Popular Science Monthly 1921-01: Vol 98 Iss 1

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Popular Science Monthly STE ae 58 . Ee —— - . — = The worlds best guide book * -to the enjoyment of music Entertaining Instructive Convenient & PS ~ Sg Be. gi “a Vict ola - ~ VICTOR RED_SEAL RECORDS qT (Keh-r00' - 20h) eatest ring OPT Americal gage j ing Oe pst 00h) oration, the van a besuly | eats have Bete ocad by the exquinte 1° teres and wat \ , beld Ae Te us a native of = P|. bees jus voice. boy he #ang in \ } power et aiyen he was 8 mete OO ented ae ite, Sire Trae bomaty of be vec orem’ “Fall who heard # Following thes » 1 91.25 ,e ' 2 17 esos 12135 2 +75 z ‘ 72 1 +25 eo 12 7 jo «(4.25 ? \.75 Trvchamacder-d om awe) 880) ies o (Rudo! oncavallo ~an (Beeuteow" Aneel) A Fare Te jno of My ¥% Dwelling 1? AM Exe? aint Be de how f kee

Are you familiar with the story of the opera of Rigoletto? Of Faust? Of Pagliacci? Do you know the national airs of Denmark and China? Do you know which Kipling ballads have been set to music? Did you know that Chopin was pronounced a genius at eight years of age? Information on all these subjects is to be found within the 510 pages of the Victor Record catalog. It presents in alphabetical order, cross indexed, the thou- sands of Victor Records which comprise the greatest library of music in all the world. But besides that it abounds with interesting musical knowledge which ~ adds greatly to your enjoyment of all music. It is a “HIS MASTER'S VOICE” VS Pat ofr REG. This trademark and the trademarked word “Victrola’’ identify all our products. the lid! Look on the label! Look under book every music-lover will want, and there is a copy for you at your Victor dealer’s. Or write to us and we VICTOR TALKING MACHINE CO. will gladly mail a copy to you. Victor Talking Machine Company, Camden.N.J. whe

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Popular Science Monthly “THE WOOD THAT ALL ITS USERS PRIZE THE WISE INVESTOR SAFELY BUYS.” A WORD as to the Reasons and Purposes behind the Cypress Pocket Library Everybody likes to build, but nobody likes “repair jobs.” Repair jobs inevitably represent an additional investment without any addition to value. That point is worth digesting. When you build, whatever you build, you like to build “for keeps.” Some people change their minds about styles, in building the same as in wearables; our tastes develop and result in changes in our wants; but nobody changes his or her mind as to wishing to get the greatest possible endurance, or wear, out of the things they buy, and especially is this true of building investments. Yet, singularly enough, so many people know so little about woods and their relative values and special utilities; so many people think that ‘lumber is lumber’’ and never attempt to specify the KIND of wood they wish used; so many people believe that repair bills are “necessary evils,’’ that we believe we shall be able to render a real public service by continuing the publication of THE CYPRESS POCKET LIBRARY, convenient in size, authoritative in character, of probable value as a technical guide, and careful and scrupulous in its every statement or inference. We have not, and do not, by any means, recommend the use of Cypress without discrimination; Cypress is not the best wood for every use; but where it IS appropriate it is so emphatically (and demon- strably) the one best wood that the many should know about it instead of the comparatively few who formerly profited by their special know]l- edge. WRITE FoR VoLuME I, with full text of U. S. Government Report on Cypress, and containing complete list of all the 43 volumes in the library. Then write us for the volumes that will best serve you. It may be of interest that many of the volumes of The Cypress Pocket Library have become established as standard works of reference —text books—in a number of eminent educational institutions and Government Departments. This is a gratifying tribute to the broad and helpful spirit in which these booklets have been produced, and more than justifies the theories behind the original pioneer idea of such a Library for Lumber USERS. Let our ‘“* ALL-ROUND HELPS DEPARTMENT” help YOU. sources are at your service with Reliable Counsel CYPRESS MANUFACTURERS’ ASSOCIATION Our entire re- SOUTHERN 1249 Perdido Building, New Orleans, Louisiana, or 1249 Heard National Bank Building, Jacksonville, Florida INSIST ON TRADE-MARKED CYPRESS AT YOUR LOCAL LUMBER DEALER'S IF HE HASN'T IT, LET US KNOW IMMEDIATELY | At Last—the Fireproof Airplane | The Typical Airplane Motor. . | How to Strengthen Flower-Pots | A Hot-Water Bottle for Teeth. . Trimming Brushes by Machine —> Popular Science : Monthly JAN., 1921 (Mi olume 98-No. cementite J Important to Readers Owing to the paper short- age, the number of* printed copies of POPULAR SCIENCE MONTHLY is limited. To insure getting your maga- zine regularly, you should place a standing order with your newsdealer, or send us your yearly subscription of $3.00. Don’t miss the big Holiday Offer on page 13. CONTENTS AERONAUTICS A Free Balloon that Hasn’t Any Net Save the Mail from Fire Is it Good Flying Weather?.. FOR THE FARMER Bossy’s Wearing Stockings Now. . eee Grubbing Up Tree-Stumps with Liquid Oxygen, A One-Man Ice-Cutting Machine A Machine to Compress Silage Fodder Made of Sawdust. . HOUSEKEEPING MADE EASY Make Your Gwa Tees: 12 ic dias sects occw ee Squeezing Out the Last Drop................ A Thren-tnck Coder Cheat «ou coc ccc ccsece cass Anchor Cuff-Links to the Shirt............... Measuring the Home-Brew Kick............... Getting Rid of the Japanese Beetle Thawing Pipes by Torch. . Family Portraits on a Rod. Reading the Temperature. Clean Your Shoes on a Skate. A Bird-Cage Hanger Clamps to Molding A Place for Rubbers............. ag The Handy Little Magnet................. This Plug Will Fit Any Socket................ This Brush Reaches All the Teeth Frames from Automobile Lenses. . A Gear-Shift-Lever Poker................... Sharpening Phonograph Needles.. . INDUSTRIAL PROGRESS What We Pay for Idle Machines. . Reducing the Handling Cost... Safety for Elevator Passengers. A Thousand-Ton Concrete Ship.............. (Continued on page 4) San Copyright, 1920, by the Modern Publishing Company POPULAR SCIENCE MONTHLY is issued monthly, Yearly subscription in the United States, $3.00. Canada, $3.50. Foreign, $4.00. Single copy, 25 cents. Advertising rates on application. twentieth of the second publication. Ferms close the month preceding date of Entered as second-class matter Dec. 28, 1915, at the Post Office at New York under the act of March 3, 1879. ter at the Post Office Department, Canada. Entered as second-class mate The contents of this magazine are copyrighted and must not be reprinted without permission. H. J. Fisher, President; R. C. Wilson, Vice-President; O. B. Capen, Secretary and Treasurer. Modern Publishing Company 225 West Thirty-ninth St. Popular Science Monthly New York City SUE CRAM tr Sec "beer " dea & seer ’ fron — hut i aba 3 sile : The . or inv = ent! the: be aga ligk I mo of 1 if a pra ity ent 3 & a oe : % & = be + Janu

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BSB. 36 ams sce PEIN January, 1921; 25 Cents a Copy; $3 a Year Popular Science ee AW ont Waldemar Kaempffert, Editor Vol. 98, No. 1 = ‘Monthly Published in New York City at 225 West Thirty-ninth Street 4. Telegraphing the Picture of an Escaping Criminal BLOOD- A CURDLING shriek has been heard in the dead of the night, seemingly coming from a ramshackle hut long since abandoned. Then silence over all. The neighbors, either too sleepy or too scared to investigate, pres- ently fall back on their pillows, to be awakened again only by the light of day. But with the morning a group of men and women, after gossiping for a while over the occurrence, ap- Monsieur Belin’s remarkable invention will also take its place in the professional and business world By A. J. Lorraine He Is the Inventor of the Telephotograph Monsieur Edouard Bélin, the inventor of the process and apparatus described in these pages, is also known to the scientific world as the man who designed and installed a system of radio signals sent out hourly to all the world from the Eiffel Tower. He is now working on the problem of television, and is optimistic that you may, within this gener- ation, be able to see (literally speaking) your friend over the wire, as you now converse with him by telephone. bushes that have had their way for many years, un- touched by the hand of man. As the search-party draws near, how- ever, they look with horror on the frightfully muti- lated body of a woman lying across the door- step. The police are called. It quickly develops that cir- cumstantial evi- dence points strongly to a man recently seen prowling about the neighborhood. He is a man with an “established rep- proaches the hut with mingled curios- ity and dread. From the distance the entrance is hidden by thickly grown utation” who is listed and figured in the rogues’ gallery. A photograph of him is procured from the gallery. Monsieur Bélin, who recently made a visit to the United States at the invitation of the New York World, to conduct experiments in the electric transmission of photographs January, 1921 17 In forty-eight hours he may be any-

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The victim of a gem robbery in Pittsburgh identifying the rogues’ gallery photograph of ‘Slick Jack” as the likeness of her discharged butler where within a two thousand miles radius from the scene of the crime. Of what avail is a photograph of him in New York if he should seek a hiding-place in Chicago? True, photo- graphs can be mailed, but immediate action is wanted. In this, as in so many emergencies, modern science has resources to cope with the situation. Edouard Bélin, the noted French physicist, has re- cently come to this country to conduct experiments on the electric trans- mission of photographs. This art, which even now has to its credit no small measure of success, undoubtedly has a great future before it. The Beginnings of Telephotography It is interesting to note the very earliest efforts in the transmission of pictorial information by telegraph. In 1879 a Frenchman named Gras conceived the idea of transmitting, for military purposes, for example, a topo- graphic map or picture. He divided the chart into a checkerboard of squares, like a chessboard, and assigned numbers to each horizontal row of squares, and letters to each vertical column, in much the same way that chess-players-dgiignate ‘thé: ppsitiort “6f: chessmen. He squid’ then telepr chart, roughly, in such, a gode as this: h hts -at *he*transmitting end is River Y2 to B2, B2 to B13, B13 to T18. Bridge B8. Highroad A8 to M8, split to W2 and V13. Since this first and primitive sug- gestion, a considerable number of more or less successful efforts have been made in the transmission of photo- graphs by electricity. Some inventors have made use of the property that the element selenium pos- sesses of changing its elec- trical resistance with the intensity of the light fall- ing upon it. Such “se- lenium cells,’’ however, are delicate, and the effect of light on them is not in- stantaneous, but requires a certain time to assert itself; the changes in the resistance of the cell lag behind the corresponding light changes. It is true that in the most success- ful developments of this method (especially as car- ried out by Professor Korn of Berlin), these difficulties seem to have been very satisfactorily met. Never- theless, a method that en- tirely a avoids the use of light-% -Ssensitive apparatus _ very inviting to any one P nes *.: 18 Popular Science Monthly MOTOR-DRIV EN > CYLINDER A chrome-gelatine print of the photo- graph is curled around the cylinder, which is rotated past a tracing-point. At the same time the cylinder moves lengthwise along the axis, so that the tracing-point follows a spiral course. As the tracing-point moves over the crests and furrows of the photograph, the diaphragm of a microphone at- tachment is vibrated so that the cur- rent in the telephone circuit varies in the same way as when one speaks over the wire who knows the difficulties of working with selenium cells. It seems at first sight almost illogical to attempt to transmit a photograph— a thing whose very appreciation by the senses depends on light—without mak- ing use of any light-sensitive trans- mitter. As well might you try to recognize the photograph of your friend in a perfectly dark room. Ex- actly: that is just the point. Suppose you handed your photo- graph to a blind man. Presumably he would proceed to investigate it by Januai runn Of ¢ any stru pare is W hav play that or | whi no has nor pro sur cor De col un Popular Science Monthly

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January, 1921 The “ear”? that hears the telephoto- graph at the other end of the wire is a delicate galvanometer, a loop of wire supporting a tiny mirror stretched be- tween the poles of a magnet. When the current from the microphone va- ries, the mirror turns through a slight angle, reflecting a powerful beam of electric light through a graduated screen on toa photographic film re- volving on a cylinder at the same rate of speed as the sender cylinder running his finger-tips over its surface. Of course he would be unable to form any conception of its appearance. And yet, by means of a delicate in- strument, a photograph, suitably pre- pared, can be read “by touch.” This is what Bélin has achieved. The amateur photographer may have observed that some negatives dis- play a distinct relief effect. It seems that certain conditions of development or of fixing produce this appearance, which ordinarily is a mere curiosity of no practical significance. Advantage has, however, been taken of this phe- nomenon in the rotogravure printing process. A print is made on a gelatine surface impregnated with bichromate. This substance has the property of be- coming insoluble on exposure to light. Development of the exposed print consists simply in washing out the unaffected soluble gelatine, leaving the A desperate encounter between a gang of desperadoes and the police. This par- ticular gang first stole an automobile and then robbed a bank January, 1921 “Slick Jack” confronted by his own photograph, which was telegraphed from Pitts- burgh to Portland, Maine, and which arrived before he did, facilitating his arrest insoluble part behind. It is not surpris- ing that the picture so produced should be found to display a more or less marked plastic or relief effect. By the use of especially heavy gelatine coatings this feature may be empha- sized as desired, and the rotogravure process—by which, for example, the picture pages of some of our Sunday newspapers are pre- pared—makes use of such relief photo- graphic prints some- what as the older half-tone and similar printing processes made use of etched metal plates. It is a chrome- gelatine print of this kind that Monsieur Bélin uses in transmitting pho- tographs by elec- tricity. The original to be transmitted is curled around a cyl- inder like the cylin- der of a phonograph. A tracing-point is applied to the sur- face of the photo- graph, which is then rotated at constant speed past this point. 19 At the same time, the cylinder moves lengthwise along its axis, so that the tracing-point follows a spiral course upon the curled photograph, and covers every point on its surface. In this way it literally “feels out” the photograph. But if the instrument kept its knowl- edge to itself, so to speak, it would be of no use to us. There must be means of translating into visible signs the indications that the blind instrument has read by touch. Furthermore, they are to be transmitted some distance. Listening to a Photograph Both these ends are secured at one stroke, in this apparatus, by the aid of a microphone. What has a microphone, that is to say a telephone transmitter, to do with the despatch of a photograph? Well, after going through the seemingly crazy perform- ance of examining a photograph by the sense of touch, why stop at that? Why not listen to a photograph with your ear? In a sense, that is what Monsieur Bélin’s apparatus does. It translates the currents coursing in a telephone circuit, which we ordinarily translate by listening with the ear. These currents are translated into a visible likeness of the photograph at the transmitting end. And this is how the thing is done:

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The tracing-needle, whose (rounded) point bears against the relief photo- graph, is applied, at its opposite end, against the diaphragm of a microphone receiver. And so, as the tracing-point moves in and out among the crests and furrows of the photograph, crophone resistance is lessened by the pressure, and a stronger current flows through the galvanometer; the beam of light is deflected toward the left, say. This does not affect its ultimate arrival at the opening in the casing, Popular Science Monthly since all rays from the course are con- verged to the same focus. But inter- posed jin the path of the beam is a graded screen, fully transparent at the right-hand end, and shading off grad- ually to complete capacity at the left-hand end. Hence the ray the resistance of the micro- phone fluctuates, and the cur- rent in the telephone circuit varies in the same way as when you are conversing over the wire. Only, the language it speaks no man ever heard of. It now needs to be translated into a photograph at the re- ceiving end. Naturally, the translator needs, first of all, an ear to hear the message. The Receiving Apparatus This ear is a delicate gal- vanometer, a loop of wire stretched between the poles of a magnet. When the current from the microphone varies, the loop of wire is eaused to turn through a slight angle. On the loop is fixed a very small mirror, which receives a beam of light from a brilliant electric lamp. As the mirror turns, the reflected beam also turns. It passes through a screen and then through a lens that focuses the beam on a_ small aperture in the wall of a light- tight cabinet or-.case. In this case revolves a second cyl- inder precisely like the one in the transmitting apparatus on which the photograph to be transmitted is wound. On this second cylinder is curled a piece of sensitized photographic film. The mechanism of the second cylinder -is arranged to keep exact time with that of the first. Monsieur Bélin has devised a very ingenious contrivance to secure this result. A cam on the carriage of the despatching cylinder trips a lever once in each revolution. At the receiv- ing end aratchet corresponding to this cam is caught by a pawl, and the movement of the receiv- ing cylinder is thus arrested until the cam at the despatching end is exactlyin the position cor- responding to that of the ratchet at the receiving end. Then the pawl releases the receiving cylinder, which now proceeds on itsrevolution. Needlesstosay, the adjustment is so made that the period of arrest is oniy a minute fraction of a second. © Keystone View Company Now this is what happens: When the tracing-point which “feels” the photograph is at a high point in the relief, the mi- The reproduction of a photograph in Monsieur Bélin’s collection that was actually transmitted by telegraph. It does not differ in appearance from an ordinary photograph. This invention may soon be used for sending telegrams; the message could be written in heavy ink and transmitted in the same manner as the photographs received when the tracing-point is on a high spot of the photo- graph (7. e., a dark spot); the light is almost completely cut off before it reaches the sensitized film in the dark cabinet. Onthe contrary, when the tracing-point is feeling out a hollow in the photograph (7. e., a light spot), then the galvanometer receives little or no current, the beam of light passes through the trans- parent part of the screen, and a maximum of light is received at the film. In this way a negative copy of the original is produced. Thus the net is drawn closer than ever by Monsieur Bélin about the fugitive from justice. The crime of the abandoned hut will not go unpunished. While the murderer is speeding in the express to a place of greater safety from pursuit, his photo- graph is being traced point by point, with the unerring finger of the Bélin transmitter. Not many minutes later the police departments of aljl the prin- cipal cities of the land are in possession of the portrait. As the culprit steps from the train, he is met by an officer and plain- clothes men holding his photo- graph in their hands. His like- ness has traveled ahead of him, and has beaten him in the race by several hours! Telegraph Your Handwriting Aside from its application to police service and to the rapid transmission of pictorial news items for the daily papers, Bélin’s invention may also be The simple looking apparatus invented by Monsieur Bélin for telegraphing photographs. He is now working on an invention that he believes will enable a person at one end of a wire to see the person with whom he is talking 20 used for the despatch of ordi- nary telegrams. The message is simply written out with a some- what heavy ink, and is then transmitted just like a photo- graph. Thus the services of a skilled Morse operator can be dispensed with. Moreover, since your very own _ hand- writing goes forward over the wire, you may sign in New York a check to be cashed by the consignee in San Francisco! The busy financier need not waste his precious moments going out of his way to sign that million-dollar contract that has been under consideration for months past. He can com- plete the transaction at his desk, setting his hand and seal to the document by telephone. A tastisn ih Jan Popular Science Monthy

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Popular Science Month],

Walter N. Polakov, Student of Industrial Relations “About twenty years ago,’’ says Walter N. Polakov, who has been retained as consulting engineer by the Board of Estimate of New York city, “I was assistant superintendent in a locomotive'plant in Russia. A strike was threatened. I was selected by the management to be one of a committee to adjust the differences between the men and the company. One evening, on invitation, I attended a meeting of the men, and there I met an old man called ‘Uncle John.’ ““*Young man,’ said he, ‘how can you adjust our dif- ferences until you have investigated the conditions under which we work? Now take my advice and, before you do anything, take a watch and time the work of each man. See how long each workman has to wait for the rivets he must drive, how long it takes to sharpen his tocls. We don’t want to be idle, for every minute we lose waiting for work deducts from our pay.’ “Uncle John was right. The men did not want to go on strike. They merely wanted conditions made possible for efficiency. That was my start in adjusting the human element to the mechanical element in industriai plants.”

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ath ly January, 1921 What We Pay for Idle Machines Walter N. Polakov points a possible solution of the problem ERE is a two-family house, each H family paying to the landlord fifty dollars rent a month. One family moves away, and the landlord demands one hundred dollars rent from the remaining tenant. “But it isn’t worth it!’ says the tenant. “You’ve got to pay; it’s my right to get one hundred dollars from this house, and I’m going to get it,” growls the landlord. So the tenant pays fifty dollars for the part of the house he occupies and fifty dollars for the idle part of the property. Curious as this arrangement may seem, it is exactly what is demanded of the public today, not in the matter of rent alone, but also in the matter of the necessities of life. This analogy of conditions as presented by Walter N. Polakov, the well known consult- ing engineer, is an example also aptly applied to the difficult industrial situa- tion of today. Eight hours is the standard working day. Time-clocks in factories measure the hours, and the employees are ‘‘docked”’ if they do not put in full time. The Real Cause of High Prices The product of the manufacturing plant depends upon the efficiency of the workmen and upon the efficiency of the machine. Expensive machines are installed. Factories hold to strict account the time of employees. Do they hold to account the time of their machines? Expert investigation has disclosed the startling fact that on an average American industries today work their men nearly 100 per cent of the working day, but that they work their machine equipment only 50 per cent of this period. The men are being worked to the utmost; machines are idle half the day. What is the result? Shoes, clothing, fuel, food—in fact, every- thing—is passing through a period of under-production. Agricultural im- plements are scarce; prices are con- sequently high. The farmer must pay such high prices for them that he must charge a high price for his product. His help is costly because the workers must pay high prices for their shoes, clothes, and food. Shoes and clothing are high partly because the machines are not kept busy making these prod- ucts. Instead of punching a time-clock, a workman should be held to account merely for the results of his day’s work. Show the average man that his work is appreciated financially and _ his By David Ardsley efforts to do better are stimulated. Browbeat him by the time-clock, and he feels free to do his work only for the sake of achieving the minimum result. Cost of Idle Machines When workmen are laid off, their wages stop. Human idleness costs an ‘employer nothing. When a machine is laid off, rent must be paid for the floor space it occupies, interest must be paid on the investment, allowance must be made for depreciation of its value, and insurance must be paid. In nearly every industry these charges are higher than the pay-roll. The fixed charges on a $10,000 ma- chine are twice the wages of its at- tendant. In the blast-furnaces used in the steel industry, the ‘‘overhead”’ charges amount to $90,000,000, while the wages are $22,780,000. In steel- mills the cost of the burden is in excess of $250,000,000, while wages are $188,142,000. Imagine what a steel strike means in machine idleness! Why is there a shortage and con- sequently a high cost of coal? In the coal industry, 50 per cent of the producing machinery remains con- stantly idle. The blast-furnaces of the steel industry, averaging the past ten years, were idle 40 per cent of the time, despite an acute shortage of the metal an entirely avoidable expense, one not caused by repairing equipment or other necessary interruptions—esti- mated roughly to be no less than $49,500,000 in a year. Organized labor does not object to increased productivity. Indeed, it declares that “labor is anxious to work out better methods for industry, and demands that it be assured that in- creased productivity be used for service and not alone for profits.” (From a declaration made by one hundred and fifteen labor unions in December, 1919.) If now, on the basis of equity,. we adopt the principle that the idle capital represented in idle plants and equipment is no more en- titled to any return or reward than idle labor, we will establish a principle of fair play. Clearly, the really effective ‘‘strikes’’ against production are those of the machines. Speed up production by making all the machines resound with industry. Start the cycle of industry in the factory. There is plenty of wealth for all; the country is rich in natural resources. But, with over- worked human beings and_ under- worked machines, there may be plenty 23 of profits for a few people, but the lack of production puts a burden of hardship on the commonwealth. In 1918 a ton of bituminous coal sold at the mine for $1.32, yet the combined wealth contained in this ton of coal had a collective value of at least $16! In terms of cash, the value of the 50,000,000 tons of coal wasted yearly in power production alone—not taking into account the large tonnage wasted in connection with other uses was $65,000,000 at the colliery. The value of the by-products of this coal would be more than $800,000,000. In terms of social value, the same coal wastage represents a loss of 500,000 tons of ammonium sulphate, 100,000,000 gallons of benzol, and 400,000,000 gallons of tar. Transfer- ring these amounts into other values, we find that the nitrogen contained in 500,000 tons of ammonium sulphate is capable of raising the production of wheat by 43,316,000 bushels, based on 115 pounds of nitrogen to the acre. Benzol is equivalent to gasoline, and the above amount is valued at about $30,000,000 —- representing, roughly, 2,000,000 miles of five-ton truck travel. The 400,000,000 gallons of tar would make possible the extension of rural highways and keep the existing roads in good condition. The foregoing three examples concern only the primary products, while there are other chem- icals, drugs, dyestuffs, ete., that could be extracted. But the greater part of this value has been paid for by the public without a return in service. How Workmen Check Time Waste Mr. Polakov told the writer about a plant in New Jersey where an efficiency chart is kept by the men themselves. If a machine is idle, the chart shows it, and the remedy is at once founce. If the delay is due to shortage of labor, word is carried to the employ- ment manager. If the delay is due to shortage of material, a tracer is sent out. “Assume that the idleness of a machine is due to lack of a certain raw material,” said Mr. Polakov, “the word is taken to the general manager. He looks at his map, where colored pins mark whence the company receives each product required in its industry. He discovers that the par- ticular material has started from a certain point. A quick summons brings the expert tracer. He finds exactly where the car of material is stuck, and if necessary provides men to get the raw material from the sidetracked train.

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This invention of an American promises to make the airman’s vocation a comparatively safe one At Last—the Fireproof Airplane One of the greatest recent develop- ments in the science of flying is the fireproof airplane, the invention of Parker R. Bradley, of Nutley, New Jersey. An ordinary airplane is rendered fireproof by the applica- tion of a fireproof ‘“‘dope’’ and paint. Then, after spraying with gasoline, as shown in this picture, it is set on fire. In experiments carried on at Hazelhurst Field, Long Island, the invention has stood the most gruel- ing tests that the government officials could devise This airplane has been the subject of repeated experi- ments with the fireproof ‘‘dope’’ without damaging its fabric. Aeronautical experts consider that this, when used with the fireproof suit and tank, will make Popular Science Monthly Mr. Bradley has also invented a fire- proof suit for the use of firemen and airmen. The picture shows such a suit appar- ently being consumed by fire. It is really only a coat of gasoline that will burn off without injury to the suit or its wearer. Airmen dressed thus may soon be a common sight Janua Li . tI take n hours ency trans{ tne fa The electr estim prope at le hand- been seven mate: of ha rapid hoist cents the speec savil Tt susp save nece over be k hois fi veri yp dre ord bac anc ex] gra an en tec cle usI ing 24 flying comparatively safe. The fireproof tank, which Mr. Bradley invented in the last year of the war, is also heatproof, and its construction is such that bullet-holes close up automatically Popular Science Monthly J =i

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January, 1921 Reducing the Handling Cost from Dollars to Cents 7 LECTRIC cranes hoist and [, transport loads that would take many men, tugging and lifting, hours to move. Industrial effici- ency depends upon the speed of transportation, outside and inside the factory. : The economic importance of the electric crane can not be over- estimated. A small electrically propelled crane can do the work of at least ten men provided with hand-operated hoists. Cases have been known where it cost sixty- seven cents to handle a ton of material by the antiquated method of hand hoists. By the use of the rapid, smooth-running electrical hoist, this cost was reduced to a few cents a ton. This was aside from the added advantage of greater speed, which also represents a saving. The electric hoist runs on an “‘T”’ suspended from the ceiling. This saves floor space, since it is not necessary to keep clear the floor over which it passes. A path must be kept clear when a hand-operated hoist is employed. The little shop electric crane is a. veritable Hercules. With it a man Mental Tests for the Clever N Europe a method has _ been adopted for selecting school-chil- dren of the highest mental ability in order that they should not be held back in their studies by slower minds. The pupils’ powers of concentration and observation are tested by the experiments represented in the photo- graphs below. The pupils are shown an engine model of a design simple enough to be understood without technical knowledge, and which a clever boy (contrary to most girls) usually has no difficulty in interpret- ing. Next, the children are shown | Saas: A Hercules of the workshop. It can hoist 3000 pounds and carry it 200 feet a minute pictures of animated scenes. These they are permitted to look at for only a short time. Half an hour later they are asked to write their impressions. In the latter test the girls usually show a superior keenness. To test their judgment, the pupils are given certain situations or prob- lems of every-day life, and are asked how they would solve them. Then problems with several solutions are presented, and they must choose the best solution. The clearness of ideas is tested by a request for concrete and abstract definitions; the promptness of can lift a weight from ten to twenty times greater than he could lift with an ordinary hand-chain block. Not only this, but he can move the load from one part of the factory to another in the twinkling of an eye. The electric hoist can pick up a load of three thousand pounds and speed along the beam with it at the rate of two hundred feet a minute. The driving motor is under perfect control at all times by the crane operator, who sits in a little steel cab high above the ground. At each side he has a controller. He is able to control the lifting with one hand and the travel of the crane along the beam with the other. Two heavy duty electric motors are used on each crane. One moves the crane along the mono-rail, and the other does the lifting. Thus, once the load has cleared the floor, the operator can start the crane, hauling up the load as it moves along. All vital parts of the crane are enclosed to exclude dust. Both motors are under perfect control, and they are very sensitive to the slightest movement of the control- ling handles. Ones ideas by the association of a with related notions. Their power of concentration is tested by asking the children to strike out certain letters or combinations of letters from given words. To test their memory, they learn by heart a set of syllables devoid of any sense, as well as connected texts, thus testing the retentive faculty as well as the speed of memorizing. After the results of these tests are gaged, the cleverest pupils are recom- mended for promotion to special schools. word A model is shown, and the pupils give their idea of its Boys usually grasp the mechanical use and workings. idea better than girls ' January, 1921 sions of it. A picture is shown, and the pupils write their impres- Here girls do better than boys in their observation of details

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Out of the tall office-buildings pour the crowds of passengers who ride in the ‘‘vertical railway systems,”’ the elevators. Popular Science Monthly 4 In New York city more than twice as many passengers are carried vertically as are conveyed on the elevated trains, the surface-cars, and the subways Safety for Passengers Who Travel Vertically How the modern elevator is safeguarded EW YORK, the tallest city in N the world, has nearly a hundred buildings twenty or more stories high. If these structures were piled on top of one another, they would reach the clouds, where eternal snow would crown them. The total height of the skyscrapers of Manhattan is more than five miles, or nearly equal to the altitude of Mount Everest, the earth’s most lofty mountain. Millions of people are carried every day by street-cars, subways, and elevated railways through the thor- oughfares between and under the tal! buildings. In the dark canyons between the lofty structures flow other streams of humanity. But in the build- ings themselves is a most remark- able “railway’’ system that carries daily more than twice as many passen- gers as all the other lines combined. It conveys them vertically instead of horizontally, and has a greater factor of safety than any other transportation system, notwithstanding the fact that thousands more people are involved. More than seven million people are By Latimer J. Wilson SPEED \ GOVERNOR 3, > At the top of the elevator-shaft is a speed governor which spreads as the speed of a car increases. This auto- matically controls the switchboard and regulates the speed 26 within twenty miles of New York’s City Hall, a population nearly as great as that of the whole of Canada, and equal to that of half a dozen of our states combined. The traction lines carry daily about five million people, while the vertical “railways,” the ele- vators, carry twice this number at least. Every time a man rides in a convey- ance he is counted a passenger. In the subway, the surface-car, or the ele- vated, he rides from his home to his place of business and back each day; but in the elevator he makes two additional trips at noon; he is a passenger in the elevator four times daily, but only twice daily in the “horizontal” lines of travel. There are more elevator passengers than others, yet seldom are there accidents result- ing in death or injury. In the eleven years from 1907 to 1918 fewer than ninety people were killed in freight and .passenger elevators throughout Manhattan. Compare this figure with the casual- ties of the short interval of one year and seven months, a period equal to fer vi it: rh ma ww FH jm “eis ae Popular Science Monthly

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eat ind our nes le, ale- at ey- the ale- his ay; wo nes the are prs, ult- ven lan ght out lal- ear ' January, 1921 the duration of our participa- tion in the world war. In that time 126,000 persons were killed in the United States; 35,000 in industry and 91,000 outside of industry, of which about 19,000 were automobile accidents. What makes the elevator a safe conveyance, traveling hundreds of feet ver- tically along its peculiar track at a speed of six hundred feet a minute? There are the local eleva- tors and the express elevators, those that run twenty-eight stories without a stop and those that stop at every floor in shorter runs. All day they are making continuous trips, yet there is seldom even a delay in their operation, and the chances of an accident are exceedingly remote. What makes an elevator so reliable and so safe? Seven Safety Devices On the modern elevator no fewer than seven mechanical de- vices are used which assure safety and convenience. New York has more than ten thousand passen- ger elevators, all equipped with safety devices; the law requires it. The factor of safety in build- ings and bridge construction is such that every part of a building must carry from six to eight times its so-called ‘“‘safe load.’’ But elevators have not less than ten times the strength required for their limit of safety. Raise and lower the window of your room, and you have oper- ated the simplest kind of an ele- vator. The cords attached to the window pass over a wheel and are connected with a counterweight. It takes as much power to pull the window down as it takes to raise it, because when the window is lowered, the counterweight in the sill-frame that balances the weight of the sash must be lifted. With an elevator-car, whose weight varies as passengers are conveyed, the counterweight is made heavier than the actual weight of the empty car. This is done to effect economy in opera- tion as the load carried in the car varies. If the counterweight and empty elevator were of the same weight, they would be bal- anced as is the window-sash and its counterweight. But when the car is full of passengers, a greater strain would be thrown upon the motor than occurs when the counterweight is made slightly January, 1921 AUTOMATIC ELEVATOR MOTOR CONTROL SAFETY JAWS UNDER CAR FOR GRIPPING GUIDE RAILS a CAMS FOR AUTOMA,: STOPPING DEVICE OlL BUFFER ON COUNTER BALANCE LOWER TOW AY COMPENSATING a 7 OIL BUFFER CABLES FOR EQUALIZ! NG WEIGHT OF ROPES BRAKE UPPE! 4 HATCHWAY A LIMIT Life is full of ups and downs for the operator of an elevator-car. He travels hundreds of feet up and down the shaft, but he is guarded against a possible accident by various safety devices that are installed along this the safest of all railway systems 27 AUTOMAT STOPPING DEVICE ie UNDER CAR At the top of the shaft is the revolving sheave around which the cables pass. Near by is the automatic switchboard heavier to allow for an average number of passengers. Experiments with fully loaded cars have been made by cutting the cables and allowing the car to fall, in order to determine the proper distance in which to stop the car without injury to the passengers. It was found that it is not safe to permit the car to stop too suddenly, even in a short drop. If an elevator falling freely for one hundred feet were to be stopped within twenty-five feet of the ground, it would have to lose speed four times as fast as it had gained speed, which is equivalent to adding four pounds of weight to every pound of the passengers’ weight. Thus a man who weighed one hundred and fifty pounds would have to support on his legs a weight of equivalent to six hun- dred pounds additional to his normal weight if the car came to a stop in the short space of twenty-five feet. His frame can support the six hundred pounds if he stands erect. But if he sits in a frail chair, this enormous addition of weight would crush the chair and dash him upon the floor of the car. The Speed Governor But the modern elevator is so arranged that the car can not gain such headway. It is auto- matically brought to a comfort- able stop soon after it surpasses a certain speed limit. A speed governor is attached to the car, spreading outward as the car runs up or down. When the governor has opened a certain degree, it automatically operates the elec- tric switchboard at the top of the shaft. If the speed becomes ex- cessive, more than six hundred feet a minute, a contact on the

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governor closes, thus reducing the speed. If, for some reason, the speed still increases, a second contact opens, disconnecting the current from the motor and the brake through the operation of the controller, thus stop- ping the car. But if something has broken and this mechanism fails so that the car attains a speed of about eight hundred feet a minute, a safety rope unwinding .around a_ grooved drum under the car quickly throws outward two brakes that grip the rails to bring the car to rest. Then there are other devices that will not permit the car to run into the overhead mechanism should the opera- tor fail to stop at the top floor. At the upper and lower limits of the hatchway are devices which automatically bring the car to a gradual standstill, in case the operator fails to stop the car. But if there should be an unusual happen- ing to send the car beyond these de- vices, there is a final hatchway limit equipped with an automatic mechan- ism which instantly cuts off the current from the motor and applies the ma- chine brake. In the bottom of the shaft is an oil cushion buffer, under the car and under the counterweight, bringing the car to a gradual stop, in case the car reaches the bottom of the shaft at a speed too high, and yet not sufficiently high to operate the gov- ernor tripping device. What the Oil Buffer Does It is easy to see what would happen if an elevator-car should get out of control, starting to drop at a rate any- where between six hundred and eight hundred feet a minute. Now, if the tripping device operating the brake under the car were the only means of bringing the car to a stop, and if this device were set to operate at eight hundred feet a minute, the car might reach the bottom of the shaft before it had attained sufficient speed to operate the brake. A drop of only three or four stories would be a decidedly un- comfortable one to be halted sud- denly at the running speed to even six hundred feet a minute. Thus it is that the oil buffer at the bottom of the shaft is an added safety factor designed to meet any emergency - brought on . by a possible failure’ of some part of the mechan- ism at a criti- cal moment. Not all ele- vators are # WHICH ‘OIL S$ FORCED When the car strikes the oil buffer, it compresses the oil in a cylinder, pressing it out through graduated holes, the buffer thus acting as a cushion beneath the car. A similar buffer is placed under the counterweight equipped with all of the safeguards that make the chances of accident too remote to be considered. But the modern office- building, towering into lofty heights and having shafts extending hun- dreds of feet, necessarily takes no chances. Here all the safety devices are used, and the accidents that occasionally happen in such buildings are those due to persons fall- ing down the shaft or to workers who are careless. Theactual drop of a car with a crash is prac- tically an impossibility. The automatic devices are preventives more cer- tain obviously than the block signals on a rail- road system, furnishing a degree of safety that is amazing. Under the car are the jaws that grip the rails when the elevator exceeds a maximum speed 28 Popular Science Monthly Pe ee. ee ee ee ee ee | L eS ee ee ee Sarr Tes | Sets OMEP EL LELY: a ee ea en eeomprimecmmammnsessmeste: Fe OD — Srcampgramecerepesmeontes tes Section aoe ee x : ME RR IS I ELE LEIS rae et ORR ae * [ \ gems eee mene hy a7] i es | cepene £5 5 ae 7 Pe ) sere " —, | | Here is shown the various length of the “runs” of the elevator-cars in the tallest building, but it has many more shafts than are indicated. Throughout the hours of the business day thousands of passengers are conveyed safely up and down. There are twenty-six elevators in the Woolworth Building Jani ae 1 "6 thro tions flyin an a of al wate orde pum is sO the | abn¢ then able a pl to ¢ flyir inta ‘Tus witl anir kee] lubr thre

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January, 1921 The Typical Airplane Motor of Today Aeronautical experts are attempting to standardize it F the heart of a man is an imperfect organ, refusing to do its work of properly pumping the blood through the body when unusual condi- tions prevail, such as are met in stunt flying, that particular man can not be an aviator. So it is with the engine of an airplane. The engine, cooled by water jackets, and kept in running order by the flow of lubricating oil pumped into its operating mechanism, is somewhat like the human heart. If the flow of this oil is interrupted by an abnormal position of the machine, then that particular engine is not suit- able for work in the air. The Motor’s ‘‘Circulation”’ Here is an airplane engine with a pump at each end of the crankcase to aid perfect running during stunt flying. Oil is thus kept in circulation intact in abnormal positions. No “rush of blood to the head”’ is possible with this mechanical imitation of the animal mechanism, for the two pumps keep an even circulation of the vital lubricating fluid. The pilot’s winged chariot is driven through the air by “horsepower.” By C. Dienstbach It is curious to consider how the mod- ern airplane motor repeats history. The inventors of the automobile con- sidered four to eight horsepower more than sufficient for the first automobiles. They argued that if two horses could draw a carriage, the power of from four to eight would be ample for an auto- mobile. But to-day a whole stableful of horsepower is used for pleasure vehicles, while racing machines use considerably over a hundred horse- power. Similarly, the power for the typical airplane has risen from twenty to more than one hundred and fifty. The V-6 type of the Italian Isotta- Fraschini engine develops at normal speed from 250 to 260 horsepower. It is a two-stroke vertical six-cylinder water-cooled engine, which at normal speed gives the propeller 1650 revolu- tions a minute, and is capable of 1850 revolutions a minute at 275 horse- power. Rated at 260 horsepower, the engine weighs only two and one half pounds to the horsepower. Like other modern motors, this engine has its valve-operating mechanism next to the valves themselves, the camshaft RADIANS _ rae in | Wy Nccanust/ O NOWETTIBES being right on top of the cylinders, because this gives always the same action in spite of vibration and is almost free from wearing influences. The Perfection of Engine Detail Those who are familiar with gaso- line engines will recognize a note- worthy feature in the design of the cylinders of the V-6. These are com- posed of matched pairs from a steel ingot, and are complete with their combustion chamber and valve seats. Each pair of cylinders has a head from a single aluminum casting bolted on to the cylinder itself. The valve guides are contained in the cylinder heads, as are also the induction and exhaust ports, the camshaft, as indicated, rest- ing upon the cylinder tops. Steel water jackets surround each pair of cylinders, being screwed on the base and head of the cylinders. As seen in the picture, cavities for the cooling water surround the valves’ bodies, in- cluding nearly the whole stem of each valve. Since the exhaust valves are the most taxed, this system shows a decided gain in reliability, and it could be combined eventually with a one- piece all-aluminum design (ex- cept the lining of rubbing surfaces and valve seats). It will be noted that the valve springs are also thus positively shielded from heat. Typical also is the long stroke which gives more power through permitting higher pis- ton speed than it proportion- ally increases weight by longer cylinders. There is a certain best cylinder bore for the light- weight gasoline engine at which loss of heat to the cylin- der walls is lowest, which means greater power for little fuel, while tne cylinder can still bear up under the ever- increasing relative quantity of heat developed in cylinders of increasing size. The Italian V-6 type Isotta-Fraschini airplane engine might be con- sidered in many ways a typical airplane motor. Each pair of its cylinders is obtained from a single steel ingot, while the cylinder heads are from aluminum castings. The water-cooling system is complete

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Popular Science Month! The Electrical Effects in “Mecca” Using colored lights like paints on an artist’s palette By Latimer J. Wilson geous Oriental play, ‘“Mecca,”’ at the Century theater, New York, E. Braun, the chief electrician, has made use of colored lights as an artist makes use of colors on a palette. The scenery depends upon light for its effectiveness. How different is the same scene exhibited with different angles of illumination and in different colors! Nature’s outdoor lighting comes from the sky, so the scenes of ““Mecca”’ are lighted from above and footlights are practically dispensed with. The rays of morning stream slant- ingly across the scene, realistically pro- ducing the effects of sunrise. When the sun is low, its rays are red or am- ber, and the shadows are colored by light reflected from the overhead region of the blue sky. This is simulated on the stage by the use of blue lights hid- . the electrical effects of the gor- den in the “‘drops’”’ above, and intensi- fied by strong lights shining through blue filters obliquely from the side op- posite the rising sun. But how are these lights so regulated that they are neither too bright nor too dim, and how can they be changed from dim to bright? Look at the side of the proscenium from behind the curtain. There is a vast array of “‘dimmers,”’ controlled by the switch- board at which men are standing throughout the performance. These dimmers are specially devised trans- formers that alter the resistance to the electrical current. They cause the light to grow gradually from a faint incandescence to full brilliancy. More than half a hundred thousand-watt lamps are used, besides a number of sunlight arc-lights, spotlights, etc. A unique mechanical effect employed in “‘Mecca,”’ appropriate for this Ara- Thin copper strips illuminated from below and raised by a small motor, while smoke powder is burnt on a hot resistance wire, constitute the “torch” in ‘‘Mecca’”’ bian Nights type of play, is a substi- tute for the ordinary front drop used in most plays to cut off the stage while the scene is being shifted. At the close of a full-stage scene, a special drop-curtain is lowered, having in its center an opening less than half as encanta spe tsagieli ‘ THE DIMMERS AND SwITCH BOARD The small stage at the left is ‘‘set’’ as an intermediate scene to be rolled out to the front of the The dimmers and spotlights are seen at the side of the proscenium large stage. 30 Popular Science Monthi. Janu

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V2 V2 wm (YP OD ee pnd | | January, 1921 This illustrates the dramatic The fountain in ‘Mecca’ is lighting by spotlights and over- really a perfect mechanical foun- ‘head lamps in the production of tain whose pressure is supplied **Mecca.”” The unnatural effect by pumps under the stage. The of footlights is eliminated. water leaves the fountain basin Here the morning sun rays are through a drain and runs into represented by the arc spotlights an overflow tank under the floor at the right of the stage. Amber from which it is drained by a gelatine filters are superposed pipe extending into the regular before the side spotlights drainage system 2 Raa NE eMC comme Here is a scene on the small stage, ‘‘set’’ while at the side of the large stage. When the special drop-curtain is down, it is rolled into place in the front of the large stage and the two screens in the middle of the curtain are slid apart 31 Jonuary, 1921 wide as the full stage. This opening is covered by two sliding screens, which operate from the side like sliding doors. has previously been set for the scene to follow, and this is rolled into place behind the special drop curtain. The lights are turned on and the sliding doors are operated, disclosing to the audience the brilliantly illuminated little stage, with its characters in place to continue the play. The small stage is fully equipped electrically. It has its own switchboard and set of dimmers. The mechanical construction is exceedingly simple, and A small stage built upon a platform on rollers the frame can be quickly taken apart so the small stage can be shipped conveniently with the scenery from one city to another as the company travels about the country. Such an independent mechanical arrangement should meet the demand for amateur and small-town theatricals. It is so compact that it can be kept in the basement of a college or church, and easily assembled and made ready for the Christmas or com- mencement play, and for the numerous “‘little theaters’’ that have sprung up, it is invaluable

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Popular Science Monthi,, It is possible, with this invention, to trim twenty dozen brushes an hour in place of the five dozen done by hand SMALL and simple ma- Trimming Brushes by Machine toward the knife. chine—so simple that it may be operated by a blind man with- out risk of injury—has been invented by M. Vollet, a French engineer, for trimming the bristles or vegetable fibers of brushes. Heretofore an experienced work- man was able to trim five dozen brushes an hour by hand. With Vollet’s machine a blind man can trim twenty or more dozen brushes This Plow HIS plow is a hard worker. It bites into the deep snow like a hungry demon. Six horses are re- quired to pull it, but the horses do not furnish the motive power that actually removes the snow. A _sixty-horse- power gas-engine does that. The engine is mounted upon the steel frame and connected by chain drive with the two fast rotary cutters at each side. They cut into the snow and lift it high into two deflecting hoods placed above. The snow is dis- charged from the hoods as fine dust clouds at both sides of the walk. The rotary cutters are adjustable in order that the depth of the cut may be regulated. The cut made measures A brush-making machine so simply con- structed that a blind man can operate it in that time in spite of his handicap. The machine is built on the plan of a lawn-mower. Four paddles, set at an angle, are fastened to the shaft, with their outer edges operating against the sharp edge of a stationary knife. In front of the cutter an adjustable guide is fixed. The brush to be trimmed is placed in a groove of the guide and pushed Has a Great Appetite are needed when the machine is in operation. An operator for the plow is also necessary. It is the task of CONTROLS SNOW- DEFLECTING SNOW DEFLECTOKS (ON BOTH SIDES OF PLOW) ENGINE HOOD aca DRAFT RIGGING FOR HORSES ADJUSTABLE PLOW POINT WIDE- BLADED ROTARY CUTTERS (ON BOTH S DES OF PLOW) A sixty - horsepower gas - engine, mounted on a steel frame and con- nected by chain drive with the cutters furnishes the power The machine is built on the plan of a lawn-mower. Four paddles operate against the edge of a stationary knife The revolv- ing paddles press the brush part against the knife edge, which cuts the bristles, horsehair, or vegetable fibers at the proper distance from the back of the brush, which is then slipped out at the opposite end of the guide. By modifying the guide member, the machine can be adapted for the trimming of curved or irregularly shaped brushes. for Snow this [man to adjust the _ cutters and keep the gasoline engine in operation. In a test made at Westmount, Can- ada, the machine removed one thou- sand cubic yards of packed, frozen snow at a cost of thirty-five dollars and fifty cents. It would have cost fifty-three dollars to have removed the same amount of snow by hand shoveling. The hand method of removal also would have taken much more time. When the snow is too deep for horses to draw the rotary plow, a small tractor can be used. In the case of a tractor being used, only two men are necessary to handle the outfit. During a really heavy five and one half feet in width. The plow has been used in certain Canadian cities in removing a snow- fall as deep as three feet. In extreme cases, the rotary plow has been able to work its way through snowdrifts as deep as six feet. The plow can also be used on the street since it cuts a clean channel wide enough to accommodate a single line of traffic. If such a channel is cut on each side of the street; traffic can be NJ snowfall this new plow was able to keep twelve miles of sidewalks clean at a cost of thirty dollars and forty-five cents a day. The number of men it would replace in a case like this would depend entirely upon the depth of the snow and the rapidity with which it was falling. In a heavy fall it would probably replace a small army of men and save al least half of the cost in re- moving the snow from the streets. In country districts, . ~ Wy ’ res resumed with very little trouble. Twodrivers for the horses 32 Rotary cutters bite into huge snowdrifts, cutting into the snow and lifting it high into two deflecting hoods placed above; it is discharged from the hoods in fine dust clouds where men are scarce but roads must be kept open, this plow would be invaluable. Jounua

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Junuary, 1921 © Modern Publishing Company Drawing by S. W. Clatworthy A Thousand-Ton Concrete Ship Built in Units (CONCRETE ships are not new. We are familiar, more or less, with the pre-cast plate method, the mono- lithic hull, and the upside-down boat. But now comes the concrete ship built in units, with a resulting hull lighter than wood and more shipshape in appearance than the earlier concrete types. Moreover, it is admirably adapted to use as a motor-ship In Great Britain these motor-ships are being manufac- tured with a dead-weight capacity of from three hundred to one thousand tons. They are becoming very popular there, and will probably be so also in the United States. The drawing is numbered to show the order in which the units are cast and put together to produce the pleas- ing result shown in the detail at the top of the page

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Popular Science Monthly _ EXPANSION TAKE UP Courtesy of U. S. Forest Service Putting Out Forest Fires IREFIGHTERS trying to stem the roaring flames of the burning forest dash toward the clearings where the tall grass may be burned ahead of the fire to prevent a new nucleus of a conflagration from being started. In fighting the forest fires and in con- trolling the areas that are purposely being burned, a type of fire-wagon is employed which conveys a water-tank on the bed of the wagon. A pipe runs from the back of the tank so that the buckets of the fighters can be quickly filled. With the continuous supply of water furnished by several of these wagon-tanks, a number of firemen can be kept busy with the buckets. This arrangement is also good for the farm where large tracts of stubble land are burned. A Mechanical Coal-Picker that Hastens Production OOD coal, bad coal, and slate are all mixed together when they come from the mines. Later they have to be sepa- rated either by hand or machinery. Slate is heavier, rougher, and flatter than coal; thus it moves more slowly. The sorting machine below takes advantage of this. The coal and slate are released at the top of the chutes. After they have traveled a short distance, they come toa roller which they must pass over. Just beyond the roller there is a slot. Thecoal, being light and speedy, jumps across the slot and continues on down the chute; the slate, being heavy, falls through. As the coal cqgntinues on its way down chutes and over rollers until all the slate is gradually eliminated, breaker arms retard its progress to prevent it from gathering too much momentum. Levers at the sides of the chutes enable the operator to adjust the chutes to any angle, thus regulating to some extent the speed of operation. You Can Make Your Own Ice 6 ewe price of ice continues to rise with the rest of life’s necessities. This in- vention will solve the ice problem for those who will go to the trouble of constructing an icehouse. The device is nothing more nor less than a simply constructed form of galvanized iron with provisions made for the expan- sion of the water as it approaches freezing- point. A small amount of water is poured into the form and allowed to freeze. When frozen, the bottom of the form is sealed, and more water is poured in and allowed to remain overnight. In the morning the ice crop is collected. Homemade ice costs a fraction of a cent a cake, and it is as pure and clean as the water used. © Keystone View Company © Keystone View Company Rubber Bands for Rainy Days F you don’t like to wear rubbers in rainy weather, perhaps you will wear rub- ber bands instead—not the ordinary kind with which you fasten packages, but great thick ones that you wrap separately around the toe and heel of each shoe. Mr. Almeron H. Perry, of Washington, D. C., thought of this idea. The bands have thick, rough treads that touch the ground and raise your feet out of water’s way. Each band is of double thickness to make it secure, and it is fastened across the top of your shoe by means of a hook and eye such as are used on women’s clothes. Glasses for Testing Chimney Smoke OU guessed right. This is some kind of a ’scope —an umbrascope. It is used in large cities to see that industries do not dis- charge more smoke into the atmosphere than is lawful. At one end of the um- brascope there is a small peephole. At the other end a piece of colored glass is in place. The device is pro- vided with four pieces of colored glass, used either independently or together. The density of the smoke is determined by comparing its color with the glass. If the color of the smoke is darker than a certain piece of glass, the factory owner is warned. 34 Popular Science Monthly = Harri O% t ment, illumi ago G devel is bei furth Depa Alt three made venie cond conv Nort to de A the | trap M Can Ani mac turr witl Mr. the tati of t fat will ma the a Si

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~ werww \e J ww we er Oe ol ec ee ewe we US — a January, 1921 L C Harris & Ewing Making Gas from Straw OAT wheat, and rye straws, when in- tensely heated in a closed compart- ment, give off a gas that can be used for illumination as well as power. Six years ago George Harrison, a Canadian engineer, developed this new fuel, which at present is being subjected to experimentation and further development by the United States Department of Agriculture. Although from fifty pounds of straw three hundred cubic feet of gas can be made, as yet there has been found no con- venient way to carry it. If the gas can be condensed into a liquid motor fuel and thus conveniently used, the farmers of the Northwest will consider waste too valuable to destroy. Imitation Animal Tracks AN increasing number of fur-bearing +i animals must be trapped to supply the demand. Here is the latest way of trapping them. Mr. Raguvald Leland, of Birch Hills, Canada, has invented a luring-machine. Animals will invariably follow footprints made by one of their kind; this machine turns out imitation footprints. It is a sled with spurred wheels on either side. When Mr. Leland pulls the sled across the snow, the wheels turn and actuate a pair of imi- tation feet that extend beyond the rear end of the sled. They are coated with animal fat so that the keen nostrils of the animal will not detect any strange odors. The man’s footprints and the tracks made by the runners on the sled are obliterated by a scraper at the rear end of the sled. ‘ « ‘ Se encxmannc LEVER : a SRRAPER Pry) 4 January, 1921 To Simplify Perspective Drawing “TRACKS seem to approach each other as you look down them, until, at a vanishing point, they seem to touch. Perspective drawing is the art of pictur- ing things on a plane surface as they appear to the eye, and in consequence there must be a left and a right vanishing point. W.A. Moore of Welland, Canada, has recently invented a rolling perspective ruler that eliminates much of the work necessary in perspective drawing. The rolling ruler is mounted on a flat base that has scales on the edges. One end is fastened to the paper at the vanishing point, and the other end is left free to rotate. You Can See the Hot Air Rise from the Hand ee a dark room place a concave mirror upright and opposite it a bright light so screened that it shines only through a pinhole. The distance of the light from the mirror must be the center of the curvature radius, and the eye looking at the mirror must be close beside the source of light. The mirror will appear evenly illumin- ated. When an opaque object such as the straight edge of a knife is partially passed across the cone of rays at the exact spot previously occupied by the eye of the observer, the illuminated disk as seen from back of the knife’s edge will appear slightly darkened. Now get some one to hold his hand about three inches from the mirror. The different densities of the air caused by the heat rising from the hand will become plainly visible. © Harris & Ewing Testing Strips of Shoe-Leather ILL they wear weil? That's the first question you ask when you find a pair of shoes you like. All sole-leather looks very much alike, and it’s hard to tell the good from the bad by the eye. The government, however, has a new machine for testing it. Strips of various makes of leather are nailed to the face of a revolving wheel. Directly beneath the wheel there is a sanded belt. As the wheel revolves, the leather strips brush across the belt with the pressure of a man’s step. After such a test it is easy to tell which leather is best. It is our opinion that many members of the leather trade have omitted this test. Bossy’s Wearing Stockings Now HOULD a fly bite you, you would swat it. But when a fly bites a cow, she can’t retaliate—she hasn’t anything with which to swat it effectually. And so she kicks futilely, swishes her tail, and fre- quently knocks over the pail of milk. Some lover of animals has thought cut a way to save poor old Bossy such constant irritation. This man tried fitting her with a pair of ladies’ cotton stockings, size eight. They may not be a particularly good fit, because of the cow’s peculiarly shaped leg, but at least they will foil the machinations of the flies. The idea originated in Illinois. If other cows in other states follow suit, specially shaped stockings may be made for them, and the hose industry receive a boost from an unexpected direction.

