Popular Science Monthly 1920-04: Vol 96 Iss 4

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tenet eaetat Cena Choose your tires the Same way a car owner does- on a busy Saturday afternoon and see the way car owners come in and say: “Give me a U. S. Royal Cord. Give me a U. S. Chain Tread.”’ Those car owners know what the name U. S. means on a tire. And their confidence in the U. S. quality is the same confidence you can have in buying your bicycle tires, if you:only say “U. S. ” |: WOULD interest you to stand in a garage Look at that U. S: Cord Tire shown in the picture. And the U. S. Chain Tread Tire alongside. They are bicycle tires—but they are made in exactly the same design and with exactly the same care as their “big brother” U. S. Automobile Tires. They deliver the same kind of service —non-skid and long wear. Few tire makers devote the same attention to bicycle tires as to automobile tires. If you have been having trouble with your bicycle tires, that’s probably the reason. The United States Rubber Company’ has a high reputation to maintain, not only in automobile tires, but in bicycle tires as well. U.S. Bicycle Tires must live up to that repu- tation all the way through. Find the dealer who sells good bicycles and U.S. Tires—the two go together. If you want to know about the rubber that goes into U. S. Bicycle Tires write for a copy "of the graphically illustrated and fascinatingly written book, “Rubber—A Wonder Story.” There are nine styles of U. S. Bicycle Tires, both clincher and single tube: U: S. Chain Tread, U. S. Cords, Giant Stud, G.& J Corrugated, G & J Chain | Tread, G & J Herringbone, Heavy Service, Overland Thornproof, Nonpareil. Choose the tread you like best from your dealer’s stock. ! Se ey United States Tires @ og. * ) : United States Rubber Company —

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oe April, 1920; Volume 96, No. 4 25 Cents a Copy; $3 a Year Popular Science Monthly Waldemar Kaempffert, Editor Published in New York City at 225 West Thirty-ninth Street = | =| —_ | Why I Know that Monkeys Talk whether you be- lieve that monkeys talk or not, and it is not the purpose of this article to convince you either way, for convictions are no more a matter of choice than noses are. The purpose of this article is to present the essential facts thus far tabulated on the subject. of simian speech and allow the reader to draw his own conclusions. The word speech is used throughout as a more exact term than language, which is often used in an ambiguous or figura- tive sense. Let us begin, then, by asking: What is speech? My reply is: Any oral sound vol- untarily uttered with if matters not to me the definite purpose of conveying a preconceived idea, concept, or impression from the mind of the speaker to that of another is speech. From this plain and simple premise we proceed to collect the salient facts on the question of simian speech and briefly recount how those facts have been formed by many years of meth- odic research. The limits of space preclude many | minor and incidental ob- servations that corrobo- rate the main facts. All through my early life I observed instances of intercommunication _ be- tween animals. For some years my studies were only By R. L, Garner In the picture at the right, Susie, one of Dr. Garner’s subjects, learning to spell. She could assemble three let- ters of her name, but had no idea of what she was doing Susie laughing and threatening to tickle Dr. Garner, who had just tickled her. Her laugh sounds very much like the chuckle of a human being casual and the results inco- herent; but my progress, though slow, was constantly in one direction, for I had faith in my own ability to solve the riddle of speech. In the mean- time, I had sorted out certain sounds that appeared to qualify as elements of speech and others that did not. The . former were voluntary, more or less modulated, and ex- pressed a desire; while the latter were involuntary or accidental, and expressed no deliberate mental process. The one group I classed as speech sounds and the other as anomalous sounds. One day I visited the Cincinnati zoo- logical garden, where I sawa large man- drill caged with a lot of small monkeys of three or four different species. The cage was divided into two compart- ments with a small doorway between them. It was quite evident A lifetime of study and nearly a quarter of a century of self- imposed exile in the African jungles in.a search for the truth about animal speech are summed up in this article. It was Dr. Garner’s last word on the subject to which he devoted his life; for he died at Chattanooga, Tenn., shortly after prepar- ing this manuscript for the POPULAR SCIENCE MONTHLY that the big mandrill was a source of terror to the small monkeys. I noticed that some of them werecon- stantly watching his move- ments and from time to time uttering peculiar sounds. It was also clear that the sounds con- veyed some idea to the 21

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a Bs small monkeys which inspired them with fear or quieted them, according to the conduct of the mandrill. I spent the whole day watching those animals until I was convinced that they could understand the meaning of the sounds well enough to be guided in their actions by the information conveyed. This in- cident opened a new avenue of study. Among the great difficulties in determining the speech of ani- mals, not the least is to dis- tinguish the exact quality or intonation of sounds made by the same animal at different times, to remember the actions that attend them and the results that follow them. It took me a long time to learn that no two species of monkeys had the same vocabulary, and that strange monkeys of different kinds, when first brought together, could not understand each other. though they learned readily. After countless difficulties, I went to Washington and sought the aid of Dr. Frank Baker. He let me have the use of two mon- keys which were kept in a small annex of the Smithsonian Insti- tution. Taking a gramophone to the building, I first placed the two monkeys in different rooms so that neither of them could see or hear the other. Then on the wax cylinder I made a record of the sounds uttered by the male monkey. This was not difficult, for he was in a loquacious mood. Taking this record into theother room, it was repro- duced to the female. Sheevinced great interest and anxiety. She rushed to the horn, looked into it and all around How to Talk to a Monkey It is next to impossible to express animal speech—or even human speech —by symbols, but we asked Dr. Gar- ner to set down as nearly as possible some words from the monkey voca- bulary. Weuh means “What’s that?” less softly it implies a request Ki-uh means “I want”’ Kri-i? means “‘Where?”’ Ahr-r-r means danger Qhui expresses want Our-h means ‘“‘Where are you?” Eu-nh means “ Here”’ Khi-iu means ‘‘Look out!”’ Khi-iu-hou orders a retreat Chu-h means “Hark!” Said it, thrust her arm into it, and chat- tered to it. Then a record of her voice was made and repeated to the male, who be- - came more excited and vociferous than ever. By repeating and varying these experiments I was convinced that these two monkeys absolutely understood the sounds thus reproduced. Dr. Baker was likewise convinced. After a cursory study of several specimens elsewhere, I selected the brown capuchin monkey because it was one of the most talkative. In- cidentally I observed that there. were certain sounds that they used more fre- quently than others. Uponone of these I focused my efforts, and by noting the Dr. Garner in the cage where he sat motionless for long hours listening to and recording the talk of the jungle folk. The cage was made in twenty - four sections which when assembled made a cube six feet six inches square actions of the monkeys when uttering or hearing that sound I soon began to make deductions as to its meaning. The method by which I proceeded is so simple that any novice can follow it. I selected a young capuchin monkey in Central Park and made a clear record of its voice on a pho- nograph. In fact, I made several of these, each contain- ing the sound that I regarded as most im- portant. These cyl- inders were taken to Cincinnati and there reproduced to a specimen of the same kind whose conduct wascarefullystudied. A second machine recorded the sounds made in response and at the same time the conduct of thesecond monkey was noted. Having made a score or so of such records and duly tab- Popular Science Monthly ulated the actions of the animals at the moment of uttering or of hearing the sounds, I was enabled to carry about with me and study those sounds at leisure, to compare them with others, and ultimately to make a tentative translation of some of them. With those records and data I went to Chicago, where the experiments were continued and amplified. After add- ing several new cylinders I returned to New York to re- sume and elaborate the experi- ments. By certain manipulations of the phonograph, such as chang- ing speed, reversing the cylinder, and other means, the sounds can be converted into divers forms, analyzed and studied in many aspects. Such experiments show the essential difference between musical notes and spoken sounds, which the keen ear of the monkey perceives more readily than our Own ears do. Now and again a new sound was added to the list and the experiments extended to four or five other species of monkeys. Finally, the chimpanzees in the Cincinnati Gardens confirmed my opinion that the higher types of animals had the higher types of speech, and this fact induced me to go where I could study the gorilla and chimpanzee in a state of nature. Allotted space here precludes even a synopsis of my seven voyages to tropical Africa, where I have lived most of the time for twenty- seven years, during which I have owned and studied on my premises thirty- nine specimens of those apes, besides a greater number in a wild state. Living alone in the depths of the great jungle, cut off from all social and intellectual intercourse with my own race, having no companion but an ape which was likewise isolated from his kind, it is surprising how quickly and how well we learned to Susie in her own kindergarten, where she studied colors, geo- metrical forms, and numbers. With the bell on the table she would summon her keeper whenever she needed his attention

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April, 1920 understand each other. In summing up the results of my researches in the African” jingles I would ‘cite the fol- lowing cogent facts: The phonograph shows that the higher types of simians have a greater vocal range and a greater number of phonetics, more clearly enunciated, more uniform in quality, and ap- parently-more definite in meaning than have animals of inferior tynes. Those characters are more marked in the chimpanzee than in any other animal below man. The next fact in the order of importance is that cer- tain oral sounds of simians are essentially the same in contour and phonetic qual- ity as certain sounds of human speech. Conspicu- ous among these are the basic sounds of deep “‘a,”’ as in war; short ‘‘a,’’ asin hat; long ‘‘u,’”’ as in blue; short “u,”’ asin hut; short ‘‘o,” as in cot; occasionally long ‘“‘o,” as-in move; and the diphthong ‘‘eu,”’ as in the French peu. Every simian does not utter all of these sounds; but the chimpan- zee does, and there are other sounds more obscure. While it is impossible to represent most animal sounds by letters of the alphabet, all of the sounds here cited are capable of being articulated to consonant elements, or vocalized, as it is technically called; and some of these, as uttered by the apes, actually carry in them incipient consonants, such as the initial and vanishing sounds of the semi-vowels ‘“‘w” and “y,” together with per- ceptible gutturals and labials. These features suggest a transition state in the evolution of speech and warrant the assertion that the phonetics of the ape are about as nearly like those of man as the physical type of the ape is to that of man. The next item is that certain oral light. sounds of simians are recognized by other monkeys of the same kind, and their meaning is sufficiently definite to evoke a uniformity of response that justifies the assumption that those particular sounds have a meaning that serves the purpose of the animal, just as human speech serves that of sound until a response is elicited; and it is apparent that the speaker is conscious of a definite meaning to the sound he utters, since observation proves that no simian habitually ut- ters those sounds when alone. The accuracy with which a mon- key regulates the loudness, pitch, and quality of tone shows that he is aware of the values of speech sounds as a means of communication; and this fact implies that he possesses both the in- stinct and the faculty of speech. It has been shown that all simians recognize and ap- parently understand the vo- cal sounds peculiar to their own race when those sounds are imitated by the phono- graph and other mechanical agencies. These facts show that the sound alone is the medium of conveying the concept. The vocabulary of every race of animals is measured by its actual, normal need. It consists of a few single sounds of categoric mean- ing, which are not qualified by any auxiliary terms or united into sentences. The paucity of words does not lessen their reality asspeech. A word is the smallest unit of expression, but it is Susie had just had her photograph taken by flash- She didn’t like it and was disinclined to face the machine again, but Dr. Garner told her in her own language that it was all right, and you can see by Susie’s expression that she was going to take his word for it although still rather anxious man; that the same sound usually produces the same éffect upon those that hear it, and that certain other sounds uniformly produce certain other effects upon them. Note also the fact that the sounds are habitually addressed to some par- ticular individual or group, with the evident purpose of evoking a response from the object addressed, as must be inferred fromthe speaker repeating the speech—just as a single drop of water is as real water as a tubful. All data focus upon the con- clusion that every simian has the faculty of speech sufficiently de- veloped to express any desire, need, or mental process as clearly as he is capable of conceiving it. It is believed that man himself is evolved from a_ simian prototype. Why may not his speech likewise be evolved from the same source? If, as my research shows, the sounds uttered by simians perform the same functions in simian economy as human speech does for man, in what respect is it not speech? Jim is aiding the research by making a phonograph record —— This is Jim’s expression after listening to his own record 23 Jim listening critically to the sound of his own voice

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Roy ana eam Popular Science Monthly Trainloads of great logs are constantly being shipped from Washington and Oregon to mills throughout the country; one fourth of all our timber grows in these states Where Does Our Timber Grow? HROUGH all the years that our country has been growing, the trees in the great timber tracts of Washington and Oregon have been growing, too. The supply has, therefore, become so enormous that it will last us for two hundred years even if the usual amount of three hundred million feet is cut each year. Above is shown ‘a trainload of great, heavy logs leaving home for mills throughout the country. If all the trees in the states of Washington and Oregon were cut and shipped in freight-cars like these, nearly two hundred million cars would be needed for the job. It is estimated that one fourth of all the timber that is produced in the United States grows in these two states. :, Uncle Saini in the Glass Business CHUNK of glass twenty inches thick and weighing half a ton, yet perfectly transparent—this is the achievement of the Bureau of Standards after three and a half years of experiment. The glass is fresh from the melting-pot and ready to be made into lenses. Until recently most of the optical glass used in this country was imported from Germany, but the war forced America into the business, and the final result is an optical glass superior in transparency to the im- ported product. Glass for lenses must be without blemish. The material used consists chiefly of white sand, which is melted down in a porcelain pot and for twenty hours must be stirred with a porcelain rod. The rod must not bump the pot once during the process, for if it does, tiny splinters called ‘“‘stones’” are likely to flake off. Or if the material is stirred too rapid- ly, glass containing bubbles will result. 2 Purity of raw material is also essential. The presence of even three hundredths of one per cent of iron will give the glass a green- ish hue. Net a cake of ice, but a cake of glass. It is twenty inches thick and weighs half a ton 24 Heat and Head Rivets by Electricity ORM wheels of differential gears are not, as a rule, solid, but consist of a bronze rim in which the gear is cut, with two cast-iron flanges fitting into counterbored recesses, one being on each side of the rim. These flanges, which form: the body and the hub of the wheel, are riveted to the rim. A machine recently developed by a manufac- turer of riveting-machines in Ohio greatly simplifies the riveting oper- ation, with a corresponding saving in time. The worm wheel to be riveted is placed on a pin supported by a strong bracket. By turning the wheel on the center pin each rivet is brought in position for being headed. After the wheel has been placed in the proper position the electrodes are then applied to the rivets. The pressing of a push-button in one of the levers sends an electric cur- rent through the rivet, heating it in afew moments. After the rivet is hot enough the upper electrode is removed from contact with the rivet by raising a lever. A_ spring . pulls back the electrode, making room for the heading tool, which is put in action by a foot release. Rivets rang- ’ : ing from \% to % By moving two levers the first rivet of jineh in diameter may the worm wheel is placed in position . for riveting. Pressure on a push- be headed by this button turns on the electric current machine. How the Air in Deep Mines -Is Cooled HE temperature of rocks in deep mines becomes about four degrees warmer with every 1,000-foot drop. To dis- seminate dust in the Johannesburg mines the rocky sides are wetted. The air, chiefly through compres- sion, reaches a temperature of about 100° F. at the bottom of the 7,000-foot level, and by evaporation of the water be- comes very humid. Fans blowing 400,000 cubic feet of air a minute are used to draw out the warm air and cool to 75° F. the deepest pits. The moisture condenses in a fog in the upper levels of the mine. _ ie of. ak le Se cl thie ee gah, tate tefe ac ak 264k lhCUrelUléC eK | | — A ~~ be oP FTP AS a“ | > wien | S~ we te Oo Wi RA ot

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April, 1920 A Liberty Month and a Nameless Day OME tidy minds fret under the - injustice that gives twenty-eight , days to February and thirty-one to as March, skimping April with thirty. | It sets these sensitive minds on edge \ that the first of the month may | fall on Monday, Tuesday, or any other day. These people may like the proposed “Liberty” calendar. It gives each month just twenty-eight days. Each month begins neatly on a Monday morning and ends as neatly on a Sun- day night. But, since twelve months of twenty-eight days leave twenty- nine days to spare, an extra month, called ‘Liberty’? month, is to be slipped in between February and March. And still there is one’ odd day to be taken care of; so that be- comes an “independent holiday” be- tween December and January, and is affectionately referred to as ‘“‘Correc- tion Day.” Then every four years another nameless day must be slipped in to take care of leap year—prov- ing that the solar system cannot be tamed by logic. As.an exactly squared up week it looks perfect; but twelve months of such © Illustrated weeks leave twenty-nine days over London News Protecting Rangers’ Eyes AM too much in the sun,” said Hamlet—and the same thing applies to rangers stationed in Forest Service lookouts. One of them, Wal- ter Jones, of the Siskiyou National Forest in Oregon, has devised an eye- protector. It is made of cardboard, painted black, is long and narrow, and fits closely around the eyes. Thus the light reaches the eyes through a narrow slot. Rangers must always be on the lookout for forest fires. If you have ever taken a walk in the country when the ground was covered with snow and the sun was shining on it, you will remember how your 7 EXPOSURE pews Surveying can now be done by airplane; the pilot keeps his airplane perfectly level and at regular intervals snaps pictures which are later assembled The Air Pilot Now Surveys the Land and Photographs It for Maps VEN the bravest surveyors dare not enter some places, and these are now being surveyed by airplane. The pilot keeps his airplane in a hori- zontal position, and snaps pictures of the land below at regular intervals. He travels backwards and forwards, taking pictures until he has covered a large section of the land. These pictures are afterward developed and pasted together to form a photographic map. The pilot’s first job is to keep his camera perfectly horizontal; this he does by means of a spirit-level placed on top of it. Then, when he snaps the pictures, he does so at regular short intervals, so that successive pictures just overlap. The speed of the airplane, its height, and several other SERENE le AL * Pee IS SUR te RE :o 5 8 , i] 135 4 14 : ca 5 4 4 : 5 te i 4 i] 4 i i eyes ached from the glare. Trying out the This is similar to the glare acley eae in the atmosphere on the ig made of black- mountain-tops. ened cardboard factors must be taken into consideration when determining the time-interval be- tween exposures. A newly invented instru- " ment figures out these intervals.

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eatoons Where House Numbers Grow on Sidewalks “TS this number 12?” “No; next door.” You’ve often fumbled this way for a street number on a dark night, wasting lots of time and causing much trouble. House numbers are "y usually where you can’t find them. But in one of London’s suburbs all the house numbers are large ones, made of bright polished metal, and fastened to the sidewalk directly in front of each house. Even a passing taxi driver can read them by the light of his cab. On the sidewalks of the streets on which many people pass, metal arrows are also fastened to remind people to keep to the right. There is one objection to cluttering up the streets with metal numbers and arrows: you are very apt to stum- ble over them and fall. Besides, who would polish them and keep them shiny? Surely no modern maid would do such a thing as kneel on the sidewalk and scrub! As an Actor He Is a Bear OST movie stars are temperamental—it seems to be one of the requirements. And the bear in the picture below is no exception to the rule. For the last half hour the director has been trying to get this bear to put his head in the pail; and the bear has stonily refused to do so. Says he in bear language: “I’ve got them all guessing now. I won’t put my head in that pail until I feel like it, and no piece of banana will tempt me. It’s always a good plan to get balky once in a while—folks are usually more considerate for some time afterward.” There are a large number of animals drawing salaries in the moving-picture business today. In one picture play all of the actors are animals. Under the Liverwurst Tree ERMANY sends us this picture of the “liverwurst”’ tree. tree is long, narrow, and looks like sausage. It hangs from the branch just as wursts hang in the show-case of a delicatessen shop. The tree grows in Africa and answers to the name of Artocarpus integrifolia. -The large fruit sometimes reaches a length of eighteen inches. The natives eat it with relish. The wood of the tree has a grain similar to mahogany and is quite valuable. Popular Scie.ce Monthly The fruit of this Mementoes of Two Wars in Its Side ACK in Civil War days a farmer who was called to war embedded his scythe in the trunk out again when he returned—but » he never returned. As the young > tree grew up it gradually swallowed 5 the scythe, until now only six inches of it project from the side. There are two more scythes in the tree to- day, placed there by descendants of the Civil War hero, who fought in the Great War. And the villagers added to the collection by placing three American flags in the branches. i In'spite of its burden, F Be : the tree continues to ” flourish. It is located at Waterloo, N. Y. They Can’t Pull for the Shore *“DULL for the shore, sailor’’-—there’s no use singing this song to the sailors shown below. They can’t pull for any place, not even for the brick wall in front of them. The reason is that their boat is tied bow and stern, to the sides of the tank in which it floats. The sailors are students at the Vincennes Military School in France, and they are practising for the racing season. Instructors and fellow students stand on top of the wall and criticize the work of the men in the boat. The school at Vincennes is much like our West Point Military Academy. The students there are put through a most rigorous course of training, and after they are graduated they become officers in the French army. ‘of a young tree, intending to pull it ©

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April, 1920 Would You Like Your Spats Hand-Painted? ERE is a girl who~ wears hand-painted ~ spats, and yet her satin slippers are very ragged at the toes. This seems like a peculiar combination of wealth and poverty, but when you stop to consider it, you realize that a small can of paint is much cheaper than a pair of satin _ slippers. When passers-by see the flowers on her spats they will never notice what goes on below. And flowers such as these are very easy to paint. Decorations on spats also act as a sort of camouflage for thick ankles. Most people wear spats, not for their beauty, but in order to save the price of a pair of shoes. With spats they can wear last sum- mer’s pumps. And Then Again, There Are Furry Ones AYS the owner of the spats below, “I wear fur on them to keep my legs warm.” If that is true and she is really anxious to keep warm, we would sug- gest to her that, instead of wearing short skirts, satin pumps, and spats, she try thick-soled leather boots and longer skirts. We can’t *help noticing, too, that she wears white silk stockings. . These are not nearly so warm as dark woolen ones. If perchance she doesn’t like the looks of woolen stockings—but she should, since they are stylish now—she might re- tain her silk ones and wear woolen underwear. There are many girls who wrap themselves in great fur coats in winter, while keep- ing their necks and ankles exposed to the cruel winter blasts. A Truck for the Maid’s Use OU set out from your room in the hotel to go down to break- fast, leaving the bed unmade, the used towels hanging damply from their hooks, and general disorder. Yet wher you return a short time later all is in order. The hotel maid must work rapidly and a combination like the one below will help her greatly. . The carpet-sweeper, broom, duster, and brush are hung on one end and a “‘soiled-clothes” bag hangs at the other. Bed linen and towels are piled on shelves between. © International Film Service Co. A Monument to Four Race-Horses Four famous Derby~ winners belonging to the late “‘Lucky Baldwin” are buried at the Santa Anita Rancho, near Los Angeles. And over their grave a giant Maltese cross is being erected by Mr. Baldwin’s daughter—the Maltese cross was the racing emblem of the stable. The cross is six feet square and is made of concrete. It is to be finished in red with black cross-lines. At the base of the cross the names of the horses will appear—‘‘Volante,” “Em- peror of Norfolk,” ‘Silver Cloud,” and “Rey El Santa Anita.” A Bear of a Bear Fondles Teddy HY should your child fondle a Teddy bear? Rather let the bear child do it. But will he? The picture answers the question. But we must admit that he does it growlingly, propelled by the whip in his mistress’ hand. She is Evelyn Greeley, an animal-trainer, and is the only person besides the keeper who can control this particular bear. Perhaps she thinks men’s clothes make her look more ferocious. The bear weighs four hundred and fifty pounds. Miss Greeley makes him take on the appearance of g loving and tender bear.

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These are shark-skins being converted into Icather; your patent-leather shoes may have belonged to some shark Do You Wear Shark-Skin Shoes? E want to catch sharks as much as sharks want to catch us. Practically all o: the shark’s body can be converted into commercial products. The skin, for instance, can be manufactured into leather and used in making traveling bags, patent-leather shoes, purses, and such things. Formerly shark-skin was cleaned and used for polishing, but it wasn’t tanned. Now the skins are given a lime bath and the oil pressed out to re-’ move the fishy odor. Every day about seven hundred sharks are caught and sent to a large tannery in Newark, N. J. A _ twelve-foot shark yields Popular Science Monthly Exit the Old Oaken Bucket ae an automatic pump is properly installed and its motor connected with your electric light cir- cuit, it will draw water from your spring, well, or other source of supply and keep your reserve tank filled whenever water is drawn from it. The pump consumes no electricity when no water is used, and all the attention it requires is the filling of the oil-well about once a year. The pump here shown is unusually compact. Motor, pump, pressure controller, and the rest of the operating mechanism are mounted on a" common base, and cannot therefore get out of aline- ment. An idler pulley, actuated by a spring, holds the belt connecting the motor with the belt wheel of the pump at the proper tension. The pump acts as a vacuum pump on the suction stroke and as an air compressor on the discharge stroke. When the tank is filled with water at the proper pressure, the controller automatically stops the pump. _ RESERVE —_. TANK PRESSURE CONTROLLER MOTOR- DRIVEN PUMP A pumping plant like this will keep your house supplied with water from a spring or well No Way to Treat a Perfect Lady RIEDA, the elephant, is furious— four years old, have just arrived on fifty square feet of leather and ten gallons of oil that sells at fifty cents a gallon. In the Orient some parts of the flesh are used for food. The teeth are made into ornaments by manufacturing jewelers. The scales are turned into glue and the rest of the shark is but she is a perfect lady; and so she shuts her mouth in a thin, firm line, and simply glares. Instead of let- ting her walk down the gang-plank in dignified fashion, her keepers have tied ropes around her and hoisted her over- board as if she were so much freight. Frieda and her twin brother Paul, the City of Manilafrom India. Along with them came kangaroos, hyenas, and monkeys that will be shipped all over the country. First impressions are important, and we doubt very much that after this experience Frieda will make a patri- otic United States citizen. ground up and used for fertilizer. International The Hardest Tool-Steel Yet Discovered HEN a tool becomes dull, time is required to sharpen it, and time in a machine-shop is expensive. A tool that will cut hard materials and still keep its edge saves both time and money. Eleven years ago Professor J. O. Arnold, of Sheffield, England, in- vented the alloy of steel in which the metal vanadium was introduced to provide a cutting power greater than that of other steels. As a result very rapid production became pos- sible. al He has now: produced a steel of even greater cutting power in which the alloy molybdenum replaces the tungsten present in all vanadium-alloy steels, forming six per cent of the steel instead of the eighteen per cent of tungsten. It eclipses the cutting power of all its rivais. ilm Service Frieda is furious, and you can’t blame her. She was hoisted ashore in a most undignified fashion after a long, hard trip frora India to Boston

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April, 1920 The Coming Triumph of the Motor-Ship ~_ Span Gennes oe AMEN” BICOL “TI U wwhrdow j= 2 " = jf MN ted SE ST UrL ik GoU A TYPICAL CONVERSION OF AN OLD STEAMER INTO A-MOTOR-SHIP MANY SUCH CONVERSIONS ARE TAKING PLACE * THE GREAT FUEL BILL BURDEN OF THE STEAMER AS COMPARED WITH THE MOTOR SHIP ON VARIOUS TRADE ROUTES { — | Funnel casing and bot rao se oe pancho hy vn Sbace elie ol. burner — ee ee ee * oil Ext Yanks on flanks — yc AE cuben oy ats peouce one mater oe otis wb gue Hien chor oke sate am From ays ees ae faa | Pere Meee npraserds gaan = ee en Single cllinders m e é Sisconnected t an nease op Lea a ee d LBL IL 3} : trem ie Es 3 et i 2 6 fd mee ‘Te big battleships of the world are fired with oil power of the oil-engine. Today the most powerful fuel. Now the great passenger steamship com- units can drive 12,000- or 15,000-ton cargo-ships with panies are following: suit. But why use boilers at twinengines totaling 61,000 horsepower at ten or twelve all?. Why not consume the oil directly in an engine, knots. The oil- turbine appears to be a future possi- just as gasoline is burned in the cylinder of an auto- bility. | Motor-ships—whose advantages are dia- mobile? Already the motor-ship is here—but only in grammed above—are selling at twice the figure given for small sizes. steamers of like dimensions. ‘Their working, however, For merchantmen the present need is to develop the costs less than seventy per cent of those of a steamer

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Sem ove heutige yee a ney wemseherom Steeda Fesepteletnepeecreerny eactpiader somes oree 1 __/1, remaman-enncaelaame Pamtety nes scr tana — Popular Science Monthly Behind the Scenes in a “Movie” Set The scenario reads, ‘*Scene on _ Stairs,” and this is what happens in the studio First, the draftsman draws up plans for the setting. He reads the scenario, and finds that Helene, the heroine, married for money; and, since the staircase scene takes place in her house, the setting must indicate wealth The staircase is shoved over against the wall of the studio, and the rest of the setting is put into place by experienced stage-hands. From the moment Helene starts to descend the stairs, she will have plenty of time to register penitence and display her beautiful negligée Windows, doors, and staircase are made according to plan in the carpenter shop; they may never be used again, yet they are carcfully made end beautifully finished Tacking decora- tions over door- ways. These small details register wealth—inciden- tally, also, a de- cided change from the humble home of Helene’s youth The stage is set. Now for the lights. A great many scenes are taken in- doors and powerful lights are needed for the purpose. While these men put on the finishing touches, so does Helene in her dress- ing-room upstairs 30 With clasped hands out- stretched in pleading, pen- itent Helene slowly ap- proaches her wronged husband. And all the while the camera clicks merrily. It is a touching scene, but the directors and the camera-man are too busy to appreciate’ it The painters and paper-hangers paint and decorate until that corner of the stu- dio looks as if it had been transplanted from Fifth Avenue Furnishing Helene’s home. This man from the studio has been haunting the furniture houses all day in order to renc appropriate chairs

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er eww" April, 1920 Doing Without the Typesetter The. story of “Piggie’—a typewritten book You think she is writing: “In. reply to—” But you’re wrong: it’s a book. When the typesetters in New York city went on strike, several magazines were written by. type- writer, so successfully that a book called ‘‘Piggie’’ was done in the same manner “Piggie” is being put on the “press. The zinc plates are pliable and fit perfectly around the top roller. ‘‘Piggie,’’ by the way, is a fairy story for grown-ups, and Piggie is a plain though far from ordinary pig. The book is by Eleanor Gates ELLE a ee RR (Right) When the first edition of “Piggie’”’ was print- ed, the zinc plates were stored away for future reference. ee As you see, the ge dozen or so plates > of ‘‘Piggie’ were sandwiched in be- tween the plates of many other books - PIGGIE I TRIS LITTLE PIG WENT TO MARKED Piggie studied the freckled face tha Gee peeriag in at bie between teo of the lower boards of the ety. "Spotted,* be GQrvuated to bisself, thoughtfully, soving @ url of o teil that was not long enough yet to shoo even o fly; "--epotted, just Like Tee. Only bie spete are onell, sed he's got so sany of thes, on 4 they're 013 on bis noeet* : Mother Pig wae lyiog flat on her side wader the corrugeted-iros thet roefed one @orner of her pen. She wee & for teen itt Piggie's eleven bi end white brothers and sisters (for this wae lesem © Auedectae] fenily of suckiiage) sere After each page is carefully typed it is photographed. The chief objection’ to these type- written pages is the ragged edge at the right-hand side. . But’ that has been overcome: recently The printing is done with a regular press, the zinc plates or electrotypes of’ them : being locked in Photographs @ place in the regular way by the Press Illustrating Service Zinc plates are made from the photographs of the typewritten pages. This man is ‘ making the few necessary corrections on a thirty-two-page zinc plate. In this kind of printing the proofreading is done on the original typewritten sheets by the typist herself (or possibly himself), and so by the time the zinc plates are made there is very little correcting to be done on the plates 31

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amy He is putting the new-born babes in boxes and is collecting the shells they left behind them. These young chicks will be brought up indoors under arti- ficial light; for experiments have proved that the source of light makes no difference in the health of chickens Sunday dinner return to earth to visit its descendants a century hence, its surprise might not be unlike that which the ghost of Benjamin Franklin would experience if he chanced upon the Woolworth Building. The chicken house of:today is a single-story structure, which, to ac- commodate the human attendant, is built ten times as high as a chicken requires. Chicken-height floors in an ordinary chicken house would make it a ten-story building: and, once we have the idea of a chicken skyscraper, why not go ahead and make it one hundred stories? ‘‘But,’”’’ says the poultryman, “it isn’t natural. A chicken must have contact with the soil, the sunshine, grasshoppers, gentle breezes, and other attributes of na- ture as it is.”’ Notwithstanding this objection, the logical place in which to run a future poultry farm will be a building in the city in which the product is to be con- sumed. There would be the added economies that go with large-scale operation: ‘cheaper -building costs, reduced heating expenses, substitu- tion of machine fer hand labor. The only added expenses would be artificial light and city ground-rent, which would be offset by the elimination of transportation. Thus more chickens could be raised, more eggs produced, and the price of eggs would then come down from their dollar-a-dozen mark. G ‘sunday the chicken you ate for These are a few of the striking fea- — tures of the Hastings factory system of indoor chicken-raising. Milo Hast- ings, a former government poultryman and an authority on incubator con- velop an equally Popular Science Monthly £ The Skyscraper Chicken Farm Raise chickens in the city and save transportation charges This is one of the incubator rooms, and it holds about fifty thousand ezgs. The three bottom trays contain eggs that are nearly hatched. The other trays are placed on collapsible racks so that the eggs can be turned easily struction, began his distinctive work in the poultry field by the designing.and construction of mechanical draft hatch- eries. He conceived the idea of a hatchery with the whole building in- sulated, and with temperature and ventilation controlled by air drafts forced with blowers. Several plants of this type have been constructed, and the consequent saving in space was enormous, thirty thousand eggs oc- cupying a space scarcely larger than a hall bedroom. Striking as were the mechanical innovations of these hatcheries, the business enterprise was not propitious, since there were too few poultry plants that had need of a large enough hatch- ing capacity to make ad- vantageous use of such. methods. To make his large-scale hatching ideas more feasible, Mr. Hastings next set about to de- perfected system of chick rearing. The chicken in the egg has only halftheattributes 32 There are thirty thousand eggs in one small room, and they all will be chickens soon. By placing the eggs on shelves that reach froin the floor to the ceiling, much space is saved of the living animal. When he kicks aside his protecting shell and starts out in search of worms, his industrial status changes radically. The chicks’ needs are instinctively adapted to out- door life. Thus far poultrymen have thought it cheaper to raise chicks in scattered coops about the fields than to attempt to make the indoor conditions fit those instincts. Mr. Hastings first set about to learn the efficiency of artificial light. He has raised chickens four different seasons in four different locations with the exclusion of daylight, and has Carting away the cast-off shells—the result of one day’s hatch. The birth-rate is very high in this hatchery, which*is located at Petaluma, Cal. Ons OM AA DRHK RK AA il hhh ——_——.

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April, 1920 checked these tests against daylight, and against an alternate use of day- light and artificial light. His con- clusions are that the nature of the light is unimportant. With artificial light the relative length of the chick’s day and night may be changed or the complete cycle may be short- ened, as when the chicks are given alternate periods of light and darkness each of six or eight instead of twelve hours. In like manner the long lighted . days of June, if these be ac- cepted .as the -best for the chiek’s benefit, may be adopted as the all-year schedule. But the greatest utility of the artificial light is that it enables the chicks to be placed on superposed floors, at heights adapted to chickens rather than to men, with a result of from five to ten times-as many chickens in a building as could be accommodated. by the daylight method, and with no -restriction of the height, breadth, or length of the building. - All building costs and most items of building up- keep become more economical per. chicken ‘with the- increase in the size of the building. But, you say, “‘Such fearful overcrowding would breed dis- ease.”’ Disease is caused by the propagation of germ life. Germs live only in dampness, notably on damp soil or litter, straw, etc. The dryness that can be maintained with arti- ficial heating and blowers, to- gether with steel and concrete construction, and lastly the mechanical circulation, cleaning, and sterilization of the scratching litter, build up a sure defense against disease. The chick needs exercise and pleasur- their heads on the ceiling. able occupation for its every waking moment. The chicken factory pro- vides artificial means of entertainment and occupation that are as efficient on stormy days and in winter as they are on pleasant days and in sum- Each floor of the chicken skyscraper is sufficiently high to allow the chickens to move about without bumping Artificial heating dries out the floor dampness that would ordinarily breed disease mer. This is achieved with mixtures of litter and grain that are mechanically carried aloft, and, by means of sloping floors, worked along and down by the This is the alleyway between the incubator rooms of a large hatchery in Cleveland. The women are sorting the eggs that have just arrived. The good ones are put in trays and incubated; the imperfect and cracked ones are sold to local dealers 33 chicks themselves, making not only an automatic exerciser, but giving self- cleaning floors. Dust baths, water trickles, and macaroni-like dough worms all aid in the good work. Machine mixing and feeding give greater accuracy in pro- portions of food, and avoid possible negligence of indi- vidual employees. A use of artificial light is here dis- covered in that the chicken will always run from dark- ness toward light. This fact. may be used to lead chickens about the place or ‘encourage them to take long walks through the runways by the manipulation of the : switchboard—or, better still, by a modified sign flasher. The largest hatchery in America is located at Cleve- land, Ohio. This plant is equipped with incubators hav- ing a capacity of 666,000 eggs —or forty tons—at one time, and in 1918 actually produced and shipped about 1,500,000 chicks in the few weeks that constitute the spring hatching season. This tremendous business was made possible by the development and perfection of hatching apparatus .embody- ing an entirely new principle of incubation. These incubators are practically automatic in operation and reduce labor to its lowest terms. Incubators of the ordinary type are boxes or cases of varying form and size, con- taining egg-trays in one tier and at a uniform level. This arrangement is necessary in order to maintain an even temperature on all parts of the trays. In the new ma- chine the egg-trays are placed in racks, twenty-two tiers high. Uniformity of temperature is obtained by the use of electric fans. ; At the Cleveland plant there are twelve of these great incubators, each twelve feet long, ten feet wide, and ten feet high. When filled, each holds 55,500 eggs. With 60 per cent hatches, each turns out 33,000 chicks every, three weeks. In caring for eggs and chicks, the attendant actually enters the in- cubator. The labor of turning the eggs twice daily is practically elimi- nated by the arrangement of egg trays in supporting racks. These racks are collapsible, one side drop- ping down as the other moves up. Merely by pulling down one ‘side of the rack the trays are tipped to an angle of about fifty degrees, throwing the eggs well over on their sides.

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The achieving of a homemade tractor is possible if one happens to own a stationary engine and if there is a junk-yard in the neighborhood. You Can Make a Tractor from a Stationary Farm Engine HE owner of an eighty-acre farm in Lehigh county, Pa., recently constructed a farm tractor, starting with a fifteen-year-old one-cylinder stationary gasoline engine. The truck and other parts of the | tractor were taken from the scrap-pile. Adding part to part, this me- chanical horse soon began to assume definite proportions, and the finished product has all the controls, speeds, and devices of a modern tractor. Mr. Geissinger, its’ maker, has been very ‘successful in using it for threshing pur- poses for himself and farmers in his section. He is able to do plowing with three plows attached to the rear, and it climbs the grades with- out a balk. The actual cost of this this tractor was $265. The Automobile Jack on Wheels O that it can be slid in under the front or rear axle of a car, the P latest thing in automobile jacks is .@ mounted on wheels. Wheels are all if right for moving the jack into place, . but what about holding it in position t ; when the strain to lift the axle is put j upon it? Will it slide? These two very important questions have been answered by the manufac- turer; for the wheels are mounted on springs, so that they move up inside of the base of the jack, which then hasa firm, non-sliding foundation. Ve The new jack is further characterized - by the fact that it is entirely encased, . so that the grease inside the standard | cannot soil hands or clothes. A long | . —— are = pec care oe I After the car has been jacked up, the rollers on this jack permit the car and jack to be pushed around to any_ desired « position rr gem tetene hgem AN n vs mete a extension handle, which can be folded k i to fit into the tool-box, also makes the jack easy to operate. apparatus. Popular Science Monthly A One-Man Street-Cleaning Truck PERATED by only one man, the improved form of motor street- sweeper shown below sprinkles, sweeps, and collects all manner of street dirt in one operation. The machine is not so wide as to restrict traffic, even on busy streets during the day. Further- more, it is mounted on solid rubber tires in the rear and pneumatics in front, and is not so noisy as to prevent its use in the residential parts of a city during the night. The sprinkling equipment consists of a water-supply tank with a capacity of one hundred and fifty gallons anda set of spray nozzles set crosswise under the truck-frame just in back of the front wheels. The water is fed by gravity from the tank at the rear to a bronze gear pump operated from the propelling engine of the apparatus. This pump is under the control of the driver. After the dirt has been softened by the water, it is left undisturbed until it comes into contact with the broom. After the dirt has been picked up by the broom, it is conveyed by an en- tirely new means to the hopper or dirt- container located above the vehicle frame directly in back of the driver’s seat. This new method makes use of an inclined flat steel plate around which are operated a series of rubber squeegees mounted on chains and placed longitudinally of the vehicle center-line. At the top of the steel plate, the dirt drops off into the hop- per, while the squeegees snap them- selves free from the dirt, pass over the upper chain sprockets, and return for another circuit. Formerly street-cleaning was a complicated job for three pieces of horse-drawn This machine, operated by one man, does it in one third the time Aj

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April, 1920 A Simple Lathe Used for Grinding Valves RINDING the valves of an autos mobile engine in an ordinary lathe is a troublesome and expensive job because great care must be taken in centering the valves and this requires the services of an expert mechanic. To overcome these two difficulties, an Indianapolis concern has just devised a simple valve-grinding lathe in which the centering is done automatically by placing the valve stem in the machine. The apparatus will grind valves with 45-degree or 30-degree heads up to two and one half inches in diameter and with seven-sixteenth-inch. stems. All that one need do is to set the cutter for either a 45-degree or a 30-degree head, insert the valve, tighten up on the clamps and feed the valve to the cutter by turning one handle, and revolve the valve about: its axis by turning another handle. A new lathe that grinds valves with the precision of a mechanic Your car washed while you wait. Aspraying apparatus above and at the sides throws water upon all parts of the car at once Washing Eight Hundred Cars a Day LEVELAND has a company that does nothing but wash cars. Its place is open twenty-four hours a day and it washes from fifty to eight hun- dred cars daily. At any time of the day you can drive your dirty car in one door and within twenty minutes drive it out.of another, washed and polished. After a car has been run on to a set of tracks, the first operation is to clean its sides and under part. This is done by a cradle of perforated pipes at the side and under the car. These pipes have a set of eight sprays, which strike the car from as many different anzles, none high enough to splash over the sides and wet the upholstery. While these sprays are at work softening the dirt, the second opera- tion, that of washing the top, begins. This is done from one side of the car by a man who stands on a spe- cial platform suspended from the roof trusses. From this platform the worker can easily reach the center of the top, which is thoroughly washed with a sponge, the water being pro- vided from an overhead pipe through a flexible hose. By the time the top is cleaned, the sprays have loosened all the dirt and mud accumulations on the chassis and body, and the car is them moved along the track and the third process is started. This consists of going over the engine hood, body, and tonneau with hose and sponge, and of cleaning the grease from the wheels and chassis with a kerosene spray. The car is then dried by compressed air. Oil-Tanks Now Filled ky Compressed Air N garages that have a compressed-air equipment for inflating pneumatic tires, no hoists, inclined skids, or waste of oil in splashing are necessary in filling oil-tanks if the. new barrel-discharging bung illustrated herewith is employed. All that is necessary is to insert the bung, attach the air hose, in- sert the outlet pipe inside the tank, and turn on the air. Fur- thermore, it is not necessary to lift the barrel off the floor. The bung is cone-shaped and threaded on the outside. Because it is cone-shaped, it can be made to fit: any size of bung-hole by simply screwing it in a trifle farther. It makes an air-tight connection in the barrel. The bung itself is made of metal, and has inserted through it a pipe, the lower end of which is telescoping so as to extend clear to the bottom of any barrel. si Pan By this method the oil is discharged into the ser- vice container without collecting foreign matter 35 The upper end of this pipe extends through the top of the bung and has attached to it a piece of flexible hose several feet long to reach from the bung to the opening in the top of the storage-tank. The compressed air is led inside of the barrel to be emptied through a hole drilled near the top of the bung and coming out near the bottom. When the air is turned on, it forces the oil up through the telescoping pipe and out through the discharge hose into the tank. Less than five pounds pressure is sufficient to empty an average barrel in a few minutes. If a faster speed of dis- charge is desired, a greater pres- sure may be applied without difficulty, inasmuch as there is always an immediate outlet for the oil. / ~

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a + mens ee orm aot —— Py — ees Mena Ler 5 hai: anaes a a © Press Illustrating Service Instead of coal put an oil-burner in your range and connect it with a pressure-tank Making the Coal Stove into an Oil-Burner INCE oil is tolerably cheap, change your coal stove into an oil-burner. The picture ilustrates how it may be done. The tank is filled with air com- pressed by a tire-pump. The lower part of the tank contains the oil reser- voir. When the valve is opened the compressed air forces the oil through a flexible copper tube into the burner. The oil is blown in the form of a fine spray into the fire-box, where it burns with a hot flame. The burner is placed on the grate of the fire-box, and the copper feed-pipe is passed through the draft shutter of the ash-box and the bars of the grate and connected with the burner. Whenever the pressure becomes too low, a few strokes of the piston of the tire-pump will send the hand of the pressure-gage to the desired figure. Pack the Barrel Tightly IR bubbles in a barrel of cement are just as harmful as air bubbles in a jar of preserves. Of course they don’t make the cement ferment, but they do collect in the top or at the sides of the barrel as the cement settles down, and makes the barrel weak. At the points where there is nothing but air beneath the staves a barrel can- not withstand a blow. A little rough han- dling will soon smash it and scatter the cement. What is the remedy? Thomas Edison, on entering the cement business, quickly solved the problem. Shake down the barrel as you fill it, says he, and the air bubbles will disappear. x You have often done the same ques thing when you filled the flour can. But barrels filled with ce- ment are too heavy to shake by hand, and so in the Edi- son plant a machine is used for the purpose. The packers place the barrel on a platform and shake it mechanically. The operator can tell from the indica- tor dial which way to shift the plate The cement in the barrel was packed so tightly, to exclude air bubbles, that at the end of a journey it remained firm when the staves were broken away 36 Popular Science M onthly Cutting Iron Plates into Ribbons OLLED iron or steel plates, as well as sheets of other metals, from the thin sheet-iron used for stovepipes to the heaviest plates of which boilers, tanks, etc., are made, are cut with shears. Formerly straight-edged cutters, operating on the same principle as the two blades of a pair of scissors, were used for that purpose. rotary shears have taken their place. A heavy steel disk with a sharp cutting edge is rotated against a stationary straight edge of hard steel. The plate to be cut is passed between the rotating cutting disk and the straight edge against which it bears. The disk, which is pressed against the plate with tremendous force, cuts through the metal as the cutter of the trimming wheel ; used by photographers cuts through the paper of a pho- tographic print. When long strips are to be cut, the line along which the cut is to be made is marked on the plate with chalk or paint, and the workmen op- erating the shears must fol- low the prescribed line very carefully. The rotary shears shown in the picture are provided with a device that facili- tates the task of follow- ing the cutting. A line pointer connected with a dial is placed a short distance ahead of the cutter,.and the workman stationed at the cutter keeps the point of the instrument on the line. The man who is feeding the plate to the cutter closely watches the indicator dial, which tells him by the . position of the hand when- ever the cutting line de- viates from the plane of the cutting edge in either direction. Finding Oil with Electricity LECTRICAL instruments of sufficient sensitiveness can be used to detect the presence of oil-bearing regions when the oil is not far from the surface. In this case the usual current transmitted through the earth is measurably stopped by the insulation afforded by the oil, and the interruption to the flow of the current from metalliferous regions ' serves thus to indicate the intervening layers of oily material or oil as an insulating medium. But some of the greatest reservoirs of oil exist at such depths that they would be beyond the range of the electri- cal detector. For deep wells the instrument is then in- effective, but it can be used satisfactorily where the oil is near the earth’s surface. The use of the instrument to detect the presence of metals is well known, but it is the diverted application of the metal-finder that serves now as an oil locator. More recently —

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a lc i ed a Ww @S = cr be eMtes (Pi auieotiin a Ae GEE April, 1920 Making Ships of Puffed Brick ONCRETE for ship work must be lighter than the hundred and fifty pound per cubic foot mixture commonly used, if the concrete ship is to compete com- mercially with wood and steel vessels. Puffed brick is a mixture of cement and other ingredients forming a concrete that is just as strong as the ordinary kind made with cement and crushed stone, but that we about one hundred and ten pounds to | the cubic foot instead of one hundred and fifty pounds. It is an artificially burned clay or shale uniformly filled with small non-connecting cells. The basic clay from which it is formed becomes plastic when heated in a-kiln to a temperature of between 1,800 and 2,000 degrees, and forms a coating that retains the gases generated by the de- composition of the contained compounds under heat. This expanding gas puffs the brick or the clay ball to several times its original size. While <G, puffed brick is full of holes, it ° —\\ is not porous. A 7,500-ton oil-tanker is one of the latest concrete ships to be made of puffed brick. Contrary to steel ship practice, its engines and boilers are pleced amidships

puffed brick concrete has been used is the 7,500-ton oil-tanker a diagram of which appears above. It and its companion ship, a 7,500-ton cargo vessel, are the two largest stone boats that have ever been attempted. The tanker is 420 feet long, and, contrary to conventional steel ship practice, has its 2,800- horsepower reciprocating en-

Thus made, the puffed brick is ground to a uniform size and mixed with cement to form concrete, which is poured into the form to mold the shape of the ship in the ordinary manner. Following the latest development in forms for building construction, those forms used for ship work are now generally made of metal and hinged with bolts, so that they can be opened up and moved along as soon as the concrete hardens. After a launching, the forms are replaced, the steel reinforcing rods_ placed, and the pouring of another ship begun. One of the latest types of concrete ship in which the Try a Sample, Lady? AMBURGER steak in a can on a shelf in the grocery store isn’t nearly so at- tractive as a sample of it served on a fancy plate, with a shiny new fork to eat it with. Realizing this, a large canned meat com- pany has supplied its sales-people with sample cases containing various canned meats, canned heat, plates, spoons, and knives. They set up their cases in the corners of grocery stores and feed morsels to customers. After one mouthful the sampler may become a confirmed buyer.

