind has been obtained particularly by Mr. B. F. Underwood through the writing of his wife. Says he: ‘Fully aware that, under certain conditions, from the submerged self may be sent up memories which cannot be distinguished from newly acquired knowledge, still, I am confident that Mrs. Underwood’s hand has written names and statements of facts, not only once but several times, which were not part of her conscious self.” 63

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3.58 sn ciicicinith nn AASAA AAA: WAR iit ri i Sb i ABE AN NNN Ege Ey 2 ~ ee sentenr te pr ERENT Ue er nore er ert Wee war Gereitf Sans = a Sp el Boers ie = Sidhe = Sa: — Fee resi enaer. Sane : Se eee ee fap le yn ag i gala e , Tiny II’s neck-watch carries his name and address, so it’s really a dog-collar This Little Dog Wears a Neck-Watch INY II, dog, was given a wrist- watch and he didn’t know what to do with it. He wore it on his front paw for a while, but he was always buying new crystals for it. He now wears the watch around his neck. Of course it’s not of much use to him there, but he doesn’t know how to tell time, anyway. His initials are on the outside, together with his address; thus the watch takes the place of the plate on a dog-collar. A Monster Beavers’ Dam N Taylor Creek, Bayfield county, Wisconsin, beavers have built a great dam. It is twelve feet high and a quarter of a mile long. The house is in the center. It is sixteen feet high and forty feet wide at the base. The sleeping compartment is large enough for a tall man to lie down in. The floor is covered with a dry compound and is spotlessly clean. When man invaded the dam a large quantity of food was found stored there. Wrecked by a Tank—a Water-Tank HIS is what a tank did—not the tanks that did such damage in the war, but just a peaceful old water-tank! A 40,000-gallon tank carried’on a 75-foot steel tower, and used in fire emergency, became so encaked with ice that the additional weight was declared unsafe, and the tons of ice were removed under orders from the Building Inspector. On the night fol- lowing the afternoon when the ice was cleared away, the steel structure support- ing the tank collapsed, and the huge weight crashed to the ground, com- pletely wrecking a four-story building. Damage to the extent of $100,000 was the result. No one was in the building except the night fireman. He was in the basement of the building, and was rescued by a passer-by who pulled him through a grating in the sidewalk. Luckily, he escaped without injury. When a huge water-tank charged down from its 75-foot perch above the courtyard of a factory, it wrecked a four-story building Popular Scvence Monthly As soon as a memorandum has been attended to, the segment on which it is noted can be slipped out A Memorandum-Pad that Comes in Sections “( “ALL Mr. Hanley,” says a memo- randum on the desk-pad. Now, when he has been called, what is to be done? Should the page of the mem- orandum-pad be torn off, what about the other memoranda on the same page? The simple way is often the best way. There is a handy memoran- dum-pad having four divisions for each leaf. When Mr. Hanley has been called, all one has to do is to slip out the section on which the memorandum was written, leaving the rest of the memoranda undisturbed. Only one hand is required to remove one of the segments. The holder con- tains enough filler to supply the average office man four or five months. See the Meridian “TOAST is east and west is west, and never the twain shall meet,” said Kipling, but he was wrong. In the picture below you can see the meridian line where east meets west; and to make the matter more interesting a man has one foot in each. The meridian is an imaginary line from the north to the south pole, passing through Greenwich, England. On the road to the observatory there, the meridian is actualiy dug out of stone. A human family could live in the house in the center of this a quarter of a mile long ‘ beave-s’ dam; the dam itself 64 At Greenwich, England, the meridian—an imaginary north-to-south-pole line—is indicated in the stone road

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May, 1920 The fruit-grower now brands his fruit, and you soon learn which is your favorite brand and order it by name Branding Fruit and Vegetables Without Injury . CAN of So-and-So’s baking powder, a bottle of Blank’s ketchup—”’ You ean safely order your groceries by the telephone because they are labeled. But fruits and ‘vegetables wear no protective labels. ; However, there is now a fruit-branding machine, invented by Ansel Wysong, of Los Angeles—the man who devised the walnut-branding machine. Oranges, lem- ons, grapefruit, apples, and even tomatoes may be labeled without injury. The machine works on the vacuum principle. Bookkeeping of Cooks yw you order breakfast at a fashionable New York hotel, the waiter does not shout to the cook, ‘‘One up on the ham and eggs!’’—oh, no! He writes your order down and then quietly disappears kitchenward. He approaches the cook with his pad in hand, reads off the order, and the cook in turn writes it on a pad—one of many lined up on a shelf. Then he puts your ham in the pan. There is a pad for each kind of order, and the cook is very careful te write each order in its proper place. At the end ofa day he is able to tell at a glance the number of ham-and-egg orders, for in- stance, that he has cooked. All orders are carefully checked up and there is very little chance of error. This Bad Man Gave the Sheriff a Jolt A MISSISSIPPI sheriff left a prisoner securely locked in his room at the hotel. Yet, when he returned, the pris- oner was gone. floor, and there was no fire-escape. When the sheriff left the room the pris- oner was calmly reading a newspaper. When he returned he found the door still locked, and the newspaper lying on a chair. Later the man was captured, and induced to tell how he had escaped. The sheriff had left the key in the door after having turned it. The prisoner, suspecting this, slipped his newspaper under the door; then, with one of his own keys, he pushed the hotel key out of the keyhole. It fell on the newspaper, and. the rest was easy. The room was on the fifth . This bad man is locked in his room; but he is forcing the key out of its lock so it will drop on the newspaper, and he will then pull the newspaper into the room with the key resting on it © Kadel & Herbert A series of these lighthouses would pilot airplanes safely for great dis- tances across country in bad weather Pillars of Light to Guide the Airman A Hounslow Aerodrome, in England, a lighthouse has been erected to guide airmen at night and in bad weather. A beam of light of 70,000 candlepower is sent vertically into the sky, illuminating the dust and moisture in the atmosphere and standing like a luminous pillar. The pilot flying above a fog can see a spot of light on the cloud-floor beneath his machine, and he knows that the landing- field lies below. Get Ready—Sneeze! ET ready! Set! Sneeze! These orders are given to a group of nose patients in the Battersea General Hospital, and at the word sneeze they all chime in. It has been found that sheezing helps the preven- tion and treatment of nasal complaints. | At the order, “‘Get ready!”’ each patient dips a feather in a saucer containing iris root. At the word “Set!’’ they sniff the feathers. Then they sneeze in chorus. = © Press Illustrating Service The cook has a pad for each different order, which makes it easy for him to check up the things he cooks each day In a 65 F How a high school student can win $500—see page 106 s ut three seconds they will all sneeze; on the feather- tips i$ iris root: sneezing helps in the treatment of adenoids

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hes Sanaa tn atntSnash met WS UCL, ML TE Ti einen A device for lifting water from a lower to a higher level by rotating the vertical tube Whirling Water Uphill NEW water-elevating device has been invented by Mr. Leon Shevchenko, of Cortland, N. Y. A vertical tube fitted half way up with a system of horizontal pipes is rapidly rotated, the centrifugal force causing the water in a lower level to flow upward and outward through the pipes. The scheme, carried out on a suitable scale, might be handy in draining pools ona farm. On a larger plan the motive power could be supplied by a gas-engine. A Bedroom Pet ee the leafy trail of the dark forest one listens for the breaking twig that whispers, ‘‘Watch now and you'll see a deer jump out of the brush!” But Mme. Clothilde Sakharoff, the exponent of a new phase in the art of dancing, became indisposed when she arrived in New York, and her husband comforted her with a refreshing breath of the outdoors by having brought to her room a tame deer. Mme. Sakharoff and her _ husband, Alexander, came to America to introduce their new dances, which had already astonished Europe. © Kadel & Herbert The bareback rider that recently created a sensation on New York’s Broadway A Bareback Rider in a Broadway Café A GRACEFUL bareback rider, poised on one foot with arms outstretched, is a novel sight for a Broadway café; yet this is what the habitués at one of the sophisticated old resorts about town are still talking about. Monkey and dog marriages no longer attract attention. The fad is no longer new, and those who indulge in fads are hard put when they want anew one. This is the first time such publicity has been gained through the love of blue-blooded horses. The bareback rider created a great sensation along Broadway when it first was introduced by the creator of a new fad in evening wear at a well known restaurant. Visitors to the gay white way are still talk- ing about it. The picture of a painted figure on one’s back is not so drastic an art as one that is tattooed. Pigment thinly applied is cheaper than the same amount of cloth, so the idea may be developed interestingly. Popular Science Monthly | aati. i] A cement-sack baling-machine which compresses the empty sacks into a compact bundle Bale Them for the Rebate Pewee cement-satks bring a good re- bate when carefully baled and shipped. To do the work by hand is laborious and time-consuming, but above is a simple machine for baling. The empty sacks are laid across the baler, then a lever is pressed down to compress them into a compact bundle. Wires hold the sacks tightly and prevent losses such as would occur if the mass were loose. It is claimed that the ma- chine is so inexpensive that the rebate on two bales of sacks pays the entire cost. He Paints with: His Toes yw ae working in an airplane factory the boy in the picture lost both arms. He decided, optimistically, that since he still had his toes his case was not hopeless. He went to the Crailey Heritage Craft School and learned to paint pictures with them. Here you see him working on a landscape. Men have learned to play on musical in- struments, hold books, and even weave with their toes. L L © Kadel & Herbert Mme. Sakharoff, while indisposed and confined to her bed, was comforted by having a tame deer brought to her room © Press Illustrating Service This young man lost his arms in an airplane factory; un- discouraged, he learned to paint pictures with his toes

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May, 1920 It may be ugly, this baby hoatzin from British Guiana, but it’s clever; it swims, dives, and flies It’s a Baby Hoatzin BEHOLD a baby hoatzin! It was alone in the nest when thé pho- tographer approached. It climbed out bravely for the first time, and moved awkwardly to the end of the branch. The photographer followed. When it was two feet away, the baby bird folded its wings and did a high dive into the water below. A few seconds later a scrawny head with two bright, beady eyes bobbed up above the surface and watched the enemy closely. When the photogapher disappeared the exhausted hoatzin dragged itself out of the water and climbed back to its nest amid cheers and felicitations from its anxious parents. It lives on the banks of the Berbice river, British Guiana. Reading in Bed D°® you like to read in bed? Most people do, but they find that in a short time their arms grow tired from holding the book, and their eyes grow tired from reading in a bad light. Both of these difficulties are done away with in the new light and book support that was recently invented by Christian Widmer, of Upland, Cal. A lamp of a conical shape is mounted on an ordinary stand. Inside of the shade there is a lens that can be adjusted so that it will throw intense light on the book you are reading. The book is ‘held ina rack fastened to waist and shoulders. The tool that trims the edges of the lawn has two blades—an _ upright curved one that does the cutting and a flat one that catches the pieces A Trimmer for the Edges of the Lawn EMOVING the rough edges has always been the hardest part of lawn- cutting. Two tools—a scuffle-hoe and a lawn-edger—have been necessary. But now Mr. Timothy Murphy, of Beacon, N. Y., comes along with a new tool that attends to the entire edging operation. It consists of two sharp blades—one being flat on the ground and the other curved upward at an acute angle. The curved blade does the trimming and the flat one catches the grass as it falls. But this flat blade has another job. It uproots any small clumps of grass that have grown just outside of the edge of the lawn. It is sharpened on three sides. The ‘“‘tensiometer” has been devised by the Bureau of Standards for testing the strain put upon airplane wires Testing Airplane Wires HEN the pilot of an airplane cuts off his engine and starts down- ward, he can hear the vibration of the tautly drawn wires strung between the airplane wings. What is the strength demanded of these vital ‘‘threads”’ which hold the frame of the airplane and keep it from being shattered? The ingenuity of the Bureau cf Standards has devised a means of knowing exactly what strain or tension a wire of a certain size can stand. The instrument is called a ‘‘tensiometer.” It consists of two supports at a fixed distance-apart, having a moving plunger midway between them. Two dials indicate what is happening when pres- sure is brought to bear upon the drawn wire, one dial showing the pounds of pressure and the other the wire tension. For Automobilists # bien picture below is for people who drive automobiles. This poor little fellow will endure this torture, without one minute’s rest day or night, for five long weeks, just because a man driving a big touring car was not careful. The child was hit. Both legs were broken above the knees. Here he is on a cot ina big Cincinnati hospital. Would you like to hear that pitiful cry and see him endur- ing this scientific torture, and know that you were the cause of it? Science says this is the only way for the bones in his little legs to heal properly so that he will not be a cripple for life. — { Dcetaientihameneeie a es pare fee il cama a ae —_— i For the army of people who like to read in bed comes this contrivance to make them comfortable; arms as well as eyes; hands are needed only to turn pages it saves tired This young sufferer is the victim of careless automobile driving. He will have to stay in this position for five long weeks. Surely this is a lesson for law-breaking speeders

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- AY ANNIE nN Sy AOL 0 Saat aha PUNE, ek So eis: Si apm it eet Aa aoc mn SAN ONO OS LSE ert ie a ee ja ag nw 8 TS. «Son CS A 9 sesh oon : 1 asigapende oie ~wateaneataeie 9p ane 00 aad oe * Popular Science Monthly Barbers from Pole to Pole ig £ 3 we ae 7 4 S +e “tang & we “ Many a soldier literally scrapes his own face; if he is lucky some one holds a mirror for him © Press Illustrating Service This economical man cuts his own hair with two razor-blades tied to his comb How’d you like a hair- cut and a shave in two and a half minutes? Impossible! you say. Not at all, chimes in the man shown above. He is Mr. Len Gallo- way, champion barber of the world. He won two gold medals in England for shaving a man in twenty seconds An idle jest no longer —the lady barber. She may actually be found at this shop (no, we won’t give you the address). As yet, there have been no casualties, and you will have to admit the superiority of the feminine touch 68 © Press Illustrating Service Perhaps John Kelly, of Cincinnati, is not the speediest barber, but he is without doubt the tallest one. He measures nearly seven feet, and for years has had to have all his clothes— even shoes and socks - made to order © Press Illustrating Service No wonder he smiles so smugly! He has cut the hair of both the present Prince of Wales and the late King Edward

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May, 1920 “We the People of the United States—” (Above) Wards of our flag: Fili- pino aborigines who bear the same relation to the island civili- zation that In- dians bear to us (Left) If ali Ameri- can men were as strong and husky as this one, they could dress in beads and feathers | too. He comes from Sa- moa, one of the many islands found in the Pacific Ocean © Publishers’ Photo Servi Young Porto Rico Americans stop playing to be photographed In spite of his bare-foot state and ragged clothes, this man from the hills of Arkansas has a family tree that can be traced back to the early colonial days of this country The Alaskans pictured here live in a quiet hut made of sod, and pay no rent to a landlord who may put them out because they have children hdl | 6S

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eee ee ee eee — woes GNC A AS i, MR At Np oo a NO eae seve et se REN CRT RE NARS thn an ee ee ae ee connate nig are ned is \ aac ore ee eae See ae se ae ere ee “ eect A Pe Te Ae Rt NRA ERNE ESI: RINSE SIS ERR LEE AIT EIT Pe GLE RRE a it a cme pots Denitllaintnrnin: tee + i sapiens pal aDee nase a8 Pare anton . 34 nS Ee ee ee a This Truck-Tractor Cuts a HAT would a driver do with 60 horses and 7 wagons loaded with 42,000 pounds of wet clay, when he came face to face with a tangle of dense woods? His teams would refuse, as politely as teams can refuse, to budge a foot into the underbrush. But the driver of a combined truck and tractor puts ona spurt of gasoline and drives straight into the thicket; nor does the locse sand underneath the wheels interfere with his progress. A truck combined with a tractor whose wheels work independently, constructed small enough to travel the narrow country rcads and capable of making headway over loose sand, mud, or snow — when the front wheels are re- placed by runners—is indeed a blessing to the Popular Scrence Monthly Road through Underbrush _ does the work of sixty horses and does it better. Naturally, when the tractor is busy in a rough field, or is digging its way through soft sand, its supply of fuel must be adequately provided without unnecessary in- terruption in the work. Sixty gallons of gasoline can be carried in the truck, twenty gal- lons under the front seat and forty gallons in a tank in the rear. The driver makes use of a hand- pump to replenish the supply in the front tank when the fuel there is exhausted, the gasoline being taken from the rear tank. Speeds of 114, 3, and 51% miles an hour are provided, and when desired the tractor can reverse as easily as the old team would “back up” when the word was given. farmer and the rural road-builder. It con- sumes two gallons of gasoline an hour in regular work under average conditions, or three fourths of a gallon of case oil (oil com- pressed from natural gas) in ten hours, and two gallons of. cheap Through densejungle- like thickets in semi- tropical climates, or through the snowdrifts of the northern country, this tractor-truck will make headway. It is of particular advantage when hauling a train ‘of sand-filled wagons across rough country in black oil a day are used on the traction wheels. This mechanical steed Filling Cement Bags ILLING barrels or bags with cement or other fine pow- der is dusty work. The workmen try to protect them- selves by wearing goggles and by screening mouth and nose with cheesecloth bandages, but these means of protec- tion soon prove inadequate. The accompanying pictures illustrate the method employed in one of the large cement mills in Germany for eliminating the dangers and discomforts caused by cement dust during the weighing and packing operations. The apparatus used automatically weighs and fills the cement. When bags are to be filled, the empty sacks are fastened Not only can the truck-tractor easily haul eighteen tons of pig-iron up an 11 per cent grade: but when a tract of heavy oak grub soil is to be broken, the tractor-truck goes right in and cuts furrows which a new road sys- tem is under construc- tion. by Means of Suction with their open ends around circular frames supported by balanced beams inside of an iron case provided with an air- tight door. When the door of the filling cabinet is closed, the constantly working suction pump exhausts the air in the cabinet, a valve is opened, and a stream of cement dust is sucked from the big tank through a tube which ends above the open end of the sack. When the cement in the bag has reached the desired weight, the sinking of the frame end of the scales opens a valve, admitting air to the case; as there is no more suction, the flow of cement ceases. Barrels are filled in a similar manner. When the door of the cabinet is closed, the air is exhausted and the cement sucked into the bag from the tanks By means of this apparatus barrels may be filled and weighed without causing a cloud of dust to endanger the health 70

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Your First Reader told f f j you, in simple words and large type, that pussy’s whiskers, wide as his body, were there to warn him of the size hole he could crawl through; but that reason alone did not suit psychologists, and they have recently proved that whiskers aid the cat’s eye Why Does a Cat Have Whiskers? Some startling conclusions on the subject Why does a cat have whiskers? This question comes under the larger one— what is the function of eye appendages? Mr. P. F. Swindle has investigated this subject very thoroughly, ‘and he has formed some startling conclusions, which he reports in the American Journal of Psychology. : Most animals have eye appendages that seem to obstruct their vision. And ig many of those that haven’t any use sub- stitutes—the snake, for instance, con- tinually thrusts out its tongue. But, according to Mr. Swindle’s investiga- tions, these obstructing appendages really aid the eye. When an animal watches its prey or stares at a branch that it intends to land on, it wiggles its whiskers constantly and thereby rests-its eyes. Thus, instead of becoming blurred in time, the object it watches is always sharply defined. Mr. Swindle experimented with a tom-cat, watching him first with his whiskers on, and then watching him after the whiskers had been shaved off. Tommy soon changed from a fat, well fed cat to a thin, hungry one. Though Tommy sits perfectly still and stares at the rat, he wiggles his whiskers constantly. Each wiggle rests his eyes and brings his visual power back to its normal sharpness. Stare fixedly at an object, and it soon blurs; half close your eyes and it stands out again a Tommy leaps and lands his victim. His eyesight is kept sharp by the aid of his whiskers and he is consequently a fat, well fed cat But inquisitive psychologists shaved off Tommy’s whiskers, and for the first time in _ ip his fat life he leaped’ and missed. In a few weeks he became melancholy and thin. Imitation whiskers were glued to his cheeks and his batting average improved perceptibly The squirrel and many other ani- mals also need whiskers for ex- pert vision. What is more, the squirrel’s bushy tail, which he constantly swishes, helps hi sight. Deprived of both whiskers and the hairs on his tail, he will often miss a branch when he leaps

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Put your pot on the burner, light the gas, and trust .to*the regulator to keep the Irish stew from. boiling over It Keeps the Pot from Boiling Over GAS regulator like that shown above is a great boon for a busy housekeeper. She may place the pot or the stewing-pan on the stove, and devote herself to other work without »eing haunted by the fear that the pot may boil over or the food in the pan become scorched. The regulator consists of a cham- ber closed by a flexible thin metal Popular Science Monthly ° A notable sack of wool used as a seat for distinguished guests at an old Lon- don residence—reminder of early days A Woolsack in an Old | London House i HE hall of an old London resi- dence is a strange place for a sack of wool, but a very notable one may be seen at Stoke Park, Ipswich. The sack is five feet six inches long and three feet six inches wide, and is covered with crimson material which long since has be- come much faded. This woolsack has an interesting history. plate, and is connected by a thin The seat of the Lord Chancellor, copper tube with a capsule resting against the bottom of the pot or pan. The capsule, the tube, and the regulator chamber are filled with a liquid, the expansion of which causes the membrane of the regulator chamber to bulge outward, thus partly closing the opening through which the gas is fed to the burner. The fiow of gas is diminished until only enough gas is supplied to main- tain a small flame. An Invalid’s Electric OT much larger than a tricycle is this new electrically propelled invalid’s chair. It is so easy to drive that an invalid can manipulate it; and it goes so slowly that there is little chance of acci- dent. The power lever is located on the right arm of the chair, and the speed is regulated by the back and forward move- -‘ment of the lever. The batteries that give the small electric its power are hidden beneath the seat.- Up front there is a hood; but, since there is no engine and radiator, we fear that it is empty. Why have one at all? Perhaps for style, or for lunch. The motor-driven rail saw at work cutting out a damaged section of rail. It saves taking out the whole section and sending it away to a repair shop, with the usual resulting delay Cutting Rails with a Motor- Driven Saw “CEE that worn section of rail?” asked the section boss, pointing it out to the visitor. Then he continued: ‘Just watch how quick a job we make of it!” And in less time than one would guess the rail was made as good as new. How was it done? Not, it is plain, by the old method, which was to have a gang of men take up the entire section of the rail and send it away to the repair shop to be sawed off, pieced out, and welded—a job that gener- ally used up valuable time. The new way to handle the job is to use a portable motor-driven saw. Along comes the saw, and it neatly cuts off the bad part of the rail at any desired angle. A new piece of rail is cut to the proper length and welded in place, and the sec- tion of track is as good as new. This saw may also be operated by hand if desired. " machine in the Hcuse of Lords, is called the Woolsack because in the time of Edward III sacks of wool were placed for the members of the Heuse to sit upon. The custom was really a subtle kind of lobbyism, the woolsack perpetually reminding the law-makers of England’s staple trade. The late Lord Gwydyr retained the woolsack here pictured as a memento of his early association with the House of Lords. Seeing His Faults F a man can see his own faults he will soon correct them. That’s why a mirror is placed alongside of each rowing- in the training quarters for students of the University of Pennsylvania. The candidate for the crew knows just how a stroke should be made, and if his is wrong he will be able to correct it. The coach walks up and down, directing the men. This method of training is quite dif- ferent from the one used in most universi- ties. The men usually row in a real boat that floats on real water. The coach stands near by and gives directions. This invalid’s chair is driven by electricity; the occupant turns on the power by moving a lever on one of the arms He watches his rowing motions in a looking-glass and thus he is able to correct the faults that he sees in his stroke

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Flies hover around garbage-pails, so why not set your fly-trap on the garbage-pail’s lid and capture them? Where the Fly-Catcher Will Do Most Good FLres always flit around food. They’re not very particular about what they eat, and generally they If you like jazz, buy a jazz outfit; with it you can make all sorts of weird noises in the name of music Get a Little Jazz Band for Your Family \ , JHY not have a little jazz band _ in your home? Manufacturers have met this need, and a complete make the garbage-can their head- quarters. John E. Connolly, of Racine, Wis., noticed this and decided that the best way to round up the pests was to set a trap for them near their favorite hang-out. And so he invented a new fly-trap that fits on top of the garbage- can’s lid. It is a wire-screen cage in the shape of a cone, and has a central tube leading down to the knob on the lid. At the bottom of the cage, resting on the lid of the pail, is a pan filled with fly poison. Helmets Made to Order VIATORS’ helmets like that pictured below are so carefully made that a plaster cast of the airman’s head is neces- sary. To achieve the utmost in telephony in the air the conditions must be made noiseless. The roar of the airplane pro- peller, the aeolian tunes played on the tense wires, all tend to drown out the A homemade bomb. It had no cap and so it didn’t go off. The villain made it out of old clothes, burlap, rope, dynamite, nails, black powder, and an unknown oily substance A Bomb Made of Burlap and Old Clothes | i the dead of night the black-hander lit the fuse and threw a bomb in Tony Perino’s front yard. Was he killea? Oh, no; the bomb was a homemade one, and the villain had forgotten to put a cap on it. He made it out of old clothes, burlap, rope, and, in the center, four pounds of dynamite, half a pound of nails, some unknown oily substance, and a quantity of black powder. He also attached a twelve-foot fuse'to it. The fuse burned down to within a few feet of the bomb and sputtered out. Even if it had burned to the end, the absence of a cap would have prevented an explosion. faint sounds in the receiver, which may be of the utmost im- portance, messages from some _ point miles away. Mr. C. W. Sirch, an industrial en- gineer of Los Ange- les, has invented a double helmet which closely ~fits the aviator’s head. It is made of felt to deaden the sound from outside sources, and over it fits another hel- met into which the telephone wires are fixed. An air-space jazz outfit, including a cow-bell, a triangle, a drum, and several other equally effective noise-makers, can now be bought in many novelty stores. All of the jazz instruments are small and you can keep them on top of your piano ready for instant need. We are told that “for parties, masquer- ades, and the like, a home jazz outfit is the proper thing.” Be that as it may, it is at least a noisy thing and will drown any bad notes that the jazzing pianist may strike. Hypnotizing a ’Gator “ALVER hypnotize a chicken? or a cat? or a snake?”’ asked the inquisitive one. “No, I haven’t,”’ is the reply. “But if you'll just step out here in the back yard I’ll show you what I can hypnotize.’ Out there in the yard isa young alli- gator. Of course, he’s planted there fresh from the en- closure where they keep alligators at the zoo. Then the process of hypnotism be- gins. The. young *gator is switched over on his back and a firm hold ob- tained so he cannot escape before he is brought under the influence of the hypnotizer. The demonstra- tor then begins to rub the under side of the alligator’s throat. If an old crusty specimen separates the two helmets, and the tel- ephone receivers are attached through a the inner helmet of felt; it is slit in the inner through the slit in the hat that the hat. telephone receivers are attached At the left is held a plaster cast of the aviator’s head, and at the right Petting the animal under the chin while he lies on his back makes him fall asleep: this is a youngster; the job is-not so easy when old alligators are to be ‘hypnotized were at hand, great care might be re- quired not to tickle him; but the young alligator merely goes to sleep. © Kadel & Herbert ED A a orem Ie 9 AS eee Sng es etn ne Se a a A RR ae et et sac SM ES RIA Sc gg sete ti IE A EEE ernment

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These dogs pull their cart out into the deep water, where it fills itself Water by Dog-Power [NDIANS in some parts of Canada have a strong prejudice against using the water near the shore of a lake for drinking, and an equally strong prejudice against exerting themselves in getting a supply from deeper water. Their problem is solved by the use of a rude water-cart drawn by dogs. The dogs are trained to draw the cart out into the deep water, where it fills itself, and then to pull it to shore under the direction of the owner. What Calorene Gas Does gaint the great unloved, has done at least one good deed for the world. It is supplying us with calorene, a new cutting gas that is not unlike acetylene. Professor A. S. Kinsey, of the Stevens Institute of Technology, was the first one to develop this gas. The high ratio of its carbon content to its hydrogen content is largely responsible for its fine cutting qualities. An analysis of it shows carbon, eighty-six per cent, and hydrogen, fourteen per cent. Acetylene gives a maximum tempera- ture of sixty-three hundred degrees Fahren- heit, and the new gas gives sixty-two hundred. Calorene may be compressed and stored in cylinders. Most cutting gases leave an oxide coating on the metal that is very hard to remove. But the coating left by the new gas is thin and fragile, and does no harm to the metal below. This inhaler works automatic- ally to enable the wearer to breathe only fresh air that is medicated to kill the germs A New Nose-Mask that Filters Out the Germs NEW type of inhaler strapped over the nose presents the formidable aspect of a gas-mask, but its working principle is applied forcibly in the war on disease. ‘ This inhaler has tworubber valves, which work automatically. One of the valves permits the inhalation of fresh air, which is medicated and filtered in the inhaler. The other valve permits the exhalation of the gases that are generated in the process of breathing. It is only necessary to insert the remedy, strap on the inhaler, and just breathe naturally. Popular Science Monthly Scarecrow to Us, God’ to the Indians : N2r all gods are beautiful. Visit the Canadian Indians of a certain section, and one of the most conspicuous objects to be seen in the fields will be what at first sight seems to be a scarecrow. But it is nothing of the sort—it’s an Indian god. In the middle of the large plain is a bundle of old clothes draped about a stout pole. A knitted hood, surmounted by a flabby hat, adorns the faceless head. A muffler is tied around the neck. Plenty of extra clothing is piled around the feet on the ground. Tin pails of liquid re- freshment and food are placed near by. So terrible a god must be kept in good humor; hence the solicitude for its welfare. The oxide scale that calorene leaves on the metal being cut is easily removed This married lady keeps her face covered; she also keeps a hand on the gigantic fish-trap 74 An Indian god surrounded by food, drink, and clothing. It looks like a first-class scarecrow A Huge Fishing-Pot "THE making of fishing-nets is one of the industries of British New Guinea, and the strange dark people of these Pacific Islands are adepts in both the making and handling of remarkable fishing-traps. Like a gigantic hornets’ nest, or like a mys- terious conical basket which might enclose a bottle of the choicest vintage, these fish- traps are constructed. Strips of black cane five feet in length are used in making these “fishing-pots,” as they are called. The traps are used in. the swamps to catch small swamp fish, and are thus closely matted to hold the catch. It is a custom in the Girar tribe for the married women to wear _ head-masks, though they are not so particular about covering the rest of the body.

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P May, 1920 © Kadel & Herbert This little ‘“movie” star has a pair of shoes for each day of the month Thirty Pairs! She Must Be a Millionaire ON person in the world, essie Barriscale, a moving- picture actress, has thirty active pairs of shoes—one for each day of the month. This proves two things: first, that the “fabulous” salaries paid to movie stars are not fabulous at all, but very real. Thirty times twenty (let’s say) equals six hundred. Why, six hundred dollars is more money than many a hard-working school- teacher earns in a year! The second point is_ that moving-picture stars don’t prac- tise what they preach. Was it not this same actress who starred in a play called “Shoes”? In the play she sinks to the depths for the sake of a much-needed pair of shoes. The Complexion that Won’t Come Off. ‘THE complexion that won’t come off is being administered to the. girl -in the picture below: Her beauty doctor uses an electric tattooing needle; he tucks pink pigment under her skin that perforce will neither rub off, wash off, nor fade away. These questions naturally arise: Will it harm her skin and prevent proper respira- tion? When the outer skin wears off, what will happen to the pigment? Ask any man who has gone through life _ tattooed and he will be able to answer the questions for you. A beauty doctor is tattooing this girl’s cheeks with pink pigment Photograph by Louis H. Talavera Soro A direct result of General Gomez’ experiments in cross-breeding zebu and American cattle is the increase of the milk intake at the model dairy at Maracay. The butter, cheese, condensed milk, and other products are shipped to all parts of the country An Interesting Experiment in Hybridization ROM eastern Africa to Trinidad, and from there to the estate of General Juan Vincent Gomez, the president-elect of Venezuela, the zebu has gone to find himself- the subject of a remarkable experiment; for the distinguished general is one of the world’s greatest cattle- raisers. In the cross-breeding of zebu bulls with Holstein-Friesian, Hereford, Jersey, and other pure-blooded stock imported from the United States, a remarkable hybrid cow has been produced. It is slightly larger than the northern cow, and it lacks the hump of the zebu. The milk production of the hybrid has been found to be very much greater than that of the northern cow. especially when it is raised in the tropics. The yield of beef is also better in quality and quantity. What is of great importance, also, the hybrid is immune to the tick and to the organic diseases to which domestic cattle are subject in the tropics. 75 In China you must rely on traveling bar- bers for a hair-cut; it’s a case of luck In China the Barber Comes to You OU can never bc sure of getting a hair-cut in China. Barbers in that land have a taste for travel, and they carry on their business in a little shop on wheels. The . matter of a hair-cut, therefore, is left to fate, which comes when the traveling barber gets around your way. The man in the picture above was very fortunate. He met a barber when his hair was only a few inches long all around. Hooking the Shoe-Horn o ? ANG it! What’s the matter with this shoe-horn?” one is apt to exclaim when using an ordinary shoe-horn; for these supposedly useful little instruments are often annoying to the last degree when they slip between one’s fingers while trying to pull on an unruly shoe. Too, the horn monopolizes the use of one hand entirely for itself while pulling on the shoe. Now we havea shoe-horn with a hook at the end to fit over the finger and prevent the horn from slipping. This new horn is distinctly an advantage to the shoe clerk, for he can use both hands in fitting the customer’s shoe, while at the same time making use of the horn. The simple extension at the end of this shoe-horn enables one to pull on the shoe without the annoyance of hav- ing the horn slip out of the hand Aa ai 0 i eS na

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A gigantic.shut-off valve, inside of, which there is room for twenty-four boys to stretch out ore full length on the “shelves” tightly clamped © Kadel & Herbert Pick up bricks ten at atime! A bar is adjusted across the row of bricks; by lifting the handle the The Size of This Valve Is Easily Gaged by the Human Element 1™ AGINE a valve so large that twenty-four people can look out of the opening into the great cylinder that forms the main chamber of the “shut-off”? arrangement—for the valve is called a ‘‘shut-off’ valve and is used on large piping systems. The height of the cylinder, as scaled from the size of the figures, is about fourteen feet, while, estimating the width in the same way, it is considerably more than seven feet in diameter. Compare this great valve with one of the smallest, the kind com- monly employed on the steam radiator in one’s room. Though ofa totally different type, this is an escape valve which permits the air to pass out of the pipes when the steam is turned on. The little valve on the service pipe, which enables one to cut off the water in an emer- gency, is a miniature ‘‘shut-off’ compared with the huge valve into which a crowd of twenty-four young men can streteh out at full length without discomfort. Uh ge Years. Fae oe, aS The electric retouching pencil guided over the trans- parent negative: the retoucher’s efficiency is doubled Retouching by Electricity i HAT an ideal likeness,’’ remarks a friend. The prints from the latest negative are retouched so that all of the natural defects are missing. Ordinary negatives often contain minute blemishes caused by very small particles collecting on the film during development. Then, there may be wrinkles on the sub- ject’s face which show too strongly as dark lines in the print. -A dark spot or line in the photographic print is a trans- parent line or spot in the negative, and opaque material is necessary to touch out these defects on the negative to make them invisible when printed. The old way of retouching was for the photographic worker to move the pencil across the negative, laboriously stippling out all of the undesired transparent spots. The new way is for him to make use of an electric pencil. The controlled electric current causes the lead of the pencil to vibrate up and down, thus automatically doing the stippling while the retoucher simply guides the pencil over the negative. Popular Science Monthly Beer labels are worth more than Austrian bank- notes, so a Swiss brewer plasters notes on his bottles © Kadel & Herbert Austrian Banknotes Make Good Beer Labels EHOLD—a bottle of beer! Alas, it is not for you, but for some lucky Swiss. And look at the label—an Aus- trian banknote! In fact, the brewer of this glorious liquor puts Austrian bank- notes on all his bottles. And he is not, as might be thought, rash and extrava- gant, but most economical. The brewer’s name is Krone, and the same word appears in large black type on the note. An Austrian Krone is worth less than a cent, a label more than a cent. Hence Krone uses Kronen. Reducing a Brick-Pile with Speed OADING bricks takes time when each brick must be handled separately. Perhaps thousands of men handling bricks were contented to go on handing them out singly or in pairs, until one day along came a man with an idea. “What a laborious way to pass bricks!”’ and he immedi- ately planned a quicker way. A brick-tongs, capable of lifting ten bricks at a time, was the result. One has merely to adjust it for the number of bricks to be carried, set it down so the ends project over the row of bricks, pick up the handle, and the mass can be lifted easily. The principle upon which the tongs works is that of a curved lever, the handle when raised serving to clamp against the brick at the lever end of a horizontal bar. 76 © International Film Service A horse standing patiently on a roof? Just the ad- vertising scheme of an enterprising owner of a stable Fresh Air for a City Horse a HY do they keep a horse on the roof?” pas- sengers on the elevated trains in Brooklyn are asking one another when they look out of the windows and see a large white horse standing near the edge of a flat roof. One with sufficient curiosity, who asks the question of the man who runs the livery stable downstairs beneath the remarkable roof-ground of the white horse, learns that the animal is kept there merely as an advertisement. You see, it is an artificial animal—the famcus Wooden Horse of Brooklyn.

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May, 1920 © International Film Service Two receivers double your hearing power. Combined with the transmitter, the instrument is found very easy to handle Put Both Ears on the Wire and Double Your Hearing ‘““LTJELLO, hello—I can’t hear you!’ So saying, you put your finger in your exposed ear and try to shut out the noises around you. Your telephone ear works at cross- purposes with your other one. But if you used a double receiver like the one above both ears would be listening to the same thing at the same time and your hearing power would be doubled. Receivers and transmitter are combined in one instru- ment that fits in a hollow telephone-stand. Thus with one hand you could operate both. Men like the new receiver, but girls don’t. It interferes with the great puffs of hair they wear over their ears. Heating Metals in a Self-Regulating Electric Melting-Pot BVERY metal-worker has probabiy received a jolt, on returning after a brief absence from his melting-pot, to discover that he had failed to turn down the gasoline torch under the melting-pot to prevent too high a degree of temperature being raised. Not only was the lead burned, but the heat from the overheated apparatus had set the near-by woodwork afire. He resolved this should not occur again. So the next time he was careful to turn down the flame of the torch when he expected to return in a few minutes. This settled into a temperature too low to keep the metal in a molten state, and time was lost in reheating it. But now there is no need for such inconvenience. The metal-worker can leave his melting-pot unmolested for any interval if he uses an electric self- regulating melting-pot. It looks like a square box supported by short legs, and is fitted to be con- nected with any electric circuit. The container into which the metal is placed is surrounded by a coil that is insulated to prevent radiation of temperature wasted on the outside, and to heat the container evenly on the inside. Its re- markable feature is the self-regulation of its own temperature. The wire that is used offers increasing resistance to the current as. its temperature rises, fixing a maximum limit at 765° F. Puss in a Bundle Seen A protractor level attached to the handle of a drill to work at an angle Drilling at an Angle T° drill a hole at a certain angle, there is an arrangement by which it can be done with an electric or hand drill. A protractor and a small spirit-level furnish the means. The level is set at the desired angle as indicated by the protractor, and the drill brought to the angle necessary to make the level stand at zero—or ‘“‘level.” If the hand is as steady as it should be, the angle of position can be maintained until the hole is started, and after that the matter becomes easy. y © Kadel & Herbert Wrapped in a paper cornucopia, pussy is an easy bundle to carry around ARY has a little cat; his hair is white as snow. Everywhere that - Mary goes, the cat is sure to go. He doesn’t trot along behind her, either. She carries him in a paper cornucopia. Only his head peeps out, and from the sleepy expression on his face it would seem that he rather likes being wrapped up like ten cents’ worth of cinnamon. With no stray feet, claws, and tail to worry about, his mistress finds him easy to carry, 77 Turn on the current and this melting- pot will control its own temperature so that a maximum of 765 degrees is not passed. The self-regulating melting- pot weighs only twenty-five pounds The new asphalt iron has a kerosene- burner inside. Almost like ironing a shirt, the workman passes the hot iron over the asphalt and heats it A Self-Heating Smoothing-Iron for Asphalt Pavement ELCHING forth a cloud of smoke and filling the air with ashes, the wood-fire wagon comes down the street. Workmen carry the irons from the fire to the asphalt spread on the street, and much of the heat is lost in transit. Time is also taken up in the process, so that the old way of heating the asphalt is inefficient in economy. Now there is an iron that saves from 60 to 75 per cent of fuel cost. It does the work of three men, and does away entirely with the smoky wood fire. The asphalt smoothing-iron has a heating chamber within, supplied with a 1 4-gallon oil-tank equipped with a hand pump and a kero- sene-burner. The burner is so arranged that the compressed air forces the flame directly into the iron. Light the flame in the burner and pass the iron forward over the asphalt, and it will immediately become heated to just the right temperature to permit the street- paving job being finished at one fifth the cost of the old method.