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Popular Science Monthly How Thieves Camouflage Stolen Cars “C@TOLEN—a seven-passenger touring-car,” is not an uncom- mon message at Police Headquarters. When the police get a report like this, they watch out, naturally, for a large touring-car. But the thieves may have changed its shape in the meantime. Take, for example, the automobile shown above. As you see, it is a roadster having two seats. Originally it was a seven- passenger car. The men who stole it re- moved the entire rear end of the body and substituted for it boards and canvas. Disk wheels added to the disguise. It was through a mere chance that the police found the car. Such cases emphasize the importance of placing secret distinguishing marks for the better identification of your car on those parts of the automobile which the thieves in all likelihood will not, or-cannot, remove. It Warns of the Page’s End HE attachment invented by M. G. Navarre, shown in the accompany- ing picture, informs you that the last line of your typewritten page is reached. It has a disk with fifty or more ratchet teeth. It is pivoted to a plate that is fastened to the machine. The disk has a movable indicator, bearing a small button. This may be set for any number of lines, single or double spac- ing. Every time the line-shifter is operated, the lever engages the ratchets and turns as many spaces as are needed. When the required number of lines are written, the indicator will be in a position to signal the completion of the line by a warning bell signal similar to that of the line indicator. Going Calling in ‘‘Darkest’’ Africa “ AFRICA” has a mysterious and terrible sound to most people. They think of it as populated with wild, unruly was taken there. Dumping Hot Ashes from an Aerial Wire At the reduction plant of a California quicksilver mining company an air railway is being used for transporting red- hot calcines to the dump. The rotary furnaces from which the cal- cines are discharged are in a parallel row and spaced about twenty-five feet apart. Each furnace discharges its calcines into a small hopper, from which they are emptied into a two-ton bucket. This bucket travels along the line of spouts, and receives the discharge from each hopper before travel- ing to the dump. The tramway cable is supported by two wooden towers. It is eleven hundred feet long and travels at a height of one hundred feet. The bucket weighs nine hundred pounds and has a carrying capacity of four thousand pounds. It is dumped auto- matically by a tripper device. savages—a place where white men, and particularly white women, fear to tread. Yet the photograph reproduced above As you see, a white woman sits in a comfortable rubber-tired wheel chair propelled by two good-natured blacks. She is starting on a round of calls, and she ap- pears to be perfectly satisfied with this means of travel. The chair is very in- geniously constructed to keep the center balance on its one wheel. The house she lives in, which is shown in the background of the picture, is very modern; it was built on a firm brick foundation. Many American flat-dwellers might covet her comfortable home in the wilds of the ‘‘Dark Continent.” Squeezing Out the Last Drop UCH has been said and written of the need of thrift and economy in every phase of the trivial round and common task. Above is given yet an- other instance of getting the most out of everything—even of a twisted, tortured old tube of tooth-paste. In order to squeeze every bit of tooth- paste out of a tube, you must do two things. First, be very sure to screw on the top each time after you use it. This prevents the paste from becoming hard and unsqueezable. When you have reached the bottom of the tube, take a small glass bottle and roll it over the flattened tube. The last few drops can then be squeezed out—much as you would flatten out dough. Popular Science Monthly Ja

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January, 1921 ee A Drill that Rivals a Shell HEN a fourteen-inch shell screeches its way through the air, men stand aghast as it crashes into armor-plate, burying its nose in the fracture. When a super-hard steel drill, revolving at five hundred revolutions a minute, plunges through armor-plate, a keen interest is awakened in the observers. A milled high-speed drill has broken all records by the speed with which it can penetrate metal. Making six hundred revolutions a minute, it bores through tough machinery steel at the astonishing rate of thirty inches a minute. Making seven hundred and fifty revolutions a minute, it plunges through seventy-two inches of cast-iron, while it can travel through 9.2 inches of hard armor-plate in one minute, making two hundred and thirty revolutions. Waste Paper for Packing “D? not waste the waste paper!” should be posted everywhere. Not only can it be made over again into new paper, but it can be used as packing material. For this purpose there are special stripping machines which cut the paper into small strips. These are dumped into a “‘baler’”’ and pressed. There are several types of machines used for cutting paper. One is suitable for an office and is driven by a 1.5-horsepower motor. Twelve thicknesses of paper can be cut through by some of these waste-paper machines. Dropping Caps Down a Tube to a Threading Machine EEDING screw caps to a threading machine—that’s what the girl in the picture is doing. One by one, she picks them out of the bin in front of her, and drops them down a small tube at the side of the bin. When they reach the bottom they are grasped by the revolving machine chuck. This machine rolls threads on shells, even when the neck is as small as one half inch in diameter and the flange as large as three inches. This method of feeding means absolute safety for the operator. She sits on a platform at the side of the machine and is well out of its way. She climbs to her post by way of a short flight of steps. Any device that makes for safety for factory workers is bound to reflect in added production. However, it is not always easy to convince factory managers or owners of this fact, and so there are con- stantly being added to the statutes of the various states laws for the protection of the workers. It Measures Water for Concrete N automatic water-measuring device 4 has been invented to enable the concrete-worker to gage the amount of water required for the various grades of aggregate. With weather conditions known and a known quality of aggregate, a fixed supply of water is required. This can be regulated by the automatic tank. The tank ‘is filled from the water supply for each batch of concrete. It is fed into the tank through the bottom after passing through a three-way valve. When the handle of the valve is set to the emptying position the inflow of water is automatic- ally stopped. The outflow is controlled by the regulating valve set to give any desired amount of water. This valve consists of a spherical housing in which is set a bronze plug to which is attached a short pipe. For Honest Scales 7 VERY few years the public finds it is being cheated, and a campaign is started for honest scales. In Denver a campaign is now being carried on. Mrs. Jones buys a pound of meat. She then takes it to an “official free city scales’”’ booth, and has it weighed. If it is not an exact pound, she receives a certificate, which she takes back to the butcher, demanding her money’s worth. Duplicate certificates are kept by the official weighers. If several bear the name of any one merchant, the city in- spector visits him. January, 1921 SCALES — FROM Lee

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Lock Your Car from the Dashboard NEW automobile lock has been intro- duced that cuts off the gasoline at the carburetor, although it is operated by a button on the dashboard. When you wish to lock your car, you pull out the button just as, in some cars, you pull out the ignition button to shut off your en- gine. If you lock it at night in the garage, you will prevent possible gas leaks and fire. The button is attached to a cord con- nected with a lxcch on the lock. When the cord is pulled, the latch is turned and the lock locked. When you wish to start your car, you lift up the hood and use a key to release the lock. The operation is so simple that in a short time it becomes second nature. Bracing the Riveter ELOW is pictured a compressed-air tool that is a great help to the riveter. It is nothing more nor less than a piston and a cylinder. It is put in place in a boiler as shown, and air is allowed to enter the cylinder. This forces the piston out, and the tool then acts as a brace inside the boiler. It also holds the rivet in place while the workman on the outside of the boiler uses the rivet- ing hammer on it. All strains are taken off the boiler in this way. Otherwise the hammer on the out- side would be apt to knock the boiler out of true. Such a pneumatic brace will find many other uses about the large shop. For in- stance, it may be used in forcing pieces in place instead of using a hammer. It is a handy tool for applying pressure wherever needed. A small compressor will supply the tool with sufficient air. oad ff , rete aid hitiii It Blows Wherever It Goes HIS is a wandering blower. It is ready for duty at all times in any part of the factory or garage. It is necessary only to push it to the place where it is needed and connect it to the electric circuit. A steady flow of high-pressure air is available, which may be used for a multitude of purposes. Keeping the delicate machinery and electric motors of the factory free from dust is only one of the important uses of this new outfit. It will deliver six cubic feet of air a minute under a pressure of two hun- dred pounds to the square inch. This is sufficient to inflate the largest automobile tires. An attachment may be used with the blower that will spray gasoline on machin- ery to clean it of accumulations of grease and dirt. Popular Science Monthly A Tool for Wrecking Walls and Ceilings F one desires to remove the walls and ceiling of a house, here is a tool, in- vented by Edward F. Wilkinson, of Gramercy, Louisiana, that will do away with the bother of erecting a scaffold. The iron bar is sufficiently long to reach to the ceiling of the average room. It is particularly adaptable to the removal of tongue-and-groove boards. After the nails have been extracted by the claw, the first board is pried out by the chisel edge. The shank is pressed down through the open space and the feet of the device are en- gaged with the next board, the lower foot be- neath, and the upper foot above the board. A lever movement is exerted, which has the effect of lifting the board out of its place in the ceiling or the wall. Drilling Made Safe HEN using compressed air or electric drills of the larger size in drilling and tapping out boiler-plate, workmen are sometimes injured if the drill or tap hap- pens to break or catch in the work. Some- times the drill pulls itself out of the work- man’s hands and whirls about with terrific force. To prevent this, the little guide shown below is brought into use. This is placed into a hole in the boiler and the handle of the drill is slipped in place. The drill is free to move backward or for- ward, but it cannot turn around. The guide also helps to keep the drill moving in a straight line. The same device can be used in con- nection with high-power electric drills, since accidents are liable to happen with these as well as with the compressed-air drills. This is a solution of a problem that has cost thousands of lives. 38 Popular Science Monthly Janua Sh Soe loo able s' glisten “Isn’t An | the n¢ beauti a skat comfo: The is not that s heels. heels bite ir M H° t bread, to ma Here aid, c: At mech¢ bread baked labor, cision Eve seven of thi prepa of the ©}

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January, 1921 She Isn’t Afraid of Slipping yore morning in midwinter, when you look out of a window of your comfort- able steam-heated room and see the trees glistening in the sunshine, you exclaim: “Isn’t nature wonderful!’ An hour later, though, you discover that the north wind that made the world so beautiful has converted the sidewalks into a skating-rink, and walking becomes un- comfortable and dangerous. The young woman in the picture above is not afraid of the iciest pavements, now that she has a pair of ice-spikes for her heels. These spikes are attached to the heels by straps, and their sharp prongs bite into the ice with every step. Making 360 Loaves an Hour OW long would it take a baker to roll the dough and shape 360 loaves of bread, or how many bakers would it take to make this number of loaves in one hour? Here is a machine that, with scant human aid, can mold sixty loaves a minute! At the rate of a loaf a second, this mechanical ‘‘dough-molder”’ turns out the bread ready to be sent to the ovens and baked. It is a device that not only saves labor, but simplifies it, working with pre- cision and speed. Even so, working eight hours a day, seven days a week, more than six hundred of these machines would be required to prepare one loaf of bread a day for each of the inhabitants of Manhattan. © Keystone View Company This Girl Pedaled Almost Across the English Channel Peceeraes the English Channel by air- plane has become very popular, chiefly because of the unpleasantness of the rough trip by boat. Yet here is a young girl who calmly decided to pedal her way across. Her bicycle is mounted on a pair of cylindrical pontoons, and the rear wheel is equipped with small paddles instead of a tire. These paddles make the bicycle- ship move when the pedals are worked. Miss Hill, the captain of the ship, made a good start, and she was within three miles of the English coast when the waves became too much for her. Her ship over- turned and she had to continue her journey in a boat. We congratulate this daring young woman on achieving that much of her journey, and we should like to inquire whether she felt any tendency toward sea- sickness. Perhaps in the excitement of this unusual crossing she forgot the Channel’s reputation in this direction. The picture above shows Miss Hill snatching a hasty lunch on her way across. © Kadel & Herbert A Bicycle Side-Car for Baby F course, side-cars are not new, but they have not been used extensively in connection with bicycles. This man thought it would be practical to make one for his baby girl. He produced the sub- stantial attachment shown. The car itself is suspended on springs, which make it very comfortable to ride in. The frame is made with standard pipe and fittings. The wheel used is similar to the front wheel of a bicycle. A celluloid windshield and a small leather top, to keep out the sun and rain, complete the outfit. It’s nice for baby, and not too hard on dad. Ringing the Duck T does not seem so difficult to toss a light ring over a duck’s neck, but try it and see! In Germany this has developed into a sport, “ringing the duck.”’ For five marks a player has three chances to throw the ring over the duck’s head. If he wins, he gets the duck. This game is less inhumane than that of ‘“‘wring- ing the goose,’”” considered a legitimate sport by some. The goose is hung by its feet while horsemen ride swiftly by, trying to pull off its head. As the bird’s neck is greased, it undergoes considerable tor- ture before the neck-wringing is accom- plished. In the case of the duck no such in- humane treatment is practised. © Kadel & Herbert es ance vere OV 1

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Dr. John A. Harriss, New York’s mil- lionaire Special Deputy for Traffic, who has spent many years in a study of New York’s peculiar traffic problems, and who installed the present block traffic system on Fifth avenue at a personal expense of twenty thousand dollars Popular Science Monthly . Speeding Up Traffic on the World’s Busiest Corner How Dr. Harriss modified the railway block- P AHE traffic problems of New York city, per- haps the most difficult and complex of any city in the world, and assuredly of any city in the United States, are not solved by a group of heavy-browed ex- perts gathered in solemn conference around piles of maps and charts and blue- prints. They are solved by one man—a tall, broad- shouldered, keen-eyed man who stands hour after hour, looking out of a window of his office upon the mael- strom of vehicles and pe- destrians that is Forty- second street and Fifth avenue, thinking traffic and seeing nothing but traffic until suddenly an idea leaps full-fledged into his brain, and then, presto! — new traffic rules are promul- gated and New York city takes one more step toward the traffic millennium when there will be no accidents and when motor vehicles and pedes- trians will move east and west and north and south in perfect peace and harmony. New York's Special Traffic Deputy This man is Dr. John A. Harriss, Special Deputy Police Commissioner for Traffic. It is a big job with a big title, but for the long hours he puts in and the hard work he-does Dr. Harriss receives probably the smallest pay of any man in the world. He receives exactly nothing—or even less than that, because, being an ex- tremely wealthy man, he never asks the city to pay for putting his new traffic ideas into effect until he is certain that they will be success- ful. He pays out of his own pocket whatever expenses are in- curred in giving them a thorough test, and then, if they justify it in the opinion of the Police Commis- sioner and the other city officials, tne municipal authorities take hold and continue the schemes. The most that Dr. Harriss ever gets out of his work is a letter of thanks from his boss — that and the knowledge that he has contributed to the safety and the hap- 40 signal system and applied it to Fifth avenue By Herbert Asbury and Joseph Brinker piness of some millions of his fellow citizens. And that in itself, of course, is no mean reward. Between five and six o’clock in the evening approximately 4500 vehicles pass the corner of Fifth avenue and Forty-second street. If the vehicles going in both directions were evenly divided, it would mean that 2250 vehicles would go north and 2250 vehicles south on Fifth avenue within the hour. Expressed in minutes in- stead of hours, thirty-seven vehicles pass the corner traveling north every minute and an equal number travel- ing south. Since Fifth avenue is wide enough for only three lines of traffic in each direction simultane- ously, thirteen vehicles, three abreast, thirty-seven or thirty-nine in all, pass the corner every minute in each di- rection. Fifth Avenue in a Rush Hour Try to form a mental picture of thirty-seven vehicles passing the cor- ner every minute going north and thirty-seven more going south simul- taneously. Then consider that there are almost half as many vehicles wait- ing to cross this heavy stream of traffic in order to get from one side of Fifth avenue to the other, and the traffic jam becomes more realistic. Consider, too, the thousands of pedes- trians waiting to cross from one corner to the other. Mix these up with the north- and south-bound vehicles and those bound east and west, and you have some idea of conditions at the most congested vehicular corner in the world. Picture also the pedestrians trying to worm their way through the streams of vehicles, some of them the costliest of limousines, moving ahead less than a foot apart, and you get a still better picture of the traffic jam that used to occur every night at that famous corner. We say “used to occur,” for this condition has been entirely changed. Many of us remember the curious uttle platforms surmounted by lamp- posts—safety isles, they were called— that used to dot Fifth avenue at vari- ous corners from Forty-second street north. It was Dr. Harriss who inves- tigated and found that a great many accidents were caused by the safety isles becoming overcrowded with pe- destrians, some of whom were pushed J anue ( ft in ibolis ind t ment reduc iecid riss Y city, such Cent unus accic agail an e€ traff thet The abo. fic 1 sout it ft wes veh gol! per For slov thir cor blo twe ty- tra in | Popular Science Monthly Ja

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January, 1921 off into the paths of automobiles. He abolished them, had them destroyed, ind the records of the Police Depart- ment immediately showed a decided reduction in the number of traffic iecidents on those corners. Dr. Har- riss made radical changes all over the city, making one-way streets out of such an important artery of travel as Central Park West, which showed an unusually high percentage of the city’s accidents—and traffic conditions once again showed an improvement. Many schemes were tried out in an effort to speed up Fifth avenue traffic, but they all failed because the underlying principle was wrong. There was no uniformity of travel above or below the congested corner. The Traffic Was Chaotic At Forty-second street the traf- fic might be proceeding north and south while at Forty-third street it might be proceeding east and west, with the result that the vehicles passing Forty-second street going north had to come to a stop to permit the east-and-west travel at Forty-third street. This, of course, slowed up traffic, and when the same thing occurred at ten or fifteen other corners along the twenty-three blocks from the congested area be- tween Thirty-fourth street and Fif- ty-seventh street, it created such a traffic muddle that the authorities in charge became alarmed. During one test period it was found that it actually took one vehicle forty minutes to pass from Fifty-seventh street to Thirty-fourth street, a dis- tance of slightly more than a mile. This was at a rate of less than two miles an hour! The next step in the plan was a pro- posal for one-way traffic going south on Fifth avenue from ten o’clock in the morning until five o’clock at night, with all northbound traffic shifted to a © Underwood & Underwood What the towerman sees from his box overlooking Fifth avenue. Probably more individuals pass his house in a day than many persons see in a lifetime The traffic on the cross streets is guided entirely by the movement of vehicles on the avenue, resulting in a slight delay in starting. Here is a suggestion for installing signal lights in view of the vehicles on side streets January, 1921 41 Park avenue, two blocks farther east, during the same period. This plan included tower signals erected along Fifth avenue to assist in the traffic movement. Although this one-way traffic plan was never actually put .into effect because it was shown to cause more instead of less confusion on such an important thoroughfare, the towers erected were retained and employed in the present plan of two-way traffic, which has reduced the running time between Fifty-seventh street and Thirty-fourth street from forty min- utes to less than ten minutes, or more than seventy-five per cent, and, in the bargain, has permitted from twenty-five to fifty per cent more vehicles to use Fifth avenue with less congestion than ever before! What the Towers Have Done The secret of this wonderful achievement is that the towers have made it possible for all vehicles going north or south on Fifth ave- nue within the congested zone to move at the same time and to stop at the same time to permit the crossing of traffic on all the inter- mediate streets between Thirty- fourth street and Fifty-seventh street. In other words, traffie on Fifth avenue is now practically contin- uous in movement, except during stated intervals, when it is inter- rupted to permit cross traffic on the intermediate streets. No longer is traffic moving north and south on Fifth avenue at Forty-second street and east and west at Forty-first street. It is moving north and south across all side streets at once, and across Fifth avenue at all side streets at other intervals. Vehicles move between one tower and the next in much the same manner as trains controlled by the block sys- tem of the railroads, except that when north-and-south travel is stopped, the vehicles must halt at the nearest street intersection, no matter whether it is at the tower or not. It is just this continuity of travel that has speeded up traffic and made Fifth avenue the fastest congested street to travel on in the world. How the Signals Work It is the block-signal-tower idea that has been responsible for the successful working out of the prin- ciple in practice. Each tower con- sists of a small boxlike house set up on steel stilts, with the floor of the house twelve feet from the roadway so as to give its occupant a clear view of the roadway from one

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tower to the next. Besides a fixed white light that is used as a position light when there is no traffic regula- tion—for instance, in the middle of the night—there are two sets of three other lights on each tower, one set facing north and the other set south. Each set of lights consists of an amber-colored lamp, flanked on one side by a green lamp of the same size and on the other by a red lamp. When the amber lamp is lighted, it is a signal for traffic to move north and south along Fifth avenue, with east-and-west traffic in the side streets at a standstill. When the green lamp is lighted, it indicates that the north- and-south traffic is to stop to permit the vehicles in the side streets to cross Fifth avenue. The red lamp is used in order to flash a warning signal that the direction of traffic is about to be changed from the north-and-south to the east-and-west direction, or vice versa. The red signal is always shown be- tween the amber and green signals, and indicates that the vehicles in mo- tion at the time must stop to permit traffic to resume at right angles to the line then moving. The time interval between the flashing of the red signal and the amber or green one following it permits the street intersections to be cleared, so that there is no delay in changing the direction of travel as soon as the signal is flashed. This is the theory of the system of continuous traffic. One Man Controls All Signals There are five signal towers, one at Thirty-fourth street and one at Fifty- seventh street, with three intermedi- ate towers at Thirty-eighth, Forty- second, and Fiftieth streets. The tower at Thirty-eighth street is not used as a block or stopping-point, but is required to flash the signals between the tower at Forty-second street and that at Thirty-fourth street because the street level at the latter street is much lower than that at Forty-second street. The flashing of the signals at all the towers is controlled by one man in the tower at Forty-second street. He employs an electric push-button bell system to notify the men in the other towers that he is about to change signals. This ringing of the bell gives the operator in each tower a sufficient interval of time to enable him to change the signals on his own tower simultaneously with the other opera- tors. All the towers are connected by telephone in case the bell system should get out of order. Traffic Direction Is Scheduled The signals are in operation from nine o’clock in the morning until mid- night, and apply not only to vehicular traffic but to pedestrian crossings as well. The time allowed for north- and-south and east-and-west travel © Underwood & Underwood The master signalman in his tower at the corner of Fifth avenue and Forty-second street. He controls the lights in all the five towers, signaling the other towermen by means of an electric bell system The five towers that control the block traffic system aad installed by Dr. John A. Harriss, New York’s Special Deputy for Traffic. They extend from the shopping district to Central Park. Each tower has two sets of lights, one facing north and the other south. Each set consists of an amber-colored lamp, flanked on one side by a green lamp and on the other side by a red lamp. These lamps flash their lights alternately. 42 Popular Science Monthly depends upon the time of day. From eight until ten o’clock in the morning, north-and-south traffic moves in p>- riods of one and one half minutes, wit}! east-and-west traffic at forty-second intervals. From ten in the morning until seven at night, the north-and- south interval is increased to two min- utes, with the east-and-west period remaining at forty seconds. From seven in the evening until midnight, the north-and-south period is still two minutes, with the east-and-west in- terval reduced to thirty seconds. The red light to indicate a change of traffic direction is flashed for five seconds at all times. While the traffic system is by no means perfect as yet, the great speed- ing up of traffic that it has made pos- sible gives promise that it may be introduced on still other streets as New York’s vehicular congestion be- comes more and more serious. While it is difficult to estimate the saving effected in dollars and cents since the new system was installed, it is prob- able that the entire cost of the instal- lation is saved every day it is in operation. An average of 4500 vehicles an hour for ten hours a day means 45,000 vehicles using the avenue. If thirty minutes are saved each vehicle in moving from Thirty-fourth street to Fifty-seventh street, the total time saved is equivalent to 22,500 hours. Estimating the time of the occupants of the cars using the avenue at the low average of one dollar an hour, the system would save $22,500 a day or $6,750,000 for a 300-day year! Suggestions for Improvement Perhaps it may be possible to im- prove the system so that one man can operate all signals. By electrical con- trols, one man in one tower could change the signals on his own tower and the other four without the neces- sity of passing the word along to a man in each tower who does nothing more than open and close an electric TOWER 4 The amber light indicates north-and-south traffic, the green light indicates east-and-west traffic, and the red flash signals that the traffic direction is about to change and everything must stop for afew seconds. It has been estimated that the cost of installation of this system is saved every day it is in operation swit« signe It m sets gree. site | side- aver oper side not ther trafl offic sect! Fopular Science Mont})’),, Tana

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& = at January, 1921 worse, and entangled the prob- lem in a maze of red tape and pompous Official direction. He de- cided to learn all there was to learn about traffic, so he went to London and Paris and Rome and Berlin and Vienna, and for month after month he traveled and looked and listened and talked to traffic ex- perts in the four corners of the earth—and then he came back to the United States to wait for a chance to put into execution some of his new-found ideas and knowl- edge. Dr. Harriss’ Appointment That chance came when Richard E. Enright, New York’s Police Commissioner, made Dr. Harriss Special Deputy for Traffic, and it was not long after that event that motorists and pedestrians began to notice that the handling of the traffic in the metropolis, Should the new traffic signal system be extended to streets on which there are street-cars, the tower might take the form of a bridge of light steel built over the street, with the towerman’s box in the center switch in accordance with the bell signals from the one controlling tower. It may also prove possible to install sets of three lights, amber, red, and green, as on the towers, on the oppo- site corners of buildings at each of the side-street intersections with Fifth avenue. At the present time the operators of vehicles waiting in the side streets to cross Fifth avenue can- not see the signals on the towers, and there is a slight delay in beginning traffic across the avenue unless a traffic officer is stationed at the street inter- section. Every One Must Help The key-note of Dr. Harriss’ cam- paign to make New York city’s traffic the best handled in the world is coop- eration between the pedestrian, the business man, the motorist, and the police. He says: “For one man to attempt unaided to find the solution of a problem that presents so many factors, commercial, social, and municipal, would be mani- — eer 7Q07 festly impossible. The officials who have to do with traffic in New York must depend upon the cooperation of the police, automobile owners, chauffeurs, and owners of business establishments and places of amuse- ment. “The innovations that I have put into effect have been largely adapta- tions of well known principles of busi- ness efficiency. They provide for the elimination of needless waste of time, the recovery of lost motion, the pre- vention of friction, confusion, and misunderstanding. They should suc- ceed because they take into account the spirit of sportsmanlike teamwork and the unfailing good ‘nature which is typical of American crowds. And without the cooperation and sympa- thy of the people, rules and regulations are of scant avail.” Dr. Harriss became interested in traffic regulation many years ago, when as a motorist he was continually coming in contact with laws that were supposed to control traffic but that in reality only made a bad matter TOWER 43 always the best in the United States, was becoming even better; the police were more efficient, there was more system to the work, and there was an all-around improvement that brought joy to every one who traveled in automobiles as well as those who had to jump out of their way several times during the day. Dr. Harriss recently returned from a trip to Europe, where leading traffic experts in London and Paris listened with great attention to his latest ideas for making city street congestion less costly in lives and money. It is said that the London authorities are con- sidering the installing of the Fifth ave- nue system in that most congested city in Europe. With such a man as Dr. Harriss at the head of New York’s traffic depart- ment, surely every citizen of the me- tropolis will not begrudge the little thought required to obey the rules as laid down by that department. As before stated, with the full cooperation of every man, woman, and child — the latter trained by the schools to observe traffic regulations—the prob- lems and complexities of modern traf- fic without doubt would be consider- ably simplified. TOWER 1

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Popular Science Month! @ oe . oi Se eee QPP eaceseereee DRE LR 2 ap GE a ME ss om 32 . x #; Seine 2 9 OES YE wu. — 3 re 4 tees Ne hs TD i ad 2 pena # ¢ +s © Modern Publishing Company HARING CROSS station in London is one London’s Five Levels of of the busiest spots in the world. It is the main junction of the underground railways, where 2290 trains stop daily. In one day 190,000 M ° ° ordinary ticket-holders enter and leave the sta- anaging the public at one tion, together with 32,000 season-ticket holders. The station carries traffic at five levels. About twenty-five feet above the Victoria suspension bridge, which it replaces, extending Embankment, Charing Cross railway bridge across the Thames. A double tramway track marks the location of the historic Hungerford occupies the outer edge of the Embankment, Popular Science Monthly

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Y Terminal Ra "lara tte 7 12° "tee ee . HE fe I aes SOT Stig

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Popular Science Monthly Measuring the Home-Brew Kick Various methods of keeping within the eighteenth amendment OW high does the home H brew kick? In these days, the citizen desiring to keep his elixir of malt and hops or his wine within the half per cent limit, can find simple devices by which he can know the amount of alcohol in fluids of his own bottling. All methods for findirg the strength of the brewed beverage are based upon the differences between the fermented and the unfermented liquids. When a cake of yeast is put into the wort or the kickless beer, it splits up the sugars and malt into aleohol anda gas quite the same as that which bubbles up through soda water and other soft drinks. Much of the gas escapes into the air, and the alcohol mingles with the water of the brew. As alcohol is lighter in weight than water, it follows that the beer is of a different density than it was before fermenta- tion began. For the purpose of find- ing out the relative or comparative densities of liquids, the hydrometer or ‘‘water measure”’ is used, and the instrument which is best suited for register- ing the home-brew kick is a type of this appliance. The common hydrometer consists of a glass bulb, drawn out at one end into a thin stem and at the other into a smaller bulb, which is weighted with quicksilver or fine shot. When it is put into a liquid, it bobs up and down for a few seconds, until it comes to an even balance. The weighted end holds it at rest, while on the scale placed within the hollow stem you may read numbered degrees, which show the difference between the liquid being tested and plain water. The result obtained is based on the fact that when a solid floats in a fluid, it shoves out of its way as much of that liquid as is equal to its own weight. Instruments of this kind are dropped into tall glass jars filled with the liquid to be examined, which naturally, as it is forced out of place by the floating weight, rises higher in the vessel. If

made a ee ae. : a” <

This is the Balling sac- charimeter, a carefully instrument de- signed for the guidance of brewers. how much alcohol is ter present by telling how ' much sugar has been lost in the brewing By John Walker Harrington The year 1921 finds home brewing among the favorite indoor sports. Our readers will be glad to learn how to eliminate the forbidden kick they are put into a liquid heavier than water, they do not sink so deep. Every swimmer has noted that he floats more easily in the heavy briny waves of the ocean than he does in lighter fresh water. If the liquid is of lower density, more of it must be displaced before the weight of the instrument is supported, and it ceases to rise and fall. If the home brew con- tained only alcohol and water, it could be quickly tested with the hydrom- eter here described. Many dealers in malt and hops and home-brewing sup- plies, who ought to know better, have been selling this instrument to their customers. It will give accurate readings, if care- fully made, by which one can find out the strength of whatever whisky or brandy he may have saved as a relic of the dear, damp days beyond recall, since those fluids contain very little dissolved solid mat- because they have been distilled. Beer and ale, as we have seen, are heavily loaded with sugar before their fer- mentation and after fermentation are still denser than the rill, on account of the malt and coloring matter and other substances which the water in 46

It shows

them has taken up. Realizing that, the brewers make use of a specially constructed instrument, based on the principle of the hydrometer, but with a different scale, which tells how much alcohol is present, but in an indirect way. It is called a saccharimeter or, in other words, “sugar measurer.” No beer is properly made which still tastes of sugar, for as we have seen, sugar is Re converted into kick . *\ and bubbles. The ™ saccharimeter tells us how much sugar has been lost and the rest of your problem is easy to solve. In using the saccharimeter, pour the liquid to be tested into the glass jar which chemists call a graduate. Fill it within a short distance of the top, so that when you slip in the in- strument, the liquid, when it rises, will be on a level with the lip or brim of the vessel. Remove all bubbles before noting the stem figures. Wait until the sac- charimeter is still. Make a record of your readings for comparison. To calculate the amount of alcohol present, subtract: the number of de- grees shown for the second reading, that is that of the fermented beer, from the reading which you obtained from the wort or the unfermented fluid. Thus: Difference 8 For rough estimates, divide this result by two; for more exact results take forty-five per cent of it. The strength of this brew in the specimen readings above would therefore be nearly 4 per cent in alcohol, or, to be more precise, 3.6 per cent, or about the same as brewers made before they descended first to 2.75 and then to one half per cent. Directions for mak- ing home brews prescribe that the extra kick be expelled by heating. First-class saccharimeters have small thermometers also in their bulbs by which one may know the exact tem- perature of the liquids being tested, for there are slight differences in the readings for fluids, warm or cold. Jan a The ul should tigatet ference ing th leave althou lift up By compe throug Schwe York expert Dr. Anc recent Wald Cincil coppe with < placec der is at its liquid A Bu for r: vapor goes 1 drum. Dr. V in the cohol at thi utes 1 after conta the f lengt! thirty Bo agent founc

Popular Science Month/,,

i = Januar

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mm o1oxstrtoodr OD MD Jan uary, 1921 The unfermented wort, of course, should be cool before it is inves- tigated. Chemists allow for dif- ferencesin temperature. In read- ing the thermometer, be sure to leave its bulb in the liquid, although it will be necessary to lift up the saccharimeter itself. By observing closely the ac- companying photographs, posed through the courtesy of the Schwarz laboratories, of New York city, you may soon become expert in its application. Dr. Waldbott’s Alcohol Test Another simple test is that recently devised by Dr. Sigmund Waldbott, of the University of Are You a Lawbreaker? NE half of one per cent. You know what that means. If you make your own wine at home, or brew your own beer, how can you tell whether it contains more than the permissible one half of one per cent alcohol? In this article some simple in- struments are described which will enable any householder to measure the alcohol in his home- made beverages. ment has not nullified that great statute of Nature, the law of fermentation, and the tem- perance-drink vendor, as well as the brewer, is in terror of put- ting on the market a beverage which has more spirit than the Government permits. The brew- er must sterilize his product with great care, lest before it is in circulation some vagrant yeast germ ora little excess sugar will have started the fermen- tation all over again. The Gov- ernment chemists realize that even after the beer has left the brewery, some evil disposed per- son, desiring to injure the maker, may put yeast and sugar in the finished product. Hence the Cincinnati. He uses a small copper flask, which is connected with a cylinder containing glass beads placed above it, and from this cylin- der is led a tube which is smaller at its outer end. Put the fermented liquid into the flask and apply heat. A Bunsen gas-burner is the best device for raising the temperature. The vapor driven off from the heated fluid goes up through the little bead-filled drum, and escapes through the tube. Dr. Waldbott says that if the fluid in the flask contains 3 per cent of al- cohol, the escaping vapor will burn at the tip of the tube for three min- utes in a flame three inches in length after it has been lighted. If the beer contains only one half per cent, the flame will be about the same length, but will last only twenty or thirty seconds. Both brewers and Internal Revenue agents have in the past few months found the new type of ebullioscope or How you should use the saccharimeter for home brews. The liquid is level with the edge of the jar and all foam has been removed. By showing the sugar lost, the alcohol content is proved ' f January, 1921 ebulliometer, invented by Dr. Juerst, a very satisfactory means of making rapid and reasonably accurate tests of near-beers. This instrument is based upon the differences in the boiling-points of water and alcohol. If aliquid contains some alcohol, it will go into ebullition more quickly than plain water. Hence, the ebullition meter or the ebulli- ometer. This long-named device, which is about sixteen inches in height, con- sists of a miniature metal boiler into which the fluid under our scrutiny is placed and then heated with the alcohol lamp underneath it. De- natured alcohol, of course. A delicate thermometer which is attached shows the exact temperature. The operator, however, must first boil pure water in the device, for as differences in the air make slight variations of the point at which water boils, there must be an_ up-to-the-minute water reading as a basis of comparison. Although the Juerst instrument is not official, it is a great help to the brewer in keeping tabs on his processes. Though it is possible to brew a beer originally which contains less than one half of one per cent of alcohol, the brew- masters usually make the beer of 2.75 strength, and then drive the alcohol out of it by passing it over a heated metal surface. Drinks with an Evil Tendency In this way, they can retain their old appliances, and as hope dies hard in the human breast, scores believe that some day they may be able to vend beer which is not devoid of a recoil. This deviceis also used by makers of soft or temperance drinks, for even the most harmless fruit- juices, or mixtures containing a little sugar, are likely to go on their wayward path by getting a stiff nip. The Fighteenth Amend- 47 utmost vigilance at all stages of manufacture, and the frequent appeals to the ebulliometer or sim- ilar quickly responding devices. Some More Complicated Tests Valuable as are the emergency methods for rapid determinations of aleohol, both the Government and the brewers, in examinations where absolute accuracy is demanded, as when a question has been raised on a decimal basis, resort to the polar- iscope, the picnometer, and _ distil- lation appliances, with which the home brewer would not care to con- cern himself. The householder has within his reach, however, means by which he can tell where he stands in his domestic brewing and therefore can find scant excuse for pleading ignorance of the strength of the potations made under his roof-tree. How to read the saccharimeter for temperature corrections. Be sure to keep the mercury bulb in the fluid if you are looking for an absolutely accurate reading

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Grubbing Up Tree-Stumps with Liquid Oxygen N account of the scarcity of plastic explosives since the war, liquid oxygen has recently come into exten- sive use as an explosive. Liquid oxy- gen in itself, of course, is not an ex- plosive; it must have a carrier in the form of a paper cartridge. It is necessary to saturate this cartridge in the liquid oxygen for from twelve to fifteen minutes to make it effective. The fuse should be drawn through the cartridge before subjecting it to the soaking process. The small flame of the fuse is sufficient to convert the cartridge into carbonic acid and water vapor. Some very promising tests of the use of liquid oxygen for grub- bing up tree-stumps—and thereby recovering needed amounts of fuel—have recently been made in the Grunewald woods, near Ber- lin. A blast-hole about five feet wide was made in such a man- ner that the cartridge could be inserted below the rootstock of a giant oak. Next the liquid oxygen was poured into a ‘“‘soaking’’ vessel and the cartridge thoroughly = im- mersed. Finally the soaked cartridge was placed in the hole and covered with earth. The grubbing up of this root, which required only two cartridges—absorbing sixteen hundred grams of liquid oxy- gen—strikingly illustrates the possibilities of this explosive, which many experts consider to be the explosive of the future. Neither liquid air nor car- bon cartridges are subject to the legal restrictions that apply to the storing and transporta- tion of explosives. In fact, previous to the soaking process there is no ex- plosive present. The cartridge inserted into the ground keeps its explosive character for only about twenty- After an explosion an oak rootstock was reduced to these fragments, which were recovered for fuel A liquid-oxygen explosion. Liquid oxy- gen can be safely stored and transported Popular Science Month, Pouring the liquid oxygen into the “‘soaking’’ vessel, preparatory to saturating the cartridge five minutes, after which time all the oxygen required for a chemical reaction becomes va- porized. Electric ignition can, of course, also be used in this connection. Apart from their use in forestry, in connection with clearing operations, road con- struction, and similar uses, these cartridges will probably find many uses in agricul- ture. In fact, their utility in all kinds of operations requiring power and_ rapid action will almost certainly bring them into wide use on American farms when their practicability has been brought to the attention of farmers in this country. How Sections of Huge Pipe Are Bent UGE steel pipes are usually cast, but they can also be bent into shape. Take, for example, the hydraulic gas-mains shown here. They were made from sections of flat steel plate. The sections were very thin—not any more than half an inch in thick- ness. After being cut to the proper size and bent into shape, they were riveted together until they made a pipe that was one hundred feet long. The outlets that will lead from the main pipes to aux- the main pipe. The neces- sary welding was done pneumatically and the long ropelike tubing used for the purpose is shown resting on the pipes. These tubes carry compressed air to th¢ hammers, which force the rivets into position. Each plate was bent into a semicircular shape, and then riveted to a similar plate to form a pipe. As the sections were added and the pipe lengthened, great care was taken to see that the upper and lower sec- tions were not added at the same place. Thus the joints were all firm, and _ subse- iliary ones are castings, and they also were riveted to These huge gas-pipes were not cast—they were bent into shape and then riveted 48 quent gas leakage was un- likely. January ae ryTH | at Heat ward f speed. fected these | a ‘the new d detect hundr At simila When couple ated. will d heat 5 N t the States takes out in obser the i dustr' actly benef detrir ecultu Dis quent tions cate t enem

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ne n in, lis in yn- PS, |x ul- ns id ly On Pir en ito na lar As nd pat lat —- the nts 1n- January, 1921 —_— Police frustrating a burglary by the use of the thermocouple, which detects heat waves given off by the human body at a distance of six hundred feet or more fe» human body radi- ates considerable heat. Heat waves are shot out- ward from it in all directions at terrific speed. An instrument has been per- fected that collects and concentrates these heat waves and projects them on a ‘‘thermocouple.”’ So sensitive is this new device that a human body can be detected with ease at a distance of six hundred feet or more. A thermocouple is merely two dis- similar metal wires soldered together. When heat waves fall upon a thermo- couple, a small current will be gener- ated. The strength of this current will depend upon the intensity of the heat source. The thermocouple used Heat Waves Betray Burglars PARABOLIC REFLECTOR INFRA-RED OR— ~~ , SENSITIVE GALVANOMETER ( MAGNIFIER 453 This shows how the heat radiations are received from a human body and re- flected upon the thermocouple on this apparatus is placed at the focal point of a parabolic reflector. When heat waves strike the reflector, they are concentrated and reflected on the thermocouple. Thus a small current is generated, and caused to pass through asensitive electrical measuring instrument called a galvanometer, and in this vay the skghtest movement can beseen. A suggested use is here illustrated. A burglary is being frustrated. The sensitive part of the apparatus is so mounted that it can be turned in any direction. Armed with this, the police can “‘see’”’ the approach of the burglars, though darkness hides them. As a demonstration of sensitiveness, a man was placed in a hole several hundred feet from the thermocouple. While he was concealed, the galvano- meter did not register. When he mere- ly raised his head above the surface, the instrument registered instantly. Getting Rid of the Japanese-Beetle Pest N the farmers’ war on their enemies the Bureau of Entomology, United States Department of Agriculture, takes an active part. Its experts go out into the fields and analyze the soil, observe the birds, examine forty-eight. quarts of beetles can be easily collected to demonstrate the efficiency of methods by which the raid was so well conducted. There are various ways of destroy- ing these insects before they reach the “‘beetle’’ stage. Burning stubble and spraying with flames of gasoline, with mechanical methods for controlling the fire, are among the most effective. This foreign beetle that the insects, and work in- dustriously to discover ex- actly what things are beneficial and what are detrimental to the agri- culturists’ interests. Discoveries are fre- quently made and inven- tions devised to help eradi- has made its appearance in New Jersey is known as the Japanese beetle. One way that has proved suc- cessful in fighting the pest is the application of that deadly poison, cyanide. The poison is dissolved in water and is applied to the cate the farm’s destructive enemies. Thus it is that Forty-eight quarts of beetles, gathered in a fight on the pest being carried on by the United States Government 49 soil, killing the grubs be- fore they can grow up.

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New and Better Ways of Loading | Live Stock on the Motor-Truck TROLLEY TRACK

ROTATING PLATFORM LOADING POSITION ) Pa . | renames: Kasil AD be) <A RZ oe eres Be =

Unloading Sheep at the Cincinnati Stockyards With the use of the motor-truck for transporting live stock have come many improvements in hand- ling. At the Cincinnati stockyards sheep are unloaded by means of a horizontal chute pulled out from over a permanent inclined runway. The truck does not back up to the

Complicated Segmental Swing Chute A somewhat complicated segmental swing chute that is swung around in back of the truck. The device is in use at the Cincinnati stock- yards. Notice, in the small line sketch shown near the top of the page, the inge- niously arranged trolley on which the curved metal chute swings. This type of chute eliminates the necessity for backing the truck into exact alinement with the edge of the chute. At the right is a different type, in which the extended part of the chute is supported on legs ,

chute, but runs up parallel to it, after which the horizontal chute is pulled out directly back of the body. This method avoids maneuvering on the part of the truck and dam- age to the rear of the truck or the front of the chute in careless back- ing up on the part of the driver

| | HII | RUNWAY (EXTENDED) J THLE RUNWAY - — PUSHED IN )

nl —— a Zz | pe () & zZ m

A Free Balloon that Hasn’t

A Simple Portable Inclined Chute By transporting his live stock by motor-truck the farmer does away with the necessity of waiting until he has a carload or of sharing with some neighbor the use of a car. While he is doing this, the price often falls be- fore he can reach the market, resulting in a considerable money loss for which he is nowise to blame, but which he alone must bear. He must load his stock as carefully as it should be un- loaded at the stockyard. The picture above shows a simple portable inclined chute for loading hogs, sheep, and cattle Popular Science Monti:ly Popular Science Monti.

| a — wand ake

January

The trav mor This fort whe to | by. I ay wei: use live abc the

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thly January, 1921 Here Is the Best Plan The longer a load of cattle must A Simple Expedient to Avoid Broken Legs Although at some yards cows must still jump out of the truck bodies on to the ground, a distance of three or four feet, this practice has been abandoned at the more pro- gressive yards because of the dan- ger of broken legs. One Kansas City stock-raiser, aware of the danger of making his cows jump from the truck.to the ground, backed up his truck to a sand- pile when about to unload, and the animals walked from truck to sand- pile easily and naturally. They were then driven on the hoof to the stockyards gate Why Motor-Trucks Are Supplanting Railroad Box-Cars More than 1,500,000 live hogs, sheep, beef cattle, and calves were hauled from farms to near-by stockyards by means of motor-trucks in 1919. Be- cause of the greater expedition of delivery by trucks as com- pared with railroad shipments, the truck is being used more and more in such work. It has many advantages over the rail method. The farmer is able to get his live stock to market while the price is high. This is not possible by rail shipping, for the freight-car has to be ordered first, and this sometimes takes two or three days. Then again, the animals lose less in weight when transported to market in motor-trucks. The motor-truck method has made necessary new methods in the stockyards, some of which are shown on these two pages. 2000 Hogs Daily : The Omaha plan permits four | travel in railroad box-cars, the Y. Ti nN | | more weight the animals lose. CATE eI HNN ~ This is caused by the discom- ARTI TT Runway fort suffered from jars and jerks ANII lig | whenever the freight-train stops . :, ty to allow passenger-trains to fly by. For this loss the farmer must pay, since stock is bought by weight at the stockyards. This is another reason for the wide use of motor-trucks for hauling live stock. The platform shown above is perhaps the best of all the new unloading layouts trucks to unload at a time, and has no moving parts to get out of order and no maintenance cost. The layout shown will permit two thousand hogs to be unloaded daily. Speed of un- loading is an important factor to the truck-owner and to the stockyard. To the former it eliminates costly truck delays; to the latter it prevents ve- hicular congestion and over- time work in getting the animals into the pens, ready for sale Showing the plan of the loading scheme in vse at Omaha. By this arrangement four trucks can be unloaded at one time without getting in one another’s way 51 January, 1921 si & ec

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A Pocket Adding-Machine ‘THE Chinaman of the laundry counts his change on a rack of strung beads. The man behind the counter uses a cash- register. But here is a pocket adding and subtracting device that will enable any one to reckon the amount of figures in addition, division, or subtraction. To add, he puts the point of his pencil into one of the holes that surround the lower of the two cardboard disks and ro- tates the disk toward the right. To sub- tract or divide, he rotates the disk toward the left. The two disks are so arranged that they revolve easily upon one another over a series of numbers. The Tight-Fitting Overalls “3 HY should overalls be loose around the waist and feet ?” inquired Elizabeth Maddex, of Terre Haute, Indiana. Whereupon she invented a new kind of overalls. These overalls have a belt that may be loosened or tightened to suit each wearer. A pair of straps—one at the knee and one at the foot—are sewed into the seam of the trousers. They are joined together by a fas- tener that snaps over a button after the straps have been wound around the legs. One look at the picture below shows the improvement that has been made in the humble overalls. A Free Balloon that Hasn’t Any Net NEARLY two centuries ago the first free balloon drifted its way across the sky, yet today this obsolete type of air- craft still holds such a fascination that men continue the sport of ‘‘free balloon” voy- ages. The usual free balloon consists of a gas-bag composed of light, airtight silk encased in a network of strong cords to which the basket is attached. But re- cently there has been invented a balloon that dispenses with the netting. Instead, the series of meridian and parallel sec- tions—“‘trajectories,”’ they are called—are sewed on the envelope and tightened by adhesive strips. Each third section ends in the summit of one of the ‘“‘bolt-rope” arcs, which form a wreath around the lower part of the envelope. The absence of network aids in replen- ishing the supply of gas. The car is more stable and repairs can be more easily made. Although this is the day of airplanes and power-propelled dirigibles, there is a fas- cination in ‘‘free ballooning” that retains a number of enthusiastic followers. Help- less in the face of the wind, the free balloon drifts hundreds of miles in a course that varies with the currents of the air at different levels. Popular Science Monti: How to Strengthen Flower-Pots [ ARGE pots of clay, used for palms and other big plants, are almost sure to crack in time, from the strain and weight of the earth. The cracks usually start at the top and gradually extend the length of the pot. To prevent this, wrap a heavy copper wire tightly around the pot, under the shoulder. Cut the ends, leaving sufficient wire for the ends to be carried over the top of the pot and bent down inside to support the wire ring. One support is not enough, so a piece of wire should be inserted under the ring on the side of the pot opposite the first support. This should also be bent over the top of the pot. Thawing Pipes by Torch A FEW days of zero weather, and you hear a good deal about “frozen pipes.’”’ The plumber comes with his blow-torch, and thaws them out inch by inch. Now, however, there is an attachment for the torch that enables the flame to concen- trate on a large section of the pipe at a time. It is a long tubular case, closed at both ends, that fits on the spout of the torch. A longitudinal section of the tube is cut away and the edges are notched to form teeth. These teeth grip the pipe, and the flame, extending the full length of the tube, spurts out through the notches and curls around the pipe. Janu Disc A® soils Soils The | bridg bridg By bridg deter bridg tirou mate deter rapid of all that és [F3 g1 cient up 01 they’ Su The whicl rod. cross WI great the h Th porte is a abou Of ¢ cates tures look | the ; loom usey

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January, 1921

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Discovering the Presence of Lime AN ingenious invention for determining the amount of lime or other alkali in soils has been developed by the Bureau of Soils of the Department of Agriculture. The instrument, known as the electrolytic bridge, is really an improvised Wheatstone bridge. By filling a small cup accompanying the bridge with soil saturated with water and determining the resistance by use of the bridge to the passage of an electric current tirough this amount of soil, the approxi- mate percentage of soluble alkali may be determined. Thus the field men may rapidly determine in the field the amount of alkali present and indicate it on maps for that area of the country.

Family Portraits on a Rod IF you think the family album does not give your ancestors’ photographs suffi- cient display, you might try hanging them up on a pole in your parlor. That’s what they’re doing in England now. Such an arrangement is shown above. The picture-frames have loops at the top which fit over hooks attached to a metal rod. The rod is supported at the ends by crossed bars. When you grow tired of looking at your great-great-aunt’spicture, you can take it off the hook and substitute some one else’s face. The rod, which is sup- ported by two end pieces, is a small one, measuring about six inches in length. Of course this accommo- dates only very small pic- tures. Those shown above look like old miniatures. In the absence of such heir- looms as these, you might use your favorite snapshots.

Light for the Mariner GTEERING a vessel by compass at night taxes the eyesight severely. The pilot must have enough light to see the motions of the compass needle, yet must be able also to peer beyond in the darkness to catch the glimmer of a distant beacon. The retina of the eye needs time to accommodate itself to changes in intensity from a bright light to darkness. Thus a light for the compass, the clock, or the tiller-ropes of a craft should be so designed that it will afford the greatest pro- tection to the eye. The light for compasses and clocks that is shown above saves the pilot’s eyes by throwing its rays only upon the dial above which it is sus- pended. One Man Can Operate This Ice-Cutting Machine ERE is an _ ice-cutting machine that can be operated by one or two men. It consists of a sled frame on which is mounted a motor that drives a saw trailed along at the rear of the ma- chine. Connected with the arms that sup- port the saw is a lever operated by hand and adapted to raise and lower the saw to cutting position. A gage arm, mounted on the frame of the machine, may be adjusted so the saw will travel in a path that will cut blocks of ice of any desired width.

Wireless Messages Recorded UR amateur wireless telegraphers may now record the messages they receive upon a tape, thanks to a new device de- veloped by Mr. William G. Finch, of Buffalo, New York. Instead of the familiar buzz in the telephone receivers, the dots and dashes will be printed upon the tape, and even the messages sent by the fastest operators will be read at leisure. An ordinary printing telegraph machine is used to record the messages. This is ac- tuated by an ultra-sensitive relay through which the radio currents pass. This device may make the hobby of radio even more popular than it is now.

Reading the Temperature JITHIN the crystal hemisphere shown above can be seen a scale of degrees ranging from the negative side of zero to 120 on the positive side. An indi- cator moves along this scale and accurately indicates the degree of temperature in the room. Every house should be equipped with a means of finding the temperature. If the thermometer is attractive in appearance, so much the better. This new thermometer is so sensitive that it will respond to a draft of the breath. The indicator is in the design of a small flag * gh which moves to the correct P { degree of temperature. ‘ Temperature is as impos- sible to estimate precisely, as it is impossible to esti- mate the degree of light in a room. One knows when a room is dark or light, hot or cold; but not how dark or cold. <A thermometer enables one to keep the temperature constant.