If you wish to gain new customers, tempt them with samples of your goods In building ships of the new puffed brick concrete, the ribs are placed close together, just as in the construction of steel ships This pow lubricated with machine ’ oil instead of elbow-grease, and saves a great deal of valuable time in the shop “ gines and boilers placed amid- ships instead of aft. This more desirable location was chosen because the oil tightness of the shaft tunnel or alley from the rear of the engine to the propeller is more certain when made of concrete than with steel plates. The system of framing in the tanker is much the same as in steel ships, the frames or ribs being placed close to- gether. Two longitudinal bulkheads extend for the clear length of the vessel from the forward to the aft collision or cofferdam transverse hulkheads. A Motor-Turned Screwdriver WIST, turn—you struggle with a screw- driver. It keeps slipping out of the groove. How about the man in the shop who must drive a great many screws in a day—does he have the same trouble? Not if he uses one of the new electric screw- drivers. The motive power is supplied by a small motor of one half horsepower or less, which may be: suspended from. the ceiling or fastened to the top plate of a metal stand resting on casters. The motor may be connected by a plug and cord with any conveniently lo- cated electric-light socket. A flexible shaft connects the motor with the screwdriving tool. The edge of the screwdriver is placed in the slot of the screw, one hand of the workman holding the « handle, the other steadying it by ) grasping the ratchet handle. jy When the handle is pressed ‘ down against the head of the screw, the screwdriver engages a friction clutch at the end of the flexible driving shaft and revolves rapidly, driving in the screw to its shoulder.

screwdriver is

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a i ; 5 et RRR Re EE eR NA NE SE IY Se Memen e eeraee aeeren rt aebatee ™ Popular Science Monthly There were portholes at regular intervals in the upper surface; these were closed just before the flour dust was exploded Watch Out for Flour and Starch XPERIMENTS carried on by the Department of Agriculture prove that the dust of starch and flour will explode with greater force than that of a coal-dust explosion. A 200-foot steel cylinder was prepared, one end of which was left open, while the other was closed except for a small hole against which a specially made ‘“‘cannon’”’ was placed. First, coal dust was spread on shelves inside the cylinder. The cannon set off a charge of gunpowder in the cylinder, and the coal dust exploded with aroar. After the cylinder had been cleaned out, flour dust was placed in it. When this was set off, the blast was far more violent than the coal- dust blast. The starch-dust explosion was the worst of all. It shook houses three miles away. The earth trembled; the engineers who were watching the explosion were thrown to the ground; and the photographer who was taking pictures in a telephone-booth a hundred feet away was temporarily blinded and stunned. A Monster Steel-Rolling Machine NE of the largest machines ever built for rolling steel plates is shown here. It is-what is known as a 180-inch plate mill, and it has been built by an Ameri- can company for the Imperial Steel Works at Kobe, Japan. Its over-all height is thirty feet three inches with the rolls together, and thirty-three feet three inches with the rolls apart. Its total weight is 592 tons. The rolls are steel forgings 49 inches in diameter, and weighing sixty tons. Forged steel rolls are used because of the almost prohibitive prices asked by roll manufacturers for chilled rolls of that size. ” The preheated red-hot slabs of steel are brought up to the rolls of this ma- chine by special apparatus and are then passed : through the heavy rolls — until a plate of the desired thickness is produced. Hot slabs of steel are passed through this great rolling- machine until they have reached the required thickness This picture of a starch-dust explosion was taken in spite of the fact that the photographer was temporarily stunned by the force Hitch Your Rubbers. to Your Shoes ID you ever lose your rub- bers in the mud? Perhaps you don’t live in a muddy place, but there are others who do, and they may be glad to hear that Mr. Philip Lettre, of North Attleboro, Mass., hasinvented a rubber-protector that makes it im- possible for a rub- ber to come off without taking the shoe with it. The protector consists of a spring with a hook at one end and a sharp pointed fastener at the other end. You pierce your rubber with the point of the fastener, and bend the point up over the back face of the fastener. Then you slip the hook over the top of your shoe. The spring between the two will stretch about half an inch to allow for adjustment. How to Grow Tall O to bed and grow tall. It has been proved by experiment that the average person gains al- most three eighths of an inch in height after a night’s sleep and shrinks the same amount dur- ing the day. A long stay in bed not in- frequently increases percep- tibly the height of invalids, and it is also true that the more rest a young child has the taller he will grow. The reason for all this is that the weight of the head when we are standing erect compresses the spine. This fastener will attach your rubber to your shoe, so that you can’t lose it in the mud without also losing the shoe ——=

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April, 1920 It would take the lifting power of four thousand men to do the work of this lofty steel giant, which was built at the League Island Navy Yard, and is said to be the world’s largest crane One of the 100,000-pound loco- motives being juggled in the -air from the strong cables of the giant crane. What a thrill- ing ride to take in mid-air! In the picture at the right: Getting ready for a swing in the air. Compare the size of the tackle with the size of the men . “ @ 7 ™ ms rw be. , : - 4 Pe ~ y ‘4 tli | -- “ —" Juggling Heavy Loads in Mid-Air MAGINE agiant having the lifting power of four thousand men, whose head is 230 feet above the ground and whose arms could reach outward 190 feet, and a very clear idea of the size and'strength of the massive crane that was built at the League Island Navy Yard can be obtained. Four locomotives, each (weighing 100,000 pounds, can be juggled in the air at one time by the huge crane. Its great mechanical arm reaches out- ward and picks up one or more of the locomotives at a distance of 190 feet, dangles it in the air 141 feet above the ground, and sets it down at a distance of 41 feet from the central supporting arch. With the power of this mechanical giant the Egyptians could have built the pyramids in short order. The temple of Karnak, with its massive blocks of solid rock, could have been piled up with ease if this giant crane had been at the beck and call of the builders. What great achievements may not be expected in the future when it is employed lifting weights to the height of a city skyscraper? With empty hands the steel crane can operate at a speed of ten feet a minute; but when it carries a heavy load, the rate of about two and a half. feet a minute is required for its operation. FS “= ¢ ~s eee ~ 3 7 ont ~~ “dee ey he a 7 a 48 q a > Compare this giant with the man. It is a giant crane that can dangle four locomotives in mid-air, whose brawny arms of steel can reach outward from 41 to 190 feet, and can raise a heavy weight to a height of 141 feet. The giant stands 230 feet high. It is capable of lifting 400,000 pounds to the height of a ten-story building A Nk ND A : > i

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ray wr nin obesaahaaracatds Mieitiae 9 Piriaghecencenecnneen eae erate er Ye Ot SAAN Ht “7'll tell the world I wouldn’t wear ’em if I didn’t have. to,’’’ he said as he gave the unwelcome lenses a rub and jammed the frames back over his cars UD BRADY, chief lineman for B the North Fork Hydroelectric Company, thrust open the door of the Centerdale substation, dived in- side, and slammed the door behind him in the face of a pursuing blast of rain. “Well! . Caught you, did it?”’ Ike Reed, the station attendant, greeted him from the near end of the purring motor-generator in the middle of the room. Bud did not reply. Leaning his wet back against the door, he jerked off a pair of large shell-rimmed spec*acles and reached into a trousers pocket. “Darn glasses, anyhow!” he growled, fishing out a dry handkerchief and rubbing the rain-splashed lenses with irritated vigor. ‘‘Whenit rains they’re - wet and get streaked; when it’s hot they sweat and get streaked; when it’s cold they steam and get streaked. They must think all I got to do is stand around and rub ’em all day.” Ike nodded. ‘Yes, I guess it is a lot o’ trouble,’”’ he agreed. Bud grunted: “You don’t know anything about it. You don’t have to wear ’em. I’ll tell the world I wouldn’t wear ’em if I didn’t have to!” and he gave the unwelcome lenses a final rub and jammed the frames back over his ears. “Pretty fair little storm,” Ike re- marked, with an amiable desire to change the subject. Bud wrinkled his nose to force his glasses into position. ‘Thought I could make it here before she broke, but she caught me about a mile out.’”’ He shook the drumming boom of rain on the roof there came a sharp crack- ling report from the switchboard at the opposite end of the long concrete room. ‘We'll have some fun now,”’ Ike sighed ruefully, and turn- ing ran back to the switchboard. The flash proved to be merely a small affair which had come in over the 33,000-volt high-ten- sion line supplying Centerdale from the water-power station back in the hills. It had jumped the horn-gap arresters, and Ike, with a glance »ver the switch- board to assure himself that every- thing was as it should be, returned to water from his shirt. “Liked to drown me and the flivver. There’s going to be some light- ning too.”’ Andthere was. Scarcely had he spoken when above the ** What’s the matter?” he yelled above the noise of the fire. “Eyes! My eyes!” Ike answered. “Don’t mind me! Get the fire!’”’ Bud saw his com- panion fall back, with his hands over his eyes - Popular Science Monthly Blindfolded by Clear Glass Ordinary spectacles saved this man’s eyes from ultra-violet rays By Charles Magee Adams where Bud had seated himself beside the front window and watched the rain swirl around the little service car parked outside. Scarcely had he seated himself when there came a vicious crackling report. “There’s going to be fireworks,” Bud announced. ‘‘Guess we’d better both take a hand,” and he ran back to the switchboard with Ike. The second flash too had jumped the horn-gap properly, but Bud and Ike had no sooner made sure that every- thing on the wide switchboard panel was in a proper condition when a third came—a long ripping flash; and after that the flashes came in with machine- gun rapidity. Side by side the chief lineman and the station attendant worked for five fast minutes: resetting the circuit breakers when they were tripped, opening and closing switches, doing everything in their power to protect

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April, 1920 the lines and equipment from the storm and still maintain service. And all the time from the fifty miles of transmission line reaching up the North Fork valley the flashes con- tinued to arrive. Then it slackened. For a _ half minute there was no flash at all, only - a single feeble flicker—for a whole minute simply the drumming of the rain on the roof. “Shame it ain’t the Fourth o’ July,” Ike grinned, mopping the perspiration from his forehead. There was a blinding flash—a crash- ing report—and a huge, vivid ball of flame burst from the maze of con- nections and cables behind the switch- board, seemed to poise for an instant, and then broke into shooting blades of fire. Bud knocked out the secondary switch, and leaped. for the fire ex- tinguisher on the wall at his side of the board. Ike knocked out the motor-generator switch, and leaped at the fire extinguisher hanging at his side of the board. Together they charged. This had been no ordinary flash— not even an ordinary big flash. From one to another of the three 33,000-volt leads it had danced; and now, as the men at the power-house back in the hills turned on the current after the momentary shutting off, a long tongue of arc licked from one to another of the conductors in its wake. Bud pointed the nozzle of his fire ex- tinguisher at the mass of crackling flames and twisted the release valve to the open position. He saw Ike turn a hissing stream of liquid from his extinguisher, miss the fiery target by a yard, wave the stream crazily along the wall two yards from the blaze, and then, dropping the extin- guisher to the floor, fall back two paces, hands over his eyes. “‘What’s the matter?” he yelled above the noise of the fire. ‘“‘Eyes! My eyes!” Ike answered. Don’t mind me! Get the fire!’’ And Bud obeyed. Until there was only a feeble trickle left in either of the two extinguishers he played their streams straight at the heart of the flames. He was a bit dazzled by the glare, but his There was a blinding flash, and a huge, vivid ball of flame burst from the maze of connections and cables behind the switchboard straightened from above Ike and patted a thick bandage into position. “You'll be all right before long if you just keep quiet and in the dark.” Bud, reaching for the motor-gener- ator switch after rigging temporary connections to restore immediate service, turned. ‘‘Ultra-violet rays?”’ “Yes; light rays from the arc, you know,”’ Dr. Vernon responded. “Then why didn’t they get me too?” Bud demanded. ‘I saw just as much -are as he did, and my eyes are weak.” The physician nodded. wear glasses,’’ he countered. Bud frowned, puzzled. ‘Yes.’ Dr. Vernon smiled: ‘‘Any ordinary glasses will filter out the ultra-violet rays. They’re all that saved you.” Bud frowned and looked at Ike, lying back in a chair, his eyes heavily bandaged. Then he slowly removed his shell-rimmed spec- tacles, held them up, “But you sight was not im- paired. Yet,-as the arcing subsided: into a scorched tangled con- nections, he ‘turned and found Ike grop- ing blindly along the wall, ten feet from where his chair was. “Ultra-violet rays, my boy,”’ Dr. Vernon, the company physi- cian, announced a half ‘hour later as he Perhaps you know such a story. wants to print it. Do You Know a Story Like This? dully glowing mass of [NVENTION and adventure have gone hand in hand ever since the time when the first man pushed a log into the stream and climbing astride went boldly navigating. Modern science has ringed the world with romance in which the machine joins with man in playing the star part. If you do the Popular Science Monthly Remember that the story must relate an actual hap- pening; that it must tell of how men overcame adversity, or escaped from danger to themselves, or saved others by the aid of their inventive powers or their skill in handling mechanical appliances. Not over 3,000 words should be used in the telling, and the more you can cut your story below that mark and keep a clear and interesting narrative the better chance your ‘manuscript will have of acceptance. above our regular rates. Payment for these stories will be and carefully wiped a splash of grease from one lens. “‘Glasses, I take it all back,” he said with respectful humility. “You win. After this you can just steam and sweat and streak all you darned please and I won’t kick or say a word, ’cause you sure saved my bacon in this here little old sub-station.”

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<a a See penta a RAE SEP sO crn Contests—But Not for Money Speed and endurance often mean bread and butter as well as sport Photographs © Harris & Ewing The man who can scramble to the top of this great ball and stay there wins. The winner is here perched on top of the ball, while the men who are holding it keep turning it and throwing it up and down, the man on top never losing his place

Popular Science Monthly

A bonus waits for the men who can put together a first-class ship in record time;- these men are trying to win it. As soon as the plate is in place the riveters begin

Here are three one-armed men in a race to see which can dress first. At the Walter Reed Hospital, in Washington, all kinds of queer contests are held by convaléscent soldiers On the last Fourth of July, before a large audi- ence, two gangs of husky convalescents, each carry- ing a spouting fire-hose, approached each other. The first to let go would lose the battle for his team, so they all held on as long as they could

Three patient victims, ready to take part in the bar- bers’ contest. They are about to be given the quickest shave and hair-cut they ever had. The winning barber did his bit in six minutes and fifteen seconds 42° This miner won a contest by drilling a hole fifty-six inches deep in seven minutes. At the word ‘‘Go” he made his pipe connections, turned on the air and water, jumped back to his machine, and began to drill

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Could- You be a Motorman? Are you color-blind? Areyou nervous? Do you think quickly? John Smith wants to be a motorman. In one test Jchn is told to take hold of two upright rods,which suddenly begin to slide. John’s power of decision is determined by the quickness with which he stops them In a test for vision John is given a large iron E mounted on a handle. Another E flashes up on a stand several feet in front of him. John must immediately adjust the E in his hand until it is in exactly the same position. In the picture the E is shown lying on its back 43 — | Next John takes his place in front of a board that shows six trolley cars meeting at a crossroads. He watches the cars very closely. An electric switch is turned on and the cars light up with dif- ferent signals. John must quickly pick the car that is entitled to start first How sensitive are your joints? If you asked John this, he would take oné look at youandrun. Yet this muscular sensitive- ness must be determined before John gets his job. One method of doing this is to have him turn a crank into various posi- tions without touching the edgesof the slot. Every time the crank touches, a bell rings A motorman must find his way in the dark. Here is John with his head in an oblong case, , When he is accustomed to the darkness, he rapidly calls out the names of objects he can see

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me Spd a To determine the amount of carbon in a particular piece of steel, fine drillings of the steel are weighed, then placed in a furnace, heated, treated with oxygen, and the resulting carbon dioxide is collected in bulbs, which are weighed before and after Popular Science M onthly The Shoe that Won't Strike Sparks F you should see a track-walker deliberately step on the third rail, don’t faint. He may be wearing shoes with wooden soles— and wood is a non-conductor of electricity when it’s dry. A new wooden-soled shoe is being turned out by a manufactur- ing company in Norway, Maine. The sole is made of polished maple, basswood, or elm, and is treated with oil to make it water- proof. It is made in one piece and is shaped like a rocker with a groove running around the edge. The heel is of rubber, and Making Steel that Is Hard or Soft LL steel contains a certain percentage of carbon, which largely determines how hard a steel is or may be rendered. For instance, tool steels contain about 1.25 per lent of carbon, while steel rails will average from .50 to .75 per cent carbon. The mild or soft steels range down to -10 or .15 per cent carbon. It is generally necessary to determine the percentage of carbon in any steel. The apparatus above is for this pur- pose. Fine drillings of the steel are obtained, weighed, and placed in a porcelain dish, which is placed inside of one of the two round furnaces at the center of the table. These are electrically heated, bringing the drillings almost to the fusion point. While at this high temperature a stream ot oxygen from the tank in the corner is allowed to pass over the drillings. The oxygen burns the carbon out of the steel, forming a gas, carbon dioxide, which is collected in the bulbs to the left of the furnace. These bulbs are weighed before and after, and the in- Check Your crease in weight re- . presents the carbon Hat, Sir? HE - pros- dioxide. perity of the coat-room boy is threatened by the invention of a me- chanical coat- checker that will guard your coat,’ hat, and um- brella for one ¢ cent. You hang all three on hooks and clamp them firmly in place by means of locking arms, securing them by means of akey. The lock- ing arms are geared together. To get back your belongings you insert a cent in a slot over the itt keyhole, where- \ upon the key will turn in the lock. A mechanical eoat-checker that guards your coat, hat, and umbrella, returning them for one cent is attached to the sole, not by nails, but by fish-line. This fish-line is also used to draw the uppers to the soles, which are cemented to- gether. This shoe has a wooden sole and uppers made of a fabric material; they are joined by fish-line and.cemented together. The heel is of rubber. Thus the shoe is an absolute non-conductor cf electricity Trying Out Our Navy’s Lines EFORE a battleship is built Uncle Sam wants to be sure of her speed. Of each ship a model is built of wood in strict accordance with the lines of the design, and at a reduced scale. This dummy, about twenty feet in length, is carefully tested in a basin specially provided. The wooden models are placed in the basin and are towed back and forth through the water by an electri- cally actuated carriage which spans the water basin and runs on tracks placed on each of the long sides of the tank. The observers who" make the tests occupy a booth in the center of the carriage, where the instruments used in the trials and the various controls are assembled. In this testing basin at the Washington Navy Yard, the second largest in the world, models of all naval ships are tried out carefully to guard against errors of constructior 44 wai caiuiiale are

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April, 1920 Buy Yourself an Ink-Stick LOP! You’ve ruined your letter with a great ink-spot. Ah, but there is a new inkless pen. Init ink-sticks are used. The stick fits into a groove in the pen. Moisten the stick in water, and the stick will dissolve enough ink to write a full-paged letter. This ink-stick was invented by Dr. John C. Olsen, a chemist connected with the Polytechnic Institute of Brooklyn. The pen- holder designed for the ink-stick has a chamber at the end for holding two extra sticks. Thus you needn’t worry about the supply running out. The manufac- turers say: “It is the only pen that has been Ink-sticks instead of liquid ink are used by this pen; the stick fits into 1 a groove in the pen, and is mois- tened with water weaned from the bottle.”’ They Built Their Air Flivver SMALL one-man carrying biplane has been designed and built by students of the Aviation Mechanics School at Great Lakes, IIl., from the usual materials, wood, wire, and canvas, and equipped with a two-cylinder air- cooled motorcycle engine. They also flew it successfully. It has a wing spread of not more than sixteen feet and a total weight of three hundred and fifty pounds. We used to despair of ever seeing a successful ‘‘airmotor’”’ of minimum weight. These students simply purchased a bicycle engine. No material is found in their structure that was not available years ago. Thus they have strikingly revealed what all airplane inventors neglected in the early days. They saw that the most obvious requirement is a body and wing structure that cleaves the air with a min- imum of effort, with everything hidden in that ‘‘body.’” The aviator in the bow of this seaplane has just hurled down a white pigeon—folding the pigeon’s wings close to its body so that they would not open before the bird cleared the airplane The Seaplane’s Carrier-Pigeon HE aviator in the bow of the seaplane reached over the side and hurled out a small white object. It shot straight down for about ten feet; then it opened, circled a few times, and disappeared. It was a carrier-pigeon. Before the aviator let go he made sure that the pigeon’s wings were tucked in close to its body so that they wouldn’t open up before it had cleared the airplane. When the pigeon had righted itself and taken its bearings, it headed straight for home. In spite of modern invention, the carrier-pigeon has lost none of its business. In fact, it is more in demand than ever. It is used by forest rangers to report fires. During the war pigeon raising and training was carried on near the front. Many a despatch-bearer started out with a pigeon in a basket on his back. Not only did the soldiers use pigeons, but practically all aviators made sure that there This one-man biplane is.the product of students at the Aviation Mechanics School in Illinois. Its weight is three hundred and fifty pounds and its wing spread is sixteen feet 45 airplanes before they started out. One striking tale of a pigeon ~ || saving the crew of a seaplane at the cost of its own life is told by the pilot of a British airplane. The seaplane was making its way home after a long-distance trip, when it ran into a fog-bank. A few minutes later the engine missed, and then stopped alto- gether. The pilot was forced to land in a rough sea. He wrote down his approximate position, slipped the paper into the tube attached to his carrier-pigeon’s leg, and released the pigeon. He had little hope of rescue because of the blinding fog. The pigeon battled its way home. It died im- mediately after, but the crew of the airplane were saved. was a pigeon tucked away in their a } |

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Se They are Going West for a Separation HESE two are really one, though they hope soon to be separated. Not that they love each other less, but they find life together very uncomfortable. They are joined just below the shoulder and have been that way throughout their thirteen years of life. They are the sons of Mr. and Mrs. Marco Godino, Filipinos now living in Washington, and they plan to go to a surgeon in the West to be operated on. Fortunately, they are very good friends as well. as brothers, and their life together has not been_un- bearable. Their chief difficulty is encoun- tered in walking. One of them must always go backward. How do they sleep? We have given up trying to guess. Abnormalities of this kind are due to deviation from the normal development of the embryo. Just why these deviations occur has not been discovered. Usually dwarfs, giants, and deformed children are born to normal par- ents. But should two similar freaks mar- ry, it is believed that the children would inherit the freakishness. © Press Jllustrating Servis You Would Probably Be Arrested for This F you used the American flag as a sheet to cover yourself with, someone would find it out, tell a patriotic society about it, and they would loudly protest. On the contrary, a pony that does the same thing on the stage is loudy applauded. The pony’s name is Julius Caesar. He fires guns, adds and subtracts figures, and always finishes his act by waving the American flag and then crawling under it. Julius was an incubator baby. He was kept alive for eleven days in a box lined with pillows, and carefully fed with milk at regular intervals, before he was pronounced normal. © International Film Service Co. Apricot Pits for Dyes MERICAN chemists have found that apricot pits are very useful in dye-making. The pits are spread out on the ground to dry, then shipped to fac- tories, where the kernels are removed. The kernels are then crushed to extract the oils and chemicals, from which the dyes are made. During the war the shells were used in gas-masks, and now they are being _used as fuel. Popular Science Monthly Opening the Door Connects You with ‘‘Central’’ WE have heard about making ships out of concrete, and other innovations in the use of con- crete. Here is a brand-new use for this vastly serviceable material. Railway telephone booths, numerous along the lines of many railway sys- tems, are likely to become stand- ardized in the form of neat little structures of concrete, just large enough to accommodate one person. The new concrete telephone-booth is so arranged that when the door is unlocked and opened the connection is automatically made and the time of wait- ing for “central” is minimized. When the door is closed the connection is broken. A ‘panel door with glass provides suf- ficient light for the interior. These con- crete booths are more ornamental in the landscape than some of the wooden struc- tures. When an emergen- cy call must be made, there is no delay in getting the message through. The rail- way employee rushes to the little booth and has merely to unlock the door and open it. When he takes down the telephone he finds the operator all ready. Dae | , WOH iyi, ‘a i Tiny Model Houses Show What You’ll Live In “FQUILD your own home!” You are always seeing signs like this one. Did you ever try it? Those who have know that a house seldom turns out the way it was expected to. The plans seem so different from the finished product. For this reason, many architects now build a small model of the house planned and set it up in surroundings identical with those in which the house will be located. The 46 materials and colors used in the model are the same as those of the house to be lived in. Thus you are able to judge whether it is the house you really want. Such a little house is shown below. Though at first it looks like the makings of a Japanese garden for go)dfish to play in, a careful study of it will con- vince you that it is a typical country house. ee —

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gear into reverse and the wheels turn round, taking the car back- ward until it rests on all fours. It’s a much simpler operation than launching a ship. Use a Pulley to Hoist Your Flag SUALLY a pulley line is hung ‘from somebody’s kitchen win- dow to somebody else’s, and on it is hung wet wash. But pulley lines are good for other things besides wash — flags, for instance. The flag shown below rides up and down on a pulley line—hal- yards they would say in the Navy. This is a great improvement on the usual flag rope, which has to be secured in place, awning fashion, every time the flag is lowered or raised. By using a pulley, it is no trouble at all to lower the flag half-mast when some important public person is mourned. As yet, this flag-pole is in its infancy, being small enough to fit on - \. a library table. : } The Launching of an Automobile HEN an automobile is launched, it is assembled on trucks that are mounted on wheels that run in tracks on the floor. When the car is ready for launching, the motor is started and the trucks are wheeled backward until the rear wheels of the car strike an inclined path. Then the man at the wheel throws the iq ~~ ‘ Be * “i / » % \ bat x . NM Barberry Chickens in a Canadian Garden PACE trimming yew, barberry, white-thorn, and golden holly trees so that they cleverly assumethe shape of fowls and other objects! Thirty years’ experience in the art has enabled the man whose hobby this has become to reach a high state of perfection in the work. Inthe gardens of Mr. W. J. Pendray, at Victoria, B. C., the visitor is en- tertained by a sight of such marvels of tree-trimming. Tree-trimming is not a task for the amateur. It re- quires years of diligent and studious attention to the particular requirements of the trees. When a definite shape is the aim of the gardener, successive trimmings from time to time must be done with this ultimate form in view, and at last the leaves seem almost to grow to accommodate the trend of the gardener’s conception. © Publishers Photo Service with a fan-shaped arrangement forming a steel frame. tremity are two strong spikes, each fitting into a groove of the track. Attached to a street-car, the apparatus is shoved along How They Clear the Rails in Berlin A* ingenious arrangement for cleaning ice, snow, and dirt from the rails of a street-car system consists of a metal rake, At its ex- the track, the spikes digging out any obstruction of dirt or ice. Ordinarily, scores of men with picks: and shovels are needed for this job. This Poor Fish Has No Tail OOR fish! What constitutes a poor fish, anyway? Obvi- ously the carp shown below is one; for he hasn’t any tail at all. And the general belief is that he didn’t lose it in a fight, but was born without it. Think of the difficulties this fish must have encountered in learning to swim! A fish uses its tail both as a rudder and as a propeller. Without either the carp was decidedly handicapped and had to overwork his fins. Perhaps this lack of a tail led to his being caught.

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— ey SNS Sa NS ET om HE uncanny property that X-rays have of penetrating substances, Popular Science Monthly Now the X-Ray Has Gone into If you suspect a hidden corrosion in reason to think that a workman is whether they are transparent or not, is now turned to practical account. If the X-rays can discover just where the safety pin lodged that baby swallowed, why shouldn’t it also explore the hidden interior of a casting or a piece of timber for defects? So British scientists have reasoned, with results shown in tke collection of pictures on these two pages. The X-ray has been used to dis- cover whether there is a flaw or crack in a metal weld.’ The steel manufac- turer has radiographed his castings and forgings in order to localize the blow-holes and other concealed im- perfections. The airplane inspector, with the aid of the ray, has searched for hidden faults in worlemanship that outwardly satisfied the eye. Here was a casting for an air- plane engine that would have passed any inspector. Major J. Hall Edwards, of the Royal Air Force, turned on the X-ray. And what did the X-ray show? A large blow-hole. Much work had been done on the casting which would have been saved had the X-ray photograph been made earlier. But the experi- ment proved that the time has come when the careful manu- facturer must add the X-ray to his inspecting equipment In the box resting on the floor is an X-ray tube. Upon it rests a wooden member that is to form part. of an airplane. Upon the -wooden member a fluorescent screen 1s placed. The man who is bending down is looking at the fluorescent screen for defects in the wood. This is the quickest way of ex- amining wooden aircraft parts with the aid of the X-ray for defects eee genes A brave man’s life was saved when this X-ray photograph was taken. The internal strength of this block was badly fitted; each of the screws had split the wood; the work was alto- gether discreditable. And so the piece was rejected. If it had not been for the X-ray it might have been a part of an airplane which would have collapsed at a critical moment 48 The X-rays showed a defect in the gasoline-feed canal of this carburetor, thus saving hours of effort in locating the trouble

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April, 1920 the armoring of a cable, if you have concealing mistakes, turn on the X-ray the Business of Manufacturing Here they are assembling the X-ray apparatus that is to be used for inspecting airplane timber with i the aid of fluorescent screens. The picture opposite shows how the fluorescent screen is used. The chief faults to be looked for are spiral grain (in spruce and in substitutes), knots, resin, pockets, compression shapes, incipient decay, grub-noles, and very light woods If you wonder whether there is a hidden corrosion in a gas-cylinder, af you suspect that gutta-percha has been adulterated, if you have reason to believe that a workman is cleverly concealing kis mistakes or his care- lessness—turn on the X-ray. When a strut or spar of an airplane is completely covered. with fabric, veneer, or plywood, it is easy enough ° to fool the inspector. But you can’t fool the X-ray. The detection of one such fault with the X-ray resulted in the rejection of dozens of completely - finished main wing-planes in “a” British factory. In one fuel-tank the rivets were found to have heads on the outside only. Cracks in the airplane timber are sometimes cleverly hidden by gluing a shaving over the sand- papered surface. _ The eye overlooks them, but not the X-ray. In every well conducted aircraft factory you will find a notice that reads: ‘‘A concealed mistake may cost a brave’ man his life.” In spite of that, mistakes have been concealed. Now comes the X-ray to protect the flyer. Here we have en X-ray photograph of a fuel-tank for an airplane. Its defective riveting and soldering stand out glaringly tbe one sh The wooden skid of an airplane was cut off too short to fit into its socket. In order to make up the length, a piece of packing (here marked with an arrow) was introduced into the space below. The workman responsible thought he could “get away with it”; but the X-rays found him out 49 Major J. Hall-Edwards of the Royal Air Force photographed loaded rifle cartridges to show how the distribution of the lead would influence their flight. In the center is the old round-nosed bullet

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Nw eT La ae eae cena aanarecttenctinnwemamenaaiistili aie’ SIS, PSNR eit tiara = Dramatizing Geography Popular Science Monthly As history unfolds itself on a forty-foot globe T a luncheon-table in San Fran- A cisco a dozen men—university graduates, most of them—talked about great-circle sailing. “The great circle from Panama to Yokohama,”’ said one of them, “‘passes west of San Francisco from one hun- dred and fifty to two hundred miles.” “‘You’re wrong,” retorted another. “The circle will pass east of San Francisco at least two hundred miles.”’ No one believed him. Even a small school globe did not convince them. And so the objector started to prove his point by means of a Mercator’s projection. To his astonishment, no one seemed to know how charts are made and the real meaning of merid- ians and parallels. The man who thus set out to prove his contention scientifically was Marsden Manson, an engineer. As a result of this experience, he invented a system of breathing life into geography. Instead of learning it from dead maps and dull text-books, he would teach it as a living, changing subject, which in- deed it has been in the last five years. Mr. Manson makes a veritable mo- tion picture of geography. It is pro- duced in a kind of theater. Out in front is a stage. Presently the cur- tains part. A huge globe is revealed— a globe forty-two feet in diameter, or one one millionth as big as the earth itself. The globe becomes animated. All Europe seems to twist and writhe. You see it literally in the geographical throes of the terrible war. Germany pushes her boundaries into Russia and Belgium; Austria her own boundaries into Rumania and Italy. Back and forth the boundaries shift. And then you see revolution tearing Russia apart. Looktothe west. The armis- tice has been signed. You know it because Alsace and Lorraine suddenly attach themselves to France; parts of Austria become Italian. Back of the auditorium is the hous- ing of a motion-picture projector. The lamp projects on the globe a film which shows very realistically what men have been fighting for, even though it is but an animated map. Also the lecturer’s assistants on the stage operate mechanism for rotating the globe, and for varying the inclina- tion of the axis realistically—which, with the cooperation of the light-pro- jecting operator, illustrates the changes of day and night and the seasons. _——-—— Animated geography teaches as no text-book can. You see a moving picture in which contour lines play exciting parts: some are villains, some heroes, some bullies, and others protectors of the weak 50 cal arse a RNG. ne Faitacrs A

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April, 1920 How to Get the Lid Off Without Breaking It OU have heard a good deal of grumbling about the high cost of eggs, but has anyone told you about the high cost of egg-crate lids? At the present time they are worth five cents each, and therefore should not be ripped apart when the crate is opened. Recently there has been invented will pry the lid off a crate without breaking the lid at all. The implement consists of a handle with a broad, flat blade at the end that is as wide as an ordinary crate lid. A He’s prying the lid cff a crate cf eggs with a new _ crate-opener that will nct break the lid. It consists of a flat blade and handle mcunted on a rectan- gular frame fcr support Is This Waist a an Egg-Crate a crate-opener that rectangular frame is attached at one side of the blade, and the opposite side fits against the crate. The frame acts as a fulcrum for the blade when you. press down on the handle. The invention enables one to re- move the lid of crates without the damaging results that are usually obtained when one tries to pry off the boards with a hammer. The wood splits, spoiling the crate until new boards can be obtained. Waste? N first glance you are apt to think that the lady in the picture shown here is wrapped up in the parlor curtains; but when you look more closely you notice the great beauty of the lace, and realize that it is out of the curtain class. As a matter of fact, it is a waist and it cost the sum of hirty-fve hundred dollats.‘ ~ It is made of old rose- point lace, and it came from Belgium, The lace had lain in the dark for so many years that it is now- the color of old ivory. In its present waist form it is held together by ropes of tiny pearls and is draped over a lining of silver cloth. You can buy lace like this by the yard—that is, if you can pay a thousand dollars a yard. It is interesting to note that the regions where pic- torial art-first flourished — Italy and Flanders—were Se ae the ones in: which. lace- tonal Film making was originally de- °° veloped. In the seven- teenth century, nunsin many places established lace schools where the peasant women learned the art. The most expensive waist in captivity is shown here; it cost $3,500. The lace used in the waist is very old and it was made in Belgium 51 Inside the telescope a photographic plate is inserted and is exposed for several hours, while the telescope moves slowly to keep up with the stars. On one photograph taken by this telescope four hundred thousand stars were counted Taking the Stars’ Pictures ANY times when you were young you tried to count the stars; but at last you gave up trying. Yet those stars have been counted by astronomers, and are con- tinually being recounted in order to find out whether any small ones have been overlooked. But the work is done on photographs of the sky that were taken at night. Above you see the sixteen-inch double telescope located at Harvard University that is used especially for photo- graphic work. A plate is inserted at the lower end of the telescope and is exposed for hours. All the while, the telescope moves slowly to follow the stars as they travel across the sky. On one photograph four hundred thousand stars were counted. Owing to the large size of the plates, the first photographs taken were somewhat blurred at the edges. To overcome this the plates were sucked into a curved form by air pressure whil in the holder. Thus all points were equidistan from the focal point of the telescope. Over-Exposed Blueprints HEN blueprints have been too long ex- posed and would wash out too dark, the defect can be corrected to a great extent. First, wash the prints in running water until all the blue liquid clears away. Then soak the prints in a solution made up of one teaspoonful of hydrogen-peroxide to each quart of water. The soaking should continue until..the proper color appears. Then wash the prints again in clear water. The process may be carried on while correctly exposed prints are in the same batch. | | } t A :

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eT ARSE Oe. oe ey ee ad “The Man that |" Hath No Music | , in Himself—” He stands alone in a world of music Music and the dance go hand in hand. In the white man’s land the music is often furnished by an orchestra of many pieces. It frequently in- spires very beautiful dancing © Press Illustrating Service Popular Science Monthly == q SS 4 © Press Illustrating Services Tum, tum, tum! The Moro boy pounds a cymbal while his sister dances. The cymbal and the drum are the favorite in- struments of the Moros—one of the Mohammedan tribes in the southern Philippines Two pieces of gas-pipe, an old tin funnel, and some axle-grease will make, we are told, a “unique tone-producer.’’ A ma- rine made one and called it his bazooka. With it he furnished P e ene . teal jazz at a recruiting station © Press Illustrating Service The Indo-Chinese laborers who were in France during the war made their own violins. A piece of wood, a tin can, and some wire were all they needed. While *‘Music hath charms to soothe the savage breast.”’ This religious healer of Siberia must have known it when he decided to carry a drum and bone drumstick with him. His charm is drum - beating to drive out evil spirits the musicians played the gang stood round and sang Siamese twins—not the famous two-in-one—are shown at the right. One of them is playing on a bamboo flute. There are seven reeds to the flute, and they produce very beautiful music—or that is what the Siamese think 52 ee iacisiaidice

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April, 1920 Giving Big Ben a Bath -~ He ticks on top of England’s House of Parliament Bankes This is Ben’s bell. If yo ihe u look at William (the man with the mustache, standing at the left of the clock) you will appreciate the size of the bell — ie oF aE is Ben’s face, as you see, is exposed to all kinds of weather, and in consequence needs to be washed regularly.. Lon- don’s Big Ben is a very famous clock ent enna With a lighted candle and a soapy wash-cloth, Algy enters the room of the pendulum. In spite of the fact that the pendulum is well cloistered, it.does collect some of the dust and dirt of the world What makes the hands go round? All these wheels and chains—commonly known asthe ““works.” They must be oiled and greased regularly if they are to function properly Manicuring him is not an easy job. He has four faces, and therefore eight hands. One of his minute-hands, fourteen feet long, is being removed here. If you look down at the wagons in the street below, try not to grow dizzy or you may toppleover ~ preventer

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© Press Illustrating Service |Fear not; the Capitol is not on fire—just plain dirty. The fire department is giving it a bath The Capitol Gets a Bath HE Capitol building was particularly dirty this year, somewhat like the gasradiator. You fill the radiator with water, but instead of turning on the gas you press an electric button. The cur- rent passes through an elec- tric heater located below the radia- tor; a resistance winding heats up when the current passes through, and this heat is transmitted to the water in the radia- and needed a very thorough scrubbing. Somesay it tor. was due to the great amount of ‘“‘mud-slinging’”’ in Con- gress, but we believe that it was honest dirt caused by the unusually large amount of rain that fell during the year. Indifferent to causes, the fire department brought out its most powerful hose and gave the Capitol a thorough bath. The firemen washed the roof, the walls, the pillars, the statues, the steps, and if the build- ing had had ears they would un- doubtedly have washed it behind the ears, too. What Is Wood Alcohol? EWSPAPERS report, “‘Scores die from drinking wood alcohol.” What is wood alcohol? Isit a relative of the alcohol contained in wine, beer, and distilled liquors? Both belong to the carbon-hydrogen compounds of similar molecular structure forming the alcohol group, but are radically unlike in derivation. Drinkable alcohol is a product of the fermentation of vegetable sub- stances containing sugar, starch, or dextrose; while wood alcohol is ob- tained by the destructive distilla- tion of wood. Pure wood alcohol is a colorless, clear, and mobile liquid, highly inflammable, and of an un- pleasant odor. In the pure state it can easily be distinguished from wine spirit by its odor, but when it forms a comparatively small part of a mixture containing flavoring mat- ter, its odor is obliterated. Diluted, it resembles in taste the { cruder varieties of wine spirit; but } even in small doses it is extremely ‘ poisonous, causing death or blind- ness. In the process of digestion wine spirit is split up into carbon dioxide and water, both harmless; while wood alcohol is changed to formic acid, formaldehyde, and other poisonous substances. Thus steam heat is obtained without the neces- sity of piping a house. Popular Science Monthly An Electric Steam Heater F you have ever lived in a suburb you surely have met the steam radiator operated by gas. with water and turn on the gas below. The water soon boils and you have steam heat. In France they are using an electric steam heater that is You fill the radiator eri wees ri ane You fill this radiator with water, press an electric button, and have steam heat Will She Take Home the America’s Cup? HE looks like a fish out of water—a man-made fish; for she is the Shamrock IV, Sir Thomas Lipton’s challenger for the America’s Cup. After lying housed for five years the yacht was recently put on the ways for an overhauling, and racing sharps got a look at her under-water build. The feature that chiefly attracted their at- tention was her unusual length of keel —thirty-five feet, or more than twice that of the Resolute, probably one of the defenders. The average vertical thickness of the sixty tons of lead is about two feet, which means that she carries the center f g This strange-looking object is the hull of the shamrock IV, with which of gravity very low, lower than her rivals, the Resolute and the Vanitie. And that means great ‘sail-carrying capacity; so it is no surprise to learn that she is to have a spectacularly lofty rig. But the long keel means a large increase in wetted surface, and the experts say that, while she will be fast in fresh winds, she will be at a disadvantage in light breezes, when the amount of wetted surface is important. ‘‘A dangerous contender in a blow,” say the salts. ” Sir Thomas Lipton hopes to capture the America’s cup this summer 54

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April, 1920 Follow the Sound of the Horn to the Fire ONK! A horn sounds from every other block down the street from above each fire-alarm box where it is fixed—a loud, continuous noise. The Atlantic City Fire Department has attained a record for its great speed in response to an alarm, and credit is given to the new system. When an alarm is turned in, the horns above the boxes at every other street down the main thoroughfare begin blowing, and at the sound all traffic stops, clearing the way for the fire-engines. Above the fire-box is a horn con- nected with the alarm, to warn people of the coming fire-truck The EAR Faridpur in Bengal is a date- palm which bows down as if to prostrate itself when the temple bells ring in the evening and which rears its head.again in the morning. The tree must have been displaced by a storm; for it now grows at an inclination of about sixty degrees to the vertical. Sir Jagadis Chunder Bose, director of the Bose Research Institute of Calcutta, is known all over the world for his remarkable Birds eat most of the insects that would destroy the crops; for this reason farmers Ought to construct houses for the birds Build More F the twittering birdies wake you at dawn don’t growl at them. Rather, be thankful that they are wide awake and ready to do a full day’s work. For the birds eat the insects that would otherwise destroy the crops that you expect to eat. We are told by a well known entomologist that if birds became extinct the world would be uninhabitable for man. Therefore build bird-houses and hang them up wherever food grows. The floor surface of a bird-house for wrens and other small birds should be about four square inches, and the height ten inches. Bluebirds need a house slightly larger. Neither wrens nor bluebirds nest in the same place The houses should be of a size to ac- commodate the birds they are intended for, and when ready hung in trees Bird-Houses twice, for which reason it would be wise, when building houses for them, to construct several compartments, so that the birds can move from one to another each season. The entrance hole for wrens should be one and one quarter inches in diameter. Six by six by six are the dimensions for the home of the song sparrow and for the majority of birds, the entrance hole varying with the size of the bird. Ninety-five per cent of all insects are eaten by birds. In the stomach of one swallow two thousand mosquitos were found, and in their midst were several flies and cucumber-bugs. A closely watched red tanager was «seen to eat thirty-five moths in one minute! Secret of the Praying Palm these recording instruments. He said to the palm as it were: “Here is a pen: tell me why you pray.” The owner of the tree objected to this proceeding. But Sir Jagadis re- moved his misgivings by telling him: “The instrument will be attached to the tree by one of my assistants, who is the son of a priest.” And what did the praying palm write? In the first place, all trees, all plants move. That Sir Jagadis proved long ago. Hence, the praying palm is nota miraculous tree. Its motion is more noticeable than that of other growing trees and plants because it is inclined to the vertical, so that the movement of trunk and leaves became easily noticeable by reference to the ground. All plants are sensitive to light, but Sir Jagadis proved that light is not the cause of this “‘praying.”” What then? The rise and fall studies of sensi- tivity not only of living plants but also of metals. Sir Jagadis has in- vented instru- ments of amazing _delicacy.. Ina sense, he gave plants a pen and let them express themselves. Sir in. temperature during the day. The record of movement of the tree was found to follow the fluctuations of the temperature at different seasons with astonishing fidelity, a rise of a few degrees being Jagadis provided the praying palm with one of In the morning the praying palm with uplifted head greets the sun 55 But as the temple bells ring in the evening it bows down as if in prayer followed by a fall of the trunk, and vice versa.

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nuit se — oN” nse Germany is now making sausage skins of silk; these young women are coating them Silk Stockings for Sausages O you eat the skin of German sausage? Don’t doit: the Ger- mans are making the skins out of silk now. The silk is woven like a seamless stocking, and is then coated with what the Germans call a “‘subtle mass”’ re- sembling what we call the “dope” applied to the linen of airplane wings. It gives the silk sausage stocking solidity as well as elasticity. The meat is stuffed into the stocking and the resulting sausage is dried and smoked, after which the meat and the skin cling firmly together. Above you see a room full of sausage skins hanging from the ceiling. They are being coated by the girls of the sausage factory. He Enjoys Using This Riveting-Machine you talk of riveters, rivet-heaters, and their helpers. _ But is it so hard? Look at the man above. His job is heating rivets, and it is really no worse than toasting marshmallows. In fact, he seems to enjoy using his new electric heating- machine. A transformer is mounted on the rear part of.the machine. Two heavy copper bars connect it with two heavy air-cooled electrode blocks of cast copper located in the front part of the stand. Under these two blocks, which can be raised or lowered separately by individual foot-levers, is another copper block that holds the rivets in a vertical position and forms the other electrode. In operating the heater, two rivets are placed in the vertical holes in the lower electrode. Then the upper electrodes are permitted to drop into contact with the heads of the rivets. The tap switch mounted on the rear legs of the stand is closed, and the current, passing from one electrode to the other, heats the rivets between them to any degree desired. The amount of current is regulated by a rheostat connected with the switch. With one of these heaters one man may bring five “ A HARD life!” That’s what yousay when = PUDOTSS TIVCtS te “hour - Popular Science Monthly The Sword of Pershing HEN the people of Missouri decided to’ present General Pershing with a memorial, they made it a sword of gold, studded with jewels. The saber is of the finest steel, but the hilt and scabbard are of eighteen-carat green gold. Rubies, diamonds, and sapphires are set in hilt and scabbard. The green gold of the scabbard is designed to resemble laurel wreaths, outside of which the General’s military record is inscribed. Per- shing’s four stars, denoting his rank of general, are wrought in platinum and encrusted with blue and white diamonds. Military experts say that this sword is the most exquisite design ever produced in an American shop, if not in the world. —_ Pershing’s sword, given to him in honor of his work in the Great War, is made of gold and studded with jewels They Will Be the Biggest Guns Afloat HE largest guns afloat will soon be the boast of the United States Navy. There are now building 190 such sea monsters, 16-inch guns, each with a muzzle energy of 115,000 foot-tons. They fire projectiles weigh- ing 2,100 pounds, so that the 190, if shot off at once, would hurl nearly 200 tons of metal at the enemy. And to doit they would burn 125,000 pounds of powder in about one twentieth of a second. The power of this terrible discharge represents energy enough to lift a battleship to the height of the Wash- ington Monument. It is said that these guns are not only of greater power than the 14-inch, but last longer. juiielgil The Mammoth was designed by the eight passengers instead of a load of 56 _ ina _. ah, fe ne fete SS aS ee ee | ll lle Ko vee! east arts: 15 ea x

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April, 1920 There are more than a thousand diamonds in this crown and cross The “Ad” of a Thousand Diamonds ORE diamonds and silk shirts are being bought today than ever before in history. And most of them are adorning the ten-dollar-a-day workman. The result of this great demand has been a two hundred per cent increase in the price of diamonds in the last few years. Yet still the workman clamors for more. A prosperous New York jeweler hung up in his window a cross fourteen inches high and a crown seven inches across the base made up entirely of diamonds! More than a thousand diamonds were used, their aggregate weight being five hundred and ninety-five carats. The two pieces were valued at four hundred and fifty thousand dollars. The crown contains two hundred and one carats, and the cross is made up of three hundred and ninety-four. Class Distinction in the Air UY your ticket, first or second class, take a seat in the electrically lighted and heated fuse- lage, and your travels through the clouds will demonstrate the progress of aviation in the past ten years. Class distinctions have gone flying; that is, they have taken to the air, now that an airplane has been built with accommodations for first and second class passengers. Blériot, the audacious aviator who first flew across the English Channel in a monoplane, designed this latest of flying giants. The fuselage, or body, has two decks, an upper and a lower. class passengers view the scenery through the twelve windows in the side of the upper deck, while sixteen second-class passengers occupy the lower deck and have six windows at their disposal. The new type Mammoth was de- signed to be a bomber; but the war ended beforethema- chine was perfected. Twelve first- A change in design madeit adapt- able for commercial use, and now it carries passengers instead of bombs, A front view shows the enor- mous size of the airplane compared with the two small biplanes under its great wings, which have a spread of ninety feet. The top plane is straight, while the lower plane slopes up from the center toward the tips to produce what is called a “dihedral” angle, the purpose of - which is to give stability in flight. . Four Hispano-Suisa engines, of 300 horsepower each, are mounted in separate power “eggs” driving sepa- rate tractor air-screws. In the center is the fuselage, the pilot’s seat being in front on top. This great mechanical bird, can fly seven continuous hours at eighty miles an hour. It has little to fear from forced landings, since it can stay in the air under the power of its en- gines; it also has eight large landing wheels, Showing the windows in the side of the fuselage, the upper row being used by the first-class passengers, the lower row by the second-class passengers English as a bomber. The. war ended before it was perfected, and so it was rearranged to carry twenty- bombs. Its great size may be realized by a comparison with the two small biplanes under the wings 57

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eet ee ee 9m ERS oer a Popular Science Monthly Music as She Is Played on Electric Anvils RAND operain the high school} The enterprising students in the Lafayette School of Oakland delighted an audience at a school entertainment by rendering the “Anvil Chorus” to a full chord accompaniment, making use of a clever electrical arrangement. The anvils were full-sized reproductions of the blacksmith’s equipment, camouflaging a set of inlaid pipes. Not only was it necessary to pro- duce harmonious sounds when the anvils were struck, but realistic Many families would be glad to live in a hog-barn like this. What a Home - Pigs! O be sure, pigs aren't particular about the kind of house they live in as long as they get plenty of swill to eat. But successful pig-owners are the ones that make sure their pigs have plenty of light, fresh air, and a clean place to sleep in. One pig-raiser built his pig-pen on the side of a steep slope, and, to insure his pigs plenty of sunshine, put eight windows in the sunny side of his slanting roof. The building is sixty feet long and twenty-two feet wide. The walls and floor are made of concrete and the roof is covered with the best grade of roofing paper. The hog-barn is lighted by electricity and a stove heats it in very cold weather. There are two fresh-air ventilators in the roof. Alas! it is to be feared that the pigs don’t appreciate their beautiful home. Speeding Up the Water-Wheel S for water-wheels, maximum power from minimum water—that is their goal. Will straight blades help them attain it? James Charles, of Richmond, Ind., says no; and so he has invented a water-wheel with curved blades. These blades are It has concrete fioors, stove heat, electricity, and windows all along the roof to let the sunshine in sparks must be thrown into the air. A stage cable, outfitted to plug in on the circuit, was used in con- nection with carbon lamps as volt- age-reducers, furnishing an abundance of sparks. The player in the center has to learn the pitch and position of the seven tones of the scale, and likewise memorize and carry his part in the celebrated chorus from “Il Trovatore.” The High School “Anvil Chorus.”” The hammers make contact, and electric sparks fly, vividly imitating the sight as well as the sound of the smithy’s art all fastened to a large central hub, and the di- rection of the blades alternates : one curves to the left and the next to the right. The blades are joined at the ends, and they thus assume snakelike formation. When water hits the wheel, it must travel through this winding course before it gets out; and thus its force is felt for a longer time than if the straight-bladed wate--wheel were used. Mr. Charles has made actual tests of this power by turning a hose on a miniature water-wheel having straight blades and later hosing acurved- bladed wheel of the same The inventor of the curved-bladed water-wheel turned a hose on it, and later hosed the straight- bladed wheel; the curved one turned faster, generat- ing more power « eo size. He says that he got far more action from the curved one. to a hub. Two model water-wheels: the one on the left has straight 7 blades; that on the right has curved ones that are fastened Which one will generate the more power? 58

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April, 1920 Awake to the Sound of Sweet Music 66 H, how I hate to get up in the morning !’’—wouldn’t you rather hear that sympathetic tune than the alarm clock each morn? Or perhaps you prefer a hymn ora waltz? Ifyou own a phonograph and a clock like the one shown, waking to the sound of music becomes possible. You choose your record. the night before, put the needle in place, wind up the machine, and switch on the lever. But before it has gone as far as the music you clamp down on top of the record a metal arm that extends out from the back of the clock. This arm is worked by a button on the face of the clock. Here’s where the clock plays an important part. You set the alarm, just as you would in any other alarm- clock. But, instead of sounding an alarm at the given time, the clock lifts the metal arm from the record, the record turns, and you are wakened by your favorite musical selection. Set the alarm clock, clamp a metal arm down on the record, and when it’s time for the alarm to go off, you will hear sweet music © Press Illustrating Service The sign tells the tale. You wait on yourself and tip no one — © Press Illustrating Service At. the small price of fifteen cents you can go into this shop and shave yourself. Necessaries like the razor, soap, and brush will be supplied without extra charge. Such luxuries as hair tonicand powder may be had at areasonable price. Don’t be alarmed at the policeman’s presenceé—he_ is simply curious about the innovation The “Help Yourself” Barber Shop “CN HAVE, 15 cents.” In big black letters this sign appears on the window of a barber shop. You walk in, pleased with the reduced rates, and there you see several men lined up in front of mirrors, and discover that they are shaving themselves. There isn’t a barber in sight! When a barber shaves you, he does it with pomp and ceremony, which is all very well if you have plenty of time. Then, when he has put on the finishing touches, he charges you thirty-five cents, and you generally tip him a dime besides. Compare the time and money spent in the ‘‘shave yourself’ and the “get shaved” barber shops. When you shave yourself, you tip yourself and do the whole job rapidly. The soap, brush, and razor are carefully steril- ized before they are handed to you. If you need a hair tonic you may have as much as you want for an additional fifteen cents. Other luxu- ries, such as powder or cold cream, may be had at a very small extra charge. Razor-makers spend thousands of dollars in advertising. ~Would it not be a good idea for them to establish cheap “shave yourself” barber shops in which their razors would be used exclusively? Thirty Thousand Dollars Went into This Eagle REENBACKS or yel- lowbacks that were ac- cidentally torn in the money room of a bank have been put into decorative use by A. J..Bame, of New York city, in the making of a mosaic 2214 by 2814 inches. The original would have an intrinsic value of $30,000 if it were made from good bills. More than two thousand pieces are contained in the design, and Mr. Bame put into the task all of his spare time extending over a period of ten months. Each piece of the mosaic had to be ironed out and cut with small scissors. Many t ere we pair of tweezers in order to cut them. The very lifelike eye of the eagle was made from the figure 2 with the bottom cut off, while the beak was from the yellow back of a twenty-dollar bill. The little designs found on five-dollar bills were used for the feathers in the eagle’s head, and the neck feathers came out of two- dollar bills. The red and blue stripes in the shield were obtained from the colored seals on ‘the bills, while the white stripes and the stars were simply a background of vad ae white paper, the stars hav- of the pieces were so small ° that they had to be held by a A mosaic design pieced together from cut-out bits of paper money accidentally torn in the money room of:a bank 59 ing been cut out with a pen- knife.