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This kind of “dog” does not need a wrench to operate it: it simply opens, slips over the work, and the cam jaw closes automatically. It is made in five sizes The die-head is auto- matically opened as soon as the travel of the turret is stopped, or the head can be opened at any point by retarding the travel of the turret slide by ma- nipulating the handle Do It with Tools and Machinery Winding armatures of elec- tric motors is a long and tedious job when done by hand. Here is a specially de- signed motor-driven machine for doing the work easily Popular Science Monthly For metal-working machines comes a simple attachment that automati- cally opens and closes the work-. holder during the feeding and retrograde movements of the tool This electrically driven scraper scrapes alumi- num and brass castings, auto- mobile crank- cases, etc., and gives the opera- tor acleaner and more uniform jobin one eighth the usual time About all that could be demanded of a sand-riddle is embodied in this small motor- driven machine. A-perfect whirlwind of sand comes out at the bottom when the operator scoops in a supply at the top This ‘both - ways” planing tool permits a roughing cut to be taken on the outward or slower stroke and a finishing cut on the return or fast stroke: dou ble efficiency 78 This apparatus in- cludes an attachment for holding and feed- ing tool bits against the grincing wheel. The method elimi- nates the slipshod hand-grinding way, which gives an unsatisfactory edge m j Me

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It clamps around the preserve-jar cover and loosens it without trouble FPPC LIFT « Housekeeping Made Easy Here are some new machines that help promote household efficiency Press down this can-puncturer, and presto! the can has two holes in it through which the ingredients flow out © Kadel & Herbert An electric light on your vacuum cleaner shows up the dark places under beds and in corners. The attachment can by any amateur electrician be made This electrical water-heater straps around the tank and is protected by a cover that laces over the heating pad Sprinkling the clothes on the line by means 1 of a hose is a much better way than the old hand method, and they can be placed in the basket at once, all ready for ironing. A new fumigator has four candles in place of one. It A thermometer especially does much better work than the single-wicked kind and designed for immersing in if one candle should go out the others will still work cooking liquids, such as This new cake-mold bakes the cake full of holes: do holes render cake more edible? jellies and the like, is a useful new kitchen utensil Here is a cooker that steam-cooks the food. It cannot burn out, and no basting is required. A tight cover, which carries a pressure- gage, clamps down tightly upon the kettle 79

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Popular Science M onthly Solving the Heavy Truck Load Problem INCE tire cost and weight are perhaps the greatest factors of interest to truck-owners, ‘it will be interesting to note that instead of using the giant 48 by 12 pneu- matics, weighing 398 pounds each, on the rear of five-ton trucks, the tandem axle con- struction embodied’ in thenew six-wheeled truck allows the use of four 40 by 8 pneumatic tires, weighing 119 pounds each—a reduction of 279 pounds in the weight the effect than that resulting from the _ three-and-a- half-ton load on two rear solid tires. Road-saving has a tremendous popu- lar appeal, so that such a quality in the new type would not only offset unfavorable sentiment against the use of high- ways by heavy vehicles, but would also be a great stimulus to larger ap- propriations for road im- provements. One striking advan- tage of pneumatics on the tandem axle con- driver on tire changes will have to lift. In addition, the four smaller pneumatics cost one third less than the larger tires. As the same size of tire is used all around on the truck, the eight-inch tire can also be used as a front wheel spare, still further reducing the tire in- vestment and the number of spares necessary to insure continuous opera- tion. No more appealing feature can be found for municipalities than that of road-saving demonstrated by the pneu- The Tilting Steering-Wheel that also Locks UTOMOBILE steering-wheels that may i \ be tilted to give the driver more space to get into or out of his car are not new. Neither are steering-wheels that may be locked. But a wheel combining both of these features is brand-new. This steering-wheel is made in two models, one for Ford cars and one for other makes. In principle, the models differ only in the size and elaborateness of the wheel. It has been approved by the National Board of Insurance Underwriters, which allows a re- bate on theft insurance if it is installed. The double or upward and downward tilting action of the wheel is secured by mounting it on a four-point spider in which the two front spiders serve as the anchor when the wheel is to be tilted forward through a small arc or backward and downward throughagreaterarc. The Ford wheel tilts forward only. Because the wheel always remains permanently piv- oted to the two front sup- ports, it cannot be driven off the top of the shaft to permit of fitting another wheel in order to control the action of the front wheels necessary to drive or tow the car from its position. Increased ease in handling is one of this six-wheeled truck’s most prominent features. Greater braking capacity is also ob- tained by its construction, four brakes being used instead of two matic-equipped ‘‘six-wheeler.”” The av- erage road has the maximum base practicable, and begins to disintegrate under the excessive pounding of solid tires. With the truck weight dis- tributed on four rear wheels, road and truck engineers estimate that the average road will withstand a load up to seven tons under newly developed construction, with no more destructive The plunger lock in this tilting steering- wheel allows the wheel to be turned freely about the top of the steering column, no matter whether the car wheels are turned straight ahead or canted into the curb at an angle You don’t have to stretch your neck to peep into this mir- ror; located at the top of the windshield, it is easily accessible 80 struction is that they permit a far greater operating radius and steadier riding qualities. The six-wheeler seems to cling to the road, and rides so steadily and with so little vibration that, in an experiment where a glass filled with liquid to within an inch of the top was placed on the rear of the truck, none of the water was spilled, even when the vehicle traveled over rough roads. In passing over an obstruction, the chassis rises but half the distance it would in the usual type of construction, and by reducing shocks and vibration proves possession of exceptional riding qualities. In some recent hauling tests be- tween Akron and Cleveland, such cushioning effect was produced by the smaller pneumatics and the multiple- wheel construction that with a five-ton load the truck traveled 48.6 miles at an average speed of 26 miles an hour, and registered eight miles an hour average speed in heavy traffic while coming out of Cleveland. At Last—a Real Mirror for the Automobile F you have ever had a near accident on account of a_ law-breaking speeder coming up on the right side of your car when your fender mirror was placed on the left side, you will ap- preciate the value of the new type of rear vision indicator shown in the accompanying illus- tration. This mirror is placed in the center of the windshield at the top, and gives a clear view of every- thing to the rear on both sides of the road. The speedoscope, as it is called, has adjustable bracket arms attachable to any car. When mounted on a closed-body car, rear vision is obtained through the rear top window. Mat 0 V ‘ i k t f ‘ ] 7 > a _,. _—_— ——- 2 sr

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May, 1920 $633,000,000 for Highways But first the government is measuring automobile impact on roads HE United States govern- ment is planning this year to spend $633,000,- 000 in building permanent high- ways. Owing to the vastly increasing use of the motor-truck and automobile, the road problem has become of _ great importance. Heavy loads at rest on the road surface exert but little effect, except ‘where the surface is too soft to bear the load. A wheel load of 8,500 pounds at rest on an eight-inch con- crete slab on a rather wet clay subgrade ex- erts a fiber stress in tension of only 34 pounds to the square inch directly under the load, as compared with the modulus of rupture for the aver- age concrete road sur- face, which ranges from 400 to 600 pounds a square inch. Hence the only danger of serious injury to the concrete from loads at rest occurs at the corners of the slabs. Impact is a frequent cause of road failure, and, with a view to ascertaining every- thing possible concerning the impacts exerted by various kinds and sizes of motor- trucks operated ,under dif- ferent conditions, the United States Bureau of Public Roads is conducting some very interesting experiments. The scheme in use: is to deliver the impact of a moving truck to a _ small copper cylinder, the blow deforming the cylinder to a definite amount, depending on its intensity. A concrete pit is constructed in the road surface in the track of the motor wheels, and a hydraulic jack is placed in the pit. The plunger of the This concrete pit, with a hydraulic jack and copper cylinder, measures the impact of the blow from the truck wheel passing over it The copper cylinder that measures the blow is set directly under the plunger of the jack, the impact being transmitted through the plunger to the copper cylinder placed directly on the plunger of the jack. Different sizes and makes of trucks, operated at different speeds and using solid rubber or pneumatic tires, have been tested out to ascertain the impacts they deliver. A standard three- to five-ton army truck loaded with five tons of sand, having a to- tal weight of 7,750 pounds on one rear wheel and an un- sprung weight (that is, not absorbed or broken by springs) of 1,837 pounds on one rear wheel, operated at a speed of fifteen miles an hour and falling through a dis- tance of three inches, exerted a maximum impact pressure of 42,000 pounds, which was 5.4 times as great as the pressure ex- erted by a rear wheel wher the truck was at rest. Wher the truck, running at a similar speed, dropped from a height of only half an inch, the impact pres- sure produced was 28,000 pounds, or 3.6 times the static load pressure. This indicates that th higher the fall, the greate is the amount of impact pressure, and also shows that trucks. with great un- sprung weight produce high impact pressures. Similar tests, in which the rear wheel of the truck was forced to strike an obstruc- tion, showed that the impact pressure increased with the velocity and with the height of the obstruction. Wedge-shaped blocks were also placed on top of the plunger of the jack and the truck driven over them, with the consequence that the impact pressure always in- jack is enlarged at the top with a_ physical characteristics before being creased with the angle of inclination platform of suitable size for receiving used in impact-testing work. The of the block and the speed of the the blow of one wheel of the truck. impact deforming the copper cylinder truck. These conditions are dupli- The copper cylinder that measures is then compared with the impact cated in actual road travel when the blow is set directly under the from a resting load necessary to the truck rolls into a depression of plunger of the jack, the impact being deform it to the same amount. transmitted through the plunger to the copper cylinder. Impact is measured in different the road. All of these results will be considered The copper ways, the truck in motion being caused in the future in designing and con- cylinders are each turned from half- to fall through different heights before structing federal highways, which, as inch copper rod, and are half an inch striking the plunger of the jack. far as possible, will be built to with- in length, being heated and standard- The truck is also made to strike stand the impact pressures of the ized so as to be absolutely uniform in obstructions of different 81 heights heavy traffic that passes over them. A a ———

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There’s Always Something New Popular Science Monthly The safety indicator has an electric light to illumi- nate street names painted on the curved glass inserts With this simple tool, engine valves with different angles of face are readily refaced and all carbon pits removed: the valve is au- tomatically self - centered when it is Ps ) put in the ra § holderofthe , apparatus Four of these bar skids are used to each truck wheel to prevent slip- page. Each bar is held by a chain covered with a rubber buffer, which prevents the chains from marring the wooden spokes of the truck wheel ee A new gas-tight piston-ring gets its non-leak properties from the permanent lap joint, which allows for expansion and contraction by reason of the curved surfaces at each end of the ring By a series of multiple units or legs, this tractor walks on the soil without tearing it by cleats or packing it tight by huge flat wheels. It is also equipped with rubber-tired wheels, which transform it into afarm truck, thus making the tractor serve a dual purpose 82 [ a Ae a fo nana us a oxaiet..\* & Here is a machine that is built like a motorcycle and ~ The phantom view of this electric tractor shows the four-wheel drive and axle units. Universal joints and propeller-shaft connect the two with the motor a8 drives like an automobile. It claims riding ™\ qualities equal to the best automobiles 2 © International Film Service P. J. Griffen, of Dorchester, Mass., has invented a new air-lock valve which he claims will increase the life of pneumatic tires fifty per cent. It locks the air in the tube for all time unless a blowout or puncture releases it. No more leaky tire valves or flat tires if this device is attached of your tires. It will reduce pneumatic worries to a minimum

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May, 1920 in Accessories for the Automobilist New inside flanges and three collar stud bolts change the ordinary Ford wheel into one that can be put on or removed in a few seconds The motor bungalow is a com- pact vehicle with kitchen, pantry, toilet facilities, ice-box, clothes and bedding lockers, electric lights, a running water system, a table, and a tent-cot for the chauffeur. Why stop at a hotel when you can carry one along? A leather pad fastened to your au- tom obile door in the manner here shown pro- tects the door top from being marred or scratched A new spark-plug tester tests the plug inside its chamber. A heavy glass lens at the end opposite the cap permits a view of electrical leaks in the plug The feature of this new shop vise is quick jaw action, secured by the screw adjustment and the universally pivoted handle This carburetor has but a single adjustment, which is set for all points between high and low speed. Its makers claim a ten- cent-a-gallon saving of gasoline ineanieuenen At last—a car for everybody at a price that everybody can pay. True, it accommodates only one passenger and has two cylinders; but then, its maker states that it runs fifty miles to the gallon of gasoline This spark-plug is constructed with a static condenser that fires in a vacuum in the plug. The flame fires through oil 83

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Why be bothered with removing bolts by hand when an electric wrench will do it quickly? Popular Science Monthly Electric Wrench for Automobiles HE electric wrench is a new power-driven combination tool by which nuts or bolts may be readily screwed into position or removed without danger of breaking the bolts. It is useful also asa screwdriver or as a portable drill. It has a specially constructed clutch with an adjustable pressure of from ten to sixty pounds. When a nut or bolt reaches its desired posi- tion the power is automatically - shut off. Among the many uses of the elec- tric wrench are those of power buffer or grinder. It is especially valuable for grinding out auto- A Combination Measure and Funnel F you have ever tried to pour lubricating oil into the breather- pipe of your automobile engine with- out the aid of a funnel, you know how much oil is wasted that way. Of course, no motorist wants to waste expensive lubricating oil, but many times the funnel is mislaid or lost. With the combination measure and funnel shown in the accompanying illustration, this would be impossible, for the funnel is an integral part of the measure. The funnel is in the form of a flexible metal pipe which can easily be bent so as to reach inacces- sible oil-filling plugs such as the one shown in the picture. This measure comes in three sizes, to hold one quart, two quarts, or one gallon. Many and varied are the ways for carrying automobile bodies. One manufacturer carries twenty-one bodies on a truck and trailer | Shipping Automobile Bodies by Truck ECAUSE automobile production is far behind the demand, many passenger-car makers have had to resort to new means of getting ma- terials shipped from other factories. Among other things which it is neces- sary to have in order to sell cars, is the body. These are not generally made in the same plant where the machine- work on the metal parts of the car is carried on. This was the case of an Ohio car- maker whose body plant was one hundred miles away. The usual shipping time by railroad between the two points is one week. Recently a. whole new series of cars was held up because the bodies had not arrived. Because of the run-down condition of the railways, delays became more and more numerous. As a result, the passenger-car maker had to call in his younger brother, the motor- truck maker, to help him out. Exactly how this was done is shown in the accompanying illus- tration. This motor-truck and trailer can carry twenty-one car bodies, the same number that can be loaded into a forty-foot railroad car. It makes the round-trip dis- tance between the body plant and the car factory by road in twenty hours, iricluding the time of loading and unloading. This means an average road speed of fifteen miles an hour. While it costs more to ship car bodies in this way, it is worth while because of the certainty of the delivery. Special racks are used on the truck and the trailer, and provision is made for bolting the bodies down to prevent damage. 84 mobile cylinders and valves. There are special folding or locking handles, so it can be used by hand for starting or loosening nuts or bolts that have become rusty. The motor will oper- ate in either direction, with three speeds forward and the same number when reversed. This new tool embodies certain mechanical principles that have never been combined in this way before: it makes possible the use of a rapidly revolving tool propelled by greater power without danger or fear of damage. The cost of operation is said to be from two to five cents an hour. A combination measure and funnel Carrying Eggs Without Breaking Them EVERAL United States mail motor-trucks operating on the rural truck routes out of Washington, D. C., make use of an ordinary canvas-covered mattress to protect the cases of eggs in transit. The post-office rural delivery trucks must maintain their schedules irre- spective of road conditions, and when any speed is attempted over poor roads the entire load is sometimes thrown an inch or two off the floor. Without the mattress to cushien the cases when they come down, many eggs are broken, with resultant loss either to the farmer or the government. The mattress in the bottom of the truck saves the eggs from breaking Stc lux of bo be ———————____—_s7-s,_,_2~ ||

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May, 1920 Stop and admire the luxurious smartness of these automobile bodies: wouldn’t you be proud to own one? Riding at high speed over shell-holes and rough roads demanded a substantially built car. General Persh- ing chose the very best for this work, and it stood up under the strain onmne 7 SPANNER tte Very Latest Fashions in Automobile Bodies A coupé for four has a de- cidedly low hung appearance, due to a new method of body- mounting - in combination with along wheel-base. The body sides are very deep and the interior well arranged Clara Kimball Young likes to pose in her own specially built car. It is cred- ited with ninety horsepower and carries the disk wheel clear of the fender Even roadsters have enclosed bodies these modern days. Here is This new sedan has a spring suspension which is unique in that one in which are incorporated many interesting refinements the springs are at an angle to the car’s axle: its price is moderate While in sedan dress, the fact is noted that there are only One moving-picture actor decided that standard bodies two doors. Its engine has several unusual features, and were not individual enough for him, and he designed this increased power is claimed over previous models of its make special body, which reflects his excellent construction ideas ee: {f ~

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Settee AVE you ever wondered H how a “movie” star could shake hands with herself? In the first picture Genevieve Fluff, famous for her work in the five-reel thriller “Double Exposure,” is doing this. According to Arthur Miller, the camera-man, this is how it is done. Double exposure means two pictures on the same film foot- age. First, one half of the film is masked off by shoving half in front of the camera’s lens a mat—a thin piece of black cardboard. The same method is used in taking the second half. The action of the star is regulated by counts. The camera-man counts—say, up to ten; the director instructs the star what to do during these counts; and the star plays the skilled marionette. But to shake hands with oneself is a difficult feat. Perfect coopera- tion of the principals and exquisite finesse in the art of double exposure are required. Among the many mishaps that beset double exposures, four loom up prodigiously: 1. The mat that ‘“‘splits” the film in half may slip, or the camera-man may accidentally move it a fraction of an inch. The line of demarcation being thus shifted, the exposure would be ruined. 2. Lack of synchronism by the three principals; in moving- picture patois such an error is termed “‘disjointed action.” 3. The carbon lights illumi- nating either scene may flicker —as a lamp often does. 4. If the first half of the double exposure is taken satis- factorily, but the second half is not, it must be retaken. By Dorothea B. Herzog Philip Hatkin, another ex- pert double-exposure “‘shoot- er,” recalls an instance when it took seven hours for a man to shake hands with him- self. Why? By explaining how the picture above was taken, you will understand. Genevieve Fluff is going to shake hands with herself. The camera-man _ prepares his camera. The director turns to Genevieve. “Did you put the cardboard inside the sleeve that is to rest against the tree?’ Genevieve Substituting a barrel- head for muscle. The first half of the picture took in down to the oe tion girl’s hand only and did ‘ not include tke ends ‘ of the barrel-sup- ported chair legs. Then boards _rest- ing on boxes were run be- neath the chair seat for support, the barrel was removed,- and the cam- era registered the lower half of the picture 86 When a motion-picture ac- tress is up a tree she can— with the camera’s aid—ex- tend a helping hand to her- self and get back to earth Photographs courtesy of Arthur Miller, of the Famous Players-Lasky Corpora- Popular Science Monthly Exposing the Double Exposure in Moving Pictures Strange feats made possible by the tricks of the camera nods. The camera-man comes forward. ‘‘Listen,”’ he explains, sketching the action of the first double-exposure scene. ‘“‘While I count up to five, you walk over to the tree. When I say 6, 7, 8, you extend your arms upwards.” The scene is re- hearsed, Genevieve’s actions in accord with instructions. Notice that all of Genevieve is taken except her hand. Why isn’t the hand taken? Because at the count of 8 it extends beyond that part of the film exposed to the light, and is therefore cut off by the mat that splits the film in two. Before Genevieve moves her position, her sleeve is nailed to | the tree’s trunk. Here is where the cardboard, holding the sleeve in position, proves its worth. As Genevieve wiggles out, another girl, whose hand re- sembles Genevieve’s, wiggles in. Genevieve hurriedly slips into a shirt-waist, a replica of the other. The -camera-man pre- pares his camera. Holding the mat that masks off the blank half of the film, he shoves in a similar mat from the other side, being sure they fit snugly. He now counts and reverses the crank of his camera. At 9 the film is where it formerly was. The mat covering the blank side is cautiously withdrawn, the completed half of the film re- maining masked off. Genevieve now returns. She climbs into the tree. . The “extra” in Genevieve’s pose on the ground is ready to extend her hand. But only her hand and a bit of the shirt-waist sleeve crosses the line dividing the film in nalf at the count of 8. If all goes well, the hand and sleeve will neatly fitGenevieve’s arm on the first side of the ex- posure. .Genevieve will shake hands with herself! “While we count up to 5,” rehearses the director to Gene- vieve, “you say, ‘Oh, I don’t want to jump down; I’m afraid.’ At 6, 7, slowly extend your hand; at 8 grasp .the girl’s hand as it comes forward.” The result, on the screen will be Genevieve’s arm on one side, and a hand clasping Genevieve’s hand on the other. Camera-men speak of aseven- hour double-exposure as a mere trifle. May,

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May, 1920 KERR RKARRRRRRRRRRRRARAR RAR RR OR -. 4 WIPE IPI TT I a v. BEST RETAIL TRADE | (Trade Mark Reg US Pat Of and Foreign Countries ORR A CO Bee: ss OO THE QUALITY OF B-V:°-D-: UNDERWEAR IS A TRADITION WITH 1TS MAKERS AND A PROVERB WITH ITS WEARERS NO UNDERWEAR _ IS B:V-D: WITHOUT THE ABOVE RED WOVEN LABEL THE B:V:D:- COMPANY N se i i v. ERIE RS f VSS oo LAA A el

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NYONE who can handle a plane well enough to smooth a strip of wood sufficiently to make a good glued joint will find no great difficulty in making his own split-bamboo fishing- rod. Ispeak from experience because I am merely an amateur with tools and have made over a dozen split -bamboo rods that compare very favorably with those costing three times as much as mine. The simple outfit that I have found most convenient consists of a 6- or 8-in. smooth- ing or block plane, a 6- or 8-in. bastard cut flat mill FiG2 The bamboo strips must be planed to a triangular shape and glued together FIG.3 file, a steel The 60-degree groove is cabinet scrap- found by the 60-degree er, a center notches on the _ gage gage,a few sheets of No. 1,0, and 00 sandpaper, and a can of good glue. The exact dimensions for two use- ful rods are shown in Fig. 1, but any rod may be copied by finding the true taper and measuring the diameter with a caliper at 6-in. intervals from the butt to the tip. The dimensions given cover the specifications for a two-piece one-joint bait-casting rod and a three-piece two-joint fly rod. { have made several rods to these measurements and they have proved of good action, not too heavy, and with sufficient backbone to stand a great deal of hard use. Making a rod of split bamboo is necessarily more complicated than planing a single piece of wood to form a solid wood rod, but if each step of the work is carefully done the amateur will succeed in turning out a good rod. As the strips.of bamboo are split from the whole pole, they must be planed to a triangular shape and glued together as shown in Fig. 2. Some kind of a block to hold the flexible strips securely is necessary. I use two planing blocks, made by planing off the corners of a block of hard maple or birch, each block being 3 ft. long, 14 in. wide, and 14 in. thick. The angle for planing off the corners so that the two blocks may be joined Popular Science Monthly How to Make a Split-Bamboo Fishing-Rod to form a 60-degree V- shaped groove is found by the 60-degree notches on the steel center gage shown in Fig. 3. These can be purchased at all tool stores and cost about twenty- five cents. As this is made of hard- ened steel it may be used to true up the Making your own apparatus adds much to the pleasure of fishing By Stillman Taylor use a common case or table knife. Place all the selected strips side by side on the bench and match them up so that the knots are as far apart as possible. Then saw off all the ends, evenly, about 2 in. longer than the finished joint of your rod is to be, and then mark all the strips at one end, that they may not be reversed. grooves, and a common Before begin- three-cornered file may eo ogee es re eg eg ning, sharpen 2 64 3 3 32 ‘6 2 6 és also be used for the same +--+}, + 1, ~~ your plane to purpose, as it has angles a ee ee the keenest Above, two-piece, one-joint bait-casting i i of 60 degrees. The depth ry sointe 3355 in, lous. Below, three: possible cutting of this groove is not im- portant, but merely the shape, and it must have piece, two-joint fly rod, joints 3619 in. edge and set true angles of 60 degrees, rz otherwise the strips cannot be planed to exact angles. The block shown in Fig. 4 is used for the first rough planing, and the larger block, shown in Fig. 5, for the final planing. Screws will fasten the two blocks together, while a common car- riage bolt will clamp the other ones firmly together. The larger grooves are used for holding the larger sized strips of bamboo used in forming the butt _ and middle joint of the rod, while the smaller grooves on the other side of the block are used for holding the small strips used in making the second joint and the tips. How to Split the Cane There are two kinds of whole bam- boo poles—one known as Calcutta and the other as Tonkin cane. They are equally good for rod-making. Select sound and thick-walled canes and only those of a good yellow color, as canes of greenish color indicate only partly AG DVT OV FIG.5 The block in Fig. 4 is used for the first plan- ing, and the larger block (Fig. 5) for the final planing. Screws will fasten the two together ~~ Ow seasoned wood. No canes less than 114 in. in diameter at the butt end are worth using. The strips are made by splitting the whole cane in halves and then quarter- ing these sections. Split through the eyes, which are the cup-like hollows where the leaves grow. After splitting, select only the most perfect strips for making your rod. A sharp knife is a handicap in splitting the bamboo, so 88 BUTT JOINT ———s -”- ar 2 2 oa ear a a as 2 oat 2S Oo ae i a re 64 3 64 6 64 St 64 S264 iG 6s 2 § e. rR a SuTT, i it i } + + + J ; t : : ; Ti, — t , 18° 24 30 36 42° 48:54 60° 66 72° 78° Ba 90° 96° 102" I MIDOLE JOINT ——sming MG. TIP JOINT ——— a The exact dimensions of two useful rods. Any rod may be copied by finding its true taper and measuring its diameter with a caliper the plane-iron fairly fine for the first final beveling. The tough bamboo quickly dulls the edge, and therefore it must be now and then resharpened, for it is impossible to make a good planed joint without the. keenest edge on the iron. Each strip is planed to a triangular section (Fig. 2) with each side of the strip to a perfect right angle of 60 de- grees. This is done by laying a strip in the groovein the block, enamel side out, as shown at A in Fig. 6, and plan- ing off flush with the top of block. This done, shift the strip to the position shown at B in Fig. 6, with enamel side down, and plane off flush to ‘the block. Now select two perfect strips that match well and place together in the groove, enamel side down, as shown at C in Fig. 6, and plane both off flush with top of block. Proceed in the same manner in getting out the six strips which make each joint of the rod. All planing is done on the soft part or inside of the cane, for the enamel must not be pared away at all to make a good rod. When using your plane, put an old glove on the left hand, which holds the strip, and when plan- ing through knots hold the plane at a. slight angle to the strip to shear off the knots cleanly and not break the fibers of the wood. My experience suggests that the beginner will find it easiest to finish one step of the work at a time and to finish planing all the strips which are to form the larger pieces of the butt joint of the rod and then glue them up before attempting the smaller sections. The butt joint first, then the middle joint and lastly the finer tips is the logical order of procedure in rod- making. A good glued joint can only be made

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May, 1920 Dependable Spark Plugs Did This Ever Happen Io Your y= putting in spark plugs, has your wrench ever slipped, banged into another plug and cracked or broken the por- celain insulator? SS ‘ oe a ———————————— svvrvwvw Sew & 6 Champion Spark Plugs stand this rough treatment and do not crack or break; our famous No. 3450 Insulator has been de- veloped and strengthened to such a degree. Car owners who use Champion Spark Plugs are remarkably free from the ordinary spark plug accidents as well as from troubles due to excessive heat, shocks and temperature changes. There is a Champion Spark Plug specially designed for every type of gasoline engine. Order a set from your dealer today. Be sure the word Champion is on the Insulator and the World Trade Mark.on the Box Champion Spark Plug Company, Toledo, Ohio Champion Spark Plug Company, of Canada, Limited, Windsor, Ontario.

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Punasistiinn suercmnsecemecanecetees seer ee when the strips are first planed as smooth as possible with a keen-edged plane-iron that is set fine to take off a smooth shaving without nicking the surface in the least. As a split-bam- boo rod is made of six pieces, it is absolutely necessary that each face of the triangular % t strip be made , smooth and with a velvet finish to afford a good “tooth” 1 ; . for the glue. , In using the flat { mill file in this way the strip is placed in a groove in the block and the file placed at J right angles to the strip and the filing is done not cross- wiseofthegrain , 2 3 but with it, 1.One piece bait- which is just castingrod. 2. Two- the reverse of joint bait-casting rod. 1 3. Three-joint the usual man- f¢1y-casting rod ner of using a file. By referring to Fig. 7 you will have a clear idea how the strip should be finished with the file preparatory to gluing all together to form the six- piece rod. The work should be checked up frequently with a center gage to be sure that each face of the triangular strip is a perfect 60-degree angle with clean and sharp edges. This is very important, for slightly rounding the edges will make it difficult to form a strong glued joint. Gluing the Six Strips Together The best grades of cabinet glue may be used, but I have obtained uniformly good results by using some good ready prepared glue. In using the glue it is important to have it hot and thin. The liquid glue will prove satisfactory only if it is used in this way, and after once heating it should not be warmed up again. For this reason I pour only a Fig. 6 shows how the strips are laid in the groove of the blocks with the enamel side out. Fig. 7 shows how the strip should be finished very little glue from the can or bottle, place it in a separate can, and keep it in a pot of boiling water until through using it. I then throw away what is left and use fresh glue the next time. The six strips which form each sec- tion or joint of the rod are glued to- gether at the same time. It cannot be properly done separately. Before gluing fit the strips together and see that the beveled sides of the strips fit snugly together. If filing has been well and carefully done all the strips will lie perfectly even together. But if this is not the case, and one strip should sink below the level of the others, it is better to work up a new and more perfect strip rather than to patch it up by gluing in a strip of paper to fill up. The six strips are fitted together and wrapped with common linen thread wound spirally around them. The strips may now be glued up. To do this in the easiest way, unwrap the thread from the large end to the center, spring open the strips, and insert a pencil between them to keep them apart. Now brush on the thin hot glue with a small flat brush, and be careful to touch all the surface of the strips. Next squeeze the strips to- gether and rewind with the thread to force the strips together and make a firm and compact waterproof joint. Unwind the other half of the section and glue in the same manner and re- WRRRREDY CORK WASHERS wood CORE BUTT CAP iG Corks 1 1-8 in. in diameter and about 1-2 in. wide will be found very satisfactory wind with thread. The glued section of the rod should be placed in a warm dry room to dry and should not be mounted for four weeks, by which time the glue has thoroughly hardened and the wood shrunk as much as it is likely to. As the strength and flexibility of a rod depends upon preserving all of the hard, glass-like enamel intact, this must on no account be pared away. When removing the wrappings from the joint, No. 00 sandpaper may be very lightly used to smooth up the surface. The Cork Hand Grasp A hand grasp or butt is best made from cork washers glued to the rod. In making this form of grasp, which is the choice of practically all expert anglers, the corks may be bought ready punched when the fittings are bought of a tackle dealer, or you may punch them yourself, using a regular punch of suitable diameter; or sharpen an ordinary piece of tubing of an old rod ferrule of the required size and make the hole in the center of the corks by means of a rotary motion. Do not try to drive the cutter through the cork, for this will only leave a ragged hole. Corks 1% in. in diam- - 90 Popular Science Monthly eter and about % in. wide are satis- factory. Details of the cork grip are shown in Fig. 8. After punching enough corks to make the hand grasp of the required length—about 9 in. for a bait-casting rod and 12 in. for a fly rod—push on the first cork flush with the butt end of the rod, coat the top of this cork with thin hot glue, and push down the second cork in contact. Proceed in this manner to build up the grip. To make the metal reel- seat a good fit, a wooden core or sleeve of soft wood aie is first shaped Shouldered ferrules are to slip snugly best, and the ferrule cen- OV€T the rod ter is put on by makinga and the out- shoulder as shown above side shaped to SHOULDER FERRULE CENTER make a snug . fit when the reel-seat is placed over it. This detail is shown in Fig. 8. After the corks are all in position, the core is slipped down to butt against the topmost cork and glued to the rod. The reel-seat is now slipped over the wood core and in turn glued to it, which makes a tight and waterproof joint that will never work loose. The hand grasp may now be worked down to the desired oval shape, using No. 1 sandpaper, or the rough paring down may be done with a very sharp knife, finishing with fine sandpaper to make the smooth finish. The butt cap is now glued on. The hand grasp for the fly rod is made in the same way as the one described for making the bait-casting rod, only the reel-seat is placed below the cork grasp instead of above it, and the same wooden core is used to make a snug fit. 2 Putting on the Ferrules Shouldered ferrules are the best and the female ferrule or ferrule center is ‘snugly put on by making a shoulder on the rod as shown in Fig. 9. This is best done by filing the wood down until it is a snug fit in the ferrule. Ce- ment the fer- rules on with the special ferrule cement sold for this purpose. Melt FIG.10. the cement Showing how the guides and smear a are whipped on and how little on the the bands of six are wound wood and a little inside the tube, and shove down into position close against the shoulder of the rod. Tips are cemented.on in the same way as the ferrules. The whole rod should now be given a thin coat of light coach varnish. The guides are attached by means of the invisible knot shown in Fig. 10, hs ie

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May, 1920 HP Reguired JIG Be/t Speed 2780FPM Specified GOODYEAR BELT 8" 6ply BLUE STREAK A quarter turn on short centers, a heavy crown pulley, and the presence of considerable moisture where the belt had to work, kept the Iroquois Pulp & Paper Company, of McKeever, New York, buying a new belt every 30 days for their rotary screendrive. ThatwasbeforetheG.T.M. —Goodyear Technical Man—analyzed the drive to determine what belt would do the best work and last the longest time on it. . The G. T. M. based his recommendations not on the fact that he was a Goodyear man and had belts to sell, but on his practical knowledge of belting plus a careful study of every feature of each drive. He figured in all the factors that affected belt performance and life—30 horsepower : to be transmitted, a drive from a 24-inch pulley 1 on a line shaft to a 23 14-inch pulley on the rotary : screen, a quarter turn on short centers—only 8 feet—a speed of 2,780 feet per minute, and a heavy damp prevailing all the time. A, QVGP em An 8-inch, 6-ply Goodyear Blue Streak met the requirements. Its friction surface held the pul- leys in a firm grip that prevented slippage and transmitted full power. Subjected to the heavy moisture, it did not stretch. To the severe strain imposed by the duty on the quarter turn it responded with inbuilt strength and flexibility. BELTING + PACKING

IROQUOIS PULP & PAPER COMPANY Driven M*< Keever,N.Y. Pulley 7 OUTLINE ROTARY SCREEN DRIVE Four Months of Goodyear Blue Streak service— you will recall that previous belts wore out at the rate of one a month—not only cut belting cost by 50% but also established an operating record of 20% increase in production. The men and ma- chines were going on with their work instead of waiting while the rotary screen had its belt taken up again. A plant analysis which included a detailed study of every drive in the Iroquois plant was made at Supt. Archie Brown’s suggestion when theG.T.M. dropped in to see how the Goodyear Blue Streak was working. In line with the same scientific method of conserving and utilizing the full energy of the plant, the Company has installed Goodyear Hose and Goodyear Packing, confident of the same economical, long-lived service from them as from their Goodyear belt. If you have a belt problem, involving either a single drive or an entire plant, there is something of value for you in the Goodyear analysis idea. The G. T. M.’s time and experience are at your command without charge. If he specifies a Good- year product, you may rely on its ability to do more and better work, over a longer period of time, at lowest final cost. Tue Goopyear TirrE & RusBBER ComMPANY Offices Throughout the World

Copyright 1920, by The Goodyear Tire 3 Rubber Co. 20% More Production—and the G. T. M.

HOSE: VALVES

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ee ee es Te Ng heh nae 8 eNO A a Sa SE eee Use “X” Liquid instead of soldering your radiator NCE a man understands the construction of a radiator he never solders leaks. A radiator is.a delicate piece of mechanism. The walls are as thin as a sheet of paper and per- haps 1-16th of an inch apart. The 3000 or more cells in the average honeycomb radiator have about 16,000 square inches of cooling surface—with more than 24,000 corners that may leak. Imagine hunting for a leak with a white-hot soldering torch and trying to do the exacting work of welding the breaks! Solder is hit-or-miss guess- work. The tremendous heat of the soldering iron expands the thin tubes and weakens the radiator. This causes more leaks and additional expense. * * * ITH “X” Liquid any leak can be repaired in ten minutes. You can do a safe, certain job—at a small part of the cost of soldering. “X”’ is simply poured into the radiator. Not only does it find every leak or break in the radiator, but also leaks in the.pump, connections, water- jacket or elsewhere; and it makes a repair that stands 2000 pounds pres- sure! Thousands of car owners keep “X” Liquid always in the water to prevent future leaks. Eliminates Rust and Scale In every water-cooled car, Rust is con- sf@ntly destroying cooling system walls; and thick layers of Scale bottle up the heat and cause overheating, breakdown of the lubricat- ing film and much engine trouble. The chemical composition of ‘X’’ is such that it loosens all Rust and Scale now present.. It absorbs the free oxygen in the water. This prevents mew Rust from form- ing. And ‘“X” does not allow the lime and magnesia in the water to deposit new Scale. In this way the narrow water passages are kept free from RUST and SCALE. Cooling is greatly improved, Oil is saved. And the motor performs better. Not a Radiator Cement Radiator Cements, flaxseed meals, etc., either in powder or liquid form; which float in the water, will clog the water.pagsages and cause trouble. “X”’ Liquid is not a radiator cement, flaxseed meal, glue gr ‘‘dope.”’ It‘is a combination of chemicals that works scien- tifically. Besafe, Ask for the original ‘“X” Liquid. It is used by the United States Govern- ment, Standard Oil Co., and others whose standards are equally as high, $1.50 75c Leaepe Gee 36.5 6 6 Will do $25.00 in repair work Pema. .-i « 2 * «& At your dealer’s or mailed direct on receipt of price. Write for proof of how one can of “X” Liquid did a $150.00 welding job. ““X’’ LABORATORIES, 25 W. 45th St., NEW YORK CITY PACIFIC COAST BRANCH, 450 Rialto Bldg., SAN FRANCISCO, CAL. 4 99 “TRADE LIQUID makes all water cooling systems LEAKPROOF RUSTPROOF - SCALEPROOF 92 Popular Science Monthly and the bands of silk wound onin 14 -in. wide bands, 4 or 6in. apart from the butt to the tip of the rod, are put on in the same manner. Apple green and scarlet are the most attractive and durable colors. Regular sewing silk in size A is satisfactory. If a finer silk is wanted for finishing the slender tips, simply untwist the A thread and use one or two strands as preferred. After putting on all the guides and windings, coat the bands of silk with white shellac varnish, to prevent the color turning when the rod is var- nished. Do not allow any shellac to touch the wood, however. Aside from four or five natural canes or bamboo poles, which furnish the material, the list of fittings in- clude the following: For Single-Tip Bait-Casting Rod 1 German silver Reel-seat, straight hood, 34 in. diameter 1 German silver Taper, small end about 15-32 in. 1 German silver Butt’Cap, % in. 2 Agate Casting Guides, 14. in. 1 Agate Offset Casting Top For. Two-Piece Bait-Casting Rod Same fittings as given for single- tip casting rods, with the addition of one German silver shouldered and welted ferrule, 17-64 in. in diameter with two closed end centers. ror Three-Piece Fly Rod 1 German silver Fly-rod Reel-seat with attached butt cap, 34 in. 1 German silver Taper, small end 33-64-in. 1 German silver shouldered and welted Ferrule, 9-32 in. 1 German silver shouldered: and welted Ferrule, 11-64 in. with two closed end centers, one for each tip. 1 No. 4 German silver Snake Guide for butt joint. 4 No. 3 German silver Snake Guides for middle joint. 3 No. 2 German silver Snake Guides for tip joint. 2 No. 7 Agate Fly —_— split pat- tern to wind on with silk. Two spools of sewing silk in contrasting colors for each rod. A Useful Threading Tool for a Lathe N easily made internal threading tool can be made from a tool-steel ~~ The V-edged disk has a segment cut out, leav- ing a radial cut- ting edge. The reduced diameter shank may be held in a small V-block in the tool- post. The cut- ting point is sharpened in the same manner as a circular forming tool, by grinding the cutting edge on a radial line with the center. with This useful little tool for turning internal threads can be made from a piece of tool-steel rod

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May, 1920 a — -— nM il: - oo an = Saving the a That Goes Out UTOMOBILEengines are built to consume gas. But the .fuel of today is not readily converted into gas. It 1s too heavy —too much like kerosene. It does not vaporize. Some of it is fed to the engine in the form of raw drops. And these raw drops are wasted. Besides they give rise to carbon and to most of the troubles that mean heavy repair bills. When the gasoline situation be- came critical, the Chalmers engineers decided that engines must burn the fuel of today instead of wasting it. They devised the Hot Spot: engine- with the Ram’s-horn intake manifold. © ’ What is the Hot Spot? What is the Ram’s-horn? In the Chalmers engine the gas- oline, wholly or Saat, vaporized, strikes a Hot Spot ward it enters a cylinder. Instantly the drops are of the Exhaust changed into “gas.” Not raw fuel, but “gas” is fed to the engine—some- thing which will burn. The Ram’s-horn intake manifold makes it easy for this pre-heated, com- pletely vaporized fuel to enter the cyl inders. It is shaped like a ram’s horn in order to get rid of sharp corners. Every gas is composed of billions of particles. Those in vaporized gasoline rush into the engine at the speed of 100 miles an hour. They must not be stopped suddenly -by a corner. The Ram’s-horn makes it easy for them to enter the cylinders. The Hot Spot and Ram’s-horn do this: 1. They make it easy to start. 2. They give you more miles per gal- lon of gasoline. 3. They reducecarbon ~ deposits inthecylinder. 4. They make it impossible for raw, unburnt fuel to drop down into the crank case and “ out” the lubricating oil. CHALMERS MOTOR CAR COMPANY, DETROIT, MICHIGAN CHALMERS MOTOR CO, OF CANADA, LTD., WINDSOR, ONTARIO MAXWELL MOTOR SALES CORP., EXPORT DIVISION, 1808 B;WAY, NEW YORK 3 “an lly ZN ut w, hr) e. «514i \ ya oe i alice Mn cm