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Clean Your Shoes on a Skate DOORMAT will 4 take the dust and light dirt off your shoes if you shuffle across it, but it will not remove cakes of mud. If you have an old double- runner skate around the house, fasten it up- Popular Science Monti:ly 7 | It’s a Hot-Water Bottle for Teeth REPARE yourself for future tooth- aches by getting a tiny hot-water bottle like this one. It is so small that it will fit snugly between your gum and your ailing tooth. It holds half an ounce of side down on the edge of one of the steps leading up to the door that is most used. When you arrive home with mud on your shoes, you can remove it neatly and thoroughly by scraping your shoes against the sharp protruding edges of the skate. Of course a single-runner skate will do the job too, but you will have to balance your foot on it. And another disadvan- tage: ‘one runner will do just half the work of two. Mother will find this adaptation of the skate of wonderful value in helping her to keep the house free from mud. Stephenson’s Engine Rebuilt “QTOP the train! There’s a cow on the track!” At that the engineer shut off the power, jumped out, and chased the cow. This took place in the year 1829, and the engine in question was the ‘‘Rocket;”’ it was one of the first to be made in England by George Stephenson, the inventor of the first steam-locomotive. Today there is a second “Rocket,” made by a moving-picture company. It is an exact copy, even to the smallest de- tail, of the original one. It has the same huge driving-wheels in front, a blast-pipe, and tall chimney from which the steam escapes, two eight-inch cylinders, and an internal water-surrounded firebox. The original “‘Rocket’’ entered into a race with two other engines and was the only one to finish. Sculptures from Cheese N UST cheese always be made in the conventional square and_ circular shapes? Not while the artistic Italian has time to mold it differently. Caciocavallo cheese is very plastic and lends itself to the making of weird figures like those shown above. After they have been molded, they are rubbed with olive oil and smoked for a few minutes over a wood fire. They come out a dingy brown. Caciocavallo tastes much like Parmesan cheese, and is used chiefly for flavoring soup and spaghetti. The word Cacioca- vallo means ‘“‘horse cheese,’’ though the cheese itself is not made from mare’s milk. It is supposed that the trademark used by the original makers was a horse’s head. How We Waste Timber Opel forty per cent of our timber is used. The other sixty per cent is in such shape after:the boards have been cut that it represents nothing but waste. This is a startling fact, but nevertheless true. Some attention is being paid to the use of this waste in manufacturing from it such products as alcohol, tanning extracts, tur- pentine, pine oils, fiber for rugs, linoleums, and carpets. These are just a few of the products that may be obtained from saw- mill waste that is now being thrown away. water, and will give out enough heat to relieve almost any toothache. When you hold hot cloths to your cheek at toothache time, much of the heat is lost before it reaches the tooth. With a hot- water bottle directly against your gum, none of the heat is lost and you are re- lieved quickly. We hasten to add that no amount of heat will keep off the dentist for an in- definite length of time. This tiny hot- water bag may be utilized for an ice-bag, should such a tiny one be needed, provided the ice is chopped small enough. A Ship Without Smokestacks HE ship below is complete with every- thing but afunnel. It is propelled with Diesel engines and- therefore it does not need a funnel like coal-burning ships. Diesel engines burn crude oil and the residue gases are exhausted through small pipes. On some German ships _ hollow masts serve as exhaust pipes. No draft is needed. The great engines installed on this ship have a tremendous power—forty-five hun- dred straining horses would be needed to rival it. Africa is the name of the new ship, and it has a length of four hundred and fifty-five feet. All the winches and steering-gears are driven by electric motors. It is the most modern ship afloat. 54 Janua HO cal might made Of « plodir would The h the pe would actua would plete itself woul sacks J "M king¢ gettil ever, enou; wood darec 30 paint fierce ible | forth Willi ously Fe the | sible has i Popular Science Month!y

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ter th rself oth- tiny like nall igly and It of rive to eek lost lOt- 1m, of in- ot- ag, led ry- ith 10t ps. all OW \ip in- to nd ve Ts he January, 1921 \| This Hanger Clamps to the Molding nee hanging bird-cages, flower- baskets, and the like from a wall, Allen Burrows, of Los Angeles, Cali- © Harris & Ewing Save the Mail from Fire HOULD accident bring down a mail- carrying airplane in flames, the loss might be minimized by the use of sacks made of fireproof material. Of course, exposed to the full fury of ex- ploding gasoline, there is nothing that would be an absolutely fireproof device. The heat generated would be so great that the paper enclosed in the asbestos covering would be ‘‘distilled’’ even if it did not actually burn. However, asbestos sacks would be a greater preventive of com- plete destruction. Though the material itself would become very hot, the letters would not suffer as much damage as from sacks of ordinary material. A Daredevil Wooden Horse “N\ AY kingdom for a horse!’”’ shouts 4 Willie, aged five. But Willie’s kingdom isn’t very large, so his chances of getting a real horse are very small. How- ever, if he shouts hard enough and long enough, his parents may buy him a wild wooden one like that shown below. The daredevil rider is also made of wood. Both horse and rider are appropriately painted in gay colors, which increases their fierce look. They are mounted on a flex- ible brass rod, and sway gently back and forth at the slightest touch. And when Willie pulls them around they ride furi- ously. Few people have given much thought to the psychology of toys, but is it not pos- sible that Willie’s love for the toy animals has influenced his love for the live ones? January, 1921 Pr + fornia, has devised 2 hanger that clamps to the wall-molding. The hanger consists of a lower forked member that engages under the molding and a pivoted clamping member that en- gages over the top of the molding, to secure the device in place. The long hook-arm on which the article to be hung is suspended is hinged to the clamp that engages the molding, so that the hanger may be swung readily to either the right or the left. The Traffic Man’s High Chair | pURING the repairing of a tramway route in Bradford, England, this ob- servation post was installed for the traffic policeman, so that he could be seen from a distance. His personal comfort was con- sidered as well as his efficiency, for which reason a chair was attached to one of the metal standards. By climbing a ladder a comfortable seat in the chair was afforded the signal officer. In the daytime he made use of a flag, and at night of a lantern. The men who stand in the open to regu- late the traffic of city streets are better able to do their duty if they are com- fortable. ac Clathing fram Caowe © Keystone View Company Milk by Slot Machine | Sed put in a nickel and pull a lever; out comes a cup of coffee. That’s the sys- tem in some of these wait-on-yourself restaurants. And now a London store- keeper has adopted the idea. He sells large quantities of milk to the people in his neighborhood. Not wanting to spend too much time in the store, he had an automatic milk machine attached to the door. A child comes along with her pitcher, holds it under a faucet in the door, puts her money into a slot, pulls a lever, and lo! a stream of milk pours forth. When the proper amount is reached the flow auto- matically stops. Comfort for a Traveling Dog USTER MURPHY is a much traveled dog, and his master sees that he travels in comfort, housed in a portable conveyance. It is constructed from gal- vanized metal which is perforated at the top on both ends for circulation of air. A food and water receptacle is placed inside, with an extra supply of food in a drawer below. The dog’s name and his master’s address are stamped on the ends of the kennel, while casters to roll it are placed beneath, and a hand hold is arranged for carrying it. It weighs little more than an ordinary suit- case—when Buster is on the outside. Buster travels in more comfort than do a great number of humans. Surely there is nothing worse than a railway coach with its hot plush seats in summertime.

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Popular Science Month!y Combing Out Nails from the Keg OX-MAKERS and others who use scores of nails usually have to dig with their hands into the keg to get the nails, afterward sorting and arranging them so all the heads are in the same position in order to pick them up rapidly and drive them into the box being made. Mr. John Catinzearo, of Chicago, has invented a device to bring the nails from the keg ready for use. A simple wooden handle carries a head into which a number of metal pins, themselves nails, are driven. They are spaced just far enough apart to permit the nails in the keg to pass between them and to be held suspended by their heads. The workman drags the “comb” through the nails a few times, and dumps in his left hand those that have been caught in the teeth of the comb. The nails are thus already assorted, and the work is done in one tenth the time of the old method. Solid Wheels instead of Spokes OLID wheels of wood have become so popular on automobiles that now they are being used on bicycles. Below you see a bicycle in which the usual wire spokes have been supplanted by wood. And, what is more, the tires on this bicycle are made of solid rubber; thus punctures become an impossibility and bicycle pumps as obso- lete as the dodo. Of course solid tires do not absorb shocks as well as do air-filled tires, but in these days of good roads there are not as many shocks to be absorbed as there were twenty years ago, thanks to the auto- mobilist. The elimination of spokes does away with the great danger to women riders of having their skirts catch. Tr 6CUdéTT 1 Tr A Bench Drilling-Stand that Is Adjustable MECHANICAL dwarf, less than a + yard high and weighing only seventy pounds, yet having strength to hold a drill that bores into solid shafts of steel, is the way one might visualize the new bench drilling-stand equipped with an electric drill. It would be impossible for a man to hold an electric drill by hand and accomplish the work done when the drill is held mechanic- ally against the material into which it bores. This drilling-bench stand is so con- structed that the drill may be swung clear of the base to operate on pieces of material that are too long to fit the bench. The bracket carrying the drill can be raised or lowered on the vertical column, and is secured firmly in any position. Is It Good Flying Weather ? guetta you go up into the atmosphere with the airplane, call up the Weather Bureau and find out whether the wind is favorable or not. Special reports are prepared daily from observation of captive test balloons. The direction of the air currents up to four thousand feet, their strength, indicated by the pull on the cable, and other information, are obtained from numerous weather sta- tions. The balloons are sent up each morning. Chiefly benefited by this’ information are the pilots of the aerial 2 mail service. In mak- ing ong-distance flights they must know what weather is ahead of them. 56 Making the Screw Stay in Its Place FTEN it is desired by the workman that the screws he puts into the wood be permanently set. To prevent the removal of the screw with an ordi- nary screwdriver, the slot into which the screwdriver would fit is held in such a manner that the screw cannot be removed. Three forms of slot-fillers have been invented by Fred Schumann, of New York city. The first filler consists of a small segment conforming to the curvature of the screwhead, which is driven through a small hole drilled in the stem of the screw at a suitable angle. The second is a filler that is driven vertically down along- side the stem, completely closing the slot. The third is made by the simple expedient of merely tapering down the corners of an ordinary screw so the screwdriver will not engage the slot to permit the screw to be removed. A Machine to Compress Silage the wintertime cows usually live on silage; it is a fodder made up of corn- stalks, sunflowers, and various grasses that are stored under pressure in a silo. The problem of compressing the silage to such a point that practically no air can get through led to the invention of the machine shown below. The silo is filled with stalks and then the compressing machine is placed on top of them. A roller at the bottom of it moves in a circular path over the stalks, pressing them down. One man guides the machine and an engine gives it its power. The engine weighs one hundred and ninety pounds and by its very weight helps compression. There is a small seat for the man who guides the machine. Jan em Thr mos unti mak and L oile in t han han are gra twc hol 7 sch pa] T Popular Science Month; an cCr?’r,T | Ja

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lan the nt di- ich in Lot ew all of gh ne sa 1g- Ot. nt of rill 2W on n- at he ch et ne he es 1g aid ht January, 1921 A Place for Rubbers Wwe do you do with your rubbers when you're not using them? Throw them in the corner of the closet, most likely, and leave them in a heap until you want them again. Why not make a rubber-holder like the one above and hang it up in some corner? Line a strip of enameled cloth with oilcloth, and punch six holes in it, two in the upper corner to afford means for hanging up the holder. Metal clasps hang from the other four holes, which are along the bottom edge, and they grasp the rubbers in the back. Thus two pairs can be hung from one holder. The clasps are of the kind used in schools and offices for holding together papers which must hang from the wall. Testing Tiles on the Principle of the Nut-Cracker [MAGING a building-tile that represents a giant nut, and two strong steel girders representing the jaws of a nut-cracker, with a long steel beam as the lever-handle supporting an automobile at the far end as sliding weight. If your imagination is at all good you will see at a glance how this giant ‘‘nut- cracker’? works in testing the strength of the tile. As the automobile is brought farther out upon the end of the lever, it increases the weight brought to bear upon the tile held between the heavy steel beams. A scale indicator is attached to show how many pounds the tile will stand before it bursts under the terrific strain. From this scale it was found that the pressure supported by the tile reached a point in excess of one hundred thousand pounds. Clothing from Cows HERE is a certain breed of cattle, known as the Galloway, which is quite different. from the usual breed. The ani- mals have thick curly hair that can be used as wool. The Galloways grew up in southwest Scotland, where a good overcoat is needed to keep the warmth in and the damp weather out. They have no horns, and it is thought that through the ages their original horns gradually disappeared, due to the fact that the country is too rugged for enemies to venture into. Regulating the Phonograph Needle PHONOGRAPH needle has been in- 4 4 vented that makes it possible to vary the tone to any desired degree of loudness or softness. It consists of a metal cap into which a needle of tungsten is fixed. When this cap is placed on the shank, the loudest tone is produced, because the vi- brating medium is shortest. But when a series of caps are interposed between that which contains the needle and the shank, a soft tone results. The Handy Little Magnet AVE you a magnet for use in the house? When unruly phonograph needles fall upon the floor, as they have a bad habit of doing, a magnet with a long handle enables one to pick them up without sticking them into his fingers. It also collects the small steel balls that are used in the modern quill pen- holder. On a far greater scale, magnets are used to lift heavy iron weights in the steel-yards. They are also used to collect bits of iron filings and steel dust that collect in the vicinity of the mills. In the machine-shop they are indis- pensable. Steel splinters have also been drawn out of an eye by means of these metallic bars charged with one of nature’s most mysterious forces. A Tractor Helps Out in a Street-Car Strike URING a strike of power-house men in a large city in Holland, the automo- bile tractor here pictured was used to pull the street-cars along the tracks. It is about the size of a large limousine and is equipped with standard gage flanged wheels, and has a chain drive. No doubt, in cases of emergency such as existed during the strike, the device would prove eminently satisfactory. Where people must travel a long distance to reach their place of business, they are not in- clined to cavil at the mode of transporta- tion used if the regular source is cut off. However, it is to be hoped that no emergency arises which will necessitate the introduction of the idea to our busy American thoroughfares. But it beats walking! January, 1921

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Popular Science Month] y If Jack Frost Could Be Put to Work - His great strength estimated in terms of horsepower By Latimer J. Wilson tively small as that in- cluded within the limits of New York city, Jack ‘ Frost makes use of more « power than that which is used to run all of the in- dustries in the whole civil- ized world. When one steps outdoors in the morning and sees the ice on the pavement, he seldom thinks about any other work being done than that of his own task in re- moving the slippery sheets from in front of his prem- ises. The trees in dazzling drapery of sun-glistening crystals, the soft fluffy blanket of snow, or the smooth hard covering of sleet may awaken esthetic ideas, but they do not turn one’s attention toward the mechanical process of their creation. Yet Jack Frost has made them all in his gigantic ice-plant, and to appre- ciate his subtle work one must delve into concrete comparisons. As the manager of an ice factory, Jack Frost has his human competitors so far outdistanced that these comparisons become ridiculous. But they are extremely interesting. To move a one-pound weight 550 feet in one second, or to lift 550 pounds one foot in one second, constitutes what we call a “horsepower.” The man in the street gages the strength of his automobile by its horsepower; it may be equipped with a ten, a thirty, or a sixty horsepower engine. To understand the enormous working ability of Jack Frost’s industrial plant, we can best refer to its energy in the form of horsepower. If the man were to clear his pavement of snow and ice, he must apply his muscle to the job, unless he makes use of a horse and a snow-plow or a motor-driven snow remover. But, in any case, the amount of work applied to the task can be measured in terms of ‘“‘horse- power.” Perhaps the sun comes out and warmly melts away the ice. In doing so it also exerts a form of energy that can be translated into the unit for measuring power. The amount of heat required to melt one pound of frozen water is conveniently expressed in units of heat, commonly called British thermal units. Just 144 of these units are required to melt that amount of frozen water, for water both freezes and melts at the same tempera- ture. If we put 144 of these heat units ik an area, aS compara- wee * "= ie — % et x a ~ - - — a my The freezing waves create curious ice forms along the shore. Here is an ice-crater, hollowed out by the action of the water into the one-pound cake of ice, we must take them from some source of heat. In man’s ice-plant at home, the ice- cream freezer, he cleverly arranges the apparatus so that the heat to melt the ice is extracted from the delicious mixture contained in the freezer. As the heat leaves the ingredients of the ice-cream, it freezes this material and passes into the mixture of salt and ice, helping to melt the ice. It is this process of melting the ice surrounding the container that freezes the cream. The salt passing into solution in the water also liberates heat and this quickens the process by making the ice melt more rapidly, thus more rapidly taking the heat from the container. A refrigerating plant works upon the same prin ciple. In one process th: water to be frozen is sur rounded by pipes in whic} salt-brine is circulated, the brine having been cooled by the evaporation of am- monia. Here the liquid takes heat from surround- ing regions by the rapidity with which it turns from:a liquid to a gaseous state. The evaporating ammonia extracts the heat from the brine, and that in circula- tion around the water-tanks reduces the water to a temperature slightly lower than the freezing-point. But for every pound of ice 144 British thermal units of heat had to be extracted from the water. But how does Jack Frost run his ice- factory, making use of more horse- power than that required to run all of the industries in the world? The best picture one can make is that illustrated in an area the size of New York city, 17.5 miles square, 307.8 square miles, which might contain a shallow flat pan which would catch the rainfall of a mild winter day. There were four days in 1918, from November to April 21, Niagara generates 4,000,000 horsepower, yet to turn into ice the water that goes over in one second would represent 18,000,000 horsepower 58 Jar ——i ©Or-.fsS Popular Science Month),

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is ad ~~ Ts es 6m Ger (SS January, 1921 In blocks of ice often exceeding thirty feet in thickness the “‘jam”’ at the foot of the falls forms into a compact ice-bridge. melted state takes from air and water and sunlight the necessary heat units To convert this ice back into the when one inch or more precipitation was recorded over the area of New York city. Now picture this huge pan of water being transformed overnight by the lowering temperature which Jack Frost carries at his disposal. The units of heat required to freeze the water of even so small an area is too \st. Jack Frost is a subtle sculptor when he coats the shrubs and trees with snow and ice. The spray of Niagara is here seen frozen on the trees fanuary, 1921 59 staggering to present a mental picture. No less than sixty-four odd trillion units of heat must be removed from the water before it is turned into ice! What becomes of this liberated heat? It passes into the atmosphere, helping to temper it and partially taking away its keen edge of cold. When all out- doors is dripping with water that is turning into ice, the air is warmer than it is after the ice has formed, all else being equal. A strange anomaly it is that while the water is freezing the air is less cold. One may not often real- ize this condition because the moisture in the air produces a damp chill that is uncomfortable. When the great pan of ice melts, the reverse conditions occur. The heat ‘necessary to melt this expanse of ice must come from somewhere, and from the surrounding atmosphere it is mainly extracted, tending to lower the temperature of the air. But how about the horsepower? Actual calcu- lations show that to melt such a cake of ice no less than sixty-four odd trillion units are involved, in other words, 916,403,891,235 horsepower! It is thus seen that Jack Frost, in one of his overnight rush jobs, uses about 300,000 times more horsepower than that obtained from all our com- bined resources.

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Popular Science Month’, OR SCENES STAGE SECTORS _ CENTRAL (STATIONARY) STAGE ae a Seven Scenes on One Big Wheel Now comes the stage on wheels. In fact, the stage is one big wheel with the scenes of the play arranged around its periphery. When an act is over, the wheel is turned and the next scene comes into place-in a fraction-of-a minute. The rotary stage is the invention of Gustav Dumont, manager of the German Opera, Charlottenburg, near Ber- lin. The stage will accommodate seven scenes. It can be turned either by hand or by electric motors. Let us hope that-the motors don’t run wild some time. If the stage turned too fast, the scenery would certainly be precipitated on the audience Speeding OULD you draw a polygon, or would you find the length of a line that equals the are of a circle, or do you desire to draw quickly the flutes in a fluted column? If so, here is a new kind of protractor that will accomplish the work with speed and simplicity. It is as valuable to the draftsman and the carpenter as a counting-machine is to the man who must handle long columns of figures. Measuring the angles of a circle, a draftsman depends for precision upon the aid furnished by a pro- tractor. Geometry is a very ancient science, and the triangle, the square, and the protractor have their origin in the remote past of human his- tory. But now a new kind of pro- tractor has been invented by C. Schreiber, of San Francisco. This protractor is so scaled that it may be used as having 360 degrees representing the divisions of a circle, but its numerals are so ar- ranged that when it is convenient to divide a semicircle, divisions of 90 degrees are indicated, thus giving 180 degrees to the complete circle. Suppose one wishes to find the Up the Work of the Draftsman length of an are of 60 degrees, the radius of the circle being known. With this radius a curve is drawn about one eighth part of a complete circle. The protractor is placed so that the measurement scale on the straight edge exactly touches the curvature of the circle. Then, after having drawn the lines that construct a certain tri- es Laying out flutes in a fluted column. At the right is shown how easily the pro- tractor is adapted to constructing many polygons, their gage point, indicated on the protractor, being found by dividing 180 degrees by the number of sides of the polygon desired 60 angle, a single change to a specified degree on the measurement scale of the protractor will enable another set of lines to be drawn which will pro- duce the line that corresponds to a length of 60 degrees of the circle. Thus, with but two positions of the protractor, the work is accomplished. On the face of the curved edge of the protractor are indicated gage points from which polygons that are not in even degrees may be laid off. To construct the fluted columns of an architectural plan, after determining the number of convolutions desired in the column, the gage point is ob- tained by dividing 90 degrees by the number required in a semicircle. ¥/) MA //h Me T// /f ‘an said lid fact hal stal Per of u Yet pro of 1 mo the the sho On ma all; otk Twi wa the filr an rey ho tel mm Hm Hh of 2.0 oo Popular Science Monthi, Janua

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ae Oe «© & | CF SE eh be ee en! ee fanuary, 1921 Which Side of Your Face Is More Intelligent ? ‘(OD | has: given you one face,” said Hamlet—but he did not mention the fact that the two halves of it are often startlingly different. Perhaps he, like most of us, did not know it. Yet photography has proved that one side of the face is usually more intelligent than the other. Take, for example, the three photographs shown on this page. One represents a you do not realize that there is so much dif- ference between the sides. This man is right- handed, yet the left side of his face is more developed than the right side. This is due to the mutual crossing of the nerves that control the two halves of the body. The nerves control- ling the right half of the body are centered in the left half of the brain. Our man uses man’s head as it actu- ally appears. An- other is made up of two left sides; this was done by printing the left half of the film on both its front and back sides. The third photograph represents two right sides. Yet see how different all three are! Notice the high forehead, the in- telligent expression and the well de- different The subject of this article as he actually looks. His face seems normal and symmet- rical, yet the right and left sides are decidedly This photograph is made up of two left sides, printed next to each other. Notice graph. the high brow, the well are developed features, the intelligent expression veloped features in the photograph of the left side of his head; compare this with the uninteresting right side pho- tograph. Yet when you look at the actual photograph of the man’s head, Two right sides of the man’s face are repre- sented in this photo- immature, the his brow low, the expres- sion uninteresting his right hand more than his left hand and thus the left half of brain receives more nervous’. im- pulses than the right; his face is similarly affected. Had our man been left- handed, the right side of his face would have shown greater develop- ment. Mrs. Alice Matzdorff, a Berlin photographer, made the photographs. The features Moving-Pictures Made in Disk Form OVIES! That’s what children ery forto-day. But you don’t like to take your children to the movies unless you are sure that the pictures to be shown are fit for their young eyes. Ah, but here is a picture machine for the home. It is cheap, easy to operate, and won’t catch fire. The secret of its success lies in the shape of the non-inflammable film used. Instead of being in tape form, it is disk-shaped, and the successive pic- tures form a spiral on the disk. Near the edge of the disk there are holes for receiving gear teeth in the projection ma- chine that make the disk rotate. This method of rotation re- duces the wear and tear on both disk and machine that would occur if the disk were centrally rotated. The holes are slightly elon- gated to allow for any contraction or expan- sion that might occur. When the handle of the projection ma- chine is turned, the disk moves; and the pictures—starting at machine can be stopped instantane- ously without blistering the film. Thus, when titles or captions are necessary, two spaces only are de- voted to them. The operator sim- ply stops the machine at the spot until he is sure that his audience has finished reading the words. A ten-and-a-half-inch disk con- tains twelve hundred pictures, and is equal to seventy-five feet of film. The projection machine is funda- mentally the same as the usual the outside end of the spiral—flash on the screen in rapid suc- cession. However, the A disk-shaped film is used in this small moving-picture projector, and the successive pictures form a spiral on the film. The holes along the edge of it receive gear teeth that cause it to rotate when the handle is turned 61 moving-picture projector; however, it may be operated with a small dry battery when there is no electric wiring in the house. The disk records can be made by the thou- sand at very little ex- pense, and thus you are able to buy them at a small price. This machine is use- ful because it is easy to carry.

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Popular Science Month, Making Up Dick Deadeye This is Louis Cassavant, well known for his excellent portrayal of the ferocious Dick Deadeye in ‘Pina- fore.” His natural looks are not the least bit ferocious, but wait till we show him made up! What amateur actors can learn from Louis Cassavant A long thin upper lip is produced by yellow paint. Heavy lines in the face are done in red- dish brown. If Mr. Cassavant thinks his coloring is too heavy, he rubs some light powder on a brush gently across his face Be sure that the crape js on tight before you trim it. You can buy ready-made eyebrows that are easier to adjust, but you are never sure that they won’t fall off at the most critical moment of the play His first move is to erect on his natural nose a thick ugly putty one. He warms the putty, wets his nose to keep the putty from sticking, and then molds it on. Next he applies a grease-paint sunburn Dick Deadeye has to blot out one eye in order to live up to his name. He does this with court- plaster, but leaves a small hole in the center to help him see. The audience, however, does not know this bb. Here he is! Not a bad villain, do you think? Of course the fuzzy whiskers and the shaggy wig help considerably. The whiskers grew in the same yard from which the eyebrows came The bushy eyebrows are ac- quired in the following way: Buy a yard of crape hair and pull out as much as you need. Smear some spirit gum on each real eyebrow, and then stick on the false ones In a few hours all this work is undone. The putty nose is re- moved by string placed across the bridge, brought down the sides, and tied underneath. By pulling the string the putty nose is forced off 62 P Januar Ponular Seenee Man})?.. Janua

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ny January, 1921 Scaring Off a Burglar Strong nerves now needed for his profession With such innocent-look- ing implements as those shown here concealed about his person, a bur- glar cautiously enters a silent house. Perhaps he is planning how he will spend his ill-gotten gains, when suddenly he sees— A flash of light in the dark will scare the tough- est burglar. Attach an ‘ozone generator’’ to the door, and it will shoot sparks when the door is opened. This device purifies the air and is pop- ular in zoos the woman below! Ne ee sieniiaaieeed Silently he turns the knob of the door = age — | leading into the room where the silver | is kept. But as he opens the door, | there is a terrific pounding. Are the i 3 police breaking their way through to ( | get him? He’s off! The noise was | ae | made by an electric vibrator on the iz, , a | floor , x | 4a M i | | —) #4 l ®, ae . y, 1 | | - | = é | Here’s a close-up of the mysteri- fi Toot! Less than a foot away, ous woman who scared off the an automobile horn blares forth burglar mentioned above. Asa as the burglar opens the door. matter of fact, she is not a He is torn between fear and | woman at all! Just a dress wonder, and decides to take no | form, placed in the doorway on | chances. As a matter of fact, \ purpose. The burglar sees the ss hie the opening of the door closed a | vague form, thinks it’s a woman, ie circuit, which caused the horn and makes a speedy exit nye to toot; no one was in the room A Another door-knob trick. The knob is _ con- nected with an electric circuit and gives the bur- — glar quite a shock when he turns the key. He suspects a trap and goes no farther 63 January, 1921

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FEW weeks ago a telephone A message was sent to the New York State Conservation Commission at Albany from a little town down Long Island way—West Sayville, home of the oyster indus- try on that part of the Atlantic coast. William Firth Wells, biolo- gist and sanitarian for the Com- mission, was making a brief report on an important experiment. He was greatly excited. “Sure,” he said in effect. ‘“‘No question about it. We've solved the problem of growing oysters artificially.” And then Mr. Wells went back to the little makeshift hatchery set up in the plant of one of the big oyster companies, and slapped his assistant on the back, and other- wise conducted himself like a pleased youngster. As far back as 1879, a scientist from the staff of the Johns Hopkins University had attempted what the New York State biologist has succeeded in accomplishing. His experiments. stopped just short of success. In a laboratory in the town of Crisfield, Maryland, the Johns Hop- kins man discovered that spawn could be taken from the female oyster and fertilized and that the eggs, in masses of 100,000,000 or so, could be kept alive in great jars of sea- water provided the temperature were maintained at that of the ocean. But at the end of six days, the period required for the oyster egg to hatch, the pioneer experimenter discovered that a tragedy was happening in his hatching-jars. The minute oysters were dying of starvation. Changing the Water a Difficulty The Johns Hopkins man imme- diately undertook to simulate free- water conditions in the jars. He tried to change the water on the theory that he would thus replenish the food sup- ply and the oxygen. Here he encountered dismal failure. There was no way of straining off the old water. The finest mesh screen was amply large enough to permit his young oysters to pass down a drain into Chesapeake Bay. “What of it?’”’ most persons would ask. “Didn’t the young oysters fall into a natural home? Why bother further?” There was the crux of the whole ex- periment. For years the oystermen had known that oyster eggs were Here are some newly hatched oysters as they appear under the microscope magnified to one hundred times their natural size. Their elusiveness dur- ing the process of straining can be readily imagined Popular Science Monthy Rescuing the Oyster Industry William Firth Wells brings the cream separator to the aid of the embryo oyster By Raymonde G. Doyle hatching in their natural enviro ment. The difficulty was that be- fore the oysters arrived at the stave when they were ready to atta themselves to stationary objects «: the ocean floor—‘‘set’”’ is the wo: used in the industry—tides a: eddies swept them out of the sheltered bays and the oyster-be swept them into deep water, whe temperature and other adverse co: ditions stunted growth or left the for the bigger creatures of the dee; to eat. It was thus becoming more impossible every day to insure the future production of the oyster- beds. No matter how much care was taken in placing fertilized eggs, or even young oysters, in the beds, the motion of the water was drag- ging them away. ‘ eee SS Young Oysters Need Care The problem, then, was to hold the tiny oysters in captivity, so to speak, and to keep them healthy through the hatching and early feeding stages and on up to the mo- ment when they were ready to “‘set.”’ William Firth Wells has done this for the oyster industry. Less than a year ago, responding to the complaints of the oystermen Mr. Wells wondered if the cream separator would kill the oysters. He is shown at the left studying them after their unique journey. He found that they thrived under the experience 64 Januai along © servati to Alb fore hi “Go tnese O% ster gradu: So . ants d on an small collec’ bottle scope, tubin: parati group pany gist a Th of ex and wate were that free | size, food star\ chan oyst woul Ri Yan will deci H fact to Si ket arg sepi prir mat fror off sep oys live inte 7 ““ce pre in of Popular Science Monthiy te ae = ean ame Janu

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vs January, 1921 along the New York coast, the Con- servation Cominission called Mr. Wells to Albany and laid the situation be- fore him. “‘Go down to Long Island and help these people,” they told him. ‘“‘The oyster industry has been slipping back gradually and you’ve got to save it.”’ So Mr. Wells took one of his assist- ants down to West Sayville and called on an oyster company to provide a small shed for a laboratory. Next he collected a lot of big spring-water bottles, some preserve jars, a micro- scope, thermometers, glass and rubber tubing, and other odds and ends of ap- paratus such as never before had been grouped together. The oyster com- pany provided the eggs, and the biolo- gist and his assistant set to work. Ingenuity Wins the Day They verified the causes of the failure of experiments performed in the past and then undertook to aerate the water in the bottles in which the eggs were being kept alive. They found that as the eggs hatched and became free swimming oysters, microscopic in size, they greedily ate up every bit of food in the water and then began to starve. When an attempt was made to change the water, most of the little oysters were lost. Aeration alone would not save them. Right there the ingenuity of a Yankee came into play. Scientists will be startled at what Mr. Wells decided to do, He telegraphed to a manu-

After emerging safely from the centrifuge, the oysters were transferred into fresh water through which was forced a circulation of oxygen by tubes that required very delicate adjustment oysters and the water from which they had extracted all the food were emp- tied into the centrifuge container. The first experiment of its kind in history was on Mr. Wells turned on the current. The machine began to operate, and the water with its thou- sands of little oysters began to whirl. Faster moved the mass and presently centrifugal force compelled a concen- tration of the tiny oysters precisely in the same manner that cream is con- centrated from milk. Finally, when the concentration was perfect, the valve at the side of the

facturer of cream separators to send the best on the mar- ket to West Sayville. He argued this way: If a cream separator operating on the principle of a centrifugal machine separates cream from milk and lets it drain off as cream, why won’t it separate the masses of tiny oysters from the water they live in, and let them drain off into fresh supplies of water? The cream separator, or “centrifuge,” as Mr. Wells prefers to call it, was set up in the laboratory. <A batch of some hundreds of thou- sands of artificially spawned and fertilized eggs was watched closely until the hatching stage had been reached and completed. At the point where the micro- scope revealed the little oy- sters to be assimilating food, preparations for changing the water were made. Sufficient time was allowed for the consumption of the food particles with which the

machine was opened and the oysters, pushed out by centrif- ugal force, fell into small bowls from which they were transferred to new supplies of water. Then a suction aeration system forced oxy- gen through the water. Examinations under the microscope were resorted to again to determine if the trip through the machine had in- jured the oysters. No dam- age was discernible. The few days in which they had been free swimmers were sufficient for the formation of the first layer of shell, and, delicate though it was, it had protected the animal life. Throughout the develop- ing stage, Mr. Wells and his assistant maintained con- stant vigilance, waiting for the oysters to sink to the bottom and exhibit a tend- ency to “set.” At the first sign of such tendency the oysters were taken to the “beds” and dumped. They sank to the bottom and fastened themselves to

original water was filled, and then, one by one, the big bottles containing the tiny

January, 1921 At the left is shown the cream separator, or centrifuge, untended for the moment, while Mr. Wells inspects the air-pump that regulates the aeration process 65 rock and shell formations, there to remain until big enough for the market.

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Things Few butchers trim meat before they weigh it. You can do the job well yourself if you use this combined skinner-slicer-trimmer with its sharp curved edges Popular Science Monthy that Every Housekeeper Should Have Scales are useful to a live fish, but when preparing it for eating, they become a nuisance. A grater with a bath-brush back will remove these scales rapidly Here’s a homemade scale. Fill a jam-jat partly with water. In it place a test-tube containing pieces of metal to keep it upright. Fita cork in the tube and attach a strip of cardboard to it. By placing vari- ous weights on the cork you will be able to mark ascale onthe cardboard If you whip cream in an open bowl, it will spatter. But the whipper above is so narrow that it will fit inside the cream bottle and eliminate waste and trouble One tainted apple in a bowl with good ones will soon rot the good ones. That’s the chief reason why the nickel- plated fruit-rack above was invented This fireless cooker is heated electrically. Automatic steam- vents in the lids prevent trouble This new bread-slicer adjusts the width of a slice by means of a pointer and then you pull the slicer backwaid and forward When milk comes toa boil it spreads itself all over the stove. The device shown above prevents this. The milk is heated in a pot that has a spout. When the milk boils and rises, it gushes out of the spout into another pot, which causes a lever to lift the original pot from the flame Here is a pull-chain device that fits over an ordinary electric switch and en- ables persons of average height to adjust with ease lights that are too high to be reached otherwise 66 *,7 @wretwtta — Janua The | 7 NG: 4 phi Dewar, cent ba resist t 952 d The ba are kill cease t the ter and pr Dew drogen out. attem] chemi had ni It o not cc expose in fac which more chemi Ger AB ( year too Ss) gated bacte that « sume this r with Th mold ing” E pin Fil: Col her Popular Science Month, Jan

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January, 1921 Keeping Up with the March of Science Facts for the man who wants to know The Chemical Effect of Light Noa greatest authority on the 4 physics of low temperatures, Sir James Dewar, has shown that some phosphores- cent bacteria, obtained from sea water, will resist the temperature of liguid hydrogen 952 degrees below zero (Centigrade). The bacteria do not give off light when they are killed. Frozen in liquid hydrogen, they cease to be Juminous, to be sure; but when the temperature is raised they shine again and prove that they were not killed. Dewar kept the bacteria in the liquid hy- drogen six months before thawing them out. In the frozen state they resisted all attempts to destroy them. Corrosive chemicals, biting acids, caustic alkalis—all had no effect. It occurred to Dewar that they might not come to life again after having been exposed to ultra-violet light. He found, in fact, that they could not be revived, which proved that light does produce a more profound chemical effect than any chemical. Germs that Feed on Sugar About one per cent of the Cuban sugar crop, valued at $1,500,000, is each year destroyed by greedy microorganisms too small to be seen except when congre- gated in crowds of millions. Molds and bacteria are the culprits. It is estimated that each person in the United States con- sumes 81.84 pounds of sugar each year. At this rate, 873,000 persons could be supplied with the sugar destroyed by germs. The sugar loses its sweetness when the molds consume the sucrose, its ‘‘sweeten- ing” principle. Why Is the Sky Blue? Not one in a hundred persons can tell + ‘\ why the sky is blue, or why the sun- rise and sunset are red. But any one can easily demonstrate the working of the “‘blue sky” law of nature. Blow a film of smoke into a darkened room, and admit the light from one window only. Look at the smoke against the dark background of the room and its color is bluish, but look through it at the light and it appears reddish. The interception of the blue rays by small particles in the atmosphere produces the blue color. The red rays carried in white light jump the gaps between these particles. A Chinese Monopoly Dagon the dye on a firecracker is con- trolled by a trust—this time Chinese. How the dye is produced from a Philip- pine wood is told by Luis J. Reyes, a Filipino student at the New York State College of Forestry at Syracuse, who came here to complete his education, after January, 1921 a. epee son fie graduating from the forest school of the Philippines. Mr. Reyes brought with him one hundred and fifty identified species of woods from the Philippines, and among them is the so-called “‘sapan,’’ known by the Chinese as soo mook, but scientifically known as Caesalpinia sapan. In the Philip- pines it is known also as sibukau or cibucao, and it is one of the best known of the Oriental dye-stuffs. A strong combine of Chinese firms in Hong-Kong is said to control the importa- tion of this wood from the Philippines. It makes the red ink or paste used not only by the Chinese for firecrackers, but also to ink the seals that the Chinese use in certi- fying official documents. According to Mr. Reyes, the wood origin- ally produces a color resembling the yellow of American logwood; but this is treated until it becomes a red of the familiar fire- cracker shade. Clay Phonograph Needles IKE Adam, the latest talking-machine needles are shaped from clay. It has been found that clay of a certain kind, when cut from the shale-banks and proper- ly dried, can be made into perfect needles capable of producing marvelously clear tones from phonograph records. Without grain or grit these needles, after being fired at a temperature of 2000° F., become sufficiently hard to play a record two hundred times. The shale is first cut in sections about six inches square, and is stored in paraffin- coated sacks to prevent too rapid drying by exposure to the air in their moist con- dition. Then the sections are placed in a drying compartment where they are slowly dried. A saw afterward cuts them into strips three quarters of an inch long and one eighth of an inch square, after which they are ground to the perfect form of the ordinary steel needle. These are put into an electric kiln and heated to the intense degree necessary to harden them. Automobile Gases that Kill HEN an automobile engine runs in a closed garage, which is apt to happen in winter, poisonous carbon-monoxide gas is given off that may kill. G. A. Burrell and A. W. Gauger, of the Bureau of Mines, have made an intensive study of the subject, and their conclusions ought to be driven home to every auto- mobile-user. Exposure to an atmosphere containing only 0.20 per cent of carbon- monoxide will cause a man to collapse in an hour; exposure to as little as 0.05 per cent will cause headache after a few hours. No two men are affected in the same manner. Curiously enough, a man at work is overcome more quickly than a man at rest. One of the investigators was extremely ill for eight hours after exposure for twenty minutes to air containing 0.25 per cent of carbon-monoxide. 67 Pm Rha Last of Lebanon’s Cedars URING the war the hand of destruc- tion fell heavily upon the age-old cedars of Lebanon. These trees, which date back to ancient history, were famous during the wars of Sennacherib, 608 RB. c. The Roman historian, Pliny, claimed their wood to be eternally durable, and the Arabs are said to have believed the trees had existed for all time. After two thousand years the timbers in the ruins of ancient Assyria were found un- changed. In remote times the oil from the cedars was used as a cure for leprosy. It was also used by the Romans for preserva- tive purposes. The huge cedars are often ninety feet in height and forty-two feet in circumference. During the world war the Turks cut down many of them to obtain fuel for locomotives, and the opposing forces con- tinued the work of destruction for military purposes. Rust-Proof Steel HE Bureau of Standards has made a study of rust-proofing methods, and has published the results in a _ paper that ought to be read by every metal manufacturer. Coatings, paints, lacquers, varnishes, and enamels of all types are considered. It is shown that zinc is the best protec- tive against corrosion. Zinc coatings were tested by the “salt spray’? method. The article to be tested was exposed to a fine mist of saturated salt solution. By measuring the time that corrosion was resisted it was possible to determine the service life of the protective coating. The Big Family of Sugars UGAR obtained from sawdust is not the usual table sugar, according to the chemists of the New York State College of Forestry at Syracuse, but an entirely dif- ferent substance, one of the many so-called “sugars” derived from different sources, and entirely different in chemical form. The public hope, therefore, that sawdust may be used to relieve the present famine in cane sugar is not likely to be realized for a long time to come, if ever. “An important sugar can be prepared from sawdust by hydrolysis with acid,” says Dr. L. E. Wise, professor of forest chemistry at the New York State College of Forestry; ‘“‘but it must not be confused with the sugar of the breakfast-table. This sugar, prepared from wood, is dex- trose or glucose, and is identical with the sugar obtained by acid treatment of starch. The sugar is not identical, however, with sucrose, commonly termed ‘cane sugar’ or ‘beet sugar.’ Glucose is, however, widely used commercially, and is an important food-stuff. It is the principal component of corn syrups and the like, and has distinct nutritive value. As sucrose w= = 2BAa ea

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can not be prepared from glucose, either commercially or in the laboratory, there is little prospect that such a synthesis will be an accomplished fact in the near future. “The commercial production of glucose from sawdust or other sources probably merits thorough investigation. On the other hand, it should be clearly under- stood that glucose is not cane sugar, and that the term ‘sugar,’ as commonly used by the layman, refers to sucrose or cane sugar. There are many sugars; in fact, they com- prise a most important group of organic compounds, and different species of trees have produced different sugars.” Bricks from Furnace Slag ‘Te slag from blast-furnaces has until recently been an all but worthless by- product, except for its use in making cement. Ifa process perfected in Germany comes into general use, slag will become a useful substance. The slag is dropped into water, and the steam generated blows out the heavier sub- stances, producing a material that re- sembles pumice-stone. This is crushed and mixed with a special bond and pressed into bricks. These bricks are rapidly coming into use in Germany for housebuilding purposes. Goat-Skins for Gloves Se gloves are made of goat-skins im- ported from India. When they reach the United States they are tanned by the chrome process for the production of glacé kid. India is one of the principal producers of these skins, and before the war skins were tanned there and shipped to London for disposal. India has recently imposed a preferential duty on the export of goat- skins, and this will eventually affect the price of kid gloves in this country. Balloons Find Air Currents A currents high above the surface of the earth often reach a speed of one hundred and forty miles an hour, as has been shown by experiments conducted by the Weather Bureau at the University of Wisconsin. One of the balloons used reached a height of twelve miles. Besides showing the direction and speed of the air currents, the balloons also show the height of the clouds and the clarity of the air. Luncheon in Formosa UMAN beings have been known to eat white ants, June bugs, frog pancakes, white mice dipped in honey, locusts, mole soup, birds’ nests, and cooked chrysanthe- mums—why not dogs’ feet? In the island of Formosa dogs’ feet are a great delicacy. Many people who read this will throw their hands up in horror, forgetting for the moment that they like pigs’ feet themselves, to say nothing of ox-tail soup and calves’ brains. Killing Rats with Poison Gas HE Chemical Warfare Service has recently demonstrated that rats can be killed with poison gas. A mixture containing thirty per cent of phosgene and seventy of chlorine was used. This was allowed to escape over an area of nine hundred square feet. Fifteen rats were on the area, and they all died from the effect of the deadly poisonous gases. They were killed at a cost of forty cents. Within fifteen minutes the phosgene had dissipated, while the chlorine gas required thirty minutes to diffuse beyond the danger point. In view of the millions of dollars’ loss caused yearly by these pests, any means of destroying them is welcome. Be Careful of Canned Foods (CANNED foods are perfectly safe to eat, provided the proper precautions are taken before the food is used. If the can is swollen in the least, gas has been gener- ated, and this is always an indication that some chemical reaction has taken place. The food in cans found in this condition should never be eaten. When the can is first punctured, the sound of escaping gas should be a warning not to partake of the contents. Food with an unnatural odor should be regarded with suspicion. Calcimine a Fire Resistant RDINARY ecalcimine or whitewash can be used to make wood fire resistant. Experiments along this line have been conducted by the Forest Products Labora- tory at Madison, Wisconsin. Wood covered with this preparation has been found to be more resistant to fire than many other more costly substances. Calcimine will not protect wood at the higher temperatures, but it will decrease the danger of fire spreading from lighted cigarettes, sparks, and matches. Radium and the Heart HOLLANDER, Dr. Zwaardemaker, caused a frog’s heart to stop beating and brought it back into action by the use of solutions containing radioactive ele- ments. Various injections of non-radio- active elements failed to produce any noticeable effect. Doctors are reeommend- ing diets containing vitamines. Will they change to a mesotherium cure for all ail- ments? About the only common thing that contains a radioactive element is the gas mantle. A diet of gas-mantles would undoubtedly prove to be very indigestible. Asbestos Threads jfpeaeros has been spun into threads so fine that they run as high as thirty- two thousand feet to the pound. The thread is woven into heat-insulating fabrics and incombustible yarn and rope. Only the better grades are used for this purpose. 68 Popular Science Month), This is a recent development, and the Geological Survey of the United States D»- partment of the Interior believes it to |). of great importance. Armor of the Ancients oY gedcloer prhgnier bei have recently com- pleted an analysis of several samples of steel taken from ancient armor. They found that it was made from very pur wrought iron converted into steel by t! old cementation process. The microstru: ture of the sample showed that the proce: used in its production was very similar to the process in use at the present tim: for the manufacture of wrought iron. The metal was hammered into sheets of the proper thickness, and these were then welded into larger sheets, which were again hammered into shape and given a fina! heating and quenching. Prize for a Testing Machine A PRIZE of $1000 by Sir Robert A. Hadfield has been offered for a meta! hardness-testing machine. By this is meant a simple and accurate machine for testing the hardness of steel and other hard alloys. ” The fund has been placed in the care of the Institution of Mechanical Engineers, 11 Great George Street, Westminster, London, S.W., England. Here is an op- portunity for readers of Popular Science Monthly to prove their mechanical skill. India’s Wild Beasts igi has a population about three times that of the United States in about one third the area; yet in that crowded country the struggle against snakes and wild beasts claims astonishing tolls. The latest report indicates that last year 55 persons, were killed by ele- phants, 5 by hyenas, 109 by bears, 350 by leopards, 309 by wolves, 853 by tigers, and 688 by boars and other animals. Poisonous snakes claimed no fewer than 22,478 persons. More than 19,000 wild beasts of various kinds were killed and 91,104 snakes were exterminated in the struggle. Recently high floods killed many of the small animals that are ordinarily the prey of wild beasts, and this probably accounts for the attention that tigers and other large animals have given to their human neighbors. Clouds Formed by Airplanes ETEOROLOGISTS are beginning to believe that, under favorable con- ditions, the passage of an airplane through the atmosphere can result in the formation of a temporary cloud more or less surround- ing the machine. Given the right degree of moisture in the air, there is every reason to conclude that the atmospheric water vapor will be condensed by the local changes of pressure produced. In the high-speed tunnel at Dayton the phenomenon has been noticed on a small scale. Popular Science Monthly Janu

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January, 1921 A Few Suggestions for Higher Office Here’s the typewriter to take with you when you go off on atrip. It is made of aluminum and conse- quently is very light. The typewriter and case to- gether weigh eleven pounds; a handle makes transportation easy Office cuffs made of cloth are not so sanitary as the celluloid cuff shown above. It snaps around the wrist by means of a rubber band and two brass clips. washed The cuff is easily Corrugated cardboard, placed in the bottom of a drawer that is used for holding books in an up- right position, will prevent the books from slipping when one cf them is removed A wet sponge will moisten envelopes effectively, but it soon becomes unsanitary. Here is a moistener made of brass; the handle contains a reservoir and water trickles through to perforations in the blade This letter-sealer consists of two metal rollers between which the envelope flap is passed. The lower roller does the moistening; it revolves through a water-trough at the base of the device This memorandum-pad for your telephone consists of a pad, a pencil, a telephone index, and a clip Jinuary, 1921 . F | at @ 69 Efficiency Glee a When will Mr. Smith re- turn? pected to return A new typewriter ribbon is passed through this machine and a suc- cession of letters made from a single spot in the ribbon. Thus its endurance is tested If you are too lazy to turn the pencil-sharpener, you can attach the sharpener to a small motor so that contact will be made when the pencil) is inserted; any sharpener may be used A bulletin-board like the one above will en- able you to see at a glance whether Mr. Smith is out, and if so when he is ex

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An Instrument to Warn of Gas Dangers ARBON-DIOXIDE is a deadly, insidi- ous gas that has neither color nor odor. When considerable amounts of carbon-diox- ide are present, the red corpuscles insist on carrying carbon-dioxide through the lungs in place of oxygen. Suffocation results. Carbon-dioxide is often present in man- holes, cellars, wells, smokestacks, and in places where metallurgical operations are carried on. The device shown above detects the pres- ence of small quantities of the gas. It has a glass tube containing a solid chemical that turns green upon exposure to carbon- dioxide. By comparing the change in color with a color scale at the side of the tube, the percentage of gas present can be determined. The rubber bulb is for sucking samples of air into the testing-tube. Singing Lessons for Canaries USIC-TEACHER to canaries is the profession of the lady in the picture, strange as it may seem. Canaries can be taught to sing sweetly as well as young ladies. They are taught by a method of comparison. Two large tanks, that fit inside each other, are filled with water that acts like compressed air, and with the aid of whistles makes music. This device whistles a note that the birds like to duplicate. When the birds hear this, they become very ambitious and try to imitate it. Several weeks’ training is sufficient to make a good singer of a young canary with the aid of the compressed-air whistle. Although the canaries make a great noise, those who know claim that it is better than listening to humans learning to sing. © Kadel & Herbert © Keystone View Company How to Keep in Condition ‘THis former middleweight wrestling champion, George Bothner, keeps himself in condition by working at an elec- tric vitalizer every morning. While he pulls at the ropes, a current of electricity passes through the handles into his body; the current is supplied by a dry-cell bat- tery. There are many electrical attachments; . one is a metal foot-pad that puts life into tired feet. There is a comb, a brush, and a massaging machine. All of them are easily attached to the battery. The picture above shows Mr. Bothner using the ropes and the foot-pad. The other appliances are hanging on the wall. This Plug Will Fit Any Socket NFORTUNATELY, _ electric wall sockets are not uniform. Some of them are slotted to receive parallel blades; others call for perpendicular blades; a few are made for T-shaped blades; and some call for blades in line with each other. But now there is a new plug the blades of which can be turned to fit any of these sockets. These blades are so adjusted that they can be turned by hand, and contact can be made from either side of them. The picture below shows one of these plugs with the blades arranged in parallel formation. The Brush that Reaches All the Teeth HE ‘‘Bohemian Girl’”’ dreamed that she dwelt in marble halls; and most of us dream either of the beautiful things we want and can’t have, or of the ugly things we fear. There is a man, however, who had a vivid dream about a toothbrush—a strange dual toothbrush unlike anything he had seen before. He woke up, made a drawing of it, and went to sleep again. In the morning he looked the drawing over and saw that it was good. Since he was a dentist, he was able soon to have a model made. There are bristles at each end of the handle, constituting two brushes. One brush is for the outside of the teeth and the other for the inside. Both of them are attached to the brush so that they can rotate slightly. Thus they reach all the hidden corners. Fodder Made of Sawdust A GOAT can eat paper, which is but a form of wood. Not so with cattle. However, if experiments now being car- ried out prove entirely successful, cattle will add sawdust to their diet. Experi- ments are being made at the Forest Prod- ucts Laboratory, Madison, Wisconsin, with a new cattle food prepared by treating sawdust with acid. The sawdust and acid are placed in the long cylinder shown in the picture below. Live steam under pressure is then admitted to the cylinder. This process converts part of the wood into sugar and renders the remainder digestible. A one quarter saw- dust ration has been prescribed for the cattle under the test. If they survive, there will be a new use for the millions of tons of sawdust produced annually in the thousands of sawmills and lumber-yards. Popular Science Monthl, Dy 4] n ake inste qaeco Te c) im It is I jal quit thin sh whit four Rais thes in b F is W not ers | cate forr alw: pail for F tha bric sor mol this mol no bea Tan

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a J muary, 1921 Here’s Something New in Chimneys Dabespes house must have 4 jts chimney; so why not make decorative chimneys instead of the usual un- decorative ones? Take, for example, the chimney shown at the right. It is located at the side of a plain wooden house and is quite the most startling thing in the neighborhood. This chimney is made of white pressed brick and has four tiled panels in _ it. Raised flowers decorate these panels and are painted in brilliant colors. Fortunately, the chimney is well made and the heat is not apt to injure the flow- ers without. Also it is lo- cated in Southern Cali- fornia where the weather is always of the best; thus the To Remind People of Eden’s Temptations HIS snake never did anybody any harm. It is made of rubber. It is not used as a joke, either. It is mounted in a tree of a churchyard at Toluco, Mexico, where it constantly reminds the congregation about the temptations of Adam and Eve. No one seems to have thought that it might keep the timid away from church. If Satan ever resided in this snake, he has been knocked out several times, since many people are de- ceived by it and stop to throw stones to kill it. It would not take a Bill Nye to imagine how funny and sheepish a man would feel after he hit this snake paint is likely to remain on for some time. For ourselves, we are forced to admit that a good old-fashioned chimney of red brick covered with Virginia creeper or some other beautiful vine would seem more attractive than artificial plants of this sort; but the world would be a monotonous place indeed if there were no chance for individual expressions of beauty. Frames from Automobile Lenses (ye automobile headlight lenses can be used for framing pictures. Cut down the pictures to suit the size of the glass, and enclose the two in the metal frame that formerly held the lense in place on the car. Next put a piece of cardboard behind the picture to hold it in place and prevent slipping. Then you will have a framed picture ready to be hung on the wall. The nations of Europe learned long ago to make use of all kinds of materials that have always been considered more or less waste in this country; but with the war the United States learned to save all along the line, from food to iron and steel. The habit was certainly a good one, and now very few people throw scraps of any kind away with- out surveying them closely with the idea of putting them to some new and useful purpose, which is a good thing for any nation to learn. Why not get the habit? It will repay you. © Kadel & Herbert Taking Flashlight Photographs Out of Doors gwacneg oe and night scenes can be pho- tographed by flashlight only when a large charge of powder is employed. To handle this charge requires special pre- cautions. A photographer has devised a way to meet the difficulty by employing a pole eight feet long, on the top of which a metal powder-holder is arranged. A wire is connected with a ten-volt battery car- ried by the photographer’s assistant. A fuse of fine German-silver wire connects the electric poles in the powder-containing device, and when the connection is made, a short circuit is pro- duced through this fuse. The powder is thus ignited. Flashlight powders are composed of ma- terials that produce the quality of light that is most active on ordinary photo- graphic emulsion, 71 with a stone, only to find it was a dummy, and to picture him sneaking away before some one saw him. It would be much like asking a scarecrow for a match. Whoever put this rubber snake in the tree must have been a snake hunter or an artist, since he arranged the creature in such a realistic manner. This is just how a snake climbs a tree—by twisting its body around the trunk. The Twelve-Pound Nugget SMALL meteorite—that’s what you might naturally think when you look at the object above. It weighs twelve pounds, and measures four by seven inches. It is not a meteorite, however—but a nugget of pure gold. The nugget, which is worth a small fortune, was discov- ered recently in the Kilo state mines, which are situated in northeastern Congo. Twenty years ago these mines did not exist. Prospectors were searching for gold in the Congo, and were assigned to various territories. The man who had charge of the section that now comprises the Kilo state mines reported that there was no gold in his zone, and asked for new terri- tory. He was told to stick to his own zone, and later he ‘“‘struck it rich.” That twelve-pound gold nugget was there all the time.