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Popular Science Monthly © International Film __ The largest Bible in the wcrld is being written by the people of England to help the religious drive cf 1920; the verses are written, signed, and pasted on the three-foot pages of the book In Great Britain Everybody is A sponge a wetting mantane flaps Rewriting the Bible ised ueish wireumunr serene aaa WELVE thousand English men and women are rewriting the Bible. Not that they don’t approve of it in its present form: they are simply get- ting ready for the religious drive of 1920, to be known as the Bible Crusade of England. This Bible will be the largest one in the world—more than five feet high and three feet broad. Each contributor has been assigned a set of verses that he or she will write and sign. The King and Queen are going to do their share of the work. The book contains one hundred and seventy-five sheets of stout paper boards on which the verses will be pasted. It is sewn with twine and bound in rich Levant morocco leather. Twelve extra large goatskins were needed for the binding. When the Bible is completed it will go on a tour of exhibition in England, Canada, and Australia, and also in the United States. One Hundred Tons in a Lump of Steel “TT weighs a ton.” We used to say this when we wished to denote great weight. But a ton isa mere trifle today. Look at the steel ingot in the picture to the right. It weighs one hundred tons, and the three workmen who are guiding it are quite indifferent about it. The ingot was poured at Creusot, France, from three forty-ton furnaces, all working at the same time, to insure uniformity throughout. - It was slightly conical in shape, and thus was easily lifted from the form. The crane that carried it off grasped it near the middle, Efficiency in Sealing Envelopes ONG ago you stopped licking the backs of envelopes because it was unsanitary. Now you buy a sponge, wet it, and use it in place of your tongue. Perhaps you find the sponge hard to manipulate. If so, you will be interested in the new envelope-moistener recently invented by John B. Mullally of Seattle, Washington. A small sponge fits in a metal coil that is attached to a metal band. On the band there are two rings that you slip on your first and third fingers. You wet thesponge before you put it in place. As it hangs over the side of your hand, you need only move your hand back and for-:: ward on the envel- ope flap in order to moisten the paste. For further direc- tions, see the picture. so that it wouldn’t be apt to slip This huge steel ingot weighs one hundred tons; it wes poured from through. three furnaces all working together, to insure uniformity throughout 60 Re ee ee ee er ee

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April, 1920 i After three years of stupendous effort the Leonardo da Vinci, an Italian war-ship that had foundered as a result of an internal explosion, was towed to its dry-dock upside down Upside Down to the Dry-Dock HEN a huge vessel, such as a V \ war-ship, is brought to the dry- dock upside down, one can imagine the magnitude of the calamity that caused the wreck. On August 2-3, 1916, when. the Italian war-ship, the Leonardo da Vinci, was resting at anchor in the channel of the Mar Piccolo, a fire broke out in the munition stores in the stern. - Immediately there occurred a gigantic explosion, tearing two great holes in the vessel and causing it tofounder. More than two hundred seamen were killed, and twenty-one officers were among the missing. Subsequent inquiry attrib- uted the cause of the disaster to two Italian workmen employed in the arsenal, and the men were consequently shot as traitors. The holes in the war-ship torn by the explosion were about thirty-two feet in length and sixteen feet wide, and were open mouths into which the turmoil. of swirling water poured, the inrushing currents causing the vessel to capsize. The turrets and upper works rested finally in the soft mud on the bottom of the channel. The keel and part of the bow remained above the water, the depth being about thirty-six feet. What would be the quickest way to get rid of the obstruction? At first the ship was regarded as lost. But, being in sheltered water not far from the arsenal, the officersin charge began to consider proposals as to how the wreck might be salvaged. One sug- gestion was to build a dike around the ship or to roll it over on the bottom . until it assumed an upright position. The task of salving the war-ship was given to General Ferrati. He sug- gested that, instead of trying to turn the ship over, it could be floated in its unfortunate position, and upon this plan the work was started. Divers found that in “turning turtle” the ship had nearly severed the firing turrets. These were removed, and some of the cannon were raised from the mounts. Then the explosion holes were plugged. After this ex- tensive preparatory work, pumps removed the water from within the hull. The water was brought down to twenty-six feet in almost the entire ship, and the munitions in the central and foremost stores weresaved. Then a successful attempt to save the coal was made. The portholes and other openings had been plugged when the large rents 61 torn by the explosion were closed, and with the removal of the water came the next step—floating the vessel. Compressed air was pumped into the hull, making it a huge caisson in which workmen could continue their work. After twelve months of stupendous effort the weight of the vessel, after the removal of its exterior detachable parts and its munitions and coal, was reduced from 24,000 tons to 18,000 tons. Then eight cylindrical barrel- like tanks were employed to lift the ship from the bottom and make it ready to be towed to the dry-dock. Four tanks, each weighing four hundred tons, were attached to the bow, and four were attached to the stern to give the necessary stability to the ship while being lifted. The bastion of the second turret was re- moved with great difficulty during the lifting of the stern of the war-ship. When the decks, upside down, were cleared, the work of actually floating the ship in its curious position was completed, and the towing to dry- dock began. It was at the beginning of September, 1919, more than three years after the disaster, that the ship was finally towed upside down to its dry-dock.

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Popular Science Monthly Newest Automotive Ideas: Taking mother on vacation and selling blankets along the way was one automo- bile owner’s idea. He found it profitable and beneScial The 1920 automobile new accessories that Driving at night would be made safer if the motorist would wear this new electric lighc on the back of his signaling hand SCREW AND CONE SCREW -THREATED BRACKET COUPLING NUT COUPLING FLANGE This tractor wheel is really a self-laying track. The wheel rolls on a series of pads -WAY b> KEY AN PLUG VALVE GPs A VALVE LOCK ROD Stamford, Conn., has invented a mechanism for con- trolling the fuel supply on automo- hm, biles. It has a # lock that the owner can adjust to cut off the gasoline supply This small motor-driven cultivator, con- trolled from the handles, tills corners inaccessible to horse-drawn implements John Fuchs, of 4 A spider-like device having three out- spread wheels over which the tire is mounted permits the operator to rotate the unfinisbed tire under the grind- ing wheel and to tone down its tread Tube-flanging was formerly a difficult job: _Now the special pliers shown here hold the tube, while a turn of the screw at the jaws quickly -does the flanging ie— SCRAPING EDGES, a OF PISTON RINGS DRAIN TO CRANICCASE >, lubricant in its place this invention em- bodies a specially de- signed piston and a separating chamber which purifies the oil before it is returned to the crank-case bottom For keeping the engine Pneumatic tires on a motor-truck are not new, but a farm truck so equipped is not only new, but practical and economical. Its owner doubled his running time and reduced running expenses 64 f st = an a, oe ek

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April, 1920 from Signals to Tractors shows exhibited many | ° Power was short. The situ- will promote economy ation was acute. Necessity required invention, and by using the trucks themselves o« the problem was solved Senent wrrrcrt tte: OIL GROOVES L- SHAPED RING WEDGE RING PISTON RING . P Here is a _ ome-piece honey-comb radiator. No soldered joints en- ter into its construc- tion, which is effected by electro - deposition This piston ring pre- vents leakage by a tri- angular-shaped wedge ring interposed be- tween the two main parts of the ring THROTTLE AND NEEDLE WM VALVE ROD AND LEVER. NEEDLE VALVE . OPERATING CHAINS USUAL NEEDLE VALVE Springs break in even the best automobiles, and AND HANDL usually the newly fitted CHAIN Cope DISK spring is stiffer than the TO DASH La Fe _— others. A block of wood This metal attachment makes clamped under the old the car driver immune to the spring in the manner headlights of an oncoming car, shown brings the car besides enabling the other fellow back to an even keel to have right road illumination AIR INTAK BUTTERFLY VAL’ FUEL INTAKE A carburetor attachment that allows ad- justmentof the needlevalve whiledriving NEEDLE VALVE CHAIN LEVER: Aa PHONES Melrose 632 Grand 64 For hauling milk a specially built glass-lined steel tank of 900-gallon capacity He enjoys all the comforts of the in- on a five-ton truck chassis has been built. In principle it is simply a closed car; the idea embodies a cab giant vacuum bottle and keeps the milk cool even in the hottest weather built around the driving compartment 65

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In Alaska reindeer are being raised for meat; a herd doubles itself in three years, making the business very profitable This baby reindeer will soon be branded —not with a branding-iron, but with an aluminum button fastened in its ear We'll Soon Be Eating Reindeer LARGE shipment of frozen reindeer recently arrived at Seattle from Alaska. The United States began raising reindeer in Alaska twenty-five years ago. As they increased they were given over to the natives under the supervision of the Bureau of Education. From a few hundred head imported from Siberia, there are now about 200,000. reindeer in the northern territory, valued - at $6,000,000. They double every three years, though many of them are slaughtered for home consumption. Reindeer cannot be branded like cattle, because their hair is very thick and is shed every year. When the reindeer calf is a few weeks old, an aluminum button about the size of a ten-cent piece, bearing the mark of the owner, is fastened into its ear, and every deer-owner has his mark or number on the tag. White men have recently gone into the business of raising reindeer in Alaska. They will improve the stock, and if possible breed off the horns. At present the large horns of the reindeer take much of the animal’s vitality. Thehornsare used for making knife handles, but the production of meat is more es- sential at present. Canada. is also going into the reindeer business. The - great terri- tory lying north of the agricultural belt is to be made a vast reindeer pasturage. White moss is the prin- cipal food of the reindeer. It is estimated that Alaska and northern Canada together have a grazing area of reindeer feed for 40,000,000 reindeer. The country is of tremendous ex- tent, and has the advantage of being a natural refriger- ator for at least seven months out of the year. Popular Science Monthly Off with His Head! an — the Lord High Executioner! She is #' shown here all ready to behead a chicken—not with an ax, but with a small-sized guillotine invented by Mr. Frank S.-Rece, of Dallas, Tex. The chicken’s head is fitted into a groove. Press down quickly on a handle at the top of the device, and down comes a sharp ‘blade and off comes the chicken’s head. Then the handle springs back to its origi- nal position. Mr. Rece con- siders his inven- tion especially adaptable for use by women, who he says are not usually skilled in chicken-killing. -The guillotine method seems A miniature guillotine has been invente ‘or killing chickens. All you do is press on a handle, and a sharp blade beheads the fowl to us more ac- curate and hu- mane than the ax method. Compare the size of the man on the farther side of _the turntable with the size of the propeller to get a clear idea of the enormous size of the machine described above 66 Machining a Monster Propeller HE United States ship Leviathan is. the biggest ship afloat at the present time, and its screw propellers are of correspondingly monstrous dimensions. Casting and finishing so gigantic an object is no child’s play and requires machinery equally gigantic in size. The accompanying picture shows the extension boring and turning machine in the Philadelphia shops of a promi- nent ship and engine building firm. On the table ready for the process of machining, is one of the Leviathan’s monster propellers. The “‘table’”’ on which the propeller is fastened is far from being an ordinary table. It has a diameter of 16% feet anda weight of 41,000 pounds. It turns on a spindle 26 inches in diam- eter and will carry a weight of 300,- 000 pounds. The tool-bear- ing arm of this monster machine weighs 35,000 pounds and has a maximum swing of 33 feet 4 inches and a maximal height under the tool-holders of 15 feet 2 inches. The boring bars down feed of 84 have a inches. Separate motors control the sliding motions of the differ- ent parts of the machine. The main drive is accom- plished by means of a 50- horsepower motor. Ap This lind Ang caus figui nine doe: cak«

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April, 1920 Here Is a Perfect Woman ENUS de Milo has a rival, Miss Rosalind Smith of Los Angeles. In fact, Miss Smith outclasses Miss Venus in being able to ex- hibit two perfect arms. Here are the measurements of the Los Angeles entrant in the perfect figure contest that is always going on: weight, 121 pounds; height, 63.5 inches; arm reach, 64-8 inches; breadth of shoulders, 14.7 inches; depth of chest, 7.5 inches; girth of neck, 12.3 inches; girth of waist, 25 inches; girth of thigh, 21.7 inches; girth of right calf, 13.1 inches. Miss Smith says that her perfect figure is due to nine hours sleep each night out- doors, deep breathing, light exercise, and the foregoing of This is Miss Rosa- lind Smith, of Los Angeles, famed be- cause of her perfect figure. She-sleeps nine hours daily and doesn’t eat candy, cake, or pastry The Truck that Does Its Own Log-Loading NE man can hoist a load of logs upon a truck with the greatest ease if he possesses a log-loading device like the one recently invented by Reginald Foster, of Hot Springs, Ark. The loader is a mass of chains, gears, pinions, joints, shafts, a clutch, a brake, and a drum. . Power from the motor is im- parted through the transmis- sion to a drum, which thereupon revolves. A cable attached to the drum has at its other end the chains that are looped around the logs. When the drum revolves, the cable winds around it, and the logs come up the inclined plane on to the platform of the truck. The clutch is then disengaged and the chains are released and sent down the incline for more logs. If, on the way up the incline, the logs should turn and refuse to roll properly, the clutch and brake could be applied, and the logs straightened and started on their way again. Ss candy, cake, and pastry. © ?RAWBERRIES!” Women’s magazines, please f saben copy. or sale! The traveling butcher shop is the latest plan for fight- ing the high cost of living; the butcher pays no rent Pork Chops for Sale! “‘Umbrellas to mend!” Added to these street cries you may soon hear, ‘‘ Pork chops One butcher found it cheaper to buy a large truck than to pay the high rent asked for his store and The engine of the truck turns a drum, winds a cable, and pulls the logs up © International Film Service The heads on the roof of a Kamerun citizen represent, not victims, but wives and children. He adds a new head for every new member of his family; therc’s also a big one for himself 67 now he peddles his meat. He turned the front part of his truck into an icebox and the rear part into a counter. Every morning he motors ;to,. market, -getting back in time to start over his route at nine o’clock. In the course of a day he covers a distance of about six miles. Not only does he escape high rent, but he needs no delivery boy. And his customers are saved the trouble of going after their meat. He Wears His Family History on the Roof ss OW many wives have you?” If you asked a native of Kamerun this question, he would simply point proudly to the roof of his house. There you would see two or three heads impaled—not real ones, we hasten to explain. Every time he acquires a new wife or child, he puts up a head —a large one for a wife and a small one for a child. At the end of the line-up there is a specially large head to repre- sent himself. How simple is the task of the husband-hunting girl in Kame- run. When she sees a man she likes, she follows him home and gives his roof a hasty but com- prehensive inspection. Ifthere are too many wifely heads al- ready there, she wastes no more time on him.

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If you don’t like a wrist-watch, try a belt-watch; it is just as convenient and the women don’t wear them—yet Now the Belt-Watch HERE’S no denying the fact . that wrist-watches are handy, but there are still many men who fight shy of wearing them, because women also wear them. Such men will be glad to hear of the -belt- watch, for men only. A loop is attached to the back of your watch and you run your belt through the loop, holding the watch upside down when you doit. When you wish to see the time, simply raise your watch up from the bottom. But doesn’t this unnatural up- side-down position affect the works of the watch? ‘“‘No,” says one enthusiastic belt-watch wearer; “my watch gained an hour a day when I wore it on my wrist, and now it keeps excellent time.” z The swinging of the arms seems to upset a watch more than constantly standing on its head does. Early Bureau of Standards IKE us, our ancestors bought and ate oats, peas, beans, and barley. And they were just as anxious to get full measure for. their money as we are. But they did not have a government bureau to set accurate standards of weight and quantity. What did they do? They went down to the market-placeand measured out the grain in great stone meas- ures like those below. Every- body used these measures, and thus they became a “bureau of standards” for the'village. _ The stone measures in our pic- ture are located in the town of Gruyére, Switzerland, and they are supposed to be the sole sur- vivors of their kind in-Europe today.

Centuries ago our ancestors used stone meas- ures like these for measuring out their grain Popular Science Monthly The deadly fumes that rise as the oxyacetylene torch burns its way into brass do not affect this welder at all Masks for Welders EADLY fumes from an oxy- acetylene torch, as it burns its way into brass and melts it, no longer hold terrors for J. A. Hen- - dricks, an expert welder in a Seattle shipbuilding plant. Formerly he used from twelve to fourteen hours for a job that now requires only from six to eight hours. Hendricks now wears a gas-mask like those used in the war. Without the mask he was forced to recuperate for two days after doing a day’s . welding. Hendricks is considered the most skilled welder on the Pacific Coast. To him falls the delicate task of welding the brass tail-shafts on big steel steamships. This operation must be one hundred per cent per- fect. Other welding jobs may pass with slight flaws, but not so with the tail-shaft jobs. Taking Your Good Road Along with You NLIKE an automobile, an airplane requires but a small portion of ground smooth enough to run upon, while a seaplane re- quires only a strip of clear water. Now comes an American in- vention - reviving an idea utilized by the Germans during the war, the invention of a landing gear that en- ables a flying-boat to come safely and grace- fully down upon solid ground. The new Sperry sea- plane is equipped with a collapsible landing gear. This new ar- rangement was designed to permit it to alight

On water or on land, equipped with suitable landing gear of boat or wheels, this Sperry seaplane glides safely down 68 both on sea and on land, and is an innovation of much impor- tance in the development of the manufacture of seaplanes. When one of these flying-boats finds itself high and dry over the land, and must come down for fuel or repairs, or for any other reason, the pilot does not fear crushing his boat on the hard ground. He merely pulls a_ lever lowering the landing gear, the wheels drop- ping down beneath the boat. Then the machine runs along the ground to a graceful stop, like a true amphibian of its kind.

0 a Si b Cc r aoaerno op” ~< Th FO es Ow BR BO moss

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April, 1920 Electrical Slaves of Whistle and Lamp How an Australian mystified English newspaper men N a hall near Tottenham Court Road, London, Captain Alan Rob- erts, an Australian, succeeded in bewildering half a dozen London news- paper men who ought to have known more about elementary electricity than they did. As it was, there was nothing to restrain them from cabling to America the news that Captain Roberts has invented an unheard-of piece of mechanism that performs miracles. Captain Roberts blew a police whistle. A miniature motor-car containing two lay figures stopped and turned in response to the blast. Then Captain Roberts played a ray of light upon the motor- car. The mustache of one of the lay figures twitched in a very lifelike way. At the same time chimes were rung by an instrument in the corner. A newspaper rep- resentative amused himself by blowing a whistle at the correct pitch and causing two lamps with electric bat- teries to flash. Radio amateurs who read the PoPpULAR SCIENCE MoNTHLY will hardly be mystified by these proceed- ings. They have seen Chris- tian Berger’s engaging elec- When Captain Alan Roberts blew a po- lice whistle this miniature motor- car, in which two lay figures were seated, ran about, stopped, and turned, controlled merely by sound ‘to release a spring or lever, the possibilities are endless. It is upon this principle that Captain Alan Roberts has built histoy. The police whistle merely affects a tele- phone transmittér concealed within the motor-car, causing the electromagnet to release the driving mechanism of the car. As for the experiment with light, that of course recalls the work of John Hays Hammond, Jr., in this coun- try. Everyone knows that selenium changes in electric resistance with the amount of light that falls upon it. John Hays Hammond built an electrical dog propelled by electric mechanism in tric dog, which leaped out of a little kennel when they clapped their hands. They know that a loud sound may so jar a telephone transmitter that it will cause a wave of electric current to flow through the electromagnet, or in some case a relay, and cause the electromagnet or the relay way to produce the effects that made his spectators gasp in toact. Ifthe jaris great enough to cause the electromagnet NGLAND is considering the use of a new pen that is made of steel, quill, or reed, and is cut down to a broad, soft nib. No separate pen is needed. The child inks the nib and writes with it. The pen moves as smoothly over the page as a paint-brush. As the child’s writing improves the nib is gradually cut down until it becomes a point. It may be cut to any angle. A small metal spring on the under surface of the nib retains much of the ink gathered at the first plunge into the ink-well, and thus a second dipping is not needed for Fred is using a quite a while. reed pen that is Why didn’t we rll oat learn with this end, not a point kind of pen? astonishment. It Squeaks But Doesn’t Scratch Captain Roberts completely mystified the newspaper men when he made a set of Westminster chimes ring by turning a beam of light upon them. But anyone familiar with selen- ium (an element which yaries in electrical conductivity with the amount of light that falls upon it) knows how it was done which selenium was included. When he turned on a pocket flash lamp, the dog would follow the light as unerringly and as instinctively as if it were alive. Captain Roberts, of course, uses selenium in the same Breaking Records at the United States Mints URING last year the mints of the United States established a new record for speed by turning out 838,- 911,195 coins for this and foreign governments. This was over 240,- 000,000 more coins than were minted in the year 1918. In American money the number of ‘ coins was 738,642,000, and their value was $20,777,000. Included in this coinage were 3,679,000 half dollars, 15,104,000 quarters, 54,529,000 dimes, 76,395,000 five-cent pieces, and 588,- 935,000 one-cent pieces. The coinage for foreign countries included 9,440,000 pieces for the Philippines; 10,000,000 pieces for Siam; 3,000,000 pieces for Salvador; 850,000 for Nicaragua; 3,200,000 for Venezuela; and 20,750,000 for Peru.

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Popular Science Monthly Were the Good Old Days as More work, longer hours—not many people Photographs © by the Two, nine, seventeen— the bookkeeper on his high stool used to add up all -the léng ‘columns of figures on his ledger; if he did not happen to be very alert he usually finished with a difference and had to start all over again Here’s the way we swept our floors—in the days be- fore the vacuum. cleaner. The dust rose’ from the carpet and settled down upon everything in sight _Machines do our adding and subtracting for us now. Tap, tap—pull. The adding- machine operator strikes two number keys and pulls a handle. Down comes the figure in black and white. She repeats this until she has come to the end of her column The shoemaker in his dirty, untidy Shoes are now made by machinery, one set of machines shop called it a day when he had turned turning out six hundred pairsa day. This is the machine out one pair of shoes. His work was that does the pulling and nailing of the soles. The man tedious, yet it required skill. He who works the machine learns his job in a very short time is here sewing the sole to the uppers and earns as much in a day as the old-time cobbler 70

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April, 1920 Good as They Are Painted? would really want to go back to them American Photo Service. The tailor of today handles fifty suits at a clip. He uses a powerful cutting-machine instead of shears, guiding it by meansofahandle. Inspite of increased production, the price of asuit has dou- bled in the last few years But the vacuum cleaner swallows all the dust it raises out of the carpet; the dust is digested Modern milkingis done by machinery. Thecows are lined up and held in place by metal bars that fit alongside of their necks. The attendant then attaches the milking machines and the milk is drawn into the pails. They are completely covered and no dust or dirt can get at the milk 71 in a large bag, from which it can be emptied Two by two, the tailor used to cut out your suits; he did it at leisure. Dust-caps and bungalow aprons with a pair of long shears. If his hand was steady, your suit are unknown in the house of the vacuum fitted well around the neck; but you never could be sure that cleaner; its owner can always be dressed up he wouldn’t stay out late the night before he cut into yours The old-time farm-hand smoked as he milked. Both milk and ashes fell into the pail, as well as several inquisitive flies. Perhaps the flies were extracted before you got the milk but they left their germs behind them

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Standardized Bodies for Motor-Trucks HE problems that have held back the more general development of side-dump bodies for motor-trucks in the past included so mounting the body that the contents could be dis- charged far enough to the side to clear the rear wheels; a low height to permit hand shoveling from the ground; a positive control of the body at the moment of dumping and re- turning; and the absence of easily damaged mechanism. These problems have been solved in a new line of standardized bodies, one type of which is shown herewith. They are offered in all sizes, from one yard cubical capacity to five yards, and can be used to carry all kinds of bulk material, such as sand, stone, or cement, or even lumber. Each body of the line is made of steel, is low enough to permit loading by hand from the ground, and may be oper- ated either by a hand-crank or by power from the truck engine. In operation, the body is first carried sideways and slightly elevated on the side opposite the dump until the center of gravity of the load comes at about the point where the body tips. Then the slotted elevat- ing cams come into action, and the body tilts to an angle of forty-five degrees, which is sufficient to dump nearly all bulk materials and lumber. The side of the body acts as.a gate and automatically folds down par- allel with the body bottom. In the hand- operated type, twelve turns of the dumping crank willbring | Dumping problems for trucks the load to the ave been solved by a stand- ardized body which, operated tipping point, by the engine, dumps the load PILE AS and similarly from one side. At the right is a eaten |: twelveturns in Shown the dumping apparatus CHASSIS the reverse di- rection will bring it back again to its normal position. When it is desired to manipulate the body by the engine power, a chain- driven: take-off is provided from the truck gear-set. A _ safety release prevents damage to the body should it strike an obstruction. The body mechanism is entirely above the. truck-frame, so that no chassis changes are necessary to fit it on practically any make of truck. The hybrid airplane-railway passenger car. Instead of being driven by a locomotive or an electric motor, the new car is run by an airplane propeller, the motive power being an engine whose fuel is benzol . Driving a Passenger Car with Wind “C*OUNDS like an airplane,’ one might say when he hears the novel railway coach coming down the track. The whirring sound of a propeller cuts the air while the sound of wheels travels down the rails—a strange combination! During the severe coal shortage in Europe an inventive genius conceived the idea of a powerful gasoline-driven engine equipped with an airplane propeller, being fitted to a specially built car. The powerful thrusts of the propeller draw in the air, and the car is sent over the rails at a speed of fifty miles an hour. Forty people can be accommodated in the wind-driven passenger car, en- joying an airplane-like ride safely on the surface of the ground. 72 Popular Science Monthly AQ a Za . =? i al [eo WITH 7 BOTTOM CLEAR OF REAR WHEELS HERE o~ The airplane type fan adapted to ' your Ford concentrates the air cur- rents and whirls them over the en- gine, thus affording additional cooling The Two-Bladed Airplane Fan for Automobile Engines NE adaptation of airplane en- gineering experience gained in the war, and now applied to the automo- bile, is the two-bladed airplane engine fan shown above. While the old type of fan is so constructed that most of the air currents slip off the blades, the airplane type concentrates the air currents by means of the peculiar spoonlike shape of the blades. The air currents are thus concentrated into a shaft of swiftly moving cool air that bathes the engine, keeping it and the cooling water at the proper temperature.

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April, 1920 He Made His Dream of a Noiseless By Fred Gilman Jopp Engine True of gas-engines was a man with a dream: a noiseless engine. Frank E. | Covey, of San Francisco, worked ceaselessly until he produced the object of his dream. His combined re- ciprocating and turbine en- gine was designed to get rid of the roar of the exhaust. Or of the early builders doing good ? RE the POPULAR SCIENCE MONTHLY’S prize contests Our recent con- test, “What Can Be Done with the Exhaust of a Gasoline Engine,” discovered, in the invention of the first prize winner, Frank E. Covey, a new light-weight noiseless gaso- line engine that 'will—if its inventor’s claims are true— revolutionize the automotive and aeronautical industries. Already it has caused enough stir to induce engineers of foreign countries to investigate.—EDITOR. We'll say they are! propeller becomes the balance wheel to a great extent, the engine can be built at about one and one quarter pounds to the horsepower, and the amount of weight done away with will cut down the weight of the power plant more than 60 percent. For more power, an engine of four to six cylinders may be doubled In this engine the exhaust, : instead of being shot into the open air or through an expensive muffler, is turned on to the rim of the flywheel or runner, into pockets just close enough together to cut the out- going burnt gases into such small-units that after the pocket passes the port there is no more pressure, ‘and there- fore no report or noise. In passing the exhaust port, the INLET ALVE EXHAUST NOZZLE TURBINE BUCKETS fIN FLY. WHEEL FAN-BLOWER/ 4 A cut-away view of Frenk E. ,Covey’s gasoline engine. Note the absence of compli- cated parts and the pistons that function upside down ee tl ati ROSS HEAD AND: CONNECTING RODS force of the exhaust striking into these pockets sends the flywheel at a tre- mendous speed with no back pressure, since the rim of the flywheel travels so much faster than the reciprocating piston that the flywheel with its pockets becomes a scavenger, allowing no carbon to form anywhere... One reason for this is that no part is dipping in oil to splash more lubricant into the cylinders than necessary, thereby burning up money and burn- ing on carbon. The fan vanes cast into each side of the flywheel form a double fan blower, which discharges the drawn-in cool air upwardly and directly into the inclined cooling rings of the cylinders. . These vanes keep the entire .con- struction cool without water; there- fore no radiator, no piping, and no danger of freezing. By closing the air intake the engine can be run as cool or as hot as desired. These are all features that will appeal very strongly to the airplane builder. For the airplane, when. the A (PISTON r a =, i! gre “ A f | o INTAKE” “INCLINED “ “COOLING RING] by placing anather unit on the same base and con- necting the whole to the main shaft. Every moving part can be oiled from the outside through sight-feed lubri- cators. Any piston can be removed without interfering with the others. Should an accident occur to one cylinder, the piston can be disconnected and removed in less than five minutes, and the engine started again without it, with the engine still in perfect balance. In cost of construction the engine is in a class by itself. So many features absolutely a part of other engines have been found unnecessary in this one that anyone acquainted with the cost of building high-grade machinery will readily see the difference in expense. In automobile construction, the near future is going to demand a car built on smaller and lighter lines. . This noiseless light-weight turbine is here to supply that requirement. Every moving part can be oiled from the outside through sight-feed lubricators. Should a piston or cylinder become injured, it can be removed in five minutes and the engine operated without it 73

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Popular Science Monthly Let the Wood-Pincher Pile the Wood HEN there is a cord of wood to put away, what a saving of time it would be if one’s arms could suddenly take on the power of the giant “wood-pincher,’”’ developed as a labor-saving device during the stringency of war-times! This mechanical wood-lifting machine is just what the average boy would like to possess when the time comes to pile wood. Great numbers of tree-trunks to be lifted and moved ordi- narily demand the labor of many men. Somewhat on the principle of the ‘‘steam shovel,” the metal jaws of the huge wood-pincher open above the piles of logs, snap together upon them, and take nearly two hundred logs for a full ‘‘bite,”’ then close tightly their iron teeth, and, guided by chains, de- posit the logs in place Milking the Peanut D° you like peanut butter? Then you certainly should like peanut milk—and it is much cheaper than cows’ milk. A half-cup of peanut kernels will produce a pint of milk that is far richer in fat and protein than is the milk of a cow. Professor George Carver, of the Tuskegee Institute, in Alabama, conducted the experiments that led to the discovery of peanut milk. He says: “Whenever you find an animal product you will find its counterpart in some vegetable.” Except for its nutty taste, peanut milk is very like cow’s milk. It will sour and curdle, and when churned will produce buttermilk. It may be used in making ice cream, and in flavoring coffee and chocolate. If not convenient to keep a cow in the back yard, raise peanuts! Cultivate a taste for peanut milk and start a cheap dairy. Safety First—Out Comes the Fuse FUSE-REMOVER. that elimi- nates the danger of a shock when pulling out fuses is the new device of a Waterbury, Conn., man. When a fuse of this type has been in place for a long time it may be rather hard to remove, but with this new device the work | becomes simple. The jaws that grasp the fuses are made of hard fiber, which in- sures good insulation. The frame is of hard wood. The device is placed so the jaws open around the fuse until the handle is pulled; then the jaws tighten and withdraw the fuse. Spare the Seed and Spoil the Flax [XN Europe seeds are removed from flax by hand in order to preserve both seed and fiber. But this method is too slow for the American flax-grower: he does it by machinery. The flax is held between two rotating rollers and the seeds are forced out. They fall down a chute directly behind the rollers, and the straw is withdrawn intact. Flax has been called the most valuable plant that is grown because of the diversity of its uses. From the straw is derived the linen fiber from which all linen goods is made, from the coarsest materials for upholstering purposes, to the finest table linen. Linseed oil is pressed from the seed, and this is the chief in- gredient of paint, linoleums, and oil-cloths. From the solid mass that is left after the oil is extracted, oil cake, which is a valuable stock food, is manufactured. Oil cake is also used in the manufacture of fertilizer. This New Field-Gun Burst on Test ECENTLY a new type of field-gun just designed was fired at one of the army proving stations, with the result shown in the photograph. The piece was first tested for strength by firing an extra heavy charge. As the gun passed thistest satis- factorily it was considered safe, and the board of officers who were conducting the test crowded around to watch the firing. On about the fifth shot the gun exploded, hurling pieces in all ‘directions, and leaving only the carriage intact. The piece of metal held by one of the spectators is part of the gun barrel. Pieces of this character were hurled among the bystanders, but fortunately there were no casualties, though one officer had his overcoat cut by a fragment. Experts who examined the wreckage attribute the accident to a flaw in the metal. Why the gun didn’t burst on the high-pressure proof charge in- stead of on a low-pressure shot will probably never be explained. OQ. et etvww=™ Ons a | —~ ~ ~~~ e Ss veh CO

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April, 1920 Heating Rivets in a New Way 6 he man who stands upon a steel girder overhanging a dizzy street- chasm, and whose job it is to demonstrate his ability to toss red-hot:rivets to an- other workman, has more than ortinary interest in the new type of furnace de- signed for the heating of the rivets. In five minutes he can create in this furnace a temperature of 3000° F., one quarter as hot as the sun. With the flame burning its brightest, he can swing the furnace on a crane and lift it to any position desired. He can keep a number of rivets on the hearth just beyond the play of the intense heat, and ina wink of the eye bring any of them to a glowing temperature merely by raking them under the flame. Kerosene is the fuel used in the fur- nace. It is transformed into a gas and blown by compressed air at a pressure of eighty or ninety pounds to the square inch, and the furnace is said to operate on 34 of a gallon an hour. It is claimed that the flame burns without hydrogen and is therefore non-oxidizing, so there is no danger of burning up the rivets or tools left in the heat of the flame. Removing the Cherry’s Pit ‘“HERRIES may be pitted in the ma- chine shown below in this fashion: First, pluck off the stem and fit the up- right cherry in the curved base of the pitting-machine; then press down on the handle and force the pit out through the hole in the center of the base. A spring sends the handle back to its original position. ‘Owing to the sudden falling off of the cocktail business, however, we fear that many a young cherry will have to go begging in the future. © Kadel & Herbert He Shoots His Toy Airplane Sviien a Gun OP! Off goes the gun, and out shoots a toy airplane. It travels grace- fully through the air for about two hun- dred feet and then drops gently to the earth. The gun is made like an air rifle, except that there is a slit in it running from the trigger to the nozzle. And inside there is a strong spring attached to a small catch that slides back and forth through the slit. The boy attaches the tail of the airplane to the catch and drags the airplane down toward the trigger. The spring contracts and is caught by the trigger. After he has aimed the gun he pulls the trigger. This releases a spring and the airplane shoots off. Since the toy is neither gun nor air- plane, but a combination of both, it might be called an airplane-gun. House-Moving by Motor-Truck \\/ BILE many New Yorkers pay two hundred dollars a month for a first-class four-room apartment, it is said that in Cincinnati one can buy a four-room house for that price. Not that Cincinnati has anything to do with it. The government built the houses, at a cost of fifteen hundred dollars each, for the workers in munitions plants in the neighborhood. The munitions workers having gone elsewhere, these houses are now being sold. But they must -be removed by their new owners within sixty days. That explains why on the roads leading out from Cincinnati may often be seen great trucks lugging the houses away. Each of the four-room houses is equipped with electric-light wiring and fixtures, and an excellent bath-room and kitchen, together with the neces- sary plumbing. . Trying Out the Seeds N these days of under-production, the parlor-table seed-tester proves its value. The tester is provided with a bottom tray, which not only protects the user from dirt and drippings, but which also makes unnecessary any further attention after the first operation. On the bottom of the tray is a blotter over which there is a pad that holds and supplies the necessary moisture. “This pad is perforated with compartments, and in these the seeds to be tested are placed. The testing is best done in late winter or very early spring, as usually too little time remains to be sure of the quality of the seeds if the gardener waits for the planting season. pelea NR ory GF~ f v

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Carrying a } Monster Cun Under the Sea / © international Film Service Co. Now that we have peace, doubtless this submarine with a 12-inch gun is prepared to see that we keep it HE British submarine M-1, which mounts a 12-inch 45-caliber gun, is the most powerful undersea craft in the world, and represents a new idea in naval warfare. It was completed in August, 1918, just before the end of the war, and was to have been used in convoying merchant ships which might have been attacked by enemy light cruisers. As a matter of fact, the M-1 has never been in action. This unusual craft is 200 feet long, and has a displacement of 2,000 tons There is the usual recoil arrangement made for the big gun, but despite this the submarine goes back about ten feet in the water, from the recoil, whenever the gun is and a speed on the surface of about 16 knots. fired. Popular Scierce Monthly It Is Midsummer Now in Northern Mars EEN through a telescope, the bright planet which everyone notices in the east after sunset appears as an exceedingly interesting object. It is Mars, the mystery world. Just now the earth observers see Mars in the height of its northern midsummer. The polar snow-cap has melted to its smallest, and many of the curious dark markings seen upon its yellow deserts and called ‘‘canals” have vanished under the sun’s persistent rays. In the far southern region of Mars midwinter pre- vails, and as the planet is observed through the rest of the year the coming of spring in the southern hemisphere will be witnessed. It is strange to look across the gap of more than 50,000,000 miles and see the changing seasons displayed upon another world! On April 21 Mars will be in opposition and on the 27th it will be closest to the earth. The distance of Mars from the earth at the present time, is about 15,000,000 miles greater than it is possiblefor the planet to approach, but it is closer than during the opposition of 1918. Sunken Ships Lifted with P Air-Bags METHOD has been devised and success- fully tried by which sunken ships can be salvaged with comparative ease. Instead of using heavy steel tanks whose weight must be added to the lifting force employed, the new way is to place fabric bags in the hull of the vessel and inflate them with air. To augment the effect, a number of bags may be attached to the outside of the hull. The bags are made of very strong rubber water-proof canvas, are from 30 to 40 feet long, and displace from 50 to 100 tons of water. There is no difficulty in placing them inside the ship’s hull. They are flexible and can be folded to fit a small space during transportation, in this respect being very different from the more clumsy steel tanks ordinarily employed. In order that the compressed air within the bags will not be forced to the bursting- point, each bag is provided with an auto- matic blow-off valve. When placed in the ship the bags are flat and lie against the girders, and the vessel begins to rise when sufficient air has been blown into the bags. Since the bags are placed just where the greatest weight is encountered, the ship can be lifted without any severe strain on the structure—a very great advantage over the old method. The first vessel to be salved by this system was the steamer Main, which had been sunk by a German submarine in Luce Bay, off the coast of Scotland. The bags displaced one hundred tons of water each, and weighed only one ton complete. Larger bags are being made, and it is rumored that the Lusitania may be raised from the bed of the ocean by this system of air-inflated bags. AIR FROM —» COMPRESSORS | | | | | AIR BAGS | BEING STOWED| Perhaps the Lusitania will be raised by air-inflated bags. The bags are placed in the ship flat; when they are inflated with air, the ship rises

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April, 1920 Let the Truck Lift It take their places. pup into a pen. visitors. An electric truck equipped as a crane. here shown in a position for hoisting heavy the hoisting structure having been unlatched and drawn down the vertical bars objects, EN men tugging at a 4,000-pound weight may finally be able to move it to the desired spot; but the work of all ten can be done very expedi- tiously with one of the new crane-trucks. Easily the electrically driven truck travels over to the pile of heavy machinery, extends its sinewy arms, picks up the massive weight, and swings it around in the most cramped quarters of a storage room, setting it down in the exact spot intended for stacking. At the present high cost of labor, one can imagine the expense of employing men to do the work that this clever piece of mechanism can do. The truck has a two-wheel drive and a four- wheel steer equipment, and is capable of being made into a four-wheel steer truck. The cost of operation varies, of course, with the facilities for charging the batteries, but under normal con- ditions the crane-truck can be oper- ated for one hour, moving a load of 4,000 pounds, at a cost of about ten cents, including the operations of starting and stopping. A Bath-Tub for Sun-Baths OR certain skin diseases the -. curative: power of sunlight has long been recognized, and many people who have availed themselves of no_ stronger remedy than sun-baths have been restored to health. Realiz- ing this, an enterprising doctor of Brittany has constructed a special type of bath-house. It is designed to collect the sun- light even when the sun is low and its light weak. A lens is arranged to follow the motion of the sun, and to concentrate the rays upon the patient, who is hidden from view in the bath-cabin. The Cabin itself revolves and the lens brings the rays to bear upon any part of the body desired. It is She’s a Dog-Catcher EXT time you pick up a stray dog or cat and send for the wagon to take it away, don’t be sur- prised, when you hear the dog-catcher’s wagon, if a ‘woman jumps from the front seat, runs up the steps, and rings your door-bell. During the war the shortage of men dog-catchers in American cities made it necessary to hire women to In the picture below you see Mrs. Laura Dietrich, one of Denver’s dog-catchers, putting a poor little stray The pens in the pound are quite desirable from a dog’s point of view. There is a clean, comfortable bed in each pen, and even a chair for Lost dogs and dogs that never in all their lives had any owner are placed side by side. certain length of time, no one claims or asks for any dog in the pound, alas! he is killed. If, within a Tere re cet an | © American Photo Service He owns his home; it’s atrolley car. The kitchen is out in the motorman’s box, and the other rooms are curtained off inside ne by the war women came to the rescue. Denver’s dog-catchers putting one of the pups in his pen In the shortage of men dog-catchers brought about Here is one of Home, Sweet Home—This Time It’s a Trolley Car ND the landlord raised the rent again! But Thomas O’Mara refused to pay it. He took his rent money, bought an old trolley car with it, and made the trolley his home. The motorman’s box is now a kitchenette, and the inside doors of the car will shut out the fumes when Mrs. O’ Mara cooks corned beef and cabbage. The seats along one side continue to serve as seats, but those on the other side are used to support the table and beds. The car is curtained off into separate rooms. There are windows all around, plenty of fresh air, sun- shine—and no rent to pay! What could mortal wish for more? We do not know where Mr. O‘Mara keeps his trolley car, but probably a kind-hearted neighbor offered his side yard.

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yy Things New for All the Members of Why not introduce some of these labor-savers? An armful of small bundles that are always slipping is no longer neces- sary, now that many grocers supe ply their customers with heavy wrapping-paper shopping-bags that have strong cord handles When cleaning house, put birdie in the yard Pour some paraffin in a glass, sink into it a wire cage containing absorbent cotton anda wick, and use for a night-light Attach this sponge-dryer beneath your soap-dish @© Press Illustrating Service Replace the bristles in an old shaving-brush with a small sponge: it takes readily to lather Popular Science Monthly he the Household Fo This broom’s Japanese aT its its. $ . You are tempted to buy more when you can carry the things so easily You can leave this candle lighted. When it has burned low, the snuffer will drop automatically inventor claims that the joint enables: the user to dig in corners conveniently the gas. get too hot? 78 “Bake in a hot oven,”’ says your recipe, and you turn up But how can you be sure that your oven won’t Use this automatic temperature regulator A German preserving out- fit provides a water-jacket with a steam cover. The jars are easily handled

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April, 1920 , It is a portable out- door lighting appa- ratus, which weighs only forty pounds, producing a powerful white light at low cost This ammeter affords the only means of testing the condition of adry-cell. Con- tact may be made directly to the battery (Right) Emery wheels partly cov- ered with a hood, which catches the dust from the tire casing and then draws it off through a blower The portable belt conveyer has found a wide range of usefulness in loading and un- loading cars and trucks and in storing material such as coal, coke, sand, and gravel The purpose of this appa- ratus is to mold into shape the babbitt metal bearings that are used in shaft- hangers and journal-boxes In manufacturing boots, those made with the so-called friction lining stick to the lasts. A portable boot-stripping machine removes them quickly and easily (Below) Useful alike to the farmer, motorist, and home mechanic is the six-in-one tool com- bining a vise, an anvil, an emery and buffing wheel, a drill, and a pipe vise. It weighs only ninety pounds The foot treadle of this lathe runs the : entire length of its frame, thus permit- ; ting convenient operation from any posi- tion. Tool-rest and tail-stock have unusually large bearing surfaces which insure great rigidity and accuracy Car rails were formerly ground by hand, a long and tedious operation. Now the big traction companies supply their men with an electric motor which drives a flexible shaft attached to a rotary grinder

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Popular Science Monthly She’s Made of Wood and a Thousand Wheels YGMALION made a statue, loved it, and it came to life for a short time. But that happened centuries ago. Dr. Nixon, of San Francisco, has built a statue answering to the name of Isis. She reclines on a divan, gorgeously clothed, and spends most of her time playing on a zither. She knows sixty-four tunes. There is no gray matter in her pretty brown head—just wheels, a compass, and bottles of colored liquid. In her bosom are more than three hundred wheels, and in her entire body more than athousand. She is a mechanical masterpiece. Dr. Nixon has spent In a sudden shower, a protector made of adjustable bars and canvas is quickly erected on the bus-top Caught in the Rain OU are sitting on top of a bus, enjoying an early warm spring day, when a sudden shower comes down. What happens if you can’t find a seat inside? But buses may soon be equipped with rain- protectors like the one shown above. weather, the protector slides into place beside the seat and is hardly noticeable. It is simply a combi- nation of jointed metal bars and rolled-up canvas. When it rains the bars are extended, the canvas unrolled, and the seat will be well protected at front and side fromtherain. Since the bus moves forward, there is no need of protecting the back of the seats. And the side toward the aisle is left open, so that passengers can get out without trouble. twelve years putting her together and he says she can do nearly everything but speak. Isis, an image carved by theman at her side, can play sixty-four tunes on her zither In fair © Intemations Service Co, Safeguard the Children by Foot-Printing Them RE you afraid your child will be kidnapped? Have the boy foot- printed! Thus has the Bertillon sys- tem of finger-printing criminals been expanded and the new method of identification been made to apply to lost children who are too small to give the police any information about them- selves. The method also is service- able in maternity hospitals, where the matter of identification of children might become complicated. Anxious mothers who fear their children might be lost or kidnapped may take them to the police station to have foot-prints made. Examine the skin of your hand under a magnifying- glass and you will see many ridges and furrows. No two people dre provided by nature with similar finger- or foot- prints in the matter of pattern or minute details in the ridges where the perspiration glands have their open- ings. “By their foot-prints ye shall know them,” might be an adaptation of the old saying, the little ridges of hands and feet providing the only absolute means of identification known. The Chinese were pioneers in recog- nizing the value of the finger-print asa_finger-prints attached to the docu- means of preventing forgeries. When ment. A finger-print beside the signa- a will was read to the beneficiaries, ture on a check would make forgery of their approval was attested by their the writer’s name an impossibility. Foot-print of a twen- Foot-printing a-boy for identification if he should be lost ty-months-old boy. orkidnapped. The child’s foot is brought in contact witha The police could pick surface evenly inked, and it is then evenly impressed upon him out of any num- . a sheet of paper. The ridges in the skin on the bottom ber of lost children of the foot furnish unmistakable details of identification 80 .

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Apri, 1920 HEN you emerged \ \ from the measles your room was fumigated so that the rest of your family wouldn’t catch ’em. Just so, when part of a tree becomes diseased, the other trees are also fumigated so that they won’t catch diseases. But fumigsting rooms and fumigating trees are vastly different jobs. By closing the door you can shut off a room, but in order to fumigate a tree you must put a tent around it to shut it off from its neigh- bors. What is the quickest, easi- Fumigating a Sick Tree A balloon drops a tent over it and the deadly. parasite-killing fumes are released By P. Schwarzbach est, and best way of accom- plishing this? Mack Swain, of Los Angeles, will tell you to drop a tent over the tree by means of a captive balloon. Perhaps you have heard of Mack Swain. He isa well known slap-stick moving- picture comedian. He has recently patented his idea of fumigating by balloon. The tent is hooked to the balloon, which is moved until it is directly over the tree. Then the balloon is lowered. The tent opens like a para- chute, and settles comfortably Insects were ruining a fruit tree, and the owner decided to fumigate it. A captive balloon with a tent hooked to it was brought directly over the tree and lowered. The tent opened up like a parachute and settled over the tree 81 The tent was fastened into place and then deadly fumes were released inside of it; the insects and their eggs were quickly killed, whereupon the balloon carried its, tent away over the tree. The balloon is then unhooked and starts back for another tent for another tree, while the tent it left behind is fastened to the ground. Hydrocyanic acid does the fumi- gating. It is a deadly volatile poison, and as it fumes away it kills ali the insects on the tree, and even the insects’ eggs. This acid is also known as Prussic acid. It has the seductive odor of peach blossoms. When the tent is securely fas- tened, the tanks of hydrocyanic acid are shoved underneath it and opened. After the fumes have done their deadly work the balloon is brought back to the scene of action, the tent is hooked on again, and away the balloon goes to another tree. Mack Swain, the inventor of this device, is not the only moving-picture comedian who is interested in it; for Chester Conk- lin, who spends his working hours trying to dodge pies, dough, and soft tomatoes, has bought a forty per cent interest in the patent.