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eee An Airplane Kite for a Man to Fly By C. P. Bradley OOD kite-sticks can be made from white pine lath by sawing each lath into three parts. Smooth the sticks with a plane if you have one, because you are liable to split or cut them too thin if you whittle the sticks. If you do not wish to make a kite as large as this you can reduce the dimensions proportionately. Make the plane section first, using sticks of the dimensions given in Fig. 1. Nail 9-10, 10- 12, and 12-9 to- gether to form a triangle, then nail in 12-7. Nail 1-9, 2-3, and 4-10 to- 9 to 3, 10 to 2, 6 to 12, and 8 to 11 (as represented by the dotted lines). Draw the strings as tightly as you can, because the whole thing must be . so well braced that it can be picked up anywhere without losing its shape. Lay this aside and start the tail section by making the two long sticks required by Fig. 2. More strength is required by these sticks than any others in the whole kite, and, while quarter-inch sticks are large enough at all other places, it would be well to use half-inch for these. If you ‘cannot get an 8- gether, and at- tach to the trian- gle at 9 and 10. Nail 11-12 at 12, and nail 5-11 to this at 11. Then nail 5-11 at 5,and put in the brace 6-8. Attach 1-11 and 4-11 at 1, 11, and 4, and you have the framework of the planes. Now go over each joint and tie every one with string. Make it impossible to pull them apart. In places such as 7 and 12 run the string all the way from one to the other several times, because you will have to depend on that to hold the sticks together. A %-in. No. 18 wire nail is as large as you should use, and it only serves to hold the sticks in place. Now brace the whole plane section with string. Run string from 1 to 12, 12 to 4, 10 to 11, 11 to 9, PLAN VIEW Draw the strings as tightly as you can; the whole thing must be braced as tightly as possible 1TO9 AND 47010 15 2A’ 1T02 AND4T03 |S I! 2TO9 AND 37010 IS: 1%! ft. piece, use the method shown in Fig. 3, and join what you have. Bevel the ends, nail together with apiece of thesame size, and wrap string around the whole thing. Where two sticks are to be nailed at about the same spot, stagger them a little, as in Fig. 4. This figure also shows that the end of every stick that does not attach to another should have a nail in the end to which the string may be fast- ened. Nail 21-14 to 16-17. Nail 20-15 to 16-17 at 15. Nail in 22-20, and fit in the braces 18-24 and 19-23. Nail 13-14 at 14. Now tie all the joints together, and brace well, so that the sticks shown in Fig. 3 will keep their shape. To prevent any side motion it is necessary to brace this sideways. To 20-15 attach the sticks 27-28 and 29-30 at 18 and 19 (Fig. 5). Nail 25-26 to 16-17 at 15. Now run all the strings shown by the dotted lines, excepting string 31-15 and 32- 15, which will be attached later. Have them all tight, so that the sticks hold their position. Then run string from 25 to 16 to 26 to 17 to 25, and fast- en well. See that the sticks 25-26 and 16- 17 are held at an exact right angle. This FIG.1 completes the tail section. If you cannot obtain an 8-ft. piece, join them as in Make the plane section first, using sticks of the dimensions given in Fig. 1. Start the tail section by making the two long sticks pictured in Fig. 2 To attach Fig.3. Wheretwosticks the two sec-_ are to be nailed, stagger tions together, them a little (Fig. 4) join them as in Fig. 6. The stick 5-11 of the plane is nailed to the stick 20-22 of the tail, and 11-12 of the plane to 22-21 of the tail. Wrap string around all of these and you are ready to cover it. Paper such as butchers use, or any other kind of tough paper, may be 94 Popular Science Monthly Here is the way it will appear when it is in the air. With a good breeze -the kite will move a 100-pound wagon used. For paste, a thick mixture of flour and water will hold. Lay plane side 1-9-12-11 flat on your paper, and cut all off but a 2-in. margin. Cover the sticks and the entire margin with paste, and rub down tightly. Do the same with the other plane. Now cover 2-9-10-3 with paper in the same way, making sure that the edges at 2-9 and 3-10 are fastened well. Paste 1-in. strips of paper over all strings that lie next to the paper to hold them to it. Now run a string from 31 to 15 and from 15 to 32. Paste the edge of the paper to one string, draw around 21-14, and fold over the other string 25 26TO 25 IS 3° as. 2770 28 IS 2° a eee a * as oe Poe ieee ’ ee. ee e = ete 2 ie -" ~~~ Jig BOL Se SS ars errs (hs aes A 3 ee - | em “a 2 - Pad ES sor 4 oe 28 » ~-+32 26 FIG.5 5 7 5 20 ee JOINING THE TWO SECTIONS i" 22 2 1¢ 4) FIG.6 The s.icks are attached as shown In Fig. 5. W en you have completed Fig. 6 the kite is ready for the string and paper covering to fit. Cut off all but the margin, and paste down. This gives you the hollow tapering section that forms the body. Fasten well at 31-20 and. 20-32. Cover the section 13-16-18- 15-14-24-17 with paper. Now run a string from 18 around 15 and back to 18. Also a short piece from 13 around 15 to 13. Paste paper over the sections 18-25-13-15-18 and over 18-26-13-15-18, and you have the kite complete. The section 18-26-13-25 is the part that lifts the weight of the tail, and the section 13-25-26 that slopes down- LEO

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May, 1920 Contractors are quick to ap- preciate the value of improved equipment. The greater resiliency of the Kelly-Springfield Caterpillar tire, its surefootedness under all con- ditions and its consistent mileage performances have made its econ- omies so evident that leading con- tractors all over the country are adopting it, many using Cater- pillars as exclusive equipment on their trucks. Caterpillars save truck depre- ciation, decrease repair costs, cut down gasoline and oil consump- tion and give amazing traction. They will both increase the efficiency of your trucks and en- able them to operate more eco- nomically. Kelly-Springfield Tire Co. New York, N. Y. ELLY truck TIRES

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kine nae oe nace MA A ney ean eran maanciie emilipttnnten bth fannie on canine dinntetingen CE re a ae Se See Insuring Comfort in Summer Footwear Shoes for outing ,tennis and everyday use LE over the country men are wearing A Keds this season. You will find them in town or at the seashore—on the street or at the tennis court—wherever you go for work or play. Keds are the ideal footwear for warm weather. Their elastic rubber soles put new life in your step. Their soft, pliable fabric makes them always cool and comfortable. Keds now include models made with reg- ular welt soles and firmly boxed toes—just like leather shoes. This means a shoe of style and distinction—the very shoe you have needed to wear with yc ir white flannels or Palm Beach suit. With these additions, Keds are now a complete line of canvas summer shoes—rang- ing from the easy, less formal tennis shoe to the latest and most fashionable styles of footwear. Last year millions of pairs of Keds were worn by men, women and children. Cood dealers everywhere carry Keds. Ask to see the various models—notice how won- derfully light and comfortable they are. Look for the name Keds on the sole. For men and women, $1.50—$6.00 For children I.15— 4.50 Keds v United States + — et So a The standard shoes for tennis, boating and vacation wear. Made of light canvas, in high or low models—while or brown—with black, grey or red rubber soles. ! One of the smart special types for summer wear. Made of the finest white canvas in high or Oxford models, with welt sole construction, which gives it all the style of leather shoes. Sturdy shoes for sport and everyday wear —for boys and grownups—with or without heels. Made of heavy white or brown duck. Brown leather trimmings with ankle patch—red rubber soles and toe cap. Rubber Company Popular Science Monthly ward acts as a sort of brake to prevent the kite from sailing too near over- head. The vertical section of the tail acts as a rudder. To find the place for the bridle, find the place along 21-24 where the kite could be suspended, keeping the stick in a horizontal position, then attach one string there. Take hold of 7-12 and find where you can suspend the kite, keeping 21-24 vertical. Attach the other string here. Now join both strings, and tie together at the point where 21-24 will hang at a 45-degree angle. Attach your flying-string to that. By covering the paper and sticks with linseed-oil paint you will tighten the paper and strengthen the whole kite.. Give the strings a coat of paraffin, because paint makes them too brittle. Use a good grade of string or cord for your bridle and flying-string. . With a favorable breeze, the kite will be able to move a weight of a hun- dred pounds on wheels—for instance, a small wagon. . If the kite should fly to one side or the other, run string from 4 to 25 and from 1 to 26. Tighten or loosen one or the other until you find the place where it flies steadily. To Prevent Dry Grass from Sticking to a Rake OW many times have you raked up dried grass from your lawn with an ordinary wire rake and become dis- gusted with the way the grass stuck to the teeth? Many times, we know. A simple attach- ment, as_ illus- trated, will elim- inate this annoy- ing trouble. Three wooden blades hinged to the teeth of a wire lawn-rake will be found to more than double its efficiency. The blades clamp the material caught by the rake to the teeth. A quick push and shake cleans it.—EDWARD R. SMITH. THREE WOOD BLADES? Cott PERE pt Don’t pull the grass from a rake with your hands. This device will do the trick easily Do You Economize on Your House Rugs? N an effort to economize, some- body recently discovered that the appearance of worn fiber rugs are grestly improved by an application of flat paint. That means a paint such as is generally used on interior walls; it has no gloss. If desired the borders may be stenciled in a different color of the same product. It is said that a rug thus treated will pass muster an additional season or two.

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May, 192v FTER years of research and ex- Ay periment, we have, step by step, accomplished these things in Palmolive Shaving Cream: We have made a soap which multi- plies itself in lather 250-fold. One-half gram—a mere bit—suffices for a shave. A single tube supplies 152 shaves. That’s a unique attainment. It means abun- dant lather from a touch of soap. Once men were quite content with soap hardly one-third so prolific. © Quick action Every hair of the beard has an oil coat. This lather instantly emulsifies that oil. Then the beard—a horny sub- stance—quickly absorbs water. It ab- sorbs 15 per cent of water within one minute after lathering, as proved by laboratory tests. And that makes a wiry beard wax-like. a This achievement alone cost w 18 months of effort. And we tried ov 130 formulas. At our expense Try this shaving soap that multiplies itself 250 times Lasting lather This lather is creamy and tenacious. It maintains its foamy fullness for ten minutes on the face. Thus it doesn’t need replacement. Such durability in lather used to be undreamed of. It means lasting lubrication for the shave. This lather is also a lotion. It con- tains palm and olive oils. So the ten- derest face requires no other applica- tion. *T will amaze you Such statements, we know, sound like fiction to laymen. But every fact here stated has been proved by scientific tests. Your own tests will confirm them. And they mean to you the same in luxurious shaving. We are offering men a Free test tube of Palmolive Shaving Cream, to let them see its action and result. Send us this coupon and we will mail you this Free Tube. Do this for your own sake. See what science has accom- plished for you in this line. Cut out the coupon now. The Palmolive Company, Milwaukee, U. S. A. s # maintains The lather itself is a lotion, containing, palm and olive oils. It soothes all irritation. FRONTS: . FOR A FREE TRIAL TUBE THE .PALMOLIVE ee aes % Milwaukee, U. (Advertising Dept) Please send me a Free Trial Tube of Palmolive Shaving Cream, were eee eee ee eee eee eee eee ee) CORTE EEE HEHEHE HOHE HEHEHE ES COCR EH ee EEE EEE E BEE COOH eee OEE Eee becomes wax-li pfallness for and thus i Within one minu ¢ the besrd absor¥ Be aaa

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went ngndhicmanaenaeeanatid CS ma annem ecnnentenitinei EET eA ti OIG, Note the three conven- ient rolls of United States Abrasives on the lathe. No waste re. Sand Paper is Buy it as you would a tool —instead of just asking for ‘‘some sand paper’’. Buy the U.S. map brand that stays sharp—for every little particle of flint or garnet is a sharp- edged tool, glued everlastingly to strong cloth or tough-fibred paper especially made for the purpose. United States Sand Paper is known everywhere by the map trademark. U.S. flintand garnet (the semi-precious gem) are first choice in the wood working industry where it is used in sheets, endless belts, discs and wasteless rolls of convenient widths. For finishing metal surfaces in foundries and machine shops, discs and belts of Her- culundum and Carbalox from Fast-Cutting Mineral Abrasives On cloth and paper Flint Paper Garnet Paper Garnet Cloth Emery Paper Emery Cloth Crocus Cloth Carbalox Cloth Herculundum Cloth Sheets, Discs, Circles, Belts and Rolls of various widths and lengths of the above U. S. Abrasives. a Tool the electric furnace, are time and labor savers—Herculun- dum for cast iron and similar materials; Carbalox for steel, brass, copper, aluminum, etc. We would welcome an oppor- tunity to discuss this with you. From the crushing of the materials to the last coat of glue, U.S. Sand Paper is sur- rounded with almost unbeliev- able precautions to insure uniformity of quality. You cannot sharpen sand paper: therefore buy the best, the U. S. brand—because it stays with you until the job is done. If your dealer does not have U.S. Abrasives in stock, write direct to us. Our Service Department will recommend the one best grade for your particular work. UNITED STATES SAND PAPER COMPANY, Williamsport, Pa. New York Herculundum and Carbalox discs cement- ed to horizontalor vertical wheels are great time savers in finishing castings and forg- ings to a close fit. The discs last long, both cloth and grit being just right for the work at hand. The table grinder below is omempenainn, Get the complete story on Se Stocks at following Branch Offices: Philadelphia Chicago San Francisco Boston Detroit High speed endless cloth belts of sand ‘paper are necessary in every modern woodworking plant. U. S. sand belts last long. If you have any sanding problems bring them to U.S. We know how to use sand paper as well as how to make it. Popular Science Monthly To Straighten a Bent Rear Axle of an Automobile BENT rear axle-housing seemingly presents a difficult task to the mechanic, but it isn’t as difficult as one would think. The axle to be straightened is first placed in a heavy lathe. A fixture supports the axle on the face-plate at the right of the lathe. The bending pipe is slipped into the axle end, the shoulder of the mechanic at the A machine lathe makes the straighten- ing of an automobile axle an easy job extreme end of the pipe giving the necessary leverage. Obviously, when the axle has been properly trued it will rotate evenly on its axis. The fixture for this work is a heavy casting, which is bolted firmly to the face-plate and which holds the axle end snugly. The different sized axles may be accommodated by using different sized bushings.—R. PRINDLE. A Quick-Action Ice-Cream Freezer HE exceedingly simple form of receiver for freezing ice cream shown in the accompanying illustra- tion has proved by actual use to be a practical and quick means of pro- ducing a very fair quality of ice cream. As may be seen, no crank- turning is necessary. It comprises a cylindrical tin can in the cover of which a circular hole is agente? COMBINED ICE = HOLDER AND : -0f ICE. CREAM CRACKED ICE Reet RECEPTACLE You can make an ice-cream freezer that requires no cranking cut. To the .cover a downwardly projecting tapered ice receptacle is soldered. The freezing surface within and sur- rounding the receptacle is so great that a quick solidifying of the mixture is speedily assured. The tapered form of the _ ice- container permits its free withdrawal from the receiver. May, -

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May, 1920 “A ¥ by likey g oP y hy Lip 4 iP 2 Zh “ iy hi NTHRCUGH . a - Man’s Ancient Enemies, Invisible No More! Then came the Micro- scope, the ‘‘ Discover- er.”’ And science de- tected virulent organ- isms, infinitely small, that attacked the human body. _Invisi- ble, they were also invincible—but once discovered and identified, science: devised safeguards against infection, and commenced its patient cataloguing of these, man’s ancient enemies. Trypanosoma fipone or sleeping sickness rasites erlarged 00 times. Epidemics still occur, for the task is not com- For countless years man lived in ignorance and fear of those dread scourges which devastated armies, made plague-spots of great cities, limited populations, and halted progress. _ pleted. But the day will come when even the most secret of these tiny foes is ‘identified—and mankind will owe that day to the microscope We made our first microscope nearly fifty years ago. It was an advance over earlier models— but it was crude indeed compared with our instru- ments of today, marvels of optical and mechanical precision,’ with perfectly-ground lenses no larger than pin-heads. In this field we have gone far. Perhaps in no other way have we served mankind better than by improving the microscope and aid- ing the crusade against disease. Write for literature on any optical product in which you are interested BAUSCH & LOMB OPTICAL COMPANY . . ROCHESTER, N. ¥Y¥. Makers of Eyeglass and Spectacle Lenses, Photographic Lenses, Microscopes, Balopticons, Binoculars and Engineering and other Optical Instruments see —— 3 that eyes may =— —— —" better ana fa

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URACOR]) TRADE MARK The portable electric cord that wears | ghana sue is strong where other cords are weak— on the outside. It has a covering of thick, heavy, long fibre cotton woven like fire hose, not braided. It is standard for portable electric tools and exten- sion lamps in many of the largest plants in America. Before ordering Duracord, a number of these firms conducted exhaustive tests as to Duracord’s ability to withstand the roughest kind of treatment. The results in every case proved that Duracord will outwear ordin- ary cords many times. Duracord can be furnished in all sizes of portable electric cord and also in the larger sizes of single and duplex cable. Ask your electrical jobber about Dura- cord or let us send you samples of Duracord and ordi- nary cord for you to test and compare yourself, TUBULAR WOVEN FABRIC CO. Pawtucket, R. I. Makers o,° Duracord Flexible Non-Metallic Conduit and tubular woven fabrics of all kinds ak “are “3 4 + \ Thisis Duracord. ? — porous cons covering only with im- Here ts the ordinary bratded cable coveri: Note the open gnd j Uh comes ol stretched - pregnating compound v with ti the @ tiluetrahion removed. of Duracord, 100 Popular Science Monthly An Alarm to Announce the Charged Storage-Battery O avoid waste of current, a simple alarm was made in a battery- charging station to announce a charged battery. Completion of the recharg- ing process is marked by the escape of gas from the cells. SEALUNGWwAX The device consists of a bent glass tube which is inserted in the opening of one of the battery cells, and, upon the formation of the gas a small STORAGE, BATTERY amount of mer- cury in the tube Why ping me is forced up- yf storage-bettery ward, making this alarm and you contact with two are warned when the wires, which charging is complete eloses a dry-cell system with a door-bell connected in. Take a length of glass tubing a foot long, and bend it as shown in the illus- tration. This should be of some small size, say a quarter inch inside measure- ment. The lower end is inserted into a rub- ber cork of the proper size to fit the neck of one of the battery cells. The other end is filled with sealing-wax, after two bare copper wires are placed in it, far enough apart to prevent short- circuiting by contact. A small vent should be made in the sealing-wax with a pin before hardening, to allow the escape of air in the tube when the mercury rises. The wires are then connected into the bell circuit.—DALE VAN Horn. TO BATTERY ( GLASS TUBE RUBBER STOPPER ~~ Filing Saw Teeth with a Spacing Gage FTENTIMES the mechanic finds it desirable to use a saw or a broach that is different in some respects from the standard tools of that nature, and to avoid the tedious job of setting up a milling-ma- chine to cut the teeth on it he files them in by hand, gaging the } pitch with his eye. Unless his a a eye is better a. wh gone 4 can than the aver- easily be made in the age man’s the manner shown here result is bad. To overcome this difficulty and get regularly spaced teeth, the gage shown in the illustration was invented. Any piece of cold-rolled steel will do if it is not too thin, and if the beveled edge is case-hardened it will last a long time.— FRANK HARRIS. May, a| VA\

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L May, 1920 SS contest! SS + OME ELS ANE OEE ALY OE OE METER ECR. Snr Fear a RAEN, a ee eee cailias sep cgmmemmon:s ce eneagna.cecmenntnnim commen epee j M g ‘ NAIA REARS RSS $3000.00 First Prizes for a Thought 103 other prizes from $1000.00 to $10.00 NOTHER Eveready contest! Another chance to win a big cash prize! Another incentive for active-minded men, women, boys and girls—for everybody with imagination! On June 1, Daylo dealers throughout the United States and Canada will dis- play in their windows the new Daylo Contest Picture. It has no title. The story it tells is a great big interesting, intensely human one. A thousand different pecple will see a thousand different stories in the picture. The story the picture tells you may be the most interesting—the prize winner—the story that may be worth $3,000.00 to you. If your answer doesn’t win first it may win the second prize—$1,000.00—or one of the 102 other prizes, none less than $10.00. Go to the store of a Daylo dealer. Study the picture in the window and write, on a contest blank which the dealer will give you, what you think the letter says. Use 12 words or less. For the best answer that conforms to the contest rules, the winner will receive $3,000.00 in cash. Answers will be judged by the editors of LIFE. If two or more contestants submit the identical answer selected by the judges for any prize, the full amount of that prize will be paid to each. Anyone may enter. There is no cost or obligation of any kind. Submit as many answers as youwish. But do not delay. Getanearly look at the picture. your answers. List of Prizes 1 First Prize $3000.00 1 Second Prize... .....$1000.00 3 Prizes of $500.00 each. . $1500.00 4 Prizes of $250.00 each. ... 1000.00 5 Prizes of $200.00 each..... 1000.00 10 Prizes of $100.00 each..... 1000.00 10 Prizes of $50.00 each....... 500.00 20 Prizes of $25.00 each..... 500.00 50 Prizes of $10.00 each..... 500.00 TOR. Peises = 6:5 S569. erated Total $10,000.00 Then send in Contest closes midnight, August Ist. N BATTERIES MAZDA BULBS This Sign on the window identifies Daylo dealers throughout the country who have contest blanks for you'and the new Daylo Contest Picture on display. If you need new batteries for your flashlight, dealers displaying this “the A-3113 can furnish you with the best—th long-lived Tungsten Battery. noes er

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Se ae eee TTT ey AT: FDNY Re A aR cr orca.n aacronww eiraenniaeamesthtiti te it at tanta eentbcasl capacities -<yenecionmet canemep onto eteetenar oe ee i TS: Popular Science Monthly Keep an Eye on Your Automobile A frequent inspection is essential to motor upkeep N automobile is a sensitive mechanical organism that requires considerate treatment. Drivers who are not mechani- cally inclined have neither the sympathy nor the respect for machinery that is necessary for its continued upkeep, and con- sequently it is something they should cultivate. Following are some suggestions that will give you an idea of how the expert works and just why his car is always ready in an emergency. Most owners are neglectful of the body of the car, while paying strict attention to the engine, and thus cause themselves the inconvenience and embarrassment of hearing rattles. The body, while it must have a little attention, does not need much time, and if fenders, spokes, and windshields are watched noises can be avoided. Too little attention is given the spokes of the wheels. After some wear, due very often to friction and shrinkege of wood, the spokes become loose, not only causing unpleasant noises, but doing serious damage to the wheel and tire if not repaired immediately. Loose spokes throw the wheels out of true and the tires soon become ruined. Are you a clutch rider? Does your foot continually rest on the pedal that controls this important part of your ear? If so, you are unconsciously wasting power and are helping to put the clutch in a condition where it will slip permanently. Spend a few min- utes studying your clutch—its makeup and the principles on which it works; learn how to keep it in condition; and likewise learn to keep your foot off the pedal when it is not necessary to keep it there. Aside from a strainer in the tank, many cars have no provision for keep- ing out dirt from the carburetor. Owners of such cars will do well to fit a trap in the fuel line. All of the big carburetor makers offer these traps for sale, and they are placed in the fuel line near the carburetor or in the bot- tom of the tank. The trap catche; all the dirt and water, and shculd be cleaned out regularly once a month. It is very important that regular inspections should. be made of the leather coverings or “boots” which protect the universals and other parts. Flying stones or sticks are apt partly to destroy these boots, permitting the lubricant to leak out and give an en- trance to dust and dirt. Look them over once a month, anyway. Undoubtedly the crudest part of the engine is the fan-belt, and yet it is a most important part. It certainly is a most frequent source of trouble, and by that token demands frequent and steady purr of the exhaust. home to locate it.

Suddenly your engine develops a foreign noise above the careful attention by the car-owner. All fan-belts are provided with an adjustment, some easy, some less so, and these adjustments are necessary. The wise motorist will not forget to give the fan a twist every time he has the hood up. The best results are attained when it is possible to turn the fan with considerable resistance, but not to spin it. Ifa quick twirl of the fan is followed by a little turning after the hand is removed, then the belt is too loose. Do not have it any tighter than necessary, for then it is under Don’t wait until you get Do it now and avoid a breakdown excessive strain, and will stretch, wear, or break the sooner. Do not neglect to change the oil in the crank-case because it is a dirty job. The car manu- facturer knows when it should be changed, and his advice should always be carefully fol- lowed. If you could visit a repair shop and see a few en- gines that have suffered from neglect, you would be more careful of your own. Trouble isoften experienced in getting the tread to stick on small tire repairs. This may be due to any one of several reasons, the most common of which is that the cement has been appliedover wet fabric. The moisture in the fabric, even if very slight, will blow the tread loose. An- other common cause for loose treads is the failure to roughen up the old carcass sufficiently. In this case the cement will not hold properly, and after a few miles of running the repair will sepa- rate. It is also well to make sure that proper pressure is being applied to the repair when it is curing, so that the patch will be thoroughly embedded in the tire. Things You Should Know About Paint-Brushes By John Henry Coon ITH everything else so high in price, it is not surprising to find a good paint or varnish brush costing double what it did a few years ago. It is surprising, though, to find, even among otherwise clever painters, a woeful lack of knowledge in the care of brushes. More brushes are ruined than are ever worn out, in spite of the fact that it is such a simple matter to take proper care of them. Two don’ts, carefully observed, will overcome the greatest mistakes made in taking care of brushes:

this condition. Some painters con- tend that when a brush is well soaked up with paint, water won’t hurt it; but working two brushes side by side, one kept in water and the other prop- erly kept, will soon disprove this contention. If you want your brushes to work well and work longer, sus- pend them in raw linseed oil to a depth of at least half an inch above the bottom of the ferrule if metal bound, or of the strap if leather bound. This will not only keep the bristles springy and elastic, but Don’t keepyour Treat your paint-brushes with consideration will tend to keep brushes in water. and they will repay you with long service Don’t let them stand on their bristle end in whatever liquid you keep them. Bristles have a little tube or capil- lary for a great part of their length, and quickly saturate themselves with water when put into it. A water-soaked brush.is flabby and lifeless, and you cannot “rub paint in’ with a brush in 102 your brushes clean and prevent their getting “lousy” at the heel. The oil will loosen the paint pigments from the brushes, which will be carried to the bottom. The oil must come above the bottom of the band or strap, how- ever; otherwise the brush, by con- stantly drying at the heel, will lose one advantage of proper suspension.

May

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May, 1920 As sure as you { areafoot high — ; you will like this Camel Turkish and Domestic blend! OU will prefer Camels’ smooth, de- lightful blend of choice Turkish and choice Domestic tobaccos to either kind smoked straight! It gives you an en- tirely new idea of cigarette enjoyment. Camels never tire your taste no matter how liberally you smoke. They are al- ways appetizing—and satisfying, because they have a desirable, mellow body. Camels leave no unpleasant cigaretty aftertaste nor unpleasant cigaretty odor. In fact, every angle you get un Camels is so different from any other cigarette that you will be won as you were never won before! That’s why we say frankly —compare Camels with any cigarette in the world at any price! We know the answer. Camels are sold everywhere in scientifically sealed packages ot 20 cigarettes for 20 cents; or ten packages (200 cigarettes) in a glassine-paper- covered carton. We strongly recommend this carton for the home or office sup- ply or when you travel. R. J. Reynolds Tobacco Co. Winston-Salem, N. C.

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mreaenghenarencepeecisenetaect

Sharpen It Up Yourself! In 5 Minutes For 5 Cents No need of sending your mower away every so often and paying $1 and $2 to have the blades filed. ean of Clover Lawn Mower Sharpening Compound will make any mower cut like new all season long. Enough in the can to sharpen one mower 10 times or 10 mowers once. A 50c.

No Experience Necessary No Need to Take Mower Apart Satisfaction Absolutely Guaranteed Read the directions and see how eas ly it’s done. No removing blades. Apply : Clover—push mower—and both the ro- ag — pig er tating and base blades are sharpened to- with each rotary blade jor gether as easy as mowing a small patch entire length. Don’t set of Jawn. too tightly together. The Clover way is the only proper method of sharpening a du!l mower. It is economical—saves time and trouble— makes grass cutting a joy all summer long. Clover also sharpens power mowers, horse clippers, hedge shears, feed cutters, lawn shears, edgers and yrun‘ng shears. Ask your hardware dealer for Clover Lawn Mower Sharpen’‘ng Compound—if he cannot supply you, send us h's name and money order for 50c. and we will mail you, postpaid, a full szed can of Clover—enovgh for a season’s use— de- 2. Apply Clover Com- livery guaranteed. pound entire length of each rotary blade with Full instructions with each can. finger lip. ‘

3. Push the mower for- ward and back rapidly on level surface a dozen times, spinning the blades, and grinding them together sharp.

Wipe off compound; 4. blades should «+? news- paper like skarp shears; if not, proceed again as abcve until they do.

BOYS: Last year boys earned $3 to $5 per week sharpening mowers after school. Join Mike Clover’s Klean Kut Klub for boys. member who earns $5 or more sharpening mowers, receives a hand- Send a postal for interesting details. some 3-bladed jack-knife. Clover Mfg. Company 201 MAIN STREET NORWALK, CONN. my address. CHICAGO BRANCH: 607 West Adams Street SAN FRANCISCO BRANCH: 557 Howard Street Makers of the Famous Clover Leaf Valve Grinding Compound Print Your Name MAIL THE COUPON Print Dealer’s Addiess CLOVER MFG. COMPANY, 201 Main St., Norwalk, Conn. Enclosed find 50c. money order for which send me one full-sized can of Clover Lawn Mower Sharpening Compound, delivery guaranteed to Persie PORNO SMEG G, os bones bon) 00 0s0<eyeck etn s Cee eee HH SEH HH SHOE HEHE OHS Pit ae MIR ss oie sds oes aNonee Gheweosenen Every

Popular Science Monthly How to Make a Cheap but Excellent Copy-Holder HE typewriter has come into such extensive use by all classes of people that an added interest attaches to any device which allows the typist to turn out more work with less ex- pense and fatigue. In copying, the typist usually lays the copy down ona table alungside of the machine, glanc- ing down, from time to time, at the text. This results in a slowing down of the work, since the operator’s eyes are taken from, the printing point of the machine to the text upon the table. The manu- script is harder to read in a horizontal than in a_ vertical position. By using the sim- ple little in- strument de- vised by the : sisciieaalli. writer, the TmcynAdeready fe printing point necessary for making it and text are close together, so that the eyes need be moved only a short distance. The materials are few and cheap; they consist of one 9-by-12-in. photo- graphic card mount; a box of uphol- sterer’s tacks 14 in. long; one paper clip; one yard-stick, a piece of wood 12 in. long, 5 in. wide, and 4 in. thick; one angle-iron brace having legs 15% in. long, 4 in.-wide, and 1% in. thick; one dozen \4-in. flat-head wood screws; a can of paint and a brush. The angle-iron, screws, paint and brush, and the clip may be bought very cheaply. Cut the yard-stick or a piece of wood of similar thickness and width to 18 in., and tack it length- wise in the center and parallel to the long side of the card, allowing the latter to project one inch above the end of the stick. Screw the leg of the angle-iron to one end of the yard- stick; the other leg is to be fastened in the center of the 12-in. piece. Make sure that no mecixanism on the under side of the typewriter touches the board. If it does, cut a slot in the wood to allow the part to work freely. After the instrument is constructed, paint it all over, as otherwise the card will absorb moisture from the air and bend. If desired, the base-board could be made out of thicker wood, such as 3-in. instead of 14-in. material. In this case, it is not necessary to have the rear legs of the typewriter rest upon the board, but the appliance may be placed behind the machine, leav- ing sufficient space for the paper to clear it. The length of 18 in. for the card- holding stick is made to take paper 81% by 18% in. in size. For shorter paper, the stick may be made 15 in. long.—W. S. STANDIFORD.

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CYCLE TRADES OF AMERICA, Inc., 35 Warren Street NATIONAL BICYCLE WEEK May Ist. to 8 th: Have you ever thought—what a bicycle can mean to you? Ride a bicycle to work—save money— time—temper. Avoid hot crowded cars —no waiting on uncertain schedules—al- ways ready to go—costs practically noth- ing to run. Ride a bicycle to the club, for pleasure; fishing trips; to play tennis; golf—Your doctor will tell you it is one of the most healthful forms of exercise. ‘A bicycle is the goal of childish delights. It is the best of all presents. Women find cycling the best way to keep happy, strong, and healthy. Now’s the time to go to your dealer and talk it over. He has a new stock and will be glad to show you the latest models. May Ist to May 8th is National Bicycle Week. Buy now and get the benefit of a full season’s use. New York, U.S. A.

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2 tee tae ree Dest ya — ru na par ASP ay 2a tL tea S onc mind A. ffir carte deb si cor cua at iach Testing a One- Ton Yale Spur- Geared Chain Block Safety is Certified in Every Yale Chain Block ACH Yale Chain block must lift a test load 50% over its rated capacity before it can leave the LJ factory. That means certified safety, safety that warrants confidence in the Yale Chain Block as the safest block for every hoisting need. For complete information re- garding the Yale Spur-Geared Block, Yale Screw-Geared Block, Yale Differential Chain Block, and Electric Hoists, ask for our new 19D catalog. For a Factory locking system use the Yale Masterkey System Write for particulars The Yale & Towne Mfg. Co. Makers of the Yale Locks Works and General Offices Stamford, Conn. New York Office: Chicago Office: 9 East 40th Street 77 East Lake Street Canadian Yale & Towne Ltd., St. Catharines, Ont. Putting speed, power and safety in handling parts to and from machines with the Yale Spur-Geared Chain 3lock Popular Science Monthly This Contest Still Open $5,000 Scholarship Fund, to be awarded by a committee of three distinguished educators ie ten scholarships of $500 each that are to be awarded to high school students this spring by the POPULAR SCIENCE MONTHLY are under the control of a committee of educators of national reputa- tion. The PopyLar SCIENCE MonrTHLY takes pleasure in announcing that the committee will consist of: Professor JOHN F. WoopHUuLL, Professor of Physics, Teachers College, Columbia University. Professor ALFRED E. BurToN, Dean, Massachusetts Institute of Technology. Dr. C. R. Mann, Chairman Advisory Educational Committee, U. S. Army. As announced in previous issues, the PoPULAR SCIENCE MONTHLY will award to high school students, at the close of the present school year, ten scholarships of $500 each. The winners may select any college or technical school in the United States that they may wish to attend. The purpose of the Scholarship Contest is to arouse interest among students in the practical application of their school work to the new mechanical and scientific improvements, inventions, and discoveries. The Scholarship Committee believes, with the POPULAR SCIENCE MonrTHLY, that we are entering upon a period of marvelous de- velopments in which scientific discovery and invention will play an important part. Examination Based on the May Issue The Scholarship Committee, because of the widespread interest in this contest, has decided to simplify the rules. The modified conditions are as follows: 1. The scholarships will be awarded as a result of a competitive examination based on the new applications of science that are found in the May issue of the PopuLAR SCIENCE MONTHLY. 2. The contest is open to any high school student. 3. The examination will be held in the candidate’s own school on June 2, 1920. 4. Any school that has pupils who wish to compete should make application for the question papers on or before May 15. Any student who has made _ himself familiar with the new inventions de- scribed in this issue is well equipped to try for the $500 prize. The PopuLAR SCIENCE MONTHLY sup- plies teachers, for their use in class-room work, with Teachers’ Service Sheets, which classify all the important new ap- plications of science in each issue of this magazine. The Teachers’ Service Sheets are supplied free of charge to any school that uses the POPULAR SCIENCE MONTHLY in connection with the work of the science classes. Service Sheets classifying all the im- portant subjects in the May issue have been prepared, and will be sent to any teacher upon application. To prepare for the,examination get your teaeher to write us for a copy of the May Service Sheets and to enroll your name for the examination. Each student who takes the examina- tion will be competing only with students who live in the same part of 106 the country. One $500 scholarship will be awarded to the student passing the best examination in each of the follow- ing groups of States: NEW ENGLAND Group: Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, Connecticut. New York Group: New York City and State. NEW JERSEY AND PENNSYLVANIA Group: New Jersey and Pennsylvania. Mip-ATLANntic Group: Delaware, Maryland, Virginia, West Virginia, Kentucky, Tennessee. SoutH ATLANTIC Group: North Carolina, South Carolina, Georgia, Alabama, Florida, Porto Rico. GreEAT LAKEs GrouP: Ohio, Indiana, Michigan. CENTRAL Group: Illinois, Wisconsin, Minnesota. PRAIRIE Group: Iowa, Missouri, Kansas, Nebraska, South Dakota, North Dakota. SoutH CENTRAL Group: Arkansas, Mississippi, Louisiana, Oklahoma, Texas. WESTERN Group: Wyoming, Mon- tana, Colorado, New Mexico, Idaho, Utah, Arizona, Washington, - Oregon, Nevada, California, Hawaiian Islands. SCHOLARSHIP COMMITTEE POPULAR SCIENCE MONTHLY 225 West 39th Street, New York

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In the INDIAN Scout, the connect- ing rods, driving shaft, pinion shaft, and intermediate gear of transmission are borne on roller bearings. Clutch and three speed main shaft are carried by large sized annular ball bearings. Front and rear hub are equipped with cup and cone type ball bearings of large size. Whatever the type, only the high- est test bearings go into the INDIAN machine. INDIAN Scout Model G20 Mechanical friction reduced to an absolute minimum The motorcycle world finds its fondest dreams realized in the INDIAN Scout. A sum of the reasons “how and why” would fill a book, but very prominent among them stands the almost unbelievable friction reduction achieved by the Scout con- struction. The finest ball and roller bearings ob- tainable guard the working parts of the INDIAN Scout against friction-wear and power-waste. Unusual advantages to the INDIAN rider result from this scientific, mechanical nimbleness. In addition to a wealth of riding ease, these friction-reducers give increased mileage per gallon of fuel and long service-life to every working part. Department 38 HENDEE MANUFACTURING COMPANY Springfield, Mass. The Largest Motorcycle Manufacturer in the World MUAH m ? ty “Pe 7 ae 7 ‘ 4 we * \ + Bf y me > 7 € : ’ a ‘ ¥ ’ &

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sk, PP en oa ee patie

of . can st bgp cama —

oe | OrTrvow 1 Braking surface 6 3-10 sq. in.—much larger than other brakes. yi ‘Drum’ expansion forced equally by two wedges at each end, insuring even braking distribution over entire inner hub surface, 3 Bronze brakeshoes being softer than hard steelinner surface, grip smooth- ly, firmly ,surely. 4 For forward pedaling, the Morrow responds instantly and positively. 5 More ball-bearingsthanother brakes, so coasts more casily. 6 The Morrow is strong and sturdy; it will stand hard wear. 7 Ninety-fiveinspections,followed bya final test ,guarantecing perfect service,

**Ride a Bicycle’ SI ECLIPSE MACHINE COMPANY ELMIRA,

Side-Swing Eliminated This simple illustration shows a splendid reason why your bicycle should have a STURDY, SURE COASTER BRAKE Imagine three boys holding hands and run- ning. Suppose the boy at one end should stop and the one at the other kept running. The boy between would get a mighty sharp jerk sideways, wouldn’t he?

This is exactly what happens in a coaster brake if the braking power is unevenly dis- tributed. When you attempt to stop with such a brakeone end of the hub is controlled and checked, but the other end tends to keep going. From this, twists ‘side-swings’ (which lead to loosened spokes) result. Uneven twists and ‘‘side-swings’” have been complete- ly eliminated inthe MORKOW Coaster Brake. An expanding ‘‘drum’” of spring steel extends practically the full length of the MORROW hub. When you back pedal, four wedges, two acting from each end, are driven into the ‘‘drum’’and expand it equally and even- ly, thereby distributing the braking power over the entire inner surface of the hub, NEW YORK

Demand the MORROW on the next oe ehawite you Buy

GEORGE FROST COMPANY MAKERS BOSTON

GRAFI -KODAKS to new. ve money. Write now ck if not satisfied. You take no CENTRAL CAMERA CO. SAVE 25% to 60% Cone and Lenses of every Geostiption. Equal chances dealing withus. We have been inthe photo- graphic business over 16 years. Write now. <é Cc Dept.65, 124 Wabash Ave., CHICAGO

leather. come. rime or Full Tim Work Sp Any man or woman, or old, can make awd money this po Mn handling this ‘new ine of Guaranteed Shoes. No capital re a yen territory to handle this guaranteed line.