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———— Is this a Check-Book or a Cigarette-Case ? ET your’ check-book be worthy of the checks with- in. If you are a rich man and think nothing of making out four-figure checks, then you should have a check-book of gold trimmed with platinum, like the one shown above. The plati- num comes in the form of a name-plate that decorates one corner of the book. This book of gold is very small—it will hang gracefully from the end of a watch-chain. The blank checks within it must be folded twice before they will fit. Six Miles of Fire-Hose HE firemen of San Francisco, Califor- nia, will not be caught napping when a big fire starts in their city. Ina recent test of the efficiency of the city’s fire-fighting apparatus, 32,000 feet of 234- and 214-inch hose was used by 110 men of the depart- ment in demonstrating just what chance they would have with such an equipment. San Francisco’s high-pressure system utilizes the salt water pumped from the bay and stored in an immense reservoir on a hill almost one thousand feet above sea- level. The total pressure available is 314 pounds, but in this test a pressure of only 150 pounds was used. With this reduced pressure the stream was hurled over the city’s tallest buildings. Since the great fire, the city has spent more than $20,000,000 to improve its fire-fighting apparatus. © Kadel & Herbert Building a Pyramid of Oil Cake ' HAT is oil cake? It is a product composed of flaxseed, cottonseed, hempseed, rapeseed, etc., from which the oil has been pressed out. In the jaws of the powerful presses it is compressed into comparatively thin sheets, and is stacked to be sold as food for stock. Some of the oil cake is used in the gar- den in place of manure as a blanket of pro- tecting warmth for the hidden germs of plant life. In the picture women workers of Lan- cashire, England, are building a pyramid of oil cake. The “cakes” are arranged to permit a free current of air through the pyramid. Popular Science Month, Silver Dice in a Golden Bullet EN who like to shake dice can buy tiny cubes of silver. They are so small that five of them can be contained easily in a hollow gold bullet The little gold bullet, with its silver dice, makes an attrac- tive ornament for a_ watch- chain, and if the wearer has heard other bullets whip the air and escaped their sting, per- haps he will have the same good luck with this golden bullet. And that is what a number of players count on—the idea that luck was with them when the greatest stake of all was played for. An Eighty-Year-Old Dancer Te? old to get a job, the man in this picture became a beggar—but not the ordinary kind. He gives the public some- thing for their money. Every morning he starts out, wheeling before him a baby- carriage on which is mounted a phono- graph. When he reaches a crowded cor- ner, he starts his phonograph and dances to the tune of it. If the picture below shows an average audience, the old man is given a great deal of encouragement by the passers-by. True, he is not an expert dancer; but the pathetic picture he makes has won him many a coin. It is to be hoped that the phonograph will not weary of well doing, but that it will cheer the ancient dancer on as long as he lives. He is a German and he dances in Berlin. © Kadel & Herbert 72 January ——— A Tyo m various shift le shiftiny strong! it bec¢ poker. top is fire. The the flo ficient with e down\ playec autor junkn r F H Wi Thee caps | They place Th bridg ss Popular Science Monthly Jan

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January, 1921 A Gear-Shift-Lever Poker “SON’T sell your battered old auto- mobile to the junkman—use the various parts in your home. The gear- shift lever, for instance, can be used for shifting logs instead of gears. It is strongly made and easily handled; thus it becomes an excellent substitute for a poker. The ball-shaped knob at the top is not affected by the heat of the fire. The part that is usually hidden below the floor-boards of the car is curved suf- ficiently to enable you to adjust the logs with ease. Of course, that is quite a step downward for the lever, which formerly played such an important part in the automobile; but who knows what the junkman would have done with it? His **Kick to the Moon’’ OW will this man, who has made a somersault from the plank, strike the water? The art of photography has been the means of analyzing motions that are far too swift to be caught by the eye. When a series of motion-pictures is taken of men jumping, diving, or running, a precise rec- ord is made of the sequence of movements. When these are studied, athletes dis- cover new ways to improve their skill. This view of the diver, executing a high somersault, called a “‘kick to the moon,” is remarkable because it was taken from such an unusual angle. She Blows the Wheel Around HE wheel in the picture above is made to rotate by means of a stream of air which the statue—a Nereid—blows at it. The ball-bearings, rolling in pol- ished races within the wheel, not only facilitate rotation, but they also reduce the amount of friction usually generated by a rotating wheel. The Nereids are water-nymphs. The one in our picture has been transferred to the land. We are familiar with the use of beauti- ful statuary in connection with fountains in public and house gardens, but utilizing such art objects for purely commercial purposes is new to us. It should not be discouraged; beauty and utility being the almost perfect combination. How the Tide Helped the Bridge-Builders "T‘HE span of the bridge pictured below weighs more than two hundred tons. The engineers had to put on their thinking- caps when it came to getting it into place. They constructed heavy pontoons and placed the span upon them. The Potomac river, over which the bridge is constructed, has a changing 1921 January, water-level due to the ocean tides. At high tide the pontoons were floated into place, and as the tide went out, the big arch was gradually lowered into its place. Thus one of nature’s forces was put to use and so saved a great deal of extra labor and expense. So successful was this constructional ‘. ee ——— een a4 73 “stunt” that the engineers in charge of the construction plan to put the other spans of the bridge in place by the same method. When the trick was done, the engineers did not have to wait long for the tide to do its work since it changes every six hours. After the spans were firmly fastened in place, the tide carried the pontoons out with it. ) Keyston View Company

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Trapping the Flying Rivets ERE is a device that captures every rivet and holds it until the “‘rivet- catcher’’ is full. Machines operated by compressed air rain blows in quick succession under the head of the rivet to be removed. Then it flies into the air, like a shot from a gun. Operated on steel frame structures, these aimless shots have been the source of narrow escapes or of accidents. Hence a device that will capture them before they have a chance to do harm is welcome. The ‘“‘catcher’’ shown slips forward, com- pletely covering the rivet after the cutting chisel has been placed in position. Here the ‘‘catcher’’ is seen closed while the gun is operating. The Little Pocket Atomizer U' is not always possible to clean eye- glasses with the corner of one’s hand- kerchief when nothing but moisture will remove the particles that have adhered to the glass. The more a man rubs the glass under such conditions, the more likely is he to scratch the lens, and scratches can not be removed without the expense and time for repolishing. A few “‘atoms”’ of moisture from the new atomizer will possibly save the valuable lenses. Reach into your pocket and take out this diminutive atom- izer. It is filled with cleansing liquid, and can be of instant service in removing the dust from the eyes’ ‘“window- panes.” To try to look through a film of dust is not only injurious to the eyesight but, with this atomizer, is a needless bother. When a Pencil Turns into a Foot-Rule LEAUV-PENCIL that can be con- verted into a foot-rule is a convenient thing to have. The owner has only to give a pull at the opposite ends of the pencil, and its telescoped parts are drawn out to twelve inches. The pencil-rule is of sterling silver and is fitted with a clip to hold it in the pocket. Another style of this pencil has a clamp that attaches it to the watch-chain. The scale is marked in sixteenths, eighths, and quarters of an inch, with the inches numbered as usual. The lead is held by a silver cap like that of other pencils. This Truck Carries Its Own Loading Crane HICAGO, in the shape of a manufac- turer, has come to the relief of the man who loads heavy and clumsy objects on motor-trucks and then tells the boss how he loves his muscle-developing job. By installing the crane shown in the picture, from five hundred to one thousand pounds of material may be loaded quickly by one man. It is possible to level the beam by an adjusting device at the front end and the load can be locked at any point on the beam by means of a brake on the trolley. This mechanical giant can run with greater speed than the trolley. Popular Science Monthly © Central News Photo Service Which Ball Is Stationary? ALL-BEARINGS are manufactured with the greatest precision. Extreme care is taken with all sizes, but the larger and more expensive bearings of the size illustrated are products of a highly per- fected science. As a simple test of accuracy, one manu- facturer mounted two balls of the same size side by side. He set one ball revolving on its pedestal and let the other remain still. So quietly and perfectly did the one ball revolve that it was necessary for an observer to place his hand on the revolv- ing ball to prove to himself that it was moving. While this test is by no means a scientific one, it is nevertheless interesting. Sharpening Phonograph Needles [Don't throw away your steel phono- graph needles. Here is a simple device attached to the top of the talking- machine that repoints the old needles. It is a small metal frame with a small drive wheel that runs by friction upon the rim of the phonograph turntable. The phono- graph motor may thus play a record or run the needle-sharpener, as desired. A small tube is arranged to hold the abrasive that both grinds and polishes the point of the needle. The needle is inserted in a hole at the top of the tube, while a small screw at the closed end of the tube enables one to regu- late the point, making it rounded or very sharp. A screw holds the “pointer” to the case of the talking-machine, which allows the operator to swing the sharpener against the revolving turntable. Januar, ce © Keys Mes N sor abou do they but the and the Need on ska in a 2 abunda perfect In p not to adopte messenr The b watch other the str To K HI ba recogn cleanil stand brush contai of the rags t golf-c The comp: nize v Popular Science Monthy Jani

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January, 1921 — © Keystone View Company. Messenger-Girls on Skates - some large offices errand-girls skim about on roller-skates. Not only do they save time and make more trips, but the work becomes a form of sport and therefore more interesting. Needless to say, these young Jadies on skates would outclass their rivals in a rink, for they have had _ the abundance of practice that makes perfect. In parts of cities where the traffic is not too heavy, this practice might be adopted by errand-boys and by the messenger-boys carrying telegrams. The boys would then have time to watch new building operations and other interesting things going on in the street. To Keep the Golf-Balls Clean hee man who has to clean the golf- balls, after they have become un- recognizable, will appreciate this ball- cleaning apparatus. It consists of a stand made of metal, with a scrubbing- brush and bucket, and a spouting bucket containing fresh water. On the bottom of the stand is a receptacle for wiping- rags that are sometimes thrown on the golf-course. These stands, which are well and compactly made, are painted to harmo- nize with the club’s colors. pio lan? drwy. 1921 es ‘ The Crushing Test for Bricks and Concrete ONCRETE- and_ brick-testing ma- chines are in use at the Bureau of Standards at Washington, D. C. This giant press can be made to exert a crushing pressure of ten million pounds. This would be equivalent to the weight of at least twenty large locomotives with their tenders. The sample of brick structure or con- crete to be tested is put together under the ram of the machine. The motors are put in operation, and down comes the ram, slowly, but with a terrific crushing force. After the right degree of pressure for the sample under test has been reached, en- gineers measure the amount of compres- sion. They are here shown taking a measurement on a column of bricks. Some brick-piles withstand the enormous pres- sure with very little injury. Others are crushed to dust in the first few minutes of the test. When a pile of bricks gets through the test uninjured, they are good bricks. ~ or Paddling Like a Duck N AN is distinctly a land creature. When he goes into deep water, he must either sink or swim. Now, the duck, on the contrary, is perfectly at home in the water. What is the reason for this difference between man and duck? One reason is the duck’s webbed feet; they open and shut when he swims, and add to his speed. If man wore a pair of paddles that opened when he struck out in the water and closed when he drew his feet up, could he swim like a duck? The man in the picture above has annexed a pair of these paddles, and he is practising with them before he attempts a trip to the pool. An Automatic Power Plant ERE is an electric-lighting outfit for country homes, yachts, or camps. It is placed in a white enam- eled steel case that hides the unsightly batteries, gasoline engine, generator, and switches. Everything is enclosed, yet the vital parts of the system are accessible should they give trouble in operation. The fuses and automatic cutouts are mounted on the back of the meter- board. This can be removed like a drawer.

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Popular Science Month, Several New Uses for the Versatile Motor-Boat Engine In the taxidermist’s workshop the little en- gine drives a variety of machines helpful in different branches of the work, saving much time and labor No wonder the presiding spirit of the laundry looks happy. The little motor-boat engine re- lieves her of all hard work by driving the washing - machine, the wringer, and the dryer Hitched to a_ small force pump, the boat engine will draw water from the spring, well, or pond, and pump it into the reservoir in the attic which sup- plies kitchen and bath- room with clear water An automobile like that shown here, with the boat engine as its driving power, can be built by boys who love to tinker with tools and machinery. It means valuable training and no end of fun With a little ingenuity the boat engine can be adapted to supply the motive power of a motor-sled which can be built in spare hours and will afford pleasure dur- ing the winter months For strictly practical purposes the little boat engine may also be adapted in many different ways. Here is one that supplies the motive power for driving a circular saw in construction work ea Popular Science Monthy Jan ia Ke N p time, 4 by a! It W It pro truck | form printe low1n¢ of the the di far tk the ti! trip; whet was stop; numb of eac when repla pairs them when line avera of ga muck the i trips. D B' coup a sid belo’ Mas Tl eyel it s side- T sing diffi mac was side T easi app frei T tow — Janua

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thiy we Se =] Jan ary, 1921 Keeping Tab on a Motor-Truck MECHANICAL cost-accountant, recording the ex- A penditures for truck operation in terms of material, time, and distance, has recently been placed on the market by a manufacturer of fare-registers and taximeters. It weighs seven pounds and is placed on the truck dash. It provides a complete printed record of all details of the truck’s work during the day. This record is in condensed form and is proof against tampering, being indelibly printed. It gives the fol- lowing information: Driver of the truck; date; when the day’s work began; how far the truck was driven; the time consumed by each trip; the time of each stop; whether or not the engine was running during the stop; mileage of each trip; number of each trip; weight of each load; when loaded; when and what tires were replaced, if any; when re- pairs were made; who made them and how long it took; when and how much gaso- line was taken on;_ the average mileage per gallon of gasoline; when and how This little register gives a much oil was taken on; condensed and permanent A su ieee record of the daily perform- the idle time; number of ance and work of the motor- trips. truck Delivering the Goods RACING together two motor- cycles by means of tie-rods coupled behind a similar machine with a side-car attachment, the man shown below made the trip from Springfield, Massachusetts, to Lima, Ohio. The idea was originated by a motor- cycle dealer of Lima, Ohio, who used it suecessfully for delivering three side-car machines to purchasers in Lima. The problem of doing the same thing with the single-track machines presented but little more difficulty. Bars were used to connect two of the machines parallel to each other and one of them was hitched by a towing-yoke to the rear of a side-car machine. The three machines in this formation were easily handled by one man and were delivered at towing-yoke were made by a blacksmith. making a change of tires How the towed motorcycles This illustration gives a rear were fastened together by view of the three motorcycles iron braces and the method of as they appeared on their long hitching them to the towing journey from Springfield, Mas- side-car machine sachusetts, to Lima, Ohio 77 January, 1921 astamnasiiiat eee opeereee Fad While one of the truck-drivers is on duty the other can enjoy a good rest in the built-in bunk Built-In Bunks for Truck-Drivers OR the convenience of their truck-drivers a large manufacturing concern, running trucks regularly between Akron, Ohio, and Boston, had bunks like that shown here built in their trucks. The run of 1500 miles is made on regular schedule in five days and a half all the year round. It was realized that sleeping quarters must be provided for an extra driver, so the trucks were adapted for this purpose. The result is entirely satisfactory and the drivers get ex- cellent rest while off duty. Entrance is made by climbing on the seat of the driver’s cab. The man off duty is ready for any emergency and can step down to the cab at a moment’s notice. A New Rim Tool that Gives Quick Action A RONT PAWL REVERSIBLE RATCHET HANDLE. RIM HOOK approximately the same cost as involved ina Here is shown a new ad- ‘freight shipment. justable rim tool and the ORKING on the principle of a The necessary parts for the connections and method of operating it in jack; easy to operate and self- adjustable to any size of tire, the new type of rim tool shown in the accom- panying illustrations will enable an amateur to un- lock the rim, remove the tire, substitute a new tire, and lock its rim, in five minutes. The tool will fit any kind and size of split rim. The rim is opened by placing the crossbar of the tool over the rim, with one end near the joint, and moving the handle back and forth a few times. Then the cross- bar is placed over the rim with the joint midway between the ends of the tool. The reversible ratchet on the handle is moved to the forward position; the rear pawl engages with the ratchet, while the front pawl is in the neutral position. By working the handle back and forth, the rim may be collapsed to any desired degree and the tire removed. The pawl action is reversed to mount the new tire and lock the rim.

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Popular Science Month, Januar A Big Midwinter Crop } of Car owners are sure to find § man Space in railway-cars being extremely scarce, a manufac- turing concern in the Middle West solved the transporta- tion problem by loading five trucks in a car : | Summer or winter, this | The simple thermostat, in- | _— serted in the pipe be- ? tween the radiator and " tench aps prac the cylinder block, keeps ter! ~s a ok wn the engine’s temperature he met as a_ talisman. me ee Samat anc point for complete fuel When your tires need inflating during a winter combustion trip, you will be glad to stop at a garage that has one of these double-service air-supply stands Why should not the automobilist carry his best girl’s photograph on the motometer? ARMATURE me Each of the two mufflers shown here takes care of three cylinders and prevents any back pressure on the ex- haust stroke of the motor, helping to keep it clean The magnetic automobile speed- ometer shown above gives accu- rate readings under all tempera- tures. Expansion or contraction of the magnet is compensated for by an automatic thermostatic armature control This new type of cutout is clamped and bolted around the exhaust pipe. In the bottom of the pipe a rectangular hole is cut, and the flapper is inserted F | > ] } } | ; ™ ‘ | % The storage batteries of this new kind of electric taxi Forget to fill the gasoline-tank? Don’t worry; just | are under the radiator and in the space next to the turn the emergency valve on the heel board of the rear | driver’s seat. These compartments also accommodate seat, and you can ride from fifteen to twenty miles on | baggage, clothing, and such things the reserve supply — ao SS anaaeennnntanneonananes 4 —— 78 Popular Science Mon'hi, Junu

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January, 1921 many things of interest here of New Automobile Ideas We ARE GIVING Away F GASOLINE. aan [The latest device for | preventing the theft of | Ford cars is a plunger lock operating a but- terfly valve in the intake manifold be- tween the carburetor and the cylinders Having purchased five gallons of gasoline from this en- terprising dealer, you may get additional fuel free if you are lucky in operating the wheel of fortune place. This new type of con- troller automatically prevents overheating of the battery, pro tects all circuits against over-voltage and burning out, and also indicates the | height of level of the' | electrolyte . ' 7, In some of the newest models of American cars the foot-pedal starter is absent. The starting lever has been placed on the instrument board, alongside of the light switch The tire boot shown here does not have to be strapped in It is placed over the injured part of the tire and is hooked to the felloe with metal lugs _—_— These mittens are at- tached to the steering- wheel of the automo- eT) LL | ; were, WoGAMBLING RA ” ' f | bile by two pivoted 4 | rods in such positions that the driver’s hands, slipped in, can grasp and operate the wheel It is a good plan to carry a nail file. In this instance the file is being used to improve the contact of the plat- inum breaker points Vibration and friction are the two great foes of every automobile engine. By counterbalancing the crankshaft as shown here, the engine lasts longer This portable air-tank, good for a working pressure of two hundred and fifty pounds to the square inch, is far more convenient than a hand pump for inflating tires while touring Junuary, 1921 hly e 79

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In one operation this machine simultaneously drills fifty-four holes in four sides of an automobile cylinder casting Quantity Production and the Drill HE machine pictured is drilling fifty-four holes in one operation in the four-cylinder block of a certain make of automobile. In fact, every hole required in the casting is made at the same time. The operator sets the casting on the table of this remark- able drill, clamps it in place, and the machine does the rest. The drills are simultaneously fed into the work from all sides. The drills on, each side are operated collectively from one “‘head,’’ which encloses a train of gears for revolv- ing each individual drill-spindle. This machine drills the casting in one minute and forty seconds. The Horn Toots as Car Burns OWARD WILL, of Syracuse, New York, lost his automobile in a recent garage fire. While the flames were raging in the building and destroy- ing its valuable contents, the horn of Mr. Will’s car blew continually as if it were calling its master or summoning the help of the fire department. Y ~~ sHort circuit ee ~ ° ao NS Short-circuiting caused the horn ofa car in a garage fire to sound continu- ously during the fire Popular Science Monh|y Controlling a Primer Electrically OME one with real ingenuity has found a way of utilizing an almost negligible part of the elec:ric energy in the storage battery of the automobile to ¢) a big service for the motorist. He has designed a thin metal piece to go be- tween the manifold flange and the carburetor connection after the manner of a gasket. This piece carries at one side a well-enclosed electro- magnet, connected with the automobile’s elec- trical system. In the center of the solenoid there is a little vertically mounted valve held down by a spring, that nor- mally prevents the flow of gasoline through the primer. But when the starter pedal is depressed, the electro-magnet is energized, raising the valve from its seat and allowing gasoline to flow through the primer and to spray into the manifold through a hole in the intermediary member. The gasoline is warmed by the heat of the energized solenoid. SOLENOID (ENE2GIZED By STARTER PEDAL) Tf) rose TO PRIMER OR AND INTAKE MANIFOL)D When the starter pedal is depressed an electro magnet raises’ the valve and sends warmed gasoline to the primer, all ready fo: ignition A Demountable Road-Oiling Tank HILE a motor-truck does not eat its head off like a horse when not employed in useful work, the over- head charges of interest on the investment, depreciation, etc., go on just the same. For that reason many road contractors with a comparatively small amount of road oiling to perform have employed horse-drawn equipment. Q Now, because but little road-repair work was done during the war, there is more road main- tenance and oiling to be done than ever before and contractors who have contracts for road oiling need no longer place their faith in the horse. A Boston manufacturer has put on the market a special oil tank and spraying apparatus which may be removed from the motor-truck chassis in less than half an hour and replaced, when desired, in the same length of time. The mounting or dismounting may be done without detaching any There are two explana- tions of this peculiar phe- nomenon possible. The first, that the heat caused the horn button to melt and made a short circuit between the points. The second explanation, which we are inclined to believe correct, is that the heat burned through the insula- tion of the horn wires, causing a short circuit be- low the horn button. The diagram illustrates what probably happened in this remarkable case. What- ever the cause, the inci- L parts, disconnecting any piping, or in any way disturbing the adjustment of the tank equipment. This is accomplished by mounting the tank and oil-distributing nozzles, and all the piping on a separate subframe, that is attached in turn to the frame of the truck chassi by means of ten bolts. When the nuts are un- screwed, the entire oiling apparatus may be lifted from the chassis by means of blocks and falls and lowered on a platform 0: dent attracted consider- able attention. When the road-oiling plant is not needed it can be removed and another body can be substituted in its place 80 trestle until it is again required. J :nuarl Popular Scvence Monthly

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KE Junuary, 1921 The Automobile in First-Aid Work In cases of emergency it will supply material help for medical treatment iv. 3 > Lary = is / = s ; / en = Sn - see SS The search lamp, with its glass removed, will relieve earache if you place it over the troublesome ear and keep it there When a tourniquet is needed to stop bleeding from tc et . sf . = S _— _ In an emergency a serviceable hot-water bag may | an artery, tie a cloth around the arm or leg and be improvised from two feet of inner tubing tied | twist it with a wrench or hammer until it is tight at both ends. The hot water for filling the bag may enough to stop the circulation be obtained from the radiator Sp 4: Folded side curtains, Broad strips of adhe- } wound firmly around sive plaster or insu- a broken arm or leg, lation tape should make a very satisfac- e » de : WR St NA te, always be in the tool- | ati tory splint in an emer- Fhe eg chest of the car. They gency case. The tem- |73 ; eat Nas ’ : } | will be found use- | porary splint should be Se sf mgs 3 : | ful for bandaging a fixed with strips of ad- ; sprained foot or ankle hesive tape during a touring-trip With a flexible shaft, the motor fan, and a camera tripod relief can be given to a fainting person. The shaft is driven by the car engine 81 January, 1921

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This large disk grinder revolves in a horizontal plane and gravity keeps the work pressed against the abrasive surface Rest the Work on the Grinder HIS is a disk-grinder used for large work. The steel disk, covered with abrasive paper or cloth, revolves horizontally, and the objects to be ground rest on the surface. It is not necessary to apply any pressure. A hoist located beside the grinder lifts the work upon the disk. The grinder also has a small suction fan that carries away the metal and abrasive dust. The disk measures fifty-three inches in diameter, weighs eight hun- dred pounds, and revolves at high speed. The grinder is used especially for surfacing work, Popular Science Monthly Through Two Looking-Glasses HAT’S up?” you say, as you see a crowd gathering in front of a store window. There you see, besides the usual display of goods, a mirror that reflects charming unseen creatures in the latest creations. Where are the originals? They are up on the floor above. Double reflection, as in the case of the periscope, makes it possible for you to see them. This is a new “advertising display device’ for use where show-window space is limited. It was invented by William Sliter, of San Francisco. The advertiser sets his scene on the second floor where he has plenty of space. Then he adjusts his mirrors to the proper angles. é How can you advertise many goods in a small window? Arrange your goods on the second floor and adjust two mirrors, periscope fashion The Igloo of the Victoria Land Eskimo N the picture the gentleman is not trying to compete with the ice trust. He is providing a place of abode for the long sunless nights of an arctic winter. Having left his tepee, or skin tent, which he had occupied during the short summer months, along the fringe of the barren lands of the un- known northland of our continent, he is now erecting his house for the winter. The implement in his hand ting snow blocks for his winter head- quarters. Blocks from two to three feet long are placed upon one another, with a slight inclination toward the center. After he has built to a height that suits his fancy, blocks are placed to form the roof. For a window he places a block of clear ice, that is often carried for many miles, as it cannot always be obtained at the place that he selects for his snow house. A small opening is left for an entrance. This is usually protected by a wall of snow blocks to prevent snow from drifting in front of the igloo door, and it also acts as a protection from the winds, which blow with arctic fury. The inside tempera- ture cannot be below freezing or the blocks would melt and the house col- is a copper knife about twelve inches long. The metal for many of his im- plements he gets from the shores of the Coppermine river, that flows into Coro- nation gulf, an inlet of the Arctic ocean. Since he knows nothing about smelting or melting ore, he depends upon a flint- like stone to hammer the vir- gin metal into the shape he wants. His copper knife is a utili- lapse. Heat is secured by the ignition of seal oil in a small soapstone lamp. Since he prefers uncooked food rather than cooked, even at a temperature of 50 degrees be- low zero, and sometimes 80 degrees, the question of heat for cooking is of no consider- ation to him as an item of household comfort. Since there is no provision for ventilation, and the odor of his sealskin garments with- holds nothing in the aggre- tarian affair, and is used for many purposes. But most valuable of all is it for cut- winter. Getting ready for the long, sunless nights of an arctic : 1: } The Eskimo who is adding an ice block to his try to totalize the atmos- house cuts the blocks with a twelve-inch copper knife 82 gate of smells, the reader may pheric result. Janu —_ nee at meee Popular Science Monthly ano’ ent, « sbneannee AC wee a Le.

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January, 1921 How to Make a Hand- or Power-Driven Blower HE man with a home shop often feels the need of a small hand- or power-d.iven blower to operate a forge or blowpipe or perhaps to use as an exhaust fan in connection with a woodworking machine or grinding- wheel or to ventilate a room. While such blowers are of simple construction, the making of the hous- ing is the source of some difficulty, for if the bearings are integra! with the casing, as is usually the case, this must be a casting of substantial construc- tion to withstand the strain and would require a more or less complicated casting. To simplify matters, our method of construction follows the lines of the large ‘“‘steel plate’? blow- ers, the housing being cut out of gal- vanized iron and soldered together with the bearing pedestals entirely independent. Two types are shown, a regular blower and one for exhaust purposes, though the latter is adapted to both classes of work. A 6-in. fan is shown. This size is capable of being driven at about 3000 revolutions per minute by a 4 or % horsepower motor, or it could be hand-driven by removing the grind- ing-whee! from an ordinary geared grinding-stand, substituting a pulley in its place and belting to the blower. If the power at hand is greater or less than this, it would be better to make an experimental fan wheel, without the housing, and cut down the blades eiediias Satna until the motor Th ai Oe is able to drive USED) ~*8 x it at the required \4 speed without overheating. The gxe}——|» housing could Ways “+, then be propor- a ! \ 74 tioned accord- | sh ingly. - A sc roll- BEND )é s ‘| shaped housing ome gs isshown. Thisis et lel oe be —,.* dividing a circle G stuns Feo Bac \ into 12 equal sovbeR PiATE. »—s§%\—Ss parts, remember- ji ing that the di- viders when set at any given radius *—l1—¢* “will mark off the ie Na circumference in- t ‘3-""-----gFig2 to 6 equal parts, and these may then be halved. Then lay off a circle represent- ing the diameter of the fan wheel and mark one radius so that it will just clear the outline of the wheel. Keep on around the circle, extend- ing each of the eleven remaining radii by an equal amount, and draw a smooth curve through the points. Fig. 1 shows this layoff when using the 6-in. fan, the numbers being the lengths of the radii in inches to the edge of the side casing, the end-plates being extended 1g in. all round to allow for soldering Fig. 1: Rear-end housing. Make hole large enough Fig. 2: Front plate of fan housing January, 1921 . a eo@ @a = = 2. -. By H. H. Parker the housing together from the outside. The exhaust outlet may be in any position, horizontal or vertical, up or down, by changing the position of the bent-over base strip. The galvanized iron used should be about 22 or 24 gage or as heavy as could be cut by tinner’s snips without great difficulty. While the outline of the two end-plates should be exactly alike, the front one should have an opening cut out large enough to admit the wheel, unless the builder was sure that no further experimenting would be required, in which case the housing might be soldered together after in- serting wheel and shaft. An air inlet is cut in the front-plate cover and one of the same size in the back plate for an ordinary blower; the exhaust type should have a hole large enough to admit only the wheel flange. These FIG4 FIGS Fig. 3: Side elevation, blower type Fig. 4: End elevation, blower type openings are best cut by drilling a series of small holes with a hand-drill, cutting the piece free with a smal! cold chisel and finishing the edge with a half-round file. A series of holes are drilled around the edge of the center opening of the front housing plate, Fig. 2, and tapped 8/36-in. Round head 8/36-in. machine screws about !4 in. long are then screwed in from the back, the heads filed off flat, and secured by a little solder. These act as studs to hold the cover plate. A paper gasket should be placed between when finally bolting the cover plate in place. The side of the housing is made of a 2-in. strip of galvanized iron bent around to follow the dotted line of Fig. 1 and the end-plates are soldered to it, taking care to keep the side casing at right angles to the ends and the end-plates parallel to each other. The bottom edges of the end-plates are bent over and drilled for screws which fasten the housing to the hard- wood base. See Figs. 3, 4, and 5. A square frame which connects with the blower-pipe is bent up to slip tightly inside of the outlet, Fig. 3, and is soldered to the pipe. If an exhaust blower is built. a round flange is sol- dered to the cover-plate intake open- ing for connection to the exhaust line, Fig. 5. Figures 6 and 7 illustrate two types 83 of fan wheel. The exhaust fan is made by riveting and soldering four gal- vanized-iron blades to a circular back plate. Then an ordinary round belt pulley, such as is supplied with small electric motors, after having the for- Fig. 5: Side elevation, exhaust type Fig. 6: Fan wheel, exhaust type Fig. 7: Fan wheel, blower type ward pulley-groove flange filed off, is screwed to the forward face of the disk and provided with a set screw to hold it to the drive shaft. The blower fan is built up without much difficulty by cutting out two spiders from the galvanized iron, drilling them for the shaft, soldering or riveting the blades to the spider arms, and soldering the shaft in place. If the fan is to be driven at a very high speed, the blades ought to be curved backward, and if at a relatively low speed, forward, to derive the greatest efficiency, but the straight- blade types shown will blow enough for average use. An Adjustable Bench Light from Odds and Ends HE illustration shows an electric- light fixture which has been used with great success. It is made from odds and ends picked up around the shop or home, and it is so built that NTER-WE IGHT This light can be shifted to any po- sition and requires no fastening to hold it it will stand any amount of hard service. It will throw light in any direction and it stays wherever it is put, as the counterweight on the upper end of the piece of tubing just balances the weight of the lamp at the lower end.—H. M. KRANER.

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A Homemade Bellows for Your Camera By Ernest Bade HEN a photographic camera has been in use for several years, it usually begins to give evidence of its old age. The first sign is almost in- variably shown by the bellows, which begin to crack at the creases and de- velop leaks at the corners. The light coming through these cracks and

Figure 1 shows the mapping out of the bellows and the manner of pasting down the cardboard strips holes causes the films of plates exposed in photographing to become “‘light- struck.” For a while judiciously applied patches may extend the life of the camera, but eventually the time will come when new bellows must be put in the place of the old. New bellows for every standard make of camera may be purchased from the dealers or manufacturers, but in cases of emergency it may be desirable for amateur photographers to make their own bellows rather than risk the delay and expense connected with the purchase of ready-made bellows from the dealer. The making of bellows which are not tapering but have the same di- mensions at both ends is compara- tively easy; tapering bellows are a

Figure 2 illustrates the method of pasting down the overlapping margin in joining the sides of the tube little more difficult to make. The de- scription given here refers to the making of bellows which do not taper. A good material for camera bellows: is thin and soft leather, which should be perfectly opaque. If this is not obtainable, or is too expensive, thin, rubber-coated cloth of black or dark brown color may be used. It should have no pinholes or other defects and

should be perfectly opaque in all its parts. First ascertain the dimensions of your old bellows. Place the material for the new bellows on a table or other flat and smooth surface and mark on the unenamelled side of the material the dimensions of the bellows, as shown in Fig. 1. Draw cross-lines at right angles, marking the folds of the bellows. Cut strips of thin cardboard, shaped like those in the picture, and paste them with thin glue on the material, as shown in Fig. 1. After all strips have been pasted down in the manner indicated, a single sheet of black paper or thin, lightproof cloth is pasted over the material. Then fold the covering of the bellows at the lines marking the height and width, so as to form a tube, and paste the 1l-in. margin left on one

Figure 3 indicates how the bellows should be folded by pressing down the creases with a small ruler side so that it overlaps the edge of the opposite side, as shown in Fig. 2. The next step is the folding of the bellows, which is best done with a small ruler, in the manner indicated in Fig. 3. To give to the finished bellows a neat appearance, great care should be taken that the folds are regular in form and all alike on each side. This completes the bellows, which may then be glued to the frame of the camera. Removing Burnt Oxide from Porcelain Crucibles HEMISTS and metallurgists often find it extremely difficult to remove burnt-in metal oxides from porcelain crucibles without injuring them. J. Willard Hershey, professor of chemistry at McPherson College, Kansas, recommends the following method: Fill the crucible about half full of aqua regia and add a few drops of hydrofluoric acid. The relative proportions of the two acids depend on the condition of the crucible. Ordinarily, after standing for five or ten minutes, the crust of oxide becomes loosened and can be washed 84 Popular Science Monthly out with a stream of water. If the crust is very thick, it may take several hours before it becomes loose enough to be washed out. These acids will not affect the crucibles in the least, pro- vided the glaze is not cracked or chipped off. Chemists who wish to use this method of cleaning their porcelain crucibles should observe the precau- tion of adding at first not more of the hydrofluoric acid than necessary to loosen the crust of oxide, and to add more only when they find that the acid mixture has not the desired effect. Extemporized Knurling May Be Done with a File OMETIMES it is necessary to knurl the edges of small brass screwheads or nuts when no knurling machine is available. A fairly satisfactory knurl may be put on brass or even soft steel or iron pieces by means of a new sharp file, either straight or cross cut, and some hardwood blocks. One of the illustrations shows how this may be done by hand. The file is placed upon a hardwood block and clamped to it by means of two built-up or grooved strips held by screws or bolts. A narrow groove, about the width of the edge of the piece to be knurled, is left between the two clamp strips and the piece of work is rolled back and forth in this groove, over the file teeth, by means of another hardwood block on top of it. Hard pressure will be nec- essary and not too coarse a file. If a lathe is at hand, an alternate PRESSURE HERE

goer wood SS — == ~> eee es ee IN

- —— HARD WO CHUCK ~ od

WORK Tk, cei “}) ~<~— CLAMP ea es es 1) ae a z: =I" FILE VOGT) lx

“SLIDE REST If you have no knurling machine in your shop, you may put a knurl on small brass screwheads by rolling them over a new, sharp file method would be to place the work in the chuck and mount the file and hard- wood block on the cross slide under- neath; the block should be of such a height that it and the file will be drawn across the tool slide when the lathe spindle is slowly revolved by pulling on the belt by hand; if necessary, assistance may be furnished by the cross-feed handle. Such work will not look quite as well as though performed with the regular lathe knurl, but in many cases will answer the purpose when the proper equipment is not conveniently ob- tainable.—H. H. PARKER. a 4 : Ss hs HARD Woop +=)

Janw ANG 0; 9 mobi insta be 0 enou mete hole drill a Six of h drill drill larg mar It hole up easi acc’ usu als for the ne cie to

Popular Science Monthly Jar

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January, 1921 Drilling Holes through Metal By H. H. Parker Ng capes about the first thing yi the machine-shop man learns to co, perhaps a few words to the auto- mobile owner or home mechanic who is installing a small drill-press may not be out of place. Of course it is easy enough to make a dent in a piece of metal with a center punch and drill a hole through the piece, but whether the drill follows the punch mark or runs off a sixteenth of an inchor so, is a question of luck to a great extent, unless the drill is perfectly sharpened and the drill-press in good shape—even so, a large drill will seldom follow the punch mark exactly. It is a good plan first to drill a small hole as shown in Fig. 1 and then follow up with the large drill; it is much easier to get a small drill through accurately and the large one will usually follow the small hole. This also causes less strain on the large drill, for the small hole relieves the point of draw back enough. Several trials may be necessary to get the drill-point centered, but this must be done before the body of the drill enters the hole, for after this happens, it will be almost impossible to draw the drill over any more. If the drill cuts into all four of the prick marks, it is well centered. An- other method is to scribe a circle a little larger in diameter than the required hole, as shown in Fig. 3, with- out making the prick marks around the edge; then if the drill encers accurately, the scribed circle will just be visible entirely around the hole. Figure 8 shows the difference be- tween a prick and center punch; the former has the sharper point, from 4J° to 69°, while the center punch has a blunter point of about 90°. The prick punch is used for the preliminary lay- ing off, as the marks may be more accurately made, while the center

the drill, which punch makes the never cuts effi- _ i. eee final indentation ciently and has | | . eX || for starting the to force its way ve | drill. through the | \*’ || {+} | G) While the sub- metal. I\ / || ject will not be To be sure the | Kaltes. as discussed here, drill will go gsc _— des the correct grind- through in the | LAL Qing of a drill is of right place, how- Mp4 great import- ever, a small ©} >} FIGS. ance; Figure 9 prick mark should | S TAL 7 shows a drill with first be made at | | tlds Wt its lips ground the center of the -— MeO wrongly, one be- cesired hole and aid ae ing longer than a circle, the same —-——.. F the other; in rig. diameter of the _ a ia CQL». 10 the angles of drill to be used, f Yy the lips are un- scribed around it apy equal, the result ne FIG.6 . ° (fig. 2). Then rIG8 being in each case make four prick Ten illustrations are here given which th at the hole, be- marks 906° apart clearly explain the best. method of sides being offi on this_ scribed drilling through metal, true to mark center, will be circle, as shown. If the metal surface is chalked first, or, in the case of very fine work, coppered or blued, the scribed lines and marks will show up much plainer. Now drill the small pilot hole and start the larger drill, but withdraw it before the body part has started to enter the hole—for the first trial, when the point is not over a third of its way in. In all prob- ability the beginning of the hole wil appear as in Fig. 4—off center. This should cause the operator no concern, for he can now proceed to “draw over” the drill. A small chisel with a narrow rounded point like Fig. 7 should be provided and a groove or a series of grooves, if the drill is badly off center, is chiseled down that side of the cavity nearest the center of the re- quired hole, as in Fig. 5. The size of the groove or the number of grooves needed must be found by practice; if too much metal is cut away, the drill will run off on that side; but if the groove was made too small, it will not

January, 1921 larger than the actual diameter of the drill, the defec- tive grinding causing it to “‘wabble.” In regard to lubrication, though it is always necessary to apply oil or lubricating compound to a drill when working on steel or wrought iron, cast iron is drilled dry. Brass is usually drilled without lubrication, but it is customary when working with this metal, as well as copper, to grind off the sharp edges of the drill lips, merely touching the edges to the wheel so that no appreciable amount of the edge will be removel. This expedient will prevent the drill catching when it breaks through; if this precaution is not taken, the operator will have good reason to re- member it next time if he happens to be holding the work when the drill point comes through and the piece starts to whirl around in his hands. This often causes painful lacerations of the skin, which may become infected and lead to a serious case of b!ood-poi oning. 85

An Improved Bar for Lathe-Testing N testing a lathe for the parallelism of its cut, it is customary to make up a steel test bar such as shown in the illustration. A very light cut is taken off each end and the ends are then calipered. After considerable usage, the enlarged ends are finally turned down to the diameter of the center portion of the bar and the whole then becomes useless, requiring the scrapping of a piece of good steel. When turning up a new test bar, or making over the old one, the ends can

SLEEVE SCREWED ON When the sleeves of this lathe-testing bar are completely turned down, new ones can be put in their place be turned down smaller than the center portion, forming shoulders, then either turned taper or threaded. Two sleeves are then turned to a larger outside diameter than the bar and fitted to the ends; as the test cuts are light, the sleeves do not need to be driven or screwed on very tightly. When the diameter of the ends is reduced to that of the center of the bar, they are removed and new sleeves fit- ted. The illustration shows a bar, one end of which has a sleeve screwed on, while the other is driven on to a taper fit.—H. H. PARKER. Use a Screen for Sifting Out the Punchings ERE is a simple yet effective method of separating the punch- ings from the product in punching washers on a press. Take a wire mesh screen and place it at the rear of the punch press as

shown. Place 94 ‘<s) PUNCH PRESS two boxes underneath, Oe | one box di- 0] - » ry = WIRE SCREENS, es rectly under fet, ee neath the : punch, the other in the position WASHERS PUNCHINGS shown. Can you imagine a sim- Down pler method of separating comes the the punchings from the punch, and finished product? out drop both the washer and the punching, but the punching falls through the screen into one box, while the washer travels down until it slides into the other box. This saves time and money to any one who does an appreciable amount of punching.—J. H. Moore.

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“Hexa”—More Powerful than TNT By Graser Schornstheimer ECAUSE little has been said about them, one should not suppose that Germany had no inventions of military importance during the war. It was particularly necessary to dis- cover an explosive that would give greater efficiency to her torpedoes. Hexa-nitrodiphenylsulphide was the result. This explosive, known in the German navy as hera, has an explosive energy ten per cent greater than that of TNT, and thirty per cent greater than that of wet guncotton. Also, it is said to be as safely handled as TNT. In the war heads of the torpedoes it was mixed with wet guncotton to give that weapon greater power, and to some extent it was mixed with TNT. In the case of the 19.7-inch torpedo, which was carried by nearly all the German submarines, it was thus used. When mixed with wet guncotton the total charge was 430 pounds, but when it was used with TNT, the charge was only 330 pounds. It would be difficult to say which of the two charges was the more efficient, but it is plain to be seen that weight and space were saved in the torpedoes by the introduction of this explosive. This was exactly what was needed. The charges of the torpedoes were always sufficient to destroy the ships at which they were aimed, but the range of the torpedo was entirely in- sufficient, and at the extreme ranges the torpedo was so slow as to make it fairly easy for even a slow ship to dodge them. After this new explosive was in- troduced, the famous 19.7-in. torpedo was redesigned. The length became 22.97 feet. The range was lengthened by the additional space that it was possible to give to the machinery. Up to 5500 yards the speed is thirty- five knots, and at 11,700 yards the speed is twenty-eight knots; or, to put it in different words, at six miles the speed is still about thirty land miles an hour. In all the larger ships, after the battle-cruiser Lutzow, an entirely new and very large torpedo was used. It was built to take the war model torpedo—23.6 inches in diameter, the largest used in any service. The war head of this torpedo contains a charge of 550 pounds of explosive, and it combines the greatest explosive energy possible in a torpedo, with the maxi- mum speed at long ranges, for at a range of eight miles the speed is still thirty land miles an hour. The double torpedo tubes for this torpedo, which were fitted to the later flotilla leaders in addition to their four 5.9-inch guns, were so heavy that they had to be handled by electric handling motors on the decks. It is easy to see why the Germans com- plained that these boats were top- heavy and that they rolled badly even in a moderate sea. It has been said that the greatest share of German naval attention was directed to the torpedo service rather than to the training of the gunnery personnel; in fact, some German naval officers charge that gunnery was neglected. This may, in some measure, explain the reason for the failure of the Germans to register hits upon the British after the first few minutes of the battle of Jutland. How Two Boys Made a Motor-Sled By C. H. HE motor-sled shown in one of the pictures and of which details of construction are given, was built by the two boys sitting on the sled, William H. and L. F. Mowery, of Kennett Square, Pennsylvania. This unusual craft was used by them last winter with excellent success and attracted consid- Thomas is made of two flexible steel guider sleds joined together by an oak plank, 13 in. wide, 114 in. thick, and 6 ft. long. The plank is attached to the rear bob with two bolts, each 3¢ in. in diameter. It is raised about 115 in. from the platform of the sled to give to the sled more freedom in following the _ir- regularitics of the erable attention. On their rides over the icy streets and roads in and around their home town, the boys of- tenattained a speed of twenty miles an hour. They found that they could run about seventy-five miles on one gal- ground. The front end of the connecting plank is_ pivoted to a cross-piece, 14 in. wide, 34 in. thick, and 2 ft. 6 in. long, which is screwed to the sled and serves for steering with the feet. A steel plate, 3 lon of gasoline. The motor-sled TT _ oa With this motor-sled its builders can make a speed of twenty miles an hour in.wide, 1 in. thick, and 10 in. long, is 86 Te | Tr, Popular Science Monthly securely bolted to the rear end of the plank with three 3%-in. bolts. To this plate the motor-wheel is fastened. The connecting-shaft of the motor passes edgewise through the steel plate. The controls are similar to those used on a bicycle and are fastened on STEEL 6 FT. PLANK ~) PLATE ) ps Se PIVOT—y NL a See eee sicp_7 SLED m Two sleds, an engine, and a plank are the main components of this motor-sled MOTOR WHEEL~ two pieces of pipe, 34 in. in diameter, which are bolted to the plank by two stud bolts. When winter is over, the motor-wheel can be disconnected from the sleds and -again attached to a bicycle to supply it with motive power during the summer. A Vaive-Spring Compressor Made from Tool Steel UMEROUS as are the clamps i that have been designed for compressing the valve-springs of auto- mobile engines, another one of ex- tremely simple construction may be added. It is made of octagonal tool steel, 2g in. thick. The steel rod is bent as shown in the accompanying illustration. One end is flattened and the flattened part DRILLAND , TAP FOR 9/6 SCREW \* 5/8" OCTAGON TOOL STEEL if HEAD REMOVED WA VALVE SS A spring > SS }) This valve-spring compressor was made of octagonal tool steel drilled and tapped for a 9/16-in. screw. The other end is also flattened, but is cut so as to form a fork large enough to pass over the valve-stem. The required dimensions are given in the drawing. When the compressor is to be used, the 1l-in. screw is unscrewed far enough that the fork of the tool can engage the valve-stem below , the spring while the screw rests on the valve-head. When the screw is now tightened, the spring will be com- pressed, while the valve-stem will be held in place. After the spring has been compressed sufficiently, the pin may be drawn from the stem and the valve removed. Popular Science Monthly e , a | . | Janue How pr nti glass, Lea dire sensi take back pape Dp. deve anc Wk gla des Januer! — os

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January, 1921 How to Photograph Leaves without a Camera \ HENEVER you wish to make ‘Y prints from leaves, take the printing-frame, place the leaf upon the glass, and lay a bromide paper with the gram. Also bore or punch two small holes at the top. Figure 2 shows how the lower part is bent in the form of a circle to fit the top of the cap. Figure 3 is a side view and shows how the upper arm is bent to attach to the handle. Figure 4 is the top por- tion of the machine as completed. The handle, of course, can be made of wood of almost any sort and size, if it has the required strength, and is attached to a piece of wood, which in Leaves may be photographed by printing direct from them on sensitized paper sensitized side upon the leaf. Then take a little cotton and place on the back of the paper. This presses the paper gently against the leaf. Expose like any other negative and develop. It will be a leaf negative Prints made in this manner show every detail of the structure of the leaves and show every vein and _ veinlet. When positives are required, use glass plates. Make the negative as described and from this negative make a print, the positive. —E. BADE. A Bottle-Capping Machine Made at Home OUSEWIVES and others who have many empty vinegar and soft-drink bottles, and who wish to put up various sorts of fruit-juices, etc., will find this capper to be “‘just what they have been looking for.’’ Many have any number of empty bottles, and can purchase the caps at nominal figures, but hesitate to pay the prices asked for capping-machines. This one can be made at home or by any tinner at a trifling cost. The illustration shows exactly how itis made. Figure 1 is a piece of sheet steel or other metal stout enough to stand the strain for which it is to be used. Cut hot, or cold, with cold chisel, as per dimensions given in dia- January, 1921 Pressing down the lever will fasten the metal cap around the mouth of the bottle turn may be secured to a table or whatever you use for holding the bot- tles while capping. Merely fasten with a hinge, as shown.—G. A. Improvised Drainage for a Suburban Garage NE of the problems for the builder of the suburban garage where drainage facilities are not present is that of disposing of oil, dirty water, mud, ete., when the car is washed or the chassis and engine cleaned with kerosene, the raciator drained, etc. An inexpensive solution of this prob- lem is chown in the accompanying sketch. This consists of an old tank or steel cask with perforations in the sides buried in loose » Ld rock about 14-° four feet un- be: derground. SAG ee This is con- OG-: = 98 nected with QR the drain in PERFORATED BARREL the center of This perforated bar- the garage rel insures drainage floor by a from your garage piece of ‘bent pipe. The bend in the pipe is S shaped, and it acts as a vent check, preventing the odor from the underground tank from returning to the garage. An old metal oil or tar barrel is suitable for this purpose and will last for an indefinite time when it is buried in the loose rock. Make sufficient holes or open- ings in the barrel before it is buried to allow for seepage. 87 A Stocking-Darner thac Is Easily Adjusted HE clamp principle of this darner is not new, though its details are somewhat improved. The novelty lies in the shape of thejball and its adjust- ability to the clamp, giving a much The stocking-darner and the wire holder which holds the material in position greater range of convenience, also al- lowing the ball to be removed entirely from the clamp. Figures 1, 2, 3, and 3a give the three cross-sections of the ball, the numbered lines on each giving the plane of the section bearing the same number. Length of ball, 314 in., width 214 in., depth about the same as width, or a NLL 'S 3a Ways of using the darner for mending holes in various parts of the stocking little less. The flattened upper side (see 1 and 3) serves for leg and other flat darning. The humped lower side (1 and 3), swung around and brought under the clamp, is handy for the point and back of heels, and by reversing the ball, end for end, slim end out, this humped side serves equally well for the under side of heels, while the slim end is for toe darning. The clamp is made of medium stiff spring wire. Figure 4 will make clear its construction. The loop at the end, which serves to clamp the work, should be made to fit as closely as possible the outline of plane 2. The remaining diagrams illustrate the darner’s use on various parts of the stocking.—CHARLES A. PEASE.