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Buzz-z-z—You Forgot the Light It Tells the Time in Words ID you’ ever re hear the story of the man who left anelectric light burn- ing on the day he started on a trip around the world? When he returned it was still burning— | ™ and he had to sell his house to pay (L the bill. There has recently been invented a switch that makes it almost impossible to forget to turn out the light. It is intended primarily for cellar, attic, and closet lights, although it is equally serviceable elsewhere. As soon as the light is turned on, a gentle buzzing begins, continuing until the current is switched off. The device, . which is merely a combination of an ordinary snap switch and an alternat- ing-current buzzer, is easily installed and soon pays for itself. The Postman Brought This Wall-Paper ATHER BUCCI, a Califor- nian, has papered a room with 105,000 stamps coming from thirty-five nations. Three designs compose the walls: one from ceiling to picture-molding, one from picture- molding to chair-level, and another design from the chair-level to the floor. The design includes the Ameri- can and Italian flags, all in stamps. It took Father Bucci about ten years to collect the stamps, and another six months to arrange them. From the minute you turn on this switch till you turn it off, its partner will buzz I See sr a \| | Here is the mech- ‘needle, anism, showing the strip of film upon which is re- corded the voice that announces the hours. horn projects the sound upward In about five min- utes, when this clock speaks the quarter - hour, Popular Science Monthly " HREE o'clock!” This clock does not strike. It speaks and tells you the hour and even the quarter- hours. Such is the marvel of an English clockmaker. The mechanism of the clock is connected with a film on which has been recorded the human voice. The film moves so that a phono- graphic arrangement connected with a horn operates when the hour or one of its quarters is to be announced. In the ordinary pho- nograph the stylus, or ” travels around the grooves of a cylinder or disk upon which the sound waves have been recorded. In the speaking The clock the needle is station- ary, resting upon a strip of film, which travels over a drum, and with slight latitudinal motion it fol- lows the oscillations of the everyone in the sound waves. recorde’ room will start upon the film. Outdoor Moving-Picture Shows ' ERE come the movies!” This is the shout of the children in country villages when they see a certain motor-truck coming down the road. Indeed, traveling movies are now common in Europe, because day- light is no longer an obstacle from mixing with the light of the image on the side from which it is projected. This is done by enclosing the projecting apparatus in a light- tight compartment. The invention lends itself to many applications. to outdoor shows. The invention that made this possible is based upon the construction of a screen which absorbs the rays fall- ing upon it while transmit- ting the rays from the other side. With such a screen, all that is required is to keep the light from the outside Pasted on cloth so it can be removed, this wall-paper rep- resents ten years of stamp-collecting Here is the traveling “‘movie,”’ showing a picture in full daylight as it appears on the side of the truck 82 Showing a moving picture on the wall of a room in broad daylight a fee? Oe Bele aa, nen st hCUlrnel elem ee ee le

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April, 1920 It Simplifies the AVE you ever tried to cut a circle out of a plate of glass, and if so how did you succeed? The surface of the ma- terial is so smooth that, even if your glass-cutter were fixed to a compass, it would not enable you to cut a clean circle unless a special arrange- ment were made on the order of an interesting invention that has just been patented. The operation of the device is simple. The plate of glass to be cut is laid on a table and the upright standard of the cutter is securely fast- ened. An arm extends from this standard, ter- minating in another up- right tubular standard from which extends a bar bearing a scale in half-inches. The glass-cutter is at- tached to this bar, and rotates around the sec- ond standard, which is clamped down by the little spindle-head on top of a strong spring. If 4 Vf The left hand turns a spindle-head, which clamps the standard down upon the plate of glass, while the right hand acjusts the position of the glass-cutter The right hand now prepares to swing the cutter around the standard to sweep out the circle. By this new device you can cut glass quickly and accurately Cutting of Circles in Glass the circle: is to be six inches in diameter the cutter is slid outward on the bar three inches along the scele, and with a sweep of the hand the gless can he quickly and accurately cut. Decisive action, the accurate sweep of the hand, and the right pres- sure are demanded of the glass-cutter if he would make a _ perfect rangement of the com- pass enables one to give just the right pressure bearing upon the glass while he sweeps out the circle. The device being clamped to the table in a fixed relation to the position of the sheet of glass makes it possible to cut duplicate circles with the utmost economy. Every circle will come from the same portion of each plate or sheet, and there will be no haphazard guesswork, resulting in loss of material. When Coal is Short Run the Factory with Tractors During the recent coal famine, when government regulations would have reduced the working hours and put many employees in idleness, at least one enterprising manufacturer succeeded in Overcoming the difficulty. With gas engines and a steam road- roller, sufficient power was generated to keep the wheels of industry turning. busy. Outside the factory building the heavy road-roller did the work of the electric motors. building the gas engines did their duty, keeping the machines Several tractors were also used to drive generators, and these furnished electricity for lighting the entire plant Inside the

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Hitting the Moon with a Rocket Professor Goddard of Clark College plans to fire off a cracker right under the nose of the man in the moon By E. F. Richards FEW menths ago the plausibility of reaching the moon was con- sidered in these pages on the basis of some calculations made by the French aeronautical engineer Robert Esnault- Pelterie, who showed that the most compact explosive known did not carry within itself sufficient energy to convey it to the feet a second, as in the ships’ rocket, . the charge required, per pound carried to the moon, would be the seventh power of 602—that is to say, 14,290 million million tons! It will thus be seen that Professor Goddard’s improvement in the design of the sky-rocket has, at a single step, Popular Science Monthly fessor Goddard has not only worked out the problem on paper: he has conducted experiments to furnish the experimental data required. It would, of course, be impossible to follow the course of such a small body through the 240,000 miles that sepa- rate us from the moon. But the rocket moon by its own power. Here are two forms of Professor Now Professor rv OTED — FR GROSCOPE Goddard’s rocket. Note in each Goddard of Clark cvoncyor atm NONROIING case the tapering nozzle, the College, Worces- slit —~ [Ve] CAMERA fundamental feature of the inven- tg: gga 5 4 ROTATING tion, by which the efficiency of the ’ 6 ” ° ROSS-BAR forward with com- etateliate putations and ex- periments __ that cast an entirely new light upon the situation. In TENSION | SPRING : A 5 INDUCTION Bad COIL | . * BATTERY ees the first place, it a a is to be observed a that, in order to seine EN CASING TAPERING reach the moon, it is not necessary that the explosive Lt employed should i & possess sufficient 4 energy to carry the whole of its CHARGES BREECH BLOCK 1 GUIDE F-FLAT SPRING y] | STATIONARY t BREECH BLOCK DISCHARGING POSITION rocket is raised from the best previous record, namely two per cent, to sixty-four per cent. The drawing on the right shows a double rocket, the fuse of the small upper rocket projecting into the charge of the large lower rocket, so that the small rocket is fired off at the moment the charge in the large rocket is exhausted. The drawing on the left shows a type of rocket in which the charge is divided into a number of separate cartridges, which are fired off one after the other. The ignition. is effected by a battery and induction coil. In the head of the rocket is placed a gyroscope which keeps the rocket pointed in one direction FUSE ROTATION CHARGES eS N~ EXPLOSIVE NS DISKS \ TAPERED \ COMBUSTION \_—TUBE weight to our sat- ellite. For, as a rocket proceeds on its course, it continually discharges a part of its mass, so that only a fraction is carried ine whole distance. Secondly,—and this is where the significance of the recent computations and experiments appears,—it has been found by calculation that the velocity of the gases issuing from the rocket, by which velocity the kick is produced, has an extraordinarily great influence upon the amuunt of explosive required. Professor Goddard has succeeded, in his experiments, in raising the velocity of the gases discharged by the rocket from 1,000 feet a second, the best performance of ships’ rockets now on the market, to 7,000 feet a second. The best rifle hurls its bullet out of the barrel with an initial velocity of less than 3,000 feet a second. The full significance of this can be appreciated only when we consider some actual figures. So, for example, Professor Goddard’s computations show that in order to kick one pound frem the earth to the moon requires, under the most favorable circum- stances, an explosive charge of 602 pounds. This is assuming a velocity of 7,000 feet a second for. the gases discharged by the rocket. But if we were restricted to a velocity of 1,000 transferred the enterprise of hurling a missile to the moon from the class of utterly impractical dreams to the domain of entirely feasible and even comparatively light tasks. The principal feature of Professor Goddard’s improved type of sky- rocket is the tapering nozzle, designed on the principle of the turbine nozzle, so as to utilize the work of expansion of the hot gases. This design has in- creased the efficiency of the rocket from two per cent, the best perform- ance attained hitherto by any rocket, to sixty-four per cent, exceeding by far the record of even the very best of internal-combustion engines. For the present we may leave out of consideration the plan of anything like a personal visit to the moon—the chief difficulties here are physiological, not physical. But we can, if we want to, reach out a long arm and tickle the moon, as it were. Here a new problem arises. Suppose we send a rocket to the moon. How shall we know whether our aim has been true and the shaft has gone home? Pro- 84 could be made to carry a_ charge of flash - powder arranged to go off when it hit the moon’s dark sur- face, the event being brought off about the time of new moon. And the amount of flash - powder required can be easily determined by a simple ex- periment. Pro- fessor Goddard found that one fifth of a grain of powder made a flash plainly visi- ble at a distance of two and one fourth miles. To produce an equally visible effect at the distance of the moon would require, accordingly, a charge of about fourteen pounds. As- suming that the total weight of flash-powder, plus acces- sory apparatus, were four timesthis amount, the total charge of explosive re- quired would be about Profes- sor Goddard’s invention is intended to carry aloft registering instruments seventeen tons. and even cameras. No telescope can fol- low the course of the rocket; but a charge of flash-powder could be carried which would explode when it hit themoon’s dark surface

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To Hit the Moon with a Rocket Professor Goddard, of Clark College, has invented a rocket that operates on entirely new principles, and that would make it possible to hit the moon. It has been estimated that with ordinary rockets it would take 14,290 million million tons of explosives to reach the moon. Professor Goddard’s rocket requires only 602 pounds, because the gases are discharged, not at the usual rate of 1,000 feet a second, but at 7,000 feet. The fastest projectile hurled from a rifle has a velocity of less than 3,000 fett a second, from which it.is seen what a marked im- provement Professor Goddard has made. The total charge of explosive required to reach the moon would be seventeen tons, equal to the total weight of ammunition discharged by a battle- ship when it shoots off all its guns at once. In other words, Professor Goddard’s improvement at a single step transfers the enterprise of hurling the missile to the moon from the class of impractical dreams to the domain of comparably simple tasks

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ee me come mmenaeinan oe re eS ae wrebecu. a oe er DS Sem eT ey eae a SI" Re a orate oc Sic ire e bi cies Fc eee gat 8 tip idaleseltrtahcengiesbee spe Popular Science Monthly Spring Cleaning the Automobile for Summer Economy By Fred Gilman Jopp UTDOORS na- ° QO ture is dressing field and tree with new style greens. Indoors your wife serves the meals on the kitchen table and clutters up the floor with rolls of carpet—it’s mere- ly spring cleaning. Your share is await- ing you, so put on your overalls, go out to the garage, and take the car out of winter storage. It should be gone over at least once a year, to eliminate many of the summer troubles that result from lack of preparedness. To make a thorough job, it is best to start at the front of the car and work back to the rear axle. To Find the Leaks First, disconnect the radiator from the car and take it off. Plug the inlet and outlet holes with wooden blocks. Stand the radiator on the floor and force water into it with a hose. If It is a simple matter to jack up the wheels of the car and lubricate the four springs. A thorough greasing at this time will eliminate all those annoying squeaks there are any leaks they will now be visible. Scrape these spots with an old knife and cover them with solder- ing acid. Then apply the solder with a soldering-iron. Wash out the radia- tor with a solution of hot water and washing soda, and rinse out with cold water from the hose a few times. Cover the gasoline line: carefully. Disconnect the joints and blow into them with the tire-pump. This will remove any sediment and save a possible stoppage of gasoline later on. Examine the line for leaks. Some- times dirt works into the carburetor strainer and collects there. Wash it out carefully or it will cause trouble. Drain the old gasoline from the tank; it is no good now except for cleaning purposes, for its strength is gone. Use the hand crank to determine the engine’s compression. You can tell by the ‘‘feel’’ of each cylinder whether the valves need regrinding. If they are ground at this time they will go fora long time in the busy season before they need grinding again. The fine grinding compound is best, since the coarse usually leaves in the valves deep ridges that must be ground out. Wash the engine carefully after you are through with the grinding opera- tion, or some of the compound will get into the cylinder walls and continue to grind into your expense account. Make sure that there is a clearance between the valve stems and lifters; otherwise the valves will not seat and there will be leakage. When adjust- ing the lifter, test for clearance after the jam nuts have been tightened, for the tightening of the locks may alter the adjustment. Taking Your Car in Hand Serious repairs on the ignition units must be taken to an expert. Don’t try to make them yourself. A study of your car’s wiring diagram will be valuable at this point, for with it you can trace each wire to its respective terminal. In- spect the ing wires that lack proper fastening. Remove the cover of the ignition dis- tributor, and use a fine flat file tosmooth down the points, but don’t remove more metal than is necessary. Adjust them when you are finished using the gage provided for the purpose. Carbon _ brushes that stick can be loosened with a drop of gasoline; weak spring pressure can be increased by pulling the spring apart with the fingers. The steering wheel play may be taken up in the gears at the bottom of the steering-post. Tighten all knuckles and lubricate carefully. Should any- thing go wrong here when the car is under way, a bad accident is sure to result. Drain the transmission and rear axle assembly with two quarts of kerosene to flush out each casing, and refill with a standard lubricant. Go over the brakes carefully; clean ‘them and fit new clevis pins if neces- sary. Adjust the brakes by jacking both rear wheels from the floor and allowing the engine to run with the car in high gear. See that both wheels stop the instant the brake is applied. Lubricate every part as explained in your instruction book. The differential, axle, and universal joints are difficult to get at, and are therefore often neglected. Get after them now and clean and lubricate each part carefully. Look over the chasses and body. Tighten all loose bolts and nuts. The front axle rarely needs attention, but if there is too much end play, take off spark-plugs for cracked porcelains; clean and adjust the points that should be spaced the distance of a thin dime apart. Ex- amine the wiring for rotted insula- tion, taping, and applying new wire when neces- sary. Clean and __ tighten all terminals nuts and bolts. and support- 86 Most “rattles” on a car are caused by just one thing—loosened nuts ¢ Make it a point to find and tighten each one individually, then you won’t be troubled with squeaks later on ea)

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April, 1920 Zcos Aids To Promoting Health, Comfort and Economy in the Home. Dees Wall Thermometers To help you main- tain a temperature in your house conducive to good health. Ireos Bath Thermometers To enable you to get the most good from your bath. HNRCESLUREASEARESANERRSOEREAGSUSOUUERO RUE DESESNIELEORCSSOU PELE erate Inter Home Set or Bake Oven Thermom- eter. Candy Thermom- eter. Sugar Meter. The secret of accurate results in cooking. eos Hygrometer Be To enable you to keep TTT iitiitis RESILEPRELELEED PETE? atmosphere in your home correct at all times. Jyeos Weather Barometers accuracy. - Jpler Quality Compasses country. Bees Fever Thermometers TEDRRUGUELELGESMAERUSOIOGEGETSDELODEDSOSES ET EACRRT ELE EEE FIRGERLETTER home. Office hermometers business efficiency. (Ask Your Dealer) JRRETEUEATECRLET ROIS EERE RESTS s TAREDREDERLEDGODAGDTERLERERGDTGAGGREAL/EABARLEEG RELICS the humidity of the * Forecast the weather twenty-four hours ahead with dependable To show you the right way in unfamiliar A necessity in every An aid in promoting SREEHREEUEGLODGATERSOLLTIG? TTT ILL LU Patt iitiiiii iy Zecos Instruments in use in modern cannery can in twelve. Formerly the housewife had to trust to experience, ‘‘guessing,’”’ or ‘looks.’ But today the canner and increasing thousands of modern housewives, cook by the ther- mometer —the secret of accurate results. When a corn canner, for instance, cooks, mechanical arms stir the corn in a huge kettle. A metal rod dips into the kettle too. It’s like your finger, that rod. It feels how hot the cornis. It expands and contracts with the slightest drop or rise in temperature and signals back to a valve on a steam pipe. ‘‘ Turn off the steam,” it says if the corn is too hot; or ‘more heat,”’ if the temperature is falling. And the regulator responds instantly by moving a valve, The Thermometer The 100% Efficient Cook “My Wife’s strawberry jam” Oh, MAN, what eating ! HAT if one jar in a dozen “works.” No housewife is a failure because of that. But, suppose a canner putting up thousands of jars of preserves, or baking beans by the million, loses one jar or What would happen? Bankruptcy. How is it then that your old-fashioned home cook—your idea and mine of the world’s best, when it comes to ‘‘eats,’’ doesn’t show up 100% efficient and the professional canner does ? Temperature Control. That’s the answer. That’s the principal reason why one can of corn on the grocer’s shelf is as good as every other can of the same brand. In hundreds of the large canneries here and abroad Jeos Temperature, Indicating, Recording and Controlling Instruments are used.- They are regarded as the standard of accuracy just as they are in hundreds of other industries. There are over 8,000 different kinds of instruments in the Jeose line. At the left we list %eos Instruments for home use. Ask your dealer about them. If he won’t supply you, write to us direct sending dealer’s name.g Literature on any instru- ment or type of instruments in which you may be interested will be sent you promptly. Taylor [Instrument Companies Rochester, N. Y. There’s a Beos or Faxler Thermometer for every purpose.

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ARREST the hub caps and adjust the bearing cones so that the wheels will turn easily without dragging. Fill the caps with grease. This will be forced through the bearings and will thor- oughly lubricate them. If when adjusting the wheels a grinding sound is heard in the bearings, take off the wheel. There may bea broken ball, a scored ball race, or a worn cone. Replace them with new. Look to Your Storage Battery Start the engine and note whether the ammeter indicates the proper charge, that the lights are burning properly, and that the storage battery shows a strength of 1.275 at least. If the battery has been left on the car all winter it is ruined, and if it shows no strength or the plates have turned white, take it to a battery station for overhauling. Hold your hand at the bottom of the radiator to see if it, gradually grows warmer—this denotes that the pump is working ‘properly. Pull the throttle wide open quickly to see whether the carburetor needs adjusting. Listen carefully to the engine’s sound the first few minutes. An expert automobile and carriage painter can obtain the real “factory finish,” but it’s well to know how to do the work yourself and save the money. When the surface is in good condi- tion and it is desired merely to freshen the colors, clean off all dust, dirt, and grease with benzine or turpentine. Next sandpaper lightly to cut the gloss, and then apply one or two coats of a good automobile finishing varnish. How to Paint Your Automobile If it is desired to change the color, first thoroughly clean off all foreign matter with sandpaper, apply two coats of automobile enamel of the desired color, and varnish. When the surface is in bad condition and the paint has been chipped or Popular Science Monthly cracked, remove all loose particles and prime such spots with lead and oil primer, composed of lead in oil thinned with turpentine and a little Japan drier. Allow it to dry for twelve hours. Deep cracks and dents should be plugged with filler and knifed on as you would use putty. Allow to dry eight hours, and sandpaper level. To even up the surface, apply one or two brush coats of the filler and surfacer, eight hours apart, toning down each coat with sandpaper. Next apply one or two coats of good automobile enamel, and the job is done. If, however, an exceptionally high finish is desired apply a coat of automobile finishing varnish. These various treatments, will give your car a factory newness. Care in the operation of a car just after overhauling is as essential as in that of a new car. Don’t forget that it takes only a few minutes of careless operation to cause great damage to your automobile. Up the Amazon River with a Piece of Wire WO out of three of my canoes had i gone under in the Rapids of the Devil, and with them had disappeared all my instruments, maps, and records. Seven out of nine in the party had been thrown into the whirling, roaring waters, and had just escaped with their lives. I had gone under four times, and had been carried a mile down the cataract before I was saved by grasping the low overhanging branch of a great tree that stretched far out over the waters. Fortunately, one of the boats had escaped, and by its use the struggling men were rescued. The accident had occurred about four miles down river from our starting-place below the falls of the Papagaio, near the Indian village of Utiarity. Utiarity consisted of a telegraph station, a storehouse, a few adobe huts, and about fifteen wickerlike structures in which the Indians lived. In the storehouse I found, to my delight, a copy of the nautical almanac for 1914, which I had left behind on our first start, an extra’copy that I could spare at that time. I took this copy along, as reading matter, every- thing of that sort having been lost. Rather poor reading matter, and I little thought at the time how valuable it would prove later. As we journeyed down that inter- minable waterway, with its never- ending forest-covered banks, its many rapids and cataracts, I was often troubled to know just where we were. I had noticed that the sun was ap- proximately in the zenith. We were traveling north. At that time of the year, February, the sun was also traveling north. My nautical almanac gave me the position of the sun at noon at Greenwich. If I could find the time of apparent noon at our midday stopping-place, and also. be . ward, By Anthony Fiala able to determine whether the sun was in my zenith, it would be a simple matter to compute our latitude; for the declination of the sun at Green- wich, corrected for the difference in longitude, would give me the latitude The wire was bent in the manner shown, and with the help of the sun the lost explorer found his location without further calculation. I knew our longitude, for I remembered the position calculated for Utiarity, and the river had flowed steadily north- so that our longitude was practically unchanged. After thinking the matter over, it occurred to me that I had a small piece of insulated copper wire in my pocket. I had carried it there ever since I had found it hanging to the outside of a small telegraph hut along the line of the telegraph trail while our pack train was crossing the Divide. It was not in use, so I detached it, thinking that a good piece of copper wire should not go to waste and that it might be of value to me later. It was! The insulation was burned off in our noonday cook fire, and I rolled the wire flat between two stones and bent it into the form of a square, with 88 one side prolonged as a plumb-bob, as shown in the illustration. A part of the wire was bent into the form of a handle, so that the contrivance could hang free and be acted upon by gravity. When the sun seemed near the zenith, I suspended the little square from the handle, with the top wire pointing north and south. If the sun was still a little toward the east, shadows from both the top and bottom wires would be thrown on a paper held below. When the shadow of the top wire covered that of the lower wire, giving only one thin shadow line, I knew it was apparent noon at that place. Noon having been determined, I turned the square east and west, that is, at right angles to its former position, in order to determine whether the sun was north or south of my position. If one thin shadow of both wires was projected on the paper, the sun was in the zenith, and I had only to pick out the declination of the sun for noon at Greenwich for the day from my almanac, and correct it for difference in longitude, to find my latitude. It was a great pleasure each noon- time, if the sun was shining, to work the little instrument of wire and determine my latitude. I had marked off the paper into degrees and half degrees on each side of a penciled meridian line, using the graduations of a compass owned by Lieutenant Loreado, the needle of which was just half the length of the plum-bob wire of my instrument. These degrees served as half degrees for the instrument. When we reached a point where we could meet with men again, I found maps, and was much pleased to see that several of the latitudes secured with the little rough instrument close- ly approximated the true latitude of _ our noonday halts.

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Copyright 1920, by The Goodyear Tire & Rubber Co. 100% Goodyear-Equipped—and the G.T.M. A growing conviction that the Goodyear analysis 100% Goodyear-equipped today—this is the re- é plan gave promise of ending their continual trou- sult of expert study followed by the service that bles with belts led the Toledo Cider & Vinegar Goodyear Belts specified to their work always Company to have a single drive studied by a yield. On the press drives there are Goodyear G. T. M.—Goodyear Technical Man—and his Glide Belts, recommendation for a belt given the benefit of a trial. On the main-to-counter shaft trans- mission, and on pumping duty, are 5-inch, 4-ply conener goaggenag ep Chas —. = 7’ . enduring. In line with the same principle o The G. T. M. did not say offhand, “Put on a every unit's relation to the work of the whole Goodyear Belt.” His first request was to see the plant, the G. T. M. specified 5-ply Goodyear drive for which a belt was wanted. He studied Monterey Acid Hose for the conveying of the the actual conditions under which the belt must product pressed out under the action of the operate. He figured pulley dimensions, center- power carried by the belts. At the end of a full to-center distances, operating speed required. season’s run, the Goodyear equipment shows He noted that a belt to be successful in this practically no wear and has furnished new records plant must resist the action of vinegar acid. or energy conserved and power transmitted. In a word, he went to work on the principle that a belt is an integral part of the plant's Single drive or entire plant, the G. T. M. looks production line. at any problem put up to him in the light of its relation to profitable production. And the Good- The results from the Goodyear Belt applied year belt he recommends is chosen first for its after this study made their own argument for an ability to perform its part unfailingly, trouble-free, extension of the analysis to the entire plant. The over a long period of economical service. The G. T. M.-specified Goodyear Belt held the pulleys, G. T. M.’s services are at your and your plant where other belts—bought on the basis of taking superintendent's command, without charge. Your whatever the jobber happened to have in stock— profit and satisfaction from Goodyear Belts speci- slipped, and lost power, and tied up units in fied on the basis of his analysis are ample as- troubles and delays that cost money. surance of our return. BELTING + PACKING HOSE-VALVES

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canes TS ii 7 _ ee arte tine rrr ote aPNGRE SS a anes, om NS a anes a a. ie & mi Co., and — Sediment. Then pour a can of ‘‘X” ee ee ae ee Liquid into the radiator. Leave it Large Size, $1.50 there a few days. This will clean . the cooling system walls from Rust Will do a $25 and Scale now present. Drain the repair job! radiator. Save the “X” Liquid by ° straining through cheese-cloth. Pour Ford Size, 75c back the ‘“X” and no new Rust or Write for proof of how Scale will form while the “X” is in me ca of X Liquid did the water a $150 repair job ““X’? LABORATORIES, 25a West 45th St., NEW YORK CITY Pacific Coast Branch: 450 Rialto Bldg., San Francisco, California. “SE Liquid mina es. edenrsss

90

Popular Science Monthly The Packing-Box Turns Dressing-Table N adornment to any bedroom is this very useful dressing-table made from a large packing-box.

MIRROR about 3 ft. long, w/ /\\ 21% ft. high, and yfyf ij lor 1)% ft. wide (///"\ will serve the seunal \ purpose. Set the box with the ” open end out- - ward, as shown in the _ illustra- tion. Then nail enough boards 2 ft. long on its top side to form In these high-cost-of-liv- the table-top. ing days a dressing-table This makes a made from a_ packing- strong and box is very acceptable roomy top. When papered inside with a pretty wall-paper, the box will serve admir- ably as a receptacle for shoes or small household articles. The top of the box is padded slightly and covered with cretonne, while cre- tonne curtains are fastened around the edge by brass tacks. A mirror and a glass shelf complete the dressing-table.—LUCILE E. CLOSE.

Keeping Small Bolts and Screws Conveniently HE illustration shows a tray to hold screws, rivets, brads, bolts, and other small articles of assorted sizes. It is made from a one-inch board and a collection of tin cans of medium size. The cans are cut lengthwise, leaving a tab on each side. These tabs are flattened out, and have holes

Some old tin cans cut lengthwise and a piece of board make this handy screw and bolt tray punched in them. When square holes of suitable size have been cut in the board, the cans are tacked securely to the under side so as to fit beneath the holes. Sliding ways may be provided under a work-bench or a cabinet, and the trays made to slide in like a drawer. Each of the small receptacles being rounded on the bottom, small objects can be easily picked up with the fin- gers. If the hole in the board is a very little smaller than the can, small objects will not spill out, even when tilted.—H. F. GRINSTEAD. A packing-box

At

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a ee HH ——<——_—— — ————— ee $$$ nnn Meeting the Gasoline Crisis N nineteen years motor vehicles have increased in number 60,600%. Motor fuel production has increased only 1,500% AUTOMOBILES HAVE INCREASED FORTY TIMES FASTER THAN GASOLINE PRODUCTION

To get more and more gasoline out of pe- troleum, oil refineries have had to lower their standards. Gasoline is getting heavier and heavier. It is more like kerosene this year than ever before; it will be still more like kerosene next year. But automobile engines are designed to burn the gasoline of five years ago—not the gasoline of today. They are hard to start; they waste fuel; they are inefficient. You can’t burn big lumps of coal in a stove in- tended to use peacoal; you can’t burn the gasoline of today in engines designed to burn the gasoline of yesterday. Professor Fishleigh of Michigan Univer- sity has shown that out of a dollar's worth of gasoline most engines get only ten cents’ worth of useful work. Now the engineers of Chalmers Company decided several years ago that engines must be improved so as to burn gas- oline of today—not to waste it. Two years ago they gave the world the Chalmers Hot Spot engine with the Ram’s-horn intake manifold. What is the Hot Spot? What is the Ram’s-horn? Present day gasoline doesn’t vaporize easily—doesn’t produce “gas,” Whole drops of gasoline are sucked into the cylinder through the intake manifold. In the Chalmers engine the gasoline, wholly or par- tially vaporized, strikes the Hot Spot before it enters a cylinder. Instantly the drops are changed into “gas.” Not raw fuel, but “gas” is fed to the engine—something which will burn. The Ram’s-horn intake manifold makes it easy for this pre-heated, completely vaporized fuel-to enter the cylinders. It is shaped like a ram’s horn in order to get rid of sharp cor- ners. Every gas is composed of billions of molecules. 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.

CHALMERS MOTOR CAR COMPANY, DETROIT, MICHIGAN CHALMERS MOTOR CO. OF CANADA, LIMITED, WINDSOR, ONTARIO MAXWELL MOTOR SALES CORP., EXPORT DIVISION, 1808 BROADWAY, NEW YORK

The Hot Spot and the Ram’s-horn do this: They make it easy to start. They give you more miles per gallon of gasoline. They reduce carbon deposits in the cylinder. They make it impossible for raw, unburnt fuel to drop down into the crank case and ‘‘cut’ ” the lubricating oil.

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, MADE BY SANFORD MILLS i ME. F TER years of scientific research and experiment Chase Leatherwove. was produced to fill a much needed want—an appropriate and practical material for upholstery purposes. For Motor Car, Furniture, Carriage and Boat Upholstery Characteristics not found elsewhere have been given to Chase Leatherwove by special processes. It is the better upholstery material of today—durable—especially tough though pliable—distinctive and rich in appearance; water proof; easily cleansed; economical. Re-upholster with Chase Leatherwove. An inexpensive amount of Chase Leatherwove willdo wonders. The results will please you. Like several other nationally known products bear- ing the ‘‘Chase” trademark, Chase Leatherwove is strictly a high-quality, reliable and honest production backed by our reputation gained through seventy- three years of manufacturing leadership. Samples of this Better Upholstery material on request. Always demand Chase Leatherwove. Manufacturers of Trunks and Bags, Shoes, Books, Novelties, etc., are asked to see the several different grades of Chase Leatherwove, made especially for their use. L. C. CHASE & CO., BOSTON ; NEW YORK DETROIT SAN FRANCISCO CHICAGO Leaders in Manufacturing Since 1847 Other products of our mills: Chase Drednaut Motor Top- Chase Velmo Upholstery Fab- ping; Chase Plush Motor rics; Chase Furwove Fabrics; Robes; Chase Horse Clothing Chase Wexford Motor Cloths. Selecting the Right Bolt at Popular Science Monthly a Moment’s Notice ‘HE construction of a bolt, nut, and washer rack that may be either secured to a wall or placed upon a bench is shown in the accompanying illustration. The washer rack con- sists of a piece of wood, A, about 2 by 4 in., into which are driven pieces of With the rack here illustrated you can select immediately the par- ticular bolt or nut you _ desire Y-in. round stock corresponding in number to the different sizes or varieties of washers used in the shop for which it is built. The end pieces B B, cut from 1-in. wood, are nailed or screwed to the ends of A, and near the bottom a series of wooden bins are built in for holding a variety of bolts and nuts. The sizes of bolts and washers are marked on the edges of the rack, making it possible to select a wanted size bolt, nut, or corresponding washer in a moment. Two Useful Suggestions for the Motorcyclist MOTORCYCLIST of experience never goes out without having prepared himself for any emergency. He carries as many duplicate parts of his machine as is convenient, and he carries whatever tools may be neces- be A convenient holder for small parts made from a piece of inner tubing vulcanized at one end sary to put them on. Two helpful ideas are shown in the accompanying © illustrations. One illustration shows a good way to carry such small parts as bolts, nuts, chain-links, and the like. A small length of an old inner tube from a motorcycle is cut off, and one of the ends of this length is vulcanized to- gether. The parts may then be placed in this, and the open end of the holder can be folded down and secured by a rubber band—or, better still, by a

Page 73

April, 1920 Why the Notches? The notches or side vents in a Kelly Caterpillar tire are not put there for ornament. They serve a very definite purpose— several, in fact. They give greater traction. They enable the tire to grip the road surface. A Kelly Caterpillar can roll serenely over a road on which the ordinary tire would be helpless without chains. They greatly increase the tire’s resiliency. In a Caterpillar the rubber displaced under load pressure has some- where to go—and it can go there quickly. The traction wave is practically done away with. It is broken every few inches so that it has little opportunity to damage the tire or hold back the truck. These are merely the advantages which the notches add to a tire that even with- out them would be in a class by itself. Kelly-Springfield Tire Co. GENERAL SALES DEPARTMENT New York, N. Y. KELLY truck TIRES

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points of aW DC. in every line. -

“TPs a WDC? ms The man who knows pipes is quick to recognize the finer

Hesees careful workmanship | | He appreciates : - the improved smoking qualities at 4 that Demuth seasoning gives. ae am 3 Genuine French Briar. Se eee. Your dealer carries sand re- pe Bigs

tWANTED Representatives in Every Facto Po>ular Science Monthly keeps abreast of the times in new inventions and discoveries. Many of the new ideas come from the skilled work- ed in the fac “tory. we hone Co oe in every factory in the country. It will you make good. POPULAR SCIENCE MONTHLY. 225 West 29th Street, New York How to Make Wireless Instruments A little book that fully describes the construction of spark wireless instruments and apparatus. Just the thing for the amateur. Illustrated. Price, postpaid, 25c. Book Dept., Popular Science Monthly 28 West 39th St., New York City

$3 month $4 WILL BUY A Beautifully Reconstructed

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, Ill.

Book on Law Free <={\ Write today for our new 171-page book #4 on ‘*The Power of Law ining.’’ It carries : a vital and inspiring message to every ambitious man. Find out about the opportunities that await the law trained man. Find out how you can learn from masters of the law right in your own home. 1\ No obligations. The ic is absolutely REE. ; while we are making a 3 wane te Teday- special reduced price offer. — agguaemies col of Law 1894 Mar Manhattan Bid i: Ulinotp

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Popular Science Monily small catch such as might be taken from an old bicycle tool-bag. A holder such as this will keep all the parts safe and clean. When folded up, it will fit in any corner of the motor- cycle tool-box. No special wrench need be carried for taking off such parts as are ordi- narily inaccessible to the monkey- wrench. The ordinary wrench may be used in con- junction with a pair of pliers in the manner shown in the illustration. Here the air- valve casing of the carburet- or is being re- moved when usually the wrench alone has not enough leeway to allow it to turn the casing at all. The head of the casing is simply grasped by the pliers, the monkey-wrench is fitted over the pliers near its joint, and by twisting on each of the two the parts may quickly be removed.

A wrench, in conjunc- tion with a flat-nose plier, removes parts that could not be taken off by the wrench alone How to Make a Bench-Clamp that Will Hold HEN two boards are to be held together for any length of time and a screw clamp is not handy, build one like the following and it will do good service. Form a base of hard wood in about the proportions shown in the illus- tration, and set in two long screws somewhat farther apart than the pieces to be clamped together. Then whittle out two levers of hard wood about 34 in. wide in the middle and A sa PTT TELE | ts To SSS SSS a TT na

A clamp that is very easy to make and very serviceable to have about any work-bench slightly tapering toward the ends. One side is straight and the other slightly curved. Set these between the screws and place the pieces to be clamped between them. Next drive a hard-wood wedge between the opposite ends until they spread suf- ficiently to grip the pieces tightly to- gether. To insure the clamp gripping with- out the possibility of slipping, roughen the inside surfaces of the levers and the edges of the wedge so they ‘ will not become easily polished with use.—L. B. ROBBINS.

Page 75

Projecting the world through a lens HE motion picture and the stereopticon—made possible by lenses! Lenses to record history or story, lenses to project them! Approximately 120,000,000 feet of film shown by them daily to \ millions of people in America’s theatres! And through lenses we are whisked o’er the seven seas—into dreamlands and real lands—into the midst of raging battle, or int> the peaceful love of a childish paradise. And through lenses are flashed upon the screen the miracles of growing plant life and the secrets of the microscope, made still larger that all may see. Allthe strange, new worlds within worlds—the worlds of industry, of medicine, of fiction, of love, of war, of truth—all these are brought to all the people, be- cause there are lenses—those bits of marvel glass, marvelously ground—that do weird things with light. That this institution has been the leader in lens and other optical development since the middle of the last century, is our incentive to maintain that leadership and do even more, ‘‘that eyes may see better and farther.”’ 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, inoculars and Engineering and other Optical Instruments atop maysee Petter and fa - ae

Page 76

FPLORSHEIM stands for what you want in shoes 4) —quality materials and | | workmanship—distin- | || guished style—comfort and long service. The exact | points that you would. like i i

|| to be sure of you can be || sure of in shoes bearing il the quality mark ‘‘Flors- |j | heim.” | Fifteen to Twenty Dollars Consider the wear, it il not the price per pair. it | Look for the quality mark | rr) oy - 9 Florsheim.” Hz | The Florsheim Shoe |=) hit Company te! 14) CHICAGO, U. S. A. Fl

HE F 4 i Hi | i | | f

Write for Hi 1 book, ‘‘Styles | of the Times.’’ rail The HES} Rainbow— f

The Wideawake Dealer has it He’s the ounce-o’-prevention, pound-o’-cure man ready to pre- scribe a few feet of Garco to relieve you of all future brake lining trouble. Garco Asbestos Brake Lining will not burn, Oil and dust will not harm it. The hardest kind of service is the sort of chance Garco is seeking to prove its every-way-you-look-at-it de- pendability. Ask your dealer about Garco, General Asbestos & Rubber Co. Charleston, S. C. CHICAGO NEW YORK PITTSBURGH

How to Grind Valves in an Emergency HEN a valve needs grinding and no proper tool is at hand for the job, one can be made that will serve the purpose. Cut offa suitable length

®% of round stick, ‘such asa broom- handle, and drive two stout wire nails in the flat end. Bend these to fit the holes in the valve head, or file their ends to an edge so as to fit in the slot, if the valve head is of such a nature. Then drill a hole near the top of the shank and fit in a bolt or nail, as shown, fora handle. The result is a satisfactory valve-grinder that cost nothing but a little time. Set the nails in the valve, place the palm of the left hand over the top of the shank to hold it down on the valve, and rotate the grinder back and forth by the handle held in the right hand.—THORTON HALLETT. NAILS WITH HEADS LU}: FILED OFF TOFIT : N MOLES IN VALVE. <—— If your engine valves need grind- ing, don’t wait to buy a tool—make it Using a Nail-Set to Ream into Metal Y merely substituting a nail-set for a drill-bit, holes may be en- larged and taper holes reamed or produced in sheet metal. , If the metal is relatively thick, the holes thus pro- duced will have adistinct taper. This can be off- set by reaming first from one side and then from the other. If this is done in thin sheet

ULM ENLARGED HOLE IN THIN MCTAL VIM tapers Te ect oreo a te ‘impor- tant point about this method of reaming is that it leaves a perfectly clean, smooth hole. The small burs raised on either side of the metal can be easily taken off with a whet-stone. It is also possible to stop at just the desired width of hole. The nail-set can be used in any chuck holding a round-shank bit, in a brace, chain-drill, or bench-drill. The ordinary feed should be used and a little oil applied to the point. This method is often particularly valuable in threading holes for tapping, when the proper drill is not to be had and all that is necessary is to widen a hole that is too small to permit the point of the taper tap to enter. 96 Small holes can be easily and quickly enlarged with a nail-set

Popular Science Monthly Quick-Action Advertisements continued from page 16 STAMPS AND COINS

NEVER Sell Old Coins until you see our Copyrighted 6x9 Illustrated Coin Value por (New Edition)—show- ing high prices we pay. $100.00 paid for 1894 —. S Mint. Send 10c for your copy to-day. You may have valuable coins. International Coin Co., Box 151-M, Philadelphia, Pennsylvania. CALIFORNIA gold, quarter size, 27c; $14 size ,53e. White cent and catalogue 10c. Norman Shultz, King City, Missouri.

100 Different Stamps, 10c; 200, 25¢c. Approvals. Michaels, 5609 Prairie, Chicago. STAMPS—61 different, also interesting Lists free. Postage 2c. Payn Stamp Company, 138 North Welling- ton Street, Los Angeles, California.

50 Excellent stamps—sc. Roesslers’ Stamp News, year 25c—Merit_ approvals—60% discount. 5 French Colonies Free. Postage 2c. Edwin Bailey, Farming- dale, New York. 158 Genuine Foreign Stamps—Mexico War Issues Venezuela, Salvador and India Service, Gautemala, China, etc., only 10c. Finest Approval Sheets 50% to

60%. Agents wanted. Big 72-p. Lists Free. We buy stamps. Established 25 years. Hussman Stamp Com- pany, Dept. 55, St. Louis, Missouri.

STAMPs, 61 All Di.ferent, 3 cents. Quaker Stamp Co., Toledo, Ohio. $2 to $609 paid for hundreds of old coins dated before 1895. Send 10 cents at once for new illustrated coin value book. Size 4x7. It may mean ‘o« furtune. Clarke & Co., Coin Dealers, Box 76, LeRoy, N. Y. PACKET “A” 100 varieties foreign stamps, 20c. F. J. Pope, Charlotte, Vermont. 17 Varieties Hayti Stamps 20c. List of 7000 varieties low priced stamps free. Chambers Stamp Co., 111C Nassau Street, New York City. STAM PS—50 varieties, Transvaal, Brazil, vera, Cc uba, Mention paper.

Mexico, ete., and Album 10c. 50 different U. S., 25¢e. 1,000 hinges, 10c. 1,000 mixed 40c. i ist free. - buy Stegman, 5949 Cote Brilliante, St. Louis, stamps. C. Missouri. CALIFORNIA gold, quarter size and Columbia Nickel, 30c. Villa coin and catalog, 10c. Homer Schultz, Union Star, Missouri. STAMPS—350 different maica, Portugal, Venezuela, ete., 19¢; fine collection in itself, $5.00; 100 various U.S. 50¢; hinges, 10c; agents wanted, 50 per cent. List free. stamps. L. B. Dover, Overland, Missouri. BEST one cent approvals in America. F. P. 1117 South 60th Street, Philadelphia, Pennsylvania. STAMPS—12 diferent from warring nations, 10c; 10 different foreign coins, 25c; 10 Uruguay stamps for 10e. Lists free. Toledo Stamp Company, Toledo, Ohio. OLD coins, large spring selling catalogue of coins for sale, free. Catalogue quoting prices paid for coins, ten cents. William Hesslein, 101-A Tremont Street, Boston, Massachusetts. STAMP collections, coins, bills, antique firearms, swords. Catalog free. Antique Shop, 33-A South 18th, Philadelphia, Pennsylvania. FREE to our readers.

British Guiana, China, Ja- 1,000 all different, 1,000 I buy

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How can I improve myself? How can I make myself more proficient, and thus earn more money? You don’t, have to go to college. Edi- son never went to college. But he has, we believe, the finest librarg of technical books in the world. If you want helpful, practical books on electricity, mechanics, mechanical engineering, wireiess, automobiles, airplanes, sheet metal work, woodworking, repairing, or any other sub ect, write for Popular Science \ionthly’s new book eatalog. The books described in it have been earefully selected by experts as best adapted to the needs of Popular Science Monthly readers. Our book catalog is free to our readers. A _ postal request will ring it. Book Department, Popular Science Monthly, 225 West 39th Street, New York City. 60 Different Asia stamps 25c; Detroit, Michigan. SPECIAL 1000 Different stamps, $2.60. C. E. Nickles, 122 Florida Avenue, Washington, D. C. TRIANGLE Approvals—'%c up. Three unused stamps Free to approval applicants sending references. Harfred Stamp Company, Dept. 8S, Germantown, Pennsylvania. Epa paid for Old Coins. Save all before 1898 and send for 1920 premium book, ten cents, with large copper cent fifteen cents, it may mean your fortune. E.C, Harr, Nora Springs, Iowa.

C. Reitter, Box 1054,

BOOKS AND PERIODICALS

BOOKS Thousands! All Best (Positively Brand New) Books for sale, 25c up; latest and up-to-date; finest published. Mechanics, Electrical, Chemistry, Aviation, Automobiles, Machinery, Tractors, Scientific, Technical, Salesmanship, Advertising, Accounting, Sten- ography, Dictionaries, Encyclopedias, Fiction, Agricul- ture, Educational, Drawing, Arithmetic, Mathematics, Law, Languages, Electrical, Mechanical, Civil Engineering. Big catalogues and complete lists, 10¢c (stamps or coin, nothing free) Bookbuyers: save money. Send—Now! C. Goodnow & Son, Dept. “E’’ South Sudbury, Massa- chusetts. FREE—The Western Miner three months to get acquainted; devoted to an exceptional investment and general news. The Western Miner, 2541 West 37th Avenue, Denver, Colorado. BOOK—Describing Hun atrocities and their attacks on women and girls in Belgium. 25c. Belgian Specialty House, 2806 Union Avenue, Dept. 8, Chicago. BOOKS, Science, Literature, etc. Lists. Higene’s, K2441 Post Street, San Franc B MECHANICAL, Scientific, Technical Books, covering every trade. Complete catalogues Free. Howard C pany, Dept. 83, 702 West 181st, New York. THE Truth Seekeré(in its 47th* year) is an Agnostic weekly, discussing religic~ and advocating Rationalism. Sample, mailed, One~ Dime. Catalog of Books free. 62 Vesey Street, New York. BLUEPRINTS: How to read. chanics’ Improvement Association. 100,000 USED books for sale, 35c up. Some cost $10.00 History, Scientific, Technical, Tictence, etc. Cata- . McCarthy, 1061 West Van Buren Street, Chicago, Illinois. CONCORDIA contains essays, formulas, plans. Year's subscription 50c, trial, 20 cents. Concordia Magazine, 11 Water, York, "Pennsylvania. ANSTRUCTION Book (for shop use) on i Auto-Tires, $1. Tire Equipment Company, 19 C 5 Cincinnati, Ohio. SIMPLE Wireless Telephones and How to Make Them. A good book for the advanced radio amateur on the prteeees. a and use of the wireless telephone. erice 2 5 oe tpaid. Book Dept., Popue lar Science Monthly, 225 West 39th Street, New York. Business,

See page 12. Me-

Som= -

Page 77

aTMeNT- si ao/sap/aeul WAP i WasutxoTo™? B oere- ae ‘gune 9» Agtg- special Orders tract. No, - a 4“ ocee 194-0 8. Arey» vi, os e oy e Be pert® ¢ th orery ae oapietion ° nd upoe stations eeaid gona Dee Cap city for rk core, pie prere e 5. che military 5 greeted meeenet - The trate’ oteg OSH bre, '¢ fs + fF gerne G) 4 ictal... ‘at 4 Aas Oot HARRY {7 * "The Adjuté cman C, MARCH: War: PEYTON Co, Chief f anf + of the secretary of SN 10m- F ade there’ pec. 21% " reeld be 4a Gon aitions! copies required Pr ap Ko. C2! i } + Generale is furnished nade 1% i =," ny © » > . as 8-Only one oo ‘ "9 sho 1. ox Teaching the Army to Coronatype HIS official photograph shows part of a class of sixty non-commissioned officers at Camp Alfred Vail, N. J., being trained to coronatype their army paperwork with military precision and accuracy. The confidence placed in Corona by the United States Army, born of recent experience with this little machine under conditions of a severity never before met by any typewriter, is well attested by the fact that coronatyping has become part of the standard instiuction for company clerks. Aside from its convenience and portability, Corona’s record for absolute dependability is largely responsible for its rapidly increasing use. Corona appears more and more frequently in the modern office, in the quiet and comfort of home, and, folded into its con- venient carrying case, as the companion and confi- dential secretary of the traveler. For business or personal correspondence, for reports, manuscripts, memoranda, you will find Corona invaluable, what- ever and whenever you write. CORONA TYPEWRITER COMPANY, INC. GROTON, NEW YORK Consult your telephone book for address of local Corona agency. CORON he Personal Writing Machine

Page 78

A Morrow Brake Does All Three Right You wish to stop your bicycle. That is easy if it is equipped with a |

a érrew COASTER BRAKE Simply back pedal. Four small wedges, two acting from each end, will expand the brake 1 drum. Thus the bronze *‘brake shoes” on the drum are brought into contact with practical- two wedges at each end, insuring ly the entire inner surface of the steel hub, ee over omnes and your bicycle is stopped — instantly or 3 Bronze brakeshoes being softer than gradually, as you choose. a—— ome For forward pedaling, the Morrow responds instantly and positively. Braking surface 6 3-10 sq. in.—much larger than other brakes, > *Drum’ expansion forced equally by

| You wish to go forward! Just pedal forward and the wedges will be forced outward, leav- More ball-bearings.hanother brakes, ing the «¢drum” neutral and expanding two ee te Sy «<driving rings” which in turn, ‘‘take hold” 6 Le aaa ya patang +e Seine of the inner surface of the hub and drive your 1= Ninety-five inspections,followed bya “ nal test.,guarantecing perfect service. ‘<bike” forward. - i

You wish to coast! Just let your feet remain id'e, The rear sprocket will be motionless, leaving the ‘¢drum”” and ‘driving rings’’ neutral, and you will enjoy smooth, almost frictionless coasting.

ECLIPSE MACHINE COMPANY ELMIRA, NEW YORK &

Demand the MORROW on the next rs te you Buy

THE REAL ESTATE ED DO YOU WORK IN A FACTORY? useful information for re $10 to $25 a Week for an Hour a Day estate We want a representative in every factory in the United States. You can easily earn $10 to $25 extra each week by using an hour a day of your spare time. Write to-day giving the name of the factory where you are employed. Popular Science Monthly 225 West 39th Street, New York ATOR. y ref RA

A. yet Te concise

or repairs, mortgagi trans’ etc.— ever fl ered together va this vital subiect. Cloth, 256 page: 1.50, Postpai Book Dept., POPULAR SCIENCE MONTHLY 225 West 39th Street

M. Payne jitory of * special Fedestgned for Fal o._Tois es the useful facts about buying. selling, leasing and sub-letting of of Real Es Estate f ferring, ineuring’ New York

is universal for making up Deaf-phone:, Detecti-phones, Amplifers, etc. Put a button on the outside of a window and listen to all that is said inside. Attach it to your Phonograph and transmit music, etc., to distant points. The best. Transmitter for Local and Long Distance Telephone. Saves 75% Batteries. . Super-sensitive. Send me $1.00 for one Button with free descriptive booklet E-5 and circuit diagrams. All kind of experimenters’ supplies in stock. Receivers, induction coils, condensers, etc. Price list on request. - Satisfaction guaranteed or money “* J. SKINDERVIKEN J. Inventor and Sole Manufacturer 335 Broadway, N. Y.C., or 154 W. Randolph St., Chicago, Ill.

Skinderviken Transmitter Button

98

Popular Science Monthly An Adjustable Table for the Draftsman’s T-Square RAFTSMEN can make a T- square with an adjustable blade. The head, which should be carefully made from some hard wood, such as birch or black walnut, has a router- ed depression a =e little wider than the width of the blade. One edge of this mortise is 5 at right angles ) rae», to the working Y-—~ HEAD

WEDGE 2 ( edge, while the P . other is slightly * inclined at an ACAD angle, in order to accommo- date a narrow wedge between Here is a useful piece of apparatus for the draftsman, which can h = be made at hcme it_and the blade. The blade is fastened to the head by screws, but is further forced against the square edge of the mortise by the wedge. By beveling the broad end of the latter at its under side and rounding the outside corner, the wedge is kept off the drawing-table. In making the square, the mortise should be routered out before the curve of the head is shaped. Care must be taken to keep both edges of the mortise exactly straight. The head is then shaped, the blade set in without putting in the screws, and the square tried out on the drawing-table. The head is trued up with a jointer. This type of square has the ad- vantage that the blade, while easily removable, is held to true with an unusual degree of accuracy and rigid- ity. A blade that has become injured or warped can be taken out, and when replaced will automatically come to true. The blades seldom work loose on the head, but should this hap- pen a couple of taps against the end of the wedge sets it up absolutely tight.—HENRY SIMON. How to Prevent Sparrows Roosting on Blinds SIMPLE means of preventing that city pest, the sparrow, from : sitting upon blinds and twittering out- side of your window all day long is to drive a wire nail about 1/16 in. - jn diameter ‘into the blind 1 in. directly over the catch where the spar-

Drive a nail overthe TOW roosts. catch in your blind This makes the and make Mr. Spar- sitting place row roost elsewhere too small for the bird without in any way interfer- ing with the opening and closing of the blind.—C. H. SMART.

sia : — -

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Note how GENCO Razors meet the strop in just the proper way to assure a perfect shaving edge. The bevel lends backbone to the edge and guides it on the strop. Reg. U.S. Pat. Off, ‘Hows the razor this morning?” asks your barber He wouldn’t ask you, if his razor pulled or scraped. It doesn’t, be- cause he’s using a regular razor— of the GENCO type—and he stropped it before he began to shave, just as you could strop one to shave your- self. It travels over your face so smoothly because it has been stropped. Any barber will tell you that a perfect shaving edge can be had only on a regular razor and by stropping. That’s why barbers all use regular razors. Anybody Can Strop a Genco Razor It’s easy, because every GENCO Razor is especially designed to strop. Its back is broad; its blade is hollow ground—ground with a slight but vitally necessary bevel right behind the edge. These three features compel every GENCO to meet the strop at the right angle. A few light strokes and there you have a regular professional shaving edge. Go to your dealer and ask to see a GENCO. Look ‘for the features mentioned. Notice the beautiful steel in it—hand-ground, perfectly tempered, good for a_ lifetime. You'll be surprised at the reasona- ble price charged for such a good razor. That same keen, business- like blade every morning will save you a lot of time and money. You'll buy one, because it looks right, feels right, and perhaps be- cause of our sweeping guarantee— “GENCO Razors must make good or we will.” And, after shaving with it, you’ll boast of it as a find. If your dealer hasn’t GENCO Razors, write to us for one Geneva Cutlery Corporation 47 Gates Avenue, Geneva, N. Y. Largest Manufacturers of High-grade Razors in the World = FY dk Reg. U. S. Pat. Off.