108 AGENTS: $50 a Week: Brand New Guaranteed Shoe Proposition for men, women and children. Must wear and give satisfaction or replaced free. All styles. Cheaper and better than Flexible steel arch shank. A prospect inevery home. Often take orders for 3 or 4 pairs in one family. Repeat orders will make you a steady in- Write for Agency. Be first in your Thomas Shoe Co., 447 Long St, Dayton, Ohio

Popular Science Monthly The Utility of the Hand- Power Grinder ESIDES fTunning a regular grind- ing wheel for sharpening tools, a small hand-power bench grinder may be adapted to a large variety of other uses in the home or small shop, espe- cially when no latheis at hand. By removing the grinding wheel, different

The small hand-power bench grinder may be adapted to a variety of other uses, such as attaching to a small dynamo or a light machine sizes of pulleys may be clamped on the spindle in its place. In the illustration, at A, B, and C are shown a grooved two-step wooden pulley, a crowned face pulley for a flat leather belt, and a single grooved pulley with a wood packing disk. Such pulleys can be turned to shape by first cutting a hardwood block to a roughly octagonal form, boring to fit the grinder boss, clamping to the spindle, and then rigging up a work- rest something like that shown at D, which is clamped or bolted to the bench alongside of the grinder and is used the same as the work-rest of a lathe. To make the device still further resemble a foot-lathe, a light wooden treadle, E, can be rigged up as shown. It is hinged to the floor and connected to the crank handle by a leather strap. Only a light foot pressure should be applied, however, or the handle will be bent or broken. A pulley fitted in place of the grind- ing wheel will serve to drive light machinery requiring only an _ inter- mittent application of power. Some- times it is desired to drive a light- power grinding stand, as at F, in order to obtain an increased speed or to obtain the benefit of special buffing or other equipment furnished by the power grinder. Another application is the driving of a small dynamo, as at G. At H is a coupling-turned up from a piece of cold-rolled steel, tapped at

pore coerennanneeriant ; a

one tur to dri the chi thi

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May, 1920 one end to fit the grinder spindle, and turned down and threaded at the other to take a chuck from a hand or breast drill. A small flange is shown at J and J, also drilled and tapped to screw on the spindle. A 2- or 3-in. universal chuck is fitted to the flange, and either this or the drill-chuck will hold drills or small pieces for polishing or filing. A wooden or metal rod with a piece of abrasive cloth glued around it, K, is a useful device when held in the chuck. Another important use is to hold a magnet core or spool for the coil winding, LZ. J shows a disk grinder—a brass or iron or even a hardwood disk screwed to the flange and a disk of abrasive cloth glued to its face. This will prove to be a very useful piece of equipment. A second disk could also be constructel and sandpaper glued to it for finish- ing small patterns and other wood- work.—H. H. PARKER. An Underground Irrigation System for the Garden F the garden plot is not large and one has access to an old tin can pile, no fears need result from continued dry spells, according to the plan of an ingenious farmer. He amassed a lot of half-gallon and gallon cans from such a pile, perforated them with No need to worry about dry spells if your garden is equipped with old tin cans punched full of holes small nail-holes, plied the hoe, and sank each can to the level of the ground between rows of garden stuff. When the cans were filled with water, the moisture reached the roots of the plants by a direct, businesslike route. A gallon of water, this thought- ful person found, went three times as far, when administered in this fashion, as when poured on in the usual way. Figuring out the profits, it was found that each minute thus spent was worth three ears of corn, half a head of cabbage, eleven radishes, and two turnips.—DALE VAN Horn. 6,000 More People Every Day Start Saving Teeth in This Way All Statements Approved by High Dental Authorities There is a new, scientific tooth paste used on millions of teeth today. You see them everywhere—glistening teeth, conspicuous for their beauty. Leading dentists all over America are urging its daily use. Over 6,000 people daily, on the average, write us for a trial tube. Soon or late all careful people are bound to join these users. But this is to urge you to learn at once what this new method means. To End the Film The purpose is to end the film—that viscous film which coats the teeth and causes most tooth troubles. You can feel this film. It clings to teeth, enters crevices and stays. The ordinary tooth paste does not dissolve it. The tooth brush does not end it. So month after month it remains there, causing stain and tartar and decay. Film is what discolors—not the teeth. It is the basis of tartar. It holds food substance which ferments and forms acid. It holds the acid in contact with the teeth to cause decay. Millions of germs breed in it. They, with tartar, are the chief cause of pyorrhea. All these troubles are constantly increasing, despite the wide use of the tooth brush. And film is the major reason. Dental science, after years of searching, has found a way to combat film. Able authorities have proved its efficiency by countless careful tests. It is now embodied in a dentifrice called Pepsodent—a tooth paste which meets every dental requirement. And a 10-Day Tube is being offered to let everyone see what it does. Watch Your Teeth Whiten Get this free tube and let your mirror show you Pepsodent effects. Pepsodent is based on pepsin, the digestant of albumin. The film is al- buminous matter. The object of Pep- sodent is to dissolve it, then to day by day combat it. A new discovery has made pepsin possible. Pepsin must be activated, and the usual agent is an acid harmful to the teeth. But science has now found a harmless activating method. And now Pepsadent REG.U.S. The New-Day Dentifrice The scientific film combatant, now advised by leading dentists everywhere and supplied by druggists in large tubes. this efficient film combatant can be every day applied. Send the coupon for a 10-Day Tube. © Note how clean the teeth feel after using. Mark the absence of the viscous film. See how the teeth whiten as fixed film disappears. Compare this new-day method with the old. Then let the clear results decide what is best for you and yours. Cut out the coupon now. 10-Day Tube Free — THE PEPSODENT COMPANY, Dept. 363, 1104 S. Wabash Ave., : Chicago, IIL Mail 10-Day Tube of Pepsodent to Only one tube to a family 109

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ramen n Ce eee ee aia ea Speen - be eat Sa ee SOF ge ee PEE eee Oe a ee aed NI Meet sh Pa a KM ya aes <a asenammenene ne ee pene ee ee ee ieenererenerenaeeies

curacy and Iver Johnson footer Sy 8 . Tver Johnson Single and Double cle, $55.00. Other Barrel Sho combine ac- Models, qependability, JOHNSON REVOLVER Prepared to © , Meet Prowlers?P | “*I wasreturning home late one night and f ortunate- ly had an Iver Johnson revolver in my hip pocket. “Reaching home, I discovered a pair of prowlers attempting to slip out the back way. I gave chase through an alley for two blocks, overhauling one of them, and from that one I learned the name of the other one, whom I interviewed the fo! owing day. “Had I not been armed, I would not have gone up against them.”—C. A. HUTSINPILLAR, IRON- TON, OHIO. * * * The Iver Johnson is always dependable. And it can’t go off by accident. Drop it, thump it, or “Hammer the Hammer.” Drawn-tempered piano- wire springs throughout make the Iver Johnson alert, ready for use on an instant’s notice. Choice of three grips: Regular, Perfect Rubber,. Western Walnut. Three Booklets, One or All Free on Request: “A”—Arms “B’—Bicycles ‘“C’’—Motorcycles If your dealer hasn’t in stock the particular model you want, send us his name and address. We will supply you through him. Iver Johnson’s Arms & Cycle Works 343 River Street, Fitchburg, Mass. 99ChambersSt., New York 7217 Market St., San Francisco $37.50 to $65.00. No extra charge for Coaster Brake.

Skinderviken Transmitter Button

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The most efficient little transmitter in the world. Over 15,000 Sold in Less Than a Year Use it on your Phonograph, Wireless, long distance telephone, etc. Hundreds of interest- ing experiments. F Make Your Own Detectiphone Send $1.00 for one Button with free descrip- tive booklet and circuit diagrams. Order now from J. SKINDERVIKEN 335 E. Broadway, New York City or 154 W. Randolph St., Chicago, Ill,

Entirely NEW principle— not a moving part — Simple. Has the Pep and Power. U. & J. Carburetor i Doubles Mileage—Guaranteed to start car in zero weather— No Priming. 50;000 delighted users. Now ready for Ford, Dodge, Maxwell and Overland. DEALERS — Service Stations, Salesmen: The “U. & J.’’ sells on demonstration—installed in thirty minutes—some good open territory. We also manufacture the U. &@ J. FORD TIMER, | Will last as long asthe car. PRICE $2.50 U. & J. CARBURETOR CO. Dert.231 ~-507 W. Jackson Bivd.. CHICAGO

110

Popular Science Monthly How to Make an Extension Bench Light NE good use for old pipe and fit- tings is that of making a bench- vise extension bracket light, as shown in the illustration. The construction is simple. ' A bracket shaped as shown is made for holding it to the wall, a pivot stud

Use up old pipe fittings by making an adjustable bench light; it can be pulled to any part of the bench desired being screwed in the one lug, over which the bent end of the pipe sets. The first section of the bracket pipe has a hole drilled at the bend to per- mit the electric cord being inserted inside the pipe. The rest of the ex- tension. bracket is made up of short lengths of pipe and old elbows. On the last elbow the electric-light socket is screwed. Each elbow is pinned at one part to prevent undue looseness and downward movement.—CHARLES H. WILLEY. A Pressure Apparatus for the Gas Blowpipe GAS blowpipe requires air under slight pressure, and a simple and inexpensive way to obtain this pres- sure, and to maintain it steadily, is shown in the accompanying sketch. Arrange a foot-pump—an ordinary tire-pump—to deliver air to a bag made of a section of an old inner tube; about 2 ft.-of the tube will be enough. Close up one end tightly, cementing the rubber and holding the edges firmly together with two strips of NETTING To BLowPipe WIRE + ¢ SECTION OF INNER TUBE

WOODEN STRIPS STRAP-IRON

12 PUMP The old automobile inner tube acting - as an air container for a gas blowpipe

wood clamped with screws, as shown. Connect the air hose from the pump to the tire-valve. For the other end of the air bag, cut a disk of wood large enough so that the PAWS OE

Seer ERR CART TERS Emer tenet

~— a meet et BA AMReraee fh

Page 93

May, 1920 tube will have to be stretched a little to go over it. Cut two rings from the tube, each as wide as the disk is thick. Give the edge of the disk two or three coats of rubber cement, and before the last coat is dry put one of the rubber rings on. Coat the outside of the ring with cement and place the tube over it. Finally, slip the other ring over the outside of the tube and bind it in place with insulated copper wire, such as ordinary bell wire. Put an air-regulating valve in the disk, in which a hole has been drilled of the right size for the valve to screw into tightly; an ordinary gas-burner cock is as good as anything. Run a rubber pipe from this to the blowpipe. It makes a much better job if the bag is enclosed in netting, or even in a cotton envelope, which will allow it to expand to about twice its normal diameter, but will prevent its bursting. If the tube is old and rather deterior- ated, do not allow it to expand to more than one and a half times its original diameter. A foot-power arrangement may be applied if desired; and it is a great convenience, leaving both hands free all the time.—R. PRINDLE. To Prevent Water Running Beneath Window-Sills : NLESS steps are taken to prevent it, rain water often runs back : under cornices or window-sills, and from there down the sides or walls of the building. This may be prevented by grooving the under side of Here is a way to keep water from running down re the sides of your house the sill in the manner shown in the illustration. Try it and you will be rid of this nuisance.—Roy POSTON. Why Mismatched Bolts and Nuts Become Loose N experienced mechanic some- times will furce a nut on to a bolt, even if the threads do not match, and in such cases the nut seldom stays on. The cause of the trouble will be made plain by a reference to the illus- tration on page 112, in which the threads are shown farther apart on the bolt than on the nut member. If the threads touch one another at the second turn from the entrance to the nut, then at the third turn they will be slightly out of contact, and still more so at the next turn. The strain is practically at a single point instead of being evenly distributed along the bolt. As the strain is often very great, the threads are simply stripped off, and a rupture occurs. : That is why a nut does not stay on if it does not match the bolt. The man REAL bicycling days again! The open road—swift, smooth flight—rushing air—tingling pulse—flying heels—glistening wheels! If you’re not young, you'll think you are. A bicycle is the healthiest, cheapest, most convenient and most dependable form of transportation ever devised. Think what it would mean to You'll Think You’re Young We back this Trade-~Mark with our reputation that boy—and to you. In quality, design and workman- ship, Dayton Bicycles have been leaders for 25 years. Ride a bicycle—ride a Dayton. Write today for your dealer’s name and catalog No. 44 show- ing 8 fine, new 1920 Dayton Models for men, women, boys and girls. Cycle Dept.. THE DAVIS SEWING MACHINE CO., Dayton, Ohio ” Ride a Bicycle” were ee ee

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Two Money Making BOOKS Elements of Industrial Chemistry. By ALLEN RoGers. Contents: General Proc- esses; Water, Its Uses and Purification; Fuels; Sulphuric Acid; Nitric Acid; Elements and In- organic Compounds; Ceramic Materials and Products; Pigments; Fertilizers; Illuminating Gas; Coal Tar and Its Distillation Products; The Petroleum Industry; The Destructive Dis- tillation of Wood; Oils, Fats and Waxes; Lubri- cating Oils; Soap, Soap Powder and Glycerine; Essential Oils; Resins, Oleo-Resins, Gum-Resins and Gums; Varnish; Sugar; Starch, Glucose, Dextrin and Gluten; Beer, Wine and Liquor; Textiles; Dyestuffs and Their Applications; The Paper Industry; Explosives; Leather. About 600 pages, illustrations. Price, $3,00, Postpaid. Techno-Chemical Receipt Book. By BRANNT and WARL. This volume gives an accurate and compendious col- lection of approved recipés and processes of practical application in the industries and for general purposes. It is a compact repository of practical and scientific information, containing thousands of recipés and proc- esses covering the latest and most useful discoveries in chemical technology and their practical application in the useful arts and industries. 5% by 4 Inches. Cloth Binding. $ illustrations, Price, $2.50 postpaid BOOK DEPT. POPULAR SCIENCE MONTHLY 225 West 39th Street, New York City 495 Pages. This May Mean $100 TO YOU You are either going up the lad- der of success or you are going down. You can’t sit on the same round month after month. Then it’s up to you to prepare yourself for bigger work and bigger pay. There is no better way to do this than to keep up with all the newest inventions, improvements and dis- coveries in mechanics and science. Popular Science Monthly gives you month by month all the Tatest in- ventions and improvements in auto- mobiles, flying, wireless, tools, and labor savers and in fact all the new- est devices in all kinds of machin- ery. A $3.00 investment may mean $100 or more to you. Others have received suggestions from this mag- azine of practical information worth many times this. The successful man is the man who is prepared when opportunity knocks at his door. Be ready for that bigger job by readin issue “4 Popular Science Monthl ‘ Only $3.00 for a whole year’s a scription. Act now. USE THIS COUPONA~~~~ POPULAR SCIENCE MONTHLY, 225 West 39th Street, New York, I enclose $3.00 (P.O. money order or check), send Popular Science Monthly for one year to, every who is in a hurry and thinks that he saves time by forcing together the first bolt and nut that are at hand is often wrong, and sometimes a breakdown results. Stan- dardizing threads is a subject that has been stud- ied from the points of view When the threads do not match, don’t force of the engi- the nut on the bolt neering socie- ties, of the makers of nuts and bolts, and of the users, with the result that much progress has been made. Here’s a Paint and Varnish Remover PINT bottle or can containing equal parts of benzol and de- natured alcohol is a good thing to have around the house, in the work- shop, and in the garage. Primarily it is a paint and varnish remover. Applied with a clean brush to a painted or varnished surface, and allowed to remain five or ten minutes, it will eat down to the bare wood and give very good results. Nothing can equal this mixture as a remover of spots of all kinds from clothing. It may be used safely on any kind of fabric, including silk and taffeta, without injuring the texture, and it will not leave any mark. It can be used very effectively in the garage because it is unsurpassed for cleaning metal parts that are mud- and oil-crusted, and for remov- ing grease and oil stains from tires. It is also an-excellent carbon re- mover. Simply pour an ounce in each cylinder when the engine is cold, allow it to stand from two to twelve hours, and then start the engine, whereupon the loosened carbon will be blown out of the exhaust in powder form.—J. E. DURST. A. Substitute Handle for the Tool-Kit S a rule, a carpenter straps all his tools into a bundle and, for lack of a suitable han- dle, carries them under his arm. A convenient handle for car- tying a bundle of tools may be provided by strapping the brace to the outside. It gives a good grip, is com- fortable to hold, and it does not add anything to be carried: The heavier. the bundle, the more such an improvised handle will be ap- preciated.—HOWARD GREENE. CBUNDLE OF TOOLS Why carry a bundle of tools under your arm, when the brace makes a very suitable handle ? 112 A Popular Science Monthly Cover Automobile Door Tops for Protection ONSTRUCTION of automobile side doors usually embodies enameled steel top strips, which, be- cause of their constant wear and tear in opening and closing the doors, causes the paint to wear off and the metal to rust. This is not only unsightly, but it is also a means of soiling the hands. To overcome this nuisance, remove the top strips by taking out the LACING ON UNDER SIDE door Save your hands and restore your door top’s appearance by leather strips screws, and cover them with thin strips of imitation leather. The bottom edges of the leather may be brought together by sewing with heavy shoe thread after the leather is placed around the metal strip. The result is a pleasing leather-covered door top. It will wear a long time before it needs recovering. Try out this scheme, not only for the sake of your own comfort, but for the car’s second-hand value. The prospective purchaser will judge the price by your car’s outward appear- ance.—P. P. AVERY. Counting Revolutions by a Simple Method O ascertain the speed in revolu- tions a minute of a revolving shaft, attach a short pencil to the shaft in any convenient way, so that it will turn with the shaft, but will not run true; the sketch shows the idea. Tack a strip of paper to a smooth strip of LOOPS ON STRIP OF PAPER wood. While The pencil revolving the shaft is around the shaft re- turning, hold cords in loops onpaper the paper lightly against the pencil, moving it slowly length- wise. The pencil will make a series of loops on the paper. By counting the loops the number of revolutions can be obtained, and by taking the time required to make the loops the calculation can easily be made. This method will not answer for shafts that turn at very high speed, but for moderate speeds it is very useful.

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“$1,000 Saved!” “Last night I came home with great news! Our savings account had passed the $1,000 mark! “T remember reading one time that your first thousand saved is the most important money you will ever have, for in saving it you have laid-a true foundation for success in life. And I remem- ber how remote and impossible it seemed then to save such a sum of money. “TI was making $15 a week and every penny of it was needed just to keep us going. It went on that way for several years—two or three small increases, but not enough to keep up with the rising cost of living. Then one day I woke up! I found I was not getting ahead simply because I had never learned to do anything in particular. As a result whenever an important promotion was to be made, I was passed by. “I made up my mind right then to invest an four after supper each night in my own future, so I wrote to Scranton and arranged for a course that would give me special training for our business. I can’t understand why I never realized before that this was the thing todo. Why, in a few months I had a whole new vision of my work! The general manager was about the first to note the change. An opening came and he gave me my first real chance— with an increase. A little later another promotion came with enough money so that we could save $25 a month, Then another increase—I could put aside $50 each pay day. And so it went. “Today I am manager of my department—with two increases this year. We have a thousand dollars saved! And this is only the beginning. We are planning now for a home of our own. There will be new comforts for Rose, little enjoyments we have had to |"urrnwartinual aamos deny ourselves up to now. And there is a real future ahead with more money than I used to dare dream that I could make. What wonderful had hours they are—those hours after supper ! 10st mnotna SLEOTRIOAL ENGINEER Electric

INTERNATIONAL CORRESPONDENCE. SCHOOLS SCRANTON “ma it » h Explain, ¥ ou ‘ollening me, owt can gay forthe pest i ing and Railways ADVERTISING For 28 years the International Correspondence Schools have been meets Y Eat, window Timmer helping men and women everywhere to win promotion, to earn more Li A le money, to have happy, prosperous homes, to know the joy of ‘getting | Mochine Shap Prosass Cantooniag ahead in business and in life. Ges Engine Operating Paventencey “HWE . OIVIL ENGINEER KKEEP' More than two million have taken the up road with I. C. S, help. Surveying end Mapping Stenographer and Typiat Over 100,000 are now turning their spare time to profit. Hundreds are STATIONARY ENGINEER TRAFFIC ‘MANAGER poser _ Isn’t it about time for you to find out what the I. C. S. Ship Drafeman Commercial Lew You, too, can have the position you want in the work of your choice, Structural

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I : 1 I | I ! I | | Samaecnee and Builder I ! ; : I i i | you can have the kind of a salary that will make possible money in Sheet Mecal W rath he the bank, a home of your own, the comforts and luxuries you would <jeetii Nistietas irene |} Frenee Vrened like your family to have. No matter what your age, your occupation or mpnomte your means—you can do it! pe All we ask is the chance to prove it—without obligation on your part or Street a penny of cost. That’s fair, isn’t it?’ Then mark and mail this coupon, NAdiy ™ nl Corveapondence send this ie soem, is ae

113

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_ — eee vale, a fr ite Te rarupenenisinpeenpinninsthdit =n a oF , Don’t go on spending that good - money you could be saving |: by riding a Columbia. Don’t go on wasting that good time in delayed trolley schedules you could be sav- ing by riding a Columbia. Don’t go on crowding yourself into stuffy cars when you can build “‘alth and strength and ride wherever you want to ride—in solid comfort —on a Columbia. See the Columbia at your deal- er’s. Get a close-up of its trim design, its light but rugged build, its ease of operation, its equipment de- tail, its enduring finish, its thoroughness of construc- tion. For every member of your family there is a model just right. ‘The prices are as moderate as a strictly high- grade bicycle can be sold for. The 1920 Columbia Catalog pictures and describes all models. Send for it and see your dealer today. WESTFIELD MANUFACTURING CO. Westfield, Mass. 45 Lozier Ave. An Adjustable Drop for the Shot-Gun Stock N experienced wing-shot says that the majority of amateur sports- men fail to score hits in bird-shooting because they use guns having. too much, or more often too little, “‘drop”’ of the stock. In covering the bird as it “gets up’’ they do not run their eye along the barrel, but more often see only the muzzle sight. As a remedy for this fault, an adjustable stock is proposed, which by The gun butt is dropped or raised to fit the long or short neck. The bolt then locks it actual tests has proved that hunters with records of poor shooting have been able to “‘get birds’ as they never did before. The provision of this adjustable stock requires the sawing off of the stock at the juncture of the “grip” and the butt. The saw-cut is made on a true circle of about two inches (or more) radius, as shown in the illustration. A hole for a %-in. pin is drilled at the center of the circular saw-cut to receive a pin which en- gages the eye of a long eye-bolt, and a mortise is cut in the “‘grip’”’ portion of the severed stock, large enough to receive the eye of the eye-bolt (which latter should be of 14-in. round rod). The severed shoulder or butt por- tion of the stock is then bored and counterbored, as shown in the il- lustration, to receive the long eye- bolt, which, by the setting up of the locking nut, as shown, unites and locks the butt portion of the stock to the “grip” end at any desired degree of drop. The eye-bolt pin in the -“grip” is reenforced by a U-shaped metal fitting, as a safeguard against splitting the stock. Why Use a Step-Ladder to Change Light Bulbs? N replacing burnt-out electric-light bulbs it is usually necessary to use a step-ladder. Because a number of electric lights in a large church were hard to reach and necessitated the use of a very long ladder, the changer here described was made. It 114 4 Popular Science Monthly Antiseptic and Germ-proof Cuts, scrapes and all skin injuries should be kept clean while they are healing. With this object use New- Skin promptly when the accident occurs. Scientific tests establish the fact that it has the power of destroying germs of infection. ** Never Neglect a Break in the Skin"’ NEWSKIN COMPANY NEW YORK This man has lost an arm. His loss is not apparen ecause e wears a Carnes Artificial which both looks ed from the living arm. ; Wearers of Carnes Arms dress them- selves, carry baggage, use knife, fork, pencil and pen and do any kind of work, including the operation of intricate machinery. Carnes Artificial Arm Keeps Men on the Payroll highly-trained artisans or mechanics, after oy ° one or both arms, have been enabled by Carnes Arm Co aantinne thee Sage are loss od quali 5 Pappy tead lependents. e Carnes Arm - spicuous at m ‘ortable ‘and its use is quickly learned, Illustrated Book FREE. O25 .Dig,, jiustrated Arm in egal and contains the stories = photographs of free to any interested ‘person. CARNES ARTIFICIAL LIMB CO. scansaeorrn ws: LEARN TO BEAN 6 to,8 weeks pernenal training here will quali you toqaen Es te G2 on bow aa a tram = MAKE $1500 $500MO own garage or ree (neighbors UTOfractor us rei fre lig fri le trod word | nll an wile st a we ~~ hh ~~ At a” tae

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May, 1920 has proved to be such a convenience that others may be glad to know of it. The changer is made of rubber- covered steel wire secured to a ferrule, and any length pole or handle may. be used. It has no moving parts, and is readily self-adjusting for any light from a sixteen-watt to a hundred-watt light. Rubber was found to be the only substance that would offer sufficient friction to grip the bulb firmly and yet leave no mark on the glass. Friction tape was first used; but it soon dried out and left a smear on the bulb, especially if it was warm. The changer requires 5 ft. No. 16 steel wire, 4 ft. small thick-walled rubber hose with an inside diameter the same as the wire, a 7-in. length of steel wire cable of the cable clothes- line variety, and a small ferrule. The kind used came from an old buggy- shaft. : The steel wire was cut into foot lengths and bent into the shape shown. After drilling a hole in the end of the ferrule, one end of the cable was soldered to it. The wires were covered with the tubing, leaving two inches of the ends free. These ELECTRIC GLOBE SOLDER RUBBER TUBING ' Lge CABLE “= WOODEN POLE No step-ladder is necessary in using this electric-light bulb changer; it is made of rubber-covered steel wire were then soldered to the other end of the cable, completing the device. The base of the wire loops was built up with solder to insure against breaking out, and the whole finished off with a file. The wires were then bent into the form shown in the illustration. Any suitable pole may be used for a handle. 12-ft. ceiling, an ordinary broom- handle, cut off, will serve nicely. For halls and buildings that will require a longer handle, a bamboo pole will If the lights are in a 10- or Banked Fires Draw No Interest Eight o’clock at night about the busiest place you can find is an electric light and power plant. Boilers at full pressure, fires alive with energy, lights ablaze! Eight o’clock in the morning it looks more like a country church on Thursday night. Every bit as animated. A difference of only twelve hours—but it’s all the difference between night load and day load. Day load, when the big slump comes, is the great problem of the central station. With fires banked and generators silenced, the entire vast equipment is tied up in a production greatly reduced. How to build up day load, so that the central station’s resources may be utilized most efficiently, and the consumer himself benefit from the lower costs? Not, obviously, by an increase in lighting. The solution lies in a greater daytime use of electric power. Your morning cup of coffee made the electric way, your weekly ironing by electricity, your daily use of vacuum cleaner and portable utility motor are substantial aids in swelling day load. Household appliances that are easy on the housewife and just as easy on the coal pile at the central station. For as the load rises the quantity of fuel needed in generat- ing each additional unit of electricity becomes smaller. The plant operates with greater efficiency as it approaches capacity production. * So when the central station is cam- paigning for irons or grills or washing- machines we can be confident that its interest is not in making a few dollars from the sale. Rather to reluce the disparity between day and night loads, to lower costs and to Published in the devote the savings to a .service pro- interest of Elec- gressively more extensive. estern techie Company Dotted all-over the land in No. a order to be near you are 43 work well, and if the changer is to be used in various places, an old jointed . R " trical - fishing-pole will do, as it can be then — by sony ra used in almost any place. stitution that will be helped by whatever helps the Industry. The steel cable makes it possible to use the changer in ceilings or on walls, as it can be bent to fit over the light, and turned without difficulty. ‘Another important feature of the changer is that after the light has been unscrewed it can be lowered without danger of its falling out, : since the rubber-coated wires grip it i " — — werege aeeagagmn 5 y sentimen securely. particular neighborhood. The branch in The materials for this changer cost about twenty-five cents, excluding the pole, and will be of value to anyone who is required to care for many lights.—DALE VAN Horn. your own city stands ready to bring you personally at your call all the advantages of a localized national service. bes 115

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Neng Poy REALS ait nn a ee ee nenaees Soe casiiemeuadiaaeadltee mane te ne sapere * naturally and form | no habit [| They work naturally and form no habit. naturally and form Send for a Complete Catalogue of MASONIC BOOKS Jewelry and Goods REDDING & CO. Publishers and Manufacturers 200 Fifth Avenue Dept.S New York [EARN ENGINEERING Expert electrical engineers are being paid fabu- lous salaries—thousands needed today. We give you personal and thorough training —practical, technical courses 3 months to'2 years under ex- pert engineers in electricity, steam, gas, armature winding, drafting, etc. Extensive laboratory and shop equipment. Not a trade school. Training is condensed—if your time is limited come to the Finlay Engineering College—only one of its kind in the. West. Day and Bnd sessions—enroll anytime. Write for FREE ca‘ st card will do. FINLAY ENGINEERING. OLLEGE 1902 indiana Ave. Kansas City. Mo. You CanSave $50.00 By recovering your old auto top frame yourself. doh -aeten sod apne at ta e8 and m cars. Any person that can $7. 95 hanes and Post Paid drive @ car can put it i We furnish instructions. d quarters — toge — with rear curtain, fasteners. E -, 7 tacks. All complete Give as peepee year and d model 1 number of your car ana Neg a gone Fae with and quote you exact p! LIBERTY TOP & TIRE CO., Dept. E8, Cincinnati, oO. Build Your Own PHONOGRAPH It's Easy With Our Help A few hours’ interesting work cals, h ideals Ne Forwia motors, tone case material, blue — and d fall instructions, Plays an You can make fine fine profit Building .phonographs .for your Write Today for Our Free Blue Print Offer ents wanted for our y built phonographs Choralcon cos 506 Monger Bldg., Ind. “fF © th: ‘ friends cantell { Piroa decide tobuy it ‘ A Sp Uhich of the _— — = Aes are Sendo it to your home. as ea it leg Get more sport and fun out of shooting than you ever imagined was in it—and iempoove, wor accuracy, too. Its simple: a .22 calib 'MAXIM SILENCER | _ On Your Gun Does the Trick pany SWALLOWS THE REPORT NOISE $6.00. You can attach it yourselt. Bend 6c for book of unique shooting experi- ith Maxim Silence. MAXIM SILENCER CO., 91 Homestead Ave., Hartford, Conn. 116 Popular Science Monthly When You Paint Strips Near the Floor T is abit difficult to keep paint off the floor when painting strips or _ borders along the wall next to the floor. Usually such work is done as carefully as possible, and what gets on il YY i r yen a ~N\\ \\ WY \ : TER Be \ f i 5 /; I) I} HAA PAN A piece of cardboard prevents the OOD ME from daubing the floor and gives a clean job the floor is removed with a rag soaked in kerosene. This, however, results in a poor job, and is not satisfactory. One of the simplest ways to do the job is to cut a strip of paper a few inches wide and lay it on the floor against the wall to be painted. This should be rather stiff. If the edge is cut straight, it will fit against the wall, and the part to be painted may then be covered with ease. No care need be exercised at the bottom, as the brush comes in contact with the paper only. The paper is moved along as the work progresses.— DALE VAN HORN. Making Freak Photographs with an Ordinary Camera LMOST everyone has seen freak photographs made from nega- tives on which the emulsion has run by overheating, or by placing the subject so his image is reflected in a mirror with an uneven surface. The picture of the image will also be distorted. A method that will afford much amusement is to take a copy of a good photograph of the subject so it will be out of perspective. This will not give a too distorted appearance, but will make~the subject look fat or thin, according to the way in which the photograph was inclined in rela- tion to the lens of the copying camera. First, provide a copying-lens at- tachment for your camera. These attachments cost from fifty cents to a dollar, and slip over the lens hood. They will copy the object life-size or smaller. A scale for focusing comes with each lens. Now, suppose you wish to copy the photograph of a plump friend so he will appear thin and haggard. To do this, it is necessary to turn one edge of the photograph nearer the lens of the camera than the other.

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May, 1920 Arrange it upright to a back-board, as shown in Fig. 1. Be sure it is per- pendicular. Then swing one edge out toward the camera until the ground- glass shows an image like that which you wish to reproduce. Of course, the more you swing it edgewise to the lens the thinner the face will appear. On the other hand, do not swing it so far around as to make the near edge too much out of focus or so the light shines on the photograph in a way to reflect and obliterate the picture. If your camera has no ground-glass, set the photograph the distance indi- cated on the scale accompanying the copying, and sight along the top of the lens with the eye. Then set the focus- ing scale on the camera accordingly. : If the subject is a thin person and you wish to make him appear short and fat, simply lay the photograph in an inclined position as indicated in Fig. 2. The more incline, the more the ends of the figure will be brought together in perspective and the il- lusion of fleshiness gained. Then again, the operator may wish to accentuate the thinness or fleshi- f | NK | ) THIS EDGE NEAREST PHOTOGRARH TOP, vIEW CAMERA 7 KJ aa FlG.2 To make your subject look thinner than he is, adopt the position shown in Fig. 1; to make him look short and fat, follow Fig. 2 ness of the subject of the photograph even more than it is. ; A still further distortion can be made by inclining the photograph and at the same time lifting one edge nearer the camera than the other. By taking a little care you will be able to present your friends with pictures of themselves that will be very amusing.—THORTON HALLETT. An Old Hacksaw Blade Makes a Durable Scriber DURABLE scriber can be made out of an old hacksaw blade. Old and broken blades are always and everywhere available. By grinding the end off square and thinning this down to an edge instead of a surface, two scribing points are produced. The hardness of the blades conken. the scriber lasting and the right-angle “‘point’”’ has more backing than a needle point, which adds to its dura- bility. Of course, such a scriber is not used for circles and similar work; but where long lines are to be laid out on metal, or where one piece is marked from another laid on top of it, it will be found very useful. The blade is, of course, moved in line with its thin section.-_-_DONALD A. HAMPSON. SHOES" FREQUENTLY HAD TONQ WHEEL LEATHER AND OTHER WS MATERIALS FROM TOWN IN A BAR? : ROW, A DISTANCE OF ABOUT = ge => gT HOLDS ITS $5.00 $9°° & 310:°° SHOES [+550 if W.L.DOUGLAS NAME AND THE Y7 RETAIL PRICE IS PLAINLY STAM PEDON THE SOLESOF EVERY Y PAIR OF SHOES BEFORETHEY LEAVE ec es EARER AGAINST HIGH PRICES SSS AND UNREASONABLE LY 6 SSS esd SHOES SHAPE” $4.50 W. L. Douglas shoes are sold through 107 of our own stores direct to the wearer at one profit. All middlemen’s and manufac profits are eliminated. W. L. Douglas $9.00 and $10.00 shoes are absolutely the best shoe values for the money in this country. W.L.Douglas name and the retail price stamped on the bottom guarantees the best shoes in style, comfort and service that can be produced for the price. tamping the price on every pair of $ sheen as a protection against high prices and unreasonable profits is only one example of the constant endeavor of W. L. Douglas to protect his custom- ers. W. L. Douglas name on shoes is his pledge that they are-the best in materials, workmanship and style es ; sible to produce at the price. every pair go the results of sixty-seven years experience in making shoes, dating back to the time when W. L. Douglas was a lad of seven, pegging T* quality of W. L. Douglas product is guaranteed by more than 40 years experience in making fine shoes. The smart styles are the leaders in the fashion centers of America. They are made in a well- equipped factory at Brockton, Mass., by the highest paid, skilled shoemakers, under the direction and supervision of ex- - perienced men, all working with an honest determination to make the best shoes for the price that moneycanbuy. The retail prices are the same everywhere. They cost no more in San Francisco than they do in New York. W. L. Douglas shoes are for sale by over 9000 shoe dealers besides our own stores. If your local dealer cannot suppl ou, take no other make. Order direct from the factory. Sen Sor booklet telling how to order shoes by mail, postage free. CAUTION.—Insist upon having W. L. shoes. The name and price is stamped on the sole. If it has been ch or mutilated, BEWARE OF FRAUD. HE hand processes—seven of them—by which every single Spencerian Pen is carefully and separately fashioned, are what { make Spencerian Pens so long lived, so uni- form in quality and so perfect in their writing points. We might add that this same indi- vidual care has made them the standard for sPENCERIAN PEN CO. 349 Broadway, New York over half a century. At all good dealers. SPENCERIAN PERSONAL Steel Pens | Send 10¢ for 10 sa pens, and get free, “What Your H ‘that Sascinating book, and- writing Reveals.” Address:

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Migorgeecn a ge moe oni — ea Does Your Mirror Say“Overwork’? OU cannot escape the grim fact that overwork is under- mining et system, weakening your nerves, upsetting iving you t digestion oward physical breakdown. Now, there is a scientific food-tonic of which Arnold Bennett, the famous novel- ist, says it has had a wonder- ful effect upon his nerves— of which Sir Gilbert Parker says that it gives fresh vigor to the overworked body and mind—of which Colonel Watterson says that without it he believes he could not have regained his vitality —from which scores of other ‘famous people have received new strength, a greater capacity for work, a new joy in life. That food-tonic is Sana- togen. A scientific tonic, a natural tonic, a tonic known and recommended by _ sicians the world over. The one tonic you can trust. It is sold by good drug- gists everywhere, in three sizes, from $1.20 up. Grand Prize International Congress of Medicine London, 1913 Write today for interesting free booklet to THE BAUER CHEMICAL co. 115 W. 18th St., New York City Sanatogen eddorsed by Physicians the World Over REVISE POEMS,COMPOSE MUSIC OF ANY DESCRIP- (TIONSECURE COPYRIGHT AND EMPLOY ORIGINAL METHODS FOR FACILITATING FREE PuBLICA- Make Money — Be an AUCTIONEER Missouri Auction School, the largest Auction School in the world. Four weeks course fits you to make big money. Col. A.W.Cies, Chillicothe, Mo., made $1000 one day;Col. E. Walters,Skedee, Okla., made $1746 one day, If you want $50 to$100 a day write today for free 67-page annual and read the stories of successes e by our graduates. {Simply send name--let us tell you how to bea Suecessful and Prosperous Auctioneer, W. B. ARPENTER, Pres., Missouri Auction School, Dept.L 818 Walnut Street, Kansas City, Mo, Boys, Bulld This Car. This nifty little driven by gasoline motor, om Be built by any boy. Parts are furnished by us building plans and ‘p Sioe Toon ice list o' _ showing bow to build this lad'e car. Violin, Hawaiian Guitar, Ukulel _. Mandolin, Cornet, Tenor Banjo or Banjo eo ° Guitar, lutely free. Very small charge for lessons only. We guarantee suc- cess or no charge. Complete outfit free, Write now. No obligation, SLINGERLAND SCHOOL OF MUSIC, Inc., Dept. 27, CHICAGO, ILL. Popular Science Monthly Photographic Bronze and Plaster Plaques N 1861 M. Willeme was successful in making plaster casts in relief from photographic’ negatives. To carry out this process a series of cameras was required as well as various devices such as pantographs to make the impression in the plaster. This process ~ : SS > \ i A product of the process described in the article: the process jis used for making ad- vertisements, signs, and architectual pieces fell into oblivion, inasmuch as it de- pended too much on the skill of the photograph-sculptor for the best re- sults. Other attempts were made, and these again proved a failure. Eventu- ally the well known swelling property of so-called ‘“‘bichromated gelatine’’ was adopted. The process involved is quite simple, and consists of eight successive steps in the production of a photograph-in bas-relief, either in plaster-of-paris or in copper. These are as follows: 1. Secure a good sharp negative (of a head) in profile. 2. Make a print in the bichromated gelatine. 3. Swell (or develop) this latter plate. 4, Mordant or harden the image. 5. Make a plaster negative or im- pression. _ 6. From this latter secure a -dupli- cate in wax. 7. Coat with graphite. 8. Electroplate with copper. Making the Gelatine Plate Use an enameled iron pot and into it place 21% oz. of Nelson’s soft gel- atine, 10 oz. water (distilled), and 6 drops glycerine. Allow the mass to stand until the gelatine swells and becomes soft. Then heat the pot (preferably in a water bath) until the mass dissolves, taking care, however, that the tem- perature does not exceed 120° F. When the mass is entirely dissolved add 150 gr. of potassium bichromate ,and 75 gr. of ammonium bichromate, stirring thoroughly and keeping the solution at 120° F. Then filter’ it through muslin into a glass graduate

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Seine EPS. 5 May, 1920 that has been heated to 130° F. All this must be done in a dark room, using only a ruby lamp for light. In the meantime a piece of glass about 5 by 7 in. in size and \ in. thick is carefully cleaned and warmed; this plate is coated with the gelatine solution. Great care must be taken that the coating is not put on in streaks and does not run over the edges. The gelatine-coated plate is then placed in a dark room or box and allowed to dry. The temperature of the room must be about 95° F. The best results are obtained with plates coated at the rate of three ounces to each plate. Leave the plates to age for three days. ° Secure a good, sharp photographic negative, preferably one of a head in profile, and expose the gelatine-coated plate through this for about fifteen minutes to direct sunlight or for one hour to ordinary diffused daylight. After. exposure remove the plate from the printing-frame, and place it face up in a dish of clean, cool water. The gelatine will immediately begin to swell. The parts of the gelatine film that have not been acted upon by light will absorb water and swell up. The other parts, which correspond to the transparent portion of the negative and which have been acted upon by light, have become insoluble and will not be affected by the water, so that they remain at their original level. The progress of the swelling can be ascertained both visually and by feeling with the tip of the finger. Should the swelling be allowed to tide Mh i The plaster is poured t) upon the swelled gel- atine print until the space is entirely filled aN ~ ‘ i vi Lid ev Li bu ny) P) i i proceed too far, the edges of the lines will absorb water, and in the finished print the surface will be con- vex. If not swelled sufficiently the relief will be shallow and the lines slightly concave. When it is judged that the relief is sufficient, remove the plate from the dish, and, after washing under the tap, place it in another dish containing a hardening solution made up of 36 oz. water, % oz. chrome alum, and 4 oz. citrie acid. After remaining in this solution from ALLOMO r e cnyineering VOL.I MOTORS ENGINE PARTS CARBURETORS VALVES LUBRICATION Aweek . ” AWeek EARN AT HOME — You don’t have to g0 away to school to become an Auto- mobile: or. Tractor Expert. Learn right at home—in your spare time—at less than one-tenth the cost. There are thousands of big jobs open to men who know something about automobiles and tractors. Ten times the number now engaged in the business are needed. You can fit. yourself to hold one of these fine jobs without . leaving - home—you keep right on with your present work—keep on earning while you learn. Here’s your chance to land one of these — man’s size jobs paying you from $40.00 to $150.00 a week. Auto Books and Tractor Information 15 great experts wrote this fine home study course on Auto and Tractor Engineering just for men like you. They: teach you everything that the best auto schools teach. You can’t learn more about autos and tractors than these books tell you. 6 big volumes packed full of everything the expert knows. 2600 pages of advanced money-making facts. Over 2000 ? pr oor making everything as plain as day. Fifty thous- and men have used these books and have made good. A hundred are making good every day. You can make good too. Here is What You Learn Automobile Motors— Welding—Motor Con- struction—Repairs—Car- buretors and . Settings— Valves—Cooling—Lubri- cation—Fly Wheels— Clutches—Transmission ; —Final Drive—Steering Pa boo Jo Starting — Lighting We will send a set of these Shop Kinks—Garage great Auto and Tractor Books to Electrics—Storage Bat- Jes for a week’s free trial. No Money down. sertee— Cone and Repair _ ext See Sy coupon Laren 4 and — it. o otorcycies—Auto e s will come at once by parcel post Trucks—Gasoline _Trac- or express collect. They will be yours to tors and How to Repair ’ Them. use for one whole week. If you don’t want Blueprints to keep the books, notify us to send for 128 uep’ - them at our expense and you won't owe us of Electric a cent. bs are the ee age aba iri i ams up to you. you do want to keep the Wiring Diagr to fit yourself en a $40.00 to $150.00 a week toad - job just send us $2.80 within seven days and ~ $2.00 each month until $24.80 has been paid. The regular price is $30.00. This special price is offered for a limited time only. In- creasing cost of materials will make it neces- sary to raise the price soon. Mail Coupon This coupon is not an order, It’s only a request for free trial. It gives you a chance to see what you get before you put up a cent. Send the coupon right now—it’s your start on the road to real money-muking. ce coer ee ee ee fee) es) Se em) SE ery rus) Smt es at gh wong AMERICAN TECHNICAL SOCIETY, Dept. A205; CHICAGO. Reference. .......... Please send me a six volume set of Automobile and Tractor information by parcel post or express collect for seven days’ trial and practical use. I will either send you : $2.80 in one week and $2.00 a month until I have paid $24.80 or notify you that I don’t want the books so you can send for them at your own expense. If the books are sent ] back I am not under any obligations and won't owe you anything. . r ° . .J eeoeewrosneer sewer eresr essere er ee ee eee ee vie ® ee elt t te rereesrees eeeeer | a Please give name of local merchant, banker or mail drde# ‘fiduse on last line. a 119