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Popular Science Monthly Keep Your Phonograph Records in Order MONG the numerous makes of phonographs there are many of the cabinet style which have shelves on which to keep an abundant supply of records. One oftentimes desires to find a certain record, and unless some efficient means of filing and indexing is employed, it is a rather tedious and confusing job. The following method has been very satisfactorily used and it takes but a short time to manufacture. At a carpenter shop have as many strips as you have shelves cut as shown

32” ea Fr

FIG). ‘ed ais | ama PNR: | CMa -

= Seis ia

FiG.2 iw ses Strips of the dimensions given are first grooved, as shown in Fig. 1; then mitered, as indicated in Fig. 2 in the illustration, Fig. 1. The width of the strip should be 1 in. shorter than the distance "redisted shelves in your phonograph cabinet, that is, as in my cabinet, the distance between shelves is 214 in., so I had strips cut to 113/16 in., thus allowing 1/16 in. for variation. Grooves made by a circular saw of 1/16-in. thickness and adjusted to a depth of 14 in. were cut length- wise of the strips, approximately 1 in. apart. The strips were then cut into three parts, as shown in Fig. 2, and assembled, as shown in Fig. 3. By the use of material 14 in. thick and 121% in. square, placed on the top and bottom of the form shown in Fig. 3 and securely fastened (using either nails or flat-head screws to be

countersunk), the form is made more en Renee Tare ] t ; i) 7 Fig 3 “| i) t i] ' 1 cmaiclieees) ae

The mitered strips are assembled as shown here. There should be one of them for each shelf of the cabinet solid and durable. See Fig. 4. The front ends of parts A and C should be flush with the edge of the ‘in. material. Before assembling B is laid on a By Theron P. Foote

With this record-finder placed in your cabinet you will find it easy to locate and extract any record disk desired drill-press and using a No. 36 drill (.106 in.), holes are drilled all the way through as shown in Fig. 5. Note that the holes do not touch the grooves but are in the center of the ridges made by the grooves. Five-inch lengths of 3/32-in. spring steel, each having a small hole in one end, were tacked on the %-in. ridges between grooves and in such a posi- tion that the free ends overlapped the hole by about lin. See Fig. 5. Using a drill-rod of slightly smaller diameter than the hole, or about 3/32

‘“—FLAT-HEAD SCREWS hy, @ 8

FG Sie Senn eae enn " ea ee ae hpi a ee . ot { " it | 1 OHI [ei pom ) il | \ a | ! | ' a | i! Ij | 1 @,! yO, i a! Wy ; al iy , 21 he i AY | I | | | { I { t { | | | | HT a ' il

14365 FIG. 4 These drawings give an idea of the ap- pearance of the assembled unit for one of the shelves, top and side view in. thick (.0937 in.), cut into as many pieces as there are grooves, each piece being about 21 in. long, and flatten one end. With a No. 55 or smaller drill, make a hole through the center of the flattened portion. See Fig. 6. One-eighth-inch drill-rod in as many pieces as there are grooves and cut into 1034-in. lengths, is threaded on one end and flattened on the other. The thread on the rods is just long enough so that when terminals which come off from dry-cell batteries are 88 screwed on the end of the rod the thread will be just flush with the top of the terminal. Through the flat- tened end drill a hole with a No. 55 or smaller drill. See Fig. 7. Strips of brass 3/16 in. wide, 1/1' in. thick and 7 in. long were cut and drilled as shown in Fig. 8. Two blocks of wood 1% in. wide, 113/16 in. long and about 1 in. thick were drilled with a No. 25 drill (.149 in.), as shown in Fig. 9. They were

N° 36 DRILL

FIG. 5. i ae (855 m®,

/N°30 DRILL Zones, DRILL~ . 2 — $ Sara | a3 FIG 8 Additional detail of the locating device constructed according to the specifica- tions given is shown in Figs. 5 to 8 then mounted by means of glue and small brads on the outside of part C —one approximately 2 in. from the front end of part C, the other to be flush with part B. The rods were then mounted in place and connected to the brass strips by means of small cotter-pins. See Fig. 10. A piece of Yin. drill-rod passes through the holes (drilled with No. 30 drill) in the brass strips and through the 14-in. material extending in back of part B and holding the form to- gether, thus acting as a pivot or axis for the brass strips.. Thus if the long

Gy ©

_-ROD- FiG.6 STRIP -FIG.8 STEEL SPRING "\-COTTER-PIN JOINTS BLOCK -FIG.9 RODS -FIG.7 MiP 1 BLOCK- FIG. 9 BATTERY TERMINALS

f FIG.10 This diagram illustrates the mechanism for locating the records after it has been completely assembled and put in place Popular Science Moni ly January, 4 ama i f

Januar,

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January, 1921 _— f —S——S=_—_=> an { “W onderful, Charlie!” || | ' ‘¢__ and to think we never re- | alized this gorgeous view was i only an hour’s ride from our door.”’ ‘‘It wasn’t, Mae, ’till we got our Harley-Davidson! We ab never could have climbed up | ae. that path with a car. ‘‘Isn’t motorcycle touring great? Think of all the trips we took this past month, and our total expense for gasoline, oil and tires was less than eight dollars! “One trip like this is worth that much, Charlie. I don’t know what I’d do without our Harley-Davidson.”’ a2 ae ey. iF Ask your dealer for a demonstration \ | of “The Best Sport in the World.” HARLEY-DAVIDSON MOTOR Co. MILWAUKEE, WIS. Largest Producers of Motorcycles in the World 1 UI aPieyw-=Day idis@aa “Corlds Champion” 89 7 Tanwar. 1921

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Between You and Success Is there a barrier between you and the big job? Isn’t that barrier the lack of “know how” which the big job requires? Wouldn’t you like to acquire that “know how’? It is not difficult to do. You can quickly tear down the wall which separates you from Success. Eighty of the biggest men in the industrial world today stand ready to help you with methods and ideas that made them successful. Put Yourself in the BIG SALARY Class Now It’s the fellow who “knows” that gets ahead—the man who knows “‘how”’ and “why” gets the worth-while jobs and the big salaries that go with them. It will take only a moment of your time to start toward a prosperous future. Fill out the coupon below—allow us to send you the seven big volumes making up the complete library on Accountancy and Business Management These great books contain a complete busi- ness training for the beginner and are a handy refer- ence work for the ex- ecutive. They cover Prepares for Business Executive every line of business Accountant —show all the new and . better ways of doing Credit Manager | things—explain meth. B kk ods by which men have ookKeeper made money and, best of all, show how YO Cost Clerk can make more money and rise to the posi- tion you would like to have. You don’t have to send us acent forthe privilege of examining these books. Just fill out and mail coupon, American Technical Society Dept. B201 Chicago U.S.A. A ES A AS A A LY TT AT A American Technical Society, Dept. B20!, Chicago, U.S.A. Please send me set of Accountancy and Business Manage- ment in seven volumes for FREE examination, shipping charges collect. I will examine the books thoroughly and if satisfied, will send $2.80 within 7 days and $2 each month until I have paid the special price of $29.80. If 1 decide not to keep the books I will return them at your expense with- in one week. Over 25,000 sets have been sold. This is the 1920 edition— just off the press. Mail the coupon today. Name. Address...... | the head is broken away. | bridge. piece of drill-rod is pushed inward the short piece of drill-rod is pushed out- ward against the free end of the flat spring inside the form. Pieces of cardboard 1/16 in. by 1014 in. by 10! gin. are now placed in the grooves and the whole form placed in one of the shelves. Insert the records between the pieces of cardboard. To take a rec- ord out, push the button (drill-rod with the battery terminal on the end) corresponding to that space and the record moves out about 1% in. or more. Passe-partout and an index complete the record cabinet. How to Extract a Broken Screw T is always a very difficult matter to remove a screw in which one side of The business may be much - simplified by fol- lowing the plan indicated in the illustration. Here a_ small block of wood is cut. The yo\ \ screwdriver is ROKEN NscRow then put into ich ea the groove and the block press- ed well against the tool. As the Turn the screwdriver with the block to remove screw | screwdriver is turned, the block is , moved around as well, with the result that the screw is easily loosened, even if it is rusty. -S. LEONARD BASTIN. ~ Popular Science Mont'|y Supplying a Clock with an Electric Alarm SIMPLE and reliable electric alarm-clock may be made by t:k- ing advantage of the fact that ihe glass of a common round clock may be revolved but will stay set in any p tion. A hole is drilled in the glass near the edge and a smail machine screw js Ts You may have the clock in one room and the alarm, or any number of them, in other rooms fastened in it by a nut on either side. A piece of fine spring brass wire, soldered to the hour-hand, projects slightly farther than the minute-hani( and ‘“‘wipes’” this serew in passing. Care must be taken that the nut does not interfere with the motion of the minute-hand. A _ flexible wire, con- nected by means of a clip to this con- tact, forms the switch for setting or stopping the alarm.—-G. H. ROuSE. Prospecting for Ore with a Vacuum Tube Y ILL the prospector of the future W use a vacuum tube instead of the miner’s pick or the geologist’s hammer? W. L. Carlson and E. C. Hanson of Washington, D. C., seem to think so, for they have patented a means for locating ore bodies by audio-frequency currents. This is brought into the vicinity of a body of ore the circuit will be thrown out of balance and a tone will be heard. The prospector packs the generator, bridge circuit, and amplifies and uses the loop as an exploring coil. On moving the coil horizontally over the earth’s surface, way combines | any change in an audio-fre- ~ theenergy which quency genera- the coil absorbs tor, an exploring coil, a balanced circuit, and a vacuum-tube amplifier as shown in the sketch. The generator supplies current to a divided cir- cuit which looks like the familiar Wheatstone In one arm is a loop of wire; in another a resistance and in- ductance, which exactly balances with the loop. A _ telephone receiver is coupled to these two arms through a transformer and two stages of vacuum tubes. Provided there is balance no sound will be heard. But if the loop 90 ore-finder and the wiring of the ex- ploring coils and induction balance is shown here i a al due to ore behind the surface will ‘'! result in some ‘ unbalance cur- rent. The am- plifiers make this audible. The patent which was _ re- cently issued to the inventors gives no Cetails as to the best size of coil or as to the depth at which ore may be detected. A some- what similar method, however, has been used in France for locating un- exploded shells which lie buried and are a constant source of danger to everybody in the localities where the armies fought. Popular Science 4, nthe Jan go January, 1 Calking an NE of t QO tool | shown in 1 tion. The rounded, I shoulder C presses the CALKING TOC This shows tool as it 1 should be ter of the illustratio Why } H SIM A mad wire. T thin. Cv Then tak graspin wire abc inch and from on begin te it care about needle s get a pe uniform Bend bo backwa fashion about from tl SCTeWS 3 Now wire, pé backwe loops a one hir AN R® A SI consid the fi Greate possib glass gradi facto An

Page 77

January, 1921 n Calking Boiler-Plates with an Improved Tool NE of the best forms for a calking- O tool for boiler-plates is that shown in the accompanying illustra- ws tion. The edge of the tool has a re rounded, projecting rib, with a flat : shoulder on each side. This com- 1e presses the metal and closes up the is seam without > making bad edges, and it does the work quickly and easily. To get the best results, the rib on the edge of the tool should be applied a little below the cen- ter of the thickness of the plate. The illustration makes this point clear. CALKING TOOL This shows the calking- tool as it is used Why Not Make Your Own Hinges at Home? SIMPLE hinge can easily be made from galvanized or copper wire. Take a wire which is not too thin. Cut off a piece about a foot long. Then take aheavy knitting-needle and, grasping the i wire about an inch and a half S from one end, , begin to wind it carefully Baa about the Zz he ; needle so as to get a perfectly uniform coil. Bend bothends backward and fashion a loop about 34 in. from the coil. Into these loops the screws are later placed. Now take a piece of the same kind of wire, pass it through the coil, and bend backward and form another pair of loops as shown in the illustration, and one hinge is complete. . @ This homemade hinge may be very artistic A New Use for the Little Magnifying-Glass EADING a Vernier scale on any style of machinists’ tool causes a considerable strain on the eyes, as the fine graduations are difficult to decipher. This is especially true of a gage such as shown here. By bending a piece of or- dinary wire, fastening it into the tool as shown, and mounting a magnifying- glass on top of the wire, the finest graduations will be seen with satis- factory clearness.—J. H. Moore. Greater accuracy is made Possible by this lens ‘onthe January, 1921 at. AcheTrav Made from a | SAFETY 13 years on the market | More than 2,000,000 in regular use. Sold without a line of advertising— thru the personal recommendation alone of its enthusiastic friends. The Reasons: SIMPLICITY—only three parts. No adjusting. Apart in one second— together in three. CLEANLINESS—no holes, no screws, no springs; instantly cleaned. SAFETY—patented guard holds the blade firmly in place. PRICE—One dollar. Shaving with the Enders is ‘‘Just like wiping your face with a towel.’’ Wa Grcers ENDERS SALES COMPANY, 17 Battery Place, New York ENDERS SELLS FOR $1.00 with six blades of the best quality Swedish-base steel. Packed in a black Keratol box, velvet-lined. FOR SALE BY BEST DEALERS EVERYWHERE. Extra blades, package of 5—35c. Pee 91 ae ER ee ae ag

Page 78

tubes. sound will be heard. ; os $95 om Hour! ‘‘Every hour I spent on my I. C. S. Course has been worth $95 to me! My = my $5,000 a year income, my ome, my family’s happiness—I owe it all to my spare time training with the Inter- national Correspondence Schools!”’ Every mail brings letters from some of the two million I. C. S. students telling of promotions or increases in salary as the rewards of spare time study. What are you doing with the hours afier supper? Can you afford to let them slip by unimproved when you can easily make them mean so much? One tour a day spent with the I. C. S. will prepare you for the position you want in the work you like best. Yes, it will! Two million have proved it. For29 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 130,000 men and women are getting ready right now with the I. C. S. help for the bigger jobs ahead. Your Chance is Here! No matter were 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 circum- stances. No matter how limited your previous ed- ucation, the simply written, wonderfully illus- trated I. C. S, textbooks make it easy to learn. No matter what career you may choose, some one of the 280 I. C.S. Courses will surely suit your needs. When everything has been made easy for you— \vhen one hour a day spent with the I. C. S. ir 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, es oe oe ew TEAR OUT HERE Gem see = oe oes? INTERNATIONAL CORRESPONDENCE SCHOCLS BOX 7608B, SCRANTCN, PA. Explain, without obligating me, how I can qualify for the position, or in the subject, de/ore which I mark X. ELECTRICAL ENGINEER SALESMANSHIP Electric Lighting ana Kys, ADVERTISING Electric Wiring Window Trimmer Telegraph Engineer Show Card Writer Telephone Work Sign Painter MECHANIOAL ENGINEER Railroad Trainman Mechanical Draftsman ILLUSTRATING Machine Shop Practice Cartooning Toolmaker BUSINESS MANAGEMENT Gas Engine Operating Private Secretary CIVIL ENGINEER BOOKKEEPER Surveying and Mapping MINE FOREMAN or ENGR STATIONARY ENGINEER Marine Engineer Ship Draftsman ARCHITECT Contractor and Bullder Architectural Drafteman Concrete Builder Structural Engineer PLUMBING AND HEATING Sheet Metal Worker Textile Overseer or Supt. OHEMIST Mathematics Name Stenographer and Typist Cert. Pub. Accountant TRAFFIC MANAGER Railway Accountant Commercial Law GOOD ENGLISH Teacher Common School Subjects CIVIL SERVICE Railway Mail Clerk AUTOMOBILE OPERATING Auto Repairing Navigation ‘Spanish AGRICULTURE | French Poultry Raising Italian Present Occupation. Street and No City. State. Internat A. Canadians may send this coupon to Sab iM t Corresp , Montreal, 7-26-10 Provided there is balance no But if the loop 90 everybody in the localities where the armies fought. Popular Setence Monthy An Automatic Coalbin By Theron P. Foote OES your wife or your mother complain because she has had to go down-cellar and fill the coalhod? Perhaps it is not simply because she had to carry it up the stairs, but be- cause she had to fill it as well. Build her an automatic coalbin, then show her that all she has to do is to take the coalhod down to the foot of the stairs, place it in the proper place and less than a minute afterward it is ready to be carried upstairs. The construction is very simple and any schoolboy can make his mother happy. Four 2 in. by 4 in., each about 9 ft. long, formed the corners of the structure. Odd pieces of board built the sides of the bin, the bot- tom boards necessarily being of heavy material so as to stand the weight. As ven a ton of coal See... occupies approx- LoS imately 48 sq. ft. N of space, and the coalbin illus- trated holds approximately 100 sq. ft., it will readily be seen that the bin will hold over two tons or 4000 Ibs. The bin should be situated about 3 ft. in front of a cellar window, so that the window may be opened or closed and thus conveniently located so that a chute from a coal-wagon can ent 2r the bin by means of a few removavle boards at the top and back. If convenient, and much preferable, the tops of the four 2 in. by 4 in. should be spiked to the girders hol’ ng the floor above. This will steady the top of the bin and make it last much longer. The chute from the bin to the hod may be made of heavy galvanized iron, and is in two pieces, one of which is securely fastened to the bin and is stationary; the other is fastened to the latter by means of hinges and is mov- able. Pulleys tend to keep the bin closed and as one end of the cords are attached to the back end of the lever shelf the moment the hod is full, its weight will release and start to close the movable section of the chute. The box weight underneath the bin and on one end of the lever shelf is filled with coal and acts as an addi- tional supply which will give approx- imately another hod of coal after the bin is found to be empty and before the coalman has had time to refill it. The lever is mounted between angle- ———— bin is not empty 92 Pcs sty th Nothing strenuous about filling your coal-bucket provided the automatic irons and is slightly movable ‘o the right and left from the front .f the bin. This is done so that after -ctting the hod on the board on the leve shelf, and pulling down the chute the handle may be securely fa ‘teneg back of the lever. As the coal cor tinyes down and into the hod, the hoc grows heavier, overbalancing the audiliary coalbox, and letting the lever ~cleage handle and chute. Asthe cord at’ ached to the chute is also attached to th eal. box, the upward movement of th. coal. box causes the chute to s‘art to close, the \ eights continuing the action and ac. tually closing it, The rods are strips of !{-in. iron, the ends of which come in contact with a rod extending through and holding the sides of the stationary part of the chute thus preventing ~—- the movable part from dropping too low. The front part of the lever shelf is built in the form of a tray so as to catch the few pieces of coal which are apt to jump the sides of the chute or overflow from the hod as it is being filled. A 1s-in. rod extends through two front legs of the bin and is the fulcrum for the lever shelf. Why a Warm Hood-Cover Keeps the Engine Cooler INCE the practice of cove ing automobile bodies with pyroxy!in- coated fabrics has become quite gen- eral, motorists often ask whether ‘he covering of the hood with the heavy waterproof, airtight material Cces not cause the engine to heat up abnorm- ally. Probably there is a simple scientific explanation of why it doesn’t work both ways. A hood-cover doe:n't create heat; it merely retains the heat generated by the engine while in oper- ation. Insummer the engine gener: tes no more heat than in winter, but the hot summer sun beating down on the enameled metal of the uncovered hood creates a much higher degree of heat than comes from the engine itself. ‘The pyroxylin-coated fabric doesn’t at- tract the heat to nearly as great an extent as the polished metal—in other words, it keeps out the heat generaied by the sun, but keeps in the heat gen- erated by the engine, such as does not escape through the vents. graduatio factory cl January, An Ast OST M ing oursel ves lighted w handiwor If you and follo Does i friend make a anythir _. Seew the cigs Take of the | gs BEND v This sh we cu bend shoul¢ to ki table. Rep A I me meth Ta coati of C: tine W tion the | wrin side; and, ing mor

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sass ON TOP OF tne wire, tne nest graduations will be seen with satis- factory clearness.—J. H. Moore.

‘onthe January, 1921 An Ash-Tray Made from a Tin Box OST of us take pleasure in show- M ing a friend some article we © the ourselves have made, and are de- { the f lighted with their appreciation of our etting handiwork. lever If you will but study the drawings hute, @ and follow the description, you can tened inues TOWS iary lease ached Coal- Coal- the art to eights * the d ac. ng it. sare {-in, nds of le in ith a ding and - sides

Does it not make you feel proud if your od, Me ee ST hehe’ picberainee 4 in-every detail friend admires the ash-tray you made? an ee onary oF: ue WDC Pipe: there’s keen chute ff make an ash-tray that will be equal to | | an 54 satisfaction in every puff. © Your | nting meting a p moe ah -. +. dealer~has the shape you like. e part ecure a tin box and use the lid for ig Wee f ) ping the cigar-holder. ’ Ww. yioradtrb ay & CO. Take a chisel and cut it, removing all t part J of the unshaded part. Cut a slit as ' shelf 4 shown in the one cor-

h | the ner so as to be able ‘ le Tew to bend the edges up jump after the fold is made. . eT ne {rom After the unshaded part is cut away, bend | two the uncut parts back, E BOOK Learn Piano! DOYOU LIKETO DRAW? crum as dotted lines indi- Cartoonists are well paid # This Interesting Free Book We will not give you any grand prize if cate, pressing them shows how you can become a skilled player ae nape a ay Fp down with the pliers, : Sot ‘Guorter ususl cost. De, Guion’s famous anxious to develop your talent with a sue- ver id d th h jel at my f Sta on Method is endorsed by, leading pe ehareegsa righ tapos pp i steals Tain an en curve the Fe cane and ails abd anapitts aheen la crars ban wie Shas in stamps for portfolio. of eartoone and ‘ d es u as in Fi 2 SONS. Scientific yet easy to ena tng illustrated. For begin- sample lesson plate, and let us explain. er to cut d e g p, g. ’ hers or teachers, old or young. All music free. Diploma granted, an h ld h 2 Write today for 64-pagze free hook, ‘‘How to Study Musi The W. L. EVANS SCHOOL OF CARTOONING = bend the tin to ho ‘ ir “i cigars. A M. L. QUINN CONSERVATORY, Studio ZA, 598 Columbia Road, Boston, 25 Mass. 825 Leader Bldg. Cleveland, Ohio C 1g piece of blotting-paper xy lin- should be glued to the bottom of box 1800 { gen- B to keep it from scratching the $ ora Story! pear the APOUS r the table.—CHESTER COOPER. no ee gt h- TS cy ow Gat LEAVY nme = woman has found fer way to fame and for- limit Big ei —-am ) 2a oe i ee enace face ga increasing demand. for csitestiensthe booklet Is tree. Gon CARN $25. 7O $75. WaEKry n, —| ¢ jucce:’ ul graduates - * HOOSIER INSTITUTE, Short s St De .. Our_course covers every ase ‘ ntific in an Automobile Dept. 178 nwayne, Indiana command Die Wilte fot catalog, samples, ‘ (Geiser scaex Se” 21 a. mn foe work CELLULOID window i San : ) w In my ‘ yecn’t : : . ARN AUTOS AND automobile hood having cracked LE heat g , TRACTORS I . . . sae me nded 1t by the following simple Wonderful opportunities constant- Ope method: ~ ly offered trained men; we train you thoroughly to start your own

rates Tak j j i “$3 ake good ey as Sia — 2 — S — tough paper, meee expert, driver, shop fore- BURLINGTON man, etc ore ig it on both sides with a solution 3000 graduates making good. 4 of Canada balsam dissolved in turpen- Ss Clevel oy robil School _j 100€ WAS eveland Automobile 00 ee heat tine to render it transparent. VO oe 1821 E, 24th St., Cleveland, Ohio. The masterpiece of watch man- / se _When dry, apply a little more solu- Bositions, temperature. and’ foo: 7 tion to the edges on one side, stick over Perel ‘ A Pocket zor cme, ofgtne eau pew at- s 0 oreign : 7 e1 es { the damaged part and smooth out all | Countries PHONOGRAPH rate of $6.00'8 month. Yi pay only . it an W } kl 3 for $5 rock-bottom price—yes, ‘‘bed rock rinkles, AT LAST! sottem prise ane tewost pr riee at ot 1eTr ; = c e Burlington 8 Bol: ae After twenty-four hours, coat both | 4, The Phonilo is a Write Today em . sides with good transparent varnish, | Agents vice that plays all needle rec- ehoose from. Name and address on gen- and, if has b / ords. Astonish your friends and win So ent om Wath Sasennen i : , lf care has been taken in follow- ‘ applause. It lasts a lifetime. Sells owt is 19th St. and Marshav s not on sound, Postpaid One Dollar in U.S. tvd., Chica o. | tinois ot anadian O : 338 Portage Avenus, Winnipeg, Man. Ing directions, the repair will last for \. LOTS of FUN—NOT A TOY months.—GEORGE H. HOLDEN. Hand-Phonilo Co., A123 W. Madison Street, Chicago ‘ 93

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rat aJob © With Big Money and a Big Future in It Electrical engineering “fills the bill.” There are no greater opportunities in any field than electricity

offers. It is the most interesting of all professions. Science de- pends on electricity — from it comes the X-ray, the healing violet rays— electricity gives essential heat and light— ponderous electric locomotives pull heavy trains over mighty mountains—the telephone, the tele- graph, the aeroplane, the automobile—all must use it. Electricity is life. Something new about it is discovered every day. The man who gets into this field right is sure to succeed. The demand for competent Elec- trical Engineers far exceeds the supply. It is Easy to Master Electrical Engineering Without giving up the work you are now doing, you can speedily prepare yourself to step into a man’s size job with a real man’s pay in the elec- the —= et trical field. stands out in front e sc a You Hold the Key | sets im struction sat- ° ° f h fund to Success in This |0?Xery" Denny ‘ ° paid us. Great Field We offer you an

The Test Just as gold must undergo the acid test, our instruc- tion must undergo

extraordinary oppor- tunity to get into this money-making pro- fession. Let us tell you how we have helped thousands of other young men to secure big paying positions. Let Us Send You Our Latest Electrical Engineering Book It tells you of all FREE the wonderful things in which an Electrical Engineer is master. It shows exactly what his work consists of. It points the way to SUCCESS — to more money, and it is FREE to you. Send for it today. Mail the coupon now. American School Dept. E-201 GED © GED © GED © GED © GED OG, F AMERICAN SCHOOL: Dept. E-201, Drexel Ave. & 58th Si., Chicago.

Chicago, Ui. Explain how I can qualify for position checked @ ..--..Architect#5,000 to16,000 Building Contractor j to $10,000 wile Automobile e Enginees a 64,000 to $10,000 - Automobile Repairman ,- to $4,000. woul Civil eon er $5,000 to $15,000 sonnel a Loy ay 4 & $4,000 to a 000; ‘to $15, 000 aii Certified Doble Ac- countant $7,000 to $15,000 oe" Accountant & — itor SENG

$2,500 ol Draftsman & ao gner $2,500 to $4, 000| we Electrical Engineer e $4,000 to $10,000 titi Genera! Education In one year @ Name

me Lawyer $5,000 to $15, "000 @ ire Mechanical Ao pg =o €4,000 to $10,000 a Shop ee YP 63,000 to $7, a 000 Employment Manager i $4,000 to e $10,000 sod Steam Engineer $2,000 to $4,000 soused Foreman’s Cone $2,000 to 84,000 @ — Sanitary by yey 00 § hist Tele hong Bnaincer ” © $5,000 @ ... Tele; m En neer rer Engin $5,000 sce High Schosl Graduate In two years @ — Fire a ¥ ye Ex: Sr | pm. ‘ fe ncn roan NE NT

A Neat Arrangement of Dry Cells HERE a small electric light is used for illumination it is often desirable to use the dry cells during the day for other purposes, especially when the dry cells are used for the operation of different pieces of ap- paratus. It is a nuisance to dis- connect the cells every time they are to be used, and the following will be found a happy solution of the problem. A neat box with a hinged lid, large enough to hold the number of cells in use, is made. Three or five is a good number. On the side of the box a switch is placed having the same number of contacts as there are dry cells, in other words, a multipoint switch. -On one end of the box near the top a socket to accommodate a miniature bulb of the desired voltage is placed. Below this two binding- posts are secured and near the bottom another single-point switch is placed to control the cur- rent to the light and bind- ing-posts. The binding - posts and lamp are connected in parallel, and when it is de- sired to use the binding - posts, the bulb may be given a few turns to loosen it. This saves the use of an- other switch. If desired, the socket on the box may be Cispensed with and the wires of the miniature lighting system connected directly to the binding-posts. A leather strap is fastened to the box, as shown, for a handle. One end of the strap has a hole cut in it, which slips over a hook at one end of the box, so as to allow the lid to be raised to get at the dry cells. The dry cells are connected in series, that is, the positive pole of one cell to the negative pole of the other, and from each negative or outside pole a wire is lead to one of the contacts on the multipoint switch. Thus it will be seen that as many of the dry cells can be cut in or out of circuit as de- sired. The wires should be connected in the switch-points in consecutive order, so that as the blade of the switch is passed over the contacts, one after another of the cells is cut in or out of circuit. The advantages in having the ce!ls so arranged are many. Being in a box with a handle, they are easily carried about, and the ease with which the cells can be cut in or out of circuit is apparent. It will be found also that the cells will last longer and will be always ready when needed, and that no time is lost in connecting or dis- connecting them when it is desired to use them.—-GEORGE E. PERKINS.

This shows the battery case and the wiring diagram

Popular Science Monthly Stretching a Felt Hat with a Vise NY one who has a felt hat that needs to be made a little large, can bring about the desired egy} without going to a hat-repair shop and sp. ding money on the job. All thatis necessary is an ordinary vise, Make - sure the vise is clean, over the jaws and open them out until there is sufficient pull to stretch the felt as much as is required. If there are sharp corners on the vise. put strips of thin, flexible wood, or springy metal, inside the hat to protect it. Care must be taken not to apply too much force, which would surely ruin the hat.—HoOwArD GREENE. How a felt hat can be stretched with a vise To Clean and Remove Paint from Iron and Steel IMPLE and effective is this way of removing paint from iron and steel. Dissolve 1 lb. of concentrated powdered lye in 3 qts. of hot water, adding lime to make the solution thick enough to spread evenly. The solu- tion should be applied as soon as it is mixed by means of a brush and allowed to remain on the surfaces to be cleaned until it is almost dry. If it is then removed, it will take the paint with it, unless it is very old and thick, in which case a second coat of the solu- tion should be applied after the first has been washed off the surface. Be fore applying a new coat of paint, the metal should be thoroughly washed with a solution composed of 1% lb. of sal soda dissolved in 2 gal. of warm water. After the soda solution has been well applied, the surface of the metal should be wiped or warmed until thoroughly dried. A method similar to this is in use by the United States Coast Artillery for cleaning the ex- terior portions of big guns and their carriages.—F. A. MCLEAN. A Homemade Drinking- Glass Holder F you wish to keep your drinking- glass from getting broken on your desk, keep it on a holder such as is shown in the accompanying illustration. To make a the holder, drive a large wire nail ora <« piece of iron or brass 7 rod, into a wood base. A block of wood, Tothetopofthissolder 2 oe and some twowiresintheformof yire will make a cross, with the ends turned up. If iron wire is used, put a drop of solder on each tip to prevent rusting. this holder qnuary, I

GE’ } Star “ Mode cribes tl steam-en turbines, ters are | It will chanic soft sold pattern- Thi sis mechani Moe neering | 400 1] complet paid, $3 Popu 995

I, TW Re rs TI coms givin factu use. Sk cre of th 10,0( Bes At dene for. every ot To! are n Poy .

Pinte ee: Me jae

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— =-——— tied NA RNA ENE ES Be SAV AEEAIN | Hand-PHnoniio VOo., Hice WH. Madison virecl, Vnicago — 93 ltt i i) ~~ ee onthly qnuary/; 1921 t To Keep the Lathe-Center Well Oiled that LATHE-CENTER on_ which arger work is revolving, should have esult some means of lubrication, so that the shop work being cut will not become over- iding heated. Usually the machinist drops 1 the hat ig is an Sure clean, TIN COVER hat With a cut made in this manner the Jaws lubricant feeds down to the lathe- them center, thus keeping it cool there ‘it i i a a . .t pull a little oil on it now and then, but this C } d h the is poor practice. ontiaence "ih there By cutting a groove to the point of in the bank put the center, as shown in the illustration, sringy GET A HOBBY you provide an excellent method of C tid ct it, MAKE MODELS lubrication. When the lathe-center 1s ontidence y too F : not in use, a tin shield can be placed in the YALE L k - Tuin Start a Home Workshop over the hole.—-J. W. Moore. oc “Model Making,” by R. F. Yates, de- ace gy oe iy gy my | Seventy-five per cent. of the steam-en Ss Ss S 4 © . ° ° os seam “railroads, sum, ete. Thirty Rion Inexpensive Pipe-Cleaners bank locks in use in America ers t te els of various nature “ : aint : Tt ‘will oy a = become a better me- | Are Easily Improvised are YALE, chanic. It mg og — do hard yo my soft so t c temperin rilling, } ° . + " cere og ieee | N ordinary clothespin can be put Your banker selects the time ; way Thisisa book every anateur rae | to another use, that of clean- lock for his vault just as his | mechanic and mode maker shou lave ee Cs : de sitors select their bank— 1 and “ Model Rn yporry describes real engi- | ing the inside of the bowl of your po . rated m0 Pages, "300 Tilustrations. Practical, pi pe. by name and reputation. Only Vater, —giy easily understood. Price, Post- | As the pin is being rotated it works he is even more careful. +h? paid, 9. le | 9 ~~ Popular Science Monthly | | down and conforms to the shape of the Bankers take no chances—they * . 225 West 39th Street, New York | re’ bowl until the bot- know the great security in . pi —— | {A — is reached, YALE Timelocks, Combina- wie a l ee i i tion and Safe Deposit Locks. f itis la ea — the They specify YALE in their er wall of the pipe. contracts, insist upon getting paint \\\q If the bowl of YALE thick, the pipe is too solu- large for the Bankers’ associations have first clothespin, insert officially recommended the | = When your pipe @ Wedge in the YALE Timelock Inspection oa needs cleaning, use Cut of the clothes- | Service. ashed | a clothespin pin. This will | ? of sal | force the two | Next time you go to your gist | prongs wider apart and thus make | bank, ask to be shown the been | them fit the bowl. YALE Timelock, which for metal | half a century has proven eb- until a solutely reliable. lar to Combining Two Useful y + : The same character present in every t at S | F pe TWENTIETH CENTURY | Motor Accessories YALE Timelock is found in every their | TADIES motoring over dusty roads | trio gris of be —_ in Book of generally wear a veil to prevent | eS nee: See R . F ] s the wind from taking undue liberties | — —~ cag fia mene m = : ndustria ectric Trucks. ecipes, ormula with their hair, and goggles to keep the | > and Processes dust out of their eyes. But those who | Always buy by the name and be idk Kall ak ak ci es tit have tried it know that a veil worn over sure that it appears on the product. 1s DOO 18) ) $s 1s 1e Ss . | : complete Book of Recipes ever published, goggles is not a comfortable arrange- | YALE MADE IS YALE MARKED king- giving thousands of recipes for the manu- ment. vour facture of valuable articles for every-day Now : invento with the con- re use. Hints, Helps, Practical Ideas and ‘OW an Inve Tr, alee: The Yale & Towne Mfg. Co. hown Secret Processes covering every branch venience and comfort of the feminine 8 | tas Magn ie ene , Makers of the Yale Locks PF SAE mee ere? motorist at heart, places on the market General Offices & Works: Stamford, Conn DER na p . ° e 7 , : 7 , . / 10,000 Practical Formulas—The | | # motor veil combining the tu | | Saieags Once": 77 Zast Lake Stet ~ i mma adhe aes . Canadian Yale & Towne Ltd. 2 Best Way to Make Everything frame is fitted into the veil, holding in St. Catharines, Ont. A book t thich ye rt vith fi- P ; ; —] 7 , dence that you will find what you are looking place a piece of pyroxylin sheeting cut for. A mine of information, up-to-date in to fit the frame. Thus there 1s no veil wood, every respect. Contains an immense number = 1 b k: che. some of formulas that every one ought to have that over the eyes; no glass to break; Night Latch make are not found in any other work. nothing to catch in the meshes of the F Price $4.00 veil and tear it. If a light amber sheeting is used for the “‘lenses,’’ the h ti Popular Science Monthly : niet “ca 1 tip 225 Weet 39th Street, New York sa are also protected against sun | glare. 95

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MM Get A Canadian Farm from the CANADIAN PACIFIC tT Canadian Pacific Railway offers you a great opportunity to own @ farm home. Many of these farms have paid for themselves with the first crop. Out of its last big block of -eserved farm lands you can buy your farm under a plan of long term easy payments that is roti me in the history of farm investments. Last Big Opportunity Until this land is disposed of the Cana- dian Pacific Railway offers you the most wonderful opportunity in the world to own a farm, achieve independence and grow rich in Western Canada. It offers to sell you farm lands in the rich open rairies and fertile park lands of the loydminster and Battleford Districts of Central Alberta and Saskatchewan or in Manitoba for an average of about $18.00 an acre. Twenty Years to Pay The Canadian Pacific offers you this land under a plan of long term, easy payments. You pay down 10%. Then you have no payment on the principal until the end of the fourth year, then sixteen annual payments. Interest 1s 6%. In Central Saskatchewan, Seager Wheeler grew the world’s prize wheat. World’s prize oats were grown at Lloydminster. Special Rates for Home- seekers and Full Information The Canadian Pacific will not sell you a farm until you have inspected it. To make this easy, special railway rates have been arranged. Do not delay your investigation. This is the last reat blockof Canadian Pacific Reserved UOSTUUUUVAVEOUONIONUNCOHIANANASUUUOAUHUOVUGUECUFLONATONECIOVONIHIVUTINGNNNVNVONNTNItiNTieNiN ~ “w ~* ATOUOTLNENUGIUOUOOUAOUGdRGUOSenPURTORUONNNALING UONUEUDUOUUODIGOOOUORAOOUNDGNTOUUAUUNGLOOVOCNBCRNAOONONEUED SPUOUANAELAGE) UOUUOUUAEOOIOGAEIOCLUTODUDOUOUUDEU*HINUOUUOUDEGETOGDUODOUDCUACTEVIUUIQUANTORUOUOTAONTNCID: CITI arm Lands. Send today for complete information—without obligation. M. E. THORNTON, Supt. of Colonization CANADIAN PACIFIC RAILWAY 965 First Street E., Calgary, Alberta Wie~™ | CANADIAN % BUREAU OF — FIC CANADIAN INFORMATION The Canadian Pacific Railway will furnish you with the latest informa- tion onevery phaseof Canadian Life. No charge or obligation attached to this service. You are invited to make use of it. Write or call at the Bureau of Canadian Information at 165 E. Ontario St., Chicago 1270 Broadway, New York, or 335 Windsor Station, Montreal, P.Q. Titan Min PITTI ITT ITT ITIL EE BPM Spi + ee Copy this Sketc and let me see what you can do with it. Many newspaper artists earning $30.00 to $125.00 or more per week were trained by my course of per- sonal individual lessons by mail. PICTURE CHARTS make original drawing ersy to learn. Send sketch of Uncle Sam with 6c in stamps for sample Picture Chart, list of successful students, examples of their work and cvicence o' what YOU cen accomplish. Please state your age. of Illustrating & Cartooning TheLandon School 3, ; Schofield Bidg. Cleveland, 0. USE HB MOTORS pavers DELIVERY Sturdy Ball Bearing Electric Motors \ —Ample capacity, smooth-running and eco- nomical. equire little or no attention to operate. Under absolute moev-back varantee you run no tisk. One to 10 fp. Choose the size you need. Cash or easy payments. We plan your in stallation, Simply state machinery you wish to operate, current avilable, etc. Ack for information on battery chargers, lighting sets and Acne Write fr wire today for information. HGOsART BROTHERS CoO., Box S-15, Troy, Ohio “STAMMERING | |fs Guse and Gire * You can be quickly cured. Send 10 cents for 288 page cloth bound book on Stammering and Stuttering. It tells how I cured myself after Stammering and Stut- tering for 20 years. N. BOGU 674 Bogue Building Indianapolis, Indiana Popular Science M, ithly Maximum Mileage from Minimum Gasoline ROBABLY the largest waste of gasoline in this country is due to the habit of letting the engine run idle. There are two other items that should receive consideration when attempting to secure fuel economy. They are the carburetor and ignition. The automobile engine of today operates on a mixture which ranges from 8 parts of air and 1 of gasoline to 14 parts of air and 1 of gasoline. The latter mixture, which is called a “lean” mixture, will give the better results. Despite this, many drivers use a mixture which is nearer the 8 parts of air and 1 of gasoline. This is known as a “rich” mixture and has a tendency to make the cylinders car- bonize rapidly. A rich mixture also makes the en- gine sluggish and prevents the quick getaway that is desirable when driving in city traffic. The richness of the mixture depends on the adjustment of the carburetor, and the man who wants to be sure of the best results should have the job done at the service station. Even when the carburetor question has been answered, the automobile owner does not want to rest his case, for a perfect carburetor alone will not answer the gasoline-wastage question. The ignition must be in perfect order. Cable connections at all points must be kept clean and tight. Without a large, hot spark the mixture in the cylinders is not com- pletely burned. While these adjustments will go a long way in securing maximum mile- age from minimum gasoline, there are many other details that should receive consideration. The fuel tank and the pipe leading from it to the carburetor may leak, and such a leak is a tremendous wasier of gasoline. This kind of a leak is diff. cult to locate. The man who kewps g check on his gas and his mileage is safe Even if the owner keeps such a check it is wise to go over the whole fy¢l system occasionally. The filters and screens in the {ye system should be cleaned at stated intervals. One will be surprised to notice the increased power that results after the fuel pipe has keen cleaned out. Every waste of power is a waste of gasoline. ° The muffler on the modern auiomo- bile is designed to give little back pressure, so no- cut-out is provided. The exhaust carries out a large amount of unburned carbon and unless the muffler is cleaned at times this un- burned carbon- will retard the ex- haust gases and thus rob the engine of power. Carbon in the cylinders is another cause of gasoline wasting. Scraping the cylinders will relieve this. If the valves do not seat properly, they will allow the fuel mixture to leak out. If the clutch slips, there is not only an enormous waste of power, but the wear and tear on the engine. Misalined wheels, as every motorist knows, wear tires rapidly. They also result in a loss of power. Another way to increase the gasoline bill is to have your brakes drag. With the modern brake and its ease of adjustment there is no excuse for this. The driver should let the automobile coast whenever possible, shutting off the ignition and pushing the gas-lever back as far as it will go. With the price of gasoline what it is to-day, use kerosene for washing metal parts and other work around the garage. How to Waterproof Blueprints and Drawings RCHiTECTS, engineers, contract- ors, linemen, etc., often have occasion to refer to drawings, blue- prints, etce., in all kinds of weather, and usually find that before long their prints are in a very dilapidated condi- tion. A simple way of overcoming this trouble is to render them waterproof by saturating them with melted paraf- fin wax such as is used for sealing fruit- jars. If the prints are placed directly into a pan filled with this molten wax, they will soak up too much of it and will always feel more or less greasy to the touch. The most convenient way, therefore, is to soak a number of pieces of absorbent cotton cloth a foot or more square, in the wax. When these pieces of cloth are cool, lay as many as are required (depending on the size 96 of the blueprint) on a table or other smooth surface, place the print on top of these, and then on top of the print lay more of the cloths until it is entirely covered. After this is done, it is only necessary to run a hot iron over them for a few moments. The print will immediately absorb the paraffin until the surface becomes sat- urated. If the table on which the work is carried out has a highly finished sur- face, a layer or two of heavy wrap- ping-paper should be placed between the cloths and the table. Should one of the family irons be used in the process, it would be a good plan to interpose a piece of wrapping: paper between the iron and the cloth also, as it will prevent the _ iron from being fouled with the wax.— F. A. MCLEAN. Popular Science Mont! j Janu t ¢ t

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ithly Jonuary, 1921 AH IAVAM mo- yack ded, unt the un- eX- gine ther ping the ‘ 2 BES tg ORNs - only . = a fo the aliAme ca i be C S eee v| ‘| ; rist ' - also way ei you never its 6 a ‘Four years ago you and | worked at the same bench. We were do¢/ discon- aa tented. Remember the noon we saw the International Correspondence Schools’ “of advertisement? That woke me up. I realized that to get ahead I needed special ps training, and I decided to let the I.C. S. help me. When I marked the coupon ay I asked you to sign with me. You said, ‘Aw, forget it!’ eta the “TI made the most of my opportunity and have been climbing ever since. You had the same chance I had, but you turned it down. No, Jim, you can’t expect more money until you’ve trained your- CiaTeRiaTiONNL, GOMRESPORDEACE” SCHOOLS self to handle bigger work.” ORAL CORRESPONDENCE GE SCHOOL th may ion seg wnt Ring fh gual ‘tor the post ther | ELEOTRIOAL ENGINEER SALESMANSHIP top some Wining and Railways AD VER TING rint There are lots of “Jims” in the world—in stores, fac- I Telephone Work Sign Painter P is : MEOHANIOAL ENGINEER Railroad Trainman tories, offices, everywhere. Are you one of them? Wake | (Mechine Shop Practice ieee one, i Toolmaker BUSINESS MANAGEMEN®? iron up! Every time you see an I. C. S. coupon your chance | civ fhamenes L Frivete Secretary Th Fe 7 ma > ° Surveying and Mapp Stenographer and Typiat oe is staring you in the face. Don’t turn it down. sitnounay sxcinean = ara arine ngineer \ ailway .ccountan' sal Right now over one hundred thousand men are pre- | ARCHITECT’ | GOOD ENGLISH k is paring themselves for bigger jobs and better pay through | Concrete Bullder sernnansee ee sur I. C. S. courses. J eetanita sR akirina = PS sCrobmite Ove ina rap- | bonensr "°° SYP [AGRICULTURE ee ne 9 veen You can join them and get in line for promotion, J “™"™ iil aiddtaareaiiins - Mark and mail this coupon, and find out how. Present : ~ rood a imme ing: INTERNATIONAL CORRESPONDENCE SCHOOLS / cy _ __State a Box 7606B Scranton, Pa. U cmatognatans may send ts coup ay 2219 tToO0oF 97

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Build Your Own PHONOGRAPH IT’S EASY WITH OUR HELP A few hours’ interesting work saves many collars—- gives you a fine machine exactly suited to your ideals—better than many machines costing much more. Plays any record. can understand them Listen to this from Charles F. Mancke, Wash.: the two outfits, and am well pleased I built one machine for myself and took an order for one for $175. I now have mine done, and it has a wonderful tone. I would not take $200 for it.” We are the originators of the home building idea. Our customers always succeed because our plans and system are easy and clear. No special skill necessary. Make Big Money Building Phonographs Ask for Our Sure-Fire Plan and Free Blue Print Offer You can make hundreds of dollars easily, Ask us. We tell you how and help you. We have started man others. We can start you. Pleasant, easy work. N.J. Adams, Michigan, says: “Just sold my phonograph which I built from your plans and parts at nearly $100 profit. Only took about a week working evenings to build it. Those who have heard it Say that it is better than phonographs they have seen and heard at $200."’ Become a Home Dealer—Wonderful Plan Our dealers’ proposition on our ready built Phonograph will appeal to you. It’s the best thing yet. No canvassing—no work—no capital needed. It works every time. We give you full yarticulars and show you how to make sure, easy money. emember, we are the old reliable house-originators of the home building and home dealer idea. rite today. Get our proposition. Have a fine phonograph at half price and make money besides. We furnish complete, simple plans and diagrams—anyone motors, tone arms, case material, everything require 1, and full instructions. F.C. Strong, Can- ada savs: “Please send me one of your circulars, ‘How to Build Your Own Phonogra ph,’ as I would like to make one. Mr. Gallie has built one and if he hadn't told me that he had made it himself I would have taken it for a $150 model.” Received Choraleon Phonograph Co., ‘2. Sacer? Fist Get our FREE Blue Print Offer DEALER WANTED FOR OUR Ready Built Phonographs SAVE OVER HALF I te Laid aly }} LF -DONT SLAVE Be a Railway Traffic Inspector—Pleas- ant, healthful work—Position guaranteed. Be out-of-doors—Travel or remain near home. Get into this wonderful new profes- sion with many opportunities for promotion. Earn $110.00 Monthly to Start and advance quickly up to $250 per Month and More All expenses paid. Steady, fascinating work. Any ambitious, average man over 18 years of age can qualify. Three Months’ spare-time, home study prepares you. No books to buy ; no expense except modest fee, which is returned to you if position is not secured. Don't delay. Investigate today. Remem- ber, we guarantee you a position. Send for FREE booklet D-222, giving all details STANDARD BUSINESS TRAINING INSTITUTE BUFFALO, N, Y. “DON'T SHOUT” “T hear you. Ican hear nowas wellasanybody. ‘How?’ Vith THE MORLEY PHONE. I'vea pair in my ears now, but they are invisible. I would not know I had themin, myself, only that I hear all right."’ The Morley Phone for the DEAF is to the ears what glasses are to the eyes. invisible, comfortable, weightless and harmless. Anyone can adjust it Over one hundred thousand sold. Write for booklet and testimonials. THE MORLEY CO., Dept. 797, 26 South 15th Street, Philadelphia. Learn Music At Home! Easy Lessons Free! Piano, Organ, Violin, y Saxophone, Flute, ‘ Clarinet, Ukulele, Trombone, Cornet, Gui- tar, Banjo, Mandolin, Harp, ‘Cello, Sight Singing. No longer need the ability to Fas be shut out of your life. ust write us a postal today or our new Free Book, fresh from the printer. Let us tell you how you can easily, quickly, thoroughly learn to lay your favorite musical instrument by note in your own home, without a teach- er, by our New Improved ” Home Study Method, without paying a cent for lessons! Different, easier than private teacher way—no tiresome, dry exercises—no inconvenience. No trick music, no “‘numbers,”’ yet simple, wonderful, amazingly easy for even a mere child. 250,000 Pupils! We have successfully taught over 250,000 people. from seven to seventy, in all parts of the world! Hundreds write— “Have learned more in one term in my home with your weekly Jessons than in three terms with private teachers.” “Everything is so thorough and complete,”’ ‘‘The lessons are marvels of simplicity. My 11-year old boy has not had the least trouble to learn.” Wonderful New Book Free! We want to have one pupil tn each locality at once to help advertise our wonder- ful easy system of teaching music. For a limited time, we therefore offer our marvelous lessons free. Only charge is for postage and sheet music which averages just a few cents weekly. Beginners or advanced pupils. We have hundreds of pupils right here in New York, the musical centre of Amerioa, who prefer our liome Study method in place of best private teacher. Get all the proof, facts, letters from pupils, amazing free offer and fascinating New Book just issued, all Sree! Write postal today. Address U. S. School of Music, 81 Brunswick Building, New York | BECOME A Dy Study At Home. Legally trained men win \ high positions and big success in business \\ and publiclife. Greater opportunities now \than ever. Bealeader. Lawyers earn \ $3,000 to $10,000 Annually \ We guide you step bystep. You can | train at home during spare time. We prepare } you for bar examination in any state. Money } refunded according to our Guarantee Bond if | dissatisfied. Degree of LL. B. conferred. / Thousands of successful students enrolled. } 20-page ‘“Law Guide’ . / books free. Send for them—NOW. LaSALLE EXTENSION UNIVERSITY Dept. 183-L Chicago, Ill, Popular Science Mont! How to Fashion a Wrenc! from Steel Tubing DDS and ends of steel pipe or co! - drawn tubing are good mater || for wrenches, the making of whi does not present great difficulti Take a piece of steel pipe or tubi: ¢ and split it at one end for a distance >f a few inches. Hammer the split pi -- tion out flat as shown in the pic- ture, and then cut out a slot which will fit the particular kind of nut for which you wish to use the wrench. You can easi- ly make for your shop or garage ai number of such wrenches fitting a variety ofnuts. Thecostisinsignificant and the making of the wrenches requires litt!e time, labor, and skill.—J. H. Moore. Discarded ends of tubing can be made into useful wrenches Making a Hacksaw Frame at Home T happened on Monday, July fifth, a holiday in celebration of July Fourth, which fell on Sunday. The previous Saturday we purchased six new hacksaw blades to be fully pre- pared for cutting all the conduits necessary, as we intended to spend our holiday installing the conduits for the wiring of our house. Then, accidentally, we broke our hacksaw frame. We tried to borrow one from our neighbors, but no one seemed to have one, so we decided to make one. Out of some spare 14-in. gaspipe fittings we took three 90° ells, one tee, a 1/15-in. length of pipe, and two 3-in. 2 BLADE- FILE-WAND - Ve” This shows how a serviceable hacksaw frame was made from odd bits of pipe nipples, the latter three pieces threaded on both ends with right-hand threads A 5-in. piece of 5/16-in. round iro rod was pipe-threaded on both ends one end to a depth of 14 in. and the other end for about 214 in. This rod we cut into two pieces, one piece 1 in long having the 1!4 in. of thread, th: other 4 in. long and having the 2} in of thread. The unthreaded ends wer: slotted to a depth of 14 in. and hole drilled with a No. 20 drill, perpendicu- lar to the slot. The l-in. piece wa threaded into the ell, the blade in- serted in the slot, and a cotter-pil through the hole and blade, to hold it _ in place. The threads of the tee on the Popular Science Monthi,, Jonua Oo} posi’ in. ent biade eotter- il pla Ad tne ot handle the 4- Ho ah: ls: Case- st raig pé yun crack Tk case- — Gite f ss c ‘“*h ne inj m tri mf «= naan a Oa Oe Ja l

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Se Jonuary, 1921 opposite end were filed out and the 4- in end was inserted in the tee, the biide fitting in the slot, and another cotter-pin was used to hold that end in place. A 5 16-in. nut was then screwed on the other end and a large wooden file handle, drilled out, was threaded on the 4-in. piece. —T. P. FoorTe. How to Straighten Metal that Is Warped “T‘HROUGH uneven heating and cooling, metal is often warped. Case-hardened pieces cannot be straightened either by pressure or pounding, as this treatment results in cracking the case. The usual treatment of a piece of case-hardened metal is to find the A simple method of straightening metal parts that have become warped in case-hardening “high” or “bowed” part, then mark this area with chalk. Heat slightly; never ared heat. The amount of heat- ing, depending on how strongly the metal is warped, is determined by trial. Clamp in a vise between blocks as in sketch. Direct a stream of cold water over the warped area. This will contract the expanded side and the steel will become straight. A ‘‘Finder’’ for Workmen Out of the Shop MONG various devices that have been used for the purpose of avoiding loss of time in finding work- men who may have gone out on an- other job, the one here illustrated has several advantages. It is conspicuous; it is so easy to operate that there is no excuse for neglecting to keep it prop- erly set, and it has the feature of being adaptable for the use of two or more different persons, without being con- fusing in its indications. On a dial that may be hung onthe door of the shop, are marked the names or numbers of various places to which the workmen are likely to be called, and an arrow for each of the January, 1921 Here are the world’s great- est Electrical Books. can have them for a weeks’ Free use in your home or shop. Eight pig books, 4000 pages of money- making facts. More than 3000 pic- Electrical Books 97 Sent to You For One Week FREE You tures, blue prints and diagrams that make everything clear as day. Prepared by 28 of the world’s master electrical minds in plain every day English that any one can understand. They teach you electricity from the ground up. They explain everything—from the simple wiring of electric bells to the mighty electric machinery you see in the power houses. would cost to go to an electrical school. tice. Old-time electricians say “they are the finest books they ever saw.” Master These Subjects Principles of Electricity; Telephones; Construction Operation and Repair Dyna- mos andMotors; Storage Batter- ies; Alternating Current Ma- chinery; Switch ee Arma- ture Winding; Construction and Operation of Transf ormer &; Electrical Meas- urements; E |e c- ductionCoils;Con- trollers; Electric Elevators; Rail- way Signaling; Interior and Ex- terior Wiring;Ma- terials and Meth- ods Used; Under- writers’ Require- ments; Electric Lighting: P 1 an- ning Systems; Es- timating, Con- tracts; Specifica- tions; M aint en- ance; Electro- chemistry; Power Stations; Opera- tion and Mainten- ance; Manage- ment of Dynamos and Motors; Elec- tric Welding ;Elec- tric Transmission Lines; Distribu- ting Systems; ElectricRail ways; Construction of | Power Plants; New Electrical Devices. They save you the money it They save you years of hard work as an appren- See our free trial—easy payment offer below. Get in the Big Money Class Electricians Earn $60 to $100 a Week The electrical field is seriously under-manned. Thousands of men who know what's what are needed right now to fill important jobs such as Sub-Station Operators, Switch-board Operators, Dynamo and Motor Tenders, Installation Experts, Trouble Men and Engineers. The work is fascinating and the pay is big. YourFuturels in Electricity Electricity is the greatest force in the world and it is growing greater every day. The whole world depends onthe electrician. Think what opportunities this offers to the fellow with a little ambition. You can succeed in electricity. Youcan have a big job and the big pay that goes with it. These books will show you the way. Don’t Send Money Prove to yourself how easy it is to master electricity by getting these books for a weeks’ free use. Just mail the coupon and the whole set will come to you at once. If you don’t like them—if you don’t think they will do for you what we claim—send them back at our expense and you won’t oweus acent. If you are satisfied with the books in every way just send us $2.80 as first payment and $3.00 each month, until $34.80 is paid. This is only adimeaday. Most of us waste more than this. Mail the coupon now and get a membership in this ee ee eae “| Society, Free, AMERICAN TECHNICAL SOCIETY 1 Dept. E-201, Chicago i e ‘ I Please send me a set of Practical Applied Electricity i al oupon a in8 volumes by express collect, for a week’s free ff I use. At the end of a week I will either send the § books back at your expense or send you $2.80 as or ese ] first paymont and $3.00 each month thereafter until | a total of 834.80 is paid. I understand that I will get § e a Cy ~~ Egan in your Society, FREE : with the books, Big Books