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The Human Side of Service More than a year has passed since. the signing of the Armistice, yet all tue world still feels the effects of the War. TheTelephone Company is no exception. More than 20,000 Bell telephone employees went to war; some of them never returned. For eighteen months we were shut off from practically all supplies. War's demands took our em- ployees and our materials, at the same time requiring increased service. Some districts suffered. In many places the old, high standard of service has been restored. In every place efforts at restora- tion are unremitting. The loyalty of employees who have staid at their tasks and the fine spirit of new em- ployees deserve public appreciation. They have worked at a disad- | vantage but they have never faltered, for they know their importance to both the commercial and social life © of the country. These two hundred thousand ~ workers are just as human as the rest of us. They respond to kindly, considerate treatment and are worthy of adequate remuneration. And the reward should always be in keep- ing with the service desired. AMERICAN TELEPHONE AND TELEGRAPH COMPANY AND ASSOCIATED COMPANIES One System Universal Service Send for this Free 118 Page Book. It tells how you can gain a thor- ough knowledge of law in your spare time. as 40,000 others are doing. Splendid op- Dortunities in the profession of law. Busi- pm, ness today needs law trained men. Free re book gives experiences of cuc:essful law trained men, and tell2 how you can read flaw under guidance of Ex- President Taft and 80 other eminent authorities. Biackstone Institute Dept.124' 608 S. Dearborn Street, Chicago a sep ] Stop! : shears Ai prea ees eke eae pig at fcr ea CO. DE S257 TOLEDO, OHIO. 100 Popular Science Monthly A Milk-Can Vacuum Cleaner O household need be without a vacuum sweeper if there is a handy man about the house. The sweeper herein described is not so A milk-can, two funnels, a homemade fan, and an electric motor are all that is required to build this vacuum cleaner efficient or so attractive as the com- mercial type, but, for its cost and simplicity, it is very good. Made from scrap parts mostly, it costs less than a dollar without the motor. The main parts of the sweeper con- sist of an old milk-can, two funnels, a homemade fan, and a quarter- horsepower electric motor, of either alternating or direct current. An especially built mouth-piece is made from sheet-iron, and if the garden hose is in good condition it may be used for the dust line. An old milk-can of five-gallon ca- POSITION OF STRAP |RON EDGE -WISE RIVETS . Fig. 1 shows the door in the side of the can. Fig. 2, the fan cut from a piece of tin. Fig.3, how the air blast meets the smaller funnel pacity was procured, and its bottom removed, also the rim about the mouth. Then a square hole was cut in one side with a hacksaw, and a piece of sheet metal bent to fit snugly over the hole and hinged to form a door. The inside edges were covered

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For the out-of-doors days KODAK And not merely the alluring picture story, but on every negative at least a date; and a title, too, if you like. Titling is the work of but an instant with an Autographic Kodak; is as simple as making the picture itself—and there is no extra charge for Autographic film. Tf it isn’t an Eastman, tt isn’t a Kodak. EASTMAN KODAK CO., Rochester, N. Y., The Kodak City Catalogue free at your Dealer's or by mail.

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Youll Nev ver + Ievow en You Need a Daylo This letter, recently received from a young man in Montreal, proves the above statement:. “I bought a Daylo on November. 3rd... On the 4th Ha asa a, fire in our block. Hearing that the owner’s children were inside, I went up alad- der at the back of the house. I went in through a window. The fireman had no lights. With my Daylo, I could just see a bed through the dense smoke and underneath-it.a child, unconscious. I - picked the child up and handed it out the window 40 a fireman....... * ""“ (Signed) Robert Maw, Jr. | y Uses or Daylo * The Home ? ERE’S one use for Daylo that’s worth ten thousand times the cost of the light. The one chance in a million that Robert Maw, unior’s, experience may happen to you is too big a chance to overlook in protecting your dear ones. Night or day—there are hundreds of places in the home and hundreds of times when you need a Daylo to penetrate darkness with its brilliant beam of long-lived light. Buy a Daylo now, before you forget it. And have a regular place to keep it—on the kitchen shelf, under your pillow, near the front door, at the head of the cellar stairs—wherever you need it most. All leading electrical, hardware, drug, sporting goods, and auto accessory stores have a supply of Daylo. And they carry the genuine Eveready Tungsten Batteries for all “flashlights.”

Coming: $10,000 Cash Prize Contest. Ask your dealer, AMERICAN EVER READY WORKS of National Carbon Company, Inc. LONG ISLAND CITY, NEW YORK NATIONAL CARBON CO., Inc., San Francisco, Cal. CANADIAN NATIONAL CARBON COMPANY, Limited Toronto, Ont.

4702 SS 2659 Makers of the famous EVEREADY STORAGE BATTERY Guaranteed 11% Years

“Good Electrical Repair Double Service® Men Are Scarce”’ From One Socket , As Motor Age says, 75% of all auto repairs are electrical, and there are not enough trained men sleie light ocket ed é todo the work. The addition of electric starting The and lighting to all cars has vastly increased this|} | | go demand. The small town repair or battery shop must know how to make electrical repairs or lose trade to the city. Learn Automotive Electricity And make good wages or have a shop of your own. We teach all the theory and ractice of Starting, lighting, gnttion and batteries—as well as farm lighting—in an 8 weeks’ course of individual instruction. | Electr Se a Instructors are specialists in | dealers must give the their iine and their work is per- | subject of electrical sonal and therough. Tee ee ae Classes, limited to 20 students | {non the wround floor each, start every two weeks. are the ones aed will Write now for classes open and cepeir inant en Sean Getaile of course. anne fille but the right kind of equipment and one or B GINEERING two trained mechanics AM U INSTITUTE r and efficient lect teal 602-1601 $. Michigan Ave., CHICAGO service. It is well to

a in * ‘Motor Increasing Demand for

Dollars in Hares We pay $7.00 to $12.50 a pair a express charges. Big P Prokes W. furnish guaranteed high ae stock and buy all you raise. Use . backyard, barn, cellar, attic. Cone tractand Illustrated Catalog Free. STANDARD FOOD AND oe og 307C Broadway give a ,dealer a ne Founded by Amer. Bureau of Eng. trical TE, can te abovt 75%, of aut: Makers yreutte lice bervice work.

Popular Science Monthly with strips of felt to make it practically airtight. It was fastened by means of a catch, as shown in Fig. 1. Over the mouth, where the rim had formerly been, a large heavy funnel was soldered. Fig. 2 shows the construction of the fan. This should be about 16 in. in diameter, or at least 2 in. less in diameter than the diameter of the can, HOOKS FOR MOTOR DUST BAG

_SET-SC REW

FUNNEL CASTERS OR SKATE WHEELS

Fig. 4 shows the method of: mounting the fan and motor at the bottom of the can, the wires being carried outside END VIEW OF BASE and should have eight blades. Before finishing, the hole for the shaft of the motor is made. Secure a bushing of the right size to fit the shaft and solder it in place. Then provide the bushing with a set-screw. See that the blades of the fan are true and all alike, and also that the fan balances perfectly when placed upon the shaft. Smooth down the edges and give each blade a sharp pitch—about one third greater than that of the average electric fan. It might be well now to test out the motor before going any further, in order to decide what pitch works the best. Makesurethat all experiments aresatis- factory before you close up the cleaner; otherwise trouble will develop later on. The smaller funnel is placed inside the housing to deflect the dust and trash from the motor. Since the current of air is constant, once past the motor, it will do no harm. This smaller funnel has the end plugged with solder, and is held in the center of the can by light-weight strap-iron supports, bent so that they meet the blast edgewise, as shown in Fig. 3 (shown on page 100). It will be well to use a motor of the enclosed type. The method of mounting the motor and fan in the bottom of the can is shown in Fig. 4. They are mounted behind, and on a center line with, the inside funnel. Raise the motor on suitable wooden blocks and secure with strap-iron over each end, sol- dered to the inside of the can. This will hold the blocks and prevent any chance of their working out by reason of the vibration. Solder a few hooks to the outside of the can to hold a sack for catch- ing the dirt. If it is desired to make the plant portable, fasten on the wheels

of an old roller-skate.

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Ride a Bicycle to Work AVE money! Avoid the miserable jam of crowded street cars! Get to work on time — every time and feeling fine. Ride a bicycle. The bicycle is the most economical form of transporta- tion. It pays for itself in carfare saved. It is convenient —always ready to go—costs practically nothing to oper- ate—is easy to handle and a pleasure to ride. Thousands of people have realized the worth of riding a bicycle to work and business. Practically every man and woman in this county will benefit by this money-saving, health-gaining habit. See your dealer today. Po.W iH CYCLE TRADES 35 Warren Street OF AMERICA, INC. New York, U.S. A.

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HIGH SCHOOL COURSE IN TWO YEARS YOu ARE BADLY 4 ze | lac 10. HANDICAPPED 9 4 oe “vf You cannot attain business or social prominence. You are barred from a successful business career, from the leading professions, from well- paid civil service jobs, from teaching and college entrance. In fact, em- - ployers of practically all worth-while positions demand High School train- ing. You can’t hope to succeed in the face of this handicap. But you can remove it. Let the American School help you. BIG FUTURE 7's Course: which has been ae by some of America’s leading pro- essors, broaden your mind, and make you keen, alert and capable. It is compli, simplified and up-to-date. It covers jects given in a resident school and meets all vequirements of a High School training. From the first lesson to. the last you are carefully examined and coached. USE SPARE TIME ONLY Most people idle away fifty hours a week. Probably you do, Use only one-fifth of-your wasted hours for study and you can remove your present handicap within two pews, You will ouey the lessons and the knowledge age 1 gain will well repay the time spent in study. YOU RUN KO So that you may see for yourself how thorough and complete our Caining. be, we invite you to take ten lessons in the Hig hool Course—or any course of rahe be training in the coupon below—before decid- ing whether you wish to continue. Hf you are not then satisfied, we will refund your money in full. We. absolutely guarantee satisfaction. On that basis you owe it to yourself to make the test. Check and mail the coupon NOW for full Particulars and Free Bulletin. AMERICAN SCHOOL OF CORRESPONDENCE Dept. H-754 Chicago, Illinois TRAINING-THE KEY TO SUCCESS Explain how 1 can qualify for the position checked. ..-High-School Graduate . Electrical Engineer . Elec. Light & Power Supt. ... Hydroelectric Engineer ...Telephone Engineer ... Telegraph Engineer ... Wireless Operator . Architect . Lawyer ..-Business Manager ...Certified Pub. Accountant ... Accountant and Auditor ... Bookkeeper . .Stenographer ..Fire Insurance Expert > . Sanitary Engineer ... Building Contractor ...Master Flumber . Civil Engineer ..Heating & Vent. Engineer ...Structural Engineer ..-Mechanical Engineer ...Shop Superintendent . Steam Engineer ..Draftsman and Designer ; ..-Photoplay Writer .. Employment Manager ..Automobile Engineer ...Automobile Repairman ..Airplane Mechanic ..General Cducation Course . Common ..Foreman’s Training Course School Branches An Ingenious Method of Bending Bus-bars COMPARATIVELY easy and simple method of bending bus- bars is here given. Copper bars of considerable length are quite difficult . to handle and to bend, with any degree of .accu- PINCH BAR. racy, without COPPER special ap- BUS-BAR ) paratus. Procure a : piece of heavy CLAMPS “TIMBER. timber, and at Clamp the bus-bar oneendarrange to the timber, a clamp con- attach the handle, Pe d bend d sisting of a flat is — piece of iron and a couple of bolts pass- ing through the iron and the timber. Clamp the bus-bar securely under this at the point where the bend is desired, and clamp a pinch-bar to it as shown in the accompanying sketch. In this manner the bus-bar can be bent to any angle desired. To put a quarter twist in a bar, clamp the pinch-bar to it at right angles to the length of the bus-bar, and give the latter a twist. Tobenda bar on edge, heat it at the point where it is to be bent, and then bend it. If the bar is bent on edge when cold, it is difficult to make it stay flat at the bend. How to Distinguish Auto- mobile Engine Knocks OCATING knocks in the automo- bile engine is difficult work even for an expert me- TeLepHone Chanic. In “receiver twenty minutes you can make a detector com- parable to a costly stetho- scope. Take a hard- wood stick 18 in. long by }% in. square, and, to one end of it at- tach an old tele- phone receiver. This may be purchased very cheaply from your local telephone company. By placing the stick end of the detector on various parts of tke engine while it is running, with your ear ct the receiver end, even the most intricate knocks manifest them- selves in a way that is easily distin- guishable. When using the detector on the transmission, jack up both rear wheels from the ground, throw the shift lever into. high speed, and pull up the emergency brake so’ that they will drag in the manner produced in driv- ing. Then you can hear any foreign knocks distinctly.—R. L. PRINDLE. 104 HARD wOoD 4— STICK x SQUARE 18" For a few cents you can make an engine knock detector that is really efficient Popular Science Monthly Statement of the Ownership, Management, Circulation, etc., required by the Act of wo ess Of August 24, 1912, of Popular Science Monthly, lished monthly at New York, N. Y., October 1, 1919. State of New York, County of New York, ss. Before me, a notary public, in and for the State and county aforesaid, personally appeared O..B. Capen, who, having been duly sworn according to law, deposes and says that he is the Business Manager of the Popular Science Monthly and that the following is, to the best of his knowledge and belief, a true statement of the ownership. management, etc., of the aforesaid publica- tion for the date shown in the above caption, required by the Act of August 24, 1912, embodied in section 443, 1 Laws and Regulations, printed on the reverse of this form, to wit: 1. That the names and addresses of the publisher, editor. managing editor and business managers are: Pub- lisher, The Modern Publishing Company, Inc., 225 West Thirty-ninth Street, New York, N. Editor, Waldemar Kaempffert, 225 West Thirty-ninth Street, New York, N. Y. Managing Editor, Loren Palmer, 225’ West Thirty- ninth Street, New York, N. Y. Business Manager, - B. Capen, 225 "West Thirty-ninth Street, New York. 7. 2.—That the owners are: The Popular Science Publishing Bons any, Inc., 225 West Thirty-ninth Street, New York, N. Y. Stockholders 3 Popular Science Publishing Com- pany, Inc., Henry J. Fisher, 22 William Street, New York, . ¥.; Oliver B. Capen, 225 West Thirty-ninth Street, New York, N. Y.; Robert Cade Wilson, 683 Springfield Avenue, Summit Ke aldemar Kaempftert, 225 West Thirtyeuinth § Street, New York, N. Y.; George B. Agnew, 22 William Street, New York, N. Y.; Susan D. Bliss, 22 William Street, New York, N.Y. 3.—That the known bondholders, mortgagees, and ‘other security holders owning = holding 1 per cent or more of total amount of bonds, mortgages, or other securities are: Importers and Traders National Bank, 247 Broadway, New York, N. Y.; H. J. Fisher, 22 William Street, New York, : Geo. H. Mead Company, Dayton, Ohio. 4 —That the two para- es next above, giving the names of the owners, stock- olders, and security holders, if any, contain not only the list of stockholders and security holders as they appear upon the books of the company, but also, in cases where the stockholder Or security holder appears upon the bocks of the company as trustee or in any other fiduciary relation the name of the person or corporation for whom such trustee is acting, is given; also that the said two paragraphs contain statements embracing afflant’s full knowledge ind belief as to the circumstances and conditions under which stockholders and security holders who do not appear upon the books of the company as trustees, hold stock and securities in a capacity other than that of & bona fide owner; = this afflant has no reason to believe that any other rson, association, or corporation has any interest direct er indirect in — stock, bonds, or other securities than as so stated by (Signed) O. B. CAPEN, Business Manager. Sworn to and subscribed Loe me this 17th day of September, 1919. Arthur A. Blauvelt, Queen’s Conmty—8767, New York County—639, New York Reg. 1612. (Seal) My commission expires March, 30. 1921. DO YOU LIKE TO DRAW Cartoonists Are Well Paid We will not give you any grand prize if you answer this ad. Nor wil we claim to make you rich in a week. But if you are anxious to develop your talent with a successful car- tvonist, so you can make money, send a copy of this picture with 6c in stamps for portfolio of cartoons and sample lesson plate, and let us explain, THE W. L. EVANS School of Cartooning 825 Leader Bldg., Cleveland, O. n indoor eis eCab Conveni ient — Sanitary rovides prac- ant mea rai bs tical, sensible and canitar ary i accommodations indoors protec from cold, stormy weather. Makes Homes Modern Easily installed- fade of hist igh grade material, beavily enameled--- eo Absolutely ¢ Odorless Scientifically d dissolve contents- = -kill germs. Pam by U. 8. Health Bureau and Boards of Héalth. 30 DAYS FREE TRIAL. Seer Aaonte Wee lendid opportunity. Exclusive nel Write ry a an Comfort Chemical Closet Co., 11% Factories Bldg., Toledo, 0. DIAMONDS For a Few Cents a Day Diamond bargains—128 ofthem. ‘The eqeatest Biwearestis ifourpame anda * Yar choles of promt ge itr pee *dper cont peaniy increase as may Write Today $ sue ae cae Learn to Dance! You can learn Fox-Trot,

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April, 1920 % ZOU'LL find\out what roomy oversize, quality materials, and extra-wear features really mean just as soon as you get into Blue Buckle OverAlls and Coats. The cut of every piece of wear-quality denim, the placing of every stitch and riveted button is planned so that you get the utmost in service and comfort out of every Blue Buckle garment. Hundreds of skilled Union work- ers, the largest overall factory in the world, rigid inspection of raw materials and finished garments are some of the reasons for unex- celled Blue Buckle quality—the greatest overall value ever put on the market. Jobbers OverAll Company, Inc. Lynchburg, Va. Largest manufacturers of overalls in the world TRACE MARK UNION MACE O06. U S.Per.Qre “Strong for Work” Blue Buckle © verAlls

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The difference between a hole |j in the wall and a real door— A door that doesn’t always close and stay closed is no better than a hole in the wall. A door that has a Yale Door Closer is a real door. It closes every time—dquietly, softly, automatically. If you are tired of doors that slam and bang and shatter—if you are weary of doors that stand open— You will install Yale Door Closers—and insure comfort and better health; save coal keep out cold and draughts—and preserve the door. Give your door a Yale Door Cioser and it will close as “Soft as Cotton” See. the trademark ‘‘Yale’’ on Door Closers, Yale Cylinder Night Latches, Padlocks, Builders’ Locks and Hardware, Bank Locks, Chain Blocks and Electric Hoists. The Yale & Towne Mfg. Co. Makers of the Yale Locks Stamford, Conn. Chicago Office: 22 East Lake Street Canadian Yale & Towne Ltd: St. Catharines, Ontario al A Bill-fold Worth Owning The “American Gentleman” bill-fold will keep your pocketstidy. And itis so neat, so compact, so good-looking that you will be proud to have one always with you. Study the picture. Note the combination of twelve. useful features. Features you need daily. The “American Gentleman” is made of genuine leather. Stitched throughout—no edges pasted. Tan or black. Only $1.00 at any dealer's. Or send $1.00, with your dealer's name, direct to us and we will mail you one postpaid. CHARLES K. COOK CO., Inc. Camden, N. J. Dealers—write for profitable dealer proposition. Makers of Collar Bags, Brief Cases, Tobacco Pouches, etc. Things | Made that Reduced the High Cost of Living The Popular Science Monthly will pay fifty dollars for the best answer HAT new use of a mechanical appliance or machine did you make for the purpose of -reducing the high cost of living? We know of one fellow. that transformed his coal furnace into an oil burner. less refrigerator. Another made an ice- There are, of course, many other things and we want to know in how many practical ways we can reduce living expenses. Tell us! Tue PorpuLarR SCIENCE Montuty offers three prizes,—a first prize of $50, a second prize of $25, and a third prize of $15,—to be awarded in accordance with the rules set forth below: Rules Governing the Contest (1) Contestants are not limited to the number of methods of re- ducing the high cost of living, but only one method can possibly win the first prize, only one the second, and only one the third. The contest is open to everybody. (2) The method must be clear- ly shown either in a photograph orinadrawing. If a drawing is sent in, it need not be made by a skilled draftsman. It is sufficient that it should be _ intelligible. While pencil sketches will be con- sidered, contestants are request- ed to make their drawings in ink on heavy white paper. The views should be sufficient in number to set forth the use of the appliance very clearly. The contestant’s name and address should appear on each sheet of drawings. (3) The drawings or photo- _graphs must be accompanied by a description, preferably type- written, in which the method is clearly given. It must be written on one side of the paper only, and it should not be more than 500 words in length. The name and address of the contestant should appear: in the upper left-hand corner of the first sheet of the written description. (4) The drawings and descrip- tion entered by contestants must be received by the POPULAR ' ScreNcE MONTHLY not later than 5 p.m. on Friday, April 30, 1920. (5) The judges of the contest will be the editors of the PoPULAR ScIENCE MONTHLY. 106 (6) The first prize of $50 will be awarded to the contestant who, in the opinion of the judges, has suggested the simplest and best method of reducing the high cost of living. The second prize of $25 will be paid to the contestant who sub- mits a method next in merit. The third prize of $15 will be paid to the contestant who sub- mits the method third in merit. (7) The winners of the contest will be announced in the earliest possible issue of the POPULAR ScIENCE MonTnsLy. A descrip- tion of the methods which win the three prizes offered will duly ap- pear in the pages of the POPULAR SCIENCE MONTRLY, together with the names of the winners. (8) The editors of the PoPULAR ScrENCE. MONTHLY shall have the right to publish meritorious manuscripts which do not win a prize. The regular space rates will be paid to the contestants who submit the manuscripts thus selected. (9) When a contestant submits more than one method, the de- scription and drawing by which each is set forth must be sent as _ a separate unit. (10) Manuscripts or drawings will be returned to contestants if stamps are enclosed. (11) Send drawings and specifi- cations to the High Cost of Living Editor, PorpuLakR SCIENCE MONTHLY, 225 West 39th Street, New York City. Popular Science Monthly

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April, 1920 Technical knowledge is not needed to appreciate the Cradle Spring Frame. Observe that the forward end of the horizontal furk is pivoted to the main frame, permitting the fork and wheel to move up and down in the arc, Thus, every jolt is ab- sorbed directly by the resilient steel springs. The INDIAN leads in exclusive comfort features Perfect riding comfort, regardless of the roads traveled, is a bred-in- the-bone characteristic of the Indian Powerplus with theCradle Spring Frame. Ride at a walking pace or “go it” at a sixty mile clip and the resultis the same: You get all the enjoyment the route offers. The Cradle Spring Frame is per- fect from the mechanical stand- point. It is unique in the motor- cycle field as a protector for both riderand machine. And it is thor- oughly and exclusively Indian. No matter how abrupt or how numerous the road jolts may be, the Cradle Spring Frame converts every shock irito a buoy- ant gliding impulse that exhilarates. HZNDEE MANUFACTURING COMPANY Dept. 38, Springfield, Massachusetts The Largest Motorcycle Manufacturer in the World

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A point for every writer

Fine, Medium, Stub and Ball Pointed PENCERIAN PERSONAL Steel Pens It’s the special Spencerian steel and thefinely worked, hand-made pointsthat make Spencerian Pens last so long and write so smoothly. Send 10¢ for 10 samples, different patterns. Then pick a style that fits your hand. Use that style always. We will also include that fascinating book, “What Your Hand- writing Reveals”. SPENCERIAN PEN CO. 349 Broadway New York City

QUICKLY <r apie LANGUAGES : pees an correut + area one roe uncia' inowit. i Fasaliyand friends oni = 4 LANGUAGE PHONE E'METHOD. and Rosenthal’s Practical Li THE LANGUAGE —s METHOD Putnam Bidg. 2W. 45th St., N.Y. FREE CATALOG Sve WAME OF SCHOOL OR

LUB AND HUMBER tm CLASS, |

BASTIAN BROS. CO.. 169 Bastian Blda., Roohester, NY TAMMER <—s A scientific method that “‘kills the fear” of stammering. Re-education the key. This marvelous method fully outlined in an accurate, dependable, worth while book—“HOW TO STOP STAMMERING” Mailed on receipt of 10 cents. 109 N. Dearborn, CHICAGO

The HATFIELD INST:

Inside Hinges that Make the Tool-Box Secure ANY people have homemade tool-boxes with the hinges for the cover get upon the top of the box. This feature en- courages the thief, for by simply remov- ing the hinges hehas complete access to the contents. Why not set the hinges on the inside and in- sure your tools by making the box as nearly thief-proof as possible? Buy the ordinary long hinges and bend them in the manner shown at the top of the illustration. This enables the bent part of the hinges to fit snugly against the inside of the cover. Use short, heavy screws, setting them tightly into the wood. If preferred, the wood may be cut away so that the hinge centers will not show above the top of the cover.

Inside hinges give the would-be thief a prob- lem in trying to open your tool - box A Little Light on the Incubator Question VERY poultryman, whether ama- teur or professional, knows how dark it is inside his incubator and how

Don’t fumble around in the dark interior of an incubator with matches; attach a battery and light difficult it sometimes is to read the instruments. Why not rig up an ordinary dry battery, push-button, and 1.5-volt lamp, as shown in the illustration, and brighten things up inside? The battery may be fastened either to the bottom or the side of the in- cubator, and the push-button to the front of the incubator. The miniature lamp and receptacle are placed in the most convenient posi- tion inside.—F. C. VESEY. 108 ” qoulse Bowles,

Popular Science Monthh

oe: ‘dt aa 1001 400% EAR iMONTH YE con eee t ‘fatarein the s Acta and and fend Pract Yi an or ate ations ong re a. tt od kan RULOS. ORG. TORS TRUCKS AND GAS ENGINES sta tuition easily w ys reach. Write for facts today. Endorsed by Auto Factories, Graduates fama Seereute

Write for full particulars right ht away 60 yon ay ty 4 —— 4 ag hme d = winter in the city or be ready for a sprin on f Hundreds of other em are aking

FREE §; 2A = Kit of 29 ‘tools worth $17.50 is ven to everyone who enrolls now. fey are yours to take home with you You Mas-

MILWAUKEE MOTOR. SCHOOL Oent 794 555 Downer Ave., Milwaukee, Wis,

med by Note

Music no longer difficult! New plan makes it easy to learn by home study. Posi- tively easier than with pri- vate teacher. Faster pro- gress. You will be able to play your favorite instru- ment in a few short months! More than 200,- 000 men, women and chil- : ‘dren have learned by our method. You, too, can learn in your spare time, We guarantee it. Lessons FREE - to have one ‘ed in each Ieee at once to new vertion ome study meth Fora » Flute, Clarinet, Pic- colo. Saxo- phone, Uku- lele, Sight Singing, Ha- waiian Steel guitar, Har- mony and Composition, Tenor, Banjo, Viola, H.S, Whi tt- mack, N ew York, writes:‘*I compliment you

hortti ref Koworth, Yay fasts ee ieehseeece ceived my music which ia sm soere eet w= } cer- tificate. I high. §. ao fe. ay fis Maleony Ga Se your solar =. le particulars. orek a wouldn’t take ~ postal today! completed U.S. SCHOOL OF music e Gruaswick Bldg. New York City students. 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, Ill.

Small Steam Engines and Boilers Gas and Gasoline Engines, +H. P. up; Tanks Sy ’ Gears Model Makers’ Supplies GetOur Catalogue sent postpaid for 15c me preferred) or stamps. % Refunded first order. 192 Pages— Over 200 Illustrations. MODERN ENGINE & SUPPLY CO. $44 Monadnock Block, CHICAGO

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April, 1920 HISTORY ART DAIRYING SCIENCE \ MANUFACTURING. ASTRONOMY. MUSIC REL'GION EXPLORATION AND ADVENTURE POLITICS AGRICULTURE ENGINEERING gorany LAW STOCK RAISING } AND GAMES oe, RK % dui & UTANNO BIOGRAPHY NESS THE ENCYCLOPAEDIA BRITANNICA Furnishes Accurate Knowledge GEOGRAPHY SPORTS AVIATION ARCHITECTURE WAR INFORMATION DRAMA SSSss TEXTILES et tre ~ LITERATURE BEAUTIF YING THE HOME PHILOSOPHY MEDICINE ‘TRAVEL On Every Subject Under the Sun The World’s Greatest Authority. THE ENCYCLOPAEDIA BRITANNICA contains robably the best and most reliable information written y the greatest experts on practically every subject known to the human mind. No matter what subject you are interested in, no mat- ter what subject your family or your children are interested in, no matter what subject comes up in your daily papers or your books, you will find that the Britannica_gives the most comprehensive information in its 44,000,000 words. Every phase of a subject is cov- ered. Even the smallest, most obscure information is in the Britan- nica, as well as the articles on the great general subjects. When you read an article in the ages ae Britannica you feel confident that the information is reliable, for the Britannica is written by the wisest minds—each a specialist in the particular subject upon which he has furnished an article for the Britannica. These writers are either professors in the great institutions of learn- ing in our country and other countries, or are scientific men and women who, by their superior intelligence and research, have acquired far advanced knowledge of their subjects, or, again, they are the great workers of the world. They write in a clear, concise manner which every member of your family can understand. You will be surprised how interesting and fascinating are the articles in the Britannica, and you will have many hours of profit and pleasure from a set of this great work. Your Country Needs Your Help in the Solution of Her Post-War Problems. Shall we retain our high tariff or shall wé operate on a free trade basis? Shall we wipe out our enormous national debt in one or two ere or shall we extend it over a comparatively long period? hall we adopt universal training or maintain a large standin army? Shall this nation become more autocratic or tend towar }sngenenme —— will mean the greatest prosperity and happiness to e people You, as a citizen of this great nation, in the day of the greatest crisis of its history, should put yourself in a position adequately to answer and pass intelligent judgment on the —— that are so vital to the country and the happiness and welfare of its people. Give Your Child a Fair Chance. Who are the men and women in each generation who have stood head and shoulders above their fellow men and who have won the most notable success? They are the men and women who, as children, have educated themselves beyond the station to which they were born. Abraham Lincoln was the best educated lawyer in his town, and he continued throughout his life probably the best posted man of his day, because he réad and read. You insist that your child has brains, but you should help that child develop his brains, and give him every advan- tage possible within your means, so that when he becomes ready to do his work in the world he is not handicapped by lack of education. Education is the path that leads to achievement, to a larger life and to greater success, Put in your child’s hands the Encyclopaedia Britannica, the world’s storehouse of knowledge, which has been the guide to the education of millions of men and women. It will inspire your child to learn, and it will furnish him with a great teacher on many thousands of subjects. We Are Offering the Britannica at a Great Bargain $ Illustrations. As First Payment brings you this Complete Set of 29 Volumes, Containing 44,000,000 Words, 30,000 Pages, 15,000 Maps and The Balance Is in Small Monthly Payments. Remember, this is an unusual offer of the Britannica Act today—NOW—by printed on genuine India paper. Sign and Send This Coupon Today. Sears, Roebuck and Co., Chicago, Ill, clipping the coupon and sending for the beautifully illus- } ,; trated book telling all about the Britannica. Kiso tell me what 1 will have to India paper. Sears, Roebuck and Co., Chicago, Ill. R. F. D. Box Street Gentlemen: Please send me, free, your Illustrated Book No. ving full information about the new Encyclopaedia Britannica. ! ay for one of the remaining sets of the Handy Volume issue of the Britannica printed on genuine 19C, Name SPHSSSSHSSSHT SEES HSSEHHESSHE SESE SHEETS SE SHER EEE EHH EES Postoffice de en ee Pein cu twee cette bs sc ctv deeebcs sa édes aeednaebek acs and Pelcantuncce cuh > sedtbehaseees 65i ies suas:

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LANDON STUDENTS WITH ONE NEWSPAPER ORGANIZATION

Popular Science Monthly Why That Sewing-Machine Motor Slips NE of the troubles that sometimes mar the operation of a sewing- machine motor which drives through a friction pulley is the slipping of the pulley. Usually an ef- fort is made to = stop the slip- S998, page by tight- | ening the ten- sion of the spring. Asa rule, however,

SEWING -

Get the most out of your sewing- machine motor by overhauling it it will be found that the trouble is due to a very thin learn if you follow these charts, bilities for you. Please state your age.

Landon Picture Charts explain the unusual success of the Landon School in developing successful artists, These charts are covered with hundreds of sketches showing you just how to proceed, step by step, in draw- ing original heads, hands, figures, animals and all de- tails of finished cartoon work, You are bound to The above photograph shows six Landon students all in the Art Department of the N. E. A. Syndicate. Blosser (first at left) . created ‘“‘Freckles and His Friends.”” R. Grove draws ‘‘The Boys CS E, LG in the Other Car.’’ Parks created ‘‘O U Busher.”’ Deitesfeld, TD, Kroesen and Mattingly have all arrived Their signatures, re- produced here, will be recognized by millions of newspaper readers. Their success is typical of hundreds of other Landon students. Now is the time to think seriously about learning todraw. Never was there a greater demand for this work. Prepareto earn from $30 to $125 or more per week. Take the first step now—write to- day for full information, send. 6c in stamps for sample picture chart, long list of successful students’and booklet showing possi- The Landon School 1151 Schofeld Bids. Blosser Grove Deitesfeld Parks Kroesen ~~ Landon Picture Charts Dear OND atc of - e Make Drawing Easy to Learn utaste oh in Gee ork Gameteiek at the Newspaper Enterprise Associa- tion. Another one is coming with us aoe Monday. t is the sure fire results your School gets which marks it as practi- cal, thorough and different. Very sincerely, C Fe sttrxe_<D SiC. Frove — La iees=n— ae b

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‘ Learn Watch h Repairing

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once in a_ while film of grease or oil lodging on the balance wheel of the machine and the face of the pulley. Usually this results from contact of the operator’s hand with the wheel of the machine. Clean the wheel and the pulley face thoroughly with a little gasoline, or even with a dry cloth, which will take a little more rubbing. In nine cases out of ten this will stop the slipping. ‘Too much oil on the motor bearings will result in an oily film, and this causes the slipping. A spring that has become too tight will cause undue wear of the bearings. Clean the commutator occasionally with a bit of dry, lintless cloth on the end of a small stick while the motor is running, being careful not to let the cloth get caught. Do not sandpaper the commutator or scrape it, and under no circumstances put oil on it.—HOWARD GREENE. To Get the Most from Your Ice-Cream Freezer NE of the household appliances that needs oil and seldom gets it is the ice-cream freezer; yet the judicious application of a lubricant ma- terially lessens the labor of

| cal cranking. a pin Use the _ heaviest _ oil You wonder why the available or, ice-cream freezer works hard. Oil it better yet, and note the difference S8Tease. This will prevent the lubricant from running out. Vaseline may be used. Lubricate the shaft bearings, the wooden handle, the sockets and bearings in which the gears turn, the teeth of the gears, and the socket at the bottom of the tub in which the container turns. The number of places where there is friction is a little surprising, and in the aggregate they can cause much extra work if run dry.—HOowarD GREENE.

a fF KF oe oe oe __s — ie oe 7a" DR wa. mes

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April, 1920 Wire Insulation Made from Tire Filler OMETIMES a wire insulation has become so worn that the copper is exposed. A break of this kind cannot easily be wrapped with tape. In such cases a small quantity of good tire filler worked into and around the chafed wire will make a fine substitute for insulation. Where double-contact lamps are used and the wires fit close together, as in the Ford type of headlight, the filler can be pressed around the wires and the cap screwed on. This also holds the wires firmly. Repairing a Magneto with Spark-Plug Porcelain O repair a magneto that has a faulty brush-holder or ‘brush nipple,” follow this simple and cheap method. The brush-holder is usually made of rubber or composite, and is bored out in its center, the hole containing a carbon brush and a spiral spring for = gm ~~ FILED OFF FLUSH 4 7 EA RMI: BRASS NUT WASHER f i= | | aan A L777 | iu | ir Vv ~ 3 CORD 4 PACKING How an old spark-plug porcelain can be inserted into a magneto to remedy short circuits from defective brush-holders tension. Frequently this holder may fracture and its threads wear, or per- haps the bearing becomes so loose that rain water leaks past into the junction of the brush and armature. This causes a short circuit, which results in a defective engine. An extremely efficient way to repair this defect is to remove the old composition holder and insert the porcelain of an old spark-plug with its lock-nut into the brush-holder. Ordi- nary cotton string may be used for packing, and the central electrode should be filed off to the proper distance from the magneto distributor, so that the spark is transmitted as before. The electrode must just barely clear the brass of the distributor, and the adjusting may be done by more or less packing in the lock-nut shown a A.—P. P. AVERY. Son, SS vA ae te 5 oo: eYaai thd t MINERAL ee NEW YORK, 9 E. Fortieth St, ATLANTA, 320 Hurt Bidg. TORONTO, 23 Sco : tt St. CINCINNATI, 410 Traction Bldg. DETROIT, 502 Lincoln Bidg. . > Biot BPN CHICAGO, 908 S. Michigan Ave. MINNEAPOLIS, 703 Plymouth Bldg. LOS ANGELES, 303 KANSAS CITY, 611 Grand Ave. Temple. PUEBLO, Thatcher Bl DENVER, 513 Mercantile Bidg. Bide. SPOKANE, 1015 Old Nat'l. Bldg. SALT LAKE CITY, 200 Walker Bldg. Indusvy and Home ATURE has revealed the means through which softening of wa- ter has been made practical for every use. Factories, shops and other industrial establishments now save literally millions of dollars that were wasted by use of hard water. And for the home—greater comfort and re- finement. Water as soft as falling rain yet free from the taint and odor and grime of roof and trees, water that is beneficial to skin and complexion, that leaves the hair fluffy and soft and comfortably clean—+this you can now have, flowing to every faucet, EFINIT RIVAL OF THE CLOUDS Nature’s Water Softener The Refinite Water Softener is a system perfected to utilize Nature’s own water soft- ening mineral, Refinite. It attaches to the supply pipe in the basement. Water needs only to pass through a bed of Refinite in this system to be freed of its troublesome lime and magnesia hardness. In laundries and the laundry department of hotels, hospitals and institutions, Refinite soft water cuts the washroom supplies expense more than half. ~ It fully doubles the life of linens; makes possible the laundering of woolens, silks and other delicate fabrics not commonly attempted. In textile mills it en- ables dyeing formulas to act dependably; improves the quality of the products. In steam power plants it prevents boiler scale, saving fuel, labor and equip- ment. The Refinite system occupies little space—Requites no expert supervision—Is easily installed--Very reasonable in price. . There’s one for. your use. Let us tell you about it— no obligation. Address our nearest office. THE REFINITE COMPANY Refinite Building OMAHA, NEB. Also Mfrs. of Refinite Rapid Pressure Filters SAN FRANCISCO, 419 Call Bldg. BUFFALO, 411 Libertas E lll

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Bathe in Comfort —— Anywhere e Robinson Folding Bath Tub makes home bathiingeasyandconven nient without the necessity of running water, expensive plumbingor sewercon- nections. Tub is made of special material (called steeline), soft ond pliable—instantly warmed. No cold clammy iron or porcelain to touch the body. Guaranteed non-leakable. Exceptionally well con- structed and reinforced. Cannot tip nor spill. En- tire weight of water and occupant rests on floor. Special device makes Tub self-emptying. When bath is finished, pull plug and the tub is empty, ready to be folded and put away by the time you are dressed, Agents Make $35 to $100 Weekly. Go into business—work for yourself—make big money whole year ‘round. Our Co-operative Sales Plan insures success, Wonderful opportunities sell- ing Robinson’s Bath Tubs. 70%, of homés need them. Customers highly pleased, well satisfied: You ean build a wonderful Lednaes selling this home ne- eessity. Our complete plan and practical sales aid assures big results. Hustlers coin money. so CAN you! ee eras y; Pasko of N. ¥ madc $76 in two hours: ro weeks; Ste; in ae, colin son Fo th Tubs, And Bo onan ents goon rede of them are doing nh a elinarakesvenmet iebtate usiness wf Tub Guaranteed 10 Years 4 el Tub folded Your Chance to Make Big Profits in Vulcanizing Here is gS chance to get into a highly profitable busi- ness which will make you in- dependent. High class vul- canizers are in demand every- where. Many of ourgraduates make $3,000 a year and over. We make the Anderson steam vulcanizer and Ander- son retreader and teach you the famous Anderson Method of Vulcanizing. Our students make good because ‘hey can do superior work with the Anderson machine and method and do it at one-tenth the cost required by all other vul- canizers. Highly sati fied customers and large profits means a paying business. Not only are we able to convince you of this but we invite you to compare the Anderson make and method with others. We have installed Anderson schools of vulcanizing in 30 states for teaching the Anderson method of vulcanizing. The course requires 5 to 10 days and costs $20. If you buy an Anderson vulcanizer we return your $20 and pay you $2 per day e: pense money while learning. ur reputation is valuable. We expect Anderson vul- canizers to do work which will outlast the rest of the tire. We expect Anderson students to succeed in a business way. Their success is our success. Therefore we do not sell an Anderson vulcanizer to anyone who has not receiv.d our course of tnsiructions. Don’t miss this opportunity. Write today for full par- ticulars and address of Anderson school nearest to you ANDERSON STEAM VULCANIZER co. 13 Williams Bidg., napolis, Ind., U. 8. A. Pring your name wo po mt takes Auto and Tractor Mechanic f captain il i RT HPIe rj 1. | Hilt ail j= SWEENEY SYSTEM eee . yes of cal training by which 8,000 “> F 60) ‘were trained for U.S..Gove @ oe oe and ay — a experience necessary, a elena: FREE showing for Bostested free catalog 2 Dow. Millie one of pictases men men ‘BOW LEGS and KNOCK. KNEES: UNSIGHTLY Ly SEND FOR BOOKLET SHOWING puotos | OF MEN WITH AND WITHOUT . The Perfect Leg Forms PERFECT SALES C0., 140 W. Mayfield Ave., Dept. 45, Chicago, Ill. Popular Science Monthly A Lathe and Grinding Cabinet to Save Space By H. H. T is often desired to use a small lathe in some locality where an overhead counter-shaft and motor drive would be in the way, unsightly, or impossible to instal. Or else a portable self-contained outfit is needed. © The diagrams herewith show the con- struction of a wooden cabinet con- taining the driving motor and neces- sary counter-shafts and belting of a two-speed drive for a small-speed lathe mounted on the cabinet, as well as a clutch drive for a grinding-stand mounted beside the lathe and driven from the motor direct. It is best to drive the grinder direct, for even a small stand requires con- siderable power, and a counter-shaft always causes considerableloss, especially with a speeded up drive, as in this case. If the lathe-head has a three-cone = pulley, six speeds Attheleftisshownthe are available; a front elevation of the reverse drive is cabinet, and at the ri right the side elevation seldom required for a speed lathe. A cone pulley might be used on the motor, and one counter-shaft and the tight and loose pulleys dispensed with; but the belt shippers are better, for the motor does not have to be started and stopped so often, which means less disturbance to the lighting circuit, and the speed may be changed from low to high merely by shifting the levers instead of changing belts. No dimensions are given, for the arrangement would have to be worked out slightly differently for various makes and combinations of motor, lathe, and grinder. A quarter-horse- power motor is about right to drive a 6- to 8-in. lathe, and a grinder-stand swinging wheels of 6 to 8 in. diameter, and the layout shown was pro- portioned to apparatus of these di- mensions. Cold rolled steel 34-in. shafting would be about right, with wooden or iron pulleys and 1l-in. or 1\%-in. flat leather belting. The boxes may be either plain cast-iron ‘‘dolly boxes,” or, if expense need not be considered, ball bearings may be installed. The large cone pulley is best, turned up out: of oak or other hard wood; the size of two of its steps depends upon the cone pulley on the lathe, and the reader is referred to any hand-book on machinery or mechanical engineering for the method to be used. In the case described the lathe ‘cone was assumed to have steps 1, 24, and 3% in. in diameter, and the large cone taid out accordingly, re- quiring its steps to be 9, 714, and 7 in. respectively... Assuming the motor speed to be 1,750, usual for a small A. C. machine, the pulley installation 112 Parker was worked out accordingly, giving a speed range for. the lathe of 300, 450, 900, 1,200, 1,800, and 3,600. The range of speed obtainable depends primarily upon the dimensions of the lathe cone: if one speed is changed the whole six will-have to change also. The grinder-stand speed was as- sumed to be 2,700 R.P.M., though the proper figure depends upon the diameter of the wheel used; the | SHELF SPACE FoR LATHE ATTACHMENTS & TOOLS } WINGED DOOR INFRONT ff Hinged door wn front “MOTOR SPEED,"1750 . COUNTERSHAFT»’600 Wf CONE. SHAFT," 600-ISO GRINDING WHECL; 6; 2700 i] LATHE, HIGH -1200,1600,3600 [i] LATHE, Low-300.450,900 DISK ENGAGES PINS IN MOTOR PULLEY — SUDING CLUTCH 4 - SHAFT — The diagram illustrates a cabinet containing the motor and counter-shafts for operating the lathe and grinder on top of the cabinet smaller the wheel, the higher its speed. A simple form of sliding clutch is provided, and this is disengaged while operating the lathe. In the drawing, the stand shown is of about the maximum size suitable for a motor of this size; a smaller stand would perhaps be more satis- factory and require less room. A hinged board folds down over the top of the stand when this is not in use, and forms a convenient tool-table; when turned upright it helps to keep grinding-wheel dust away from the lathe. A back-board will also be of service in confining this dust; but, in any case, the lathe should be covered with a cloth before doing any grinding. This particular layout shows the two sets of tight: and loose pulleys of the same size, 6-in., also the larger straight-face pulley. Various forms of belt shippers are possible; the one shown has two handles projecting through the front of the cabinet. Another arrangement would be to have two foot-pedals held up by springs, so that the lathe would stop as soon as the pressure of the foot was removed. Though no specific dimensions or directions are given, the cabinet should be of substantial. construction to reduce vibration and well braced to counteract the various belt pulls.

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April, 1920 Getting a Heavy Barrel Up an Incline NE man can ordinarily handle a heavy barrel when it is on a level plane, but it is difficult to force it up an incline. If a long rope is used as shown in the i Wt ETL ik rr Y =| nu J Was? A No difficulty is encountered in pulling a barrel uphill if you use the method described here iiustration, the barre! can be readily moved. The rope is doubled and fastened over an eye-bolt in the door-sill, the loops being passed around the barrel ends and the ends held by the operator. With the help of this arrangement | one man can pull a barrel up any angle of incline with very little effort. Regulating the Flow ofa Grindstone Lubricator HE ordinary water-holder that is sold with every grindstone has no means of WOOD STRIP eitherregulat- ing or stop- ping the fldw of water. The way to remedy this defect is te fasten a wooden strip across thetop, boring the strip so as to permit the snug working of a wooden Here’s a way to control plug through the water flow on that it. troublesome grindstone The plug is shaped to fit the bottom of the cone, similar to a needle valve in an automobile car- buretor. By raising or lowering the plug, the Published in the interest of Elec- trical Develop- ment by an In- stitution that will be helped by whatever helps the Industry. water in the grindstone’s holder can be controlled at will.—JAMES M. KANE. “Mr. Stephenson— meet Dr. Franklin!” Chug, chugging along in his first rude steam locomotive, Stephenson did not look to “chained lightning”’ to render the inven- tion safe and most widely useful. Nor did Benjamin Franklin, as he flew his kite into the storm clouds, foresee how electricity would in a later day spur the “iron horse’ on to greater achievements. Yet today safety and speed in steam railroad operation are reconcilable only in proportion as electric signal devices are em- ployed. Your protector is, ultimately, the electrical apparatus upon which every steam railway relies. A railroad without telegraph or telephone would hurl itself into the scrap heap. How else to reach out and warn a train rushing into unseen danger? How else quickly to spread the news of damage done -by storm? How else to clear the tracks for the express which carries you onward to your journey’s end? All along the way, night and day, men are alert to shield you from harm. Train dispatchers, telegraph keymen, signal tow- ermen at every city and way station, have no other concern except to see you safely through. So that your trip to New York, Chicago, or the coast is safer, quicker, pleasanter than ever Napoleon traveled in state from Paris to Marseilles. Snugly quartered in a Pullman sleeper you command a thousand watchful hands and eyes for body-guards. But their vigilance would accomplish nothing without equipment in perfect order. On such factors as the proper ad- justment of a telegraph receiver and the responsiveness of an electric switch rests your “Safe Home!”’ That travel has been made secure today is a tribute to the excellence of electrical equipment no less than the skill of opera- tion and the care of supervision that our steam railroads have consistently main- tained. estern Electric Company No So completely does this organi- ‘ zation serve the electrical field that every time you call up your grocer, switch on a light or take a street car down town, the chances are you are making use of Western Electric equipment. J 113

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6s 99 ICan Succeed! “What other men have done with the help of the International Cor- respondence Schools, I can do. If the I. C. S. have raised the salaries of other men, they can raise mine. If they have helped others to ad- vance, they can help me. To me, I. C. S. means ‘I CAN SUCCEED.’” Make pagers mind right now that not another day shall pass until you have made your start toward success. For 28 years men in offices, stores, shops, factories, mines, railroads—in every line of technical and commercial work—have been winning promotion and increased salaries through the I. C. S. More than 100,000 men and women are tting ready right now with I. C. S. help or the bigger jobs ahead. No matter where you live, the I. C. S. will come to you. No matter what your handicaps, or how small your means, we have a plan to meet your circumstances. No matter what career you ma choose, some one of the 280 I. C. S. Courses surely suit your needs. When everything has been made easy for you— when one hour a day spent with the I. C. S. in the quiet of your own home will bring you a bigger income, more comforts, more pleasures, all that success means—can you let another single price- less hour of spare time go to waste? Make your start right now! This is all we ask: Without cost, without obligating yourself in any way, put it up to us to prove how we can help you. Just mark and mail this coupon. oe ee ee eee TEAR OUT HERE Ge eee eee oe ee INTERNATIONAL CORRESPONDENCE SCHOOLS BOX 7672, SCRANT ° Explain, without obi me, how I ualify for the position, pay ee a bo which I mark X. ELEOTRIOAL ENGINEER MAN: ting ana Kys. ADVERTISING Window Trimmer Telegraph Engineer how Card Writer Wo Sign Painter MEOHANIOAL ENGINEER oad Trainman Draftsman ILLUSTRATIN Shop Practice Cartooning BUSINESS MANAGEMENT Operating Private GINEER BOOKKEEPER |\Stenographer and Cert. Pub. A Railway Mail Clerk AUTOMOBILE OPERATING = Repairing " RORNULTURE [Frese Poultry Raising § (Italian State. ‘ Canadians o~ send this ny a to 7-26-46 How to Make a Mission Magazine-Stand HIS cabinet is within the ability of any boy to make, and if care is taken in its construction, a durable and handsome piece of furniture will be the reward. The beauty of the arts and crafts design lies in the simplicity of line, good work- manship, and smooth waxed finish. The following pieces of lumber will be required: 2 sides, 1% in. by 12 in. by 42 in., sandpapered on four sides. 1 top shelf, 34 in. by 12 in. by 15 in., sand- papered on two sides. As the stand will ap- lbottomshelf. pear when completed 2 shelves, 1 in. by 12 in. by 141% in., sandpapered on two sides. 4 keys, 1 in. by 1 ‘in. by 3% in., sandpapered on two sides. The dimensions given are for the finished pieces, and the material can be ordered from any mill. If the amateur craftsman desires to cut up his own lumber, the dimensions must, of course, be enlarged a trifle to make proper allowance for squaring up the i! 4 OO 42° | | uu =—12-—+1 ed ‘5;—— The scale diagram indicates the correct dimensions of each part rough. As the most popular finish is gained by staining and waxing, white or red oak is the best wood to use. Ash also takes mission finishes well, and chestnut, while softer, possesses a beautiful grain, and may often be used to good advantage in making furni- ture of this character. Begin the work by squaring up the joint edges and the ends, but do not cut the shelves to correct length just now. Lay out the outline on the side pieces by using a paper pattern, and carefully mark out the tenons. Carefully study the scale drawings, which indicate the correct dimensions of each part. As shown, the top and Small as well as Popular Science Monthly $200 Saved By This Home Lover One housewife had selected $550 worth of Furnishing locally before learning of this new Larkin plan. The same selection at ourlow Factory-to-Family prices cost her only $350. Wouldn't you call this saving of $200 worth while? May we send all the interesting facts? 800 Furnishings At 17c a Day —2 Years to Pay auickly filled Se ae den” Sen eeeeane Payments as low as 17c a day. Com- pletely furnish an entire home or Larkin Ca, Bo Tee ee Parts of several rooms this convenient way. Get This Bi 104-Page Book FREE >> complete guide a Homes. Write forit now. Find out how easily and economi your home can be brightened. OFFICERS Sy; Cop 3 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 nf the best waterproof ma- hogany calf leather. Guaranteed, 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 to be good for work and dress at the same time. U. S. National Army Shoe Co. ‘Dept. P.M. 795, Westfield, Mass, The little matter of 25 cts. in stamps or coin will bring you the Pathfinder 13 weeks on trial. The Pathfinderis an illustrated weekly, published at the Nation's center, for the Nation; a paper that prints all the news of the world and tells the truth and only the truth; now in its 27th year. This paper fills the bill without emptying the purse; it costs but $1 a year. If you Will H want to keep po: on what is going on Deneve Ses Doeume in the world, at the least] the World ’s Capital and expense of time or money, the Pathfinder is this is your means. If] like in the inner ‘ou want'a paper in your] council h those who F home which is sin-]| mold the world’s destiny. rom cere, reliable, enter- s # taining, wholesome, the Pathfinder is yours. If you would appreciate a paper which puts everyt ns 15Sc to show that you might like such @ = paper, and we will send the Pathfinder on probation 13 weeks. The 15c does not repay ap us, but we are glad to invest in new friends, THE PATHFINDER, Bex 923, Washington, D.C. hing tlearly, briefly—here itis. Send 200 Fifth Avenue Send for a Complete Catalogue of MASONIC BOOKS Jewelry and Goods REDDING & CO. Publishers and Manufacturers Dept.S New York lower shelves are tenoned through the 114 Guaranteed 5 Years Send for Catalog Today. P. BUCHSTEIN CO., 113 6th St, S., MINNEAPOLIS, MINN. BUCHSTEIN’S FIBRE LIMB soothing to your stump,— strong, cool, neat, light. Easy payments. deformi- ties. ae a> 65 «bt i" ct DM 0 —_ ae ae ok. oe, ee

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April, 1920 sides. A good way to mark this out is to place the shelves on the bench > with face edges uppermost and the endseven. Lay the square across and run a pencil line around the edges to get the width between the sides. Now take each piece in turn and pencil a mark entirely around it. Having marked out the tenons, and the square mor- tises for the keys, careful- ly chisel out the mortises and saw out the tenons. == When this The key or wedge can be is done, lay made in several forms the shelf on the side-piece, and, using the tenon for a pattern, mark out the outline for the mortise in the side pieces directly fromthetenon. This will prevent any possibility of a mistake. The mortises should be carefully cut, and there are two ways of doing this. One way is to chisel out the entire mortise; the second to bore a number of connected huies with a bit and chisel out tothe lines. In cutting mortises, take care to keep the sides sharp and clean. Do not attempt to chisel more than half way through on one side, but turn it over and cut through from the opposite side. By doing this, a clean mortise is obtained without danger of splitting or marring the edges. The middle shelves are merely. let into the sides about 4in. That the grooves may not show, a shoulder is © cut about \% in. back from the edges. The key or wedges may be made in several forms, but the plain tapered key is very good, and is mostly used. Whatever the shape of the key em- ployed, it is well to remember that the taper of the key where it passes through the tenon must be made the same size as its mor- tise. Sandpaper well, using No. 1 paper, and finish up the work with 00 grade, until all surfaces are clean and smooth. For finishing, any one of the many mis- Pn gn sion stains may be first measured, used. A very nice then cut as brown may be ob- shown here tained by using one part of Flemish water stain in four parts of water. Brush this on and let it dry. When dry, go over lightly with 00 sandpaper, but do not cut through the stain. A coat of dark brown filler is now applied, according to the directions on the label of the can. Let this stand until the gloss disappears, then wipe off with a cloth, crosswise with the grain. The next day the final finish of wax is applied. Rub the wax well into the wood with a cloth and polish. Dayton Day will be celebrated by Dayton dealers throughout the United States, on Friday, April 23 marking the 25th anniversary of ew ny Ri Hy 14 Be | | i les , We back this Trade~Mark Visit Your Dayton Dealer ; with our Reputation. TWENTY-FIVE YEARS AGO — the first hospitality, and, in viewing his display Dayton Bicycle was shipped from the of new 1920 Dayton models, see for Davis factory. yourself the high point in development On Friday, April 23, Dayton Dealers, and refinement that Dayton has everywhere, will keep open house in @chieved through a quarter-century of observance of the Dayton’s 25th anni- fort. There will be something inter- versary, esting for everyone. eid *) Consider well what a Dayton can do for you— You are invited to visitthe Dayton deal- _can save for you., Write today for new catalog : : . illustrating 8 fine 1920 models for boys. girls, er in your Commanaty,. It will be well men and women. Ask for your dealer’s name worth your while to enjoy your dealer’s and Catalog No. 44. A bicycle is the cheapest and healthiest known means of transportation Cycle Dept., THE DAVIS SEWING MACHINE CO., Dayton, Ohio Ride a Bicycle”

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In

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this new, rich, unlimited field. | one else—Made only in our saree

1. 2. ce A. 3 C old Kills *Rough RouGH onRaTs| “Dont Die in the House” “ these pests where other preparations fail. Mix it = with foods that rats and mice will eat. the kind of food whenever necessary. Don’t be The one perfect SPARK INTENSIFIER. Fires any plug. Banishes spark plug trouble. Saves gas. 100,000 already in use. Pe A safety insuring and comfort-making STEER- ING DEVICE FOR FORDS. Simple. 100% efficient. Makes driving a pleasure. A hot-firing, UNBREAKABLE SPARK PLUG with three strictly exclusive, practical, and sales-pulling features. A“ VISIBLE” SPARK PLUG with all ex- clusive features of above-mentioned plug and equipped, also, with spark intensifier, A HANDY FASTENER for non-skid chains. Locks and holds with a “‘bull-dog’’ grip. Saves the motoring public an enormous loss.