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No Other Typewriter Can Do This: MULTIPLEX HAMMOND'S pega changeable type Many styles, many Languages Two types or languages al ways in the machine change ° Mes ‘ g ~ The § World’s Most Wonderful ee = C2 “Writing Machine Here's a-polyglot machine that writes all lan- ~ guages from Eskimo Indian to Kata Kana Japan- ese and over 365 different type-sets. The type is instantly interchangeable —two different lan- guages or type sets are always on the machine. “Just turn the knob" to change language or type. Hammond *“‘Many Typewriters In One” Sounds like an Arabian Nights story but the machine itself is very practical, very real. It is the typewriter President Wilson uses personally— the typewriter he took with him when he visited King George. Types for all purposes and for all Languages Spacing to sult size of type Perfect alignment Gutomatic Sybe Impression All on one MULTIPLEX The marvelous UST ANESS tuawchongsetie type feature is only one of 16 men and women in all walks a life prefer and yet use the Multiplex. Write today for FREE BOOKLET It will show you how, with the Multiplex you can put the force of emphasis into your typed matter—how you can drive home with strength of accent the fullness of your argu- ment—how you can write with the same convincing force = you use in speaking—an exclusive feature of the Multi- ex Write your name. address and occupation on the margin of this page NOW and mail the margin to HAMMOND TYPEWRITER CO. 639 East 69th St. New York City Also an Aiuminum PORTABLE Model. l1lbs. Full capacity. Ask for special Folder. Factory price direct to you This $12 Officer Shoe Hand sewed. First Grade. $ .89 The factory price direct to you at only The retail price of this shoe is $12.00. It is made of the best waterproof ma- hogany calf leather. G nteed to give the best wear. Send your name and size you wish and we will send you these Army Officer shoes. If these shoes are not just as we say, send them back. You don’t lose a cent. If you are sending money order or check do not include postage. Pay only $6.89 for shoes. We pay post- age. State size. | These shoes are built tobe good for work and dress: at the same time. U.i8: National Army “Shoe Co. (©) 3310 3:8) SHO three to five minutes, remove the plate and wash it thoroughly. Lay the plate on a level slab, and place iron bars )% in. in thickness glass and parallel with them, as shown in Fig. 1. The bars should be well greased with lard or oil to prevent the plaster subsequently used from adhering to them. The Plaster Cast ‘Now prepare the plaster-of-paris (grade. XXX) by pouring a little water into a basin and adding the plaster until it is the consistency of treacle. To this add a handful of powdered alum. It is best to pass the plaster through a fine sieve to remove any large or rough: particles of foreign matter. The mixture should be well worked up with a wooden spoon, or stirred, and this should be done rapidly, or the plaster will set during the operation. “As soon as it is mixed, carefully pour the plaster upon the swelled gelatine print until the space between the bars is completely filled and is rather higher than the bars, care being taken to avoid air bubbles. It should be pressed down with a large shallow spoon or spatula. When the plaster begins to set, scrape the sur- face level with a straight-edge resting on the bars, and when set hard insert the edge of a knife beneath one end to push the glass and cast apart, removing the irons and trimming the edges. It is a matter of experience to determine how long to leave the plaster before lifting it from the gela- tine print. By pressing the finger on the back the time can be judged. When it takes some pressure to make an impression the cast may be consid- ered ready to lift. Thus is produced a negative in plaster, from which a copy is to be made in wax. Copying in wax is done by removing the moisture from the face of the plaster negative with the aid of a cloth or sponge. The plaster negative is then laid flat and the iron bars again laid in the same position as when the plaster-of-paris was molded: Now pour upon this negative to the height of 44 in. 8 oz. beeswax, 32 oz. paraffin, and 6 oz. rosin. When this has con- gealed or hardened separate it with a knife. Now give the wax print, or positive, a surface of fine graphite, and place it in a shallow basin, leaving in it a concentrated solution of copper sulphate. Sprinkle upon the surface of the wax image some fine iron filings. A fine copper film will immediately form on the surface of the graphite. Wash in running water and copper- plate.in the usual manner. It must not be supposed that this process is to become a competitor of the sculptor, but it is really intended to be a valuable aid to him. . It. may be commercially used for making signs, medals, cameos, brooches, and Dept. P.M. 795, Westfield, Mass. 120 architectural pieces—SAMUEL WEIN. about one inch from the edges of the | Popular Science Monthly like box cars—all but Garco Many are the bumps to be avoided along the highways and byways. Garco will free you from the more jarring ones. . . It puts the stopping of your car under complete control. It makes your brakes as responsive to your will as the muscles of your legs and arms. Its untiring strength and energy pro- vide many months of reliable service. Tell your dealer you want Garco. General Asbestos & Rubber Co. Charleston, S. C, NEW YORK CHICAGO - PITTSBURGH Beckgercf100 10 i BURKE JAMES. ~ INCORPORATED STORAGE BATTERIES FOR ANY CAR Starting Lighting Guaranteed Nine to Eighteen Months No False Promises. Performance Counts 6 Volts rebuilt $12 and your old battery or $14.50 cash 12 Volts rebuilt 17 and your old battery or 19.50 cash NEW 6 VOLT GUARANTEED 18 MONTHS $21.00 Economize in comfort with a BANNER BATTERY. Send twenty per cent deposit, balance C.O.S. subject to inspection. BANNER BATTERY CO. 1356 Michigan Ave. Chicago, II. QUICKLY [LANGUAGE LEARNED ON ALL PHONOGRAPHS **Like ieerning a tune—and as easy.’’ Our disc Records repeat the correct accent and a ation until you ers Ay hekeees friends enjoy language study by the LANGUAGE PHONE METHOD and Rosenthal’s Practical Linguistry The war has created unlimited opportunity. Pre- oe now tabet better Fad a ss or increase your _ busin eee yon | studied = at school, Write for Booklet and Free Trial Offer. mr THE LANGUAGE PHONE METHOD 946 Putnam Bidg. 2 W. 4Sth St.. N.Y. ARMATURE AND MAGNET WINDING A necessary’ book for electricians. diagrams, $1.85 postpaid. POPULAR SCIENCE MONTHLY 225 West 89th Street, New Yors Full facts and ~ wap. pe Fs

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May, 1920 A Detector Stand Having a Set Adjustment ANY kinds of detector stands have been devised, but still an- other, one that contains an uncommon © arrangement of the mechanical parts, is here presented. The amateur may find in the instrument several ideas of interest. ‘The illustration shows a stand capa- ble of exact adjustment. It is stable, and, as can be seen, the point can be raised while transmitting and returned to the exact spot of sensitiveness at which it was set prior to raising the Here is a detector stand that is capable of exact adjustment point. In this manner it is an easy proposition to hold the sensitive point after it is once found. The point is made fast to a binding- post which is held in position by the support taken from an old sounder. The silicon is held in place by a strip of brass. The heavier the spring the more stable will be the adjust- ment.—E. T. JONES. Repairing a Gasoline-Logged _ Carburetor Float HERE comes a time when the cork float of many carburetors becomes gasoline-logged and heavy. To remedy this is not quite so easy as it looks unless one understands the trick of removing all the gasoline from the interior of the cork. Per- haps the gasoline has filled the pores of the cork through one small hole. Consequently to drive out the gas through that one hole is the problem. Hanging in the sun will do it in, time, but here is a better method not generally known. Immerse the float in a kettle of boiling water. In a very short time the gasoline will be vaporized and pass out, and the hole can be located by the bubbles coming away from the -cork. Take the water away from the heat so it quiets down, and watch the bubbles of gasoline until they cease. Then remove the float. immediately before water has a chance to enter, and dry out slowly over a gentle heat. When thoroughly dried, give it one or two good coats of shellac, and it will very likely be a long time before’ it will again need attention. Plug up the hole with sealing-wax before shellacking. Use Your Electrical Appli- ances More Conveniently More than. half the pleasure and conve- nience of electrical appliances lies in hav- ing them ready for immediate service. There should be a place in every room where such an instant attachment can be made without fuss or bother of remov- ing light bulb. ‘The does this for you. Provides two connec- tions from a single socket. Gives youlight and either heat or power at the same time, “Every Wired Siome Needs Three or More’’ AT YOUR DEALER’S 34-5350 Folder free on request BENJAMIN ELECTRIC MFG. CO. Chicago New York San Francisco Ask your dealer to equip the cords of your electrical appliances with Benjamin 903 Swivel Attachment Plug. It screws into the socket without twisting the cord. The Benjamin No. 2452 Shade Holder enables you to use any shade with your Two-Way Plug. ee pana CATALOG S15 SAS .Shete' S) AKER or two colors ‘ y fe : High grade Solid gold Pins and Rings. GBASTIAN BROS, CO., 169 Bastian Gldg., Rochester, N, v AN EASY WAY TO MAKE MONEY .2::: on a small sal Be ind dent, Go in thea ti ifn ba business, One man says “I “made $60. © Seas mo’ capital needed. Jobs "sae es onl & motorist = pos: lo - AALER Ti Tire re Repair Outi taprored Wine Wrapped Tread Method m Does as priced sass on te. big bigh can use it. It’s the only HB. 4 that has Automatic Heat Control, and can’t ae or evens a tire. _ FREE Book rar nse ee Soe Don’t delay. Write C. A. SHALER co. 2104 Fourt: St, Waupun, Wisconsin e. 8 of users. In use 10 years, SAVES MONEY -- FIts ANY STOVE Weite for free liter Iteratare— cols ev Gre ~ Vy = Wf Pajamas & Night Shirts Gx if Es ee The NIGH Twear of a Nation"

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Learn Drafting Employers everywhere are looking for skilled draftsmen. They are offering good salaries to start with splendid chance for advancement. Drafting offers exceptional opportu- nities to a young man because drafting itself not only commands goo” pay, but it is the first step toward success in Mechanical or Structural Eugineering - or Architecture. And drafting is just the kind of work a boy likes to do. There is an easy delightful way in which you can learn right at home in spare time. For 28 years the Inter- national Correspondence Schools have been giving boys just the training they need for success in Drafting and more than 200 other subjects. Thousands of boys have stepped into good positions through I. C. S. help, but never were Opportunities so great as now. Let the I. C. S. help you. Choose the work you like best in the coupon, then mark and mail it. This doesn’t obligate you in the least and will bring you information that may start you on a successful career. ‘This is your chance. Don’t let it slip by. Mark and mail this coupon now. = a ee ee oe TEAR OUT FER E ae ame eee eo Se INTERNATIONAL CORRESPONDENCE SCHOOLS 7676, SCRANTON,

BOX P. Exriein. wihost obligatin e, how I can qualify for the in the sub blect hajore which I mark X. eoaanen ENGINEER SALESMANSHIP Electric Lighting ana Kye. ADVERTISING Electric Z Window Trimmer Telegraph Engineer Show Ca Telephone Work Sign Painter MEOH ANIOAL ENGINEER Railroad Trainman Mechanical Draftsman ILLUSTRATING Toolmaker SOstvEse MANAGEMENT A Gas x7 Gperating CIVIL G _—, BOOKKEEPER Surveying and | Stenographer sririounartraiases’ | Hanon stone ‘a A ~ TRA tel eg B fen FFIC MANAGER Ship Draftsman Commercial Law HITECT GOOD EN Oentractor and Ballder < ‘each 4rehitectural Draftsman Common School Subjects Structural Ragineer Ralls » Mall Clerk ail w: PLUMBING AND HEATING AUTOMORILE OPERATING Sheet Metal Worker Auto Re Textile Overseer or Bapt, Navigation OHEMIST AGRIOULTURE Freneh Name. Present o = Street and No. - City.

this to enon” _ International Rey naan: deg Po nae oe

How to Make a Laboratory Rheostat N electrical laboratory is incom- plete without a small rheostat, and after trying out numerous styles and kinds I have yet to find the equal of the following hand-made contri- vance. Into a piece of slate or other good insulating ma- terial drill holes as laid out in Fig. 1. Note that there are eight large holes % and twelve small ° * ones, and that each two of the FIG! small holes oc- Fig.1.Holesarebored cupies approxi- in a piece of slate mately as much or other good insu- y lating material in the Space as one manner shown here large hole. Into both the large and the small holes I fitted round-headed brass machine-screws, having first filed the head down almost flat. I cut the switch arm out of fiber (hard rubber may be used), and fitted two small pieces of flexible brass sheet- ing, insulated from each other by means of a space, to the under side by means of small machine-screws. The left-hand piece is permanently in contact with the center machine- screw that holds the arm in place. Two termi- nal posts are mounted below the rheostat _ and three Edi- son base-lamp receptacles above. The wiring isshown in Fig. 2 and the rheostatic steps are dia- O° ° e995 ° *eoe 6

grammatically outlined in Fig. 2. The wiring lay- Fig. 3 out for the rheostat - is shown in the dia- The resist- gram. Take care in ance of a-— making connections lamp may be considered as constant (it varies only between the limits of hot and cold, according to: the voltage applied). Using the standard 60-watt lamp (the carbon fila- : ment preferred) i} - SHORT CiCuIT in all three re- Jc a ceptacles, and knowing that if = cemameee 110 Gin. ere a3 a applied the lamp would draw a lit- tle more than FIG. 3, half an ampere, Fig. 3. Here are the it is easy to find rheostatic steps. Make the resistance sure that all connec- b b tions are correct before tO be about youturnonthecurrent 220 ohms. 122

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SMusic Lessons “ET TT At Home By — lete Conservatory Rooms i. home ae music cee ns mn at Ameri 7 a pean Eland by Paderewski. h Mast ter teachers guide and coach Lessons a marvel of simplicity and completeness. Any Instrument or Voice Wesameng interested in—Piano Voice, Public School Masie, Violin, Cornet, Mandolins Gi uitar, Banjo, or Reed —and we will send our 'ALOG coverin, instrumental and | courses, d NOW. . NIVERSITY EXTENSION CONSERVATORY 6287 Siewel-Mouce Bldg. Chicago, Illinois. Deafness a ae every pane ofg bd ) ness or defective hearing from causes such as Cai Deaf- ness, pi or Sunken Dru Thic ms, Roaring Hissing Ly Perforated, Wholly _or Partially Destroyea Drums,Discharge from Ears, etc. Wilson | a 2 Ear Drums “Little Wireless Phones for the Ears’’ ire no medicine but effectively replace what is ing or defective in thenatural eardrums, They are simple Caveat, Se which the wearer easily fits into the ears wperet ey aoaeeratte. Soft, safe and comfortable. today for our e FREE NESS, giving you full part noe hy and testimonials. WILSON EAR mauM Co. ted 675 Inter-Southern Bl ‘Louis KY.

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May, 1920 Assuming 220 ohms per lamp the rheostat will give a variation in the following steps: Ist,. no resistance 2d, 73 ohms 3d, 110 ohms 4th, 220 ohms 5th, 330 ohms 6th, 440 ohms 7th, 660 ohms ) If now there should be substituted an old so-called 32 C. P. carbon lamp (which on 110 volts draws very nearly one ampere, determining the resistance to be approximately 110 ohms) for one of the 60-watt lamps, the rheostatic steps would be in accordance with the following tabulation, determining in which receptacle the 110-ohm lamp was placed: With the 110= Recepta- tacle Receptacle nthe 10= Rasentar —_Reoegt pt 1st step Noresist- Noresist- - No resist- ° : ance ance ance 2d step 55 ohms 55 ohms 55 ohms 3d step 73 ohms 73 ohms 110 ohms 4th step 2200hms 220o0hms _ 110 ohms 5th step 23ohms 293ohms 220 ohms 6th step 33800hms 440o0hms 330 ohms 7th step 5500hms 550o0hms 4550 ohms It is a simple matter to procure lamps of other sizes and resistance, and the foregoing example simply illustrates how the steps of the rheostat may be varied. Should you desire to obtain the ohmic graduations of the rheostat when substituting one or more dif- ferent.resistances, the following parallel and series combination formulas will be found of value, the letters X, Y, and Z being the resistance in ohms of the lamps in the respective recep- tacles: Ist step—No merenat: i. e., short circuit 2d step— of Y +> Z N conductance or = XYZ t xe = res'stance 1 1 N . > 3d step— Y ao z= YZ conductance or = = resistance 4th step—X = resistance 5th step— + + z = a conductance or a X = res stance 6th step— X + Z = resistance 7th step— X + Y + Z = resistance THERON P. FOOTE. Paint Milk-Cans to Prevent Them from Rusting T is a common practice to paint milk-cans, but as a-rule the dairy- man’s only thought in doing it is to enable him to pick out his cans more readily from among others when they are put out on station platforms. By selecting the right kind of paint —antoxide, it is called by the paint trade—the can, besides being made distinguishable by its color, is also made rust-proof. This rust inhibitive paint should be applied at least to the bottom of the can, as the protective plating of tin is soon worn off there, and the unprotected iron then be- comes a quick and easy prey for rust.’ The paint greatly lengthens the life of the can; and new ones, and even patches, cost money these days. SMOOTH! \YES!AND ITS GUARANTEED TO KEEP MY FACE SMOOTH FOR LIFE™ Written Guarantee with Each Razor ’ SHUMATE RAZORS are s80-good that we guarantee them for life. Here’s the reason: The ; blade is made from tungsten alloy steel, which takes a keener edge than any other steel can -- and holds it. You can use a SHUMATE for years without honing. The secret of this wonderful steel is ours alone, and we guard it jealously, Buy a SHUMATE RAZOR and use it, not only a few times, but as long as you like. If you decide after an exacting trial, that you don’t like it, we'll exchange it for a new one without a word. Ever recline in a barber’s chair and almost go to sleep as you experienced that delightful, soothing sensation when his razor swept your face clean? And have you said to yourself “I wish I had a razor that would perform like that"? A SHUMATE will do it and -- keep on doing it. $ Send us $2.00 and the SHUMATE Barber razor will be sent to you e postpaid. If your- beard is extra wiry, we recommend our $3.00 SHUMATE RAZOR, specially ground for this purpose. In remitting, give us your dealer's name, and a chamois lined, rust-proof case will be included with your razor. SHUMATE RAZOR COMPANY, 826 CHESTNUT ST. ST. LOUIS, U.S. A. Established 1884 Capacity 10,000 Razors Daily “DON’T SHOUT” “T hear you. Ican hear now as wellasanybody. ‘How?’ an THE MORLEY ONE. I’vea pairin ae ears now, but they are invisible. I would not know I had themin, myself, only - that I hear all right. The Morley Phone for the . ~ =~ ALY Vip Sees CP, C2 fage, Sidings, 0 ape — pa you is to the ears what Edwards “Reo” Meta Shingles ' fnvit isible, wg A. B.S | : a cost less; outlast three ordinary roofs. j * weightless and harmless. teed Anyone can adjust it.” Over one hundred thousand sold, - Gusran rot, fire, rust, . t Write for booklet and testimonials. THE MORLEY CO., Dept. 797, 26 South 15th Street, Philadelphia Dollars in Hares We pay $7.00to$18.50 and upa pair and express charges. Big Profits. We furnish guaranteed high grade stock and buy all you raise. Use backyard, barn, cellar, attic. Con- tractand Illustrated Catalog Free. STANDARD FOOD AND FUR ASS'N Samples & Roofing Book § AGENTS 522: J PROFIT Gold and Silver Sign Letters For store fronts, office windows and glass signs of all kinds. No experience necessary. Anyone can put them on and make money right from the start. ' $40.% to $100. a Week! ». You can sell to nearby trade, or travel all “GU, over the country. There is a big demand 5 a ae for window lettering in every town. Sehd : £ d for free samples and particulars Liberal Offer to General Agents. METALLIC LETTER CO. 433A North Clark Street, CHICAGO, ILL

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be ee ipriaaap metas . ae rr tee ra ee £8 i SE a Sh ee epaeiibies all Lae tr ee " cash , r eet , tenia athe earn Wen Tractor Business by Rahe Practical Method Standard Instruction of America. The Rahe method inciudes enorm- ous equipment, twice more than any other auto school — Autos, Trucks, Tractors, Electric Start- ing, Lighting and Ignition Sys- tems of all types. The greatest tire repair, machine shop and oxy-acetylene equipment. The greatest live motor department in the United States. Anto& ‘School Worlds Oldest and Greatest Tens of thousands of Rahe gradu- ates are counted among the best men in the automotive industry. Our experience of more than 12 years, with our vast equip- ment and hundreds of Master Mechanic Instructors and assistants, enable us to train you best and quickest. Earn $150 fo $400 a Month Any man 16 years and older can come to this great school and fit himself for a waiting position or go into business for himself. No previous experience or training necessary. No special educational requirements to start. No tools or “extras” to buy. Write at once) Free 68-page Cata- fog and proof of graduates Success. Rahe Auto & Tractor School Dept, 2887, Kansas City, Mo, (Two blocks to your left as you come out of the Union Station.) ane Water-Glass for Preserving the Cistern ATER-GLASS, which is used for preserving eggs, can also be used in cisterns. That is, it forms a coating upon the walls, keeping away pollution and the creeping in of surface or sub-surface water. When a cistern is built, there is a pronounced chemical action between the water contained therein and the cement walls. As a result the water is very apt to become hard, possibly to such a degree as to be unpalatable. A copious application of water-glass will prevent this chemical action and soften the water. When building a new cistern, simply give it a final coat of cement, let it harden thoroughly, and then paint it with water-glass solution. Water-glass is absolutely harmless, can be purchased almost anywhere, and will repay its use.—L. B. ROBBINS. Even a Tractor Sometimes Gets Stuck in the Mud OSTLY delays are often en- countered in any farmer’s tractor experience, because of miring down in wet or loose soil. This can some- times be avoided by resorting to the use of proper methods. One farmer hit upon a simple scheme which brought the tractor out in less than twenty minutes. In going from one field to another, the tractor was driven through a low spot FLYWHEEL ROPE. TO TEAM METHOD NO.!. TeacTor L0G OPE TIED TO SPOKE METHOD NO.2 Has your tractor ever mired in deep mud or sand? Here are two good ways to get it out which proved to be too loose for the drive wheels of the machine. After several attempts to get it out by its own power, a rope was wrapped about the surface of the flywheel, after one end had been tied to one of the spokes. A team was hitched to the other end, the gear train thrown . into mesh, and by wrapping the rope again as it was unwrapped from about the flywheel, as often as was neces- sary, the machine was slowly hauled out of the low spot. Lack of power in this case prevented the tractor | from pulling through on its own | power. In another instance, a tractor that had mired down and lost its traction was able to pull out on its own power eral feet ahead of it, and fastening Popular Science Monthly aay ters. Ca’ ASST ES, all the stander LOFTIS BROS. & CO. THE MATIONAL CREDIT JEWELERS Dept.N-871 108 N. State St., Chicago, Stores in Leading Cities Make Your Bike a WY CO race Ce by sinking a timber ina trench sev-- two log chains to it from the drive Cleartone Phonographs $4.00 to $200.00 Re“ail Our Sundry Dept. offers Needles 39c Ret thousand. Motors $1.36 to $14.75 each. Tone-Arms and Re- ucers $1.30 to $5.75 per set. Main apnes 2U0e 90c each. Records, Needles, Sapphire Puvints and Parts at reasonable prices. _ Write for our 84-page catalogue, the only one of its kind in America, illustrating 33 different styles of Talking Machines and over 500 different Phono- graphic Parts, LUCKY 13 PHONOGRAPH COMPANY Expert Dept. 466, E. 12th Street, N.¥., U.S. A. | NEED BRANCH MANAGERS Will pay big money to men with autos. Inst ll Rideezee, the , BETTER THAN AIR IN- NER TIRE. Cheaper than tubes,a light resilient substance guaranteed ten years. Equip your car at agent’s price. Sell to friends. The business of the future. RIDEEZEE Co., ST. PAUL, MINN. cs DIRECT FROM FACTORY TO YOU OUR NEW CATALOG WITH 600 OF THE \ LATEST UP-TO-DATE DESIGNS FREE. a ee Cc. K. GROUSE CO. Bruce Ave.. North Attleboro. Mass. Keep Tabs on all the new inventions and dis- coveries by subscribing to POPULAR SCIENCE wheels.—DALE VAN HORN.. 124 MONTHLY. |

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May, 1920 A Practical Way to Tighten Wrist-Pin Bushings O tighten a loose wrist-pin au. when it is located on the con- necting-rod, take a piece of tubing that will just slip over the bushing on one side of the connecting-rod. Next get a piece of metal a little smaller than the bushing to put against it. Place them in a vise and press the bushing out. Now give the bushing about a quarter turn and-thrust it back in the connecting-rod, and you will find the wrist-pin tight enough to run for some time before it will be necessary to renew the bushings. To Keep the Dust Out of - the House — OUSEWIVES in general will wel- come anything that removes mud from the shoes outside the house

door. The frame shown in the illus- = hl METAL

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Shoe-scrapers are manufactured usually of iron. Here is one made almost entirely of wood tration is made of wood, with the exception of the scraper, which is a piece of 14-in. iron. The wood may be of hard maple, pine, oak, or cedar; but whatever wood used should receive a coating of enamel or water-proof varnish to make it durable and also to permit of an occasional washing. By following the diagram the scraper can be easily made, and when at- tached to the doorstep or porch it will prove a big help in keeping the floors clean.— RONALD PRINDLE. One Reason Why a Gasoline Engine ‘‘Skips’’ AILURE of a cylinder to fire may be due to an improper mixture of gas and air, dirty spark-plugs, too great a spark-gap or too lean a spark. Every motorist has noticed that skipping is much more frequent when the motor is running slowly than when it is running fast. This is due to the fact that when the motor is running fast, and also the generator, a high voltage is induced, and con- sequently a fatter, hotter spark is produced at the spark-gaps. Evidence of this increased voltage is shown at night by the lights. When the car is running slowly the voltage across the lights is but little more than that of the storage battery, and the lights are dim. But as the speed increases the voltage becomes higher,

TheWorld of Industry Needs

How Columbia si _ (More letters on request) _ “I have accepted a DLA WO) | You Can Learn Quickly By Our Practical Method you are a person of even average ability, you can master this profitable profession in your og tet ea at your own home through our “Home Study Course.” You can in a short ti tase Uneeune & Sent Gane Deetionion Be cunse of the fact thes cut Soe and

tsman and a teacher especially q him to give you sue hind of teshainn wen We teach you to work from actual models just as you would in a or ea instead of merely copying from

Draftsmen Get $35.00 to $100.00 - a Week -° E very mechanical idea must be drawn out by the drafteman before it can become a reality. On account of the importance of his work. he is therefore paid a gvod salary and is always in line for advance- Drafting is not only one of the best paying professions, bu is the stepping stone to bigger opportunities. Man: Many men, receiving up to $40,000 a year and over, in technical positions, owe their success to their knowledge of Drafting as the starting point. General | construction companies, eee ‘ot unanhiely. of tools and special equip equip- >in

Students Succeed

numbers and at better salaries than

ever tion ° draftsman, pa: ing $2.64 40.00 a Yet ‘“‘Columbia’’ Graduates are the Kind of eas cae lee ae Ge Draftsmen that are Needed with you, which has proven all that properly trained Draftsmen, such am those graduated by the was needed for me to become a COLUMBIA SCHOOL OF DRAFTING, are the ones who get professional draftsman.’”’ — Lau- the preferred positions and . ~ sala: retice P. Johnston, “Several firms have $40 a ries, and are the ones who are most. greatly in d our students demon- ( strates Sis. fact. Cclunibie poke ena are important Positions in big concerns throughout the country. We would ee to ent 7s 2 p> of ene m.many of our

net pm.

hose pr highly paid here ve my positions as Draftsmen are the result of their practical train- second aime tie have ing with us. A few of these letters are here reprinted. decided to stay. I nnd’ t ere are hundreds of men No Previous Training Required

ope’ for and if I quit where. IamI

As our students are given practical Drafting work from the be- q could secure another position in ginning of our course, they grasp the essentials quickly, so that no | three hours’ time. ere will be F mip ious training or drafting experience of any kind is required te take up 4 @ still greater demand for Drafts- work with us. You do not even need « high school education to learn men.’’—Geo. Murray, Jr. Professional Drafting as taught by this school and the gms “4? sive you is all that is needed to secure a position as Draftsman Ty express my ap- ston’s letter). a nae NS I in I Drawing Outfit Furnished Students the progress of my studies and for We furnish, without extra charge, an individual drawing outfit to all our g aiding me, upon completion of students for use throughout the course. mies your property as rose couse ~~ sours a very soon as the course has been paid for. rable .. at & mont ' to start. I am getting on well co ay QS SSK ae BUSH OSES OHBABSw aH» oat Re ee We advancement “pcg gfe sos : a ata yx SCHOOL OF DRAFTING , x nt.’’—. ahi 7 deowil won wit 70H Dept, NOS Mace ET Seren NW “T have accepted a good position do TO-DAY. If g Pp ’ treets, ai with a large manufacturing con- | You are interested in ™ Washington, D.C. cern in Chicago and wish to thank learning this interesting Without obligation to me, please send me FREE ou for the traini your School and big paying pro- @ your illustrated book of particulars, testimonials as given me.”—E . Johnson. fession, send the follow- from students, rates and liberal terms. 8 oxapee Nadir gg acing 8 A-2 A ‘or our Free PRE th “ — ene ste catalog of particulars. 4 Name ...cccccccccccccrccevenveceseceesesssseees g. = ore, <r a year; COL ounaee S T. wh, S yer; Ff Bee C., Claflin. Prac. a Street amd Mo... wc cccccccccccccccccecscccceceens R. Fowkes, $3.700 a year. Roy C- ae Pres. ap penny dens Lath &T Streete, N.W., ® : Washington, Rey ge et CM Es clan kdb aaciopel cath ne ee ee Be a Jazz Music Master Yes, you can, even if you have never touched a piano. The Niagara School of Music has perfected a method of instruction which will enable = you to play all the popular song hits perfectly Ks 4C All you reed to know is how pus to hum a tune. Our method ano nO —only 20 lessons, which you not can master in a little while— ay will enable you to transform ris the tune which is running through your head into ac- BEA | tual JAZZY music on the *| piano. All by ear. : It is Easy to Learn Many masters of Jazz and —~—=————=~) Ragtime music don’t know anote. Bea Music Master yourself. It is easy— the lessons interesting and sim- ple—no tedious ding-dong daily practice, with the do, re, mi, until you think vou ih ag Ca . , en in! lteore and viutuesmue | | Get Wholesale Discounts friends will marvel. ou INTRODUCTORY OFFER = you can try these famous shirts simply play by ear. by mail. for the set $5.70 less 10%. On receipt of $1.00 Beasen theTune ,Playit by Ear we send t splendid shirta parcel post C. O. D. $4.13 he ce morke | ces. a | , hum the tune, play ° ? Yourself, All by eat. ust Six Months’ Wear Guaranteed think how many dull hours finest whi ing fab h this easily acquired ability vase —_—_— of Tone, cn Nevandar?"Oina obit gh oath on Se will make hapny, how many the set. 9 Taek in the ipovular coat i style. outs attach . hand laun tae Ae | friends you will make ha DY, and ver sets Sade chad si a sow popular you w M not plea ve time, order now ai when you JAZZ the newest mgr Broadway pre / rs REE SBE Ss, ecues| | WRITE Giete DURATEX ; es b biet a se Mester") an enor, It iP Grhmta ful ; , Catalog ve a = NIAGARA SCHOOL OF MUSIC, Niagara Falls. N.Y; os qed pe a apne merwoat, neckweet se a atclagniannton cn Sena — se = = «= wMAIL THIS TODAY ae ees == shirts i wens ge new garments trea: bs | Pemtaee sesgtn te mail to address below, your owe a, porbathek ei apd Street Wearer agents make extra money in Spare time Ppa A ESE RN RI" “SORA G SE GOODELL & CO., 551 DURATEX BLDG., NEW YORK ds Lereest mail wholesale haberdashery house in the world

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000 More Miles' To Old Tires Stations Needed Everywhere You know what 4,000 to 5,000 additional tire mileage means to motorists. Haywood’s Tire Surgery is a new tire repair method that gives new life and thou- sands of miles of additional service to tires which before would be thrown in the junk pile. Think of what this means, man, as a@ money making opportunity. Think of the business that is going begging to pay you big money if you're ready to act. FE Wonderinl Business Easy to Learn—No Experience Necessary confinin Uncountable millions of tires are cut, torn, gashedand bruised, {{ myself solely to re-build. broken down, worn out, yet with the Haywood method of tire} ing of Tires by Haywood gurgery all these tires, ~ matter ny ba ag can be pat ox Method. into service. Every town, every hamlet, every city needs Haywood Tire at Mt and it’s that we are o: ering you— $6,500.00 Home Paid For @ business of your own—a_ business that is already making John W. Blair, Toledo hundreds of men rich and so will make you. Ohio, says: “When i YOU CAN LEARN IN A WEEK. _ Walk right into $2500 to if started three years ago, a year—be independent in business for your- had just $50.00 left after the facts. paying for my outfit. I now have a $6,500.00 self. Let-us send you home paid for, $1,000.00 Mail Coupon — Get My Free Book in one bank, and de- Just put your name and address on the coupon be- : ; low, end it to me by return mail, and ’llsend you f Posits in several others.” without obligation full particulars of this money a opportunity. My Free Book explains 5 everything. Tells how to start business with very little money. Now you can easily and quickly learn all about tires and m method of TireSurgery. It will anod pen how to handle every detail o m,sarwoon Weems tray. "ie posage form eet OF POO tard wl prove Kee the best investment you ever made. M. HAYWOOD, President HAYWOOD TIRE & EQUIPMENT COMPANY 626 CAPITAL AVENUE INDIANAPOLIS, INDIANA Mat Ta-day For All Facts M. HAYWOOD, President HAYWOOD TIRE & EQUIPMENT COMPANY 626 Capitol Avenue, indianapolis, Indiana Dear Sir:—Send me quick. without obligation, full particulars of Tire Surgery. Name : Address o-<—. ed lied ne ee ee ee

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mean money to you if you make POPULAR SCIENCE MONTHLY, 225 West 39th Street, New York " WANTED How to Make Wireless Instruments R ives i . ; i ; Popular epresentativ: *s in Every Factory | A little book that fully describes the construction of discoveries. Many of the new ideas come from the skilled work- spark wireless instruments and apparatus. Just the men in the factory. i ” f ’ # e want representatives in eve ‘actory in the country. It will B k Dept., Popular RSE Monthly 225 West 39th St., New York City thing for the amateur. Illustrated. Price, postpaid, 25c.

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The hazards of motoring are in- creased by defective warning de- vices. The signal that cannot fail is the Buell Explosion Whistle. Over 200,000 in use; 10 year guarantee. Eas- ily installed, simple in operation, requires no attention. At your dealer or write direct. BUELL MFG. CO. Cottage Grove at 30th, ~ Chicago

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Popular Science Monthly more current flows through the lamps, and the lights grow bright. Likewise, with increased speed there is more voltage across the induction coil, and a hotter spark results. Skipping results in loss of power and irregular motion of engine and car; and, whatever its cause, it should be located and remedied without delay.— FLoyD L. DARRow. A Novel Way to Use a Discarded Milk-Can HE house shown in the illustration was built under a hill, and with a short chimney the draft for the stove was poor. In order to improve the draft the man of the house took an

An old milk-can may be used to assist the chimney draft old milk-can, cut out the bottom, and secured it to the top of the chimney. It has served its purpose for a long time, and no doubt will last longer than the galvanized pipe used for that purpose.—HARVEY MEAD. How to Make New Lamps from Old IKE Aladdin of old a good many industrious housewives believe in rubbing their metal lamps. Aladdin got what he wished for when he rubbed his wonderful lamp, but the housewife generally gets, in the course of time, what she doesn’t want; namely, a shabby lamp; for it doesn’t take long. to rub the lacquer off metal. Lamps wouldn’t be permitted to remain shabby very long if house- keepers knew how simple a process it is to re-lacquer or re-enamel them. Paint dealers, druggists, and dealers in plumbing supplies sell the lacquers and enamels in small-quantity con- tainers. Directions for applying usu- ally come with them. It is possible to make an old lamp look like a new one. For instance, a plain brass lamp may be enameled in white or ivory by using the proper undercoating. Other effects are as easily obtainable. So, while Aladdin could get something with his lamp that housekeepers of the present day cannot get, the latter may console themselves by the thought that they can do things with their lamps that he couldn’t do.

an aoe Ok o.