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Better than a mustard plaster Once when grandma’s joints commenced to ache and twinge, she used to os to the mustard pot and makea mustard plaster. Now she goes to Musterole and gets relief, but does without the blister and the plaster, too! My, how good that Musterole feels when you rub it in gently over that lame back and those sore muscles. First you feel the entle tingle, then the de- ghtful, soothing coolness that reaches in the twing- ing joints or stiff, sore muscles, It penetrates to the heart of the congestion. This is because it is made of oil of Mustard and other home simples. And the heat gen- erated by Musterole will not blister, On the contrary the peculiarity of Musterole lies in the fact that shortly it gives you such a cool, relieved feeling all about the twingey part. And Musterole usually brings the relief while you are rubbing iton. Always keep a jar handy. Many doctors and nurses recommend Musterole. 35c. and 65c. jars—$3.00 hospital size. The Musterole Co., Cleveland, Ohio BETTER THAN A MUSTARD PLASTER MADE FOR + U.S. GOVERNMENT "12 FULL LENGTH HIP ROOTS GUARANTEED FIRST QUALITY These $12.00 U. S. Army Hip Rubber Boots were left by cancellation of government orders. Every boot is new and bears official stamp of the U.S. Gov't Inspector. Send now before itis too late: Why not save money by ordering 2 or 3 pairs? NOW ONLY $5.50 a pair. Pay on arrival. You risk nothing. If you are not 2 = A SEND NO MONEY perfectly satisfied, we will return your money at once, Knee Rubber Boots $4.75 Rubber Boot Socks, 45c Show this wonderful Offer to your friends. Vrite, or mail coupon, as you prefer. EAST HOUSE 64 Armory Bldg., East Boston, Mass. Send U. 8S. Gov’t. Hip Rubber Boots, C. 0, D, My money back if not satisfied, Name.. Addres Wind on She 0006000460854 00 ssan teens Cee ee eee eee ersereesesese eeeeesessse SIMPLE WIRELESS TELEPHONES AND HOW TO MAKE THEM. An elemental book on the principles, con- struction and use of an arc system of dsr telephony Illustrated Price, postpaid, 25 cents POPULAR SCIENCE MONTHLY 225 West 39th Street New York men is balanced on a pivot-bolt at the center. The bolt should be set up fairly tight, and a thick washer should be under each arrow, to give clearance. When set as in the sketch, the dial in- dicates that Mr. Jones is to be found in the superintendent’s office, while — IN EMERGENCY — FIND ELECTRICIAN — WHERE ARROW POINTS — Each man is represented on the dial by an arrow that indicates where he is Mr. Smith is at work in the mechanical laboratory. If made in “‘idle time,’’ such a device costs almost nothing, and may save enormous loss at times of accident or other emergency.—CuRTIS RALSTON. Typewriter Attachment for ‘‘Sub”’ Figures HE accompanying _ illustration shows the simple construction of a device which was fitted to a chemist’s typewriter, and which saved him much time and trouble. In chemical writing, and also in various other classes of work, it is necessary frequently to write figures slightly below the line, as in H,SO,. On nearly all typewriters it is possible to install some such key as the one SPECIAL SUB-KEY yy SOLDER 2 axe — BRASS CLAMP CAS: CFP 7 REGULAR SHIFT-KEY SPRING & OTHER KEYS AND STEM, 7 fi = ae ——— THREADED |= SLEEVE = === TYPEWRITER BASE == Figures in proper position for chemical formulas are written by merely de- pressing an extra shift-key here illustrated, which elevates the carriage just the proper distance to write these figures. The construction, which would have to be modified slightly in proportion and position of parts to fit it to other makes of machines, is quickly seen in the sketch. A special key is fitted to the top of a stem that works up and down in a little sheet-brass clamp, which is tightly attached to the regular shift-key. The lower end of the stem is threaded, and a _ short 100 : Jor comfort j |A useful holiday sift} _ MADE AT SHIRLEY MASSACHUSETTS § CARPENTERS, Shipfitters, Bricklayers, Structural, Concrete and Sheet Metal Workers, Electricians, Mechanics, Plumb- ers, Pipefitters, Boilermakers and others can earn more money if they know how to read Blue Prints. By our simple method, we train youin ashorttime. Writefor Catalog B,stating trade. BE A DRAFTSMAN Earn $35-$150 Week Draftsmen are in demand. Books and tools FREE. Writefor CatalogG. DOIT TODAY! Columbia Correspondence School 19% Carroll Dept. Drexel Bidg., Phila, Pa. Lowest Typewriter prices Guaranteed, fully inspected, strongly rebuilt, 1 @5.00 di 4 _— pone pn S ‘months to pay balance. Send us your ad at once details of the Most Startling Offer { in typewriter val ‘ i S DAYS coostenity to occure pone tattns ate anine TRIAL ‘wregeaeit, rrpewnrgn excuanor Ukulele, Hawaiian Guitar, Violin, TENOR BANJ Mandolin, Guitar, Cornet or Banjo Wonderful new system of teaching note music by mail, To first pupils in each locality, we give a $20 superb Violin, Mandolin, Ukulele, Guitar, Hawaiin Guitar, Cornet, Tenor Banjo or Banjo abso- lutely free. Very small charge for lessons only. We guarantee suc- cess or no charge. Complete outfit free, Write now. No obligation. SLINGERLAND SCHOOL OF MUSIC, inc. Dept. 603 CHICAGO, ILL. Cleartone Phonographs $4.00 to $200.00 Retail Our Sundry Dept. offers Needles 39c per thousand. Motors $1.35 te $14.75 each. Tone-Arms and Re- producers $1.30 to $5.75 per set. Main springs 2V0c to 90c each Records, Needles, Sapphire Points and Parts at reasonable prices. : Write for our 84-page catalogue, the only one of its kind in America, illustrating 33 different styles of Talking Machines and over 500 different Phono graphic Parts. LUCKY 13 PHONOGRAPH COMPANY Export Dept. 503G, East 19th Street, New York Elements of Industrial Chemistry By ALLEN RoGeErs, Contents: General Proc- esses; Water, Its Uses and Purification; Fuels; Sulphuric Acid: Nitric Acid; Elements and In- organic Compounds; Ceramic Materials and Products; Pigments; Fertilizers; Uluminating Gas; Coal Tar and Its Distillation Products; The Petroleum Industry; The Destructive Dis- tillation of Wood; Oils, Fats and Waxes; Lubri- cating Oils; Soap, Soap Powder and Glycerine; Essential Oils; Resins, Oleo-Resins, Gum-Resins and Gums; Varnish; Sugar; Starch, Glucose, Dextrin and Gluten; Beer, Wine and Liquor; Textiles; Dyestuffs and Their Applications; The Paper Industry; Explosives; Leather. About 600 pages, illustrations. Price, $3 .00, Postpaid. BOOK DEPT. POPULAR SCIENCE MONTHLY 225 West 39th Street, New York City of the: is pres pre sse depres the sl Thi ol ali than positi form Usi W amot reves far t remc rise | W othe the | —_~ eww TH of & co co

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ealled, and an arrow for each of the | Sr rR Ph January, 1921 sle ve is tapped to fit the stem thread. This sleeve is, for purposes of quiet- es, best made of fiber or hard rubber, th ugh brass tubing will serve the pur- po-e. Between the sleeve and the clamp, around the stem, is a coil- spring of the open or compression type. rhe action of the device will be clear at once: The shift-key can be operated as usual, owing to the compressibility of the coil-spring. When the “‘sub”’ key is pressed, the shift-key is thereby de- pressed only slightly, the amount of such depression being regulated by turning the sleeve on the sub key stem. Chis throws the index numerals out of alinement and brings them more than halfway below the line, in the position which they take in chemical formulas. Using the Fan Support as a Breather-Pipe- \ 7E recently encountered an engine ' that failed to develop the proper amount of power, and an examination revealed that the breather-pipe 92 far too small in size, for when it was removed from the crankcase, a distinct rise in power was noticed. We were about to provide for an- other breather on the opposite side of the case, when a thoughtful workman, : SCREEN ' vt 3 CAP H tam FAN Z ie Z 1! tyra 3 ‘eee © 3 ’ a2 oe s. we ! 9 2 era% ‘ae oN B Ney oo 0 B an tees vet + gal? 1 BRACKET 1 ye AND ' \\\ barrrereerneennnrnnnntins WAAER vate) TIMING GEARS By drilling a hole through the steel post supporting the fan, it be- came a breather-pipe and oil-vent who was overhauling the fan assembly of this same engine, noticed that the supporting post was made of a solid bar of rolled steel. It occurred to him that a hole pored clear through this post, and provided with a sereen and nut at the top, would vive additional air connection to the inside of the crankcase, and, further, that it would afford an excellent filling- cap for pouring oil into the front com- partment of the case that housed the timing gears. The illustration shows the manner in which the idea was carried out. It proved eminently suc- cessful and worthy of adoption in any similar case, provided the conditions make it feasible-—ADOLPH KLEIN. 99 Learn Automobile Tractorand Flying Business HENRY J. RAHE Founder and President I HAVE invested 14 years of my life and over 2 riillion dollars in building up my school, until now it is the greatest and most roficient Automotive raining School in ex- istence. C into a steady, big-paying business. self sure of a steady, big income. OME to the Rahe School—the world’s oldest and greatest Automotive School—and get Make your- The 9 million Automobiles, Trucks and Tractors now in use have got to be kept up and running. Thous- ands more of Rahe Trained men are needed for that right now in every section of the country. Prepare yourself here in 6 to 8 weeks, and take your pick out of thousands of high-pay positions now waiting for you. Oropen your own business in one of the 50,000 —— places now calling for new shops and sales agencies, ~ Jeahe School $2,000 Net Proft. About three years ago I took up the training at the Rahe School and have been running a garage ever since. I doall kinds of automobile work. My business nets me over $2,000 a year.—Emerson Shutt, Mediap- olis, Iowa. Making $8 a Day. Iam making $8.00 a day here, and I give the Rahe School cred- it for my ability to hold this job. —Vernon D. Larabee, Lansing, Mich. (1408 N. Larch.) Age 20—Earns $5,000 Iam 20 years old and have had training at the RaheSchool. I own and operate my own gar- age. I do all kinds of work and my business is paying me around $5,000 a year.—Ernest Christensen, Waynesville, Mo. Makes $75 a Week. Iam owner and manager of a repairshop here. I took train- ing at the Rahe School a year ago. I do all kinds of repair work on automobiles and my business pays me around $75 a week.—D.D. Cates, Burlington, N. C. (Route 3) Income $40 a Week. My wages were very small before taking up Rahe Train- ing, but now I have my own shop and a steady income of about $40 a week,—C. C, Cady, Parker, Kansas. 2 Million Dollars Invested AUTO—TRACTOR— AIRPLANE 14th Year—38,000 Graduates As a Rahe Trained man, you always have the advantage over all other men not trained here. Over 38,000 men already Rahe Trained are better trained men. They know the best and quickest way to learn is through my school. I always have more calls for men than I have students. The thousands of Rahe Trained men now in business for themselves in every State are always sending to me for more Rahe Trained men than I can furnish. By coming here, you get preferred oppor- tunity for a good job, or for a business of your own immediately upon leaving the school. Four (4) big buildings (equal to 20-story skyscraper) ; big tractor farm and big flying field. Complete and thorough training in every branch of the business. Plenty of op- portunity to earn part living expenses while in“school. Low-Pric¢d Life Scholarship Now. Before you ar- —— — Free Catalog P73" * = any school, visit this School. If you can’t } come now, do the next best thing—send ‘ Phe | for my 84-page free catalog. The coupon | fi below will do. Catalog shows fully by I] Scho, / photographs how you learn best here— | ul 0, how you are sure of the best opportunities | | I Om iy, le after you receive your Rahe Training. salting / | 54 HENRY J. RAHE PACES ») +7 / Dept. 2889 Kansas City, Mo. /. ‘T@@ Book ea 101 Mail This Coupon for special tuition i] offer and big.84-page ent catalog giving proof of graduates’ success and show- i ng the many opportunities now open, All sent FREE. Niantic da elllansissdiceinsinilinebslsindicinsandvabii A ESET are ee a a a Occupation

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oevr WwwewLET ouorses qwevww~e s~eww wea * wl . ee OO OSS eee 100

Popular Science Moni'ly Januar Holding Thin Pieces for Hang Pictures on Need|. ae ee Lathe Machining Points. achens By a simple twist of the wrist, place Pictu Charts or Drawings, on any surface w be GC a Moore Push-Pins} — “',° m: Glass Heads—Steel Points versed UCH difficulty is usually ex- perienced in holding thin pieces to be machined in the lathe, shaper, miller, ete.

Harmonize with any color scheme; can be By using beeswax a firm, even con- used over and over. For heavy Pictures, cal sed

as a e a . . Mirrors, Hanging Bookshelves, etc., use it , e Like a damaged product tact results. Pieces as thin as 1/16 in. meekt POOLING GANG Bee tan, «| while of the factory? fat: is 8 y ° heavy cut to be made. Heavier pieces See evecr*teee by, Hardware, ] Be or ve the di can be held firmly enough fora fairly “The hanger with the twist.’ Samples Free. Look in the glass. See if what you see there is a can be held without the aid of clamps and Department Stores.

full. fledged fd 1 goods—a . : if reject of society—nerves gone, Vitality sapped, energy which would in- MOORE PUSH-PIN CO., Phe ack ea t et—4 reakenec tremblin nope- . ™ . ae, teeny Manetel. oi ing feels that lite is “9 worth STOCKY? FHICK terfere with the 11-1 Berkley Street, Philadelphia, Pa. ¥ living, and the world looks dark and gloomy. CLAMPED TO ° —) The guilty man shudders at the spectacle he sees CE PLATE machine-work. in the meres hig: mya ape ~— ng face te. — FA\ The beeswax vith yourself what has made you what you are, if you =e of the guilty ones. a0 a — is melted and BIG PROFITS IN VULCANIZING | a Don’t be a Half-Baked Misfit WORK : : _ a f were ae mith adoro SeeR tostat t 4 b an— “holes “ . a Ost My Be nth g ae ae se 8 io son ou SLIDE REST to either the aoe Better tire ork ployer would be glad to have around—a man every f l f Dair rs at ——— e workeé f ae man and woman will acep ate 0 ae. a a g proti's. a instinctively take to th l h daumnuatioter Vase. asks right off. You can Beeswax applied to the e athe or also the operation of the Anuer: : st do it—if you will ; bl f h son Super-heated Vulcani:+r illus ] listen to a little com- table of the machine ta e ol the fom te byhd up a cncecasia copie tauzht by. aman who f | Cuts thin metal easily shaper or miller. as ere with sets made himself the B h b There are Anderson schools sired, best physical speci ut the best tee cchcoling hes ‘cotpmnint most | then devoted himse't method is to have a piece of parallel gists distinctive. but i to the rehabilitation f.| stock about 14 in. thick to which the iy i won? hae °ekow | | Wax is applied and which i is ony tasers tuk pont a to he ceeded that _— wax 1s app 1e an WwW 1¢ In turn 1S and ven gh tmnt hh expense s , mle m ol elo ny the cunaee clamped to the faceplate or table of er daye served because we: sell'tre Pen Se the machine. After the wax cools, the ANDERSON STEAM VULCANIZER co. ° ° ° ° lis, Strongfortism piece to be machined is heated slightly eomsecnoth a manger, Set, U. S. A. Will Put You and pressed firmly on the wax-covered — On Your Feet surface, being held under pressure for | x woes inf | 4 minute or two until the wax hard- @} Be AES 5] ‘ 1 A SINS BNO Oneee IR cusses Lo aoe oP = ens.—S. B. ROYAL. Either pin illustrated sale with a ee Ce enmend Pisa strap which, by means of the bolt Dollars in Hares Here mention other subjects not listed above....... shown, holds the parallel C on the sur- We pay $7.00to$18.50 and upa pair “+ eecnneane ees ty ar | | face, 7, which is being tested with the | Jadexoresscharses. Big Brofte NE Tbi oc ncance eae tar och cep aden cules cee surface E. stock and buy all you raise. Use a ae = . ° > backyard, barn, cellar. attic. Con- Age... Fig cig won a ORI ss ss ke ns cheakooabon 7 he readin on the dial 1s first tract and © pate ast Catalog Free g Free. S Perri vrrrrrerire riot rTiritrrie Tre CP eee. 4 M ; 7 a : ' taken, and the indicator B is moved STANDARD FOOD AND FUR ASS’N City. . . pe 5 6 ccd an oesée 407C Broadway New York

to the other end of the parallel C and

102

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eaewsaw S2Y SW eens ewe eeaw wocee 62° Oeaeaewo vl oS - 101

itily January, 1921 i? read to see if it is the same as at the other end. _ was found that this overhanging bar C made the dial register a vibra- 1s | tion of 83-1000 in. every time a heavy machine, running 20 ft. away, re- versed. A truck going by the factory caused a registration of 2-1000 in., . while a locomotive and freight-cars registered 5-1000-in. vibration on the dial— RALPH A. WRIGHT.

Calls Coming in Steadily for National Radio Institute Graduates. Big Concerns in Need of Operators Photographing Books with the Movie Camera : i> modern public library has _ adopted the camera and the pho- tostat as mutual aids fo the research > the worker and patent attorney. One

Many attractive positions are now open in Merchant Marine, Commercial Land Radio Service, Radio Supply Factories, U. S. Navy, Aerial Mail, and large Business Corporations SALARIES UP TO $3,500 A YEAR Exceptional opportunity for ambitious men for promotion to the higher branches of Radio. Our graduates are qualified as Senior Operators, and besides Room and Board, receive $125 a month to start, which altogether means more than $200. Positions to which they can promote themselves are as follows: Supercargo and Wireless Operator—$175 a month; Radio

An: asks for a book, picks outa chapter or Mechanic—$1,500 to $2.000 a year; Radio Aid—$6.00 to $8.00 per day; ene os ° e Radio Inspector—$1,500 to $3,000 a year; Radio Engineer—-$6,000 and illustration, and has_ photographic more a year; Radio Draftsman—$7.00 to $10.00 a day. You can learn ind e E wireless the National Radio Institute way, quic kly and easily, by mail right vith copies made of aS Many pages as de- in your own home, in your spare time. No previous experience or training is ; ° ° e necessary. With our help you can quickly qualify for first grade govern- is sired, for a nominal fee. The service in ment license and a fine position. U. S. DEPARTMENT OF COMMERCE RECOGNIZES N. R. I. and allows its graduates 5 to 10 points credit when taking the examination for First Grade Government License. This school heads the printed list of reputable Wireless Schools recommended by the U. S. Shipping Board. TRAVEL WITHOUT EXPENSE If you are eager to travel, anxious to visit foreign countries, and increase your knowledge of world affairs, Wireless offers the chance of a life time. On shipboard you are rated as an officer. You need not travel unless you wish, but may secure a position at one of the many ever increasing land radio offices. NEW AUTOMATIC WIRELESS INSTRUMENT FREE In addition to all necessary text books and other equipment with which we supply you, we furnish FREE to every student our marvelous new automatic Natrometer, which transmits Wireless messages in 600 different combinations aud can be regulated to operate at any speed from 1 to 30 words a minute. It is complete with phones. etc., and is sent you in a neat carrying case. This instrument is operated entirely without the use of aerials and is used exclusively by the Nationa! Radio Institute to teach Wireless at home in the scientific way. : most cases is accurate and quick—— 0 but it will soon have to be even faster it to hold its own, if the public takes to

ci.

r\9 You receive the instrument after your enrollment; it becomes your personal property upon completion of our course 4 SEND FOR FREE BOOK Write to-day for FREE BOOK “Wireless the Opportunity of To-Day,” containing interesting and valuable info: mation. NATIONAL RADIO INSTITUTE 7 Dept. 426 Washington, D. Cc. J LAV J BECOME AN LL.B. h bnew ee caly law sohest - the U.S. which cmatested | i i i i a standard resident school and gives its students identically Copying Pictures and print w ul the same instruction by mail. We are legally qualified and moving-picture camera saves time authorized to confer the Degree of Bachelor of Laws — cmeenentto LL. B.—by correspondence. Over 450 lectures delivered in _ ight in your own Coens, by mail, classrooms and especially revised for our students by a large from the ‘greatest wrestlers the world has — corps of prominent, practicing lawyers. Our Law Library ever known. Bean athlete, be strong, be healthy. consists of 24 volumes ‘bound into 12 books) of Students’ arn how to throw and handle big men with ease. Learn

using the small moving-picture camera in copying out-of-print books, ete. It is possible to use these photo- graphs whether reduced or enlarged. The latest edition of a noted encyclo- pedia was photographically reproduced page by page and a facsimile edition printed and sold by thousands. So many important patents are “‘out of print’? when sent for, that the official delay of ‘twelve weeks” is a very serious matter, and manual copying is expensive. What is to be done? Why not use a moving-picture camera? It is easy to arrange such a camera so that, witha crank motion such as we see in many adding-machines, one single film unit will pass the lens every time the crank is turned. Here is the way the camera is worked: The light of a ‘‘semi-lamp”’ or a mercury arc is focussed on the book, document, or manuscript and the pages are turned by hand or by special large clips, sc that the hand will not show in the picture. After some practice, this operation can be done at the rate of about one exposure a second. If we depend upon che one exposure a second, we shall be safe, as at that rate we get sixty Standard Text Books, prepared at an enormous cost exclu- sively for the use of our students by one of the largest and most reliable law book publishers in America. Written ae antee to prepare graduates to pass bar examination. course in Oratory and PublicSpeaking given free. Thousands of successful graduates. Only school of its kind in America. Established in 1910. Write today for Illustrated Catalog which will give you the Facts — the Proof— the Evidence. Hamilton College of Law, 507 Morton Bidg., Chicago

Le: to defend yourself. Learn from the World FarmerBurns andFrankGotch Farmer Burns, who tought frank Gotch— trainee of Govan s Champions, porte es Cha renee | teach you Scient ye om iture— Jiu-Jitsu and Self-Defense. i = ond address on a post-card or letter,

Rudolph Wurlitzer Co ee

| Free Trial you may have any instrument with complete musical b pes for a week’s free trial at home. No obliga- tion. Return it at our expense after tria! if you wich. Outfit includes velvet lined case, self instructor, music andall accessories at factory cost. Atremendous saving. Convenient Monthly Payments

A few cents a day will pay forinstrument and outfit. Wurlitzer instruments are known all over the world for artistic quality Send Coupon for Beautiful New Catalog Every instrument known illustrated with price, easy terms and free trial blank. Catalog absolutely free. Write today. The Rudolph Wurlitzer Co., Dept. 17s1 i 147 E. 4th dt., Cincinnati,O.—329S Wabash Ave. Chicago . Send me your new catalog re in color with rali de- tails of urliteee Complete Outfits and fr~e trial and easy payment offe: INGO cececccecces sriweutondnseuenseapetaseto. <6 ; i

DEI GED. coccsatcincsscnseserecteescesecseesecesess eco _ (State é tadirumeand's you are « specially interested ‘fa. ry anne nnewe cus:

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= ees Could you hold your own? You probably haven't had a real fight since you were very small. Settling a dispute with your fists is the last thing you'd think of. And yet, a time may come when you will have to fight. Suppose you saw a rowdy in the act of insulting a woman. Could you look the other way? No, sir, you'd want to step right up and teach him the lesson he deserved. But could you? A quarrel might lead to the challenge ‘‘Come outside and fight."" Could you do it and hold your own? Or suppose you were attacked in a deserted street after dark. You'd have to fight! Your very life might depend upon being able to disarm the thug and cripple him with a powerful blow or jiu jitsu hold. Remember, those two fisis of yours are the best weapons if you know how to use them—they're always with you, always ready. Marshall Stillman will teach you boxing and self- defense in your own home. His system is the result of 30 years’ study—he’s an expert -toxer himself, and a pupil of Professor Mike Donovan who retired undefeated middleweight champion of the world. In his course, the fundamentals (hitting, guarding, ducking, feinting, and footwork) are easily learned. because you start by practising simple movements before a mirror—the breast stroke in swimming, holding out your hand for a coin, etc. Subcon- sciously you are led into striking heavy blows, guarding, ducking, feinting, etc., just as though you had a real opponent before you. When you've mastered the fundamentals, you’re taught every good blow in the ring—when to land it, where to land it, and how to guard against your op- ponent’s counter attack. Then comes shadow boxing. Marshall Stillman has com- bined such scientific blows as the Jack Dempsey Triple, the Bennie Leonard Triple, the Mike Donovan Double, etc.. into three lively rounds for daily practice You're also taught 12 wrestling holds and 15 jiu jitsu holds —how to disarm a man with a pistol dagger or club, how to break a strangle hold. etc. The course includes a set of muscle building exercises, The Colon Exercise (a remedy tor constipation) and Synthetic Breathing (a lung developer and aid in curing nervousness). As an added feature. theres an illustrated history of 69 great boxers with “‘inside’’ stories seldom heard outside pro- tessional circles. There are 246 illustrations in the course. Sent Free on Approval The entire course is sent on approval. You keep it 10 days, and then if not satisfied, return it. If you buy it, you have till the 15th of the following month to pay ($5 in the U.S.,$6 in Canada, $7 in foreign countries). Mail the coupon to Marshall Stillman Association, Suite F-201, 461 Fourth Ave., New_York ee ey el | Marshall Stillman Association Suite F-201, 461 Fourth Ave., New York You may send me your complete course in Boxing and Self Defense, including extra instruction described above ive you my pledge that you may feel safe in trusting me as agreed. ont 1 will pay $5 ($6 in Canada; $7 in foreign countries) for the course on the 15th of next month or return it in 10 days after I receive it Name. Address. AN EASY WAY TO MAKE MONEY .2:::: on a small salary. Be independent. Go in oe? ie rm pairing business. One man says ‘‘I made $60.00 the first day.’’ Others average $200 to $500 a month. Very little capital needed. Jobs plentiful. Every motorist a pos: sible customer. No experience needed. We teach you, SHALER ER Tire Repair ant Improved Wrapped Tread Method Used by Tire Manufacturers Does as good wor’s as the big high priced vulcanizing outfits. A boy can use it. It’s the only vulcanizer that has Automatic Heat Control, and can't uadercure or overcure a tire. Requires no watching or regulating. FREE Book “How to Open a Tire Repair Shop.”* It tells how to make hig money. Don’t delay. Write quick. C. A. SHALER CO. 2100 Fourth St. Waupun, Wisconsin ' to the other end of the parailel © and | 102 copies a minute. When we allow for fatigue of the operator, we may take an average of one third of this or twelve hundred pages an hour. One great advantage is that no special apparatus is necessary to ob- tain clear pictures of book pages. A good sky illumination is sufficient in most cases.—‘*‘VAN BRUNT.” A Strong yet Light Ladder from Furring Strips TRONG yet light ladders may be made from furring strips, such as are used in building construction for stay-laths or braces. The writer has 16-0 - — y 1«2° FURRING STRIPS This ladder may be easily made from a few furring strips and a handful of nails made many such ladders and found them very satisfactory. The accompanying illustration clearly illustrates the construction of the ladder. The two bent strips, which are nailed to the uprights and to each rung of the ladder, materially add to the strength and rigidity of the ladder.—W. F. QUACKENBUSH. For Safety First in the Japanning Shop MALL articles of metal which are to be japanned or enameled are usually coated by the dipping method. This method undoubtedly speeds pro- duction, but increases the risk to life and property. Varnishes and enamels are easily inflammable and their use, especially in large quanti- a ties, as required \ \ FUSIBLE LINK in dipping, ' makes neces- SAFETY DIPPING sary special TANK *. precautions against fire and LINK explosion. The accom- Teese eit HHHH panying _illus- tration shows the method Fusing - links adopted in a large metal fac- diminish the tory to dimin- riskoffireand ish the danger explosion of ignition in the dipping de- partment. Mechanical arrangements are provided of such a nature that the heating of the dipping-room to a pre- determined temperature—say, 150° F. -will automatically cause the cover- ing of the dipping-tank and the dis- charge of its contents through a pipe to the outside of the building. When the heat in the room, through some cause, reaches the critical point, are used to 104 Popular Scrence Moni'ily YOU Can Do YOUR Ow;. SOLDERING and All Metal Repairing With IN WAR A PASTE THAT TURNS INTO METAL WHEN HEATED A_ match will doit. Requires no acid or soldering iron Joins or repairs wires, metals or metalware. Sold by hardware and electrical stores or sent by us postpaid. SOLDERALL CO., Dept. A, GOVERNMENTS USED BY U. S. AND ALLIED] 129 SUSSEX AVE., NEWARK, N Cc OMBINA ONS Tube and he =... $1.50 Dealers Send for Quantity Prices Look for Trade rag “‘SOLDERALL."’ Beware of imita- tions with similar names TLEARN PARLIAMENTARY Procedure and Public Speaking Be the Leader. We teach you by mail the rules of Parliamentary Pro- cedure and the duties of the presiding officer in conducting lodge, union or club meetings—all that governs the deliberative or legislative assembly. The Course, prepared by Herman Ames Philips, for 15 years Jour- nal Clerk, National House of Representatives, and John Philpot Curran, LL.B., is based on the rules used in Congress. Low Cost, easy terms. Write for free il- lustrated booklet of pointers for speakers. AMERICAN PHILOMATHIC SOCIETY | _ Bent. 3: 121 —_— * Chicago, mW. — Wireless Telegraph— Transformers With which any amateur can cover great dis- tances. Write today for Bulle- tin on Wireless. Warren, Ohio eS! GET BIG BUSH OFFER We do not deal throug! tors bat County Ag Agents BIG AS a Money- Maki f ing Otter lor four and De Luxe six. Don’t wait. Write today! BUSH MOTOR CO., Chicago, llinois, Dept. ail, Bush Temple oney-Back guar tee. Bush light Build This Phonograph Y ourself TREMENDOUS SAVING IN COST Easy foscipating work, with our SIMPLIFIED PLAN arnish blue prints, diagrams motor, cabinet pieces, ready-built horn, etc You don’t need to bea cabinet-maker. ‘A few hours assembling and you will have a fine in strument at one- omar ter the b “nea cores price, AGENTS MAKE selling these instruments. mene today tor ‘fe a details and our FREE OFFER. Addre MODERN PHONOGRAPH “SUPPLY co. 412 Springer Building 313 So. Clinton St. CH ____ CHICAGO, ILL. | LL. #Agents $85 Weekly Get a Robinson Folding Bath Tu F REE. Big seller. Costs little, 1 plumbing. Weight 15 pounds, folds to small roll. F s Full length baths, ta better than tin tubs. Guaranteed 10 years. $15 ¢t $20 a day easily made. Write quick for special offer ROBINSON CABINET MFG. CO. 13 Factories Bldg. Toledo, O ‘BOWLEGSand KNOCK-KNEES’ iy UNSIGHTLY — fj SEND FOR BOOKLET SHOWING PHOTOS OF MEN WITH AND WITHOUT The Perfect Leg Forms y SSS Yj PERFECT SALES C0. ,140 W.Mayfield Ave., Dept. 45, Chicago, lll. Jonua fi ible are M weigh the ¢ descel the té ts nks throu outsid Ma biles ° water to pl garag With any ¢ the b As panyi in wh is ma or bu they The t Proct over firml This Th lengt lengt large bras mod betw each pass cork leng the tube long they tube FE wat ovel to : fum tubs sho1 sho1 Tania

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safe, as at that rate we get sixty | IN WAR GOVERNMENTS ' Jonuary, 1921 fu-ible links, placed at several points, are melted, thereby releasing counter- weights the dropping of which causes the eovers of the dipping-tanks to descend and the discharge valve under he tank to open. The liquid in the tanks is then rapidly discharged through the drainpipe to the ground outside of the building. Make Your Own Still for Battery Water ITH the greatly increasing use \ of storage batteries in automo- biles the demand for pure or distilled water has increased. It is unnecessary to purchase this water or pay the garage man to put it in the battery. With this simple and inexpensive still any one can distill water for refilling the batteries as the occasion requires. As shown in the illustration accom- panying this article, the boiler or tank in which the water is turned to steam, is made of a quart or half-gallon can or bucket with rolled seams. Be sure they are not soldered at the bottom. The top of the can or bucket is open. Procure a large tin funnel that will fit METAL OR GLASS "i CYLINDER Why pay for distilled water for your storage battery? Make your own still over the top of the can and then solder firmly and tightly in place as shown. This completes the boiler. The condenser consists of three lengths of glass tubing each 12 in. in length. These tubes pass through a larger tube or a piece of iron pipe or brass tube of sufficient size to accom- modate the tubes with some space between them. Fit a large cork into each end of the large pipe or tube and pass the three glass tubes through the corks. Then into each cork fit a short length of glass tube, one at the bottom, the other near the top of the large tube. Connect the free ends of the long tubes with rubber tubing so that they will form one long continuous tube. Fill the boiler half full of clean water by submerging, and place it over a gas flame until the water comes to a boil. Connect the top of the funnel with one free end of the glass tube through the condenser by a short length of rubber tube. Slip a short length of rubber tube over the evw *¢ eae Se es , Copyright 1920 SSS Raat Wurlitzer Co.' 103 (State instrument you are spectally interested tm.) _ What Happens When you brush teeth in this way Five quick effects occur when teeth are brushed in this scientific way. Millions now get them twice a day. Leading dentists everywhere urge all to get them. Ask us for this 10-Day Tube. It will show what these effects mean in whiter, cleaner teeth. The five effects Pepsodent multiplies the salivary flow. That is nature’s tooth-pro- tecting agent. It multiplies the starch digestant in the saliva. That to quickly digest the starch deposits which, if left, form acid. It multiplies the alkalinity of the saliva. That to neutralize the acids which cause tooth decay. Two factors directly attack the film on teeth. One keeps the teeth so highly polished that film cannot easily adhere. These are all desired effects. They are aids to Nature which author- ities approve. See how they chang: your tooth conditions in this ten- day test. You are welcome to this test A 10-Day Tube of Pepsodent is sent to all who ask. It is bringing a new dental era, and we want you to know the facts. The fight on film Pepsodent results from many years of effort to fight film on teeth. Film is that viscous coat you feel. It clings to teeth, enters crevices and stays. The ordinary tooth paste does not end it, so film-caused troubles have been con- stantly increasing. Film is what discolors, not the teeth. Film is the basis of tartar. It holds food substance which ferments and forms acid. It holds the acid in contact with the teeth to cause decay. They, Pepsadent REG.U.S. The New-Day Dentifrice A scientific film combatant com- bined with two other modern req- uisites. Now advised by leading dentists everywhere and supplied by all druggists in large tubes. Millions of germs breed in it. with tartar, are the chief cause of pyorrhea. Thus most tooth troubles are now traced to film. Now dental science has found ways to fight it. These methods are em- bodied in Pepsodent. Five years of tests have amply proved it. The high- est authorities today endorse its prin- ciples. Millions now employ it. Send the coupon for a 10-Day Tube. Note how clean the teeth feel after using. Mark the absence of the vis- cous film. See how teeth whiten as the film-coat disappears. The book we send explains the rea- sons for its multiple effects. See and feel them, then judge for yourself how much they mean to you and yours. Cut out the coupon now. 10-Day Tube Free” THE PEPSODENT COMPANY, Dept. 181, 1104 S. Wabash Ave., Chicago, III. Mail 10-Day Tube of Pepsodent to Only one tube to a family 05

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esvy 5 VUE Ses we weuwpes, YY awww, . Your Choice 75c a Week

FREE! With every set is included — FREE —a Consulting Membership which gives you the privilege of submit- ting your perplexing problems to a corps of experts for an entire year. This Consulting Membership regu- larly sells for $12.00.

No matter what your occupation, one of the home study sets listed below will quickly fit you for a better job and bigger pay. Any set you select will be sent for seven days’ exami.a- tion, and if you decide to buy you may pay the rock- bottom price at the rate of only 75ca wees. But you must act now! The rising cost of paper and binding materials won't permit us to continue the present low prices much longer. These books are the work of recognized authorities. They are written in plain, easily understood language by recognized authorities, and contain hundreds of photographs, diagrams, tables, etc., that make diffi- cult points as simple as A-B-C. Handsomely and durably bound in half or full morocco leather (except as noted), and stamped in gold Pay-Raising Books At Greatly Reduced Prices Accountancy and Business Management, 7 vol., 2700: pages, 1000 pictures. Was SS250 6 ..<:2 eS, Se as ee ee Now $29.80 Carpentry and Contracting, 5 volumes,

2138 pages, 1000 pictures. Was $37.50. Now 24.80 Civil Engineering, ¥ volumes, 3900 pages, 3000 pictures. Was $67.50 .........Now 39.80 Electrical Engineering, 8 volumes, 4100 pages, 3300 pictures. Was $60.00 .Now 34.80 Automobile Engineering, 6 volumes, 2600 pages, 2000 pictures. Was $45.00....Now 29.80 Machine Shop Practice, 6 volumes, 2300 pages, 2500 pictures. Was $45.00...Now 29.80 team and Gas Engineering, 7 volumes, 3300 pages, 2500 pictures. Was $52.50, See er ee cb ale totais Be haw be eee 29.80 Law and Practice (with reading course), i3 volumes, 6000 pages, illustrated. Was NUE See ese Sse Who'd BSc es OF ..Now 49.80 Fire Prevention and Insurance, 4 vols., 1500 pages, 600 pictures. Was$30.00 Now 19.80 Telephony and Telegraphy, 4 volumes, 1728 pages, 2000 pictures. Was $30.00 Now 19.80 | Sanitation, Heating and Ventilating, 4 | volumes, 1454 pages, 1400 pictures. Was MD Rahs svt 2505/0 ate sieice au he cs cae Now 18.80 Drawing, 4 volumes, 1578 pages, 1000 pic- tures, blue-prints, etc. Was $30.00...Now 19.80 Send No Money Shipped for 7 Days’ Trial Yes, we'll gladly ship any set right to your home or office upon your simple request. Pay only shipping charges when the books arrive. Don't send a penny until after you have used them seven days, then re- mit only $2.80 or return them at our expense. Pay balance at the rate of $3.00 a month—75c a week. Act now—while these splendid books are being offered at 20% to 50% less than regular prices. This offer is open to every person within the boundaries of the U. S. and Canada. Grasp your opportunity— fill in and mail this coupon NOW!

American Technical Society, Dept. X201, Chicago American Technical Society, Dept. X201, Chicago, U. S. A. | | Please send me set of |

I will examine the books tho oughly and, if satisfied, will send $2.80 within 7 days and $3 each month, until I have paid the special price of If I decide ; not to keep the books, I will notify you at once and hold them subject to your order. Title not to pass to | me until the set is fully paid for.

| NAME. | ADDRESS. . .

REFERENCE ........4- 9uncacsseveese ccccvcevecess

104 other end of the condenser tube and run it to a clean glass receptacle. Pass a small stream of cold water through the condenser by connecting the lower of the short glass tubes with a hydrant and the upper to a drain. Just open the faucet enough to keep a small, easy stream of cold water passing through the condenser and out of the drain hose. The steam from the boiler passes through the condenser and becomes condensed in the tubes chilled by the flowing water. The pure distilled water is collected in the receptacle as shown.—FRANCIS DASHIELL. To Hold a Saw in a Vise with Spring Leaves WO leaves from an automobile spring form a desirable adjunct to the vise when saw filing or when filing

the edges of sheet metal. These may have vise jaw SPRING clamps of sHEet Meta, _ ‘EAVES sheet iron riv- CLAMPS eted on them to make them hold properly in the vise while arrang- ing the saw for filing or clamping the sheet metal in place. The two spring leaves will hold the saw for filing blades are procurable from the pile of discards about the garage in lengths of three feet or more. They are curved in shape and, due to their meeting at the extreme tips first, will clamp the part solidly and afford sufficient rigidity to permit of filing the parts freely.—G. A. LUERS.

A Novel Pen-Rack for the Writing-Desk N attractive pen-rack that any one would value can be made from an old horseshoe. Get the horseshoe and, if it is dirty, clean it well. Should there be a rusty, uneven surface on it, this must be smoothed down with emery - paper. There is no need, however, to get thehorse- shoe really bright. You will now need six rather short nails bent slightly up- ward. It is quite easy to bend these with a pair of pliers, and you should try to get them all with about the same curve. You must now get a much longer nail, one that is almost six inches long being the best. If you cannot secure so long a nail, a piece of stout wire would do as well. This long nail or piece of wire is curved 106 ah

An old horseshoe makes an attractive pen-rack for the writing-desk These , old spring. PERFECT SALES CO.,140 W.Mayfield Ave., Dept. 45, Chicago, Ill.

Popular Science Mon lily AX AON \ j IOIRE | : HH WHOA YW ECKTFE . \ re |

= DD y Lous Home Learn Sci- tie ,Cou'se entific Box- own home Thousands ar now doing it. Just send me_ your name, age, occu- pation and vag 2 address and “ I will send you my Free Book- let explaining ex- actly what my course contains. Dept. W Gibbons Athletic Association Metropolitan Theatre Bldg. ST. PAUL MINNESOTA % Z SAA ADAG vane \ N’r tt SAY \ RY \ W \ Way"

a ar

\ Sw SiN Sc 90 fo 125 W/o Miles on Ay a Gallon of Gasoline! The Shaw Motorbicycle. A high-grade, easy running, speedy motorbicycle of dependable power at a saving of from a third to a half in actual money. Equipped with 24% H-P Motor, famous Breeze carburetor, high tension magneto. Automatic lubrication. Chain drive. Simple, efficient control at all times. Thousands in use. Write today for prices and terms, also about the Shaw At ment—fits any old bike. SHAW MANUFACTURING Co. Dept. 461, GALESBURG, KANS.

Shoot Without Noise Avoid disturbance, also flinching. Enjoy quiet shooting, anywhere, anytime. Use the new Model 1920 MAXIM SILENCER Price, .22 cal. $7.00 All larger calibers $10.00. Send 6c in stamps for catalog and BOOKLET of astonish- ing experiences ot Silencer The Maxim Silencer Co. 91 Homestead Ave. Hartford, Conn.

e e Build This Car een, his nifty little car ae riven by gasoline motor, can be | by eny boy Parts furnis! i by us

to build this lads SYPHER MFG. CO., 174 Sypher Bidg., Toledo, Ohie ‘Learn to Dance You can learn Fox-Trot, One-Step, Two-Ste Waltz and latest ‘‘up-to-the-minute’’ societ) dances in your own home hy the wonderfu! Peak System of Mail Instruction. New Diagram Method. Easily learnec no music needed; thousands taught succes: fully; success absolutely guaran b Write for Special Terms. Send today for FREE informatior. and surprisingly low offer

WILLIAM CHANDLER PEAK, M. B. Room 117 821 Crescent Place, Chicago, ti! Jan

ITY, Here's The eAN C * how { S out I hi strong, it is the sides t pl ts). L Wheels ha’ “And m challenge : x Ain Aut You'll enjc the Auto-] Auio-Whe some book Set you Show this 3 coaster handle th Free for € Spokesma about our the Auto-

Bar No. tior lini sea

Popular Science Monthly Januc

Page 93

—— FF Says es veEewrw Ww VY we Jan: ary, 1921 ly . Here’s the reason I wanted a sot : The sAuto-WheelRoadster GC} © how these sides work?—When I spread them ~ out I have a hauling wagon. Just see how str ug itis. Now suppose I want to coast, I push the sides towards the center. (They swing on pivots). Look at that roadster. Built just right. Wheels have real roller-bearings. Noother wagon like it. “And maybe you think it doesn’t travel. —I’ll challenge any boy on this street to a race.” The Perfect Christmas Gift ‘in Auto-Wheel wagon is a year-’round pal. You'll enjoy it throughout your boyhood. Besides the Auto- Wheel Convertible Roadster, we make the Aulo- Wheel Coaster, the all-purpose wagon. Hand- some booklet describes all sizes and models. Set your heart on an Auto- Wheel for Christmas. Show this ad to Dad. Send us names of 3 coaster dealers, telling which ones handle the Auto-Wheel, We'll send .. Free for 6 months The “‘Auto-Wheel « Spokesman,”’ our magazine telling about our BIG PRIZE CONTESTS and the Auto- Wheel Clubs, You may be able to win an Aute- Wheel. We'll also send the Auto-Wheel Coaster DimeSavings Bank. Tre SuloWhea Coaster Co..inc. The Buffalo Sled Compana AST. Schenck Street, N. Tonawanda, N.Y. j In Canada: Preston, Ont. © Export Office: 365 W. 23rd ¥ New York City é Auto- Wheel Spokesman FREE Wool Arimy Shiris f Money Back Guarantee Genuine Olive Drab All Wool World’s g==-33 Greatest Work Shirt! Only ol Postage Prepaid Several Now ! No. 200 — Wool Arm , tion U.S. Army Olive b. Breast inter- lining. _ Reinforced elbows, Double sewed seams. Made of best wool shirting. Thorough- ly laundered and repaired. New ones cost over $3.00 if shipment just received—but they’ll go quick- fy. Money refunded if not satisfac- tory. Order at onc Price each, delivered prepaid, only .......... $2.87 Shirts. Regula- BIG BOOK of New and used Army | CARNIE - GOUDIE CO. Goods. Writel} Oept. K Ss, Kansas City, Mo. New Big No. 14-200 pp. Wireless and 100 pp. Electrical Catalog Wireless catalog mailed for 12¢c and electrical catalog for 6c. You may deduct this amount on first $1.00 CATALOG NO.14 The Wiliam B. Duck Co. a purchase. Catalog not sent other- ANYTHING vies , virelece > vill tell yRECAL § wise. Any wireless amateur wi you it isthe one catalog to have s anencyclopedia of information it is invaluable. The largest and most elaborate radio catalog pub- lished. Values that cannot be duplicated elsewhere. THE WILLIAM B. DUCK COMPANY 212-214 Superior St. TOLEDO, OHIO VeswV — as shown in the illustration, so as to form a support for the rack. ‘I'he six small naiis are soldered into the holes, three on each side. The big nail is then put in on the other side so that it forms a brace. It should be arranged in such a way that when it touches the table, the horseshoe is held nearly upright. When all this is completed, the whole of the pen-rack may be painted. Paint of any color may be used.—S. LEONARD BASTIN. Remodeling a Plain Piece of Furniture ITH a little mechanical skill and a few carpenter tools a common- place and unornamental piece of fur- niture may be remodeled into an attractive and useful object fit for any room. The accompanying illustration shows how an exceedingly plain and unprepossessing bureau was _ trans- formed into a handsome and artistic buffet. The bureau originally had three plain drawers with varnished natural wood fronts. The top drawer was 1} DRAWER \y REMOVED DOORS IN |_ PLACE OF DRAWERS This shows what may be done with a little skill and a few tools removed together with the partition between it and the middle drawer, which was also discarded. From the material contained in the top drawer a small drawer was made, supported by brackets as shown in the illustration. The space previously occupied by the middle drawer was made a shelf by polishing and varnishing the partition board on which it had rested. The bottom drawer was also removed and from the front board of it a double door was made for the bottom com- partment. Ornamental hinges and keyhole escutcheons enhanced the antique appearance of the buffet. How Ford Springs May Be Oiled Easily MADE a set of spring oilers that proved very efficient for our Ford car. I took newspapers and cut them about four inches wide and the same length as one side of the spring. Then I cut little slots in the paper where the 107 The Hour That a When you see a man putting in his noon hour learning more about his work, you see a man who won’t stay down. He’ll never be satis- fied until he hits the top. And he’ll get there! In shops, factories, offices, stores, in every line of industry, men are holding splendid positions won through spare time study with the International Corre- spondence Schools. Today they are earning four or five times— yes, some of them ten times as much money as when they started. Employers everywhere are look- ing for men who really want to get ahead. If you want to make more money, show your employer that you’re trying to be worth more money. For 29 years the International Cor- respondence Schools have been training men and women homes. right in their own More than two million have stepped up in just this way. are studying now. More than 130,000 Can you afford to let another hour pass without making your start toward something better? Here is all we ask—without cost, with- out obligation, mark and mail this cou- pon! — = oem eer TEAR OUT HERE see se eee oe meee INTERNATIONAL CORRESPONDENCE SCHOOLS BOX 7608-B, SCRANTON, PA. Explain, without obligating me, how I can qualify for the ELEOTRIOAL ENGINEER Electric Lighting and Rys. Electric Wiring Telegraph Engineer Telephone Work MEOHANIOAL ENGINEER Mechanical Draftsman Machine Shop Practice Toolmaker Gas Engine Operating CIVIL ENGINEER Surveying and Mapping MINE FOREMAN or ENGR STATIONARY ENGINEER arine Engineer Ship Drafteman ARCHITECT Centractor and Rallder architectural Drafteman Concrete Builder Structural Engineer PLUMBING AND HEATING Sheet Metal Worker Textile Overseer or Supt. ONEMIST L) Mathematics Name (J Poultry Raising position, or in the subject, before which I mark X. SALESMANSHIP ADVERTISING Window Trimmer Show Card Writer Sign Painter Railroad Trainman ILLUSTRATING Cartooning BUSINESS MANAGEMENT Private Secretary BOOKKEEPER Stenographer and Typist Cert. Pub. Accountant TRAFFIC MANAGER Railway Accountant Commercial Law GOOD ENGLISH Teacher Common School Suabjecte CIVIL SERVICE Railway Mail Clerk AUTOMOBILE OPERATING Auto Repairing Navigation Spanish AGRICULTURE French Itellao Present Occupation Street and No City. State Canadians may send this coupon to 7-25-18 International Correspondence Schools, Montreal, Canada

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4a —s ame 5 V ao OO "821 Crescent reAan, . & 1 106

Popular Science Monthly Be Januiry,

-— = — clips hold the spring together and made

== ae —— DIRECT FROM THE F ACTORY the paper fit snugly around the springs. | From paper patterns I cut covers of TO YOU FOR $13.50 black muslin. Then I made covers out AU ; Lene : 2 of some side curtains from an old car. This genuine waterproof raincoat, com- . bining all qualities of the highest-gr-ce I got an old woolen blanket and cut it garment, the final achievements in style, | in strips that were about the same | durability, ventilation, design and material, | idth dl h h . dI E XPE |DIRECT FROM THE FACTORY TO|| | Width and length as the spring, an / cha YOU BY PREPAID INSURED PAR- | sewed them THE OLIVER OIL-GAS BURNER Well tr | CEL POST. together— Does away with coal and wood — Cheaper. can qua With the signing of the armistice and | ge 2 Makes your stove or range a gasstove. Gives you by | termination of our Government contracts, | about five more heat. Be =~ oa pyar : instruct we found ourselves stocked with a large | thicknesses in MoS omen a ok wood. Saves hours work thousar supply of material and, having lost our peep hod pay my Pp my ment. civilian patronage, we decided to sell | REAR SPRING all. ’ pay ong ifaies fts'owa gas from Goal oil eroser’ automo | I ‘soaked at small cost. Gives even heat instantly canizin | i much or little, Saves money, time, labor, ing cls these in cylin- : a — py A Cc italo mt Well wrapped and oiled ‘ : \ = Ei literature and train 0 direct from the factory to you. Man's springs will not squeak der oil for ; pert a model shown is double-breasted, with in- | about fifteen ae tions. verted pleat down back, belt all around, | P . Oliver Oil-Gas Burner Ae ABA copy ! | buckled wrist fastenings, outside patch | minutes and then laid them flat on A Machine Co., fee Moto! pockets, convertible col- | the top of the springs The muslin 2O1 LOUIS MO” 0G lar and built so that | = ROS : ip TURN A VALOR 2698 U NO WET CAN GET || | cover was first wrapped around the i comps ‘Sa: © coom: pit | THRU. | spring and next the old _ side-cur- seas AN IDEAL tain cover. I wound friction tape | CHRISTMAS GIFT around this to hold it in place. The — bargain or yours oraneal | only care I give to the springs is to SCID e Roofing tives or friends. A gift of this || | Pour about two tablespoonfuls of oil in i pA. ID, at Factory and) bouns to be appreciated | the tops each month. The car rides ASSL KEL Ke Prices ceint of your remittance and | better and squeaks are eliminated. instructions, we will send a — —. Peerless Raincoat direct to “Reo” Cluster Metal Shingles, V-Crimp, Corru- | hae ®

the desired person for Christ- pated, Standing Seam. Sg CORC( )) : Fr . P Cont Bottle Capper | | | Puts metal crown caps on any size won | | | Standard beverage bottle. No ad- oo justment. Always ready. Mechan- cally perfect. Positive seal. Your |! . | beverages will keep if capped with ’\ See? i r a CORCO. Nickel plated—weight SLA. IH + H,- 10 ounces. a. i, ‘Wit! re) # COLT If your dealer can’t supply you, in: . send us his name and $2.50 and a ved z a CORCO Capper will be sent direct tik arnMechanical Drawing | | 2 ee Corco Manufacturin . Pa : 7 Woz Mccormick Odes Berta enaes °° EARN $35 TO $100 A WEEK AS TAPE IN HOLDER | The little matter of 10 ets. will bring you 8 | the Pathfinder eight weeks on trial. ¢ The th AN EXPERT DRAFTSMAN | What Pathfinder is an illustrated weekly, pub- : : : . . . . . lished at the Nation’s center, for all the t We wit tesla you oy mail in yous _ n ~e ieongh qr With the aid of. this holder, wire- * ee ~y oat ae pos —_ wractica »me Study Course Mecha ~ F: z. 4 : cq . orl Mo ane our improved method you will learn Drafting as you would wrapping tape is easily handled a Dime and tells the truth; now in its 2éth in actual practice in any big drafting department. When year. This paper fills the bill with- gee Cates Cee cbaree you Sn ee eee ri poms Will bring out —— Wash oa | altsm = or ea opportunities je nak caacuannant to —— of making the OV erall length of the holder but $16 wear. If | the wetsn eeiel end ue raftsman paving $5, 0( ai re a ye > practi- > ’ i = poenn com y drafting hic hs e will give you may prove about 4 in. Three or four holes are You Posted "on What is Tike chine y a Fe. e stepping stone to position as ne ~ngineer I nag é P 2 Production at ; much high - ap eal ee Our graduates are ee through oe for a 3/16-in. Fromthe world, at the Se inatis doting. I always in deman ig concerns employ them regularly at machine-screw whic serves as a | east expense 0) ‘ g00d salaries, because they KNOW-—because we produce ° we g time or money, this is your means. first-class professional Draftsmen. shaft for the roll of ta e to turn on. If you want a paper in your home tr WRITE TODAY FOR FREE CATALOG | en eee ee eerie | WQUUOING pues erie ante ter: 3 telling what we have done for others and what we can do for n e op ) e hoider 1s cut as it . es yours. If you would appreciate a pa you. It will open your eyes to Your Future in Drafting. about 1/16 in. wide for the tape to pass t i= which puts a clearly, , ROY C. CLAFLIN, Pres., through. The roll of tape is inserted api a yy py Tike such I COLUM ite pe is ’ @ paper, and we will send the Pathfinder on BIA SCHOOL OF DRAFTING, ; , robation eight weeks. The 10c does not repay Us, Dept. 1204, Washington, D. C. the machine-screw passed through, and ut we are glad to invest in new friends, Address: , a nut screwed on and _ tightened | THEPATHFINDER. 486 LanedonSta.. Washington, D.C. oe against the holder so as to spring it in | slightly and cause the roll to turn YouCanSave $50. 00! i ) ° ° By recovering your old LF e want one exclusive repre- stiffly when the tape is pulled through. gute top frame yourse'! 7 sentativeineach locality use The tension can be adjusted b all makes and models of ca: Prana rade tires. Guarantee Bond for ont ang aap tie A sarctnrativon, Waters “ 8000 Miles. (No peconds). Shipped pres means oO . e nu : . e wor man Pa vemedene Cemether wi #5 ZEA Bald on sprrovalt cur Bpectal Direct Prices, Write has to do is to wind the tape running | | thecal, festeners,_ melts and tacks. All complete: Give » aXe * ; MFLLINGER TIRE & RUBBER CO, t it . d our catalogue with samples and quote you exact price. Mf 1004 Oak St., Kanses City, Mo. out as it 1S used. LIBERTY TOP & TIRE CO., Dept. E8. Cincinnati, O

108

Ponynular Science Mon?))),,

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erreur were

1 (a PS PUTED, AU TEET OME, VIE 107

fF hly January, 1921

' How Window-Washing Can | Be Made Less Irksome INDOW-WASHING is not usu- ally considered a pleasant pas- time, particularly in winter. It is decidedly unpleasant work. One of its most annoying features is the discomfort caused by the water run- ning down the arm when it is extended for the purpose of washing the upper part of a window-pane. One ingenious | janitor found a simple method of pre- venting this particular annoyance by

BE AN 2 | | AUTOMOTIVE EXPERT! \XPERT Automobile and Tractor Me- Ek chanics are in demand everywhere. Well trained men earn big money. YOU can qualify for these positions. We teach you by daily actual practice under skilled instructors. Experience in training thousands of mechanics for U. S. Govern- ment. Course include all branches of automobiles, tractors, welding and tire vul- canizing. Day or even- ing classes. Our free catalog tells how we train men to occupy ex- pert automotive posi- tions. Send for your copy now. Motor Institute, Inc

Don’t Grope for Words Give Grenville Kleiser (famous Speech Specialist) 15 minutes daily He Will Give You a Mastery of Words There are no old-fashioned, wearisome rules of grammar to memorize. By an entirely new plan you absorb and immediately apply the fruits of years of teaching experience which are comprest into twenty intimate’ homé(essons 2698 University Avenue S. E. Minneapolis, Minn.‘

J ] Old Style Shavin Best Of All Every man knows that Old Style Shaving is best—but few know how to keep the Old Style Razor in goodcondition. Just plain stropping will not produce a perfect cutting odge—8 good honing once a week

If you will devote 15 minutes daily to this orig- inal Course you will quickly and surely learn to ; " rt ria]

Pov makes! good My ih it Enlarge Your Stock of Words— shaving comfort. y ti Wit) Use the Right Word in the Right PoneYourO NN Place— RAZOR-HONE

is the only hone that the inexperienced man can use without fear of over-honing— the holes (patented) aut tically remove the rough, scratchy edge that makes the Old Style Razor pull. These holes shear off every particle of ‘‘Wire-Edge.’’ TRY ONE 30 DAYS If it fails to do exactly what we claim—to make your favorite old razor shave like new—return it at our expense, Your money cheerfully refunded. All ood hardware and drug dealers carry Perforated Hones — if yours is not yet supplied, send $1.00 direct to us with your dealer’s name, PERFORATED HONE CO., 314 Hammond Bldg. DETROIT, MICHIGAN Write Tactful, Forceful Letters, Advertisements, Stories, Ser- mons, Treatises, Etc.— Become an Engaging Conversa- tionalist — Enter Good Society-—— Be a Man of Culture, Power, and Influence in Your Community.