STARTLING INVENTIONS fe =§=Choose your own exelusive territory. Sell direct, wholesale, or both. Our line is a real winner—easy to demonstrate, easy to sell. Your own and surrounding counties may be open now. BIG EARNINGS EASY Here’s something entirely clear of the “old and beaten path”—big, quick, easy money, and a lucrative business of your own. Our exclusive representatives—some with NO OTHER SELLING EXPERIENCE-- have doubled and tripled their previous 1n- comes. No reason why you shouldn’t. Not at all hard. We have something every car owner needs—Can’t buy from any tactory. ae But if you want to share in these profits, then don’t wait—not’ even another minute. Write TODAY for complete information. Post card will do. Send by next mail—sure. JUBILEE MFG. Co. 629 Station C, OMAHA, NEB.

lear your house and keep mice with reliable ‘‘Rough On Rats.’’ them all quickly — and they Brooks’ wonderful on Rats” successfully exterminates mee Change Don’t Wear a Truss modern scientific invention, the relieves rupture, will be sent on trial. No obnoxious springs or Appliance, the new discovery that

MR. C. E. BROOKS Brooks’ Rupture Appliance automatic Air Cushions. Binds and draws

pestered—get** Rough on Rats’’at drug and general stores. Send for booklet,“‘Ending Rats and Mice”. E.S.WELLS,Chemist, Jersey City. N. J. Originator of **Rough On Rats’’ rT Has the broken parts together as _you would a broken limb. No salves. No lies. Durable, cheap. Sent rove it. Protected by U. S. patents. Catalog and measure blanks mailed free. mame and address today. BROOKS APPLIANCE CO., 255B State St., Marshall, Mich.

FOR THESE

BUNGALOW BOOK Plan FUTURE HOMES Now with ECONOMY PLANS of CALIFORNIA STYLES ted f beaut, d ‘adaptability to any chinate, “Representative Cal, Homes” 50 Plans, $3,760 to $12,000—$1 “The New Colonials” 55 Plans, $3,000 to $20,000—$1 “West Coast Bungalows” an meee i 60 Plans, $1,800 to $4,500—$1 Fr get book of 75 or i 5 Fag A flue FREE EXTRA—‘‘Littie Bungaiows"’ 40 Pians, $750 to $3000—50 cts. Money back if not satisfied EW. STILLWELL & CO., Architects, 471 Calit.. Bidg.,Los Angeles

35 Mil Boys, Guild This Car. This nifty little car es driven by gasoline motor, can be built by s ved are wory chore a 26. for an cheap. Di ‘or per hour Is building plans and price list of parts showing Bow to Muikd thie lad’s car. Record of

STRAT 0 DO, OHi

‘WHITING-ADAMS HOUSEHOLD BRUSHES For Public Buildings, Railroads, Steamships, Factories, JOHN L. WHITI Brush Man

EE Le Households, and all other users cleanliness, Whiting-Adams Brushes are positive dirt and dust eradicators. Send for Illustrated Literature NG-J. J. ADAMS CO., Boston, U. S. A. ufacturers for Over 109 Years and the

DALLA O MOET OMIM EINE ITN NN ETT TPO requiring effective Largest in the World Popular Science Monthly Cementing a Rubberized Patch in an Umbrella HE common habit of standing up a wet umbrella in a corner with the handle up causes the moisture to drain down to its point, and this eventually rots the covering. Making a neat job of a sewed-on patch is not easy, and it is a question of time before the patch will tear off again. Recently I discovered a way to attach a rubberized patch to make the repair water- and tear-proof. I

TRIANGULAR STRIPS FIG! FIG2 - (

FIG.S

Don’t throw away that torn umbrella: you can mend it with rubber sheeting | happened to have a quantity of the rubber film or sheeting that is used to fasten the turned-up portion of the bottoms of trouser legs. Cutting it into strips long enough to project over the tear, I punctured a hole in each one, and slipped them down on the rod of the opened um- brella, arranging them in spokelike form (Fig. 1). Into the uncovered small triangular-shaped spaces I fitted small pieces cut to fit. Then I cut a circular piece of black alpaca (Fig. 2), and fitted it on over the rubber. The cap on the rod had to be removed, of course, before either rubber or cloth could be slipped on. After I had arranged the cloth and rubber evenly, I took a small heated iron and ran it carefully over the patch. The result was very satisfactory. If the fabric is not too badly torn it can be drawn together with a thread; but if this is not possible, a thin piece of fabric can be drawn under the ribs so that it comes opposite the tear and extends beyond the edges (Fig. 3). I cut a similar sized piece of the rubber and slipped it’ between the piece of fabric and the tear. To fasten this I cut a hole in the top of a rather deep cardboard box, placed the point of the umbrella rod into the hole, and ironed the repair into shape (Fig. 4). This cardboard disk makes the

BU eee

operation a great deal easier when no

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April, 1920 inside patch has to.be applied. I cut out a stiff piece of cardboard (Fig. 5) larger than the circular piece of. cloth, then cut a slot and central opening to allow it to pass by the umbrella rod. I then slipped this disk between the fabric and the ribs (Fig. 6), which gave me a good base on which to iron the patch into shape. This repair, when properly made, is waterproof and will save many an umbrella going to the trash pile—JAMES M. KANE. To Make a Deep Hoe from an Old Shovel HOE suitable for handling and cutting small irrigation ditches, digging trenches for deep planting, and like purposes can be easily made from an old shovel. Remove shovel from the handle by driv- ing out the riv- ets, and heat the Why buy a ne: when (@) shank of the [5 pee. om shovel blade ina forge or coal fire. When red, bend the shank at right angles and allow it to cool. Then replace the handle, and a good serviceable hoe is the result. A round-point shovel is best for this pur- pose.— WINDSOR CROWELL,

(SHANK HEATED the BENT Electric Lights to Call Employees HE manager of a well furnished modern office found that the sound of the call-bell which he rang for the stenographer, office-boy, or clerk was a source of annoyance to himself and callers to his office. He therefore installed a battery and a set of small electric lights in the outer

PRIVATE OFFICE OUTER OFFICE Instead of an annoying bell the flash of an: electric light calls your employees to your desk office, which were regulated by means of push-buttons placed on his desk. ' In installing such an outfit small 4- to 6-volt lamps and a battery of four dry-cells may be used. The lamps may be placed on a panel in the main office, each lamp designating some particular employee; or if preferred the lamps may be placed on the desks of the employees. The wiring diagram is only sug- gestive. The wires may, of course, be concealed.—FLoyp L. DARROW.

othing to do till po Monday ” HAT’S more, when you have a 1900 Cataract Electric Washer, you finish the wash bright and early each Monday! Do you know why? It’s because of the magic figure 8. In the 1900 Washer the water is forced through the clothes in a figure 8 movement, four times as often as in the ordinary washer, Thus it washes the clothes faster. In fact, it is this magic movement that makes the 1900 the perfect washing machine. You can wash everything in your 1900, for there is not a single part in the tub to cause wear and tear, or to pull off buttons. The water is forced through your clothes entirely by the action of the tub, not by the action of any parts in the tub. When you have finished the wash, there are no parts to lift out and clean either. The 1900 works easily, smoothly, and at a cost of less than 2c an hour. It washes the clothes snowy white and clean if 8 to 10 minutes. The wringer also works electrically, and can be moved from the washer clear around to the clothes basket without moving the washer an inch. “

The water swirls through Comes in 8 the tub in a figure 8 move- and 12 sheet ment four times as often as SIXES, in the ordinary washer, Our Special Trial Offer You may prove to yourself that the 1900 is the perfect washing machine. ‘There is a 1900 dealer near you who will gladly demonstrate a 1900 Cataract Washer right in your own home. Then if you wish, you may start paying for it on terms to suit your convenience. Remember, we also have washing machines operated by hand and water power. Write us today for the name of the nearest 1900 dealer and a copy of the book, *‘George Brinton’s Wife.’’ It’s a story you will enjoy. Molly, his pretty little wife, had troubles of her own until she interrupted a bridge party, and then things began to happen. 1900 CATARACT WASHER | 1900 WASHER COMPANY 206 Clinton St., Binghamton, N. Y. Canadian Factory and Office: CANADIAN 1900 WASHER COMPANY 357 Yonge St., Toronto

Just connect it with the electri light and off it starts.

1900 WASHER COMPANY 206 Clinton St., Binghamton, N. Y. Please send me the name of the nearest 1900 dealer and acopy of the § story, ‘‘George Brinton’s Wife.**

——NAME

ADDRESS

CITY AND STATE. sit

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VER the hills to the country---far from the Job and the City! Not just once ina long while, but every Sunday or every evening if you like, when you have a Harley-Davidson! Miles are mighty short, and trips are very cheap, when you have a ‘‘World’s Champion” to whisk you there and back. Forty to sixty miles on a gallon of gasoline, with tire and other upkeep costs low in pro- portion. Ask Your Dealer About His Easy Payment Plan HARLEY-DAVIDSON MOTOR CO., MILWAUKEE, WISCONSIN. Harley-Davidse@:s “Worlds Champion” That is what gives them chances for promotion. They start in at a good “es Phi Many who started our course a few months ago now positions. OUR BROOKLET tells of this ideal vocation ~out in the out-doors—how you associate with big men— you can earn an excellent salary from the start—how you can cleab te the | Sit ete nt RAI aaa Tire Repairing FIC Learn a Profession ree J Earn From *300 to*600 11} | | [treo with | a month a il BIG MEN Be a Tire Expert, | C@eavice sTarion) weteach you free nn at our school or by mail. Thousands are getting in now. salary — $110.00 a month and expenses. —a can tsounn dgbenae on eno vglnnes, | And Sey \ wines they attract the favorable attention of their REPAIRING superiors. Promotions then are rapid. Learn This Profitable Profession «ce All you need ig a common school education 3 We Put You entrance to our three-month’s course, In a p ay ing which is to learn at home during your 2 - ee Semend for Railway Trafho fnapectors i S Business of Your Own so good. THERE I$ A BIG OD 18 THIS FIELD. . We know of fine openings for our graduates. Right fi rom the Start in a growing profession, Motorists- The to portuni' UPON | a better now and Small investment may mean a fortune to you in a short time. It assures you a large profit “Have your tires and tubes repaired by the new and famous Popular Science Monthly A New Kind of Index for the Photo-Plate File HE subject matter of a photo- graphic plate stored away in a rack is usually unknown unless the plate is removed and held to the light. But with the index shown in the illustration fitted to the plate-rack the nature of any plate in it may be seen at a glance. Two large metal tabs hang at the side of the rack drawer, which is equipped with a carrier so that it may Fig. 1 shows how the description is alined opposite its plate; while Fig. 2 shows the method of slip- ping a card into its proper place be drawn out all the way. Slips of paper, each one carrying a descrip- tion of a plate, are fitted in each tab. When the rack is drawn out and the tab lifted, as shown in Fig. 1, each description lies directly opposite its plate. The tabs swing on two wire hooks which are screwed into the frame- work of the rack. These tabs are made of sheet tin, and, when necessary, may be lifted from the rack. The method of slipping the paper into the tab is shown in Fig. 2.—EpwarpD R. SMITH. Make a Sprayer for Your Indoor Plants T is advisable frequently to spray window-garden plants in order to give the leaves, stems, and flowers water in a finely La divided state just as nature 4 renh does when a i 4 “— CORK thick fog cov- ; ers everything IN with its wet ie soe small and A simple and simple sprayer 4 convenient can easily be sprayer for constructed. house plants, This consists that you can make yourself of two tubes and a_ cork. For the tubes take two lengths of goose-quills, straws, or thin glass tubing. Cut a section from the cork as illustrated, and bore two holes through the cork at the cut ends and co ct m= 45 =e > SA et 85 Oe yy fF FF ~~ we LC ~ Pr 45 TH FF >_> bei at aelUveelClU

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April, 1920 at right angles to each other. Now push the tubes through the holes until they meet, being careful to have one tube slightly above the other. To use the sprayer, place one tube in a glass of water and the other against the lips. If a draft of air is now blown through the tube a partial vacuum will be produced in the other tube, causing the liquid to rise in the tube and be projected from the nozzle in a fine spray.—ERNEST BADE. A Reciprocating Pump-Jack Made of Pipe-Fittings PUMP-JACK for small pumps i \ can easily be made of common pipe-fittings. It is of a reciprocating nature, and will operate a pump at a considerable distance from the source of power. The diagram illustrates its construction. A long piece of pipe the desired size constitutes the main or horizontal shaft. To this you attach lengths about a foot long, one to each end, by elbows, so that one is vertical and the other horizontal (A and B). To these projecting pieces, at right le) SET=SCREWS 7 NIPPLE A SIDE You can make your dwn reciprocating pump-jack from discarded pipe-fittings angles to them, elbow short nipples, and the jack is done. Simply provide set-screws at each elbow, so the threads will not start because of the strain put upon them when under load. Also drill a hole in the end of each nipple for cotter-pins. Set the jack at the base of the pump ; at right angles to the pump handle in suitable bearings. The vertical arm is attached to a wooden rod, as shown, which goes to the pulley wheel on the motor or counter-shaft, and is attached to it eccentrically, like the connecting rod of an engine. The horizontal arm is attached to the pump handle by a second wooden rod. A metal clamp, as shown in detail, serves to hold it firm and allows it to be shifted along the pump handle, thus varying the stroke. Cotter-pins keep these rods from running off. As the power rod moves backward and forward it lifts and lowers the horizontal arm. This operates the pump handle and also pumps the water.—WINDSOR CROWELL. Those White Teeth Ask People How They Get Them All Statements Approved by High Dental Authorities Millions of teeth are being cleaned ‘in a new way. You see them everywhere —white, glistening teeth. Ask about them. The owners will tell you, probably, that they use Pepsodent. ‘They have found a way to fight the film which causes most tooth troubles. Millions have already proved it. Lead- ing dentists everywhere advise it. And over 6,000 new people daily write us for a 10-Day Tube. | Why Teeth Discolor | A viscous film forms on the teeth and coats them. You can feel it with your tongue. Modern dentists know this film to be the teeth’s great enemy. It clings to teeth, enters crevices and stays. The tooth brush does not end it. The ordinary tooth paste does not dissolve it. So it remains to do a ceaseless damage, until removed by cleaning in a dentist’s chair. Let Your Make this free test. Look at your teeth now, then look in ten days. Let your mirror tell the story. Pepsodent is based on pepsin, the di- gestant of albumin. The film is albuminous matter. The object of Pepsodent is to dissolve it, then to day by day combat it. Science has lately made this method possible. Pepsin must be activated, and the usual agent is an acid harmful to the teeth. So it long seemed barred. But a harmless activating method has _ been Pepsaodéent The New-Day Dentifrice The scientific film combatant, now ad- vised by leading dentists everywhere and supplied by druggists in large tubes. Film is what discolors — not the teeth. It is the basis of tartar. It holds food sub- stance 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. So, despite the tooth brush, all these troubles have been constantly increasing. Now We Combat Film Dental science, after years of searching, has found a way to combat film. Five years of careful tests have proved this beyond question. The method is now embodied in a den- tifrice called Pepsodent. It complies in all ways with modern dental requirements. And a 10-Day Tube of this tooth paste is now sent free to anyone who asks. Mirror Tell found, so active pepsin 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 the fixed film disappears. The results are quick and evident. They are all-important. You will never go back to old methods when you know them. For the sake of cleaner, safer teeth cut out this coupon now. Ten-Day Tube F ree THE PEPSODENT COMPANY Dept. 165, 1104 S. Wabash Ave. Chicago, Il. Mail 10-Day Tube of Pepsodent to ee ee ee) 119

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STEEL BOATS CANT SINK Write for catalog showing more than 40 models of steel and wooden power boats, rowboats and canoes. Safe for you or your family. Buoyant air compartments . like a life boat and strong steel hulls. warp, leak, waterlog, dry out or open at the seams. No calking required, no boat house needed. Designed by America’s foremost naval architects—built in the world’s largest boat shop. More than 70,000 now in use. Mullins power boats have the best marine motors. Quiet, vibration-free operation is insured by the Mullins patented silent under water exhaust. Mullins Steel boats can’t THE MULLINS BODY CORPORATION Boat Dept., 619 Franklin St. SALEM, OHIO DO YOUR OWN PLUMBING AND HEATING sf a COST Send for our big instruc- tive 256 page Handy Man Book catalog. Ev- ery home owner, farmer, contractor, etc., needs it. Shows over 10,000 fix- tures and supplies in plumbing and heating at wholesale, how to save skilled labor and unnec- essary material, by our new CUT-TO-FIT METHOD Besides being our whole- sale catalog this instruc- tive Plumbing and Heat- @& ing encyclopedia helps you select and install the proper PLUMBING WATER SYSTEM, HOT AIR, WATER OR STEAM PLANT, has many plans, diagrams, sketches, ele- vations, etc., plainly showing how to do the work, this newer easy way with the aid of this BIG HANDY MAN BOOK We have spared no effort and have gone to a great expense to compile this valuable book and to eliminate broadcast circula- lation, we request a deposit of 25 cents which will be refunded A on first order, or send for our free bulletin. HARDIN-LAVIN CO. 44 Years at 4526-36A Cottage Grove Avenue, Chicago $500,000 Plants Behind Our Guarantee. ins BO ERSTE Boca wt AN EASY WAY TO MAKE MONEY 22: on 8 small salary. Be independent. Go in the tire re ring 2 cage e One man eays “I made $00.00 ¢ he first paint Others e $200 to $500 a month. Very — capital nected. "Soe plentiful. aot motorist a sible customer. No experience need ng ao it. eae e only 3. A Boy that has Automatic Heat Control, and can’t he nae or overcure a tire. or regulating. FREE Book ee Open Tire an ll Ie tals how to make big’ money tdelay. Write Cc. A. SHALER co. Gi 2115 Fourth St. | Waupun, Wisconsin 90 to 125 wan Miles on a Gallon of Gasoline! The Shaw Motorbicycl A high-grade, running, speedy motorbicycle of “ese ble power at a saving of from a third to a half in actual money. Meseeets with 24% H-P Motor, famous Breeze , high tension magneto. Automatic lubrication. Chain drive, Simple, efficient control at all times. ace in use, Write today for and terms, also about the Shaw At nent—fits any old bike. SHAW MANUFACTURING Co. Dept. 364, GALESBURG, KANS. 500% AGENTS erorit 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 over the country. There is a big demand for window lettering in every town. Send for free samples and particulars. Liberal Offer to General Agents. METALLIC LETTER CO. 433A North Clark Street, CHICAGO, ILL 120 Popular Science Monthly Don’t Buy an Expensive Piano Lamp; Make One VERY serviceable piano lamp may be made from a thin strip of mahogany about 19 in. long and an electric lamp- Cut the strips as shown in the illustra- tion. No meas- urements can be given, be- cause pianos ; differ in con- w ntthaaeg aay ae struction. not scratch the pi- After the strips ano or fall from it are nailed to- gether they are sandpapered and varnished. The lamp-socket is attached to the right end, as shown, and wired to a con- venient plug. Strips of felt are glued beneath the holder so that it can- not scratch the varnish at any place.—ROBERT SCHMITT. Do You Know These Things About the Oiling System? AKE sure the oil-gage on your automobile is free to move, as a wrong indication is serious. Some- times the wire is bent, and the gage does not fall as the oilis used up. The inexperienced driver does not realize this and his engine runs dry. — A gage ought to be within reach, so it may be tested by moving up and down. It gives a striking object lesson when the oil-base has not been cleaned for several thousand miles. On pushing the float down into the heavy oil muck at the bottom, it stays there, showing the need of a thorough cleaning. Few people realize that oil de- teriorates under heat, and that the spoiled oil in the crank-case thickens, accumulating carbon from the cylin- ders and making a thick, pasty mass that will not pass through the pump. When necessary to change the oil, say every thousand miles, it should be drained out carefully. Some of the muck remains and mixes with the fresh oil, reducing its lubricating qualities. This is unavoidable unless the crank-case is removed for cleaning. It is dangerous practice to put kerosene into the crank-case and then to run the engine to cut the muck and so drain it out with the kerosene. The bottom of the oil-base is covered with grit, metal chips, and other fire- grinding material which will be stirred up and forced into the bearings. . To avoid this, remove the oil-base and clean it by hand. ; Check-valves, which control the flow of oil in a plunger type of pump, should be cleaned occasionally te insure proper working. When the oil does not flow or the gage shows no pressure, it may be because the pump is air-bound; usually cleaning the check-valves removes the trouble. ,. =e

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April, 1920 Repair Your Bicycle Tires at Small Cost EXT time you get a tire ee, don’t go to a bicycle store and pay a high price to have it repaired. Try this simple expedient. Get a large darning- needle (the neice larger the bet- ter), and file off the end near the top of the eye. Press the pointed end of the needle into a block of wood about three inches square ce] a ° ~aionnieae uh cone and an inch punctured tire. Here’s thick. a quick way of fixing it Take a hand- ful of elastic bands, and pass as many as you can through the crotch in the needle and around the block of wood. Put some rubber cement in the hole to be fixed, and push the filed end of the needle in the puncture as far asit will go. With a sharp knife cut the rubber bands across the back of the block of wood. When this is done, the rubber bands will contract and the ends will stick out of the puncture. The next step is to apply a lighted match ‘to the projecting bands so they will melt and fill up the punc- ture. In a few minutes, when the rubber is cooled sufficiently, the tire can be inflated. Very large holes and rips cannot be patched in this way, because the crotch of the needle will not hold enough bands to fill the hole or rip.—ARTHUR GOLDENBAUM. Some Practical Uses for the Magnet SHORT time ago somebody gave me a horseshoe magnet taken from the ringer of a telephone. I didn’t know just how I could use it, but it has proved useful in a number of ways. When I spill a box of nails in dirt or shavings, instead of picking them up by hand, a long and tedious job, I just |. take the magnet and pick them up ina hurry. Sometimes, in working around a machine, I drop .a screw or piece of || metal into a difficult place. The magnet picks it up instantly, saving much time and bother. When a nut drops into an auto- -mobile’s crank-case or transmission, I simply make use of the magnet to remove it. Otherwise I would have to fish around with a wire for an hour or two before I could catch the nut. These are only a few of the many uses for a magnet. Get one and see how quickly you can locate that unseen piece-of metal that is delaying your Li’ iatts ‘(ae > r Some « Xa Via a ts eee tte a5 Tiresome strap-hanging is avoided- boosted trolley fares saved —comfort and health -pro- moted—lost time done away with—when you sit in the easy saddle of a 1920 This American family’s time, money, and health saver is soon paid for with saved trolley fares and a nest-egg started. Swift, smooth-running, lightweight but pow- erfully strong, trim, and equipped with the ab- solute best of everything, you will find the Columbia the favorite wherever those who work with hand and brain have investigated bicycle values. Your local dealer will gladly explain the su- periority of the 1920 Columbia and its many big features. See him today and start saving. Sena for 1920 Commbia Catawog, showing models and types for every- body, all at reasonable prices. WESTFIELD MANUFACTURING CO. 45 Lozier Ave., Westfield, Mass. pit. a Bicycle work.

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ie NR atin OS ATR Pe a as

jearn Auto... Tractor Business

by Rahe Practical Method Standard Instruction of America. The Rahe method includes 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 oe United States.

Auto & TractorSchool 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 $450 to $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- Og.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.)

fal

KT Ci? wa | Ip ASU eo v.. é “WELL DEVELOPED HEAD

Do You Know that Tree- Planting Is a Science ? REE-PLANTING as a memorial in honor of the men who sacrificed their lives for their country is being taken up widely this spring. This commendable custom should be ob- served not only this year but every year. Tree-planting should form a permanent part of the improvement program of every city and town in the United States. Here’s the way to do it scientifically: TREES PRUNED AS ORDINARILY REQUIRED A iN IF ROOTS ARE FULL = = ers CROWN NEED BE BRANCHES FORMING LESS CURTAILED. WIDE.NOT CLOSE ——— BASE OF PERMANENT ANGLES WITH STEM CROWN 10 FEET ABOVE PAVEMENT STAKE 2¢ *10FT. DRIVEN 2 FT. INTO GROUND — RUBBER-COvERED ” WIRE OR CANVAS ~ BINDER ~~~ BASE OF TEMPORARY CROWN 7 FEET ABOVE PAVEMENT PLENTY OF FIBROUS ROOTS BROKEN _ ROOTS CUT OFF SMOOTH MULCH OF PULVERIZED saul I ———

<= JQROWING SPACE -JAT LEAST 6 FT.

WS S = lel SQUARE BED DUG OUT 18-IN. NS DEER, THEN FILLED To RICH EARTH PACKED LOWER ROOT LEVEL FIRMLY ALL ABOUT WITH MIXTURE OF ROOTS 3 GOOD SOIL AND # ROTTED MANURE This diagram from the American Forestry Association shows how to plant a tree properly Keep Your Distributor Clean and Dry XCESSIVE oiling of a magneto can do nearly as much harm as insufficient lubrication. One thing it does is to cause the surplus oil to be thrown into the distributor, where it works much mischief. It gets between the brush and the contacts and either insulates them from each other en- tirely, causing missing, or it causes arcing. Arcing burns the oil and forms soot, which interferes with the good working of the machine, and it also produces heat, which disintegrates the carbon brush and causes it to crumble. All magneto manufacturers make their distributors so that they may be removed easily and wiped clean with a dry, clean cloth. One type of ma- chine, for instance, has its distributor held on by three little clips, retained by three thumb-nuts. These may be loosened by hand, the clips turned, and the distributor cover will come off inthe hand. Other magnetos have three screws to retain the cover. Some have a central revolving brush and stationary contacts in the cover and others a revolving contact and individual stationary brushes in the cover. The brushes in either case are attached to small springs and may be slipped into or out of their sockets by hand. 122 Popular Science Monthly

Get Into a Steady, Profitable,

Permanent Business. ||

Open a TIRE REPAIRING SHOP! Make bigmoney! Noe mastered. Tire repairing has no dull season. Extreme cold weather has detrimental effect on tires— they need more careful attention and frequent repairing. VANDERPOOL VULCANIZER (5 Cavity) has work a day. MANUAL and wire immediately.

WM. VANDERPOOL CO., Springfield, Ohio

In answering address Dept. A-1 dom * eel | jee s a We supply complete outfit. Send for FREE TIRE REPAIRING xperience necessary. Easily capacity of $100 worth of full particulars. Write or

Why use Coal or se Wood? ( \ 7 Og CD) pits a Valve wna

uarantee. NTS OLIVER QIL-GAS BURNER & ait Ni 7th St... WAN : ED MACHINE B B80 _ St. "Se, Hue, From Prine. The Oliver 0 Oil Cas Burner makes- 2 gals. oi1 cqual 97 lbs.coal

“DON'T SHOUT” J howe ne I = omg now as

PH pa nd 1 one hundred thousand sold. THE MORLEY CO., Dep Wits THE e MORLEY my ears now, but they are in- visible. I would not know I had them in, m How?’

ONE. I’vea pair in yself, only that I hear all right The Morley Phone for the DEAF what glasses eyes. Invisible comfortable, ben ge and ‘0 csand o Write fo for foowlet and testi- t, 797, 26 Gonth 15th Street, Philadelphia

5) Print Your Own cards, circulars, labels, , tags menns m) book, Press $8. book. .baper. OUTS 3 Repeats HALF. Maa SMALL OUTLA

5. Job a oie for ~ itself in short time. ill lat for years. Easy to use, printed rules sent, Print for others, Wis FF ROFIT. Write factory ODAY for press catalog, TYPE, cards, paper, “eg, stig EXCELSIOR THE PRESS CO., 33, Meriden, Conn.

for over is caused expensive. stateme

DEAFNESS I know because I-was Deaf and had Head Noises Wholly De easy to take out. Are “Unseen Comforts. IS MISERY 30 years. My invisible Antiseptic Ear ms restored my hearin and stopped Head weeny and will do it for you. ey are Tiny Megaphoni Cannot be seen when worn. Effective when ees by Catarrh or by Perforated, Partially or stroyed Natural Drums. Easy to put a in n- Write for Booklet and my sworn mt of how I recovered my hearing. A. O. LEONARD Gutee Gan, 60 Oe Avenue e e New York City +

, an - — -—- gai —" ax CUCU TOOT

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April, 1920 Calipers for Inside and Out- side Measurements N a certain job it was necessary to find accurately a number of both inside and outside measurements. Not having calipers at hand, an improvised tool was made. A piece of clock-spring seven inches long was obtained, likewise two darn- POINT FOR Agu Fi MEASU REMENT. HOOK FOR OUTSIDE MEASUREMENTS re NEEDLES + CLOCK SPRING A piece of clock-spring and two darn- ing needles make a pair of calipers for inside and outside measurements ing needles. In each end of the spring was cut a long hole just large enough to take two needles. , Hooks were bent on one end of each needle by heating, and both were placed in the holes in the spring, as shown in the sketch. The tension in the spring held the needles together until the measurements could be taken down.—DALE VAN Horn. A Tray-Warmer for Amateur Photographers HERE are many occasions when the photographer, either amateur or professional, constantly has to heat his developer or other solutions so his pictures will come up properly. This results in loss of time and fluctuations in temperature that tend to impair the quality of the work. The electric heater shown herewith is designed to accommodate the stand- ard size trays, and it will keep the solutions at the desired temperature under most conditions. First build a box of matched lumber, using %-in. stock. Build it 16 in. . long, 12 in. wide, and 6 in. deep, out- LIGHT Switcn *— REO LIGHT ae 16" —> t ASBESTOS LINING SPOINT SWITCH LIGHT STANDARD \ Showing the apparatus in detail _ with all parts marked to scale side measurements. Leave the top open. Line the inside with asbestos paper and carry it up to the top edges. The tops are built of narrow strips of wood }% in. thick, and mitered at the corners like a picture-frame. The sketch shows how they nest inside of each other, so any size tray can be used. Build the first or largest one 16 by 12 in., with the opening 1034 by 1234 in. The second one should fit snugly in the first, with an opening 814 by 10% in. The third top fits in we W.L. DOUGLAS WAS PERMITTED N TOATTEND SCHOOL FOR SHORT WN PERIODS DURING THE WINTER MONTHS WHEN THERE WERE. SLACK SPELLS IN THE WORK $920 320 & $1990 po 90 SHOES 7 OCCASIONALLY HE HAD TO FACE PUNISHMENT FOR TARDINESS BECAUSE HE WAS KEPT AT THE Ba WORK BENCH PEGGING SHOES W. L. Douglas shoes are ‘wold through 107 of our own stores direct to the wearer at one profit. All middlemen’s and manufa profits are eliminated. W. L. Douglas $9.00 and $10.00 shoes are a ately the best ~ 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 — as a protection against high prices and unreasonable profits is only one example of the constant endeavor of W. = Dou to protect his custom- ers. Sg las name on shoes is his ade “that —_ are the best in materials, workmanship and style — sible to produce at the price. ito every pair go the results of sixty-seven years experience in making shoes, dating back to the time when W. L. he quality of W. L. Dou yn is T "guaranteed ‘by more aoe) experience in making fine shoes. The [ere 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 2x- — men, all working with an honest etermination to make the best shoes for the price that money can buy. ‘ The retail prices are the same everywhere. They cost no more in San Francisco Douglas was a lad of seven, pegging shoes. do in New York. W. L. Douglas shoes are - sale by over 9000 shoe dealers besides our own stores. Fhe local dealer cannot suppl ou, take no other make. Or er direct from the factory. Sen ¥o r booklet telling how to order shoes by mail{ postage free. President W. L. rae 7 st upon = perme Fs & Yl Douglas sh oes. The na stam: ay Ay m chan or mutilated, BEWARE OF AVOID LUMBER SHORTAGE Lumber shortage—a virtual famine of Jumber—exists in many parts of the country. Ly a —— that it is impossible even now to get ma for certain needs. Stocks were never so low as they are ~~ wr Thi The demand was eS 80 is a. Means Still Higher Prices. It means that up b-day nam grey 4 uy $100 worth peasy [~ mo te ae a monk forced tenes ee your need of yoy in six month 00 cost you : 0% or 100% penalty? UILD Early buyers of Aladdin Homes are savured B NOW delivery. Aladdin p~ tye action 15 necessary. A nd os homes will 800 mn fill the Aladdin one maa aa memeneeta es om NATIONAL SERVICE as fol- aa ge pr oot its cent de cee ea decd, to yak Brac , Li forests of th United States, - op. Fs eresert f timber in from the mart rt "* No, 1873 to of the needs of the coun’ : for \e ret enema ee ake parts of the country will Soeb ili te ti f. N. The Aladdin Company, Bay City, Michigan Ms c_Mieeoot , nyt a of materials Branches: . Ha!

Page 104

No Other Typewriter Can Do This: MULTIPLEX HAMMOND'S Insvonvvy changeable ype Many styles, many Languages H Two types or languages al ways in the maching

Bee AD INC

Most Wonderful “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. You “Just turn the knob”—to change language or type.

**Many Typewriters In One’’ ie Sounds like an Arabian Nights story but the 64 machine itself is very practical, very real. Itis the typewriter President Wilson uses personally— the typewriter he took with him when he visited King George. Types for all purposes i and for all Languages Spacing to sult size of type Perfect alignment Gutomatic Sybe Imbreosion All on one MULTIPLEX The marvelous INSTANTLY interchangeable type feature is only one of the many reasons why thousands of prominent men and women in all walks of life prefer and personally 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 4 you use in speaking—an exclusive feature of the Multi- pDiex. Write your name, add and

tion on the margin of this page NOW and mail to : HAMMOND TYPEWRITER CO. 639 East 69th St. New York City Aiso an Aluminum PORTABLE Model. 1lilbs. Full capacity. Ask for special Folder. 2 aE

afi ge A ALTE. SIT Dp Sopchera Sd AA AK KK Sa / sat J Spe . ; ERE TSE b= 775 ho by at least one inch. Wind it

with iron wire ,--————1 aseestos so no two turns '}—t=——” touch. The [-———— Binoing- amount of wire = ees oR to use can only — be determined by experiment, as the size of the wire makes considerable difference. Wind it closely at first, and connect one end to the binding- post which is inserted in the asbestos. Connect one electric wire to this binding-post and place the other at different points along the wire until it becomes too hot to touch. Now place a binding-post at that point and connect to the heater wire. Then place another binding-post be- yond that one and a fourth one at the end of the asbestos. Rivet four small angles of metal to the asbestos and to the inside of the box half way be- tween top and bottom. See that no portion of the wiring on the heater touches the box or electric wires except at the four binding-posts. Fit a plug receptacle and a three- point switch to the right-hand side of the box and connect up as indicated in the sketch. One terminal goes to the lever of the switch; the other direct to the binding-post on the heater. Then each point of the switch is wired to the binding-posts as shown. An electric light standard can be bolted to the back of the box and fitted with a 4 C.P. ruby bulb if desired. This should be wired direct to the plug circuit as shown. It will be an additional con- 124 The heater is com- posed of a sheet of thick, stiff asbestos wound with iron wire

First aid in _ every household -Musterole Cough, cough, cough. How it racks little Dorothy and passes on to mother and grandma and holds a croup danger for all the little ones! Hurry, there, with the Musterole, that pure, white ointment that is better than a mustard plaster—and it will not bring a blister. Massage it gently over the chest and neck. Feel the tingle, then the cool delightfulness as Musterole searchesdown. It will penetrate, never fear. It will rout that old congestion clear away. Musterole is a pure, white oint- ment made from oil of mustard and afew home simples! Muster- ole searches in under the skin down to the heart of the conges- tion. There it generates a peculiar congestion -dispersing heat. Yet this heat will not blister. On the contrary you feel a relieving sense of delightful coolness. Rub Musterole over the spot. And you get relief while you use it; for Musterole results usually fol- low immediately. On no account fail to have a jar of Musterole handy. For coughs and colds and even the congestions of rheumatism or lumbago Musterole is wonderful. Many ‘doctors and nurses recommend Musterole, 30c and 60c jars—$2.50 hospital size. The Musterole Co., Cleveland, Ohio BETTER THAN A MUSTARD PLASTER

10 Cents a Day Pays for This Symphonola Plays all records, Victor, Columbia, Edison, Pathe, Little Wonder Emerson. Take a year to pay, after 30 days’ trial. Compare its tone for clearness, volume, with more costly instruments. Return at our expense if it fails to wared gona Ask today for the Beautifully Illustrated Symphonola Book FREE Shows this and other ends 9 styles sold on easy payments. Get list of the latest Symphonola Recor s dance, Dopular, clear sounding, full graph. toned disc records. Playable on any Phono Ltthitt Coe desk SPSM 420. Buffalo, N.Y, - Golden Gem ve PORTABLE ¢ * Adding Machine

€ t | ee G S14 rat noe. 5. — a If KE 80672 2mm Buy through your stationer. |ay@ingan TPR } Writefor 10-day TrialOtfer |Rg/sray ts P. E. Gancher, A. A. M. Co. [BAe Ji 3m jim 148 Duane St., New York y Canadian Agency ME Protirtr a ae ee Multiplies - Subtracts §*%

Page 105

foril, 1920 venience and can be turned on and off at will as desired. Set the tray of solution in the opening adapted to its size and turn on the current at the plug. Then throw the switch on the first point and let the wire warm up. _ If not hot enough, throw the switch to the second point and to the third if found

TOLAMP a] $F. s. -ccnceugebesdevsccten Soadetrece> . Please fiil out all lines, 2 RY ENE Gare Lt Se RE RE RE Few ae

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ee eer een ert Suva MN. SPL SHS | *4 000 aYear in’ TiRESU GERY 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. }4 Wonderful Saline Easy to Learn—No Experience Necessary Uncountable millions of tires are cut, torn, gashed and bruised, broken down, worn out, yet with the Haywood method cf tire month, pos confining= : myself solely to re-build- surgery all these tires,no matter how far gone, can be put back into service. Every town, every hamlet, every city needs Haywood Tire Surgeons, and it’s that we are offering you— @ business of your own—a_ business that is already making hundreds of men rich and so will make you. ing of Tires Haywood Method.” — $6,500.00 Home Paid For John W. Blair, ‘Toledo Ohio, says: “When I started three years ag self. Let us send you all without obligation the business. In fact, how tosuce ™, HAYWOOD pounder of the best investment you ever made. 626 CAPITAL AVENUE YOU CAN LEARN IN A WEEK... Walk right into $2500 to $4000 a year—be ipSepenions : in business for your- Mail Coupon —Get My Free Book Just put your name and address on the coupon be- low, send it to me by return mail, and I'll send you r ull particulars of this money [I making opportunity. My Free Book explains === ra 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 = how to handle every detail o and make money. Don’t wait. Write me today. The postage for a stamp or post card will prove £& M. HAYWOOD, President HAYWOOD TIRE & EQUIPMENT COMPANY ‘0, I had_ just $50.00 left after paying for my outfit. I now have a $6,500.00 home paid for, $1,000.00 in one bank, and de- posits in several others.” -_ INDIANAPOLIS, INDIANA : i hhehert Le EinAnstkesbepatperhapop ens was «canen nee acuccwks + Ta-day For All Facts: > M4. HAYWOOD, President ry "oak Come TIRE & EQUIPMENT COMPANY . Capitol Avenue, indianapolis, Indiana * Dear Sir:—Send me quick. without obligation, full particulars of Tire Surgery. : Name ' Address IMPLE WIRELESS TELEPHONES AND HOW TO MAKE THEM. An elemental book on the principles, con- struction and use of an arc system of wireless telephony. ustrated. Price, postpaid, 25 cents. POPULAR SCIENCE MONTHLY 225 West 39th Street New York - HOW TO MAKE WIRELESS INSTRUMENTS. A little book that fully describes the construction of spark wireless instruments and apparatus. Just the thing for the amateur. Illustrated. Price, postpaid, 25 cents. POPULAR SCIENCE MONTHLY 225 West 39th Street New York “Lighting Fixtures” Ready to hang. Direct from manufacturers. Completely wired including glass- ware. = Send for new No. 18 catalogue. ; ERIE FIXTURE SUPPLY CO. oe Desk “HO-LEAKOga. ONE PIECE \ gies On market 5years, mw 011 SEALING P 4 1,000,000a month. Seer ——$F Beware imitations. heal pi q gi “NO-LEAK-0” PISTON RING Scsove 7 Patented Trade Mark Reg. NO-LEAK-O Piston Ring Co., Baltimore, Md. AMAZING PROFITS ) in Hares and Cavies We pay $7.00 to $13.50 a pairfor Hares and $1.50 to $2.00 a pairfor Cavics, and Express Charges. Wefurnish largest and finest guaranteed high rade stock and buy all you raise. ee Illustrated Booklet and Contract. UNITED FOOD & FUR ASSOCIATION 329 W. 48th St. Dept. 4, New York You CanSaye $50.00 By recovering your old auto top fiame yourself. We ee these — fit all makes and models of cars. Any person that can $6 84 a eat drive @ car can put it on. a ree We furnish instructions. Roof and quarters sewed with together rear curtain, fasteners, welts and tacks. All complete. Give as the name, year ros model maniet of your car and we will send you ol and quote you exact price. LIBERTY TOP & TIRE CO., Dept. E8, Cincinnati, O. | Power Grip » of Dental ARMS OF STEEL “|, [The Barker Power Grip will double and treble the strength in your fingers, hands, wrists and forearms in a remarkably short time. The is of special value to and 4 recommended by Doctors urgery, Pianists, Telegraph Oper: ; Strong grip is admired more than any other feat of ») has saved many a person’s life, in cases of emergency. Those who suffer ® from cold hands or perspiring hands will obtain great benefits by s) price of the Barker Power Grip 1.OO postpai Prof. A. BARKER, D. C., Studio 6500, 127 W. 42nd St., N. Y. ators and T: ters. A . In fact, it 126 Popular Science Monthly Are You Interested in Boiled Automobiles? m OT broiled—boiled!”’ exclaimed the repair-shop manager. “Oh, I thought you said broiled,” replied the visitor. ‘‘Even so, I think they would make tough eating.” The manager gave a sigh of despair, and then went on to explain the merits of the new boiler, into which parts of an automobile are thrown for the purpose of removing the grease. The illustration gives a general idea of the construction. A 4-in. pipe leads into the boiler, and is surrounded with the water. (BO! LER AIR "BURNERS An easily constructed hot-water bath for removing grease from automobile parts Inside this pipe is a gas-burner of any suitable make, the flame from « hich plays against the interior of the piping and raises the water to the boiling temperature. A good washing powder is sometimes added to the water and aids in the cleansing. Parts of an automobile can be ree paired more effectively when clean, and no better method for the cleaning is found than simply immersing in the hot-water bath. A few minutes’ boil- ing removes all particles of grease, and leaves a clean surface that can be soldered or otherwise mended. Not only the surfaces but the interiors of parts are thoroughly cleansed by this boiling process.—H. C. RIDGELEY. Assuring the Motorist of Properly Alined Wheels INING up the wheels of an auto- mobile is a problem that many motorists do not attempt because they do not know how; but the following method is easy and accurate in every case. Set the car in an open space on an absolutely flat floor. Place two boxes on the floor, one about two feet from the rear right wheel. Now stretch a STRING oF 1 Automobile wheels out of alinement give short tirelife. Keep them prop- erly alined by this simple method string between the two boxes, being careful to keep the string at an even distance from the floor. Measure from this string to the front and rear parts

Page 107

[ April, 1920 of the right front and rear tires. If the distances are not equal, shift the are exactly so. The string will then be exactly parallel to the line of the wheels on that side. Then, with a second pair of boxes and a string, do the same thing on the left side, thereby obtaining another line. When this is accomplished, measure across from one line to the other, making sure that these two are equal distances from the wheels. Do j the same at the rear. If these two measurements agree exactly, the wheels are in alinement. 1 How a Drill Is Cut to Bore Hard Rock : ’ URVEYORS in mines use as a per- manent station mark a “spad” driven in the roof of the mine. This is a flat piece of metal driven into a wooden plug that has previously been driven into a hole bored in the solid rock of themineroof. They then hang a plumb-bob This drill will from the bore through the “spad” as a hardest stone sight-line. The rock composition of the roof may vary from soft shale through several degrees of hardness to what is called sand-rock, which is the hardest rock to drill. Perched on a ladder with one foot and hanging on with the other, it is no easy job to take a regular hand drill and hammer upon it. The writer tried a brace and regular twist drill, but even that wouldn’t bite. Several different ways of sharp- ening were tried out, and finally the way shown in the illustration was evolved. A _ high-speed twist drill sharpened in this way will drill almost any stone. By cutting its center away the same effect is produced as with the diamond drill used for remov- ing test plugs.—S. B. ROYAL.

A Very Useful Drawing-Table Extension y N extension to a drawing-table which is as simple as it is useful, and which, when not needed to increase the capacity of the table, can be instantly converted into a convenient ‘ tray for holding accessories, is shown in the illustration on page 128: ' The extension consists of a 12-in. board of a thickness corresponding to that of the table, and provided with two narrow cleats about two feet long. Each cleat has through its free portion a 3%-in. hole at a point close to the board to permit the passage of a 14-in. stud, which is tightly screwed into the

boxes or the steering wheel until they

TheWorld of Industry Needs PT SMEN You Can Learn Quickly By Our Practical Method If you are a person of even average ability, you can master this profitable profession in your spare time at your own home through our famous ‘*‘Home Study Course.’’ You can in a short time Uessene 0 Sest chee Eaeee be- oo of the fact obey e our

you will A versonally Tertvosted and coached by the President of the school, Roy C. Claflin, whose long experience ass draftsman and a teacher especially quali- fies him to give you the kind of training you need, We teach you to work from actual models <p as you would in a drafting room, of merely copying from booke. Draftsmen Get $35.00 to $100.00 a Week Every mechanical idea must be drawn out by the draftsman before it can become a reality On account of the importance of his work, he is therefore paid a good salary and is always in line for advance- ment. Drafting is not only one of the best paying professions, but is the stepping a to bigger opportunities. Many men, receiving up to $40,000 a year, and over, in technical positions, owe their success to their athe a of Drafting as | the starting point. General | construction of y, es, and aut biles, desi, of tnaltesaapstiok omties ment, makers of aeroplanes, large engineering companies; in fact, all branches of industry need DRAFTSMEN today in greater numbers and at better salaries than ever before. ‘¢‘Columbia’”’ Graduates are the Kind of Draftsmen that are Needed The properly trained Draftsmen, such as those graduated by the COLUMBIA SCHOOL OF DRAFTING, are the ones who get the preferred positions and best salaries, and are the ones who are most greatly in d d. The of our students demon- strates this fact. Columbia gr tes are filling important positions in big concerns at the country. We wi like to send you a book of testimonials from many of our hundreds of students and graduates ee present nny paid positions as Draftsmen are the result of their practical train- ing with us. A few of these letters are here reprinted. No Previous Training Required As our students are given practical Drafting work from the be- ginning of our course, they grasp the essentials quickly, so that no previous training or drafting experience of any kind is required to take up this work with us. You do not even need a high school education to learn Professional Drafting as taught by this school and the training we give _~ is = that is needed to secure a position as Drafteman (Read P. John- ’s letter).

How Columbia Students Succeed “ (More letters on request) “I have ent ony a tion as draftsman, paying $ .00 a year = ban 23 I had no Pow a or drafting rience aside from my caning with you, which has proven all was needed for me to become a professional draftsman.’’ — Lau- rence P. Johnston. (Mr. Johnston expects to be advanced to $3,300 & year in a few weeks.)

“Several firms have offered me $40 and $45 a week to start. As I am doi nicely as draftsman up here and about to receive my second increase in salary, have decided to stay. I find there are nundreds of openings for drafts- . Men and if I quit where I am I could secure another position in three hours’ time. There will be 2 an greater demand for Drafts- .”’——-Geo. Murray, Jr.