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May, 1920 A Rhubarb Press Made from a Clothes-Wringer N old clothes-wringer was con- verted into a press for extracting the juice of rhubarb by the following procedure. The rubber rolls were removed, and in their place were substituted ee ey eon Belle sees Theserolls were cut round, of the same shape and size as the rubber rolls, and then sawed JUICE 7 into equal That old clothes. halves. Nctch- wringer will make an es were cut excellent press for near each end . extracting fruit juices : to -hold small wire flush with the surface of the rolls. Then a core was cut in the center of each roll the size of the steel shaft. The rolls were then placed on the shafts and held firmly in place with the wire. With a stiff spring tension the juice was easily extracted from rhubarb, grapes, and other fruit. A tin strip, bent to shape, was tacked on to the bottom of the wringer posts, one on each side, to drain off the liquid into some receptacle-—DALE VAN HORN. Making a Suitable Holder for Pieces of Work OR the purpose of securing the piece operated on in a machine- shop, it is often necessary to construct a special holder, the shape and size of which must be governed by the par- ticular conditions. For example, sup- ‘pose that a bolt, rivet, or similarly shaped piece is to be clamped for an operation such as threading, filing, shortening, etc. Under such condi- tions, a device like the one illustrated may be used to advantage. The holder shown consists of a bent metal strip with holes of various sizes for the bolts, and a wedge for securing Z SSS The wedge secures the bolt, rivet, or similar piece to be filed, threaded, or otherwise operated on the bolts in position. The wedge passes through suitable slots in the metal strip, which is bent down into the horizontal portion for fastening to the bench. The bolt or rivet is inserted in the hole that fits its shank, and the wedge is forced into place by a couple of light blows from a hammer. When the work is completed, the piece may be removed readily by lightly tapping the end of the wedge.—H. C. RIDGELY. = on oe ee ee ee ee * TRADE-MARKS AND 0) AA ATENT SP ECIAL OFF PATENT ABLE NATURE Before disclosing an invention, the inventor should write for our blank form ‘‘Evidence of Conception.’’ . This should be signed and witnessed and if returned to us to- gether with model or sketch and description of the inven- tion, we will give our opinion as to its patentable nature. Our Three Books Mailed Free to Inventors - Our Illustrated Guide BOOK HOW TO OBTAIN A PATENT Sent FREE on Request Contains full instructions regarding Patents, Trade-Marks, Foreign Patents. Our Methods, Terms, and 100 Mechanical Move- ments illustrated and described, Articles on Patent Practice and Procedure, and Law Points for inventors. OUR TRADE MARK BOOK Shows the value and necessity of Trade-Mark Protection and gives information regarding unfair competition. OUR FOREIGN BOOK We have Direct Agencies in all Foreign Countries. Write for our illustrated Guide Book on Foreign Patents. SPECIALIZATION Our Staff The field of invention is so fast that it is impossible for any one man to become an expert in all the different classes of invention. Only those practically skilled in the class to which the invention relates are capable of rendering efficient service. For this reason Victor J. Evans & Co. employ a number of patent lawyers and mechanical experts who have been selected for their special knowledge and ability in certain lines of invention. Each case is placed in charge of experts in the classes in which the invention relates. THE VALUE OF YOUR PATENT Will depend much upon the skill and care with which your case is prosecuted in the United States Patent Office. This work will receive the benefit of skill and ‘experi- ence acquired by a long and successful practice. We spare neither time nor pains to secure the broadest possible patents that the inventions will warrant. That every case entrusted to us receives our best efforts, and that our work is done consistently, skillfully and thoroughly is evidenced by the many unsolicited letters of commenda- tion that we receive constantly from our clients. We will furnish upon request lists of clients from any State in the Union for whom we have secured ‘patents. Our New York, Philadelphia, Pittsburgh, Chicago, and San Francisco Offices Owing to the growth of our business we have established for the benefit of our clients-Branch Cffices in New York City, Philadelphia, Pa., Pittsburgh, Pa., Chicago, Ill., and.San Franciseo, Cal. These branch offices being located in these large commercial cities, together with our: Main Office located near the U. S. Patent office, in Washington, enables us to more promptly handle the business of our clients, particularly as the branch offices are in constant touch with the Main Office and fully equipped to handle patent businessin allits branches. ~ Highest References—Prompt Attention—Reasonable Terms MBean ae ee ee OF REE COUPON™ ®@ ®® @ wee = = @ = & jiuvedearaerayyy itt wit \ ayy) ly \ iWin \VICTOR J. EVANS & CO: Patent Attorneys Pittsburgh 1007 Woslworth Bldg. 135 S Broad Street 514 Empire Bldg. Chicago Offices, 1114 Tacoma Bldg. San Francisco Offices, Hobart Bidg. ,Main Offices, 760 9th Street, Washington, D.C. Gentlemen: Please send me FREE OF CHARGE your books as described above. i) ii) } | Ea | “ i i SN Ki \| Ni | uit i Ni

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Terms Reasonable PATENTS Write for free booklet Highest References Send model or drawing for preliminary examination and report as to patentability Best Results ALL BUSINESS GIVEN PROMPT AND PROPER ATTENTION WATSON E. COLEMAN, Patent Lawyer, 624 F St., Washington, D.C. PATENTS F YOU HAVE AN INVENTION which you wish to patent you can write fully and freely to Munn & Co. for advice in regard to the best way of obtaining protection. Please send sketches or a model of your invention and a description of the device, explain- ing its operation. All communications are strictly confi- dential. Our vast practice, extending over a period of seventy years, enables us in many cases to advise in regard to patentability without any expense to theclient. Our Hand-Book on Patents is sent free on request. This explains our methods, terms, etc., in regard to Patents, Trade Marks, Foreign Patents, etc. yr If you are a reader of SCIENTIFIC AMERICAN ou are probably aware of the fa ct that it has a special appeal to the inventor. Each issue contains a description of a large number of recently pat- ented inventions. Pending pat- ent legislation as well as the most recent rulin of the Patent Office and the courts are considered in its columns. MUNN & CO. SOLICITORS OF PATENTS 683 Woolworth Building, New York 624 F Street, Washington, D. C. Tower Building - Chicago, Ill. Hobart Bldg., 582 Market Street, San Francisco, Calif. ATENTS PROCURED and TRADE-MARKS REGISTERED Twenty Years’ Experience. Instructions and Terms on request. ROBB, ROBB & HILL, Attorneys at Law Specializing in Patent and Trade-mark Practice exclusively 840 McLachien Bidg., 1336 Schofield a mids. ee Ww ington, D. C. Cleveland, Ohio. P Sa ee ~-~ = ae Before applying for a patent write for a Free Copy o our book ‘‘How to Obtain a Patent,” which contains valuable information and } advice to inventors. Ittells how to secure Patents. Send a model or sketch of your invention for our ‘Evidence of Conception” form and our opinion of its patentable nature—Free. Twenty years’ experiencein patentmatters. Write today for your BOOK, bbetaeteeeeraree ORPRER ROS RR SROBSE SOAR RE SERRE ED SECURE A PATENT, send for Our Guide Book, HOW TO GET A PATENT, sent Free on request. PUPS PRO ESUOUESUPRE RUSS U SUC OSES SES EOC GEE STEGER ES ARES PATEN TS Geo.P Kimmel Pe ROee C CORUEM PSESCEOCCUETS POSE CEC See seae £25 ERASE) Trade Marks Send sketch or model for actual search and report. Write for Book- let of instructions on patent practice and procedure. Prompt personal service.... Patent Lawyer u - = - . = ~ = = - os = ~ ~ = « “ = * “ - = « = > = = = = = - - - = - ~ o IF YOU HAVE AN INVENTION and DESIRE TO LEARN HOW TO Tells our Terms, Methods, etc. Send model or sketch and description of your invention and we will give our opinion as to its patentable nature. RANDOLONG CO. * ao... 130 F St, N. W.,. Washington, D.C.) cope... sessssssse silica SP ee ee ee ee ee ee Popular Science Monthly There’s the Rain-Alarm— Close the Window T is no joke to wake up in the middle of the night and find the windows open and rain coming in. After one or two such experiences, one practical fellow made an auto- matic rain-alarm which was placed outside his bedroom window on hot nights when the windows were left open.: He secured an old electric-light bulb, and cut it in half by tying a string to it and wetting with alcohol, after first breaking off the tip. Then the lower half, including the: base and terminals, was screwed into a socket, which was fastened to a board as shown. The large copper wires lead- ing to the filament were bent back BULB eh BELL” a BATTERIES Why wait to wake up and find that a mid- night rain has ruined the window cur- tains? Make an electric alarm that will warn you when the rain begins to fall down into the bottom of the cup, one on either side, care being taken to keep them from touching, handful of salt placed around them. This was connected to a battery of two dry-cells, and then to a door-bell placed in the bedroom. A_ switch was also placed in the circuit, complet- ing the outfit. The action is obvious. As soon as any moisture reaches the salt, a solution is formed which is a good conductor of electricity, and im- mediately a current is set up whieh rings the bell. To break the circuit, turn the switch.DALE VAN HORN. The Hairpin Becomes a Pair of Calipers PAIR of calipers is perhaps the most frequently used tool in the machine-shop, being required for al- most every kind of job. One day the writer wished to take some outside measurements and he couldn’t find his calipers in the tool- box. His eye lighted on a scrub- woman in the next room and a bright idea came into his head. Why not beg a hairpin and make a pair of calipers with it? He followed up his idea, the measurements were taken, and when the job was finished it was found to aline properly.—A. G. VIDAL. and a. sr i) J

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May, 1920 U.S. ® PATENTS / sie fim pier: [fee ZS 1 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. A sample form together with printed instructions will show youjust how to work up your evi- dence and establish thesame before filing ap- plication for patent. As registered patent at- torneys we represent hundreds ofinventors all over the United States and Canada in the ad- vancement of inventions. Ourschedule of fees willbe found reasonable. The form “Evidence of Conception,” sample, instructions relating to obtaining of patents and schedule of fees oat \ ae request. Ask for them,—a post card will do. 274 Ouray Bldg. WASHINGTON, D. C. Originators of forms ‘‘Evidence of Conception.” CAN YOU think of a simple, practical idea that will fill one of the many ree quests we have on file for new inven- tions? It may mean a fortune for you, Thousands of thingsare needed Ricut Now. Your brainscan help. Send to- day for our great new book—“‘Invene tions and Trade Marks, Their Protection and Exploitation” and learn more about making money from ideas than you ever knew before. It tells many things that are wanted, t0O. A postal will do— it is free. We help our clients, PATENTS the dollars out of thelt ADVERTISED ideas—having facilities Done others possess. For SALE FREE avanenae In INVENTION And ox at once," “MA MANUFACTURING AMERICAN SUPPLEMENT. ‘ INDUSTRIES, INC. man an cen 201 Patent Dept., pe samme WASHINGTON, De. pon ae weeny he Bak for Inventors and ADAn had ioe eile, 9 SixTu Eorrion By return mail FREE. Write LACEY & LACEY Dept. M Washington. DC. SIXTH EDITION DO YOU KNOW EVERY MOVE YOUR ATTORNEY MAKES? \X INVENTORS «+ My clients are immediately informed of every step in the prosecution of their applications. Write Now PATENTS. Send Sketch Office of WARNER I. CUBBERLEY, Patent Attorney 20 National Union Bidg., Wash. D C. Neglect Is the Cause of Most Battery Trouble EMEMBER that the battery is totally different from any other part of your automobile—that it is chemical, not mechanical, in its func- tion. You do not pour electricity into it like a fluid, and then draw it out to use as you do water from a faucet. You pass a current through it from the generator, which is geared to your engine, and this current changes the chemical conditions, caus- This motorist is about to pay the bat- tery repairman a goodly sum for repairs which could easily have been avoided ing sulphuric acid to combine again with the lead of the battery’s plates. The amount of acid in the battery is therefore constant, and you should never add to it, with the idea that it will put “‘pep” into the battery. When the battery goes dead, it is because the acid has gone back into the plates, “sulphating” them; and in that case what the battery needs is a prolonged charge to draw it back into the solution. It is probably your own fault, be- cause you have used more current for lights and starting than the generator could put back. You should have learned that you must test your battery with a hydrometer, an instrument that registers the specific gravity of each cell and tells you whether the battery is charged properly or not—since the specific gravity of the battery solution (or its weight as compared with water) varies according to the amount of sulphuric acid in it. This test should be made every two weeks. If you continually drive fast, if you take long tours, if you have few starts and stops and little use for lamps, you will put too much current into your battery and burn up your plates. If you are a doctor, driving in winter with many stops, short runs, and lots of night work, you'll take too much out and the battery will ‘‘go dead.” But with regular testing you can regulate driving and avoid trouble. If your battery is being. underfed, ‘| take it to a service station and have it 129 aWEEK Pays for the Black “Beauty Noexercise is better than cycling for build- ing up muscle and vitality. As a sport, a wheel sets you free—free to roam the fresh countryside and breathe invigorating air. You can be a bike owner now, without Awaiting to save money or postponing the benefits of cycling. Simply send for a catalog, select your model, and Black Beauty will be shipped to you at once, on approval. We pay all freight. When you've seen for yourself what a magnificent wheel the Black Beauty is, pay a small deposit, then $1 a a week (or $5 a month). ’ hand 5 horns, bells, lamps, etc Everything that goes with a wheel. Send for free Sundries Catalog. 18 Exclusive Features Although coming me more than any other pane ESR and fois It’s built he's co ; *s bu a Bigh-pricee mnotorear—only the best workman- P: only the ey oy — materials. Looking at it, you know it’sa roughbred. Racy lines, powerful steel frame, smart colors, shining nicl.e} and enamel finish. Then, the Black Beauty has eighteen fea such as the famous $10 Firestone Blue- Non-Skid Tires; New Departure ( coaster } rake; motorbike saddle, pedals and handlebars; Duck- worth roller chain; Diamond E. spokes; “B-B” sprocket; chrome steel ball bearin.s, etc. Don't dzlay. Write now for illustrated Black Beauty catalog. A post card will do. HAVERFORD CYCLE CO. Dept. 385 PHILADELPHIA Send Today For Free Catalog m Cotors t (OUT aeletca

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pred _-aieaberrtieat ar ee a ee aa rn rn eens ae een oo east - . When Your Stomach * Goes on Strike ai Pen: ee nema When your stomach or liver or kidneys go on strike, it isn't for shorter hours or higher pay. It’s simply for decent, workable, livable shop conditions. And it’s no matter for compromise or arbitration; it’s no case for hesitation and delay. Your health, strength, vitality— your life itself—depend upon your rectifying the wrong con- ditions and treating your faithful servants right. YOU CAN’T AFFORD TO DELAY The wonderful machine God gave you was built to run a hundred years or more, but it will burn itself out and break down long before that, like any man-made piece of machinery, if you abuse it and let it get into a dilated state, and then fail to make the necessary repairs. The distress occasioned by consti- pation, indigestion, head- aches, nervousness, or any other ailment, is merely a warning flashed to your brain —and by the brain to the senso-y nerves—that one or more of your vital organs are not running right; that they need attention and need it quick. You would be poi- soned to death within a few days if your kidneys went on strike. And you are being poisoned by constipation just as surely, although more slowly, when your intestines lose the power of eliminating promptly and thoroughly the waste matter in the food you eat. FIT YOURSELF TO ENJOY LIFE A man’s happiness largely depends upon his Vital Powers; his success in social, domestic and business life all centers around this. If he is not virile, he is not magnetic, forceful or attractive; neither is he sought after—his very strength is the axis upon which all else relating to him revolves. Men become weak through overwork, worry, sexual abuse and bad habits, and gradually lose their strength and manhood. When they reach the stage when they find their strength on the wane, it is the forerunner of failure and domestic happiness is then soon upset. Young men, listless and ~ their brain power decreases as their man- STRONGFORTISM The principles of Strongfortism are based upon my discovery that inte: muscular activity governs Health, Strength and Life itself. Most forms of disease are caused from the muscles losing their power of rapid comeractign. As _ = pee are — — for the inte: organs in position, when they are me | the organs gradually fall out of their place and rest upon other organs, upsetting their functioning and causing almost every wn form of disease. STRONGFORT The Perfect Man and quickly makes them normal and so draws the ng organs back to their position. ee 5 . Just what Strongfortism is: simply the utilization of Nature's own resources to free yourself from handi- capping ailments, build yourself up and regain your lost health, strength, energy and power. . I have spent my life stu g out the means whereby wonderful, hidden forces of Nature may be brought into play and utilized to their fullest extent in the upbuilding of weak, ailing, discouraged men and women. By means of them I built up myself until I am called the most perfect and the strongest man in the world. By the same method I have brought and am bringing health, strength, vitality, confidence and courage to my pupils in every part of the civilized globe. What I have done for them I can do for YOU —there isn’t the slightest doubt of ite SEND FOR MY FREE BOOK You will be intensely interested in “Promotion and Conservation of Health, Strength and Mental Energy.”’ It tells you just what Strongfortism already has done for thousands discouraged, despondent men and women. It shows just what it can do and will do for YOU, without medicines and drugs of any kind, and without interfering in any way with your usual work or occupation. Fifteen or twenty minutes daily devoted to Strongfortism, in the privacy of your own room, will bring about an improvement that will be noted with surprise and gratification by all your'friends. Send for the book today—NOW. Don't run the risk of missing it by waiting until tomorrow. IT’S FREE, but its VALUE to you will be inestimable. Fill out the coupon and enclose it with three 2c stamps te pay for packing and postage, and I will mail you along with the book a special letter on the points in which you are most interested. LIONEL STRONGFORT Physical and Health Specialist 1235 Strongfort Institute NEWARK, N. J, CUT OUT AND MAIL THIS COUPON Mr. Lionel Strongfort, Newark, N.J. Dear Strongfort—Please send me your book, “‘Pro- motion and Conservation of , Strength and Mental Energy.’”’ for postage of which I enclose cents in peace to cover mai expenses. I have marked (X) before the subject in which I am interested. ; 1235 ...Colds ...Deformity ..Poor Memory .--Catarrh ... Insomnia ... Rheumatism ... Asthma ...Heartweakness ...Poor Circulation -i Obesity ..-Short Wind ...Weak — ---Headache ...Flat Feet .. Fallin, air ..-Thinness ...Constipation ...Bad Habits ...Rupture .--Biliousness ... Weaknesses “prea oe fie id Liver . Skin snag ...New des gestion ...Despondenc ed Mat Chest ..- Nervousness ...Round Shoulders ...Lung Troubles ...Increased Height PRD 4 vin no bbs AuCkee Nhe halk 90 00 cocsencncéccodecsencuese AD, ios écied CURR iin dign ccc ccccncecovestepespocess GGG oS Baden on vddanenes ene eveccces eecccecccccccccccocs i nttscwsncoce State. .ccccccoee Svevesoeses Rvacese charged. The cost of this essential service is insignificant when compared to oil, gasoline, and other charges. If your battery is overfed, it will feel hot to the touch. In that case open the starter a little oftener or, better still, turn on all your lights. The other element in the acid solu- tion of the battery is water. In con- nection with this there are two things for the car-owner to remember: 1. What evaporates must be re- placed at intervals of two weeks or so. 2. Use only distilled water which is absolutely pure. More trouble results from neglect of this than from any other cause. When the level of the water falls below the top of the plate, only the submerged portion of the plate is active. That means more current going into less plate surface—and less current going out. Result: overheating and even deterioration of plates. Since 90 per cent of all battery troubles results from neglect of these two easy, simple things—testing and filling—you can imagine what an increase there would be in battery life if simply that much and no more were observed by the car-owner. Moreover, there is hardly a garage that does not profess to flush and test batteries regularly for its customers—yet hun- dreds of cars are daily driven into battery service stations and found to be only half filled or undercharged. Roll the Beans Around This Way, Please ! HE contrivance shown in the illustration has been put into practical use by a Wisconsin man. Instead of ‘‘Please pass the beans,” the standard request at his table is, “Please roll the beans around this way.” Or the hungry one quietly revolves the stand until the bean dish WOODEN TABLE TOP If" THICK AUTOMOBILE WHEEL am | = == Don’t ask for food at thistable. Simply revolve it and the food rolls around in front of you is within reach. _ The construction details are simple. An old automobile wheel, together with the steering knuckle, is firmly affixed to a steel plate and is thus supported on a horizontal plane. A wooden or metal disk is superimposed upon the wheel, a suitable cloth draped over all, and the stand is ready for action. We shouldn’t advise serving soup on this kind of table, for if you were a little bit hasty in obtaining your portion you might get it in your. lap. 130 Popular Science Monthly To the Man With an Idea I offer a most comprehensive, 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 probable 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, 2276-D Woolworth Building, New York City INVENTOR’S BULLETIN Sent Without Charge MY FREE BLANK FORM INVENTOR’S RECORD For Disclosing Your Idea SIMPLIFIES PROCEDURE WILLIAM H.MUuLLicAN REGIS#EREC ATTORNEY 392 Woodward Bldg.. Washington, D. C. PATENTS TRADE-MARKS COPYRIGHTS Send for our free book of patent information Beale & Park is 51st tiicna WILLIAM C. LINTON Consulting Engineer and Patent Attorney “Inventor’s Adviser’? Mailed free on request. Gives full information as to Patents, Trade Marks and Their Cost OFFICE 364 UNIVERSITY ST., Montreal, Canada. 916 F ST. N. W Washington, D. é. DYNAMO BUILDING for AMATEURS A practical treatise showing in detail the construction of a small dynamo or motor, the entire machine work of which can be done ona small foot lathe. Full instructions with drawings. Will run a sewing machine or small drill press. Price, postpaid, $1.10. Popular Science Monthly, 225 W. 39th St., New York sons oe sas 6 LW nm roel as fete A et MA et et Ot ma te wets 1 MF wet lO Ok it

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May, 1920 Piercing Holes in a Large Gasket HEN overhauling an automo- bile—or, for that matter, any machine that has gaskets—it not infre- quently happens that a gasket has to be made that is large and of awkward shape and therefore difficult to cut in one piece. Further, a large piece of material would be required to make a one piece job. If such a gasket does not have to withstand any great pres- sure, as would be the case in gasketing a front-end gear cover on the en- gine, or in some cases a gear-box cover, it can be made just as well from a number of separate Read this article and thenyouwillknowwhat Pieces, making to do the next time long V-joints -yourenginegasket leaks where the pieces come together. If you will look at the illustration above you will get the idea without any trouble. Such a job will be entirely satisfac- tory if the gasket material is rather thick and compressible: cork composi- tion, asbestos composition, and the like work very well. But for gaskets of thin paper or fiber, or for anything very hard, it will not do. Make the joints sufficiently long and fit them carefully, so that there will be contact along all the adjoining edges. As each piece is finished, stick it in place with shellac; this greatly facili- tates the fitting of the next piece. Keep the outer surface of the gasket clean, and when it is all in place rub it with a mixture of graphite and a little grease or oil. This will give you a gasket that will stay in place when next the cover is removed, will not stick to the cover, and will last indefinitely if made as described.—HOWARD GREENE. How to Use Your Watch as a Protractor T was quite by accident that the writer discovered that a watch made an ideal protractor inan emergency. A circle con- sists of three hundred and sixty degrees; therefore each of the twelve hour spaces would consist of one twelfth of three hun- dred and sixty, or thirty degrees. Each hour is spaced off into five equal parts, so each space is exactly six minutes. With a little care one can readily work to a degree with very good ac- curacy.—J. W. MOORE. Here is a very old idea, but it is valuable ‘to know in an emergency 7 Why Do Chiropractors Advertise and Is Advertising Ethical? This question is often asked by those who sin- cerely wish the science of Chiropractic well, but who believe that by advertising the science is reduced to the level of patent medicine and quackery. Upon close questioning, however, it develops that it is not advertising, but rather — particular kind of advertising to which they object. Webster defines advertising as ‘‘giving notice to the public,’’ and ethics as ‘‘pertaining to the conduct and involving the moral question,”’ i. e., the question of right and wrong, so that the question might be stated as follows: Is it right to give notice to the public that a great new dis- covery has been made in the method of getting the sick well? When the question is so stated it answers itself. It is as though one were to ask: Is it ethical to advertise where food is to be gotten to those who are starving or is it right to give notice of the discovery of a spring to those who are dying of thirst in the desert? If Chiropractice is what chiropractors and patients claim it to be, it would be a crime to conceal it from a sick world. If it is half what they say it is, every moral impulse and every ethical consideration would urge those who know its merits to proclaim them. Of course, if Chiropractic is a fraud, if it lacks merit or if it occupies a relatively small niche in the health edifice, such claims as are publicly made would merit the most severe condemnation and penalties. The wonderful increase in the number of practitioners and the rate at which the schools are multiplying, as well as the evident prosperity of the profession and the enthusiasm of the patients preclude any such conclusion. Grant the ethical basis, then, of its being a thoroughly meritorious proposition, and the whole question simply resolves itself into a problem of how best to advertise its merits to that portion of the public who have never even heard its name or whose conception of its philosophy, science and art is incorrect. So we may conclude that the question of ad- vertising is simply a question of expediency and the question of ethics is involved in the merit of the science and the form in which the notice is given, rather than in the principle of the act of advertising. ASS’N UNIVERSAL CHIROPRACTORS’ - U. S. A. DAVENPORT, IOWA, = - nol - 131 ~

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t i yy : at 4 17 a ft: ma: } q ‘L a sercanmrenede i —— or Wes ' pees: mie Mies —_— ee -/ Cronies Beh Ne — ESS - * ‘ * Oy a oni “el T was shown in the article I in the POPULAR SCIENCE MONTHLY for April how the grid in a thermionic vacuum tube makesit pos- sible to use this device to amplify cur- rents. The fact that the insertion of the grid in the tube makes it possible for the tube to amplify also brings within its scope a number of other uses to which the tube can be put. In particular, it can be made to produce sustained oscillations. A device that can amplify can also pro- T, To >A BL ; \ L E = Se = Electron Relays as Amplifiers and Oscillators: Il By H. J. Van der Bijl, M.A., Ph. D. close enough to the input. coil L, to act inductively on this coil. In other words, there is a mutual inductance indicated by M between these two coils. Now the current in the input coil is amplified, and the amplified current obtained in the output coil flows through L, so that the input coil re- ceives energy both from A and from L and J). duce oscillations. The production of oscil- lations by an amplifier is sometimes troublesome. We shall show how the amplifying property of the tube enables it to produce sus- tained oscillations. Amplifying the Currents Referring to Fig. 1, which represents a simple amplifying circuit using the tube as an amplifier, it was shown in the first article that small currents entering the system at A are amplified by the tube, so that the. current obtained in B is larger, and some- times much larger, than that entering A. The circuit shown here, as well as some of the circuits we will show to explain how the tube produces os- cillations, are drawn in as simple a way as possible to illustrate the functions that they perform. The batteries commonly employed in the circuit arrangements are omitted. Later on we shall give complete cir- cuits showing the batteries and where they should be placed in order to get the best arrangement when using the tube as an oscillator. In Fig. 1 7; is the input transformer and T> is the output transformer. The transformers are inserted simply to have convenient impedances connected to the tube. Let us, therefore, consider only the coils of these transformers that are connected directly to the tube itself; that is, coil L,, which is the secondary of the input transformer, and coil Le, which is the primary of the output transformer. The energy in Ly, is larger than that in L, because of the amplification produced by the tube. Now we can make the energy in L, still larger if we take part of. this energy and transfer it to L;. This part will then be further amplified. An arrangement whereby this can be done is shown in Fig. 2. Here L» is divided, one part of it being placed FIG. Vacuum-tube circuit showing connections as an amplifier: note the step-up transformer for input and the step-down for output This part of the energy, which is fed back from the output to the input, is further amplified so that more energy appears in the output coil, and there- fore more is fed back. In this way it can be seen that the current in the out- put of the tube will keep on increasing until it is limited in some way or other. This limitation of the current is caused by the shape of the current voltage characteristic of the tube, something that we will presently explain. The circuit shown in Fig. 2 is so arranged that the input current coming from the line A is amplified, and its period, or the frequency of the amplified cur- rent obtained in the output line B, is the same as that of A; but this principle of feeding part of the output back to the input can be used to make the tube produce sustained oscillations without the necessity of impressing any oscillations on the system from the outside. The circuit whereby this can be done is shown in Fig. 3. It will be recognized that Fig. 3 is the same as Fig. 2, except that the connecting lines Aand B are omitted and that Fig. 3 contains a condenser, C. The coil also indicated by L, corresponds to Ly, of Fig. 2, and the output coil is here designated by L. L, and L are so connected that there is a mutual in- ductance between them. By adding the condenser C we produce an oscillation circuit, LC. It is well known that if energy is continually supplied to such a circuit it will oscillate with a frequency depending upon the values of the capacity C and inductance L, just as a pendulum will swing with a definite period. Suppose a slight change takes FIG.2 Feed-back circuit for vacuum tube, showing inductive coupling between the output and input circuits 182 place in the electron current flow- ing from filament to plate. This pulse will set the circuit LC oscillating with a frequency determined by the values of L and C. The oscillations will, of course, die out unless energy is continually supplied to the circuit. This constant supply of energy is made possible by the amplifying prop- erties of the tube. Thus a change in the current flowing in L causes a change of currentin L,. This produces a change in the potential of the grid, re- sulting in a further change in the plate current. If the phase relations in the plate and grid circuit are such that this effect is cumulative, the current in circuit LC will continue to oscillate with a frequency determined closely by the values of L and C, and will continue to increase in intensity until limited by the characteristic constants of the tube and the constants of the external circuit in such a way that the power dissipated is equal to the power supplied. In order to be able to use a vacuum tube to produce oscillations, it is necessary to know how the production of the oscillations depends on the characteristics of the tube. This makes it necessary to introduce the important quantities, namely, the two plate resistances and the mutual cone ductance to the tube. Plate Resistance The plate-current, plate-voltage characteristic is shown in Fig. 4. Suppose that the normal voltage on the plate is given by the value V, so that changes in the plate current produced by changes in the plate potential will be represented by values lying above and below A. The ordi- nary d.c. resistance of the tube, like that of a wire, is given by the voltage divided by the current. That is, it is given by the reciprocal of the slope of the dotted line OA. But the a.c. resistance of the tube is a different thing. Suppose , that the plate voltage V be in- creased by a small amount c such as A B. The Lg ——|}-— Fe Be current then in- creases to the point C. If the plate voltage alternately in- creases and de- ‘creases by the —— a MAGS Oscillator connection for vacuum tube: note coupling between out- put and input ¢ir aL ne ce oe

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May, 1920 AMATEURS ATTENTION ! Send over) 5 Miles on D.C. Here at last is real ‘‘commercial type’’ radio apparatus designed for low power direct current. New transmitting records are in store for you. Take advantage of this special introdwariny offer and save $7.50. $n rt 23 | = The ““AMRAD” QUENCHED GAP Special Induction Coil Type All your power on one sharp wave and a clear, bell-like note at every tap of the key will make other THE “AMRAD”’ INDUC- TION COIL 6 Volt or 32 Volt is almost an exact duplicate of the U, S. Signal Corps coil used in trench service during the war. It has bake- amateurs in your lite insulation throughout. Its sec- a u tag fe ome ——_ Lg ge ger gg tinge ii ill ite. sa Quenched Gap, carefully operated, yields the secret of long ; : range transmitting on low power. This special gap is iden- output about roo per cent. greater than the average tical in design to the heavy % k.w. and 1 k.w. Amrad 2 inch coil. The vibrator is rugged, steady and non- Quenched Gaps now being installed in long distance amateur sticking and designed to give a spark frequency equiv- stations. Not only will this special quenched gap malve your alent to 100 cycles which means maximum transmitting transmitter as efficient, for its power, as the more costly range on short wave lengths. The 32 volt coil is intended equipment but you will be able to send more messages with- especially for use on farm lighting circuits. When ordered ’ f v out interfering with other stations. For the first time in the separat ly this tvpe is $1 extra. To get maximum results history of amateur radio every induction coil transmitter with the 6 volt coil a heavy 6 volt storage battery is the best can now be tuned to comply with Government decrement and most economical source of current. regulations. The Amrad Quenched Gap is the secret. Price, Gavoit type.......cccccceccecces $28. 50 Price, Induction Coil Type........... $1 2.50 Special Introductory Offer If you have had tee power at your disposal and inefficient apparatus or if you are waiting to be introduced to the fascination of sending radio mes- sages over into the next county or state here is your chance to get the two most important pieces of transmitting apparatus at an actual saving of $7.50. ‘‘Amrad’’ Induction Coil, regular price, e « « $28.50 ‘‘Amrad’’ Quenched Gap, si ae $41.00 Special Price for the Double Buy, $33.50 Either 32-volt or 6-volt coil may be chosen Show this advertisement to your dealer and ask him to order one of these \ How to Order combinations for you. If you have no radio dealer in your vicinity send us check or nonzy order for $5 and we will ship direct to you by parcel post C.O. D., the balance plus postage. Act promptly, as’ the standard Signal Corps parts which we secured from the Government were only sufficient to make up a limited number of sets. If you are not ready to buy and want _ further information send for fom. Bulletin P which eontains complete description and operating directions. on be for short-term trade discount on this combination. ~. ef Opportunity to introduce apparatus of such high quality at such low prices will ever be had again. The offer.is made os ily . introduce our cag growing line of ‘commercial type” mer ) 5 3 ae . AMERICAN RADIO AND RES! ae ee f ad LAY ‘ ' RS WY eae : 29 PAR! lacus Aedfor

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Learn at Home! Employers everywhere are looking for men with mechani- cal ability. Splendid salariesand rapid advancement are offered. There is an easy, delightful way in which you can learn right at homein spare time. For 28 years the International Cor- respondence Schools have been giving men and women just the training they need for success in mechanical engineering and more than 200 other subjects. Hundreds of thousands have stepped into good positions through I. C.S. help, but never were opportunities so great as now. Let the I. C. S. help you. Choose the work you like best in the coupon below, then mark and mail it today. This doesn’t obligate you in the least and it will bring you information that will start you on a successful career. This is your chance. Don’t let it slip by. Mark and mail this coupon now. TEAR OUT KE INTERNATIONAL CORRESPONDENCE ScHOOLs SCRANTO q for the --ol obug tig me. tow 1 an aust ELEOTRICAL ENGINEER SALESMANSHIP ené Rys. ADVERTISING Window Trimmer Show Card Writer Painter MEOH ANIOAL ENGINEER Railroad ILLUSTRATING BUSINESS MANAGEMERT Gas Z Surveying and Mapping and Typist SINE oR Cert. STATIONARY ENGINEER MANAGER Marine Railway Common School Sabjeets CIVIL SERVICE Railway Mail Clerk AUTOMORILE OPERATING Navigation = seniguutoRE oe

T-26-18 Seteruationsl Corrempondeaaen qitesnpen te, istas

|

amount AB, the plate current will os- cillate over the amount given by CB. Now, the resistance of the tube to these oscillations is the increment in voltage AB divided by the increment in current BC, which is equal to the reciprocal of the slope AC indicated by the broken line DAC. This is the a.c. resistance of the tube when the current oscillates over the small por- tion AC of the characteristic. It will be seen that the slope of this line is different from the one that gives ime d. c. resistance of the tube. When the oscillations are not so small, but cause the cur- rent to vary over a much greater range than that indicated by AC, we can no longer talk of the slope of the curve, but we can a to a first approximation ye aa PLATE CURRENT

Popular Science Monthly encountered in vacuum-tube work. It determines the quality of the tube as amplifier, detector, etc. At present we shall consider how it determines whether or not the tube can produce sustained oscillations. The oscillation circuit shown in Fig. 3 represents one of a number of different types, and is the one that lends itself most readily to mathematical solution. The solution of this problem shows that whether or not the tube will produce sustained oscillations depends on whether or not the mutual con- ductance is greater or less than a quantity involving the My constants of the oscilla- he tion circuit LC. This quantity may, for the ad sake of convenience, be represented by a line having a certain definite

represent the a.c. resist- =< ance of the tube by a line connecting the two ex- treme points of the char- acteristic over which the current oscillates. Thus, if the current increases to E and de- creases to F, we can say that the a. c. resistance of the tube to such oscilla- tions is given by the reciprocal of the slope of the line connecting E and F. Mutual Conductance The characteristic shown in Fig. 4 is the plate-current, plate-voltage characteristic, and from it we get an idea of the resistance of the tube. The mutual conductance, on the other hand, may be obtained by a con- sideration of the plate-current, grid- voltage characteristic, such as that shown in Fig. 5. Suppose the normal grid potential is such that the direct current flowing through the tube is given on this characteristic by EO. If the potential of FIG4 PLATE POTENTIAL Showing relation between plate-circuit voltage and plate current. riation in tube resistance

slope. Such a line is shown by GF to the left of Fig. 5, and we may state that the slope of this line depends, among other things, on how close the coupling is between the two coils L, and L, shown in Fig. 8; that is, it depends on the mutual conductance M between them. Now, as long as the mutual con- ductance of the tube is greater than this quantity,—that is, as long as the slope of the line giving the mutual conductance is greater than the slope of the line GF,—the tube will produce oscillations, and the strength of the oscillations will increase until the two slopes become equal. It will readily be seen by referring to Fig. 5 that if the variation in the plate current be- comes greater, the mutual conductance becomes less; thus, while the current varies between the values D and C, the mutual con- ductance is given by the slope of the dotted line DC; but when the current Note va-

the grid alternately in- cre creases and decreases so that the current oscillates around O between the values D and C, then the mutual conductance can be taken to be the slope of the dotted line DC. If the potential of the grid varies over such a wide range that the current increases to B (Fig. 5) and decreases to A, then the mutual conductance may be taken to be the slope of the line AB. It will be noticed that the mutual conductance is given by the slope of the plate-current, grid-voltage char- acteristic, while the plate resistance of the tube is given by the reciprocal of the slope of the plate-current, plate- voltage characteristic. This quantity, mutual conductance, is given by the amplification constant divided by the resistance of the tube. Both these quantities and the mutual conductance may readily be obtained by simple measurements. The mutual conductance is a very important quantity that is often 134 the coupling GRID POTENTIAL Variation of plate current and grid voltage in an os- cillating vacuum tube as varies between A and B the mutual conductance is given by the slope of the dotted line AB, which is - less than the slope of DC. The oscillations produced by the tube will, therefore, increase in intensity, as shown to the right of Fig. 5, until the slope of the mutual conductance line becomes equal to the slope of the line GF. Under the conditions for which this diagram is drawn, which shows that GF is parallel to AB, the strength of the oscillations will increase until the current rises to the maximum value B and drops to the minimum value A. If the coupling beween the output and input coils were decreased, the slope of the line GF would increase, and the current would then not oscillate be- tween values A and.B, but over.a smaller range. On the other hand) by increasing the coupling we can increase - the intensity of the oscillations. [ The third and last article in this series by Dr. Van der Bijl will appear in the POPULAR SCIENCE MonrTHLY for June.] is changed

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May, 1920 Now as Never Before YOU NEED THE !Encyclopaedia Britannica HANDY VOLUME ISSUE War awoke this great land of ours and set the stage for a tremendous industrial, spiritual and social awakening. There probably is not a man, woman or child among the more than 100,000,000 inhabitants of the United States upon whom the past five years has not had a profound effect. Great reforms are being hastened and this will be a better and cleaner world after the ordeals of fire through which it has passed. The participation of the United States as never before in the world’s affairs has brought to the people new interests not limited to the neighborhood, town or city in which they live, but interests that are world wide. A miracle has been wrought in men’s minds, a miracle in which there is a tremendous thirst for knowledge, a knowledge which is absolutely necessary today, as never before. ere can people find correct, authoritative and comprehensive information on the many different subjects in which they are interested, as a consequence of this awakening? They naturally turn to the wonderful storehouse of knowledge—the world’s test guide to correct and authoritative information—The Encyclopaedia Britannica. The Britannica furnishes practical, detailed and authoritative cles of great value to the business man, to the manufacturer, to the importer, to the worker in the industries. The Britannica will give a foundation for study of subjects which will be uppermost in our minds for years to come. It is the book for Americans today who are waking up to new thoughts, new work and new interests. A Complete Library of Knowledge. be stampeded with fear of what is before us? Are you sitting down and ie fe studying the facts of past cases that were somewhat similar? Are you But this marvelous work with its 41,000 separate articles is more than familiar with what has happened after other wars? In England after the a guide for the enterprising business man of the United States, fitting him Napoleonic campaigns; in the United States after the Civil War; to France, to be a citizen of the world—a world merchant. The Britannica isacom- 9 Germany and to Neutrals after the Franco-Prussian war? plete library of knowledge on every subject. It discusses in a way that This wonderful book of knowledge—the new Encyclopaedia Britannica you can understand every branch of science, industry, literature, art, religion, —Jiterally brings the whole world to the reader. It tells all about foreign inventions and engineering; history and race development; wars and peace; countries, their people, their history, their progress, their resources, their architecture, astronomy, chemistry, sociology, education, steam, electricity, imports and exports. An hour a day with the Britannica will give you as geology and geography, biography, law and physics. You and your family clear and comprehensive an idea of the rest of the world as we Americans will find in the Britannica a liberal education. In answer to the hundred now have of the States of the Union. uestions which every day come to your mind and to your wives’ and chil- ren’s minds—it will tell you more about everything than you can get from Woman Needs the Britannica as Never Before. any other source. The war has changed the status of women industrially and politically. The mother must keep abreast of the great thoughts and movements that What Is Before Us? are taking place throughout the world, that are vitally affecting her. Woman There are many serious post-war problems confronting us. Do you today in her greater and more important place in the world needs the ine understand the tendencies in our industrial life? Why are the prices of | clopaedia Britannica as never before—she needs it to teach her how to fulfill commodities high? Will wages go still higher or down? Will the cost of her new status as a citizen—how to make her more efficient in the business living gradually drop? Is there likely to be some great cataclysm that will world and, as a mother, to make herself broader and a bigger woman so serve to send prices and wages tumbling downward? Are you inclined to she can teach her children wisely and correctly. BUT YOU MUST ACT QUICKLY $7 As First Foyment brings you this Complete Set of 29 Volumes Cortaining 44,000,000 Words, 30,000 Pages, 15,000 Maps and Illustrations. The balance is in Small Monthly Payments. Our present small stock of sets is printed on the Sign and Send This Coupon Todey. genuine India paper — the light, | thin but opaque sheet Sears, Roebuck and Co., Chicago, Ill. which has proved an ideal medium on which to print Gentlemen: Please send me, free, your Illustrated Book No,19-G, the Encyclopaedia Britannica. Act today— NOW — by giving full information about the Encyclopaedia Britannica. Also clipping the coupon and sending for the beautifully tell me what I will have to pay for a set of the Handy Volume illustrated book telling all about the Brit a issue of the Britannica printed on genuine India paper. UNIS 856 sw, dn se'oe an dip Ono cones Glee tem alan ben sade ah a aS ea Cone WiRiieh cl Ce bmi ee Ss, uc °* | RF. 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ne ee eee YOU CAN QUALIFY AS A SIGNAL ENGINEER Learn at home in spare time to fill a big-pay fascina- ting iob as Signal Engineer Thedemend ts growing dally for electrically trained Sietl ann 'tekeiel. supervise and maintain signal systems and other safety devices on failroads everywhere. employment; good salaries right from the start. pe cota A YEAR! f bie Bow you Fie neta f ; absolutely FREE! Write for it 3} atonce, Ad 3] DEPARTMENT OF SIGRALING ese TREN (I Reo aceon eel aplainrabalatapetirs 100 NTS. BEL ewe ed Be ick td ia lg Ss = NE Clark Had Left His ae “Clark, everything’s up!” Clark stop short "Tn :the doorway of the bank en's when he saw the man inside. Lc a oly a threatening glint in the officer’s eye, he “This boy's got the goods on you,” said the presi- dent. on ry Speed to me ms Yes you sign safe. Clark, when you left your thumb-print there.” Of course Cla-k conf when he saw what we al- t his ae matched the one on the safe. was some time wk the finger-print course of the iveraty of Applied ence. Now I am = ere expert, in a field where men earn ween $ 000 a year. Why shouldn't you, too, enjoy the same success? Be a Finger-Print De- tective—Train at Home Get into this fascinating game now. The demand for eS -print eaperts ss Sconete the supply. This id vocation is alive with won- oa eee he is immediate. Govern- ts, corporations, police Conartsaent. ¢ institutions aaa: individuals ae constantly calling for trained rR print rts. The field is as wide as the world, the pay is big, the work is intensely interesting. No mat- ter what your Present occupation is, you can quickly to bea Aang aod print expert. Our wonderful new our name on the method trai: ou at home to fill one of the positions now going ng. Free Course in Secret Service Let us send new book explaining = course. You will and it it ‘remendously a will show just er the finger-print profession is bone you can learn it, and what our many successful stu- dents say. Also learn about our ig offer of a FREE Course in re... Service in ce. The ee two closely allied prof ns es a_ brilliant within your grasp. Act at once. Mail the spepon to-day. UNIVERSITY OF APPLIED SCIENCE Desk 9205, 1920 Sunnyside Ave., Chicago, Illinois. (eee Ft ER OR OE Ta ET REE RE RTT UNIVERSITY OF APPLIED SCIENCE Desk 9205, 1920 Sunnyside Ave., Chicago, Illinois. Gentlemen: Without ony y CuRantion whatever, send me your new FREE book Prints, and your offer of a FREE course in Soeret rvice intelligence. UND. ck 5 ch eR Caw «00s ho Chico ewen deme see ap SOOED o's y.. 5:3 CRITE Mania + «+ oo coup AD eamion a ¥eete Sa OUCRDMIR iia td «= Sionco sav ddga kate Finger} ‘Print A Receiving System for Reducing Interference OME receiving units make use of direct coupling, others static coup- ling, and still others electromagnetic coupling. The one that I have de- signed cannot be classed in any of the above. My system uses an antenna tuned to resonance. Connected to the antenna is the “balancing cir- cuit.” This, in turn, is tuned. The latter circuit draws signals from the tuned antenna circuit in a much greater proportion than static. This affords a receiving circuit which is highly desirable when static is bad. The diagram shows a ‘circuit that proved most efficient. The antenna connects through the single slide tuner to the ground. From the antenna circuit a connection is made to the balancing circuit by means of a single binding-post on the receiving cabinet. The connections are evidently the ones that are usually employed in most regenerative circuits. The tick- ler is shown coupled to the coil, which has its switch arm lead con- nected to the grid through the usual variable condenser. This insures coupling between the plate and grid circuit, and a constant feed-back ac- cording to the position of the tickler coil in relation to the larger tuning inductance. By connecting a variable condenser in series with a ground lead, as shown by the dotted lines to the filament, greater strength of signals is - ie . SINGLE SLIDE TUNER BALANCING CIRCUIT gTICKLER G FIG.1 a3 Regenerative vacuum-tube receiving circuit with circuit features that minimize interfer- ence. Note the alternative connection of the filament to the ground through a condenser experienced. However, the selectivity and elimination of static and inter- ference is lost by so doing. The antenna is tuned to a single wave-length. This has a tendency, as in all such cases, to eliminate other stations transmitting on wave-lengths near to the one being received; and likewise the secondary circuit may be either adjusted to exact resonance with the tuned antenna circuit to abstract all the energy, or it may be tuned slightly off resonance, making it possible further to eliminate interfer- ing stations.—EDWARD T. JONES. 136 Popular Science Monthly Electrician’s Wiring Manual By F. F. Sengstock, E. E. For many years Electrical Engineer of Chicago Board of Underwriters. Here is a manual that will be a friend in need when you are up against a stiff job. It will tell you exactly what to do and how to do it in strict accord- ance with the National Electrical Code. Carry It in Your Pocket This a book that every wireman, contractor and electrician should have in his pocket when on a job. Not a discussion of Code Rules, but a straight talk from a man who knows the sub- ject from A to Z and gives you the benefit of his many years’ experience. Your Work Will Pass Inspection If in doubt, this book will show you how to proceed so that your work will pass the most exacting inspector. Every step explained in detail, made clear by 415 careful — drawings. Contains many tables and formulas. 448 pages. Pocket size, flexible binding. Price, postpaid, $2.50. POPULAR SCIENCE MONTHLY 225 West 39th St., New York 10,000 WAYS to Make Money The most valuable techno-chemical formule book published, including over 10,000 selected scientific, chemi- cal, technological and practical recipes and processes is the Twentieth Century Book of Recipes, Formulas and Processes This book of 800 pages, gives thousands of recipes for the manu- facture of valuable articles for every- day use. Hints, helps, practical ideas and secret processes are revealed within its pages. It covers every branch of the useful arts and tells thousands of ways of making money. The pages are filled with matters of immeasurable, practical value to the photog- rapher, the grey the painter, the manu- facturer of glues, pastes, cements and mucilages, the physician, the druggist, the electrician, the engineer, the foundryman, the machinist, the potter, the tanner, the confectioner, ‘the chiropodist, the. manu- facturer of chemical novelties and _ toilet preparations, the dyer, the electroplater, the enameler, the engraver, the provisioner, the glass worker, the goldbeater, the watchmaker and jeweler, the ink manufacturer, the opti- cian, the farmer, the dairyman, the paper maker, the metal worker, the soap maker, the veterinary surgeon, and the technologist in os Contains an immense number of ormulas that everyone ought to have that are not found in any other work. New edi- tion. Cloth binding. Price, postpaid, $4.00. Book Dept. POPULAR SCIENCE MONTHLY 225 West 39th St., New York