Booth Tarkington One of these wrist cups will keep the Distinguished Novelist and Short Story Writer, water from running down your arm

érigin Author of ‘Monsieur Beaucaire,"’ *'Seventeen,"’ etc. pace pe mA age | nn . uree is almost pain- inetra- . P ully needed by many professional mest_the | placing a rubber washer on the wrist of wage ne | his right arm, as shown in the accom- course will Know what. he fe. tall aE : he writes. His audience will cer- ‘cdots | aapeemaieetion. 7 Nain Cnow tect tS wl i is book tells you w' use ‘ ; ell, ao matter what his subject.” Saxophone — singly, in quartettoe, = i a em ar _ —s : ar’ well, ao matter what his subject 0 sex , Orin regular banc, In dlameter, irom an O inner tube O . ) to transpose cello parts in orchestra ’ . and many other things you would © an automobile tire. Then hecutahole || Mary Roberts Rinehart like to know. \y i | v learn to the scale In one hour’s } j } i< i Eminent Novelist. D-amatist. and War-¢ es pond- peg aN in the center, slightly smaller in diam= |[ ori tivthoraf"K.""" Rings, Queens and Pawnsy” el -s popularity. Easy to pay by our . eomanet eter than his wrist. When the washer es Ee: ws 0S OS nant a was placed on the wrist, it fitted tightly cellent for the purpose. Also the is thing in True-Tone band and orchestra instruments d ‘ . d h di 3k f bb f — of books for — y ap. 8 BUESCHER.24n°. INSTRUMENT Co. and caused the disk of rubber to form Coke like a scholasly and sacet in- ] 314 Buescher Block, E:khart, Ind, a cup that would eatch the water telligently ———— course of in- , struction and writing th a squeezed out of the sponge or cloth S " that otherwise would have run down R ne . : the arm. The water was emptied from FREE er ; i i — + VAN N ‘*How to Becomea Master of English”’ 10 Expert electrical engineers are being paid time to time.—DALE VAN Horn. : 2 fabulous salaries. Thousands needed to- 1 quamnnan Gaantueaa eet ee ae tee Ge Bs yr . anc é 1 ou, the . day. We give you personal and thorough real practical help it will give you in a hundred e training — practical, technical, courses three ; ; 1 different ways. Obtain a mastery of English and : CSG dake ae oe. ema emes | | Saving Time by Using a New || mre cai (Beye i electricity, steam, gas, auto, armature winding, * | avery why. ’ ; rafting, etc. Extensive laboratory and shop | Adjustable Wrench | pee ! ¢ uipment. Not a trade school. Surolt anytime. | SIGN AND MAIL THIS COUPON NOW i not judge us by size of ad but write for free illustrated catalogue, | 1 . : Ben te . R . n FINDLAY ENGINEERING COLLEGE | IT TLE time 1s W asted in set ting chisditititataieiiaitian iiiniaiiainsinbaiaamiiil 1003 tatienn tem ee . ee the wrench shown in the accom-

| Funk & WAGNALLS COMPANY panying illustration to fit nuts or bolt- Dept. 460, New York heads of different sizes. Pulling out a || Please send ty mail Booklet and full information regarding Grenville Kleiser's Correspondence Course

Over 100,000 in Use

I Mostly sold through fe $ little knob will release the grip of the || in Good English I For Personal Desk o A jaws of the wrench after you have com- |{ yame I | RRR oo pleted your work. Local Address........++s0s00: <a The movable jaw of the wrench has || Street and Number or R.F.D, | at the end nearest to the handle a little || post ofice nee Pee J eaben, that io promeed. Dy -@ SpPiNE 11 pes... o.oo. c 5.2 :GteWeccccccccteccccees | 109

| sahhd

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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 the client. Our Hand-Book on Patents is sent free on request. This explains our methods, terms, etc., in regard to Patents, Trade Marks, Foreign Patents, etc. If you are a reader of SCIENTIFIC AMERICAN you are probably aware of the fact 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 legisiation 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. CAN YOU think of a simple, practical idea that will fill one of the many re- quests we have on file for new inven- tions? It may mean a fortune for you, Thousands of things are needed RiGut Now. Your brains can help. Send toe day for our great new book—“‘Invene tions and Trade Marks, Their Protection and _ Exploitation’’ and learn more about making money from ideas than you ever knew before. It tells many things that are wanted, t0O. A postal will do— it is free. sieges — acter oe eas fae. ADVERTISED te ots pose For SALE FREE pon caciaygee ne AMR INVENTION Aad pont ot once" Ml MANUFACTURING SUPPLEMENT. AMERICAN INDUSTRIES, INC. 201 Patent Dept., WASHINGTON, D. C. Published for -the man with an idea Send for free sample copy. One year'ssub- tm Bcription 50c. 1" or $5 wit’Buy A Standard, Guaranteed im With Every Modern Writing Convenience Write Today For Illustrated Circular istuhates Try-Before-You-Buy Plan SMITH TYPEWRITER SALES Co. (Harry A. Smith) 396 —218 No, Wells St.,Chicago, ll, 108 against the ratchet teeth cut into the side of the wrench-bar. If you wish to use the wiench, bring the fixed jaw with its Miner side against one of the flat sidesgf the nut or bolt- head, slide the movable jaw toward the nut until it is pressed firmly against the opposite flat surface, and let the catch engage the teeth of the ratchet. The jaws will hold the nut or bolthead DETAIL Push the jaws against opposite sides of the nut and the catch will hold them tight until released firmly until they are released by the disengaging of the catch. There is no screw to turn or other complicated and time-consuming oper- ation to be performed to secure a firm grip.—CHARLES SCHADEL. Cutting Large Keyways by Hand NUMBER of large keyways had to be cut in heavy shafts in a shop that had no machine that would do the work, and it was necessary to devise a method on the spot. The problem was solved in the acanitines ingenious way: A steel tool was made the same width as the keyway, with a cutting edge on one side. The wheel was placed on the shaft with the wheel keyway, which was already cut, in its proper posi- tion. The tool was about 1/32 in. deeper than the keyway in the wheel hub. It was inserted and driven through witha @==— hammer,and as CUTTER it went through it cut a shallow groove on the shaft. It was then sent through again, this time with a strip of sheet iron on top, which forced it to take another cut. This process was repeated until the cut reached the desired depth. In- stead of using a large number of very thin strips to cause the tool to feed, heavy strips were used as the cut went deeper. The work was done in a shorter time than would seem possible. In fact, the scheme was so successful, that the shop later rigged up a false hub so that keyways could be cut without the wheel being in place, and a false shaft for cutting keyways in hubs. 110 ge CUTTING EDGE Nothing simpler than cutting keyways in this way A tl el ee Tl eed ee, ee Popular Science Monthly Free Book on Patents Before applying for a patent write for a Free Copy of our book ‘How to Obtain a Patent,” which contains valuable information and advice to inventors. Ittells how to secure Patents. Send a model or sketch of your invention for our ‘‘Evidence of Conception” form and our opinion of its patentable nature—Free. Twenty years’ experiencein patent matters. Write today for your E BOOK. 4849 Talbert Bldg., WASHINGTON, D. C. PD LL LLL PATENTS Booklet Free Highest References Promptness Assured Best Results Send drawing or model for preliminary examination of Patent Office recor« and report as to patentability All Business Given Prompt and Proper Attention WATSON E. COLEMAN, Patent Lawyer 624 F St., Washington, D. C. I. T. S. Patents Five years ago, practically without capital, J. G Tufford, Elyria, Ohio, and his associates Smith and Ingwer started business with the now well-known I. T. S. Rubber Heel under the Tufford U. S. and foreign patents obtained through Lacey & Lacey. Fourteen tons of these heels are now produced daily. The profits already amount to many hun- dreds of thousands of dollars and foreign patents have been sold to the extent of $550,000.00. That demonstrates the financial possibilities even of an extremely yng invention of merit properly patented. Read PATENT-SENSE Sate " “dhe Book for Inventors & Mfrs" eis By Return M. Wi =) Lacey UNeey Te RTE Ne zal Deafness : Perfect hearing is now being re- MEO stored in every condition of deaf- ) ness or defective hearing from causes such as Catarrhal Deaf- ness, Relaxed or Sunken Drums, « Thickened Drums, Roaring and -“\ Hissing Sounds, Perforated, Wholly or Partially Destroyed Drums, arge from Ears, etc. Wilson Common-Sense Ear Drums “‘Little Wireless Phones for the Ears’? require n0 medicine but effectively replace what is lacking or defective in thenatural eardrums. They are simple devices, which the wearer easily fits into the ears where they are invisible. Soft, safe and comfortable. Write today for our 168 page : FREE book on DEAF: » iving you full particulars and testimonials. WILSON FAR DRUM CO., I ted 283 Inter-Southern Bldg, LOUISVILLE, KY WILLIAM C. LINTON Consulting Engineer and Patent Attorney “Inventor's Adviser’’ Mailed free on request. Gives full information as to Patents, ieee Marks and Their Cost FFICES 916 F ST. N. W., Washington, D. C. 364 UNIVERSITY ste Montreal, Canada. Janucry Three A:: any L€ muc:i | T plat jor! built O least these a braces it —_ BRACE / Boys this s detail board: side. Nex bers Curve a lars from make deep : Foll here each same sink Th third is on cente No the brace This edge, dow? Hi; the | trati loose

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January, 1921 — Three-Runner Sled Made of | Barrel Staves | ARREL-STAVE sled fitted with steering runner can be made by any one skilful with tools and will give muc!: pleasure to the builder. Tie body of the sled consists of a platiorm, 45 in. long by 24 in. wide, built of l-in. boards. Probably at least three boards will be required and these are cleated together by three oak braces the shape and size shown in the K 45" - > SEAT) Q tT } i ‘« ~ 7 TILLER | ) x BRACE / — RUNNERS \—— STRAP IRON Boys clever with tools can easily make this sled from the drawings detail sketch. Place across the body boards so 1% in. will be left at each side. Next, cut out two side-runner tim- bers of 1%-in. lumber 12 in. wide. Curve the bottom edge to the curve of a large barrel-stave, preferably one from a crockery barrel. This will make the centers 12 in. deep by 10 in. deep at the ends. Screw a stave to ja 12 ——» $2" f= -- |-: BODY BRACE 4 STEERING RUNNER K 30° eae = SIDE RUNNER BLOCK Follow the lines and dimensions given here in cutting the runner blocks each timber so the ends protrude the same distance at each end. Counter- sink the screwheads. The steering runner is attached toa third block the same way. This block is only 12 in. long, 11 in. deep in the center, and 10 in. deep at the ends. Now fasten the two side runners to the body, fitting them against the braces and under the body boards. This should bring them flush with the edge. Screw them to the braces and down through the body from the top. Have a U-shaped iron strap made at the blacksmith’s similar to the illus- tration. A heavy bolt should fit loosely in the center hole. Place this a — Oeuw ss veswy —_ ee. 2 ae = _ ao a ee Ss 109 % TRADE-MARKS he) AA ES SPECIAL OFFER FREEOPINION as To PATENT ABLE NATURE Befo~e disclosing an invention, the inventor should write ? for our blank form ‘*‘Evidence of Conception.’ This should be signed and witnessed and if returned to us to- : gether with model or sketch and description of the inven- tion, we will give our opinion as to its patentable nature. Our Three Books Mailed Free to Inventors Our Illustrated Guide BOOK HOW TOOBTAIN 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. GY SPECIALIZATION Our Staff The field of invention is so vast that it is impossible for any one man to become an expert in all the different classes of invention. Only those practically skilled in the class to which the invention relates are capable of rendering efficient service. For this reason Victor J. Evans & Co. employ a number of patent lawyers and mechanical experts who have been selected for their special knowledge and ability in certain lines of invention. Each case is placed in charge of experts in the classes in which the invention relates. THE VALUE OF YOUR PATENT Will depend much upon the skill and care with which your case is prosecuted in the United States Patent Office. This work will receive the benefit of skill and experi- ence acquired by a long and successful practice. We spare neither time nor pains to secure the broadest possible patents that the inventions will warrant. That every case entrusted to us receives our best efforts, and that our work is done consistently, skillfully and thoroughly is evidenced by the many unsolicited letters of commenda- tion that we receive constantly from our clients. We will furnish upon request lists of clients from any State in the Union for whom we have secured patents. Our New York, Philadelphia, Pittsburgh, Chicago, and San Francisco Offices Owing to the growth of our business we have established for the benefit of our clients Branch Offices in New York City, Philadelphia, Pa., Pittsburgh, Pa., Chicago, Ill., and San Francisco, Cal. These branch offices being located in these large commercial cities, together with our Main Office located nearthe 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 pe oes ee | | § = “FREE COUPON@ SS 28 Se eee eee 2] VICTOR J. EVANS & CO. MI Patent Attorneys New York Offices Philadelphia Offices 1007 Woolworth Bldg. 135 S. Broad Street 514 Empire Bldg. (| Chicago Offices, 1114 Tacoma Bldg. San Francisco Offices, Hobart Bldg. Main Offices, 760 9th Street, Washington, D.C. Pittsburgh Offices a a a a a a a ml

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i ite L , , Bitte eben ee, eed — Ee ee .- » BVVneLy 110 ; Jani Popular Science M. ithly j i ith the head h : Makin in wl e head as shown and trap IF YOU HAVE AN the whole superstructure to the - ‘eer. fr INVENTION and DESIRE ing-runner block at its center. The REY TO LEARN HOW TO — is then passed through the hb Je jp A Lc SECURE A PATENT, send for Our Guide Book, HOW TO || ‘he body about a foot from the ‘ont cal, or & GET A PATENT, sent Free on request. Tells our Terms, Methods eee Deing (have yo ee , >» ’ placed above and below the boy to worksho etc. Send model or sketch and description of your invention and we prevent wear. hobbies will give our opinion as to its pote Cut a tiller out of hard wood, «! the almost patentable nature. i $1ze and shape indicated in the llus- gO to a , RENEE bcisis wich Seprctoncrns doch bvaxsecdoeoiw teed Saal | tration and place it over the pro}: ‘ting for one, RANDOLPH & COQ! stmtet.ccccssucinnnnnnnsen | Portion of the bolt. Then placc ona save mo : | | nut and screw it tight, but be c: refy] 130 F St. N. W., Washington, D. C. Fina Me STATE...o.6so. ad | not to bind the bolt, for in that ise jt | will not turn the steering runner A seat somewhat like that shown ip r the side-view drawing will give com- fort to the rider. This can be built of PATCH short ends of matched lumber and upholstered if desired. The b Place an eyebolt in the front of the a pow ne 0 cde UT body to which a drag-rope may be Si | ND ey qi. x attached. are a bi cr THIS AN To the Man With an Idea The rider can seat himself comfort- cast-off : I offer a most comprehensive, ex- ably in the seat and steer the sled by fit, and DON’T LOSE YOUR RIGHTS perienced, efficient service for his moving the tiller from side to side. Imme TO PATENT PROTECTION: sso cola — a the This should be done gently, lest the water a Before disclosing your invention to anyone I EI “ bss ion. runner act as a brake.—L. B. Rosuins. end of send for blank —— as geome: ges we aa ‘ for advice as’ to Cat, po me ye oer into th Cc ** to be signed and witnesse ; prior United States patents, etc. Pre- y sc tenga ay ety sagas gaan liminary advice gladly furnished with- Filtering Rapidly with a unless 3 dence nn establish - a See arse ~t ee charge. is : the floo licatio: tent. n y experience an h . een hl me wa np Rann Maines srt neat eta a Funnel Attachment with se over the United States and Canada in the ad- accurately advise clients as to probable Take vancement of inventions. Our schedule of fees patentability before they go to any N order to increase the speed of filter- ; willbe cee om ee The form ‘ ——— expense. in a thin lass tubin about fant out of ro t tructions relating Book! f a 100 r oa Test pad on pe of iene freckle of valuable information s ns on = 8, 8 & s i lamp. sent upon request. Ask for them,—a post card request. Write today. long 18 taken and bent so that a ring 1s 9 smal will do. RICHARD B. OWEN formed near its upper end. This piece a al PATENTS AND TRADE MARKS wan \ Potent Lawyer of glass tubing is then attached to the the hol doin) 2276-D Woeltonh Bolin funnel with a piece of rubber. Fluids urpos New York City are filtered in the ordinary way, but oa dpa 274 Ouray Bldg. the so WASHINGTON, D.C. if desi Originators of forms ‘‘Evidence of Conception signs 1 handle PATENTS Convert Your Bicycle Into a Motor Cycle - By using a STEFFEY ATTACHMENT A Pl. TRADE-MARKS COPYRIGHTS A Easy to attach. Fits the double- Send for our free book bar, arch or diamond frame. In of patent information successful use over 21 years. Send on estat — stamp at once for lowest factory ‘é * ashington, VD. = prices. Beale & Par 16 S.Broad St., Philadelphia, Pa. he STEFFEY MANUFACTURING CO. A t Department S, 5025 Brown Street, Philadelphia, Pa. strips | strips, Standard Underwoods SEXUAL player 5- Year Guarantee KNOW E Wider Yes, oo genuine Standard Visible Writ- i er- $ Xe vr 08 newly " whriib seomniaie aD. pat S uit, at y INFIELD SCOTT HALL, M.D.,Ph.D. on factory FACTS MA PLAi N Grice, youre What every young 4 and for $5.00down and than easy monthly payments. 10 Days FREE Trial Try it for 10 days at our risk. Money back guarantee. Send now for free book—bargain offer No 14. TYPEWRITER EMPORIUM, Montrose and Ravenswood Avenue 14 Shipman Bulding Chicago, linols LRG Every young woman should know 1 00 What er every yours husband and = Every young wife should know ost What every parent should know Eee oe eth binding — — 320 pages—many illustrations wrapper ‘able of ions, on request AMERICAN PUB. CO., 117 Winston Bidg., Philadelphia “Buy Holiday y Gifts the Easy Way. Upena Cnarge Account with Loftis Bros. & Co. Onur large illustrated Catalogis your shopping guide to unusual bargains in handsome worth-while gifts on credit. Select as —s- | articles as you wish and have all charged in one account, Your credit is g 4 on purchases of Credit Terms $5 = over, ones fifth down, balance in eight ‘equal amounts, payable monthly. — | Stores in Leading Cities Dept. H uy LOFTIS BROS. & CO., The National Credit Jewelers Send for Catalog Whatever you select = = Cate log will be sent prepaid b You see and examine the ‘article tight in your own hands What could please a loved one more, or so well oupress your re- ard, as a beautiful ond Ring, a Valliere, Bar Pin, Brooch, Ear Screws, Wrist Watch, ora Diamond Scarf Fin, Diamond-set Emblem or Signet Ring, solid-gold Watch, etc. Send for Catalog today. Liberty Bonds Accepted. 108 N. STATE ST., CHICAGO, ILL. 112 An extension, consisting of a loop of glass tubing, attached to the funnel will hasten filtration filtration is rendered more rapid by the fact that the long column of liquid draws the liquid through the filter -y producing suction. The column of liquid in the glass tube, sinking by its own weight, creates a vacuum in the upper part of the tube The suction draws the liquid with great force through the filter paper or cotton and hence hastens the filtering opera- tion. This method is, obviously, only ol advantage in cases in which cond erable quantities of liquid are to be filtered. It will not prove efficicnt with small quantities. Popular Science Monthly Jan ae

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‘Oosely 1n the center hole. ithly (Tap leer. The ie in ront eing y to ‘ the illus. ‘ting ona reful se it Nin om- It of and the be ort- by ide. the INS, cer- oot g is ece the ids put = “ve he id January, 1921 Making a Magnifying-Glass from an Old Bulb © you a postage-stamp collector, A’. , collector of geological, botani- cal, or entomological specimens? Or have you an amateur laboratory or workshop? For any one of these hobbies a magnifying- glass is useful, almost necessary in some cases. Don’t go to a store and pay a few dollars for one, but make one for yourself and save money. The only materials needed -FILL WITH| WATER HANDLE ) j PATCH COLD SocKET \ OLD BULB The bulb filled with water will act as a powerful magnifying-glass are 2 burnt-out incandescent lamp, a east-off socket in which the bulb will fit, and a small piece of wood. Immerse the lamp in a basin of water and cut off the small tip on the end of the bulb. The water will rush into the bulb and will not come out unless you jar it with the hole toward the floor. Seal the break in the lamp with sealing-wax or adhesive tape. Take all the old wire and insulation out of the socket and screw it to the lamp. The taking out of the wire leaves a small hole in the socket. A piece of wood about 3 in. long, stuck into the hole in the socket, will serve the purposes of a handle. It should be sandpapered round. The handle and the socket may both be taped over if desired, and if not ornamental de- signs may be carved on the wooden handle.-—A. GOLDENBAUM. A Playing-Card Counter for a Friendly Game CCUNTER for card games and the like can be made from a few strips of stiff paper. Cut as many strips, about 3 in. wide, as there are Cut a strip about 1 in. or through players. wid:r—and rows of slits From a few strips of cardboard a neat and convenient counter may be made Which the narrow strips can be passed. The narrow strips are woven through the slits as shown, and the requi- site numbers marked on them. The humbers show in succession as the Strips are pulled through the respective 111 teow eSE aw OOOO awe aw awe maecaeaaaeawae ae a slits.—HowARD GREENE. January, 1921 PATENTS tion for patent. Record your idea by sending for blank form “Record of Invention,” before filing your applica- Send Sketch or Model for Preliminary Examination 212 Ouray Building Our terms are reasonable and our booklet giving full information on patents will be sent on request. J. L. JACKSON & CO. Washington, D. C. WRITE A SONG You can do it. Write about Love, Mother, Home, Childhood, Comic, Patriotic, or any subject and send words to me at once. i compose music and guarantee publication, EDWARD TRENT, 631 Reaper Block, CHICAGO electrica!, rope, air- plane, piano, pipe- organ, flat, hoops, bale-ties, tacks, nails, barbed-wire, concrete re - inforce- ment, springs, net- ting. wire fences, steel posts, trolley-road wires, and rail bonds, wire wheels, auto-towing cables, horse-shoes. Illustrated Books Describing Uses, FREE American Steel & Wine Co, °- Becton. 2.2086. 5A. The Midget Slide Rule will instantly add, subtract, multiply and divide either whole numbers, dec imals, fractions or mixed numbers. It solves proportion and gives roots, pow- ers, Sines, Tangents and Logs. The most versatile calculatorever inva nted. Made of Metal. or 4" rice with Instruction Book, $1.50. Satisfaction guaranteed. Send for our Catalocue and Instructions in Logarithms and Trigonometry. Gilson Slide Rule Co. Niles. Mich. Charge Batteries---Make Your Own Light The HB Lighting and Battery Charging Set makes electric lights for as low as 2c per and at the same time brings profits of $100 to $150 per month charging batteries. Operates from line-shaft or engine. Small Payment Puts This Money-Maker in © Garage or Shop Profits Polance on easy terms. 3 pay for out Absolute Money-Back Guarantee. F — Service Department about proper size for your needs. Pin this ad to your letterhead and write TODAY for information Hobart Brothers Company, Box S- 16, Troy, Ohio in a few hours at home you can easily bee come an accomplished dancer by my amazing new chart system. Simple as counting. Learn Waltz, ne-Step, Two-Step, Fox-Trot and all late dance gene. fe popular —the ory of the crowd. ave learned y- e pimply, send > card will eine Pat fells eeee my marreoue Bow stem. Special low r: te @ today. Prof. H. E. Wolfe, President. WOLFE’S MODERN DANCE STUDIOS Building, jissouri. Kansas City, M 108-D Woite Keep Young Thru Pandiculation You feel the need of exercise. You haven't time. 15 min- utes use of Pandiculator equals 2 hours in gymnasium. Gives you punch, Ree. and vigor. The lazy man's gym. 32-p. booklet FRE The Pandiculator Co.. 343 Advance Bldg., Cleveland O Home-Made Toys for Girls and Boys Here is a veritable gold mine of suggestions for home-made toys, each one of which has been carried out successfully SE TIN a tsb i'n 9. 0g 08 OG eae ad wile bho the h ues Price $2.25 Popular Science Monthly 225 West 39th Street, New York 113 Gibson Instruments Mandolin, Mandola, Mando - Cello, Gultar, Tenor-Banjo, Mandolin - Banjo, Collo-Banjo, Guitar-Banjo, Harp- Guitar, Mando-Bass — a’ ~~ Easy to Play Easy to Pay Select your Gibson now. ak can soon be playing the music of the day. Your friends will be surprised and delight- fully entertained. Let us help you organize a Gibson Orchestra i“ in your community. You can in- ' crease your popularity, income and pleasure by playing for Concerts, Enter- tainments, Church Affairs, etc. A small down payment and then $5 a month will soon pay for a Gibson and will fur- nish you with wholesome, year-’round entertainment. If you have an old instrument, we will make liberal allow- ance on a Gibson. Write Today for Free Book, Catalog, Free Trial Offer, information about Wm, Place, Jr. Book and the instrument you prefer. GIBSON MANDGLIN-GUITAR OO. 481 Parsons &t., Kalamazoo, Mich., U. 8. A. air method is mak- ngmen RICH! Chas, Evans, carpenter, $1 eee now MAKING @ week in sho; shown here. Gibbard of Mich., age 62, learned TIRE SURGERY, has shop ‘in small tow n, writes: ‘‘Cash receipts for May, June and July; 1920, $30,000.00.’ HAYWOOD'S wis easy tolearn. I will teach you in two weeks, Within thirty ar ou’re started on road to fortune. Car owners EVERY ERE demand be NEW on igen meth- res wear- ire Sur- Mr. Mavis Gaoncl Anon i ‘ ve., indiana a Dear Sir: Send full details of Tire og as I want to get into big paying business quickiy Name. Address.

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NS Se Swe wauyw r= ce New Bi¢ Pay Field Now/ Trained Traffic Experts Earn $2500 to $10,000 a Year and More Do you want to get into a field of work that is uncrowded—where the job will seek you instead of you looking for it? Do you want to earn $2,500 to $10, 000 or more a year? Do you want a position of prestige and independence? Do you want to be one of the biggest—one of the most important men of your company? Of course you do! Then train for traffic work—be a traffic expert. Transportation today is the country’s second largest industry. Four billions of dollars are annually spent in freight charges. Yet perhaps eight.of every ten shippers are losing money. And why? Just this: few of the men now in traffic work actually know how to route, classify and pack freight to get the cheapest rates. Millions of dollars are being wasted in this way. 100,000 more competent, well- trained traffic men are needed to stop these losses. Be one of these experts and you won't have to look for a job. The job will look for you. You may almost set your own salary! Thousands of Jobs Open— Train for One in Spare Time Right now opportunities are unlimited. The great boom in both foreign and domestic trade are crowding the railroads and the Merchant Marine to their carrying capacity. Thousands of men trained in traffic work, are wanted to direct this great flow of trade. Railroads, shippers, and shipowners are literally begging for men. You don’t have to quit your job to qualify for one of these splendid positions. Just as we have already trained thousands of others so can we train you—right in your own home, in your spare time. Traffic men of national re putation, the recognized leaders of the field, will tell you all the secrets of Interstate Commerce. The training is thorough, yet easy and interesting. The cost is but a few cents a day. Get in now! A splendid future and a quick success at a big pay job awaits Write for FREE Book Let us send you “Opportunities and Requirements for Traffic Work.’’ It is a remarkable book that ex- plains in detail this great system of training. It shows how men must be trained in traffic work. It tells all about this wonderful organization of expert traffic men who include such men as T. A. Gantt, Traffic Manager, Corn Products Refining Company; Ralph H. Drake, Division Freight Agent, American Can Co.; Samuel G. Lutz, Vice-President, Chicago & Alton Railroad, and nearly 200 others of equal prominence. They have banded together to correct the big mistakes made daily in shipping freight, that are wasting millions of dollars every year. They are giving their time to train men to right this condition. You will learn how the A. C. A. Advisory Traffic Council renders an indispensable service to the suc- cessful traffic men. Get this great, new free book now. It will open your eyes to the splendid oppor- tunities in this fascinating new profession. Mail the coupon, or send a letter now to the American Commerce Association Dept. 141, 4043 Drexel Blvd. Chicago, Illinois AMERICAN COMMERCE ASSOCIATION, Dept. 141, 4043 Drexel Boulevard, Chicago, Illinois. Please send me, without obligation on my part, your free book, “Opportunities and Requirements for Traffic Work.”’ Also tell me how I can qualify as a traffic expert. Name. ee eee RR cos easka ss se kee Occupation. 9 Soe — i 112 VV VSS WSSsses NG Seeesse ws Vows Popular Science Monthly The Neatest Mechanical Job I Ever Saw Selecting the prize-winners in the contest was a difficult task HEN the Popular Science Monthly in the early part of the year, offered three prizes, aggre- gating $90, for the neatest mechanical jobs that had ever come under the observation of the contestants, as described by them and illustrated by photographs or drawings, it was not expected by the editors that the selec- tion of the prize-winners would present Truing up a defective shaft by means of an emergency jig carrying a cutter, earned for J. Edgar Mitchell, of Hunts- ville, Alabama, the first prize of $50 great difficulty. But, when replies began to come in from all parts of the world and the material offered was looked over and sifted, it became clear that the final selection would be extremely difficult in view of the large number of meritorious answers. After carefully weighing the relative value of each point of merit, the first prize of $50 was awarded to J. Edgar Mitchell, of Huntsville, Alabama. The second prize of $25 was awarded to Myron Drachman, of New York, for the clever use of a gas-pipe and a speak- ing-tubeinconstructingacall-bellcircuit 114 He described the neat and efiicient method employed by him and another machinist in truing up the shaft by which the 150 horsepower engine jn the local power plant was di rectly connected with the generator. The engine developed a knock, and upon investigation its cause was located jn the center main bearing. It was found that the shaft was 3/32 in. out of true cylindrical form. Removing the shaft for the purpose of truing it would have consumed too much time. The prize- winner and another machinist solved the problem by rigging up the jig shown in the illustration from pieces of flat iron, pipe spacers, and a steel screw with flat iron bearings. A cut- ting-tool was clamped in the jig and John Premru, of South Norwalk, Con- necticut, earned the third prize of $15 by the neat method of providing a loose pulley for disconnecting a machine while the engine was run slowly the shaft was made true. The entire work was done in one day and a half. The second prize of $25 was awarded to Myron Drachman, of 128 West 121st street, New York, for the neat and clever manner in which he estab- lished an electric call-bell circuit be- tween the basement and the fourth floor of a house. Having ascertained that there was no short circuit between the gas-pipe and the speaking-tube, both of which extended from the base- ment to the fourth floor, he used the gas-pipe in place of one wire, the speak- ing-tube in place of the other, cor- nected the bell with the two lines on the fourth floor, and battery and push- button with the other ends of the two Jar (ary jines in co! plete the nous The t to John Connect had rigg po ible chine ¥ Parallel et a di wooden dia mete pro\ ide runs lo to in bolted ceiling. to cha pulley again ‘ Amo which several be put Month To ( . da of one 01 jealou coml desis Q) solid posit trivé with P: in. 1 one Wid 9 in of : Ss] mM wit an¢ Popular Science Monthly Januar

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lent her in ctly lhe pon 1 in und Tue aft ize- ved jig Ces teel ‘ut- and the ork ded ‘est eat ab- be- rth ned een ibe, 1se- the on- on ish- [wo January, 1921 lines in the basement, establishing a complete circuit without tearing up the house or spending money for wires. ‘he third prize of $15 was awarded to John Premru, of South Norwalk, Connecticut, who described how he had rigged up a loose pulley to make it possible to disconnect a working ma- chine withouS stopping the engine. Parallel wit’: the driving pulley and ct a distance of 14 in. he placed a wooden, home-made pulley of the same diameter, but slightly bevelled and provided with a flange. This pulley runs loosely on a pin or bolt fastened to an improvised wooden hanger bolted to one of the beams of the ceiling. A belt-shifter made it possible to change the belt from the driving pulley to the loose pulley and back again as desired. Among the entries to the contest which were not awarded a prize are several of great merit and these will be published in the Popular Science Month’y as space permits. To Make a Combination Sled and Toboggan HE boy with the sled is jealous of the boy with a toboggan and the one owning a toboggan is apt to feel jealous of the boy with a sled. This Your boy will be happy if you make this combination sled for him combination sled and toboggan is designed to furnish the two in one. One side is planked over with a solid, smooth bottom, while the op- posite side, that is, when the con- trivanee is turned over, is furnished with round iron runners like a sled. Procure two planks 5 ft. long by 12 in. wide and 1 in. thick. Taper each one so one end will measure 12 in. wide and the opposite end will measure 9 in. Round the 12-in. end in the form of a semicircle. The narrower end should then be notched as shown. Smooth the notch out round so it will resemble the back end of a sled-runner, no matter which side the planks are set on. Get your local blacksmith to make you a pair of half-round iron runners similar to sled runners. Drill these with several holes along their length and countersink them on the round thly Janu I TYs 1921 113 ARCHITECT $5000 To $15S000 Fa is ap ACCOUNTANT $7,000 TO $15,000 BUSINESS MANAGER $ 5000 To $15,000 ELECTRICAL ENGINEER $4000 10 $10,000 AUTOMOBILE ENGINEER $4000 TO $10,000 115 That is what Albert Foster wrote us eight- een months ago, and he goes on: “I’m tired of being bossed for $25a week. I wanta He-Man job with real pay. I want to get into the $100 a week class. Tell me how to do it.” We showed him how. Today he has a He-Man job and He-Man pay. We tell of his experience because it’s typical. WHAT ARE YOU? A man who is up and doing, getting real money, or are you simply marking time on $25 or $30 a week? $100 jobs don’t go begging. If you want one you’ve got to go after it. Are you satis- fied with your present condition in life? If you are, we have nothing to offer you, but if you want one of these real jobs with big pay, then we can help you and help you in a hurry. A REAL MAN with a real man’s pay is what you want to be, and we will show you how. Without loss to you of a single work- ing hour, we will show you a sure way to success and big pay. A large number of men in each of the positions listed are enjoying their salaries because of our help —we want to help you. Make a check on the coupon against the job you want and we will help you get it. Write or print your name on the coupon and send it in today. You will be under no obligation. American School of Correspondence Dept. G-175 Chicago, U. S. A, 0GD0GDe cD 0 > oc» 6 00a OGD VameameaDoe = SCHOOL of CORRESPONDENCE e Dept. G-175 ‘Chicago, Til. Qf Explain how I can qualify for position checked : 8 ee — Accountant and Au | Steam Engineer 5,000 to _ ,000 $2,500 to 37, “000 $2,000 to $4,000 e —— pa... Contract — Drafts: one n and De —. Foreman $5,000 to $10, 000 500 to $4. ‘000 mane to $4,000 Automobile. — —— Electr a ‘een ngin — Photoplay Wr 8 $4,000 to si, 000 "$4. 000 a “$10, 000 a 000 to $10,000 Automobile a ____ General Education — Sanitary En fel 500 to 34. 000 In one ye $2,000 to $5,000 —.- snteidemine .Lawye * | —Tetephone oe ngin 4 $5,000 to = 000 ‘$5 000 - — 000 | 500 * $5,000 —— Structural Enginee —Mechanical En, — Telegraph E ngineer #) $4,000 to $10, 000 $4.000 *e ry 10, 000 $2,500 to $5,000 —._ Business Manager — Shop Superinten | High School Graduate B $5,000 to $15,000 $3,000 ns ‘7. 000 In two years —_ Certified Public Acc ye —. Employment Ma ] ——Fire Insurance Expert $7,000 to $15. $4,000 ry ‘S10, 000 $3,000 to $10,000 e Name u © Address e enc ap cam coamemococmoameapemoamod

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E> ne c. G. CONN, Lt Ltd. 132 Conn Bldg., Elkhart, Ind. GENTLEMEN:—Please send me your free book and details of free trial offer of any instrument. lp OPI. scteneseckeonsss _ Instrument eRe, Bo Dolan, solo cornetist, Sousa’s and, thrills thousands nightly with his Conn. He says:** The CONN cornet possesses a rich tone, perfect scaleand IS EASY TO PLAY IN ALL REGISTERS, PARTICU- LARLY THE UPPER.” How to Master the Cornet Quickly HINK of the fascination, the opportunities for you to play in band or orchestra; travel; in- crease your income! Cultivate your musical “bump.” Take a tip from artists like Dolan and Lewis; win success with a Conn, Easy blowing, quick response, light valve action and matchless tone in Conn instruments give you quick mastery. NUNCA mum iy U Six Days’ Free Trial; Easy Pay- ments. Get all exclusive Conn features at nogreater cost. Conn instruments have won highest honors at world expositions, Send coupon for details, TTL OANA itt UD 30 cA Guarantee Bond with Every Conn glo tee 432 Conn Bldg Elkhart. Ind. , Agencies in ail large cities WORLDS LARGEST MANUFACTURERS OF HIGH GRADE BAND AND ORCHESTRA INSTRUMENTS tit Ae a KML RA deh 1th THT Ted Lewis, saxophone comedian and director of Lewis’ famous Jazz Band uses the CONN and praises its key mechanism, tuning device and other exe clusive features which make the Saxophone EASIER TO PLAY. HAUNT YWQUEUPULIV LUAU | FREE BOOK Ze@ Full of musicalin- @ formation,describes i@ allinstruments, helps you decide which you J@ want to play. Noob- —@ \igation; send cou- TUTTO PPO PEER PORTO RHEE RHEE HEHEHE EO EROS EEE OORT EEE HEHEHE BETES side. Make them long enough so the ends can be bent over and fastened to the ends of the planks as shown. Fasten one to the corresponding edges of each plank with long screws, coun- tersinking them well so they will not interfere with the smooth passage over the snow. Then place several ribs between the two planks to fasten them to- gether. These ribs are square sticks, 2 ft. long. Place them close to the edges of the planks opposite the run- ners and be sure there are at* least three of them near together at the front or curved end. At this end the highest rib should not come higher than halfway up the curve. With these in place, plank them over with \4-in. soft pine or cedar planking. Fasten these planks to the ribs and edges of the side planks with counter- sunk screws. To bend the planks up over the curve formed by the ribs it may be necessary to soak them in hot water to make them pliable. This forms the toboggan bottom. Fill with oil and sandpaper smooth. Lastly, nail several light slats length- wise across the inside surface of the ribs to act as a floor for the toboggan passengers. In this position the passengers can use the contrivance as a toboggan on soft snow. Then by turning it over, ‘it can be used as a sled on hard snow and the passengers can sit on the toboggan bottom. Bore two holes in the front of the sides for attaching the pull- rope.—L. B. ROBBINS. A Dustless Ash Receptacle for the Furnace NE of the most disagreeable features of hot-air furnaces is the dust which arises in clouds and per- vades the whole cellar whenever the accumulated ashes are removed from the ash-box under the grate. A built- in ash-pit under the furnace with a suitable out- let to the yard would remove this feature, but such pits IRON ee RECEPTACLE BUCKET The ashes are raked in the covered bin and no dust arises are rarely pro- vided except in private resi- dences built pon for your copy oa to order. The ash receptacle shown in the ac- companying illustration and patented by its inventor may be installed in connection with almost any type of hot air or steam-heating furnaces and will greatly abate the dust evil. The only structural changes neces- sary for the installation of this dust- proof receptacle for ashes are a small and shallow pit in the rear of the fur- nace, large enough to accommodate the ash-bin, and the cutting of an 116 Popular Science M onthly opening through the rear wall of the furnace, slightly below the level of the floor of the ash-box. The chute connecting the rear of the ash-box with the bin is fitted in this Opening and into the flanged spout of the bin, The ashes, instead of being shoveleq out through the door of the ash-box are pushed back and slide through the chute into the covered bin in the rear of the furnace, where they are caught in a bucket loosely fitting the bin. This bucket, which holds as much as two average coal-scuttles, can be lifted out of the bin by a handle. Save the Fingers from Injury in Sawing AWING wood with a circular saw is a dangerous task unless proper care is taken. By using a wooden finger-guard as shown in the accompanying illustra- tion, much of the danger is eliminated. 4 represents two small wooden screws with their heads cut off. The thread- ed portion is screwed into the guard, and the other part is filedtoa sharp point. These two points grip the wood firmly and allow you to put a good pressure on the saw without danger of slipping. B is a wooden hand-rest which engages the rear edge of the board that is to be sawed. “Safety first’? suggests this finger-guard for saws Cutting Steel Plates by Drilling Edgeways HE usual method of cutting cast- iron or steel plates by drilling is to make a series of holes almost running into each other, then breaking it, PI s paella, aaa a aaa. Meee a cece January, Twe on E> Alt Tl iD lone with cuit cor dled out sary I eve are gra you yo BREAK BREAK—y Eiaae | . - "USUAL METHOD EDGEWAY METHOD Cutting plates by drilling edgeways makes a much neater job leaving an extremely jagged edge to be finished off. An old-time mechanic was observed following a different method of proced- ure in cutting some cast-iron plates about 3( in. thick. They were clamped in a vise on a drill-press table and holes drilled down edgeways, two holes from the opposite sides of each plate meet- ing about the center, the drill being 23/82, thus leaving little to be broken away. Popular Science M onthl Janu y

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nthly the ‘lof hute ~box ling, bin, ‘eled box, ugh the are the Luch 1 be Ary Saw per 1 as tra- | of r ig two den ‘ith cut pad- 1 is nto and part int. WO the ut a 10ut den odge ) be ved -ed- ates ped oles rom eet- ing ken onthly Janu: 1 TY 1921 Two Great Books on Alternating Currents I Experiments with 110-Volt Alternating Currents This really wonderful book by |. D. Adams explains what can be done by the amateur electrician with the 110-volt commercial cir- cuit. It shows how the 110-volt commercial circuit may be han- dled with perfect safety and with- out involving the expense neces- sary to maintain a power supply. It is written so clearly that everyonecan understand it. There are profuse illustrations and dia- grams which show exactly how you can make these experiments yourself, The only way to gaina thorough understanding of electricity, as it is used commercially, is by direct personal experiment. The knowl- edge thus gained is of vastly more value and importance than that acquired from the performance of the stereotyped series of battery experiments so uniformly de- scribed in the text books. The many experiments described in this book were all performed at home and not ina machine shop or laboratory. The apparatus in- volved was necessarily made as simple as possible consistent with the securing of striking results. Fully Illustrated. Price Postpaid, $1.75 II Construction of Small Alternating Current Motors By PROF. A. E. WATSON Brown University This book contains complete in- structions for building small alter- nating current motors in several sizes. The designs will be found in harmony with those of the very best manufacturers and they can be worked out by the amateur for making useful instruments. Some of the subjects taken up are ‘Characteristic Features of Alternating Current Motors,” “Construction of a One-Half Horsepower, Single Phase induc- tion Motor,” ‘‘Procedure in Test- ing and Using an Alternating Current Generator or Synchron- ous Motor.” Clear, concise directions and careful drawings are features of this book. Fully Illustrated. Price, $1.50 Popular Science Monthly 225 West 39th Street, New York The Roll-Top Desk Used as a Drawing-Board OW often have you, when at work on a roll-top desk, wished for a small drawing-board for making plans? One day, quite by accident, I thought of the plan shown in the illustration. Why not pull out the slide and make a small T-square to fit it? No sooner thought than done, with the result that the little T- square, with a small 4-in. tri- angle, made an ideal sketching outfit, at hand at all times. An improvised drawing-board like this is particularly convenient for draftsmen who wish to work at home, but have not room enough for a drafting-table-—J. W. MOORE. The slide of a roll-top desk will make an excellent drawing - board Eliminating Rattles from Automobile Doors N automobile which has run a year or so usually develops an annoying door rattle. This is because the body has become worn and gives with every jolt from the running gear. Use a _ piece of l-in. L-iron 3 in. long, with holes drilled as shown, and riv- et on a piece of \%-in. clock spring. If the steel is too SCREW HOLES hard, heat it This little device pre- 22 d bend it, cooling it quick- ly to restore its temper. Coun- tersink the wood screw holes and file down all edges smoothly. Screw this device to the body so that when the doors are closed the springs are about flat and, of course, under tension. As the door is closed the spring receives the impact gently and keeps it tight.—P. P. AVERY. vents your automobile doors from rattling A Hot Garage Will Injure Your Car HILE it is, of course, most ad- vantageous to heat the garage by some means or other during the cold months, there is another extreme that should be avoided. We refer to keeping the garage too warm. If the heat is too irtense, the sudden change of temperature when the vehicle is taken out into the cold air, or when it enters the overheated garage after having been in the cold, is apt to cause the varnished panels to check and fine cracks to appear in the finely January, 1921 finished varnish coating of the body. 117 New Invention Shows How to Write and Speak Masterly English ET us send you, absolutely free, a copy of our new iliustrated book, ‘‘How to Write and Speak \.asterly English.’’ You will be glad you wrote for this book, no mat- ter how much or how little you may know about the English language and its proper usage in your business and social life. This book, sent free, is for the employe and employer, for stenographers, bookkeepers, authors, correspondents, clerks, credit men, typists, lawyers—in fact for everyone who really wants to make a habit of using correct English. Write today for this book. New Invention Takes Only 15 Minutes a Day Yes — only 15 minutes a day with Sherwin Cody’s New Invention — and you can actu- ally SEE how your English improves. ; mp The mechanical drudg- ery is eliminated, No rules to memorize. Mr. Cody is perhaps the greatest and best known teacher of business English in the country, This new patent is the result of 20 years’ experience and takes the place of a teacher at your elbow. Whatever work you do your English ‘‘makes or breaks’’ you. Incorrect spelling, punctuation, pronuncia- tion or usage, or the use of flat, ordinary words handicaps you in business and among your friends. You can improve your English now in 15 minutes a day, in spare time. Make words WIN for you. Sherwin Cody’s New 100% Self Correcting Method The average person in business or at school is only 61% efficient in English. Mr. Cody's method teaches you from the ground up. Old methods do not stick in the mind. Mr. Cody’s new invention teaches by HABIT makes it EASIEST to do it in the RIGHT way. Lessons include Letter Writing, Spell- ing, Punctuation, Grammar, Reading and Conversation. One lesson each evening ex- cept Saturday and Sunday. Only 15 minutes aday. And so simple is the new Invention that you see at a glance your errors and note every day your improvement. Every time you speak or write you show just how much you know. Lack FREE! of language power may easily be cost- ing you thousands of dollars every year. See what Mr. Cody can dofor you. See what afew minutes a day NOW will mean to you later. It costs nothing to find out. Mail the coupon ora postal card this very minute for the free book ‘“‘How to Speak and Write Masterly English.’ It will prove a revelation to you. WRITE NOW. Address Sherwin Cody School of English 181 Searle Bldg. ROCHESTER, N. Y. SHERWIN CODY SCHOOL OF ENGLISH 181 Searle Bldg., Rochester, N. Y. Please send me your Free Book, ‘How to Write and Speak Masterly English.” Name Address