“I wish to express my ap-

preciation for your courteous Drawing Outfit Furnished Students i pen ig a janes R. We furnish, wighoms mans charee, an individual drawing outfit to all our y\ aiding me, ‘upon completion vot | avons" cour a'becs pelt Torr apanscset a: desirable os position at t $140 a month MAIL THIS TLI IIIT titi ft | om getting on well | COUPON TODAY @ A the” chances for advancement H] COLUMBIA SCHOOL OF DRAFTING are excellent.”—A. L. Gash. Your future success (5 wes 1097, 14th & T Streets; N. W. ; depends upon what you r Washington D.C. : = wick Wgsetiet geet pete | Se Deets Be eee nufac con- are interes in thout bog in ‘Chicago and wish ton hank mecning ¢ this interesting . ie esteatel "beek” Pgh ne tactimontale rain: our 00) an paying pro- ceosl Geruet has given me. Emil B ¥ gh ~~ fession, aan the follow- & OR ey OO ing coupon WITHOUT & A few of our many other suce' | DELAY for our Free [% Name .............+0+ £3 a Cae of etek o b ccccoucdesesdesadebs cage desnbos ° . orra, & year; coLumal. SCHOOL © T. R. Brown, $2,860 a year;! 4 . R. Fowkes. $3.700 © yon ae s Dinees and Weiy 60 esccsavecechvacasbabeon ecccce ° : ene? Streets, NW. 8 ‘ Washington, Cc Se Oia dekctoendeaavaceekiis SRG swiiethinvacaoasd

poy bes hoice of instruments Yentte Ena lave vous chsles of tes gad 0 comvito niet prices, A sausie Pack, all accessories, fastruction book, etc, mg ‘oe Convenient Monthly Payments Aftertrialretarn outfit xt our expense if vou wish. If youdecidetobuy ae ‘ou may the low direct in small mon’ Wisalleed doe 66 prove lo Romees meant highest Send this is Coupon ree send fap’ zee free wines ieee Ge We B. dth ad ee

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i pe grea a dit LI ORES R SCRE I AY Iasi A Sak IPAS SN SS ES a Sige eee and Some Old Boxes ed SAN FRANCISCO BOY, “J. P. B.”” (name on A request) turned the trick. He says any Auto- wheel Owner can do the same thing whenever there is a parade or a big celebration in town. Just before one of the big Frisco parades, this lad collected up a lot of empty wooden boxes. Then, when the spectators began to line the sidewalks, to see the parade, he loaded his Auto-Wheel with all the boxes it would hold; and started through the crowd. And, as he said, the people almost fought one an- other to buy the boxes at 25 cents each —to sit on. He handled about $5 worth of his ‘‘stock’’ at a time. for he found he could fit the boxes one inside the other. The Auto-Wheel Coaster can carry 1000 pounds with ease, so he had no need to fear overloading. -De. You Know the Story of _ Auto-Wheel Wagons? The Auto-Wheel Coaster and Auto-Wheel Convert- ible Roadster have boy friends all over the country, and in Canada. The Coaster is an all-around wagon for hauling and coasting. The Convertible Roadster is two wagons in one. One minute it isa box wagon. Swing the sides up, and you have a long, lean racer, built to suit a boy’s own ideas. Auto-Wheels are sturdy wagons, easy to steer, fast and smooth running, good looking. Roller bearings give real speed, and there’s a dependable brake for slowing down at corners. Auto-Wheel Magazine Free Every boy should send for this interesting publi- cation. Getonthe mailing list. Send us the names of three Coaster dealers, telling which one handles the Auto- Wheel. We send the magazine — also the Auto-Wheel Booklet— free. asf @eee) §=Organize An ofhato whee? Louse amy Auto-Wheel | Coaster Club Write us for our plan of giving FREE caps to members of these clubs, and a special cap to the captain. THE BUFFALO SLED COMPANY 157 Schenck Street, N. Tonawanda, N. Y. In Canada; Preston, Ont. When they equip their guns with the Maxim Silencer. It eliminates the report en- tirely. No flinching, no recoil, no “nerves. "Makes target practice and small gun shooting a fascinatiny pastime for the fice .22 cal. 00, Youcan ~~ lf. ask at i 8 for free book of astonishing exper: ences of Maxim Silencer users The Maxim Sitencer Co. ' 84 Homestead Ave., Hartford, Ot. WANTED—A Representative in every fac- tory in the United States, Popular Science Monthiy, 225 West 39th Street, New York, table-top from the bottom. A wing- nut on each stud permits the extension to be quickly tightened or loosened. Such an extension is exceedingly useful where the capacity of a drawing- table must be at times increased, as in ‘perspective drawing or for excep- tionally large work. If desired, it can be instantly demounted, but this will hardly ever be found desirable. In- stead, by merely unscrewing the wing- e—-AS AN EXTENSION —y AS A SHELF : This extension to the drawing-table is a great help to the draftsman in limited quarters nuts a few turns, the extension may be converted into a wide and con- venient shelf for holding drawing instruments, pencils, pens, ink erasers, and other objects where they are both out of the way and cannot roll on the work. There is no obstruction in the path of the T-square, since even if it is longer than the width of the table, it will pass over the objects on the tray. On account of its construction, the extension when in this position is securely in place, the weight of the board itself holding the free ends of the cleats firmly.— HENRY SIMON. Making That Rickety Chair Steady Again HE chair with one or more legs that are everlastingly coming out is a nuisance and should not be tolerated. It is a common-source of annoyance now that chairs are fre- quently made of unseasoned wood. Here is one way to re- pair the offend- ing leg. In the loose end, across the middle, make a split 4% in. deep or thereabouts. This split should be at right angles to the grain of the chair bottom into which the leg fits. Remove all glue, if there is any, from the chair- bottom hole. Next, get a good piece of walnut or some other hard wood, and cut out a wedge }% in. long and as thick as the looseness of the offending leg requires. Insert this wedge tightly into the split. If the leg is very loose, daub a little glue about the leg end. With the wedge inserted in the split, plaee the leg end in the bottom hole, and with a hammer drive it back to its original position. As the driving process is continued, the wedge enters into the leg end. The result is a leg end which fills its hole tightly and never comes out.—JOHN T. BARTLETT. 128 An easy and efficient way to mend a chair leg that falls out of place Popular Science Monthly 4... 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. It saves those long, hot, 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, Ask for our booklet and learn about the 30-day trial plan. Lockwood-Ash Motor Company 2013 Jackson Street Jackson, Mich. (69) Build Your Own PHONOGRAPH It’s Easy With Our Help | Get Our FREE “ives you's Goo machine exacuy to | Blue Print ca at Gee ee, 1. succeed because our system is simple. No special skill necessary. We {urn‘sh complete, plain plang and diagrams—motors, tone arms, case material, every thing required and full instructions. Charles F. Mancke, Washi ton, says:—Received the outfit- and am well pleased. Bui one machine for myself and took an order for one for $115. I have mine done. It has a wonderful tone. Make Money Building Phonographs Ask for our Sure-Fire Plan ~ and Free Blue Prin: Offer. We have started manv others. Wecan start you Ple-sant, easv work. N. J. Adams. \.ichizan, says: — **Just sold u.y phonograph, which | built from your plans and parts at nearly $100 pro it.’ We are the old reliable house originators of the home building _ idea. Get our proposition. Write today. Choraleon Phonograph Ce, «The “Tumble Home” of the ‘Kennebec makes it so—this feat! 4 eure is illustrated here—the dotted sline being The Tumble Home of §the ordinary canoe—the black org wutsideline that of the Kennebeca ‘, Fullest particulars with illus- ¢ trations of all our models ¢ ‘given in our 1920 book, ,’. _ sent postpaid. J KENNEBEC BOAT AND CANOE CoO. | 29R. R. Square, Waterville, Maine. SAVE 25°. to 60% on slightly used GRAFLEX-KODAKS Cameras and Lenses of every description. que. tonew. Save money. Write now for _Free Bargain Book and Catai “ listi: bundr of money-saving bargains in slightly used and new cameras and - Ali goods sold on 10 days Free Trial. loney ack if not satisfied. You take no chances dealing withus. We have been in the photo- graphic business over 16 years. Write now- CENTRAL CAMERA CO. Dept.64, 124 Wabash Ave., CHICAGO $5000 IN SCHOLARSHIPS Entries Close April 1, 1920 If you want to compete for one of Popular Science Monthly’s $500 Scholarships ask your school principal te send in your name on or before April1, 1920. Full com: ditions were published in the February issue. Scholarship Committee, Popular Science Monthly, 225 W. 39th St., New York ad Jewett bhOMmMD.3 a

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Old Town Cances’ An “Old Town Canoe” will jump at the thrust, or glide at the dip of a paddle. Floats light as a fleck of foam, but every “Old Town” has the built-in strength and sturdi- ness to withstand many years of rugged service. For the youngsters, buy the “Sponson Model” the canoe that’s safer than a row boat. Write for catalog. 3000 canoes in stock. $67 up from dealer or factory. OLD TOWN CANOE COMPANY 1994 Main Street Tells how yen can build and fly accurate, reduced- scale Models of real Aeroplanes; DE HAVILLAND — — NC-4 and others. Y - You can build one easily. nd 10c in stamps NOW and get this 48-page book. Aeroplanes—NC-4 Plans for Model . 50c; DE HAVILLAND Battle Plane, Cur- tiss Military Tractor, Bleriot Monoplane, Nieuport Monoplane, Taube Monoplane, 35c each; Cecil Peoli Champion Racer, 25c. Send for Plans or Book Today. IDEAL AEROPLANE e Cor. Houston and Wooster Sts. New Yo ‘THIS book, “The Daysof Real Sport, ’’illustrat- ed by Briggs, the cartoonist and containing a red- blooded story of boyhood fishing days, will be sent FREE to every sportsman. | Learn of the pleasure. excitement and thrills which bait casting angling gives--enjoyment you can have, No sitting still waiting for them to bite. Book shows fullline of South Bend Tackle. Sent FREE. SOUTH BEND BAIT CO. 14586 High St. South Bend, Ind. Unt HAVE YOU A SAW AND HAMMER? Then Make Horses and Money Send 50 cents for this simple cut-out. What you can’t sell. yourself we guarantee to uy. TOY COMPANY ELBO Cor. 121st St. and Ashland Ave. Richmond Hill, L. I. WANTED—A Representative in every Sectory in the United States. POPULAR SCIENCE MONTHLY, 225 West 39th Street, New York. A Two-in-One Triangle for Draftsmen N making a mechanical drawing, both the thirty- and the forty-five- degree triangle are usually employed. A single triangle, however, if shaped like the one in theillustration, may be used to lay out any angles that are multiples of fifteen degrees. The position of the triangle in. the upper part of the fig- ure is conve- nient for draw- ing lines mak- ing angles for which the thirty-degree- triangle is ordi- narily made use of. The forty-five-degree angles may be laid off with the triangle in the position shown in the lower figure. By laying off a fifteen-degree line and placing the edge of the triangle upon it, a seventy-five-degree angle may be made with ease, and other combinations will occur to the reader. If desired, the interior of the triangle may be cut out in such a way that the seventy-five-degree angle may be laid off at once without shifting. Some draftsmen like the two-in-one triangle and do excellent work with it, while others are so accustomed to using the two triangles that any change would be entirely out of the question. Everyone has his pet habit, if he is aware of it.—H. C. RIDGELEY. By varying the posi- tion of this triangle, any angle that is a multiple of fifteen de- grees may be drawn You Can’t Lose This Rubber Stamp UBBER stamps have an annoying way of hiding themselves when wanted, and on the small desk where papers pile up it takes a lot of time to locate them. In an office where a certain stamp is con- stantly used this method of keep- ing it always within reach was adopted. A number of rub- ber bands were knotted to- gether, to form an elastic cord long enough to permit the stamp to be easily pulled down to the work required. When released the stamp returns to its original posi- tion.—JAMES M. KANE. RUBBER BANDS Suspend your pet rubber stamp by elastics above your desk-top 129 Because They Know How to Sell! Why Don’t You Enter This Big-Pay Field? Look at the four pictures above. They are men who stepped out of small pay jobs into big money positions in the selling end of business. None of them had ever sold a dime’s worth of goods before. Yet they quickly became Star Salesmen and their earnings average over $7,352 a year! They owe their amazing success to the National Salesmen's Training Association, an organi- zation of top-notch salesmen and sales managers that has shown thousands of men how to win big success and financial independence in the selling game. Let their success be yours! Open your ayes t@ the splendid op- portunities of the wonderful, fascinating profession of Salesmanship. Salesmen top them all in-making money. Get into this great field where jobs are_ten to one as compared to others and the pay many times greater. Earn $2,500 to $10,000 A Year Why be satisfied with less when you can so easily learn the secrets of suc- cessful selling and fit yourself for splendid success in this wonderfully fascinating pro- fession? Let salesmanship do for you what it has done for others. The National Salesmen’s Training Association will train you, in just a small part of your spare time at home, to become a Star Salesman, and it will help you to secure a position just as soon as you are ready. You can go on the road, travel anywhere, stay at the finest hotels, and have all your expenses paid, or you can stay in your own city as a salesman. Do not miss this wonderful opportunity to make from three to ten times your present earnings! Free Proof That We Can Make you A Star Salesman And Help You Land A Job All we ask any intelligent, ambitious man to do is to send us his name. Just mail the coupon or a post- card. We want to prove to you that we can make you a Star Salesman—that we can qualify you for a position in the ranks of men who are earning $2,500 to $10,000 a year and more. This costs you nothing. The coupon below will bring you ‘“‘A Knight of the Grip,’’ our wonderful big Book on Salesmanship. It will’show you how thousands of men from all walks of life have, through N.S. T. A. training, masteréd the secrets that only Star Salesmen know, gone out and earned salaries many times greater than they ever re- ceived before. Twelve years of success are behind this marvelous organization famed for its record in training men to sell. If you really want to get ahead—want to earn big money instead of wages, don’t delay another day in getting this free proof. Don’t wait another minute. Write NOW. Address 4 ? ee é af National Salesmen’s Training Association Dept. 15-D, Monadnock Building, Chicago, U.S.A. PS A A A NE OR CC AE AN NN OLNEY Ge SOME NY eT National Salesmen’s Training Association, Dept. 15-D, Monadnock Bldg., Chicago, U. S. A. With no obligation on my part, please send me ful? information about the N. S. T. A. Training and Em- plovment Service. Also a list showing lines of business with openings for salesmen.

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Electricity Learn at Home There is a wonderful opportu- nity right now for young men who like electricity. If you are ambi- tious and will train yourself in spare timeyou tan step into a good position and get experience that will give you a real start toward success in life. Good salaries are offered with rapid promotion. For 28 years the International Correspondence Schools have been training young men for suc- cess in €lectricity and over 200 ’ other'subjects. They will help you repare right at home for a position in the line of electrical work you like best—or in any other work that appeals to you. Thousands of men, through: I. C. S. training, have stepped into fine jobs, 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 may start you on a successful career. ‘This is your chance. Don’t let it slip by. Mark and mail this coupon mow. “@ — —— ee a ===TEAR OUT HERE —— ae ae oo INTERNATIONAL CORRESPONDENCE SCHOOLS BOX 7673, SCRANTON, PA. ' Explain, without obli: tin me, how I can qualify for th position, or in the subject, betore which I mark x aan penser: ogg ENGINEER OHEMIOAL ENGINEER Electrici SALESMANSHIP Electric Wiring ADVERTISING MAN Electric’ Lighting Window Trimmer Electric Car Runnin: Show Card Writer Heavy Electric T Outdoor Si Electrical Deatenea” RAILR OADER Electric Machine Designer ILLUSTRATOR Tel core ee BUSINESS elephony Ni MANAGEMENT MECHANICAL ENGINEER Private Secretary Seeenanicel Dealiomen BOOKKEEPER: ip Dra an Stenographer and Typist Machine Shop Practice Cert. Pub. Accountant ee aker evi 1 ENGINEER Surveying and Mapping Traffic Management Commercial Law GOOD ENGLISH STATIONARY me MINE FOREM'N OREN@’R CIVIL SERVIC ARCHITECT Railway Mail Clerk Architectural Draftsman Textile Overseer or Supt. PLUMBING AND HEATING AGRIOULTURE Spanish Sheet M orker PoultryRaising French Navigator Automobiles Italian Name nt 7-26-19 Occupation Street and No State. MOTHER who couldn’t bear to throw away her baby’s first shoes called upon a number of electro- platers to see whether she could have a metallic coat applied to the shoes. Her idea was to preserve them and at the same time make them ornamental. Leather is a non-conductor of elec- tricity and it was for this reason that electroplaters thought the work impossible. How- ever, one enterpris- ing young man accepted the com- mission and suc- cessfully carried it out. A new field for the electro- plater was thus opened, and today there are a number of large concerns that specialize in this particular kind of work. There are five successive steps in plating the shoes: drying; water- and acid-proofing the shoes; making the shoes conductive to the current; copper-plating; finishing, as buffing or polishing, and lacquering. The drying can be done either in the air or in a chamber of hot air. The first operation is to make the shoes absolutely water- and acid- proof. Unless this is done, the solu- tions will penetrate and destroy the leather, thus spoiling the whole opera- tion. First dip the shoes for about thirty minutes in a hot composition made up of 8 oz. beeswax, 2 lbs. paraffin and 5 oz. rosin. Upon removing the shoes, you will find that they are coated with a thin film. This is allowed to cool. The next operation is to give the shoes a thin coat of shellac and allow them to dry in the air for about three hours. When thoroughly dry give them two coats of the fol- lowing mixture: 3 0z. copper-plat- ing bronze pow- der, 4 pint lacquer and )% pint amyl acetate. After the shoes have been care- fully and_ thor- oughly coated place them again in the air to dry. This usually takes from five to six hours. They are then ready to be copper-plated. Before the shoes go into the plating Here are the completed shoes encased forever in a thin film of brilliant metal Popular Science Monthly Immortalizing Baby’s First Shoes By Samuel Wein solution, great care must be exercised not to handle them roughly, for even finger-prints prevent the correct depo- sition of metals. Now secure a 2)4-gallon porcelain crock or glass jar, and pour in the fol- lowing solution: 2 lbs. copper sulphate, 2 gals. water, and 6 oz. sulphuric acid. Upon this crock place two brass or copper rods and connect them with the source of cur- rent. From ene of the rods suspend one shoe in the so- lution, and on the other rod hang a piece of sheet cop- per about 6 in. square and 1} in. thick. The rod that holds the shoe acts as the cathode and the piece of sheet copper as the anode, Thesource of cur- rent employed may be from batteries, and their amperage must be in the neighborhood of six or eight to the square foot of surface to | be plated. The potential should be about one volt. Leave the shoe in this solution for about twenty-four hours, when a coat of 1/64 in. copper will be smoothly deposited upon them. Allowit to dry and then buff or polishit. Some people prefer a different metal fromcopper. Brass is very attractive. Here is the formula for brass used by _ the writer: 6'0z. copper cyanide; 9 oz. zine cyanide; 3 oz. hypo; 3 oz. sodium phosphate; 1 gal. water. Brass-plating is done on the copper and requires about one hour. When the plating is finished and polished, it may be lacquered all over, to prevent the metal from tarnishing. The shoes may be polished from time to time with an ordinary metal polish. j Po 2 ~ 5 ¥ J Every mother cherishes baby’s first shoes. Here’s a way to preserve them in metal

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. Regia You Can Do It— You Can Play Those Jazzy Song Hits Without Knowing One Note From the Other Ne—not by the do-reemi method. Not by the old tiresome method of notes and scales and arpeggios. Not at the great expense of years of fruitless study. There’s a new way—the simplest, quickest, most interesting method of learning to play the piano that you ever heard of. It makes it easy to play a song by ear after hearing it a couple of times. You Can Learn to Play in 3 Months You can learn at home, during your spare time. It will not require long hours of study and practising. It is not expensive. Our amazing new course, developed jyist a year ago, has taught hundreds of men and women how easy Jazz music is to play. Many of these could not play at all when they began our course. To-day they can reel off the latest, snappiest jazz music by ear. It’s the New Method That Makes It Possible For instance, when you receive the course by mail, you'll be surprised to find how easy it is to understand. It just comes natural to you to pick out pieces on the piano as we teach you. And you make progress from the very start. The lessons will show you some real little tricks of playing. Our students, after finishing the full course are able to play anything they hear. All by ear. The person who can play jazz to-day is popular in any crowd. His talent gives life to any party. And, if he develops that talent as we teach him to develop it, the oppor- tunities for profit are splendid. The Stage is open to those who can play the piano as the Niagara method teaches. It may be hard to believe. You may doubt, as others have, our ability to teach you by mail (in one-tenth the time and at one-tenth of the usual cost) what most music: teachers cannot teach you by personal instruction. But if you'll let us send you our literature, you’ll find some proofs that will surprise you. Just write for our FREE Booklet and see. NIAGARA SCHOOL OF MUSIC Dept. A-3 Niagara Falls, N. Y. NIAGARA SCHOOL OF MUSIC, Dept. A-3, Niagara Falls, N. Y. COUPON cuce'tr an” ae. FREE Booklet describing your method of POS 5 6s iss ae es bas City i131

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Popular Science Monthly For the Radio E-xperimenter

Electron Relays as Amplifiers and Oscillators : By Fig. 1. A typical

a vacuum tube as an amplifier S an amplifier an electron relay A supplies a great need. As an oscillation generator it is no less valuable. Only ten years ago the problem of the production of high- frequency continuous oscillations was one of the most important and difficult problems in the radio art. This was specially true of oscillations of moder- ate power produced at high efficiency. There was then in existence the Poulsen arc; afterward came the Goldschmidt and Alexanderson gen- erators. These devices are used com- mercially for the transmission of radio and telegraphic messages, and have been ‘successful over long distances. Large amounts of power are needed, however. When compared with the thermionic vacuum tube, we find that the ares and generators lack certain advantages that the vacuum tube possesses and that place the tube in a different class. It is true that at the present time a single vacuum tube does not handle very large amounts of power. This does not, of course, mean that it will

KO oto VOLTS always be lim- ,; . ig- 3. How the plate ited to short- circuit current at =< distance trans- stant voltage is altered mission. As a PY Changing the voltage matter of fact, 2PPlied tothe grid circuit it will be recalled that in 1915 the American Telephone and Telegraph Company and Western Electric Com- pany transmitted speech by radio from Arlington to Paris and Honolulu, a hook-up for using » distance in the latter case of five thousand miles, and this was done with the thermionic vacuum tube. Once experiment has indicated the

A small Poulsen arc generator way, commercial applications are sure to follow. The use of the vacuum tube as an oscillation generator for the transmission of speech over several hundred miles is already a commercial possibility. Whatever the amount of power that the tube is made to produce in the form of alternating current, the prin- ciple of operation is the same. One advantage of this type of oscillation generator is high efficiency. Another is that it can be made to produce oscillations varying over a considerable range of frequency. This varying can be adjusted almost instantly, and the power output controlled with the expenditure of hardly any energy. Oscillations from Direct Current In order to understand how the tube can be made to produce oscillations from direct current, it is necessary first to look into its service as an amplifier. It is the amplifying prop- erty of the tube that makes it a valuable device. The electron cur- rent flowing through the tube from filament to plate can be controlled by varying the potential on the grid, and-to vary this potential only a very small amount of energy is necessary, although the variation of energy in

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A vacuum-tube amplifier set of German war- time manufacture, captured by the French the output or plate circuit can be very large. This is its amplifying property and it is due to the grid. Suppose the tube be inserted in a circuit such as that shown in Fig. 1. The circuit FGL, forms the input circuit and FL,P the output circuit. The coil L, of the input circuit forms the secondary of the input transformer, and is prefera- bly wound to have a very high im- -pedance. The transformer in the output circuit is wound to have an impedance equal to the resistance of the tube. Currents coming in from the line A are amplified by the tube. By this 132

H. J. van der Bijl, M. A., Ph, D. F Fig. 2. Showing how the current depends upon the plate voltage PLATE CURRENT

FIG.2 PLATE VOLTAGE! we mean that if the impedance of the line A is equal to the impedance of the line B, we find that the current in B is greater than thatin A. This is how the tube is made to amplify telephonic currents on long-distance lines. To explain this a little more fully, let us consider the characteristic curves of the vacuum tube. The rela- tion between the current in the output circuit FPL, and the potentials applied to the grid G and the plate P with respect to the negative end of the fila- ment F is given by the equaticn I = A(E, + #E,)" where E, is the potential difference between the filament and the 1 late E, the potential difference between fila- ment and grid. Suppose that in this equation E, be made equal to zero; that is, let the grid be connected directly to the negative end of the filament. Then the relation between the current I and potential E, on the plate can be given by a curve like that shown in Fig. 2. It will be noticed that, as the plate potential is increased, the current at first increases more aad more rapidly, but finally becomes independent of any further ‘Siaeaeomnantegt 7 increase in the plate voltage. This maximum value to which the current rises depends on thetemperature of the filament. Fig. 4. The amplifying If the filament ability of a vacuum is raised to a tube depends on its out- higher tempera- put circuit resistance ture the current VOLTAGE AMPLIFICATION

FIG4 Repo —» will increase un- * til a higher maximum value is reached. If, on the other hand, we give the plate potential a constant value, but vary the potential of the grid, we get the curve shown in Fig. 3. It will be seen that when the grid potential is zero the electron current flowing from filament to plate is not zero, but has a value given by OF. This is because the potential on the plate causes a field to act through the openings of the grid and so pull the electrons through the grid to the plate. If the potential of the grid now be made positive, the current to the plate increases 2s shown by the curve FG. If, on the other hand, the potential

pl Fi

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April, 1920 This Fine Natrometer Set Furnished Every Student of the National Radio Institute. € and built especially for us and comes to you complete in neat It is a wonderful set designed carrying case. It embodies the same type of wireless instruments which are used by the United States Bureau of Navigation in testing applicants for first grade wireless operators license, with the addition of many improvements developed through our years of experience in this field. The Natrometer automatically sends you wireless messages just as you would receive them from a station thousands of miles away. We do not merely loan you the Natrometer. We give it to you. It becomes your per- sonal property upon your completion of the course. Special Privileges to National Radio Institute Students Students of the National Radio Institute receive the following: Complete combination course in Wireless Telegraphy and Tele- phony— Special post-graduate course at our large Washington school, if desired — Five text books, one hand book, forty-six special lessons and eighteen personal examinations— Membership in the N. R. I. Radio Relay League and handsome blue-and-gold membership pin presented immediately upon enrollment— 3 Large handsome diploma suitable for framing— Complete automatic Natrometer outfit and carrying case— Personal help in securing wireless position and endorsement of Institute officials. Send For FREE BOOK We have prepared a book telling all you want to know about wireless and the Sas it offers you, stating facts you are interested in are freely discussed. It tells how, during the past six years we have helped hundreds of ambitious men and women and how we will help you. Send the coupon to-day or write to the National Radio Institute—America’s first and foremost—Est. 1914— Dept. 188,—14th and U Sts., N. W., Washington, D. C. The Nationai Radio Institute Dent. 188, 14th and ,.U Sts., N. W., Washington, D. Cc. Radio Telegraphy and Telephony Mastered at Home by Marvelous New Method Through our Famous Home Study Course and with the help of our wonderful Natrometer outfit you can quickly learn both Wireless Telegraphy and Telephony in a few short weeks in your spare time and at home—without inconvenience or loss of time from work. Students of this institute have finished the course and secured their official license after approximately only ten weeks’ in- structions. First Grade License Guaranteed Our course is so thorough and our method of instruction so practical that we are able to guarantee that, after successfully completing our course, you will be able to pass the examinations and secure a first-grade government operator’s license. Salaries Up to $15,000 a Year The pay of Wireless Operators, Radio Inspectors, Wireless Aids, Machinists, Electricians and Wireless Engineers varies from $225 a month to start for oper- ators to $15,000 a year and salaries should advance steadily in line with the rapid developments in this profession. The demand for wireless operators and workers in all branches of wireless is enormous and positions are guaranteed to all graduates of this in- stitute as soon as they secure their first grade govern- ment license. Travel and See the World or locate in one of the many Land Radio Offices now open. Radio provides a broad field of opportunity and activity. If you like to travel you can visit foreign countries—if life on the seas or lakes appeals to you there are postions in coastwise and lake shipping service—if you are best fitted for indoor work and prefer to be near your home there are the land radio stations, manufacturing plants and railroads—and for real adventure you have the aerial mail and commerce. MAIL THIS COUPON TODAY (ewe Rae as eae eae telling ea B= = NATIONAL RADIO INSTITUTE, ~ Dept. 188, 14th and U Sts., N. W., Washington, D. C. 3 Send me your free book, ‘‘Wireless;sthe Opportunity of .Today,”’ 3 me about the opportunity in Wireless, your Famous Home Study Course. in Wireless Telegraphy and Telephony, your post-graduate course, the N. R. I. : Radio Relay League and your special wifeless instrument offer. & PRN a5 Wo boos eee} Geen hoi vac ima tout ts hie eaten es tan Be BAdar OD SS EE Ad ic vo wich Oknale ck aeus Oe aA hs MEL bgt Hine neeeah g . CHR on bose b bs Coe ve KER WEA we CER rd 688 See State: cai:

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There is crying need for Finger Print Experts right now and the demand for these trained men is growing every day. A profession that offers wonderful op- portunities for advancement. Govern- ments, corporations, police depart- ments, institutions and individuals have constant use for these specially trained men. The work is fascinating and The Paylis Big! No special education is necessary. You can become a master of this profession by studying at home in your spare time. Expert Finger Print men travel all over the country solving mysteries that baffle all others. They are important men and highly regarded and envied by every one. a Mail the Coupon Re Get full information about this great profession and our big offer of a free course in Secret Service Intelligence. The mastery of these two closely allied professions places a brilliant career within your grasp. Achievements that will immediately place the stamp of suc- cess upon you, are now possible. Send this coupon for full information NOW. University of Applied Science Nees Finger Print Experts are Desk 9204, 1920 Sunnyside Ave., Chicago Gentlemen: Without any obligation whatever send me your cew. FREE ook on. on F r Print id of a free course in Secret artes Intelligence. ns pags FTTH PRO O EO EOOEE HEHE SEES ES ESE EEEEEES SOOTHER THO EOEEOEOEDEEESEC EE EES OSE EEEES of the grid be made negative, the cur- rent to the plate decreases as shown by the curve FEC. At the point C the negative potential of the grid is sufficiently high to neutralize the effect | of the positive potential on the plate. The positive potential on the plate Here are the principal parts of the Poul- sen arc shown in another illustration tends to pull the electrons away from the grid, while the negative potential on the grid tends to drive them back. When these two effects are equal the current through the tube is reduced to zero. The exponent ‘“‘n” in the equation is not a constant sd we consider the whole range of the characteristic up to the bend at B in Fig. 2 or Gin Fig. 3; but it can be put equal to a constant for shorter ranges of the characteristic, to a sufficiently high degree of ac- curacy for the purpose for which the tube may be used. Thus if the tube is used as an amplifier (in which case we operate over the part of the characteristic EF or somewhat greater) we can put n=2. For lower values of current the ex-. ponent n generally becomes larger, and for higher currents it generally becomes somewhat smaller. . Referring again to the circuit dia- gram shown in Fig. 1, let the Popular Science Monthly the grid does not become greater than DO, it will be seen that the grid never becomes positive with respect to the filament, so that the grid never takes any current,. and therefore there is practically no expenditure of energy in the grid circuit. The power in the plate circuit is therefore varied without it | being necessary to spend an appre- | ciable amount of energy to do so. Explanation of Constants The constant » is knewn as the amplification constant of the tube. What it really means is that a change in the potential of the grid produces p times as great a change in the plate current as an equal change in the plate potential. In other words, we can look upon a change, e, in the grid potential as being equivalent in effect to an electromotive force we impressed in the plate circuit. The tube can therefore be used as a voltage amplifier. If the impedance of the coil Le is very high compared to the resistance of the tube, a change e in the potential of the grid will establish a potential difference between the ends of Le equal to we. If the impedance of the coil L is not so large, the voltage amplification produced will be less than p. The extent to which it will be smaller depends on how large the impedance of Lz is com- pared to the resistance of the tube. Suppose, for the present, that Lis a pure non-inductive resistance equal to R, and let the resistance of the tube be Rp. Then the relation between the voltage amplification and the ratio /Rp is given by the curve shown in Fig. 4. If L is not a pure resistance but an inductance, then this curve is somewhat different but has a similar shape. Now »p the amplification constant, depends on the structure of the tube, and can be made to have almost any grid battery Eg have a value given by OD (Fig: 3); then the current through the tube is equal to DE, if the potential on the plate is that which gives a cur- rent OF when the grid potential is zero. Of course, if the plate potential now be made higher, the current to the plate increases, and we have a curve lying above the one shown in Fig. 3. For the present, however, we shall consider only the curve CEFG. If now an alternating current flows through the cir- cuit A (Fig. 1), alternating po- tentials will be applied to the grid through the input trans- former. These potential varia- tions will be superimposed upon the constant voltage of the grid battery Eg, so that the potential of the grid will oscillate around the point D in Fig. 3, and this alternately increases and de- creases the current in the output or plate circuit of the tube. If the peak value of the alternating potential on 134 Cross-section and rotating inductor of an Alexanderson generator. These are 'the machines the Radio Corporation expects to use for long-distance radio desired value. In most amplifier types of tubes » has a value of about 5 or 6, but the tube can be designed to have a much larger value of the amplification constant. Voltage amplifiers are in use that have an amplification constant equal to 40. But they can be made to iti \ j ie Be

Page 115

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 Le i ee =a special introductory offer and save $7.50. years aA = sama — KK Anan ON Cae Z By: Lie ———, 7 g 7 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 18 key will make other wy THE “AMRAD” INDUC- TION COIL 6 Volt or 32 Volt is almest an exact duplicate of the U. S. Signal Corps coil used in trench c service during the war. It has bake- amateurs in your lite insulation throughout. Its sec- state sit up and take ondary, wound in 29 sections, produces notice. The Amrad 50,000 volts. Rated at 100 watts this coil has an output about 100 per cent. greater than the average 2 inch coil. The vibrator is rugged, steady and non- sticking and designed to give a spark frequency equiv- alent to 100 cycles which means maximum transmitting range on short wave lengths. The 32 volt coil is intended especially for use on farm lighting circuits. When ordered separately this type is $1 extra. To get maximum results with the 6 volt coil a heavy 6 volt storage battery is the best Quenched Gap, carefully operated, yields the secret of long range transmitting on low power. This special gap is iden- tical in design to the heavy 4% k.w. and 1 k.w. Amrad Quenched Gaps now being installed in long distance amateur stations. Not only will this special quenched gap make your transmitter as efficient, forits power, as the more costly equipment but you will be able to send more messages With- out interfering with other statidns. For the first time in the history of amateur radio every induction coil transmitter can now be tuned to comply with Government: decrement and most economical source of current. regulations. The Amrad Quenched Gap is the secret. Prion, Gaede eatin. .2k 6s hee css $28.50 Price, Induction Coil Type........... $12.50 Special Introductory Offer If you have had limited 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, . . . $28.50 ' 6‘Amrad’’? Quenched Gap, ‘* se ane 12.50 $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 money 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 free Bulletin P which contains complete description and operating directions. ? 4 Write at once for short-term trade discount on this combination. D ealers Opportunity No better opportunity to introduce apparatus of such high quality at such low prices will ever be had again. The offer is made especially to introduce our rapidly growing line of ‘commercial type’’ radio apparatus. Address all communications to New York office AMERICAN RADIO AND RESEARCH CORPORATION 29 PARK ROW Factory at Medford Hillside, Mass. NEW YORK 135

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/ Ra HN eEny em eR SEE IGE AIORENE LARD Ft pS u=mm 6 O) Cie Breve) celsye! 7.4 aes 4 Forty-four years is the average span of man’s life in auneice. The great insurance com- panies each year write millions of dollars worth of insurance based upon that proven fact. Most men wear out or break down before their time because of prevent- able disease—because they neglect the warnings of Nature that their Vital Machine is out of order. Constipation, dyspepsia, biliousness, weakness, headaches, dizzy spells, in- ability to remember or con- centrate, hardening of the arteries, varicose veins, high blood pressure, etc., are S.O.S. calls, which MUST be heeded, if you don’t want to land in the scrap- heap of broken-down hu- manity before you even l reach the prime of life. 1 Act NOW—before it is too late Don't go through life, weak, sickly,impotent, un- able to enjoy it or benefit . by the ability en pore Nature has endow you STRONGFORT —always in discomfort or The Perfect Man misery, always the under- dog—with a dead certainty of either slipping into the great army of the ey, unfit or of dying before your time. DON’T DO IT— it isn’t necessary. You can get rid of your handicapping ailments or bad habits and put your human machine in A-1 running order, just as thousands of other weak, sickly, discouraged men have done. Don’t try to get life out of dead dope Pill-feeders never become red-blooded, virile MEN. Quack “remedies” are manufactured for the money they bring their makers. A little tem- porary relief or stimulation—then the inevitable reaction—and you are worse off than before. Méil- lions of dollars are wasted and thousands of lives cut short each year, through the worthless prom- ises of patent medicine fakirs. There’s only one safe, sane, sure way back to health, strength, and energy, and that is Nature’s way. You have within you the greatest health and energy restoring, revitalizing power the world has ever known, in the tremendous forces Nature herself exerts toward upbuilding the human or- ganism, when once you understand her methods and observe her laws. The principles of Strongfortism are based upon my discovery—that internal muscular activity governs Health, Strength, and Life itself. Most forms of disease are caused from the muscles los- ing their power of rapid contraction. As these muscles are responsible for holding the internal organs ‘in position, when they are relaxed, the organs gradually fall out of their place and rest upon other organs, upsetting their functioning and causing almost every known form of disease. Strongfortism gives contractile power to these muscles and quickly makes them normal and so draws the sagging organs back to their position. My whole life has been spent in studying out and developing this Science of Strongfortism. My pupils are located in every civilized country of the world. I can and I will do for YOU what I already have done for them. Send for my FREE book “Promotion and _ Conservation of Health, Strength and Mental Energy”’ will tell you all about Strongfortism—what it has done for others and what it undoubtedly will do for YOU. It Be oad fails. You can practice rect in the jy Sag A of your own bedroom and get all the benefit it. Fifteen to twenty minutes a day will worka wonderful improve- ment in a few weeks’ time. Send for the took ss VRE Don't put it off until tomorrow. IT’S FREE, but you gladly would send me a good-sized check for it, if you knew what it contains. Fill out the coupon and mail with three 2c stamps for packing and postage and I will send you with the ook ¢ & special letter on the subject on which you are most interested. LIONEL STRONGFORT Physical and Health Specialist 1193 Strongfort Institute, Newark, N. J. “s*-- CUT OUT AND MAIL as } COMPOR e---- Mr. Lionel Strongfort, Newark, Dear Strongfort:—Please Bel Aa your book, ‘‘Pro- motion and Conservation of Health, Strength, and Mental Energy,”’ for postage of which I enclose three 2c stamps to cover mailing expenses. I have marked (X) tefore the subject in which I am interested. (11{ 3) . Colds . Insomnia .-Catarrh ..Short Wind .-Obesity ..Stomach Dis- - -Headache orders .-Thinness ..Constipation .-Rupture ..Biliousness .-Lumbago . .Torpid Liver .-Neuritis ..Indigestion

Biglormity. Riveumation 4 opment NAME ...... SED EG TONS S05 oS 0s 5 deine sag occ cs. MAB iictecias eee» OCCUPATION............. ; sede nog neg PEER DN SITIES DOT DEE sg gare i pl eae Ay YT TITY) STATE eee eee eeeee

| of the order of

have an amplification constant many times larger than this value. This amplifying property of the tube is due to the grid, and the amplifica- tion constant depends on the mesh of the grid. The finer the mesh the higher the amplification constant be- comes. At the same time, the grid acts as a sort of screen to the flow of electrons from the filament to the plate, and the finer the mesh of the grid is made the greater be- comes this screening effect. Hence, if we want Fiz. 5. A hook- to increase the ampli- ae ene fication constant by of aresistance in Making the grid of a the plate circuit closer mesh, we at the same time increase the resistance of the tube. On the other hand, the resistance of the tube can be decreased by increasing the plate potential (as will be explained later). When the tube has a high amplification constant, it is therefore, in general, desirable to operate it with high plate voltages. Theoretically there is hardly any limit to the voltage amplification that can be produced by atube. Of course, a transformer can also be looked upon as a voltage amplifier, because an ordinary step-up transformer will step up the voltage; but there will generally be some loss of power, whereas in the case of the tube the A.C. power is amplified. Gen- erally speaking, it follows from Fig. 4 that the best way to obtain large voltage amplification is to make the resistance or impedance in the plate circuit large compared with the re- sistance of the tube itself.

Right Circuits for Amplifying This is different from the case in which the tube is used as a power amplifier, because the power amplifica- tion is a maximum when the external impedance is equal to the re- sistance of the / tube. The amount of pow- er amplifica- tion given by most tubes used in practice is

several hun- dredfold; but -=<-= a= Se vacuum-tube GRID VOLTS amplifiershave Fig 6. Showing how plete been madethat current depends on plate- will gi . circuit voltage and also hh . vow on the grid voltage. The eramplification dotted lines JEH is of severalthou- a dynamic characteristic sandfold. It is perhaps known that vacuum

| tubes will amplify without appreciably distorting the wave form. This is, however, true only if special precau- tions be taken to operate the tube in | the proper kind of circuit. It will, for example, readily be seen by referring to Fig. 3 that if an 136

Popular Science Monthly LEARN PIANO TUNING

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Page 117

April, 1920 a alternating potential be superimposed on the constant grid potential OD, and if this alternating potential is-a pure sine wave, then the current- wave as shown to the right of the curve is not a pure sine wave, but has larger positive loops than negative loops. This is due to the curvature of the current-voltage characteristic, and this is in fact the property that enables us to use the tube as a radio detector. What is good for the radio detector is bad for the amplifier. In order to make a tube amplify without dis- torting, it is necessary to straighten out the characteristic. This can be done by inserting a resistance in the plate circuit. To see how this is done, let us refer to the diagram shown in Fig. 5, in which the potential of the grid can be varied by means of the variable battery Eg and measured with a volt- meter Vg. The current in the plate circuit is measured with the ammeter A. If now the potential of the grid be raised so that the current in the output circuit is increased, there is established a voltage drop in the resistance R; and since the voltage of the plate battery E is constant, the potential difference Ep between filament and plate must decrease. In other words, the voltage Ep and the current in the plate circuit are 180 degrees out of phase. This has the effect of straightening out the char- acteristic, as can be explained with reference to Fig. 6. Assume that the grid potential has a value given by OD, and the potential difference between filament and plate has that value which gives rise to the middle curve CEF. If we now de- crease the negative potential of the grid from D to O, the current in the plate circuit would increase to F if the potential difference Ep between fila- ment and plate remained constant; but, on account of the external re- sistance R, the plate potential Ep drops to a lower value, and the cur- rent, therefore, only increases to the value H. On the other hand, if the negative grid potential be increased, the current in the plate circuit de- creases. This increases the plate po- tential so that the current drops to J instead of to C along the line EC. If the external circuit contains an inductance instead of simply a pure resistance, the effects are somewhat different because of the different phase relations existing between the currents and voltages in the plate circuit. In this case the dynamic characteristic takes the form of a loop instead of a straight line. Suffice it to say here that if the external resistance be made sufficiently large the distortion result- ing from the curvature of the char- acteristic can be reduced to a negligible quantity. [This is the first of three articles by Mr. van der Bijl: the second will appear in the PopuLar SCIENCE MONTHLY for May.] Meat J. Ozment, Dept. 52, St. Louis, Mo. transmission and reception of wireless messages. No BE AWIRELESS OPERATOR LEARN WIRELESS rN al?) yi EARN $1!125TO $200 MONTHLY TRAVEL WORLD FREE OF EXPENSE The Demand for Wireless Operators Far Exceeds the Supply The New York Wireless Institute will make you an operator—AT et peat your — time—quickly, easily and thoroughly. No previous training or experience uired. Our entire Home Study Course has been prepared by Mr L R. Krumm, Chhef Radio Inspector, Bureau of Navigation, N. ¥Y. Experts able to impart their tical and t knowledge to YOU in an easy to understand way, will direct your power 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.: All you will have to do, is to listen. BIG SALARIES TRAVEL THE WORLD OVER Wireless operators receive excellent salaries A Wireless Operator can visit all parts of ranging from $125 to $200 a month and itis . the world and receive fine pay and only a stepping stone to better positions. maintenance at the.same time. Do you 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 land stati or with the Positions as Radio Engineers, Radio In- Commercial Wireless or with the Steam at salaries up to ship Companies. FREE Instruments and Text Books We furnish free to all students, dur- ing the course, the wonderful receiving and en set exactly as prod in ‘theillu: ogy = This is not inate ing Universities, Colleges, Schools throughout the U-B- thro out the . and Rane py Start the Om- but GIVEN to all students com- nigraph, place the phone to pleting the Course. EASY PAYMENTS. A small your ear and this remarkable Oayment down will enroll you. 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City FREE Post-Graduate Course’ & Send me free of charge, your booklet, ‘How to Become an A one month’s Post-Graduate ® Expert Wireless Operator,” containing full particulars of Course, if you so desire, at one §% your Course, including your Free Instrument Offer. of the largest Wireless Schools Ei.5 che tins nesert patie 2 onder City— largest port in the World and the headquarters ; FUMEEO in 0 0. dc ovcvccccesccceesedb esses 6asebebeed so 600% of every leading wae ess and Steamship Company a 4 BENG. own ce ccccacces sepeceenotaadng pausedene .aebacak j City or Town ee Pe . State.... ** ASK ANYONE WHO HAS USED IT” o Brandes Wireless Headset en a Prinies Su- TRIALS = OFFER: it critically for ten days. Then, if ft doesn’t come up to our claims EVERY owner of an should have this 64 mR. a book illustrati and describing the newest DeFOREST de velopments in Radio App%ratus. Contains — valuable information about mr a, diagrams, Unit-Type Receiv- pare with others—for Sensitive- ness, clearness, distancé, Prove for yourself the fine quality. ets, individual instruments, i the “‘ matched tone.” e two complete — with and phragms toned exactly alike, without cabinets and many other strengthen the and pre- features you will want to know about. Send 10 cents in stamps and get a copy for your Radio Library. DeForest Radio Telephone and Telegraph Company amateurs everywhere Send 4c for Catalogue R C. BRANDES, Inc., 32 Union Sq., Room 813, New York, U. S. A. Wireless Receiver Specialists ni- cal echools: and by peotession- “ae 8 Set $7 1393 Sedgwick Ave., New York tame BE AN EXPER TIL A0 Wiress (ESE) Manual Wonderful, new device, guides your A-l0 *,e ° Tae ac, hand; corrects your writing in few About March 15th we will have ready for distri- days. Big improvement in three hours. No bution new Manual and Catalog of standard radio failures. Complete outline FREE. Write | | Viticus insteomente And, feseribing in detail the expense has been spa to make this Wireless Manual complete and up-to-date in every wa a, as to be of tance not only to the amateur, t also to the professional user and experimenter in the most fascin- ating of all modern arts. The size of the Manua) will ne 4%" x 9” and will contain approximately 180 pages If interested send in your name and address and a copy will be sent to you as soon as issued. Manhattan Electrical Supply. Company, Inc. New York, 17 Park Place Louis, 1106 Pine St. wanpeeet wee 2 SHORTHAND Learn in 5 evenings home study; ay te oe by et Ww at a stvorteled, piskonmtpetetion Favor- SeeNe endo ee notes ai confidential diary, Bir dings Fee or business; aid in your god in Army, Navy, co courts, career. U commercial schools; by public ye stenogra- phers, teachers ht got. 1] for bus: le, includin, Lessons, Guarantee Chicago, 114 So. Wells St. San Rat mg 604 Mission St. ] hure with Tes . id. Address : KINGINSTITUTE, EH-188, Station F, NEW YORK CITY ** THERE'S ELE Init” SELEARN A — ELESS-—-——— ——— ee eee, eee cme we 8 co eet em ee EE re ME ce am UD omen om TEACH YOURSELF 333 2r3tne, 2.71008 garni : pan ge Morse or Continental ional —. Pe pong hy I om ye oun ould. Adopted by U. § Govt. and d leading Universities, Colleges and Telograpts OMNIGRAPH MFC. co, Dept. H., 39 Cortlandt St., New York, 187

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PATENTS Write for free booklet Terms Reasonable Highest References Best Results f Send model or drawing for preliminary examination and report as to patentability ALL BUSINESS GIVEN PROMPT AND PROPER ATTENTION WATSON E. COLEMAN, Patent Lawyer, 624 F St., Washington, D.C. INVENTOR’S BULLETIN Sent Without Charge MY FREE BLANK FORM INVENTOR’S RECORD For Disclosing Your Idea SIMPLIFIES PROCEDURE Wit LiAM HMUuLLicAN REG Perce 2 ATTORNEY 392 Woodward Bldg., Washington, D. C. Taare * The Book fe INVENTORS MANUFACTURERS eRe SIXTH EDITION TENTS PROCURED and | TRADE-MARKS REGISTERE Twenty Years’ Experience. Terms on request. ROBB, ROBB & HILL, Attorney at Law Specializing in Patent and Trade-mark Practice exclusively 840 McLachien Bldg., 1336 Schofield Bldg., Washington, D. C. Cleveland, Ohio. Instructions and U.S. 4 “A - : : | D FOR NII EN THIS raRM> 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. | 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 sent upon request. Ask for them,—a post card will do. ANCASTER a AL WASHINGTON, D. C. Originators of forms ‘‘Evidence of Conception.” PATENTS TRADE-MARKS COPYRIGHTS Send for our free book of patent in ion SP Nerlncanee OO 16 S. Broad St., Philadelphia, Pa. DO YOU KNOW EVERY MOVE YOUR ATTORNEY MAKES? “. INVENTORS .— My clients are“immediately informed of every step In the prosecution of their applications. WriteNow PATENTS Send Sketch Office of WARNER I. CUBBERLEY, Patent Attorney, 20 National Union Bidg., Wash. D C. Stoppers and Filters for Undamped Waves NDAMPED waves are so gen- erally used today that amateur and professional alike are becoming interested in ways for selecting a de- sired wave length and excluding an interfering wave. In the last year or so several patents have been issued that describe methods and means for RESPONSE TO INCOMING SIGNAL RESPONSE INDUCTANCE(L) OR CAPACITY(C> J FIG.) TUNING CURVE b y Thomas Stanley ° o! Tells you both the why and the how. and closed core transf CONSTRUCTION OF INDUCTION COILS AND TRANSFORMERS, Curtis. Full of tes and instructions. ess work. Open sformers are both en up ‘ora practical in- book on the whole subject this one is hard to beat for the Price, postpaid. 25 cents. POPULAR SCIENCE MONTHLY 225 West 39th Street New York SECURE A PATENT, send for Our Guide Book, HOW TO GET A PATENT, sent Free on request. 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. t RAMOOLPH & CO.) me 130 F St, N. W, Washington, D.C.) cart. csosntn PEATE eee eee ae ee ae ee IF YOU HAVE AN INVENTION and DESIRE TO LEARN HOW TO ‘ observed, it will 138 2 Popular Science Monthly WAVE LENGTH OR ~_ FREQUENCY FIG2 ~ Showing how the intensity of an incoming signal depends on tuning of the receiving set discriminating against wave trains of one range of frequency in favor of trains of anotherrange. Some of these methods are very complicated and require considerable accurately con- structed apparatus, as is the case of the method described by G. A. Campbell in United States Patent 1,227,118. : It is amazing, however, how much can be done with a simple tuned circuit, formed by a coil and a con- denser, if one fully understands its operation. Every radio enthusiast knows howto tune such a circuit by varying either the inductance or the P capacity. When listening to a con- tinuous wave sta- : : — : "Tr DETECTOR tion he finds that as he varies L or C his set passes = through an ad- :iG3 RECEIVING CIRCUIT justment where S$ : the response is TO greatest. The DETECTOR curve showing this jc change is the fa- — miliar one of Fig.1. If the tuning is fixed in some ad- | justment, and req etectrica signals of different EI U ALENT OF wave lengths are be found that the t response goes ¢ through _—varia- — tions of intensity ® like those of Fig. 2. Of course, to test this, one should have an oscillator FIGS — ELECTRICAL the frequency of EQUIVALENT OF which he may __ FIe@ change continu- Citcuit diagrams that help to show why tuning the receiv- ing set is important ously without changing the out- put; for the curve of the figure assumes that the incoming signal is always of the same intensity when it reaches the circuit under test.