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May, 1920 A Self-Closing Telegraph Key that Will Work NE of the most persistent ane noyances met with in American telegraphy has been seated in the simplest of its apparatus—the fa- miliar transmitting key. ; The Morse telegraph circuit used almost exclusively throughout the western hemisphere employs a ‘‘hook- up” that necessitates an absolutely unbroken pathway throughout its entire length for the flow of current that steadily passes along while the

This invention of John T. Brattin employs a simple spring attachable to any key line is at rest. Every telegraph key along the line has a switch that must be closed and kept closed while the key is not employed. The closing of this switch becomes second nature to the “fold head” operator; but even then he sometimes forgets to close it, while telegraphers new to the work often do so. Should a single key along a telegraph circuit be left open, the current ceases to flow and the line is dead. For a great many years inventors have attempted to produce a key, or an attachment for the present types of keys, that will close the circuit automatically, unerringly, and solidly as soon as the operator has finished transmitting. It was suggested long ago that a circuit might be wired so that the depression of the key opened the circuit. Dots and dashes in this case would pass through reversed and unreadable; but the local relay con- tacts would also be reversed, so that the station sounder would respond to a close whenever the relay tongue was released and fel! away to its “‘back’’ contact. This scheme might work if every operator along the line were a per- fect sender, and if every key spring tensioned sufficiently to insure proper action. There are different tastes in tensions among telegraphers. Many a telegrapher cannot successfully carve out a Morse character unless his key spring is so loose that during manipu- lation the back contacts barely touch. Then there appeared a self-closing key that would work if every telegra- pher held his key so that one finger TRAVE|

A WIRELESS OPERATOR LEARN WIRELESS AT HOME EARN $!25 TC $200 MONTHLY $5000 a year. This wonderful Set for learning the Code fur- nished free with our Course The Transmitter shown is the celee brated Omnigraph used by eeveral Departments of the U. S. Govern- ment and by the

Technical and and Canada. students. Ask any Inspector to verify this.

seading Universities, Colleges, Telegraph schools throughout the U.S. Start the Om- nigraph, place — bene B rkable hn Seeger pa yrs Wire~ ments so easy that anyone ambitious to enter the fast- less Messages, the same as though you were receiving them, through the air, from a Wireless Station hundreds of miles away. When you apply for your license. the U. 8. Government will test you with the Cmnigraph—the same model Omnigraph as we furnish oor 5 FREE Post-Graduate Course p t - y hd if Gores te oe & your Course, including your Free Instrument Offer f t Wireless Schools ® in N n° v7 tity, N New York—the % Wonic City— ad largest portin § __ the World and the headquarters a po Ee eee re re re ee oe of every leading Wireless and : ee © DINER, 6 0.0 0 08 08b6iceeteensenedeseceubeskeasead é tity or Town. 42) =, EY The Demand for Wireless Operators Far Exceeds the Supply The New York Wireless Institute will make you an operator—AT HOME—in your spare time—quickly, easily and thoroughly. No previous training or experience required. Our entire Home Study Course has been prepared by Mr. L. R. Krumm, Chief Radio Inspector, Bureau of Navigation, N.Y. E practical and technical knowledge to YOU in an easy to understand way, will direct your course. The graded lessons mailed you will prove so fascinating that you will be eager for the next one. The instruments furnished free, will make it as easy to learn the Code as it was to learn to talk. BIG SALARIES Wireless operators receive excellent salaries A Wireless Operator can visit all parts of ranging from $125 to $20 a month and itis the world and receive fine pay and only a stepping stone to better positions. There is practically no limit to your earning prefer a steady position without travel? power. Men who but yesterday were There will be many opportunities for you _ Wireless Operators are now holding at the numerous land stations or with the Positions as Radio Engineers, Radio In- Commercial Wireless or with the Steam- spectors, Radio Salesmen at salaries up to ship Companies.

Experts able 4o impart their All you will have to do, is to listen. TRAVEL THE WORLD OVER maintenance at the same time. Do you FREE Instruments and Text Books ° We furnish free to all students, dur- ing the course, the wonderful receiving and sending set exactly as produced in the illustration. This set is not loaned,

but GIVEN to all students com- pleting the Course. EASY PAYMENTS. A small payment down will enroll you. We will make the pay- est growing profession—Wireless—may do so. % Send for FREE Booklet Without obligating you in any way, send for our booklet “How to Become an Expert Wireless Operator’’—it js free. Mail the coupon below, or postal or letter— but do it today. SSeS ee oe ® NEW YORK WIRELESS INSTITUTE Dept. 56, 258 Broadway, N. Y. City a Send me free of charge, your booklet, ‘‘How to Become an 8 Expert Wireless Operator,”’ containing full particulars of

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copy. Set up your own Wireless Station and “‘Listen-in’’ on radio news from everywhere. Anybody can do it. Our new book, An Amateur Radio Receiving Sta- tion” tells what you need, how to get it, how to set it up and operate it. Explains wireless so everyone can understand and gives infor- mation about Radio work. Send 10 cents in stamps now and get a

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Get a Copy of Our Complete Wireless Catalog and Order All of Your RADIO MATERIAL From One Source of Supply and Save Trouble Send 25c for a copy of Wireless Manual and Catalog A 12 You cannot get satisfaction from wireless instruments unless they are absolutely perfect. The slightest imper- fection in construction destroys their effietency. We offer for sale wireless apparatus only of the highest quality, guaranteed to be mechanically and electrically perfect. Our combined Manual and Catalog illustrates and accurately describes the uses of standard radio instru- ments and should be of great assistance, not only to the amateur but to the professional user and experimenter in selecting proper radio material WE MAKE A CHARGE OF 25C FOR THIS MANUAL, ISSUING A COUPON REDEEMABLE ON AN ORDER FOR $5.00 OR MORE IT 1S THE LAST WORD IN WIRELESS CATALOGS. SEND FOR A COPY NOW. YOU CANNOT AFFORD TO BE WITHOUT ONE WHEN YOU WANT TO BUY. Manhattan Electrical Supply Company, Inc. New York, 17 Park Place St. Louis, 1106 Pine St, Chicago, 114 So. Wells St. San neon 604 Mission St,

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Do You Know How to Wire? Do you know how to do odd jobs of wiring about your house or other buildings? To make sure that your work will not affect your insurance, you should have a copy of Sengstock’s Electrician’ ~ Wiring Manual. This book is written in simple, plain English, easily understood by anyone. Pocket size, 448 pages, 415 illustrations, flexible binding. Price, postpaid, $2.50. POPULAR SCIENCE MONTHLY 225 West 39th St. New York 137

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« we ae so tance Arno arab aeiaae anette at imine ait 2 Sa ange Bim a REN EI at PS apscrpreneeieneitmemmanaty ©185~ sonar an cor 2 sp SAE nen i we sities: oD IT hs RT Spee TRE ee eae aoe THE FLORS22EIM SHOE Fl The Florsheim Shoe Co | } || the shoe have earned the |! | =| Look for the quality mark, Bil | lig) il WHEREVER you go ||| The Florsheim Shoe is known as a good shoe. | Years of dependable serv- |/5 ice have steadily spread |: Florsheim reputation and |/£ popularity—the name and jE confidence of all men who |i they pay. look for quality for what |/5) Consider the wear, not the price per pair “Florsheim.” iH CHICAGO, U. S. A. Write for book “Styles avaCUONODDAUOUOUUINNAINGHOM rt Bo of the Times’ The Moreland— Style M-4r Lil Make Your Own Electrical peperatas e It is easy to make your own at home with the aid of these 4 up-to-date books that you can understand. Each has over 72 pages and ov er 60 illustrations, 3 color cover, size 5 x 7 inches. HOME MADE ELECTRICAL APPARATUS in three parts. VOL, I, Contains-Working Draw- ings and directions for making all sorts of Static Machines, Static Apparatus, Home-Made Batteries, Storage Cells, Transformers, Recti- fiers, etc. VOL, 2, Contains Working drawings and direc. tions for all sorts of Voltmeters, Ammeters, Gal- vanometers, Switches, Rheostats, Tele raph Keys, Sounders, Telephones, Shocking oils, Spark Coils, Experiments, etc., etc. 3, Contains working drawings and direc- tions for making all sorts of Dynamos, Motors, Electric Engines, Miniature Lighting Plants, Wireless Telegra Wireless —— ments, etc., HOME MADE. TOY MOTORS gives complete details with working drawings for making 12 simple but operative electric motors. Several built from sheet “‘tin.” Others with castings. 35c peeedal. Three $1 .00 GET THEM NOW Price Advance Any Day COLE & MORGAN, Inc., Publishers, Apparatus, Tesla_ Coils, Electro-plating, Experi- papi 119, 19 Park Place, New York. incessantly covered the exact center of the key knob. Few operators do this. As indicated in the diagram, a metal pin, topped with hard rubber, protrudes slightly above the center of the key-knob. When the key is properly grasped for transmitting, finger pres- sure upon the pin opens the telegraph circuit. Now comes forward Mr. John T. Brattin, of Denver, with a patented key that is better than its predecessors. It employs a simple spring that may be attached to any key in place of the rigid switch in general use. When at rest this spring automatically closes the circuit by pressing against the lower front contact tongue. When the key is grasped for transmission, the operator’s fingers continually press the spring away from contact. Mr. Brattin’s key-closing device is receiving a thorough tryout on certain important telegraph circuits. It is a question whether the operator will not quickly tire under the constant pressure of the device against his fingers; moreover, the position of his POINTS OF CONTACT LINE SPRING LINE This self-closing key will work if the operator always presses the center pin with his finger hand while transmitting is neces- sarily restricted. The spring pres- sure cannot be weak, or the contact when the key is at rest might be im- paired.—SAMUEL W. BEACH. A Homemade Transformer for Stepping Down 110 Volts N making a transformer it is well to remember that the volts per turn, 7. €., Winding, are the same in both the primary and the secondary. If the primary has 770 turns, then for every seven turns we put on the secondary we increase the open-circuit voltage of the secondary by one volt. Of course, the voltage across each seven turns of the secondary will not be one volt when we connect a load to it, for then we shall have the drop in voltage due to the resistance (or, more strictly, the impedance) of the secondary windings. And also, when we are taking current from the secondary a larger current is flowing in the primary; so that the voltage really effective in the primary is no longer the 110 volts of the mains. The size of wire we choose, and the total number of turns (7. e., the in- ductance) of both the primary and the secondary, become of importance for this reason. The size of wire becomes of further importance when we consider how much current we wish the secondary to 138 ~ Popular Science M onthly Build This Neaudaas LEARN TO FLY! The smallest practical man- carrying flyer in the world. Designed by George D. White, America’s foremost aeronautical engineer. Wing spread 22 feet, length 14 feet, weight 210 pounds. You can build one, instail a motorcycle, cyclecar, Ford or aero motor of 16 to 30 H.P. and teach yourself to fly, 15 H.P. gives it 45 mph., 30 H.-P. gives it 80 mph. Ceiling about 12,000. Ideal for the amateur, for learn- ing to fly, for pleasure use and all sporting uses. Flight range 2 hours. Send $2 today for complete working drawings with specifications and full instructions for building, SEND $2 NOW! RAPID BLUE PRINT CO. Entire 10th Floor Grayco Building LOS ANGELES, CAL. Don’t Wear a Truss Brooks’ Appliance, the modern scientific invention, the wonderful new discovery that relieves rupture, will be sent on trial. No obnoxious springs or pads. MR. C. E. BROOKS Brooks’ Rupture Appliance Has automatic Air Cushions. Binds and draws the arenes Parts together as you would a broken limb. No salves. No lies, ~~ cheap. Sent on trial to prove {t. Protected b patents Catalog and measure blanks mailed ‘on. Send name and address today. BROOKS APPLIANCE CO., 255B State St., Marshall, Mich. Convert Your Bicycle Into a Motor-Cycle by using a Steffey Attachment. iS Fits any wheel. Easy to attach. oy AP Write at once for special low prices. ZB Za Agents wanted. Send stamp for ly circulars. STEFFEY MFG. CO. Dept. S, 5025 Brown Street, Phila., Pa. PRACTICAL BOOKS For PRACTICAL MEN 1. Automobile Troubles and How to Remedy Them. 2. Automobile Ignition, Timing and Valve Setting, Self Starting and Lighting, in- cluding Ford System. . Motor Trucks, with Special Chapters on Ford. . AB C of the Motorcycle. . Gas Engine Troubles and Installation, with Trouble Chart. . Motor Boats: Construction and Opera- tion. . . Questions and Answers for Automobile students and Mechanics. ; Gas, Gasoline, and Oil Engines, includ- ing Glossary. The price of each of these books is $1.40, Decknadlt Book Department POPULAR SCIENCE MONTHLY 225 West 39th Street New York BOUND VOLUMES OF POPULAR SCIENCE MONTHLY Each volume contains over 2000 pictures, over 1500 new articles, making a handsome big book of g60 pages. Volumes available: Vol. 88, Jan.-June, 1916; Vol. gt, July-Dec:, 1917; Vol.g2, Jan.-June, 1918; Vol. 93, July-Dec., 1918; Vol. 94, Jan.-June, 1919. Price, per volume, postpaid, $2.50. oN fo Oe OO Book Department, POPULAR SCIENCE MONTHLY 225 West 39th Street, New York ee ae oe 7 a ee... eee a ae ee, ee

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May, 1920 give; for the heating effect of the current decreases as we increase the size of wire. We must be careful to choose large enough wire to carry the current without excessive heating, which would spoil the insulation. How one amateur solved the prob- lem is told by Neil D. Cameron es follows: The core was made of 18 in. length of hay bale wire. These were bent around a cylinder of about 434 in. diameter to form them. They were eens bound tightly by strong wire into a ring, for I wished to make a Gramme ring type of transformer. Although each wire was thus closed into a ring, the ends were not allowed to touch, and the small. air-gaps of the different wires were staggered to come at different points in the core. This ring was put in a slow charcoal fire, that made it dull red, and left until the fire had died and the iron cooled. It was then tapped to knock off ashes. The binding wires were loosened, and shellac was poured through the core until each wire was thoroughly insulated. After drying, the bindings were tightened and the windings puton. During winding the binding wires were taken off one ata time. All must be removed, for they would otherwise act as short-circuited turns of a secondary winding. The core was insulated by three layers _of cotton tape. I used twill tape or scraps of cotton torn into strips about one inch wide. The primary was formed by about 800 turns of No. 24 D.C.C. magnet wire. Between successive layers of the primary \\ uc PRIMARY COIL SECONDARY COIL A Winding diagram for a homemade trans- former. The core is formed by wire. Steps 110 volts downto lower voltages there was one winding of cotton tape. After the primary winding had been applied a double thickness of cotton tape was put on, and then the secondary. Seven and a half turns of secondary cor- responded toa volt. I used No. 14 D:C.C. magnet wire and brought our taps for such | voltages as I expected to require. The tap wires were green insulated lamp- cord. When making a tap I was par- ticularly careful to make a clean soldered joint, to leave no drops of solder, and to insulate the joint well with a small piece'of friction tape. The scheme of winding is shown in the figure. I then mounted the transformer between two oak boards, bolting them together at the corners, but protecting the transformer from the bolts by slipping a piece of fiber fuse tubing over each bolt. The taps were brought out from one side and the primary lead-in wires from the other, both being terminated on clips mounted on one of the oak faces. Hiazarle , Fate Cli AN Y YY Lat m% & BK Be AS \U a ILD FLOWERS! With their breath in the air, who wants to be cooped up in town? Open the throttle of your Harley- Davidson and the whole countryside is yours. Mile-stones zip past, for you have the ‘‘World’s Champion”’ to whirl you over the roads. Open ’er up, and feel the thrill that only the motorcyclist knows. And ENDURANCE! The Harley- Davidson won every important long distance race in America during the past year. Ask Your Dealer About His Easy Payment Plan HARLEY-DAVIDSON MoTor Co. MILWAUKEE, WISCONSIN se | ft es a oe \ yy wEDaw AdhiGebee vad 0s Champion” Attach this Motor to Your Boat New pleasures are open to the man who attaches a Lockwood-Ash Row Boat Engine to his row boat. back-breaking pulls to the fishing or picnic grounds or the camp. It is simple, economical and practical and takes but a few minutes to install, and learn. about the Lockwood-Ash Motor Jackson, Mich. LIMITED) That is what gives them chances for It saves those long, hot, promotion. They start in at a good salary — $110.00 a month and expenses. The work is important, for the bo sates of whet 4 z e i~ 7 a with Company ‘ i car aes 2013 Jackson Street oaew) ® WE SECURE Standard Business wointeraencine RAILWAY FIC ‘ INSPECTORS IATE WITH BIG MEN s on their vigilanc P. is when they do their work as we -—- 1 attract iad favorable attention of ther otions then are rapid. ; Learn This Profitable Profession All you need is a common schoo! education for entrance to our three-month’s course, to learn at home during your e — time. = ake the. saiteeve poms wane Ask for our booklet ’ ema tee for Batis _——e, inepecters = We bnew of fine openings for our graduates. yr 30-day trial plan. Many who ago now hold posi OUR BOOKLET tells of this ideal vocation —out in the big out-doors—how you associate i men—how you can earn an excellent rom the nnd you OF oS COUPON _4-- your key to bow better started our course a few months itions. PON §: not start tb wy a a nonth and SUN aLD, N., Y. Please without obligation ‘our wr Booker D-96, , your uve, lc Insvector’s Course TFOOe Seer ener eseseseeeer eeeees

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arama ein ta tc rune gar mane 25 net w Sella tag eae sess 2.4m | Your Own Business and a Big income from Tire Repairing We receive hundreds of letters from enthusias- tic men all over the country who are making $2000.00 to $5000.00 a year with Vanderpool’s latest improved Tire-repairing Outfits. 28,000,000 Tires Wearing Out Every Day The field is enormous, profits are great. Motor- ists in your community would welcome the opportunity of having their tires repaired and getting extra mileage. Vanderpool’s Vulcanizer Produces More Work The Vanderpool Springs save you the work of continually tightening bolts, once set they are always on the job, holding down the tire while it settles in the ribbed-tread molds, until the vulcanizing is finished, resulting in perfect re- treads with no separation or blisters. Send for booklet which shows latest models and sizes and tells you how to make money in this rapidly in- creasing business. Write now; a day lost is money lost forever. In answering Address Dept. 7E. VANDERPOOL,VULCANIZER __ It’s easy for this fellow. Steer- ing ‘round corners and out of tight places is a feature of the Auto-Wheel Coaster and Auto- wey Wheel Convertible Roadster. These wagons develop the best motorists, with sharp eyes and keen nerves. Roller - bearings cut - under wheels; wide-sweeping steering- tongue. Built durably to give years of service. The Auto-Wheel will carry a 1,000 pound load. Two types: Auto-Wheel Coaster —for all ‘round coasting and haul- ing. Auto-Wheel * Convertible Roadster—two wagons in one, changed from box wagon to speed- ster in half a minute. FELT PENNANT FREE— Also descriptive booklet and our new magazine for boys for the names of 3 local coaster dealers. Mention _which one handles the wagon with Auto-Wheel Coaster or Auto-Wheel Convertible Road- ster on the sides. Organize an Auto- Wheel Coaster Club. Free caps to mem- bers. Special cap to captain. Get busy. ! The BuffaloSled Company 157 Schenck St., N. Tonawanda, N. Y. In Canada, Preston, Ont. HIGH SCHOOL PUPILS Earn $5.00 to $15.00 a week during after-schoolhours. Are you interested ? Then write to Popular Science Monthly 225 West 39th Street, New York Mounting Detector Crystals in Amalgam SIMPLE device for holding crys- tals for a detector may be made by the use of an amalgam, as shown in the sketch. The container may be a section of a small brass tube. How- ever, almost any metal re- ceptacle may be ultilized. An amalgam gives a good, firm contact, which is yield- ing neverthe- less to such an extent that the crystal can be turned completely around if de- sired. Tin and lead amalgams, pre- pared by mixing their filings with a few drops of mercury, are always soft and very suitable for this pur- pose.—E. STETSON. CRYSTAL , BRASS TUBE This homemade holder for the detector crys- tal permits its rotation It Produces 30,000-Voltage Direct Current MACHINE of several kilowatts capacity, that will develop 10,000 volts direct current, has long been sought. The machine here illustrated does this, and more, for it is possible to build it for voltages as high as 25,000 or 30,000 and capacities of 50 kilowatts. In the past high-voltage d.c. has been obtained only with considerable difficulty, except in quite small ca- pacities. For large capacities d.c. generators have been put in series; but, with a practical limit of some- thing like 1,500 volts per commutator, any very high potential is obtained only with considerable complication. For small capacities rectification of high-voltage a.c., by means of ther- mionic valves or by mercury-arc rectifiers, has been a common method. To some extent, particularly for X-ray work, synchronous commutators have been used. Even such cumbersome schemes as an oscillating switch, which carried a set of condensers from a parallel connection in which they were charged to a series connection in which they were used to charge the service con- densers, has been used for experimental purposes. This new high-potential d.c. machine is a develop- ment of the synchronous commutator, and consists essentially of a commu- tator driven in synchronism with a polyphase a.c. which it rectifies. The number of phases of the a.c. supply depends upon the d.c. voltage desired. In the illustration a is the syn- 140 A transformer for changing from three- to nine-phase current Popular Science Monthly She Cot of (Many Uses In the City—the Country—or the Camp— as an emergency bed in the Home when un- expected guests arrive, or in case of sickness; for occasional outings; for ‘‘outdoor”’ sleeping on porch in hot weather; for the camp or sum- mer ‘cottage—there are many uses for *‘Gold Medal’’ Folding Cots. Light, strong, comfortable; compact when folded; quickly set up and taken down. Every Family Should Have One Sold by Furniture, Hardware, Sporting Goods Dealers—and Tent-Makers—everywhere. Write for complete catalog. GOLD MEDAL CAMP FURNITURE MEG. Co. | a 1728 Packard Avenue RACINE, WIS» are (GOLD MEDAL | ( Furniture For Home and Camp } SS DisMONDS& WRITE FOR THE ROYAL CATALOG It posts you on values, prices, discounts and the way tocut out middlemen’s profits. Learn how to get a high class article at a moderate price. The Royal Catalog is filled with information about high grade Diamonds, Watches and Jewelry, and et tells how to - on charge account, g* paying monthly or weekly, as like. Liberty Bonds Acce; zed. Ask for Edition 131. It is Free! . _ ~ yr IROOVAL draMonn y WATCH Q5 MAIDEN LANE - NEW VORK Then Make Horses and Money Send 50 cents for this simple cut-out. What you can’t sell yourself we guarantee to buy. KELBO TOY COMPANY Cor. 12ist St. and Ashland Ave. Richmond Hill, L3 I. BUCHSTEIN’S FIBRE LIMB soothing to your stump— strong, cool, neat, light. . Easy payments. ‘y Braces for all ; deformi- Guaranteed 5 Years ties. Send for Catalog Today. P. BUCHSTEIN CO., 113 6th St., S., MINNEAPOLIS, MINN. swath $4 WILL BUY A Beautifully Reconstructed TYPEWRITER With Every Modern Writing Convenience WRITE TODAY FOR ILLUSTRATED CIRCULAR Explaining Try-Before-You-Buy Plan HARRY A. SMITH, 306-218 North Wells St., Chicago, ii. $10.00 FOR YOU. How would you like to make $10.00a week during your spare time? Others are doing it by representing POPULAR SCIENCE MONTHLY. Why not you? POPULAR SCIENCE MONTHLY, 225 Wesi 39th Street, N.Y.C. reais Ma: chr ext 1S the era tra to eX] us lez ao ms PL = lt

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May, 1920 chronous commutator carried on. an extension of the shaft of the three- phase generator b. The generator b is driven, in this case, by a d.c. motor housed in the same frame as the a.c. generator. From the gen- erator three-phase is carried to the transformer. Here it is stepped up to the necessary voltage, as already explained, and at the same time changed from three to the number of phases desired. In most cases nine is used. From the transformer the leads are carried to the synchronous commutator a, where the rectification takes place. The high-potential d.c. is then taken off at the ends of the commutator. It is not essential that the commuta- tor be carried by the a.c. generator. It may be carried by a synchronous The synchronous commutator for nine- phase alternating current shown on the tight is driven by a three-phase motor motor which takes its energy from the a.c. supply to the transformer. The arrangement shown is one that makes a variation of the d.c. voltage simple and easy, since it is necessary only to change the field excitation of the generator. This machine will doubt- less find a large field of use, par- ticularly in radio and experimental service.—MILTON KENT. Radio Transmission Is Best in Winter HOSE radio operators who have had years of experience know how markedly the transmission efficiency of the ether varies from time to time. Some years ago Dr. L. W. Austin, work- ing with the United States Navy and the Bureau of Standards, made a series of tests on transmission under different weather conditions. The familiar “fading” effect of signals seems +o be characteristic of summer months. Not only is trans- mission usually best in the winter months, but atmospheric disturbances are small. It is in these months that new records of distance are usually made. The last record seems to be held by R..F. Gowen, of the De Forest Radio Company, who has been sending speech a distance of nine hundred miles, from Ossining, N. Y., to Chicago. He uses a wave-length of 375 meters, and puts about one third of a kilowatt in his antenna.. With good vacuum-tube receiving sets and amplifiers, it looks as if the only limit to such records were static interference and such ether effects as ‘‘fading.” STEEL BOATS CANT SINK seams. Mullins steel boats never need calking—no boat house required. Powered with the best marine engines, equip- ped with Mullins patented silent under water exhaust. Designed .by America’s fore- most naval architects; made in world’s largest boat factory. More than 70,000 in use. of over 40 models, steel and its, “rowboats and canoes. MGB. It’s all pleasure and no risk when you have a Mullins steel boat. These boats simply can’t sink -because they’re built with air-tight compart- — fore and aft, like a life- t. The strong steel hull—equal to one-inch planking—can’t leak, warp, waterlog or open at the Write for ca wooden power THE MULLINS BODY CORPORATION 619 Franklin St. Boat Dept. SALEM, OHIO Form a canoe club. We will furnish constitutions and by- laws. You can pick a fleet of “Old Town Canoes”’ from the new 1920 catalog. Thirteen graceful models pictured in nat- ural colors. Complete list of ac- cessories. All prices given. First cost is the last—there is no up- keep to an ‘‘Old Town’’. Write for free, postpaid catalog today. OLD TOWN CANOE CO. 1995 Main Street Old Town, Maine, U.S. A. Patch All Leaks With Hercules Cold Soder The metal mender Squeeze the semi-liquid metal mender of tube, cover hole, allow Hercules Cold Soder to harden. That’s all. No heat or acid necessary, Mends leaks, holes or cracks in auto radi- tors, cylinders, steam, gas, water pipes and all household utensils. Mends any metal even brass, aluminum and graniteware. Tightens pipe joints. HERCULES PRODUCTS COMPANY COUNCIL BLUFFS, IOWA A and 26th Ave. FOR END 25 HERCULES .COLD SODE= w® MENDS ANY LEAX In METAL’ E FREE How to Write Master Letters A wonderful 52 page book that explains the short cut to big pay. Quick self-advancement for every am- bitious man and woman. A new easy method of Suc- cessful Letter Writing, by E. B. Davison (famous as Ad-man Davison), the highest paid letter writer in the world. This book explains a new Self-Teaching System that puts Swift Success within your grasp! How letter writing provides endless new Opportunities; how it gives you a new force, a new money- making power; how to sell your services for the highest price; how to make up the other man’s mind; how to attract, how to interest, how to convince him; how to step up from clerk to executive; how to become a business-getter. The moment you can write good business letters you are an important factor in any business; a better salary awaits, you; a Bigger Future is yours! This 52-page book, “How to rite Master Letters,” is absolutely free. No obligation. Write for your copy today. ust address Opportunity Press, _ Seat. C1® Carcagd 786 Sixth Ave., New | ve., New York. “THERE'S TIONEVINIT TELEGRAPH Yair _.. — —_ MORSE AND WIRELESS—-—-— 4 ee ee om ee eee we ee eee eee ee ee ee ee TEACH YOURSELF 'i2tey.ine. ti TH8 SuaiGnsen Senda , ‘ untied Morse 13 beg messages, “ot ‘my 8 ed , just as an expert operator yould. age pted b ¥ Lt Sov and leading Schools. a ctylen. ‘og free. Ualversities, Colleges ond Telegraph OMNIGRAPH. MFG. CO., Dept. H., 39 Cortlandt St., New York,

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This FREE Book tells how you can get cash for your property by using the Simplex Plans for selling Real Estate, which have already sold more than 5,000 properties of all kinds in the U.S. and Canada. No matter where your property is located, these successful plans will show you how to sell it yourself, without employing agents or paying commissions to any one. Don’t spend a minute's time, an ounce of effort or a cent of money grying to sell without first reading this important book, and yearning how to sell your property quickly, economically and at the highest possible price. The reading of this book has saved property owners hundreds and thousands of dollars im commissions, and it can do the same for you. As ‘ the book is sent absolutely Quick Results! free, you have everything to gain and nothing to lose. “Sold my house within | Send your name and ad- two weeks by following | ‘tess at once—a postal will the Simplex Plans.”—F. lift — will eg > re. 8te y return mail, postpaid, a Stork, Wis. “Sold for cash | copy of this important in 10 days."— W. H. Cart- | ; : Sond, Mass. “Bed any guen- book, without cost or obli- erty. Your plan quickést I ane ever saw.”"’"—Johnson String, N. J. ‘Sold my home for cash within three weeks.”"— The Si | ¢ M. E. Lounsberry, Okla. Imp. ex 0. “Sold my lots for cash.’’"— R. P. Moodie, Ottawa, Can. D ; “Sold for cash within a few ot 238 weeks.” —M. P. Jones,lowa. 1123 Broadway New York FREE Bargain Book Contains many pictures of thi 0 want at remarkably low salons, A tom are shown below. | Write today for this n and your name will be put or our special mailing list. Hunting and Fishing Knife 60¢ Strong serviceable knife for camp- ing, hunting, fishing and out-door work. Strong 5 1-2 inch steel blade, ebonized handle and genuine leather sheath with belt loop. ited supply at 60c, Handy Stite Awl 69¢ For stitching leather goods, repair- | ing boots and shoes, tents, sails, and tough material. A wonder for speed and efficiency. Only a few left at 69c. Vest Pocket Flashlight ic A powerful light but small enough to fit in your vest pocket or a lady’s hand bag, Bright nickel case. Complete Rowe and two-cell battery. A bargain Cc. Combination Pocket Screw Driver 35 te Great for sportsmen. Use on guns, fish- ing tackle, traps and tools. Equipped with well made interchangeable driver in three sizes. Only 35c. Everyman’s Pocket Hone 35e Agenuine Black Diamond hone. Puts a lasting razor edge on any good knife. Also hones razors, Fits in your vest pocket. , Finest material, 35c. A Write for this Free Bargain Bosk today when ordering Remit by coin, currency or money order. Money back ¢f not satisfied. BALTIMORE MAIL ORDER COMPANY Baltimore and Howard Streets Dept. 140 BALTIMORE, MD. xEnsel _ Aysxt Corners’| Milli rr ye |B Billions, Sy iSE.No Paste NEEDED fe Us them to mount all kodak Hf D pictures, post cards,clippings m albums in Square, Round, Oval, cy Heart . ° oe ee Sa r. : Slip them on corners of pictures, then wet and stick. . QUICK-EASY-ARTISTIC, No muss, no fuss. At photo 4; supply, drug and stat’y stores. Accept no substitutes; 3 there is nothing as good. 10c brings full pke. and samples rom Engel Mfg. Co. Dept. 62-6 1456 Leland Ave., CHICAGO SIMPLE WIRELESS TELEPHONES AND HOW TO MAKE THEM. An elemental book on the principles, con- struction and use of an arc system of wireless telephony. illustrated. Price, postpaid, 25 cents POPULAR SCIENCE MONTHLY 225 West 39th Street New York Amateurs, Do You Protect Your Supply Mains? ERE is a method of protecting the supply mains, The spark-gap is made of three terminals, each with a 3/16-in. hole through it, set on a slate base. The points are made of three pieces of 3/16-. in. brass rod, pointed sharply and adjusted very closely. The 16-c.p. USE NOV.AG MAINS 16 CPC. LAMP SEC. 20.000 VOLTS FUSE == ~~ SENDING KEY SV. = TRANSFORMER This is the circuit one amateur is using to protect the 110-volt mains that supply his spark-transmitter lamp is connected on one side to the grounded side of the main. Which is the grounded side may be determined by trying the connection of a 100-volt lamp between a water-pipe and a line wire. When the apparatus is in use the S.P.S.T. switch is thrown in. If it is undesirable to have the lamp glowing, it may be painted with stovepipeenamel.—NEIL D. CAMERON. Bells Controlled by Radio for Ships in Distress ABLEGRAMS from London tell of developments promising that ships in distress may be able to ring alarm bells on other ships within about three hundred miles—that is, near enough to be effective in offering aid. No details are given, but prob- ably the usual receiving set is altered only by the inclusion of a sensitive relay instead of the head telephones. Such relays may be hot-wire instru- ments or ordinary electromagnetic relays like those used in wire tele- graphy, since the detector supplies a rectified current. But they must be more sensitive than the ordinary telegraph relay, since they must operate on very feeble currents. Where the difficulty tomes in to all such methods of a remote control by radio is the possibility of a really sensitive device giving false signals due to atmospheric disturb- ances or to transmission from near-by stations having a poor decrement, and thus affecting stations with which they are not supposed to be in tune. For amateurs who live near each other and have fairly powerful trans- mitters, it should be easy to adjust a relay to ring a bell at the will of the operator at the distant station. But don’t be surprised if it rings falsely sometimes; for you know that this same principle is used by electric- light power plants and the like to detect the approach of lightning storms. 142 Popular Science M onthly BOOKS THAT WIN Help yourself up the ladder to Better Pay by becoming more efficient. The easiest way to do this is to buy and study these helpful books. CONSTRUCTION OF SMALL ALTER- NATING CURRENT MOTORS. By A.E. Watson. This book contains complete in- structions for building small alternating cur- rent motors in several sizes. The designs will be found in harmony with those of the very best manufacturers and they can be worked out by the amateur for making useful instru- ments. Fully illustrated. Price, $1.25, Postpaid. AUTOMOBILE REPAIRING MADE EASY. By Victor W. PacE, A thoroughly practical book containing complete directions for making repairs to all parts of the motor car mechanism. Written in a thorough but non- technical manner. This book contains special instructions on Tire repairing and rebuilding. Latest timing practice. Ejight-“and twelve- cylinder motors, etc., ete. You will never ““get stuck’’ on a job if you own this book. 1,000 specially made engravings on 500 plates. 1,056 pages. 11 folding plates. Price $4.00, Postpaid. SHEET METAL WORK. By WILLIAM NEUBECKER. A manual of practical self-in- struction in the art of pattern drafting and construction work in light and _ heavy- gauge metal, including skylights and roofing, cornice work, etc. Cloth, 288 pages, 370 illus trations. Price, 2,00, Postpaid- MENSURATION FOR SHEET METAL’ WORKERS. By W. NEUBECKER. Price, $1.10, Postpaid. MACHINE SHOP WORK. By FREDER- 1cK W. TURNER, OscaR E. PERRIGO and H. P. FAIRFIELD. Acomprehensive guide to the most approved methods in modern shop prac- tice, including the construction and use of im- proved tools and machines, and other details of shop equipment and management. The use of various hand tools is explained, followed by a comprehensive discussion of the lathe and lathe tools, with the methods of screw cutting, taper and eccentric turning, etc. In- dex. Leather, 275 pages, 325 illustrations. Price, $2.25, Postpaid. STANDARD PRACTICAL PLUMBING. By R. M. StarsBuck. This is a complete treatise and covers the subject of modern plumbing in all its branches. It treats ex- haustively on the skilled work of the plumber and the theory underlying plumbing devices and operations, and commends itself at once *to everyone working in any branch of the plumbing trade. A large amount of space is devoted toa very complete and practical treat- ment of the subjects of hot water supply, cir- culation and range boiler work. Cloth, 406 pages. 347 illustrations. Price, $3,50, Postpaid. Book Dept., Popular Science Monthly 225 West 39th St., New York City