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oremen an uperintenéents Sy _ saat ee Learn to Fill BIGGER Shoes! O matter what kind of work you are doing now, a set of these great home study books will quickly fit you for a bigger and better paying job. We will send any set you select for one week’s free ex- amination, and if you want to keep them you pay only the special reduced price, at the rate of 75 cents aweek. This is your opportunity to make more money—grasp it NOW Use these books and a little spare time and LEARN TO FILL BIGGER SHOES. Pay-Raisin$é Books at Greatly Reduced Prices Accountancy and Business Management, 7 vols., 2700 pages, 1000 pictures. Was $52.50. Now $29.80 Carpentry and Contracting. 5 volumes, 2138 ¥ Now pages, 1000 pictures. Was $37.50......... 24.80 Civil Engineering. 9 volumes. 3900 pages, 3000 pictures. Was $67.50..............Now 39.80 Electrical Engineering. 8 volumes, 4100 pages, 3300 pictures. Was $60.00.............. Now 34.80 Automobile Engineering. 6 volumes, 2600 pages, 2000 pictures. Was $45.00........ Now 29.80 Machine Shop Practice. 6 volumes, 2300 pages, 2500 pictures. Was $45.00........Now. 29.80 Steam and Gas Engineering. 7 volumes, 3300 pages, 2500 pictures. Was $52.50..... .Now 29.80; Law and Practice. (with reading course), 13 volumes, 6000 pages, illustrated. Was$97.50. Now 49.80 Fire Prevention and Insurance. 4 volumes, 1500 pages, 600 pictures. Was $30.00.....Now 19.80 Telephony and Telegraphy. 4 volumes, 1728 pages, 2000 pictures. Was $30.00........Now 19.80 Sanitation, Heating and Ventilating, 4 vol., 1454 pages, 1400 pictures. Was $30.00....Now 18.80 Drawing, 4 volumes, 1578 pages, 1000 pictures, blue-prints, etc. Was $30.00 ............ Now 19.80 Send No Money Shipped for 7 Days’ Trial Write the name of the books you want on the coupon and mail it today. We will send the = books at once, express a collect, and you can use : them just as if they were your own for a whole week. If you decide you don't want to keep them, send them back at our expense. 75c a Week If you like the books, as thousands of other men have after examination, just send us $2.80. You can send the balance of the special reduced price thesame way—$3.00each month (75 cents a week). Start right now and learn to fill bigger shoes. There will be a better job look- ing for you if you do. Be ready to meet it when it comes. Send the coupon now. American Technical Society Dept. XX-201 Chicago | American Technical Society, Dept. XX-201, Chicago, U.S.A. l | Please send me set of ... for 7 DAYS’ examination, shipping charges col- | lect. I will examine the books thoroughly and, if satisfied, will send $2.80 within 7 days and $3 each month until I have paid the special price of | is cs eee ae If I decide not to keep the books I will return them at your expense at the end of one week. Title not to pass to me until the set is fully paid for. | EE Oe Pn ee ; em ee ee 110 An Electric-Alarm Trap for Ice Fishing HE glare of an icy lake becomes very tiresome to one watching the red flags of fish-traps on a sunny day. To relieve this condition, the trap herein described departs from the visual signal and gives warning of a hooked fish by an electric bell. It is just as simple to make as the “tip- ups,” and will give an unfailing alarm. It is a good plan to fit each stick with a bell of a different tone and to place them at widely scattered points about the lake. Their tones can be soon dis- tinguished and the fish pulled in. The stick is a piece of straight grained wood, 24 in. long, 2 in.- wide, and % in. thick. Point one end so that it can be inserted easily in a hole chopped in the ice. At the other end screw two spring brass clips, with just enough tension so BELL BATTERY CLP > WIRING DIAGRAM PEG INSERTED BETWEEN cups |) TRAP IN POSITION — — If you use one of these traps, you may safely take a nap between bites they will give a firm contact, but not so tight that they cannot be easily forced apart. About midway down the stick mount an old flash-lamp tube with both ends removed. Set the cellsin the tube and screw asmall contact of brass to the stick at each end of the tube so they will hold the cells firmly in place. Fasten the tube to the stick by two bands of tin. A small electric bell should then be mounted on the stick directly below the battery. The wiring diagram is shown in the detail illustration. Tie a small piece of sheet rubber or fiber to a string and suspend it from the side of the stick. This is placed between the battery and contact at A when it is desired to break the circuit. Paint all the wiring, battery tube, and other exposed parts requiring it, with two coats of shellac. Tie the fishing-line to be used to the lower part of the stick and provide a small piece of hard wood, shaped like a sinker, which can be slipped along the line to determine the distance the line will hang from the clips. Set the stick in a small hole in the ice alongside the fishing-hole. Water 118 Popular Science M onthly and ice chips around the stick will freeze and hold it solid. Place the wooden peg at the Proper point on the line and place it between the clips. Remove the fiber contac. breaker from the battery and let j hang. When the fish takes the bait anq runs with it, it will pull the peg frop, between the clips. This completes the electric circuit and rings the bell, The fisherman pulls in the fish rebaits his hook, and resets the alarm, removing the contact-breaker before leaving.—WINDSOR CROWELL. Filing Shafting in the Lathe Becomes Easy HAFT-FILING can be accom. plished in more ways than one, The usual hand method is tiresome, to say the least. Having a number of shafts to file we rigged up the device shown in the illustration. We placed a block, A, at the rear end of carriage, anda board, C, in the position shown. Then we connected both with a leather hinge, as illustrated c ~ ie TAILSTOCK Under the — Fiting shafting made les board C we tedious by this impro- placed two vised jig small pieces, D and E (see enlarged view), and into this we slipped a piece of a file. The rest is self-apparent. We merely pressed on the end of the board C, put in the carriage feed, and the file traveled along the work. A Florence Flask Made from an Electric Lamp ANY of the incandescent lamps now being manufactured are of the “‘tipless’’ variety; that is, they are free from the sharp point on the glass which was necessary in exhausting the air from the globe. Such lamps can be made use of, after the filament is burned out, toformround- 7 linia dil bottom flasks conomical chemists make ; Florence flasksfrom burnt- for use in the out lamps. laboratory. It is the work of only a few seconds to file a scratch around the glass near the small end, and to break off the globe at this line. The edges are readily rounded off by holding in a flame. TIPLES Popular Science M onthly January: An \ B ‘¢% cal b work ploye opera the b cause jrons The cuttin Tw venie jron, fectly these dista cente same The | over pies pea per to ber pla abc ang pla to wil Opt an en no pe 3t¢

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TOper CWeen ntact. let it t and from eS the fish larm, efore athe coms one, some, 0 file n the 1 into We board 1e file rom amps are of “y are glass was y in sting from ye. amps made after ment d out, ound- flasks n the ry. the file a small t this inded Jan uarTYys 1921 An Efficient Bench-Stop for Boards BENCH-STOP, for holding boards {[ \ to be planed on the edges, which can be easily made and which does the k better than the kind usually em- ployed, is shown in the illustration. In operation, the board is pushed against the bent ends of the angle-irons. This causes the levers to swing and the angle- irons to close tightly on the board. The bench-stop holds tighter as the cutting pressure becomes greater. Two pieces of angle-iron of any con- venient size are provided —1-in. angle- iron, about 4 in. long, will answer per- fectly for all general purposes. One of these irons is cut out on one end for a distance of about 1 in., and from the center down. The other is cut in the same way, but from the center up. The overhanging sections are then bent over toward the flat side, so that the SCREW PLATE TO BENCH LEVER ARM BOARD Guided by these drawings and the text, the amateur carpenter will be able to make a bench-stop like this pieces viewed from the end will ap- pear as shown in the end view. This permits the flat sides of the two pieces to be brought together without the bent ends touching each other. The plates screwed on the bench should be about 1 in. by 4 in. by 4 in. The angle-irons are fastened to these plates by levers so that they are free to swing. The levers should be about 4 in. by 34 in. A length of 214 in. will give the stop about a 4-in. Opening. This stop holds the work firmly, and even when planing the opposite ends of long boards, the ends can- not swing around as sometimes hap- pens with the usual type of bench- 3top.—R. H. KASPER. Most Paints Are Improved by Zinc Oxide JYAINT in which suitable propor- tions of zine oxide are used covers more surface than lead alone, accord- ing to leading paint technologists. Zine oxide also imparts toughness to the film, reduces chalking, gives the coating improved luster, preserves the oil, and lessens the danger of fading. January, 1921 117 of students and graduates 8 Dobe salary. I train you onally. Drafting Tools = Trained Until other graduates are loing. I give you practical drafting room work. Everything just exactly as you would get it in a real job. I give you my personal man-to-man attention. And I train you until fnow get the full meaning of this) un: ‘ you are qualified and experienced as a first class draftsman and until a" ina permanent — seine Send Coupon forF ree Book You Get Job That’s My Offer-- TUPENDOUS! That’s the word for this greatest—most magnificent Drafting offer! I know how far my offer leads all pothers, t puerantes every word and my pundrede be backs up a I make you qualified to draw $3,600 per year like scores of my Chief Draftsman y aeyeye) | his promises. First about that $3,600 first lass draftsman’s salary And more—I give you a whole set of drafting tools the minute you become my student. You get every tool re need. A magnificent $25.00 set of instruments with which to build your success in draftsmanship. Remember—the draftsman goes bs and up to the fabulous incomes of engineers and architects. Chief Draftsman Dobe Dept. 1361, 4001 Broadway, Chicago Without an obligation whatsoever, please mail your ok, “Successful Draftsman- ship”, and full particulars of vour liberal “Personal Instruction” offer to few students. No matter what plans you have for the future. Get this great book—‘‘Successful Drafts- manship’”’. Find out about the simply marvelous opportunities ahead now. How the world needs draftsmen; enginéers; architects and _ builders. What great salaries and possibilities there are! Name... Send coupon for my free book today. Chief Draftsman Dobe Dept. 1361,4001 Broadway, Chicago, Ill. . .* How to Become a Successful Electrician By Pror. T. O’'Conor SLOANE. The studies to be followed, methods of work, field of operation and the requirements of the successful electrician a pointed out and fully ex- plained 202 pages. Illustrated. . Price, $1.50 Popular Science Monthly - 225 West 39th Street, New York. Power Benders THREE NEW MODELS “*COLD"’ Pipe Bending Ma chines (pat.) electrically oper- ated to bend from : 8 inches. Send for printed mat- ter. We also manufacture TEN other sizes, hand operated to bend from 1-8 to 6 inches. American Pipe Bending Machine Co, FOUNDRY FACILITIES AVAILABLE Large manufacturing plant in Cleveland, well organized and equipped for Mac chine Shop, Pattern Shop and Foundry pro- duction, will consider converting part of its production capacity to some manufacturer upon a low cost produc- tion basis. This is an ideal opportunity for manufacturer wishing Cleveland factory connection with a well organ- ized plant. Address replies in care of THE NESBITT SERVICE COMPANY Caxton Building, Cleveland, O, Manufacturers—51 Pearl Street, BOSTON, Mass.. U. S. A. ADDITIONAL MACHINE SHOP AND 119 Selling Eagle Sawing Machinew Every timber owner needs one, Pow- erful,fast-cutting, saws the natural way, Adem- onstration sells it. Representatives making from $80 to $300 a week, $2.00 An Hour You can make Bawing wood while demon- stratin Write today for fou = formation and Spec- gent’s Prices. , a Machine Co Dept. 482, Kansas City, Mo. INSURE YOUR MEASUREMENTS Stocked by Dealers—Send to us for Catalog No. 12 THE [UFKIN fpuLe C0."*ien”

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In the largest factories in the smallest machine shops— wherever lathes are used— Monarch Lathes are found. Built right of the very best material —designed to meet all conditions in lathe work— Monarch Lathes deliver per- fect work of the most minute accuracy and give long time service. Moderately priced because they are built in quantity. Guaranteed to give satisfac- tion to the purchaser. Write today for catalog and full information of Monarch Lathes. The Monarch Machine Tool Co. 108 Oak Street Sidney, Ohio a est my Bios Electricians’ Knife and Tweezers We can meet dealers’ demands at once and offer attractive quantity prices Write for description MATHIAS KLEIN & SONS, Mfrs. CANAL STA. 3, CHICAGO \ “Lighting Fixtures” ‘\ gnting t Ready to hang. { Direct from manufacturers. , Completely wired including glass- \ ¢ @ ware. a > L Send for Catalogue No. 20 r ; ERIE FIXTURE SUPPLY CO. ' ” Desk A, Erie, Pa. Self-Taught Mechanical Drawing ed Elementary Machine Design By F. L. Syv_vester, M.E. A practical elementary treatise comprising the first principles of geometric and mechanical drawing, workshop mathematics, mechanics, strength of materials and the calculation and design of machine details. 330 pages, 215 engravings..........cceeeeees Price, Popular Science Monthly - 225 West 39th Street, New York 118 Fighting Snowdrifts with an Automobile Plow F you live in the country or in the suburbs and do not wish to be marooned by every snowstorm, get a snowplow like that shown in the ac- companying illustrations, provided, of course, that you are the fortunate | possessor of an automobile of some With this snowplow attached to their car suburbanites need not fear a snow blockade kind to which you can attach the plow. The drawing clearly explains the construction of the plow, which is the invention of Claude C. Hyde, of Otisville, New York. The plow consists of two side parts, placed directly in front of the front wheels, and a V-shaped middle part. The wheel plows are supplied with shoes or runners, which keep it from digging into the roadbed and are yieldingly attached with spiral springs so they may pass over rough places or obstacles in the road. The middle plow may be raised or lowered so as to take as much snow WHEEL PLOW RUNNER OR SHOE ee Pe ae See, Re a Ga api ae. RR The plow attachment can be easily disconnected when it is not needed from the road between the wheels as the power of the automobile engine will permit. When the plow is not needed, it may be removed in a few minutes and without the use of special tools. One Way of Removing Dents in Wood NSIGHTLY dents in woodwork of almost every description can be removed easily by the following simple method: First thoroughly sponge the dented part with warm water, allowing it to 120 7 a ee Popular Science M onthly soak well into the wood. Then take a piece of brown wrapping-paper, fold it into half a dozen thicknesses, anq after soaking well in warm water, lay it over the dent previously sponged. The treatment is completed by ap. plying a hot flatiron until ail the moisture is evaporated. For dents of ordinary depth, one application is usually sufficient to raise the dent level with the surface, anq the worst case; will yield to this treatment if repeated two or three times.—GEORGE H. HOLDEN. Methods of Keeping Carbon Out of Bolt-Holes HEN cleaning carbon out of an engine with the cylinder head of, carbon will get down into the bolt- holes holding the head unless some precaution is taken to keep it out. Carbon in bolt-holes means a loss of time, especially after the gasket and head are assembled. Two simple CARBON FLOATS. Filling the _ bolt. FACE holes with water will prevent them from becoming filled with carbon WATER FASTENER Another way to keep bolt-holes free from carbon con- sists of inserting long paper-fasteners CARBON methods are suggested for the pre- vention of this or they may be com- bined. Fill the bolt-holes with water and the carbon will float on top of the water and can be blown off with the breath or the tire pump. The second method is to drop paper- fasteners into each hole with the points up. When the paper-fastener is pulled out the carbon which has dropped in comes out too.—G. A. LUERS. To Keep the Teapot Cover from Falling Off OW often has the china teapot cover fallen off, overturned a cup of steaming tea, and ruined the table-cloth, just because the cover had not been watched? But why watch the cover at all? Chain the cover down and it will not cause any accidents. Such a cover guard consists of two short chains and three rings. ‘The first is a closed ring and must fit loosely over the spout of the teapot. A chain just long enough to reach to the knob at the center of the cover is attached to the ring. The free end of the chain is provided with an open, flexible or spiral ring which fits around the stem of the knob. A second chain is attached to this ring and is cut Janue off so of the attack This 1 fits a pletes Ins of th slippeé the | the cc the | is § arou hand this in p! teapc will r nor The shou and | bras: chail mate moré¢ usef Hi i are thri cons Thi: the A is b one the met Popular Science Month, Og ee a Janu _ ~ =

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January, 1921 off so that it just reaches the handle | a | aa of the pot. The third and last ring is and attached to this end of the chain. r, lay This ring is also open and springy and ed, fits around the handle. This com- Y ap. pletes the teapot-cover holder. | the Insert the closed ring over the spout of the teapot. The middle ring is One slipped over raise the knob of and the cover, and this the last ring three is slipped around the handle. When this guard is oon in place, the teapot cover will not fall off f an nor slip off. Ring chains like this off, The chain may prevent a smash olt- should be thin ome and not clumsy, and if it is made from out. brass, so much the better. Make the loss chain and the rings from uniform and material, then the effect is so much Aple more pleasing and will combine the useful with the esthetic.—E. BADE. alt. Heating an Aquarium for ater e e hem Tropica. Fish ing bon ROPICAL fish require a tem- perature of at least 60° F. If they are kept in an aquarium, they will not thrive unless the water in the tank is constantly held at that temperature. to This condition may be maintained by free : 4 aes, the use of a simple heating apparatus. ing A metal tube, preferably of copper, ers is bent in the form of a U, but with one arm at least one inch longer than 119 the other. Two holes are cut in the re- metal bottom of the tank, into which m- ter > he , —ogl WA he 24 RQUARIUM = er its Vy ed in | | WY] Lil’ “ This heating apparatus will make a the aquarium a fit abode for tropical 1e fish during cold weather er y the two arms of the bent tube are le fitted and soldered. The curve of the y U should be at least one inch from the bottom. 0 The tank is raised by blocks of le wood, so that a small alcohol lamp or it a Bunsen burner may be placed under t. the curve of the U. It is best to place 0 the lamp nearer to the longer arm of IS the U. The water in this tube, as d soon as it becomes warm, rises to the ly surface. This causes the cold water to sink in the shorter arm of the tube. As it becomes heated it rises again, it and in this manner constant circula- January, 1921 | | Our new trade mark! cAnnouncement HE purchase by TheStanley Works of the Stanley Rule and Level Company will enable us to serve you in the future even more efficiently than in the past. For more than 70 years the two - Stanley Companies have been build- ing steadily towards one end—to make the name STANLEY a mark of de- pendable quality in Wrought Steel Hardware d Carpenters’ Tools A new trade mark as here shown has been established as the result of this merger. The combined experience and facilities of these two great companies will hereafter be devoted to maintaining and increasing the service represented by the name STANLEY. THE STANLEY WORKS Main offices and plants: NEW BRITAIN, CONN. Branch offices: New York Chicago Los Angeles San Francisco Seattle Pe ee RS A eee ee ge ET ee ee SE Say 121

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Pies ee } eit Metallurgy and Drop-Forgings N former days, the skill of the individual workman was almost the sole dependence in the production of drop-forgings. But foryears past, to supplement with scientific knowledge the craftsmanship of their operators, Williams have maintained com- plete chemical and physical lab- oratories in charge of an expe- rienced metallurgist. He selects the materials and prescribes the methods and temperatures to be used in manufacture. He knows, definitely, what results to expect; his laboratories tell him accu- rately whether or not they have been obtained. Individual skill, backed by scien- tific knowledge, has made Wil- liams’ drop-forged machinists’ tools—Wrenches, Tool Holders, Lathe Dogs, Clamps, etc. Superior. J. H. WILLIAMS & CO. “The Drop-Forging People” BROOKLYN BUFFALO CHICAGO 7 Ricuarps Sr. 7 VULCAN Sr. 1007 W. 1201rn Sr. WILLIAMS’ ‘* AGRIPPA”’ TOOL HOLDERS For all regular machining operations Ask for Machinists’ Tools Book tion is established and an even dis- tribution of the heat through the whole tank. The temperature is regu- lated by a thermometer and the size of the flame under the heating-pipe. During the winter the tank should be covered with a glass plate to ke2p the water at a more uniform tem- perature. Do You Bump Garage Doors with the Mudguards? ERY often you can identify the fellow who keeps his automobile in his own garage by the condition of the fenders of his automobile. They are bent down somewhat, or dented, and otherwise disfigured, because in driving in or backing out of his garage he has a habit of misjudging the dis- rs, x Dr mc UV RORNBNR Slanting guides at the garage door will protect the fenders from injury tance between the fender and the door- jamb, and before he can stop moving, the fender has been made to suffer. Where the doorway is none too wide —a natural condition with the city man’s garage, since usually he cannot make it any larger than necessary to barely squeeze the car in—it is a good idea to install guard rails in the corners of the door opening or little concrete or wooden guiding-blocks. If a piece of husky piping is attached at each corner it will serve as a guard against which the tire will strike if the auto- mobile is run too close to the doorway. This will either have the effect of pushing the au.omobile over away from the side of the door, or it will offer enough obstruction to the forward movement of the automobile to warn the driver in time to change the auto- mobile’s position. Obviously, these diagonal pipes would only be of ad- vantage when entering the garage, | being of no service when backing out. The concrete or wooden blocks, however, are intended as backing-out protection, serving to guide the wheels in the path they should follow in order to clear the doorway sufficiently. They are of no special advantage when entering the garage, being opposite in their function to the diagonal pipe fenders mentioned above. 122 Popular Science Month, How to Test Rubber Rings for Preserve-Jars UBBER rings used in canning or preserving may be tested hy simple methods. Cut a 6-in. piece out of a ring and, taking hold of t}. ends so tha’; 4 in. remain between the fingers, stretch the piece along a ruler until the fingers are 10 in. apart When released, the sample should ro turn to its original length and shou'd not break. Another method of testing is the following: Fill a light weight paii with 1 gal. and 7 pt. of water, or the equivalent of approximately 17 lbs. Place the jar-ring around an empiy spool, then pass a wire through the center of the spool and fasten to the handle of the pail. Pass a broom- handle through the ring and lift. [f the ring does not break, there is not much danger of its giving trouble in canning. A Detachable Crane for Use on the Truck OW to avoid the necessity of employing an assistant to the truck-driver for loading and _ un- loading heavy and bulky goods is a problem of which the detachable crane shown in the accompanying il- lustration offers an inexpensive solu- tion. This hoist is not permanently at- tached to the body of the truck and can be removed easily when it is not With the aid of a detachable crane on his truck the driver can do the loading and unloading without a helper needed for handling heavy freight parcels. The main support of the crane is a heavy pipe, which is held in a vertical position by two brackets bolted to the end of one of the side boards of the truck. The pipe is held at the proper height by a supporting pin which rests on the upper bracket. The upper part of the pipe is curved in the shape of an S and has at its end a vertical pin which forms the upper pivot of the crane. The crane is also made of heavy pipe and is bent as shown in tke accompanying illustration. The end of the upper arm is flattened and provided with a hole into which the Popular Science Mont); 2 | A Butt-Hinge Serves as an | boot will cling closely to it and seem :,, ”"* January vertical fits. slightly stud of lower fF pivoted which © attache A Ha HI al a temf accura two pit with tl] Hav such V everyt GREEN Cl larg Thi Janu Lan

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January, 1921 vertical pivot pin of the main support fits. The end of the lower arm is slightly bent and fits over the center stud of a flange-plate which forms the lower pivot. To the elbow of the pivoted crane the hoisting tackle, which may be of any suitable type, is attached.—G. A. LUERS. A Handy Templet Stand for Accurate Work HE making of templets has been, and always will be difficult, for a templet, to be of any use, must be accurate, expecially when it is made of two pieces, one of which must coincide with the other. Having found it difficult to hold such work to the light to ascertain if everything was as it should be, we REEN C H ; G : EN CELLULOID SHADE. AIR HOLES

REFLECTOR AND BULB tempter ee | )

You will save your eyes and insure greater accuracy by using a templet stand like that shown here constructed the stand as shown in the accompanying sketch. The stand was made of wood. In action we placed the pieces to be fitted on a little shelf in front. In the rear was an electric light and a reflector. A shade, made from a piece of green celluloid, relieved the strain on the eyes. Near the top were air holes, so that the heat of the light would not injure the wood.—J. H. MOORE. Conquering that Stubborn Automobile Hub-Cap OMETIMES it is very difficult to remove the hub-cap, even when a large wrench is used for the purpose. This is usually due to water which found its way to the threads of the cap and formed rust. In that case, make use of the jack as shown in the illustration. Procure a long - handled wrench so as to obtain greater leverage, and place the jack under the end of the handle. A few sirokes of the jack will start the most stubborn hub-cap. This method is equally successful with big trucks, using the jack furnished with the truck.: When removing wheel-nuts, you should bear in mind that the nuts have right-hand threads on the left side and left-hand threads on the right side of the hub.—R. L. PRINDLE.

A long-handled wrench and a jack form a pow- erful combination January, 1921 7 < — eshtiah | Sn tha narhiuiratar

aa.

Oda Speme ag 6 Ake x end sizes, ous Ran , Pieyceay 8 sive fer .. at ee. on, epDreral e ‘Sive $10 to $25 on your bicycle. soon tjeral Baer, Barmant pio, Earssig vy ni . en! i first di it. En ic boys ‘N the small monthly payments thereafter. — Bp Ne aF€S Cecmone atta wean ees LD) WARE) Bete Sunrvelous prices sod terme, 1} \ x NIN) Mead ‘Sc, company ae ) $6000 a Year is Your Profit WY from four sales a day, No experience needed, Largest concern of its kind in the world. Davidson sold 96 in one week, Flynn 72 in three weeks spare time. Boyce 25 in one evening. New Aladdin light is asensation wherever introduced. Five times as bright as electric. Won Gold Medal. Approved and used by U. 8. Gov- ernment. Endorsed by 35 leading Universities. Farm- ers have the ener, they need this light, and 9 out of 10 willbuy. Also big opportunity in small towns and suburbs. Excellent spare time and evening seller. NO CAPITAL REQUIRED, Sample on free trial. Write for agency proposition and exclusive territory. M.O Johnson, Sales Manager, 609 W. Lake St., Chicago

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. Owners of the world’s largest Asbestos Mines Pilliod \ Vi TOOL CASES EXCEL

—\ Machinists, Tool Makers and Carpenters find them most satisfactory in construction, appearance, service and price, Immediate shipment. Booklet describing 20 styles on request. The Pilliod Lumber Co. Dept. A, Swanton, Ohie

LATEST OUT Log and Tree Saw NOW you can get the latest WITTE Arm Swing, Lever Controlled, Force Feed Log Saw for sawing up logs any size, Movés like a wheelbarrow—goes any- where—saws up-hill, down-fill or on level. Cuts much faster than former rigs. Oper- ated by a high power, frost-proof WITTE 4.-Cycle Engine Costs only 25 to50 cents a day to oper- ate. Double the powerneeded for saw- ing logs ortrees. Perfectly balanced rig- Can be used for belt work. New WITTE Tree Saw At low cost additional can TYE Tree

2226 Empire Bldg., at ~ EE t For this Complete Log Saw F. O. B. Kansas City, Mo. From Pittsburgh,Pa., add $6.80 Don’t buy any Log Saw, Tree Saw or Buzz Saw Outfit until ou have seen the new WITTE. west priced Guaranteed rig on the market. Cuts much faster than for- mer rigs. On tests we cut 2-ft. log in 90 seconds. Treesaw cuts ’em close to the ground. Goes anywhere. We are making a special advertising price NOW—So write at once for complete description of this wonderful outfit FREE. BRANCH SAW $23.50. WITTE Engine Works 2226 Oakland Ave., Kansas City, Mo;/ Pitsburgh, Pa.

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Always Experimenting for Production -gains The true mechanic never finishes with developing his machines; in process or in service hes making them befter producers—-as Veeder Counters register his progress. Veeders count the product as your machines work; show the production-rate over a given period; record the effects of changes in mechanism or oper- ating method. You get the measure of your machine and the data for its further development, when a COUNTER sets before you the exact result of your experimenting as you go along. t The above Revolution Set-Back Counter records the output of any machine where a shaft revolution indi- cates an operation. Sets back to zero from any figure by turning knob once round. Supplied with from four to ten figure-wheels, as required. Price with four figures, as illustrated, $10.00 (sub- ject to discount). Cut less than one half size. This small Rotary Ratchet Counter (No. 6) counts reciprocating movements , of the lever, as re- - quired in record- wage ing the output of punch presses. | When the lever is moved through an angle of 40 to 60 degrees, the count- csi hail er registers one. A complete revolu- tion of the lever registers ten. This counter is adapted to no end of small machines, simply by regulating the throw of the lever. Price, $2.00. (Cut nearly full size.) e ‘\itiieoninne, NOOO Veeder Counters for every con- ceivable purpose may be seen in a booklet, “Checking Up Produc- tion.” Write if you haven't a copy. The Veeder Mfg. Co., 44 Sargeant St., Hartford, Conn. A Butt-Hinge Serves as an Improvised Vise HOWN in the illustration is a small clamping-vise that can readily be made from a 4- or 5-in. butt-hinge, and is serviceable for holding elec- trical parts, pins, keys, etc., while filing or fitting. The hinge is screwed to the edge of the bench or any projecting beam. STEEL ROD THREADED AND BENT LOCKE D NUTS LOOSE NUT SUNK IN WOOD SCREW HINGE = |}. | Y----=-- TO BENCH How a butt-hinge can be made into a serviceable clamp vise is illustrated here The ecges are bent by inserting a piece of steel between them and ham- mering. A bent and threaded rod with three nuts is the means of closing the jaws. This fixture is made up ina few minutes and is serviceable for the odd light jobs about the automobile shop.—G. A. LUERS. Save the Tires by Using a Laced Boot HE tire is one of the weakest features of the automobile. A small puncture may cause a blowout; a sudden stop may produce a weak place in the tread. Usually the shoe that is discarded shows a thin spot 6 to 18 in. long, while aside from this it is in good condition. You can make a durable lace-on boot that will stay if put on according to directions. This will prevent further wear of the weak part TIRE and lengthen = tige SectION >= the life of the 2” LARGER tire. ‘ To make the lace-on boot, secure a portion of another tire, | — preferably A laced boot will pro- one that is long the life of any in- two inches jured tire larger in di- ameter. Wet it, and with asharp knife slice off the beads or clinchers and an inch of the side adjoining. Then with a belt punch make clean holes every three inches.- Pass a good belt-lace through these holes and lace the boot over the worn part of the tire. When the tire is inflated, the lace-on 124 Popular Science Mont)!: boot will cling closely to it and seem + be a part of it. If the shoe is in good condition . cept in one weak spot, wash this \ |] with gasoline, spread it with ligyid rubber cement. Let this dry, and -;e- peat. Next lash on the boot prepared on the inside in the same manner :ind the heat generated by running \ ll vuleanize the two together. This js especially desirable in a Criving-whee] tire. HOLLISTER SAGE. Keeping the Carburetor in a Good Humor UCH has been written about the difficulties of carburetion under normal conditions, when the engines under consideration are in good shape; but the difficulties are even greater in the case of engines that have been used for a long time. Some of the common complaints are of the so-called “galloping engine's” inability to throttle to a low speed and an unaccountable missing or skipping. Air-leaks diluting the gasoline va- pors are the foremost causes of irregu- lar action. Seldom does the air leak LEAKAGE OF AIR _CARBURETOR VALVE (})| Se cca hg (A AROUND INTAKE VALVE Ta CMON” AL Ud) i HOT AIR TUBE FROM EXHAUST TO CABURETOR., NEEDLE VALVE ADNED BUSHING Air-leaks in the carburetor and the intake valves make the engine miss fire through a loose gasket, but the hole through which the stem of the throttle valve protrudes, due to wear, pro- vides an air leak that should be remedied. Take the lever off, bush the hole with the shell of a rifle cartridge or similar piece of tubing to keep the air penetrating at this point. Now re- move the intake valves, discard the exhaust valves and use the intake valves in their place. Purchase new intake valves and if these do not fit the holes snugly, ream the extreme ends of the valve guide and place a copper or brass bushing at each end or entirely through if desired. Fit a small grease-cup and use a graphite grease, and the leakage of air at this place will be overcome. Re- move the piston-rings and fit new ones with lapped ends that will effectively stop all leaks at this place. The next January, change is modificat ent make atomize t to rest ric spraying In sor tube is l and bush solder tc ject is t give to greater \ no prehe With the but closed | opening its fuel, of the i opening sufficiel will no’ skippin cases.— Th Popular Science Monthly

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- ll —S ew ee ee CG January, 1921 change is in the carburetor, which modification will vary with the differ- ent makes. To make the carburetor atomize the fuel better, it is necessary to restrict the opening surrounding the spraying needle. In some carburetors a removable tube is used which can be taken out and bushed or given a heavy coating of solder to close the opening. The ob- ject is to narrow the opening and to give to the stream of entering air greater velocity. If the carburetor has no preheater, one should be added. With the carburetor removed, push the butterfly throttle valve to its closed position and note the small opening through which the engine gets its fuel, which will give you some idea of the importance of closing the small openings that give a combined area sufficient to dilute the mixture until it will not burn, which accounts for the skipping of the engine in many cases. GEORGE LUERS. This Burning-Glass Is a Piece of Ice UPPOSE you go fishing some cold day and find that you have no matches with which to start a fire— what would you do? If you have a jackknife with you and can find a piece of nice clear ice about 1 in. thick and 4 in. across, you need have no cause for worry. Carve out a roughly shaped double convex lens somewhat like thestyle shown in the sketch. Then rub it between the palms of the hands until the bodily heat melts away the roughness and it assumes a smooth surface on both sides similar to a glass lens. By focusing the rays of the sun on a bit of tinder, such as dry wood, pith, paper, etc., a flame can soon be produced that only needs to be fanned carefully and fed with combustible material to yield a good fire. If it is desired to use this lens several times during the day, dip it in water occasionally, which will smooth it and form a new film of ice on its surface, thus keeping it up to size.—L. B. ROBBINS. Ice is as good as glass for making a burning- glass in winter Cutting Wire to Length in the Lathe HERE a great number of pieces of wire or small rod have to be cut to the same length, the work can be quickly and conveniently done in the lathe. Take a piece of brass or iron that will go into the tool-post and drill 4HnoW Use Starrett Tools HAT'S the quickest way to learn how much vital information it contains. But only constant use will teach you the full value of the STARRETT Data Book For MaAcuinisTs. Experts selected its tables and formulas to meet the requirements of practical machinists. Useless matter has been eliminated, with the result that each of its 180 pages will aid you to solve some specific problem. It is the logical sequel to the Starrett Book for Ma- chinists’ Apprentices, now in its fourth edition. 180 pages, bound tn red Athol leather. Numerous tables and diagrams. Size 4! x7. Price 75 cents. THE L. S. STARRETT CO. The World's Greatest Toolmakers Man ifacturers of Hack Saws Unexcelled ATHOL, MASS. For the Machinist Ap- rentice Vol.1 of The tarrett Books is inval- uable. It deals with how to use tools and is an instruction rather than a reference book. Dies; Their Construction and Use for the | Modern Working of Sheet Metal CONSTRUCTION OF INDUCTION COILS AND TRANSFORMERS, xy Thomas Staniey Curtis. Full of practical notes ane instruction, somes pa Bi oth the why and the how Little is left to guess work Opes closed core transformers are both take 0 up Ls wr aprn 46° ~al in- , , s : : crac tion b ok on the whole subjec st this one is ha to beat_for the By J. V. Woopwortn. The latest practice in the working struc ” ‘Ort rice, p eh os. cents of sheet metals. It shows how dies are designed, made and used. 525 illustrations, 394 pages.......... POPULAR SCIENCE MONTHLY 225 West 39th Street . Priee, $3.50 Popular Science Monthly - 225 West 39th Street, New York FACTORY GUARANTEED ALL SIZES PROMPT DELIVERY New York Polyphase Motors Direct Current Motors Single Phase Motors 2and 3 phase, A. C., 220 v. nh hy Bp D. C., shunt wound, 110-220 Single Pha A. C., 60 cycle, ie. 1750R P.M., Complete 750 R. 6 M. ' With base pulley and aaa M. with pulley ci tcesaiigg seine 1/4 asec, $28.50 \ ; 1/4 Siuchine Ment - $28-50 ua, $46.50 '/4 28 . ; 1/q HP.1%. 0». widiog $22.50 Snitable for all lighting. Battery 9 LPL. $66.50 4 ing achioe Met $28.50 | va 28 eden Vy Stn $46.50 Requirements, 1 aP-- $58 50 /2 bent a: 8v.10amo.-- $19.50 ar. $86-50 i “ae $82 50 Vp For coupe service ‘ene 954. 50 15 v., 10 amp $26.50 Sup. $98.50 50 40 v, 6 amp. - - $31.50 5 we. $116.50 2 WP. $124. 2.1? metinn ndeten $126.50 110 v, 2% amp. $31.50 10. P. Specit 3uP- - $142.5C H. P. repulsion induction 110 v, Samp. -- $52.50 tod Rating $106.50 a $218.50 with ling base ™ $146.50 ff 40, 12amp. -- $52.50 WRITE FOR CATALOG. BARGAINS IN MOTORS AND ee wih sia Soe $] 88-50 110 v, 9, amp. $67.50 40,25 amp. -- $67.50 | | V4) HP 3 P., a . Spoil Gorge Mate” - 974-00 WASHING MACHINE MOTORS 110v,18amp. $116.50 40v.,50amp. $1 16.50 eee ae co SMIPPING TERMS: S2.cre.reat.c iat tae MANUFACTURERS’ DISTRIBUTER tr, Pe $116.50 CHAS. H. JOHNSTON, Box 14, West End, Pittsburgh, Pa. MONEY BACK 125

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REGsU,LS. PAT. OFF. 4 TH & BEN 4 ro\. MI AViMG HOMEN.|U.

Corrugated Lock-Washer 6 Point Contact HE Red Devil Cor- rugated Lock Washer has six points of contact. This means that it grips the nut with three times the number of points that other lock washers do. Furthermore, 144 turns are required to loosen it, and a 3 loosen the This means 6628% greater effi- ciency. 4 turn will usual lock washer. Extreme vibration will not Red Devil Lock loosen a Washer. Made of manganese steel, oil tempered, and with a blue gun metal finish. At your dealers or from us direct Retail Price No. 103 — 30 in a bag, 3-16” to 5-8” . 15¢ No.140—40 “ “ “ “ “ (20¢ ee” Sample Assortment Smith & Hemenway Co., Inc. 264 Broadway New York City Factories, Irvington, N. J. Booklet on request Mechanics’, Electricians’ and Motorists’ Hand Tools, Pliers, Glass Cutters, Hack Saw Frames and Blades, Auger Bits, Chain Drills, etc., ete.

a hole through it lengthwise that will just allow the wire to pass through without play. Clamp it in the tool- post parallel with the bed of the lathe. Put a small faceplate on the spindle nose and bolt a piece of square steel to it, allowing the steel to project a couple of inches beyond the rim. This is the cutter. It should be bolted on at

FACE-PLATE ——7

an As the faceplate rotates, the cutter shears the wire in equal lengths an angle, as shown in the accompany- ing illustration, and not on the radius, so that it will have a shearing action. Move the wire guide up until the cutter will just clear it when the lathe turns over. Push the wire through the guide to the required distance and the cutter will shear it off as the lathe turns, which it should do at slow speed—slow enough to give time to feed the wire between cuts. A simple stop can be rigged to govern the length to be cut off.—HOWARD GREENE. One More Way of Testing Lathe Alinement GOOD test for the alinement of lathe centers may be made by the disk method. Use a perfectly flat disk of metal about \% in. thick and in the center drill a very small hole say 1/16in. Make sure that the hole is clean and that it is at right angles to the sur- face. _ Put the disk between the cen- ters and run the lathe. If thecen- ters are in line, the disk will run true. If they are out, the disk will wabble. In making this test, the centers themselves must be round and true.

TAILSTOCK If the disk wabbles the lathe-centers do not run true Economical Fuel Bricks that May Be Recharged RDINARY building-bricks pro- vide a compact and economical source of heat for cooking. Merely allow the brick to soak up kerosene and the fuel is ready for use. These fuel bricks will burn several hours, and give out a strong heat. Do not re-charge the bricks until they have become quite cold, otherwise there will be waste through evapora- tion.—GEORGE H. HOLDEN. 126

Popular Science Moniiily Soldering with the Aid of an Oil Lamp HE accompanying picture con\ oys a valuable suggestion to auto yo- bilists who often meet an emerge ney in which they have to solder ihe broken wires of their lighting or ‘nj- tion circuits. The picture shows a simple method which may be easily and quickly improvised, provided the car is equipped with an oil lamp, <uen as is used in the parking light. A baking-powder tin is ano‘her essential requirement. Cut several] V-shaped slits in the edge at the open end and punch a few holes in the s des near the closed end. With a hammer incent the top so as to form a sha ‘ow dish, large enough to hold the soider

Solder may be melted in an emergency indented bottom of a tin can which is required for the work. Light the lamp, place the tin with the solder over it and in a few minutes the solder will be melted. The wires are »o)dered by dipping the ends into the molten metal.—G. A. LU=Rs. An Emergency Repair to a Broken Pulley T is a well known fact that the in- - stant anything breaks is the time you need it most. One of our line-shaft pulleys broke suddenly and we were in a bad plight as we could not secure a pulley from any store in town, because it was 20-in. diameter, 6-in. face, and 2 15/16-in. bore. Some- thing had to be done or a machine would go out of com- mission, a line of them in fact, all driven from this line-shaft. How we got out of this diffi- culty is shown by the illustra- tion. We asked ae How a pulley was our pattern- made in an emer- makers to saw gency us twelve sec- tions as shown, each section out of 3-in. thick lumber. These were all nailed together and a belt bound around the outside of the make-shift pulley. Next we fastened two collars with a 2 15/16-in. bore on each end, then cut the right size of keyway.

Januar Equ “HI ‘| im to ben peciall Some a swin kind ' inexpt

Pop!

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it or r Popular Science Monthly es i January, 1921 Equip the Laundry-Bench with Rollers ~HE accompanying sketch shows an | improvement which may be added to benches of all kinds; but more es- pecially to benches used in the laundry. Some washing-machines do not have a swinging wringer, and a bench of this kind will save much lifting, and is so inexpensive to make, that every home This laundry-bench can be made movable or stationary, as it may be needed laundry should have one. A short pull on the rope until the knot catches in the slotted hole at the end of the bench puts the bench on rollers and a heavy load can be moved surprisingly easy. When a solid, immovable bench is desired, the rope is released, and the legs rest firmly on the floor, for the weight causes the rollers to move up, as is shown by the dotted lines. Four casters, two pairs of ordinary strap hinges, and the necessary lumber is all the material required to make one of these time- and labor-saving articles. ARTHUR M. HAHN. Put Snap-Hooks on Your Clothes-Hangers NLESS they are carefully handled and properly shaped, clothes- hangers will often become -dislodged and slip off the pole or line to which they are hooked. A snap-hook, which you can easily make from a piece of spring metal, strong enough to support | __ SPRING METAL 4 A, Snap-hooks like this make your clothes-hangers a great deal more efficient the weight of a coat or suit, will pre- vent the hanger from slipping off from its support. Take a piece of spring metal, either iron or brass, heat it to take out its temper, then bend it as shown in the accompanying illustration. Also drill a hole in the straight part which forms the base of the hook. Reheat the shaped metal and restore its springi- ness by quenching it in oil. It will then be ready to be fastened to the hanger.—H. E. MENDE. Used in U. S. Navy and - in Gov’t —™, Schools Special Offer Now— Wholesale Factory Prices! Friction Clutch Steady, '} Sure 4 Smooth Power At All Times Easy * - A f to aap We" matiBre 5 Secon Js Move to change from Lo2 Siw ¢> Tree Faller and Back Adiin Big Money With the OTTAWA Log Saw. Have plenty of fuel for yourself and to sell. Make $300 to $500 a month as others are do- ing. All done without hard work. You sit and rest while the OTTAWA does the hard work of sawing. Cuts mine props, railroad ties, fence posts, shingle timber, stave bolts and ice. When not sawing, engine runs belt machinery. Get Big Special Offer Now—Lowest Factory Price—Less than Wholesale. OTTAWA [OG SAW Cuts Down Trees—Saws Logs By Power Pulls Over 4 H-P, The New Improved — 1921 Model OTTAWA makes 310 Saw Cuts a Minute—over 5 each second. Weighs 100 pounds less than any other 4-cycle log saw built. Easiest to move and operate of all log saws, Counter Balanced Crank Shaft eliminates vibration, incr eases power and saves fuel. Direct gear drives saw; no chains to tighten; no keys; no set screws. 4-Cycle Frost-proof engine. Built-in Magneto—no batteries. Automatic Governor with Sp eed Regulator. Eccen- tric gives human rocking motion, keeping cut free from saw dust. Outfit strong but simply built. Nothing to get out of fix. A great work-saver and money-maker. Friction Clutch 'cver controlled, roller bear- ing, enables you to start and stop saw blade without stopping engine. Saves time and provides absolute safety in moving saw from log to log and from cut to cut along log! No dangerous swishing ot the saw blade in the air! Second clutch provided as a safety clutch to prevent accident if saw blade should bind. wy 30 Days’ Trial—10-Year Guarantee. Every OTTAWA shipped on Thirty Days’ Trial. Must fulfill Ten-Year OTTAWA Guarantee. For nearly 20 years we have been selling direct from factory to users. Now over 15,000 satis- fied users. Cash or Easy Payments. Get our liberal payment plans — : of purchase and find out how easy it is to own an OTTAWA Log Saw. Soon pays for itself. Any man with logs to cut cannot afford to be without this Log Saw. You can easily own it under our wonderful selling plan. Special Offer Now— Wholesale Factory Prices! To enable as many as possible to provide fuel for themselves and to sell, we are making a Special OTTAWA Buzz Saw Rig for Use in Cutting Write Offer at Wholesale Factory Prices. Send for it at once! Don't delay! Just put your name and address on coupon and you will T lay receive promptly complete information about this Big Special Offer and Very Low Introductory Price. for OTTAWA MEG. CO... 1807 Wood Street *2 Ottawa, Kansas FREE BOOK! We have prepared a 32-page book which you may have free. It illustrates in full color the OTTAWA Log Saw, FAMAIL THIS NOW Wi a “a0? 4 OTTAWA MFG. CO., 1807 Wood St., Ottawa, Kans. Send me your Free Book and Big Special Offer on 1921 Model OTTAWA Log Saw. It is understood I am under no obligations. taken from genuine photographs o and showing all details of construc- oO. tion. Be sure and_ send your e TE ln Canes ad AROS Cee ees name and address on coupon so @ Address SBEeEue eee eee aaa aeaeea that you will receive your copy promptly. 127 19> |

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Be a Trained

HE opportunities for properly trained men in the Automobile and Tractor business are _ positively unlimited. Ten million or more automobiles, trucks and tractors in use in America, and the produc- tion of several million more each year offers a future for trained men that is unparalleled in history.

If you are ambitious to get out of the rut and have a business of your own, there never was a better opportunity than right NOW in the Automobile and Tractor Busi- ness. There are thousands of excellent openings in good territory for garages, re- pair shops, and service stations. Tremendous Demand for Detroit Trained Men Ask any of our graduates, they will tell you that just as soon as they arrived home, they had more work offered them than they could handle. $5600 a month is not an unusual M.S. A.S. graduates whoarein business. Thou- sands of openings in good territory await you. Get our catalog and learn more about the won- derful opportunities for | vit trained men. profit for

today qs \ if i | i | contains

- . \ ty WED a. = ——— We 8 MADE (# AMERICA Derroir, Micu.l

USA. The Michigan State Auto School enjoys a = ry enviable reputation and is probably one of the best of its kind in the United States. Have no hesitation in recommending it in every par- ticular Yours very truly, PACKARD MOTOR CAR COMPANY catalog Send free = e w > turers Our

Man—The M. M. S. A. S. TRAINING covers every point of knowledge and practice re- quired of a successful automotive expert. We teach automobiles and tractors from A to Z. Very thorough and complete training in elec- trics. Actual experience in assembling, block testing, bearing scraping, repairing, including batteries. Tractor training, with actual field practice on M.S. A. S. tractor farm, included in complete Auto Course. Our equipment and training are positively the best obtainable. Brazing and welding and tire-repairing are also taught. The M.S. A. S. can teach you how to conduct a business of your own successfully. How to re- pair and sell cars, how to judge used car values and give you the necessary no in garage management, equipment, etc. Graduates are life members, with all service advantages free. You can return any time and ‘“‘brush up” on new equipment free of charge. OPPORTUNITIES FOR YOU Start a Garage, Repair Shop or Service Station. Little capital is required when you know your business You can sell cars, tractors and all kinds of accessories in connection Re>air and Operate Tractors. ates train and go back to the farm. work; Factory and Other Positions Open. men are also needed. Be a Saiesman. Cc omplete of the business gives M. S advantage over the o ding ury salesman. Have a Tire Repair Shop. Think of the tremendous number of tires that require repairing each day in your district. Just multiply the number of cars by four Many of our gradu Big money in this Real trained and thorough knowledge A. S. graduates a great Brazing and Welding is a good trade, too. Splendid opportunities for shops : Or Be a Lighting Plant Expert. Many positions open for service and installation experts in the farm lighting plant field LEADING MANUFAC- TURERS ENDORSE AND RECOMMEND OUR SCHOOL. They have placed their machines with us for the instruction of students. They are constantly sending us students and calling for grad- uates.

**The Detroit Auto 581 Auto Building 3729 Woodward Ave.

Tie AUTO CENTER i is the logical place seh 94% . . . De troit district automotive experts are here. MICHIGAN STATE AUTO SCHOOL logical place to LEARN the TO and TRACTOR BUSINESS. of automobiles made in greatest are world's

the

‘in the Heart of the Auto Industry ool’? — Detroit, Mich,U.S.A. 198

Popular Science Monthly

S. A. Ss. Kind MAKE $500 A MONTH AND MORE Here Are a Few Examples from Our Thousands of Successful Graduates J. S. Steckel, of Coplay, Ill.. was oon fixer < $18.00 a week. | He trained at the M. $. . and now he has a garage of his own paying a ae of, over $100 a wee . W. F. Harms, of Eldridge, Iowa, was a farm nd at $35 a. a month. ‘oday, after training at M. he has a garage business and three helpers; vet Ry Bi $500 a month. Before training, Byron Hulton at Floyd, Va., was working for $40 a month. Now he has a half interest n a garage business that pays a profit of over $1,000 a month Before training at M.S.A.S., H. A. Bradley, of Cleveland was a shipping clerk at $12.00 a week. Now he has a business of his own in Cleveland, monthly profits over $500 a month. Tony Dandrea, Austin, Pa., Now he has a garage with more handle with three men C. F. Swanson, of Sioux C.ty, Ia., was working by the day. Now his protits run $520 a month in garage and car sales. Martin Vander Bie and F. E. Michigan, M. S S. graduates, garages in Western Michigan. MONEY BACK GUARANTEE We guarantee to qualify you for a position as chauf- feur, repair man, demonstrator, auto electrician, garage man, automobile dealer, tractor mechanic and operator or farm lhghting expert, paying from $125 to $400 monthly, or refund your moncy FREE BIG 124-PAGE CATALOG Send the coupon today for big 124-page illus strated catalog and copy of latest ‘““Aute School News They tell about Courses—show more than a hundred pic- tures of equipment—give ‘etters from big Auto Fac tories and stories of success from ama and oppor- tunities for you Use coupon N< Re Send This Coupon Today MICHIGAN STATE AUTO pCmor. 581 Aute Bulsie4. 3729 Woodward Ave DE was a common laborer. business than he can Dulyea, of Holland have one of the best OIT, MICH. Gentlemen: Please send me absolutely FREE New 124-page Illustrated Catalog, also “Auto and inform course you are School News” ion as checked below. (Mark each interested in.) { | Auto and Tractor Course {| | Fire Repairing ! : Brazing snd Weiding Name. Street. City P.S.—Or bet tter still, you can expect me to look over your sctool.

Page 115

Popular Science Monthly thly Caruso immortalized A vast heritage of arts and literature has been be- queathed to the world by the passing centuries, but it remained for the Victrola to perform a similar service for music. It has bridged the oblivion into which both singer and musician passed. The voice of Jenny Lind is forever stilled, but that of Caruso will live through all the ages. The greatest artists of the present generation have recorded their art for the Victrola, and so established the enduring evidence of their greatness. There are Victrolas from $25 to $1500. New Victor Records on sale at all dealers on the Ist of each month. Victrola ae 1 REG. U.S. PAT. OFF. WN “ IS MASTERS alle E REG. U.S’ PAT OFF

Q Victor Talking Machine Co. ene at under the lid! Look on the label! Camden, New Jersey VICTOR TALKING MACHINE CO.

1

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Cypress_ Pocket. Lib brary a Cypress irc iHiletixe) Beye); (42) Working. Plans¢ Be 2 Fare*portraits of AU DUBON® £ y sr double. supplement” =o.On special supplement: Suitable for Framing i ee ~~

NEW - Vol. 42 in the Famous.

wad

Well, we suppose you’d better GET 1HAT BOY TO WRITE right away for this veryspecial Vol. 4 “Good Bungalows for Good Birds.” It is a wonderful compila- tion of bird lore and bird information. BIG DOUBLE SUPPLEMENT WITH 20 BEAUTIFUL AND COR- RECT DESIGNS— all spe- cially made by artists who know birds. (Not oneis like the other good designs in bird house catalogs.) Also in this volume you will find 20 FULL WORKING PLANS with Complete Specifications. And ALSO EXTRA ART SUPPLEMENT, 12 x 29 inches, in FIVE COLORS with a total of 3 PORTRAITS OF AUDUBON SUITABLE FOR FRAMING, two of them being re- productions in 5colors of 2 rare old steel engravings, also photograph of his home and of the Statue to his memory. ALSO 5 BIRDS in NATURAL COLORS and 180 correct pen portraits of other birds—with calls.

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Popular Science Monthly

Popular Science Monthly FEB., 1921 | Volume pees | — ———— Ea BRSISMECR O Important to Readers Owing to the paper short- age, the number of printed copies of POPULAR SCIENCE MONTHLY is limited. To insure getting your maga- zine regularly, you should place a standing order with your newsdealer, or send us your yearly subscription RSS Garr

of $3.00. | AERONAUTICS | The Wind-Tunnel at St. Cyr................. 24 Stronger Airplane Propellers................ 26 New Wings for the Airplane.............. 29 A Wild Air Ride Through Omaha........ 36 Landmarks for the Aviator.............. 37 eee ee reer eer Teer . 43 How We Look from Sustes Roky a Manns ietetce es . 55 Planes that Went to Alaska............. 58 In a Glass Case for Six <0 5 eee 65

| This Big Pipe Regulates the Flow

The Smallest One-Man Airplane HOUSEKEEPING MADE EASY A Japanese Hat fer a Lamp-Shade. . 43 A Quarter’s Worth: of Electricity... . 43 Typewriter Lamp Made from Reuiiessions Shaft 55 Saving Coal with u Flower-Pot. _ 55 An Electric Decorative Table Fountain... . 56 Daffodils Make Pretty Candlesticks........ 56 A Concrete Garbage-Furnace......... 57 Fish-Nets for Active Babies......... : 58 Use Old Automobile Cushions... : , 58 Scrubbing Floors Electrically........... -» 62 Hooks to Hang Pictures Straight. . Ss0 66 | It Will Keep Doors from Banging............ 66 The Old Horn asa Funnel................ 70 It’s Tea-Ball and Teapot Too................ 71 Push the Bed into the Wall........ 83 INDUSTRIAL PROGRESS Cameras and Divers to Restore Coal-Mines 23 An Electric Sawmill on Wheels 26 Edison Talks on Super-Labor-Saving Machines 3}! A Paper Suit for One Dollar ..... Pee is: oe Electric Lights in the Desert... . . 36 Making Use of the Smoke of W alent Shells. as ae Bracing the Riveter = Sk Ce Ee ee “ay ee <meta “a ~ a (Continucd on page 4)

Copyright, 1921, by the Modern Publishing Compan) POPULAR SCIENCE MONTHLY is issued month! ye Yearly subscription in the United States, ~ Canada, $3.50. Foreign, $4.00. Single copy, 25 cent Advertising rates on application. twentieth of the second publication. 28, 1915, at the Post Office at New York under act of March 3, 1879. Entered as second-class mat- ter at the Post Office Department, Canada. The contents of this magazine are copyrigh i and must not be reprinted without permiss H, J. Fisher, President; R. C. Wilson, Vice-Preside O. B. Capen, Secretary and Treasurer. Modern Publishing Company 225 West Thirty-ninth St. New York Cicy Forms close the month preceding date ol Entered as second-class matter Dec. “HE ele to the e! As men resistan the pas: Dr. A physiol versity aiple il measur should

Popular Science Monthy Febru