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eT ESD April, 1920 We make use every. day of this fact that a definite tuning corresponds to a definite wave length. What is its explanation? In the tuned circuit of Fig. 3, a voltage is induced in the coils by the current that the incoming wave sets up in the antenna. As far as con- cerns the tuned circuit and the de- tector, the effect is the same as if a generator of the signal frequency were connected to the coil as shown in Fig. 4. It is easier to understand. what happens in the circuit if in our minds we separate the resistance of the coil S from the inductance. To help in so doing we sometimes draw the coil in two parts, as in Fig. 5, one part a resistanceless inductance L, and the other a non-in uctive resist- ance R. The voltage required to send an alternating current through an in- ductance is always just opposite to that required to send the same al- ternating current through a condenser. When the inductance and the capacity form a circuit tuned to the frequency of the alternating current, then the ACRO, rt ae Re Jy as mie Pin oe A AXIS OF TIME ON sits Tramace = ACROSS C VOLTAGE OF GENERATOR 3% 7 = CURRENT. FLOWING THROUGH R.LAANDG FIG6& VOLTAGES AND CURRENT IN A TUNED CIRCUIT This plot shows why a tuned circuit gives a maximum response. No voltage is required to send a cur- rent through the inductance and capacity. Only the resistance re- quires a voltage to give a current voltages required by the inductance and the capacity are not only just opposite, but are also always just equal. The result is that it doesn’t require any voltage to send an alter- nating current through an inductance and a condenser, connected in series, if they are tuned to the frequency of the source of the voltage. Voltage is then required only to force current = * through the re- [ oe sistance of the a L a circuit. In Fig. 5, then, all the fo voltage of the yS' ze generator is ¢syof2 he? effective in TUNED CIRCUIT sending an al- AS A SHUNT ternating cur- A tuned circuit rent through used as a by-pzss ’ the resistance; and the current that flows around the circuit of R, L,and C is just that which the whole voltage of the generator could send through the resistance alone. If we obtained a picture on the moving film of an oscillograph of the values of the voltages and the current in such a tuned circuit, it would be like Fig. 6. Pre-eminence of American Inventions Telephone F the epoch-making inventions of the world during the last half century, more than fifty in number, Americans are credited with thirty- five, which include the Telephone, Typewriter, Cash Register, Incandescent Lamp, Talking Machine, Electric Furnace Reduction, Electro- lytic Alkali Production, Transparent Photo- graphic Film, Motion Picture Machine, Button- hole Sewing Machine, Carborundum, Chain Stitch Sewing Machine, Single Type Composing Machine, Continuous Process Match Machine, Chrome Tanning, Disk Plow (modern type), Welt Machine, Electric Lamp, Recording Adding Machine, Celluloid, Automatic Knot-Tying Ma- chine, Machine for Making Barbed Wire, etc. Recordi: Adding Machine Motion Picture Machine America leads the world in invention and must maintain its supremacy in the future. Talking Machine Electric Furnace Reduction To the Man With an Idea I offer a comprehensive, ex- My experience and famili- perienced, efficient service for arity with various arts fre- his prompt, legal protection and the development of his proposition. quently enable me to accurately advise clients as to probable patentability be- Send sketch, or model and f,,. they go to any expense. description, for advice as to cost, and search through prior pertinent United States Booklet of valuable infor- patents. Preliminary advice ™@ton and form for properly gladly furnished without disclosing your idea free on charge. request. RICHARD B. OWEN, Patent Lawyer 6 Owen Building, - - - - Washington, D. C. 2776D Woolworth Building, - - New York City 139

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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. ‘I lis explains our methods, terms, etc., i. regard to Patents, Trade Marks, Foreign Patents, etc. If you are a reader of SCIENTIFIC AMERICAN ou are probably aware of the ~ 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 rulings 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, IIl. Hobart Bldg., 582 Market Street, San Francisco, Calif. ee P EPP RSORU CECE SEOR ERE CE SUCRSOS EEC EOE GEESE EEE SS SE Ga! PATEN TS pedegebaerecee Trade Masks Send sketch cr mece! teogemreerhitg for actua) search and report. Write for Bcck- let cf tnstructions cy patent pr: actice atid procedure. Prempt personal service Geo.P Kimmel Patent /awye: 39-E Loan and Trust Building, Washington, D.C. ivacedWecaetabinne JIPERPECP PAVED EVER EL ER ee aae Perfect hearing is now stored in every cenditien of he ) ness or defective pening from * causes such as Catarrhal Deaf- ness, Relaxed or Sunken Thickened pee, Roaring Whelle part ny Beene olly or i ay royea Drums,Di m Ears, etc, medicine but effectivel ee in oR oe tem defective in the ianarekoar drums, They are Seaoie which the wearer easily fits into the ears weer ec pnaetcre pene ‘or our e n . NESS, giving you full cok a hag and ne obi, WILSON EAR DRUM CO., Inc ted 554 Inter-Southern Bldg. LOUISVILLE, KY. The reason we use a tuned circuit to supply a detector is apparent at, once when we remember that the detector is connected across the condenser, and that across the latter there will be the greatest voltage when the current through it is greatest. As we have just seen, the current through the entire circuit is greatest when tuned to the frequency of the voltage source. If an inductance and a condenser have the proper values to form a tuned circuit like that ‘ L: of Fig. 3, and to give a max- Qs 7 imum response 2 J? fora signal of ma frequency f,, CONNECTIONS FOR TESTING then we know The plot may beob- that this coil tained by calculation and condenser ls Fis apace Pigg in series act to circuit shown above waves of fre- quency f;, just like a small resistance. If connected as in Fig. 7 they will form a short circuit to any waves of frequency f, that we try to send through from terminals 1-2 to terminals 3-4. If wave trains of this frequency and of some other, as fz, are impressed on the left-hand terminals, only the train of frequency fz will pass through, for the other will be short- circuited or ‘‘by-passed.”” It is only for the single frequency for which L and C are tuned that the circuit will act like a short- circuiting re- sistance. For frequencies above or below C it will be less 21 Ta and less effec- tive as a by- hin esha sabia 4 e tuned. circuit is 180i , 28 18 connected to stop the shown in Fig.8. flow of current of This relationis its own frequency obtained by — connecting a generator, as in Fig. 9, to one side and measuring the voltage on the other pair of terminals. The voltage impressed by the generator must be kept constant while its fre- quency is varied. An inductance and a condenser that have been tuned to a definite frequency may also be used as a “stopper” in series with any desired portion of a radio circuit by connecting as in Fig. 10. Notice that the condenser and inductance are es in parallel with each other, but that the com- bination is now in series with the circuit that it is to protect from waves of its own FIGS SHOWING TRANSMISSION frequency. This THROUGH GROUT OF | cireuit: aso has eo the character- shunts cat wavesof ” istic of Fig. 8. its own frequency To see the reason we look back to Fig. 6, and remember that if a condenser and an inductance are car- rying the same alternating current the “140 FIG.10 STOPPER CIRCUIT Popular Science Monthly CAN YOU think of a simple, practical idea that will fill one of the many ree uests we have on file for new invene tions? It may mean a fortune for you. Thousands of things are needed RiGut 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, €00. A postal will do— it is free. PATENTS We help our clients, SESS Mf wonnso none others possess. — For SALE F REE Advice free. In INVENTION A d book atone, MANUFACTURING ciated SUPPLEMENT. Published for the man with an idea INDUSTRIES, INC. Send for free sample 201 Patent Dept., copy. One year’ssub- WASHINGTON, D. C. m 6cription 50c. fe Book on os ¢ one 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. It tells 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 patent matters. Write today for your FREE BOOK. A A OY LT ML ll ll le A Al si This Interesting Free Book shows how you can become a skilled player of piano or organ in your own home, at one ee usual cost. Dr. Quinn’s famous ritten Method is endorsed by leading usic! ians and heads. of State Spocryeteriee. ag 26 years. Play chords at 0 and complete piece in every im sons. Scientific py easy to ‘understand. a lustratd. For begin- ners or teachers, old or - All m Write today for 64-page ! flow te Stody Music’ ", M. L. QUINN CONSERVATORY, Studio ZD, Social Union Bidg., Boston, Mass. America’s Coming Biggest Industry. Big . demand for Combination Riggers and Motor Men. Earn $75 a week and up. _ Complete instruction. N Aeronautical t. W r aan Emenee ——— ar planes for ational Airplane School, S12P E. Sth, Kansas City, Mo, gran \e Aa @ ww Publishes BO l cash art as- b - signments MAGAZINE lessons an articles on Cartooning, Designing, Illus- trating, Lettering and Chalk-Talking. Criticises amateurs’ work, Full of in- formation for artists and art students. Satisfactory or money refunded. 20c a copy, $1 a year. Send $1 NOW, Thrift Stamps Taken G.H. LOCKWOOD, Editor, Dept.595 Kalamazoo. Mich.

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April, 1920 voltage impressed on them must always be opposite. Of course, we can turn this around and say that if we impress the same voltage on a con- denser and on an inductance the cur- rent in the condenser will always be opposite to that in the. inductance. Now, in Fig. 10 the same voltage must be impressed on both, since they are in parallel. Thecurrent in the condenser is then opposite to that in the induc- tance. If the frequency of the source of voltage which is connected to terminals 1-2 is that for which the circuit is tuned, these currents are not only opposite but always equal. Ata junction point like b, where the cur- rents join to flow outward to terminal 3, the two currents will always just neutralize each other. In other words, FIGH ONE FORM OF CAMPBELL “FILTER” A very efficient circuit for passing waves of preassigred frequencies no current of this frequency can flow along the wire 1-3, and hence none from terminals 1-2 to 3-4. In actual practice, however, the inductance has some resistance, and so the currents in the branches do not exactly balance. The radio operator who understands these circuits can do all sorts of stunts with a vacuum-tube oscillator or modulator, picking up any harmonic frequency that he may select. A very effective circuit for cutting out a given range of frequencies may be built by combining shunt-and-series tuned circuits in the manner that G. A. Campbell describes in his patent. He connects a number of similar ele- ments as in Fig. 11, and by so doing obtains an immense advantage, which is shown by the characteristic VOLTAGE curve of Fig. 12. i Se This “filter,” as he calls it, will WAVE pass not only a LENGTH singlefrequency, FIGI2 TRANSMISSION : Lh no but as wide a FILTER range of frequen- The circuit here gives cies as one the flat-topped turn- wishes; and all ing curve as shown get through with about the same intensity if their sources have the same intensity. Such a filter is of particular use in dealing with telephony, whether wire or radio; for the human voice requires ‘for its intelligible transmission a con- siderable range of frequencies. The inventor shows a number of other forms of filters, but all require calcula- tions the mathematics of which is be- yond many amateurs. This need not bother the amateur much, however, for he can obtain good results by using the convenient circuits that are ex- plained above. Ce i ATENT S Cooviienrs fe) AA Ca SPECI AL OFFE FREE OPINION AS TO PATENTABLE NATURE Before disclosing an invention, the inventor should write for our blank form ‘Evidence of Conception.’’ This i} should be signed and witnessed and if returned to us to- A gether with model or sketch and description of the inven- | tion, we will give our opinion as to its patentable nature. Hi | Our Three Books Mailed Free to Inventors Our Illustrated Guide BOOK HOWTO 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 Qur 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. ° 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. But to do this in some cases requires time and labor, and while you will sometimes have to wait, we will have to both wait and work. 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 commendation 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 and Chicago Offices Owing to the growth of our business we have established for the benefit of our clients Branch Offices in New York City, Philadelphia, Pa., Pittsburgh, Pa., and Chicago, Ill. 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 business in all its branches. Highest References—Prompt Attention—Reasonable Terms Fea VICTOR J. EVANS & CO. HI Nom titi Patent Attorneys New York Offices i Philadelphia Offices Pittsburgh Offices NI 1007 Woolworth Bldg. 135 S. Broad Street 514 Empire Bldg. \ i Chicago Offices, 1114 Tacoma Bldg. y a ih Main Offices, 760 9th Street, Washington, D.C. || Gentlemen: Please send me FREE OF CHARGE your books i, as described above. ‘lf i HM ee anion “a Ce ce 2S SS) ee

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April, 1920 An Air-Pressure. Grease Supply for Garages O one enjoys the job of cleaning out the grease and hard oil that gets into the transmission-case and the differential housing, and one man avoided it by devising a grease sup- ply that wes always on tap, with good air-pressure back of it. An old self-filling gas-tank, the kind that may be replenished with chemicals when needed, was used for the air and grease chamber. This had been pro- vided with a removable cap at one end, held in place by two bolts, as shown in the sketch, and through which the grease was supplied to the tank. At the bottom, as shown, a quarter- inch hole was bored and fitted with a four-inch length of gas-pipe, which in turn was connected with a length of INLET VALWE5 PRESSURE TUBING >\ - 4 ,REMOVABLE a ord GAS, TANK (ie ( | au Kr Bx: RRR RRR (@) 5

Se. va “a NOZZLE7 Rouer, SKATE WHEELS

Showing how en old gas-tank formerly used for illuminating purposes can be converted into aa air-pressure grease-gun pressure hose. At the other end of the hose, a long nozzle was also connected, and had in itself a pet- cock for turning off the grease when desired. This long nozzle was made of brass tubing, rolled down to the shape shown. The pet-cock was of the wedge variety, and was screwed to the end of the nozzle, being placed between the nozzle and the hose. Another hole was drilled through the side of the tank, near the top, tapped, and an old tire valve screwed in for the air intake. In use, the head of the tank was removed, a gallon of hard oil put in, and puddled to give it a tendency to run and keep at the bottom, the head replaced, and air driven into the chamber by applying the end of the air hose to the tire valve. From thirty to eighty pounds pressure was found necessary, depending upon the viscosity of the grease used. Then, by simply turning the cock in the end of the outlet line, grease was delivered at any .point in a constant stream. To increase its usefulness further and to save time, the tank was mounted upon a truck, with the wheels from an old roller-skate for the mount- ing. ' In refilling, and to prevent wasting grease when the cap was removed, the core of the tire valve was loosened, letting out the extra air, before the cap was taken off, preparatory to putting in more grease. The tank was wheeled to the place to be used and then tipped upon end, forcing all of the grease to the bot- tom.—DALE VAN HORN.

A, yy WZ

== ZL € = Things That “ Bigger Pay | Will Bring You | You want these things and probably many others, so why don’t you double and treble your pay? You can do it. With double and treble the:amount you are now earning you can go to the bank each pay day and put away a sum of money for a “rainy day,” or Ae that can be used for profitable investments or building your Ht) own home. Bigger pay would enable you to own an automo- | bile and to get many pleasures out of life that you cannot now afford. To be able to go to the bank each pay day and steadily build up a bank account without missing it is alone worth any effort it may take to increase your earning power. Then think of the things you want that are not pictured here. Whether you ever enjoy those things depends entirely on yourself. Every day you see men around you stepping up into better jobs and drawing bigger pay. It isn’t a question of “how do they do it?” You know they have trained them- ? selves to handle the jobs ahead Don t Dodge GQ sof them. The question is “WHY Better Job Braue He on at e things tha er pay wi etter Oo bring you so why not decide NOW | Promotion and better payis up to prepare yourself for a better i to you and not the boss. The job and better pay? li big pay checks go to those who can think, act and do things AMERICAN SCHOOL for themselves. Training will make you a master of your OF CORRESPONDENCE work and place you in the job Dept, G-754, Chicago you want. There are no two r¢

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ways about it; while you ignore yeep ee the benefits of training youare _...Higt' Schoo! Graduate ing a better job. Without “Pelephone Eng a interfering with your work you = “:Automobile Engineer can prepare for bigger payright <Alrmpiane Mechanic” in your own home—after sup- ““Banitary Engineer” per in some of the hours you “Heating and Ventilating now ywaste. The thousands ... Master Plumber who have marked and mailed — ‘Structural Encincer the Coupon to the right have “Shop Superintendent doubled and trebled their pay. ee That is just what you Cando—SO —Name reeset doastheydid.SendtheCoupon. caress

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fate i. Sips edi ea “A ns STOR PETIT SSIS If the t test should come to you tonight to fight for your life or the safety of a loved one, would you know how to strike an effective blow and put the weight of the body behind it, or to cripple your opponent with jiu jitsu or bone-breaking hold? Isn't tt a fact that you are not ready? I will teach you how at my risk. Who wants to learn boxing at homer If you remonstrate with a bully for striking a smaller man, and he turns on you, can you hold your own? Wouldn't you like to? If you are walking with your mother, sister, or best girl, and some one passes a slighting remark, or uses improper language, won't you be ashamed if you can’t take her part? Well, can you? Less than 2% of the men and boys in this country know anything about the art of self-defense. Only 2%of our trained athletes know how to box. That means when someone says, “Come put on the gloves,” less than 2% are fit and ready. Wouldn't you like to learn how to box? Wouldn't you like to learn easily and quickly—right in your own home—at less than half the cost of a single term of lessons by the old method? I have developed a unique “shortcut” method of teaching boxing. You can learn the fundamentals in 6 lessons, and can outbox older and stronger opponents after two weeks’ study. My original method has enabled me to teach professional boxers difficult blows and guards they could not learn by the old method. Professor Mike Donovan heartily endorsed this “Shortcut” method and helped me prepare the lessons I send you. Boxing instructors and Y.M.C.A. physical directors are taking the course to use in their own work, and are urging their pupils to take it to save time and money. I start you with movements you are familiar with—holding out your hand for a coin, the breast stroke in swimming, etc. The first thing you know, I bave you striking correct blows, putting weight and steam behind them, parrying blows, duck- ing, feinting, ete. I teach you the rudiments in front of your mirror before you face your first opponent. When you finally go up against an opponent, you know how to hit, what to expect in return, and how to guard against it. It’s almost unbelievable. But you can find out whether it’s so without paying any money: I will send you my course on approval—that’s my way of overcoming your doubt. The cost is less than you would pay for a single term of lessons. I will include instruction in three rounds of shadow boxing, eight bone-breaking and jiu-jitsu holds, eight effective standing wrestling holds and guards for use against violent attack, a set of daily exercises to keep you in good physical condition, and also a free copy of Mike Donovan's book on boxing blows and guards. If, after five days’ examination, you do not want the course, you can send it back to me and no questions asked— If you want to keep the ceurse, the Special Home Study Edition is only $5, instead of the former price of $10. But you needn’t send any money yet—simply mail the coupon for a free trial to the Marshall Stillman Association, Suite F-4, No. 461 Fourth Avenue, New York. _—_— ee Free Trial Coupon — — — — — Marshall Stillman Assn., Suite F-4, 461 Fourth Ave., New York You may send me on five-day approval your complete Course in Boxing, including five “Shortcut” or Subconscious Boxing Lessons, one set of daily exercises, three rounds of shadow boxing, eight bone-breaking holds and releases, eight holds in standing wrestling, and a free copy of Professor Mike Donovan's Book, “The Science of Boxing.” I will either return the course, or remit $5 in full payment within five days after its arrival. ee Sia Ba bap nies Saisie spk Loc dp onan 6 epee EE, EEE LE ay Ne a ee Cleartone Phonographs $4.00 to $200.00 Retail —=—=—= Motos t1 $13 35 Pe Ete oooh Tone mot nd Re: roducers $1.30 to $5.75 t. M bo °'90e 90c each. Records, "Needles, See hire Points and Parts at reasonable pri Write for our 84- logue, the only one of it kind in America, aaa 33 i different styles of Ta’ ae — ines and over 600 different Phono- it LUCKY 13 PHONOGRAPH COMPANY Export Dept. 46G, E. 12th Street, N.¥., U.S. /. Cat ont this ad and mail it to us, with your name and address (no money); and we will send Las i A arias KARNAK RAZOR by return mail, postpaid. the razor for 30 days FREE; then if you ike tt it pay os $1.85. If you don’tlike it return it. SEND NO _MORE COMPANY, Dept.397 St. Louis, Ma, Convert Your Bicycle Into a Motor-Cycle by using a Steffey Attachment. Fits any wheel. Easy. to attach. Write at once for special low prices. Agents wanted. Send stamp for circulars. STEFFEY MFG. CO. Dept. S, 5025 Brown Street, Phila., Pa. a HIGH FRE Sa oe APPARATUS, ITS CONSTRUCTION ND PRACTICAL APPLICATION By Thomas Stanko Curtis. The most comprehensive and thorough work on this interesting subject ever produced book is essentially practical in its treatment and it constitutes an accurate record of the researches of its author over a period of several years, ~~ nu which time dozens of coils were built and experimented with. 248 pages Fully illustrated. Price, $2.50 Book ment Popular Science Monthly 225 West 39th Street, New York ~and pointed teeth on Popular Science Monthly What You Should Know When Working Hard Wood HERE are few car- penters whose lot it is to handle nothing but soft woods throughout life, and it is of interest to see in what way the hard wood differs from the soft. In the first place, hard wood cannot be shaped with dull tools, and the harder the wood in use, the sharper must be the tool. Thus the first essential is well filed saws and keen edges on planes andchisels. You Will Need Special Tools The tools, are special; that is, the old-fashioned wide- mouthed planes, with their chatteringirons and cutters, will not act on timber the fiber of which is dense, lengthy, or er- ratic. Therefore iron and composite iron- and-wood planes will be found to work faster and better than the old beech planes. Trimming in hard wood has its difficulties, and must be done without too much haste. For instance, with jambs, especially with the inside Y%-in. jambs in stud partitions, the most common difficulty met is the ficulties, and it ‘twisting or bending of the piece, caused either by imperfect drying or by the pieces warping from being brought from a dry, warm atmosphere into the dampness of a . newly plastered building. Often, in this case, the worker finds it almost impossible to draw the face of the jamb straight without splitting it, but Pointers on Overheating ATCH for steam at the radiator Cap, as it indicates that the en- gine is overheating, a condition that may result in serious damage to the engine if not attended to in time. Overheating burns up the oil, and causes friction, loss of power, scored cylinders, broken parts, and possi- bly a bent crank-shaft and broken crank-case. The knocking of an engine is usually more pronounced on a hill, but it may occur with the engine under load. This defect will take place with the spark retarded, proving that it is not a spark knock. It may be due to glowing carbon, unless the carbon has recently been removed. To remedy this condition remove a spark-plug, and if its end is found to be badly carbonized it is probably a carbon knock; but a knock accom- 144 By G. F. Trimming hard wood has its dif- deliberately and without haste Collins it can be easily done if a few saw kerfs are run diagonally across the back of the jamb to a depth of about half its thickness. A similar treatment is applicable for twisted or warped casings; but when molded the kerfs should not be so deep as to show on the face, which would effectually destroy the piece. Maple, oak, hazel, white mahogany, butter- nut, basswood, hard yellow pine, and ash all show this ten- dency. How to Nail Hard Wood Another important factor in hard wood is nailing. Even with wire nails, it is safest to bore the stuff with a drill, especially at the ends, where its brittleness makes it most liable to split, and in nailing it is well to have the stuff solidly placed against the plaster furring, or what- ever may be behind it, in order that it may not jar under the impact of the hammer. The use of a small pointed nail-set is desirable in hard wood; or at least the point of the set should be less in diameter than the head of the nail, as a set too large will split out the stuff. All nails should be driven through the thick part of the stuff and not through the thin; if it is too thick, it should be bored first, but when nailed through the thin portions it is liable to spring out and split when working under atmospheric changes. must be done the Automobile Engine panied by steam at the radiator is generally-due to overheating. Overheating is usually shown when the engine runs with the switch open or in the “off” position. This may also be due to the pres- ence of carbon, and the spark-plugs should be examined. To stop an engine running without the spark throw out the clutch, drop the shift lever into high gear, apply the foot- brake gently, throttle down the en- gine, and let in the clutch. This will stall the engine. Sometimes scale from water and rust clog the radiator and prevent the water from circulating properly Bits from the rubber hose also get inside the cooling system and retard the flow of water. Give the radiator a thorough clean- ing and probably your overheating troubles will disappear. 6-228 — ae ee

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We Rear SA eS Ss

April, 1920 Holding Device for an Automobile Gate HEN the front wheels of an automobile rock a gate flat to the ground, the top of the gate is caught by the catch until the rear wheels of the car pass over the gate. Running over the springboard L releases the catch C so that the gate rocks back into place again. Pressure

You don’t have to get out of tne car to unlock and push eside this gate. It cpens and closes automatically on L moves the angle-piece A, drawing the wire R taut and the catch C back. The gate pivoted be- tween two posts is normally held up- right by means of a counterweight W. The gate must be pushed down by hand for a horse-drawn vehicle, but it is automatically closed by passing over the springboards.— EDWARD R. SMITH. A Magnetic Lifter for Engine Valves HERE a great many valves have to be removed from cages and enclosed ports, a magnetic valve- lifter will prove of real value. The core consists of a long soft iron bolt about 10 in. long by % in. stock. Saw the heads off a large spool and run them on the bolt as shown, flattened surfaces of the heads facing toward each other. Wind the bolt with several layers of heavily insulated No. 18 copper wire. SOFT 1PON BOLT

SPOOL END e BRASS HANDLE COVERED WITH

Q Eo" FITS BETWEEN NUTS

In garages, where many valves have to ' be ground, the magnetic valve-lifter is a time-saver. It is made from scraps It is well to shellac each layer of wire before proceeding back over.it with the next layer. Fill the space between the spool heads, and when completed wind with electric tape to keep out the moisture. Then run on one end nut until it forces the spool head in place against the coil. Bend the brass Sargent Framing Squares

ARGENT Steel Framing Squares are the cnly squares which will calculate the lengths! and cuts of Hip, Valley, Jack and Ccmmz-n rafters, without any figuring on the part of the carpenter. Sargent Framing Squares are made of the finest to<1 steel and tested for trueness and accuracy. Made in nine dependable finishes. Ask for a Sargent Framing Square No. 500 series va

ITH the first stroke of a Sargent Auto-Set Bench Plane the carpenter knows he has a superior plane in his hands. Its rigid and true-cutting blade, its lack of chatter, its quick and easy adjustment for coarse or fine cuts, all recommend it to expert workmen. In addition is thé special Auto- Set feature which permits the blade to be removed, sharpened and re- placed in exactly the same position and for the same depth of cut, without any readjustment what- ever. the six sizes. SARGENT & COMPANY Send for catalog showing Hardware Manufacturers 50 Water Street, New Haven, Conn.

. ar paooss 1 oe : z ee - " -

LOCKS Ame

HARDWARE

electrical,rope, air- plane, piano, pipe- organ, flat, hoops, bale-ties, tacks, nails, barbed-wite, concrete re-inforev- ment, * ngs, _net- ti wi: ~ ng. re Sones, — Ss “a res and rail Illustrated Books Describing Uses, FREE American Steel & Wire Co. *-®=**s:,7.2.2°5.4.

Tulare 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 Col only one of its kind in the, West. Day and night sessions—enroll any-'time. Write for FREE catolog, a = card will do. FINLAY ENGINEERING COLLEGE 1002 Indiana Ave. Kanszs City. Mo.

Pilliod TOOL CASES EXCEL Machinists, Tool Makers and Carpen‘ers ind them most satisfactory in construction, appearance, service and price.

Booklet describing 20 styles on request. The Pilliod Lumber Co. Dept. A, Swanton, Ohio 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. For anything you want in Asbestos, turn to KEASBEY & MATTISON COMPANY Dept. S-4. AMBLER. PENNA.. U.S. A.

145 Owners of the world’s largest Asbestos Mines

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Pliers No. 1950 Especially made for elec- tricians, but valuable for heavy use of any kind. Have side cutters and can be used as hammer or wrench. Pliers No. 999 A combination tool for handling pipes, wire, or for use as a hand vise. It is strong and heavy enough to serve as a hammer. “No Pinch” grip, and handles shaped to give you the strongest grip with the least ex- ertion. si aoe cell OB le he Booklet on Request “Red Devil” is the Expert ' Mechanic’s guide to known i quality in Pliers, Elec- trician’s Tools, Hack Saw Frames and Blades, Auger Bits, Chain Drills and other uf Hand Tools, all of a class Ue with ‘Red Devil” Glass 4 Cutters, the biggest sellers te in the world. “Red Devil” Corrugated Lock Washes have 6-point contact; they hold fast. | SMITH & HEMENWAY CO, Inc. 264 Broadway, New York, N. Y. Factories: Irvington, N. J. ee $ : om Fee a an RO SERIA handle around as shown, slip over the bolt end, and secure with a second nut. A coat of shellac over the whole magnet will help to preserve it as well as add to its appearance. Connect to electric current, hold the bolt head over a valve head, and the entire valve can be lifted out of the seat by pulling on the handle of the magnet. With sufficient current this magnet can lift several pounds. Winding the handle with tape will further protect the operator against any possible shock from short-cir- cuiting.—L. B. ROBBINS. Revolving Tool Drawer for the Mechanic DRAWER cannot usually be pulled out more than half its length with safety, especially when it contains tools or other heavy objects. The back part of the drawer is there- fore of little use or is difficult to reach. A mechanic has devised a combina- tion that overcomes this difficulty. As shown in the illustration, there is first =. i SSE IT SS S = Ss Wa SS REVOLVING TRAY Simply revolve the drawer until the partic- ular tool you want comes under your hand constructed a sliding drawer frame without a bottom, having a narrow board nailed across both top and bottom at the middle. The hexagonal set of compartments is fitted inside the sliding frame, so that it will revolve freely about a long bolt that passes through the center, and also through holes in the boards nailed across the top and bottom of the sliding frame. A washer made from a piece of 1-in. board fits beneath the revolving part in order that it may turn freely. It will be necessary to pull such a drawer out only six or eight inches, and then to revolve the inner section until the proper compartment appears. This arrangement is particularly designed to hold bolts, nuts, screws, rivets, and small tools, and can be fitted beneath a work-bench top without occupying space otherwise needed. 146 Popular Science Monthly - 7 ENGINES Save $15 to $500 Built in the Largest Exclusi e Factory in ways get delivery from WITTE, eheanae for the price. for latest catalog and priceof WITTE Engines with BOSCH Standard Ignition I can furnish you a Stationary, Portable, or Saw-Ri tfit—Kerosene or Gasoline—or a ptiny, be Saw with all latest other factory | WITTE ENGINE WORKS - Kansas » Mo. ote Pittsburgh, Pa. Se tba. 2225 Eupire Bldg. IF YOU HAVE METAL TO CUT YOU NEED DROP-FORGED BARTLETT Gon pound Lever SNIPS $2 to $6.70 Made of high-grade Crucible Tool Steel, accurately tempered. Cuts metal up to 18 gauge easily. 7-inch size just right for household use. 7-inch, stamped, $2.60. 8-inch, forged, $3.00. 10- inch, $4.50. 12-inch, $5.80. 14- en inch, $6.70. Your dealer has them a orcan get them from his jobber. If he will not we moras eee , in U.S. . trices. - DER ON REQUEST BARTLETT MFG. CO., 31 E. Lafayette Ave., Detroit, Mich TOOL CASES Machinists and Toolmakers Write for our booklet showing the best built and most practical selec- of Too s on the market. e ship direct from factory and tee please you or refund money. AGerstecriSens 60 Columbia St... Dayton, Ohio CHARGE Big Profits For You j lany HB owners are clear- Auto Stora ing’ $100 to $250 BATTERI Some even pon This 500 watt Charger rec es 1 to 8 batteries at once with current cost of 10c to l5c per battery. Au ists pay ‘75¢ to $1.50. $15 Pats This Mepey Maker in Your Garage Balance in easy monthly payments. ings should eabi Writefor fullpar- tiealars or ond $e heat 1 payment with trial ° means lost profits. Order fromthisad. No risk. Absolute M Back Guarantee. 7 * Do it today. , Hobart Brothers Co., Box S42, Troy, Ohio ¥3 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 grinding. ste Simple. economical, durable 1 sandsin use. liy guaranteed; 30 days trial Write at once for Free book and low price. OTTAWA MFG. CO., 1801 Wood St., Ottawa,Kas. AUTOMOBILE IGNITION, VALVE TIMING, SELF-STARTING AND LIGHTING, INCLUDING FORD SYSTEM A manual of the care, adjustment and repair of the auto- mobile electric system, covering both the ignition and elec- tric self-starti systems, It can be easily understood by one who is not at all acquainted with electrical principles, for the subject is taken up progressively from the most elementary descriptions of electrical circuits to the most complicated starting systems in easy The chapter on valve timing is a remarkable feature. It gives information on the proper valve adjustments for a great number of modern cars. Price, postpaid, $1.40 Book Department, Popular Science Monthly, 225 West 39th St, wie ee ee ete New. York Aj

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The iit Nitereitaen | Stor | a —F ver Know that away back in1867 Messrs. J. R. Brown and Sharpe brought from Paris an idea which resulted in what is now the most necessary tool in the mechanical world _| —the Micrometer Caliper? Ei, ee That today there are over | 100 different types of Mi- crometers—the result of many years of study and improvement? This information is told in a most interesting way in our | latest booklet, ‘“‘The Microm- # | eter’s Story.” After reading } | it you will understand why BROWN & SHARPE Machinists’ Tools } | are recognized throughout ‘| the world as the machinists’ . | ¥ favorite. If you are interested we will send you a copy of the booklet along with our catalog No. 27 which lists over 1000 tools. || Brown &SharpeMfgCo | | Providence, RI. | ae | 4 | - Ea Consider the Top of Your Automobile HEN the top of your car is neg- lected it becomes shabby in a very short time, detracting from its ap- pearance and value should you wish to trade itinforanewcar. Thisis abso- lute carelessness, because with a little consideration and care the top can be made to stand up as long as the body or the running gear. Never fold the top when it is wet, for there is always the possibility of mold or mildew attacking it, and this results in rapid deterioration. When the car is laid up for any length of time, the top should always be left up, to preserve its shape. Use the slip cover whenever the top is folded. Everyone knows that the vacuum There may be a fine car under that shabby automobile top, but the out- sider isn’t likely to get that impression created at the rear of the car when it is in motion fills the uncovered top with dust and dirt. Mohair tops should be cleaned by brushing thoroughly with a whisk- broom and eradicating the spots with a sponge, warm water, and castile soap. A chamois wrung dry will finish the job by taking up the excess moisture.—R. L. PRINDLE. A Combined Switch-Key and License-Holder NSTEAD of going out automobil- ing without your driving license, LICENSE nine times out of ten, why not keep it in a place where you could not drive and be without it? An empty cartridge sol- dered to the switch-key makes an ideal place in which to keep the license. Solder an emp- ty metal car- tridge to one side of the key, opening uppermost. Then roll the license into a little spill, and slip it into the cartridge, closing with a cork stopper if desired. The license will always be with you when driving and cannot become mis- laid as long as the key is in your possession.— WINDSOR CROWELL. 147 You can’t possibly lose your automobile li- cense if it is attached to the switch-key FORGING— Ancient and Modern INCE the olden days when armorers of Damascus forged on anvils, with hand-hammers, their world - famed ‘| swords, the Art of Forging has de- veloped into a gigantic modern in- dustry. The smith and his puny hand- hammer have been supplanted by powerful machines that forge great crankshafts, as well as smaller pieces, in dies. The drop-hammer’s mighty force has replaced the blacksmith’s arm of brawn. And rightly so. For the process: of Drop-Forging insures far greater strength and accuracy, better quality and speedier output in wrought metal parts than would otherwise be possible. In the manufacture of Williams’ Superior Drop -Forgings and Drop- Forged Tools is employed the most im- proved mechanical equipment, backed by engineering knowledge, technical skill and experience—experience gained during nearly half a century in the con- stant effort to maintain the high stand- ard established for Williams’ product. Booklets describing our Superior Drop-Forged Wrenches, “Vulcan” and “Agrippa” Machinists’ Tools and Pipe Fitters’ Tools will be mailed, free, on request. J. H. WILLIAMS & CO. “The Drop- Forging People” 7 Richards Street, - Brooklyn, N. Y. 7 South Clinton Street, - Chicago, IIl. 7 Vulcan Street, - - Buffalo, N. Y. WILLIAMS’ SUPERIOR DROP-FORGED WRENCHES 40 Standard patterns in about 1000 sizes with openings 3/16 to 7-5/8 inches. Write for our new Wrench Book. ——=Qa

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cae came aera Bere

Is Your Machine Under-estimated THAT ‘productiveness which puts your machine ahead of the next best—is it a matter of record with the user of the machine? Can the best rate-of-work be checked-up by the operator— and kept up by comparative records of his work ? There’s the need of a COUNTER —to give the owner and opera- tor the full measure of your machine, keeping adjustments and operating methods up to the point of efficiency. This small Rotary Ratchet Counter (No. 6) counts reciprocating move- ments of the lever, as required in re- cording the output of punch presses. When the a is moved through an angle of 40 to 60 degrees, the count- er registers one. A complete revolu- tion of the lever regis- ters ten. This counter is adapted to no end of counting purposes, simply by regulating the throw of the lever. Price, $2. (Cut nearly full size.) The Revolution Set-Back Countér below is designed for larger ma- chines, where a shaft-revolution indicates an. operation.

[eee [O10 LOL

Registers one for each revolution of shaft, 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 figure-wheels, $9.00 (subject to discount). (Cut less than 14 size.) Set- Back Rotary Ratchet Counter of similar size and type, $10.50 (list). Other Veeder Counters are supplied ac- cording to your requirements, in great pony of size and style, Let us send new illustrated booklet. The Veeder Mfg. Co. 44 Sargeant St., Hartford, Conn.

A New Way to Lay Off Bolt-Holes HEN dividing a circle into an even number of equal angles— as in laying off bolt-holes—the follow- ing procedure will save much time. Suppose that you wish to lay off sixteen bolt- holes around a circle (see il- lustration). By using the 45- degree triangle and T-square in the usual manner, eight of these holes can be located —as at A,B, C, D, E, F, G, and H. Now, instead of bisecting the arc between A and B with compasses or dividers, it can be done by joining A and F by means of a triangle and sliding the triangle parallel to itself into the position OX. This construc- tion depends upon the geometrical theorem that an angle inscribed in a circle is equal to one half of the central angle standing onthesamearc. Thus we have angle XOB equal to angle AFB equal to one half angle AOB. In the same manner, the points Y, Z, etc., may be located by successively joining the center of each hole with the far end of the diameter through the next hole. If it is-necessary to lay off thirty-two holes, the process may be repeated to bisect the ares AX, XB, BY, etc., and repeated again for sixty-four bolt-holes. By the use of a 60-degree triangle, twelve bolt-holes can be located from the T-square, from which other points can be laid off for 24, 48, 96, etc., bolt- holes successively.—F. M. WESTON.

Suggesting an easy way of laying off bolt- holes on a drawing Rubber Nipples Make Fine Insulators for Test Clips OMETIMES test clips or test points are attached to lines carry- ing some- voltage, heavy enough to seem dis- agreeable if accident- A rubber nursing ally passed nipple prevents through the the current from body. In that case

leaking through insulators: near the terminals where handled are convenient. A good temporary insulator can be made of a rubber nursing nipple. Simply enlarge the hole in the nipple and run the wire through it until the clip or point just emerges from the large end. The clips can then be handled with perfect safety.— WINDSOR CROWELL. 148 what heavy °

Popular Science Monthly

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

‘‘Wonder” Cold Pipe Bending Machines (pat.) elec- trically operated to bend from 1” to 8”. Send for printed matter. We also manufacture TEN other sizes, hand operated to bend from }%” to 6”. American Pipe Bending Machine Co. jonni usc, BIG PROFITS forYou ' inHB BATTERY CHARGING

Battery charging is a wonderfully profitable business that you can handle without any special electrical or mechanical experience. With no better opportunity than yours, many HB owners are clearing $100 to $150 EXTRA PROFIT Every Month Some even mare. This HB 500-watt Charger re charges | to 8 auto storage ba ries at once with current cost of. fonly 10c to lic wart battery. Auto- ist pays 75c 50. res little attention aud no > extra ily made. its quickly and easi Ths Money-Maker.<, 15 _ Your re. taal bee Se ueee tend $16 firs eg 8 on nt with tral o arg of at once from this No By © Grier ctarget - 8 money-back be HOBART BROTHERS COMPANY * Box S41 Troy, Ohio. RICHARDSON’S POLYPHASE SLIDE RULE

has the regular A, B, C and D Scales: also a CI or Inverted Scale. Logarithm, Sine and Tangent Scales. All graduations are printed on white coated steel from engine divided plates. These Scales are accurate and will retain their accuracy indefinitely. They are not affected by acids, alkalies, water or grease. Length of rule 10 inches. A 100 page Instruction Book, which teaches all there is to know about slide rules, is sent with each order. Price of the Richardson’s pate Slide Rule, in case, with a 100 page Instruction Book, $2.00. An ideal slide rule. It is low- priced and an equal to any cad rule in and durability. "Be convinced. money will be promptly refunded if you are not satisfied. GILSON SLIDE RULE CoO., Niles, Mich. STAR STORAGE BATTERIES 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. Sz Aa

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April, 1920 The Poultry Hook is a Great Labor-Saver NE simple labor-saver for the poultryman is a hook for catching birds. Any WIRE HOOK——3Y77 amateur me- chanic can make it in a jiffy. Take a long piece of stiff steel _ or iron wire, and bend it in the shape of a long Simply lean over the U. The open fence and catch the end of the U chicken by the leg should then be turned back, so the sharp end of the wire will not injure the bird’s legs. Fasten the hook to a strong but light pole, and the hook is ready for business. The hook is slipped around the fowl’s leg, and slides down to the foot, where it holds until the poultryman can walk up and pick up the bird with his hands. A simple but efficient aid in the poultry-yard.—L. B. RoBBINs. Automobile Economy—What It Means HEN the topic of economy is dis- cussed among a group of motor- ists, it is often found that only the type of economy secured by high gasoline mileage is referred to. The other fac- tors of economy are frequently forgot- ten either in purchasing or using a car. Let us examine them in order. First, economy is an all-inclusive term. In some respects. it is synony- mous with good investment and dollar- for-dollar value. In its broader sense you must consider performance, com- fort, and good looks when obtained at a medium price. Sturdiness of construction and proper workmanship reduce your re- pair charges—in most cases an impor- tant economy feature. Accessibility of adjustments and lack of complicated mechanism reduce your upkeep to a minimum—another fact to be re- membered. The increase in gasoline mileage se- cured by proper preheating of fuel is worthy of note at this time when the quality of gasoline is low. Easy start- ing and great flexibility in high gear save much gasoline. Scientific distribution of light weight not only increases gasoline mileage but adds miles to the usefulness of your tires. The cost often takes precedence over fuel expenses, and the ratio of car weight to standard tire equipment should be considered by the intelligent buyer. Every motorist realizes the possibil- ities for economy in his every-day driving, but these few suggestions may remind him of several factors. that should be thought of under the subject of economy. TO cut down the cost per cut How Many S. P. M.? ‘‘Haste makes waste’’ is just as true of hack saws as of anything else. Forcing a blade by increas- ing the strokes per minute means a quickly dulled blade. 50 to 60 strokes per minute is about as fast as it is economical to run when | cutting dry. - On soft steel, using the speed compound, saws may be run to advantage at about 100 S. P. M., at from 65 to 80 on annealed steel, and on unannealed tool steel at about 60 to 80 strokes per minute. | Follow ‘the Starrett’ Hack Saw Chart, put on the weight and watch the..cutting cost decrease. THE L..S. STARRETT CO. The World’s Greatest Toolmakers -Menufacturers of Hack Saws Unexcelled ATHOL, MASS. TLAS ited f: brand new Diates with vA oN "Water n blue Mountaine tn relief and all’ Rail, Deen tot ooo ene lence Monthly, 228 West FACTORY GUARANTEED -. ALL SIZES - IN ORIGINAL BOXES @ . : m_ Your Opportunity pa Single Phase Motors Motors P sali Suitable for re ll lighting | # and 3 phase, A.C.. ¢20v, Battery Outfits 1200 B. P. Be with ba i Battery Charging 60 c, 1750 RPM., complete To operate on A. C., a phase and Power Requirement*. | with base and pulley 1g REustatas: $24.50) som wom $16.50 | su. $49.50 | "atntes™ "$40.00 th REESE $358) | scnem guaso|'** - 959.80 | Esai” "$68.50 Vo vate, 1 women 946-00 10, 2% am $24.50 7) $72.50 ees eee. $75- 1“ i $67.50 | wo wu 12 =. $38.50 121 vl, A, 20 watt, Heels, $8.00 2 ran $108-50 | += $38.50 ms ae naa he aie ume $85.00 SAREE, $124.50 | ee see eo ienueeee,, | ean $11000 5 Kosta keg wor $164.50 | Moves re $85 00 | fre ot $36.50 MM yooke witee owhaaeent 9 1 259-00 WRITE FOR CATALOG. BARGAINS IN MOTORS AND GENERATORS ‘ SPECIA

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et; f pie iG 7 De Non a oo a eh Ei | 1 i ii 4 , +f : is SIMONDS c “ Sitichiliing —all of them: Compress blade, keyhole blade, and that all-purpose 18" blade made for cutting either wood or metal. lL A handy kit for contract- ors on roof, or floor, or any kind of repair work entailing nail and metal work cutting. Edgeholding — the out- standing quality of Simonds Saws — because of the Simonds made steel that’s in them. 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, SAW STEEL SIMONDS ercovcrs 7 _MADE RIGHT SINCE 1832 What. Do-You Know About Your Car’s Electric System? ESPITE the fact that a well built electric lighting and_ starting system gives little trouble, it is im- portant that the devices provided by the manufacturer to indicate derange- ment be watched. It is almost as easy to form the habit of looking at the indicators as it is to form the habit of ignoring them. Self-starters at present are very reliable; nevertheless, that does not | mean that this device does not need | eareful attention. The electrical ap- pliances used have a number of important bearings and points of | adjustment that need careful atten- tion. One should make it a point to familiarize himself with all the details regarding the electrical system, and inspect them carefully at frequent intervals. By so doing a lot of trouble and expense will be done away with. Most self-starting systems have a | fuse-box installed at an accessible point. The purchaser of a new car should acquaint himself with this as quickly as possible. Very often con- siderable trouble is eliminated by the installation of a new fuse. This is a simple matter, but its neglect may cause a lot of trouble and unnecessary expense. Modern cars are equipped with electric self-starters and do not have the crank handle installed. Without a crank handle it is difficult properly to test the compression of each cylinder. Often a motor is run with weak cylinders simply because it is too much trouble to attach the crank handle and test the compression of each cylinder. If the compression.of each cylinder is not kept up to standard there is bound to be more or less of a pound in the engine, which is injurious to all the working parts, this being true especially of the bear- ings. When the self-starting device fails to start the engine after reasonable trial, the trouble should be located without delay. One cannot expect too much from a small battery. The self-starter is not supposed to crank the engine indefinitely. Bear this in mind and you will prolong the life of your battery. Many times a troublesome skip in a cylinder is due to an unsuspected leak in the high-tension wire. When hunt- ing for such trouble, go over the wires carefully, raising them slightly from any place where there might be a leak. When found, the place must be covered’ with electric tape, unless a new wire is installed. If the wire runs through a metal tube it will not be possible to trace the whole length of it, so it must be re- moved from the tube and connected as before. By running the engine and going over the wire inch by inch, the leak should be discovered. . If it is not 150 Popular Science Monthly tanle Teale Stanley Cutter and Chisel Grinder The STANLEY CUTTER AND CHISEL GRINDER is a device for holding Plane Irons, Chisels, and other similar cutting tools that they may be ground or honed to any desired angle or bevel, insuring an ac- curacy that is very difficult to obtain when the tool is held in the hand. The tool to be sharpened is rigidly held in the Grinder by thumb screws, and may be given any desired angle by means of the large screw attached to the roller frame, which raises or lowers the main body. As shown in the cut the Grinder is fitted with two thumb screws and _ three thumb screw holes. By the use of the two thumb screws, the tool to be ground is held much more firmly than is possible with the use of a single screw. The Sharpener is made en- tirely of metal, all parts being nickel plated. Special circular upon request ANLEY Rute & Levet Co. New Baitain, Conn. U.S.A. zt

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April, 1920 strong enough to give a spark it may be found by passing the fingers along its length. A slight shock will indi- cate the trouble instantly. Braided insulation is particularly liable to pick up moisture and short- circuit every time it rains. When the missing cylinder is located you should parallel the wire—that is, lay a new or perfect wire from distributor to plug. Disconnect the old one and the engine should pick up speed and the missing should stop. The safety spark-gap of a magneto rarely gives trouble, but it may at some time. It has too much re- sistance in ordinary circumstances, but if the gap in the spark-plug burns too wide it will be easier for the current to short-circuit through the safety gap. Run the engine and listen carefully for a spark. If it occurs, look at the gaps of the plugs and set all of them to the thickness of an old hacksaw blade. Some drivers prefer a larger gap than the hacksaw blade will give. The usual blade is about one fortieth of an inch, or .025. This is right for magneto, but one thirty-second may be used with battery ignition. Since the gap never closes up, but always burns larger, it is evident that a smaller rather than a larger gap is preferable. For the magneto a small gap is necessary; otherwise the engine will miss explosions at low speed. Why the Homemade Wagon- Jack is Best HE worst thing about most wagon- jacks is the time it takes to get them adjusted and set in place. On a ranch where a number of hay-racks _were in more or less constant use, a Why. buy the manufactured kind when you can make a wagon-jack suited to your particular need simple jack was made to raise the wheels from the ground preparatory to greasing them. The jack was made by sawing a 2-by-4-in. piece of wood as shown in the illustration, hinging the cut-out portion, and bolting a thin piece of strap-iron about it to prevent splitting the wood. The hinged piece was so cut that the upper end came two or three inches above the bottom side of the axle when it rested upon the ground. This was placed under the axle, and the lever arm raised until the two came together, locking itself and holding up the wheel.— DALE VAN Horn. rerelos WRG PRATT we - All-Steel Mitre Box made to give Real Service We: have been making these Mitre Boxes for ten years. During all this time, re- pairs and replacements have been practically nothing. : Our Mitre Boxes are built entirely of steel and trussed like a bridge. This construction eliminates the possibility of breakage from any cause and enables the tool to retain its accu- racy for practically a lifetime. The saw may be locked at any desired angle. It can be held in an elevated position by a spring lock, which is easily released by a slight downward pressure. Stops can be readily regu- lated to permit sawing to any desired depth. These are a few of the good points of the Goodell-Pratt All-Steel Mitre Box, but there is but one way to really appreciate this tool and that way is to ask your dealer to show it to you. Complete pocket -edition catalogue sent on request GOODELL PRATT COMPANY Greenfield, Mass

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eC en ee np wet Fat HSIN ont matte te blawananten POF oe ww sili, | te ot ~~ Ae. mete ta In liquid form and easy to use, Will ordinarily seal leaks in from two to ten minutes. A quick, perma- nent, inexpen- sive repair for tubes and cas- ings. Can be applied in three minutes at a cost of 2 cents. Will remove pits and foreign sub- stances f ge valves, givin velvet seat. ill not cut grooves. eg EE Oa i, Yi TD ee aN Fine af 1 fol Sy pa An enantinsad dose will stop that knock— quiet the motor—and save the batteries. You can do it yourself in ten minutes. Keep Your Car Popular Science Monthly Ma — an It isn’t fair to yourself or to your car to run it without any attention and then sell it at a big loss. With but little effort you, yourself, can keep your car in such condition that the depreciation will be very slight. offer for your use Johnson’s Car Savers. ence is necessary for their use. by the amateur with perfect satisfaction. We No experi- They can all be applied Johnson’s Car Savers are of the very highest quality on the market, but hee you insist upon Johnson’s you are taking no chance, for all of our preparations are fully guaranteed. il oy) ill MTT HN OM mobile. when you come to sell or turn in your car. Car Savers. booklet ‘‘Keep Your Car Young”’—It’s free. S. C. JOHNSON & SON Dept. P. S. M. 4, RACINE, WISCONSIN 152 Johnson’s Car Savers have been on the market for several years. of cans have been used by motorists everywhere with entire satisfaction. For years our employees have been our partners and share the profits. Because of this personal interest unusual care and skill enter into the man- ufacture of the Johnson products—overhead is reduced to the minimum and we are enabled to sell at a very slight increase over pre-war prices, not- withstanding the tremendous advances on all of our raw materials. Start today to reduce the depreciation of your auto- An hour or two every month and Johnson’s Car Savers will prove their value in dollars and cents Millions Representative dealers and. jobbers all over the world handle Johnson’s Don’t accept or handle unknown substitutes. Write for our me Johnson’s Black-Lac is the ideal top dress- ing. One coat imparts a rich, black surface just like new. A splendid elas- tic varnish for bodies, hoods and fenders. A coat wil! ncrease the value of your car from 10% to 35%. Dries in 24 hrs. It seeps between the springs, thor- oughly lubricat- ingthem. Makes your car ride easier, reduces the liability of spring breakage. eae