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May, 1920 How to Construct a Dry-Cell | from Tinfoil ERY satisfactory dry-cells may be made by using the various parts of worn-out cells. The advice given here is intended only if the zinc coverings are so worn out as to be useless. The graphite-manganese di- oxide filling, carbon rod, and binding- screws should be saved. Before be- ginning to make up the new celis, spread the graphite mixture out to dry. Select a strong tubular cardboard box, such as certain breakfast cereals come in, to be used for a container. Next, line the bottom and sides of this box with a triple layer of fairly heavy tinfoil to within about 1% in. of the top of the box. This tinfoil forms the negative element of the cell, instead of the zinc more com- monly used. Two pieces of tinfoil, each about 1 in. by 2 in., should then be placed 1 in. between the three layers of tinfoil, to act as coatings between the coatings and the binding- screw. Cut out two circular pieces of blotting paper to fit into the bottom of the box over the tinfoil. Cut two more pieces of blotting paper, about ¥g in. longer than the box, to fit around the sides of the box. The extra 14 in. should be bent under so as to fit over the bottom, leaving the paper 1 in. over the top of the tin- foil. This extra inch is to be bent over after the filling has been put in. Put two more pieces of blotting paper in the bottom, so as to make a complete cell of paper through which none of the filling can touch the tinfoil. By this time the graphite-manga- nese dioxide filling should be dry. The manganese dioxide, which acts as a depolarizer, is probably pretty well exhausted of its oxygen. To re- oxidize it, it should be placed in a stout pan and heated over a gentle flame to about 400° F. Do not let it become red-hot, because the little oxygen left would thereby be driven off. Stir the mixture thoroughly while heating. Spread it out to cool. While this is going on a saturated solution of sal-ammoniac should be prepared. This is the exciting solu- tion for the cell. Pour enough of this solution into the cell to thor- oughly saturate the paper lining. The surplus should be saved for future use. Then turn the cell upside down to drain off the little solution re- maining. This should take about twenty minutes, as the proper degree of moisture is important if the cell is to be a success. While draining, the filling can be made up. Mix enough of the graphite- manganese dioxide with some of the sal-ammoniac solution, so that when made into a ball it will not fall apart if taken into the hand. The proper consistency is important, since the amperage depends a good deal upon it. Heat the carbon rod on the The Johnson Twin will take you where you want to go when you want to go THE JOHNSON Motor WHEEL The only two-cylinder motor in the world to push a bicycle Make your bicycle into a two-cylinder Motor Bike, by replacin the rear bicycle wheel with a twin-cylinder Johnson Motor Wheel. Consists of flat twin-cylinder motor, extra strong 26-inch wheel, two-inch motor fabric clincher tire, patented shock absorbing driving sprocket, magneto and electric light generator. JOHNSON MOTOR WHEEL CO. 906 EAST SAMPLE STREET Travel 150 miles on a gallon of gasoline 60 miles for 10 cents Johnson Motor Wheel, $97.50. SOUTH BEND, INDIANA Speed 6to38 miles an hour Johnson Motor Bike, $140, F. 0. B. Factory, plus war tax Learn to Dance! You can dances in your learn Fox-Trot, Step, Two-S Waltz and latest ‘‘up-to-the-minute”’ societ: by the wond One- own home by th Peak System of Mail Instruction. New Di: BO music 3 Write for § for FREE inf t yo and surprisingly ~~ Room 100, 82) Crescent Place Chleage, ile Methes. = aA oday Terms. “Lighting Fixtures” Ready to hang. Direct from manufacturers. Completely wired including glass- ware. Send for new No. 18 catalogue. ERIE FIXTURE SUPPLY CO. Desk A, Erie, Pa. FREE 6000 Mile Guarantee UNION TIRES ard in reconstructed tires. Th reinforcement of 4 extra layers of fabric a : dies oe cee : with every PUNCTURE PROOF TUBE FREE >] that under ordinary conditionswill last ten to 20,000 miles. Our 5,000-mile tire certificate with every tire. reduces ntee Tire and Tube of practical | ‘nglish, has perfectei a new eugene cnehete oe $12.00 patented invention which in 15 minutes ow Tae "950 | $8x4i6 .....- 12.60 of your daily spare time, will quickly pos EE 9.10 | $4x434 ...... 18.15 givc you unusual command of language. Bnd 10.86 | B6x4%5 «ss. 18.40 Students of this “100% Self-Correcting 0x4 ones 10.70 | 36x44 ...... 13.85 Method”. secured more improvement in 3x4 Roosees 11.15 |86x5....-. 14.85 five weeks than had previously been ob- Bixd | ..11.60 1875 5... . 14.96 tained by other pupils in two years. 15 ii de Free With minutes each oy of YOUR spare time Reliner nt cide or clincher can now through Sherwin Cody make you wan ° you speak or write clearly, forcefully, correctly, and .O0.D., sub Sinsant i? full amount is sent UN Dept. 90 o@ Sa 9-1 KENNEBEC CANOES—Safest to Use The superiority of the KENNEBEC CANOE is due primarily to an ideal—the aim of the makers to create a new and higher standard in canoe building. Write for the Free Book today. Kennehec Boat and Canoe Co. RR. 8q., Waterville. Maine, 29R R h order. ER COMPANY peteog oe & 15th Gt, Chicago Puncture roof TUBE tly blow: ities. Over 200,000 in ln 15 Minutes a Day Sherwin Cody, the well-known teacher represent the highest stand- eir out and age, W@ yy convincingly. **100% Self-Correcting Course’’ The average person in business is only 61% efficient in the vital points of English grammar. That is cause the methods of teaching English in school ‘eft the student only a hazy idea - the subject—the ‘rules’ did not stick in his mind. But Sherwin Cody's new invention upsets all old standards of teaching English. And it overcomes the only weak point in instruction-by-mail. It actually takes the lac> f an instructor at your elbow. It assigns you lessons +4 tter Writing, Spelling, Punctuation, Reading and Conversation. corrects them for you @nd anticipates your questions. It even guides your paper and assi ns you your Percentage till you reach the 100%, mark. Interesting Free Booklet Mr. Cody has written ‘an { t explaining his new course in detail” if you feel pour fack ef Language Power, if you are ever embarrassed by mistakes in grammar. spelling or punctuation, if t words Science Monthly. Popular Science Monthly 225 West 39th Street, New York $25 FOR YOU a You can earn $25 or more a week in your spare time collecting new and renewal subscriptions for Popular Write to-day. 143 command the t, correc express your ideas thie booklet will “3 revelation to you. Send for it now. rwin comman: makes 2 Ph hy A ly spare time. Maile - BRAT RK. thie booklet at onee. SHERWIN CODY SCHOOL OF ENGLISH Dept. 185, News Building, Rochester, N. Y. al

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Man-power in Fuller Play By machines you make men more productive, up to the limit of average industri- ousness—and there the power of the machine stops. Veeder Counters intrude on that average industriousness with records of output (showing the actual and possible), urging on the operator to records nearer his capacity. Machines then are run with a real objective—a man’s size goal of production where COUNTERS break the spell of a routine rate rate of work. The small Revolution Counter below registers one for a revolution of a shaft, recording a machine operation. Though small, this counter is very durable;. its mechanism will stand a very high rate of speed, making it especially suitable for light, fast-run- ning machines, and most adaptable to experimental work. If run backward, the counter sub- tracts. Price, $2.00 (Cut nearly full size.) The Set-Back Rotary Ratchet Coun- ter below is for larger machines, such as punch presses and metal-stamping machines, where a reciprocating movement indicates an operation. Registers one for each throw of the lever, and sets back to zero from any figure by turning knob once round. Supplied with from four to ten figure-wheels, as required. Price with four figures, as illustrated, $10.50 (subject to discount). Cut less than 14 size. There’s a Veeder for every purpose where you could pos- sibly use a counter. Write for the new counter booklet. The Veeder Mfg. Co., 44 Sargeant St., Hartford, Conn. bottom and sides to get rid of any foreign substance that may have adhered to it. When the cell has drained properly put some ‘of the mixture in it, packing it well. When enough has been put in to bring the top of the carbon rod above the top of the cell, adjust the rod centrally and pack the mixture around it. The more compact it is, the higher will be the amperage of the finished cell. In packing, use a thick piece of wood, with a mallet as a hammer. Tap the carbon rod_ occasionally with the mallet. This is done to keep the rod in position, since the tendency is for it to rise. When all of the mixture is in the cell, fold the extra inch of blotting paper over and slip two other pieces of blotting paper over the rod, to complete the paper lining. Be carefui that none of the mixture comes in contact with the tinfoil, since this would ruin the cell by short-circuiting it. Pour melted paraffine to the depth of 14 in. around the rod to seal the cell. Also cover the sides and bottom of the cell with melted paraffine. Put binding- posts through the carbon rod and through the tinfoil connector, and then set the cell in a cool place for the paraffine to harden. The cell can then be used the same as any other dry-cell.—PauL F. KNAUS. To Make a Water-Tight Joint for Buildings NE method of making a water- tight joint between the brick wall cement Ofabuilding and stayvsotr aside roof of cor- rugated iron con- sists of a wooden support for ce- ment. This is set over the edge of the roof, and causes the rain to jump the leak and come down . on the roof One way to repair a past it. leaky joint is to bolt x . a cement repair over it , The idea is simple, economi- cal, and can be used in a variety of ways.—Roy H. Poston. Here’s a Good Substitute for Frosted Glass LL kinds of glass are scarce on the markets, and frosted glass is particularly hard to get now. A makeshift substitute that isn’t bad at all, if properly applied, consists in brushing on the plain glass a coat of ordinary flat wall paint, afterward stippling it with a stiff brush to give it a uniform appearence and eliminate the brush marks. In factories and other places that do not call for de luxe appointments, this painting of windows in place of frosted glass will answer for perma- nent use and save considerable poeney 144 Popular Science Monthly Big Profits in ) Vulcanizing Little Capital Needed a Let us help you sta:din this profitable business an be independent. Many of our graduates make $3,000 a year and over. We manufacture the Ander- son steam vulcanizer and the Anderson re-treader and teach ou. the Famous’ Anderson ethod of vulcanizing. With an Anderson you can get the cream of the business regardless of competition because you can guarantee the work to outlast the remainder of the tire. We can show you that the Anderson machine and method does superior work at a cost of less than 10 per cent of that required for all other vulcanizers. This means satisfied customers and bigger profits. We have established Anderson vulcanizing schools in thirty states for teaching the Anderson Method. The course requires 5 to 10 days and costs $20. If you buy an Anderson vulcanizer we not only return your $20 but pay you $2 per day expense money while you are learning. We expect Anderson vulcanizers to do first class work and expect our students to make good in a business way. Their success is our success. Therefore we do not sell an Anderson vulcanizer to any one who has not received our course of instructions. It costs you nothing to investigate this wonderful oppor- tunity. Write today for full particulars and address of ve school nearest you. Print your name to avoid mistakes. ANDERSON STEAM VULCANIZER CO. Indianapolis, Indiana The Midget Slide Rule will instantly add, subtract, multiply and divide ejher whole numbers, dec- imals, fractiéns or mixed numbers. It Dow. ers, Sines, Tangents and Logs. The most versatile calculatoreverinvented. Made of Metal. Size 4'’. Price with Instruction Book, $1.50. Satisfaction guaranteed. nd for our Catalorue and Instructions in Logarithms and igonometry. Gilson Slide Rule Co. Niles, Mich. TOOL CASES Machinists and Toolmakers Write for our booklet showing the best built and most practical selec- ion of Tool Cases on the market. We ship direct from factory and guarantee to please you or refund all money. AMGerslacr tent. GO Columbia St... Dayton. Ohio STAR STORAGE BATTER'ES More Dependable Lower in Price The BEST Guarantee Liberal discounts to dealers; write for particulars THE STAR STORAGE BATTERY COMPANY Manufacturers of Automobile Starting and Lighting Batteries MUNCIE. IND. U.S. A, | Small Steam Engines and Boilers A Gas and Gasoline Engines, Zz | » +H. P. up; Tanks, Pumps, we Gears Model Makers’ Supplies ——~ , GetOur Big Catalogue sent postpaid for lic (coin preferred) or stamps. Refunded first order. 192 Pages— Over 200 Illustrations. MODERN ENGINE & SU L Ss Y co. 344 Monadnock Block, CHICAGO 200,000 in Use Mostly sold through recommendation It checks meatalcalculations, he Buy through your stationer, Weitefor 10-day TrialQiier |i P. E. Gancher, A. A. 3. Co. | 148 Duane St., New York (J Canadian | ANZ musical instroment eent for @ trial with complete musical outfit, ease, music, ge! Have'a free trial. N to buy. Ses d for Free ay All musical instruments illustrated, Full cll Satin a fel ean bar ae eet St., Cincinnati or S.Wabash Ave., nr. A book of 400 The Boy Craftsman. >, PK oi n°a5" onty explains how to make things, but also gives many sug- gestions as to how a boy canearn money. Price, post- paid, $2.25. Popular Science Monthly, 225 West 39th Street, New York.

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May, 1920

Electricians’ Knife Scissors and Tweezers We can meet dealers’ demands at once and offer attractive quantity prices Write for description MATHIAS KLEIN & SONS, Mfrs. CANAL STA. 3, CHICAGO

BieProfits ii withthe HB 52-Battery Charger Start Your Better es Business Lo sfaaneeeaed $150 to ery Mon’ NOW is your o ~ A Make 3150 to $350 Clear Profit Pont i month with Wy, HB Charger. Rec Ff 6-volt batteries, or equivalent, at one time. Cost > pee es Owner f Deve? 75c to 50. F BIG? PROFITS. ond. build Othe rmanent pumacen. rs are doln it— you Smah Ca Soe Payment @ Brings You

Por ful fall '9 ion. posant BROTHERS COMPANY “Succesaful Mfrs. Taos — es ae ELIABLE, STANDARD FOR YEARS PIONEERS IN THE NOTEWORTHY IMPROVEMENTS Stocked by Deal aun Sees ter Catalog No. 12. 87 One Man < Saws 25 Cords a Day The Ottawa Log Saw does the work often men. Makes wood sawing easy and profitable. When not sawing wood use for pumping, feed pans. se. Simple, economical, Curette Thousandsin use guaranteed; 30 days Write at once for Free Sook and low price, OTTAWA MFG. CO.., 1801 Woed St., Ottawa,Kas.

Battery Charging

Pilliod _ TOOL CASES EXCEL Machinists, Tool Makers and Carpenters’ find them most satisfactory in construction,

Dept. A, Swanton, Ohio Removing a Cork from the Inside of a Bottle HILE the glass bottle is not so popular as it was a year ago, it still has some uses. It often happens that a cork, that you are trying to POSITION OF "ago ALMOST

The next time a cork gets inside of a bottle, try this method of removing it remove from its neck, is accidentally pushed down into its interior. An easy way to remove this cork is to take a double piece of twine, tie a large double knot on one end, and lower it into the bottle. The. next operation is that of tilting the bottle, so that the cork falls in line with its neck end apon the string. The string is then pulled until the knot engages between the cork and the neck of the bottle (Fig.1). Another pull and it’s out (Fig. 2)—M. TocaBEN. Carry a Button-Hook When You Go Motoring Did you know that a button-hook is a very useful thing to keep in your automobile? With it you can locate and pull out small parts that fall into the mud-pan or inside the engine; and for the pull- ing out of cotter-pins it is the very best tool that could be used, for the hook seems to be made for the express purpose of catching hold of the looped end of the cotter-pin. How to Turn a Ball on the End of a Rod QUICK way to turn a ball on the end of a rod—as, for instance, in making ball handles for machine tools—is to take a pipe the inside diameter of which is some- what less than that of the de- sired ball, and grind it, leav- ing a keen edge. Cyanide hardening com- pletes the tool. Put a tool- shank in the tool-post for a rest, and use the pipe as a hand tool, giving it a twisting motion that can be made to cut a smooth shaving from the ball. Before using the tool, the ball should be brought approximately to

Turning a ball on the end of a rod is not easy unless you know how

shape. 145

SIMONDS HAND SAWS

HY do hundreds of thousands of car- penters use SIMONDS Saws ? Because they know the balance, size, weight and edge of a SIMONDS Saw is exactly right for its in- tended service. SIMONDS Saw steei con- tains the finest alloys the world produces. The blades are ground closer to gauge and have EDGE- HOLDING qualities un- equaled in other saws. Every saw bearing the SIMONDS trade mark is Suaranteed Simonds Manufacturing Co. Fitchburg, Mass. “The Saw Makers,’’ Established 1832 CHICAGO, ILL. VANCOUVER, B. C, NEw YORK CITY LONDON, ENG. PORTLAND, ORE. MONTREAL, QUE. Lockport, N. Y. MEMPHIS, TENN. NEW ORLEANS, LA. SEATTLE, WASH. SAN FRANCISCO, CAL. ST. JOHN, N.B (SIMONDS

SAW STEEL |] PRODUCTS;

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vos gen eae rah geeeer rset STANLEY IMPROVED LEVELING STANDS A Stanley Leveling Stand, used in connection with a wood or iron level, and a pair of level sights will be found in many cases a very satisfactory and inexpensive substitute for the more ex- pensive surveyor’s instru- ments. By its use one can read- ily determine levels from a given point to one at a dis- tance, such as locating or setting the profiles for foun- dation work, ascertaining the proper grades for drains, ditches, etc. It can be placed ona stake or crowbar and adjusted to a horizontal position, even though the stake or crow- bar may not be exactly perpendicular. As now made it can readi- ly be attached to a tripod. STANLEY Rute & Lever Co. New Britain. Conn. U.S.A. Popular Science Monthly, Harnessing the Summer Zephyr How to make a windmill that will operate light machinery By Thorton Hallett REQUENTLY a small amount of power is wanted to operate very light machinery, toys, fans, etc., and no power is at hand except the wind. This, however, can be harnessed to do the work if the amateur mechanic will only gather together a few tools and You can rig up an arrangement and put the wind to work. You will be surprised at the amount of labor it will do utilize the cast-off things about his bench. The little windmill shown here is not intended for speedy work, but will give a fairly steady power when the wind is anywhere near fixed velocity. The base of the windmill is a wooden disk about two feet in diameter. Mount six spokes around its center, equal distances apart as shown, and bolt them to the top of the disk with three carriage bolts apiece. Each spoke is 31% ft. long, measuring from the certer of the disk. This makes the spread from opposite spoke ends approximately 7 ft. Bolt an upright to each spoke end 18 in. long, as illustrated, and secure with a wire stay fastened to each end and passing through a hole in the spoke. Next, make six sails. This is done by constructing a light wooden frame and covering with tightly stretched canvas. They can be made in the shape shown or oblong, as desired. Oil the canvas with boiled linseed oil to protect it from the weather. Secure the sails to the uprights on the ends of the spokes with stout hinges, top and bottom, so the sails will all swing in the same direction. : Bolt a pipe-flange to the center of the under side of the disk, and thread 146 a suitable length of small straight pipe into it for a shaft. Keep it from un- threading with a set-screw. Have this shaft long enough to reach down to the top of the window and keep the sails a foot or two above the roof. : Drive a suitable bevel gear on the lowe. end, and mesh it with another at right angles attached to the drive- shaft in the room. Cap the pipe over each gear, and thread in a plug that has been filed round and smooth. These set and revolve in greased ‘\ sockets in a heavy oak block fastened fi to the side of the house in the proper fh position to line the shafts up in a true vertical and horizontal position. A second bearing should be fitted to the vertical shaft at the peak of the roof. Make this of a section of larger pipe held in position with strap-iron riveted to it and bolted to the build- ing. A collar below it prevents the shaft from rising and pulling the gears out of mesh. Set up all threads with set-screws and thoroughly oil any parts of the work exposed to the weather. Use as light parts as_ possible throughout, to insure easy working, but do not sacrifice strength. If properly made the windmill will surprise one with the many things it will do. With a little ingenuity the revolving shaft can be attached to numerous small things, such as the butter-churn, the cream-whipper, etc. S > SPOKE SAIL | ‘ FRAME _— = L WIRE STAY DISK FLANGE | SHAFT UPRIGHT C COLLAR BEARING STRAP ~ iPON PIPE SHAFT BEARING DETAIL OF TOP GEAR BLOCK BEARING 1 ' he SHAFT PIPE an CAPs FILED ROUND TO FIT IN SOCKET =] SOCKETS i— SHOWING ACTION OF HINGED SAILS IN WIND DETAIL OF = SPOKES j BOLTED TO TOP OF WOODEN DISK Made from cast-off things about the housé, this small but efficient windmill can be made to do a variety of odd jobs

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May, 1920 Turn on the Light with the Power ACHINES operated by indi- vidual electric motors can be automatically illuminated when the current is turned on to operate the | | a SWITCH LIGHT OVER MACHINE 6 [I lat b MOTOR BELTED | LIGHT WIRES TO MACHINE BELOW SWITCH| | BENEATH LIGHT ] Why make two operations of turning on the light and power machine? This dual switch does both with one movement machine by the simple wiring method illustrated above. A knife-switch is used to control the current, and is wired directly to the motor or rheostat. Then, below the switch or between it and the motor, | connect in wires to the light as} shown. These should be between the j motor and switch in order that the light shall work at the same time the motor is started; otherwise the lighting will not be automatic and must be operated by a _ separate switch. This is a simple idea, but will be found a time-saver to the machinist who has two switches where only one is needed.— WINDSOR CROWELL. An Improvement on the Old-Style Oil-Gage N large generators and other ma- chines made several years ago, the bearings had exposed and unprotected gage-glasses to show the oil level. These gages constantly invite danger of a shut-down, owing to breakage of the glasses and consequently a burned bearing. There is little advantage in having an 8-in. or 10-in. glass to indicate the oil level. A brass pipe having a small opening at one side of the proper level of the oil, with a short piece of gage- glass cemented inside the pipe at the ——_~~ SM 5 oR 10 a GAGE GLASS BRASS PIPE: WITH OPENING SIDE OF BEARING ——— Don’t wait for your engine bearings to be burned out. Make this gage tell you for a certainty that the oil is low opening, is preferable. This will show the correct height of oil to be main- ‘The apprentice. for Catalog No. 21° toolmaker says: ‘Yes, I’ve got quite a num- ber. No more, probably, than most toolmakers, but quite a number just the same. But then, I ought to have a lot of "em. I’ve been buying Star- rett Tools ever since I was an **You know my work calls for pretty close limits, and some way or other I’ve got a feeling of confidence in Starrett Tools that makes it easier for me to do good work. ‘‘When did I get my first Starrett Toul? Oh, somewhere back in the 80’s. In fact, it must have been pretty soon after the Starrett factory started. There’s one thing that al- ways impressed me. Right from the start, Starrett Tools have been designed and made by men who knew machine shop ‘practice You know, practical men. And somehow it shows in the quality of the tools,” The L. S. STARRETT COMPANY THE WORLD'S GREATEST TOOLMAKERS Manufacturers of Hack Saws Unexcelled ATHOL, MASS. Accuracy, utility, and quality are built into every te: Tool. Write 42-988 Single Phase —_ * 220 volts, A. C., 60 cycle, 800 R. P. M. with je Ph a $24.50 Vai. ai We Ape $38. 50 of THEI vol, re- Mame 246: 50 1 ne $67-50 2kozcs, $108.50 8 Nuieetten te 124-50 5 Nails danrece 9164-90 | Mes tained, and will eliminate entirely the danger of cracked glass. Your Opportunity To Buy New Guaranteed Electrical “ Apparatus of Standard Manufacture. Polyphase Motors — for aoe coon 2 and 3 phase, A.C., 220v, Battery Charging 60 c, 1750 RPM., complete and Power Requirements. | with base and pulley. 8 volts, 10am. $16.50 | ue, . 15 volts, 10 amp. $21.00 | # vot, som. $24.50 | '™" - 110, 2% ame. $24.50 | 2H. - 44 volts, 12 om. $38.50 | 110 volts § mp. $38.50 $42.50 $59.50 $72.50 ne. - $84.50 44 vss, 50m. $58.50 | #-?. “$102. 50 wan oes $58.50 1H. > ig see I pans oly $36.50 io - wae UBF + ) nDeunahe 00 cycle, single phase 110 volts, swe Nom $40 .00 without switchboard mat Adan mm # $68.50 mumetaac mae, . $75.00 atmos $86.00 maaitotem $85.00 mate. $110-00 a ge aa ae $125: 00 wanases CATALOG. BARGAINS IN MOTORS AND GENERATORS

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RE = ps Sante. ase ats) - - eee Bil aa = pk tA We cl TO tS Be app Kaan A sO A I Ate eA a EOE TG LI ORE tea or Bens et mE Sie ORS en ee ne ea Why Forgings are Superior to Castings ROUGHT metal is _ tougher, stronger and and more reliable than cast metal. Consequently, for safety or dependable service, wrought metal is used; its great superiority in these qualities being universally recog- nized. A casting has no close, tough grain—it is naturally brittle. As “blow holes’’—cavities due to gas—are often formed beneath its surface, it is im- possible to know whether the casting is solid, or hollow, at its vital point. Its appearance of solidity may be, literally, a “hollow sham,” concealing a dangerous defect. Castings are never used where maximum strength is com- bined with minimum weight. Drop-Forgings are made from ham- mered, or rolled — wrought — bars. Even their raw metal, therefore, is much tougher than the finished cast- ing; this metal is still further improved . and refined by the compressive and strengthening blows it receives from the drop-hammer, the “ram” or ham- mer of which weighs up to 12,000 lbs. The tenacious toughness and de- pendable strength of Williams’ Superior Drop-Forgings and Drop-Forged Tools are the result of experience gained dur- ing nearly half a century of constant effort to make only the best. J. H. WILLIAMS & CO. “The Drop- Forging People” 7 Richards Street - Brooklyn, N. Y. WILLIAMS’ “AGRIPPA” TOOL HOLDERS You can make a shop SHOP crane in a small garage that was very inexpensive to build proved extremely useful in lifting automobile and truck engines in and out of the chassis. Its use on a few jobs paid its initial cost. The crane was constructed as follows: A piece of timber, either spruce or hard pine, 8 in. long, 4 in. wide, and 8 In small garages the usual way to lift an engine or heavy part is by falls and tackle suspended from the roof. A home- made crane eliminates this tiresome work in. deep, is needed for the cross or top piece. This is used to carry the block and tackle. Next Bet two pieces 8 ft. by 4 in. for the uprights or side pieces. For the floor pieces take two pieces of heavy plank, each 3 ft. long, 4 in. thick, and 8 in. wide. Cut a mortise in one end of the uprights 2 by 4 in. long. Make a hole exactly in the center of each floor piece to match the mortises. The top end of the uprights should be squared. With a square lay off on one end of the first upright a line 4 in. from the end. Turn the stick over sideways and continue the line around until it meets the line where it started. On this line, 1 in. in from the edge, make a cross mark. Turn the stick over half way, and mark again, making sure that the crosses are exactly op- posite each other. Do the same on the end. Take a saw and cut out the block on these lines, and repeat the operation on the second upright. Square the ends of the 8 ft. by 8 in. by 4 in. thick stick. Then, with the square, lay off 3 in. from the end, and square this around the stick until it meets the line at the start. Next measure off 4 in. on this line and mark it. Do the same on the opposite side, being sure that the lines are directly opposite. Mark off the end in a like manner, and then take the saw and cut this block out. The block will be 4 by 4 by 3 in., leaving the ends of the stick 4 by 4 in. and the cut-away por- 148 Popular Science Monthly For Small Garage Owners crane for lifting engines tion 4 by 4 in. and the depth cut 3 in. Do the same with the other end of the stick. Have a blacksmith make the neces- sary strap- and brace-irons. For the bottom of the uprights you will need four heavy braces of flat iron 3 in. wide and 44 in. thick. These irons should be 2 ft. 9 in. long, with holes drilled in the ends for -in. bolts. On the same line with the cut at the top, 18 in. down from the top of one of the side pieces, draw a line with the square. Follow on down the side, and mark off 1 in. on this line. Turn the stick, and mark the opposite side in the same manner; 6 in. above this toward the top square off another line. With a saw cut out this tri- angular piece. Do the same with the cross-piece at the top. These are the seats for the corner braces of 4-by-4-in. stock, and later will be bolted together with 14-in. bolts. Work the other end in the same manner, marking off with the square 18 in. from the corner each way and cutting out for the brace seats. When setting up the crane, start with the floor pieces. Next, set up an upright with the notches on the stick to the side. Be sure that the mortises at the bottom fit snugly. The upright can either be nailed or a hole bored and a bolt put through it crosswise of the plank. Set up the other upright in the same way, and put brace-irons on the bottom, bolting them into place as you go. Laying off the two sides about 9 ft. apart on the floor, with the brace slots and notches at the top facing, put the cross-piece into place. Raise the ends of the side pieces from the floor and rest them on a box. Set them into place, and the job is com- plete. This Cover Keeps Free the Fire-Barrel Head N buildings where fire-barrels are used, it is generally the practice to make a round cover to place over the barrel to keep out the dirt. About half the time these covers are mislaid, or ma- terials are placed upon them because they afford a convenient resting-place. In order to overcome diffi- culties of this nature, a conical-shaped cover can easily be made of tin. This cover cannot be easily knocked off, and it does not present a flat sur- face to tempt the lazy man to lay something on.—J. R. MINTER. Mm m ’ BARREL COVER \ bis 5 A ans ioseliiagen ele anaes 3 Pointed tin covers on your fire-barrels keep people from using them

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May, 1920 A Practi Safe, Easy-To-Use, o eaoel” One“Man Outfit for Farmers, Shingle Mills, Loggers, Timber Men, caer Makers, at Cutters, Contractors, Box Makers, Ice Packers, and ahandy money-making outfit for the man who has timber land toclear, Easy to oper- ate on any size or kind of log. Shipped any- where, complete, with saw, ready for work. Direct From Factory You buy direct from WITTE — you getquick 180 strokes per minute, Nochainsor belts— Friction clutch, operated by hand lever, in- tantly starts and stops saw while engine is running. Starts saw at slow speed or full speed. Chitch works automatically if saw “WITTE ENGINE WORKS KARSAS CITY, M0. PITTSBURGH, PA. PIPE BENDERS Bends all sizes of Pipe from \” to 8”. Hand or motor operated. Send for catalog} American Pipe Bending Machine Co. 51 Pearl Street, BOSTON, MASS., U. S. A. ASBESTOS We are miners and shippers of Crude Asbestos in any quantity. We produce all grades at our world famous BELL ASBESTOS MINES, in Canada. We also card fibres, spin yarns, weave cloths, and make all sorts of Asbestos products. FY For anything you want in Asbestos, turn to ; KEASBEY & MATTISON Saray Dept. S-4. AMBLER, PENNA., U.S. A. Owners of the world’s largest Ravan Mines i IF YOU HAVE METAL TO CUT ¥OU NEED BARTLETT PROP- FORGED SNIPS $2 to $6.70 Compound Lever pede of La erade Crucible Lb Secl, accurate- te: r sizes cut me up eauge easily. 7- inch size. just a ries for bop sthold Ss inch, forged, rasieane 10- 12- gs Bo aon chee 3. our dealer h them or can eet ee rom his obber. au Prices F.0.B. FOLDER ON REQUEST BARTLETT MFG. CO., 31 E. Lafayette Ave., Detroit, Mich, world electrical Tope, air- plane, piano, pipe- organ, flat, hoops, bale-ties, tacks, nails, barbed-wire, concrete re - inforev- ment, springs, net- ting. | wire icp Seneas |, trolley-road wires and rail nds voneds, auto-towing cables, horse-shoes, Illustrated Books Describing Uses, FREE ‘ z = tinfoil is stuffed into the metal pro- A Pencil Used as a Spark- Plug Tester HE ordinary lead pencil which has a metal point protector makes an i excellent spark- plug tester, and one that is al- Ways in your pocket when needed. A small hole HOLE. THROUGH is bored or cut PENCIL through the pencil at its No spark-plug tester at middle, so as to hand? Then make one make a gap for out of a lead pencil the spark to jump. Then FILL WITH TINFOIL METAL PROTECTOR tector to make contact with the lead in the unsharpened end of the pencil, and it is complete.—J. F. DWIGGINS. He Says the Simplest Jack is the Best JACK O. JACKSON, of Jackson- ville, says that the simplest jack is the best, and he ought to be an authority on such a subject. He uses the old-fashioned board, which is neither new nor compli- cated, the matter of adjustment being the unusual feature. The board is placed in an inclined position, as shown in the illustration, and the ma- chine is then run forward a few inches. This movement brings the jack into the upright position, with the wheel off the ground. Of course a little skill is required to prevent over-shooting the magk; but the man who cannot acquire skill of When the machine is moved ferward slightly, the inclined board will jack up the wheel various kinds should not attempt to run an automobile. Mr. Jackson makes a bet with his friends that he can jack up a wheel while his machine is in motion. The board is then adjusted, preferably without the other man knowing it, and the machine is started. The wheel is raised automatically while the machine is moving, and the wager is won.* The simple device is often the best. The present one is inexpensive, easily constructed, and has no movable American Steel & Wire Co.” ®=*"ts5;7,5,4°5+ parts.—H. C. RIDGELY. 149 Chisel and Punch Auto Kit A handy and useful little kit for Motorist or Machinist. In almost any kind of repair work the kit will be in con- stant demand. For example, removing valves and piston rings in cylinders, cotter pins in crankshafts, relining brakes, replacing rivets, and repairing fan belts. Every tool made of octagon stock, Swedish analysis point 80 carbon steel. Absolutely the highest grade steel and the best possible for the pur- pose. The tools are five inches long. Every tool guaranteed. 2 Cold Chisels 2 Cape Chisels 1 Half-Round Cape Chisel 1 Round Nose Chisel 1 Diamond Point Chisel 2 Machinist’s Pin Punches 1 Center Punch 2. Solid Punches In a neat little khaki case that can be rolled up and put in your coat pocket or the side door pocket of your car. At your dealer’s or direct from us for $3.00 Mention style No, 169 Send for Tool Booklet SMITH & HEMENWAY CO. Inc. 264 Broadway, New York, N.Y. Factories: Irvington, N. J.

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Brown & SHARPE MACHINISTS’ TOOLS os zy a on — 3 ee a eT eee AG) 4 RCE Fr nr eee FER etn real nag te pa te plier ae \ PRE AOTPD 4: Oo ae ae =a ©) er = Ses ae oo Universal Bevel Protractor Combination Square Is it serviceable ? Will it give as good service five years from now ? HT If a concern has , supplied tools to satisfied machin- ists for three gener- “tT ations, the answer tH. is evident, and points out to you the tools to buy. Brown & Sharpe Machinists’ Tools We have a catalog that will interest you. Send for No. 27 BROWN & SHARPE MFG. CO. Providence, R. I., U.S.A. Vernier Caliper “The Mark that Guarantees Quallty.” Popular Science Monthly Utilize Old Barrels by Making a Water-Tank In these days of the high cost of everything old barrels can be put to an important use By Windsor Crowell N inexpensive though serviceable water-tank for the farm, shop, or camp can be constructed of barrels, and will do all that the more costly kind will. The number of barrels necessary to use depends, of course, upon the volume of water it is desired to store and consume at each pump- How the water-barrel tank will appear when finished. Surely this is a good substitute for a galvanized water-tank ing; the illustration, which is of a tank made of three barrels, will supply the average family with a day’s supply of water. If the water is to be used for drinking purposes, the barrels must be thoroughly cleaned before assem- bling; but if for washing, irrigating, or similar purposes such precautions are not necessary. The barrels will clean themselves in time. First, erect a platform at the de- sired point sufficiently large to ac- commodate an up-ended barrel. This may be braced to a roof, on high land, or built up from the ground. Always keep in mind, however, that the maximum height of the water-level will determine the pressure: namely, about one half pound to each foot elevation. Barrels A and B must have the heads left in, but barrel C can either have the head removed or a large hole cut in the middle to allow water to run in and any overflow to escape. Bore a 1%-in. hole in the middle of each end of each barrel. Be sure there are no tears or splits to allow water to escape; also remove burrs. Then connect A to B and B to C by 1\%-in. galvanized pipes, as shown. These are made up. of two sections of pipe joined by a union in the middle and the opposite ends of the pipes threaded. Separate the sections, and run on a lock-nut, as 150 shown, until the ends of the threads are reached. Then thread each pipe into the ends of the respective barrels until the lock-nuts bear against them. A piece of felt soaked in white lead will help make a joint water-tight if placed between the wood and the lock- nut. . With these in place, connect the union, and the two barrels will be connected with each other. Place substantial blocking between their edges, so the piping will not be strained and so they will stand perpendicularly and rigid. Connect B to C in the same manner. Drill the top hoop of barrel C, and place three or four large eye-bolts around the rim, to which may be fastened stays to keep the tower from swaying in high winds if placed out- doors. The supply-pipe from the pump can be run vertically along the sides of the barrels as shown, and secured to their sides by means of little metal clips. Extend the discharge end of the supply- pipe down into the barrels several inches, to avoid loss of water in high winds. The bottom of barrel A is bored and tapped as already explained, and the discharge-pipe carried from it by means of an elbow or T.. A shut-off CHIT RS GUY- ROPE CLIP FOR FASTENING SUPPLY PIPE TO BARREL FASTENERS \ ING TIMBERS | SUPPLY PIPE FROM PUMP geome wooo CONNECTING PIPES SHUT ~ OFF ee BETWEEN ol PIPE BARRELS Here is a diagrammatic view of the entire assembly. Note how the wires are arranged to prevént the tower from being blown over near the tank will facilitate retaining the contents in the barrels in case the piping along the line is to be dis- connected for any reason. Paint the outside of the barrels and all exposed metal parts, and you will have a storage-tank to be proud of and one that will cost but little. If properly taken care of the tank will last a long time. Be sure that all parts are painted to protect them from the weather. ie aoe

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May, 1920 How to Cut Roofing with a Chisel ARIOUS kinds of knives are em- ployed in cutting roofing; and, though some of them are better than others for the purpose, none of them are satisfactory. The reason is inherent in the knife, and is’ that, no matter how it is shaped, it has a wedge action. This works all right in some ma- terials, but very badly in a tough, hard fiber saturated CUT WITHKNFE CUTWITHCHSEL - with asphalt, “ and often cov- f ROOTING ered with grit, Try a chisel instead of which takes the a knife the next time Sharp edge off you cut asphalt roofing after the first cut. Try a chisel the next time, and note the difference. It should be sharpened in the usual way, though the most im- portant thing is not to keep the end cutting edge in shape, but to keep the side edges sharp and square with the broad surfaces of the chisel. A 1%-in. or 34-in. chisel is best. The tool should be held slightly in- clined in the direction of cutting. Considerable force may be employed, and the rapidity with which the tough sheet is parted will be a revelation. The reason, of course, is that the square, sharp side edges of the chisel plow out the material and remove it ahead of the tool, instead of wedging into it. This is also the reason why the edges of the chisel last ten times as long as the knife-edge; for the sanded surface is also plowed out and thrown aside before it can do much harm to the cutting edges.—HENRY SIMON. CHISEL STRAIGHT COGE A Simple and Useful Electric Light Adjuster USEFUL, very simple and in- expensive shade adjuster can be made from two clamps and a piece of string. The clamps are tied to the end of the string. By fastening one of the clamps to the edge of the shade and the other to diff- erent points on the cord, the illumination may be directed to any angle. The same device may be used in adjusting the length of the cord, as shown in the illustration. This idea though crude, will be found to solve many a lighting prob- lem by throwing the light exactly where it is needed. Does that swinging elec- tric light annoy you? Then make an adjuster ] DISSTON SAWS AND TOOLS Every Home Needs the Saw Most Carpenters Use ANY a man, after buying and using a Disston Saw, has learned that he possessed consider- able handiness in the use of tools. The perfect balance and the right “‘hang,”’ the proper tension, the correct set, the sharp teeth—all the Disston qualities that enable the carpenter to do his finest work will also enable you to handle your occasional jobs quickly, easily, and well. A Disston Saw holds its sharp, true-cutting edge be- cause of the strength and toughness of the Disston- Made Steel used in the blade. Disston Hand Saws are made in various styles—a saw to meet each specific requirement perfectly. Your dealer will promptly show you the exact saw for your needs. Disston Saws are sold by the better hardware dealers everywhere. Write for the booklet on Disston Saws—it tells how to select, use, and care for Disston Saws and Tools. HENRY DISSTON & SONS, Inc., Philadelphia, U. S.A. “America’s Largest and Longest-Established Makers of Hand Saws, Cross-Cut Saws, Band Saws, Circular Saws, and Tools” ’ Canadian Distributors: HENRY DISSTON & SONS, Ltd., Toronto, Canajia Cincinnati San Francisco Boston Seattle Vancouver, B.C. Bangor, Maine New York New Orleans Chicago Memphis Portland, Ore, Sydney, Austratia

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Popular Science Monthly @) Se), CARBON <2 REMOVER —~ VP can keep your motor snappy and full of “pep” by preventing the accumulation of carbon. Don’t wait until your engine is choked and caked with it. Use Johnson’s Carbon Remover every 500 miles, then the carbon is removed while it is soft and powdery, eliminating the frequent grinding of valves and keeping the motor always clean. No experience or labor required—you can easily do it yourself in ten minutes—and the cost is trifling. Easy — Clean — Safe — Quick Johnson’s Carbon Remover is the easiest, cleanest, safest and most satisfactory remedy for carbon. It will save you from $3.00 to $5.00 over any other method without laying up the car. A dose of Johnson’s Carbon Remover, the engine laxative, will stop that knock—quiet your motor—save your batteries and reduce your gasoline consumption 12% to 25%. Keep Your Car Young with Johnson’s Car Savers Start today to reduce the depreciation of your automobile. An hour or two every month and JOHNSON’S CAR SAVERS will prove their value in dollars and cents when you come to sell or turn in your car. Johnson’s Radiator Cement—liquid. Johnson’s Stop-Squeak Oil—a wonderful spring lubricant. Johnson’s Valve Grinding Compound—gives a velvet seat. Johnson’s Cleaner and Prepared Wax—make body, hood and fenders look like new. Johnson’s Black-Lac—the perfect top dressing. Johnson’s Auto-Lak—a splendid one coat body varnish. Johnson’s Hastee Patch—can be applied in two minutes. Write for our folder on ‘‘Keeping Cars Young’’—it’s free. S. C. JOHNSON & SON Racine, Wis., U. S. A. ooo mo

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